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Sample records for alloy-co36cr22ni22w15fe3

  1. Low-cost, high-strength Fe--Ni--Cr alloys for high temperature exhaust valve application

    Science.gov (United States)

    Muralidharan, Govindarajan

    2017-09-05

    An Fe--Ni--Cr alloy is composed essentially of, in terms of wt. %: 2.4 to 3.7 Al, up to 1.05 Co, 14.8 to 15.9 Cr, 25 to 36 Fe, up to 1.2 Hf, up to 4 Mn, up to 0.6 Mo, up to 2.2 Nb, up to 1.05 Ta, 1.9 to 3.6 Ti, up to 0.08 W, up to 0.03 Zr, 0.18 to 0.27 C, up to 0.0015 N, balance Ni, wherein, in terms of atomic percent: 8.5.ltoreq.Al+Ti+Zr+Hf+Ta.ltoreq.11.5, 0.53.ltoreq.Al/(Al+Ti+Zr+Hf+Ta).ltoreq.0.65, and 0.16.ltoreq.Cr/(Fe+Ni+Cr+Mn).ltoreq.0.21, the alloy being essentially free of Cu, Si, and V.

  2. Interdiffusion between Co3O4 coating and the oxide scale of Fe-22Cr alloy

    DEFF Research Database (Denmark)

    Hansson, Anette Nørgaard; Friehling, Peter B.; Linderoth, Søren

    2002-01-01

    on Fe-Cr alloys. Coatings of Co3O4 were deposited on a Fe-22Cr alloy by plasma spraying and spray-painting. As-deposited samples were oxidised in air containing 1% H2O at 900C for various exposure time. During exposure the Fe-22Cr alloy forms an oxide scale, which reacts with the coating. The effects...

  3. Alloying effect on hardening of martensite stainless steels of the Fe-Cr-Ni and Fe-Cr-Co systems

    International Nuclear Information System (INIS)

    Fel'dgandler, Eh.G.; Savkina, L.Ya.

    1975-01-01

    The effect of alloying elements is considered on the γ → a-transformation and hardening of certain compositions of the ternary Fe-Cr-Ni- and Fe-Cr-Co alloy systems with the martensite structure. In martensite Fe-(10 to 14)% Cr base steels the elements Co, Cu, W, Ni, Mo, Si, Cr decrease, Mn, Si, Mo, Cu increase, and Cr, Ni, Co decrease the temperature of α → γ-transition. The tempering of martensite steels of the Fe-Cr-Ni- and Fe-Cr-Co-systems containing 10 to 14% Cr, 4 to 9% Ni, and 7 to 12% Co does not lead to hardening. Alloyage of the martensite Fe-Cr-Ni-, Fe-Cr-Co- and Fe-Cr-Ni-Co base separately with Mo, W, Si or Cu leads to a hardening during tempering, the hardening being the higher, the higher is the content of Ni and, especially, of Co. The increase in the content of Mo or Si produces the same effect as the increase in the Co content. In on Fe-Cr-Co or Fe-Cr-Ni-Co based steels alloyed with Mo or Si, two temperature ranges of ageing have been revealed which, evidently, have different hardening natures. The compositions studied could serve as the base material for producing maraging stainless steels having a complex variety of properties

  4. Effects of environment on the release of Ni, Cr, Fe, and Co from new and recast Ni-Cr alloy.

    Science.gov (United States)

    Oyar, Perihan; Can, Gülşen; Atakol, Orhan

    2014-07-01

    The addition of previously cast alloy to new alloy for economic reasons may increase the release of elements. The purpose of this study was to analyze the effects of the immersion period, immersion media, and addition of previously cast alloy to new alloy on the release of elements. Disk-shaped specimens were prepared from a Ni-Cr alloy (Ni: 61 wt%, Cr: 26 wt%, Mo: 11 wt%, Si: 1.5 wt%, Fe, Ce, Al, and Co alloy (group N) and 50% new/50% recast alloy (group R). After the immersion of the specimens in both NaCl (pH 4) and artificial saliva (pH 6.7) for 3, 7, 14, 30, and 60 days, the release of ions was determined by using atomic absorption spectrometry. Data were analyzed with a 3-way ANOVA (α=.001). The release of Ni was significantly affected by the immersion period, of Ni and Cr by the alloy and media (Palloy (Palloy in artificial saliva was 109.71 for Ni, 6.49 for Cr, 223.22 for Fe, and 29.90 μg/L for Co. The release of Co in NaCl was below the detection limit in both groups. The release of Ni in NaCl and artificial saliva increased with the length of the immersion period in both groups. The release of Cr and Fe was higher in artificial saliva than in NaCl in group R, regardless of the immersion period. The release of Co in NaCl was below the detection limit in both groups. Copyright © 2014 The Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  5. On the Path to Optimizing the Al-Co-Cr-Cu-Fe-Ni-Ti High Entropy Alloy Family for High Temperature Applications

    Directory of Open Access Journals (Sweden)

    Anna M. Manzoni

    2016-03-01

    Full Text Available The most commonly investigated high entropy alloy, AlCoCrCuFeNi, has been chosen for optimization of its microstructural and mechanical properties by means of compositional changes and heat treatments. Among the different available optimization paths, the decrease of segregating element Cu, the increase of oxidation protective elements Al and Cr and the approach towards a γ-γ′ microstructure like in Ni-based superalloys have been probed and compared. Microscopical observations have been made for every optimization step. Vickers microhardness measurements and/or tensile/compression test have been carried out when the alloy was appropriate. Five derived alloys AlCoCrFeNi, Al23Co15Cr23Cu8Fe15Ni16, Al8Co17Cr17Cu8Fe17Ni33, Al8Co17Cr14Cu8Fe17Ni34.8Mo0.1Ti1W0.1 and Al10Co25Cr8Fe15Ni36Ti6 (all at.% have been compared to the original AlCoCrCuFeNi and the most promising one has been selected for further investigation.

  6. Alloying behavior, microstructure and mechanical properties in a FeNiCrCo0.3Al0.7 high entropy alloy

    International Nuclear Information System (INIS)

    Chen, Weiping; Fu, Zhiqiang; Fang, Sicong; Xiao, Huaqiang; Zhu, Dezhi

    2013-01-01

    Highlights: • FeNiCrCo 0.3 Al 0.7 high entropy alloy is prepared via MA and SPS. • Two BCC phases and one FCC phase were obtained after SPS. • The two BCC phases are enriched in Fe–Cr (A2 structure) and enriched in Ni–Al (B2 structure). • Bulk FeNiCrCo 0.3 Al 0.7 HEA exhibits excellent mechanical properties. - Abstract: The present paper reports the synthesis of FeNiCrCo 0.3 Al 0.7 high entropy alloy (HEA) by mechanical alloying (MA) and spark plasma sintering (SPS) process. Alloying behavior, microstructure, mechanical properties and detailed phases of the alloy were investigated systematically. During MA, the formation of a supersaturated solid solution with body-centered cubic (BCC) structure occurred. However, partial BCC structure phase transformed into a face-center cubic (FCC) structure phase during SPS. Two BCC phases with nearly the same lattice parameter of 3.01 Å and one FCC phase with the lattice parameter of 3.72 Å were characterized in the transmission electron microscope (TEM) images. The two BCC phases which are evidently deviated from the definition of high entropy alloys (HEAs) are enriched in Fe–Cr and enriched in Ni–Al, respectively. Moreover, the FCC phase agrees well with the definition of HEAs. Bulk FeNiCrCo 0.3 Al 0.7 alloy with little porosity exhibits much better mechanical properties except compression ratio compared with other typical HEAs of FeNiCrCoAl HEA system. The yield strength, compressive strength, compression ratio and Vickers hardness of FeNiCrCo 0.3 Al 0.7 alloy are 2033 ± 41 MPa, 2635 ± 55 MPa, 8.12 ± 0.51% and 624 ± 26H v , respectively. The fracture mechanism of bulk FeNiCrCo 0.3 Al 0.7 alloy is dominated by intercrystalline fracture and quasi-cleavage fracture

  7. Permeability and giant magnetoimpedance in Co69Fe4.5X1.5Si10B15 (X=Cr, Mn, Ni) amorphous ribbons

    International Nuclear Information System (INIS)

    Byon, Kwang Seok; Yu, Seong-Cho; Kim, Cheol Gi

    2001-01-01

    The magnetoimpedance (MI) has been measured in the amorphous ribbons of the soft ferromagnetic alloy Co 69 Fe 4.5 X 1.5 Si 10 B 15 (X=Cr, Mn, Ni) as functions of frequency (f). For all of the three samples, at low frequency, f≤5MHz, the MI ratio increases with increasing frequency, but the MI ratio decreases at high frequency, f≥5MHz. The MI profiles are not changed at low frequency regions of f≤1MHz in the amorphous ribbons. The MI ratio at high frequency of f=5MHz becomes 57% in Co 69 Fe 4.5 Cr 1.5 Si 10 B 15 , but the MI ratio becomes 30% in Co 69 Fe 4.5 Mn 1.5 Si 10 B 15 and Co 69 Fe 4.5 Ni 1.5 Si 10 B 15 . The MI ratio at f=10MHz becomes 45% in Co 69 Fe 4.5 Cr 1.5 Si 10 B 15 and the MI ratio becomes 23% in Co 69 Fe 4.5 Mn 1.5 Si 10 B 15 and Co 69 Fe 4.5 Ni 1.5 Si 10 B 15 , respectively. The maximum values of field sensitivity are 2.7(X=Cr), 2.5(X=Mn), 2.2(X=Ni)%/Oe for f=5MHz. [copyright] 2001 American Institute of Physics

  8. The Microstructures and Electrical Resistivity of (Al, Cr, TiFeCoNiOx High-Entropy Alloy Oxide Thin Films

    Directory of Open Access Journals (Sweden)

    Chun-Huei Tsau

    2015-01-01

    Full Text Available The (Al, Cr, TiFeCoNi alloy thin films were deposited by PVD and using the equimolar targets with same compositions from the concept of high-entropy alloys. The thin films became metal oxide films after annealing at vacuum furnace for a period; and the resistivity of these thin films decreased sharply. After optimum annealing treatment, the lowest resistivity of the FeCoNiOx, CrFeCoNiOx, AlFeCoNiOx, and TiFeCoNiOx films was 22, 42, 18, and 35 μΩ-cm, respectively. This value is close to that of most of the metallic alloys. This phenomenon was caused by delaminating of the alloy oxide thin films because the oxidation was from the surfaces of the thin films. The low resistivity of these oxide films was contributed to the nonfully oxidized elements in the bottom layers and also vanishing of the defects during annealing.

  9. A study of corrosion behavior of Ni-22Cr-13Mo-3W alloy under hygroscopic salt deposits on hot surface

    International Nuclear Information System (INIS)

    Badwe, Sunil; Raja, K.S.; Misra, M.

    2006-01-01

    Alloy 22, a nickel base Ni-22Cr-13Mo-3W alloy has an excellent corrosion resistance in oxidizing and reducing environments. Most of the corrosion studies on Alloy 22 have been conducted using conventional chemical or electrochemical methods. In the present investigation, the specimen was directly heated instead of heating the electrolyte, thereby simulating the nuclear waste package container temperature profile. Corrosion behavior of Alloy 22 and evaporation conditions of water diffusing on the container were evaluated using the newly devised heated electrode corrosion test (HECT) method in simulated acidified water (SAW) and simulated concentrated water (SCW) environments. In this method, the concentration of the environment varied with test duration. The corrosion rate of Alloy 22 was not affected by the continuous increase in ionic strength of the SAW (pH 3) environment. Passivation kinetics was faster with increase in concentration of the electrolytes. The major difference between the conventional test and HECT was the aging characteristics of the passive film of Alloy 22. The heated electrode corrosion test can be used for evaluating materials for construction of heat transfer equipments such as evaporators

  10. Analysis of Microstructure and Sliding Wear Behavior of Co1.5CrFeNi1.5Ti0.5 High-Entropy Alloy

    Science.gov (United States)

    Lentzaris, K.; Poulia, A.; Georgatis, E.; Lekatou, A. G.; Karantzalis, A. E.

    2018-04-01

    Α Co1.5CrFeNi1.5Ti0.5 high-entropy alloy (HEA) of the well-known family of CoCrFeNiTi has been designed using empirical parameters. The aim of this design was the production of a HEA with fcc structure that gives ductile behavior and also high strength because of the solid solution effect. The VEC calculations (8.1) supported the fcc structure while the δ factor calculations (4.97) not being out of the limit values, advised a significant lattice distortion. From the other hand, the ΔΗ mix calculations (- 9.64 kJ/mol) gave strong indications that no intermetallic would be formed. In order to investigate its potential application, the Co1.5CrFeNi1.5Ti0.5 HEA was prepared by vacuum arc melting and a primary assessment of its surface degradation response was conducted by means of sliding wear testing using different counterbody systems for a total sliding distance of 1000 m. An effort to correlate the alloy's wear response with the microstructural characteristics was attempted. Finally, the wear behavior of the Co1.5CrFeNi1.5Ti0.5 HEA was compared with that of two commercially used wear-resistant alloys. The results obtained provided some first signs of the high-entropy alloys' better wear performance when tested under sliding conditions against a steel ball.

  11. Microstructure evolution during the precipitation and growth of fully coherent DO{sub 22} superlattice in an Ni-Cr-W alloy

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Xiangyu [Stake Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi' an 710072 (China); Hu, Rui, E-mail: rhu@nwpu.edu.cn [Stake Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi' an 710072 (China); Li, Xiaolin [Stake Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819 (China); Luo, Gongliao [Stake Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi' an 710072 (China)

    2016-08-15

    The ordering transformation occurring in a model Ni-Cr-W superalloy during prolonged exposure to proper temperature has been investigated systematically. It is demonstrated that nanometer-sized precipitates with a DO{sub 22} structure can precipitate in the Ni-Cr-W alloy by means of simple aging treatment at 650–700 °C. The mechanism of transformation to DO{sub 22} superlattice has been determined to be continuous ordering based on the results of high resolution transmission electron microscopy investigation and variation trend in Vickers microhardness. Different variants of DO{sub 22} phase can coexist in the matrix with no signs of overaging as aging time increases, indicating it has a high thermal stability. The precipitates of DO{sub 22} superlattice has been found to be of ellipsoidal shape which results in the greatest reduction of strain energy. The interfaces between DO{sub 22} precipitates and matrix have been revealed to be coherent at the atomic scale, resulting in considerable coherency strain attributing to the lattice misfit between DO{sub 22} particle and matrix. Because of the high-density nanometer-sized DO{sub 22} phase, the microhardness of the alloy has been improved remarkably after aging treatment. - Graphical abstract: Different variants of the DO{sub 22} superlattice can coexist in the matrix, and the interface between precipitate and the matrix remain coherence at the atomic scale. The three dimensional form of the DO{sub 22} precipitates constructed from three mutually perpendicular projections is an ellipsoidal stick, and the directions of elongations are along the longest axis of the unit cell for DO{sub 22} phase. - Highlights: •The DO{sub 22} phase precipitated in the Ni-Cr-W alloy has a high thermal stability. •The morphology of DO{sub 22} superlattice has been determined to be ellipsoid. •The interface between DO{sub 22} phase and matrix are fully coherent at the atomic scale. •Different variants of DO{sub 22} phase occur

  12. Densities of molten Ni-(Cr, Co, W) superalloys

    Institute of Scientific and Technical Information of China (English)

    XIAO Feng; YANG Ren-hui; FANG Liang; LIU Lan-xiao; ZHAO Hong-kai

    2008-01-01

    In order to obtain more accurate density for molten Ni-(Cr, Co, W) binary alloy, the densities of molten pure Ni and Ni-Cr, Ni-Co, Ni-W alloys were measured with a sessile drop method. It is found that the measured densities of molten pure Ni and Ni-Cr, Ni-Co, Ni-W alloys decrease with increasing temperature in the experimental temperature range. The density of alloys increases with increasing W and Co concentrations while it decreases with increasing Cr concentration in the alloy at 1 773-1 873 K. The molar volume of Ni-based alloys increases with increasing W concentration while it decreases with increasing Co concentration. The effect of Cr concentration on the molar volume of the alloy is little in the studied concentration range. The accommodation among atomic species was analyzed. The deviation of molar volume from ideal mixing shows an ideal mixing of Ni-(Cr, Co, W) binary alloys.

  13. Microstructure and corrosion properties of CrMnFeCoNi high entropy alloy coating

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Qingfeng [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai, 200240 (China); Feng, Kai, E-mail: fengkai@sjtu.edu.cn [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai, 200240 (China); Li, Zhuguo, E-mail: lizg@sjtu.edu.cn [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai, 200240 (China); Lu, Fenggui [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai, 200240 (China); Li, Ruifeng [School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, 212003 (China); Huang, Jian; Wu, Yixiong [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai, 200240 (China)

    2017-02-28

    Highlights: • Equimolar CrMnFeCoNi high entropy alloy coating are prepared by laser cladding. • The cladding layer forms a simple FCC phase solid solution with identical dendritic structure. • The cladding layer exhibits a noble corrosion resistance in both 3.5 wt.% NaCl and 0.5 M sulfuric acid. • Element segregation makes Cr-depleted interdendrites the starting point of corrosion reaction. - Abstract: Equimolar CrMnFeCoNi high entropy alloy (HEA) is one of the most notable single phase multi-component alloys up-to-date with promising mechanical properties at cryogenic temperatures. However, the study on the corrosion behavior of CrMnFeCoNi HEA coating has still been lacking. In this paper, HEA coating with a nominal composition of CrMnFeCoNi is fabricated by laser surface alloying and studied in detail. Microstructure and chemical composition are determined by X-ray diffraction (XRD), optical microscope (OM), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) are used to investigate the corrosion behavior. The coating forms a simple FCC phase with an identical dendritic structure composed of Fe/Co/Ni-rich dendrites and Mn/Ni-rich interdendrites. Both in 3.5 wt.% NaCl solution and 0.5 M sulfuric acid the coating exhibits nobler corrosion resistance than A36 steel substrate and even lower i{sub corr} than 304 stainless steel (304SS). EIS plots coupled with fitted parameters reveal that a spontaneous protective film is formed and developed during immersion in 0.5 M sulfuric acid. The fitted R{sub t} value reaches its maximum at 24 h during a 48 h’ immersion test, indicating the passive film starts to break down after that. EDS analysis conducted on a corroded surface immersed in 0.5 M H{sub 2}SO{sub 4} reveals that corrosion starts from Cr-depleted interdendrites.

  14. Phase separation in equiatomic AlCoCrFeNi high-entropy alloy

    Energy Technology Data Exchange (ETDEWEB)

    Manzoni, A., E-mail: anna.manzoni@helmholtz-berlin.de [Helmholtz-Zentrum Berlin, Institute of Applied Materials, D-14109 Berlin (Germany); Daoud, H.; Völkl, R.; Glatzel, U. [Metals and Alloys, University Bayreuth, Ludwig-Thoma-Strasse 36b, D-95447 Bayreuth (Germany); Wanderka, N. [Helmholtz-Zentrum Berlin, Institute of Applied Materials, D-14109 Berlin (Germany)

    2013-09-15

    The microstructure of the as-cast AlCoCrFeNi high entropy alloy has been investigated by transmission electron microscopy and atom probe tomography. The alloy shows a very pronounced microstructure with clearly distinguishable dendrites and interdendrites. In both regions a separation into an Al–Ni rich matrix and Cr–Fe-rich precipitates can be observed. Moreover, fluctuations of single elements within the Cr–Fe rich phase have been singled out by three dimensional atom probe measurements. The results of investigations are discussed in terms of spinodal decomposition of the alloying elements inside the Cr–Fe-rich precipitates. - Highlights: ► The Alloy separates into an Al–Ni rich matrix and Cr–Fe-rich precipitates. ► Concentration depth profiles in the Cr–Fe rich regions show opposite fluctuations. ► They have been attributed to the spinodal decomposition of Fe- and Cr-rich phases. ► The Al–Ni rich region corresponds well to the Al–Ni rich phases observed in the 6 component AlCoCrCuFeNi alloy.

  15. Applicability of the θ projection method to creep curves of Ni-22Cr-18Fe-9Mo alloy

    International Nuclear Information System (INIS)

    Kurata, Yuji; Utsumi, Hirokazu

    1998-01-01

    Applicability of the θ projection method has been examined for constant-load creep test results at 800 and 1000degC on Ni-22Cr-18Fe-9Mo alloy in the solution-treated and aged conditions. The results obtained are as follows: (1) Normal type creep curves obtained at 1000degC for aged Ni-22Cr-18Fe-9Mo alloy are fitted using the θ projection method with four θ parameters. Stress dependence of θ parameters can be expressed in terms of simple equations. (2) The θ projection method with four θ parameters cannot be applied to the remaining creep curves where most of the life is occupied by a tertiary creep stage. Therefore, the θ projection method consisting of only the tertiary creep component with two θ parameters was applied. The creep curves can be fitted using this method. (3) If the θ projection method with four θ or two θ parameters is applied to creep curves in accordance with creep curve shapes, creep rupture time can be predicted in terms of formulation of stress and/or temperature dependence of θ parameters. (author)

  16. High-Temperature Tensile Strength of Al10Co25Cr8Fe15Ni36Ti6 Compositionally Complex Alloy (High-Entropy Alloy)

    Science.gov (United States)

    Daoud, H. M.; Manzoni, A. M.; Wanderka, N.; Glatzel, U.

    2015-06-01

    Homogenizing at 1220°C for 20 h and subsequent aging at 900°C for 5 h and 50 h of a novel Al10Co25Cr8Fe15Ni36Ti6 compositionally complex alloy (high-entropy alloy) produces a microstructure consisting of an L12 ordered γ' phase embedded in a face-centered cubic solid-solution γ matrix together with needle-like B2 precipitates (NiAl). The volume fraction of γ' phase is ~46% and of needle-like B2 precipitates database; Thermo-Calc Software, Stockholm, Sweden). The high-temperature tensile tests were carried out at room temperature, 600°C, 700°C, 800°C, and 1000°C. The tensile strength as well as the elongation to failure of both heat-treated specimens is very high at all tested temperatures. The values of tensile strength has been compared with literature data of well-known Alloy 800H and Inconel 617, and is discussed in terms of the observed microstructure.

  17. Effect of Molybdenum on the Corrosion Behavior of High-Entropy Alloys CoCrFeNi2 and CoCrFeNi2Mo0.25 under Sodium Chloride Aqueous Conditions

    Directory of Open Access Journals (Sweden)

    Alvaro A. Rodriguez

    2018-01-01

    Full Text Available The corrosion behavior of high-entropy alloys (HEAs CoCrFeNi2 and CoCrFeNi2Mo0.25 was investigated in 3.5 wt. percent sodium chloride (NaCl at 25°C by electrochemical methods. Their corrosion parameters were compared to those of HASTELLOY® C-276 (UNS N10276 and stainless steel 316L (UNS 31600 to assess the suitability of HEAs for potential industrial applications in NaCl simulating seawater type environments. The corrosion rates were calculated using corrosion current determined from electrochemical experiments for each of the alloys. In addition, potentiodynamic polarization measurements can indicate active, passive, and transpassive behavior of the metal as well as potential susceptibility to pitting corrosion. Cyclic voltammetry (CV can confirm the alloy susceptibility to pitting corrosion. Electrochemical impedance spectroscopy (EIS elucidates the corrosion mechanism under studied conditions. The results of the electrochemical experiments and scanning electron microscopy (SEM analyses of the corroded surfaces revealed general corrosion on alloy CoCrFeNi2Mo0.25 and HASTELLOY C-276 and pitting corrosion on alloy CoCrFeNi2 and stainless steel 316L.

  18. The effect of molybdenum on the corrosion behaviour of the high-entropy alloys Co1.5CrFeNi1.5Ti0.5Mox in aqueous environments

    International Nuclear Information System (INIS)

    Chou, Y.L.; Yeh, J.W.; Shih, H.C.

    2010-01-01

    The purpose of this study is to investigate the electrochemical properties of the Co 1.5 CrFeNi 1.5 Ti 0.5 Mo x high-entropy alloys in three aqueous environments which simulate acidic, marine, and basic environments at ambient temperature (∼25 o C). The potentiodynamic polarisation curves of the Co 1.5 CrFeNi 1.5 Ti 0.5 Mo x alloys, obtained in aqueous solutions of H 2 SO 4 and NaOH, clearly revealed that the corrosion resistance of the Mo-free alloy was superior to that of the Mo-containing alloys. On the other hand, the lack of hysteresis in cyclic polarisation tests and SEM micrographs confirmed that the Mo-containing alloys are not susceptible to pitting corrosion in NaCl solution.

  19. Fe-Cr-Ni system alloys

    International Nuclear Information System (INIS)

    Levin, F.L.

    1986-01-01

    Phase diagram of Fe-Cr-Ni system, which is the basic one for production of corrosion resistant alloys, is considered. Data on corrosion resistance of such alloys are correlated depending on a number of factors: quality and composition of modifying elements, corrosion medium, temperature, alloy structure, mechanical and thermal treatment. Grades of Fe-Ni-Cr alloys are presented, and fields of their application are pointed out

  20. Design and characterization of FeCrNiCoAlCu and FeCrNiCo(AlCu){sub 0,5} multicomponent alloys; Previsao e caracterizacao de ligas multicomponentes FeCrNiCoAlCu e FeCrNiCo(AlCu){sub 0,5}

    Energy Technology Data Exchange (ETDEWEB)

    Triveno Rios, Carlos; Artacho, Victor Falcao [Universidade Federal do ABC (CECS/UFABC), Santo Andre, SP (Brazil). Engenharia de Materiais

    2014-07-01

    High entropy alloys using multi-element main quasi-equivalent atomic proportions and generally forms single-phase solid solution and has the ability to enhance levels of strain hardening combined with high levels of plastic deformation at room temperature. In this work two high-entropy alloys with almost similar composition were studied and the factors influencing the formation of solid solution phases (δ atomic radius difference, ΔH{sub mix} mixing enthalpy, ΔS{sub mix} mixing entropy) were evaluated. The microstructure as-cast and the compositions of phases in the two alloys were analyzed by SEM and XRD. The mechanical characterization was realized by measurements of microhardness and cold compression test. The results showed that FeCrNiCo(AlCu){sub 0,5} and FeCrNiCoAlCu alloys with δ equal to 5,7 and 4,9, respectively, form alloys with solid solutions of high entropy. However, the presence of FC and BCCC structures greatly influence the mechanical properties. (author)

  1. Room-temperature ferromagnetic transitions and the temperature dependence of magnetic behaviors in FeCoNiCr-based high-entropy alloys

    Science.gov (United States)

    Na, Suok-Min; Yoo, Jin-Hyeong; Lambert, Paul K.; Jones, Nicholas J.

    2018-05-01

    High-entropy alloys (HEAs) containing multiple principle alloying elements exhibit unique properties so they are currently receiving great attention for developing innovative alloy designs. In FeCoNi-based HEAs, magnetic behaviors strongly depend on the addition of alloying elements, usually accompanied by structural changes. In this work, the effect of non-magnetic components on the ferromagnetic transition and magnetic behaviors in equiatomic FeCoNiCrX (X=Al, Ga, Mn and Sn) HEAs was investigated. Alloy ingots of nominal compositions of HEAs were prepared by arc melting and the button ingots were cut into discs for magnetic measurements as functions of magnetic field and temperature. The HEAs of FeCoNiCrMn and FeCoNiCrSn show typical paramagnetic behaviors, composed of solid solution FCC matrix, while the additions of Ga and Al in FeCoNiCr exhibit ferromagnetic behaviors, along with the coexistence of FCC and BCC phases due to spinodal decomposition. The partial phase transition in both HEAs with the additions of Ga and Al would enhance ferromagnetic properties due to the addition of the BCC phase. The saturation magnetization for the base alloy FeCoNiCr is 0.5 emu/g at the applied field of 20 kOe (TC = 104 K). For the HEAs of FeCoNiCrGa and FeCoNiCrAl, the saturation magnetization significantly increased to 38 emu/g (TC = 703 K) and 25 emu/g (TC = 277 K), respectively. To evaluate the possibility of solid solution FCC and BCC phases in FeCoNiCr-type HEAs, we introduced a parameter of valence electron concentration (VEC). The proposed rule for solid solution formation by the VEC was matched with FeCoNiCr-type HEAs.

  2. Synthesis and Characterization of High-Entropy Alloy AlFeCoNiCuCr by Laser Cladding

    Directory of Open Access Journals (Sweden)

    Xiaoyang Ye

    2011-01-01

    Full Text Available High-entropy alloys have been recently found to have novel microstructures and unique properties. In this study, a novel AlFeCoNiCuCr high-entropy alloy was prepared by laser cladding. The microstructure, chemical composition, and constituent phases of the synthesized alloy were characterized by SEM, EDS, XRD, and TEM, respectively. High-temperature hardness was also evaluated. Experimental results demonstrate that the AlFeCoNiCuCr clad layer is composed of only BCC and FCC phases. The clad layers exhibit higher hardness at higher Al atomic content. The AlFeCoNiCuCr clad layer exhibits increased hardness at temperature between 400–700°C.

  3. Effect of Ti content on structure and properties of Al2CrFeNiCoCuTix high-entropy alloy coatings

    International Nuclear Information System (INIS)

    Qiu, X.W.; Zhang, Y.P.; Liu, C.G.

    2014-01-01

    Highlights: • Al 2 CrFeNiCoCuTi x high-entropy alloy coatings were prepared by laser cladding. • Al 2 CrFeNiCoCuTi x coatings show excellent corrosion resistance and wear resistance. • Al 2 CrFeNiCoCuTi x coatings play a good protective effect on Q235 steel. • Ti element promotes the formation of a BCC structure in a certain extent. -- Abstract: The Al 2 CrFeNiCoCuTi x high-entropy alloy coatings were prepared by laser cladding. The structure, hardness, corrosion resistance, wear resistance and magnetic property were studied by metallurgical microscope, scanning electron microscopy with spectroscopy (SEM/EDS), X-ray diffraction, micro/Vickers hardness tester, electrochemical workstation tribometer and multi-physical tester. The result shows that, Al 2 CrFeNiCoCuTi x high-entropy alloy samples consist of the cladding zone, bounding zone, heat affected zone and substrate zone. The bonding between the cladding layer and the substrate of a good combination; the cladding zone is composed mainly of equiaxed grains and columnar crystal; the phase structure of Al 2 CrFeNiCoCuTi x high-entropy alloy coatings simple for FCC, BCC and Laves phase due to high-entropy affect. Ti element promotes the formation of a BCC structure in a certain extent. Compared with Q235 steel, the free-corrosion current density of Al 2 CrFeNiCoCuTi x high-entropy alloy coatings is reduced by 1–2 orders of magnitude, the free-corrosion potential is more “positive”. With the increasing of Ti content, the corrosion resistance of Al 2 CrFeCoCuNiTi x high-entropy alloy coatings enhanced in 0.5 mol/L HNO 3 solution. Compared with Q235 steel, the relative wear resistance of Al 2 CrFeCoCuNiTi x high-entropy alloy coatings has improved greatly; both the hardness and plasticity are affecting wear resistance. Magnetization loop shows that, Ti 0.0 high-entropy alloy is a kind of soft magnetic materials

  4. Effect of d electrons on defect properties in equiatomic NiCoCr and NiCoFeCr concentrated solid solution alloys

    Science.gov (United States)

    Zhao, Shijun; Egami, Takeshi; Stocks, G. Malcolm; Zhang, Yanwen

    2018-01-01

    The role of d electrons in determining distributions of formation and migration energies for point defects in equiatomic NiCoCr and NiCoFeCr concentrated solid solution alloys (CSAs) are studied regarding electron density deformation flexibility based on first-principles calculations. The disordered state is taken into account by constructing special quasirandom structures. The migration barriers are determined by directly optimizing the saddle point. It is found that the formation energies of interstitials in CSAs are lower than those in pure Ni, whereas the formation energies of vacancies are higher. In both NiCoCr and NiCoFeCr, Co-related dumbbell interstitials exhibit lower formation energies. Notably, the distributions of migration energies for Cr interstitials and vacancies exhibit a remarkable overlap region. A detailed analysis of electronic properties reveals that the electronic charge deformation flexibility regarding eg to t2g transition has a dominant effect on defect energetics for different elements in CSAs. Thus the electron deformation ability is suggested as a key factor in understanding the peculiar defect behavior in CSAs.

  5. Mechanical properties of Fe-Ni-Cr-Si-B bulk glassy alloy

    International Nuclear Information System (INIS)

    Lee, Kee Ahn; Kim, Yong Chan; Kim, Jung Han; Lee, Chong Soo; Namkung, Jung; Kim, Moon Chul

    2007-01-01

    The mechanical properties and crystallization behavior of new Fe-Ni-Cr-Si-B-based bulk glassy alloys were investigated. The suitability of the continuous roll casting method for the production of bulk metallic glass (BMG) sheets in such alloy systems was also examined. BMG samples (Fe-Ni-Cr-Si-B, Fe-Ni-Zr-Cr-Si-B, Fe-Ni-Zr-Cr-W-Si-B) in amorphous strip, cylindrical, and sheet forms were prepared through melt spinning, copper mold casting, and twin roll strip casting, respectively. Fe-Ni-Cr-Si-B alloy exhibited compressive strength of up to 2.93 GPa and plastic strain of about 1.51%. On the other hand, the Fe-Ni-Zr-Cr-Si-B, composite-type bulk sample with diameter of 2.0 mm showed remarkable compressive plastic strain of about 4.03%. The addition of zirconium was found to enhance the homogeneous precipitation of nanocrystalline less than 7 nm and to develop a hybrid-composite microstructure with increasing sample thickness. Twin roll strip casting was successfully applied to the fabrication of sheets in Fe-Ni-Cr-Si-B-based BMGs. The combined characteristics of high mechanical properties and ease of microstructure control proved to be promising in terms of the future progress of structural bulk amorphous alloys

  6. Mechanical properties of Fe-Ni-Cr-Si-B bulk glassy alloy

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kee Ahn [School of Advanced Materials Engineering, Andong National University, Andong 760-749 (Korea, Republic of)]. E-mail: keeahn@andong.ac.kr; Kim, Yong Chan [New Metals Research Team, RIST, Pohang 790-330 (Korea, Republic of); Kim, Jung Han [Center for Advanced Aerospace materials, POSTECH, Pohang 790-784 (Korea, Republic of); Lee, Chong Soo [Center for Advanced Aerospace materials, POSTECH, Pohang 790-784 (Korea, Republic of); Namkung, Jung [New Metals Research Team, RIST, Pohang 790-330 (Korea, Republic of); Kim, Moon Chul [New Metals Research Team, RIST, Pohang 790-330 (Korea, Republic of)

    2007-03-25

    The mechanical properties and crystallization behavior of new Fe-Ni-Cr-Si-B-based bulk glassy alloys were investigated. The suitability of the continuous roll casting method for the production of bulk metallic glass (BMG) sheets in such alloy systems was also examined. BMG samples (Fe-Ni-Cr-Si-B, Fe-Ni-Zr-Cr-Si-B, Fe-Ni-Zr-Cr-W-Si-B) in amorphous strip, cylindrical, and sheet forms were prepared through melt spinning, copper mold casting, and twin roll strip casting, respectively. Fe-Ni-Cr-Si-B alloy exhibited compressive strength of up to 2.93 GPa and plastic strain of about 1.51%. On the other hand, the Fe-Ni-Zr-Cr-Si-B, composite-type bulk sample with diameter of 2.0 mm showed remarkable compressive plastic strain of about 4.03%. The addition of zirconium was found to enhance the homogeneous precipitation of nanocrystalline less than 7 nm and to develop a hybrid-composite microstructure with increasing sample thickness. Twin roll strip casting was successfully applied to the fabrication of sheets in Fe-Ni-Cr-Si-B-based BMGs. The combined characteristics of high mechanical properties and ease of microstructure control proved to be promising in terms of the future progress of structural bulk amorphous alloys.

  7. Magnetic properties of the CrMnFeCoNi high-entropy alloy

    International Nuclear Information System (INIS)

    Schneeweiss, Oldřich; Friák, Martin; Masaryk University, Brno; Dudová, Marie; Holec, David

    2017-01-01

    In this paper, we present experimental data showing that the equiatomic CrMnFeCoNi high-entropy alloy undergoes two magnetic transformations at temperatures below 100 K while maintaining its fcc structure down to 3 K. The first transition, paramagnetic to spin glass, was detected at 93 K and the second transition of the ferromagnetic type occurred at 38 K. Field-assisted cooling below 38 K resulted in a systematic vertical shift of the hysteresis curves. Strength and direction of the associated magnetization bias was proportional to the strength and direction of the cooling field and shows a linear dependence with a slope of 0.006 ± 0.001 emu T. The local magnetic moments of individual atoms in the CrMnFeCoNi quinary fcc random solid solution were investigated by ab initio (electronic density functional theory) calculations. Results of the numerical analysis suggest that, irrespective of the initial configuration of local magnetic moments, the magnetic moments associated with Cr atoms align antiferromagnetically with respect to a cumulative magnetic moment of their first coordination shell. The ab initio calculations further showed that the magnetic moments of Fe and Mn atoms remain strong (between 1.5 and 2 μ B ), while the local moments of Ni atoms effectively vanish. Finally, these results indicate that interactions of Mn- and/or Fe-located moments with the surrounding magnetic structure account for the observed macroscopic magnetization bias.

  8. Nano-twin mediated plasticity in carbon-containing FeNiCoCrMn high entropy alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Z. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Materials Science and Engineering Department, University of Tennessee, Knoxville, TN 37996 (United States); Parish, C.M. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Bei, H., E-mail: beih@ornl.gov [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2015-10-25

    Equiatomic FeNiCoCrMn alloy has been reported to exhibit promising strength and ductility at cryogenic temperature and deformation mediated by nano-twining appeared to be one of the main reasons. We use the FeNiCoCrMn alloy as a base alloy to seek further improvement of its mechanical properties by alloying additional elements, i.e., interstitial carbon. The effects of carbon on microstructures, mechanical properties and twinning activities were investigated in two different temperatures (77 and 293 K). With addition of 0.5 at% C, the high entropy alloy still remains entirely single phase face-centered cubic (FCC) crystal structure. The materials can be cold rolled and recrystallized to produce a microstructure with equiaxed grains. Both strain hardening rate and strength are enhanced while high uniform elongations to fracture (∼70% at 77 K and ∼40% at 293 K) are still maintained. The increased strain hardening and strength could be caused by the promptness of deformation twinning in C-containing high entropy alloys. - Highlights: • Interstitial atom C was successfully added into FeNiCoCrMn high entropy alloys. • The strain hardening rate and strength are enhanced in the C-containing alloy. • The increased strain-hardening and strength are caused by the nano-twinning.

  9. Slurry Erosion Behavior of AlxCoCrFeNiTi0.5 High-Entropy Alloy Coatings Fabricated by Laser Cladding

    Directory of Open Access Journals (Sweden)

    Jianhua Zhao

    2018-02-01

    Full Text Available High-entropy alloys (HEAs have gained extensive attention due to their excellent properties and the related scientific value in the last decade. In this work, AlxCoCrFeNiTi0.5 HEA coatings (x: molar ratio, x = 1.0, 1.5, 2.0, and 2.5 were fabricated on Q345 steel substrate by laser-cladding process to develop a practical protection technology for fluid machines. The effect of Al content on their phase evolution, microstructure, and slurry erosion performance of the HEA coatings was studied. The AlxCoCrFeNiTi0.5 HEA coatings are composed of simple face-centered cubic (FCC, body-centered cubic (BCC and their mixture phase. Slurry erosion tests were conducted on the HEA coatings with a constant velocity of 10.08 m/s and 16–40 meshs and particles at impingement angles of 15, 30, 45, 60 and 90 degrees. The effect of three parameters, namely impingement angle, sand concentration and erosion time, on the slurry erosion behavior of AlxCoCrFeNiTi0.5 HEA coatings was investigated. Experimental results show AlCoCrFeNiTi0.5 HEA coating follows a ductile erosion mode and a mixed mode (neither ductile nor brittle for Al1.5CoCrFeNiTi0.5 HEA coating, while Al2.0CoCrFeNiTi0.5 and Al2.5CoCrFeNiTi0.5 HEA coatings mainly exhibit brittle erosion mode. AlCoCrFeNiTi0.5 HEA coating has good erosion resistance at all investigated impingement angles due to its high hardness, good plasticity, and low stacking fault energy (SFE.

  10. Helium accumulation and bubble formation in FeCoNiCr alloy under high fluence He+ implantation

    Science.gov (United States)

    Chen, Da; Tong, Y.; Li, H.; Wang, J.; Zhao, Y. L.; Hu, Alice; Kai, J. J.

    2018-04-01

    Face-centered cubic (FCC) high-entropy alloys (HEA), as emerging alloys with equal-molar or near equal-molar constituents, show a promising radiation damage resistance under heavy ion bombardment, making them potential for structural material application in next-generation nuclear reactors, but the accumulation of light helium ions, a product of nuclear fission reaction, has not been studied. The present work experimentally studied the helium accumulation and bubble formation at implantation temperatures of 523 K, 573 K and 673 K in a homogenized FCC FeCoNiCr HEA, a HEA showing excellent radiation damage resistance under heavy ion irradiation. The size and population density of helium bubbles in FeCoNiCr samples were quantitatively analyzed through transmission electron microscopy (TEM), and the helium content existing in bubbles were estimated from a high-pressure Equation of State (EOS). We found that the helium diffusion in such condition was dominated by the self-interstitial/He replacement mechanism, and the corresponding activation energy in FeCoNiCr is comparable with the vacancy migration energy in Ni and austenitic stainless steel but only 14.3%, 31.4% and 51.4% of the accumulated helium precipitated into helium bubbles at 523 K, 573 K and 673 K, respectively, smaller than the pure Ni case. Importantly, the small bubble size suggested that FeCoNiCr HEA has a high resistance of helium bubble formation compared with Ni and steels.

  11. Point defect properties of ternary fcc Fe-Cr-Ni alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wróbel, J.S., E-mail: jan.wrobel@inmat.pw.edu.pl [Faculty of Materials Science and Engineering, Warsaw University of Technology, Woloska 141, 02-507 Warsaw (Poland); Nguyen-Manh, D.; Dudarev, S.L. [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Kurzydłowski, K.J. [Faculty of Materials Science and Engineering, Warsaw University of Technology, Woloska 141, 02-507 Warsaw (Poland)

    2017-02-15

    Highlights: • Properties of point defects depend on the local atomic environment. • As the degree of chemical order increases, the formation energies increase, too. • Relaxation volumes are larger for the more ordered structures. - Abstract: The properties of point defects in Fe-Cr-Ni alloys are investigated, using density functional theory (DFT), for two alloy compositions, Fe{sub 50}Cr{sub 25}Ni{sub 25} and Fe{sub 55}Cr{sub 15}Ni{sub 30}, assuming various degrees of short-range order. DFT-based Monte Carlo simulations are applied to explore short-range order parameters and generate representative structures of alloys. Chemical potentials for the relevant structures are estimated from the minimum of the substitutional energy at representative atoms sites. Vacancies and 〈1 0 0〉 dumbbells are introduced in the Fe{sub 2}CrNi intermetallic phase as well as in two Fe{sub 55}Cr{sub 15}Ni{sub 30} alloy structures: the disordered and short range-ordered structures, generated using Monte Carlo simulations at 2000 K and 300 K, respectively. Formation energies and relaxation volumes of defects as well as changes of magnetic moments caused by the presence of defects are investigated as functions of the local environment of a defect.

  12. Annealing effects on structure and mechanical properties of CoCrFeNiTiAlx high-entropy alloys

    International Nuclear Information System (INIS)

    Zhang, K B; Fu, Z Y; Zhang, J Y; Wang, W M; Lee, S W; Niihara, K

    2011-01-01

    Novel CoCrFeNiTiAl x (x:molar ratio, other elements are equimolar) high-entropy alloys were prepared by vacuum arc melting and these alloys were subsequently annealed at 1000 deg. C for 2 h. The annealing effects on structure and mechanical properties were investigated. Compared with the as-cast alloys, there are many complex intermetallic phases precipitated from the solid solution matrix in the as-annealed alloys with Al content lower than Al 1.0 . Only simple BCC solid solution structure appears in the as-annealed Al 1.5 and Al 2.0 alloys. This kind of alloys exhibit high resistance to anneal softening. Most as-annealed alloys possess even higher Visker hardness than the as-cast ones. The as-annealed Al 0.5 alloys shows the highest compressive strength while the Al 0 alloy exhibits the best ductility, which is about 2.6 GPa and 13%, respectively. The CoCrFeNiTiAl x high-entropy alloys possess integrated high temperature mechanical property as well.

  13. Enhancing pitting corrosion resistance of AlxCrFe1.5MnNi0.5 high-entropy alloys by anodic treatment in sulfuric acid

    International Nuclear Information System (INIS)

    Lee, C.P.; Chen, Y.Y.; Hsu, C.Y.; Yeh, J.W.; Shih, H.C.

    2008-01-01

    High-entropy alloys are a newly developed family of multi-component alloys that comprise various major alloying elements. Each element in the alloy system is present in between 5 and 35 at.%. The crystal structures and physical properties of high-entropy alloys differ completely from those of conventional alloys. The electrochemical impedance spectra (EIS) of the Al x CrFe 1.5 MnNi 0.5 (x = 0, 0.3, 0.5) alloys, obtained in 0.1 M HCl solution, clearly revealed that the corrosion resistance values were determined to increase from 21 to 34 Ωcm 2 as the aluminum content increased from 0 to 0.5 mol, and were markedly lower than that of 304 stainless steel (243 Ωcm 2 ). At passive potential, the corresponding current declined with the anodizing time accounting, causing passivity by the growth of the multi-component anodized film in H 2 SO 4 solution. X-ray photoelectron spectroscopy (XPS) analyses revealed that the surface of anodized Al 0.3 CrFe 1.5 MnNi 0.5 alloy formed aluminum and chromium oxide film which was the main passivating compound on the alloy. This anodic treatment increased the corrosion resistance in the EIS measurements of the CrFe 1.5 MnNi 0.5 and Al 0.3 CrFe 1.5 MnNi 0.5 alloys by two orders of magnitude. Accordingly, the anodic treatment of the Al x CrFe 1.5 MnNi 0.5 alloys optimized their surface structures and minimized their susceptibility to pitting corrosion

  14. Effect of Perovskite coating on oxide scale growth on Fe-22Cr

    DEFF Research Database (Denmark)

    Persson, Åsa; Mikkelsen, Lars; Hendriksen, Peter Vang

    2006-01-01

    A coating consisting of La0.85Sr0.15MnO3 (LSM) was deposited onto two Fe 22 wt % Cr alloys Crofer 22APU and Sandvik lC44Mo20. The evolution of the oxide layers developing underneath the coatings during oxidation was investigated. The effect of the LSM coating on oxidation rate and microstructure ...

  15. Corrosion behaviour of electrodeposited nanocrystalline Ni-W and Ni-Fe-W alloys

    International Nuclear Information System (INIS)

    Sriraman, K.R.; Ganesh Sundara Raman, S.; Seshadri, S.K.

    2007-01-01

    The present work deals with evaluation of corrosion behaviour of electrodeposited nanocrystalline Ni-W and Ni-Fe-W alloys. Corrosion behaviour of the coatings deposited on steel substrates was studied using polarization and electrochemical impedance spectroscopy techniques in 3.5% NaCl solution while their passivation behaviour was studied in 1N sulphuric acid solution. The corrosion resistance of Ni-W alloys increased with tungsten content up to 7.54 at.% and then decreased. In case of Ni-Fe-W alloys it increased with tungsten content up to 9.20 at.% and then decreased. The ternary alloy coatings exhibited poor corrosion resistance compared to binary alloy coatings due to preferential dissolution of iron from the matrix. Regardless of composition all the alloys exhibited passivation behaviour over a wide range of potentials due to the formation of tungsten rich film on the surface

  16. Creep and Oxidation Behavior of Modified CF8C-Plus with W, Cu, Ni, and Cr

    Science.gov (United States)

    Unocic, Kinga A.; Dryepondt, Sebastien; Yamamoto, Yukinori; Maziasz, Philip J.

    2016-04-01

    The microstructures of modified CF8C-Plus (Fe-19Cr-12Ni-0.4W-3.8Mn-0.2Mo-0.6Nb-0.5Si-0.9C) with W and Cu (CF8CPWCu) and CF8CPWCu enhanced with 21Cr + 15Ni or 22Cr + 17.5Ni were characterized in the as-cast condition and after creep testing. When imaged at lower magnifications, the as-cast microstructure was similar among all three alloys as they all contained a Nb-rich interdendritic phase and Mn-based inclusions. Transmission electron microscopy (TEM) analysis showed the presence of nanoscale Cu-rich nanoprecipitates distributed uniformly throughout the matrix of CF8CPWCu, whereas in CF8CPWCu22/17, Cu precipitates were found primarily at the grain boundaries. The presence of these nanoscale Cu-rich particles, in addition to W-rich Cr23C6, nanoscale Nb carbides, and Z-phase (Nb2Cr2N2), improved the creep strength of the CF8CPWCu steel. Modification of CF8CPWCu with Cr and Ni contents slightly decreased the creep strength but significantly improved the oxidation behavior at 1073 K (800 °C). In particular, the addition of 22Cr and 17.5Ni strongly enhanced the oxidation resistance of the stainless steel resulting in a 100 degrees or greater temperature improvement, and this composition provided the best balance between improving both mechanical properties and oxidation resistance.

  17. Microstructural characterisation of high-entropy alloy AlCoCrFeNi fabricated by laser engineered net shaping

    Energy Technology Data Exchange (ETDEWEB)

    Kunce, I., E-mail: ikunce@wat.edu.pl [Department of Advanced Materials and Technology, Military University of Technology, 2 Kaliskiego Str., 01-908 Warsaw (Poland); Polanski, M.; Karczewski, K. [Department of Advanced Materials and Technology, Military University of Technology, 2 Kaliskiego Str., 01-908 Warsaw (Poland); Plocinski, T.; Kurzydlowski, K.J. [Faculty of Materials Science and Engineering, Warsaw University of Technology, 141 Wołoska Str., 02-507 Warsaw (Poland)

    2015-11-05

    Laser engineered net shaping (LENS) was used to produce thin-walled samples of the high-entropy alloy AlCoCrFeNi from a prealloyed powder. To determine the effect of the cooling rate during solidification on the microstructure of the alloy, different laser scanning rates were used. A microstructural study of the surfaces of the sample walls was performed using X-ray diffraction analysis and optical and scanning/transmission electron microscopy. The crystal structure of the alloy was determined to be a body-centred cubic (bcc)-derivative B2-ordered type. The microstructure of the alloy produced by LENS was dendritic. Further, it was found that with an increase in the laser scanning rate from 2.5 to 40 mm s{sup −1}, the average grain size decreased from 108.3 ± 32.4 μm to 30.6 ± 9.2 μm. The maximum cooling rate achieved during the laser cladding of the alloy was 44 × 10{sup 3} K s{sup −1}. The electron microscopy study of the alloy showed the presence of precipitates. The morphology of the disordered bcc (Fe, Cr)-rich precipitates in the ordered B2 (Al, Ni)-rich matrix changed in the dendritic and interdendritic regions from fine and spherical (with a diameter of less 100 nm) to spinodal (with the thickness being less than 100 nm). The LENS- produced AlCoCrFeNi alloy exhibited an average microhardness of approximately 543 HV0.5; this was approximately 13% higher than the hardness in the as-cast state and can be attributed to the grain refinemet in the LENS- produced alloy. Moreover, it was found that increasing the cooling rate during laser cladding increasess the microhardness of the alloy. - Highlights: • Laser-engineered net shaping is used to produce samples of AlCoCrFeNi alloy. • The alloy has a body-centred cubic (bcc)-derivative B2-ordered crystal structure. • Electron microscopy images of the alloy show the presence of precipitates. • The microhardness of the laser-clad alloy is higher than that of the as-cast alloy. • The cooling rate

  18. Microstructure and Tribological Properties of AlCoCrFeNiTi0.5 High-Entropy Alloy in Hydrogen Peroxide Solution

    Science.gov (United States)

    Yu, Y.; Liu, W. M.; Zhang, T. B.; Li, J. S.; Wang, J.; Kou, H. C.; Li, J.

    2014-01-01

    Microstructure and tribological properties of an AlCoCrFeNiTi0.5 high-entropy alloy in high-concentration hydrogen peroxide solution were investigated in this work. The results show that the sigma phase precipitates and the content of bcc2 decrease during the annealing process. Meanwhile, the complex construction of the interdendrite region changes into simple isolated-island shape, and much more spherical precipitates are formed. Those changes of microstructure during the annealing process lead to the increase of hardness of this alloy. In the testing conditions, the AlCoCrFeNiTi0.5 alloy shows smoother worn surfaces and steadier coefficient of friction curves than does the 1Cr18Ni9Ti stainless steel, and SiC ceramic preserves better wear resistance than ZrO2 ceramic. After annealing, the wear resistance of the AlCoCrFeNiTi0.5 alloy increases coupled with SiC counterface but decreases with ZrO2 counterface.

  19. Phase transformation, magnetic property and microstructure of Ni-Mn-Fe-Co-Ga ferromagnetic shape memory alloys

    International Nuclear Information System (INIS)

    Tsuchiya, K.; Sho, Y.; Kushima, T.; Todaka, Y.; Umemoto, M.

    2007-01-01

    Effects of addition of Fe and Co on the phase stability, magnetic property and microstructures were investigated for Ni-Mn-Ga. In Ni-Mn 21- x -Fe x -Ga 27 alloys, martensitic transformation temperatures decreased with increasing amount of Fe (x) up to 15 mol%, then slightly increased by the further addition. The crystal structure of martensite phase was 10 M for x 15 mol%. Relatively high martensite stability was obtained for Ni 52 -Mn 16- x -Fe x -Co 5 -Ga 27 alloys. The highest stability of the ferromagnetic martensite phase was achieved in Ni 52 -Mn 6 -Fe 10 -Co 5 -Ga 27 after aging at 773 K for 3.6 ks. Martensite structure was non-modulated 2 M in this series of alloys

  20. Tensile ductility of an AlCoCrFeNi multi-phase high-entropy alloy through hot isostatic pressing (HIP) and homogenization

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Zhi, E-mail: Zhi.Tang@alcoa.com [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States); Department of Materials Science and Engineering, Virginia Tech, Blacksburg, VA 24061 (United States); Senkov, Oleg N. [Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, OH 45433 (United States); Parish, Chad M. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Zhang, Chuan; Zhang, Fan [CompuTherm LLC, 437 S. Yellowstone Dr., Suite 217, Madison, WI 53719 (United States); Santodonato, Louis J. [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States); Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Wang, Gongyao [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States); Zhao, Guangfeng; Yang, Fuqian [Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506 (United States); Liaw, Peter K., E-mail: pliaw@utk.edu [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States)

    2015-10-28

    The microstructure and phase composition of an AlCoCrFeNi high-entropy alloy (HEA) were studied in as-cast (AlCoCrFeNi-AC, AC represents as-cast) and homogenized (AlCoCrFeNi-HP, HP signifies hot isostatic pressed and homogenized) conditions. The AlCoCrFeNi-AC ally has a dendritric structure in the consisting primarily of a nano-lamellar mixture of A2 (disordered body-centered-cubic (BCC)) and B2 (ordered BCC) phases, formed by an eutectic reaction. The homogenization heat treatment, consisting of hot isostatic pressed for 1 h at 1100 °C, 207 MPa and annealing at 1150 °C for 50 h, resulted in an increase in the volume fraction of the A1 phase and formation of a Sigma (σ) phase. Tensile properties in as-cast and homogenized conditions are reported at 700 °C. The ultimate tensile strength was virtually unaffected by heat treatment, and was 396±4 MPa at 700 °C. However, homogenization produced a noticeable increase in ductility. The AlCoCrFeNi-AC alloy showed a tensile elongation of only 1.0%, while after the heat-treatment, the elongation of AlCoCrFeNi-HP was 11.7%. Thermodynamic modeling of non-equilibrium and equilibrium phase diagrams for the AlCoCrFeNi HEA gave good agreement with the experimental observations of the phase contents in the AlCoCrFeNi-AC and AlCoCrFeNi-HP. The reasons for the improvement of ductility after the heat treatment and the crack initiation subjected to tensile loading were discussed.

  1. The irradiation hardening of Ni-Mo-Cr and Ni-W-Cr alloy under Xe26+ ion irradiation

    Science.gov (United States)

    Chen, Huaican; Hai, Yang; Liu, Renduo; Jiang, Li; Ye, Xiang-xi; Li, Jianjian; Xue, Wandong; Wang, Wanxia; Tang, Ming; Yan, Long; Yin, Wen; Zhou, Xingtai

    2018-04-01

    The irradiation hardening of Ni-Mo-Cr and Ni-W-Cr alloy was investigated. 7 MeV Xe26+ ion irradiation was performed at room temperature and 650 °C with peak damage dose from 0.05 to 10 dpa. With the increase of damage dose, the hardness of Ni-Mo-Cr and Ni-W-Cr alloy increases, and reaches saturation at damage dose ≥1 dpa. Moreover, the damage dose dependence of hardness in both alloys can be described by the Makin and Minter's equation, where the effective critical volume of obstacles can be used to represent irradiation hardening resistance of the alloys. Our results also show that Ni-W-Cr alloy has better irradiation hardening resistance than Ni-Mo-Cr alloy. This is ascribed to the fact that the W, instead of Mo in the alloy, can suppress the formation of defects under ion irradiation.

  2. Corrosion kinetics of alloy Ni-22Cr-13Mo-3W as structural material in high level nuclear waste containers

    International Nuclear Information System (INIS)

    Rodriguez, Martin A.

    2004-01-01

    Alloy Ni-22Cr-13Mo-3W (also known as C-22) is one of the candidates to fabricate high level nuclear waste containers. These containers are designed to maintain isolation of the waste for a minimum of 10,000 years. In this period, the material must be resistant to corrosion. If the containers were in contact with water, it is assumed that alloy C-22 may undergo three different corrosion mechanisms: general corrosion, localized corrosion and stress corrosion cracking. This thesis discusses only the first two types of degradation. Electrochemical techniques such as amperometry, potentiometry, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) and non-electrochemical techniques such as microscopic observation, X-ray fluorescence (XRF) and X-ray photoelectron spectroscopy (XPS) were applied to study the corrosion behavior of alloy C-22 in 1 M NaCl, 25 C degrees saturated NaF (approximately 1 M) and 0,5 M NaCl + 0,5 M NaF solutions. Effects of temperature, pH and alloy thermal aging were analyzed. The corrosion rates obtained at 90 C degrees were low ranging from 0.04 μm/year to 0.48 μm /year. They increased with temperature and decreased with solution pH. Most of the impedance measurements showed a simply capacitive behavior. A second high-frequency time constant was detected in some cases. It was attributed to the formation of a nickel oxide and/or hydroxide at potentials near the reversible potential for this reaction. The active/passive transition detected in some potentiodynamic polarization curves was attributed to the same process. The corrosion potential showed an important increase after 24 hours of immersion. This increase in the corrosion potential was associated with an improvement of the passive film. The corrosion potential was always lower than the re-passivation potential for the corresponding media. The trans passive behavior of alloy C-22 was mainly influenced by temperature and solution chemistry. A clear trans passive peak

  3. Effect of alloying elements on σ phase formation in Fe-Cr-Mn alloys

    International Nuclear Information System (INIS)

    Okazaki, Yoshimitsu; Miyahara, Kazuya; Hosoi, Yuzo; Tanino, Mitsuru; Komatsu, Hazime.

    1989-01-01

    Alloys of Fe-(8∼12%) Cr-(5∼30%) Mn were solution-treated at 1373 K for 3.6 ks, followed by cold-working of 50% reduction. Both solution-treated and 50% cold-worked materials were aged in the temperature range from 773 to 973 K for 3.6 x 10 3 ks. The identification of σ phase formation was made by using X-ray diffraction from the electrolytically extracted residues of the aged specimens. The region of σ phase formation determined by the present work is wider than that on the phase diagram already reported. It is to be noted that Mn promotes markedly the σ phase formation, and that three different types of σ phase formation are observed depending on Mn content: α→γ + α→γ + α + σ in 10% Mn, α→γ + σ in 15 to 20% Mn alloys, α→χ(Chi) →χ + σ + γ in 25 to 30% Mn alloys. An average electron concentration (e/a) in the σ phase was estimated by quantitative analysis of alloying elements using EPMA. The e/a value in the σ phase formed in Fe-(12∼16%) Cr-Mn alloys aged at 873 K for 3.6 x 10 3 ks is about 7.3, which is independent of Mn content. In order to prevent σ phase formation in Fe-12% Cr-15% Mn alloy, the value of Ni * eq of 11 (Ni * eq = Ni + 30(C) + 25(N)) is required. (author)

  4. Hydrogen solubility in austenite of Fe-Ni-Cr alloys

    International Nuclear Information System (INIS)

    Zhirnova, V.V.; Mogutnov, B.M.; Tomilin, I.A.

    1981-01-01

    Hydrogen solubility in Fe-Ni-Cr alloys at 600-1000 deg C is determined. Hydrogen solubility in ternary alloys can not be predicted on the basis of the data on its solubility in binary Fe-Ni, Fe-Cr alloys. Chromium and nickel effect on hydrogen solubility in iron is insignificant in comparison with the effect of these elements on carbon or nitrogen solubility [ru

  5. Corrosion resistance of Fe-based amorphous alloys

    International Nuclear Information System (INIS)

    Botta, W.J.; Berger, J.E.; Kiminami, C.S.; Roche, V.; Nogueira, R.P.; Bolfarini, C.

    2014-01-01

    Highlights: ► We report corrosion properties of Fe-based amorphous alloys in different media. ► The Cr-containing alloys had corrosion resistance close to that of Pt in all media. ► The wide range of electrochemical stability is relevant in many industrial domains. -- Abstract: Fe-based amorphous alloys can be designed to present an attractive combination of properties with high corrosion resistance and high mechanical strength. Such properties are clearly adequate for their technological use as coatings, for example, in steel pipes. In this work, we studied the corrosion properties of amorphous ribbons of the following Fe-based compositions: Fe 66 B 30 Nb 4 , [(Fe 0.6 Co 0.4 ) 0.75 B 0.2 Si 0.05 ] 96 Nb 4 , [(Fe 0.7 Co 0.3 ) 0.75 B 0.2 Si 0.05 ] 96 Nb 4 , Fe 56 Cr 23 Ni 5.7 B 16 , Fe 53 Cr 22 Ni 5.6 B 19 and Fe 50 Cr 22 Ni 5.4 B 23 . The ribbons were obtained by rapid solidification using the melt-spinning process, and were characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and optical (OM) and scanning electron microscopy (SEM). The corrosion properties were evaluated by corrosion potential survey and potentiodynamic polarization. The Cr containing alloys, that is the FeCrNiB type of alloys, showed the best corrosion resistance properties with the formation of a stable passive film that ensured a very large passivation plateau

  6. Effect of cobalt on microstructure and properties of AlCr1.5CuFeNi2Cox high-entropy alloys

    Science.gov (United States)

    Kukshal, Vikas; Patnaik, Amar; Bhat, I. K.

    2018-04-01

    The present paper investigates the effect of Co addition on the alloying behaviour, microstructure and the resulting properties of cast AlCr1.5CuFeNi2Cox high-entropy alloys intended to be used for high temperature applications. The elements Al, Cr, Cu, Fe, Ni and Co (Purity > 99) weighing approximately 800 g was melted in a high temperature vacuum induction furnace. The microstructure, phase transformation, density, microhardness and compressive strength of the samples were analysed using x-ray diffraction (XRD), scanning electron microscopes (SEM), Vickers microhardness tester and universal Testing machine. The crystalline structure of the alloys exhibits simple FCC and BCC phases. The microstructures investigation of the alloys shows the segregation of copper in the interdendritic region resulting in Cu-rich FCC phase. The addition of Co further enhances the formation of FCC phase resulting in the decrease in micro hardness value of the alloys, which varies from 471 HV to 364 HV with increase in the cobalt content from x = 0 to x = 1 (molar ratio). The similar decreasing trend is also observed for the compressive strength of the alloys.

  7. Interface Resistance between FeCr Interconnects and La0.85Sr0.15Mn1.1O3

    DEFF Research Database (Denmark)

    Mikkelsen, Lars; Neufeld, Kai; Hendriksen, Peter Vang

    2009-01-01

    The long term oxidation behaviour and the electrical interface resistance between FeCr interconnects and La0,85Sr0,15Mn1,1O3 plates was studied by a DC four-point method in air at 750{degree sign}C for 10000 h. The tested FeCr alloys were: Crofer 22 APU, Sanergy HT, Plansee IT10, Plansee IT11, an....... Low degradation rates of less than 1 mcm2/1000 h were measured on all interfaces. The microstructure analysis showed that a duplex Cr2O3-(Mn,Co,Cr)3O4 oxide scale with a thickness of 3-5 µm had evolved on the alloys....

  8. Effects of composition and heat treatments on the strength and ductility of Fe-Cr-Co alloys

    International Nuclear Information System (INIS)

    Kubarych, K.G.

    1980-06-01

    The relationship between the microstructure and mechanical properties of spinodally decomposed Fe-Cr-Co ductile permanent magnet alloys was investigated using transmission electron microscopy, electron diffraction, tensile testing, and Charpy impact testing. Isothermal aging and step aging of four alloys (Fe-28 wt % Cr-15 wt % Co, Fe-23 wt % Cr-15-wt % Co-5 wt % V, Fe-23 wt % Cr-15 wt % Co-3 wt % V-2 wt % Ti, and Fe-31 wt % Cr-23 % Co) resulted in decomposition into two phases, an Fe-Co rich (α 1 ) phase and a Cr rich (α 2 ) phase. The microstructural features of the decomposition products were consistent with those expected from a spinodal reaction and agree with the reported work on the Fe-Cr-Co system. An Fe-23 wt % Cr-15 wt % Co-5 wt % V alloy was found to have, among the four alloys, the best combinations of strength and ductility

  9. Preliminary Microstructural and Microscratch Results of Ni-Cr-Fe and Cr3C2-NiCr Coatings on Magnesium Substrate

    Science.gov (United States)

    Istrate, B.; Munteanu, C.; Lupescu, S.; Benchea, M.; Vizureanu, P.

    2017-06-01

    Thermal coatings have a large scale application in aerospace and automotive field, as barriers improving wear mechanical characteristics and corrosion resistance. In present research, there have been used two types of coatings, Ni-Cr-Fe, respectively Cr3C2-NiCr which were deposited on magnesium based alloys (pure magnesium and Mg-30Y master alloy). There have been investigated the microstructural aspects through scanning electronic microscopy and XRD analysis and also a series of mechanical characteristics through microscratch and indentation determinations. The results revealed the formation of some adherent layers resistant to the penetration of the metallic indenter, the coatings did not suffer major damages. Microstructural analysis highlighted the formation of Cr3C2, Cr7C3, Cr3Ni2, Cr7Ni3, FeNi3, Cr-Ni phases. Also, the apparent coefficient of friction for Ni-Cr-Fe coatings presents superior values than Cr3C2-NiCr coatings.

  10. Preliminary assessment of metal-porcelain bonding strength of CoCrW alloy after 3 wt.% Cu addition

    International Nuclear Information System (INIS)

    Lu, Yanjin; Zhao, Chaoqian; Ren, Ling; Guo, Sai; Gan, Yiliang; Yang, Chunguang; Wu, Songquan; Lin, Junjie; Huang, Tingting; Yang, Ke; Lin, Jinxin

    2016-01-01

    In this work, a novel Cu-bearing CoCrW alloy fabricated by selective laser melting for dental application has been studied. For its successful application, the bonding strength of metal-porcelain is essential to be systematically investigated. Therefore, the aim of this study was to evaluate the metal-porcelain bonding strength of CoCrWCu alloy by three-point bending test, meanwhile the Ni-free CoCrW alloy was used as control. The oxygen content was investigated by an elemental analyzer; X-ray photoelectron spectroscopy (XPS) was used to analyze the surface chemical composition of CoCrW based alloy after preoxidation treatment; the fracture mode was investigated by X-ray energy spectrum analysis (EDS) and scanning electron microscope (SEM). Result from the oxygen content analysis showed that the content of oxygen dramatically increased after the Cu addition. And the XPS suggested that Co-oxidation, Cr_2O_3, CrO_2, WO_3, Cu_2O and CuO existed on the preoxidated surface of the CoCrWCu alloy; the three-point bending test showed that the bonding strength of the CoCrWCu alloy was 43.32 MPa, which was lower than that of the CoCrW group of 47.65 MPa. However, the average metal-porcelain bonding strength is significantly higher than the minimum value in the ISO 9693 standard. Results from the SEM images and EDS indicated that the fracture mode of CoCrWCu-porcelain was mixed between cohesive and adhesive. Based on the results obtained in this study, it can be indicated that the Cu-bearing CoCrW alloy fabricated by the selective laser melting is a promising candidate for use in dental application. - Highlights: • The bonding strength of metal-porcelain was slightly decreased with Cu addition; • Cu not only led to promote the diffusion of O and W element but also inhibited the diffusivity of Co in the outward direction; • The changed oxidation behavior resulted in lowering the bonding strength;

  11. Preliminary assessment of metal-porcelain bonding strength of CoCrW alloy after 3 wt.% Cu addition

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Yanjin; Zhao, Chaoqian [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, 155Yangqiao Road West, Fuzhou (China); Ren, Ling [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang (China); Guo, Sai; Gan, Yiliang [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, 155Yangqiao Road West, Fuzhou (China); Yang, Chunguang [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang (China); Wu, Songquan; Lin, Junjie; Huang, Tingting [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, 155Yangqiao Road West, Fuzhou (China); Yang, Ke, E-mail: kyang@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang (China); Lin, Jinxin, E-mail: franklin@fjirsm.ac.cn [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, 155Yangqiao Road West, Fuzhou (China)

    2016-06-01

    In this work, a novel Cu-bearing CoCrW alloy fabricated by selective laser melting for dental application has been studied. For its successful application, the bonding strength of metal-porcelain is essential to be systematically investigated. Therefore, the aim of this study was to evaluate the metal-porcelain bonding strength of CoCrWCu alloy by three-point bending test, meanwhile the Ni-free CoCrW alloy was used as control. The oxygen content was investigated by an elemental analyzer; X-ray photoelectron spectroscopy (XPS) was used to analyze the surface chemical composition of CoCrW based alloy after preoxidation treatment; the fracture mode was investigated by X-ray energy spectrum analysis (EDS) and scanning electron microscope (SEM). Result from the oxygen content analysis showed that the content of oxygen dramatically increased after the Cu addition. And the XPS suggested that Co-oxidation, Cr{sub 2}O{sub 3}, CrO{sub 2}, WO{sub 3}, Cu{sub 2}O and CuO existed on the preoxidated surface of the CoCrWCu alloy; the three-point bending test showed that the bonding strength of the CoCrWCu alloy was 43.32 MPa, which was lower than that of the CoCrW group of 47.65 MPa. However, the average metal-porcelain bonding strength is significantly higher than the minimum value in the ISO 9693 standard. Results from the SEM images and EDS indicated that the fracture mode of CoCrWCu-porcelain was mixed between cohesive and adhesive. Based on the results obtained in this study, it can be indicated that the Cu-bearing CoCrW alloy fabricated by the selective laser melting is a promising candidate for use in dental application. - Highlights: • The bonding strength of metal-porcelain was slightly decreased with Cu addition; • Cu not only led to promote the diffusion of O and W element but also inhibited the diffusivity of Co in the outward direction; • The changed oxidation behavior resulted in lowering the bonding strength;.

  12. Austenitic alloys Fe-Ni-Cr dominating

    International Nuclear Information System (INIS)

    Gibson, R.C.; Korenko, M.K.

    1980-01-01

    Austenitic alloy essentially comprising 42 to 48% nickel, 11 to 13% chromium, 2.6 to 3.4% niobium, 0.2 to 1.2% silicon, 0.5 to 1.5% vanadium, 2.6 to 3.4% molybdenum, 0.1 to 0.3% aluminium, 0.1 to 0.3% titanium, 0.02 to 0.05% carbon, 0.002 to 0.015% boron, up to 0.06% zirconium, the balance being iron. The characteristic of this alloy is a conventional elasticity limit to within 2% of at least 450 MPa, with a maximum tensile strength of at least 500 MPa at a test temperature of 650 0 C after immersion annealing at 1038 0 C and 30% hardening. To this effect the invention concerns Ni-Cr-Fe high temperature alloys possessing excellent mechanical strength characteristics, that can be obtained with lower levels of nickel and chromium than those used in alloys of this kind in the present state of the technique, a higher amount of niobium than in the previous alloys and with the addition of 0.5 to 1.5% vanadium [fr

  13. Enhancing pitting corrosion resistance of Al{sub x}CrFe{sub 1.5}MnNi{sub 0.5} high-entropy alloys by anodic treatment in sulfuric acid

    Energy Technology Data Exchange (ETDEWEB)

    Lee, C.P.; Chen, Y.Y.; Hsu, C.Y.; Yeh, J.W. [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Shih, H.C. [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 300, Taiwan (China); Institute of Materials Science and Nanotechnology, Chinese Culture University, Taipei 111, Taiwan (China)], E-mail: hcshih@mx.nthu.edu.tw

    2008-12-01

    High-entropy alloys are a newly developed family of multi-component alloys that comprise various major alloying elements. Each element in the alloy system is present in between 5 and 35 at.%. The crystal structures and physical properties of high-entropy alloys differ completely from those of conventional alloys. The electrochemical impedance spectra (EIS) of the Al{sub x}CrFe{sub 1.5}MnNi{sub 0.5} (x = 0, 0.3, 0.5) alloys, obtained in 0.1 M HCl solution, clearly revealed that the corrosion resistance values were determined to increase from 21 to 34 {omega}cm{sup 2} as the aluminum content increased from 0 to 0.5 mol, and were markedly lower than that of 304 stainless steel (243 {omega}cm{sup 2}). At passive potential, the corresponding current declined with the anodizing time accounting, causing passivity by the growth of the multi-component anodized film in H{sub 2}SO{sub 4} solution. X-ray photoelectron spectroscopy (XPS) analyses revealed that the surface of anodized Al{sub 0.3}CrFe{sub 1.5}MnNi{sub 0.5} alloy formed aluminum and chromium oxide film which was the main passivating compound on the alloy. This anodic treatment increased the corrosion resistance in the EIS measurements of the CrFe{sub 1.5}MnNi{sub 0.5} and Al{sub 0.3}CrFe{sub 1.5}MnNi{sub 0.5} alloys by two orders of magnitude. Accordingly, the anodic treatment of the Al{sub x}CrFe{sub 1.5}MnNi{sub 0.5} alloys optimized their surface structures and minimized their susceptibility to pitting corrosion.

  14. Diffusion of 51Cr along high-diffusivity paths in Ni-Fe alloys

    International Nuclear Information System (INIS)

    Cermak, J.

    1990-01-01

    Penetration profiles of 51 Cr in polycrystalline alloys Ni-xFe (x = 0, 20, 40, and 60 wt.% Fe) after diffusion anneals at temperatures between 693 and 1473 K are studied. Sectioning of diffusion zones of samples annealed above 858 K is carried out by grinding, at lower temperatures by DC glow discharge sputtering. The concentration of 51 Cr in depth x is assumed to be proportional to relative radioactivity of individual sections. With help of volume and pipe self-diffusion data taken from literature, the temperature dependence of product P = δD g (δ and D g are grain boundary width and grain boundary diffusion coefficient, respectively) is obtained: P = (2.68 - 0.88 +1.3 ) x 10 -11 exp [-(221.3 ± 3.0) kJ/mol/RT]m 3 /s. This result agrees well with the previous measurements of 51 Cr diffusivity in Fe-18 Cr-12 Ni and Fe-21 Cr-31 Ni. It indicates that the mean chemical composition of Fe-Cr-Ni ternary alloys is not a dominant factor affecting the grain boundary diffusivity of Cr in these alloys. (author)

  15. Deep Drawing Behavior of CoCrFeMnNi High-Entropy Alloys

    Science.gov (United States)

    Bae, Jae Wung; Moon, Jongun; Jang, Min Ji; Ahn, Dong-Hyun; Joo, Soo-Hyun; Jung, Jaimyun; Yim, Dami; Kim, Hyoung Seop

    2017-09-01

    Herein, the deep drawability and deep drawing behavior of an equiatomic CoCrFeMnNi HEA and its microstructure and texture evolution are first studied for future applications. The CoCrFeMnNi HEA is successfully drawn to a limit drawing ratio (LDR) of 2.14, while the planar anisotropy of the drawn cup specimen is negligible. The moderate combination of strain hardening exponent and strain rate sensitivity and the formation of deformation twins in the edge region play important roles in successful deep drawing. In the meanwhile, the texture evolution of CoCrFeMnNi HEA has similarities with conventional fcc metals.

  16. Corrosion resistance of Ni-Cr-Mo alloys. Chemical composition and metallurgical condition's effects

    International Nuclear Information System (INIS)

    Zadorozne, N.S.; Rebak, Raul B.

    2009-01-01

    Ni-Cr-Mo alloys offer an outstanding corrosion resistance in a wide variety of highly-corrosive environments. This versatility is due to the excellent performance of nickel in hot alkaline solutions and the beneficial effect of chromium and molybdenum in oxidizing and reducing conditions, respectively. Alloy C-22 (22 % Cr-13 % Mo-3% W) is a well known versatile member of this family. Due to its excellent corrosion resistance in a wide variety of environments, Alloy C-22 has been selected for the fabrication of the corrosion-resistant outer shell of the high-level nuclear waste container. The increasing demand of the industry for corrosion resistant alloys with particular properties of corrosion and mechanical resistance has led to the development of new alloys. Alloy C-22HS (Ni-21 % Cr-17 % Mo) is a new high-strength corrosion resistant material recently developed and introduced into the market. This alloy provides a corrosion resistance comparable with that of other C-type alloys, and it can also be age hardened to effectively double its yield strength. HASTELLOY HYBRID-BC1 (Ni-22 % Mo-15 % Cr) is a new development intended for filling the gap between Ni-Mo and Ni-Cr-Mo alloys. This novel alloy is able to withstand HCl and H 2 SO 4 , even in the presence of dissolved oxygen and other oxidizing species. Its resistance to chloride-induced pitting corrosion, crevice corrosion and stress corrosion cracking is also remarkable. Thermal aging of Ni-Cr-Mo alloys leads to microstructure changes depending on the temperature range and exposure time at temperature. A Long Range Ordering (LRO) reaction can occur in the range of 350 C degrees to 600 C degrees, producing an ordered Ni 2 (Cr,Mo) phase. This ordering reaction does not seem to affect the corrosion resistance and produces only a slight loss in ductility. LRO transformation is homogeneous and has proven to be useful to fabricate the age-hard enable Alloy C22-HS. Tetrahedral Close Packed (TCP) phases, like μ, σ and

  17. Anodic behavior of alloy 22 in bicarbonate containing media: Effect of alloying

    International Nuclear Information System (INIS)

    Zadorozne, N S; Giordano, C M; Rebak, R B; Ares, A E; Carranza, R M

    2012-01-01

    Alloy 22 is one of the candidates for the manufacture of high level nuclear waste containers. These containers provide services in natural environments characterized by multi-ionic solutions.It is estimated they could suffer three types of deterioration: general corrosion, localized corrosion (specifically crevice corrosion) and stress corrosion cracking (SCC). It has been confirmed that the presence of bicarbonate and chloride ions is necessary to produce cracking, . It has also been determined that the susceptibility to SCC could be related to the occurrence of an anodic peak in the polarization curves in these media at potentials below transpassivity. The aim of this work is to study the effect of alloying elements on the anodic behavior of Alloy 22 in media containing bicarbonate and chloride ions at different concentrations and temperatures. Polarization curves were made on alloy 22 (Ni-22% Cr-13% Mo), Ni-Mo (Ni-28, 5% Mo) and Ni-Cr (Ni-20% Cr) in the following solutions: 1 mol/L NaCl at 90 o C, and 1.148 mol/L NaHCO 3 ; 1.148 mol/L NaHCO 3 + 1 mol/L NaCl; 1.148 mol/L NaHCO 3 + 0.1 mol/L NaCl, at 90 o C, 75 o C, 60 o C and 25 o C. It was found that alloy 22 has a anodic current density peak at potentials below transpassivity, only in the presence of bicarbonate ions. Curves performed in 1 mol/L NaCl did not show any anodic peak, in any of the tested alloys. The curves made on alloys Ni-Mo and Ni-Cr in the presence of bicarbonate ions, allowed to determine that Cr, is responsible for the appearance of the anodic peak in alloy 22. The curves of alloy Ni-Mo showed no anodic peak in the studied conditions. The potential at which the anodic peak appears in alloy 22 and Ni-Cr alloy, increases with decreasing temperature. The anodic peak was also affected by solution composition. When chloride ion is added to bicarbonate solutions, the anodic peak is shifted to higher potential and current densities, depending on the concentration of added chloride ions (author)

  18. Microstructure and Mechanical Properties Evolution of the Al, C-Containing CoCrFeNiMn-Type High-Entropy Alloy during Cold Rolling.

    Science.gov (United States)

    Klimova, Margarita; Stepanov, Nikita; Shaysultanov, Dmitry; Chernichenko, Ruslan; Yurchenko, Nikita; Sanin, Vladimir; Zherebtsov, Sergey

    2017-12-29

    The effect of cold rolling on the microstructure and mechanical properties of an Al- and C-containing CoCrFeNiMn-type high-entropy alloy was reported. The alloy with a chemical composition (at %) of (20-23) Co, Cr, Fe, and Ni; 8.82 Mn; 3.37 Al; and 0.69 C was produced by self-propagating high-temperature synthesis with subsequent induction. In the initial as-cast condition the alloy had an face centered cubic single-phase coarse-grained structure. Microstructure evolution was mostly associated with either planar dislocation glide at relatively low deformation during rolling (up to 20%) or deformation twinning and shear banding at higher strain. After 80% reduction, a heavily deformed twinned/subgrained structure was observed. A comparison with the equiatomic CoCrFeNiMn alloy revealed higher dislocation density at all stages of cold rolling and later onset of deformation twinning that was attributed to a stacking fault energy increase in the program alloy; this assumption was confirmed by calculations. In the initial as-cast condition the alloy had low yield strength of 210 MPa with yet very high uniform elongation of 74%. After 80% rolling, yield strength approached 1310 MPa while uniform elongation decreased to 1.3%. Substructure strengthening was found to be dominated at low rolling reductions (<40%), while grain (twin) boundary strengthening prevailed at higher strains.

  19. Ostwald Ripening Process of Coherent β′ Precipitates during Aging in Fe0.75Ni0.10Al0.15 and Fe0.74Ni0.10Al0.15Cr0.01 Alloys

    Directory of Open Access Journals (Sweden)

    N. Cayetano-Castro

    2015-01-01

    Full Text Available The Ostwald ripening process was studied in Fe0.75Ni0.10Al0.15 and Fe0.74Ni0.10Al0.15Cr0.01 alloys after aging at 750, 850, and 950°C for different times. The microstructural evolution shows a rounded cube morphology (Fe, NiAl β′ precipitates aligned in the ferrite matrix, which changes to elongated plates after prolonged aging. The variation of the equivalent radii of precipitates with time follows the modified Lifshitz-Slyozov-Wagner theory for diffusion-controlled coarsening. Thermo-Calc analysis shows that the chromium content is richer in the matrix than in the precipitates which causes higher hardness and coarsening resistance in the aged Fe0.74Ni0.10Al0.15Cr0.01 alloy.

  20. Phase Evolution and Mechanical Properties of AlCoCrFeNiSi x High-Entropy Alloys Synthesized by Mechanical Alloying and Spark Plasma Sintering

    Science.gov (United States)

    Kumar, Anil; Swarnakar, Akhilesh Kumar; Chopkar, Manoj

    2018-05-01

    In the current investigation, AlCoCrFeNiSi x (x = 0, 0.3, 0.6 and 0.9 in atomic ratio) high-entropy alloy systems are prepared by mechanical alloying and subsequently consolidated by spark plasma sintering. The microstructural and mechanical properties were analyzed to understand the effect of Si addition in AlCoCrFeNi alloy. The x-ray diffraction analysis reveals the supersaturated solid solution of the body-centered cubic structure after 20 h of ball milling. However, the consolidation promotes the transformation of body-centered phases partially into the face-centered cubic structure and sigma phases. A recently proposed geometric model based on the atomic stress theory has been extended for the first time to classify single phase and multi-phases on the high-entropy alloys prepared by mechanical alloying and spark plasma sintering process. Improved microhardness and better wear resistance were achieved as the Si content increased from 0 to 0.9 in the present high-entropy alloy.

  1. KINETICS OF CATHODIC REDUCTION OF OXYGEN ON NI-CR-MO-W ALLOY

    International Nuclear Information System (INIS)

    NA

    2006-01-01

    Ni-Cr-Mo-W alloys (C-group alloys) are well known as materials with very high Corrosion resistance in very aggressive environments, an asset that has motivated the selection of Alloy 22 as a waste package material in the Yucca Mountain Project for the long-term geologic disposal of spent nuclear fuel and other high-level radioactive wastes. The aim of this project is to elucidate the corrosion performance of Alloy 22 under aggressive conditions and to provide a conceptual understanding and parameter data base that could act as a basis for modeling the corrosion performance of waste packages under Yucca Mountain conditions. A key issue in any corrosion process is whether or not the kinetics of the cathodic reactions involved can support a damaging rate of anodic metal (alloy) dissolution. Under Yucca Mountain conditions the primary oxidant available to drive corrosion (most likely in the form of crevice, or under-deposit, corrosion) will be oxygen. Here, we present results on the kinetics of oxygen reduction at the Alloy 22/solution interface

  2. Effects of lipopolysaccharides on the corrosion behavior of Ni-Cr and Co-Cr alloys.

    Science.gov (United States)

    Yu, Weiqiang; Qian, Chao; Weng, Weimin; Zhang, Songmei

    2016-08-01

    Lipopolysaccharides (LPS) are constituents of gingival crevicular fluid and may affect the base metal alloys used in metal ceramic crowns. The role of LPS in base metal alloys is currently unknown. The purpose of this in vitro study was to evaluate the effects of gram-negative bacterial LPS on the electrochemical behavior of Ni-Cr and Co-Cr alloys. Alloy specimens were divided into 4 groups according to Escherichia coli LPS concentration (0, 0.15, 15, and 150 μg/mL) in acidic saliva (pH 5). Open circuit potential (OCP) and potentiodynamic polarization behavior were examined using a computer-controlled potentiostat. Metal ions released from the 2 alloys were measured by immersion in LPS-free solution and 150 μg/mL LPS solution and analyzed by inductively coupled plasma atomic emission spectrometry (ICP-AES). Data were evaluated using 1-way ANOVA (α=.05). Compared with control groups, medium LPS concentration (15 μg/mL) accelerated Ni-Cr alloy corrosion (Palloy corrosion (Pcorrosion current density, and polarization resistance parameters. After immersion in high LPS concentrations (150 μg/mL), a slight increase in Ni ion release (P >.05) was observed for the Ni-Cr alloy, while a more significant Co ion release (Palloy. LPS negatively affected the electrochemical behavior of both the Ni-Cr and Co-Cr alloys. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  3. Alloying behavior and deformation twinning in a CoNiFeCrAl0.6Ti0.4 high entropy alloy processed by spark plasma sintering

    International Nuclear Information System (INIS)

    Fu, Zhiqiang; Chen, Weiping; Fang, Sicong; Zhang, Dayue; Xiao, Huaqiang; Zhu, Dezhi

    2013-01-01

    Highlights: ► CoNiFeCrAl 0.6 Ti 0.4 high entropy alloy has been synthesized via MA and SPS. ► Deformation twinning possibly occurred during MA or SPS. ► This alloy exhibits excellent mechanical properties. ► The fracture mechanism of this alloy is intergranular fracture and plastic fracture. -- Abstract: Inequi-atomic CoNiFeCrAl 0.6 Ti 0.4 high entropy alloy has been designed and fabricated by mechanical alloying (MA) and spark plasma sintering (SPS). Alloying behavior, microstructure, phase evolution and mechanical properties of CoNiFeCrAl 0.6 Ti 0.4 alloy were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM), as well as by an Instron testing system. During MA, a supersaturated solid solution consisting of a FCC phase and a metastable BCC phase was formed. Two FCC phases (named FCC1 and FCC2) and a new BCC phase were observed after SPS. During SPS, the metastable BCC phase transformed into the FCC2 phase and the new BCC phase. Meanwhile, the FCC1 phase was the initial FCC phase which was formed during MA. Moreover, nanoscale twins obviously presented only in partial FCC1 phase after SPS. Deformation twinning may be occurred during MA or SPS. The sintered alloy with a high relative density of 98.83% exhibits excellent comprehensive mechanical properties. The yield stress, compressive strength, compression ratio and Vickers hardness of the alloy are 2.08, 2.52 GPa, 11.5% and 573 H V , respectively. The fracture mechanism of CoNiFeCrAl 0.6 Ti 0.4 high entropy alloy is mainly performed at intergranular fracture and plastic fracture mode

  4. Magnetic features of Fe-Cr-Co alloys with tailoring chromium content fabricated by spark plasma sintering

    International Nuclear Information System (INIS)

    Rastabi, Reza Amini; Ghasemi, Ali; Tavoosi, Majid; Ramazani, Mazaher

    2017-01-01

    Structural and magnetic characterization of Fe-Cr-Co alloys during milling, annealing and consolidation processes was the goal of this study. In this regards, different powder mixtures of Fe 80−x Cr x Co 20 (15≤x≤35) were mechanically milled in a planetary ball mill and then were consolidated by spark plasma sintering (SPS). The produced samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). According to achieved results, the structure of as-milled samples in different compositions consists of single α phase solid solution with coercivity and saturation of magnetization in the range of 110–200 Oe and 150–220 emu/g, respectively. The magnetic properties of consolidated samples depend on the kinds of formed precipitates in microstructure and the maximum values of coercive force and saturation of magnetization obtained in Fe 55 Cr 25 Co 20 magnetic (with single α phase) alloy were 107 Oe and Ms 172 emu/g, respectively. In fact, the formation of non-magnetic σ and γ phases has a destructive effect on magnetic properties of consolidated samples with higher Cr content. Since such magnet requires less cobalt, and contains similar magnetic feature with superior ductility compare to the AlNiCo 5, it could be considered as a promising candidate for employing instead of AlNiCo 5. - Highlights: • Milled samples consist of single phase α-solid solution. • Saturation of magnetization of Fe 65 Cr 15 Co 20 reached to 172 emu/g. • Fe 65 Cr 15 Co 20 alloy is the suitable composition fabricated by SPS.

  5. The impedance properties of the oxide film on the Ni-Cr-Mo Alloy-22 in neutral concentrated sodium chloride solution

    Energy Technology Data Exchange (ETDEWEB)

    Jakupi, P.; Zagidulin, D.; Noel, J.J. [Department of Chemistry, University of Western Ontario, London, Ontario, N6A-3K7 (Canada); Shoesmith, D.W., E-mail: dwshoesm@uwo.ca [Department of Chemistry, University of Western Ontario, London, Ontario, N6A-3K7 (Canada)

    2011-07-01

    The oxide film properties on Alloy-22 in the applied potential (E) range -600 mV to 600 mV (vs. saturated KCl, Ag/AgCl reference electrode) were characterized by Electrochemical Impedance Spectroscopy (EIS) in near neutral pH, 5 M NaCl solutions, at 30 deg. C. The impedance properties of the film were compared to the chromium content of the film determined by X-ray photoelectron spectroscopy (XPS). The oxide film properties on Alloy-22 may be divided into three applied potential (E) ranges: -600 mV {<=} E < -300 mV, -300 mV {<=} E {<=} 300 mV, and E > 300 mV. For the range -600 mV {<=} E < -300 mV the film resistance (R{sub film}) increases with potential accompanied by an increase in Cr{sub 2}O{sub 3} content; in the range -300 mV {<=} E {<=} 300 mV, R{sub film} values and the Cr{sub 2}O{sub 3} content of the oxide film achieve their maximum values; for E > 300 mV, a decrease in both R{sub film} and Cr{sub 2}O{sub 3} is observed accompanied by a significant increase in Cr(OH){sub 3}. Comparison of the impedance properties for Alloy-22 to those of Ni-Cr alloys indicate that the barrier layer oxide on Alloy-22 contains a lower number of less mobile defects, most likely Cr interstitials. Destruction of the barrier layer for E > 300 mV leads to the formation of a thicker, less protective bilayer, which is high in Mo content.

  6. In-situ electrochemical-AFM study of localized corrosion of AlxCoCrFeNi high-entropy alloys in chloride solution

    Science.gov (United States)

    Shi, Yunzhu; Collins, Liam; Balke, Nina; Liaw, Peter K.; Yang, Bin

    2018-05-01

    In-situ electrochemical (EC)-AFM is employed to investigate the localized corrosion of the AlxCoCrFeNi high-entropy alloys (HEAs). Surface topography changes on the micro/sub-micro scale are monitored at different applied anodizing potentials in a 3.5 wt% NaCl solution. The microstructural evolutions with the increased Al content in the alloys are characterized by SEM, TEM, EDS and EBSD. The results show that by increasing the Al content, the microstructure changes from single solid-solution to multi-phases, leading to the segregations of elements. Due to the microstructural variations in the AlxCoCrFeNi HEAs, localized corrosion processes in different ways after the breakdown of the passive film, which changes from pitting to phase boundary corrosion. The XPS results indicate that an increased Al content in the alloys/phases corresponds to a decreased corrosion resistance of the surface passive film.

  7. Soft Magnetic Properties of High-Entropy Fe-Co-Ni-Cr-Al-Si Thin Films

    Directory of Open Access Journals (Sweden)

    Pei-Chung Lin

    2016-08-01

    Full Text Available Soft magnetic properties of Fe-Co-Ni-Al-Cr-Si thin films were studied. As-deposited Fe-Co-Ni-Al-Cr-Si nano-grained thin films showing no magnetic anisotropy were subjected to field-annealing at different temperatures to induce magnetic anisotropy. Optimized magnetic and electrical properties of Fe-Co-Ni-Al-Cr-Si films annealed at 200 °C are saturation magnetization 9.13 × 105 A/m, coercivity 79.6 A/m, out-of-plane uniaxial anisotropy field 1.59 × 103 A/m, and electrical resistivity 3.75 μΩ·m. Based on these excellent properties, we employed such films to fabricate magnetic thin film inductor. The performance of the high entropy alloy thin film inductors is superior to that of air core inductor.

  8. Magnetic features of Fe-Cr-Co alloys with tailoring chromium content fabricated by spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Rastabi, Reza Amini; Ghasemi, Ali, E-mail: ali13912001@yahoo.com; Tavoosi, Majid; Ramazani, Mazaher

    2017-03-15

    Structural and magnetic characterization of Fe-Cr-Co alloys during milling, annealing and consolidation processes was the goal of this study. In this regards, different powder mixtures of Fe{sub 80−x}Cr{sub x}Co{sub 20} (15≤x≤35) were mechanically milled in a planetary ball mill and then were consolidated by spark plasma sintering (SPS). The produced samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). According to achieved results, the structure of as-milled samples in different compositions consists of single α phase solid solution with coercivity and saturation of magnetization in the range of 110–200 Oe and 150–220 emu/g, respectively. The magnetic properties of consolidated samples depend on the kinds of formed precipitates in microstructure and the maximum values of coercive force and saturation of magnetization obtained in Fe{sub 55}Cr{sub 25}Co{sub 20} magnetic (with single α phase) alloy were 107 Oe and Ms 172 emu/g, respectively. In fact, the formation of non-magnetic σ and γ phases has a destructive effect on magnetic properties of consolidated samples with higher Cr content. Since such magnet requires less cobalt, and contains similar magnetic feature with superior ductility compare to the AlNiCo 5, it could be considered as a promising candidate for employing instead of AlNiCo 5. - Highlights: • Milled samples consist of single phase α-solid solution. • Saturation of magnetization of Fe{sub 65}Cr{sub 15}Co{sub 20} reached to 172 emu/g. • Fe{sub 65}Cr{sub 15}Co{sub 20} alloy is the suitable composition fabricated by SPS.

  9. Study and characterization of FeNi and NiCr(80-20) % w alloys, during and after neutron irradiation, using the resistivity method

    International Nuclear Information System (INIS)

    Otero, Mauro Pereira

    1978-01-01

    We have used the resistivity method with and without neutron irradiation to study the parameters that appear in the Order-Disorder Transitions of Fe Ni(50-50)% at. and Ni Cr( 80 - 20) % w. alloys. The results obtained with Fe Ni are in agreement with those obtained by Marchand at the University of Grenoble. Several isothermal annealings were made in the range 400 - 302 deg C in which T c (Order-Disorder Transition Critical Temperature) was determined between 327 and 310 deg C. The activation energy obtained was E a = 0,49 eV and is in agreement with works of Marchand, Dienes and Damask. As for Ni Cr(80-20)% the following has been done: a) Electrical Properties characterizations, having in mind the technological applications; b) Linear and isothermal annealings were performed to determine the Order-Disorder Transition Critical Temperature (I ) supported by hypothesis made, taking into account the Yano's and Taylor's marks. The-result is T c = (536 +- 4) deg C; c) determination of activation energy E a = (1,36 +- 0.14) eV. The resistivity measurements mere performed by means of the classical 4-wire method. An anisotropy of electrical resistivity was found to exist depending on the sense of the applied electrical field. (author)

  10. Hot corrosion of Co-Cr, Co-Cr-Al, and Ni-Cr alloys in the temperature range of 700-750 deg C

    Science.gov (United States)

    Chiang, K. T.; Meier, G. H.

    1980-01-01

    The effect of SO3 pressure in the gas phase on the Na2SO4 induced hot corrosion of Co-Cr, Ni-Cr, and Co-Cr-Al alloys was studied in the temperature range 700 to 750 C. The degradation of the Co-Cr and Ni-Cr alloys was found to be associated with the formation of liquid mixed sulfates (CoSO4-Na2SO4 or NiSO4-Na2SO4) which provided a selective dissolution of the Co or Ni and a subsequent sulfidation oxidation mode of attack which prevented the maintenance of a protective Cr2O3 film. A clear mechanism was not developed for the degradation of Co-Cr-Al alloys. A pitting corrosion morphology was induced by a number of different mechanisms.

  11. Oxidation of Fe–22Cr Coated with Co3O4: Microstructure Evolution and the Effect of Growth Stresses

    DEFF Research Database (Denmark)

    Hansson, Anette Nørgaard; Burriel, Monica; Garcia, Gemma

    2007-01-01

    The oxidation behavior of a commercially available Fe–22Cr alloy coated with a Co3O4 layer by metal organic—chemical vapor deposition was investigated in air with 1% H2O at 1,173 K and compared to the oxidation behavior of the non-coated alloy. The oxide morphology was examined with X......-ray diffraction, electron microscopy, and energy dispersive X-ray spectroscopy. Cr2O3 developed in between the Co3O4 coating and the alloy, while alloying elements of the substrate were incorporated into the coating. Particular attention was devoted to possible sources of growth stresses and the effect...... of the growth stresses on microstructure evolution in the scales that developed on the non-coated and the coated Fe–22Cr alloy. Microstructural features suggested that scale spallation on coated Fe–22Cr occurred as a result of superimposing thermal stresses during cooling onto the growth stresses, that had...

  12. High-temperature plastic flow of a precipitation-hardened FeCoNiCr high entropy alloy

    Energy Technology Data Exchange (ETDEWEB)

    He, J.Y.; Wang, H.; Wu, Y.; Liu, X.J. [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Nieh, T.G. [Department of Materials Science and Engineering, the University of Tennessee, Knoxville, TN 37996 (United States); Lu, Z.P., E-mail: luzhaoping@163.com [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China)

    2017-02-16

    In this work, we systematically investigated flow behavior of a high entropy alloy (HEA) strengthened by coherent γ′ precipitates in the temperature range of 1023–1173 K. In contrast to the single-phase FeCoNiCrMn HEA, this precipitate-hardened alloy, i.e., (FeCoNiCr){sub 94}Ti{sub 2}Al{sub 4}, exhibited large reduction of the steady-state strain rate (by ~2 orders of magnitude) or drastic enhancement in flow stress, indicating significant improvement in high-temperature properties. Our results showed that the deformation could be divided into two regimes. At temperatures below 1123 K, coherent γ′ precipitates effectively blocked the dislocation motion, thus resulted in a threshold stress effect. Above 1123 K, however, γ′ particles dissolved and the deformation was controlled by the ordinary dislocation climb mechanism. In addition, we conducted transmission electron microscopy to characterize dislocation-precipitate interaction to provide microstructural evidences to support our conclusion of the specific deformation mechanisms in the two temperature regimes.

  13. Atomic scale study of grain boundary segregation before carbide nucleation in Ni-Cr-Fe Alloys

    Science.gov (United States)

    Li, Hui; Xia, Shuang; Liu, Wenqing; Liu, Tingguang; Zhou, Bangxin

    2013-08-01

    Three dimensional chemical information concerning grain boundary segregation before carbide nucleation was characterized by atom probe tomography in two Ni-Cr-Fe alloys which were aged at 500 °C for 0.5 h after homogenizing treatment. B, C and Si atoms segregation at grain boundary in Alloy 690 was observed. B, C, N and P atoms segregation at grain boundary in 304 austenitic stainless steel was observed. C atoms co-segregation with Cr atoms at the grain boundaries both in Alloy 690 and 304 austenitic stainless steel was found, and its effect on the carbide nucleation was discussed. The amount of each segregated element at grain boundaries in the two Ni-Cr-Fe alloys were analyzed quantitatively. Comparison of the grain boundary segregation features of the two Ni-Cr-Fe alloys were carried out based on the experimental results. The impurity and solute atoms segregate inhomogeneously in the same grain boundary both in 304 SS and Alloy 690. The grain boundary segregation tendencies (Sav) are B (11.8 ± 1.4) > P (5.4 ± 1.4) > N (4.7 ± 0.3) > C (3.7 ± 0.4) in 304 SS, and B (6.9 ± 0.9) > C (6.7 ± 0.4) > Si (1.5 ± 0.2) in Alloy 690. Cr atoms may co-segregate with C atoms at grain boundaries before carbide nucleation at the grain boundaries both in 304 SS and Alloy 690. Ni atoms generally deplete at grain boundary both in 304 SS and Alloy 690. The literature shows that the Ni atoms may co-segregate with P atoms at grain boundaries [28], but the P atoms segregation do not leads to Ni segregation in the current study. In the current study, Fe atoms may segregate or deplete at grain boundary in Alloy 690. But Fe atoms generally deplete at grain boundary in 304 SS. B atoms have the strongest grain boundary segregation tendency both in 304 SS and Alloy 690. The grain boundary segregation tendency and Gibbs free energy of B in 304 SS is higher than in Alloy 690. C atoms are easy to segregate at grain boundaries both in 304 SS and Alloy 690. The grain boundary segregation

  14. Microstructures of neutron-irradiated Fe-12Cr-XMn (X=15-30) ternary alloys

    International Nuclear Information System (INIS)

    Miyahara, K.; Hosoi, Y.; Garner, F.A.

    1992-01-01

    The objective of this effort is to determine the factors which control the stability of irradiated alloys proposed for reduced activation applications. The Fe-Cr-Mn alloy system is being studied as an alternative to the Fe-Cr-Ni system because of the need to reduce long-term radioactivation in fusion-power devices. In this study, four Fe-12Cr-XMn (X =15, 20, 25, 30 wt%) alloys were irradiated in the Fast Flux Test Facility to 20 dpa at 643K and 40 dpa at 679, 793, and 873K to investigate the influence of manganese content on void swelling and phase stability. The results confirm and expand the results of earlier studies that indicate that the Fe-Cr-Mn system is relatively unstable compared to that of the Fe-Cr-Ni system, with alpha and sigma phases forming as a consequence of thermal aging or high temperature irradiation

  15. Solubility of sulfur in Fe-Cr-Ni alloys

    International Nuclear Information System (INIS)

    Bogolyubskij, S.D.; Petrova, E.F.; Rogov, A.I.; Shvartsman, L.A.

    1979-01-01

    The solubility of 35 S was determined in Fe-Cr-Ni alloys in the range of temperatures between 910 and 1050 deg C by the method of radiometric analysis. It was found that the solubility of sulfur increases with the concentration of chromium in alloys with 20% Ni

  16. Growth of single-crystal W whiskers during humid H2/N2 reduction of Ni, Fe-Ni, and Co-Ni doped tungsten oxide

    International Nuclear Information System (INIS)

    Wang Shiliang; He Yuehui; Zou Jou; Wang Yong; Huang Han

    2009-01-01

    Numbers of W whiskers were obtained by reducing Ni, Ni-Fe, and Ni-Co doped tungsten oxide in a mixed atmosphere of humid H 2 and N 2 . The phases and morphologies of the reduction products were characterized by XRD and SEM. Intensive TEM and EDS analyses showed that the obtained whiskers were W single crystals which typical have alloyed particles (Ni-W, Fe-Ni, or Co-Ni-W) at the growth tips. The formed W whiskers were presumed to be induced by the alloyed particles. Our experimental results revealed that, during the reduction process of tungsten oxide, the pre-reduced Ni, Fe-Ni, or Co-Ni particles not only served as nucleation aids for the initial growth of W phase from W oxide but also played the roles of catalysts during the reductive decomposition of gaseous WO 2 (OH) 2 .

  17. Production and characterization of stainless steel based Fe-Cr-Ni-Mn-Si(-Co) shape memory alloys

    International Nuclear Information System (INIS)

    Otubo, J.

    1995-01-01

    It is well known that the Fe based alloys can exhibit shape memory effect due to the γ to ε martensitic transformation. The effect may not be as striking as observed in the NiTi alloy but it might become attractive from the practical point of view. In this work, two compositions of Fe-Cr-Ni-Mn-Si(-Co) stainless steel based shape memory alloy, prepared by the VIM technique, will be presented. The results are good with shape recovery of 95% for a pre-strain of 4% after some training cycles. In terms of workability the alloys produced are worse than the usual AISI304. However, adjusting the thermo-mechanical processing, it is perfectly possible to produce wire as thin as 1,20mm in dia. or down. (orig.)

  18. The Role of Carbon in Grain Refinement of Cast CrFeCoNi High-Entropy Alloys

    Science.gov (United States)

    Liu, X. W.; Liu, L.; Liu, G.; Wu, X. X.; Lu, D. H.; Yao, J. Q.; Jiang, W. M.; Fan, Z. T.; Zhang, W. B.

    2018-06-01

    As a promising engineering material, high-entropy alloys (HEAs) CrFeCoNi system has attracted extensive attention worldwide. Their cast alloys are of great importance because of their great formability of complex components, which can be further improved through the transition of the columnar to equiaxed grains and grain refinement. In the current work, the influence of C contents on the grain structures and mechanical properties of the as-cast high-entropy alloy CrFeCoNi was chosen as the target and systematically studied via a hybrid approach of the experiments and thermodynamic calculations. The alloys with various C additions were prepared by arc melting and drop cast. The as-cast macrostructure and microstructure were characterized using optical microscopy, scanning electron microscopy, and transmission electron microscopy. The cast HEAs transform from coarse columnar grains into equiaxed grains with the C level increased to ≥ 2 at. pct and the size of equiaxed grains is further decreased with the increasing C addition. It is revealed that the interdendritic segregation of Cr and C results in grain boundary precipitation of M23C6 carbides. The grain refinement is attributed to the additional constitutional supercoiling from the C addition. The yield stress and tensile strength at room temperature are improved due to the transition of columnar to equiaxed grains and grain refinement.

  19. Equilibrium phase of high-entropy FeCoNiCrCu0.5 alloy at elevated temperature

    International Nuclear Information System (INIS)

    Lin, C.-M.; Tsai, H.-L.

    2010-01-01

    The phase transformations of FeCoNiCrCu 0.5 alloy with the as-cast structure and heat-treated structures were studied. The as-cast alloy specimens were first heated at 1050 o C with a holding time of 1 h. Serial heat-treatment processes at 350 o C, 500 o C, 650 o C, 800 o C, 950 o C, 1100 o C, 1250 o C and 1350 o C with a holding time of 24 h were then carried out to understand the phase evolution and the relationship between the microstructure and the hardness of the specimens. The microstructures were investigated and chemical analyses performed by optical microscopy (OM), scanning elector microscopy (SEM), X-ray diffractometer (XRD) and transmission elector microscopy (TEM). The results show that FCC peaks were observed from the X-ray diffraction of the as-cast specimens and a precipitate phase was present in the specimens that had been heated to 950 o C. The hardness of the FeCoNiCrCu 0.5 alloy remained unchanged in the specimens that underwent various heat treatments that were applied in this study.

  20. Effects of torsional deformation on the microstructures and mechanical properties of a CoCrFeNiMo0.15 high-entropy alloy

    Science.gov (United States)

    Wu, Wenqian; Guo, Lin; Liu, Bin; Ni, Song; Liu, Yong; Song, Min

    2017-12-01

    The effects of torsional deformation on the microstructures and mechanical properties of a CoCrFeNiMo0.15 high-entropy alloy have been investigated. The torsional deformation generates a gradient microstructure distribution due to the gradient torsional strain. Both dislocation activity and deformation twinning dominated the torsional deformation process. With increasing the torsional equivalent strain, the microstructural evolution can be described as follows: (1) formation of pile-up dislocations parallel to the trace of {1 1 1}-type slip planes; (2) formation of Taylor lattices; (3) formation of highly dense dislocation walls; (3) formation of microbands and deformation twins. The extremely high deformation strain (strained to fracture) results in the activation of wavy slip. The tensile strength is very sensitive to the torsional deformation, and increases significantly with increasing the torsional angle.

  1. High pressure synthesis of a hexagonal close-packed phase of the high-entropy alloy CrMnFeCoNi

    Energy Technology Data Exchange (ETDEWEB)

    Tracy, Cameron L.; Park, Sulgiye; Rittman, Dylan R.; Zinkle, Steven J.; Bei, Hongbin; Lang, Maik; Ewing, Rodney C.; Mao, Wendy L.

    2017-05-25

    High-entropy alloys, near-equiatomic solid solutions of five or more elements, represent a new strategy for the design of materials with properties superior to those of conventional alloys. However, their phase space remains constrained, with transition metal high-entropy alloys exhibiting only face- or body-centered cubic structures. Here, we report the high-pressure synthesis of a hexagonal close-packed phase of the prototypical high-entropy alloy CrMnFeCoNi. This martensitic transformation begins at 14 GPa and is attributed to suppression of the local magnetic moments, destabilizing the initial fcc structure. Similar to fcc-to-hcp transformations in Al and the noble gases, the transformation is sluggish, occurring over a range of >40 GPa. However, the behaviour of CrMnFeCoNi is unique in that the hcp phase is retained following decompression to ambient pressure, yielding metastable fcc-hcp mixtures. This demonstrates a means of tuning the structures and properties of high-entropy alloys in a manner not achievable by conventional processing techniques.

  2. Microstructure and mechanical properties of friction stir welded and laser welded high entropy alloy CrMnFeCoNi

    Science.gov (United States)

    Jo, Min-Gu; Kim, Han-Jin; Kang, Minjung; Madakashira, Phaniraj P.; Park, Eun Soo; Suh, Jin-Yoo; Kim, Dong-Ik; Hong, Sung-Tae; Han, Heung Nam

    2018-01-01

    The high entropy alloy CrMnFeCoNi has been shown to have promising structural properties. For a new alloy to be used in a structural application it should be weldable. In the present study, friction stir welding (FSW) and laser welding (LW) techniques were used to butt weld thin plates of CrMnFeCoNi. The microstructure, chemical homogeneity and mechanical behavior of the welds were characterized and compared with the base metal. The tensile stress-strain behavior of the welded specimens were reasonable when compared with that of the base metal. FSW refined the grain size in the weld region by a factor of ˜14 when compared with the base metal. High-angle annular dark field transmission electron microscopy in combination with energy dispersive X-ray spectroscopy showed chemical inhomogeneity between dendritic and interdendritic regions in the fusion zone of LW. Large fluctuations in composition (up to 15 at%) did not change the crystal structure in the fusion zone. Hardness measurements were carried out in the weld cross section and discussed in view of the grain size, low angle grain boundaries and twin boundaries in FSW specimens and the dendritic microstructure in LW specimens.

  3. Density of liquid NiCoAlCr quarternary alloys measured by modified sessile drop method

    Institute of Scientific and Technical Information of China (English)

    FANG Liang; ZHANG Shu-fang; XIAO Feng; YANG Ling-chuan; DONG Jian-xin; CAO Chun-lan; TAO Zai-nan; K. MUKAI

    2006-01-01

    The densities of liquid NiCoAlCr quaternary alloys with a fixed molar ratio of Ni to Co to Al (x(Ni)-x(Co)-x(Al)≈73-12-15) which is close to the average value of the commercial Ni-based superalloys TMS75, INCO713, CM247LC and CMSX-4, and the mass fraction of chromium changes from 0 to 9% were measured by a modified sessile drop method. It is found that with increasing temperature and chromium concentration in the alloys, the densities of the liquid NiCoAlCr quaternary alloys decrease, whereas the molar volume of the liquid NiCoAlCr quaternary alloys increases. And the liquid densities of NiCoAlCr quaternary alloys calculated from the partial molar volumes of nickel, cobalt, aluminum and chromium in the corresponding Ni-bases binary alloys are in good agreement with the experimental ones, i.e. within the error tolerance range the densities of the liquid Ni-based multi-component alloys can be predicted from the partial volumes of elements in Ni-based binary alloys in liquid state. The molar volume of liquid NiCoAlCr binary alloy shows a negative deviation from the ideal linear mixing and the deviation changes small with the increase of chromium concentration at the same temperature.

  4. Experimental observations of transient phases during long-range ordering to Ni4Mo in a Ni-Mo-Fe-Cr alloy

    International Nuclear Information System (INIS)

    Tawancy, H.M.; Aboelfotoh, M.O.

    1987-01-01

    Experimental observations are reported of transient phases which form during long-range ordering to Ni 4 Mo (f.c.c. → Dl/sub a/ superlattice) in the quaternary alloy Ni-19.2 at% Mo-1.2 at% Fe-1.06 at% Cr using electron diffraction. In the early stages of ordering during isothermal annealing, diffuse intensity maxima centered at the short-range order reflections (1 1/2 O)/sub f.c.c./ and along /sub f.c.c./ directions are observed. Subsequently, a DO 22 superlattice is generated from the short-range order state. The coexistence of the DO 22 , Pt 2 Mo-type, and Dl/sub a/ superlattices is observed in this alloy system which indicates that these three superlattices have similar energy. With continued annealing, both the DO 22 and Pt 2 Mo-type superlattices have similar energy. With continued annealing, both the DO 22 and Pt 2 Mo-type superlattices disappear, indicating that they are transient phases. These results are not inconsistent with the theoretical treatments of ordered alloys which are based on an Ising model with pairwise atomic interactions. (author)

  5. Improvement of antiscuff properties and thermal stability of alloys of the Fe-Cr-Ni-Si system used for building-up of fittings

    International Nuclear Information System (INIS)

    Luzhanskij, I.B.; Runov, A.E.; Gel'man, A.S.; Stepin, V.S.

    1978-01-01

    Studied was the influence of the system and the degree of alloying of alloys of the Fe-Cr-Ni-Si system on their operational characteristics in the operation mode of the energy armature of superhigh parameters. The TsN18 alloy has been developed (containing 0.1 to 0.2% C; 3.5 to 6.0% Si; 0.5 to 3.0% Mn; 16 to 17% Cr; 10.5 to 12% Ni; 1.5 to 3% Mo; the balance being Fe), bombining a high resistance to scuffing with a fairly high heat resistance; the alloy lending itself to building up and to machining. The dependence of the wear resistance of the alloys of the Fe-Cr-Ni-Si system on two factors has been established; namely, - the antifriction characteristics of the film of secondary structures, and physico-mechanical properties of the alloy

  6. Note: Erosion of W-Ni-Fe and W-Cu alloy electrodes in repetitive spark gaps.

    Science.gov (United States)

    Wu, Jiawei; Han, Ruoyu; Ding, Weidong; Qiu, Aici; Tang, Junping

    2018-02-01

    A pair of W-Ni-Fe and W-Cu electrodes were tested under 100 kA level pulsed currents for 10 000 shots, respectively. Surface roughness and morphology characteristics of the two pairs of electrodes were obtained and compared. Experimental results indicated cracks divided the W-Cu electrode surface to polygons while the W-Ni-Fe electrode surface remained as a whole with pits and protrusions. Accordingly, the surface roughness of W-Ni-Fe electrodes increased to ∼3 μm while that of W-Cu electrodes reached ∼7 μm at the end of the test. The results reveal that the W-Ni-Fe alloy has a better erosion resistance and potential to be further applied in spark gaps.

  7. Microstructure, thermophysical and electrical properties in AlxCoCrFeNi (0 ≤ x ≤2) high-entropy alloys

    International Nuclear Information System (INIS)

    Chou, H.-P.; Chang, Y.-S.; Chen, S.-K.; Yeh, J.-W.

    2009-01-01

    Al x CoCrFeNi (0 ≤ x ≤2) alloys were prepared by an arc remelter and investigated. With increasing x, the Al x CoCrFeNi alloys change from single FCC phase to single BCC phase with a transition duplex FCC/BCC region. The weak X-ray diffraction intensities indicate severe X-ray scattering effect of lattice in these high-entropy alloys. Electrical conductivity and thermal conductivity much smaller than those of pure component metals is ascribed as due to this lattice effect. The behavior of electrical conductivity and thermal conductivity can be divided into three parts according to microstructure. Both values of electrical conductivity and thermal conductivity decrease with increasing x in single-phase regions. Values of electrical conductivity and thermal conductivity are even higher than those in the duplex phase region because of the additional scattering effect of FCC/BCC phase boundaries in the alloys. Relative contribution of electron and phonon to electrical resistivity and thermal conductivity is evaluated in this study. It is shown that both electron and phonon components are comparable in these high-entropy alloys, and their transport properties are similar to that of semi-metal.

  8. Design of Novel Precipitate-Strengthened Al-Co-Cr-Fe-Nb-Ni High-Entropy Superalloys

    Science.gov (United States)

    Antonov, Stoichko; Detrois, Martin; Tin, Sammy

    2018-01-01

    A series of non-equiatomic Al-Co-Cr-Fe-Nb-Ni high-entropy alloys, with varying levels of Co, Nb and Fe, were investigated in an effort to obtain microstructures similar to conventional Ni-based superalloys. Elevated levels of Co were observed to significantly decrease the solvus temperature of the γ' precipitates. Both Nb and Co in excessive concentrations promoted the formation of Laves and NiAl phases that formed either during solidification and remained undissolved during homogenization or upon high-temperature aging. Lowering the content of Nb, Co, or Fe prevented the formation of the eutectic type Laves. In addition, lowering the Co content resulted in a higher number density and volume fraction of the γ' precipitates, while increasing the Fe content led to the destabilization of the γ' precipitates. Various aging treatments were performed which led to different size distributions of the strengthening phase. Results from the microstructural characterization and hardness property assessments of these high-entropy alloys were compared to a commercial, high-strength Ni-based superalloy RR1000. Potentially, precipitation-strengthened high-entropy alloys could find applications replacing Ni-based superalloys as structural materials in power generation applications.

  9. Effect of iron content on the structure and mechanical properties of Al{sub 25}Ti{sub 25}Ni{sub 25}Cu{sub 25} and (AlTi){sub 60-x}Ni{sub 20}Cu{sub 20}Fe{sub x} (x=15, 20) high-entropy alloys

    Energy Technology Data Exchange (ETDEWEB)

    Fazakas, É., E-mail: eva.fazakas@bayzoltan.hu [WPI-Advaced Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-Ku, Sendai 980-8577 (Japan); Wigner Research Center for Physics, Hungarian Academy of Sciences, H-1525, P.O.B. 49 (Hungary); Bay Zoltán Nonprofit Ltd., For Applied Research H-1116 Budapest, Fehérvári út 130 (Hungary); Zadorozhnyy, V. [National University of Science and Technology «MISIS», Leninsky prosp., 4, Moscow 119049 (Russian Federation); Louzguine-Luzgin, D.V. [WPI-Advaced Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-Ku, Sendai 980-8577 (Japan)

    2015-12-15

    Highlights: • Three new refractory alloys namely: Al{sub 25}Ti{sub 25}Ni{sub 25}Cu{sub 25}, Al{sub 22.5}Ti{sub 22.5}Ni{sub 20}Cu{sub 20}Fe{sub 15} and Al{sub 20}Ti{sub 20}Ni{sub 20}Cu{sub 20}Fe{sub 20}, were produced by induction-melting and casting. • This kind of alloys exhibits high resistance to annealing softening. • Most the alloys in the annealed state possess even higher Vickers microhardness than the as-cast alloys. • The Al{sub 22.5}Ti{sub 22.5}Ni{sub 20}Cu{sub 20}Fe{sub 15} and Al{sub 20}Ti{sub 20}Ni{sub 20}Cu{sub 20}Fe{sub 20} alloys annealed at 973 K show the highest compressive stress and ductility values. - Abstract: In this work, we investigated the microstructure and mechanical properties of Al{sub 25}Ti{sub 25}Ni{sub 25}C{sub u25} Al{sub 22.5}Ti{sub 22.5}Ni{sub 20}Cu{sub 20}Fe{sub 15} and Al{sub 20}Ti{sub 20}Ni{sub 20}Cu{sub 20}Fe{sub 20} high entropy alloys, produced by arc melting and casting in an inert atmosphere. The structure of these alloys was studied by X-ray diffractometry and scanning electron microscopy. The as-cast alloys were heat treated at 773, 973 and 1173 K for 1800 s to investigate the effects of aging on the plasticity, hardness and elastic properties. Compared to the conventional high-entropy alloys the Al{sub 25}Ti{sub 25}Ni{sub 25}Cu{sub 25}, Al{sub 22.5}Ti{sub 22.5}Ni{sub 20}Cu{sub 20}Fe{sub 15} and Al{sub 20}Ti{sub 20}Ni{sub 20}Cu{sub 20}Fe{sub 20} alloys are relatively hard and ductile. Being heat treated at 973 K the Al{sub 22.5}Ti{sub 22.5}Ni{sub 20}Cu{sub 20}Fe{sub 15} alloy shows considerably high strength and relatively homogeneous deformation under compression. The plasticity, hardness and elastic properties of the studied alloys depend on the fraction and intrinsic properties of the constituent phases. Significant hardening effect by the annealing is found.

  10. Influence of yttria surface modification on high temperature corrosion of porous Ni22Cr alloy

    DEFF Research Database (Denmark)

    Karczewski, Jakub; Dunst, Katarzyna; Jasinski, Piotr

    2017-01-01

    Protective coatings for porous alloys for high temperature use are relatively new materials. Their main drawback is high temperature corrosion. In this work protective coatings based the on Y-precursor infiltrated into the sintered Ni22Cr alloys are studied at 700°C. Effects of the amount...... of the protective phase on the resulting corrosion properties are evaluated in air and humidified hydrogen. Weight gain of the samples, their open porosities and microstructures are analyzed and compared. Results show, that by the addition of even a minor amount of the Y-precursor corrosion rates can be decreased...

  11. Precipitation sequences in austenitic Fe-22Cr-21Ni-6Mo-(N) stainless steels

    International Nuclear Information System (INIS)

    Kim, S.-J.; Lee, T.-H.

    1999-01-01

    Precipitation sequence of nitrogen containing Fe-22Cr-21Ni-6Mo-N austenitic stainless steel has been investigated after aging at high temperatures, and compared with nitrogen free steel. The σ phases and M 23 C 6 carbides were observed along the grain boundaries as well as in the matrix in both of the solution treated specimens. The M 6 C carbides and chi phase appeared successively in between 3 hours and 24 hours depending on the nitrogen content. Main difference in aging behavior was the precipitation of fine nitrides. Aging for 24 hours and 168 hours of nitrogen containing steel resulted in the formation of fine Cr 2 N and faceted AlN nitrides. The crystallography, structure and morphology were analyzed with analytical electron microscopy. (orig.)

  12. An assessment of the lattice strain in the CrMnFeCoNi high-entropy alloy

    International Nuclear Information System (INIS)

    Owen, L.R.; Pickering, E.J.; Playford, H.Y.; Stone, H.J.; Tucker, M.G.; Jones, N.G.

    2017-01-01

    The formation of single phase solid solutions from combinations of multiple principal elements, with differing atomic radii, has led to the suggestion that the lattices of high-entropy alloys (HEAs) must be severely distorted. To assess this hypothesis, total scattering measurements using neutron radiation have been performed on the CrMnFeCoNi alloy and compared with similar data from five compositionally simpler materials within the same system. The Bragg diffraction patterns from all of the studied materials were similar, consistent with a face-centered cubic structure, and none showed the pronounced dampening that would be expected from a highly distorted lattice. A more detailed evaluation of the local lattice strain was made by considering the first six coordination shells in the pair distribution functions (PDF), obtained from the total scattering data. Across this range, the HEA exhibited the broadest PDF peaks but these widths were not disproportionately larger than those of the simpler alloys. In addition, of all the materials considered, the HEA was at the highest homologous temperature, and hence the thermal vibrations of the atoms would be greatest. Consequently, the level of local lattice strain required to rationalise a given PDF peak width would be reduced. As a result, the data presented in this study do not indicate that the local lattice strain in the equiatomic CrMnFeCoNi HEA is anomalously large.

  13. Microstructure and Wear Behavior of Atmospheric Plasma-Sprayed AlCoCrFeNiTi High-Entropy Alloy Coating

    Science.gov (United States)

    Tian, Li-Hui; Xiong, Wei; Liu, Chuan; Lu, Sheng; Fu, Ming

    2016-12-01

    Due to the advantages such as high strength, high hardness and good wear resistance, high-entropy alloys (HEAs) attracted more and more attentions in recent decades. However, most reports on HEAs were limited to bulk materials. Although a few of studies on atmospheric plasma-sprayed (APS) HEA coatings were carried out, the wear behavior, especially the high-temperature wear behavior of those coatings has not been investigated till now. Therefore, in this study, APS was employed to deposit AlCoCrFeNiTi high-entropy alloy coating using mechanically alloyed AlCoCrFeNiTi powder as the feedstock. The phase structure of the initial powder, the feedstock powder and the as-sprayed coating was examined by an x-ray diffractometer. The surface morphology of the feedstock powder and the microstructure of the as-sprayed coating were analyzed by field emission scanning electron microscopy and energy-dispersive spectroscopy. The bonding strength and the microhardness of the as-sprayed coating were tested. The wear behavior of the coating at 25, 500, 700 and 900 °C was investigated by analysis of the wear surface morphology and measurements of the volume wear rate and the coefficient of friction.

  14. High-temperature mechanical properties of high-purity 70 mass% Cr-Fe alloy

    Energy Technology Data Exchange (ETDEWEB)

    Asahina, M.; Harima, N.; Takaki, S.; Abiko, K. [Tohoku Univ., Sendai (Japan). Inst. for Materials Research

    2002-01-16

    An ingot of high-purity 70 mass% Cr-Fe alloy was prepared by high-frequency induction melting in a high-purity argon atmosphere using a cold copper crucible. Its tensile properties such as hot-ductility and tensile strength were measured, and compared with the results for a high-purity 50 mass% Cr-Fe alloy, a high-purity 60 mass% Cr-Fe alloy and a Ni-based super-alloy. The formation of {sigma}-phase was also examined. The purity of a 70Cr-Fe alloy (70 mass% Cr-Fe alloy) ingot is more than 99.98 mass% and the total amount of gaseous impurities (C, N, O, S, H) in the 70Cr-Fe alloy is 69.9 mass ppm. The strength of the 70Cr-Fe alloy is higher than those of the 60Cr-Fe alloy and the 50Cr-Fe alloy at the temperatures between 293 and 1573 K, without decrease in ductility with increasing Cr content. The 70Cr-Fe alloy also possesses excellent high-temperature ductility. The {sigma}-phase was not observed after aging of 3.6 Ms at 873 K. Consequently, the 70Cr-Fe alloy is an excellent alloy as the base of super heat-resistant alloys. (orig.)

  15. Influence of the Cr and Ni concentration in CoCr and CoNi alloys on the structural and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Aubry, E. [Nipson Technology, 12 Avenue des Trois chênes, Techn’Hom 3, Belfort 90000 (France); Liu, T. [Institut Jean Lamour, UMR 7198 CNRS-Université de Lorraine, Vandoeuvre-lès-Nancy 54506 (France); Billard, A. [IRTES-LERMPS EA 7274, UTBM, Site de Montbéliard, Belfort Cedex 90010 (France); Dekens, A. [Institut Jean Lamour, UMR 7198 CNRS-Université de Lorraine, Vandoeuvre-lès-Nancy 54506 (France); Perry, F. [PVDco, 30 rue de Badménil, Baccarat 54120 (France); Mangin, S.; Hauet, T. [Institut Jean Lamour, UMR 7198 CNRS-Université de Lorraine, Vandoeuvre-lès-Nancy 54506 (France)

    2017-01-15

    The crystalline and magnetic properties of micron thick magnetron sputtered Co{sub 1−x}Cr{sub x} and Co{sub 1−x}Ni{sub x} alloy films are analyzed in the view of their implementation as semi-hard magnets. All of the tested films crystallize in an hcp lattice, at least up to 35 at% of alloying elements (Cr or Ni). The structural study shows that the ratio of hcp phase with [0001] axis orientated perpendicular to the film as compared with in-plane orientation increases (resp. decreases), when Ni (resp. Cr) concentration increases independently of the post-annealing temperature. The orientation of the magnetization results from the competition between the demagnetization field which tends to align the magnetization in plane and the crystalline anisotropy which tends to maintain the magnetization along the [0001] axis. Interestingly, we find that, although Co and Ni are very similar atoms, Co{sub 1−x}Ni{sub x} alloys crystalline anisotropy can be strongly increased and reach up to twice the anisotropy of the best Co{sub 1−x}Cr{sub x} alloy, while maintaining a magnetization at saturation above 1200 kA/m. The thermal stability of the structural and magnetic properties of both alloys is demonstrated for an annealing temperature up to 300 °C. - Highlights: • Sputtered CoCr and CoNi films are analyzed for their semi-hard magnetic properties. • CoNi alloys exhibits higher saturation magnetization and crystalline anisotropy. • These evolutions can be directly correlated to the quality of hcp crystal orientation. • Thermal stability of structural and magnetic properties is demonstrated up to 300 °C.

  16. Hyperfine interaction and some thermomagnetic properties of amorphous and partially crystallized Fe70−xMxMo5Cr4Nb6B15 (M = Co or Ni, x = 0 or 10 alloys

    Directory of Open Access Journals (Sweden)

    Rzącki Jakub

    2015-03-01

    Full Text Available As revealed by Mössbauer spectroscopy, replacement of 10 at.% of iron in the amorphous Fe70Mo5Cr4Nb6B15 alloy by cobalt or nickel has no effect on the magnetic structure in the vicinity of room temperature, although the Curie point moves from 190 K towards ambient one. In the early stages of crystallization, the paramagnetic crystalline Cr12Fe36Mo10 phase appears before α-Fe or α-FeCo are formed, as is confirmed by X-ray diffractometry and transmission electron microscopy. Creation of the crystalline Cr12Fe36Mo10 phase is accompanied by the amorphous ferromagnetic phase formation at the expense of amorphous paramagnetic one.

  17. Structure change in 25 Cr - 20 Ni steels as a function of their Cr, Ni, Si and W content

    International Nuclear Information System (INIS)

    Gribaudo, L.M.; Durand, F.; Durand-Charre, M.

    1983-01-01

    The influence of varying the Cr, Ni, Si and W concentrations on the type and composition of the carbides of solidification and on the phase shift temperature is studied with 18 alloys of composition close to stainless steel-25-20 (AISI 310) composition. Experimental techniques used are differential thermal analysis, microprobe and scanning electron microscope. Crystallization is interpreted with the equilibrium diagram Ni-Cr-C. The formation of the interdendritic σ phase for a chromium rich alloys is interpreted with the phase equilibrium diagram of Fe-Ni-Cr-C. Mechanical properties and corrosion resistance are dependent on the morphology of the carbides M 7 C 3 and M 23 C 6 [fr

  18. Corrosion of alloy 22 in phosphate and chloride containing solutions

    International Nuclear Information System (INIS)

    Carranza, Ricardo M.

    2007-01-01

    Alloy C-22 is a Ni-based alloy (22% Cr, 13% Mo, 3% W y 3% Fe in weight per cent) that exhibits an excellent uniform and localized corrosion resistance due to its protective passive film. It was designed to resist the most aggressive environments for industrial applications. Alloy 22 is one of the candidates to be considered for the outer shell of the canister that would contain high level radioactive nuclear wastes. The effect of phosphate ion in chloride containing solutions at 90 C degrees was studied under aggressive conditions were this material might be susceptible to crevice corrosion. The electrolyte solution, which consisted of 1M NaCl and different phosphate concentrations (between 10 -3 M and 1M), was deoxygenated by bubbling with nitrogen. Electrochemical tests, electron microscope observations (SEM) and energy dispersive spectrometer analysis (EDS) were conducted. Crevice corrosion was not detected and the comparison of the potentiodynamic polarization tests showed an increase of the passivity range in phosphate containing solutions. The passive current value was 1 μA/cm 2 approximately in all the tests that were performed in this work. The differences in composition of the anodic film formed on the samples suggest that phosphate is responsible for the increase of the passivity range by incorporation to the passive film. (author)

  19. Microstructural origins of high strength and high ductility in an AlCoCrFeNi2.1 eutectic high-entropy alloy

    International Nuclear Information System (INIS)

    Gao, Xuzhou; Lu, Yiping; Zhang, Bo; Liang, Ningning; Wu, Guanzhong; Sha, Gang; Liu, Jizi; Zhao, Yonghao

    2017-01-01

    Recent studies indicate that eutectic high-entropy alloys can simultaneously possess high strength and high ductility, which have potential applications in industrial fields. Nevertheless, microstructural origins of the excellent strength–ductility combination remain unclear. In this study, an AlCoCrFeNi 2.1 eutectic high-entropy alloy was prepared with face-centered cubic (FCC)(L1 2 )/body-centered-cubic (BCC)(B2) modulated lamellar structures and a remarkable combination of ultimate tensile strength (1351 MPa) and ductility (15.4%) using the classical casting technique. Post-deformation transmission electron microscopy revealed that the FCC(L1 2 ) phase was deformed in a matter of planar dislocation slip, with a slip system of {111} <110>, and stacking faults due to low stacking fault energy. Due to extreme solute drag, high densities of dislocations are distributed homogeneously at {111} slip plane. In the BCC(B2) phase, some dislocations exist on two {110} slip bands. The atom probe tomography analysis revealed a high density of Cr-enriched nano-precipitates, which strengthened the BCC(B2) phase by Orowan mechanisms. Fracture surface observation revealed a ductile fracture in the FCC(L1 2 ) phase and a brittle-like fracture in the BCC(B2) lamella. The underlying mechanism for the high strength and high ductility of AlCoCrFeNi 2.1 eutectic high-entropy alloy was finally analyzed based on the coupling between the ductile FCC(L1 2 ) and brittle BCC(B2) phases.

  20. Effect of iron content on the structure and mechanical properties of Al25Ti25Ni25Cu25 and (AlTi)60-xNi20Cu20Fex (x=15, 20) high-entropy alloys

    International Nuclear Information System (INIS)

    Fazakas, É.; Zadorozhnyy, V.; Louzguine-Luzgin, D.V.

    2015-01-01

    Highlights: • Three new refractory alloys namely: Al 25 Ti 25 Ni 25 Cu 25 , Al 22.5 Ti 22.5 Ni 20 Cu 20 Fe 15 and Al 20 Ti 20 Ni 20 Cu 20 Fe 20 , were produced by induction-melting and casting. • This kind of alloys exhibits high resistance to annealing softening. • Most the alloys in the annealed state possess even higher Vickers microhardness than the as-cast alloys. • The Al 22.5 Ti 22.5 Ni 20 Cu 20 Fe 15 and Al 20 Ti 20 Ni 20 Cu 20 Fe 20 alloys annealed at 973 K show the highest compressive stress and ductility values. - Abstract: In this work, we investigated the microstructure and mechanical properties of Al 25 Ti 25 Ni 25 C u25 Al 22.5 Ti 22.5 Ni 20 Cu 20 Fe 15 and Al 20 Ti 20 Ni 20 Cu 20 Fe 20 high entropy alloys, produced by arc melting and casting in an inert atmosphere. The structure of these alloys was studied by X-ray diffractometry and scanning electron microscopy. The as-cast alloys were heat treated at 773, 973 and 1173 K for 1800 s to investigate the effects of aging on the plasticity, hardness and elastic properties. Compared to the conventional high-entropy alloys the Al 25 Ti 25 Ni 25 Cu 25 , Al 22.5 Ti 22.5 Ni 20 Cu 20 Fe 15 and Al 20 Ti 20 Ni 20 Cu 20 Fe 20 alloys are relatively hard and ductile. Being heat treated at 973 K the Al 22.5 Ti 22.5 Ni 20 Cu 20 Fe 15 alloy shows considerably high strength and relatively homogeneous deformation under compression. The plasticity, hardness and elastic properties of the studied alloys depend on the fraction and intrinsic properties of the constituent phases. Significant hardening effect by the annealing is found.

  1. Development of Computational Tools for Modeling Thermal and Radiation Effects on Grain Boundary Segregation and Precipitation in Fe-Cr-Ni-based Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ying [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-08-01

    This work aims at developing computational tools for modeling thermal and radiation effects on solute segregation at grain boundaries (GBs) and precipitation. This report described two major efforts. One is the development of computational tools on integrated modeling of thermal equilibrium segregation (TES) and radiation-induced segregation (RIS), from which synergistic effects of thermal and radiation, pre-existing GB segregation have been taken into consideration. This integrated modeling was used in describing the Cr and Ni segregation in the Fe-Cr-Ni alloys. The other effort is thermodynamic modeling on the Fe-Cr-Ni-Mo system which includes the major alloying elements in the investigated alloys in the Advanced Radiation Resistant Materials (ARRM) program. Through thermodynamic calculation, we provide baseline thermodynamic stability of the hardening phase Ni2(Cr,Mo) in selected Ni-based super alloys, and contribute knowledge on mechanistic understanding on the formation of Ni2(Cr,Mo) in the irradiated materials. The major outcomes from this work are listed in the following: 1) Under the simultaneous thermal and irradiation conditions, radiation-induced segregation played a dominant role in the GB segregation. The pre-existing GB segregation only affects the subsequent radiation-induced segregation in the short time. For the same element, the segregation tendency of Cr and Ni due to TES is opposite to it from RIS. The opposite tendency can lead to the formation of W-shape profile. These findings are consistent with literature observation of the transitory W-shape profile. 2) While TES only affects the distance of one or two atomic layers from GBs, the RIS can affect a broader distance from GB. Therefore, the W-shape due to pre-existing GB segregation is much narrower than that due to composition gradient formed during the transient state. Considering the measurement resolution of Auger or STEM analysis, the segregation tendency due to RIS should play a dominant

  2. Hysteresis properties of the amorphous high permeability Co66Fe3Cr3Si15B13 alloy

    Directory of Open Access Journals (Sweden)

    V. S. Tsepelev

    2018-04-01

    Full Text Available The scaling law of minor loops was studied on an amorphous alloy Co66Fe3Cr3Si15B13 with a very high initial permeability (more than 150000 and low coercivity (about 0.1 A/m. An analytical expression for the coercive force in the Rayleigh region was derived. The coercive force is connected with the maximal magnetic field Hmax via the reversibility coefficient μi/ηHmax. Reversibility coefficient shows the relationship between reversible and irreversible magnetization processes. A universal dependence of magnetic losses for hysteresis Wh on the remanence Br with a power factor of 1.35 is confirmed for a wide range of magnetic fields strengths.

  3. Passive Corrosion Behavior of Alloy 22

    International Nuclear Information System (INIS)

    R.B. Rebak; J.H. Payer

    2006-01-01

    Alloy 22 (NO6022) was designed to stand the most aggressive industrial applications, including both reducing and oxidizing acids. Even in the most aggressive environments, if the temperature is lower than 150 F (66 C) Alloy 22 would remain in the passive state having particularly low corrosion rates. In multi-ionic solutions that may simulate the behavior of concentrated ground water, even at near boiling temperatures, the corrosion rate of Alloy 22 is only a few nano-meters per year because the alloy is in the complete passive state. The corrosion rate of passive Alloy 22 decreases as the time increases. Immersion corrosion testing also show that the newer generation of Ni-Cr-Mo alloys may offer a better corrosion resistance than Alloy 22 only in some highly aggressive conditions such as in hot acids

  4. Creep rupture properties of laves phase strengthened Fe--Ta--Cr--W and Fe--Ta--Cr--W--Mo alloys

    International Nuclear Information System (INIS)

    Singh, S.

    1975-12-01

    A small addition of tungsten (0.5 at. percent) was shown to have an effect similar to that of molybdenum on the phase transformation characteristics of alloy Ta7Cr (with a nominal composition of 1 at. percent Ta, 7 at. percent Cr, balance Fe). The existence of time-temperature dependent transformation behavior in alloy Ta7Cr0.5W was confirmed. The effect of spheroidization time and temperature on creep strength was determined. In addition, effect of mechanical processing prior to aging, on creep strength was also determined. It was also shown that by suitable modifications of composition, the grain boundary film can be broken during the aging treatment without the use of spheroidization treatment. Microhardness, tensile and creep properties have been determined. Optical metallography and scanning electron microscopy have been used to follow the microstructural changes and mode of fracture. The creep rupture strength of alloy Ta7CrW alloy was found to be superior to many of the best commercially available ferritic alloys at 1200 0 F. (21 fig., 8 tables)

  5. Glass forming ability and magnetic properties of Co(40.2−x)Fe(20.1+x)Ni6.7B22.7Si5.3Nb5 (x=0–10) bulk metallic glasses produced by suction casting

    International Nuclear Information System (INIS)

    Sarlar, Kagan; Kucuk, Ilker

    2015-01-01

    The effect of Fe concentration on the glass forming ability (GFA) and magnetic properties in Co (40.2−x) Fe (20.1+x) Ni 6.7 B 22.7 Si 5.3 Nb 5 (x=0–10) bulk metallic glasses were investigated. By suction casting method, the bulk metallic glasses with diameters up to 2 mm were produced. We try to find out which Fe concentration makes an influence on Co based system's magnetic properties and glass forming ability. The curves of thermal analysis, obtained using differential scanning calorimetry (DSC), show that the Co (40.2−x) Fe (20.1+x) Ni 6.7 B 22.7 Si 5.3 Nb 5 (x=0–10) have a supercooled liquid region (∆T x ) of about 44 K. The saturation magnetizations (J s ) for as-cast BMG alloys were in the range of 0.62 T−0.81 T. - Highlights: • The effect of Fe concentration on the glass forming ability. • The substitution of an appropriate amount of Fe can enhance the GFA. • The substitution of Fe for Co also improves soft magnetic properties of the BMGs. • The high of J s 0.62−0.81 T with a low H c of 2−289 A/m of the alloys

  6. Mechanical and functional properties of two-phase Ni53Mn22Co6Ga19 high-temperature shape memory alloy with the addition of Dy

    International Nuclear Information System (INIS)

    Yang, S Y; Wang, C P; Liu, X J

    2013-01-01

    The effects of Dy addition on microstructure, martensitic transformation, mechanical and shape memory properties of the two-phase Ni 53 Mn 22 Co 6 Ga 19 high-temperature shape memory alloy were investigated. It is found that a small Dy addition results in the refinement of grain size, which can effectively improve the tensile ductility and strength of the two-phase Ni 53 Mn 22 Co 6 Ga 19 alloy. However, a Dy(Ni,Mn) 4 Ga precipitate forms in the alloys with the Dy addition, and its amount increases with an increase in the Dy addition. This change causes the ductility of the alloys to decrease when the Dy addition is further increased to 0.3 at.%. The results further show that the changes in the martensitic transformation temperature of the studied alloys can be attributed to the combined effects of the tetragonality (c/a) and electron concentration (e/a) of martensite. Additionally, the shape memory effects of the alloys are closely related to the refinement of grain size and the alloy strength. In this study, the (Ni 53 Mn 22 Co 6 Ga 19 ) 99.8 Dy 0.2 alloy exhibits a variety of good properties, including a high martensitic transformation starting temperature of 385.7 °C, a tensile ductility of 10.3% and a shape memory effect of 2.8%. (paper)

  7. CoCr/NiFe double layers studied by FMR and VSM

    NARCIS (Netherlands)

    Stam, M.T.H.C.W.; Gerritsma, G.J.; Lodder, J.C.; Popma, T.J.A.

    1987-01-01

    CoCr/NiFe double layers were investigated by FMR and VSM. The FMR linewidth of NiFe of the double layer is about twice that of a single NiFe layer. The resonance field is the same in both cases. Using the VSM the coercive field of the CoCr layer of the double layer was obtained. It is approximately

  8. Electron microscopy and diffraction of ordering in Ni-W alloys

    International Nuclear Information System (INIS)

    Mishra, N.S.

    1995-01-01

    Electron microscopy and diffraction studies of ordering in stoichiometric Ni-20%W and off-stoichiometric Ni-15%W alloys have been carried out. The specimens of Ni-20%W were first 1,398 K for 4 h and then quenched rapidly into water. Short range order (SRO) spots were observed at {1 1/2 0}* positions. Two hitherto unknown metastable phases: D 2h 25 -Ni 2 W and D0 22 -Ni 3 W were observed in the diffraction patterns. Long range order (LRO) transformations were studied at 1,103 and 1,213 K. Kinetics and mechanism of transformations have been identified. Ni-15%W specimens were solution treated at 1,523 K for 1 h followed by quenching in water. SRO spots similar to those found in Ni-20%W were observed in this alloy as well. The transition to LRO was studied at 1,093 K. Distinct Ni 4 W precipitates could be observed after 5 h of annealing at this temperature. After 100 h of annealing precipitates were found to grow into faceted shape coherent with the disordered matrix. After prolonged annealing for over 150 h the Ni 4 W precipitates began to lose coherency by the generation of misfit dislocations. The microstructural observations have been compared for the stoichiometric and off-stoichiometric alloys

  9. Local Energies and Energy Fluctuations — Applied to the High Entropy Alloy CrFeCoNi

    Science.gov (United States)

    Fukushima, Tetsuya; Katayama-Yoshida, Hiroshi; Sato, Kazunori; Ogura, Masako; Zeller, Rudolf; Dederichs, Peter H.

    2017-11-01

    High entropy alloys show a variety of fascinating properties like high hardness, wear resistance, corrosion resistance, etc. They are random solid solutions of many components with rather high concentrations. We perform ab-initio calculations for the high entropy alloy CrFeCoNi, which equal concentration of 25% for each element. By the KKRnano program package, which is based on an order-N screened Korringa-Kohn-Rostoker Green's function method, we consider a face-centered cubic (FCC) supercell with 1372 randomly distributed elements, and in addition also smaller supercells with 500 and 256 atoms. It is found from our calculations that the local moments of the Cr atoms show a large environmental variation, ranging from -1.70 μB to +1.01 μB with an average of about -0.51 μB. We present a new method to calculate "local energies" of all atoms. This is based on the partitioning of the whole space into Voronoi cells and allows to calculate the energetic contribution of each atomic cell to the total energy of the supercell. The supercell calculations show very large variations of the local energies, analogous to the variations of the local moments. This shows that the random solid solution is not stable and has a tendency to form an L12-structure with the Cr-atoms ordered at the corner of the cube and the elements Fe, Co, and Ni randomly distributed on the three other FCC sublattices. For this structure the variation of the local moments are much smaller.

  10. Heat treatment of NiCrFe alloy 600 to optimize resistance to intergranular stress corrosion

    Science.gov (United States)

    Steeves, A.F.; Bibb, A.E.

    A process of producing a NiCrFe alloy having a high resistance to stress corrosion cracking comprises heating a NiCrFe alloy to a temperature sufficient to enable the carbon present in the alloy body in the form of carbide deposits to enter into solution, rapidly cooling the alloy body, and heating the cooled body to a temperature between 1100 to 1500/sup 0/F for about 1 to 30 hours.

  11. Powder metallurgical processing of equiatomic AlCoCrFeNi high entropy alloy: Microstructure and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Mohanty, S.; Maity, T.N.; Mukhopadhyay, S. [Department of Materials Science and Engineering, Indian Institute of Technology Kanpur, Kanpur 208016 (India); Sarkar, S. [Department of Materials Engineering, Indian Institute of Science, Bangalore 560012 (India); Gurao, N.P. [Department of Materials Science and Engineering, Indian Institute of Technology Kanpur, Kanpur 208016 (India); Bhowmick, S. [Hysitron Inc., Eden Prairie, MN 55344 (United States); Biswas, Krishanu, E-mail: kbiswas@iitk.ac.in [Department of Materials Science and Engineering, Indian Institute of Technology Kanpur, Kanpur 208016 (India)

    2017-01-02

    Phase formation, microstructural evolution and the mechanical properties of novel multi-component equiatomic AlCoCrFeNi high entropy alloy synthesized by high energy ball milling followed by spark plasma sintering have been reported here. The microstructure of the mechanically alloyed (MA) powder and sintered samples were studied using X-ray diffraction, scanning electron and transmission electron microscopy, whereas the detailed investigation of the mechanical properties of the sintered samples were measured using micro and nano hardness techniques. The fracture toughness measurements were performed by applying single edge V notch beam (SEVNB) technique. The MA powder shows the presence of FCC (τ) and BCC (κ) solid solution phases. Extended ball milling (up to 60 h) does not change the phases present in MA powder. The sintered pellets show phase-separated microstructure consisting of Al-Ni rich L1{sub 2} phase, α′ and tetragonal Cr-Fe-Co based σ phase along with Al-Ni-Co-Fe FCC solid solution phase (ε) for sample sintered from 973 to 1273 K. The experimental evidences indicate that BCC (κ) solid solution undergoes eutectoid transformation during sintering leading to the formation of L1{sub 2} ordered α′ and σ phases, whereas FCC (τ) phase remains unaltered with a slight change in the lattice parameter. The hardness of the sample increases with sintering temperature and a sudden rise in hardness is observed 1173 K. The sample sintered at 1273 K shows the highest hardness of ~8 GPa. The elastic modulus mapping clearly indicates the presence of three phases having elastic moduli of about 300, 220 and 160 GPa. The fracture toughness obtained using SEVNB test shows a maximum value of 3.9 MPa m{sup 1/2}, which is attributed to the presence of brittle nanosized σ phase precipitates. It is proposed that significant increase in the fraction of σ phase precipitates and eutectoid transformation of the τ phase contribute to increase in hardness along with

  12. LaNi0.6Co0 4O3-δ dip-coated on Fe-Cr mesh as a composite cathode contact material on intermediate solid oxide fuel cells

    Science.gov (United States)

    Morán-Ruiz, Aroa; Vidal, Karmele; Larrañaga, Aitor; Laguna-Bercero, Miguel Angel; Porras-Vázquez, Jose Manuel; Slater, Peter Raymond; Arriortua, María Isabel

    2014-12-01

    The feasibility of using Crofer22APU mesh dip coated with LaNi0.6Co0.4O3-δ (LNC) ceramic paste as a uniform contact layer on a Crofer22APU channeled interconnect was studied. The control of LNC dip coating thickness on Fe-Cr mesh was carried out by rheological measurements of the suspension. SEM cross-section of formed composite contact material showed good adherence between ceramic and metallic components. The measured area specific resistance (ASR) value at 800 °C was 0.46 ± 0.01 mΩ cm2, indicating low contact resistance itself. The long term stability of metallic/ceramic composite was also studied. The contact resistance, when composite contact material was adhered to channeled Crofer22APU interconnect, was 5.40 ± 0.01 mΩ cm2, which is a suitable value for the performance of IT-SOFC stack. The stability of the system after treating at 800 °C for 1000 h was characterized using X-ray Micro-Diffraction (XRMD), Scanning Electron Microscope equipped with an Energy Dispersive X-ray analyzer (SEM-EDX) and X-ray Photoelectron Spectroscopy (XPS) techniques. The oxidation rate of the alloy and Fe3O4 phase formation were enhanced on the channels of the interconnect. Thus, the formation of CrO3 (g) and CrO2(OH)2 (g) species was accelerated on the composite surface under the channel. Through XRMD and XPS analysis the coexistence of two perovskite phases (initial LNC and Cr-perovskite) was observed.

  13. Effect of Si and Mn additions on ferrite and austenite phase fractions in 25Cr-7Ni-1.5Mo-3W base super duplex stainless steels

    International Nuclear Information System (INIS)

    Jeong, S.W.; Lee, Z.-H.; Lee, H.M.

    2000-01-01

    The effect of heat treatment and Si and Mn additions on the ferrite and austenite phase fractions of the super duplex stainless steel (SDSS), Fe-25Cr-7Ni-1.5Mo-3W-Si-Mn-0.25N (numbers are all in wt.% unless specified otherwise), was investigated. The thermodynamic calculations of phase equilibria and phase fractions were performed using the Thermo-Calc program. Based on the calculated results, specific compositions of Si and Mn were selected and alloys with these compositions were analysed by Feritscope, X-ray diffractometry and scanning electron microscopy. The calculated phase fractions and experimentally analysed ones were compared and there was a good agreement between calculations and measurements. The optimum heat treatment condition for Fe-25Cr-7Ni-1.5Mo-3W-0.5Si-0.5Mn-0.25N is to hold at 1050 to 1100 C for 2 h in considering the ferrite to austenite ratio of 50:50 and to avoid second phase precipitation such as the σ phase. It was suggested that an excessive addition of more than 0.8Si and 1.0Mn may induce the σ phase precipitation. (orig.)

  14. Thermal expansion of Cr2xFe2-2xMo3O12, Al2xFe2-2xMo3O12 and Al2xCr2-2xMo3O12 solid solutions

    International Nuclear Information System (INIS)

    Ari, M.; Jardim, P.M.; Marinkovic, B.A.; Rizzo, F.; Ferreira, F.F.

    2008-01-01

    The transition temperature from monoclinic to orthorhombic and the thermal expansion of the orthorhombic phase were investigated for three systems of the family A 2 M 3 O 12 : Cr 2x Fe 2-2x Mo 3 O 12 , Al 2x Fe 2-2x Mo 3 O 12 and Al 2x Cr 2-2x Mo 3 O 12 . It was possible to obtain a single-phase solid solution in all studied samples (x=0, 0.1, 0.3, 0.5, 0.7, 0.9 and 1). A linear relationship between the transition temperature and the fraction of A 3+ cations (x) was observed for each system. In all orthorhombic solid solutions studied here the observed thermal expansion was anisotropic. These anisotropic thermal expansion properties of crystallographic axes a, b and c result in a low positive or near-zero overall linear coefficient of thermal expansion (α l =α V /3). The relationship between the size of A 3+ cations in A 2 M 3 O 12 and the coefficient of thermal expansion is discussed. Near-zero thermal expansion of Cr 2 Mo 3 O 12 is explained by the behavior of Cr-O and Mo-O bond distances, Cr-Mo non-bond distances and Cr-O-Mo bond angles with increasing temperature, estimated by Rietveld analysis of synchrotron X-ray powder diffraction data. - Graphical abstract: In this figure, all published overall linear coefficients of thermal expansion for orthorhombic A 2 M 3 O 12 family obtained through diffraction methods as a function of A 3+ cation radii size, together with dilatometric results, are plotted. Our results indicate that Cr 2 Mo 3 O 12 does not exactly follow the established relationship

  15. Effect of Manganese on Microstructures and Solidification Modes of Cast Fe-Mn-Si-Cr-Ni Shape Memory Alloys

    Science.gov (United States)

    Peng, Huabei; Wen, Yuhua; Du, Yangyang; Yu, Qinxu; Yang, Qin

    2013-10-01

    We investigated microstructures and solidification modes of cast Fe-(13-27)Mn-5.5Si-8.5Cr-5Ni shape memory alloys to clarify whether Mn was an austenite former during solidification. Furthermore, we examined whether the Creq/Nieq equations (Delong, Hull, Hammer and WRC-1992 equations) and Thermo-Calc software® together with database TCFE6 were valid to predict the solidification modes of cast Fe-(13-27)Mn-5.5Si-8.5Cr-5Ni shape memory alloys. The results have shown that the solidification modes of Fe-(13-27)Mn-5.5Si-8.5Cr-5Ni alloys changed from the F mode to the FA mode with increasing the Mn concentration. Mn is an austenite former during the solidification for the cast Fe-Mn-Si-Cr-Ni shape memory alloys. The Delong, Hull, Hammer, and WRC-1992 equations as well as Thermo-Calc software® together with database TCFE6 are invalid to predict the solidification modes of cast Fe-(13-27)Mn-5.5Si-8.5Cr-5Ni SMAs. To predict the solidification modes of cast Fe-Mn-Si-Cr-Ni alloys, a new Creq/Nieq equation should be developed or the thermodynamic database of Thermo-Calc software® should be corrected.

  16. Stress-induced Curie temperature increase in the Fe{sub 64}Ni{sub 36} invar alloy

    Energy Technology Data Exchange (ETDEWEB)

    Gorria, Pedro; Martinez-Blanco, David; Blanco, Jesus A. [Departamento de Fisica, Universidad de Oviedo (Spain); Boada, Roberto; Chaboy, Jesus [ICMA and Departamento de Fisica de la Materia Condensada, CSIC - Universidad de Zaragoza (Spain); Fernandez-Martinez, Alejandro [LGIT, University of Grenoble and CNRS, Maison des Geosciences, Grenoble (France); Institut Laue-Langevin, Grenoble (France); Garbarino, Gaston; Castro, German R.; Mezouar, Mohamed [European Synchrotron Radiation Facility (ESRF), Grenoble (France); Smith, Ronald I. [ISIS Facility, RAL, Chilton, Didcot, Oxon (United Kingdom); Alonso, J.I.G. [Department of Physical and Analytical Chemistry, University of Oviedo (Spain); Hernando, Antonio [Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC, Madrid (Spain)

    2009-05-15

    Structural and magnetic changes on invar Fe{sub 64}Ni{sub 36} alloy (T{sub C}=500 K) produced by mechanical milling followed by heating up to 1073 K, were investigated by neutron diffraction, magnetization measurements, X-ray diffraction under high pressures and X-ray absorption at both Fe and Ni K-edges. We argue that the strain induced in the Fe{sub 64}Ni{sub 36} material after this treatment mainly affects the Fe sites due to the magnetovolume coupling, the most notorious feature being the increase of the Curie temperature ({delta}T{sub C}=70 K). (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. High-temperature oxidation of advanced FeCrNi alloy in steam environments

    Science.gov (United States)

    Elbakhshwan, Mohamed S.; Gill, Simerjeet K.; Rumaiz, Abdul K.; Bai, Jianming; Ghose, Sanjit; Rebak, Raul B.; Ecker, Lynne E.

    2017-12-01

    Alloys of iron-chromium-nickel are being explored as alternative cladding materials to improve safety margins under severe accident conditions. Our research focuses on non-destructively investigating the oxidation behavior of the FeCrNi alloy "Alloy 33" using synchrotron-based methods. The evolution and structure of oxide layer formed in steam environments were characterized using X-ray diffraction, hard X-ray photoelectron spectroscopy, X-ray fluorescence methods and scanning electron microscopy. Our results demonstrate that a compact and continuous oxide scale was formed consisting of two layers, chromium oxide and spinel phase (FeCr2O4) oxides, wherein the concentration of the FeCr2O4 phase decreased from the surface to the bulk-oxide interface.

  18. CoCr double-layered media with NiFe and CoZrNb soft-magnetic layers (invited)

    International Nuclear Information System (INIS)

    Bernards, J.P.C.; Schrauwen, C.P.G.; Zieren, V.; Luitjens, S.B.

    1988-01-01

    The magnetic, structural, and recording properties of CoCr double-layered media are investigated. The underlayer materials NiFe (crystalline) and CoZrNb (amorphous) were combined with two different kinds of intermediate layers: Ti (crystalline) and Ge (amorphous). Applying a bias voltage during sputtering of NiFe results in a low coercivity of the NiFe layer and in a high coercivity of the CoCr layer. The structure of the NiFe layer influences the structure of the CoCr layer. A Ti layer between the NiFe and CoCr layers decreases the in-plane remanence of the CoCr layer. The coercivity of all CoZrNb layers is low, independent of the application of a bias voltage. The orientation and structure of CoCr on CoZrNb can be improved by using a Ge intermediate layer, which results in a low coercivity of the CoCr. A Ti intermediate layer increases the coercivity. Ring heads show a dependence of spike noise on the underlayer coercivity and on the applied normal force. A probe-type head shows a dependence of its output on the CoCr coercivity, which may be understood in terms of demagnetization and writing depth

  19. Corrosion behaviour and surface analysis of a Co-Cr and two Ni-Cr dental alloys before and after simulated porcelain firing.

    Science.gov (United States)

    Qiu, Jing; Yu, Wei-Qiang; Zhang, Fu-Qiang; Smales, Roger J; Zhang, Yi-Lin; Lu, Chun-Hui

    2011-02-01

    This study evaluated the corrosion behaviour and surface properties of a commercial cobalt-chromium (Co-Cr) alloy and two nickel-chromium (Ni-Cr) alloys [beryllium (Be)-free and Be-containing] before and after a simulated porcelain-firing process. Before porcelain firing, the microstructure, surface composition and hardness, electrochemical corrosion properties, and metal-ion release of as-cast alloy specimens were examined. After firing, similar alloy specimens were examined for the same properties. In both as-cast and fired conditions, the Co-Cr alloy (Wirobond C) showed significantly more resistance to corrosion than the two Ni-Cr alloys. After firing, the corrosion rate of the Be-free Ni-Cr alloy (Stellite N9) increased significantly, which corresponded to a reduction in the levels of Cr, molybdenum (Mo), and Ni in the surface oxides and to a reduction in the thickness of the surface oxide film. The corrosion properties of the Co-Cr alloy and the Be-containing Ni-Cr alloy (ChangPing) were not significantly affected by the firing process. Porcelain firing also changed the microstructure and microhardness values of the alloys, and there were increases in the release of Co and Ni ions, especially for Ni from the Be-free Ni-Cr alloy. Thus, the corrosion rate of the Be-free Ni-Cr alloy increased significantly after porcelain firing, whereas the firing process had little effect on the corrosion susceptibility of the Co-Cr alloy and the Be-containing Ni-Cr alloy. © 2011 Eur J Oral Sci.

  20. Influence of the chemical composition of rapidly quenched amorphous alloys (Ni, Fe, Cr)-B-Si on its crystallization process

    Science.gov (United States)

    Elmanov, G.; Dzhumaev, P.; Ivanitskaya, E.; Skrytnyi, V.; Ruslanov, A.

    2016-04-01

    This paper presents results of research of the structure and phase transformations during the multistage crystallization of the metallic glasses with the compositions Ni71,5Cr6,8Fe2,7B11,9Si7,1 and Ni63,4Cr7,4Fe4,3Mn0,8B15,6Si8,5 labeled as AWS BNi-2 according to American Welding Society. Differential scanning calorimetry (DSC), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDX) were used as experimental research methods. The influence of the alloys chemical composition (boron, manganese and iron) on the temperatures and the exothermic heat effects of phase transformations, as well as on the phase composition of alloys at three stages of crystallization was analyzed. We present a thermodynamic explanation of the observed heat effects. It has been shown that manganese has the main influence on the phase transformations temperatures and heat effects in these two alloys. It is also assumed that at the final crystallization stage simultaneously with the formation of phases Ni3B and β1-Ni3Si should occur the nucleation of borides of CrB type with high Cr and low Si content.

  1. Irradiation-induced softening of Ni3P and (Ni, Fe, Cr)3P alloys

    International Nuclear Information System (INIS)

    Schumacher, G.; Miekeley, W.; Wahi, R.P.

    1993-01-01

    Production of amorphous alloys by solid state reactions (SSR) has attracted much interest during the last few years. One of the methods to induce such a reaction is the irradiation of suitable crystalline alloys by fast particles. Examination of this kind of SSR in M 3 P type of brazing alloys (M: Metal) is attractive because of the following reason: In brazed joints of candidate structural materials like 316L stainless steel for applications in fusion reactors, crystalline intermetallic phases have been detected which are unstable relative to the amorphous state when irradiated at moderate temperatures with fast particles. It is expected that the transition to the amorphous state is accompanied by changes of the mechanical properties, which are of fundamental interest in this context. Until now, only a few studies on the evolution of mechanical properties during amorphization have been performed. Measurements of microhardness of the crystalline and the corresponding amorphous phase do not exist to the authors knowledge. In this communication, the authors present results on changes of microhardness, due to amorphization by fast ions. The measurements have been performed on a model alloy Ni 3 P and on the brazed joint of stainless steel 316L, containing M 3 P (M: Ni, Fe, Cr) as one of the phases. Though microhardness is not a fundamental property of materials, it is a manifestation of several related properties, such as yield stress, ductility, work-hardening, elastic modulus and residual stress states. It represents a resistance for indentation and is, therefore, appropriate for comparative purposes

  2. Effect of manganese and chromium on microstructure and toughness of Fe-Cr-Mn alloys resulting from solid-solution treatment

    International Nuclear Information System (INIS)

    Okazaki, Yoshimitsu; Miyahara, Kazuya; Wade, Noboru; Hosoi, Yuzo

    1989-01-01

    This study is aimed at making clear the effect of Mn and Cr on the microstructure and toughness of an Fe-Cr-Mn alloy which is considered as one of the candidate alloys for reduced activation materials for the first wall application of the fusion reactor. The microstructures of Fe-12% Cr-(5∼30)% Mn(mass%) alloys after solution treatment at 1373 K for 3.6 ks are markedly varied with Mn contents; α'(martensite) + δ(ferrite) in 5% Mn alloy, α' + δ + ε(martensite) + γ(austenite) in the 10% Mn alloy, α' + ε + γ in 15% Mn alloy, ε + γ in the 20% Mn alloy, and ε + γ +δ in the 25% Mn alloy, and γ + δ in the 30% Mn alloy. It is to be noted that the δ phase increases with increasing Mn content when the Fe-12% Cr alloy contains more than 25% Mn, which suggests that Mn plays the role of a ferrite former. In Fe-15% Mn-Cr alloy, the δ phase is not observed in the range of Cr contents up to 12%, whereas it is markedly increased with the addition of 16% Cr. C, N and Ni are very helpful in forming the γ phase in these alloys as generally known in Fe-Cr-Ni alloys. The toughness evaluated by the Charpy impact test at 273 K and room temperature is very low in the 5% Mn alloy which consists of the α' and δ phases. It is, however, significantly improved by a small amount of the γ phase and increases with increase of γ phase stability. (author)

  3. The effect of small 4th element alloying additions on the calculated phase stability in the Fe-Cr-Ni system

    International Nuclear Information System (INIS)

    Watkin, J.S.

    1979-01-01

    Recent studies into the void swelling of Fe-Cr-Ni alloys have revealed that the magnitude of swelling depends upon alloy constitution and this together with the fact that minor element additions also play a major role in swelling necessitate a detailed knowledge of the influence of small 4th element additions on phase stability. In this paper the effects of additions of Nb, Ti, Al, Mo, Co and C to the Fe-Cr-Ni ternary are assessed by calculation. They confirm the ferritising tendencies of Nb, Ti and Al and the strong austenitising effect of C. Confirmation is also found for the scaling factors in the equivalent Ni and Cr equations in common usage and the paper presents Fe-Cr-Ni ternary sections at 400, 550 and 700 0 C modified for 1 at.% addition of each of the above elements. (orig.) [de

  4. Internal carbonitriding behavior of Ni-V, Ni-Cr, and Ni-3Nb alloys

    International Nuclear Information System (INIS)

    Allen, A.T.; Douglass, D.L.

    1999-01-01

    Ni-2V, Ni-5V, Ni-12V, Ni-10Cr, Ni-20Cr, and Ni-3Nb alloys were carbonitrided in C 3 H 6 and NH 3 gas mixtures (bal H 2 ) over the range 700--1,000 C. Carbonitridation of Ni-12V and Ni-20Cr in C 3 H 6 /NH 3 /H 2 (1.5/1.5/97 v/o) and (1.5/10/88.5 v/o) produced duplex subscales consisting of near-surface nitrides with underlying carbides. Growth of each zone obeyed the parabolic rate law under most conditions. The presence of carbon generally did not effect the depth of the nitride zones compared to nitriding the alloys in NH 3 /H 2 (10/90 v/o). However, at 700 C, the nitride zones were deeper in the carbonitrided Ni-V alloys and Ni-20Cr. The presence of nitrogen generally increased the depth of the carbide zones in Ni-12V and Ni-20Cr compared to carburizing these alloys in C 3 H 6 /H 2 (1.5/98.5 v/o). VN, CrN, and NbN formed in Ni-V, Ni-Cr, and Ni-Nb alloys, respectively, whereas the underlying carbide layers contained V 4 C 3 in Ni-12V, Cr 3 C 2 above a zone of Cr 7 C 3 in Ni-20Cr, and NbC in Ni-3Nb. The solubilities and diffusivities of nitrogen and carbon in nickel were determined. Nitrogen and carbon each exhibited retrograde solubility with temperature in pure Ni in both carbonitriding environments. Nitrogen diffusion in nickel was generally lower in each carbonitriding mixture compared to nitrogen diffusion in a nitriding environment, except at 700 C when nitrogen diffusion was higher. Carbon diffusion in nickel was generally higher in the carbonitriding environments compared to carbon diffusion in a carburizing environment

  5. First principles study of structural stability and site preference in Co3 (W,X

    Directory of Open Access Journals (Sweden)

    Joshi Sri Raghunath

    2014-01-01

    Full Text Available Since the discovery [1] of γ′ precipitate (L12 – Co3(Al, W in the Co-Al-W ternary system, there has been an increased interest in Co-based superalloys. Since these alloys have two phase microstructures (γ + γ′ similar to Ni-based superalloys [2], they are viable candidates in high temperature applications, particularly in land-based turbines. The role of alloying on stability of the γ′ phase has been an active area of research. In this study, electronic structure calculations were done to probe the effect of alloying in Co3W with L12 structure. Compositions of type Co3(W,X, (where X/Y = Mn, Fe, Ni, Pt, Cr , Al, Si, V, W, Ta, Ti, Nb, Hf, Zr and Mo were studied. Effect of alloying on equilibrium lattice parameters and ground state energies was used to calculate Vegard's coefficients and site preference related data. The effect of alloying on the stability of the L12 structure vis a vis other geometrically close packed ordered structures was also studied for a range of Co3X compounds. Results suggest that the penchant of element for the W sublattice can be predicted by comparing heats of formation of Co3X in different structures.

  6. Synthesis, crystallization behavior and surface modification of Ni-Cr-Si-Fe amorphous alloy

    International Nuclear Information System (INIS)

    Iqbal, M.; Akhter, J.I.; Rajput, M.U.; Mahmood, K.; Hussain, Z.; Hussain, S.; Rafiq, M.

    2011-01-01

    A quaternary Ni/sub 86/Cr/sub 7/Si/sub 4/Fe/sub 3/ amorphous alloy was synthesized by melt spinning technique. Surface modification was done by electron beam melting (EBM), neutron irradiation and gamma-rays. Microstructure of as cast, annealed and modified samples was examined by scanning electron microscope. Crystallization behavior was studied by annealing the samples in vacuum at different temperatures in the range 773-1073 K. Techniques of X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used for characterization. Differential scanning calorimetry (DSC) was conducted at various heating rates in the range 10-40 K/min. Thermal parameters like glass transition temperature T/sub g/, crystallization temperature T/sub x/, supercooled liquid region delta T/sub x/ and reduced glass transition temperature T/sub rg/ were measured. The Ni/sub 86/Cr/sub 7/Si/sub 4/Fe/sub 3/ alloy exhibits wide supercooled liquid region of 60 K indicating good thermal stability. The activation energy was calculated to be 160 +- 4 kJ/mol using Kissinger and Ozawa equations respectively which indicates high resistance against crystallization. The XRD results of the samples annealed at 773 K, 923 K, 973 K and 1073 K/20 min show nucleation of Ni/sub 2/Cr/sub 3/ and NiCrFe crystalline phases. Vickers microhardness of the as cast ribbon was measured to be 680. About 30-50 % increase in hardness was achieved by applying EBM technique. (author)

  7. Synthesis of 15N-enriched urea (CO(15NH22 from 15NH3, CO, and S in a discontinuous process

    Directory of Open Access Journals (Sweden)

    C. R. Sant Ana Filho

    2012-12-01

    Full Text Available CO(15NH22 enriched with the stable isotope 15N was synthesized based on a reaction involving CO, 15NH3, and S in the presence of CH3OH. The method differs from the industrial method; a stainless steel reactor internally lined with polytetrafluoroethylene (PTFE was used in a discontinuous process under low pressure and temperature. The yield of the synthesis was evaluated as a function of the parameters: the amount of reagents, reaction time, addition of H2S, liquid solution and reaction temperature. The results showed that under optimum conditions (1.36, 4.01, and 4.48 g of 15NH3, CO, and S, respectively, 40 ml CH3OH, 40 mg H2S, 100 ºC and 120 min of reaction 1.82 g (yield 76.5% of the compound was obtained per batch. The synthesized CO(15NH22 contained 46.2% N, 0.55% biuret, melting point of 132.55 ºC and did not exhibit isotopic fractionation. The production cost of CO(15NH22 with 90.0 at. % 15N was US$ 238.60 per gram.

  8. Microstructural Changes During Plastic Deformation and Corrosion Properties of Biomedical Co-20Cr-15W-10Ni Alloy Heat-Treated at 873 K

    Science.gov (United States)

    Ueki, Kosuke; Ueda, Kyosuke; Nakai, Masaaki; Nakano, Takayoshi; Narushima, Takayuki

    2018-06-01

    Microstructural changes were observed during the plastic deformation of ASTM F90 Co-20Cr-15W-10Ni (mass pct) alloy heat-treated at 873 K (600 °C) for 14.4 ks, and analyzed by electron backscatter diffraction and in situ X-ray diffraction techniques. The obtained results revealed that the area fraction of the ɛ-phase ( f ɛ ) in the as-received alloy was higher than that in the heat-treated alloy in the low-to-middle strain region (≤ 50 pct), whereas the f ɛ of the heat-treated alloy was higher than that of the as-received alloy at the fracture point. During plastic deformation, the ɛ-phase was preferentially formed at the twin boundaries of the heat-treated alloy rather than at the grain boundaries. According to the transmission electron microscopy observations, the thin ɛ-phase layer formed due to the alloy heat treatment acted as the origin of deformation twinning, which decreased the stress concentration at the grain boundaries. The results of anodic polarization testing showed that neither the heat treatment at 873 K (600 °C) nor plastic deformation affected the alloy corrosion properties. To the best of our knowledge, this is the first study proving that the formation of a thin ɛ-phase layer during the low-temperature heat treatment of the studied alloy represents an effective method for the enhancement of the alloy ductility without sacrificing its strength and corrosion properties.

  9. Microstructural Changes During Plastic Deformation and Corrosion Properties of Biomedical Co-20Cr-15W-10Ni Alloy Heat-Treated at 873 K

    Science.gov (United States)

    Ueki, Kosuke; Ueda, Kyosuke; Nakai, Masaaki; Nakano, Takayoshi; Narushima, Takayuki

    2018-04-01

    Microstructural changes were observed during the plastic deformation of ASTM F90 Co-20Cr-15W-10Ni (mass pct) alloy heat-treated at 873 K (600 °C) for 14.4 ks, and analyzed by electron backscatter diffraction and in situ X-ray diffraction techniques. The obtained results revealed that the area fraction of the ɛ-phase (f ɛ ) in the as-received alloy was higher than that in the heat-treated alloy in the low-to-middle strain region (≤ 50 pct), whereas the f ɛ of the heat-treated alloy was higher than that of the as-received alloy at the fracture point. During plastic deformation, the ɛ-phase was preferentially formed at the twin boundaries of the heat-treated alloy rather than at the grain boundaries. According to the transmission electron microscopy observations, the thin ɛ-phase layer formed due to the alloy heat treatment acted as the origin of deformation twinning, which decreased the stress concentration at the grain boundaries. The results of anodic polarization testing showed that neither the heat treatment at 873 K (600 °C) nor plastic deformation affected the alloy corrosion properties. To the best of our knowledge, this is the first study proving that the formation of a thin ɛ-phase layer during the low-temperature heat treatment of the studied alloy represents an effective method for the enhancement of the alloy ductility without sacrificing its strength and corrosion properties.

  10. Preparation and Oxidation Performance of Y and Ce-Modified Cr Coating on open-cell Ni-Cr-Fe Alloy Foam by the Pack Cementation

    Science.gov (United States)

    Pang, Q.; Hu, Z. L.; Wu, G. H.

    2016-12-01

    Metallic foams with a high fraction of porosity, low density and high-energy absorption capacity are a rapidly emerging class of novel ultralight weight materials for various engineering applications. In this study, Y-Cr and Ce-Cr-coated Ni-Cr-Fe alloy foams were prepared via the pack cementation method, and the effects of Y and Ce addition on the coating microstructure and oxidation performance were analyzed in order to improve the oxidation resistance of open-cell nickel-based alloy foams. The results show that the Ce-Cr coating is relatively more uniform and has a denser distribution on the surface of the nickel-based alloy foam. The surface grains of the Ce-Cr-coated alloy foam are finer compared to those of the Y-Cr-coated alloy foam. An obvious Ce peak appears on the interface between the coating and the alloy foam strut, which gives rise to a "site-blocking" effect for the short-circuit transport of the cation in the substrate. X-ray diffraction analysis shows that the Y-Cr-coated alloy foam mainly consists of Cr, (Fe, Ni) and (Ni, Cr) phases in the surface layer. The Ce-Cr-coated alloy foam is mainly composed of Cr and (Ni, Cr) phases. Furthermore, the addition of Y and Ce clearly lead to an improvement in the oxidation resistance of the coated alloy foams in the temperature range of 900-1000 °C. The addition of Ce is especially effective in enhancing the diffusion of chromium to the oxidation front, thus, accelerating the formation of a Cr2O3 layer.

  11. Crystallography of sigma phase precipitation in superaustenitic Fe-22Cr-21Ni-6Mo-0.3N stainless steels

    International Nuclear Information System (INIS)

    Lee, Tae Ho; Jung, Yun Chul; Kim, Sung Joon

    1999-01-01

    The crystallographic features of sigma phase precipitation in super austenitic Fe-22Cr-21Ni-6Mo-(0.3N) stainless steels during isothermal aging were investigated utilizing transmission electron microscopy. The sigma phase precipitated along the austenite grain boundaries even after solution treatment due to higher Mo contents and remained stable throughout aging at 900 .deg. C up to 168 hours. The sigma phase observed in this study was found to be ternary Fe-Cr-Mo sigma phase and had tetragonal structure with lattice parameters of a=9.17A and c=4.74A. The orientation relationships between the sigma phase and austenite were determined from the analyses of selected area diffraction patterns taken by various zone axes and stereo graphic analyses. The orientation relationships between sigma and austenite phases obtained in this study were as follows; 1) (110) γ ll (110) σ , [111] γ ll [001] σ and (112) γ ll (110) σ , [111] γ ll [001] σ and 2) (110) γ ll (110) σ , [112] γ ll [113] σ and (111) γ ll (332) σ , [112] γ ll [113] σ . However, the former orientation relationship was predominant throughout aging and the latter orientation relationship was scarcely observed in very limited aging condition

  12. Phase decomposition in a mechanically alloyed Cu-44.5 at%Ni-22.5 at%Fe alloy during isothermal aging

    International Nuclear Information System (INIS)

    Lopez-Hirata, Victor M.; Saucedo-Munoz, Maribel L.; Diaz-Barriga-Arceo, Lucia G.

    2006-01-01

    A supersaturated solid solution of Cu-44.5 at%Ni-22.5 at%Fe alloy was produced by ball milling of a pure chemical elemental mixture for 1080 ks. An fcc supersaturated solid solution with a grain size of about 20 nm was obtained after milling. This alloy was subsequently aged at 803, 898 and 1003 K for different times. The growth kinetics of the modulation wavelength was determined from the X-ray diffraction results and followed the Lifshitz-Slyozov-Wagner theory for a diffusion-controlled coarsening in the MA alloy after aging. The growth kinetics of composition modulation wavelength for the MA alloy was faster at 803 and 898 K than that for the same alloy composition obtained by a conventional processing and then aged at the same temperatures. The activation energy for the decomposed phase coarsening process in the MA alloy was lower than that corresponding to the conventionally-processed alloy. (author)

  13. Anisotropic nanolaminated CoNiFe cores integrated into microinductors for high-frequency dc–dc power conversion

    International Nuclear Information System (INIS)

    Kim, Jooncheol; Kim, Minsoo; Herrault, Florian; Kim, Jung-Kwun; Allen, Mark G

    2015-01-01

    This paper presents a rectangular, anisotropic nanolaminated CoNiFe core that possesses a magnetically hard axis in the long geometric axis direction. Previously, we have developed nanolaminated cores comprising tens to hundreds of layers of 300–1000 nm thick metallic alloys (i.e. Ni 80 Fe 20 or Co 44 Ni 37 Fe 19 ) based on sequential electrodeposition, demonstrating suppressed eddy-current losses at MHz frequencies. In this work, magnetic anisotropy was induced to the nanolaminated CoNiFe cores by applying an external magnetic field (50–100 mT) during CoNiFe film electrodeposition. The fabricated cores comprised tens to hundreds of layers of 500–1000 nm thick CoNiFe laminations that have the hard-axis magnetic property. Packaged in a 22-turn solenoid test inductor, the anisotropic core showed 10% increased effective permeability and 25% reduced core power losses at MHz operation frequency, compared to an isotropic core of the identical geometry. Operating the anisotropic nanolaminated CoNiFe core in a step-down dc–dc converter (15 V input to 5 V output) demonstrated 81% converter efficiency at a switching frequency of 1.1 MHz and output power of 6.5 W. A solenoid microinductor with microfabricated windings integrated with the anisotropic nanolaminated CoNiFe core was fabricated, demonstrating a constant inductance of 600 nH up to 10 MHz and peak quality factor exceeding 20 at 4 MHz. The performance of the microinductor with the anisotropic nanolaminated CoNiFe core is compared with other previously reported microinductors. (fast track communication)

  14. Effects of Ni and Mo on the microstructure and some other properties of Co-Cr dental alloys

    International Nuclear Information System (INIS)

    Matkovic, Tanja; Matkovic, Prosper; Malina, Jadranka

    2004-01-01

    Influences of adding Ni and Mo on the microstructure and properties of as-cast Co-Cr base alloys have been investigated in order to determine the region of their optimal characteristics for biomedical application. The alloys were produced by arc-melting technique under argon atmosphere. Using optical metallography and scanning electron micro analyser it has been established that among 10 samples of Co-Cr-Ni alloys only samples 5 and 9 with the composition Co 55 Cr 40 Ni 5 and Co 60 Cr 30 Ni 10 have appropriate dendritic solidification microstructure. This microstructure, typical for commercial dental alloys, appears and beside greater number of as-cast Co-Cr-Mo alloys. The results of hardness and corrosion resistance measurements revealed the strong influence of different alloy chemistry and of as-cast microstructure. Hardness of alloys decreases with nickel content, but increases with chromium content. Therefore all Co-Cr-Ni alloys have significantly lower hardness than Co-Cr-Mo alloys. Corrosion resistance of alloys in artificial saliva was evaluated on the base of pitting potential. Superior corrosion characteristics have the samples with typical dendritic microstructure and higher chromium content, until nickel content have not significant effect. According to this, in ternary Co-Cr-Ni phase diagram was located the small concentration region (about samples 5 and 9) in them alloy properties can satisfied the high requirements for biomedical applications. This region is considerably larger in Co-Cr-Mo phase diagram

  15. Forming a structure of the CoNiFe alloys by X-ray irradiation

    Science.gov (United States)

    Valko, Natalia; Kasperovich, Andrey; Koltunowicz, Tomasz N.

    The experimental data of electrodeposition kinetics researches and structure formation of ternary CoNiFe alloys deposited onto low-carbon steel 08kp in the presence of X-rays are presented. Relations of deposit rate, current efficiencies, element and phase compositions of CoNiFe coatings formed from sulfate baths with respect to cathode current densities (0.5-3A/dm2), electrolyte composition and irradiation were obtained. It is shown that, the CoNiFe coatings deposited by the electrochemical method involving exposure of the X-rays are characterized by more perfect morphology surfaces with less developed surface geometry than reference coatings. The effect of the X-ray irradiation on the electrodeposition of CoNiFe coatings promotes formatting of alloys with increased electropositive component and modified phase composition.

  16. STUDY OF COATINGS OBTAINED FROM ALLOY Fe-Mn-C-B-Si-Ni-Cr

    Directory of Open Access Journals (Sweden)

    Mychajło Paszeczko

    2016-09-01

    Full Text Available Tribological behaviour of coatings obtained from eutectic alloy Fe-Mn-C-B-Si-Ni-Cr was studied. The coatings were obtained by the method of gas metal arc welding (GMA with use of powder wire. GMA welding method is widely used for the regeneration of machine parts. Eutectic Fe-Mn-C-B-Si-Ni-Cr alloys can be used to obtain high quality coatings resistant to wear and corrosion. Pin-on-disk dry sliding wear tests at sliding speeds 0.4 m/s and under load 10 MPa were conducted for pin specimens. During friction a typical tribological behavior was observed. The mechanism of wear was mechanical-chemical.

  17. Elastic properties of fcc Fe-Mn-X (X = Cr, Co, Ni, Cu) alloys studied by the combinatorial thin film approach and ab initio calculations.

    Science.gov (United States)

    Reeh, S; Kasprzak, M; Klusmann, C D; Stalf, F; Music, D; Ekholm, M; Abrikosov, I A; Schneider, J M

    2013-06-19

    The elastic properties of fcc Fe-Mn-X (X = Cr, Co, Ni, Cu) alloys with additions of up to 8 at.% X were studied by combinatorial thin film growth and characterization and by ab initio calculations using the disordered local moments (DLM) approach. The lattice parameter and Young's modulus values change only marginally with X. The calculations and experiments are in good agreement. We demonstrate that the elastic properties of transition metal alloyed Fe-Mn can be predicted by the DLM model.

  18. Electroless siliconizing Fe-3% Cr-3% Si alloy

    International Nuclear Information System (INIS)

    Nurlina, Enung; Darmono, Budy; Purwadaria, Sunara

    2000-01-01

    In this research Fe-3%Cr-3%Mo-3%Si and Fe-3%Cr-3%Cu-3%Si alloys had been coated by silicon metal without electricity current which knows as electroless siliconizing. Coating was conducted by immersed sampler into melt fluoride-chloride salt bath at temperature of 750 o C for certain period. The layer consisted of Fe3Si phase. Observation by microscope optic and EDAX showed that the silicide layer were thick enough, adherent, free for crack and had silicon content on the surface more than 15%. The growth rate of silicide layer followed parabolic rate law, where the process predominantly controlled by interdiffusion rate in the solid phase. Key words : electroless siliconizing, the melt fluoride- chloride salt mix, silicide layer

  19. Valence-electron configuration of Fe, Cr, and Ni in binary and ternary alloys from Kβ -to- Kα x-ray intensity ratios

    Science.gov (United States)

    Han, I.; Demir, L.

    2009-11-01

    Kβ -to- Kα x-ray intensity ratios of Fe, Cr, and Ni have been measured in pure metals and in alloys of FexNi1-x ( x=0.8 , 0.7, 0.6, 0.5, 0.4, 0.3, and 0.2), NixCr1-x ( x=0.8 , 0.6, 0.5, 0.4, and 0.2), FexCr1-x ( x=0.9 , 0.7, and 0.5), and FexCryNi1-(x+y) ( x=0.7-y=0.1 , x=0.5-y=0.2 , x=0.4-y=0.3 , x=0.3-y=0.3 , x=0.2-y=0.2 , and x=0.1-y=0.2 ) following excitation by 22.69 keV x rays from a 10 mCi C109d radioactive point source. The valence-electron configurations of these metals were determined by corporation of measured Kβ -to- Kα x-ray intensity ratios with the results of multiconfiguration Dirac-Fock calculation for various valence-electron configurations. Valence-electron configurations of 3d transition metals in alloys indicate significant differences with respect to the pure metals. Our analysis indicates that these differences arise from delocalization and/or charge transfer phenomena in alloys. Namely, the observed change of the valence-electron configurations of metals in alloys can be explained with the transfer of 3d electrons from one element to the other element and/or the rearrangement of electrons between 3d and 4s,4p states of individual metal atoms.

  20. Crystallization processes in an amorphous Co-Fe-Cr-Si-B alloy under isothermal annealing

    Science.gov (United States)

    Fedorets, A. N.; Pustovalov, E. V.; Plotnikov, V. S.; Modin, E. B.; Kraynova, G. S.; Frolov, A. M.; Tkachev, V. V.; Tsesarskaya, A. K.

    2017-09-01

    Research present the crystallization processes investigation of the amorphous Co67Fe3Cr3Si15B12 alloy. In-situ experiments on heating in a transmission electron microscope (TEM) column were carried out. Critical temperatures influencing material structure are determined. The onset temperature of material crystallization was determined.

  1. Microstructural Evolution of AlCoCrFeNiSi High-Entropy Alloy Powder during Mechanical Alloying and Its Coating Performance.

    Science.gov (United States)

    Tian, Lihui; Fu, Ming; Xiong, Wei

    2018-02-23

    High-entropy alloys (HEAs) are promising structural materials due to their excellent comprehensive performances. The use of mechanically alloyed powders to deposit HEA coatings through atmospheric plasma spraying (APS) is an effective approach that can broaden the application areas of the HEAs. In this paper, a ductility-brittleness AlCoCrFeNiSi system was chosen as an object of study, and the detailed evolution of the surface morphology, particle size distribution, and microstructure of the powder during mechanical alloying was investigated. An AlCoCrFeNiSi HEA coating was deposited using powder milled for 10 h, which can be used as an ideal feedstock for APS. The surface morphology, microstructure, microhardness, and wear behavior of the coating at room temperature were investigated. The results showed that as the milling time increased, the particle size first increased, and then decreased. At the milling time of 10 h, simple body-centered cubic (BCC) and face-centered cubic (FCC) solid solution phases were formed. After spraying, the lamellar structure inside a single particle disappeared. An ordered BCC phase was detected, and the diffraction peaks of the Si element also disappeared, which indicates that phase transformation occurred during plasma spraying. A transmission electron microscopy analysis showed that nanometer crystalline grains with a grain size of about 30 nm existed in the APS coating. For the coating, an average microhardness of 612 ± 41 HV was obtained. Adhesive wear, tribo-oxidation wear, and slight abrasion wear took place during the wear test. The coating showed good wear resistance, with a volume wear rate of 0.38 ± 0.08 × 10 -4 mm³·N -1 ·m -1 , which makes it a promising coating for use in abrasive environments.

  2. Quasicrystalline and crystalline phases in Al65Cu20(Fe, Cr)15 alloys

    International Nuclear Information System (INIS)

    Liu, W.; Koester, U.; Mueller, F.; Rosenberg, M.

    1992-01-01

    Two types of icosahedral quasicrystals are observed in Al 65 Cu 20 Fe 15-x Cr x (0 ≤ x ≤ 15) alloys, the face-centred AlCuFe-type icosahedral phase with dissoluted Cr and the primitive AlCuCr-type icosahedral phase with dissoluted Fe. In the vicinity of Al 65 Cu 20 Fe 8 Cr 7 a stable decagonal phase (a=0.45 nm and c=1.23 nm) forms competitively with the icosahedral quasicrystals. All these three quasicrystalline phases can be regarded as Hume-Rothery phases stabilized by the energy band factor. The density is measured to be 4.57, 4.44, and 4.11 g/cm 3 for the icosahedral Al 65 Cu 20 Fe 15 , the decagonal Al 65 Cu 20 Fe 8 Cr 7 , and the icosahedral Al 65 Cu 20 Cr 15 alloys, respectively. Depending on the composition in the range between Al 65 Cu 20 Fe 8 Cr 7 and Al 65 Cu 20 Cr 15 , several crystalline phases are observed during the transormation of the AlCuCr-type icosahedral phase: the 1/1-3/2-type orthorhombic (o) and the 1/0-3/2-type tetragonal (t) approximants of the decagonal phase, a hexagonal (h) phase, as well as a long-range vacancy ordered τ 3 -phase derived from a CsCl-type structure with a=0.2923 nm. The structures of all the crystalline phases are closely related to those of the icosahedral (i) and decagonal (d) quasicrystals, which leads to a definite orientation relationship as follows: i5 parallel d10 parallel o[100] parallel t[100] parallel h[001] parallel τ 3 [110]. (orig.)

  3. Room-Temperature Deformation and Martensitic Transformation of Two Co-Cr-Based Alloys

    Science.gov (United States)

    Cai, S.; Schaffer, J. E.; Huang, D.; Gao, J.; Ren, Y.

    2018-05-01

    Deformation of two Co-Cr alloys was studied by in situ synchrotron X-ray diffraction. Both alloys show stress-induced martensite transformation, which is affected by phase stabilities and transformation strains. Crystal structure of WC in Co-20Cr-15W-10Ni is identified. Compared with other phases present, it is elastically isotropic, exhibits high strength, and can elastically withstand strains exceeding 1 pct. Texture change during phase transformation is explained based on the crystal orientation relationship between γ- and ɛ-phases.

  4. Thermodynamics of oxygen solutions in Fe-40% Ni-15% Cr melts containing Mn, Si, Ti, Al

    International Nuclear Information System (INIS)

    Dashevskij, V.Ya.; Makarova, N.N.; Grigorovich, K.V.; Kashin, V.I.; Polikarpova, N.V.

    2000-01-01

    Thermodynamic analysis and experimental studied are performed for oxygen solutions in Fe-40% Ni-15% Cr melts where Mn, Si, Ti, Al are used as reducing agents. It is revealed that in the alloys studied the affinity of reducing agents to oxygen essentially lower than in liquid iron, nickel and Fe-40% Ni alloy. This is explained by the fact that the oxygen activity in melts noticeably decreases due to a high chromium content whereas the activity of reducing elements increases in a rather less degree. The agreement between analytical and experimental results confirms the validity of the calculation technique [ru

  5. Magnetism and electronic structure of CoFeCrX (X = Si, Ge) Heusler alloys

    International Nuclear Information System (INIS)

    Jin, Y.; O'Connell, A.; Kharel, P.; Lukashev, P.; Staten, B.; Tutic, I.; Valloppilly, S.; Herran, J.; Mitrakumar, M.; Bhusal, B.; Huh, Y.; Yang, K.; Skomski, R.; Sellmyer, D. J.

    2016-01-01

    The structural, electronic, and magnetic properties of CoFeCrX (X = Si, Ge) Heusler alloys have been investigated. Experimentally, the alloys were synthesized in the cubic L2 1 structure with small disorder. The cubic phase of CoFeCrSi was found to be highly stable against heat treatment, but CoFeCrGe disintegrated into other new compounds when the temperature reached 402 °C (675 K). Although the first-principle calculation predicted the possibility of tetragonal phase in CoFeCrGe, the tetragonal phase could not be stabilized experimentally. Both CoFeCrSi and CoFeCrGe compounds showed ferrimagnetic spin order at room temperature and have Curie temperatures (T C ) significantly above room temperature. The measured T C for CoFeCrSi is 790 K but that of CoFeCrGe could not be measured due to its dissociation into new compounds at 675 K. The saturation magnetizations of CoFeCrSi and CoFeCrGe are 2.82 μ B /f.u. and 2.78 μ B /f.u., respectively, which are close to the theoretically predicted value of 3 μ B /f.u. for their half-metallic phases. The calculated band gaps for CoFeCrSi and CoFeCrGe are, respectively, 1 eV and 0.5 eV. These materials have potential for spintronic device applications, as they exhibit half-metallic electronic structures with large band gaps, and Curie temperatures significantly above room temperature.

  6. Nature of the interfaces between the constituent phases in the high entropy alloy CoCrCuFeNiAl

    Energy Technology Data Exchange (ETDEWEB)

    Welk, Brian A.; Williams, Robert E.A.; Viswanathan, Gopal B. [Center for the Accelerated Maturation of Materials, Department of Materials Science and Engineering, The Ohio State University, 1305 Kinnear Road, Columbus, OH 43212 (United States); Gibson, Mark A. [CSIRO, Private Bag 33, Clayton, Victoria 3169 (Australia); Liaw, Peter K. [Department of Materials Science and Engineering, The University of Tennessee, 414 Ferris Hall, 1508 Middle Drive, Knoxville, TN 37996 (United States); Fraser, Hamish L., E-mail: fraser.3@osu.edu [Center for the Accelerated Maturation of Materials, Department of Materials Science and Engineering, The Ohio State University, 1305 Kinnear Road, Columbus, OH 43212 (United States)

    2013-11-15

    The interfaces between the phase separated regions in the dendritic grains of laser-deposited samples of the high entropy alloy CoCrCuFeNiAl have been studied using aberration-corrected analytical (scanning) transmission electron microscopy ((S)TEM). The compositional variations have been determined using energy dispersive x-ray spectroscopy (EDS) in (S)TEM. It was found that between B2, consisting mainly of Al, Ni, Co, and Fe, and disordered bcc phase, consisting mainly of Cr and Fe, there is a transition region, approximately 1.5 nm in width, over which the chemical composition changes from the B2 to that of the bcc phase. The crystal structure of this interfacial region is also B2, but with very different sublattice occupancy than that of the adjacent B2 compound. The structural aspects of the interface between the ordered B2 phase and the disordered bcc phase have been characterized using high angle annular dark-field (HAADF) imaging in STEM. It has been determined that the interfaces are essentially coherent, with the lattice parameters of the two B2 regions and the disordered bcc phase being more or less the same, the uncertainty arising from possible relaxations from the proximity of the surfaces of the thin foils used in imaging of the microstructures. Direct observations show that there is a planar continuity between all three constituent phases. - Highlights: • In the dendritic grains, there are two dominant phases, one with the ordered B2 structure, and the other disordered bcc. • From the intensity ratios in HAADF, the B2 phase appears to have a stoichiometry of the form Al(Ni, Co, and Fe). • Energy dispersive x-ray spectroscopy reveals the presence of an ordered interface transition region between the two phases. • Nanodiffraction in the Titan shows that the interface region is also ordered with the B2 crystal structure based on C.

  7. The role of Zr and Nb in oxidation/sulfidation behavior of Fe-Cr-Ni alloys

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K. (Argonne National Lab., IL (USA)); Baxter, D.J. (Argonne National Lab., IL (USA) INCO Alloy Ltd., Hereford, England (UK))

    1990-11-01

    05Structural Fe-Cr-Ni alloys may undergo rapid degradation at elevated temperatures unless protective surface oxide scales are formed and maintained. The ability of alloys to resist rapid degradation strongly depends on their Cr content and the chemistry of the exposure environment. Normally, 20 wt % Cr is required for service at temperatures up to 1000{degree}C; the presence of sulfur, however, inhibits formation of a protective surface oxide scale. The oxidation and sulfidation behavior of Fe-Cr-Ni alloys is examined over a wide temperature range (650 to 1000{degree}C), with particular emphasis on the effects of alloy Cr content and the radiation of reactive elements such as Nb and Zr. Both Nb and Zr are shown to promote protective oxidation behavior on the 12 wt % Cr alloy in oxidizing environments and to suppress sulfidation in mixed oxygen/sulfur environments. Additions of Nb and Zr at 3 wt % level resulted in stabilization of Cr{sub 2}O{sub 3} scale and led to a barrier layer of Nb- or Zr-rich oxide at the scale/metal interface, which acted to minimize the transport of base metal cations across the scale. Oxide scales were preformed in sulfur-free environments and subsequently exposed to oxygen/sulfur mixed-gas atmospheres. Preformed scales were found to delay the onset of breakaway corrosion. Corrosions test results obtained under isothermal and thermal cycling conditions are presented. 58 refs., 55 figs., 8 tabs.

  8. Characterization of rust layer formed on Fe, Fe-Ni and Fe-Cr alloys exposed to Cl-rich environment by Cl and Fe K-edge XANES measurements

    International Nuclear Information System (INIS)

    Konishi, Hiroyuki; Mizuki, Jun'ichiro; Yamashita, Masato; Uchida, Hitoshi

    2005-01-01

    Chloride in atmosphere considerably reduces the corrosion resistance of conventional weathering steel containing a small amount of Cr. Ni is an effective anticorrosive element for improving the corrosion resistance of steel in a Cl-rich environment. In order to clarify the structure of the protective rust layer of weathering steel, Cl and Fe K-edge X-ray absorption near edge structure (XANES) spectra of atmospheric corrosion products (rust) formed on Fe, Fe-Ni and Fe-Cr alloys exposed to Cl-rich atmosphere were measured. The Fe K-XANES measurements enable the characterization of mixture of iron oxides such as rust. The chemical composition of the rust was determined by performing pattern fitting of the measured spectra. All the rust is composed mainly of goethite, akaganeite, lepidocrocite and magnetite. Among these iron oxides, akaganeite in particular is the major component in the rust. Additionally, the amount of akaganeite in the rust of Fe-Ni alloy is much greater than that in rust of Fe-Cr alloy. Akaganeite is generally considered to facilitate the corrosion of steel, but our results indicate that akaganeite in the rust of Fe-Ni alloy is quantitatively different from that in rust of Fe-Cr alloy and does not facilitate the corrosion of steel. The shoulder peak observed in Cl K-XANES spectra reveals that the rust contains a chloride other than akaganeite. The energy of the shoulder peak does not correspond to that of any well-known chlorides. In the measured spectra, there is no proof that Cl, by combining with the alloying element, inhibits the alloying element from acting in corrosion resistance. The shoulder peak appears only when the content of the alloying element is lower than a certain value. This suggests that the generation of the unidentified chloride is related to the corrosion rate of steel. (author)

  9. Effect of pre-oxidation on high temperature sulfidation behavior of FeCr and FeCrAl alloys

    Directory of Open Access Journals (Sweden)

    Pillis Marina Fuser

    2004-01-01

    Full Text Available High temperature corrosion of structural alloys in sulfur bearing environments is many orders of magnitude higher than in oxidizing environments. Efforts to increase sulfidation resistance of these alloys include addition of alloying elements. Aluminum additions to iron-chromium alloys bring about increase in sulfidation resistance. This paper reports the effect of pre-oxidation on the sulfidation behavior of Fe-20Cr and Fe-20Cr-5Al alloys in H2-2% H2S environment at 800 °C. The surfaces of sulfidized specimens were also examined. Pre-oxidation of the two alloys results in an incubation period during subsequent sulfidation. After this incubation period, the Fe-20Cr alloy showed sulfidation behavior similar to that when the alloy was not pre-oxidized. The incubation period during sulfidation of the Fe-20Cr-5Al alloy was significantly longer, over 45 h, compared to 2 h for the Al free alloy. Based on the microscopic and gravimetric data a mechanism for sulfidation of these alloys with pre-oxidation has been proposed.

  10. Assessment of phase constitution on the Al-rich region of rapidly solidified Al-Co-Fe-Cr alloys

    International Nuclear Information System (INIS)

    Wolf, W.; Bolfarini, C.; Kiminami, C.S.; Botta, W.J.

    2016-01-01

    The formation of quasicrystalline approximants in rapidly solidified Al-Co-Fe-Cr alloys was investigated. Alloys of atomic composition Al 71 Co 13 Fe 8 Cr 8 , Al 77 Co 11 Fe 6 Cr 6 and Al 76 Co 19 Fe 4 Cr 1 were produced using melt spinning and arc melting methods and their microstructural characterization was carried out by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Up to the present there is no consensus in the literature regarding the formation of quasicrystalline phase or quasicrystalline approximants in the Al 71 Co 13 Fe 8 Cr 8 alloy. This work presents, for the first time, a detailed structural characterization of selected alloys in the Al-Co-Fe-Cr system close to the atomic composition Al 71 Co 13 Fe 8 Cr 8 . The results indicated the samples to be composed, mostly, by two intermetallic phases, which are quaternary extensions of Al 5 Co 2 and Al 13 Co 4 and are quasicrystalline approximants. Although the Al 5 Co 2 phase has already been reported in the Al 71 Co 13 Fe 8 Cr 8 alloy, the presence of the monoclinic Al 13 Co 4 is now identified for the first time in the as cast state. In the binary Al-Co system a quasicrystalline phase is known to form in a rapidly solidified alloy with composition close to the monoclinic and orthorhombic Al 13 Co 4 phases. This binary quasicrystalline phase presents an average valence electron per atom (e/a) between 1.7 and 1.9; thus, in addition to the Al 71 Co 13 Fe 8 Cr 8 alloy, the compositions Al 77 Co 11 Fe 6 Cr 6 and Al 76 Co 19 Fe 4 Cr 1 were chosen to be within the region of formation of the quaternary extension of the Al 13 Co 4 phase and also within the (e/a) of 1.7 to 1.9. However, no quasicrystalline phase is present in any of the studied alloys. The Al-Co-Fe-Cr system, around the compositions studied, is composed of quaternary extensions of Al-Co intermetallic phases, which present solubility of Fe and Cr at Co atomic sites. - Highlights: •The Al rich region of the AlCoFeCr

  11. Certain structural properties of the phase-binder of the alloys in W-Ni-Fe system

    International Nuclear Information System (INIS)

    Minakova, R.V.; Storchak, N.A.; Verkhovodov, P.A.; Bazhenova, L.G.; Poltoratskaya, V.L.

    1980-01-01

    The paper is concerned with effect of cooling conditions and subsequent heat treatment on grain size, lattice parameter and distribution of composing elements in the phase-binder of the W-Ni-Fe-alloy. The X-ray diffraction analysis was used to determine that the phase-binder structure depends on the heat treatment after liquid-phase sintering and consists of coarse grains with a diameter 3-8 mm for the annealed W-Ni-Fe-alloy decreasing to 40-100 μm at slow cooling. The determined change in solubility and of grain interface enrichment with tungsten in the phase-binder

  12. Ring head recording on perpendicular media: Output spectra for CoCr and CoCr/NiFe media

    Science.gov (United States)

    Stubbs, D. P.; Whisler, J. W.; Moe, C. D.; Skorjanec, J.

    1985-04-01

    The recording density response for sputtered CoCr (thickness=0.5 μm) and CoCr/NiFe (t=0.25 μm/0.5 μm) as well as evaporated CoNi (t=0.12 μm) and Co surface-doped iron oxide particulate media has been measured by reading and writing with Mn-Zn ferrite heads (gap length=0.375 μm, track width=37 μm) in contact with the media. Measurements to 200 kfc/i (thousand flux changes per inch) show a gap null around 115 kfc/i. The data have been normalized by dividing out the head sensitivity to obtain the value of spacing plus transition width (d+a) for the various media. For the CoCr media this value varied from 0.075-0.088 μm; for CoNi, 0.100 μm, and for the particulate medium, 0.163 μm. In addition, testing with a larger gapped Mn-Zn ferrite head (g=2.43 μm) shows that the head fields are distorted by the soft magnetic underlayer in dual layer CoCr/NiFe samples when the gap length is large compared to the distance to the underlayer.

  13. Flexural strength of pure Ti, Ni-Cr and Co-Cr alloys submitted to Nd:YAG laser or TIG welding.

    Science.gov (United States)

    Rocha, Rick; Pinheiro, Antônio Luiz Barbosa; Villaverde, Antonio Balbin

    2006-01-01

    Welding of metals and alloys is important to Dentistry for fabrication of dental prostheses. Several methods of soldering metals and alloys are currently used. The purpose of this study was to assess, using the flexural strength testing, the efficacy of two processes Nd:YAG laser and TIG (tungsten inert gas) for welding of pure Ti, Co-Cr and Ni-Cr alloys. Sixty cylindrical specimens were prepared (20 of each material), bisected and welded using different techniques. Four groups were formed (n=15). I: Nd:YAG laser welding; II- Nd:YAG laser welding using a filling material; III- TIG welding and IV (control): no welding (intact specimens). The specimens were tested in flexural strength and the results were analyzed statistically by one-way ANOVA. There was significant differences (pTIG and laser welding and also between laser alone and laser plus filling material. In conclusion, TIG welding yielded higher flexural strength means than Nd:YAG laser welding for the tested Ti, Co-Cr and Ni-Cr alloys.

  14. Linear thermal expansion coefficient of cast Fe-Ni invar and Fe-Ni-Co superinvar alloys

    International Nuclear Information System (INIS)

    Ogorodnikova, O.M.; Chermenskaya, E.V.; Rabinovich, S.V.; Grachev, S.V.

    1999-01-01

    Cast invar alloys Fe-Ni (28-35 wt. % Ni) are investigated using metallography, dilatometry and X-ray methods as soon as the crystallization is completed and again after low-temperature treatment resulting in martensitic transformation in low nickel alloys. Nickel distribution in a cast superinvar Fe-32% Ni-4% Co is studied by means of X-ray spectrum microanalysis. The results obtained permit the correction of model concepts about cast invars and the estimate of a coefficient of linear expansion depending on phase composition and nickel microsegregation [ru

  15. Properties of the passive films on Ni-Cr-Mo alloys

    International Nuclear Information System (INIS)

    Lloyd, A.C.; Noel, J.J.; McIntyre, N.S.; Shoesmith, D.W.

    2003-01-01

    Ni-Cr-Mo alloys are among the most corrosion resistant materials known, showing exceptional localized corrosion resistance under extreme industrial conditions. Accordingly, one such alloy, Alloy-22. is a candidate material for the outer sheathing of nuclear waste packages for the Yucca Mountain repository. Nevada, USA. We briefly report our results on the passive behaviour for a series of Ni-Cr-Mo alloys, with the emphasis on determining if there is a temperature dependence associated with it. The change of passive corrosion rate with temperature is a critical parameter required for long-term performance assessment calculations. The results show that alloy C22 performed better than the other members of the C-series of alloys under acidic conditions. This indicates that its selection as a waste package material is appropriate, and that it possess the potential for long-term containment of radio-nuclides. (author)

  16. Pulse electrodeposition of Fe-Ni-Cr alloys

    International Nuclear Information System (INIS)

    Adelkhani, H.

    2000-01-01

    Pulse Electroplating is a relativity new technique in electrodeposition of pure metals and alloys which has resulted in a number of improvement over the traditional direct current method. Among these are a better composition control, lower porosity, reduction of internal stresses and hydrogen content as well as other impurities. In this work Pulse plating of Fe-Ni-Cr alloys has been investigated by using a series of planned experiments. A domain of Pulse parameters, such a pulse frequency, pulse duration, current density and batch condition such as Ph, temperature and has been defined where the coating quality is optimal. The result obtained were Compared with those of D C electroplating and finally a number of recommendations are made for future works towards a semi-industrial process

  17. Si effects on radiation induced segregation in high purity Fe-18Cr-14Ni alloys irradiated by Ni ions

    International Nuclear Information System (INIS)

    Ohta, Joji; Kako, Kenji; Mayuzumi, Masami; Kusanagi, Hideo; Suzuki, Takayoshi

    1999-01-01

    To illustrate the effects of the element Si on radiation induced segregation, which causes irradiation assisted stress corrosion cracking (IASCC), we investigated grain boundary chemistry of high purity Fe-18Cr-14Ni-Si alloys irradiated by Ni ions using FE-TEM. The addition of Si up to 1% does not affect the Cr depletion at grain boundaries, while it slightly enhances the depletion of Fe and the segregation of Ni and Si. The addition of 2% Si causes the depletion of Cr and Fe and the segregation of Ni and Si at grain boundaries. Thus, the Si content should be as low as possible. In order to reduce the depletion of Cr at grain boundaries, which is one of the major causes of IASCC, Si content should be less than 1%. (author)

  18. Stress Corrosion Cracking of Ni-Fe-Cr Alloys Relevant to Nuclear Power Plants

    Science.gov (United States)

    Persaud, Suraj

    Stress corrosion cracking (SCC) of Ni-Fe-Cr alloys and weld metals was investigated in simulated environments representative of high temperature water used in the primary and secondary circuits of nuclear power plants. The mechanism of primary water SCC (PWSCC) was studied in Alloys 600, 690, 800 and Alloy 82 dissimilar metal welds using the internal oxidation model as a guide. Initial experiments were carried out in a 480°C hydrogenated steam environment considered to simulate high temperature reducing primary water. Ni alloys underwent classical internal oxidation intragranularly resulting in the expulsion of the solvent metal, Ni, to the surface. Selective intergranular oxidation of Cr in Alloy 600 resulted in embrittlement, while other alloys were resistant owing to their increased Cr contents. Atom probe tomography was used to determine the short-circuit diffusion path used for Ni expulsion at a sub-nanometer scale, which was concluded to be oxide-metal interfaces. Further exposures of Alloys 600 and 800 were done in 315°C simulated primary water and intergranular oxidation tendency was comparable to 480°C hydrogenated steam. Secondary side work involved SCC experiments and electrochemical measurements, which were done at 315°C in acid sulfate solutions. Alloy 800 C-rings were found to undergo acid sulfate SCC (AcSCC) to a depth of up to 300 microm in 0.55 M sulfate solution at pH 4.3. A focused-ion beam was used to extract a crack tip from a C-ring and high resolution analytical electron microscopy revealed a duplex oxide structure and the presence of sulfur. Electrochemical measurements were taken on Ni alloys to complement crack tip analysis; sulfate was concluded to be the aggressive anion in mixed sulfate and chloride systems. Results from electrochemical measurements and crack tip analysis suggested a slip dissolution-type mechanism to explain AcSCC in Ni alloys.

  19. Interfacial microstructure and performance of brazed diamond grits with Ni-Cr-P alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, C.Y. [Faculty of Mechanical and Electronic Engineering, Guangdong University of Technology, Guangzhou 510006 (China)], E-mail: cywang@gdut.edu.cn; Zhou, Y.M.; Zhang, F.L.; Xu, Z.C. [Faculty of Mechanical and Electronic Engineering, Guangdong University of Technology, Guangzhou 510006 (China)

    2009-05-12

    The reaction mechanism of the interface among diamond, commercial Ni-Cr-P alloy and steel substrate has been studied by optical microscopy, scanning electron microscope, X-ray diffraction and Raman spectroscopy. The reaction layers formed among diamond, brazing alloy and steel substrate produced good wettability of diamond grits for achieving better quality tools. The reaction layer between diamond and brazing alloy comprised a reaction layer of brazing alloy and a reaction layer of diamond. Cr{sub 7}C{sub 3} and Cr{sub 3}C{sub 2} formed in the reaction layer of brazing alloy was the main reason for improving the bonding strength of Ni-Cr alloy to the diamond grits. A reaction layer of diamond may be a graphitization layer formed on the surface of diamond under high temperature brazing. The reaction layer of brazing alloy and steel substrate was the co-diffusion of Ni, Cr and Fe between the brazing alloy and the steel substrate. The life and sharpness of brazed diamond boring drill bits fabricated in this study were superior to the electroplated one in the market owing to its high protrusion and bonding strength.

  20. Elevated-Temperature Corrosion of CoCrCuFeNiAl0.5Bx High-Entropy Alloys in Simulated Syngas Containing H2S

    Energy Technology Data Exchange (ETDEWEB)

    Dogan, Omer N; Nielsen, Benjamin C; Hawk, Jeffrey A

    2013-08-01

    High-entropy alloys are formed by synthesizing five or more principal elements in equimolar or near equimolar concentrations. Microstructure of the CoCrCuFeNiAl{sub 0.5}B{sub x} (x = 0, 0.2, 0.6, 1) high-entropy alloys under investigation is composed of a mixture of disordered bcc and fcc phases and borides. These alloys were tested gravimetrically for their corrosion resistance in simulated syngas containing 0, 0.01, 0.1, and 1 % H{sub 2}S at 500 °C. The exposed coupons were characterized using XRD and SEM. No significant corrosion was detected at 500 °C in syngas containing 0 and 0.01 % H{sub 2}S while significant corrosion was observed in syngas containing 0.1 and 1 % H{sub 2}S. Cu{sub 1.96}S was the primary sulfide in the external corrosion scale on the low-boron high-entropy alloys, whereas FeCo{sub 4}Ni{sub 4}S{sub 8} on the high-boron high-entropy alloys. Multi-phase Cu-rich regions in the low-B high-entropy alloys were vulnerable to corrosive attack.

  1. Glass forming ability and magnetic properties of Co{sub (40.2−x)}Fe{sub (20.1+x)}Ni{sub 6.7}B{sub 22.7}Si{sub 5.3}Nb{sub 5} (x=0–10) bulk metallic glasses produced by suction casting

    Energy Technology Data Exchange (ETDEWEB)

    Sarlar, Kagan [Physics Department, Faculty of Arts and Sciences, Uludag University, Gorukle Campus, 16059 Bursa (Turkey); Physics Department, Kamil Ozdag Faculty of Sciences, Karamanoglu Mehmetbey University, YunusEmre Campus, 70100 Karaman (Turkey); Kucuk, Ilker, E-mail: ikucuk@uludag.edu.tr [Physics Department, Faculty of Arts and Sciences, Uludag University, Gorukle Campus, 16059 Bursa (Turkey)

    2015-01-15

    The effect of Fe concentration on the glass forming ability (GFA) and magnetic properties in Co{sub (40.2−x)}Fe{sub (20.1+x)}Ni{sub 6.7}B{sub 22.7}Si{sub 5.3}Nb{sub 5} (x=0–10) bulk metallic glasses were investigated. By suction casting method, the bulk metallic glasses with diameters up to 2 mm were produced. We try to find out which Fe concentration makes an influence on Co based system's magnetic properties and glass forming ability. The curves of thermal analysis, obtained using differential scanning calorimetry (DSC), show that the Co{sub (40.2−x)}Fe{sub (20.1+x)}Ni{sub 6.7}B{sub 22.7}Si{sub 5.3}Nb{sub 5} (x=0–10) have a supercooled liquid region (∆T{sub x}) of about 44 K. The saturation magnetizations (J{sub s}) for as-cast BMG alloys were in the range of 0.62 T−0.81 T. - Highlights: • The effect of Fe concentration on the glass forming ability. • The substitution of an appropriate amount of Fe can enhance the GFA. • The substitution of Fe for Co also improves soft magnetic properties of the BMGs. • The high of J{sub s} 0.62−0.81 T with a low H{sub c} of 2−289 A/m of the alloys.

  2. Effects of air melting on Fe/0.3/3Cr/0.5Mo/2Mn and Fe/0.3C/3Cr/0.5Mo/2Ni structural alloy steels

    International Nuclear Information System (INIS)

    Steinberg, B.

    1979-06-01

    Changing production methods of a steel from vacuum melting to air melting can cause an increase in secondary particles, such as oxides and nitrides, which may have detrimental effects on the mechanical properties and microstructure of the alloy. In the present study a base alloy of Fe/0.3C/3Cr/0.5Mo with either 2Mn or 2Ni added was produced by air melting and its mechanical properties and microstructure were compared to an identical vacuum melted steel. Significant differences in mechanical behavior, morphology, and volume fraction of undissolved inclusions have been observed as a function of composition following air melting. For the alloy containing manganese, all properties remained very close to vacuum melted values but the 2Ni alloy displayed a marked loss in Charpy impact toughness and plane strain fracture toughness. This loss is attributed to an increase in volume fraction of secondary particles in the nickel alloy, as opposed to both the Mn alloy and vacuum melted alloys, as well as to substaintially increased incidence of linear coalescence of voids. Microstructural features are discussed

  3. Assessment of phase constitution on the Al-rich region of rapidly solidified Al-Co-Fe-Cr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, W., E-mail: witorw@gmail.com [Programa de Pós-Graduação em Ciência e Engenharia de Materiais, Universidade Federal de São Carlos, Rod. Washington Luiz, Km 235, 13565-905 São Carlos, SP (Brazil); Bolfarini, C., E-mail: cbolfa@ufscar.br [Departamento de Engenharia de Materiais, Universidade Federal de São Carlos, Rod. Washington Luiz, Km 235, 13565-905 São Carlos, SP (Brazil); Kiminami, C.S., E-mail: kiminami@ufscar.br [Departamento de Engenharia de Materiais, Universidade Federal de São Carlos, Rod. Washington Luiz, Km 235, 13565-905 São Carlos, SP (Brazil); Botta, W.J., E-mail: wjbotta@ufscar.br [Departamento de Engenharia de Materiais, Universidade Federal de São Carlos, Rod. Washington Luiz, Km 235, 13565-905 São Carlos, SP (Brazil)

    2016-12-15

    The formation of quasicrystalline approximants in rapidly solidified Al-Co-Fe-Cr alloys was investigated. Alloys of atomic composition Al{sub 71}Co{sub 13}Fe{sub 8}Cr{sub 8}, Al{sub 77}Co{sub 11}Fe{sub 6}Cr{sub 6} and Al{sub 76}Co{sub 19}Fe{sub 4}Cr{sub 1} were produced using melt spinning and arc melting methods and their microstructural characterization was carried out by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Up to the present there is no consensus in the literature regarding the formation of quasicrystalline phase or quasicrystalline approximants in the Al{sub 71}Co{sub 13}Fe{sub 8}Cr{sub 8} alloy. This work presents, for the first time, a detailed structural characterization of selected alloys in the Al-Co-Fe-Cr system close to the atomic composition Al{sub 71}Co{sub 13}Fe{sub 8}Cr{sub 8}. The results indicated the samples to be composed, mostly, by two intermetallic phases, which are quaternary extensions of Al{sub 5}Co{sub 2} and Al{sub 13}Co{sub 4} and are quasicrystalline approximants. Although the Al{sub 5}Co{sub 2} phase has already been reported in the Al{sub 71}Co{sub 13}Fe{sub 8}Cr{sub 8} alloy, the presence of the monoclinic Al{sub 13}Co{sub 4} is now identified for the first time in the as cast state. In the binary Al-Co system a quasicrystalline phase is known to form in a rapidly solidified alloy with composition close to the monoclinic and orthorhombic Al{sub 13}Co{sub 4} phases. This binary quasicrystalline phase presents an average valence electron per atom (e/a) between 1.7 and 1.9; thus, in addition to the Al{sub 71}Co{sub 13}Fe{sub 8}Cr{sub 8} alloy, the compositions Al{sub 77}Co{sub 11}Fe{sub 6}Cr{sub 6} and Al{sub 76}Co{sub 19}Fe{sub 4}Cr{sub 1} were chosen to be within the region of formation of the quaternary extension of the Al{sub 13}Co{sub 4} phase and also within the (e/a) of 1.7 to 1.9. However, no quasicrystalline phase is present in any of the studied alloys. The Al-Co-Fe-Cr system

  4. Microstructural evolution of Fe−22%Cr model alloy under thermal ageing and ion irradiation conditions studied by atom probe tomography

    Energy Technology Data Exchange (ETDEWEB)

    Korchuganova, Olesya A., E-mail: KorchuganovaOA@gmail.com [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 115409, Moscow (Russian Federation); State Scientific Center of the Russian Federation, Institute for Theoretical and Experimental Physics of National Research Centre “Kurchatov Institute”, 117218, Moscow (Russian Federation); Thuvander, Mattias [Chalmers University of Technology, SE-412 96, Göteborg (Sweden); Aleev, Andrey A.; Rogozhkin, Sergey V. [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 115409, Moscow (Russian Federation); State Scientific Center of the Russian Federation, Institute for Theoretical and Experimental Physics of National Research Centre “Kurchatov Institute”, 117218, Moscow (Russian Federation); Boll, Torben [Chalmers University of Technology, SE-412 96, Göteborg (Sweden); Kulevoy, Timur V. [State Scientific Center of the Russian Federation, Institute for Theoretical and Experimental Physics of National Research Centre “Kurchatov Institute”, 117218, Moscow (Russian Federation); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 115409, Moscow (Russian Federation)

    2016-08-15

    Nanostructure evolution during ion irradiation of two thermally aged binary Fee22Cr alloys has been investigated using atom probe tomography. Specimens aged at 500 °C for 50 and 200 h were irradiated by 5.6 MeV Fe ions at room temperature up to fluences of 0.3 × 10{sup 15} ions/cm{sup 2} and 1 × 10{sup 15} ions/cm{sup 2}. The effect of irradiation on the material nanostructure was examined at a depth of 1 μm from the irradiated surface. The analysis of Cr radial concentration functions reveals that dense α′-phase precipitates in the 200 h aged alloy become diffuse and thereby larger when subjected to irradiation. On the other hand, less Cr-enriched precipitates in the alloy aged for 50 h are less affected. The CreCr pair correlation function analysis shows that matrix inhomogeneity decreases under irradiation. Irradiation leads to a decrease in the number density of diffuse clusters, whereas in the case of well-developed precipitates it remains unchanged.

  5. Microstructural evolution of Fe−22%Cr model alloy under thermal ageing and ion irradiation conditions studied by atom probe tomography

    International Nuclear Information System (INIS)

    Korchuganova, Olesya A.; Thuvander, Mattias; Aleev, Andrey A.; Rogozhkin, Sergey V.; Boll, Torben; Kulevoy, Timur V.

    2016-01-01

    Nanostructure evolution during ion irradiation of two thermally aged binary Fee22Cr alloys has been investigated using atom probe tomography. Specimens aged at 500 °C for 50 and 200 h were irradiated by 5.6 MeV Fe ions at room temperature up to fluences of 0.3 × 10 15 ions/cm 2 and 1 × 10 15 ions/cm 2 . The effect of irradiation on the material nanostructure was examined at a depth of 1 μm from the irradiated surface. The analysis of Cr radial concentration functions reveals that dense α′-phase precipitates in the 200 h aged alloy become diffuse and thereby larger when subjected to irradiation. On the other hand, less Cr-enriched precipitates in the alloy aged for 50 h are less affected. The CreCr pair correlation function analysis shows that matrix inhomogeneity decreases under irradiation. Irradiation leads to a decrease in the number density of diffuse clusters, whereas in the case of well-developed precipitates it remains unchanged.

  6. Corrosion behavior of high purity Fe-Cr-Ni alloys in trans-passive condition

    International Nuclear Information System (INIS)

    Mayuzumi, Masami; Ohta, Jyoji; Kako, Kenji

    1998-01-01

    The corrosion behavior of high-purity (99.99%) Fe-Cr-Ni alloys was investigated in 13 N nitric acid with/without Ce 4+ ions to clarify the effect of impurities on the trans-passive corrosion of stainless steel. The following results were obtained. (1) Almost no intergranular corrosion was observed in the high-purity alloys, although the corrosion rate of the matrix region was nearly the same as that of a commercial stainless steel with the same Cr and Ni content. (2) Due to the improved intergranular corrosion resistance, the effect of the purification became significant in the corrosion condition with the grain-separation being predominant. (3) The high-purity alloys showed higher susceptivility to intergranular corrosion with aging treatment between 873 K and 1073 K. Although the sulfuric acid/copper sulfate test suggested the formation of Cr-depleted zones, a grain boundary micro-analysis using a FETEM with an EDX did not reveal any change in Cr content or impurity segregain along the grain boundaries. The mechanism of corrosion enhancement resulting from the aging treatment remains nuclear. (author)

  7. Mechanism of swelling suppression in phosphorous-modified Fe-Ni-Cr alloys

    International Nuclear Information System (INIS)

    Lee, E.H.; Mansur, L.K.

    1986-01-01

    Five simple alloys were ion irradiated at 948 0 K in an experiment designed to investigate the mechanism of swelling suppression associated with phosphorous additions. One of the alloys was the simple ternary Fe-15Ni-13Cr, another had 0.05% P added and the other three had further additions of the phosphide precipitate-forming elements Ti and/or Si. Ion irradiations were carried out with heavy ions only (Ni or Fe) or with heavy ions followed by dual heavy ions and helium. The ternary with and without P swelled readily early in dose with or without helium. The other three alloys only showed swelling in the presence of helium and exhibited a long delay in dose prior to the onset of swelling. These displayed fine distributions of Fe 2 P type phosphide precipitates enhanced by irradiation. The phosphide particles gave rise to very high concentrations of stable helium filled cavities at the precipitate matrix interfaces. The results were analyzed in terms of the theory of cavity swelling. The accumulation of the critical number of gas atoms in an individual cavity is required in the theory for point defect driven swelling to begin. It is concluded that the primary mechanism leading to swelling suppression is therefore the dilution of injected helium over a very large number of cavities. It is suggested that this mechanism may offer a key for alloy design for swelling resistance in high helium environments

  8. Analysis of PTA hardfacing with CoCrWC and CoCrMoSi alloys

    Directory of Open Access Journals (Sweden)

    Adriano Scheid

    2013-12-01

    Full Text Available CoCrWC alloys are widely used to protect components that operate under wear and high temperature environments. Enhanced performance has been achieved with the CoCrMoSi alloys but processing this alloy system is still a challenge due to the presence of the brittle Laves phase, particularly when welding is involved. This work evaluated Plasma Transferred Arc coatings processed with the Co-based alloy CoMoCrSi - Tribaloy T400, reinforced with Laves phase, comparing its weldability to the CoCrWC - Stellite 6, reinforced with carbides. Coatings were also analyzed regarding the response to temperature exposure at 600°C for 7 days and subsequent effect on microstructure and sliding abrasive wear. Coatings characterization was carried out by light and scanning electron microscopy, X-ray diffraction and Vickers hardness. CoCrWC coatings exhibited a Cobalt solid solution dendritic microstructure and a thin interdendritic region with eutectic carbides, while CoCrMoSi deposits exhibit a large lamellar eutectic region of Laves phase and Cobalt solid solution and a small fraction of primary Laves phase. Although phase stability was observed by X-ray diffraction, coarsening of the microstructure occurred for both alloys. CoCrMoSi showed thicker lamellar Laves phase and CoCrWC coarser eutectic carbides. Coatings stability assessed by wear tests revealed that although the wear rate of the as-deposited CoCrMoSi alloy was lower than that of CoCrWC alloy its increase after temperature exposure was more significant, 22% against 15%. Results were discussed regarding the protection of industrial components in particular, bearings in 55AlZn hot dip galvanizing components.

  9. Microstructural evolution of direct chill cast Al-15.5Si-4Cu-1Mg-1Ni-0.5Cr alloy during solution treatment

    Directory of Open Access Journals (Sweden)

    He Kezhun

    2011-08-01

    Full Text Available Heat treatment has important influence on the microstructure and mechanical properties of Al-Si alloys. The most common used heat treatment method for these alloys is solution treatment followed by age-hardening. This paper investigates the microstructural evolution of a direct chill (DC cast Al-15.5Si-4Cu-1Mg-1Ni-0.5Cr alloy after solution treated at 500, 510, 520 and 530℃, respectively for different times. The major phases observed in the as-cast alloy are α-aluminum dendrite, primary Si particle, eutectic Si, Al7Cu4Ni, Al5Cu2Mg8Si6, Al15(Cr, Fe, Ni, Cu4Si2 and Al2Cu. The Al2Cu phase dissolves completely after being solution treated for 2 h at 500℃, while the eutectic Si, Al5Cu2Mg8Si6 and Al15(Cr, Fe, Ni, Cu4Si2 phases are insoluble. In addition, the Al7Cu4Ni phase is substituted by the Al3CuNi phase. The α-aluminum dendrite network disappears when the solution temperature is increased to 530℃. Incipient melting of the Al2Cu-rich eutectic mixture occurrs at 520℃, and melting of the Al5Cu2Mg8Si6 and Al3CuNi phases is observed at a solution temperature of 530℃. The void formation of the structure and deterioration of the mechanical properties are found in samples solution treated at 530℃.

  10. Kinetic study of the annealing reactions in Cu-Ni-Fe alloys

    International Nuclear Information System (INIS)

    Donoso, E.

    2014-01-01

    The thermal aging of a Cu-45Ni-4Fe, Cu-34Ni-11Fe and Cu-33Ni-22Fe alloys tempered from 1173 K have been studied from Differential Scanning Calorimetry (DSC) and microhardness measurements. The analysis of DSC curves, from room temperature to 950 K, shows the presence of one exothermic reaction associated to the formation of FeNi 3 phase nucleating from a modulate structure, and one endothermic peak attributed to dissolution of this phase. Kinetic parameters were obtained using the usual Avrami-Erofeev equation, modified Kissinger method and integrated kinetic functions. Microhardness measurements confirmed the formation and dissolution of the FeNi 3 phase. (Author)

  11. Hydrogen storage properties of LaMgNi3.6M0.4 (M = Ni, Co, Mn, Cu, Al) alloys

    International Nuclear Information System (INIS)

    Yang, Tai; Zhai, Tingting; Yuan, Zeming; Bu, Wengang; Xu, Sheng; Zhang, Yanghuan

    2014-01-01

    Highlights: • La–Mg–Ni system AB 2 -type alloys were prepared by induction melting. • Structures and lattice parameters were analysed by XRD. • Hydrogen absorption/desorption performances were studied. • Mechanisms of hydrogen absorption capacity fading were investigated. - Abstract: LaMgNi 3.6 M 0.4 (M = Ni, Co, Mn, Cu, Al) alloys were prepared through induction melting process. The phase compositions and crystal structures were characterised via X-ray diffraction (XRD). The hydrogen storage properties, including activation performance, hydrogen absorption capacity, cycle stability, alloy particle pulverisation and plateau pressure, were systemically investigated. Results show that Ni, Co, Mn and Cu substitution alloys exhibit multiphase structures comprising the main phase LaMgNi 4 and the secondary phase LaNi 5 . However, the secondary phase of the Al substitution alloy changes into LaAlNi 4 . The lattice parameters and cell volumes of the LaMgNi 4 phase follow the order Ni < Co < Al < Cu < Mn. Activation is simplified through partial substitution of Ni with Al, Cu and Co. The hydrogen absorption capacities of all of the alloys are approximately 1.7 wt.% at the first activation process; however, they rapidly decrease with increasing cycle number. In addition, the stabilities of hydriding and dehydriding cycles decrease in the order Al > Co > Ni > Cu > Mn. Hydriding processes result in numerous cracks and amorphisation of the LaMgNi 4 phase in the alloys. The p–c isotherms were determined by a Sieverts-type apparatus. Two plateaus were observed for the Ni, Co and Al substitution alloys, whereas only one plateau was found for Mn and Cu. This result was caused by the amorphisation of the LaMgNi 4 phase during the hydriding cycles. Reversible absorption and desorption of hydrogen are difficult to achieve. Substitutions of Ni with Co, Mn, Cu and Al significantly influence the reduction of hysteresis between hydriding and dehydriding

  12. Development of Fe-Ni and Ni-base alloys without {gamma}' strengthening for advanced USC boilers

    Energy Technology Data Exchange (ETDEWEB)

    Semba, Hiroyuki; Okada, Hirokazu; Igarashi, Masaaki; Hirata, Hiroyuki [Sumitomo Metal Industries, Ltd., Amagasaki, Hyogo (Japan). Corporate Research and Development Labs.; Yoshizawa, Mitsuru [Sumitomo Metal Industries Ltd., Amagasaki, Hyogo (Japan). Steel Tube Works

    2010-07-01

    An Fe-Ni base alloy, 23Cr-45Ni-7W alloy (HR6W) strengthened by Fe{sub 2}W-type Laves phase is one of the candidate materials for the piping application. Stability of long-term creep strength and superior creep rupture ductility have been proved by creep rupture tests up to 60000h at 650-800 C. The 10{sup 5}h extrapolated creep rupture strength at 700 C approved by TUV is 85MPa. It has also been confirmed that HR6W has excellent microstructural stability by means of microstructural observations after term creep tests and aging. A thick wall pipe of HR6W, which is 457mm in diameter and 60mm in wall thickness, has successfully been manufactured by the Erhart Push Bench press method. This trial production has shown that hot workability of HR6W is sufficient for manufacturing thick wall piping for A-USC plants. A new Ni-base alloy, 30r-50Ni-4W alloy (HR35) has been proposed for piping application having comparable creep rupture strength with Alloy 617 at 700 C. This alloy is not strengthened by {gamma}' phase but mainly by {alpha}-Cr phase. The 10{sup 5}h extrapolated creep rupture strength is estimated to be 114 MPa at 700 C. It has sufficient creep rupture ductility compared with Alloy 617. A thick wall pipe of HR35 has also been successfully manufactured. Capability of HR6W and HR35 as structural materials for A-USC plants has been examined in detail. They have high resistance to relaxation cracking after welding. It is, therefore, concluded that both the alloys are promising candidates especially for thick wall piping in A-USC power plants. (orig.)

  13. High temperature oxidation characteristics of developed Ni-Cr-W superalloys in air

    International Nuclear Information System (INIS)

    Suzuki, Tomio; Shindo, Masami

    1996-11-01

    For expanding utilization of the Ni-Cr-W superalloy, which has been developed as one of new high temperature structural materials used in the advanced High Temperature Gas-cooled Reactors (HTGRs), in various engineering fields including the structural material for heat utilization system, the oxidation behavior of this alloy in air as one of high oxidizing environments becomes one of key factors. The oxidation tests for the industrial scale heat of Ni-Cr-W superalloy with the optimized chemical composition and five kinds of experimental Ni-Cr-W alloys with different Cr/W ratio were carried out at high temperatures in the air compared with Hastelloy XR. The conclusions were obtained as follows. (1) The oxidation resistance of the industrial scale heat of Ni-Cr-W superalloy with the optimized chemical composition was superior to that of Hastelloy XR. (2) The most excellent oxidation resistance was obtained in an alloy with 19% Cr of the industrial scale heat of Ni-Cr-W superalloy. (author)

  14. Selected Properties And Tribological Wear Alloys Co-Cr-Mo And Co-Cr-Mo-W Used In Dental Prosthetics

    Directory of Open Access Journals (Sweden)

    Augustyn-Pieniążek J.

    2015-09-01

    Full Text Available The presented work provides the results of the abrasive wear resistance tests performed on Co-Cr-Mo and Co-Cr-Mo-W alloys with the use of the Miller’s apparatus. The analyzed alloys underwent microstructure observations as well as hardness measurements, and the abraded surfaces of the examined materials were observed by means of electron scanning microscopy. The performed examinations made it possible to state that the Co-Cr alloys characterized in a high hardness, whereas the changes in the mass decrement were minimal, which proved a high abrasive wear resistance.

  15. Physical and Mechanical Properties of LoVAR: A New Lightweight Particle-Reinforced Fe-36Ni Alloy

    Science.gov (United States)

    Stephenson, Timothy; Tricker, David; Tarrant, Andrew; Michel, Robert; Clune, Jason

    2015-01-01

    Fe-36Ni is an alloy of choice for low thermal expansion coefficient (CTE) for optical, instrument and electrical applications in particular where dimensional stability is critical. This paper outlines the development of a particle-reinforced Fe-36Ni alloy that offers reduced density and lower CTE compared to the matrix alloy. A summary of processing capability will be given relating the composition and microstructure to mechanical and physical properties.

  16. Secondary phases in Al_xCoCrFeNi high-entropy alloys: An in-situ TEM heating study and thermodynamic appraisal

    International Nuclear Information System (INIS)

    Rao, J. C.

    2017-01-01

    Secondary phases, either introduced by alloying or heat treatment, are commonly present in most high-entropy alloys (HEAs). Understanding the formation of secondary phases at high temperatures, and their effect on mechanical properties, is a critical issue that is undertaken in the present paper, using the Al_xCoCrFeNi (x = 0.3, 0.5, and 0.7) as a model alloy. The in-situ transmission-electron-microscopy (TEM) heating observation, an atom-probe-tomography (APT) study for the reference starting materials (Al_0_._3 and Al_0_._5 alloys), and thermodynamic calculations for all three alloys, are performed to investigate (1) the aluminum effect on the secondary-phase fractions, (2) the annealing-twinning formation in the face-centered-cubic (FCC) matrix, (3) the strengthening effect of the secondary ordered body-centered-cubic (B2) phase, and (4) the nucleation path of the σ secondary phase thoroughly. Finally, the present work will substantially optimize the alloy design of HEAs and facilitate applications of HEAs to a wide temperature range.

  17. A Study of Thin Film Resistors Prepared Using Ni-Cr-Si-Al-Ta High Entropy Alloy

    Directory of Open Access Journals (Sweden)

    Ruei-Cheng Lin

    2015-01-01

    Full Text Available Ni-Cr-Si-Al-Ta resistive thin films were prepared on glass and Al2O3 substrates by DC magnetron cosputtering from targets of Ni0.35-Cr0.25-Si0.2-Al0.2 casting alloy and Ta metal. Electrical properties and microstructures of Ni-Cr-Si-Al-Ta films under different sputtering powers and annealing temperatures were investigated. The phase evolution, microstructure, and composition of Ni-Cr-Si-Al-Ta films were characterized by X-ray diffraction (XRD, transmission electron microscopy (TEM, and Auger electron spectroscopy (AES. When the annealing temperature was set to 300°C, the Ni-Cr-Si-Al-Ta films with an amorphous structure were observed. When the annealing temperature was at 500°C, the Ni-Cr-Si-Al-Ta films crystallized into Al0.9Ni4.22, Cr2Ta, and Ta5Si3 phases. The Ni-Cr-Si-Al-Ta films deposited at 100 W and annealed at 300°C which exhibited the higher resistivity 2215 μΩ-cm with −10 ppm/°C of temperature coefficient of resistance (TCR.

  18. The effect of 3 wt.% Cu addition on the microstructure, tribological property and corrosion resistance of CoCrW alloys fabricated by selective laser melting.

    Science.gov (United States)

    Luo, Jiasi; Wu, Songquan; Lu, Yanjin; Guo, Sai; Yang, Yang; Zhao, Chaoqian; Lin, Junjie; Huang, Tingting; Lin, Jinxin

    2018-03-19

    Microstructure, tribological property and corrosion resistance of orthopedic implant materials CoCrW-3 wt.% Cu fabricated by selective laser melting (SLM) process were systematically investigated with CoCrW as control. Equaxied γ-phase together with the inside {111}  type twin and platelet ε-phase was found in both the Cu-bearing and Cu-free alloys. Compared to the Cu-free alloy, the introduction of 3 wt.% Cu significantly increased the volume fraction of the ε-phase. In both alloys, the hardness of ε-phase zone was rather higher (~4 times) than that of γ-phase zone. The wear factor of 3 wt.% Cu-bearing alloy possessed smaller wear factor, although it had higher friction coefficient compared with Cu-free alloys. The ε-phase in the CoCr alloy would account for reducing both abrasive and fatigue wear. Moreover, the Cu-bearing alloy presented relatively higher corrosion potential E corr and lower corrosion current density I corr compared to the Cu-free alloy. Accordingly, 3 wt.% Cu addition plays a key role in enhancing the wear resistance and corrosion resistance of CoCrW alloys, which indicates that the SLM CoCrW-3Cu alloy is a promising personalized alternative for traditional biomedical implant materials.

  19. High-frequency permeability of electroplated CoNiFe and CoNiFe-C alloys

    International Nuclear Information System (INIS)

    Rhen, Fernando M.F.; McCloskey, Paul; O'Donnell, Terence; Roy, Saibal

    2008-01-01

    We have investigated CoNiFe and CoNiFe-C electrodeposited by pulse reverse plating (PRP) and direct current (DC) techniques. CoNiFe(PRP) films with composition Co 59.4 Fe 27.7 Ni 12.8 show coercivity of 95 A m -1 (1.2 Oe) and magnetization saturation flux (μ 0 M s ) of 1.8 T. Resistivity of CoNiFe (PRP) is about 24 μΩ cm and permeability remains almost constant μ r ' ∼475 up to 30 MHz with a quality factor (Q) larger than 10. Additionally, the permeability spectra analysis shows that CoNiFe exhibits a classical eddy current loss at zero bias field and ferromagnetic resonance (FMR) when biased with 0.05 T. Furthermore, a crossover between eddy current and FMR loss is observed for CoNiFe-PRP when baised with 0.05 T. DC and PRP plated CoNiFe-C, which have resistivity and permeability of 85, 38 μΩ cm, μ r '=165 and 35 with Q>10 up to 320 MHz, respectively, showed only ferromagnetic resonance losses. The ferromagnetic resonance peaks in CoNiFe and CoNiFe-C are broad and resembles a Gaussian distribution of FMR frequencies. The incorporation of C to CoNiFe reduces eddy current loss, but also reduces the FMR frequency

  20. Microstructural response of an Al-modified Ni-Cr-Fe ternary alloy during thermal processing

    Energy Technology Data Exchange (ETDEWEB)

    Akinlade, D.A. [Department of Mechanical and Manufacturing Engineering, University of Manitoba, Winnipeg, MB (Canada)], E-mail: dotun172@yahoo.co.uk; Caley, W.F. [Department of Process Engineering and Applied Science, Dalhousie University, Halifax, NS (Canada); Richards, N.L.; Chaturvedi, M.C. [Department of Mechanical and Manufacturing Engineering, University of Manitoba, Winnipeg, MB (Canada)

    2008-07-15

    A thermodynamic package was used to predict the phase transformations that occurred during thermal processing of a superalloy based on the composition of a ternary Ni-Cr-Fe alloy. The effect of the addition of 6 w/o Al on phase transformation in the material sintered were estimated and compared with results obtained experimentally by X-ray diffraction and metallography, while the transformation temperature of the modified alloy was corroborated by differential scanning calorimetry (DSC). Mechanical property of the alloy was estimated in terms of Vickers hardness. These results suggest that despite potential problems encountered in high-temperature powder processing of superalloys that often tend to influence the feasibility of using thermodynamic predictions to model such alloy systems, the software and predictions used in this study offer a way to simulate both design and characterisation of the experimental alloy.

  1. Microstructure and Wear Behavior of CoCrFeMnNbNi High-Entropy Alloy Coating by TIG Cladding

    Directory of Open Access Journals (Sweden)

    Wen-yi Huo

    2015-01-01

    Full Text Available Alloy cladding coatings are widely prepared on the surface of tools and machines. High-entropy alloys are potential replacements of nickel-, iron-, and cobalt-base alloys in machining due to their excellent strength and toughness. In this work, CoCrFeMnNbNi HEA coating was produced on AISI 304 steel by tungsten inert gas cladding. The microstructure and wear behavior of the cladding coating were studied by X-ray diffraction, scanning electron microscopy, energy dispersive spectrometer, microhardness tester, pin-on-ring wear tester, and 3D confocal laser scanning microscope. The microstructure showed up as a nanoscale lamellar structure matrix which is a face-centered-cubic solid solution and niobium-rich Laves phase. The microhardness of the cladding coating is greater than the structure. The cladding coating has excellent wear resistance under the condition of dry sliding wear, and the microploughing in the worn cladding coating is shallower and finer than the worn structure, which is related to composition changes caused by forming the nanoscale lamellar structure of Laves phase.

  2. Phase transformation in rapidly quenched Fe-Cr-Co-Mo-Ti-Si-B alloys

    Science.gov (United States)

    Zhukov, D. G.; Shubakov, V. S.; Zhukova, E. Kh; Gorshenkov, M. V.

    2018-03-01

    The research results of phase transformations in Fe-24Cr-16Co-3Mo-0.2Ti-1Si-B alloys (with a boron content of 1 to 3% by mass) obtained by rapid quenching are presented. The structure formation regularities during the melt spinning and during the subsequent crystallization annealing in rapidly quenched bands of the Fe-Cr-Co-Mo-Ti-Si-B system alloys were studied. The changes in the phase composition of the rapidly quenched Fe-Cr-Co-Mo-Ti- Si-B system alloys after quenching at various quench rates and at different boron concentrations in the alloys are studied. It is shown that during crystallization from an amorphous state, at temperatures above 570 °C, in addition to the α-phase, the σ-phase appears first, followed by the γ-phase. Heat treatment of rapidly quenched bands to high-coercive state was carried out. A qualitative assessment of magnetic properties in a high-coercivity state was carried out. An evaluation of the level of magnetic properties in a high-coercivity state allows us to conclude that the application of a magnetic field during crystallization from an amorphous state leads to anisotropy of the magnetic properties, that is, an anisotropic effect of thermo-magnetic treatment is detected.

  3. Stacking fault energy measurements in solid solution strengthened Ni-Cr-Fe alloys using synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Unfried-Silgado, Jimy [Metals Characterization and Processing Laboratory, Brazilian Nanothecnology National Laboratory - CNPEM/ABTLuS, Caixa Postal 6192, CEP 13083-970, Campinas, Sao Paulo (Brazil); Universidade Estadual de Campinas UNICAMP, Faculdade de Engenharia Mecanica FEM, Campinas (Brazil); Universidad Autonoma del Caribe, Grupo IMTEF, Ingenieria Mecanica, Barranquilla (Colombia); Wu, Leonardo [Metals Characterization and Processing Laboratory, Brazilian Nanothecnology National Laboratory - CNPEM/ABTLuS, Caixa Postal 6192, CEP 13083-970, Campinas, Sao Paulo (Brazil); Furlan Ferreira, Fabio [Universidade Federal do ABC, Centro de Ciencias Naturais e Humanas (CCNH), Sao Paulo (Brazil); Mario Garzon, Carlos [Universidad Nacional de Colombia, Departamento de Fisica, Bogota (Colombia); Ramirez, Antonio J, E-mail: antonio.ramirez@lnnano.org.br [Metals Characterization and Processing Laboratory, Brazilian Nanothecnology National Laboratory - CNPEM/ABTLuS, Caixa Postal 6192, CEP 13083-970, Campinas, Sao Paulo (Brazil)

    2012-12-15

    The stacking fault energy (SFE) in a set of experimental Ni-Cr-Fe alloys was determined using line profile analysis on synchrotron X-ray diffraction measurements. The methodology used here is supported by the Warren-Averbach calculations and the relationships among the stacking fault probability ({alpha}) and the mean-square microstrain (<{epsilon}{sup 2}{sub L}>). These parameters were obtained experimentally from cold-worked and annealed specimens extracted from the set of studied Ni-alloys. The obtained results show that the SFE in these alloys is strongly influenced by the kind and quantity of addition elements. Different effects due to the action of carbide-forming elements and the solid solution hardening elements on the SFE are discussed here. The simultaneous addition of Nb, Hf, and, Mo, in the studied Ni-Cr-Fe alloys have generated the stronger decreasing of the SFE. The relationships between SFE and the contributions on electronic structure from each element of additions were established.

  4. Comparison of the irradiation effects on swelling and microstructure in commercial alloy A-286 and a simple Fe--25 Ni--15Cr gamma prime hardened alloy

    International Nuclear Information System (INIS)

    Chickering, R.W.; Bajaj, R.; Lally, J.S.

    1977-01-01

    The irradiation behaviors of alloy A-286 as well as experimental gamma prime hardened alloys are being studied in the National Alloy Development Program for application of gamma prime hardened alloys in the liquid metal fast breeder reactor. The principal direction of the studies concerns the high temperature strength and swelling resistance of the alloys. Minor element compositions may affect the phase stability and void swelling. A high Ti to Al ratio indicates a tendency for the gamma prime Ni 3 (Ti,Al) to transform into eta phase (Ni 3 Ti) after long term thermal aging and irradiation enhances the tendency for transformation. Another minor element, Si, as a constituent of G-phase, and irradiation may enhance G-phase formation. The Ti, Al, and Si contents affect the swelling of Fe-Cr-Ni alloys. The swelling resistance generally increases with increasing amounts of these three elements in the matrix. In the study the effects of Ti to Al ratio, Ti content, Al content, and Si content on swelling and phase stability were analyzed after Ni-ion irradiation

  5. Cl K-edge XANES spectra of atmospheric rust on Fe, Fe-Cr and Fe-Ni alloys exposed to saline environment

    International Nuclear Information System (INIS)

    Konishi, Hiroyuki; Mizuki, Jun'ichiro; Yamashita, Masato; Uchida, Hitoshi

    2004-01-01

    Cl K-edge XANES measurements of atmospheric corrosion products (rust) formed on Fe, Fe-Ni and Fe-Cr alloys in chloride pollution have been performed using synchrotron radiation in order to clarify roles of anticorrosive alloying elements and of Cl in the corrosion resistance of weathering steel. The spectra of binary alloys show a shoulder structure near the absorption edge. The intensity of the shoulder peak depends on the kind and amount of the alloying element, whereas the energy position is invariant. This indicates that Cl is not combined directly with alloying elements in the rust. (author)

  6. Corrosion resistance of amorphous NiCrZr and NiCrMoZr alloys

    International Nuclear Information System (INIS)

    Naka, M.; Miyake, M.; Okamoto, I.

    1987-01-01

    One of the authors has reported that the corrosion resistance of chromium containing amorphous alloys is extremely improved by alloying phosphorus among metalloids. Two factors operate for the improvement of corrosion resistance of the amorphous alloys. First, phosphorus serves for the rapid formation of protective passive film. Second, the compositional and structural homogeneity in amorphous state also account for the formation of protective film. The latter factor has been clearly seen in the high corrosion resistance of CoCrMoZr and CoCrWZr alloys without metalloids. In order to clarify the separately two factors in the corrosion resistance of amorphous alloys, the corrosion resistance of amorphous alloys without metalloids has to be further investigated. This paper also deals with the corrosion resistance and electrochemical behavior of NiCrZr and NiCrMoZr alloys in 1N HCl, and compare them with the corrosion behavior of the crystalline alloys containing the same composition as that of the amorphous alloys

  7. Effects of Different Levels of Boron on Microstructure and Hardness of CoCrFeNiAlxCu0.7Si0.1By High-Entropy Alloy Coatings by Laser Cladding

    Directory of Open Access Journals (Sweden)

    Yizhu He

    2017-01-01

    Full Text Available High-entropy alloys (HEAs are novel solid solution strengthening metallic materials, some of which show attractive mechanical properties. This paper aims to reveal the effect of adding small atomic boron on the interstitial solid solution strengthening ability in the laser cladded CoCrFeNiAlxCu0.7Si0.1By (x = 0.3, x = 2.3, and 0.3 ≤ y ≤ 0.6 HEA coatings. The results show that laser rapid solidification effectively prevents brittle boride precipitation in the designed coatings. The main phase is a simple face-centered cubic (FCC matrix when the Al content is equal to 0.3. On the other hand, the matrix transforms to single bcc solid solution when x increases to 2.3. Increasing boron content improves the microhardness of the coatings, but leads to a high degree of segregation of Cr and Fe in the interdendritic microstructure. Furthermore, it is worth noting that CoCrFeNiAl0.3Cu0.7Si0.1B0.6 coatings with an FCC matrix and a modulated structure on the nanometer scale exhibit an ultrahigh hardness of 502 HV0.5.

  8. High-resolution electron microscopy study of Ni81Fe19 film with Co33Cr67 buffer layer

    International Nuclear Information System (INIS)

    Xu, Q.Y.; Wang, Z.M.; Shen, F.; Du, Y.W.; Zhang, Z.

    2003-01-01

    The anisotropic magnetoresistance (AMR) in permalloy Ni 81 Fe 19 film deposited on a 1.2 nm Co 33 Cr 67 buffer layer was significantly enhanced. The high-resolution electron microscopy was used to study the microstructure of Ni 81 Fe 19 film with and without Co 33 Cr 67 buffer layer. It was found that Co 33 Cr 67 buffer layer can induce good (1 1 1) texture, while without Co 33 Cr 67 buffer layer, Ni 81 Fe 19 film show randomly oriented grain structure. The Δρ/ρ enhancement is attributed to the decrease in the resistivity ρ of the Ni 81 Fe 19 film due to the formation of the large (1 1 1) textured grains in Ni 81 Fe 19 film with Co 33 Cr 67 buffer layer. However, the surface roughness of substrate may limit the (1 1 1) textured grain size and induce additional grain boundaries in Ni 81 Fe 19 film with Co 33 Cr 67 buffer layer, limit the enhancement of the AMR effect

  9. Alloying and heat treatment optimization of Fe/Cr/C steels for improved mechanical properties

    International Nuclear Information System (INIS)

    Sarikaya, M.

    1979-06-01

    The effects of alloying elements and heat treatments on the microstructural changes and strength-toughness properties were investigated in optimization of vacuum melted Fe/Cr/C base steels. The structure of the steels in the as-quenched conditions consisted of highly dislocated autotempered lath martensite (strong phase) and thin continuous interlath films of retained austenite (tough phase). It has been emphasized again that the mechanical properties of the steels are sensitive to the amount and the stability of retained austenite. To increase the stability of retained austenite in the as-quenched condition 2 w/o Mn or 2 w/o Ni was added to the base steel, viz., Fe/3Cr/0.3C. Partial replacement of Cr by about 0.5 w/o Mo did not alter the beneficial microstructure

  10. Deformation Behavior of Al0.25CoCrFeNi High-Entropy Alloy after Recrystallization

    Directory of Open Access Journals (Sweden)

    Jinxiong Hou

    2017-03-01

    Full Text Available Cold rolling with subsequent annealing can be used to produce the recrystallized structure in high entropy alloys (HEAs. The Al0.25CoCrFeNi HEAs rolled to different final thickness (230, 400, 540, 800, 1000, 1500 μm are prepared to investigate their microstructure evolutions and mechanical behaviors after annealing. Only the single face-centered cubic phase was obtained after cold rolling and recrystallization annealing at 1100 °C for 10 h. The average recrystallized grain size in this alloy after annealing ranges from 92 μm to 136 μm. The annealed thin sheets show obviously size effects on the flow stress and formability. The yield strength and tensile strength decrease as t/d (thickness/average grain diameter ratio decreases until the t/d approaches 2.23. In addition, the stretchability (formability decreases with the decrease of the t/d ratio especially when the t/d ratio is lower than about 6. According to the present results, yield strength can be expressed as a function of the t/d ratio.

  11. Properties of ternary NiFeW alloy coating by jet electrodeposition

    Indian Academy of Sciences (India)

    In this paper, ternary NiFeW alloy coatings were prepared by jet electrodeposition, and the effects of lord salt concentration, jet speed, current density and temperature on the properties of the coatings, including the composition, microhardness, surface morphology, structure and corrosion resistance, were investigated.

  12. Structure of Ni-rich Ni--Cr--B--Si coating alloys

    International Nuclear Information System (INIS)

    Knotek, O.; Lugscheider, E.; Reimann, H.

    1975-01-01

    The structures of quaternary, nickel-rich Ni--Cr--B--Si alloys were analyzed at a constant boron content of 10 at. percent and a temperature of 850 0 C. The composition range for silicide formation was determined. In these quaternary alloys, known binary nickel silicides, nickel and chromium borides, and the ternary silico-boride Ni 6 Si 2 B were confirmed. A new composition for the W 5 Si 3 -type phase in the Ni--B--Si system was proposed. (U.S.)

  13. Study of the microstructure and of microhardness variation of a Ni-Fe-Cr austenitic alloy by niobium

    International Nuclear Information System (INIS)

    Carvalho e Camargo, M.U. de; Lucki, G.

    1979-01-01

    The mechanisms of hardening and corrosion resistance increase in Ni-Fe-Cr austenitic stainless steels by Nb additions are of interest to nuclear technology Niobium additions to a 321 type stainless steel were made in order to study the microhardness, electrical resistivity and metallography. Experimental measurements results are shown. The effect of Nb additions as a micro-alloying element and the thermal and mechanical processes (cold working in particular) in the microstructure and microhardness properties of the 11% Ni - 70%Fe - 17% Cr austenitic alloys were studied. (Author) [pt

  14. On the corrosion testing of weldments of high alloyed CrNiMo-stainless steels and NiCrMo-alloys

    International Nuclear Information System (INIS)

    Riedel, G.; Voigt, C.; Werner, H.

    1997-01-01

    Weldments of high-alloyed CrNiMo stainless steels and NiCrMo alloys can be more susceptible to localized corrosion than the solution annealed basic material owing to segregations and precipitations in the heat affected zone, the high temperature zone and/or in the weld. To investigate these differences the FeCl 3 -test (10% FeCl 3 . 6aq), the test ''green death'' (11.5% H 2 SO 4 , 1.2% HCl, 1% CuCl 2 , 1% FeCl 3 ) as well as chronopotentiostatic tests in artificial sea water or in 3% NaCl-solution are used. In particular for testing the highest alloyed materials a CaCl 2 -test was developed (4.5 M CaCl 2 , chronopotentiostatic test in duration of 8 to 10 hours at + 200 mV (SCE)), which can be carried out to a temperature of 115 C at atmospheric pressure. The aggressivity increases in the range FeCl 3 -test, ''green death''-test, CaCl 2 -test. Matching and graduated over-alloyed weldments (TIG, heat input of 7 and 15.5 kJ/cm) of materials 1.4529, 1.4562, 2.4856, 2.4819 (german materials No.) are comparingly examined in various tests, of materials 1.4406, 1.4539, 1.4439 and 1.4563 (german materials No.) only matching weldments in the FeCl 3 -test. In strongly oxidizing media only a highly over-alloyed performed weldment (filler material 2.4607, german material No.) produces the best corrosion behaviour, measured as the critical temperatures of localized corrosion. Measurements of critical current densities of passivation can be used for investigations of corrosion behaviour of weldments, too. Critical current densities of passivation are showing a tendency to inverse proportion to the critical temperatures of localized corrosion. Suitable electrolytes are among others 0.2 M H 2 SO 4 + 1 M NaCl + 10 -3 % KSCN, N 2 -bubbled, 25 to 60 C and xM H 2 SO 4 + 4 M NaCl + 10 -3 % KSCN (x = 0.05 to 1), 25 C, in contact with air. An influence of heat input at the welding is indicated in the test of localized corrosion, but it is only small. It is sometimes more clearly shown at

  15. Structural, thermal and photomagnetic properties of spin crossover [Fe(bpp)2]2+ salts bearing [Cr(L)(ox)2]- anions.

    Science.gov (United States)

    Clemente-León, Miguel; Coronado, Eugenio; Giménez-López, M Carmen; Romero, Francisco M; Asthana, Saket; Desplanches, Cédric; Létard, Jean-François

    2009-10-14

    This paper is divided into two parts: in the first part, the influence of solvate molecules on the magnetic properties of spin crossover salts of [Fe(bpp)(2)][Cr(L)(ox)(2)]ClO(4) x nS (bpp = 2,6-bis(pyrazol-3yl)pyridine; L = 2,2'-bipyridine (bpy) or 1,10-phenanthroline (phen); ox = oxalate dianion; S = solvent) is analyzed. The second part is devoted to the photomagnetic properties of the previously reported [Fe(bpp)(2)][Cr(L)(ox)(2)](2) family of compounds. The study describes the crystal structure, differential scanning calorimetry (DSC) and magnetic properties of [Fe(bpp)(2)][Cr(bpy)(ox)(2)]ClO(4) x EtOH x 4 H(2)O (1) and [Fe(bpp)(2)][Cr(phen)(ox)(2)]ClO(4) x 1.5 EtOH x 4 H(2)O (2). Both salts are high-spin (HS) compounds. Desolvation of 1 yields a material exhibiting a gradual spin crossover that involves 50% of the Fe(2+) cations. Rehydration of this desolvated salt induces a significant increase in the low-spin (LS) population. Desolvation of 2 affords a material showing a more abrupt spin crossover with thermal hysteresis (T(1/2)(increasing) = 286 K and T(1/2)(decreasing) = 273 K). This material is not very sensitive to rehydration. The anhydrous compounds [Fe(bpp)(2)][Cr(bpy)(ox)(2)](2) (3) and [Fe(bpp)(2)][Cr(phen)(ox)(2)](2) (4) display some quantitative photomagnetic conversion with T(LIESST) values of 41 and 51 K, respectively. Kinetic parameters governing the photo-induced HS-LS relaxation process have been determined and used to reproduce the T(LIESST) curves.

  16. Effect of Cu on microstructure, mechanical properties, corrosion resistance and cytotoxicity of CoCrW alloy fabricated by selective laser melting.

    Science.gov (United States)

    Lu, Yanjin; Ren, Ling; Xu, Xiongcheng; Yang, Yang; Wu, Songquan; Luo, Jiasi; Yang, Mingyu; Liu, Lingling; Zhuang, Danhong; Yang, Ke; Lin, Jinxin

    2018-05-01

    In the study, CoCrWCu alloys with differing Cu content (2, 3, 4 wt%) were prepared by selective laser melting using mixture powders consisting of CoCrW and Cu, aiming at investigating the effect of Cu on the microstructures, mechanical properties, corrosion behavior and cytotoxicity. The SEM observations indicated that the Cu content up to 3 wt% caused the Si-rich precipitates to segregate along grain boundaries and in the grains, and EBSD analysis suggested that the Cu addition decreased the recrystallization degree and increased the grain diameter and fraction of big grains. The tensile tests found that the increasing Cu content led to a decrease of mechanical properties compared with Cu-free CoCrW alloy. The electrochemical tests revealed that the addition of Cu shifted the corrosion potential toward nobler positive, but increased the corrosion current density. Also, a more protective passive film was formed when 2 wt% Cu content was added, but the higher Cu content up to 3 wt% was detrimental to the corrosion resistance. It was noted that there was no cytotoxicity for Cu-bearing CoCrW alloys to MG-63 cell and the cells could spread well on the surfaces of studied alloys. Meanwhile, the Cu-bearing CoCrW alloy exhibited an excellent antibacterial performance against E.coli when Cu content was up to 3 wt%. It is suggested that the feasible fabrication of Cu-bearing CoCrW alloy by SLM using mixed CoCrW and Cu powders is a promising candidate for use in antibacterial oral repair products. This current study also can aid in the further design of antibacterial Cu-containing CoCrW alloying powders. Copyright © 2018 Elsevier Ltd. All rights reserved.

  17. Difference between Cr and Ni K-edge XANES spectra of rust layers formed on Fe-based binary alloys exposed to Cl-rich environment

    International Nuclear Information System (INIS)

    Konishi, Hiroyuki; Mizuki, Jun'ichiro; Yamashita, Masato; Uchida, Hitoshi

    2005-01-01

    The rust layer formed on weathering steel possesses a strong protective ability against corrosives in an atmospheres. This ability is related to the structure of the rust layer. The difference in the protective ability of a rust layer. The difference in the protective ability of a rust layer in a Cl-rich environment between conventional weathering steel containing Cr and advanced weathering steel containing Ni is believed to be caused by the differences in local structural and chemical properties between alloying elements. Cr and Ni, in the rust layer. In order to examine the effect of these alloying elements on the structure of the rust layer formed on steel in a Cl-rich environment, we have performed Cr and Ni K-edge X-ray absorption near-edge structure (XANES) measurements for the rust layer of Fe-Cr and Fe-Ni binary alloys exposed to a Cl-rich atmosphere using synchrotron radiation. The results of the Cr K-edge XANES measurements for the rust layer of Fe-Cr binary alloys show that the atomic geometry around Cr depends on the concentration of Cr. Therefore, it is expected that the local structure around Cr in the rust layer is unstable. On the other hand, from the results of the Ni K-edge XANES measurements for the rust layer of Fe-Ni binary alloys. Ni is considered to be positioned at a specific site in the crystal structure of a constituent of the rust layer, such as akaganeite or magnetite. As a consequence, Ni negligibly interacts with Cl - ions in the rust layer. (author)

  18. Hydrogen storage properties of LaMgNi{sub 3.6}M{sub 0.4} (M = Ni, Co, Mn, Cu, Al) alloys

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Tai [Department of Functional Material Research, Central Iron and Steel Research Institute, Beijing 100081 (China); Key Laboratory of Integrated Exploitation of Baiyun Obo Multi-Metal Resources, Inner Mongolia University of Science and Technology, Baotou 014010 (China); Zhai, Tingting; Yuan, Zeming; Bu, Wengang [Department of Functional Material Research, Central Iron and Steel Research Institute, Beijing 100081 (China); Xu, Sheng [Key Laboratory of Integrated Exploitation of Baiyun Obo Multi-Metal Resources, Inner Mongolia University of Science and Technology, Baotou 014010 (China); Zhang, Yanghuan, E-mail: zhangyh59@sina.com [Department of Functional Material Research, Central Iron and Steel Research Institute, Beijing 100081 (China); Key Laboratory of Integrated Exploitation of Baiyun Obo Multi-Metal Resources, Inner Mongolia University of Science and Technology, Baotou 014010 (China)

    2014-12-25

    Highlights: • La–Mg–Ni system AB{sub 2}-type alloys were prepared by induction melting. • Structures and lattice parameters were analysed by XRD. • Hydrogen absorption/desorption performances were studied. • Mechanisms of hydrogen absorption capacity fading were investigated. - Abstract: LaMgNi{sub 3.6}M{sub 0.4} (M = Ni, Co, Mn, Cu, Al) alloys were prepared through induction melting process. The phase compositions and crystal structures were characterised via X-ray diffraction (XRD). The hydrogen storage properties, including activation performance, hydrogen absorption capacity, cycle stability, alloy particle pulverisation and plateau pressure, were systemically investigated. Results show that Ni, Co, Mn and Cu substitution alloys exhibit multiphase structures comprising the main phase LaMgNi{sub 4} and the secondary phase LaNi{sub 5}. However, the secondary phase of the Al substitution alloy changes into LaAlNi{sub 4}. The lattice parameters and cell volumes of the LaMgNi{sub 4} phase follow the order Ni < Co < Al < Cu < Mn. Activation is simplified through partial substitution of Ni with Al, Cu and Co. The hydrogen absorption capacities of all of the alloys are approximately 1.7 wt.% at the first activation process; however, they rapidly decrease with increasing cycle number. In addition, the stabilities of hydriding and dehydriding cycles decrease in the order Al > Co > Ni > Cu > Mn. Hydriding processes result in numerous cracks and amorphisation of the LaMgNi{sub 4} phase in the alloys. The p–c isotherms were determined by a Sieverts-type apparatus. Two plateaus were observed for the Ni, Co and Al substitution alloys, whereas only one plateau was found for Mn and Cu. This result was caused by the amorphisation of the LaMgNi{sub 4} phase during the hydriding cycles. Reversible absorption and desorption of hydrogen are difficult to achieve. Substitutions of Ni with Co, Mn, Cu and Al significantly influence the reduction of hysteresis between

  19. [The effect of bacteria reaction time on corrosion properties of Ni-Cr alloys pretreated with different proteins].

    Science.gov (United States)

    Qi, Han-quan; Zhang, Song-mei; Qian, Chao; Yuan-Li, Zheng

    2015-12-01

    To evaluate the corrosion properties of absorbed protein on the surface of NiCr alloys, and provide experimental base for corrosion resistance of dental casting alloys. NiCr alloy specimens were divided into 3 groups: one group was exposed to the artificial saliva(control group), and the other 2 groups were exposed to the artificial saliva with 1% bovine serum albumin(BSA), or 0.22% lysozyme(LSZ). Group of BSA and group of LSZ were the experimental group. Specimens in 3 groups were cultured in solution of Streptococcus mutans for 12 h, 24 h, 36 h and 48h, and investigated with electrochemical impedance spectroscopy measurement(EIS) and potentiodynamic polarization measurement(POT) to determine the corrosion resistance of the alloys. The data was analyzed with SPSS 17.0 software package. The results indicated that the corrosion resistance of both BSA group and LSZ group were higher than that of the control group (Pcorrosion resistance of BSA group and LSZ group had no significant difference (P>0.05), but was still higher than that of the control group. After 36 h culture time, the control group and the BSA group had no statistical difference in corrosion resistance (P>0.05), while the LSZ group had the poorest corrosion resistance. When the culture time extended to 48 h, the control group had a better corrosion resistance compared with the BAS group and the LSZ group(Pcorrosion properties than LSZ group. The potentiodynamic polarization curve and electrochemical impedance spectroscopy had similar results. The adhesion of BSA and LSZ on the surface of the NiCr alloys in the early time could effectively inhibit the corrosive effect of Streptococcus mutans. The LSZ had better effect than BSA. With the continuing role of bacteria and the consumption of the absorb protein, the corrosion resistance of NiCr alloys toward Streptococcus mutans becomes lower than the alloys without absorb protein, which demonstrated that the adhesion of protein would change the surface

  20. Study of the oxidation of Fe-Cr alloys at high temperatures

    International Nuclear Information System (INIS)

    Carneiro, J.F.; Sabioni, A.C.S.

    2010-01-01

    The high temperature oxidation behavior of Fe-1.5%Cr, Fe-5.0%Cr, Fe-10%Cr and Fe- 15%Cr model alloys were investigated from 700 to 850 deg C, in air atmosphere. The oxidation treatments were performed in a thermobalance with a sensitivity of 1μg. The oxide films grown by oxidation of the alloys were characterized by scanning electronic microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The oxide films are Fe-Cr spinels with variable composition depending on the alloy composition. For all conditions studied, the oxidation kinetics of these alloys follow a parabolic law. The comparison of the oxidation rates of the four alloys, at 700 deg C, shows that the parabolic oxidation constants decrease from 1.96x10 -9 g 2 .cm -4 .s -1 , for the alloy Fe-1.5% Cr, to 1.18 x 10-14g 2 .cm -4 .s -1 for the alloy Fe-15% Cr. Comparative analysis of the oxidation behavior of the Fe-10%Cr and Fe-15%Cr alloys, between 700 and 850 deg C, shows that the oxidation rates of these alloys are comparable to 800 deg C, above this temperature the Fe-10%Cr alloy shows lower resistance to oxidation. (author)

  1. Characterization of crystallization kinetics of a Ni- (Cr, Fe, Si, B, C, P) based amorphous brazing alloy by non-isothermal differential scanning calorimetry

    International Nuclear Information System (INIS)

    Raju, S.; Kumar, N.S. Arun; Jeyaganesh, B.; Mohandas, E.; Mudali, U. Kamachi

    2007-01-01

    The thermal stability and crystallization kinetics of a Ni- (Cr, Si, Fe, B, C, P) based amorphous brazing foil have been investigated by non-isothermal differential scanning calorimetry. The glass transition temperature T g , is found to be 720 ± 2 K. The amorphous alloy showed three distinct, yet considerably overlapping crystallization transformations with peak crystallization temperatures centered around 739, 778 and 853 ± 2 K, respectively. The solidus and liquidus temperatures are estimated to be 1250 and 1300 ± 2 K, respectively. The apparent activation energies for the three crystallization reactions have been determined using model free isoconversional methods. The typical values for the three crystallization reactions are: 334, 433 and 468 kJ mol -1 , respectively. The X-ray diffraction of the crystallized foil revealed the presence of following compounds Ni 3 B (Ni 4 B 3 ), CrB, B 2 Fe 15 Si 3 , CrSi 2 , and Ni 4.5 Si 2 B

  2. Martensite shear phase reversion-induced nanograined/ultrafine-grained Fe-16Cr-10Ni alloy: The effect of interstitial alloying elements and degree of austenite stability on phase reversion

    Energy Technology Data Exchange (ETDEWEB)

    Misra, R.D.K., E-mail: dmisra@louisiana.edu [Center for Structural and Functional Materials, University of Louisiana at Lafayette, Madison Hall Room 217, P.O. Box 44130, Lafayette, LA 70504-1430 (United States); Zhang, Z.; Venkatasurya, P.K.C. [Center for Structural and Functional Materials, University of Louisiana at Lafayette, Madison Hall Room 217, P.O. Box 44130, Lafayette, LA 70504-1430 (United States); Somani, M.C.; Karjalainen, L.P. [Department of Mechanical Engineering, University of Oulu, P.O. Box 4200, Oulu 90014 (Finland)

    2010-11-15

    Research highlights: {yields} Development of a novel process involving phase-reversion annealing process. {yields} Austensite stability strongly influences development of nanograined structure. {yields} Interstitial elements influence microstructural evolution during annealing. - Abstract: We describe here an electron microscopy study of microstructural evolution associated with martensitic shear phase reversion-induced nanograined/ultrafine-grained (NG/UFG) structure in an experimental Fe-16Cr-10Ni alloy with very low interstitial content. The primary objective is to understand and obtain fundamental insights on the influence of degree of austenite stability (Fe-16Cr-10Ni, 301LN, and 301 have different austenite stability index) and interstitial elements (carbon and nitrogen) in terms of phase reversion process, microstructural evolution during reversion annealing, and temperature-time annealing sequence. A relative comparison of Fe-16Cr-10Ni alloy with 301LN and 301 austenitic stainless steels indicated that phase reversion in Fe-16Cr-10Ni occurred by shear mechanism, which is similar to that observed for 301, but is different from the diffusional mechanism in 301LN steel. While the phase reversion in the experimental Fe-16Cr-10Ni alloy and 301 austenitic stainless steel occurred by shear mechanism, there were fundamental differences between these two alloys. The reversed strain-free austenite grains in Fe-16Cr-10Ni alloy were characterized by nearly same crystallographic orientation, where as in 301 steel there was evidence of break-up of martensite laths during reversion annealing resulting in several regions of misoriented austenite grains in 301 steel. Furthermore, a higher phase reversion annealing temperature range (800-900 deg. C) was required to obtain a fully NG/UFG structure of grain size 200-600 nm. The difference in the phase reversion and the temperature-time sequence in the three stages is explained in terms of Gibbs free energy change that

  3. Study of phase transformations in Fe-Mn-Cr Alloys

    International Nuclear Information System (INIS)

    Schule, W.; Panzarasa, A.; Lang, E.

    1988-01-01

    Nickel free alloys for fusion reactor applications are examined. Phase changes in fifteen, mainly austenitic iron-manganese-chromium-alloys of different compositions were investigated in the temperature range between -196 0 C and 1000 0 C after different thermo-mechanical treatments. A range of different physical measuring techniques was employed to investigate the structural changes occurring during heating and cooling and after cold-work: electrical resistivity techniques, differential thermal analysis, magnetic response, Vickers hardness and XRD measurement. The phase boundary between the α Fe-phase and the γ-phase of the iron manganese alloy is approximately maintained if chromium is added to the two component materials. Consequently all the alloy materials for contents of manganese smaller than about 30% Mn are not stable below 500 0 C. This concerns also the AMCR alloys. However the α Fe-phase is not formed during slow cooling from 1000 0 C to ambient temperature and is only obtained if nucleation sites are provided and after very long anneals. A cubic α Mn-type-phase is found for alloys with 18% Cr and 15% Mn, with 13% Cr and 25% Mn, with 10% Cr and 30% Mn, and with 10% Cr and 40% Mn. For these reasons the γ-phase field of the iron-chromium-manganese alloys is very small below 600 0 C and much narrower than reported in the literature. 95 figs. 22 refs

  4. Synthesis Of NiCrAlC alloys by mechanical alloying

    International Nuclear Information System (INIS)

    Silva, A.K.; Pereira, J.I.; Vurobi Junior, S.; Cintho, O.M.

    2010-01-01

    The purpose of the present paper is the synthesis of nickel alloys (NiCrAlC), which has been proposed like a economic alternative to the Stellite family Co alloys using mechanical alloying, followed by sintering heat treatment of milled material. The NiCrAlC alloys consist of a chromium carbides dispersion in a Ni 3 Al intermetallic matrix, that is easily synthesized by mechanical alloying. The use of mechanical alloying enables higher carbides sizes and distribution control in the matrix during sintering. We are also investigated the compaction of the processed materials by compressibility curves. The milling products were characterized by X-ray diffraction, and the end product was featured by conventional metallography and scanning electronic microscopy (SEM), that enabled the identification of desired phases, beyond microhardness test, which has been shown comparable to alloys manufactured by fusion after heat treating. (author)

  5. Effects of composition on the order-disorder transformation in Ni-Cr based alloys

    International Nuclear Information System (INIS)

    Marucco, A.

    1991-01-01

    The Ni-Cr based alloys undergo an ordering transformation, due to the formation of an ordered Ni 2 Cr phase, which causes a lattice contraction and it is responsisble for ''negative creep'' or excessive stresses in constrained components. A short-range ordered (SRO) structure develops in the matrix phase after solution treatment and at early stages of ageing, which can transform to a long-range ordered (LRO) structure, depending on the alloy composition and on time and temperature of ageing, upon prolonged annealing below the critical temperature. In stoichiometric Ni 2 Cr alloy LRO forms in a few hours, but in off-stoichiometric alloys the transformation kinetics are very sluggish and LRO takes several tens of thousands of hours to form, when it forms. The ordering behaviours of stoichiometric Ni 2 Cr and Ni 3 Cr were studied by means of isothermal treatments in the temperature range 450-600degC for different ageing times up to 30 000 h, followed by lattice parameter measurements by X-ray diffraction and electrical resistivity measurements. Similar studies performed on a series of ternary Ni-Cr-Fe alloys revealed the dependence of the degree of order on Cr concentration and a markedly delaying influence of Fe on the ordering kinetics. Finally, long-term microstructural stability of some commercial Ni-Cr based alloys, widely used for high temperature applications, have been studied: the ordering behaviour and associated microstructural changes are discussed in this paper

  6. Fe-15Ni-13Cr austenitic stainless steels for fission and fusion reactor applications. I. Effects of minor alloying elements on precipitate phases in melt products and implication in alloy fabrication

    International Nuclear Information System (INIS)

    Lee, E.H.; Mansur, L.K.

    2000-01-01

    In an effort to develop alloys for fission and fusion reactor applications, 28Fe-15Ni-13Cr base alloys were fabricated by adding various combinations of the minor alloying elements, Mo, Ti, C, Si, P, Nb, and B. The results showed that a significant fraction of undesirable residual oxygen was removed as oxides when Ti, C, and Si were added. Accordingly, the concentrations of the latter three essential alloying elements were reduced also. Among these elements, Ti was the strongest oxide former, but the largest oxygen removal (over 80%) was observed when carbon was added alone without Ti, since gaseous CO boiled off during melting. This paper recommends an alloy melting procedure to mitigate solute losses while reducing the undesirable residual oxygen. In this work, 14 different types of precipitate phases were identified. Compositions of precipitate phases and their crystallographic data are documented. Finally, stability of precipitate phases was examined in view of Gibbs free energy of formation

  7. Effect of Fe substitution at the Ni and Mn sites on the magnetic properties of Ni50Mn35In15 Heusler alloys

    International Nuclear Information System (INIS)

    Halder, Madhumita; Suresh, K.G.

    2015-01-01

    The structural and magnetic properties of Ni 48 Fe 2 Mn 35 In 15 and Ni 50 Mn 34 FeIn 15 Heusler alloys have been investigated. At room temperature, Ni 48 Fe 2 Mn 35 In 15 has L2 1 cubic structure, whereas Ni 50 Mn 34 FeIn 15 shows a two-phase structure due to the martensitic transition. In the case of Ni 48 Fe 2 Mn 35 In 15 , there is only one magnetic transition at 316 K with no martensitic transition. However, in Ni 50 Mn 34 FeIn 15 , we observe the martensitic transition at about 280 K. The Curie temperatures for austenite and martensite phases are 314 and 200 K, respectively. The maximum magnetic entropy changes are found to be 5.5 and 4.5 J kg −1 K −1 for Ni 48 Fe 2 Mn 35 In 15 and Ni 50 Mn 34 FeIn 15 , respectively, for 50 kOe. Ni 50 Mn 34 FeIn 15 exhibits exchange bias behavior, with a bias field of 130 Oe at 5 K. Both the alloys satisfy the empirical relation between the martensitic transition and the valence electron concentration (e/a) ratio. - Highlights: • Structural and magnetic properties of Ni 48 Fe 2 Mn 35 In 15 and Ni 50 Mn 34 FeIn 15 Heusler alloys have been investigated. • Ni 48 Fe 2 Mn 35 In 15 does not undergo a martensitic transition, whereas Ni 50 Mn 34 FeIn 15 shows martensitic transition. • Ni 50 Mn 34 FeIn 15 alloy exhibits exchange bias behavior. • Both alloys satisfy the empirical relation between martensitic transition and valence electron concentration (e/a)

  8. Inter-diffusion between Co3O4 coatings and the oxide scale on Fe-22Cr

    DEFF Research Database (Denmark)

    Hansson, Anette Nørgaard; Linderoth, Søren; Mogensen, Mogens Bjerg

    2007-01-01

    , electron microscopy, and energy dispersive X-ray spectroscopy. Cr2O3 developed in-between the Co3O4 coating and the alloy, whilst alloying elements of the substrate were incorporated in the coating, regardless of the deposition method. The coatings reduced the growth rate of the Cr2O3 layer as well...

  9. Inhibited Aluminization of an ODS FeCr Alloy

    International Nuclear Information System (INIS)

    Vande Put Ep Rouaix, Aurelie; Pint, Bruce A.

    2012-01-01

    Aluminide coatings are of interest for fusion energy applications both for compatibility with liquid Pb-Li and to form an alumina layer that acts as a tritium permeation barrier. Oxide dispersion strengthened (ODS) ferritic steels are a structural material candidate for commercial reactor concepts expected to operate above 600 C. Aluminizing was conducted in a laboratory scale chemical vapor deposition reactor using accepted conditions for coating Fe- and Ni-base alloys. However, the measured mass gains on the current batch of ODS Fe-14Cr were extremely low compared to other conventional and ODS alloys. After aluminizing at two different Al activities at 900 C and at 1100 C, characterization showed that the ODS Fe-14Cr specimens formed a dense, primarily AlN layer that prevented Al uptake. This alloy batch contained a higher (> 5000 ppma) N content than the other alloys coated and this is the most likely reason for the inhibited aluminization. Other factors such as the high O content, small (∼ 140 nm) grain size and Y-Ti oxide nano-clusters in ODS Fe-14Cr also could have contributed to the observed behavior. Examples of typical aluminide coatings formed on conventional and ODS Fe- and Ni-base alloys are shown for comparison.

  10. Anomalous decrease in X-ray diffraction intensities of Cu-Ni-Al-Co-Cr-Fe-Si alloy systems with multi-principal elements

    International Nuclear Information System (INIS)

    Yeh, J.-W.; Chang, S.-Y.; Hong, Y.-D.; Chen, S.-K.; Lin, S.-J.

    2007-01-01

    With an aim to understand the great reduction in the X-ray diffraction (XRD) intensities of high-entropy alloys, a series of Cu-Ni-Al-Co-Cr-Fe-Si alloys with systematic addition of principal elements from pure element to seven elements was investigated for quantitative analysis of XRD intensities. The variation of XRD peak intensities of the alloy system is similar to that caused by thermal effect, but the intensities further drop beyond the thermal effect with increasing number of incorporated principal elements. An intrinsic lattice distortion effect caused by the addition of multi-principal elements with different atomic sizes is expected for the anomalous decrease in XRD intensities. The mathematical factor of this distortion effect for the modification of XRD structure factor is formulated analogue to that of thermal effect

  11. Density of Liquid Ni-Cr Alloy

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The density of liquid Ni-Cr alloy was measured by a modified sessile drop method. The density of liquid Ni-Cr alloywas found to decrease with increasing temperature and Cr concentration in the alloy. The molar volume of liquidNi-Cr alloy increases with increasing the Cr concentration in the alloy. The molar volume of Ni-Cr alloy determinedin the present work shows a positive deviation from the linear molar volume.

  12. SEPARATION OF Fe (III, Cr(III, Cu(II, Ni(II, Co(II, AND Pb(II METAL IONS USING POLY(EUGENYL OXYACETIC ACID AS AN ION CARRIER BY A LIQUID MEMBRANE TRANSPORT METHOD

    Directory of Open Access Journals (Sweden)

    La Harimu

    2010-06-01

    Full Text Available Fe (III, Cr(III, Cu(II, Ni(II, Co(II, and Pb(II  metal ions had been separated using poly(eugenyl oxyacetic acid as an ion carrier by bulk liquid membrane transport method. The effect of pH, polyeugenyl oxyacetic acid ion carrier concentration, nitric acid concentration in the stripping solution, transport time, and metal concentration were optimized. The result showed that the optimum condition for transport of metal ions was at pH 4 for ion Fe(III and at pH 5 for Cr(III, Cu(II, Ni(II, Co(II, and Pb(II ions. The carrier volumes were optimum with concentration of 1 x 10-3 M at 7.5 mL for Cr(III, Cu (II,  Ni(II, Co(II ions and at 8.5 mL for Fe(III and Pb(II ions. The concentration of HNO3 in stripping phase was optimum at 2 M for Fe(III and Cu(II ions, 1 M for Cr(III, Ni(II and Co(II ions, and 0.5 M for Pb(II ion. The optimum transport times were 36 h for Fe(III and Co(II ions, and 48 h for Cr(III, Cu (II, Ni(II, and Pb(II ions. The concentration of metal ions accurately transported were 2.5 x 10-4 M for Fe(III and Cr(III ions, and 1 M for Cu (II, Ni(II, Co(II, and Pb(II ions. Compared to other metal ions the transport of Fe(III was the highest with selectivity order of Fe(III > Cr(III > Pb(II > Cu(II > Ni(II > Co(II. At optimum condition, Fe(III ion was transported through the membrane at 46.46%.   Keywords: poly(eugenyl oxyacetic acid, transport, liquid membrane, Fe (III, Cr(III, Cu(II, Ni(II, Co(II, and Pb(II ions

  13. Effect of temperature on the crevice corrosion resistance of Ni-Cr-Mo alloys as engineered barriers in nuclear waste repositories

    International Nuclear Information System (INIS)

    Hornus, Edgard C.; Rodríguez, Martin A.

    2011-01-01

    Ni-Cr-Mo alloys offer an outstanding corrosion resistance in a wide variety of highly corrosive environments. Alloys 625, C-22, C-22HS and Hybrid-BC1 are considered among candidates as engineered barriers of nuclear repositories. The objective of the present work was to assess the effect of temperature on the crevice corrosion resistance of these alloys. The crevice corrosion re-passivation potential (E CO ) of the tested alloys was determined by the Potentiodynamic-Galvanostatic-Potentiodynamic (PD-GS-PD) method. Alloy Hybrid-BC1 was the most resistant to chloride-induced crevice corrosion, followed by alloys C-22HS, C-22 and 625. E CO showed a linear decrease with temperature. There is a temperature above which E CO does not decrease anymore, reaching a minimum value. This E CO value is a strong parameter for assessing the localized corrosion susceptibility of a material in a long term timescale, since it is independent of temperature, chloride concentration and geometrical variables such as crevicing mechanism, crevice gap and type of crevice formers. (author) [es

  14. Microstructure, Texture, and Mechanical Behavior of As-cast Ni-Fe-W Matrix Alloy

    Science.gov (United States)

    Rao, A. Sambasiva; Manda, Premkumar; Mohan, M. K.; Nandy, T. K.; Singh, A. K.

    2018-04-01

    This article describes the tensile properties, flow, and work-hardening behavior of an experimental alloy 53Ni-29Fe-18W in as-cast condition. The microstructure of the alloy 53Ni-29Fe-18W displays single phase (fcc) in as-cast condition along with typical dendritic features. The bulk texture of the as-cast alloy reveals the triclinic sample symmetry and characteristic nature of coarse-grained materials. The alloy exhibits maximum strength ( σ YS and σ UTS) values along the transverse direction. The elongation values are maximum and minimum along the transverse and longitudinal directions, respectively. Tensile fracture surfaces of both the longitudinal and transverse samples display complete ductile fracture features. Two types of slip lines, namely, planar and intersecting, are observed in deformed specimens and the density of slip lines increases with increasing the amount of deformation. The alloy displays moderate in-plane anisotropy ( A IP) and reasonably low anisotropic index ( δ) values, respectively. The instantaneous or work-hardening rate curves portray three typical stages (I through III) along both the longitudinal and transverse directions. The alloy exhibits dislocation-controlled strain hardening during tensile testing, and slip is the predominant deformation mechanism.

  15. Study of the oxidation of Fe-Cr alloys at high temperatures; Estudo da oxidacao de ligas Fe-Cr a altas temperaturas

    Energy Technology Data Exchange (ETDEWEB)

    Carneiro, J.F.; Sabioni, A.C.S. [Universidade Federal de Ouro Preto (LDM/DF/UFOP), MG (Brazil). Dept. de Fisica. Lab. de Difusao em Materiais; Trindade, V.B. [Universidade Federal de Ouro Preto (DEMM/UFOP), MG (Brazil). Dept. de Engenharia Metalurgica e de Materiais; Ji, V. [Laboratoire d' Etude des Materiaux Hors-Equilibre (LEMHE), Orsay (France)

    2010-07-01

    The high temperature oxidation behavior of Fe-1.5%Cr, Fe-5.0%Cr, Fe-10%Cr and Fe- 15%Cr model alloys were investigated from 700 to 850 deg C, in air atmosphere. The oxidation treatments were performed in a thermobalance with a sensitivity of 1{mu}g. The oxide films grown by oxidation of the alloys were characterized by scanning electronic microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The oxide films are Fe-Cr spinels with variable composition depending on the alloy composition. For all conditions studied, the oxidation kinetics of these alloys follow a parabolic law. The comparison of the oxidation rates of the four alloys, at 700 deg C, shows that the parabolic oxidation constants decrease from 1.96x10{sup -9}g{sup 2}.cm{sup -4}.s{sup -1}, for the alloy Fe-1.5% Cr, to 1.18 x 10-14g{sup 2}.cm{sup -4}.s{sup -1} for the alloy Fe-15% Cr. Comparative analysis of the oxidation behavior of the Fe-10%Cr and Fe-15%Cr alloys, between 700 and 850 deg C, shows that the oxidation rates of these alloys are comparable to 800 deg C, above this temperature the Fe-10%Cr alloy shows lower resistance to oxidation. (author)

  16. Magnetic characterization of nanocrystalline Fe{sub 80−x}Cr{sub x}Co{sub 20} (15≤x≤35) alloys during milling and subsequent annealing

    Energy Technology Data Exchange (ETDEWEB)

    Rastabi, Reza Amini; Ghasemi, Ali, E-mail: ali13912001@yahoo.com; Tavoosi, Majid; Sodaee, Tahmineh

    2016-10-15

    Magnetic characterization of nanocrystalline Fe–Cr–Co alloys during milling and annealing process was the goal of this study. To formation of Fe{sub 80−x}Cr{sub x}Co{sub 20} (15≤x≤35) solid solution, different powder mixtures of Fe, Cr and Co elements were mechanically milled in a planetary ball mill. The annealing process was done in as-milled samples at different temperature in the range of 500–640 °C for 2 h. The produced samples were characterized using X-ray diffraction, scanning electron microscopy, differential scanning calorimetry and vibrating sample magnetometer. Performed mechanical alloying in different powder mixtures lead to the formation of Fe–Cr–Co α-phase solid solution with average crystallite sizes of about 10 nm. The produced nanocrystalline alloys exhibit magnetic properties with the coercivity and saturation of magnetization in the range of 110–200 Oe and 150–220 emu/g, respectively. The coercivity of produced alloys after annealing process decreased and reached to about 40–150 Oe. The highest value of coercivity in as-milled and annealed samples was achieved in alloys with higher Cr contents. - Highlights: • Hc and Ms of produced alloys obtained in the range of 110–200 Oe and 150–220 emu/g. • The highest value of Hc in milled and annealed samples was achieved in Fe{sub 45}Cr{sub 35}Co{sub 20}. • Hc of produced alloys after spinodal decomposition decreased to about 40–150 Oe. • The effect of crystalline defects and residual strain on magnetic fields pinning in milled samples is higher than spinodal decomposition in annealed samples. • The highest value of Hc in as-milled and annealed samples was achieved in Fe{sub 45}Cr{sub 35}Co{sub 20}. The coercivity of produced alloys after annealing process decreased and reach to about 40–150 Oe. • The produced nanocrystalline alloys exhibit magnetic properties with the coercivity and saturation of magnetization in the range of 110–200 Oe and 150–220 emu

  17. All-atom force field for molecular dynamics simulations on organotransition metal solids and liquids. Application to M(CO)(n) (M = Cr, Fe, Ni, Mo, Ru, or W) compounds.

    Science.gov (United States)

    Bernardes, Carlos E S; Canongia Lopes, José N; Minas da Piedade, Manuel E

    2013-10-31

    A previously developed OPLS-based all-atom force field for organometallic compounds was extended to a series of first-, second-, and third-row transition metals based on the study of M(CO)(n) (M = Cr, Fe, Ni, Mo, Ru, or W) complexes. For materials that are solid at ambient temperature and pressure (M = Cr, Mo, W) the validation of the force field was based on reported structural data and on the standard molar enthalpies of sublimation at 298.15 K, experimentally determined by Calvet-drop microcalorimetry using samples corresponding to a specific and well-characterized crystalline phase: Δ(sub)H(m)° = 72.6 ± 0.3 kJ·mol(–1) for Cr(CO)(6), 73.4 ± 0.3 kJ·mol(–1) for Mo(CO)(6), and 77.8 ± 0.3 kJ·mol(–1) for W(CO)(6). For liquids, where problems of polymorphism or phase mixtures are absent, critically analyzed literature data were used. The force field was able to reproduce the volumetric properties of the test set (density and unit cell volume) with an average deviations smaller than 2% and the experimentally determined enthalpies of sublimation and vaporization with an accuracy better than 2.3 kJ·mol(–1). The Lennard-Jones (12-6) potential function parameters used to calculate the repulsive and dispersion contributions of the metals within the framework of the force field were found to be transferable between chromium, iron, and nickel (first row) and between molybdenum and ruthenium (second row).

  18. Kinetic study of the annealing reactions in Cu-Ni-Fe alloys; Estudio cinetico de las reacciones de recocido en aleaciones de Cu-Ni-Fe

    Energy Technology Data Exchange (ETDEWEB)

    Donoso, E.

    2014-07-01

    The thermal aging of a Cu-45Ni-4Fe, Cu-34Ni-11Fe and Cu-33Ni-22Fe alloys tempered from 1173 K have been studied from Differential Scanning Calorimetry (DSC) and microhardness measurements. The analysis of DSC curves, from room temperature to 950 K, shows the presence of one exothermic reaction associated to the formation of FeNi{sub 3} phase nucleating from a modulate structure, and one endothermic peak attributed to dissolution of this phase. Kinetic parameters were obtained using the usual Avrami-Erofeev equation, modified Kissinger method and integrated kinetic functions. Microhardness measurements confirmed the formation and dissolution of the FeNi{sub 3} phase. (Author)

  19. The Phase Evolution and Property of FeCoCrNiAlTix High-Entropy Alloying Coatings on Q253 via Laser Cladding

    Directory of Open Access Journals (Sweden)

    Bin He

    2017-09-01

    Full Text Available High-entropy alloys (HEAs are emerging as a hot research frontier in the metallic materials field. The study on the effect of alloying elements on the structure and properties of HEAs may contribute to the progress of the research and accelerate the application in actual production. FeCoCrNiAlTix (x = 0, 0.25, 0.5, 0.75, and 1 in at.%, respectively HEA coatings with different Ti concentrations were produced on Q235 steel via laser cladding. The constituent phases, microstructure, hardness, and wear resistance of the coatings were investigated by XRD, SEM, microhardness tester and friction-wear tester, respectively. The results show that the structure of the coating is a eutectic microstructure of FCC and BCC1 at x = 0. The structure of coatings consists of both proeutectic FCC phase and the eutectic structure of BCC1 and BCC2. With the continuous addition of Ti, the amount of eutectic structure decreases. The average hardness of the FeCoCrNiAlTix HEA coatings at x = 0, 0.25, 0.5, 0.75, and 1 are 432.73 HV, 548.81 HV, 651.03 HV, 769.20 HV, and 966.29 HV, respectively. The hardness of coatings increases with the addition of Ti, where the maximum hardness is achieved for the HEA at x = 1. The wear resistance of the HEA coatings is enhanced with the addition of Ti, and the main worn mechanism is abrasive wear.

  20. Processing and characterization of AlCoFeNiXTi0,5 (X = Mn, V) high entropy alloys

    International Nuclear Information System (INIS)

    Triveno Rios, C.; Kiminami, C.S.

    2014-01-01

    The microstructure of high entropy alloys consists of solid solution phases with FC and BCC simple structures, contrary to classical metallurgy where they form complex structures of intermetallic compounds. Because of this they have several attractive properties for engineering applications. In this work the AlCoFeNiMnTi 0,5 and AlCoFeNiVTi 0,5 alloys were processed by melting arc. Since the main objective was the microstructural and mechanical characterization of ingots as-cast. The alloys were characterized by scanning electron microscopy, X-ray diffraction, microhardness and cold compression test. The results showed that the microstructure consists mainly of dendrites and interdendritic regions consisting of metastable crystalline phases. It was also observed that the AlCoFeNiVTi 0,5 alloy showed better mechanical properties than the AlCoFeNiMnTi 0,5 alloy. This may be associated with differences in the parameters of formation of simple solid solution phases between the two alloys. (author)

  1. Understanding self ion damage in FCC Ni-Cr-Fe based alloy using X-ray diffraction techniques

    Science.gov (United States)

    Halder Banerjee, R.; Sengupta, P.; Chatterjee, A.; Mishra, S. C.; Bhukta, A.; Satyam, P. V.; Samajdar, I.; Dey, G. K.

    2018-04-01

    Using X-ray diffraction line profile analysis (XRDLPA) approach the radiation response of FCC Ni-Cr-Fe based alloy 690 to 1.5 and 3 MeV Ni2+ ion damage was quantified in terms of its microstructural parameters. These microstructural parameters viz. average domain size, microstrain and dislocation density were found to vary anisotropically with fluence. The anisotropic behaviour is mainly attributable to presence of twins in pre-irradiated microstructure. After irradiation, surface roughness increases as a function of fluence attributable to change in surface and sub-surface morphology caused by displacement cascade, defects and sputtered atoms created by incident energetic ion. The radiation hardening in case of 1.5 MeV Ni2+ irradiated specimens too is a consequence of the increase in dislocation density formed by interaction of radiation induced defects with pre-existing dislocations. At highest fluence there is an initiation of saturation.

  2. Probing exotic magnetic phases and electrical transport in Cr-rich γ-NiFeCr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Pal, Pampa [S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098 (India); Majumdar, A.K., E-mail: akm@bose.res.in [S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098 (India); Ramakrishna Mission Vivekananda University, PO Belur Math, Howrah 711202 (India); Nigam, A.K. [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India)

    2015-05-01

    We have identified ferromagnetic, antiferromagnetic, and re-entrant spin-glass-like phases in Cr-rich γ-NiFeCr alloys and studied their critical magnetic behavior. Their electrical resistivity exhibits distinct minima between 10 and 24 K with ρ∞−√T due to electron–electron interaction effects. Electron–phonon and electron–magnon contributions to ρ are isolated. The magnetoresistance shows hysteresis effects, a signature of spin-glass-like phases and a sign reversal with change of magnetic states. We have also observed that the nature of magnetic states strongly depends on the concentration of Fe and Cr. In this system, even a small amount of Fe enhances ferromagnetism a lot while addition of a little bit of Cr suppresses ferromagnetism and takes the system to the antiferromagnetic regime. The correlation between the magnetic and the electrical properties are more meaningful here since both studies were done on the same set of samples which have rather high melting points. - Highlights: • Identified ferro, antiferro, and re-entrant spin-glass phases in Ni–Fe–Cr alloys. • Resistivity ρ~−√T shows minima from 10–24 K due to electron–electron interaction. • Electron–phonon and electron–magnon contributions to ρ are isolated. • Magneto-transport measurements strengthened the magnetic phases identified. • Correlation in magnetic/electrical properties more meaningful if same samples used.

  3. Microstructure Evolution and Chemical Analysis on Carbon Steels and Fe-Cr-Mo Alloys after FAC Simulation Tests

    International Nuclear Information System (INIS)

    Kim, Seunghyun; Kim, Taeho; Lee, Yun Ju; Kim, Ji Hyun

    2017-01-01

    Flow-accelerated corrosion (FAC) is an environment assisted degradation of structural materials, which usually occurs in pipelines of power plants. There have been many studies to investigate the fundamental mechanism and corresponding countermeasures against FAC, and recently the carbon steels have been replaced by ASTM A 335 P22, which contains approximately 2.2 wt.% of Cr and 1 wt.% of Mo. By enhancing passivity of P22 by Cr, it is reported that FAC rate has been greatly reduced. However, while corrosion behavior of Fe-based alloys is relatively well known, their behavior under high-temperature flowing water is not well investigated. In other words, effects of Cr and its corrosion and oxidation behavior is not clearly revealed. Furthermore, it is known that Mo enhances the pitting corrosion resistance of alloys however its mechanism is not clearly investigated. Recently, replacement of Mo in alloy contents has been widely studied because of the cost of Mo. Carbon steels undergo severe environmental-assisted degradation behavior so called FAC, and as its countermeasure the carbon steel has been replaced by P22 which contains Cr and Mo. It is generally known that Cr and Mo enhances passivity of Fe-based alloys however their corrosion and oxidation behavior has not been fully investigated especially in high-temperature flowing water environments. In this study, we employed HRTEM and synchrotron XAS techniques in order to investigate detailed microstructure evolution and chemical bonding of the commercialized carbon steel and the Fe-Cr-Mo alloys. From the analysis, it is found that while carbon steels exhibit porous oxide P22 exhibit oxide structures with thin Cr-rich oxide and spinel. Therefore, carbon steel undergoes severe FAC compared to P22 however effects of Cr and Mo and their behavior in high-temperature flowing water will be investigated.

  4. X-ray study of rapidly cooled ribbons of Al-Cr-Zr and Al-Ni-Y-Cr-Zr alloys

    International Nuclear Information System (INIS)

    Betsofen, S.Ya.; Osintsev, O.E.; Lutsenko, A.N.; Konkevich, V.Yu.

    2002-01-01

    One investigated into phase composition, lattice spacing and structure of rapidly cooled 25-200 μm gauge strips made of Al-4,1Cr-3,2Zr and Al-1,5Cr-1,5Zr-4Ni-3Y alloys, wt. %, produced by melt spinning to a water-cooled copper disk. In Al-4,1Cr-3,2Zr alloy one detected intermetallic phases: Al 3 Zr and two Al 86 Cr 14 composition icosahedral phases apart from aluminium solid solution with 4.040-4.043 A lattice spacing. In Al-1,5Cr-1,5Zr-4Ni-3Y alloy one identified two Al 86 Cr 14 icosahedral phases and two AlNiY and Al 3 Y yttrium-containing ones, lattice spacing of aluminium solid solution was equal to 4.052-4.053 A [ru

  5. The effects of Ni substitution on the magnetic properties of as-cast and annealed Fe-Co amorphous alloy wires

    International Nuclear Information System (INIS)

    Pinitsoontorn, S.; Badini Confalonieri, G.A..; Davies, H.A.; Gibbs, M.R.J.

    2005-01-01

    Amorphous alloy wires of composition (Co x Fe y Ni z ) 72.5 Si 12.5 B 15 , with Ni substituted for both Co and Fe, were prepared by the rotating water bath chill cast technique. The maximum Ni content that can be substituted in order to cast amorphous wire is reported. The effects of Ni addition on the hysteresis loop parameters and the major magnetic properties of the as-cast wire are reported

  6. Influence of Ti addition and sintering method on microstructure and mechanical behavior of a medium-entropy Al0.6CoNiFe alloy

    International Nuclear Information System (INIS)

    Fu, Zhiqiang; Chen, Weiping; Chen, Zhen; Wen, Haiming; Lavernia, Enrique J.

    2014-01-01

    The influence of Ti addition and sintering method on the microstructure and mechanical behavior of a medium-entropy alloy, Al 0.6 CoNiFe alloy, was studied in detail. Alloying behavior, microstructure, phase evolution and mechanical properties of Al 0.6 CoNiFe and Ti 0.4 Al 0.6 CoNiFe alloys were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), as well as by mechanical testing. During the mechanical alloying (MA) process, a supersaturated solid solution consisting of both BCC and FCC phases was formed in the Al 0.6 CoNiFe alloy. With Ti addition, the Ti 0.4 Al 0.6 CoNiFe alloy exhibited a supersaturated solid solution with a single FCC phase. Following hot pressing (HP), the HP sintered (HP’ed) Al 0.6 CoNiFe bulk alloy was composed of a major BCC phase and a minor FCC phase. The HP’ed Ti 0.4 Al 0.6 CoNiFe alloy exhibited a FCC phase, two BCC phases and a trace unidentified phase. Nanoscale twins were present in the HP’ed Ti 0.4 Al 0.6 CoNiFe alloy, where deformation twins were observed in the FCC phase. Our results suggest that the addition of Ti facilitated the formation of nanoscale twins. The compressive strength and Vickers hardness of HP’ed Ti 0.4 Al 0.6 CoNiFe alloy were slightly lower than the corresponding values of the HP’ed Al 0.6 CoNiFe alloy. In contrast with HP’ed Al 0.6 CoNiFe alloy, spark plasma sintered (SPS’ed) Al 0.6 CoNiFe alloy exhibited a major FCC phase and a minor BCC phase. Moreover, the SPS’ed Al 0.6 CoNiFe alloy exhibited a lower compressive strength and Vickers hardness, but singificantly higher plasticity, as compared to those of the HP’ed counterpart material

  7. Damping behavior of AlxCoCrFeNi high-entropy alloys by a dynamic mechanical analyzer

    International Nuclear Information System (INIS)

    Ma, S.G.; Liaw, P.K.; Gao, M.C.; Qiao, J.W.; Wang, Z.H.; Zhang, Y.

    2014-01-01

    Highlights: • The Al content is related with structural relaxation and damping capability. • Dynamic modulus is insensitive to the frequency especially for storage modulus. • Several internal-friction peaks are observed in the Al-free or Al-lean alloys. • The damping behavior is proposed to be strongly relied on the level of ordering. - Abstract: For the first time, the damping behavior of high-entropy alloys was studied using the dynamic-mechanical analyzer, over a continuous heating temperature from room temperature to 773 K, at a given frequency range from 1 to 16 Hz in model alloys Al x CoCrFeNi (x = 0, 0.25, 0.5, 0.75, and 1). The experimental results reveal that the Al-rich alloys have a much smaller elastic storage-modulus amplitude over the temperature and thus a larger resistance to structural relaxation, while the Al-free and Al-lean alloys exhibit a much higher loss tangent and thus a much higher damping capability. Overall the elastic storage modulus decreases while the loss tangent increases with increasing the temperature, but little dependence was observed for the frequency. Several visible internal-friction peaks were presented in the face-centered cubic alloys, whose positions and heights are independent of the frequency. The damping capability of these alloys can be comparable to or even overwhelm the conventional Fe–Al alloys. The damping behavior above was proposed to be agreeable with the level of ordering (η) of alloys characterized by two proposed parameters (the relative-entropy effect, Ω, and the atomic-size difference, δ)

  8. Microstructure and mechanical properties of NiCoCrAlYTa alloy processed by press and sintering route

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, J.C., E-mail: jpereira@uc.edu.ve [Instituto de Tecnología de Materiales, Universidad Politécnica de Valencia, Camino de vera s/n, Valencia, España (Spain); Centro de Investigaciones en Mecánica, Facultad de Ingeniería, Universidad de Carabobo (Venezuela, Bolivarian Republic of); Zambrano, J.C. [Centro de Investigaciones en Mecánica, Facultad de Ingeniería, Universidad de Carabobo (Venezuela, Bolivarian Republic of); Afonso, C.R.M. [Departamento de Engenharia de Materiais, Universidade Federal de São Carlos (UFSCar), São Carlos, SP (Brazil); Amigó, V. [Instituto de Tecnología de Materiales, Universidad Politécnica de Valencia, Camino de vera s/n, Valencia, España (Spain)

    2015-03-15

    Nickel-based superalloys such as NiCoCrAlY are widely used in high-temperature applications, such as gas turbine components in the energy and aerospace industries, due to their strength, high elastic modulus, and high-temperature oxidation resistance. However, the processing of these alloys is complex and costly, and the alloys are currently used as a bond coat in thermal barrier coatings. In this work, the effect of cold press and sintering processing parameters on the microstructure and mechanical properties of NiCoCrAlY alloy were studied using the powder metallurgy route as a new way to obtain NiCoCrAlYTa samples from a gas atomized prealloyed powder feedstock. High mechanical strength and adequate densification up to 98% were achieved. The most suitable compaction pressure and sintering temperature were determined for NiCoCrAlYTa alloy through microstructure characterization. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and energy dispersive spectroscopy microanalysis (EDS) were performed to confirm the expected γ-Ni matrix and β-NiAl phase distribution. Additionally, the results demonstrated the unexpected presence of carbides and Ni–Y-rich zones in the microstructure due to the powder metallurgy processing parameters used. Thus, microhardness, nanoindentation and uniaxial compression tests were conducted to correlate the microstructure of the alloy samples with their mechanical properties under the different studied conditions. The results show that the compaction pressure did not significantly affect the mechanical properties of the alloy samples. In this work, the compaction pressures of 400, 700 and 1000 MPa were used. The sintering temperature of 1200 °C for NiCoCrAlYTa alloy was preferred; above this temperature, the improvement in mechanical properties is not significant due to grain coarsening, whereas a lower temperature produces a decrease in mechanical properties due to high porosity and

  9. Effects of the sp element additions on the microstructure and mechanical properties of NiCoFeCr based high entropy alloys

    International Nuclear Information System (INIS)

    Vida, Adam; Varga, Lajos K.; Chinh, Nguyen Quang; Molnar, David; Huang, Shuo; Vitos, Levente

    2016-01-01

    The effects of the sp (Al, Ga, Ge, Sn) element additions on the microstructure and mechanical properties of equimolar NiCoFeCr High Entropy Alloys (HEAs) are investigated. The results of X-ray diffraction measurements combined with scanning electron microscopy SEM investigations, as well as the results of nanoindentation test revealed that while the structure of the basic alloy is full FCC, the addition of sp elements has changed it to a multiphase containing both FCC and BCC components, but in different scales. Accordingly, the addition of sp elements strongly increases the strength of the basic state, especially in the case of alloys where the BCC phase is dominant in the microstructure. The physical properties as the Young’s- and shear moduli of the investigated HEAs were also determined using ultrasound methods. The correlation between these two moduli suggests a general relationship for metallic alloys.

  10. Ab initio and Atomic kinetic Monte Carlo modelling of segregation in concentrated FeCrNi alloys

    Science.gov (United States)

    Piochaud, J. B.; Becquart, C. S.; Domain, C.

    2014-06-01

    Internal structure of pressurised water reactors are made of austenitic materials. Under irradiation, the microstructure of these concentrated alloys evolves and solute segregation on grain boundaries or irradiation defects such as dislocation loops are observed to take place. In order to model and predict the microstructure evolution, a multiscale modelling approach needs to be developed, which starts at the atomic scale. Atomic Kinetic Monte Carlo (AKMC) modelling is the method we chose to provide an insight on defect mediated diffusion under irradiation. In that approach, we model the concentrated commercial steel as a FeCrNi alloy (γ-Fe70Cr20Ni10). As no reliable empirical potential exists at the moment to reproduce faithfully the phase diagram and the interactions of the elements and point defects, we have adjusted a pair interaction model on large amount of DFT calculations. The point defect properties in the Fe70Cr20Ni10, and more precisely, how their formation energy depends on the local environment will be presented and some AKMC results on thermal non equilibrium segregation and radiation induce segregation will be presented. The effect of Si on the segregation will also be discussed.

  11. Structural high-temperature and (βNiAl+γ)-alloys based on Ni-Al-Co-Me systems with an improved low-temperature ductility

    International Nuclear Information System (INIS)

    Povarova, K.B.; Kazanskaya, N.K.; Drozdov, A.A.; Lomberg, B.S.; Gerasimov, V.V.

    2001-01-01

    The βNiAl-based alloys (B2) have lower density higher resistance to oxidation, and higher melting temperature relative to those of Ni-superalloys or γ'Ni 3 Al-base alloys. An improved low-temperature ductility of advanced Ni-AI-Co-M β+γ alloys(El=9-16 % at 293-1173 K is achieved due to the formation γ-Ni solid solution intergranular interlayers of eutectic origin. Secondary γ and/or γ' precipitates form in the grains of the supersaturated β-solid solution upon heat treatment at 1473-1573 K and 1073-1173 K. The limiting contents of alloying elements (Ti, Hf, Nb, Ta, Cr, Mo) for the (β+γ) alloys Ni - (19-29) % AI - (22-35) % Co, are determined which allowed to avoid the formation of primary γ'-phase (decrease solidus temperature ≤1643 K) and hard phases of the types σ, η and δ (decrease ductility). Alloying affects the morphology of the secondary γ and γ' precipitates: globular equiaxed precipitates are formed in the alloys containing Cr, Mo, and needle precipitates are formed in alloys alloys containing γ'-forming elements Nb, Ta and, especially, Ti and Hf. After directional solidification, (β+γ')-alloys have directed columnar special structure with a low extension of transverse grain boundaries. This microstructure allows one to increase UTS, by a factor 1,5-2 and long-term strength (time to rupture increase by a factor of 5-10 at 1173 K). (author)

  12. Development of the dentistry alloy Ni-Cr-Nb; Desenvolvimento de ligas odontologicas Ni-Cr-Nb

    Energy Technology Data Exchange (ETDEWEB)

    Souza, M.A.; Ramos, A.S.; Hashimoto, T.M., E-mail: mari_sou@hotmail.co [UNESP/FEG, Guaratingueta, SP (Brazil). Fac. de Engenharia. Dept. de Materiais e Tecnologia

    2010-07-01

    This work reports on the structural characterization of Ni-Cr-Mo and Ni-Cr-Nb alloys produced by arc melting. Samples were characterized by means of optical microscopy, X-ray diffraction, scanning electron microscopy, and EDS analysis. Results indicated that the arc melting process was efficient to produce homogeneous structures in Ni-Cr-Mo and Ni-Cr-Nb alloys. The nickel dissolved large amounts of Cr, Mo and Nb, which was detected by EDS analysis and X-ray diffraction. The alloy containing molybdenum indicated the presence of structure based on Ni{sub SS}, while that the alloys containing niobium presented primary grains of Ni{sub SS} and precipitates formed by the simultaneous transformation of the Ni and Ni{sub 3}Nb phases. (author)

  13. Grain refinement of Al-Si9.8-Cu3.4 alloy by novel Al-3.5FeNb-1.5C master alloy and its effect on mechanical properties

    Science.gov (United States)

    Apparao, K. Ch; Birru, Anil Kumar

    2018-01-01

    A novel Al-3.5FeNb-1.5C master alloy with uniform microstructure was prepared using a melt reaction process for this study. In the master alloy, basic intermetallic particles such as NbAl3, NbC act as heterogeneous nucleation substrates during the solidification of aluminium. The grain refining performance of the novel master alloy on Al-Si9.8-Cu3.4 alloy has also been investigated. It is observed that the addition of 0.1 wt.% of Al-3.5FeNb-1.5C master alloy can induce very effective grain refinement of the Al-Si9.8-Cu3.4 alloy. The average grain size of α-Al is reduced to 22.90 μm from about 61.22 μm and most importantly, the inoculation of Al-Si9.8-Cu3.4 alloy with FeNb-C is not characterised by any visible poisoning effect, which is the drawback of using commercial Al-Ti-B master alloys on aluminium cast alloys. Therefore, the mechanical properties of the Al-Si9.8-Cu3.4 alloy have been improved obviously by the addition of the 0.1 wt.% of Al-3.5FeNb-1.5C master alloy, including the yield strength and elongation.

  14. Hyperfine Interactions and Some Magnetic Properties of Nanocrystalline Co40Fe50Ni10 and Co50Fe45Ni5 Alloys Prepared by Mechanical Synthesis and Subsequently Heat Treated

    International Nuclear Information System (INIS)

    Pikula, T.; Oleszak, D.; Pekala, M.

    2011-01-01

    Co 40 Fe 50 Ni 10 and Co 50 Fe 45 Ni 5 ternary alloys were prepared by mechanical alloying method. To check the stability of their structure thermal treatment was applied subsequently. As X-ray diffraction studies proved the final products of milling were the solid solutions with bcc lattice and the average grain sizes ranged of tens of nanometers. After heating of the Co 50 Fe 45 Ni 5 alloy up to 993 K the mixture of two solid solutions with bcc and fcc lattices was formed. In other cases thermal treatment did not change the type of the crystalline lattice. Moessbauer spectroscopy revealed hyperfine magnetic field distributions which reflected the different possible atomic surroundings of 57 Fe isotopes. Results of the macroscopic magnetic measurements proved that both investigated alloys had relatively good soft magnetic properties. (authors)

  15. Resistivity and Passivity Characterization of Ni-Base Glassy Alloys in NaOH Media

    Directory of Open Access Journals (Sweden)

    Khadijah M. Emran

    2018-01-01

    Full Text Available Resistivity and passivation behavior of two Ni-base bulk metallic glasses, with the nominal composition of Ni70Cr21Si0.5B0.5P8C ≤ 0.1Co ≤ 1Fe ≤ 1 (VZ1 and Ni72.65Cr7.3-Si6.7B2.15C ≤ 0.06Fe8.2Mo3 (VZ2, in various concentrations of NaOH solutions were studied. The investigations involved cyclic polarization (CP, electrochemical impedance spectroscopy (EIS, and electrochemical frequency modulation (EFM methods. Cyclic polarization measurements showed spontaneous passivation for both Ni-base glassy alloys at all alkaline concentrations, due to the presence of chromium as an alloying element that formed an oxide film on the alloy surface. The EIS analysis showed that the passive layers grown on the two Ni-base glassy alloy surfaces are formed by a double oxide layer structure. Scanning electron microscope (SEM examinations of the electrode surface showed Cr, Ni, Fe, and O rich corrosion products that reduced the extent of corrosion damage. Atomic force microscopy (AFM imaging technique was used to evaluate the topographic and morphologic features of surface layers formed on the surface of the alloys.

  16. Crystallization kinetics and magnetic properties of FeSiCr amorphous alloy powder cores

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Hu-ping [School of Logistics Engineering, Wuhan University of Technology, Wuhan 430063 (China); Wang, Ru-wu, E-mail: ruwuwang@hotmail.com [National Engineering Research Center For Silicon Steel, Wuhan 430080 (China); College of Materials Science and Metallurgical Engineering, Wuhan University of Science and Technology, Wuhan 430081 (China); Wei, Ding [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074 (China); Zeng, Chun [National Engineering Research Center For Silicon Steel, Wuhan 430080 (China)

    2015-07-01

    The crystallization kinetics of FeSiCr amorphous alloy, characterized by the crystallization activation energy, Avrami exponent and frequency factor, was studied by non-isothermal differential scanning calorimetric (DSC) measurements. The crystallization activation energy and frequency factor of amorphous alloy calculated from Augis–Bennett model were 476 kJ/mol and 5.5×10{sup 18} s{sup −1}, respectively. The Avrami exponent n was calculated to be 2.2 from the Johnson–Mehl–Avrami (JMA) equation. Toroid-shaped Fe-base amorphous powder cores were prepared from the commercial FeSiCr amorphous alloy powder and subsequent cold pressing using binder and insulation. The characteristics of FeSiCr amorphous alloy powder and the effects of compaction pressure and insulation content on the magnetic properties, i.e., effective permeability μ{sub e}, quality factor Q and DC-bias properties of FeSiCr amorphous alloy powder cores, were investigated. The FeSiCr amorphous alloy powder cores exhibit a high value of quality factor and a stable permeability in the frequency range up to 1 MHz, showing superior DC-bias properties with a “percent permeability” of more than 82% at H=100 Oe. - Highlights: • The crystallization kinetics of FeSiCr amorphous alloy was investigated. • The FeSiCr powder cores exhibit a high value of Q and a stable permeability. • The FeSiCr powder cores exhibit superior DC-bias properties.

  17. Trace element control in binary Ni-25Cr and ternary Ni-30Co-30Cr master alloy castings

    Energy Technology Data Exchange (ETDEWEB)

    Detrois, Martin [National Energy Technology Lab. (NETL), Albany, OR (United States); Oak Ridge Inst. for Science and Education (ORISE), Oak Ridge, TN (United States); Jablonski, Paul D. [National Energy Technology Lab. (NETL), Albany, OR (United States);

    2017-10-23

    Electro-slag remelting (ESR) is used for control of unwanted elements in commercial alloys. This study focuses on master alloys of Ni-25Cr and Ni-30Co-30Cr, processed through a combination of vacuum induction melting (VIM) and electro-slag remelting (ESR). Minor additions were made to control tramp element levels and modify the melting characteristics. Nitrogen and sulfur levels below 10 ppm and oxygen levels below 100 ppm were obtained in the final products. The role of the alloy additions in lowering the tramp element content, the resulting residual inclusions and the melting characteristics were determined computationally and confirmed experimentally. Additions of titanium were beneficial to the control of oxygen levels during VIM and nitrogen levels during ESR. Aluminum additions helped to control oxygen levels during remelting, however, aluminum pickup occurred when excess titanium was present during ESR. The usefulness of these master alloys for use as experimental remelt stock will also be discussed.

  18. Reduction under hydrogen of ferrite MFe{sub 2}O{sub 4} (M: Fe, Co, Ni) nanoparticles obtained by hydrolysis in polyol medium: A novel route to elaborate CoFe{sub 2}, Fe and Ni{sub 3}Fe nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ballot, N.; Schoenstein, F.; Mercone, S.; Chauveau, T.; Brinza, O. [Laboratoire des Sciences des Procedes et des Materiaux, CNRS, LSPM - UPR 3407, Universite Paris 13, PRES Sorbonne-Paris-Cite, 99 Avenue J.-B. Clement, 93430 Villetaneuse (France); Jouini, N., E-mail: jouini@univ-paris13.fr [Laboratoire des Sciences des Procedes et des Materiaux, CNRS, LSPM - UPR 3407, Universite Paris 13, PRES Sorbonne-Paris-Cite, 99 Avenue J.-B. Clement, 93430 Villetaneuse (France)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer Spinels nano-particles MFe{sub 2}O{sub 4} (M: Co, Fe or Ni) are obtained by hydrolysis in polyol medium. Black-Right-Pointing-Pointer Gentle reduction under hydrogen flow of spinel nano-particles yields metal and alloy nanoparticles. Black-Right-Pointing-Pointer TEM and X-ray analysis show that CoFe{sub 2}, Fe and Ni{sub 3}Fe nano-particles are monocrystalline particles with size less than 160 nm. Black-Right-Pointing-Pointer Iron with size of 150 nm presents ferromagnetic behavior. Black-Right-Pointing-Pointer CoFe{sub 2} alloy with size of 55 nm could be considered as a superparamagnetic material. - Abstract: A novel method to process metal and various alloy particles of nanometric size is described. The first step consists in the elaboration of MFe{sub 2}O{sub 4} (M: Fe, Ni or Co) spinel nanoparticles in polyol medium via hydrolysis and the second one in gently reducing these latter under hydrogen at 300 Degree-Sign C. X-ray diffraction analysis shows that pure Fe and CoFe{sub 2} alloy are well obtained by reducing Fe{sub 3}O{sub 4} and CoFe{sub 2}O{sub 4}, respectively. This is not the case when we try to reduce NiFe{sub 2}O{sub 4}. A mixture of Fe and Ni{sub 3}Fe is observed. TEM analysis reveals that the size of metal particles stays within the range of a few tenths of nm up to 150 nm, while the precursors (MFe{sub 2}O{sub 4}) never exceed 5 nm. Our results show that the formation of metal particles occurs via two main steps: (i) reduction of the spinel oxide nanoparticles into metal ones and (ii) aggregation of the latter, leading to larger metal nanoparticles. Magnetic measurements indicate that the as-obtained metallic materials have good magnetic properties mainly affected by the sizes of the nanoparticles and the purity of the reduced phases.

  19. High-Strength Ultra-Fine-Grained Hypereutectic Al-Si-Fe-X (X = Cr, Mn) Alloys Prepared by Short-Term Mechanical Alloying and Spark Plasma Sintering

    Science.gov (United States)

    Průša, Filip; Bláhová, Markéta; Vojtěch, Dalibor; Kučera, Vojtěch; Bernatiková, Adriana; Kubatík, Tomáš František; Michalcová, Alena

    2016-01-01

    In this work, Al-20Si-10Fe-6Cr and Al-20Si-10Fe-6Mn (wt %) alloys were prepared by a combination of short-term mechanical alloying and spark plasma sintering. The microstructure was composed of homogeneously dispersed intermetallic particles forming composite-like structures. X-ray diffraction analysis and TEM + EDS analysis determined that the α-Al along with α-Al15(Fe,Cr)3Si2 or α-Al15(Fe,Mn)3Si2 phases were present, with dimensions below 130 nm. The highest hardness of 380 ± 7 HV5 was observed for the Al-20Si-10Fe-6Mn alloy, exceeding the hardness of the reference as-cast Al-12Si-1Cu-1 Mg-1Ni alloy (121 ± 2 HV5) by nearly a factor of three. Both of the prepared alloys showed exceptional thermal stability with the hardness remaining almost the same even after 100 h of annealing at 400 °C. Additionally, the compressive strengths of the Al-20Si-10Fe-6Cr and Al-20Si-10Fe-6Mn alloys reached 869 MPa and 887 MPa, respectively, and had virtually the same values of 870 MPa and 865 MPa, respectively, even after 100 h of annealing. More importantly, the alloys showed an increase in ductility at 400 °C, reaching several tens of percent. Thus, both of the investigated alloys showed better mechanical properties, including superior hardness, compressive strength and thermal stability, as compared to the reference Al-10Si-1Cu-1Mg-1Ni alloy, which softened remarkably, reducing its hardness by almost 50% to 63 ± 8 HV5. PMID:28774094

  20. Effects of alloying elements (Mn, Co, Al, W, Sn, B, C and S) on biodegradability and in vitro biocompatibility of pure iron.

    Science.gov (United States)

    Liu, B; Zheng, Y F

    2011-03-01

    Pure iron was determined to be a valid candidate material for biodegradable metallic stents in recent animal tests; however, a much faster degradation rate in physiological environments was desired. C, Mn, Si, P, S, B, Cr, Ni, Pb, Mo, Al, Ti, Cu, Co, V and W are common alloying elements in industrial steels, with Cr, Ni, Mo, Cu, Ti, V and Si being acknowledged as beneficial in enhancing the corrosion resistance of iron. The purpose of the present work (using Fe-X binary alloy models) is to explore the effect of the remaining alloying elements (Mn, Co, Al, W, B, C and S) and one detrimental impurity element Sn on the biodegradability and biocompatibility of pure iron by scanning electron microscopy, X-ray diffraction, metallographic observation, tensile testing, microhardness testing, electrochemical testing, static (for 6 months) and dynamic (for 1 month with various dissolved oxygen concentrations) immersion testing, cytotoxicity testing, hemolysis and platelet adhesion testing. The results showed that the addition of all alloying elements except for Sn improved the mechanical properties of iron after rolling. Localized corrosion of Fe-X binary alloys was observed in both static and dynamic immersion tests. Except for the Fe-Mn alloy, which showed a significant decrease in corrosion rate, the other Fe-X binary alloy corrosion rates were close to that of pure iron. It was found that compared with pure iron all Fe-X binary alloys decreased the viability of the L929 cell line, none of experimental alloying elements significantly reduced the viability of vascular smooth muscle cells and all the elements except for Mn increased the viability of the ECV304 cell line. The hemolysis percentage of all Fe-X binary alloy models were less than 5%, and no sign of thrombogenicity was observed. In vitro corrosion and the biological behavior of these Fe-X binary alloys are discussed and a corresponding mechanism of corrosion of Fe-X binary alloys in Hank's solution proposed. As a

  1. Study of the impact of treatment modes on hardness, deformability and microstructure of VT6 (Ti-6Al-4V and VV751P (Ni-15Co-10Cr alloy samples after selective laser sintering

    Directory of Open Access Journals (Sweden)

    Galkina Natalia V.

    2017-01-01

    Full Text Available Selective laser sintering is an advanced method for obtaining sophisticated products and assembly permanent joints. This is particularly relevant for heat resistant alloys employed in aviation equipment. Heat treatment modes traditionally applied to the products are chosen in accordance with conditions of further product operation. In this paper there are given the results of experimental study of hardness, deformability and microstructure of samples after selective laser sintering of Ni-15Co-10Cr and Ti–6Al–4V alloy powders. It has been determined that Ni-15Co-10Cr alloy ageing increases the hardness and deformability of samples; these characteristics decrease if the ageing lasts for 9-19 hours. Annealing of Ti–6Al–4V alloy samples results in preserving original hardness. After complete annealing, the hardness of samples decreases from 32 … 33HRC to 24 … 26HRC. Microstructural studies showed that there are cracks between layers in the surface of Ti–6Al–4V alloy samples after sintering and not complete annealing. After full annealing, cracks' width and length decreased. Cracks in Ni-15Co-10Cr alloy samples' microstructure were not detected.

  2. Synthesis Of NiCrAlC alloys by mechanical alloying; Sintese de ligas NiCrAlC por moagem de alta energia

    Energy Technology Data Exchange (ETDEWEB)

    Silva, A.K.; Pereira, J.I.; Vurobi Junior, S.; Cintho, O.M., E-mail: alissonkws@gmail.co [Universidade Estadual de Ponta Grossa (UEPG), PR (Brazil)

    2010-07-01

    The purpose of the present paper is the synthesis of nickel alloys (NiCrAlC), which has been proposed like a economic alternative to the Stellite family Co alloys using mechanical alloying, followed by sintering heat treatment of milled material. The NiCrAlC alloys consist of a chromium carbides dispersion in a Ni{sub 3}Al intermetallic matrix, that is easily synthesized by mechanical alloying. The use of mechanical alloying enables higher carbides sizes and distribution control in the matrix during sintering. We are also investigated the compaction of the processed materials by compressibility curves. The milling products were characterized by X-ray diffraction, and the end product was featured by conventional metallography and scanning electronic microscopy (SEM), that enabled the identification of desired phases, beyond microhardness test, which has been shown comparable to alloys manufactured by fusion after heat treating. (author)

  3. Microstructure and Wear Behavior of FeCoCrNiMo0.2 High Entropy Coatings Prepared by Air Plasma Spray and the High Velocity Oxy-Fuel Spray Processes

    Directory of Open Access Journals (Sweden)

    Tianchen Li

    2017-09-01

    Full Text Available In the present research, the spherical FeCoCrNiMo0.2 high entropy alloy (HEA powders with a single FCC solid solution structure were prepared by gas atomization. Subsequently, the FeCoCrNiMo0.2 coatings with a different content of oxide inclusions were prepared by air plasma spraying (APS and high-velocity oxy-fuel spraying (HVOF, respectively. The microstructure, phase composition, mechanical properties, and tribological behaviors of these HEA coatings were investigated. The results showed that both HEA coatings showed a typical lamellar structure with low porosity. Besides the primary FCC phase, a mixture of Fe2O3, Fe3O4, and AB2O4 (A = Fe, Co, Ni, and B = Fe, Cr was identified as the oxide inclusions. The oxide content of the APS coating and HVOF coating was calculated to be 47.0% and 12.7%, respectively. The wear resistance of the APS coating was approximately one order of magnitude higher than that of the HVOF coating. It was mainly attributed to the self-lubricated effect caused by the oxide films. The mass loss of the APS coating was mainly ascribed to the breakaway of the oxide film, while the main wear mechanism of the HVOF coating was the abrasive wear.

  4. Effects of conducting oxide barrier layers on the stability of Crofer® 22 APU/Ca3Co4O9 interfaces

    DEFF Research Database (Denmark)

    Holgate, Tim C.; Han, Li; Wu, NingYu

    2014-01-01

    Practical implementation of oxide thermoelectrics on an industrial or commercial scale for waste heat energy conversion requires the development of chemically stable interfaces between metal interconnects and oxide thermoelements that exhibit low electrical contact resistances. A commercially...... available high-chrome iron alloy (i.e., Crofer® 22 APU) serving as the interconnect metal was spray coated with LaNi0.6Fe0.4O3 (LNFO) or (Mn,Co)3O4 spinel and then interfaced with a p-type thermoelectric material—calcium cobaltate (Ca3Co4O9)—using spark plasma sintering. The interfaces have been...

  5. Effect of alloying elements on martensitic transformation in the binary NiAl(β) phase alloys

    International Nuclear Information System (INIS)

    Kainuma, R.; Ohtani, H.; Ishida, K.

    1996-01-01

    The characteristics of the B2(β) to L1 0 (β') martensitic transformation in NiAl base alloys containing a small amount of third elements have been investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD), and transmission electron microscopy (TEM). It is found that in addition to the normal L1 0 (3R) martensite, the 7R martensite is also present in the ternary alloys containing Ti, Mo, Ag, Ta, or Zr. While the addition of third elements X (X: Ti, V, Cr, Mn, Fe, Zr, Nb, Mo, Ta, W, and Si) to the binary Ni 64 Al 36 alloy stabilizes the parent β phase, thereby lowering the M s temperature, addition of third elements such as Co, Cu, or Ag destabilizes the β phase, increasing the M s temperature. The occurrence of the 7R martensite structure is attributed to solid solution hardening arising from the difference in atomic size between Ni and Al and the third elements added. The variation in M s temperature with third element additions is primarily ascribed to the difference in lattice stabilities of the bcc and fcc phases of the alloying elements

  6. Development of a tungsten heavy alloy, W-Ni-Mn, used as kinetic energy penetrator

    International Nuclear Information System (INIS)

    Zahraee, S. M.; Salehi, M. T.; Arabi, H.; Tamizifar, M.

    2007-01-01

    The objective of this research was to develop a tungsten heavy alloy having a microstructure and properties good enough to penetrate hard rolled steels as deep as possible. In addition this alloy should not have environmental problems as depleted uranium materials, For this purpose a wide spread literature survey was performed and on the base of information obtained in this survey, three compositions of tungsten heavy alloy were chosen for investigation in this research. The alloys namely 90 W-7 Ni-3 Fe, 90 W-9 Ni-Mn and 90 W-8 Ni-2 Mn were selected and after producing these alloys through powder metallurgy technique, their thermal conductivity, compression flow properties and microstructure, were studied. The results of these investigations indicated that W-Ni-Mn alloys had better flow properties and lower thermal conductivities relative to W-Ni-Fe alloy. In addition Mn helped to obtain a finer microstructure in tungsten heavy alloy. Worth mentioning that a finer microstructure as well as lower thermal conductivity in this type of alloys increased the penetration depth due to formation of adiabatic shear bands during impact

  7. Ab initio and atomic kinetic Monte Carlo modelling of segregation in concentrated FeCrNi alloys

    International Nuclear Information System (INIS)

    Piochaud, J.B.; Becquart, C.S.; Domain, C.

    2013-01-01

    Internal structure of pressurised water reactors are made of austenitic materials. Under irradiation, the microstructure of these concentrated alloys evolves and solute segregation on grain boundaries or irradiation defects such as dislocation loops are observed to take place. In order to model and predict the microstructure evolution, a multi-scale modelling approach needs to be developed, which starts at the atomic scale. Atomic Kinetic Monte Carlo (AKMC) modelling is the method we chose to provide an insight on defect mediated diffusion under irradiation. In that approach, we model the concentrated commercial steel as a FeCrNi alloy (γ-Fe 70 Cr 20 Ni 10 ). As no reliable empirical potential exists at the moment to reproduce faithfully the phase diagram and the interactions of the elements and point defects, we have adjusted a pair interaction model on large amount of DFT (Density Functional Theory) calculations. The point defect properties in the Fe 70 Cr 20 Ni 10 , and more precisely, how their formation energy depends on the local environment will be presented and some AKMC results on thermal non equilibrium segregation (TNES) and radiation induce segregation will be presented. The effect of Si on the segregation will also be discussed. Preliminary results show that it is the solute- grain boundaries interactions which drive TNES

  8. Microstructural evolution of Fesbnd 22%Cr model alloy under thermal ageing and ion irradiation conditions studied by atom probe tomography

    Science.gov (United States)

    Korchuganova, Olesya A.; Thuvander, Mattias; Aleev, Andrey A.; Rogozhkin, Sergey V.; Boll, Torben; Kulevoy, Timur V.

    2016-08-01

    Nanostructure evolution during ion irradiation of two thermally aged binary Fee22Cr alloys has been investigated using atom probe tomography. Specimens aged at 500 °C for 50 and 200 h were irradiated by 5.6 MeV Fe ions at room temperature up to fluences of 0.3 × 1015 ions/cm2 and 1 × 1015 ions/cm2. The effect of irradiation on the material nanostructure was examined at a depth of 1 μm from the irradiated surface. The analysis of Cr radial concentration functions reveals that dense α‧-phase precipitates in the 200 h aged alloy become diffuse and thereby larger when subjected to irradiation. On the other hand, less Cr-enriched precipitates in the alloy aged for 50 h are less affected. The CreCr pair correlation function analysis shows that matrix inhomogeneity decreases under irradiation. Irradiation leads to a decrease in the number density of diffuse clusters, whereas in the case of well-developed precipitates it remains unchanged.

  9. Influence of manganese, carbon and nitrogen on high-temperature strength of Fe-Cr-Mn austenitic alloys

    International Nuclear Information System (INIS)

    Hosoi, Y.; Okazaki, Y.; Wade, N.; Miyahara, K.

    1990-01-01

    High Mn-Cr-Fe base alloys are candidates for the first wall material of fusion reactors because of rapid decay of radioactivity of the alloys after neutron irradiation compared with that of Ni-Cr-Fe base alloys. Their high temperature properties, however, are not clearly understood at present. In this paper, a study has been made of the effects of Mn, C and N content on the high-temperature tensile strength and creep properties of a 12% CR-Fe base alloy. Mn tends to decrease tensile strength and proof stress at intermediate temperatures. At higher temperatures in the austenite range, however, tensile properties scarcely depend on Mn content. C and N additions improve the tensile properties markedly. The combined addition of 0.2%C and 0.2%N to a 12%Cr-15%Mn-Fe base alloy makes the strength at 873K as high as that of a modified type 316 stainless steel. Combined alloying with C and N also improves the creep strength. Cold working is very useful in increasing the creep strength because of the finely dispersed precipitates in the matrix during creep. From these results, Fe-12%Cr-15%Mn-15%Mn-0.2%c-0.2%N is recommended as one of the most suitable alloys in this system for high temperature usage. (author)

  10. Near-net-shape 95W-3.5Ni-1.5Fe thin-walled products produced by plasma spray forming

    International Nuclear Information System (INIS)

    Wang, Y.M.; Xiong, X.; Min, X.B.; Xie, L.; Zheng, F.

    2010-01-01

    Tungsten heavy alloy 95W-3.5Ni-1.5Fe (in wt.%) refractory metallic thin-walled products (diameter ≤100 mm, length ≤150 mm and wall thickness ≤5 mm) were produced using plasma spray forming (PSF) covered in argon atmosphere at a pressure of 1.01 x 10 5 Pa followed by vacuum liquid phase sintering at 1465, 1485 and 1500 deg. C for 90 min, respectively. A lamellar structure consisting of vertical columnar grains and some fine particles was found in PSF deposits. Relative density of the deposits was about 87.70% with poor mechanical property. Upon vacuum liquid phase sintering, their density and property have been improved significantly. The microstructures of PSF deposits before and after vacuum sintering were found to consist with tungsten and (Ni, Fe)-rich phase. Volume fraction of (Ni, Fe)-rich phase was decreased due to vaporization that occurred in plasma spraying and vacuum liquid phase sintering. Their fracture surfaces were dominated by intergranular rupture. The lamellar structure remained in the deposits during early stages of sintering (solid state sintering and initial of liquid phase sintering). Particle rearrangement and rapid densification of the deposits did not occur until the surface of tungsten particles being modified and changed into spheroids by solution and precipitation. In the end, the PSF deposits have been transformed from lamellar structure into two phase composites with dispersed spheroidal tungsten grains embedded in a continuous network of (Ni, Fe)-rich phase.

  11. Precipitation sensitivity to alloy composition in Fe-Cr-Mn austenitic steels developed for reduced activation for fusion application

    International Nuclear Information System (INIS)

    Maziasz, P.J.; Klueh, R.L.

    1988-01-01

    Special austenitic steels are being designed in which alloying elements like Mo, Nb, and Ni are replaced with Mn, W, V, Ti, and/or Ta to reduce the long-term radioactivity induced by fusion reactor irradiation. However, the new steels still need to have properties otherwise similar to commercial steels like type 316. Precipitation strongly affects strength and radiation-resistance in austenitic steels during irradiation at 400--600/degree/C, and precipitation is also usually quite sensitive to alloy composition. The initial stage of development was to define a base Fe-Cr-Mn-C composition that formed stable austenite after annealing and cold-working, and resisted recovery or excessive formation of coarse carbide and intermetallic phases during elevated temperature annealing. These studies produced a Fe-12Cr-20Mn-0.25C base alloy. The next stage was to add the minor alloying elements W, Ti, V, P, and B for more strength and radiation-resistance. One of the goals was to produce fine MC precipitation behavior similar to the Ti-modified Fe-Cr-Ni prime candidate alloy (PCA). Additions of Ti+V+P+B produced fine MC precipitation along network dislocations and recovery/recrystallization resistance in 20% cold worked material aged at 800/degree/C for 166h, whereas W, Ti, W+Ti, or Ti+P+B additions did not. Addition of W+Ti+V+P+B also produced fine MC, but caused some σ phase formation and more recrystallization as well. 29 refs., 14 figs., 9 tabs

  12. Hot Corrosion Behavior of Bare, Cr3C2-(NiCr) and Cr3C2-(NiCr) + 0.2wt.%Zr Coated SuperNi 718 at 900 °C

    Science.gov (United States)

    Mudgal, Deepa; Singh, Surendra; Prakash, Satya

    2015-01-01

    Corrosion in incinerators, power plants, and chemical industries are frequently encountered due to the presence of salts containing sodium, sulphur, and chlorine. To obviate this problem, bare and coated alloys were tested under environments simulating the conditions present inside incinerators and power plants. 0.2 wt.% zirconium powder was incorporated in the Cr3C2-(NiCr) coating powder. The original powder and Zr containing powder was sprayed on Superni 718 alloy by D-gun technique. The bare and coated alloys were tested under Na2SO4 + K2SO4 + NaCl + KCl and Na2SO4 + NaCl environment. The corrosion rate of specimens was monitored using weight change measurements. Characterization of the corrosion products has been done using FE-SEM/EDS and XRD techniques. Bare and coated alloys showed very good corrosion resistance under given molten salt environments. Addition of 0.2wt.%Zr in Cr3C2-25%(NiCr) coating further greatly reduced the oxidation rate as well as improved the adherence of oxide scale to the coating surface during the time of corrosion.

  13. Effect of thermal cycling on the microstructure of a directionally solidified Fe, Cr, Al-TaC eutectic alloy

    Science.gov (United States)

    Harf, F. H.; Tewari, S. N.

    1977-01-01

    Cylindrical bars (1.2 cm diameter) of Fe-13.6Cr-3.7Al-9TaC (wt %) eutectic alloy were directionally solidified in a modified Bridgman type furnace at 1 cm/h. The alloy microstructure consisted of aligned TaC fibers imbedded in a bcc Fe-Cr-Al matrix. Specimens of the alloy were thermally cycled from 1100 to 425 C in a burner rig. The effects of 1800 thermal cycles on the microstructure was examined by scanning electron microscopy, revealing a zig-zag shape of TaC fibers aligned parallel to the growth direction. The mechanism of carbide solution and reprecipitation on the (111) easy growth planes, suggested previously to account for the development of irregular serrations in Co-Cr-Ni matrix alloys, is believed to be responsible for these zig-zag surfaces.

  14. Effects of alloying on Co--Si eutectoid structures and properties

    International Nuclear Information System (INIS)

    Livingston, J.D.

    1976-01-01

    The effects of various ternary alloying elements on the microstructure and properties of directionally solidified and transformed Co-Si eutectoid alloys were studied. Aligned eutectoid structures were maintained with additions of up to 10 at. percent Ni. However, higher Ni additions led to changes in both the silicide and solid-solution phases, related changes in microstructure, and decreased tensile strength. Additions of 5 at. percent Cr, Cu, Fe, or Mn produced cellular eutectoid microstructures which deteriorated the mechanical properties. Additions of W, Ta, or Al led to eutectic, rather than eutectoid, microstructures. Alloys based on the Co-W-Si eutectic appear to have the most promising high-temperature mechanical properties

  15. Pressure effects on spin density wave in Cr rich Cr-Al, Si, Mn, Fe and Co alloys

    International Nuclear Information System (INIS)

    Mizuki, Jun-ichiro; Endoh, Yasuo; Ishikawa, Yoshikazu

    1982-01-01

    The effect of pressure on the spin density wave (SDW) state in Cr rich Cr-Al, Si, Nn, Fe and Co alloys has been elucidated by neutron diffraction studies. We found that the change of the SDW wave vector Q, by applying pressure, 1/Q. delta Q/ delta P, is linearly related to the decrease of T sub(N) with increasing pressure 1/T sub(N). delta T sub(N)/ delta P and that all the results from the Cr-Si, Fe and Co alloys fall on a single straight line independent of their concentrations. Their magnetic phase diagrams in a temperature-pressure coordinate system can be related to the alloy phase diagram by employing an empirical rule that applying pressure corresponds to a decrese in the electron to atom ratio. The non transition metal Si impurity has been found to act as an electron donor, while the effect of Al is not interpreted by the two band nesting model. (author)

  16. Tensile deformation behavior and deformation twinning of an equimolar CoCrFeMnNi high-entropy alloy

    Energy Technology Data Exchange (ETDEWEB)

    Joo, S.-H.; Kato, H. [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Jang, M.J.; Moon, J. [Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang 37673 (Korea, Republic of); Tsai, C.W.; Yeh, J.W. [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Kim, H.S., E-mail: hskim@postech.ac.kr [Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang 37673 (Korea, Republic of); Center for High Entropy Alloys, Pohang University of Science and Technology, Pohang 37673 (Korea, Republic of)

    2017-03-24

    The tensile deformation and strain hardening behaviors of an equimolar CoCrFeMnNi high-entropy alloy (HEA) were investigated and compared with low and medium entropy equiatomic alloys (LEA and MEA). The HEA had a lower yield strength than the MEA because the addition of Mn weakens solid solution hardening in the HEA. However, deformation twinning induced the multiple stage strain hardening behavior of the HEA and enhanced strength and elongation. Using tensile-interrupted electron backscatter diffraction analysis, geometrically necessary dislocations were observed as plume-shaped features in grain interior, and a considerable texture was characterized, which is typical of face centered cubic metals. Moreover, the relationship between favorably oriented grains and twinning in the HEA bore a clear resemblance to the same tendency in TWIP steels. The thickness of the twin bundles was less than 100 nm. A high density of stacking defects was found in the nanotwins. Nano twinning and stacking faults were found to contribute to the remarkable mechanical properties. Deformation induced twinning not only demonstrated the dynamic Hall-Petch effect but also changed dislocation cell substructures into microband structures.

  17. Corrosion study of the passive film of amorphous Fe-Cr-Ni-(Si, P, B alloys

    Directory of Open Access Journals (Sweden)

    López, M. F.

    1996-12-01

    Full Text Available Amorphous Fe62Cr10Ni8X20 (X = P, B, Si alloys in 0.01M HCl solution have been investigated by means of standard electrochemical measurements in order to evaluate their corrosion resistance. The study reveals that the best corrosion behaviour is given by the Si containing amorphous alloy. X-ray photoelectron spectroscopy (XPS and Auger electron spectroscopy (AJES have been employed to study the composition of the passive layers, formed on the surface of the different amorphous alloys. The results on Fe62Cr10Ni8X20 show that a protective passive film, mainly consisting of oxidized chromium, greatly enhances its corrosion resistance.

    La resistencia a la corrosión de las aleaciones amorfas Fe62Cr10Ni8X20 (X = P, B, Si inmersas en HCl 0,01M se evaluó usando técnicas electroquímicas. Las técnicas de espectroscopia de fotoemisión de rayos X y espectroscopia Auger se emplearon para estudiar la composición de las capas pasivas, formadas en aire sobre la superficie de las aleaciones amorfas. Del estudio realizado se concluye que el mejor comportamiento frente a la corrosión viene dado por la aleación amorfa que contiene como metaloide Si. Esto es debido a que la capa pasiva de dicha aleación está formada principalmente de óxido de cromo, lo cual confiere una alta resistencia a la corrosión.

  18. Alloying Behavior and Properties of FeSiBAlNiCo x High Entropy Alloys Fabricated by Mechanical Alloying and Spark Plasma Sintering

    Science.gov (United States)

    Wang, Wen; Li, Boyu; Zhai, Sicheng; Xu, Juan; Niu, Zuozhe; Xu, Jing; Wang, Yan

    2018-02-01

    In this paper, FeSiBAlNiCo x (x = 0.2, 0.8) high-entropy alloy (HEA) powders were fabricated by mechanical alloying process, and the powders milled for 140 h were sintered by spark plasma sintering (SPS) technique. The microstructures and properties of as-milled powders and as-sintered samples were investigated. The results reveal that the final milling products (140 h) of both sample powders present the fully amorphous structure. The increased Co contents obviously enhance the glass forming ability and thermal stability of amorphous HEA powders, which are reflected by the shorter formation time of fully amorphous phase and the higher onset crystallization temperature, respectively. According to coercivity, the as-milled FeSiBAlNiCo x (x = 0.2, 0.8) powders (140 h) are the semi-hard magnetic materials. FeSiBAlNiCo0.8 HEA powders possess the highest saturation magnetization and largest remanence ratio. The SPS-ed products of both bulk HEAs are composed of body-centered cubic solid solution, and FeSi and FeB intermetallic phases. They possess the high relative density above 97% and excellent microhardness exceeding 1150 HV. The as-sintered bulks undergo the remarkable increase in saturation magnetization compared with the as-milled state. The SPS-ed FeSiBAlNiCo0.8 HEA exhibits the soft magnetic properties. The electrochemical corrosion test is carried out in 3.5% NaCl solution. The SPS-ed FeSiBAlNiCo0.2 HEA reveals the better passivity with low passive current density, and the higher pitting resistance with wide passive region.

  19. Sulfidation behavior of Fe20Cr alloys

    International Nuclear Information System (INIS)

    Pillis, Marina Fuser

    2001-01-01

    Alloys for use in high temperature environments rely on the formation of an oxide layer for their protection. Normally, these protective oxides are Cr 2 O 3 , Al 2 O 3 and, some times, SiO 2 . Many industrial gaseous environments contain sulfur. Sulfides, formed in the presence of sulfur are thermodynamically less stable, have lower melting points and deviate much more stoichiometrically, compared to the corresponding oxides. The mechanism of sulfidation of various metals is as yet not clear, in spite of the concerted efforts during the last decade. To help address this situation, the sulfidation behavior of Fe20Cr has been studied as a function of compositional modifications and surface state of the alloy. The alloys Fe20Cr, Fe20Cr0.7Y, Fe20Cr5Al and Fe20Cr5Al0.6Y were prepared and three sets of sulfidation tests were carried out. In the first set, the alloys were sulfidized at 700 deg C and 800 deg C for 10h. In the second set, the alloys were pre-oxidized at 1000 deg C and then sulfidized at 800 deg C for up to 45h. In the third set of tests, the initial stages of sulfidation of the alloys was studied. All the tests were carried out in a thermobalance, in flowing H 2 /2%H 2 S, and the sulfidation behavior determined as mass change per unit area. Scanning electron microscopy coupled to energy dispersive spectroscopy and X-ray diffraction analysis were used to characterize the reaction products. The addition of Y and Al increased sulfidation resistance of Fe20Cr. The addition of Y altered the species that diffused predominantly during sulfide growth. It changed from predominant cationic diffusion to predominant anionic diffusion. The addition of Al caused an even greater increase in sulfidation resistance of Fe20Cr, with the parabolic rate constant decreasing by three orders of magnitude. Y addition to the FeCrAl alloy did not cause any appreciable alteration in sulfidation resistance. Pre-oxidation of the FeCrAl and FeCrAlY alloys resulted in an extended

  20. Alloyed Ni-Fe nanoparticles as catalysts for NH3 decomposition

    DEFF Research Database (Denmark)

    Simonsen, Søren Bredmose; Chakraborty, Debasish; Chorkendorff, Ib

    2012-01-01

    A rational design approach was used to develop an alloyed Ni-Fe/Al2O3 catalyst for decomposition of ammonia. The dependence of the catalytic activity is tested as a function of the Ni-to-Fe ratio, the type of Ni-Fe alloy phase, the metal loading and the type of oxide support. In the tests with high...... temperatures and a low NH3-to-H2 ratio, the catalytic activity of the best Ni-Fe/Al2O3 catalyst was found to be comparable or even better to that of a more expensive Ru-based catalyst. Small Ni-Fe nanoparticle sizes are crucial for an optimal overall NH3 conversion because of a structural effect favoring...

  1. Hot corrosion behavior of Ni-Cr-W-C alloys in impure helium gas

    International Nuclear Information System (INIS)

    Ohmura, Taizo; Sahira, Kensho; Sakonooka, Akihiko; Yonezawa, Noboru

    1976-01-01

    Influence of the minor alloy constituents such as Al, Mn and Si on the hot corrosion behavior of Ni-20Cr-20W-0.07C alloy was studied in 99.995% helium gas at 1000 0 C, comparing with that behavior of commercial Ni-base superalloys (Hastelloy X and Inconel 617). The low oxidizing potential in the impure helium gas usually causes selective oxidation of these elements and the growth of oxide whiskers on the surface of specimen at elevated temperature. The intergranular attack was caused by selective oxidation of Al, Si and Mn. The spalling of oxide film was restrained by addition of Mn and Si, providing tough spinel type oxide film on the surface and 'Keyes' on the oxide-matrix interface respectively. The amount and the morphology of the oxide whiskers depended on Si and Mn content. More than 0.29% of Si content without Mn always caused the growth of rather thinner whiskers with smooth surface, and the whiskers analyzed by electron diffraction patterns and EPMA to be Cr 2 O 3 containing Si. Mn addition changed the whiskers to thicker ones of spinel type oxide (MnCr 2 O 1 ) with rough surface. On the basis of these results, the optimum content of Al, Mn and Si to minimize the growth of whiskers, the intergranular attack and the spalling of oxide film was discussed. (auth.)

  2. Thermodynamic analysis of (Ni, Fe)3Al formation by mechanical alloying

    International Nuclear Information System (INIS)

    Adabavazeh, Z.; Karimzadeh, F.; Enayati, M.H.

    2012-01-01

    Highlights: ► (Ni, Fe) 3 Al intermetallic compound was synthesized by mechanical alloying. ► We use a thermodynamic analysis to predict the more stable phase. ► We calculate the Gibbs free-energy changes by using extended Miedema model. ► The results of MA compared with thermodynamic analysis and showed a good agreement with it. - Abstract: (Ni, Fe) 3 Al intermetallic compound was synthesized by mechanical alloying (MA) of Ni, Fe and Al elemental powder mixtures of composition Ni 50 Fe 25 Al 25 . Phase transformation and microstructure characteristics of the alloy powders were investigated by X-ray diffraction (XRD). The results show that mechanical alloying resulted in a Ni (Al, Fe) solid solution. By continued milling, this structure transformed to the disordered (Ni, Fe) 3 Al intermetallic compound. A thermodynamic model developed on the basis of extended theory of Miedema is used to calculate the Gibbs free-energy changes. Final product of MA is a phase having minimal Gibbs free energy compared with other competing phases in Ni–Fe–Al system. However in Ni–Fe–Al system, the most stable phase at all compositions is intermetallic compound (not amorphous phase or solid solution). The results of MA were compared with thermodynamic analysis and revealed the leading role of thermodynamic on the formation of MA product prediction.

  3. Minor-alloyed Cu-Ni-Si alloys with high hardness and electric conductivity designed by a cluster formula approach

    Directory of Open Access Journals (Sweden)

    Dongmei Li

    2017-08-01

    Full Text Available Cu-Ni-Si alloys are widely used due to their good electrical conductivities in combination with high strength and hardness. In the present work, minor-alloying with M = (Cr, Fe, Mo, Zr was conducted for the objective of further improving their hardness while maintaining their conductivity level. A cluster-plus-glue-atom model was introduced to design the compositions of M-alloyed Cu-Ni-Si alloys, in which an ideal composition formula [(Ni,Si,M-Cu12]Cu3 (molar proportion was proposed. To guarantee the complete precipitation of solute elements in fine δ-Ni2Si precipitates, the atomic ratio of (Ni,M/Si was set as 2/1. Thus the designed alloy series of Cu93.75(Ni/Zr3.75Si2.08(Cr/Fe/Mo0.42 (at% were arc-melted into ingots under argon atmosphere, and solid-solutioned at 950 °C for 1 h plus water quenching and then aged at 450 °C for different hours. The experimental results showed that these designed alloys exhibit high hardness (HV > 1.7 GPa and good electrical conductivities (≥ 35% IACS. Specifically, the quinary Cu93.75Ni3.54Si2.08(Cr/Fe0.42Zr0.21 alloys (Cu-3.32Ni-0.93Si-0.37(Cr/Fe−0.30Zr wt% possess both a high hardness with HV = 2.5–2.7 GPa, comparable to the high-strength KLFA85 alloy (Cu-3.2Ni-0.7Si-1.1Zn wt%, HV = 2.548 GPa, and a good electrical conductivity (35–36% IACS.

  4. Strength and ductility of Ni3Al alloyed with boron and substitutional elements

    International Nuclear Information System (INIS)

    Ishikawa, K.; Aoki, K.; Masumoto, T.

    1995-01-01

    The effect of simultaneous alloying of boron (B) and the substitutional elements M on mechanical properties of Ni 3 Al was investigated by the tensile test at room temperature. The yield strength of Ni 3 Al+B increases by alloying with M except for Fe and Ga. In particular, it increases by alloying with Hf, Nb, W, Ta, Pd and Si. The fracture strength of Ni 3 Al+B increases by alloying with Pd, Ga, Si and Hf, but decreases with the other elements. Elongation of Ni 3 Al+B increases by alloying with Ga, Fe and Pd, but decreases with other elements. Hf and Pd is the effective element for the increase of the yield strength and the fracture strength of Ni 3 Al+B, respectively. Alloying with Hf leads to the increases of the yield strength and the fracture strength of Ni 3 Al+B, but to the lowering of elongation. On the other hand, alloying with Pd improves all mechanical properties, i.e. the yield strength, the fracture strength and elongation. On the contrary, alloying with Ti, V and Co leads to the lowering of mechanical properties of Ni 3 Al+B. The reason why ductility of Ni 3 Al+B is reduced by alloying with some elements M is discussed

  5. The use of nitrogen to improve the corrosion resistance of FeCrNiMo alloys for the chemical process industries

    Energy Technology Data Exchange (ETDEWEB)

    Kearns, J.R.; Deverell, H.E.

    1987-06-01

    The addition of 0.1 to 0.25 wt% nitrogen to austenitic alloys has been shown to enhance resistance to localized corrosion in oxidizing chloride and reducing acid solutions. Further tests of FeCrNiMo alloys assess the effects of nitrogen additions on: mechanical properties, chloride and caustic stress corrosion cracking resistance, passivation characteristics, and general corrosion rates in various acid, alkali, and salt solutions pertinent to the chemical process industries. The precipitation of chromium-rich secondary phases was retarded by solid solution additions of 0.1 to 0.25 wt% nitrogen. The corrosion resistance of FeCrNiMoN alloys in the welded condition was improved by using shield-gas mixtures of argon and 2.5 to 5.0 wt% nitrogen.

  6. First-Principles Study on the Structural Stability and Segregation Behavior of γ-Fe/Cr2N Interface with Alloying Additives M (M = Mn, V, Ti, Mo, and Ni

    Directory of Open Access Journals (Sweden)

    Hui Huang

    2016-07-01

    Full Text Available This study investigated the structural stability and electrochemical properties of alloying additives M (M = Mn, V, Ti, Mo, or Ni at the γ-Fe(111/Cr2N(0001 interface by the first-principles method. Results indicated that V and Ti were easily segregated at the γ-Fe(111/Cr2N(0001 interface and enhanced interfacial adhesive strength. By contrast, Ni and Mo were difficult to segregate at the γ-Fe(111/Cr2N(0001 interface. Moreover, the results of the work function demonstrated that alloying additives Mn reduced local electrochemical corrosion behavior of the γ-Fe(111/Cr2N(0001 interface by cutting down Volta potential difference (VPD between clean γ-Fe(111 and Cr2N(0001, while alloying additives V, Ti, Mo, and Ni at the γ-Fe(111/Cr2N(0001 interface magnified VPD between clean γ-Fe(111 and Cr2N(0001, which were low-potential sites that usually serve as local attack initiation points.

  7. Ductile long range ordered alloys with high critical ordering temperature and wrought articles fabricated therefrom

    Science.gov (United States)

    Liu, Chain T.; Inouye, Henry

    1979-01-01

    Malleable long range ordered alloys having high critical ordering temperatures exist in the V(Fe, Co).sub.3 and V(Fe, Co, Ni).sub.3 systems. These alloys have the following compositions comprising by weight: 22-23% V, 14-30% Fe, and the remainder Co or Co and Ni with an electron density no more than 7.85. The maximum combination of high temperature strength, ductility and creep resistance are manifested in the alloy comprising by weight 22-23% V, 14-20% Fe and the remainder Co and having an atomic composition of V(Fe .sub.0.20-0.26 C Co.sub.0.74-0.80).sub.3. The alloy comprising by weight 22-23% V, 16-17% Fe and 60-62% Co has excellent high temperature properties. The alloys are fabricable into wrought articles by casting, deforming, and annealing for sufficient time to provide ordered structure.

  8. Stress corrosion cracking of Ni-Fe-Cr alloys in acid sulfate environments relevant to CANDU steam generators

    Energy Technology Data Exchange (ETDEWEB)

    Persaud, S.Y.; Carcea, A.G., E-mail: suraj.persaud@mail.utoronto.ca [Univ. of Toronto, Toronto, ON (Canada); Huang, J.; Korinek, A.; Botton, G.A. [McMaster Univ., Hamilton, ON (Canada); Newman, R.C. [Univ. of Toronto, Toronto, ON (Canada)

    2014-07-01

    Ni-Fe-Cr alloys used in nuclear plants have been found susceptible to stress corrosion cracking (SCC) in acid sulfate environments. Electrochemical measurements and SCC tests were done using Ni, Alloy 600, and Alloy 800 in acid sulfate solutions at 315 {sup o}C. Electrochemical measurements suggested that sulfate is a particularly aggressive anion in mixed chloride systems. Cracks with lengths in excess of 300 μm were present on stressed Alloy 800 samples after 60 hours. High resolution analytical electron microscopy was used to extract a crack tip from an Alloy 800 sample and draw final conclusions with respect to the mechanism of SCC. (author)

  9. Soft magnetic properties of hybrid ferromagnetic films with CoFe, NiFe, and NiFeCuMo layers

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jong-Gu [Eastern-western Biomedical Engineering, Sangji University, Wonju 220-702 (Korea, Republic of); Hwang, Do-Guwn [Dept. of Oriental Biomedical Engineering, Sangji University, Wonju 220-702 (Korea, Republic of); Rhee, Jang-Roh [Dept. of Physics, Sookmyung Women' s University, Seoul 140-742 (Korea, Republic of); Lee, Sang-Suk, E-mail: sslee@sangji.ac.kr [Dept. of Oriental Biomedical Engineering, Sangji University, Wonju 220-702 (Korea, Republic of)

    2011-09-30

    Two-layered ferromagnetic alloy films (NiFe and CoFe) with intermediate NiFeCuMo soft magnetic layers of different thicknesses were investigated to understand the relationship between coercivity and magnetization process by taking into account the strength of hard-axis saturation field. The thickness dependence of H{sub EC} (easy-axis coercivity), H{sub HS} (hard-axis saturation field), and {chi} (susceptibility) of the NiFeCuMo thin films in glass/Ta(5 nm)/[CoFe or NiFe(5 nm-t/2)]/NiFeCuMo(t = 0, 4, 6, 8, 10 nm)/[CoFe or NiFe(5 nm-t/2)]/Ta(5 nm) films prepared using the ion beam deposition method was determined. The magnetic properties (H{sub EC}, H{sub HS}, and {chi}) of the ferromagnetic CoFe, NiFe three-layers with an intermediate NiFeCuMo super-soft magnetic layer were strongly dependent on the thickness of the NiFeCuMo layer.

  10. Grain boundary segregation in FeCrNi model alloys; Korngrenzensegregation in FeCrNi-Modellegierungen

    Energy Technology Data Exchange (ETDEWEB)

    Schlueter, B.; Schneider, F.; Mummert, K. [Institut fuer Festkoerper- und Werkstofforschung Dresden e.V. (Germany); Muraleedharan, P. [Indira Gandhi Centre for Atomic Research, Kalpakkam (India). Div. of Metallurgy

    1998-12-31

    P and S segregate at the grain boundaries and thus increase susceptibility to intergranular corrosion at those sites. This could be proven by means of nitric acid-chromate tests and potentiostatic etching tests. There is a direct connection between loss in mass, mean depth of intergranular corrosion attacks, dissolution current density, and level of segregation-induced concentration of P and S at the grain boundaries. The segregation effect at these sites was found to be most evident in specimens of the examined Fe-Cr-Ni steel which had been heat-treated for 1000 hours at 550 C. However, segregation occurs also in materials that received a heat treatment of 400 C/5000 hours, while intergranular corrosion is observed only after heat treatment of 500 C/1000 hours. Apart from segregation of P, formation of Cr-rich phosphides is observed, which leads to depletion of Cr at the precipitates. (orig./CB) [Deutsch] P und S segregieren an die KG und erhoehen dort die IK-Anfaelligkeit. Dies konnte mit Hilfe von Salpetersaeure-Chromat- und Potentiostatischem Aetztest nachgewiesen werden. Es besteht ein direkter Zusammenhang zwischen Masseverlust, mittlerer IK-Angriffstiefe, Aufloesungsstromdichte und Hoehe der segregationsbedingten Anreicherungen von P und S an den KG. Der KG-Segregationseffekt am untersuchten Fe-Cr-Ni-Stahl ist im Waermebehandlungszustand 550 C/1000 h am deutlichsten ausgepraegt. Aber auch bereits bei 400 C/5000 h findet Segregation statt. IKSpRK tritt nur im Waermebehandlungszustand 550 C/1000 h auf. Neben der P-Segregation wird die Bildung Cr-reicher Phosphide beobachtet, die zur Abreicherung von Cr an den Ausscheidungen fuehrt. (orig.)

  11. Reactive Stresses in Ni49Fe18Ga27Co6 Shape-Memory-Alloy Single Crystals

    Science.gov (United States)

    Averkin, A. I.; Krymov, V. M.; Guzilova, L. I.; Timashov, R. B.; Soldatov, A. V.; Nikolaev, V. I.

    2018-03-01

    The reactive stresses induced in Ni49Fe18Ga27Co6-alloy single crystals during martensitic transformations with a limited possibility of shape-memory-strain recovery have been experimentally studied. The data on these crystals are compared with the results obtained previously for Cu-Al-Ni, Ni-Ti, and Ni‒Fe-Ga crystals. The potential of application of the Ni49Fe18Ga27Co6 single crystals in designing drives and power motors is demonstrated.

  12. Estimation of the Temperature-Dependent Nitrogen Solubility in Stainless Fe-Cr-Mn-Ni-Si-C Steel Melts During Processing

    Science.gov (United States)

    Wendler, Marco; Hauser, Michael; Sandig, Eckhard Frank; Volkova, Olena

    2018-04-01

    The influence of chemical composition, temperature, and pressure on the nitrogen solubility of various high alloy stainless steel grades, namely Fe-14Cr-(0.17-7.77)Mn-6Ni-0.5Si-0.03C [wt pct], Fe-15Cr-3Mn-4Ni-0.5Si-0.1C [wt pct], and Fe-19Cr-3Mn-4Ni-0.5Si-0.15C [wt pct], was studied in the melt. The temperature-dependent N-solubility was determined using an empirical approach proposed by Wada and Pehlke. The thus calculated N-concentrations overestimate the actual N-solubility of all the studied Fe-Cr-Mn-Ni-Si-C steel melts at a given temperature and pressure. Consequently, the calculation model has to be modified by Si and C because both elements are not recognized in the original equation. The addition of the 1st and 2nd order interaction parameters for Si and C to the model by Wada and Pehlke allows a precise estimation of the temperature-dependent nitrogen solubility in the liquid steel bath, and fits very well with the measured nitrogen concentrations during processing of the steels. Moreover, the N-solubility enhancing effect of Cr- and Mn-additions has been demonstrated.

  13. High temperature aging structures of Ni-20Cr-20W alloys

    International Nuclear Information System (INIS)

    Ohmura, Taizo; Sahira, Kensho; Sakonooka, Akihiko; Yonezawa, Noboru

    1977-01-01

    High temperature aging structures and age hardening of Ni-20Cr-20W alloys developed as the superalloys for the nuclear energy steelmaking, and effects of C and Zr additions to the alloys and the effect of preheat treatment on these properties were studied. M 6 C, α-W and two kinds of M 23 C 6 having different lattice parameters were found as precipitates in the alloys. M 23 C 6 whose lattice parameter was around 10.7A precipitated in the early stage of aging at 700 0 C-1,150 0 C, and the carbide changed to M 6 C at higher temperature than 1,000 0 C, but it remained as a stable carbide at lower temperature than 900 0 C. α-W precipitated at 800 0 C-1,100 0 C after precipitation of M 23 C 6 and it disappeared with increase of M 6 C. M 23 C 6 having the larger lattice parameter (10.9A) precipitated transitionally in aging stage of 26 x 10 3 in Larson Miller parameter at 900 0 C and 1,000 0 C. Age hardening corresponded to the precipitation of M 23 C 6 and it was reduced by the double pre-heat-treatment. Zr addition and amount of C influenced on the aging structure and age hardening. Zr seemed to be a favorable element to stabilize the carbide. (auth.)

  14. Ion irradiation effects on high purity bcc Fe and model FeCr alloys

    International Nuclear Information System (INIS)

    Bhattacharya, Arunodaya

    2014-01-01

    FeCr binary alloys are a simple representative of the reduced activation ferritic/martensitic (F-M) steels, which are currently the most promising candidates as structural materials for the sodium cooled fast reactors (SFR) and future fusion systems. However, the impact of Cr on the evolution of the irradiated microstructure in these materials is not well understood in these materials. Moreover, particularly for fusion applications, the radiation damage scenario is expected to be complicated further by the presence of large quantities of He produced by the nuclear transmutation (∼ 10 appm He/dpa). Within this context, an elaborate ion irradiation study was performed at 500 C on a wide variety of high purity FeCr alloys (with Cr content ranging from ∼ 3 wt.% to 14 wt.%) and a bcc Fe, to probe in detail the influence of Cr and He on the evolution of microstructure. The irradiations were performed using Fe self-ions, in single beam mode and in dual beam mode (damage by Fe ions and co-implantation of He), to separate ballistic damage effect from the impact of simultaneous He injection. Three different dose ranges were studied: high dose (157 dpa, 17 appm He/dpa for the dual beam case), intermediate dose (45 dpa, 57 appm He/dpa for dual beam case) and in-situ low dose (0.33 dpa, 3030 appm He/dpa for the dual beam case). The experiments were performed at the JANNuS triple beam facility and dual beam in situ irradiation facility at CEA-Saclay and CSNSM, Orsay respectively. The microstructure was principally characterized by conventional TEM, APT and EDS in STEM mode. The main results are as follows: 1) A comparison of the cavity microstructure in high dose irradiated Fe revealed strong swelling reduction by the addition of He. It was achieved by a drastic reduction in cavity sizes and an increased number density. This behaviour was observed all along the damage depth, up to the damage peak. 2) Cavity microstructure was also studied in the dual beam high dose

  15. Erosion-oxidation behavior of thermal sprayed Ni20Cr alloy and WC and Cr3C2 cermet coatings

    Directory of Open Access Journals (Sweden)

    Clarice Terui Kunioshi

    2005-06-01

    Full Text Available An apparatus to conduct high temperature erosion-oxidation studies up to 850 °C and with particle impact velocities up to 15 m.s-1 was designed and constructed in the Corrosion Laboratories of IPEN. The erosion-oxidation behavior of high velocity oxy fuel (HVOF sprayed alloy and cermet coatings of Ni20Cr, WC 20Cr7Ni and Cr3C2 Ni20Cr on a steel substrate has been studied. Details of this apparatus and the erosion-oxidation behavior of these coatings are presented and discussed. The erosion-oxidation behavior of HVOF coated Cr3C2 25(Ni20Cr was better than that of WC 20Cr7Ni, and the erosion-oxidation regimes have been identified for these coatings at particle impact velocity of 3.5 m.s-1, impact angle of 90° and temperatures in the range 500 to 850 °C.

  16. Radiation damage buildup and dislocation evolution in Ni and equiatomic multicomponent Ni-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Levo, E. [Department of Physics, P.O. Box 43, FIN-00014, University of Helsinki (Finland); Granberg, F., E-mail: fredric.granberg@helsinki.fi [Department of Physics, P.O. Box 43, FIN-00014, University of Helsinki (Finland); Fridlund, C.; Nordlund, K. [Department of Physics, P.O. Box 43, FIN-00014, University of Helsinki (Finland); Djurabekova, F. [Department of Physics, P.O. Box 43, FIN-00014, University of Helsinki (Finland); Helsinki Institute of Physics, P.O. Box 43, FIN-00014, University of Helsinki (Finland)

    2017-07-15

    Single-phase multicomponent alloys of equal atomic concentrations (“equiatomic”) have proven to exhibit promising mechanical and corrosion resistance properties, that are sought after in materials intended for use in hazardous environments like next-generation nuclear reactors. In this article, we investigate the damage production and dislocation mobility by simulating irradiation of elemental Ni and the alloys NiCo, NiCoCr, NiCoFe and NiFe, to assess the effect of elemental composition. We compare the defect production and the evolution of dislocation networks in the simulation cells of two different sizes, for all five studied materials. We find that the trends in defect evolution are in good agreement between the different cell sizes. The damage is generally reduced with increased alloy complexity, and the dislocation evolution is specific to each material, depending on its complexity. We show that increasing complexity of the alloys does not always lead to decreased susceptibility to damage accumulation under irradiation. We show that, for instance, the NiCo alloy behaves very similarly to Ni, while presence of Fe or Cr in the alloy even as a third component reduces the saturated level of damage substantially. Moreover, we linked the defect evolution with the dislocation transformations in the alloys. Sudden drops in defect number and large defect fluctuations from the continuous irradiation can be explained from the dislocation activity.

  17. Corrosive and cytotoxic properties of compact specimens and microparticles of Ni-Cr dental alloy.

    Science.gov (United States)

    Ristic, Ljubisa; Vucevic, Dragana; Radovic, Ljubica; Djordjevic, Snezana; Nikacevic, Milutin; Colic, Miodrag

    2014-04-01

    Nickel-chromium (Ni-Cr) dental alloys have been widely used in prosthodontic practice, but there is a permanent concern about their biocompatibility due to the release of metal ions. This is especially important when Ni-Cr metal microparticles are incorporated into gingival tissue during prosthodontic procedures. Therefore, the aim of this study was to examine and compare the corrosion and cytotoxic properties of compact specimens and microparticles of Ni-Cr dental alloy. Ni-Cr alloy, Remanium CSe bars (4 mm diameter), were made by the standard casting method and then cut into 0.5-mm-thick disks. Metal particles were obtained by scraping the bars using a diamond instrument for crown preparation. The microstructure was observed by an optical microscope. Quantitative determination and morphological and dimensional characterization of metal particles were carried out by a scanning electron microscope and Leica Application Suite software for image analysis. Corrosion was studied by conditioning the alloy specimens in the RPMI 1640 medium, containing 10% fetal calf serum in an incubator with 5% CO2 for 72 hours at 37°C. Inductively coupled plasma-optical emission spectrometry was used to assess metal ion release. The cytotoxity of conditioning medium (CM) was investigated on L929 cells using an MTT test. One-way ANOVA was used for statistical analysis. After casting, the microstructure of the Remanium CSe compact specimen composed of Ni, Cr, Mo, Si, Fe, Al, and Co had a typical dendritic structure. Alloy microparticles had an irregular shape with a wide size range: from less than 1 μm to more than 100 μm. The release of metal ions, especially Ni and Mo from microparticles, was significantly higher, compared to the compact alloy specimen. The CM prepared from compact alloy was not cytotoxic at any tested dilutions, whereas CM from alloy microparticles showed dose-dependent cytotoxicity (90% CM and 45% CM versus control; p alloy. This could affect health on long

  18. Resonant Ni and Fe KLL Auger spectra photoexcited from NiFe alloys

    International Nuclear Information System (INIS)

    Koever, L.; Cserny, I.; Berenyi, Z.; Egri, S.; Novak, M.

    2005-01-01

    Complete text of publication follows. KLL Auger spectra of 3d transition metal atoms in solid environment, measured using high energy resolution, give an insight into the details of the local electronic structure surrounding the particular atoms emitting the signal Auger electrons. Fine tuning the energy of the exciting monochromatic photons across the K-absorption edge, features characteristic to resonant phenomena can be identified in the spectra. The shapes of the resonantly photoexcited KLL Auger spectra induced from 3d transition metals and alloys are well interpreted by the single step model of the Auger process, based on the resonant scattering theory. The peak shapes are strongly influenced by the 4p partial density of unoccupied electronic states around the excited atom. High energy resolution studies of KLL Auger spectra of 3d transition metals using laboratory X-ray sources, however, request very demanding experiments and yield spectra of limited statistical quality making the evaluation of the fine details in the spectra difficult. The Tunable High Energy XPS (THE- XPS) instrument at BW2 offers optimum photon x and energy resolution for spectroscopy of deep core Auger transitions. For the present measurements high purity polycrystalline Ni and Fe sheets as well as NiFe alloy samples of different compositions (Ni 80 Fe 20 , Ni 50 Fe 50 , Ni 20 Fe 80 ) were used. The surfaces of the samples were cleaned by in-situ argon ion sputtering. The measurements of the Ni and Fe KL 23 L 23 Auger spectra of the metal and alloy samples were performed with the THE-XPS instrument using high electron energy resolution (0.2 eV). In Fig.1, the measured Fe KL 23 L 23 spectrum, photoexcited at the Fe K absorption edge from Fe metal, is compared with the respective spectrum excited from a Ni 50 Fe 50 alloy. A significant broadening of the 1 D 2 peak and an enhancement of the spectral intensity at the low energy loss part of this peak observed in the alloy sample, while the

  19. The influence of nickel content on microstructures of Fe-Cr-Ni austenitic alloys irradiated with nickel ions

    International Nuclear Information System (INIS)

    Muroga, T.; Yoshida, N.; Garner, F.A.

    1990-11-01

    The objectives of this effort is to identify the mechanisms involved in the radiation-induced evolution of microstructure in materials intended for fusion applications. The results of this study are useful in interpreting the results of several other ongoing experiments involving either spectral or isotopic tailoring to study the effects of helium on microstructure evolution. Ion-irradiated Fe-15Cr-XNi (X = 20, 35, 45, 60, 75) ternary alloys and a 15Cr-85Ni binary alloy were examined after bombardment at 675 degree C and compared to earlier observations made on these same alloys after irradiation in EBR-II at 510 or 538 degree C. The response of the ion-irradiated microstructures to nickel content appears to be very consistent with that of neutron irradiation even though there are four orders of magnitude difference in displacement rate and over 200 degree C difference in temperature. It appears that the transition to higher rates of swelling during both types of irradiation is related to the operation of some mechanisms that is not directly associated with void nucleation. 6 refs., 8 figs

  20. Laser surface alloying of aluminium with WC+Co+NiCr for improved wear resistance

    CSIR Research Space (South Africa)

    Nath, S

    2012-03-01

    Full Text Available Department of Metallurgical & Materials Engineering, IIT Kharagpur, West Bengal, India 2National Laser Centre, CSIR, Pretoria, South Africa Abstract In the present study, laser surface alloying of aluminium with WC+Co+NiCr (in the ratio of 70... be used for dispersion of ceramic materials into metallic matrix and hence, form a ceramic dispersed metal matrix composite on metallic substrate [3]. The advantages of laser surface alloying include refinement of the microstructure, uniform dispersion...

  1. Irradiation effects in Fe-30%Ni alloy during Ar ion implantation

    International Nuclear Information System (INIS)

    Soukieh, Mohamad; Al-Mohamad, Ali

    1993-12-01

    The use of metallic thin films for studying the processes which take place during ion irradiation has recently increased. For example, ion implantation is widely used to study the structural defects in transition metallic thin films such as (Fe, Ni, Co), because it can simulate the effects occurring in nuclear reactors during neutron irradiation especially the swelling of reactor materials. The swelling of metals and alloys is strongly related to the material structure and to the irradiation conditions. The general feature of formation of structural defects as a function of irradiation dosage and annealing temperature is well known. However, the detailed mechanisms are still not well understood. For example, the swelling of iron alloy with 30-35% nickel is very small in comparison with other Ni concentrations, and there is no clear information on the possibility of phase transitions in fe-Ni alloys during irradiation. The aim of this work is to study the phase-structural changes in Fe-30% Ni implanted by high dose of argon ions. The effect of irradiation with low energy argon ions (40 KeV, and fluences of 10.E15 to 10.E17 ions/cm) on the deposited thin films of Fe-30% Ni alloy was investigated using RBS and TEM techniques. The thicknesses of these films were about 65+-10 nm deposited on ceramic, KBr, and Be fiols substrates. Gas bubble formation and profile distribution of the implanted argon ions were investigated. Formation of an ordered phase Fe 3 Ni during irradiation appears to inhibit gas bubble formations in the film structure. (author). 17 refs., 15 figs., 7 tabs

  2. {gamma}-Fe phase plasma-induced on the surface of thin S3A alloy ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Cabral-Prieto, A., E-mail: agustin.cabral@inin.gob.mx; Garcia-Sosa, I., E-mail: irma.garcia@inin.gob.mx [Instituto Nacional de Investigaciones Nucleares, Departamento de Quimica (Mexico); Nava, N., E-mail: tnava@imp.mx [Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas (Mexico); Camps, E., E-mail: enrique.camps@inin.gob.mx; Escobar, Luis, E-mail: luis.escobar@inin.gov.mx [Instituto Nacional de Investigaciones Nucleares, Departamento de Quimica (Mexico); Lopez-Castanarez, R., E-mail: rlc@anuies.mx; Olea-Cardoso, O., E-mail: olc@anuies.mx [Universidad Autonoma del Edo. de Mexico, Facultad de Quimica (Mexico)

    2011-11-15

    Amorphous alloy ribbons of Fe{sub 77}Cr{sub 2}B{sub 16}Si{sub 5} were exposed to cold plasmas of N{sub 2} and Ar-N{sub 2} at temperatures lower than T{sub x} = 808 K. The conversion X-ray Moessbauer spectra of the plasma-exposed ribbons consist of a singlet and a broadened magnetic sextet. The singlet with isomer shift {delta} = -0.11 mm/s can be assigned to {gamma}-Fe austenite phase. Minor bulk magnetic changes in the alloy were measured as a consequence of these treatments; e.g. the relative intensities A23 of the transmission Moessbauer spectra of the untreated and treated samples, were 3.22 and 3.56, respectively, the B{sub hf} values changed from 22.9 T (untreated sample) to 22.4 T (plasma treated samples). Unexpectedly, the {gamma}-Fe phase can also be produced by simply heating the alloy ribbons under N{sub 2} flux at temperatures as low as 423 K. Moessbauer data of the crystallized samples are also reported, and a qualitative assessment on the mechanical properties of the Fe{sub 77}Cr{sub 2}B{sub 16}Si{sub 5} alloy associated with the plasma and/or temperature surface induced {gamma}-Fe phase is given.

  3. Evolution of ion damage at 773K in Ni- containing concentrated solid-solution alloys

    Science.gov (United States)

    Shi, Shi; He, Mo-Rigen; Jin, Ke; Bei, Hongbin; Robertson, Ian M.

    2018-04-01

    Quantitative analysis of the impact of the compositional complexity in a series of Ni-containing concentrated solid-solution alloys, Ni, NiCo, NiFe, NiCoCr, NiCoFeCr, NiCoFeCrMn and NiCoFeCrPd, on the evolution of defects produced by 1 MeV Kr ion irradiation at 773 K is reported. The dynamics of the evolution of the damage structure during irradiation to a dose of 2 displacements per atom were observed directly by performing the ion irradiations in electron transparent foils in a transmission electron microscope coupled to an ion accelerator. The defect evolution was assessed through measurement of the defect density, defect size and fraction of perfect and Frank loops. These three parameters were dependent on the alloying element as well as the number of elements. The population of loops was sensitive to the ion dose and alloy composition as faulted Frank loops were observed to unfault to perfect loops with increasing ion dose. These dependences are explained in terms of the influence of each element on the lifetime of the displacement cascade as well as on defect formation and migration energies.

  4. Variation in band gap of lanthanum chromate by transition metals doping LaCr0.9A0.1O3 (A:Fe/Co/Ni)

    International Nuclear Information System (INIS)

    Naseem, Swaleha; Khan, Wasi; Saad, A. A.; Shoeb, M.; Ahmed, Hilal; Naqvi, A. H.; Husain, Shahid

    2014-01-01

    Transition metal (Fe, Co, Ni) doped lanthanum chromate (LaCrO 3 ) nanoparticles (NPs) were prepared by gel combustion method and calcinated at 800°C. Microstructural studies were carried by XRD and SEM/EDS techniques. The results of structural characterization show the formation of all samples in single phase without any impurity. Optical properties were studied by UV- visible and photoluminescence techniques. The energy band gap was calculated and the variation was observed with the doping of transition metal ions. Photoluminescence spectra show the emission peak maxima for the pure LaCrO 3 at about 315 nm. Influence of Fe, Co, Ni doping was studied and compared with pure lanthanum chromate nanoparticles

  5. Localized Corrosion of Alloy 22 -Fabrication Effects-FY05 Summary Report

    International Nuclear Information System (INIS)

    Rebak, R B

    2005-01-01

    general and localized corrosion behavior both in the wrought and annealed condition and in the as-welded condition. The specimens for testing were mostly prepared from flat plates of material. It was important to determine if the process of fabricating a full diameter Alloy 22 container will affect the corrosion performance of this alloy. Specimens were prepared directly from a fabricated container and tested for corrosion resistance. Results show that both the anodic corrosion behavior and the localized corrosion resistance of specimens prepared from a welded fabricated container were the same as from flat welded plates. That is, rolling and welding plates using industrial practices do not hinder the corrosion resistant of Alloy 22. (3) Effect of Black Annealing Oxide Scale--The resistance of Alloy 22 to localized corrosion, mainly crevice corrosion, has been extensively investigated in the last few years. This was done mostly using freshly polished specimens. At this time it was important to address the effect an oxide film or scale that forms during the high temperature annealing process or solution heat treatment (SHT) and its subsequent water quenching. Electrochemical tests such as cyclic potentiodynamic polarization (CPP) have been carried out to determine the repassivation potential for localized corrosion and to assess the mode of attack on the specimens. Tests have been carried out in parallel using mill annealed (MA) specimens free from oxide on the surface. The comparative testing was carried out in six different electrolyte solutions at temperatures ranging from 60 to 100 C. Results show that the repassivation potential of the specimens containing the black anneal oxide film on the surface was practically the same as the repassivation potential for oxide-free specimens. (4) Heat-to-Heat Variability--Testing of Ni-Cr-Mo Plates with varying heat chemistry: The ASTM standard B 575 provides the range of the chemical composition of Nickel-Chromium-Molybdenum (Ni-Cr

  6. Gaseous Phase and Electrochemical Hydrogen Storage Properties of Ti50Zr1Ni44X5 (X = Ni, Cr, Mn, Fe, Co, or Cu for Nickel Metal Hydride Battery Applications

    Directory of Open Access Journals (Sweden)

    Jean Nei

    2016-07-01

    Full Text Available Structural, gaseous phase hydrogen storage, and electrochemical properties of a series of the Ti50Zr1Ni44X5 (X = Ni, Cr, Mn, Fe, Co, or Cu metal hydride alloys were studied. X-ray diffraction (XRD and scanning electron microscopy (SEM revealed the multi-phase nature of all alloys, which were composed of a stoichiometric TiNi matrix, a hyperstoichiometric TiNi minor phase, and a Ti2Ni secondary phase. Improvement in synergetic effects between the main TiNi and secondary Ti2Ni phases, determined by the amount of distorted lattice region in TiNi near Ti2Ni, was accomplished by the substitution of an element with a higher work function, which consequently causes a dramatic increase in gaseous phase hydrogen storage capacity compared to the Ti50Zr1Ni49 base alloy. Capacity performance is further enhanced in the electrochemical environment, especially in the cases of the Ti50Zr1Ni49 base alloy and Ti50Zr1Ni44Co5 alloy. Although the TiNi-based alloys in the current study show poorer high-rate performances compared to the commonly used AB5, AB2, and A2B7 alloys, they have adequate capacity performances and also excel in terms of cost and cycle stability. Among the alloys investigated, the Ti50Zr1Ni44Fe5 alloy demonstrated the best balance among capacity (394 mAh·g−1, high-rate performance, activation, and cycle stability and is recommended for follow-up full-cell testing and as the base composition for future formula optimization. A review of previous research works regarding the TiNi metal hydride alloys is also included.

  7. Nickel and cobalt base alloys

    International Nuclear Information System (INIS)

    Houlle, P.

    1994-01-01

    Nickel base alloys have a good resistance to pitting, cavernous or cracks corrosion. Nevertheless, all the nickel base alloys are not equivalent. Some differences exit between all the families (Ni, Ni-Cu, Ni-Cr-Fe, Ni-Cr-Fe-Mo/W-Cu, Ni-Cr-Mo/W, Ni-Mo). Cobalt base alloys in corrosive conditions are generally used for its wear and cracks resistance, with a compromise to its localised corrosion resistance properties. The choice must be done from the perfect knowledge of the corrosive medium and of the alloys characteristics (chemical, metallurgical). A synthesis of the corrosion resistance in three medium (6% FeCl 3 , 4% NaCl + 1% HCl + 0.1% Fe 2 (SO 4 ) 3 , 11.5% H 2 SO 4 + 1.2% HCl + 1% Fe 2 (SO 4 ) 3 + 1% CuCl 2 ) is presented. (A.B.). 11 refs., 1 fig., 12 tabs

  8. Hot corrosion behavior of Ni-Cr-W-C alloys in impure He gas

    International Nuclear Information System (INIS)

    Ohmura, Taizo; Sahira, Kensho; Sakonooka, Akihiko; Yonezawa, Noboru

    1977-01-01

    Influence of the minor alloy constituents such as Al, Mn and Si on the hot corrosion behavior of Ni-20Cr-20W-0.07C alloy was studied in 99.995%He gas at 1,000 0 C, in comparison with the behavior of commercial Ni-base superalloys (Hastelloy X and Inconel 617). The low oxidizing potential in the impure He gas usually causes selective oxidation of the elements described above and the growth of oxide whiskers on the surface of specimen at elevated temperatures. The intergranular attack was caused by selective oxidation of Al, Si and Mn. The spalling of oxide film was restrained by additions of Mn and Si, providing tough spinel type oxide film on the surface and 'keys' on the oxide-matrix interface respectively. The amount and morphology of the oxide whiskers depended on Si and Mn contents. Si of more than 0.29% without Mn always caused the growth of rather thinner whiskers with smooth surface, and the whiskers analyzed by electron diffraction patterns and EPMA to be Cr 2 O 3 containing Si. Mn addition changes the whiskers to thicker ones of spinel type oxide (MnCr 2 O 4 ) with rough surface. On the basis of these results, the optimum contents of Al, Mn and Si to minimize the growth of whiskers, the intergranular attack, and the spalling of oxide film were discussed. (auth.)

  9. Long-term creep rupture strength of weldment of Fe-Ni based alloy as candidate tube and pipe for advanced USC boilers

    Energy Technology Data Exchange (ETDEWEB)

    Bao, Gang; Sato, Takashi [Babcok-Hitachi K.K., Hiroshima (Japan). Kure Research Laboratory; Marumoto, Yoshihide [Babcok-Hitachi K.K., Hiroshima (Japan). Kure Div.

    2010-07-01

    A lot of works have been going to develop 700C USC power plant in Europe and Japan. High strength Ni based alloys such as Alloy 617, Alloy 740 and Alloy 263 were the candidates for boiler tube and pipe in Europe, and Fe-Ni based alloy HR6W (45Ni-24Fe-23Cr-7W-Ti) is also a candidate for tube and pipe in Japan. One of the Key issues to achieve 700 C boilers is the welding process of these alloys. Authors investigated the weldability and the long-term creep rupture strength of HR6W tube. The weldments were investigated metallurgically to find proper welding procedure and creep rupture tests are ongoing exceed 38,000 hours. The long-term creep rupture strengths of the HST weld joints are similar to those of parent metals and integrity of the weldments was confirmed based on with other mechanical testing results. (orig.)

  10. High thermal stability in W/MgO/CoFeB/W/CoFeB/W stacks via ultrathin W insertion with perpendicular magnetic anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yi; Yu, Tao [School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191 (China); Zhu, Zhengyong; Zhong, Huicai [Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029 (China); Khamis, Khamis Masoud [School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191 (China); Zhu, Kaigui, E-mail: kgzhu@buaa.edu.cn [School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191 (China); Key Laboratory of Micro-Nano Measurement-Manipulation and Physics, Ministry of Education, Beihang University, Beijing 100191 (China)

    2016-07-15

    The perpendicular magnetic anisotropy (PMA) of a series of top MgO/CoFeB/W stacks were studied. In these stacks, the thickness of CoFeB is limited in a range of 1.1–2.2 nm. It was found that the stack can still maintain PMA in a 1.9 nm thick CoFeB free layer. Besides, we investigated the thermal stability factor ∆ of a spin transfer torque magnetic random access memory (STT-MRAM) by inserting an ultra-thin W film of 0.8 nm between two CoFeB films. The result shows a clear PMA behavior for the samples with CoFeB thickness up to 2.5 nm, and an in-plane magnetic anisotropy (IMA) when the CoFeB is thicker than 2.5 nm. Moreover, the thermal stability factor ∆ of the CoFeB stack with W insertion is about 132 for a 50 nm size STT-MRAM device, which is remarkably improved compared to 112 for a sample without W insertion. Our results represent an alternative way to realize the endurance at high annealing temperature, high-density and high ∆ in STT-MRAM device by ultra-thin W insertion. - Highlights: • The MgO/CoFeB/W multilayer can still maintain PMA in a CoFeB thickness of 1.9 nm. • The sample with 2.5 nm thickness of CoFeB by W insertion can still maintain PMA. • The sample with W insertion can still maintain PMA until the annealing temperature as high as 350 °C. • The thermal stability factor ∆ of sample with W insertion could be increase to about 132 for a 50 nm size STT-MRAM device.

  11. Optimizing Heat Treatment Process of Fe-13Cr-3Mo-3Ni Martensitic Stainless of Steel

    Science.gov (United States)

    Anwar, M. S.; Prifiharni, S.; Mabruri, E.

    2017-05-01

    The Fe-13Cr-3Mo-3Ni stainless steels are modified into martensitic stainless steels for steam turbine blades application. The working temperature of steam turbine was around 600 - 700 °C. The improvement properties of turbine blade material is necessary to maintain steam turbine work. The previous research revealed that it has corrosion resistance of Fe-13Cr-3Mo-3Ni which is better than 13Cr stainless steels in the chloride environment. In this work, the effect of heat treatment on microstructure and hardness of Fe-13Cr-3Mo-3Ni stainless steels has been studied. The steel was prepared by induction melting followed by hot forging. The steels were austenitized at 1000, 1050, and 1100 °C for 1 hour and were tempered at 600, 650, and 700 °C for 1 hour. The steels were then subjected to metallographic observation and hardness test of Rockwell C. The optimal heat treatment of Fe-13Cr-3Mo-3Ni was carried out austenitized in 1050 °C and tempered in 600 - 700 °C.

  12. Corrosion effect on the electrochemical properties of LaNi3.55Mn0.4Al0.3Co0.75 and LaNi3.55Mn0.4Al0.3Fe0.75 negative electrodes used in Ni-MH batteries

    International Nuclear Information System (INIS)

    Khaldi, Chokri; Boussami, Sami; Rejeb, Borhene Ben; Mathlouthi, Hamadi; Lamloumi, Jilani

    2010-01-01

    The thermodynamic parameters, electrochemical capacity, equilibrium potential and the equilibrium pressure, of LaNi 3.55 Mn 0.4 Al 0.3 Co 0.75 and LaNi 3.55 Mn 0.4 Al 0.3 Fe 0.75 alloys have been evaluated from the electrochemical isotherms (C/30 and OCV methods) and CV technique. A comparative study has been done between the parameter values deduced from the electrochemical methods and the solid-gas method. The parameter values deduced from the electrochemical methods are influenced by the electrochemical corrosion of the alloys in aqueous KOH electrolyte. The corrosion behaviour of the LaNi 3.55 Mn 0.4 Al 0.3 Co 0.75 and LaNi 3.55 Mn 0.4 Al 0.3 Fe 0.75 electrodes after activation was investigated using the method of the potentiodynamic polarization. The variation of current and potential corrosion values with the state of charge (SOC) show that the substitution of cobalt by iron accentuates the corrosion process. The high-rate dischargeability (HRD) of the LaNi 3.55 Mn 0.4 Al 0.3 Co 0.75 and LaNi 3.55 Mn 0.4 Al 0.3 Fe 0.75 alloys was examined. By increasing the discharge current the (HRD) decrease linearly for both the alloys and for the LaNi 3.55 Mn 0.4 Al 0.3 Fe 0.75 compound is greater then for the LaNi 3.55 Mn 0.4 Al 0.3 Co 0.75 one.

  13. Investigation of phenomena brought about by hydrogen using image analysis methods in relationship with microstructure and failure morphology of A508.3 and Z2 CND 22 05 steels and of Fe-Ni alloy

    International Nuclear Information System (INIS)

    Sozanska, Maria

    1997-01-01

    This research thesis report the study, by means of image analysis methods, of phenomena brought about by the hydrogenation of metals. Three materials have been studied: an austeno-ferritic duplex steel (Z2 CND 22 05) which is often used in severe conditions in the oil industry, a bainitic steel (A 508.3) which is used in severe conditions in nuclear plants, and the Fe31pcNi alloy. For the first one, the author characterized the microstructure in relationship with yield strength, and the recovery of mechanical properties with a decrease of hydrogen quantity after thermal treatment and through a detailed examination of the fracture surface. For the second one, the fracture surface has been examined after tensile tests at different temperatures (from -196 to 20 C), and profile parameters obtained with image analysis methods have been correlated with mechanical properties. For the Fe-Ni alloy, image analysis methods have been used to track the variations of the martensitic transformation with or without hydrogen. Martensite morphology has been studied

  14. Stress corrosion cracking of nickel alloys in bicarbonate and chloride solutions

    International Nuclear Information System (INIS)

    Ares, A. E.; Carranza, R. M.; Giordano, C. M.; Zadorozne, N. S.; Rebak, R.B.

    2013-01-01

    Alloy 22 is one of the candidates for the manufacture of high level radioactive waste containers. These containers provide services in natural environments characterized by multi-ionics solutions, it is estimated they could suffer three types of deterioration: general corrosion, localized corrosion (crevice corrosion) and stress corrosion cracking (SCC). It has been confirmed that the presence of bicarbonate at temperatures above 60°C and applied potentials around +400 mVSCE are necessary in order to produce cracking, . This susceptibility may be associated to the instability of the passive film formed and to the formation of an anodic current peak in the polarization curves in these media. Until now, it is unclear the role played by each alloying element (Ni, Cr or Mo) in the SCC susceptibility of Alloy 22 in these media The aim of this work is to evaluate the SCC susceptibility of nickel-based alloys in media containing bicarbonate and chloride ions, at high temperature. Slow Strain Rate Testing (SSRT) was conducted to samples of different alloys: 22 (Ni-Cr-Mo), 600 (Ni-Cr-Fe), 800H (Ni-Fe-Cr) y 201 (99.5% Ni).This tests were conducted in 1.1 mol/L NaHCO 3 +1.5 mol/L NaCl a 90°C and different applied potentials (+200mVSCE,+300 mVSCE, +400 mVSCE). These results were complemented with those obtained in a previous work, where we studied the anodic electrochemical behavior of nickel base alloys under the same conditions. It was found that alloy 22 showed a current peak in a potential range between +200 mVSCE and +300 mVSCE when immersed in bicarbonate ions containing solutions. This peak was attributed to the presence of chromium in the alloys. The SSRT showed that only alloy 22 has a clear indication of stress corrosion cracking. The current results suggested that the presence of an anodic peak in the polarization curves was not a sufficient condition for cracking. (author)

  15. Effect of Nb and Cr incorporation on the structural and magnetic properties of rapidly quenched FeCoSiB microwires

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, Partha; Roy, R.K.; Mitra, A. [NDE and Magnetic Materials Group, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Panda, A.K., E-mail: akpanda@nmlindia.org [NDE and Magnetic Materials Group, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Churyukanova, Margarita; Kaloshkin, Sergey [National University of Science and Technology, MISIS, Leninsky Prospect, 4, Moscow 119049 (Russian Federation)

    2012-08-15

    Rapidly quenched microwires with a nominal composition of Fe{sub 39}Co{sub 39}Si{sub 8}B{sub 14} (A{sub O}), Fe{sub 37}Co{sub 37}Nb{sub 4}Si{sub 8}B{sub 14} (A{sub N}) and Fe{sub 36}Co{sub 36}Nb{sub 4}Cr{sub 2}Si{sub 8}B{sub 14} (A{sub NC}) have been investigated. Devitrification of as-quenched microwires showed that crystallization temperatures increased with simultaneous incorporation of Nb and Cr as in A{sub NC} alloy. Addition of these elements also contributed to an increase in activation energy in A{sub N} and A{sub NC} alloys. Nb addition reduced the particle size, which became much finer in the case of the Cr-containing alloy. Although Nb addition did not have much effect on lowering the Curie temperature T{sub C} of the amorphous phase, Cr substitution lowered T{sub C} to 698 K from high values of 785 K and 787 K observed in the no. A{sub O} and A{sub NC} alloys, respectively. However, the Cr addition revealed a better Giant magneto-impedance (GMI) response compared to the other alloys. Such improved GMI properties in the Cr-containing alloy are attributed to lower values of the coercivity and magnetostriction in the alloy containing both Nb and Cr. - Highlights: Black-Right-Pointing-Pointer FeCoSiB based rapidly quenched microwires prepared by in-rotating-water quenching system. Black-Right-Pointing-Pointer Effect of Nb and Cr on the thermal and GMI behavior of FeCoSiB microwires has been investigated. Black-Right-Pointing-Pointer Effect of Nb and Cr on magnetic properties has also been investigated.

  16. Thermomechanical behavior of Fe-Mn-Si-Cr-Ni shape memory alloys modified with samarium

    International Nuclear Information System (INIS)

    Shakoor, R.A.; Khalid, F. Ahmad

    2009-01-01

    The deformation and training behavior of Fe-14Mn-3Si-10Cr-5Ni (wt.%) shape memory alloys containing samarium addition has been studied in the iron-based shape memory alloys. It is noticed that thermomechanical treatment (training) has significant influence on proof stress, critical stress and shape memory behavior of the alloys. The improvement in shape memory behavior can be attributed to the decrease in the proof stress and critical stress which facilitates the formation of ε (hcp martensite). It is also observed that alloy 2 containing samarium undergoes less softening as compared to alloy 1 with training which inhibits the formation of α (bcc martensite) and thus enhances the shape memory behavior. The excessive thermomechanical treatment with increase in the training cycle has led to the formation of α (bcc martensite) along with ε (hcp martensite) in the alloy 1 which appeared to have decline in the shape memory effect. This has been demonstrated by the examination of microstructure and identification of α (bcc martensite) martensite in the alloy 1 as compared to alloy 2

  17. Coercivity and nanostructure of melt-spun Ti-Fe-Co-B-based alloys

    Directory of Open Access Journals (Sweden)

    W. Y. Zhang

    2016-05-01

    Full Text Available Nanocrystalline Ti-Fe-Co-B-based alloys, prepared by melt spinning and subsequent annealing, have been characterized structurally and magnetically. X-ray diffraction and thermomagnetic measurements show that the ribbons consist of tetragonal Ti3(Fe,Co5B2, FeCo-rich bcc, and NiAl-rich L21 phases; Ti3(Fe,Co5B2, is a new substitutional alloy series whose end members Ti3Co5B2 and Ti3Fe5B2 have never been investigated magnetically and may not even exist, respectively. Two compositions are considered, namely Ti11+xFe37.5-0.5xCo37.5−0.5xB14 (x = 0, 4 and alnico-like Ti11Fe26Co26Ni10Al11Cu2B14, the latter also containing an L21-type alloy. The volume fraction of the Ti3(Fe,Co5B2 phase increases with x, which leads to a coercivity increase from 221 Oe for x = 0 to 452 Oe for x = 4. Since the grains are nearly equiaxed, there is little or no shape anisotropy, and the coercivity is largely due to the magnetocrystalline anisotropy of the tetragonal Ti3(Fe,Co5B2 phase. The alloy containing Ni, Al, and Cu exhibits a magnetization of 10.6 kG and a remanence ratio of 0.59. Our results indicate that magnetocrystalline anisotropy can be introduced in alnico-like magnets, adding to shape anisotropy that may be induced by field annealing.

  18. Structure-phase transformations in 36NXTYu highly deformed alloy during aging

    International Nuclear Information System (INIS)

    Plotnikov, S.V.; Radashin, M.V.; Alontseva, D.L.

    2001-01-01

    The 36NXTYu alloy - containing 35.39% Ni, 12.43% Cr, 3.08% Ti, 1.22% Al, 0.93% Mn, 0.36% Si, 0.09% Cu , 0.03% C, 0.12% P, 0.09% S and the rest iron - has been examined. Under aging beginning in the alloy the Ni 3 (Al,Yi) type metastable γ'-phase release of with L12 structure is taking place, and then the stable η-phase (Ni 3 Ti, DO 24 ) is occurring. The thin foils structure and micro-diffraction analysis were observed with help of the electron microscope. Fractography has been watched on the scanning electron microscope. For study both phase content and samples texture the DRON-3 diffractometer was applied. The mechanical testing include one-axis static expansion with measurement of a strength limit, conventional fluidity limit, relational extension up to sample breakage. It is shown, that rolling deep levels in the 36NXTYu alloy, in the common case, do not change the structure-phase transformation morphology, but instead of γ'-phase the η-phase is discretely releasing

  19. Ion backscattering, channeling and nuclear reaction analysis study of passive films formed on FeCrNi and FeCrNiMo (100) single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, C; Schmaus, D [Paris-7 Univ., 75 (France). Groupe de Physique des Solides de l' ENS; Elbiache, A; Marcus, P [Ecole Nationale Superieure de Chimie, 75 - Paris (France)

    1990-01-01

    The compositions of passive films formed on Fe-17Fr-13Ni (at. %) and Fe-18.5Cr-14Ni-1.5Mo (100) single crystals have been determined and the structure of the alloy under the film has been investigated. The alloys were passivated in 0.05M H{sub 2}SO{sub 4} at 250 mV/SHE for 30 min. The oxygen content was measured by nuclear microanalysis using the {sup 16}O(d,p) {sup 17}O* reaction. The oxygen content in the passive film is similar for the two alloys and equal to (12{plus minus}2) 10{sup 15} O/cm{sup 2}. The cationic compositions of the passive films have been determined by {sup 4}He channeling at two incident beam energies: 0.8 and 2.0 MeV. For the two alloys studied, a total cation content of (5{plus minus}2)10{sup 15} at/cm{sup 2} is found in the passive films. The corresponding thickness is about 12 A. There is an excess of oxygen, which can be attributed to the presence of hydroxyls and sulfate. A strong chromium enrichment is found in the passive film formed on both alloys: chromium represents about 50% of the cations. There is no evidence of molybdenum enrichment in the passive film formed on the Mo-alloyed stainless steel. The comparison of the results obtained at the two different incident beam energies (0.8MeV and 2MeV) reveals the existence of defects at the alloy/passive film interface. (author).

  20. Microstructure And Functional Properties Of Prosthetic Cobalt Alloys CoCrW

    Directory of Open Access Journals (Sweden)

    Nadolski M.

    2015-09-01

    Full Text Available The material subject to investigation was two commercial alloys of cobalt CoCrW (No. 27 and 28 used in prosthodontics. The scope of research included performing an analysis of microstructure and functional properties (microhardness, wear resistance and corrosion resistance, as well as dilatometric tests. The examined alloys were characterized by diverse properties, which was considerably influenced by the morphology of precipitates in these materials. Alloy No. 27 has a higher corrosion resistance, whereas alloy No. 28 shows higher microhardness, better wear resistance and higher coefficient of linear expansion. Lower value of the expansion coefficient indicates less probability of initiation of a crack in the facing ceramic material.

  1. Martensitic transformation and mechanical properties of Ni{sub 49+x}Mn{sub 36–x}In{sub 15} (x=0, 0.5, 1.0, 1.5 and 2.0) alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Le; Mehta, Abhishek [Department of Materials Science and Engineering and Advanced Materials Processing and Analysis Center, University of Central Florida, Orlando, FL, 32816 (United States); Giri, Anit [TKC Global, 13873 Park Center Road, Herndon, VA 20171 (United States); Weapons and Materials Research Directorate, US Army Research Laboratory, Aberdeen Proving Ground, MD 21005 (United States); Cho, Kyu [Weapons and Materials Research Directorate, US Army Research Laboratory, Aberdeen Proving Ground, MD 21005 (United States); Sohn, Yongho, E-mail: Yongho.Sohn@ucf.edu [Department of Materials Science and Engineering and Advanced Materials Processing and Analysis Center, University of Central Florida, Orlando, FL, 32816 (United States)

    2015-10-14

    Five polycrystalline Ni{sub 49+x}Mn{sub 36–x}In{sub 15} (x=0, 0.5, 1.0, 1.5 and 2) alloys were prepared by triple arc-melting and examined to understand their martensitic transformation and mechanical properties. Martensitic transformation temperatures were determined by differential scanning calorimetry (DSC) and observed to increase with increasing Ni content. Powder X-ray diffraction (XRD) and transmission electron microscopy (TEM) showed that Ni{sub 49}Mn{sub 36}In{sub 15} is austenitic at room temperature while modulated 7M martensitic structure was observed in other alloys. Different twinning relationships between martensitic variants were revealed by TEM. Reduced elastic modulus and hardness were measured by nanoindentation. For the martensites, the reduced elastic modulus increased as the e/a increases, while hardness did not vary. The austenitic phase exhibited a lower reduced elastic modulus and hardness. A larger scatter in the reduced elastic modulus and hardness was observed for the martensitic phase in conjunction with variants of different orientation. The martensitic transformation behavior and nanoindentation results were also compared with Ni{sub 53+x}Mn{sub 22–x}Ga{sub 25} (x=0.5, 1.0, 1.8 and 2.5) alloys. For both Ni–Mn–In and Ni–Mn–Ga alloys, the martensitic transformation temperature and reduced elastic modulus increased as the e/a ratio increased.

  2. Study crevice corrosion alloys C-22 and 625 by electrochemical noise

    International Nuclear Information System (INIS)

    Ungaro, María L.; Carranza, Ricardo M.; Rodríguez, Martín A.

    2013-01-01

    C-22 and 625 alloys are two of the NiCr-Mo alloys considered as candidate materials to form the corrosion resistance engineered barriers for nuclear waste repositories. The corrosion resistance of these alloys is remarkable in a wide variety of environments. Despite of their resistance these alloys are susceptible to crevice corrosion in a certain aggressive environments. This work presents the use of electrochemical noise technique to study crevice corrosion susceptibility of alloys C-22 and 625 in 1M NaCl acidic solutions at 60ºC and 90ºC. Asymmetrical electrodes and a complementary platinum electrode were used to assess the influence of cathodic reaction in crevice process. The obtained records were analyzed directly and through statistical parameters. The potential drop and the simultaneous increment of the current records indicated the occurrence of crevice corrosion. The alternative use of a platinum electrode resulted in higher currents and higher potentials and reduced the induction time to crevice formation. The reason for this behavior is that platinum surface allows faster cathodic reactions than C-22 and 625 alloys. The standard deviation of the current records was responsive to the crevice corrosion intensity. C-22 alloy had better crevice corrosion performance than 625 alloy. (author)

  3. Fabrication of metallic alloy powder (Ni{sub 3}Fe) from Fe–77Ni scrap

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Inseok [ES Materials Research Center, Research Institute of Industrial Science and Technology, Incheon 406-840 (Korea, Republic of); Shin, Shun-Myung [Extractive Metallurgy Department, Korea Institute of Geoscience and Mineral Resources, Deajeon 305-350 (Korea, Republic of); Ha, Sang-An [Department of Environmental Engineering, Silla University, Busan 46958 (Korea, Republic of); Wang, Jei-Pil, E-mail: jpwang@pknu.ac.kr [Department of Metallurgical Engineering, Pukyong National University, Busan 608-739 (Korea, Republic of)

    2016-06-15

    The oxidation behavior of Fe–77Ni alloy scrap was investigated at an oxygen partial pressure of 0.2 atm and temperatures ranging from 400 °C to 900 °C. The corresponding oxidation rate increased with increasing temperature and obeyed the parabolic rate law, as evidenced by its linear proportionality to the temperature. In addition, surface morphologies, cross-sectional views, compositions, structural properties were examined by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). Diffusion through either the spinel structure or the NiO layer, which were both present in the alloy during oxidation at elevated temperatures, was deemed the rate-limiting step of the reaction. The oxide powder less than 10 μm was obtained from Fe–77Ni alloy scrap was obtained using ball-milling and sieving processes. In fact, 15 h of milling yielded a recovery ratio of 97%. Using hydrogen gas, the oxide powder was successfully reduced to an alloy powder of Ni{sub 3}Fe and reduction rates of ∼97% were achieved after 3 h at 1000 °C. - Highlights: • The oxidation behavior of Fe–77Ni alloy scrap was investigated. • The oxide powder less than 10 μm was obtained from Fe–77Ni alloy scrap. • Using hydrogen gas, the oxide powder was successfully reclaimed. • Reduction rates of ∼97% were achieved after 3 h at 1000 °C.

  4. Effect of Ni Addition on the Wear and Corrosion Resistance of Fe-20Cr-1.7C-1Si Hardfacing Alloy

    International Nuclear Information System (INIS)

    Lee, Sung Hoon; Kim, Ki Nam; Kim, Seon Jin

    2011-01-01

    In order to improve the corrosion resistance of Fe-20Cr-1.7C-1Si hardfacing alloy without a loss of wear resistance, the effect of Ni addition was investigated. As expected, the corrosion resistance of the alloy increased with increasing Ni concentration. The wear resistance of the alloy did not decrease, even though the hardness decreased, up to Ni concentration of 5 wt.%. This was attributed to the fact that the decrease in hardness was counterbalanced by the strain-induced martensitic transformation. The wear resistance of the alloy, however, decreased abruptly with increases of the Ni concentration over 5 wt.%.

  5. Homoleptic diphosphacyclobutadiene complexes [M(η(4)-P2C2R2)2]x- (M = Fe, Co; x = 0, 1).

    Science.gov (United States)

    Wolf, Robert; Ehlers, Andreas W; Khusniyarov, Marat M; Hartl, František; de Bruin, Bas; Long, Gary J; Grandjean, Fernande; Schappacher, Falko M; Pöttgen, Rainer; Slootweg, J Chris; Lutz, Martin; Spek, Anthony L; Lammertsma, Koop

    2010-12-27

    The preparation and comprehensive characterization of a series of homoleptic sandwich complexes containing diphosphacyclobutadiene ligands are reported. Compounds [K([18]crown-6)(thf)(2)][Fe(η(4)-P(2)C(2)tBu(2))(2)] (K1), [K([18]crown-6)(thf)(2)][Co(η(4)-P(2)C(2)tBu(2))(2)] (K2), and [K([18]crown-6)(thf)(2)][Co(η(4)-P(2)C(2)Ad(2))(2)] (K3, Ad = adamantyl) were obtained from reactions of [K([18]crown-6)(thf)(2)][M(η(4)-C(14)H(10))(2)] (M = Fe, Co) with tBuC[triple bond]P (1, 2), or with AdC[triple bond]P (3). Neutral sandwiches [M(η(4)-P(2)C(2)tBu(2))(2)] (4: M = Fe 5: M = Co) were obtained by oxidizing 1 and 2 with [Cp(2)Fe]PF(6). Cyclic voltammetry and spectro-electrochemistry indicate that the two [M(η(4)-P(2)C(2)tBu(2))(2)](-)/[M(η(4)-P(2)C(2)tBu(2))(2)] moieties can be reversibly interconverted by one electron oxidation and reduction, respectively. Complexes 1-5 were characterized by multinuclear NMR, EPR (1 and 5), UV/Vis, and Mössbauer spectroscopies (1 and 4), mass spectrometry (4 and 5), and microanalysis (1-3). The molecular structures of 1-5 were determined by using X-ray crystallography. Essentially D(2d)-symmetric structures were found for all five complexes, which show the two 1,3-diphosphacyclobutadiene rings in a staggered orientation. Density functional theory calculations revealed the importance of covalent metal-ligand π bonding in 1-5. Possible oxidation state assignments for the metal ions are discussed.

  6. Atomic-scale properties of Ni-based FCC ternary, and quaternary alloys

    International Nuclear Information System (INIS)

    Tamm, Artur; Aabloo, Alvo; Klintenberg, Mattias; Stocks, Malcolm; Caro, Alfredo

    2015-01-01

    The aim of this study is to characterize some atomic-scale properties of Ni-based FCC multicomponent alloys. For this purpose, we use Monte Carlo method combined with density functional theory calculations to study short-range order (SRO), atomic displacements, electronic density of states, and magnetic moments in equimolar ternary NiCrCo, and quaternary NiCrCoFe alloys. According to our study, the salient features for the ternary alloy are a negative SRO parameter between Ni–Cr and a positive between Cr–Cr pairs as well as a weakly magnetic state. For the quaternary alloy we predict negative SRO parameter for Ni–Cr and Ni–Fe pairs and positive for Cr–Cr and Fe–Fe pairs. Atomic displacements for both ternary and quaternary alloys are negligible. In contrast to the ternary, the quaternary alloy shows a complex magnetic structure. The electronic structure of the ternary and quaternary alloys shows differences near the Fermi energy between a random solid solution and the predicted structure with SRO. Despite that, the calculated EXAFS spectra does not show enough contrast to discriminate between random and ordered structures. The predicted SRO has an impact on point-defect energetics, electron–phonon coupling and thermodynamic functions and thus, SRO should not be neglected when studying properties of these two alloys

  7. Solidification characteristics and segregation behavior of a P-containing Ni-Fe-Cr-based alloy

    Science.gov (United States)

    Wang, Changshuai; Su, Haijun; Guo, YongAn; Guo, Jianting; Zhou, Lanzhang

    2017-09-01

    Solidification characteristics and segregation behavior of a P-containing Ni-Fe-Cr-based alloy, considered as boiler and turbine materials in 700 °C advanced ultra-supercritical coal-fired power plants, have been investigated by differential thermal analysis and directional solidification quenching technique. Results reveal that P decreases the solidus temperature, but only has negligible influence on liquidus temperature. After P was added, the solidification sequence has no apparent change, but the width of the mushy zone increases and dendritic structures become coarser. Moreover, P increases the amount and changes the morphology of MC carbide. Energy-dispersive spectroscopy analysis reveals that P has obvious influence on the segregation behavior of the constitute elements with equilibrium partition coefficients (ki) far away from unity, whereas has negligible effect on the constituent elements with ki close to unity and has more influence on the final stage of solidification than at early stage. The distribution profiles reveal that P atoms pile up ahead of the solid/liquid (S/L) interface and strongly segregate to the interdendritic liquid region. The influence of P on solidification characteristics and segregation behavior of Ni-Fe-Cr-based alloy could be attributed to the accumulation of P ahead of the S/L interface during solidification.

  8. High-Strength Ultra-Fine-Grained Hypereutectic Al-Si-Fe-X (X = Cr, Mn) Alloys Prepared by Short-Term Mechanical Alloying and Spark Plasma Sintering.

    Science.gov (United States)

    Průša, Filip; Bláhová, Markéta; Vojtěch, Dalibor; Kučera, Vojtěch; Bernatiková, Adriana; Kubatík, Tomáš František; Michalcová, Alena

    2016-11-30

    In this work, Al-20Si-10Fe-6Cr and Al-20Si-10Fe-6Mn (wt %) alloys were prepared by a combination of short-term mechanical alloying and spark plasma sintering. The microstructure was composed of homogeneously dispersed intermetallic particles forming composite-like structures. X-ray diffraction analysis and TEM + EDS analysis determined that the α-Al along with α-Al 15 (Fe,Cr)₃Si₂ or α-Al 15 (Fe,Mn)₃Si₂ phases were present, with dimensions below 130 nm. The highest hardness of 380 ± 7 HV5 was observed for the Al-20Si-10Fe-6Mn alloy, exceeding the hardness of the reference as-cast Al-12Si-1Cu-1 Mg-1Ni alloy (121 ± 2 HV5) by nearly a factor of three. Both of the prepared alloys showed exceptional thermal stability with the hardness remaining almost the same even after 100 h of annealing at 400 °C. Additionally, the compressive strengths of the Al-20Si-10Fe-6Cr and Al-20Si-10Fe-6Mn alloys reached 869 MPa and 887 MPa, respectively, and had virtually the same values of 870 MPa and 865 MPa, respectively, even after 100 h of annealing. More importantly, the alloys showed an increase in ductility at 400 °C, reaching several tens of percent. Thus, both of the investigated alloys showed better mechanical properties, including superior hardness, compressive strength and thermal stability, as compared to the reference Al-10Si-1Cu-1Mg-1Ni alloy, which softened remarkably, reducing its hardness by almost 50% to 63 ± 8 HV5.

  9. On the kinetic and thermodynamic fragility of the Pt{sub 60}Cu{sub 16}Co{sub 2}P{sub 22} and Pt{sub 57.3}Cu{sub 14.6}Ni{sub 5.3}P{sub 22.8} bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Gallino, Isabella, E-mail: i.gallino@mx.uni-saarland.de [Saarland University, Department of Materials Science and Engineering, Campus C6.3, 66123 Saarbruecken (Germany); Gross, Oliver [Saarland University, Department of Materials Science and Engineering, Campus C6.3, 66123 Saarbruecken (Germany); Dalla Fontana, Giulia [Department of Chemistry IFM and NIS, University of Torino, V. Giuria 7, 10125 Torino (Italy); Evenson, Zach; Busch, Ralf [Saarland University, Department of Materials Science and Engineering, Campus C6.3, 66123 Saarbruecken (Germany)

    2014-12-05

    Highlights: • The studied Pt–Cu–(Ni,Co)–P glasses are more fragile than Zr-based alloys. • They show large increases in the C{sub p} at T{sub g} and small barriers for cooperative rearrangements of atoms. • They have fragility parameters among the lowest reported for BMG systems (D{sup *} = 10–12). • They crystallize into a state that melts with distinctly high entropy of fusion. • The microscopic origin of their fragility seems different than that for Zr- and Pd-based BMGs. - Abstract: The investigations in this study focus on bulk metallic glass (BMG) alloy families based on noble metals like Pt, which are more kinetically fragile than Zr-based BMG systems. Thermophysical properties have been investigated by calorimetry and thermal mechanical analyses for the determination of the specific heat capacity and viscosity, respectively. For the Pt{sub 60}Cu{sub 16}Co{sub 2}P{sub 22} and Pt{sub 57.3}Cu{sub 14.6}Ni{sub 5.3}P{sub 22.8} BMG compositions consistent Vogel–Fulcher–Tammann (VFT) fits of the viscosity measurements are established, and the temperature dependence of the configurational entropy is calculated from thermodynamic data. Fits to the Adam–Gibbs equation are performed using this configurational entropy change. Their fragile nature is compared to that of Zr-based alloys in terms of structural considerations.

  10. Influence of a niobium coating on sulfidation resistance of FeCr and FeCrY alloys; Influencia de um revestimento de niobio sobre a resistencia a sulfetacao das ligas FeCr e FeCrY

    Energy Technology Data Exchange (ETDEWEB)

    Geribola, Gulherme Altomari

    2014-07-01

    Niobium and niobium based alloys are currently used in many industrial applications because they offer excellent resistance to degradation in various corrosive environments. These media include gaseous atmospheres at high temperatures such as those found in existing coal gasifying plants in power plants for energy generation. These atmospheres are complex gas mixtures that contain sulfur and oxygen, among other compounds. Sulphides are thermodynamically less stable, have lower melting points and often have larger deviations from stoichiometry compared to the corresponding oxides. Although there are studies regarding the use of refractory metals in high temperature sulphidizing atmospheres, the use of niobium compounds has not been adequately evaluated and there is very little studies available in the literature about its use as a protective coating. The aim of this study was to evaluate the effect of a niobium film, deposited by magnetron sputtering on the isothermal sulphidation behavior of Fe-20Cr and Fe-20Cr-1Y alloys. The sulphidation tests were carried out at 500, 600 and 700 deg C for 2h in H{sub 2}/2% H2S atmosphere. The sulphidation resistance was determined by mass gain per unit area. The sulphidation behavior of the coated and uncoated alloys was similar at 500 deg C, and none of the alloys scaled. At 700 deg C FeCr alloy scaled in the form of a fine powder, while the reaction product formed on the alloy FeCrY scaled in the form of plates. The effect of niobium became pronounced at 700 deg C. The reaction product layer formed on the coated alloy was thinner and more plastic than that formed on the uncoated alloy. The mass gain per unit area of the coated alloys decreased significantly and they did not scaled. (author)

  11. Magnetic characterization of nanocrystalline Fe80−xCrxCo20 (15≤x≤35) alloys during milling and subsequent annealing

    International Nuclear Information System (INIS)

    Rastabi, Reza Amini; Ghasemi, Ali; Tavoosi, Majid; Sodaee, Tahmineh

    2016-01-01

    Magnetic characterization of nanocrystalline Fe–Cr–Co alloys during milling and annealing process was the goal of this study. To formation of Fe 80−x Cr x Co 20 (15≤x≤35) solid solution, different powder mixtures of Fe, Cr and Co elements were mechanically milled in a planetary ball mill. The annealing process was done in as-milled samples at different temperature in the range of 500–640 °C for 2 h. The produced samples were characterized using X-ray diffraction, scanning electron microscopy, differential scanning calorimetry and vibrating sample magnetometer. Performed mechanical alloying in different powder mixtures lead to the formation of Fe–Cr–Co α-phase solid solution with average crystallite sizes of about 10 nm. The produced nanocrystalline alloys exhibit magnetic properties with the coercivity and saturation of magnetization in the range of 110–200 Oe and 150–220 emu/g, respectively. The coercivity of produced alloys after annealing process decreased and reached to about 40–150 Oe. The highest value of coercivity in as-milled and annealed samples was achieved in alloys with higher Cr contents. - Highlights: • Hc and Ms of produced alloys obtained in the range of 110–200 Oe and 150–220 emu/g. • The highest value of Hc in milled and annealed samples was achieved in Fe 45 Cr 35 Co 20 . • Hc of produced alloys after spinodal decomposition decreased to about 40–150 Oe. • The effect of crystalline defects and residual strain on magnetic fields pinning in milled samples is higher than spinodal decomposition in annealed samples. • The highest value of Hc in as-milled and annealed samples was achieved in Fe 45 Cr 35 Co 20 . The coercivity of produced alloys after annealing process decreased and reach to about 40–150 Oe. • The produced nanocrystalline alloys exhibit magnetic properties with the coercivity and saturation of magnetization in the range of 110–200 Oe and 150–220 emu/g, respectively.

  12. Microsegregation observed in Fe-35.5Ni-7.5Cr irradiated in EBR-II

    International Nuclear Information System (INIS)

    Brager, H.R.; Garner, F.A.

    1984-01-01

    At 593 0 C one alloy, Fe-35.5Ni-7.5Cr, which was particularly resistant to swelling in EBR-II, increased in density 0.9% at 7.6 x 10 22 n/cm 2 (E > 0.1 MeV). Examination by energy dispersive x-ray analysis revealed that substantial oscillations occur in the nickel content of the alloy, varying from 25 to 53% about the nominal level of 35.5%. These oscillations exhibit a period of approx.200 nm. Regions enriched in nickel are depleted in chromium and iron, and the reverse is true in regions of low nickel content. This spinodal-like process produces a net densification and also appears to eventually destroy the swelling resistance of the alloy. Once voids form in the nickel-poor chromium-rich regions, further segregation of nickel to void surfaces is expected to accelerate the loss of swelling resistance

  13. Cr-Ni ALLOY ELECTRODEPOSITION AND COMPARISON WITH CONVENTIONAL PURE Cr COATING TECHNIQUE

    Directory of Open Access Journals (Sweden)

    M. Moniruzzaman

    2012-12-01

    Full Text Available Cr coating is widely used as the outer surface of precision parts due to its attractive appearance and superior corrosion resistance properties. It is obtained by electrodeposition via a conventional bath with hexavalent Cr ions. This manufacturing technique has many drawbacks, such as very low efficiency and high operating temperature and it is hazardous to health. In this work, we studied a Cr-Ni alloy deposition technique and compared the alloy coating properties to those with conventional Cr coating. Sequential two-step alloy electrodeposition was also compared. We took varying concentrations of Cr, Ni and complexing agents for the electrodeposition of Cr-Ni alloy and sequential Cr-Ni alloy coating on mild steel. Operating parameters, i.e. current density and temperature, were varied to examine their effects on the coating properties. The coatings thus obtained were characterized by visual observation, corrosion test, microhardness measurement, morphology and chemical analysis. The Cr-Ni alloy coating was found to be more corrosion resistant in 5% NaCl solution and harder than the pure Cr coating obtained by conventional electrodeposition. Toxic gas was produced in a much lower extent in the alloy coating than the conventional Cr coating technique. Again, the two-step Cr-Ni alloy coating was found better in terms of corrosion resistance as well as hardness compared to the Cr-Ni alloy coating. The process was also found to be much more environmentally friendly.

  14. Microstructure and wear resistance of laser cladded Ni-Cr-Co-Ti-V high-entropy alloy coating after laser remelting processing

    Science.gov (United States)

    Cai, Zhaobing; Cui, Xiufang; Liu, Zhe; Li, Yang; Dong, Meiling; Jin, Guo

    2018-02-01

    An attempt, combined with the technologies of laser cladding and laser remelting, has been made to develop a Ni-Cr-Co-Ti-V high entropy alloy coating. The phase composition, microstructure, micro-hardness and wear resistance (rolling friction) were studied in detail. The results show that after laser remelting, the phase composition remains unchanged, that is, as-cladded coating and as-remelted coatings are all composed of (Ni, Co)Ti2 intermetallic compound, Ti-rich phase and BCC solid solution phase. However, after laser remelting, the volume fraction of Ti-rich phase increases significantly. Moreover, the micro-hardness is increased, up to ∼900 HV at the laser remelting parameters: laser power of 1 kW, laser spot diameter of 3 mm, and laser speed of 10 mm/s. Compared to the as-cladded high-entropy alloy coating, the as-remelted high-entropy alloy coatings have high friction coefficient and low wear mass loss, indicating that the wear resistance of as-remelted coatings is improved and suggesting practical applications, like coatings on brake pads for wear protection. The worn surface morphologies show that the worn mechanism of as-cladded and as-remelted high-entropy alloy coatings are adhesive wear.

  15. Effects of Fe and Cr on corrosion behavior of ZrFeCr alloys in 500 oC steam

    International Nuclear Information System (INIS)

    Wang Jun; Fan Hongyuan; Xiong Ji; Liu Hong; Miao Zhi; Ying Shihao; Yang Gang

    2011-01-01

    Research highlights: Amount and size of SPP will effect the corrosion resistance of Zr alloy at 500 o C/10.3 MPa. - Abstract: A study of the corrosion behaviors of ZrFeCr alloy and the influence of microstructure on corrosion resistance are described by X-ray diffraction and scanning electron microscope in this paper. The results show that several ZrFeCr alloys exhibit protective behavior throughout the test and oxide growth is stable and protective. The best alloy has the composition Zr1.0Fe0.6Cr. Fitting of the weight gain curves for the protective oxide alloys in the region of protective behavior, it showed nearly cubic behavior for the most protective alloys. The Zr1.0Fe0.6Cr has the more laves Zr(Fe,Cr) 2 precipitate in matrix and it has the better corrosion resistance. The Zr0.2Fe0.1Cr has little precipitate, the biggest hydrogen absorption and the worst corrosion resistance. The number of precipitates and the amount of hydrogen absorption in Zr alloy plays an important role on corrosion resistance behaviors in 500 o C/10.3 MPa steam.

  16. Fabrication of Co{sub 0.5}Ni{sub 0.5}Cr{sub x}Fe{sub 2-x}O{sub 4} materials via sol-gel method and their characterizations

    Energy Technology Data Exchange (ETDEWEB)

    Kadam, R.H.; Birajdar, A.P. [Materials Research Laboratory, Srikrishna Mahavidyalaya Gunjoti, Omerga, Osmanabad 413613, Maharashtra (India); Alone, Suresh T. [Department of Physics, RS Art' s, Science and Commerce College, Pathri, Aurangabad, Maharashtra (India); Shirsath, Sagar E., E-mail: shirsathsagar@hotmail.com [Spin Device Technology Center, Department of Information Engineering, Shinshu University, Nagano 380-8553 (Japan)

    2013-02-15

    Co{sub 0.5}Ni{sub 0.5}Cr{sub x}Fe{sub 2-x}O{sub 4} nanoparticles have been designed by the sol-gel auto combustion method, using nitrates of the respective metal ions, and citric acid as the starting materials. The process takes only a few minutes to obtain as-received Cr-substituted Co-Ni ferrite powders. X-ray diffraction (XRD), vibrational sample magnetometer (VSM), transmission electron microscopy (TEM) are utilized in order to study the effect of variation in the Cr{sup 3+} substitution and its impact on particle size, lattice constant, specific surface area, cation distribution and magnetic properties. Lattice parameter, particle size found to decrease with increasing Cr{sup 3+} content, whereas specific surface area showed increasing trend with the Cr{sup 3+} substitution. Cation distribution indicates that the Cr, Co and Ni ions show preference toward octahedral [B] site, whereas Fe occupies both tetrahedral (A) and octahedral [B] sites. Saturation magnetization (M{sub S}) decreased from 65.1 to 40.6 emu/g with the increase in Cr{sup 3+} substitution. However, Coercivity increased from 198 to 365 Oe with the Cr{sup 3+} substitution. - Highlights: Black-Right-Pointing-Pointer Cr{sup 3+} substituted Co--Ni ferrite. Black-Right-Pointing-Pointer Site occupancy of Co--Ni--Cr--Fe ions. Black-Right-Pointing-Pointer Magnetization and coercivity shows inverse trend to each other.

  17. Corrosion of high purity Fe-Cr-Ni alloys in 13 N boiling nitric acid

    International Nuclear Information System (INIS)

    Ohta, Joji; Mayuzumi, Masami; Kusanagi, Hideo; Takaku, Hiroshi

    1998-01-01

    Corrosion in boiling nitric acid was investigated for high purity Fe-18%Cr-12%Ni alloys and type 304L stainless steels (SS). Owing to very low impurity concentration, the solution treated high purity alloys show almost no intergranular corrosion while the type 304L SS show severe intergranular corrosion. Both in the high purity alloys and type 304L SS, aging treatments ranging from 873 K to 1073 K for 1 h enhance intergranular corrosion. During the aging treatments, impurities should be segregated to the grain boundaries. The corrosion behaviors were discussed from a standpoint of impurity segregation to grain boundaries. This study is of importance for purex reprocessing of spent fuels

  18. Tuning Fermi level of Cr{sub 2}CoZ (Z=Al and Si) inverse Heusler alloys via Fe-doping for maximum spin polarization

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Mukhtiyar [Department of Physics, Kurukshetra University, Kurukshetra-136119, Haryana (India); Saini, Hardev S. [Department of Physics, Panjab University, Chandigarh-160014 (India); Thakur, Jyoti [Department of Physics, Kurukshetra University, Kurukshetra-136119, Haryana (India); Reshak, Ali H. [New Technologies—Research Center, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia); Kashyap, Manish K., E-mail: manishdft@gmail.com [Department of Physics, Kurukshetra University, Kurukshetra-136119, Haryana (India)

    2014-12-15

    We report full potential treatment of electronic and magnetic properties of Cr{sub 2−x}Fe{sub x}CoZ (Z=Al, Si) Heusler alloys where x=0.0, 0.25, 0.5, 0.75 and 1.0, based on density functional theory (DFT). Both parent alloys (Cr{sub 2}CoAl and Cr{sub 2}CoSi) are not half-metallic frromagnets. The gradual replacement of one Cr sublattice with Fe induces the half-metallicity in these systems, resulting maximum spin polarization. The half-metallicity starts to appear in Cr{sub 2−x}Fe{sub x}CoAl and Cr{sub 2−x}Fe{sub x}CoSi with x=0.50 and x=0.25, respectively, and the values of minority-spin gap and half-metallic gap or spin-flip gap increase with further increase of x. These gaps are found to be maximum for x=1.0 for both cases. An excellent agreement between the structural properties of CoFeCrAl with available experimental study is obtained. The Fermi level tuning by Fe-doping makes these alloys highly spin polarized and thus these can be used as promising candidates for spin valves and magnetic tunnelling junction applications. - Highlights: • Tuning of E{sub F} in Cr{sub 2}CoZ (Z=Al, Si) has been demonstrated via Fe doping. • Effect of Fe doping on half-metallicity and magnetism have been discussed. • The new alloys have a potential of being used as spin polarized electrodes.

  19. Structural and magnetic properties of Ni{sub 78}Fe{sub 22} thin films sandwiched between low-softening-point glasses and application in spin devices

    Energy Technology Data Exchange (ETDEWEB)

    Misawa, Takahiro; Mori, Sumito [Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido 001-0020 (Japan); Komine, Takashi [Faculty of Engineering, Ibaraki University, Hitachi, Ibaraki 316-8511 (Japan); Fujioka, Masaya; Nishii, Junji [Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido 001-0020 (Japan); Kaiju, Hideo, E-mail: kaiju@es.hokudai.ac.jp [Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido 001-0020 (Japan)

    2016-12-30

    Graphical abstract: This paper presents the first demonstration of the formation of Ni{sub 78}Fe{sub 22} thin films sandwiched between low-softening-point (LSP) glasses used in spin quantum cross (SQC) devices and the theoretical prediction of spin filter effect in Ni{sub 78}Fe{sub 22}-based SQC devices. The fomation of the LSP-glass/Ni{sub 78}Fe{sub 22}/LSP-glass structures was successfully demonstrated using a newly proposed thermal pressing technique. Interestingly, this technique gives rise to both a highly-oriented crystal growth in Ni{sub 78}Fe{sub 22} thin films and a 100-fold enhancement in coercivity, in contrast to those of as-deposited Ni{sub 78}Fe{sub 22} thin films. This remarkable increase in coercivity can be explained by the calculation based on two-dimensional random anisotropy model. These excellent features on structural and magnetic properties allowed us to achieve that the stray magnetic field was uniformly generated from the Ni{sub 78}Fe{sub 22} thin-film edge in the direction perpendicular to the cross section of the LSP-glass/Ni{sub 78}Fe{sub 22}/LSP-glass structures. As we calculated the stray magnetic field generated between the two edges of Ni{sub 78}Fe{sub 22} thin-film electrodes in SQC devices, a high stray field of approximately 5 kOe was generated when the gap distance between two edges of the Ni{sub 78}Fe{sub 22} thin-film electrodes was less than 5 nm and the thickness of Ni{sub 78}Fe{sub 22} was greater than 20 nm. These experimental and calculated results suggest that Ni{sub 78}Fe{sub 22} thin films sandwiched between LSP glasses can be used as electrodes in SQC devices, providing a spin-filter effect, and also our proposed techniques utilizing magnetic thin-film edges will open up new opportunities for the creation of high performance spin devices, such as large magnetoresistance devices and nanoscale spin injectors. Our paper is of strong interest to the broad audience of Applied Surface Science, as it demonstrates that the

  20. The influence of Cr content in Fe-Cr-Co alloys on the magnetic properties and Moessbauer effect

    International Nuclear Information System (INIS)

    Yan Yong; Sho Hanru; Li Dexin; Li Guodong; Li Dongshen; Zhen Jinshan

    1986-01-01

    Fe-xCr-8Co (x=24, 25, 27, 29 and 32 wt%) permanent magnetic alloys have been studied by Moessbauer effect, magnetic balance and vibrating-sample magnetometer. It is indicated that the optimum permanent magnetic properties obtained for the composition of the alloys at about x=27. The value of Cr content in these alloys sigificantly influences the average hyperfine field, the saturation magnetic moment, the proportion of paramagnetic phase and orientation of magnetic moment in these alloys. The intrinsic coercive force is gradually reduced with the temperature decreasing from 290 to 77 K. The paramagnetic peak in the spectrum disappears at about 125 K. The certain mechanism has been suggested to explain the experimental results. (Auth.)

  1. Mechanical alloying of the FeNi-Ag system

    International Nuclear Information System (INIS)

    Gonzalez, G.; Ibarra, D.; Ochoa, J.; Villalba, R.; Sagarzazu, A.

    2007-01-01

    The Fe-Ni-Ag system is of particular interest for its potential applications as soft magnetic granular material with small magnetic grains embedded in a non-magnetic metal matrix. Under equilibrium conditions: Fe-Ag and Ni-Ag are immiscible and Fe-Ni shows complete solubility. These materials are particularly important for magnetoresistivity properties. The properties of these alloys are closely related to their microstructure; therefore, a detailed study of the transformations occurring during milling was undertaken using pre-alloyed Fe x Ni 100-x (x = 30, 50 and 70) further milled with different Ag content to give the following alloys compositions (Fe x -Ni 100-x ) 100-y Ag y (y = 5, 20, 60). Consolidation of the mechanically alloyed powders by sintering at 950 o C was performed. Morphological and structural characterization of the sintered powders was carried out by scanning and transmission electron microscopy and X-ray diffraction. Fe 30 Ni 70 and Fe 50 Ni 50 formed ordered FeNi 3 compound. Fe 70 Ni 30 showed the formation of a mixture of γ-(Fe,Ni) and α-Fe(Ni) solid solutions. The mixture of these systems with Ag showed the metal solid solutions surrounded by Ag islands of Fe x Ni y -Ag, There was also evidence of Ag diffusing into the γ-(Fe,Ni). High Ag content (60%) shows formation of islands of FeNi surrounded by Ag. Sintering is always improved with the Ag content

  2. Synthesis and characterization of the Fe-18%Ni-12%Co-4,9%Mo-1,5%Ti alloy

    International Nuclear Information System (INIS)

    Nunes, G.C.S.; Biondo, V.; Nunes, M.V.S.; Paesano Junior, A.; Sarvezuk, P.W.C.; Blanco, M.C.

    2014-01-01

    The Fe-18%Ni-12%Co-4,9%Mo-1,5%Ti was made by arc-melting and submitted to different heat treatments, for solubilization in the γ - phase (austenite), followed by cooling to the room temperature, and also for further aging. The prepared alloys were characterized by X-ray diffraction (Rietveld method) and Mössbauer spectroscopy. The results showed that the cooling induced the system to a martensitic transformation, crystallizing it into a cubic structure (martensite). The crystallographic parameters and the hyperfine parameters obtained by Mössbauer Spectroscopy are consistent with those found in literature for Maraging-350 steels. The aging treatments generates the formation of reversed austenite in relative amounts that vary with the temperature and time of treatment. (author)

  3. Creep strength and microstructure in 23Cr-45Ni-7W Alloy (HR6W) and Ni-base superalloys for advanced USC boilers

    Energy Technology Data Exchange (ETDEWEB)

    Semba, Hiroyuki; Okada, Hirokazu; Yonemura, Mitsuharu; Igarashi, Masaaki [Sumitomo metal Industries, Ltd., Hyogo (Japan). Corporate Research and Development Labs.

    2008-07-01

    Establishment of materials technologies on piping and tubing for advanced ultra super critical (A-USC) plants operated at steam temperatures above 700 C is a critical issue to achieve its hard target. 23Cr-45Ni-7W alloy (HR6W) has been developed in Japan, originally as a high strength tubing material for 650 C USC boilers. In order to clarify the capability of HR6W as a material applied to A-USC plants, creep strength and microstructure of HR6W were investigated in comparison with {gamma}'-strengthened Alloy 617 and other Ni-base superalloys, such as Alloy 263. It has been revealed that the amount of added W is intimately correlated with precipitation amount of Laves phase and thus it is a crucial factor controlling creep strength. Stability of long term creep strength and superior creep rupture ductility have been proved by creep rupture tests at 650-800 C up to 60000h. The 10{sup 5}h extrapolated creep rupture strengths are estimated to be 88MPa at 700 C and 64MPa at 750 C. Microstructural stability closely related with long term creep strength and toughness has also been confirmed by microstructural observations after creep tests and aging. Creep rupture strength of Alloy 617 has been found to be much higher than that of HR6W at 700 and 750 C, while comparable at 800 C. A thermodynamic calculation along with microstructural observation indicates that the amount of Laves phase in HR6W gradually decreases with increasing temperature, while that of {gamma}' in Alloy 617 rapidly decreases with increasing temperature and {gamma}' almost dissolves at 800 C. This may lead to an abrupt drop in creep strength of Alloy 617 above 750 C. Alloy 263, in which more {gamma}' precipitates than Alloy 617, shows much higher creep strength. However, it is suggested that inhomogeneous creep deformation is enhanced compared with HR6W and Alloy 617. Capability of HR6W as a material for A-USC plants was discussed in terms of creep properties, microstructural stability and other

  4. Precision casting of Ti-15V-3Cr-3Al-3Sn alloy setting

    OpenAIRE

    Nan Hai; Liu Changkui; Huang Dong

    2008-01-01

    In this research, Ti-15V-3Cr-3Al-3Sn alloy ingots were prepared using ceramic mold and centrifugal casting. The Ti-15V-3Cr-3Al-3Sn setting casting, for aeronautic engine, with 1.5 mm in thickness was manufactured. The alloy melting process, precision casting process, and problems in casting application were discussed. Effects of Hot Isostatic Pressing and heat treatment on the mechanical properties and microstructure of the Ti-15V-3Cr-3Al-3Sn alloy were studied.

  5. The Al Effects of Co-Free and V-Containing High-Entropy Alloys

    Directory of Open Access Journals (Sweden)

    Songqin Xia

    2017-01-01

    Full Text Available In this study, five-component high-entropy alloys (HEAs AlxCrFeNiV (where x denotes the molar ratio, x = 0, 0.1, 0.3, 0.5, 0.75, 1, and 1.5 were prepared using an arc-melting furnace. The effects of the addition of the Al on the crystal structures were investigated using X-ray diffraction (XRD, scanning electron microscopy (SEM, and transmission electron microscopy (TEM. Also, two non-equiatomic ratio HEAs, AlxCrFeNiV (x = 0.3, and 0.5, were systematically studied through the use of various characterization methods in the as-cast state. The Al0.3CrFeNiV alloy displayed typical duplex body-centered cubic (BCC structures, including disordered BCC (A2, and NiAl-type ordered BCC (B2 phases. Meanwhile, in regard to the Al0.5CrFeNiV alloy, this alloy was found to contain an unknown phase which was enriched in Cr and V, as well as the coherent A2/B2 phases. Both of these alloys displayed very high yield and fracture strengths. However, their compression fracture strains were approximately 10%. Also, the fracture surfaces showed mainly cleavage fracture modes.

  6. Connection between kinetic phenomena and atomic ordering processes and electronic structure of Ni3(FeMe)-type alloys

    International Nuclear Information System (INIS)

    Vasil'eva, R.P.; Arkhipov, Yu.N.; Narkulov, N.; Fadin, V.P.

    1978-01-01

    The results are presented of the measurements of the Hall and the Nernst-Ettingshausen effect and of thermal emf, electric resistivity and magnetization measurements in alloys Ni 3 (FeMe), where Me is Mo, Cr, W. The concentration of additions is not higher than 12.5%. The relationship of the kinetic phenomena with peculiarities of the electron structure and ordering processes is investigated. The obtained data show that the Hall and Nernst-Ettingshausen electromotive forces in the investigated alloys have positive values. The effects of the concentration variations of the investigated phenomena manifest themselves stronger in ordered state, this testifyies to a considerable increase of the part, the hole sections of the Fermi surface play. The investigation enables some conclusions to be made on the energy characteristics of these alloys as a function of the variation of the concentration composition of the alloys and the ordering processes

  7. Effects of Microalloying on the Microstructures and Mechanical Properties of Directionally Solidified Ni-33(at.%)Al-31Cr-3Mo Eutectic Alloys Investigated

    Science.gov (United States)

    Whittenberger, J. Daniel; Raj, Sai V.; Locci, Ivan E.; Salem, Jonathan A.

    2002-01-01

    Despite nickel aluminide (NiAl) alloys' attractive combination of oxidation and thermophysical properties, their development as replacements for superalloy airfoils in gas turbine engines has been largely limited by difficulties in developing alloys with an optimum combination of elevated-temperature creep resistance and room-temperature fracture toughness. Alternatively, research has focused on developing directionally solidified NiAl-based in situ eutectic composites composed of NiAl and (Cr,Mo) phases in order to obtain a desirable combination of properties a systematic investigation was undertaken at the NASA Glenn Research Center to examine the effects of small additions of 11 alloying elements (Co, Cu, Fe, Hf, Mn, Nb, Re, Si, Ta, Ti, and Zr) in amounts varying from 0.25 to 1.0 at.% on the elevated-temperature strength and room-temperature fracture toughness of directionally solidified Ni-33Al-31Cr-3Mo eutectic alloy. The alloys were grown at 12.7 mm/hr, where the unalloyed eutectic base alloy exhibited a planar eutectic microstructure. The different microstructures that formed because of these fifth-element additions are included in the table. The additions of these elements even in small amounts resulted in the formation of cellular microstructures, and in some cases, dendrites and third phases were observed. Most of these elemental additions did not improve either the elevated-temperature strength or the room-temperature fracture toughness over that of the base alloy. However, small improvements in the compression strength were observed between 1200 and 1400 K when 0.5 at.% Hf and 0.25 at.% Ti were added to the base alloy. The results of this study suggest that the microalloying of Ni-33Al-31Cr-3Mo will not significantly improve either its elevatedtemperature strength or its room-temperature fracture toughness. Thus, any improvements in these properties must be acquired by changing the processing conditions.

  8. The Synergy Effect of Ni-M (M = Mo, Fe, Co, Mn or Cr Bicomponent Catalysts on Partial Methanation Coupling with Water Gas Shift under Low H2/CO Conditions

    Directory of Open Access Journals (Sweden)

    Xinxin Dong

    2017-02-01

    Full Text Available Ni-M (M = Mo, Fe, Co, Mn or Cr bicomponent catalysts were prepared through the co-impregnation method for upgrading low H2/CO ratio biomass gas into urban gas through partial methanation coupling with water gas shift (WGS. The catalysts were characterized by N2 isothermal adsorption, X-ray diffraction (XRD, H2 temperature programmed reduction (H2-TPR, H2 temperature programmed desorption (H2-TPD, scanning electron microscopy (SEM and thermogravimetry (TG. The catalytic performances demonstrated that Mn and Cr were superior to the other three elements due to the increased fraction of reducible NiO particles, promoted dispersion of Ni nanoparticles and enhanced H2 chemisorption ability. The comparative study on Mn and Cr showed that Mn was more suitable due to its smaller carbon deposition rate and wider adaptability to various H2/CO and H2O/CO conditions, indicating its better synergy effect with Ni. A nearly 100 h, the lifetime test and start/stop cycle test further implied that 15Ni-3Mn was stable for industrial application.

  9. Oxidation behavior of NiCoCrAlY coatings deposited by double-Glow plasma alloying

    Science.gov (United States)

    Cui, Shiyu; Miao, Qiang; Liang, Wenping; Li, Baiqiang

    2018-01-01

    The NiCoCrAlY coatings were deposited on the Inconel 718 alloy substrates by a novel method called double-glow plasma alloying (DG). The phases and microstructure of the coatings were investigated by X-ray diffraction analysis while their chemical composition was analyzed using scanning electron microscopy. The morphology of the NiCoCrAlY coatings was typical of coatings formed by DG, with their structure consisting of uniform submicron-sized grains. Further, the coatings showed high adhesion strength (critical load >46 N). In addition, the oxidation characteristics of the coatings and the substrate were examined at three different temperatures (850, 950, and 1050 °C) using a muffle furnace. The coatings showed a lower oxidation rate, which was approximately one-tenth of that of the substrate. Even after oxidation for 100 h, the Al2O3 phase was the primary phase in the surface coating (850 °C), with the thickness of the oxide film increasing to 0.65 μm at 950 °C. When the temperature was increased beyond 1050 °C, the elemental Al and Ni were consumed in the formation of the oxide scale, which underwent spallation at several locations. The oxidation products of Cr, which were produced in large amounts and had a prism-like structure, controlled the subsequent oxidation behavior at the surface.

  10. Transient oxidation of Al-deposited Fe-Cr-Al alloy foil

    International Nuclear Information System (INIS)

    Andoh, A.

    1997-01-01

    The oxide phases formed on an Al-deposited Fe-Cr-Al alloy foil and an Fe-Cr-Al alloy foil of the same levels of Al and (La+Ce) contents, and their oxidation kinetics have been studied in air at 1173 and 1373 K using TGA, XRD and SEM. Al deposition promotes the growth of metastable aluminas (θ-Al 2 O 3 , γ-Al 2 O 3 ). Scales consisting of θ-Al 2 O 3 and a small amount of α-Al 2 O 3 develop on the Al-deposited foil at 1173 K and exhibit the whisker-type morphology. In the early stage of oxidation at 1373 K, thick scales consisting of θ-Al 2 O 3 and α-Al 2 O 3 grow rapidly on the Al-deposited foil. The transformation from θ-Al 2 O 3 to α-Al 2 O 3 is very fast, and the scales result in only α-Al 2 O 3 . In contrast, α-Al 2 O 3 scales containing a minor amount of FeAl 2 O 4 develop on the alloy foil. The growth rate of α-Al 2 O 3 scales on the Al-deposited foil is smaller than that on the alloy foil and very close to that on NiAl at 1373 K. (orig.)

  11. Microstructure and mechanical properties of ultrafine-grained Fe-14Cr and ODS Fe-14Cr model alloys

    International Nuclear Information System (INIS)

    Auger, M.A.; Leguey, T.; Munoz, A.; Monge, M.A.; Castro, V. de; Fernandez, P.; Garces, G.; Pareja, R.

    2011-01-01

    Reduced activation ferritic Fe-14 wt%Cr and Fe-14 wt%Cr-0.3 wt%Y 2 O 3 alloys were produced by mechanical alloying and hot isostatic pressing followed by forging and heat treating. The alloy containing Y 2 O 3 developed a submicron-grained structure with homogeneous dispersion of oxide nanoparticles that enhanced the tensile properties in comparison to the Y 2 O 3 free alloy. Strengthening induced by the Y 2 O 3 dispersion appears to be effective up to 873 K, at least. A uniform distribution of Cr-rich precipitates, stable upon a heat treatment at 1123 K for 2 h, was also found in both alloys.

  12. Measurement and Analysis of Density of Molten Ni-W Alloys

    Institute of Scientific and Technical Information of China (English)

    FANG Liang; XIAO Feng; TAO Zainan; MuKai Kusuhiro

    2005-01-01

    The density of molten Ni-W alloys was measured with a modified pycnometric method. It is found that the density of the molten Ni- W alloys decreases with temperature rising, but increases with the increase of tungsten concentration in the alloys. The molar volume of molten Ni- W binary alloys increases with the increase of temperature and tungsten concentration. The partial molar volume of tungsten in liquid Ni- W binary alloy has been calculated approximately as ( - 1.59+ 5.64 × 10-3 T) × 10-6m3 ·mol-1.

  13. Transformation lines in an Fe-Cr-Ni-Mn-Si polycrystalline shape memory alloy

    International Nuclear Information System (INIS)

    Tanaka, Kikuaki; Hayashi, Toshimitsu; Fischer, F.D.; Buchmayr, B.

    1994-01-01

    Transformation lines, the martensite/austenite start and finish conditions in the stress-temperature plane, are determined in an Fe-Cr-Ni-Mn-Si polycrystalline shape memory alloy with two different experimental procedures. The transformation lines are shown to be almost linear with nearly the same slope. The martensitic transformation zone and the reverse transformation zone do not coincide, and the reverse transformation zone is very wide; T Af -T As ∼ 180 K. The strong dependence on the preloading of the transformation lines, especially of the reverse transformation lines, is examined. (orig.)

  14. Microstructure and Tensile Behavior of Al8Co17Cr17Cu8Fe17Ni33 (at.%) High-Entropy Alloy

    Science.gov (United States)

    Daoud, H. M.; Manzoni, A.; Völkl, R.; Wanderka, N.; Glatzel, U.

    2013-12-01

    Microstructure evolution and tensile behavior of the high-entropy alloy Al8Co17Cr17Cu8Fe17Ni33 (at.%) are investigated at room temperature and at 500°C in the as-cast state and under different heat-treatment conditions. Detailed microstructural characterizations are carried out using optical microscopy, scanning electron microscopy, and transmission electron microscopy. The equilibrium phase evolution as a function of temperature was calculated using the Thermo-Calc software (Thermo-Calc Software, Stockholm, Sweden) integrated with TTNi-7 database. The observed majority phase is a face-centered cubic solid solution for all tested specimens. Tensile ductility at room temperature and at elevated temperature is enhanced by heat treatment at 1150°C. An embrittlement phenomenon has been observed after a heat treatment at 700°C resulting in significant degradation in tensile properties.

  15. Nickel Alloy, Corrosion and Heat-Resistant, Sheet, Strip, and Plate 72Ni - 15.5Cr - 0.95 (Cb (Nb) + Ta) - 2.5Ti - 0.70Al - 7.0Fe Consumable Electrode, Remelted or Vacuum Induction Melted, Solution Heat Treated, Precipitation-Hardenable

    CERN Document Server

    SAE Aerospace Standards. London

    2012-01-01

    Nickel Alloy, Corrosion and Heat-Resistant, Sheet, Strip, and Plate 72Ni - 15.5Cr - 0.95 (Cb (Nb) + Ta) - 2.5Ti - 0.70Al - 7.0Fe Consumable Electrode, Remelted or Vacuum Induction Melted, Solution Heat Treated, Precipitation-Hardenable

  16. NEUTRON-INDUCED SWELLING OF Fe-Cr BINARY ALLOYS IN FFTF AT ∼400 DEGREES C

    International Nuclear Information System (INIS)

    Garner, Francis A.; Greenwood, Lawrence R.; Okita, Taira; Sekimura, Naoto; Wolfer, W. G.

    2002-01-01

    The purpose of this effort is to determine the influence of dpa rate, He/dpa ratio and composition on the void swelling of simple binary Fe-Cr alloys. Contrary to the behavior of swelling of model fcc Fe-Cr-Ni alloys irradiated in the same FFTF-MOTA experiment, model bcc Fe-Cr alloys do not exhibit a dependence of swelling on dpa rate at approximately 400 degrees C. This is surprising in that an apparent flux-sensitivity was observed in an earlier comparative irradiation of Fe-Cr binaries conducted in EBR-II and FFTF. The difference in behavior is ascribed to the higher helium generation rates of Fe-Cr alloys in EBR-II compared to that of FFTF, and also the fact that lower dpa rates in FFTF are accompanied by progressively lower helium generation rates.

  17. The Al-rich region of the Al-Mn-Ni alloy system. Part II. Phase equilibria at 620-1000 oC

    International Nuclear Information System (INIS)

    Balanetskyy, S.; Meisterernst, G.; Grushko, B.; Feuerbacher, M.

    2011-01-01

    Research highlights: → Phase equilibria in the Al-rich region of the Al-Mn-Ni alloy system were studied at 1000, 950, 850, 750, 700, 645 and 620 deg. C by means of SEM, TEM, powder XRD and DTA. → Three ternary thermodynamically stable intermetallics, the φ-phase (Al 5 Co 2 -type, hP26, P63/mmc; a = 0.76632(16), c = 0.78296(15) nm), the κ-phase (κ-Al 14.4 Cr 3.4 Ni l.1 -type, hP227, P63/m; a = 1.7625(10), c = 1.2516(10) nm), and the O-phase (O-Al 77 Cr 14 Pd 9 -type, Pmmn, oP650,: a = 2.3316(16), b = 1.2424(15), c = 3.2648(14) nm), as well as three ternary metastable phases, the decagonal D 3 -phase with periodicity about 1.25 nm, the Al 9 (Mn,Ni) 2 -phase (Al 9 Co 2 -type, P1121/a, mP22; a = 0.8585(16), b = 0.6269(9), c = 0.6205(11) nm, β = 95.34(10) o ) and the O 1 -phase (basecentered orthorhombic, a ∼ 23.8, b ∼ 12.4, c ∼ 32.2 nm) were revealed. → The existence of a thermodynamically stable R-phase of stoichiometry Al 60 Mn 11 Ni 4 , reported earlier in literature, was not confirmed in the present study. - Abstract: Phase equilibria in the Al-rich region of the Al-Mn-Ni alloy system were studied at 1000, 950, 850, 750, 700, 645 and 620 o C. Three ternary thermodynamically stable intermetallics, the φ-phase (Al 5 Co 2 -type, hP26, P6 3 /mmc; a = 0.76632(16), c = 0.78296(15) nm), the κ-phase (κ-Al 14.4 Cr 3.4 Ni l.1 -type, hP227, P6 3 /m; a = 1.7625(10), c = 1.2516(10) nm), and the O-phase (O-Al 77 Cr 14 Pd 9 -type, Pmmn, oP650,: a = 2.3316(16), b = 1.2424(15), c = 3.2648(14) nm), as well as three ternary metastable phases, the decagonal D 3 -phase with periodicity about 1.25 nm, the Al 9 (Mn,Ni) 2 -phase (Al 9 Co 2 -type, P112 1 /a, mP22; a = 0.8585(16), b = 0.6269(9), c = 0.6205(11) nm, β = 95.34(10) o ) and the O 1 -phase (base-centered orthorhombic, a ∼ 23.8, b ∼ 12.4, c ∼ 32.2 nm) were revealed. Their physicochemical behaviour in the Al-Mn-Ni alloy system was studied.

  18. Magnetocaloric Properties of Fe-Ni-Cr Nanoparticles for Active Cooling

    Science.gov (United States)

    Chaudhary, V.; Ramanujan, R. V.

    2016-10-01

    Low cost, earth abundant, rare earth free magnetocaloric nanoparticles have attracted an enormous amount of attention for green, energy efficient, active near room temperature thermal management. Hence, we investigated the magnetocaloric properties of transition metal based (Fe70Ni30)100-xCrx (x = 1, 3, 5, 6 and 7) nanoparticles. The influence of Cr additions on the Curie temperature (TC) was studied. Only 5% of Cr can reduce the TC from ~438 K to 258 K. These alloys exhibit broad entropy v/s temperature curves, which is useful to enhance relative cooling power (RCP). For a field change of 5 T, the RCP for (Fe70Ni30)99Cr1 nanoparticles was found to be 548 J-kg-1. Tunable TCin broad range, good RCP, low cost, high corrosion resistance and earth abundance make these nanoparticles suitable for low-grade waste heat recovery as well as near room temperature active cooling applications.

  19. A new methodology based on ultrasonic attenuation to characterize dynamically recrystallized microstructure in a 15Cr-15Ni-2.2Mo-Ti modified austenitic stainless steel

    International Nuclear Information System (INIS)

    Mandal, S.; Kumar, A.; Sivaprasad, P.V.; Jayakumar, T.; Baldev Raj; Kumar, S.; Samajdar, I.

    2010-01-01

    In this study, a C-scan ultrasonic imaging system has been employed for imaging the microstructural variations during dynamic recrystallization (DRX) of a 15Cr-15Ni-2.2Mo-Ti modified austenitic stainless steel. Four specimens were forged at 1273 K for different strains in the range of 0.1-0.5. It has been observed that the specimen with 0.2 strain or lower did not show any variation in the amplitude of the first backwall echo. However, at and above 0.3 strain, a visible variation in the C-scan images has been observed. This variation has been attributed to the evolution of fine grains. The formation of fine grains, on the other hand, was related to DRX, as indicated by electron back scattered diffraction (EBSD). (author)

  20. Developing precipitation hardenable high entropy alloys

    Science.gov (United States)

    Gwalani, Bharat

    High entropy alloys (HEAs) is a concept wherein alloys are constructed with five or more elements mixed in equal proportions; these are also known as multi-principle elements (MPEs) or complex concentrated alloys (CCAs). This PhD thesis dissertation presents research conducted to develop precipitation-hardenable high entropy alloys using a much-studied fcc-based equi-atomic quaternary alloy (CoCrFeNi). Minor additions of aluminium make the alloy amenable for precipitating ordered intermetallic phases in an fcc matrix. Aluminum also affects grain growth kinetics and Hall-Petch hardenability. The use of a combinatorial approach for assessing composition-microstructure-property relationships in high entropy alloys, or more broadly in complex concentrated alloys; using laser deposited compositionally graded AlxCrCuFeNi 2 (0 mechanically processed via conventional techniques. The phase stability and mechanical properties of these alloys have been investigated and will be presented. Additionally, the activation energy for grain growth as a function of Al content in these complex alloys has also been investigated. Change in fcc grain growth kinetic was studied as a function of aluminum; the apparent activation energy for grain growth increases by about three times going from Al0.1CoCrFeNi (3% Al (at%)) to Al0.3CoCrFeNi. (7% Al (at%)). Furthermore, Al addition leads to the precipitation of highly refined ordered L12 (gamma') and B2 precipitates in Al0.3CoCrFeNi. A detailed investigation of precipitation of the ordered phases in Al0.3CoCrFeNi and their thermal stability is done using atom probe tomography (APT), transmission electron microscopy (TEM) and Synchrotron X-ray in situ and ex situ analyses. The alloy strengthened via grain boundary strengthening following the Hall-Petch relationship offers a large increment of strength with small variation in grain size. Tensile strength of the Al0.3CoFeNi is increased by 50% on precipitation fine-scale gamma' precipitates

  1. Microstructural comparison of effects of hafnium and titanium additions in spark-plasma-sintered Fe-based oxide-dispersion strengthened alloys

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yina, E-mail: huangyina1981@hotmail.com [Department of Materials, University of Oxford, Oxford OX1 3PH (United Kingdom); School of Electronic Science & Applied Physics, Hefei University of Technology, Hefei, Anhui 230009 (China); Zhang, Hongtao [Department of Materials, Loughborough University, Leicestershire, LE11 3TU (United Kingdom); Auger, Maria A.; Hong, Zuliang [Department of Materials, University of Oxford, Oxford OX1 3PH (United Kingdom); Ning, Huanpo [School of Engineering of Materials Science, Queen Mary University of London, London, E1 4NS (United Kingdom); Nanoforce Technology Ltd, London, E1 4NS (United Kingdom); Gorley, Michael J. [Department of Materials, University of Oxford, Oxford OX1 3PH (United Kingdom); CCFE, Culham Science Centre, Abingdon, Oxon, OX14 3DB (United Kingdom); Grant, Patrick S. [Department of Materials, University of Oxford, Oxford OX1 3PH (United Kingdom); Reece, Michael J.; Yan, Haixue [School of Engineering of Materials Science, Queen Mary University of London, London, E1 4NS (United Kingdom); Nanoforce Technology Ltd, London, E1 4NS (United Kingdom); Roberts, Steve G. [Department of Materials, University of Oxford, Oxford OX1 3PH (United Kingdom); CCFE, Culham Science Centre, Abingdon, Oxon, OX14 3DB (United Kingdom)

    2017-04-15

    Two oxide dispersion strengthened alloys: 14Cr-0.25Y{sub 2}O{sub 3}-0.22Hf (wt.%) and Fe-14Cr-0.25Y{sub 2}O{sub 3}-0.4Ti (wt.%) were fabricated by mechanical alloying and subsequently consolidated by spark plasma sintering (SPS). Electron backscatter diffraction showed grain sizes in the range 0.5–15 μm in both alloys. Transmission electron microscopy and scanning transmission electron microscopy showed a homogeneous distribution of nano-oxides precipitated during SPS. Using high resolution transmission electron microscopy, energy dispersive X-ray spectroscopy and atom probe tomography, several different oxide phases were found in both alloys, but the majority of dispersoids were Y-Hf-O type in Fe-14Cr-0.25Y{sub 2}O{sub 3}-0.22Hf and Y-Ti-O type in Fe-14Cr-0.25Y{sub 2}O{sub 3}-0.4Ti. There were a variety of orientation relationships between the different dispersoids and the ferritic matrix. Both alloys had dispersoid densities of ∼10{sup 23}/m{sup 3}, with average diameters of 4.3 nm and 3.5 nm in the 0.22Hf and 0.4Ti containing alloys, respectively. Per atom added, Hf (0.07 at.%) is suggested to be more potent than Ti (0.46 at.%) in refining the nano-oxides.

  2. Effect of self-absorption correction on surface hardness estimation of Fe-Cr-Ni alloys via LIBS.

    Science.gov (United States)

    Ramezanian, Zahra; Darbani, Seyyed Mohammad Reza; Majd, Abdollah Eslami

    2017-08-20

    The effect of self-absorption was investigated on the estimation of surface hardness of Fe-Cr-Ni metallic alloys by the laser-induced breakdown spectroscopy (LIBS) technique. For this purpose, the linear relationship between the ratio of chromium ionic to atomic line intensities (CrII/CrI) and surface hardness was studied, both before and after correcting the self-absorption effect. The correlation coefficient significantly increased from 47% to 90% after self-absorption correction. The results showed the measurements of surface hardness using LIBS can be more accurate and valid by correcting the self-absorption effect.

  3. Structure and magnetic properties of Co{sub 2}(Cr{sub 1−x}Fe{sub x})Al, (0 ≤ x ≤ 1) Heusler alloys prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Yogesh, E-mail: 123209001_yogesh@manit.ac.in [Department of Materials Science & Metallurgical Engineering, Ceramic & Powder Metallurgy Laboratory, Maulana Azad National Institute of Technology, Bhopal, Madhya Pradesh 462003 (India); Vajpai, Sanjay Kumar, E-mail: vajpaisk@gmail.com [Department of Materials Science & Metallurgical Engineering, Maulana Azad National Institute of Technology, Bhopal, Madhya Pradesh 462003 (India); Srivastava, Sanjay, E-mail: s.srivastava.msme@gmail.com [Department of Materials Science & Metallurgical Engineering, Maulana Azad National Institute of Technology, Bhopal, Madhya Pradesh 462003 (India)

    2017-07-01

    Highlights: • A series of nanocrystalline Co{sub 2}(Cr{sub 1−x}Fe{sub x})Al Heusler alloy by powder metallurgy. • Effect of substitution of Fe for Cr on the microstructure and magnetic properties. • Increasing amounts of B2 type disordered structure with increasing Fe content. • Enhanced Ms, Mr, Hc, and Tc with increasing Fe content. • Relative magnetic anisotropy decreased with increasing Fe content. - Abstract: In the present study, a series of nanocrystalline Co{sub 2}(Cr{sub 1−x}Fe{sub x})Al Heusler alloy powders were successfully prepared by high energy ball milling and the effect of substitution of Fe for Cr on the microstructure and magnetic properties was investigated in detail. The Co{sub 2}CrAl alloy powder consisted of only A2 type disordered structure whereas the substitution of Cr by Fe led to the appearance of increasing amounts of B2 type disordered structure along with A2 type structure. All the Co{sub 2}(Cr{sub 1−x}Fe{sub x})Al Heusler alloy powders demonstrated high spontaneous magnetization together with a very small hysteresis losses. The saturation magnetization, remanence, coercivity, and Curie temperature increased with increasing Fe content. The increasing magnetization with increasing Fe content was attributed to the replacement of antiferromagnetic Cr by strongly ferromagnetic Fe and an increasing amounts of relatively more ordered, atomically as well as ferromagnetically, B2 structure as compared to that of A2 phase. The increment in remanence and coercivity with increasing Fe content were associated with the variation in microstructural characteristics, such as grain size, lattice defects, and the presence of small amounts of magnetic/nonmagnetic secondary phases. The increment in Curie temperature with increasing Fe content was attributed to the enhancement of d-d exchange interaction due to the possible occupancy of vacant sites by Fe atoms. All the Heusler alloys indicated extremely low magnetic anisotropy and the

  4. Phase stability and tensile properties of Co-free Al0.5CrCuFeNi2 high-entropy alloys

    International Nuclear Information System (INIS)

    Ng, Chun; Guo, Sheng; Luan, Junhua; Wang, Qing; Lu, Jian; Shi, Sanqiang; Liu, C.T.

    2014-01-01

    Highlights: • The solid solution phase in the high-entropy alloy was confirmed to be metastable. • The alloy exhibited microstructural and mechanical stability against annealing. • Only as-cast alloys showed sufficient tensile plasticity. • A large variability of the measured tensile properties was recorded. • The alloys showing slip banding behavior did not necessarily have tensile ductility. -- Abstract: High-entropy alloys (HEAs) are becoming new research frontiers in the metallic materials field. The phase stability of HEAs is of critical significance, but a convincing understanding on it has been somewhat held back by the slow diffusion kinetics, which prevents the completion of diffusion assisted phase transformations toward the equilibrium state. Here a unique methodology, combining both the thermomechanical treatments and thermodynamic calculations, was employed to reveal the phase stability of HEAs, exemplified using the newly developed Al 0.5 CrCuFeNi 2 alloy. The metastable nature of the solid solution phases in this high-entropy alloy was uncovered through thermomechanical treatments induced phase transformations, and supported by the thermodynamic calculations. Meanwhile, the tensile properties for both the as-cast and thermomechanically treated alloys were measured, and correlated to their indentation behavior

  5. Surface morphology of scale on FeCrAl (Pd, Pt, Y) alloys

    International Nuclear Information System (INIS)

    Amano, T.; Takezawa, Y.; Shiino, A.; Shishido, T.

    2008-01-01

    The high temperature oxidation behavior of Fe-20Cr-4Al, floating zone refined (FZ) Fe-20Cr-4Al, Fe-20Cr-4Al-0.5Pd, Fe-20Cr-4Al-0.5Pt and Fe-20Cr-4Al-(0.01, 0.02, 0.05, 0.1, 0.2, 0.5)Y alloys was studied in oxygen for 0.6-18 ks at 1273-1673 K by mass gain measurements, X-ray diffraction and scanning electron microscopy. The mass gains of FeCrAl, FZ FeCrAl, FeCrAlPd and FeCrAlPt alloys showed almost the same values. Those of FeCrAl-(0.01, 0.02, 0.05, 0.1, 0.2, 0.5)Y alloys decreased with increasing yttrium of up to 0.1% followed by an increase with the yttrium content after oxidation for 18 ks at 1473 K. Needle-like oxide particles were partially observed on FeCrAl alloy after oxidation for 7.2 ks at 1273 K. These oxide particles decreased in size with increasing oxidation time of more than 7.2 ks at 1473 K, and then disappeared after oxidation for 7.2 ks at 1573 K. It is suggested that a new oxide develops at the oxygen/scale interface. The scale surface of FeCrAl alloy showed a wavy morphology after oxidation for 7.2 ks at 1273 K which then changed to planar morphology after an oxidation time of more than 7.2 ks at 1573 K. On the other hand, the scale surfaces of other alloys were planar after all oxidation conditions in this study. The scale surfaces of FeCrAl, FZ FeCrAl, FeCrAlPd and FeCrAlPt alloys were rough, however, those of FeCrAl-(0.1, 0.2, 0.5)Y alloys were smooth. The oxide scales formed on FeCrAl-(0.1, 0.2, 0.5)Y alloys were found to be α-Al 2 O 3 with small amounts of Y 3 Al 5 O 12 , and those of the other alloys were only α-Al 2 O 3

  6. About oxide dispersion particles chemical compatibility with areas coherent dissipation/sub-grains of bcc-alloys in Fe - (Cr, V, Mo, W systems

    Directory of Open Access Journals (Sweden)

    Udovsky A.

    2016-01-01

    Full Text Available A concept of partial magnetic moments (PMM of the iron atoms located in the first ч four coordination spheres (1÷4 CS for bcc lattice have been introduced based on analysis of results obtained by quantum-mechanical calculations (QMC for volume dependence of the average magnetic moment ferromagnetic (FM Fe. The values of these moments have been calculated for pure bcc Fe and bcc - Fe-Cr alloys. This concept has been used to formulate a three sub-lattice model for binary FM alloys of the Fe-M systems (M is an alloying paramagnetic element. Physical reason for sign change dependence of the short-range order and mixing enthalpy obtained by QMCs for Fe-(Cr, V bcc phases has been found. Using this model it has been predicted that static displacements of Fe - atoms in alloy matrix increase with increasing the of CS number and result in reducing of the area of coherent dissipation (ACD size with growth of the dimension factor (DF in the Fe-(Cr, V, Mo, W systems in agreement with the X-ray experiments. It has been shown theoretically that anisotropy of spin- density in bcc lattice Fe and DF in binary Fe - (Cr, V, Mo, W systems is main factor for origins of segregations on small angle boundaries of ACD and sub-grains boundaries To prevent the coagulation of both ACD and sub-grains, and to increase the strength of alloys, it is advisable to add oxide dispersion particles into ferrite steel taking into account their chemical compatibility and coherent interfacing with the crystalline lattice of a ferrite matrix. Application of phase diagrams for binary and ternary the Fe-(Y, Zr-O systems to verify chemical compatibility of oxide dispersion particles with ferrite matrix have been discussed

  7. Synthesis of FeCoNi nanoparticles by galvanostatic technique

    International Nuclear Information System (INIS)

    Budi, Setia; Hafizah, Masayu Elita; Manaf, Azwar

    2016-01-01

    Soft magnetic nanoparticles of FeCoNi have been becoming interesting objects for many researchers due to its potential application in electronic devices. One of the most promising methods for material preparation is the electrodeposition which capable of growing nanoparticles alloy directly onto the substrate. In this paper, we report our electrodeposition studies on nanoparticles synthesis using galvanostatic electrodeposition technique. Chemical composition of the synthesized FeCoNi was successfully controlled through the adjustment of the applied currents. It is revealed that the content of each element, obtained from quantitative analysis using atomic absorption spectrometer (AAS), could be modified by the adjustment of current in which Fe and Co content decreased at larger applied currents, while Ni content increased. The nanoparticles of Co-rich FeCoNi and Ni-rich FeCoNi were obtained from sulphate electrolyte at the range of applied current investigated in this work. Broad diffracted peaks in the X-ray diffractograms indicated typical nanostructures of the solid solution of FeCoNi.

  8. Synthesis of FeCoNi nanoparticles by galvanostatic technique

    Energy Technology Data Exchange (ETDEWEB)

    Budi, Setia, E-mail: setiabudi@unj.ac.id [Potgraduate Program of Materials Science Study, Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Indonesia, Depok 16424 (Indonesia); Department of Chemistry, Faculty of Mathematics and Sciences, Universitas Negeri Jakarta, Jl. Pemuda No.10, Rawamangun, Jakarta 13220 (Indonesia); Hafizah, Masayu Elita; Manaf, Azwar, E-mail: azwar@ui.ac.id [Potgraduate Program of Materials Science Study, Department of Physics, Faculty of Mathematics and Natural Sciences, Universitas Indonesia, Depok 16424 (Indonesia)

    2016-06-17

    Soft magnetic nanoparticles of FeCoNi have been becoming interesting objects for many researchers due to its potential application in electronic devices. One of the most promising methods for material preparation is the electrodeposition which capable of growing nanoparticles alloy directly onto the substrate. In this paper, we report our electrodeposition studies on nanoparticles synthesis using galvanostatic electrodeposition technique. Chemical composition of the synthesized FeCoNi was successfully controlled through the adjustment of the applied currents. It is revealed that the content of each element, obtained from quantitative analysis using atomic absorption spectrometer (AAS), could be modified by the adjustment of current in which Fe and Co content decreased at larger applied currents, while Ni content increased. The nanoparticles of Co-rich FeCoNi and Ni-rich FeCoNi were obtained from sulphate electrolyte at the range of applied current investigated in this work. Broad diffracted peaks in the X-ray diffractograms indicated typical nanostructures of the solid solution of FeCoNi.

  9. Physical properties of molten core materials: Zr-Ni and Zr-Cr alloys measured by electrostatic levitation

    Energy Technology Data Exchange (ETDEWEB)

    Ohishi, Yuji, E-mail: ohishi@see.eng.osaka-u.ac.jp [Graduate School of Engineering, Osaka University (Japan); Kondo, Toshiki [Graduate School of Engineering, Osaka University (Japan); Ishikawa, Takehiko [Japan Aerospace Exploration Agency (Japan); SOKEN-DAI (Graduate University for Advanced Studies) (Japan); Okada, Junpei T. [Institute for Materials Research, Tohoku University (Japan); Watanabe, Yuki [Advanced Engineering Services Co. Ltd. (Japan); Muta, Hiroaki; Kurosaki, Ken [Graduate School of Engineering, Osaka University (Japan); Yamanaka, Shinsuke [Graduate School of Engineering, Osaka University (Japan); Research Institute of Nuclear Engineering, University of Fukui (Japan)

    2017-03-15

    It is important to understand the behaviors of molten core materials to investigate the progression of a core meltdown accident. In the early stages of bundle degradation, low-melting-temperature liquid phases are expected to form via the eutectic reaction between Zircaloy and stainless steel. The main component of Zircaloy is Zr and those of stainless steel are Fe, Ni, and Cr. Our group has previously reported physical property data such as viscosity, density, and surface tension for Zr-Fe liquid alloys using an electrostatic levitation technique. In this study, we report the viscosity, density, and surface tension of Zr-Ni and Zr-Cr liquid alloys (Zr{sub 1-x}Ni{sub x} (x = 0.12 and 0.24) and Zr{sub 0.77}Cr{sub 0.23}) using the electrostatic levitation technique. - Highlights: • The physical properties of Zr-Ni and Zr-Cr liquid alloys have been measured Zr{sub 1-x}Ni{sub x} (x = 0.12 and 0.24) and Zr{sub 77}Cr{sub 23}. • The measurement was conducted using the electrostatic levitation technique. • The density, viscosity, and surface tension of each liquid alloy were measured.

  10. Physical properties of molten core materials: Zr-Ni and Zr-Cr alloys measured by electrostatic levitation

    International Nuclear Information System (INIS)

    Ohishi, Yuji; Kondo, Toshiki; Ishikawa, Takehiko; Okada, Junpei T.; Watanabe, Yuki; Muta, Hiroaki; Kurosaki, Ken; Yamanaka, Shinsuke

    2017-01-01

    It is important to understand the behaviors of molten core materials to investigate the progression of a core meltdown accident. In the early stages of bundle degradation, low-melting-temperature liquid phases are expected to form via the eutectic reaction between Zircaloy and stainless steel. The main component of Zircaloy is Zr and those of stainless steel are Fe, Ni, and Cr. Our group has previously reported physical property data such as viscosity, density, and surface tension for Zr-Fe liquid alloys using an electrostatic levitation technique. In this study, we report the viscosity, density, and surface tension of Zr-Ni and Zr-Cr liquid alloys (Zr 1-x Ni x (x = 0.12 and 0.24) and Zr 0.77 Cr 0.23 ) using the electrostatic levitation technique. - Highlights: • The physical properties of Zr-Ni and Zr-Cr liquid alloys have been measured Zr 1-x Ni x (x = 0.12 and 0.24) and Zr 77 Cr 23 . • The measurement was conducted using the electrostatic levitation technique. • The density, viscosity, and surface tension of each liquid alloy were measured.

  11. Variation in band gap of lanthanum chromate by transition metals doping LaCr{sub 0.9}A{sub 0.1}O{sub 3} (A:Fe/Co/Ni)

    Energy Technology Data Exchange (ETDEWEB)

    Naseem, Swaleha, E-mail: wasiamu@gmail.com; Khan, Wasi, E-mail: wasiamu@gmail.com; Saad, A. A., E-mail: wasiamu@gmail.com; Shoeb, M., E-mail: wasiamu@gmail.com; Ahmed, Hilal, E-mail: wasiamu@gmail.com; Naqvi, A. H. [Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Z.H. College of Engg. and Technology, Aligarh Muslim University, Aligarh-202002 (India); Husain, Shahid [Department of Physics, Aligarh Muslim University, Aligarh-202002 (India)

    2014-04-24

    Transition metal (Fe, Co, Ni) doped lanthanum chromate (LaCrO{sub 3}) nanoparticles (NPs) were prepared by gel combustion method and calcinated at 800°C. Microstructural studies were carried by XRD and SEM/EDS techniques. The results of structural characterization show the formation of all samples in single phase without any impurity. Optical properties were studied by UV- visible and photoluminescence techniques. The energy band gap was calculated and the variation was observed with the doping of transition metal ions. Photoluminescence spectra show the emission peak maxima for the pure LaCrO{sub 3} at about 315 nm. Influence of Fe, Co, Ni doping was studied and compared with pure lanthanum chromate nanoparticles.

  12. Effect of Si on the glass-forming ability, thermal stability and magnetic properties of Fe-Co-Zr-Mo-W-B alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wang, W.-M. [Institute for Metallic Materials, IFW Dresden, P.O. 270016, Dresden D-01171 (Germany); Key Lab of Liquid Structure and Heredity of Materials, Shandong University, Jinan 250061 (China); Gebert, A. [Institute for Metallic Materials, IFW Dresden, P.O. 270016, Dresden D-01171 (Germany)], E-mail: a.gebert@ifw-dresden.de; Roth, S.; Kuehn, U.; Schultz, L. [Institute for Metallic Materials, IFW Dresden, P.O. 270016, Dresden D-01171 (Germany)

    2008-07-14

    This paper presents investigations on the effect of Si on the glass-forming ability, thermal stability and magnetic properties of the Fe-Co-Zr-Mo-W-B samples (group I: Fe{sub 60}Co{sub 8}Zr{sub 10}Mo{sub 5}W{sub 2}B{sub 15-x}Si{sub x}, 1 {<=} x {<=} 4; group II: Fe{sub 60}Co{sub 8}Zr{sub 10-x}Mo{sub 5}W{sub 2}B{sub 15}Si{sub x}, 0 {<=} x {<=} 4; group III: Fe{sub 60}Co{sub 8}Zr{sub 8}Mo{sub 5}W{sub 2}B{sub 17-x}Si{sub x}, 0 {<=} x {<=} 2) prepared by melt spinning, injection casting, and centrifugal casting methods. It is found that the glass-forming ability (GFA) of the alloys in group I is more deteriorated than that in group II, and that the alloys in group III can be cast into the rods of 1-3 mm diameter without crystalline reflections in their XRD patterns. For the amorphous ribbons and rods, a non-monotonic change of the nearest neighbour distance r{sub 1} with increasing Si content c{sub Si} was detected, which is parallel to that of the glass transition and crystallization temperatures T{sub g} and T{sub x}, but opposite to that of the magnetization at room temperature M{sub RT} and the Curie temperature T{sub c}. This correlation can be interpreted by a structure model presuming that iron atoms appear simultaneously in two types of local structures in the amorphous samples.

  13. Moessbauer and XRD study of pulse plated Fe-P and Fe-Ni thin layers

    International Nuclear Information System (INIS)

    Miko, Annamaria; Kuzmann, Erno; Lakatos-Varsanyi, Magda; Kakay, Attila; Nagy, Ferenc; Varga, Lajos Karoly

    2005-01-01

    57 Fe conversion electron Moessbauer spectroscopy, X-ray diffraction, electrochemical and magnetic measurements were used to study pulse electroplated Fe-P and Ni-Fe coatings. XRD and 57 Fe CEMS measurements revealed the amorphous character of the novel pulse plated Fe-P alloys. CEM spectra indicated significant differences in the short range order and in the magnetic anisotropy between the Fe-P deposits pulse plated at medium long deposition time (t on = 2 ms), with short relaxation time (t off = 9 ms) and low current density (I p = 0.05 Acm -2 ) or at short deposition time (t on = 1 ms) with long relaxation time (t off = 250 ms) and high current density (I p = 1.0 Acm -2 ). The broad peaks centred around the fcc reflections in XRD of the pulse plated Ni-22 wt.% Fe deposit reflected a microcrystalline Ni-Fe alloy with a very fine, 5-8 nm, grain size. The CEM spectrum of the pulse plated Ni-22 wt.% Fe coating corresponded to a highly disordered solid solution alloy containing a minute amount of ferrihydrite. Extreme favourable soft magnetic properties were observed with these Ni-Fe and Fe-P pulse plated thin layers.

  14. Microstructure and mechanical properties of ultrafine-grained Fe-14Cr and ODS Fe-14Cr model alloys

    Energy Technology Data Exchange (ETDEWEB)

    Auger, M.A., E-mail: mauger@fis.uc3m.es [Departamento de Fisica-IAAB, Universidad Carlos III de Madrid, 28911-Leganes (Spain); Leguey, T., E-mail: leguey@fis.uc3m.es [Departamento de Fisica-IAAB, Universidad Carlos III de Madrid, 28911-Leganes (Spain); Munoz, A., E-mail: amunoz@fis.uc3m.es [Departamento de Fisica-IAAB, Universidad Carlos III de Madrid, 28911-Leganes (Spain); Monge, M.A., E-mail: mmonge@fis.uc3m.es [Departamento de Fisica-IAAB, Universidad Carlos III de Madrid, 28911-Leganes (Spain); Castro, V. de, E-mail: vanessa.decastro@materials.ox.ac.uk [Department of Materials, University of Oxford, OX1 3PH (United Kingdom); Fernandez, P., E-mail: pilar.fernandez@ciemat.es [National Fusion Laboratory-CIEMAT, Avda. Complutense 22, 28040 Madrid (Spain); Garces, G., E-mail: ggarces@cenim.csic.es [Departamento de Metalurgia Fisica, CENIM (CSIC), Avda. Gregorio del Amo 8, 28040 Madrid (Spain); Pareja, R., E-mail: rpp@fis.uc3m.es [Departamento de Fisica-IAAB, Universidad Carlos III de Madrid, 28911-Leganes (Spain)

    2011-10-01

    Reduced activation ferritic Fe-14 wt%Cr and Fe-14 wt%Cr-0.3 wt%Y{sub 2}O{sub 3} alloys were produced by mechanical alloying and hot isostatic pressing followed by forging and heat treating. The alloy containing Y{sub 2}O{sub 3} developed a submicron-grained structure with homogeneous dispersion of oxide nanoparticles that enhanced the tensile properties in comparison to the Y{sub 2}O{sub 3} free alloy. Strengthening induced by the Y{sub 2}O{sub 3} dispersion appears to be effective up to 873 K, at least. A uniform distribution of Cr-rich precipitates, stable upon a heat treatment at 1123 K for 2 h, was also found in both alloys.

  15. Insights into the deformation behavior of the CrMnFeCoNi high-entropy alloy revealed by elevated temperature nanoindentation

    Energy Technology Data Exchange (ETDEWEB)

    Maier-Kiener, Verena [Montanuniversitat Leoben, Leoben (Austria); Schuh, Benjamin [Austrian Academy of Sciences, Leoben (Austria); George, Easo P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States); Clemens, Helmut [Montanuniversitat Leoben, Leoben (Austria); Hohenwarter, Anton [Austrian Academy of Sciences, Leoben (Austria)

    2017-07-27

    A CrMnFeCoNi high-entropy alloy was investigated by nanoindentation from room temperature to 400 °C in the nanocrystalline state and cast plus homogenized coarse-grained state. In the latter case a < 100 >-orientated grain was selected by electron back scatter diffraction for nanoindentation. It was found that hardness decreases more strongly with increasing temperature than Young’s modulus, especially for the coarse-grained state. The modulus of the nanocrystalline state was slightly higher than that of the coarse-grained one. For the coarse-grained sample a strong thermally activated deformation behavior was found up to 100–150 °C, followed by a diminishing thermally activated contribution at higher testing temperatures. For the nanocrystalline state, different temperature dependent deformation mechanisms are proposed. At low temperatures, the governing processes appear to be similar to those in the coarse-grained sample, but with increasing temperature, dislocation-grain boundary interactions likely become more dominant. Finally, at 400 °C, decomposition of the nanocrystalline alloy causes a further reduction in thermal activation. Furthermore, this is rationalized by a reduction of the deformation controlling internal length scale by precipitate formation in conjunction with a diffusional contribution.

  16. Electrical and magnetic properties of Fe-based bulk metallic glass with minor Co and Ni addition

    Energy Technology Data Exchange (ETDEWEB)

    Jung, H.Y. [IFW Dresden, Institute for Complex Materials, D–01069 Dresden (Germany); Stoica, M. [IFW Dresden, Institute for Complex Materials, D–01069 Dresden (Germany); POLITEHNICA University of Timisoara, P-ta Victoriei 2, Timisoara (Romania); Yi, S. [Department of Materials Science and Metallurgical Engineering, Kyungpook National University, 702–701 Daegu (Korea, Republic of); Kim, D.H. [Center for Non-crystalline Materials, Department of Metallurgical Engineering, Yonsei University, 120–749 Seoul (Korea, Republic of); Eckert, J. [IFW Dresden, Institute for Complex Materials, D–01069 Dresden (Germany); University of Technology Dresden, Institute of Materials Science, D–01062 Dresden (Germany)

    2014-09-01

    The effect of minor Co and Ni alloying on soft magnetic properties and electrical resistivity of Fe{sub 75.5}C{sub 7.0}Si{sub 3.3}B{sub 5.5}P{sub 8.7} (at%) bulk metallic glass has been investigated. Within examined compositional range (Co and Ni up to 4 at%, respectively), the saturation magnetization and electrical resistivity of the alloys continuously decrease with increasing Co or Ni content, while the Curie temperature and initial permeability increase. Comparing the effect of Co and Ni additions, the alloys with Co addition have much higher Curie temperature and saturation magnetization than the alloy with Ni addition. Also, the Co-added alloys show smaller coercivity and larger permeability than the Ni-added alloys. The present results suggest that minor addition of Co can provide better effectiveness to enhance the magnetic softness of Fe-based BMGs than minor Ni addition. - Highlights: • Soft magnetic characteristics of CI-based BMGs can be enhanced with minor Co and Ni alloying. • Minor Co addition can provide better effectiveness to enhance the magnetic softness of CI-based BMG than Ni addition. • Optimum Co addition enlarges atomic packing density and randomness of amorphous structure.

  17. MmNi 3.55Co 0.75Mn 0.4Al 0.3B 0.3 hydrogen storage alloys for high-power nickel/metal hydride batteries

    Science.gov (United States)

    Ye, Hui; Huang, Yuexiang; Chen, Jianxia; Zhang, Hong

    Non-stoichiometric La-rich MmNi 3.55Co 0.75Mn 0.4Al 0.3B 0.3 hydrogen storage alloys using B-Ni or B-Fe alloy as additive and Ce-rich MmNi 3.55Co 0.75Mn 0.4Al 0.3B 0.3 one using pure B as additive have been prepared and their microstructure, thermodynamic, and electrochemical characteristics have been examined. It is found that all investigated alloys show good activation performance and high-rate dischargeability though there is a certain decrease in electrochemical capacities compared with the commercial MmNi 3.55Co 0.75Mn 0.4Al 0.3 alloy. MmNi 3.55Co 0.75Mn 0.4Al 0.3B 0.3 alloys using B-Ni alloy as additive or adopting Ce-rich mischmetal show excellent rate capability and can discharge capacity over 190 mAh/g even under 3000 mA/g current density, which display their promising use in the high-power type Ni/MH battery. The electrochemical performances of these MmNi 3.55Co 0.75Mn 0.4Al 0.3B 0.3 alloys are well correlated with their microstructure, thermodynamic, and kinetic characteristics.

  18. Effect of mechanical alloying on FeCrC reinforced Ni alloys

    Energy Technology Data Exchange (ETDEWEB)

    Yilmaz, S. Osman [Univ. of Namik Kemal, Tekirdag (Turkey); Teker, Tanju [Adiyaman Univ. (Turkey). Dept. of Metallurgical and Materials Engineering; Demir, Fatih [Batman Univ. (Turkey)

    2016-05-01

    Mechanical alloying (MA) is a powder metallurgy processing technique involving cold welding, fracturing and rewelding of powder particles in a high-energy ball mill. In the present study, the intermetallic matrix composites (IMCs) of Ni-Al reinforced by M{sub 7}C{sub 3} were produced by powder metallurgical routes via solid state reaction of Ni, Al and M{sub 7}C{sub 3} particulates by mechanical alloying processes. Ni, Al and M{sub 7}C{sub 3} powders having 100 μm were mixed, mechanical alloyed and the compacts were combusted in a furnace. The mechanically alloyed (MAed) powders were investigated by X-ray diffraction (XRD), microhardness measurement, optic microscopy (OM), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The presence of the carbides depressed the formation of unwanted NiAl intermetallic phases. The mechanical alloyed M{sub 7}C{sub 3} particles were unstable and decomposed partially within the matrix during alloying and sintering, and the morphology of the composites changed with the dissolution ratio of M{sub 7}C{sub 3} and sintering temperature.

  19. Density of Ni-Cr Alloy in the Mushy State

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The density of Ni-Cr alloy in the mushy state has been measured using the modified sessile drop method. The density of Ni-Cr alloy in the mushy state was found to decrease with increasing temperature and Cr concentration in alloy.The molar volume of Ni-Cr alloy in the mushy state therefore increases with increasing the Cr concentration in alloy.The ratio of the difference of density divided by the temperature difference between liquidus and solidus temperatures decreases with increasing Cr concentration. The density of the alloy increased with the precipitation of a solid phase in alloy during the solidification process. The temperature dependence of the density of alloy in the mushy state was not linear but biquadratic.

  20. Site preference and elastic properties of ternary alloying additions in B2 YAg alloys by first-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Wu Yurong, E-mail: winwyr@126.com [College of Electromechanical Engineering, Hunan University of Science and Technology, Xiantang 411201 (China); Hu Wangyu [Department of Applied Physics, Hunan University, Changsha 410082 (China); Xu Longshan [Department of Materials Science and Engineering, Xiamen University of Technology, Xiamen 361024 (China)

    2012-09-15

    First-principles calculations were preformed to study the site preference behavior and elastic properties of 3d (Ti-Cu) transition-metal elements in B2 ductility YAg alloy. In YAg, Ti is found to occupy the Y sublattice whereas V, Cr, Co, Fe, Ni and Cu tend to substitute for Ag sublattice. Due to the addition of 3d transition metals, the lattice parameters of YAg is decreased in the order: VCrCr, Fe, Co and Cu can improve the ductility of YAg alloy, and Fe is the most effective element to improve the ductility of YAg, while Ti, Ni and V alloying elements can reduce the ductility of YAg alloy, especially, V transforms ductile into brittle for YAg alloy. In addition, both V and Ni alloying elements can increase the hardness of YAg alloy, and Y{sub 8}Ag{sub 7}V is harder than Y{sub 8}Ag{sub 7}Ni.

  1. Electrochemical hydrogen-storage properties of La{sub 0.78}Mg{sub 0.22}Ni{sub 2.67}Mn{sub 0.11}Al{sub 0.11}Co{sub 0.52}-M1Ni{sub 3.5}Co{sub 0.6}Mn{sub 0.4}Al{sub 0.}-5 composites

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Hongxia, E-mail: hhxhunan@126.com [Key Lab of New Processing Technology for Nonferrous Metals and Materials Ministry of Education, Guilin University of Technology, Guilin (China); Li, Guohui [Guangxi Scientific Experiment Center of Mining, Metallurgy and Environment, College of Chemistry and Bioengineering, Guilin University of Technology, Guilin (China); Zhuang, Shuxin [School of Material Science and engineering, Xiamen University of Technology, Xiamen (China)

    2013-07-15

    For improving the electrochemical properties of nonstoichiometric AB{sub 3} -type La{sub 0.7}8Mg{sub 0.22}Ni{sub 2.67}Mn{sub 0.11}Al{sub 0.11}Co{sub 0.52} alloy as negative electrode of Ni-MH battery, its related composites La{sub 0.78}Mg{sub 0.22}Ni{sub 2.67}Mn{sub 0.11}Al{sub 0.11}Co{sub 0.52}-x wt.% M1Ni{sub 3.5}Co{sub 0.6}Mn{sub 0.4}Al{sub 0.5} (x = 0, 10, 20, 30) were prepared. Analysis by X-ray diffractometry (XRD) revealed that the composites consist mainly of LaNi{sub 5} and La{sub 2}Ni{sub 7} phases. Despite the small decrease in the maximum discharge capacity, the cycle performance was significantly enhanced. Linear polarization (LP), anodic polarization (AP) and potential step discharge experiments revealed that the electrochemical kinetics increases first and then decreases with increasing x. (author)

  2. Al2O3 adherence on CoCrAl alloys

    International Nuclear Information System (INIS)

    Kingsley, L.M.

    1980-04-01

    Adherence of protective oxides on NiCrAl and CoCrAl superalloys has been promoted by a dispersion of a highly oxygen reactive element or its oxide being produced within the protection system. Two aspects of this subject are investigated here: the use of Al 2 O 3 as both the dispersion and protective oxide; and the production of an HfO 2 dispersion while simultaneously aluminizing the alloy. It was found that an Al 2 O 3 dispersion will act to promote the adherence of an external scale of Al 2 O 3 to a degree comparable to previously tested dispersions and an HfO 2 dispersion comparable to that produced by a Rhines pack treatment is produced during aluminization

  3. The influence of Fe content on spreading ability of tungsten heavy alloys matrix on tungsten surface

    Directory of Open Access Journals (Sweden)

    A. Krzyńska

    2011-07-01

    Full Text Available The results of experimental study of tungsten spreading ability with W-Ni-Co-Fe matrix are presented. The aim of these investigations was to see how Fe concentration in WNiCo matrix influences the wettability of tungsten grains during liquid phase sintering. Four green compact specimens containing 50%W, 10%Co and Ni + Fe = 40% but with different Ni to Fe ratio were prepared. The cylindrical specimen 5mm diameter and 5mm height were put on clean pure tungsten substrate and then 20 minutes heated at 1520oC in hydrogen atmosphere. After heating the specimens were carefully measured and then the specimens for structure observations were prepared. It was concluded, that increase of Fe content decrease the melting temperature of WNiCo alloy. The melting point decrease caused by Fe content increase substantially the spreading ability of tungsten substrate with WNiCo alloy. Metallography investigations showed some microstructure changes in “reaction zone” identified in tungsten substrate – (WNi40-xCo10Fex interface. The results of the study confirmed our earlier observations that even relative small Fe addition promotes Weight Heavy Alloys (WHA liquid phase sintering.

  4. Structure and grindability of cast Ti-5Cr-xFe alloys

    International Nuclear Information System (INIS)

    Hsu, H.-C.; Pan, C.-H.; Wu, S.-C.; Ho, W.-F.

    2009-01-01

    The purpose of this study was to investigate the structure, microhardness and grindability of Ti-5Cr and a series of ternary Ti-5Cr-xFe alloys with 0.1, 0.5, 1, 3 and 5 wt.% Fe, respectively. This study evaluated the phase and structure of Ti-5Cr and Ti-5Cr-xFe alloys, using an X-ray diffraction (XRD) for phase analysis and optical microscope for microstructure of the etched alloys. In addition, grindability was evaluated by measuring the amount of metal volume removed after grinding for 1 min at each of the four rotational speeds of the wheel (500, 750, 1000 or 1200 m/min), with the goal of developing a titanium alloy with better machinability than commercially pure titanium (c.p. Ti). The results showed that the structure of Ti-5Cr-xFe alloys is sensitive to the Fe content. With Fe contents higher than 0.5 wt.%, the equi-axed β phase is entirely retained, while ω phase was found in the Ti-5Cr, Ti-5Cr-0.1Fe, Ti-5Cr-0.5Fe and Ti-5Cr-1Fe alloys. The largest quantity of ω phase and highest microhardness were found in Ti-5Cr-0.5Fe and Ti-5Cr-1Fe alloys. The grinding rates of the Ti-5Cr and Ti-5Cr-xFe alloys showed a similar tendency to the microhardness. The Ti-5Cr, Ti-5Cr-0.1Fe, Ti-5Cr-0.5Fe and Ti-5Cr-1Fe alloys exhibited the best grindability, especially at 500, 750 and 1000 m/min. Furthermore, the grindability of the tested metals increased in proportion to grinding speed up to 1000 m/min, with a decrease after 1200 m/min. This study concluded that Fe may be used to harden titanium and improve the grindability

  5. Effect of Mo-Fe substitution on glass forming ability, thermal stability, and hardness of Fe-C-B-Mo-Cr-W bulk amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Khalifa, Hesham E.; Cheney, Justin L. [University of California, San Diego Materials Science and Engineering Program, 9500 Gilman Drive, La Jolla, CA 92093-0411 (United States); Vecchio, Kenneth S. [University of California, San Diego Department of NanoEngineering, 9500 Gilman Drive, La Jolla, CA 92093-0411 (United States)], E-mail: kvecchio@ucsd.edu

    2008-08-25

    Amorphous Fe{sub 67-x}C{sub 10}B{sub 9}Mo{sub 7+x}Cr{sub 4}W{sub 3} (x = 1-7 at.%) plates with 640 {mu}m thickness were prepared by copper mold casting. The thermal properties and microstructural development during heat treatments were investigated by a combination of differential scanning calorimetry (DSC), differential thermal analysis, and X-ray diffractometry (XRD). The glass forming ability (GFA) and activation energy for crystallization have a distinct dependence on Mo content. Fe{sub 62}C{sub 10}B{sub 9}Mo{sub 12}Cr{sub 4}W{sub 3} is the best glass former in this study, demonstrating a supercooled liquid region, {delta}T{sub x} = 51 K, and an activation energy for crystallization, Q = 453 kJ/mol. The GFA of alloys in this system was governed by elastic strain optimization resulting directly from the variation in Mo content. Heat treatments were performed to demonstrate resistance to crystallization under typical processing conditions. Alloys in this system exhibited a three-phase evolution during crystallization. A second set of heat treatments was performed to identify each phase. Hardness data was collected at each of the heat treatment conditions, and a bulk metallic glasses (BMG)-derived composite containing a Mo-rich phase exhibited Vickers Hardness in excess of 2000. The fully amorphous alloys had an average hardness approaching 1500.

  6. 2nd Gen FeCrAl ODS Alloy Development For Accident-Tolerant Fuel Cladding

    Energy Technology Data Exchange (ETDEWEB)

    Dryepondt, Sebastien N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Massey, Caleb P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Edmondson, Philip D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-08-01

    Extensive research at ORNL aims at developing advanced low-Cr high strength FeCrAl alloys for accident tolerant fuel cladding. One task focuses on the fabrication of new low Cr oxide dispersion strengthened (ODS) FeCrAl alloys. The first Fe-12Cr-5Al+Y2O3 (+ ZrO2 or TiO2) ODS alloys exhibited excellent tensile strength up to 800 C and good oxidation resistance in steam up to 1400 C, but very limited plastic deformation at temperature ranging from room to 800 C. To improve alloy ductility, several fabrication parameters were considered. New Fe-10-12Cr-6Al gas-atomized powders containing 0.15 to 0.5wt% Zr were procured and ball milled for 10h, 20h or 40h with Y2O3. The resulting powder was then extruded at temperature ranging from 900 to 1050 C. Decreasing the ball milling time or increasing the extrusion temperature changed the alloy grain size leading to lower strength but enhanced ductility. Small variations of the Cr, Zr, O and N content did not seem to significantly impact the alloy tensile properties, and, overall, the 2nd gen ODS FeCrAl alloys showed significantly better ductility than the 1st gen alloys. Tube fabrication needed for fuel cladding will require cold or warm working associated with softening heat treatments, work was therefore initiated to assess the effect of these fabrications steps on the alloy microstructure and properties. This report has been submitted as fulfillment of milestone M3FT 16OR020202091 titled, Report on 2nd Gen FeCrAl ODS Alloy Development for the Department of Energy Office of Nuclear Energy, Advanced Fuel Campaign of the Fuel Cycle R&D program.

  7. Anti-Invar properties and magnetic order in fcc Fe-Ni-C alloy

    International Nuclear Information System (INIS)

    Nadutov, V.M.; Kosintsev, S.G.; Svystunov, Ye.O.; Garamus, V.M.; Willumeit, R.; Eckerlebe, H.; Ericsson, T.; Annersten, H.

    2011-01-01

    Anti-Invar effect was revealed in the fcc Fe-25.3%Ni-0.73%C (wt%) alloy, which demonstrates high values of thermal expansion coefficient (TEC) (15-21)x10 -6 K -1 accompanied by almost temperature-insensitive behavior in temperature range of 122-525 K. Alloying with carbon considerably expanded the low temperature range of anti-Invar behavior in fcc Fe-Ni-based alloy. The Curie temperature of the alloy T C =195 K was determined on measurements of temperature dependences of magnetic susceptibility and saturation magnetization. The Moessbauer and small-angle neutron scattering (SANS) experiments on the fcc Fe-25.3%Ni-(0.73-0.78)%C alloys with the varying temperatures below and above the Curie point and in external magnetic field of 1.5-5 T were conducted. Low value of the Debye temperature Θ D =180 K was estimated using the temperature dependence of the integral intensity of Moessbauer spectra for specified temperature range. The inequality B eff =(0.7-0.9)B ext was obtained in external field Moessbauer measurement that points to antiferromagnetically coupled Fe atoms, which have a tendency to align their spins perpendicular to B ext . Nano length scale magnetic inhomogeneities nearby and far above T C were revealed, which assumed that it is caused by mixed antiferromagnetically and ferromagnetically coupled Fe atom spins. The anti-Invar behavior of Fe-Ni-C alloy is explained in terms of evolution of magnetic order with changing temperature resulting from thermally varied interspin interaction and decreasing stiffness of interatomic bond. - Highlights: → Anti-Invar effect was revealed in the fcc Fe-25.3%Ni-0.73%C (wt%) alloy. → Carbon expanded the temperature range of anti-Invar behavior in Fe-Ni-based alloy. → Moessbauer data point to mixed interspin interaction and low the Dedye temperature. → The SANS experiments reveal nano length scale magnetic inhomogeneities ≤6 nm. → Anti-Invar behavior of Fe-Ni-C alloy explained by thermally varied magnetic order.

  8. Co-reduction of Copper Smelting Slag and Nickel Laterite to Prepare Fe-Ni-Cu Alloy for Weathering Steel

    Science.gov (United States)

    Guo, Zhengqi; Pan, Jian; Zhu, Deqing; Zhang, Feng

    2018-02-01

    In this study, a new technique was proposed for the economical and environmentally friendly recovery of valuable metals from copper smelting slag while simultaneously upgrading nickel laterite through a co-reduction followed by wet magnetic separation process. Copper slag with a high FeO content can decrease the liquidus temperature of the SiO2-Al2O3-CaO-MgO system and facilitate formation of liquid phase in a co-reduction process with nickel laterite, which is beneficial for metallic particle growth. As a result, the recovery of Ni, Cu, and Fe was notably increased. A crude Fe-Ni-Cu alloy with 2.5% Ni, 1.1% Cu, and 87.9% Fe was produced, which can replace part of scrap steel, electrolytic copper, and nickel as the burden in the production of weathering steel by an electric arc furnace. The study further found that an appropriate proportion of copper slag and nickel laterite in the mixture is essential to enhance the reduction, acquire appropriate amounts of the liquid phase, and improve the growth of the metallic alloy grains. As a result, the liberation of alloy particles in the grinding process was effectively promoted and the metal recovery was increased significantly in the subsequent magnetic separation process.

  9. In-situ studies of the TGO growth stresses and the martensitic transformation in the B2 phase in commercial Pt-modified NiAl and NiCoCrAlY bond coat alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hovis, D.; Hu, L.; Reddy, A.; Heuer, A.H. [Dept. of Materials Science and Engineering, Case Western Reserve Univ., Cleveland, OH (United States); Paulikas, A.P.; Veal, B.W. [Materials Science Div., Argonne National Lab., Argonne, IL (United States)

    2007-12-15

    Oxide growth stresses were measured in situ at 1100 C on commercial Pt-modified NiAl and NiCoCrAlY bond coat alloys using synchrotron X-rays. Measurements were taken on samples that had no preoxidation, as well as on samples that had experienced 24 one-hour thermal exposures at 1150 C, a condition known to induce rumpling in the Pt-modified NiAl alloy, but not in the NiCoCrAlY alloy. The NiCoCrAlY alloy showed continuous stress relaxation under all conditions, whereas the Pt-modified NiAl alloys would typically stabilize at a fixed (often non-zero) stress suggesting a higher creep strength in the 'Thermally Grown Oxide' on the latter alloy, though the precise behavior was dependent on initial surface preparation. The formation of martensite in the Pt-modified NiAl alloys was also observed upon cooling and occurred at temperatures below 200 C for all of the samples observed. Based on existing models, this M{sub s} temperature is too low to account for the rumpling observed in these alloys. (orig.)

  10. Microstructure evolution and mechanical properties of Ti−22Al−25Nb alloy joints brazed with Ti−Ni−Nb alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y.; Cai, X.Q.; Yang, Z.W., E-mail: tjuyangzhenwen@163.com; Qiu, Q.W.; Wang, D.P.; Liu, Y.C.

    2016-10-01

    Ti{sub 45}Ni{sub 45}Nb{sub 10} (at.%) brazing alloy, fabricated by arc melting, was successfully used to braze Ti−22Al−25Nb (at.%) alloy. The microstructures of Ti{sub 45}Ni{sub 45}Nb{sub 10} brazing alloy and Ti−22Al−25Nb alloy brazed joints were analyzed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), electron backscatter diffraction (EBSD), and micro-area X-ray diffraction (XRD). The effects of the brazing parameters on the interfacial microstructure and mechanical properties of the Ti−22Al−25Nb alloy brazed joints were investigated. The results showed that the joint was primarily comprised of two characteristic zones: diffusion zone I and central zone II, and the reaction phases formed in the brazed joint were the B2, O, τ{sub 3}, and Ti{sub 2}Ni phase. The crystal orientation of B2 phase in diffusion zone I was consistent with that in the Ti−22Al−25Nb substrate. The O phase was precipitated from the B2 phase. As the brazing temperature or holding time increased, τ{sub 3} was gradually replaced by the B2 phase, and the Ti{sub 2}Ni phase decreased and ultimately disappeared. The maximum shear strength achieved at room temperature was 318 MPa when the joint was brazed at 1180 °C for 20 min, whereas it was 278 MPa at 650 °C. Crack primarily propagated in the τ{sub 3} compound, which was extremely hard and brittle, and partially traversed the B2 and O phases. - Highlights: • Ti{sub 45}Ni{sub 45}Nb{sub 10} alloy was successfully developed to braze Ti−22Al−25Nb alloy. • Ti−22Al−25Nb alloy was transformed from B2 phase into the O + B2 duplex phase after brazing. • Crystal orientation of B2 in joint was dependent on metal substrate. • Correlation between joint microstructure and mechanical properties was revealed. • Ti−22Al−25Nb brazed joint had excellent ambient and high temperature strength.

  11. Development of low-Cr ODS FeCrAl alloys for accident-tolerant fuel cladding

    Science.gov (United States)

    Dryepondt, Sebastien; Unocic, Kinga A.; Hoelzer, David T.; Massey, Caleb P.; Pint, Bruce A.

    2018-04-01

    Low-Cr oxide dispersion strengthened (ODS) FeCrAl alloys were developed as accident tolerant fuel cladding because of their excellent oxidation resistance at very high temperature, high strength and improved radiation tolerance. Fe-12Cr-5Al wt.% gas atomized powder was ball milled with Y2O3+FeO, Y2O3+ZrO2 or Y2O3+TiO2, and the resulting powders were extruded at 950 °C. The resulting fine grain structure, particularly for the Ti and Zr containing alloys, led to very high strength but limited ductility. Comparison with variants of commercial PM2000 (Fe-20Cr-5Al) highlighted the significant impact of the powder consolidation step on the alloy grain size and, therefore, on the alloy mechanical properties at T < 500 °C. These low-Cr compositions exhibited good oxidation resistance at 1400 °C in air and steam for 4 h but could not form a protective alumina scale at 1450 °C, similar to observations for fine grained PM2000 alloys. The effect of alloy grain size, Zr and Ti additions, and impurities on the alloy mechanical and oxidation behaviors are discussed.

  12. Capture cross sections for Cr, Fe and Ni

    International Nuclear Information System (INIS)

    Corvi, F.

    1990-01-01

    Since stainless steel represents about 25% of the volume of a fast power reactor, its constituent elements strongly influence its two main neutronic parameters: critical enrichment and breeding gain. Also, capture in the narrow p and d-wave resonances of Cr, Fe and Ni contributes as much as 10 to 15% of the Doppler coefficient of reactivity. Following sensitivity calculations, typical accuracy requirements in the energy range 0.1-100 keV are 5-10% for capture in Fe and 10-20% for capture in Ni and Cr. 11 refs, 2 tabs

  13. Microstructure and mechanical properties of FeCrAl alloys under heavy ion irradiations

    Science.gov (United States)

    Aydogan, E.; Weaver, J. S.; Maloy, S. A.; El-Atwani, O.; Wang, Y. Q.; Mara, N. A.

    2018-05-01

    FeCrAl ferritic alloys are excellent cladding candidates for accident tolerant fuel systems due to their high resistance to oxidation as a result of formation of a protective Al2O3 scale at high temperatures in steam. In this study, we report the irradiation response of the 10Cr and 13Cr FeCrAl cladding tubes under Fe2+ ion irradiation up to ∼16 dpa at 300 °C. Dislocation loop size, density and characteristics were determined using both two-beam bright field transmission electron microscopy and on-zone scanning transmission electron microscopy techniques. 10Cr (C06M2) tube has a lower dislocation density, larger grain size and a slightly weaker texture compared to the 13Cr (C36M3) tube before irradiation. After irradiation to 0.7 dpa and 16 dpa, the fraction of type sessile dislocations decreases with increasing Cr amount in the alloys. It has been found that there is neither void formation nor α‧ precipitation as a result of ion irradiations in either alloy. Therefore, dislocation loops were determined to be the only irradiation induced defects contributing to the hardening. Nanoindentation testing before the irradiation revealed that the average nanohardness of the C36M3 tube is higher than that of the C06M2 tube. The average nanohardness of irradiated tube samples saturated at 1.6-2.0 GPa hardening for both tubes between ∼3.4 dpa and ∼16 dpa. The hardening calculated based on transmission electron microscopy was found to be consistent with nanohardness measurements.

  14. Searching for Next Single-Phase High-Entropy Alloy Compositions

    Directory of Open Access Journals (Sweden)

    David E. Alman

    2013-10-01

    Full Text Available There has been considerable technological interest in high-entropy alloys (HEAs since the initial publications on the topic appeared in 2004. However, only several of the alloys investigated are truly single-phase solid solution compositions. These include the FCC alloys CoCrFeNi and CoCrFeMnNi based on 3d transition metals elements and BCC alloys NbMoTaW, NbMoTaVW, and HfNbTaTiZr based on refractory metals. The search for new single-phase HEAs compositions has been hindered by a lack of an effective scientific strategy for alloy design. This report shows that the chemical interactions and atomic diffusivities predicted from ab initio molecular dynamics simulations which are closely related to primary crystallization during solidification can be used to assist in identifying single phase high-entropy solid solution compositions. Further, combining these simulations with phase diagram calculations via the CALPHAD method and inspection of existing phase diagrams is an effective strategy to accelerate the discovery of new single-phase HEAs. This methodology was used to predict new single-phase HEA compositions. These are FCC alloys comprised of CoFeMnNi, CuNiPdPt and CuNiPdPtRh, and HCP alloys of CoOsReRu.

  15. Thermodynamic stability of oxides in the Ni-Cr-Fe system and stress corrosion crack growth kinetics of alloy 600 in primary water

    International Nuclear Information System (INIS)

    Caron, D.; Cassagne, T.; Daret, J.; Santarini, G.; Mazille, H.

    1999-01-01

    In the framework of the study of stress corrosion of alloy-600, a thermodynamical study of stoichiometric simple and mixed oxides of Ni-Cr-Fe system has been performed. This theoretical work shows that the oxidation of alloy-600 is dependent on temperature and on the quantity of dissolved hydrogen

  16. The chemical composition and parameters of production processes influence on structure and properties of W-Ni-Fe alloys

    International Nuclear Information System (INIS)

    Majewski, T.; Przetakiewicz, W.

    2000-01-01

    Tungsten heavy alloys, i.e. tungsten based metal-matrix composites are characterized by unique properties, because except their high hardness, strength and density, they also possess excellent ductility, impact strength, machinability and corrosion resistance. This combination of properties makes these alloys suitable for wide range of engineering applications, e.g. in the mechanical engineering, in the mining, sport and medicine and also in the armament and aviation. Production process of these materials consists of many phases and it is very difficult to accomplish, because properties of heavy alloys are extremely sensitive to processing history. In this article dependence of chemical composition of mixture of powders on structure and mechanical properties of W-Ni-Fe alloys was determined. It was found that increase of tungsten contents and Ni/Fe ratio causes reduction of ductility and increase of growth rate of tungsten particle. There is the maximum ultimate tensile strength of W-Ni-Fe alloys with content of tungsten 93%. The study also presents relationship between these properties and succeeding parameters of production process: composition of sintering atmosphere, time and temperature following heat treatment and plastic working. Using a wet hydrogen atmosphere (with high dew point) causes reduction of porosity and improvement of mechanical properties. With sintering temperature above 1500 o C these parameters decrease. If the sintering time is elongated above 1 h also density and mechanical properties of heavy alloys decrease. Tungsten heavy alloys are also used for production of kinetic energy penetrators and so properties for different range of strain rates were compared. It was found that yield and failure strengths increase with increasing strain rate, failure strain decreases with increasing strain rate. This information can help in optimization the production process of such composites. (author)

  17. Moessbauer and XRD study of pulse plated Fe-P and Fe-Ni thin layers

    Energy Technology Data Exchange (ETDEWEB)

    Miko, Annamaria [Bay Zoltan Institute for Material Science (Hungary); Kuzmann, Erno, E-mail: kuzmann@para.chem.elte.hu [Eoetvoes Lorand University, Research Group for Nuclear Methods in Structural Chemistry, Hungarian Academy of Sciences, Department of Nuclear Chemistry (Hungary); Lakatos-Varsanyi, Magda [Bay Zoltan Institute for Material Science (Hungary); Kakay, Attila [Research Institute for Solid State Physics and Optics (Hungary); Nagy, Ferenc [Eoetvoes Lorand University, Research Group for Nuclear Methods in Structural Chemistry, Hungarian Academy of Sciences, Department of Nuclear Chemistry (Hungary); Varga, Lajos Karoly [Research Institute for Solid State Physics and Optics (Hungary)

    2005-09-15

    {sup 57}Fe conversion electron Moessbauer spectroscopy, X-ray diffraction, electrochemical and magnetic measurements were used to study pulse electroplated Fe-P and Ni-Fe coatings. XRD and {sup 57}Fe CEMS measurements revealed the amorphous character of the novel pulse plated Fe-P alloys. CEM spectra indicated significant differences in the short range order and in the magnetic anisotropy between the Fe-P deposits pulse plated at medium long deposition time (t{sub on} = 2 ms), with short relaxation time (t{sub off} = 9 ms) and low current density (I{sub p} = 0.05 Acm{sup -2}) or at short deposition time (t{sub on} = 1 ms) with long relaxation time (t{sub off} = 250 ms) and high current density (I{sub p} = 1.0 Acm{sup -2}). The broad peaks centred around the fcc reflections in XRD of the pulse plated Ni-22 wt.% Fe deposit reflected a microcrystalline Ni-Fe alloy with a very fine, 5-8 nm, grain size. The CEM spectrum of the pulse plated Ni-22 wt.% Fe coating corresponded to a highly disordered solid solution alloy containing a minute amount of ferrihydrite. Extreme favourable soft magnetic properties were observed with these Ni-Fe and Fe-P pulse plated thin layers.

  18. Investigation of phase stability of novel equiatomic FeCoNiCuZn based-high entropy alloy prepared by mechanical alloying

    Science.gov (United States)

    Soni, Vinay Kumar; Sanyal, S.; Sinha, S. K.

    2018-05-01

    The present work reports the structural and phase stability analysis of equiatomic FeCoNiCuZn High entropy alloy (HEA) systems prepared by mechanical alloying (MA) method. In this research effort some 1287 alloy combinations were extensively studied to arrive at most favourable combination. FeCoNiCuZn based alloy system was selected on the basis of physiochemical parameters such as enthalpy of mixing (ΔHmix), entropy of mixing (ΔSmix), atomic size difference (ΔX) and valence electron concentration (VEC) such that it fulfils the formation criteria of stable multi component high entropy alloy system. In this context, we have investigated the effect of novel alloying addition in view of microstructure and phase formation aspect. XRD plots of the MA samples shows the formation of stable solid solution with FCC (Face Cantered Cubic) after 20 hr of milling time and no indication of any amorphous or intermetallic phase formation. Our results are in good agreement with calculation and analysis done on the basis of physiochemical parameters during selection of constituent elements of HEA.

  19. Magnetic nanowires (Fe, Fe-Co, Fe-Ni – magnetic moment reorientation in respect of wires composition

    Directory of Open Access Journals (Sweden)

    Kalska-Szostko Beata

    2015-03-01

    Full Text Available Magnetic nanowires of Fe, Fe-Co, and Fe-Ni alloy and layered structure were prepared by electrochemical alternating current (AC deposition method. The morphology of the nanowires in and without the matrix was studied by energy dispersive X-ray spectroscopy (EDX, scanning electron microscopy (SEM, and X-ray diffraction (XRD, respectively. The wires either show strong dependence on the combination of elements deposition (alloy or layered or chemical composition (Co or Ni. The magnetic properties of the nanostructures were determined on the basis of Mössbauer spectroscopy (MS.

  20. Comparative study of the microstructures and mechanical properties of direct laser fabricated and arc-melted Al{sub x}CoCrFeNi high entropy alloys

    Energy Technology Data Exchange (ETDEWEB)

    Joseph, Jithin, E-mail: jithin@deakin.edu.au [Institute for Frontier Materials, Deakin University, Waurn Ponds 3216 (Australia); Jarvis, Tom; Wu, Xinhua [Monash Centre for Additive Manufacturing, Monash University, Clayton 3168 (Australia); Stanford, Nicole; Hodgson, Peter; Fabijanic, Daniel Mark [Institute for Frontier Materials, Deakin University, Waurn Ponds 3216 (Australia)

    2015-05-01

    High entropy alloys (HEA) are a relatively new metal alloy system that have promising potential in high temperature applications. These multi-component alloys are typically produced by arc-melting, requiring several remelts to achieve chemical homogeneity. Direct laser fabrication (DLF) is a rapid prototyping technique, which produces complex components from alloy powder by selectively melting micron-sized powder in successive layers. However, studies of the fabrication of complex alloys from simple elemental powder blends are sparse. In this study, DLF was employed to fabricate bulk samples of three alloys based on the Al{sub x}CoCrFeNi HEA system, where x was 0.3, 0.6 and 0.85 M fraction of Al. This produced FCC, FCC/BCC and BCC crystal structures, respectively. Corresponding alloys were also produced by arc-melting, and all microstructures were characterised and compared longitudinal and transverse to the build/solidification direction by x-ray diffraction, glow discharge optical emission spectroscopy and scanning electron microscopy (EDX and EBSD). Strong similarities were observed between the single phase FCC and BCC alloys produced by both techniques, however the FCC/BCC structures differed significantly. This has been attributed to a difference in the solidification rate and thermal gradient in the melt pool between the two different techniques. Room temperature compression testing showed very similar mechanical behaviour and properties for the two different processing routes. DLF was concluded to be a successful technique to manufacture bulk HEA's.

  1. Microstructural characterization of Y2O3 ODS-Fe-Cr model alloys

    International Nuclear Information System (INIS)

    Castro, V. de; Leguey, T.; Munoz, A.; Monge, M.A.; Pareja, R.; Marquis, E.A.; Lozano-Perez, S.; Jenkins, M.L.

    2009-01-01

    Two Fe-12 wt% Cr alloys, one containing 0.4 wt% Y 2 O 3 and the other Y 2 O 3 -free, have been produced by mechanical alloying followed by hot isostatic pressing. These oxide dispersion strengthened and reference alloys were characterized both in the as-HIPed state and after tempering by transmission electron microscopy and atom-probe tomography. The as-HIPed alloys exhibited the characteristic microstructure of lath martensite and contained a high density of dislocations. Small voids with sizes 3 C and M 23 C 6 carbides (M = Cr, Fe) probably as a result of C ingress during milling. After tempering at 1023 K for 4 h the microstructures had partially recovered. In the recovered regions, martensite laths were replaced by equiaxed grains in which M 23 C 6 carbides decorated the grain boundaries. In the ODS alloy nanoparticles containing Y were commonly observed within grains, although they were also present at grain boundaries and adjacent to large carbides.

  2. Distribution of Cr atoms in the surface zone of Fe-rich Fe–Cr alloys quenched into various media: Mössbauer spectroscopic study

    International Nuclear Information System (INIS)

    Dubiel, Stanisław M.; Cieślak, Jakub; Żukrowski, Jan

    2015-01-01

    Graphical abstract: Chromium depletion, Δx = x_k − x, in Fe_1_0_0_−_xCr_x (x = 2.2, 3.9, 6.4, 8.5, 10.25, 10.75, 14.9, 15.15) alloys quenched into LN (left panel) and those quenched onto brass (right panel) as found from CEMS (pre surface zone) and TRANS (bulk) Mössbauer spectra (x_k – Cr content in the pre surface or bulk as estimated from the average hyperfine field found for the quenched samples). - Highlights: • Effect of quenching media on Cr atom distribution in Fe–Cr alloys was determined. • Significant differences between bulk and pre surface zone were revealed. • Quenching into water and LH resulted in surface oxidation of samples. • Samples quenched onto a block of brass were not oxidized. - Abstract: Effect of a quenching medium (water, liquid nitrogen and block of brass) on a distribution of Cr atoms in the surface zone of Fe_1_0_0_−_xCr_x (x ≤ 19) alloys was studied with the Mössbauer spectroscopy. The distribution of Cr atoms was expressed in terms of the Cowley–Warren short-range order (SRO) parameters: 〈α_1〉 for the first neighbor-shell, 〈α_2〉 for the second neighbor-shell and 〈α_1_2〉 for both neighbor-shells. It was revealed that none of the quenching media resulted in a random distribution of atoms, yet the degree of randomness was the highest for the samples quenched onto the block of brass. The quenching into water and liquid nitrogen caused a partial oxidation of samples’ surface accompanied by a chromium depletion of the bulk. Quantitative analysis of various phases in the studied samples both in their bulk as well as in pre surface zones was carried out.

  3. The thermodynamic stability induced by solute co-segregation in nanocrystalline ternary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Tao; Chen, Zheng; Zhang, Jinyong; Zhang, Ping [China Univ. of Mining and Technology, Xuzhou (China). School of Mateial Science and Engineering; Yang, Xiaoqin [China Univ. of Mining and Technology, Xuzhou (China). School of Chemical Engineering and Technology

    2017-06-15

    The grain growth and thermodynamic stability induced by solute co-segregation in ternary alloys are presented. Grain growth behavior of the single-phase supersaturated grains prepared in Ni-Fe-Pb alloy melt at different undercoolings was investigated by performing isothermal annealings at T = 400 C-800 C. Combining the multicomponent Gibbs adsorption equation and Guttmann's grain boundary segregation model, an empirical relation for isothermal grain growth was derived. By application of the model to grain growth in Ni-Fe-Pb, Fe-Cr-Zr and Fe-Ni-Zr alloys, it was predicted that driving grain boundary energy to zero is possible in alloys due to the co-segregation induced by the interactive effect between the solutes Fe/Pb, Zr/Ni and Zr/Cr. A non-linear relationship rather than a simple linear relation between 1/D* (D* the metastable equilibrium grain size) and ln(T) was predicted due to the interactive effect.

  4. Shape of growing crystals of primary phases in autectic alloys of Fe - Fe2B and Ni - Ni3B systems

    International Nuclear Information System (INIS)

    Tavadze, F.N.; Garibashvili, V.I.; Nakaidze, Sh.G.

    1983-01-01

    Shapes of Fe 2 B and Ni 3 B crystal growth in eutectic Fe-B and Ni-B system alloys are considered. Iron hemiboride primary crystals take the form of a plane-face phase boundary and inherit a tetragonal prismatic lattice. After the crystal attains the critical size the dendritic branching occurs resulting in formation of a typical sceleton dendrite. Comparison of data obtained with entropy of melting for Fe 2 B and Ni 3 B borides shows that FeB crystals during the growth should take the spherical form. It is stated that the shape of growing crystals in Fe-Fe 2 B and Ni-Ni 2 B eutectic colonies is determined by the shape of borides

  5. Crevice Corrosion on Ni-Cr-Mo Alloys

    International Nuclear Information System (INIS)

    P. Jakupi; D. Zagidulin; J.J. Noel; D.W. Shoesmith

    2006-01-01

    Ni-Cr-Mo alloys were developed for their exceptional corrosion resistance in a variety of extreme corrosive environments. An alloy from this series, Alloy-22, has been selected as the reference material for the fabrication of nuclear waste containers in the proposed Yucca Mountain repository located in Nevada (US). A possible localized corrosion process under the anticipated conditions at this location is crevice corrosion. therefore, it is necessary to assess how this process may, or may not, propagate if the use of this alloy is to be justified. Consequently, the primary objective is the development of a crevice corrosion damage function that can be used to assess the evolution of material penetration rates. They have been using various electrochemical methods such as potentiostatic, galvanostatic and galvanic coupling techniques. Corrosion damage patterns have been investigated using surface analysis techniques such as scanning electron microscopy (SEM) and optical microscopy. All crevice corrosion experiments were performed at 120 C in 5M NaCl solution. Initiating crevice corrosion on these alloys has proven to be difficult; therefore, they have forced it to occur under either potentiostatic or galvanostatic conditions

  6. Effect of Ni interlayer on diffusion bonding of a W alloy and a Ta alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jian; Liu, Ruxia; Wei, Qinqin; Luo, Guoqiang; Shen, Qiang; Zhang, Lianmeng [Wuhan Univ. of Technology (China). The State Key Lab. of Advanced Technology for Materials Synthesis and Processing

    2017-11-01

    The combination of W and Ta is expected to be highly beneficial for many applications from aerospace, weapons, military and nuclear industry. In this paper, W and Ta alloys were successfully diffusion bonded with Ni interlayer. The process of the formation of W/Ni/Ta diffusion bonded joints was investigated by means of scanning electron microscopy, X-ray diffraction system, electron probe micro-analyzer, energy dispersive spectrometry and shear strength measurement. The results show that the shear strength increases when the bonding temperature increases and exhibits a maximum value of 244 MPa at 930 C. The bonding of W/Ni can be attributed to the bonding of Ni to tungsten grains and the bonding of Ni to a Ni-Fe-binder mainly by elemental diffusion. The fracture takes place in the Ni/Ta interface and Ni{sub 3}Ta and Ni{sub 2}Ta intermetallic compounds are formed on the fracture surfaces.

  7. Microstructure of ordered (Co078Fe022)3V alloy

    International Nuclear Information System (INIS)

    Braski, D.N.; Carpenter, R.W.; Bentley, J.

    1981-05-01

    The (Co 0 78 Fe 0 22 ) 3 V alloy belongs to a class of long-range-ordered alloys that are being developed for elevated-temperature applications. The microstructure after quenching and after subsequent aging at temperatures between 973 and 1073 0 K has been characterized by analytical electron microscopy. Short-range order (SRO) and small VC matrix precipitate particles were observed in the as-quenched material. At 973 0 K VC precipitated discontinuously in grain boundaries and on extrinsic stacking faults. Aging at 1073 0 K precipitated VC in grain boundaries and on extrinsic stacking faults, and produced intrinsic stacking faults that were precipitate-free. Ordered domains grew upon aging at rates proportional to t/sup 1/2/; the activation energy for growth was 222 +- 20 J/mol. Thermal antiphase boundaries (APBs) had isotropic energies and (a/2) displacement vectors. Intrinsic and extrinsic stacking faults also serve as APBs, with displacement vectors of (a/6) and (a/3) , respectively

  8. Density and Structure Analysis of Molten Ni-W Alloys

    Institute of Scientific and Technical Information of China (English)

    Feng XIAO; Liang FANG

    2004-01-01

    Density of molten Ni and Ni-W alloys was measured in the temperature range of 1773~1873 K with a sessile drop method.The density of molten Ni and Ni-W alloys trends to decrease with increasing temperature. The density and molar volume of the alloys trend to increase with increasing W concentration in the alloys. The calculation result shows an ideal mixing of Ni-W alloys.

  9. Research on low strain magnetic mechanical hysteresis damping performance of Fe-15Cr-3Mo-0.5Si alloy

    International Nuclear Information System (INIS)

    Wang, Hui; Huang, Huawei; Hong, Xiaofeng; Yin, Changgeng; Huang, Zhaohua; Chen, Le

    2015-01-01

    Highlights: • Heat treatment system has a great effect on the alloy damping performance. • Damping performance does not improve monotonously with temperature. • Furnace cooling is higher than that of alloy after air cooling. • There is an optimum annealing temperature and grain size to obtain high damping. - Abstract: This paper studies the preparation of Fe-15Cr-3Mo-0.5Si alloy by using vacuum induction melting furnace and vacuum annealing furnace, the damping performance of which in different heat treatment states is tested with dynamic mechanical thermal analyzer (DMA). Through microstructure observation with metallographic microscope (OM), grain boundary observation with scanning electron microscopy (SEM), phase structure analysis with X-ray diffraction (XRD) and internal stress of S-B model analysis, the effect law of annealing temperature, types of cooling, holding time and grain sizes on the damping performance of alloy and the related mechanism can be concluded as follows. The annealing temperature and grain sizes have a significant impact on the damping strain amplitude as well as the magnetic and mechanical damping performance of this ferromagnetic alloy. Proper annealing temperature and grain size is the necessary condition to get high damping performance of the alloy. It is not conducive to improvement of the damping performance if the annealing temperature is too high or too low and the grain size is too small or too large. For Fe-15Cr-3Mo-0.5Si alloy, within the range of the low strain amplitude, alloy damping performance does not improve monotonously with the increase of the annealing temperature and grain size. The maximum value appears at the annealing temperature of 1100 °C/1 h with the grain size of about 300 μm. At high annealing temperature of 1100 °C, the damping performance of alloy in the slow cooling furnace is higher than that with air cooling treatment. The extension or shortening of the holding time, to a certain extent

  10. Research on low strain magnetic mechanical hysteresis damping performance of Fe-15Cr-3Mo-0.5Si alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hui, E-mail: qinghe5525@163.com; Huang, Huawei; Hong, Xiaofeng; Yin, Changgeng; Huang, Zhaohua; Chen, Le

    2015-02-15

    Highlights: • Heat treatment system has a great effect on the alloy damping performance. • Damping performance does not improve monotonously with temperature. • Furnace cooling is higher than that of alloy after air cooling. • There is an optimum annealing temperature and grain size to obtain high damping. - Abstract: This paper studies the preparation of Fe-15Cr-3Mo-0.5Si alloy by using vacuum induction melting furnace and vacuum annealing furnace, the damping performance of which in different heat treatment states is tested with dynamic mechanical thermal analyzer (DMA). Through microstructure observation with metallographic microscope (OM), grain boundary observation with scanning electron microscopy (SEM), phase structure analysis with X-ray diffraction (XRD) and internal stress of S-B model analysis, the effect law of annealing temperature, types of cooling, holding time and grain sizes on the damping performance of alloy and the related mechanism can be concluded as follows. The annealing temperature and grain sizes have a significant impact on the damping strain amplitude as well as the magnetic and mechanical damping performance of this ferromagnetic alloy. Proper annealing temperature and grain size is the necessary condition to get high damping performance of the alloy. It is not conducive to improvement of the damping performance if the annealing temperature is too high or too low and the grain size is too small or too large. For Fe-15Cr-3Mo-0.5Si alloy, within the range of the low strain amplitude, alloy damping performance does not improve monotonously with the increase of the annealing temperature and grain size. The maximum value appears at the annealing temperature of 1100 °C/1 h with the grain size of about 300 μm. At high annealing temperature of 1100 °C, the damping performance of alloy in the slow cooling furnace is higher than that with air cooling treatment. The extension or shortening of the holding time, to a certain extent

  11. Chromium Extraction via Chemical Processing of Fe-Cr Alloys Fine Powder with High Carbon Content

    Science.gov (United States)

    Torres, D. M.; Navarro, R. C. S.; Souza, R. F. M.; Brocchi, E. A.

    2017-06-01

    Ferrous alloys are important raw materials for special steel production. In this context, alloys from the Fe-Cr system, with typical Cr weight fraction ranging from 0.45 to 0.95, are prominent, particularly for the stainless steel industry. During the process in which these alloys are obtained, there is considerable production of fine powder, which could be reused after suitable chemical treatment, for example, through coupling pyrometallurgical and hydrometallurgical processes. In the present study, the extraction of chromium from fine powder generated during the production of a Fe-Cr alloy with high C content was investigated. Roasting reactions were performed at 1073 K, 1173 K, and 1273 K (800 °C, 900 °C, and 1000 °C) with 300 pct (w/w) excess NaOH in an oxidizing atmosphere (air), followed by solubilization in deionized water, selective precipitation, and subsequent calcination at 1173 K (900 °C) in order to convert the obtained chromium hydroxide to Cr2O3. The maximum achieved Cr recovery was around 86 pct, suggesting that the proposed chemical route was satisfactory regarding the extraction of the chromium initially present. Moreover, after X-ray diffraction analysis, the final produced oxide has proven to be pure Cr2O3 with a mean crystallite size of 200 nm.

  12. Molecular dynamics study on threshold displacement energies in Fe-Cr alloys

    Science.gov (United States)

    Fu, Jiawei; Ding, Wenyi; Zheng, Mingjie; Mao, Xiaodong

    2018-03-01

    The threshold displacement energies (Ed) of Fe and Cr atoms in Fe-Cr alloys with Cr contents ranging from 0% to 21% have been obtained with molecular dynamics (MD) method. The values of Ed have been calculated along the three high-symmetry crystallographic directions [0 0 1], [0 1 1] and [1 1 1], a slightly 2° tilt from these directions, and a high-index crystallographic directions [1 3 5]. The results showed that [0 1 1] crystallographic direction had the highest Ed among the three high-symmetry directions in each Cr content alloy. Fe-9Cr had higher weighted average Ed than the other Cr content alloys for both Fe and Cr PKA due to its statistically high Ed along the [0 1 1] crystallographic direction up to 44.3 eV. And the statistical analysis on the primary damage configuration demonstrated that 〈1 1 0〉Fe-Fe dumbbells were the dominant defect structures after relaxation. These data can enrich the database of Ed in Fe-Cr alloys and have potential applications in guiding the optimization design of radiation-resistant RAFM steels.

  13. Processing and characterization of AlCoFeNiXTi{sub 0,5} (X = Mn, V) high entropy alloys; Processamento e caracterizacao de ligas de alta entropia AlCoFeNixTi{sub 0,5} (X = Mn, V)

    Energy Technology Data Exchange (ETDEWEB)

    Triveno Rios, C., E-mail: carlos.triveno@ufabc.edu.br [Universidade Federal do ABC (CECS/UFABC), Santo Andre, SP (Brazil). Engenharia de Materiais; Lopes, E.S.N.; Caram, R. [Universidade Estadual de Campinas (FEM/DEMA/UNICAMP), Campinas, SP (Brazil); Kiminami, C.S. [Universidade Federal de Sao Carlos (DEMa/UFSCar), Sao Carlos, SP (Brazil). Departamento de Engenharia de Materiais

    2014-07-01

    The microstructure of high entropy alloys consists of solid solution phases with FC and BCC simple structures, contrary to classical metallurgy where they form complex structures of intermetallic compounds. Because of this they have several attractive properties for engineering applications. In this work the AlCoFeNiMnTi{sub 0,5} and AlCoFeNiVTi{sub 0,5} alloys were processed by melting arc. Since the main objective was the microstructural and mechanical characterization of ingots as-cast. The alloys were characterized by scanning electron microscopy, X-ray diffraction, microhardness and cold compression test. The results showed that the microstructure consists mainly of dendrites and interdendritic regions consisting of metastable crystalline phases. It was also observed that the AlCoFeNiVTi{sub 0,5} alloy showed better mechanical properties than the AlCoFeNiMnTi{sub 0,5} alloy. This may be associated with differences in the parameters of formation of simple solid solution phases between the two alloys. (author)

  14. Microstructure and interfacial evaluation of Co-based alloy coating on copper by pulsed Nd:YAG multilayer laser cladding

    International Nuclear Information System (INIS)

    Yan Hua; Wang Aihua; Xu Kaidong; Wang Wenyan; Huang Zaowen

    2010-01-01

    Laser cladding defect-free coatings on copper is rather difficult. The purpose of this study is to fabricate high quality Co-based alloy coating on copper substrate by laser cladding. Powder preplacement with a thickness of 0.7 mm improves the absorptivity of copper substrate to laser effectively and generates defect-free coating. Microstructures, phase constitutions and wear properties are investigated by means of scanning electronic microscopy (SEM) with X-ray energy dispersive microanalysis (EDX), transmission electron microscopy (TEM) and X-ray diffraction (XRD), as well as dry sliding wear test. Experimental results show that α-Co solution, Cr 23 C 6 , Ni 17 W 3 and Cr 4 Ni 15 W are the main phases in the Co-based coating. The Ni-based solid solutions (α-Co, Ni) and (Ni, Cu) are formed at interface, which generate metallurgical bonding by diffusion between Co-based coating and copper substrate. The average microhardness of the coating is 478HV 0.1 . Wear resistance of copper is significantly improved by laser cladding Co-based alloy multilayer coating.

  15. Characterization on the coatings of Ni-base alloy with nano- and micron-size Sm2O3 addition prepared by laser deposition

    International Nuclear Information System (INIS)

    Zhang Shihong; Li Mingxi; Yoon, Jae Hong; Cho, Tong Yul

    2008-01-01

    The coating materials are the powder mixture of micron-size Ni-base alloy powders with both 1.5 wt.% micron-size and nano-size Sm 2 O 3 powders, which are prepared on Q235 steel plate by 2.0 kW CO 2 laser deposition. The results indicate that with rare earth oxide Sm 2 O 3 addition, the width of planar crystallization is smaller than that of the Ni-base alloy coatings. Micron- and nano-Sm 2 O 3 /Ni-base alloy coatings have similar microstructure showing the primary phase of γ-Ni dendrite and eutectic containing γ-Ni and Cr 23 C 6 phases. However, compared to micron-Sm 2 O 3 /Ni-base alloy, preferred orientation of γ-Ni dendrite of nano-Sm 2 O 3 /Ni-base alloy is weakened. Planar crystal of several-μm thickness is first grown and then dendrite growth is observed at 1.5% micron-Sm 2 O 3 /Ni-base alloy coating whereas equiaxed dendrite is grown at 1.5% nano-Sm 2 O 3 /Ni-base alloy coating. Hardness and wear resistance of the coating improves with decreasing Sm 2 O 3 size from micron to nano. The improvement on tribological property of nano-Sm 2 O 3 /Ni-base alloy over micron-Sm 2 O 3 /Ni-base alloy coatings can be attributed to the better resistance of equiaxed dendrite to adhesion interactions during the wear process. In 6 M HNO 3 solution, the corrosion resistance is greatly improved with nano-Sm 2 O 3 addition since the decrease of corrosion ratio along grain-boundary in nano-Sm 2 O 3 /Ni-base alloy coating contributes to harmonization of corrosion potential

  16. Characterization of dissimilar welding: carbon steel E309L-E308L-ERNiCr3-ENiCrFe3 alloy 600

    International Nuclear Information System (INIS)

    Mucino G, O.

    2015-01-01

    Most BWR type reactors have internal support components, which need to be attached to the inner surface by welding. Specifically, in these joints two materials interact, such as stainless steel and nickel base alloys. Nickel base alloys such as alloy 82 (ERNiCr3) and alloy 182 (ENiCrFe-3) are used for the joining of both dissimilar materials. For joints made with both nickel base alloys, the alloy 182 is prone to stress corrosion cracking (SCC); so it is essential to carry out studies related to this contribution material. In the nuclear industry any study related to this alloy is of importance because experience is gained in its behavior when is part of a system of an operation reactor. This work presents the characterization of the weld deposit of a stainless steel coating (with electrodes E309L and E308L) on a carbon steel plate type A36 and the joining with an Inconel 600 plate, simulating the joining of the internal coating of vessel and the heel of the support leg of the envelope of a BWR reactor. In this work, the mechanical and micro-structural characterization of the alloy deposit 182 was performed. (Author)

  17. Microstructural characterization of a rapidly solidified ultrahigh strength Al94.5Cr3Co1.5Ce1 alloy

    International Nuclear Information System (INIS)

    Ping, D.H.; Hono, K.; Inoue, A.

    2000-01-01

    The microstructure of a rapidly solidified Al 94.5 Cr 3 Co 1.5 Ce 1 alloy has been examined in detail by means of high resolution transmission electron microscopy (HRTEM) and atom probe field ion microscopy (APFIM). In the as-quenched microstructure, nanoscale particles of a solute-enriched amorphous phase and an Al-Cr compound are dispersed in randomly oriented fine grains of α-Al ( 200nm ). The interface between the Al grains and the amorphous particles is not smooth but irregular with atomic protrusions and concavities, suggesting that interfacial instability occurs during the solidification process. Nanoscale amorphous particles are formed as a result of solute trapping within the rapidly grown Al grains. After annealing at 400 C for 15 minutes grain growth occurs, and the interface of the Al grains is smoothed. The amorphous region trapped within the grains if crystallized to an Al-Cr compound, but no icosahedral phase has been confirmed. The APFIM results have revealed that Cr and Ce atoms have a similar partitioning behavior, i.e., they are rejected from the α-Al phase and partitioned into the trapped amorphous regions. On the other hand, Co atoms are not partitioned between the two phases in the as-quenched state but are partitioned into the α-Al grains in the annealed alloys being rejected from the Al compounds and finally form Al-Co compounds. Based on these microstructural characterization results, the origins of high strength of this alloy are discussed

  18. Effects of annealing on the microstructure and magnetic property of the mechanically alloyed FeSiBAlNiM (M=Co, Cu, Ag) amorphous high entropy alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Xiaoxia; Zhou, Xuan; Yu, Shuaishuai; Wei, Congcong; Xu, Jing; Wang, Yan, E-mail: mse_wangy@ujn.edu.cn

    2017-05-15

    The effects of annealing treatment on the microstructure, thermal stability, and magnetic properties of the mechanical alloyed FeSiBAlNiM (M=Co, Cu, Ag) amorphous high entropy alloys (HEAs) have been investigated in this project. The simple crystallization products in FeSiBAlNi amorphous HEAs with Co and Ag addition reveal the high phase stability during heating process. At high annealing treatment, the crystallized HEAs possess the good semi-hard magnetic property. It can conclude that crystallization products containing proper FeSi-rich and FeB-rich phases are beneficial to improve the magnetic property. Annealing near the exothermic peak temperature presents the best enhancing effect on the semi-hard magnetic property of FeSiBAlNiCo. It performs both large saturated magnetization and remanence ratio of 13.0 emu/g and near 45%, which exhibit 465% and 105% enhancement compared with as-milled state, respectively. - Highlights: • Co, Cu, Ag additions affect crystallization behavior of FeSiBAlNi amorphous HEAs. • Crystallization products in FeSiBAlNi Co/Ag reveal high phase stability. • Proper FeSi-rich and FeB-rich phases are beneficial to improve magnetic property. • Annealing treatment improves semi-hard magnetic property compared to as-milled state. • Annealing near exothermic peak temperature shows best enhancing effect on magnetism.

  19. Simultaneous aluminizing and chromizing of steels to form (Fe,Cr){sub 3}Al coatings and Ge-doped silicide coatings of Cr-Zr base alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, M.; He, Y.R.; Rapp, R.A. [Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering

    1997-12-01

    A halide-activated cementation pack involving elemental Al and Cr powders has been used to achieve surface compositions of approximately Fe{sub 3}Al plus several percent Cr for low alloy steels (T11, T2 and T22) and medium carbon steel (1045 steel). A two-step treatment at 925 C and 1150 C yields the codeposition and diffusion of aluminum and chromium to form dense and uniform ferrite coatings of about 400 {micro}m thickness, while preventing the formation of a blocking chromium carbide at the substrate surfaces. Upon cyclic oxidation in air at 700 C, the coated steel exhibits a negligible 0.085 mg/cm{sup 2} weight gain for 1900 one-hour cycles. Virtually no attack was observed on coated steels tested at ABB in simulated boiler atmospheres at 500 C for 500 hours. But coatings with a surface composition of only 8 wt% Al and 6 wt% Cr suffered some sulfidation attack in simulated boiler atmospheres at temperatures higher than 500 C for 1000 hours. Two developmental Cr-Zr based Laves phase alloys (CN129-2 and CN117(Z)) were silicide/germanide coated. The cross-sections of the Ge-doped silicide coatings closely mimicked the microstructure of the substrate alloys. Cyclic oxidation in air at 1100 C showed that the Ge-doped silicide coating greatly improved the oxidation resistance of the Cr-Zr based alloys.

  20. Flow behavior and microstructures of powder metallurgical CrFeCoNiMo0.2 high entropy alloy during high temperature deformation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jiawen [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Liu, Yong, E-mail: yonliu@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Liu, Bin, E-mail: binliu@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Wang, Yan [School of Aeronautics and Astronautics, Central South University, Changsha 410083 (China); Cao, Yuankui; Li, Tianchen; Zhou, Rui [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China)

    2017-03-24

    Dynamic recrystallization (DRX) refine grains of high entropy alloys (HEAs) and significant improve the mechanical property of HEAs, but the effect of high melting point element molybdenum (Mo) on high temperature deformation behavior has not been fully understood. In the present study, flow behavior and microstructures of powder metallurgical CrFeCoNiMo{sub 0.2} HEA were investigated by hot compression tests performed at temperatures ranging from 700 to 1100 °C with strain rates from 10{sup −3} to 1 s{sup −1}. The Arrhenius constitutive equation with strain-dependent material constants was used for modeling and prediction of flow stress. It was found that at 700 °C, the dynamic recovery is the dominant softening mechanism, whilst with the increase in compression testing temperature, the DRX becomes the dominant mechanism of softening. In the present HEA, the addition of Mo results in the high activation energy (463 kJ mol{sup −1}) and the phase separation during hot deformation. The formation of Mo-rich σ phase particles pins grain boundary migration during DRX, and therefore refines the size of recrystallized grains.

  1. Change of Cr atoms distribution in Fe85Cr15 alloy caused by 250 keV He+ ion irradiation to different doses

    International Nuclear Information System (INIS)

    Dubiel, S.M.; Żukrowski, J.

    2015-01-01

    Highlights: • Effect of He-ion irradiation dose on Fe 85 Cr 15 alloy. • Irradiation-induced clustering of Cr atoms. • Irradiation-caused reorientation of the surface magnetization vector. • Irradiation-caused increase of Fe-site spin-density. - Abstract: Redistribution of Cr atoms in a Fe 85 Cr 15 alloy caused by its irradiation with 250 keV He + ions to different doses, D = 8 ⋅ 10 16 , 16 ⋅ 10 16 and 48 ⋅ 10 16 ions/cm 2 was investigated by means of conversion electrons Mössbauer spectroscopy. The redistribution was expressed in terms of the Warren–Cowley short-range order parameters α 1 , α 2 and α 12 pertaining to the first (1NN), second (2NN) and both i.e. 1NN + 2NN shells, respectively. Clear evidence was found, both for non-irradiated and irradiated samples that the actual distribution of Cr atoms is characteristic of the shell, and for a given shell it depends on the irradiation dose. In particular, α 1 is positive, hence indicates an under population of Cr atoms in 1NN with respect to the random case, α 2 is negative, giving evidence thereby that 2NN is overpopulated by Cr atoms, and α 12 is weakly positive. Under the applied irradiation the number of Cr atoms in both neighbor shells decreased signifying thereby a clustering of Cr atoms. The underlying decrease of Cr concentration within the 1NN–2NN volume around the probe Fe atoms was estimated at 1.5 at.% ranging between 2.1 for the lowest and 0.8 at.% for the highest dose

  2. The Effects of CO{sub 2} Pressure on Corrosion and Carburization Behaviors of Chromia-forming Austenitic Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ho Jung; Kim, Sung Hwan; Jang, Changheui [KAIST, Daejeon (Korea, Republic of)

    2015-05-15

    By applying S-CO{sub 2} cycle to SFR, the inherent safety could be improved by alleviating the concern of explosive reaction between high temperature steam and liquid sodium as well as increased thermal efficiency at 500-550 .deg. C compared to helium Brayton cycle. Meanwhile, from the material point of view, a compatibility such as corrosion and carburization of candidate materials in S-CO{sub 2} environment should be evaluated to assure the long-term integrity of IHX. It has been previously reported that Ni-base alloys and high-Cr Fe-base austenitic alloys showed a good corrosion resistance by the formation of thin chromia layer while carburization behaviors of those materials were not properly investigated. Corrosion and carburization behaviors of three chromia-forming austenitic alloys (Ni-base alloys and Alloy 800HT) were evaluated in S-CO{sub 2} (200 bar) and CO{sub 2} (1 bar) environment at 550.650 .deg. C for 1000 h. For all test materials, a good corrosion resistance was exhibited by the formation of thin chromia (Cr{sub 2}O{sub 3}) with small amount of minor oxides such as Mn1.5Cr1.5O{sub 4}, Al{sub 2}O{sub 3}, and TiO{sub 2}.

  3. Development of ODS FeCrAl alloys for accident-tolerant fuel cladding

    Energy Technology Data Exchange (ETDEWEB)

    Dryepondt, Sebastien N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Hoelzer, David T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Pint, Bruce A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Unocic, Kinga A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-09-18

    FeCrAl alloys are prime candidates for accident-tolerant fuel cladding due to their excellent oxidation resistance up to 1400 C and good mechanical properties at intermediate temperature. Former commercial oxide dispersion strengthened (ODS) FeCrAl alloys such as PM2000 exhibit significantly better tensile strength than wrought FeCrAl alloys, which would alloy for the fabrication of a very thin (~250 m) ODS FeCrAl cladding and limit the neutronic penalty from the replacement of Zr-based alloys by Fe-based alloys. Several Fe-12-Cr-5Al ODS alloys where therefore fabricated by ball milling FeCrAl powders with Y2O3 and additional oxides such as TiO2 or ZrO2. The new Fe-12Cr-5Al ODS alloys showed excellent tensile strength up to 800 C but limited ductility. Good oxidation resistance in steam at 1200 and 1400 C was observed except for one ODS FeCrAl alloy containing Ti. Rolling trials were conducted at 300, 600 C and 800 C to simulate the fabrication of thin tube cladding and a plate thickness of ~0.6mm was reached before the formation of multiple edge cracks. Hardness measurements at different stages of the rolling process, before and after annealing for 1h at 1000 C, showed that a thinner plate thickness could likely be achieved by using a multi-step approach combining warm rolling and high temperature annealing. Finally, new Fe-10-12Cr-5.5-6Al-Z gas atomized powders have been purchased to fabricate the second generation of low-Cr ODS FeCrAl alloys. The main goals are to assess the effect of O, C, N and Zr contents on the ODS FeCrAl microstructure and mechanical properties, and to optimize the fabrication process to improve the ductility of the 2nd gen ODS FeCrAl while maintaining good mechanical strength and oxidation resistance.

  4. Development of Ultra-high Purity (UHP) Fe-Based Alloys with High Creep and Oxidation Resistance for A-USC Technology

    Science.gov (United States)

    Hamdani, Fethi; Das, Nishith K.; Shoji, Tetsuo

    2018-06-01

    The design of ultra-high purity (UHP) Fe-based model alloys for advanced ultra-supercritical (A-USC) technology is attempted in this work. Creep testing has been performed in air at 700 °C and a stress level of 150 MPa. Analysis of the fracture surface and cross section of the crept specimen was performed. To evaluate the oxidation resistance in A-USC conditions, oxidation testing was performed in supercritical water (SCW) at 700 °C and 25 MPa. Weight gain (WG) measurements and meticulous characterization of the oxide scale were carried out. Based on thermodynamics and density functional theory calculations, some reactive elements in the Fe-Cr-Ni system were designated to promote precipitation strengthening and to improve the hydrogen-accelerated oxidation resistance. The addition of a 2 wt pct Mo into Fe-22Cr-22Ni-0.6Nb wt pct-based matrix did not significantly improve the creep resistance. The addition of 0.26 wt pct Zr coupled with cold working was effective for improving creep properties. The Mo-modified model alloy showed almost the same WG value as SUS310, while the Zr-modified alloy showed a higher WG value. Meanwhile, a Cr-enriched continuous oxide layer was formed at the oxidation front of the Zr-modified alloy and SUS310S after exposure to SCW conditions.

  5. Development of Ultra-high Purity (UHP) Fe-Based Alloys with High Creep and Oxidation Resistance for A-USC Technology

    Science.gov (United States)

    Hamdani, Fethi; Das, Nishith K.; Shoji, Tetsuo

    2018-03-01

    The design of ultra-high purity (UHP) Fe-based model alloys for advanced ultra-supercritical (A-USC) technology is attempted in this work. Creep testing has been performed in air at 700 °C and a stress level of 150 MPa. Analysis of the fracture surface and cross section of the crept specimen was performed. To evaluate the oxidation resistance in A-USC conditions, oxidation testing was performed in supercritical water (SCW) at 700 °C and 25 MPa. Weight gain (WG) measurements and meticulous characterization of the oxide scale were carried out. Based on thermodynamics and density functional theory calculations, some reactive elements in the Fe-Cr-Ni system were designated to promote precipitation strengthening and to improve the hydrogen-accelerated oxidation resistance. The addition of a 2 wt pct Mo into Fe-22Cr-22Ni-0.6Nb wt pct-based matrix did not significantly improve the creep resistance. The addition of 0.26 wt pct Zr coupled with cold working was effective for improving creep properties. The Mo-modified model alloy showed almost the same WG value as SUS310, while the Zr-modified alloy showed a higher WG value. Meanwhile, a Cr-enriched continuous oxide layer was formed at the oxidation front of the Zr-modified alloy and SUS310S after exposure to SCW conditions.

  6. Mechanism study of c.f.c Fe-Ni-Cr alloy corrosion in supercritical water

    International Nuclear Information System (INIS)

    Payet, M.

    2011-01-01

    Supercritical water can be use as a high pressure coolant in order to improve the thermodynamic efficiency of power plants. For nuclear concept, lifetime is an important safety parameter for materials. Thus materials selection criteria concern high temperature yield stress, creep resistance, resistance to irradiation embrittlement and also to both uniform corrosion and stress corrosion cracking.This study aims for supplying a new insight on uniform corrosion mechanism of Fe-Ni-Cr f.c.c. alloys in deaerated supercritical water at 600 C and 25 MPa. Corrosion tests were performed on 316L and 690 alloys as sample autoclaves taking into account the effect of surface finishes. Morphologies, compositions and crystallographic structure of the oxides were determined using FEG scanning electron microscopy, glow discharge spectroscopy and X-ray diffraction. If supercritical water is expected to have a gas-like behaviour in the test conditions, the results show a significant dissolution of the alloy species. Thus the corrosion in supercritical water can be considered similar to corrosion in under-critical water assuming the higher temperature and its effect on the solid state diffusion. For alloy 690, the protective oxide layer formed on polished surface consists of a chromia film topped with an iron and nickel mixed chromite or spinel. The double oxide layer formed on 316L steel seems less protective with an outer porous layer of magnetite and an inhomogeneous Cr-rich inner layer. For each alloy, the study of the inner protective scale growth mechanisms by marker or tracer experiments reveals that diffusion in the oxide scale is governed by an anionic process. However, surface finishes impact deeply the growth mechanisms. Comparisons between the results for the steel suggest that there is a competition between the oxidation of iron and chromium in supercritical water. Sufficient available chromium is required in order to form a thin oxide layer. Highly deformed or ultra fine

  7. Improvement in Microstructure Performance of the NiCrBSi Reinforced Coating on TA15 Titanium Alloy

    Science.gov (United States)

    Peng, Li

    2012-10-01

    This work is based on the dry sliding wear of NiCrBSi reinforced coating deposited on TA15 titanium alloy using the laser cladding technique, the parameters of which were such as to provide almost crack-free coatings with minimum dilution and very low porosity. SEM results indicated that a laser clad coating with metallurgical joint to the substrate was formed. Compared with TA15 substrate, an improvement of the micro-hardness and wear resistance was observed for this composite coating. Rare earth oxide Y2O3 was beneficial in producing of the amorphous phases in laser clad coating. With addition of Y2O3, more amorphous alloys were produced, which increased the micro-hardness and wear resistance of the coating.

  8. Features of Magnetorefractive Effect in a [CoFe/Cu] n Multilayer Metallic Nanostructure

    Science.gov (United States)

    Yurasov, A. N.; Telegin, A. V.; Bannikova, N. S.; Milyaev, M. A.; Sukhorukov, Yu. P.

    2018-02-01

    The features of magnetorefractive effect (MRE) in metallic multilayer film Ni48Fe12Cr40(50 Å)/[Co90Fe10(14 Å)/Cu(22 Å)]8/Cr(20 Å) nanostructures, which exhibit giant magnetoresistance at room temperature, are investigated experimentally and theoretically. We show that the MRE in these structures reaches 1.5% in an applied magnetic field of 3.5 kOe, in a broad part of the IR region, and can change sign for both transmission and reflection of light. The refraction and extinction coefficients that are calculated for the nanostructures in an external magnetic field are in good agreement with our experimental data. The deduced formulas can be applied to estimating the MRE in multilayer metallic nanostructures.

  9. Promising Cu-Ni-Cr-Si alloy for first wall ITER applications

    International Nuclear Information System (INIS)

    Ivanov, A.; Abramov, V.; Rodin, M.

    1996-01-01

    Precipitation-hardened Cu-Ni-Cr-Si alloy, a promising material for ITER applications, is considered. Available commercial products, chemical composition, physical and mechanical properties are presented. Embrittlement of Cu-Ni-Cr-Si alloy at 250-300 C is observed. Mechanical properties of Cu-Ni-Cr-Si alloy neutron irradiated to a dose of ∝0.2 dpa at 293 C are investigated. Embrittlement of Cu-Ni-Cr-Si alloy can be avoided by annealing. (orig.)

  10. Low pressure plasma spray deposition of W-Ni-Fe alloy

    International Nuclear Information System (INIS)

    Mutasim, Z.Z.; Smith, R.W.

    1991-01-01

    The production of net shape refractory metal structural preforms are increasing in importance in chemical processing, defense and aerospace applications. Conventional methods become limited for refractory metal processing due to the high melting temperatures and fabrication difficulties. Plasma spray forming, a high temperature process, has been shown to be capable of refractory metal powder consolidation in net shape products. The research reported here has evaluated this method for the deposition of heavy tungsten alloys. Plasma Melted Rapidly Solidified (PMRS) W 8%Ni-2%Fe refractory metal powders were spray formed using vacuum plasma spray (VPS) process and produced 99% dense, fine grain and homogeneous microstructures. In this paper plasma operating parameters (plasma arc gas type and flowrate plasma gun nozzle size and spray distance) were studied and their effects on deposit's density and microstructure are reported

  11. Exchange bias in antiferromagnetic coupled Fe3O4+Cr2O3 nanocomposites

    International Nuclear Information System (INIS)

    Liu, X H; Cui, W B; Lv, X K; Liu, W; Zhao, X G; Li, D; Zhang, Z D

    2008-01-01

    Exchange bias (EB) and magnetic properties of ferrimagnetic (FI) Fe 3 O 4 and antiferromagnetic (AFM) Cr 2 O 3 nanocomposites prepared by mechanical alloying have been investigated. A large EB field of 2.2 kOe at 10 K is observed in one of the nanocomposites, which may be related to the uncompensated and pinned AFM spins at the interface between FI and AFM phases of the nanocomposites. The EB field varies with the strength of cooling field and the content of the Cr 2 O 3 phase, the phenomena observed are explained in terms of interfacial exchange interaction between the two phases

  12. Microstructure and mechanical properties of Al-20Si-5Fe-2X (X = Cu, Ni, Cr) alloys produced by melt-spinning

    International Nuclear Information System (INIS)

    Rajabi, M.; Simchi, A.; Davami, P.

    2008-01-01

    Al-20Si-5Fe-2X (X = Cu, Ni and Cr) ribbons were produced by melt-spinning and consolidated by hot pressing at 400 deg. C for 60 min. The microstructure of the ribbons and the consolidated alloys was investigated using optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffractometry (XRD) method, and transmission electron microscopy (TEM). The hardness and compressive strength of the specimens at ambient and elevated temperatures were examined. The microstructure of the ribbons exhibited featureless and dendritic zones. Results of XRD and TEM showed formation of spherically shaped Si particles with an average diameter of 20 nm. Ultrafine Si (110-150 nm) and iron-containing intermetallic particles were noticed in the microstructure of the consolidated ribbons. An improved strength was achieved by alloying of Al-20Si-5Fe with Cu, Ni, and Cr. Nickel was found to be the most effective element in increasing the maximum stress, particularly at elevated temperatures

  13. Microstructure and Corrosion Behavior of Ni-Alloy/CrN Nanolayered Coatings

    Directory of Open Access Journals (Sweden)

    Hao-Hsiang Huang

    2011-01-01

    Full Text Available The Ni-alloy/CrN nanolayered coatings, Ni-Al/CrN and Ni-P/CrN, were deposited on (100 silicon wafer and AISI 420 stainless steel substrates by dual-gun sputtering technique. The influences of the layer microstructure on corrosion behavior of the nanolayered thin films were investigated. The bilayer thickness was controlled approximately 10 nm with a total coating thickness of 1m. The single-layer Ni-alloy and CrN coatings deposited at 350∘C were also evaluated for comparison. Through phase identification, phases of Ni-P and Ni-Al compounds were observed in the single Ni-alloy layers. On the other hand, the nanolayered Ni-P/CrN and Ni-Al/CrN coatings showed an amorphous/nanocrystalline microstructure. The precipitation of Ni-Al and Ni-P intermetallic compounds was suppressed by the nanolayered configuration of Ni-alloy/CrN coatings. Through Tafel analysis, the corr and corr values ranged from –0.64 to –0.33 V and 1.42×10−5 to 1.14×10−6 A/cm2, respectively, were deduced for various coating assemblies. The corrosion mechanisms and related behaviors of the coatings were compared. The coatings with a nanolayered Ni-alloy/CrN configuration exhibited a superior corrosion resistance to single-layer alloy or nitride coatings.

  14. Shape memory effect of Fe-14% Mn-6% Si-9% Cr-6% Ni alloy polycrystals

    International Nuclear Information System (INIS)

    Inagaki, Hirosuke

    1992-01-01

    Factors affecting the shape memory effect in Fe-14% Mn-6% Si-9% Cr-6% Ni alloy polycrystals were studied in detail. It was found that the shape memory effect in this alloy was most influenced by the amount of deformation. With increasing amount of deformation, the shape memory effect diminished appreciably. Although the fraction of the initial dimensional change that could be restored was about 45% in the specimen strained by 4%, only 21% of the initial dimensional change was recovered in the specimen strained by 9%. Temperatures of deformation were found to be also an important factor that affected the shape memory effect. The maximum shape memory effect was observed in the specimens strained at temperatures between the M s and M d temperatures. In this alloy, however, specimens strained at temperatures below the M s temperature indicated a relatively large shape memory effect, too. It was further found that the shape memory effect was appreciably intensified by repeated straining and annealing, especially when straining was performed at 500deg C. It was suggested that the shape memory effect in Fe base alloys was strongly influenced by the dislocation substructure present in the starting material. (orig.) [de

  15. Structural evolution of Ni-20Cr alloy during ball milling of elemental powders

    International Nuclear Information System (INIS)

    Lopez B, I.; Trapaga M, L. G.; Martinez F, E.; Zoz, H.

    2011-01-01

    The ball milling (B M) of blended Ni and Cr elemental powders was carried out in a Simoloyer performing on high-energy scale mode at maximum production to obtain a nano structured Ni-20Cr alloy. The phase transformations and structural changes occurring during mechanical alloying were investigated by X-ray diffraction (XRD) and optical microscopy (Om). A gradual solid solubility of Cr and the subsequent formation of crystalline metastable solid solutions described in terms of the Avrami-Ero fe ev kinetics model were calculated. The XRD analysis of the structure indicates that cumulative lattice strain contributes to the driving force for solid solution between Ni and Cr during B M. Microstructure evolution has shown, additionally to the lamellar length refinement commonly observed, the folding of lamellae in the final processing stage. Om observations revealed that the lamellar spacing of Ni rich zones reaches a steady value near 500 nm and almost disappears after 30 h of milling. (Author)

  16. Structural evolution of Ni-20Cr alloy during ball milling of elemental powders

    Energy Technology Data Exchange (ETDEWEB)

    Lopez B, I.; Trapaga M, L. G. [IPN, Centro de Investigacion y de Estudios Avanzados, Unidad Queretaro, Libramiento Norponiente No. 2000, Juriquilla, 76230 Queretaro (Mexico); Martinez F, E. [Centro de Investigacion e Innovacion Tecnologica, Cerrada de Cecati s/n, Col. Santa Catarina Azcapotzalco, 02250 Mexico D. F. (Mexico); Zoz, H., E-mail: israelbaez@gmail.co [Zoz GmbH, D-57482, Wenden (Germany)

    2011-07-01

    The ball milling (B M) of blended Ni and Cr elemental powders was carried out in a Simoloyer performing on high-energy scale mode at maximum production to obtain a nano structured Ni-20Cr alloy. The phase transformations and structural changes occurring during mechanical alloying were investigated by X-ray diffraction (XRD) and optical microscopy (Om). A gradual solid solubility of Cr and the subsequent formation of crystalline metastable solid solutions described in terms of the Avrami-Ero fe ev kinetics model were calculated. The XRD analysis of the structure indicates that cumulative lattice strain contributes to the driving force for solid solution between Ni and Cr during B M. Microstructure evolution has shown, additionally to the lamellar length refinement commonly observed, the folding of lamellae in the final processing stage. Om observations revealed that the lamellar spacing of Ni rich zones reaches a steady value near 500 nm and almost disappears after 30 h of milling. (Author)

  17. Effect of Fe, Ni, and Cr on the corrosion behaviour of hyper-eutectic Al-Si automotive alloy under different pH conditions

    Directory of Open Access Journals (Sweden)

    Mohammad Salim Kaiser

    2018-05-01

    Full Text Available Effect of Fe, Ni and Cr on the corrosion behaviour of hyper-eutectic Al-Si automotive alloy was studied. The test of corrosion behaviour at different environmental pH 1, 3, 5, 7, 9, 11 and 13 was performed using conventional gravimetric measurements and complemented by resistivity, optical micrograph, scanning electron microscopy (SEM and X-ray analyser (EDX investigations. The highest corrosion rate was observed at pH 13 followed by pH 1, while in the pH range of 3.0 to 11, there is a high protection of surface due to formation of stable surface oxide film. The highest corrosion rate at pH 13 is due to presence of sodium hydroxide in the solution in which the surface oxide film is soluble. At pH 1, however, high corrosion rate can be attributed to dissolution of Al due to the surface attack by aggressive chloride ions. Presence of Fe, Ni and Cr in hyper-eutectic Al-Si automotive alloy has significant effect on the corrosion rate at both environmental pH values. Resistivity of alloy surfaces initially decreases at pH 1 and pH 13 due to formation of thin films. The SEM images of corroded samples immersed in pH 1 solution clearly show pores due to uniform degradation of the alloy. In pH 13 solution, however, the corrosion layer looks more packed and impermeable.

  18. In situ XAS study of Li{sub x}Ni{sub 0.7}Fe{sub 0.15}Co{sub 0.15}O{sub 2} cathode material

    Energy Technology Data Exchange (ETDEWEB)

    Mansour, A.N. [Naval Surface Warfare Center, West Bethesda, MD (United States); Croguennec, L.; Prado, G.; Delmas, C. [Inst. de Chimie de la Matiere Condensee de Bordeaus-CNRS and Ecole Nationale Superieure de Chimie et Physique de Bordeaux, Pesssac Cedex (France)

    2001-03-01

    We have examined the oxidation states and local atomic structures of Ni, Fe, and Co in Li{sub x}Ni{sub 0.7}Fe{sub 0.15}Co{sub 0.15}O{sub 2} as a function of Li content during the first charge in a Li//Li{sub x}Ni{sub 0.7}Fe{sub 0.15}Co{sub 0.}1{sub 5O2} nonaqueous cell. We show that the composition of the material in the pristine state is more accurately described by Li{sub 0.95}Ni(II){sub 0.09}Ni(III){sub 0.66}Fe(III){sub 0.15}Co(III){sub 0.15}O{sub 2}. Half Ni(II) resides in Li-vacant sites. Both Fe and Co substitute for Ni within the NiO{sub 2} slabs with no significant amounts of Fe or Co that can be attributed to Li-vacant sites. The local structure parameters are consistent with oxidation states observed on the basis of the XANES data. The Ni {kappa}-edge energy continuously shifts to a higher energy with decrease in Li content due to oxidation of Ni( II) to Ni( III) and Ni( III) to Ni( IV). After the complete oxidation of Ni( III) to Ni( IV), the Fe KAPPA(-edge energy begins to increase with further decrease in Li content indicating the oxidation of Fe( III) to Fe( IV). The Co )KAPPA-edge energy at half-height, on the other hand, is unchanged during the whole range of Li de-intercalation indicating that no significant change in the oxidation state of Co occurs upon the complete removal of Li. (au)

  19. Internal chlorination of Ni-Cr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Berztiss, D.; Hennesen, K.; Grabke, H.J. [Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany)

    1998-12-31

    In contrast to internal oxidation, sulfidation and carburization, very little information is available regarding internal chlorination, especially diffusion of chlorine in metallic alloys. This paper describes results of experiments on Ni-Cr alloys (<10 wt% Cr) exposed in an atmosphere containing radioactive HCl. The diffusion of chlorine in the alloy can be determined by measurement of residual {beta}-activity from the sample surface. Successively thin layers (0.5-10 {mu}m) of the alloy were removed by lapping and the surface activity was measured to obtain a depth profile. Both single and polycrystalline materials were tested. Through this work it should be determined if there is in fact solubility and diffusion of chlorine in Ni-based alloys as some authors have proposed or if the ingress of chlorine is mainly a grain boundary phenomenon. (orig.)

  20. The electrochemical behaviour of various non-precious Ni and Co based alloys in artificial saliva

    Directory of Open Access Journals (Sweden)

    Mareci D.

    2005-07-01

    Full Text Available Five non-precious Ni-Co based alloys were analyzed with respect to their corrosion behaviour. The correlation between the amount of the elements Cr, Mo, V and the corrosion behaviour, expressed by the PREN (pitting resistance equivalent number index in the case of the allied steels, was extended for Ni-Cr and Co-Cr dental alloys characterization. Open circuit potential, corrosion current densities, as a measure of the corrosion rate, and main parameters of the corrosion process were evaluated from linear and cyclic polarization curves, for five Ni-Cr or Co-Cr alloys in an Afnor type artificial saliva. The maintenance times of the alloy in the corrosive medium influence the corrosion rate; the corrosion current values decrease with the maintenance time due to their passivation in solution. The microscopic analysis of the alloy surfaces shows that this passivation in solution does not modify the corrosion type. The alloys with PREN 32.9 are susceptible of localized corrosion.

  1. Bulk and surface properties of liquid Al-Cr and Cr-Ni alloys

    International Nuclear Information System (INIS)

    Novakovic, R

    2011-01-01

    The energetics of mixing and structural arrangement in liquid Al-Cr and Cr-Ni alloys has been analysed through the study of surface properties (surface tension and surface segregation), dynamic properties (chemical diffusion) and microscopic functions (concentration fluctuations in the long-wavelength limit and chemical short-range order parameter) in the framework of statistical mechanical theory in conjunction with quasi-lattice theory. The Al-Cr phase diagram exhibits the existence of different intermetallic compounds in the solid state, while that of Cr-Ni is a simple eutectic-type phase diagram at high temperatures and includes the low-temperature peritectoid reaction in the range near a CrNi 2 composition. Accordingly, the mixing behaviour in Al-Cr and Cr-Ni alloy melts was studied using the complex formation model in the weak interaction approximation and by postulating Al 8 Cr 5 and CrNi 2 chemical complexes, respectively, as energetically favoured.

  2. Bulk and surface properties of liquid Al-Cr and Cr-Ni alloys.

    Science.gov (United States)

    Novakovic, R

    2011-06-15

    The energetics of mixing and structural arrangement in liquid Al-Cr and Cr-Ni alloys has been analysed through the study of surface properties (surface tension and surface segregation), dynamic properties (chemical diffusion) and microscopic functions (concentration fluctuations in the long-wavelength limit and chemical short-range order parameter) in the framework of statistical mechanical theory in conjunction with quasi-lattice theory. The Al-Cr phase diagram exhibits the existence of different intermetallic compounds in the solid state, while that of Cr-Ni is a simple eutectic-type phase diagram at high temperatures and includes the low-temperature peritectoid reaction in the range near a CrNi(2) composition. Accordingly, the mixing behaviour in Al-Cr and Cr-Ni alloy melts was studied using the complex formation model in the weak interaction approximation and by postulating Al(8)Cr(5) and CrNi(2) chemical complexes, respectively, as energetically favoured.

  3. Laser alloyed Al-Ni-Fe coatings

    CSIR Research Space (South Africa)

    Pityana, SL

    2008-10-01

    Full Text Available The aim of this work was to produce crack-free thin surface layers consisting of binary (Al-Ni, Al-Fe) and ternary (Al-Ni-Fe) intermetallic phases by means of a high power laser beam. The laser surface alloying was carried out by melting Fe and Ni...

  4. Low Temperature Diffusion Transformations in Fe-Ni-Ti Alloys During Deformation and Irradiation

    Science.gov (United States)

    Sagaradze, Victor; Shabashov, Valery; Kataeva, Natalya; Kozlov, Kirill; Arbuzov, Vadim; Danilov, Sergey; Ustyugov, Yury

    2018-03-01

    The deformation-induced dissolution of Ni3Ti intermetallics in the matrix of austenitic alloys of Fe-36Ni-3Ti type was revealed in the course of their cascade-forming neutron irradiation and cold deformation at low temperatures via employment of Mössbauer method. The anomalous deformation-related dissolution of the intermetallics has been explained by the migration of deformation-induced interstitial atoms from the particles into a matrix in the stress field of moving dislocations. When rising the deformation temperature, this process is substituted for by the intermetallics precipitation accelerated by point defects. A calculation of diffusion processes has shown the possibility of the realization of the low-temperature diffusion of interstitial atoms in configurations of the crowdions and dumbbell pairs at 77-173 K. The existence of interstitial atoms in the Fe-36Ni alloy irradiated by electrons or deformed at 77 K was substantiated in the experiments of the electrical resistivity measurements.

  5. Magnetic properties of point defect interaction with impurity atoms in Fe-Cr alloys

    Science.gov (United States)

    Nguyen-Manh, D.; Lavrentiev, M. Yu.; Dudarev, S. L.

    2009-04-01

    An integrated ab initio and statistical Monte Carlo investigation has been recently carried out to model the thermodynamic and kinetic properties of Fe-Cr alloys. We found that the conventional Fe-Cr phase diagram is not adequate at low temperature region where the magnetic contribution to the free energy plays an important role in the prediction of an ordered Fe 15Cr phase and its negative enthalpy of formation. The origin of the anomalous thermodynamic and magnetic properties of Fe-Cr alloys can be understood using a tight-binding Stoner model combined with the charge neutrality condition. We investigate the environmental dependence of magnetic moment distributions for various self-interstitial atom dumbbells configurations using spin density maps found using density functional theory calculations. The mixed dumbbell Fe-Cr and Fe-Mn binding energies are found to be positive due to magnetic interactions. Finally, we discuss the relationship between the migration energy of vacancy in Fe-Cr alloys and magnetism at the saddle point configuration.

  6. Characterization investigations during mechanical alloying and sintering of Ni-W solid solution alloys dispersed with WC and Y2O3 particles

    International Nuclear Information System (INIS)

    Genc, Aziz; Luetfi Ovecoglu, M.

    2010-01-01

    Research highlights: → Characterization investigations on the Ni-W solid solution alloys fabricated via mechanical alloying and the evolution of the properties of the powders with increasing MA durations. → Reinforcement of the selected Ni-W powders with WC and Y 2 O 3 particles and further MA together for 12 h. → There is no reported literature on the development and characterization of Ni-W solid solution alloys matrix composites fabricated via MA. → Sintering of the developed composites and the characterization investigations of the sintered samples. → Identification of new 'pomegranate-like' structures in the bulk of the samples. - Abstract: Blended elemental Ni-30 wt.% W powders were mechanically alloyed (MA'd) for 1 h, 3 h, 6 h, 12 h, 24 h, 36 h and 48 h in a Spex mixer/mill at room temperature in order to investigate the effects of MA duration on the solubility of W in Ni and the grain size, hardness and particle size. Microstructural and phase characterizations of the MA'd powders were carried out using X-ray diffractometer (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). On the basis of achieved saturation on the solid solubility, hardness and particle size, the Ni-30 wt.% W powders MA'd for 48 h were chosen as the matrix which was reinforced with different amounts of WC and/or with 1 wt.% Y 2 O 3 particles. The reinforced powders were further MA'd for 12 h. The MA'd powders were sintered at 1300 o C for 1 h under Ar and H 2 gas flowing conditions. Microstructural characterizations of the sintered samples were conducted via XRD and SEM. Sintered densities were measured by using the Archimedes' method. Vickers microhardness tests were performed on both MA'd powders and the sintered samples. Sliding wear experiments were done in order to investigate wear behaviors of the sintered samples.

  7. Chemical diffusion of Cr, Ni and Si in welded joints. II

    International Nuclear Information System (INIS)

    Kucera, J.; Ciha, K.

    1987-01-01

    The results are given of a study in chemical diffusion in welded joints P2/A and P3/A. P2 stands for the steel (Fe-17.48 Cr-8.15 Ni-0.14 Si), P3 for (Fe-18.52 Cr-8.20 Ni-1.78 Si) and A for the Fe-Arema. Triadic sandwiche-like samples were diffusion heated at temperatures from 920 to 1170 degC. The concentration distributions N(x,t) of the given elements were measured with microprobe JXA-3A. The evaluation of the experimental data was carried out either by Grube's method, or in some cases by the spline-polynomial method. The evaluated diffusivities D-bar satisfy the Arrhenius relation and yield the standard diffusion characteristics D 0 and H. The diffusivities D-bar of Cr, Ni and Si in P1/A, in P2/A and P3/A welded joints vary with Si content in P1, P2 and P3 alloys, similar to the Cr-51 and Ni-63 self-diffusivities in Fe-18 Cr-12 Ni-X Si steels, and tend to increase with increasing Si content. The values D-bar measured in the vicinity of grain boundaries are higher than the bulk diffusion coefficients. The most rapid diffusant is Si and the slowest one Ni. Thus, the relations D-bar Si :D-bar Cr :D-bar Ni ≅ 6:3:1 (P3/A) and D-bar Si :D-bar Cr :D-bar Ni ≅ 1.7:1.4:1 (P3/A) are valid at 1050 degC. Comparing the results with those published if can be noted that the Cr-51 and Ni-63 self-diffusion in Fe-18 Cr-12 Ni-X Si steels is faster than chemical diffusion of these elements in the said steel welded joints P2/A and P3/A; X varies from 0.14 to 1.98. (author). 7 tabs., 7 figs., 20 refs

  8. Irradiation-induced precipitation and solute segregation in alloys. Fourth annual progress report, February 1, 1981-March 31, 1982

    International Nuclear Information System (INIS)

    Ardell, A.J.

    1982-04-01

    The studies of irradiation-induced solute segregation (IISS) and irradiation-induced precipitation (IIP) in Ni-Si and Pd-Fe alloys have been completed. Progress is reported for several other projects: irradiation damage in binary Pd-Cr, -Mn and -V alloys (15 at. %); IIP in Pd-Mo and Pd-W alloys; IIP in Pd-25 at. % Cr alloy; and irradiation damage effects in proton-bombarded metallic glasses (Ni-65 Zr, 40 Fe 40 Ni 14 P6B). 27 figures

  9. Influence of cold-working and subsequent heat-treatment on young's modulus and strength of Co-Ni-Cr-Mo alloy

    International Nuclear Information System (INIS)

    Otomo, Takuma; Matsumoto, Hiroaki; Chiba, Akihiko; Nomura, Naoyuki

    2009-01-01

    Changes in Young's modulus of the Co-31 mass%Ni-19 mass%Cr-10 mass%Mo alloy (Co-Ni based alloy) with cold-swaging, combined with heat-treatment at temperatures from 673 to 1323 K, was investigated to enhance the Young's modulus of Co-Ni based alloy. After cold-swaging, the Co-Ni based alloy, forming fiber deformation texture, shows the Young's modulus of 220 GPa. Furthermore, after ageing the cold-swaged alloy at temperature from 673 to 1323 K, the Young's modulus increased to 230 GPa, accompanied by a decrease in the internal fiction and an increase in the tensile strength. This suggests that the increment in Young's modulus is caused by a moving of the vacancies to the dislocation cores and a continuous locking of the dislocations along their entire length with solute atoms (trough model). By annealing at 1323 K after cold swaging, Young's modulus slightly increased to 236 GPa. On the other hand, the tensile strength decreases to almost the same value as that before cold swaging due to recrystallization. These results suggest that the Young's modulus and the strength in the present alloy are simultaneously enhanced by the continuous dislocation locking during aging as well as the formation of fiber deformation texture. (author)

  10. Abrasive wear resistance and microstructure of Ni-Cr-B-Si hardfacing alloys with additions of Al, Nb, Mo, Fe, Mn and C

    International Nuclear Information System (INIS)

    Berns, H.; Fischer, A.; Theisen, W.

    1987-01-01

    The development of new Ni-base hardfacing alloys for filler wire welding or metal spraying should result in materials with a good resistance against high temperature corrosion and abrasive wear. The first step is to design microstructures, which obtain a satisfactory abrasive wear behaviour at room temperature. Thus, different alloys are melted and scrutinized as to their microstructure and their abrasive wear resistance in laboratory. Compared to commercial Ni-base hardfacing alloys they show a higher volume fraction of coarse hard phases due to the additional, initial solidification of Nb-carbides and Cr-, and Mo-borides. Thus, the abrasive wear resistance is improved. For hard abrasive particles, such as corundum, the Ni-base alloys are more wear resistant than harder Fe-base alloys investigate earlier. This is due to the tougher Ni metal matrix that results in microcracking not to be the most significantly acting wear mechanism

  11. Determination of the Fe-Cr-Ni and Fe-Cr-Mo Phase Diagrams at Intermediate Temperatures using a Novel Dual-Anneal Diffusion-Multiple Approach

    Science.gov (United States)

    Cao, Siwei

    Phase diagrams at intermediate temperatures are critical both for alloy design and for improving the reliability of thermodynamic databases. There is a significant shortage of experimental data for phase diagrams at the intermediate temperatures which are defined as around half of the homologous melting point (in Kelvin). The goal of this study is to test a novel dual-anneal diffusion multiple (DADM) methodology for efficient determination of intermediate temperature phase diagrams using both the Fe-Cr-Ni and Fe-Cr-Mo systems as the test beds since both are very useful for steel development. Four Fe-Cr-Ni-Mo-Co diffusion multiples were made and annealed at 1200 °C for 500 hrs. One sample was used directly for evaluating the isothermal sections at 1200 ° C. The other samples (and cut slices) were used to perform a subsequent dual annealing at 900 °C (500 hrs), 800 °C (1000 hrs), 700 °C (1000 hrs), and 600 °C (4500 hrs), respectively. The second annealing induced phase precipitation from the supersaturated solid solutions that were created during the first 1200 °C annealing. Scanning electron microscopy (SEM), electron probe microanalysis (EPMA), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM) were used to identify the phases and precipitation locations in order to obtain the compositions to construct the isothermal sections of both ternary systems at four different temperatures. The major results obtained from this study are isothermal sections of the Fe-Cr-Ni and Fe-Cr-Mo systems at 1200 °C, 900 °C, 800 °C, and 700 °C. For the Fe-Cr-Ni system, the results from DADMs agree with the majority of the literature results except for results at both 800 °C and 700 °C where the solubility of Cr in the fcc phase was found to be significantly higher than what was computed from thermodynamic calculations using the TCFE5 database. Overall, it seems that the Fe-Cr-Ni thermodynamic assessment only needs slight improvement to

  12. Microstructure of aluminized coating on a Ni-Cr alloy after annealing treatment

    International Nuclear Information System (INIS)

    Huang, H.-L.; Gan Dershin

    2008-01-01

    The effects of annealing on the microstructure of first stage (high-Al activity pack) aluminized coating on Ni-15Cr alloy prepared by pack cementation method were analyzed by transmission electron microscope. The coating consists of a thin layer of γ'-Ni 3 Al, an interfacial zone of mixed β-NiAl and α-Cr, and a thick outer zone of β-NiAl (A layer) and mixed β-NiAl and α-Cr (B layer). Martensitic transformation was observed in the β-NiAl grains in the interfacial zone. Parallel crystallographic relationship was found at the γ/γ' interface in the substrate and the α/β interface in the interfacial zone. Cr 2 Al was found to precipitate in the β-NiAl and α-Cr grains in the B layer of the outer zone. The formation mechanisms of the coating layers, the precipitates, and the observed crystallographic relationships are discussed

  13. Zr - based alloys as hydride electrodes in Ni-MH batteries

    International Nuclear Information System (INIS)

    Biris, A.R.; Biris, A.S.; Misan, I.; Lupu, D.

    1999-01-01

    Hydrogen storage alloys, MH, are already used in Ni-MH alkaline batteries conquering an important share of the rechargeable nickel-cadmium battery market. This remarkable success is due not only to the replacement of the toxic material, cadmium, by metal hydrides but also to an increased specific energy, which makes them attractive for electric vehicles. Many research groups are concerned in the improvement of the hydride electrode characteristics: hydrogen storage capacity, high-rate discharge ability, increased cycle life. These properties can be modified by substitution of the base components of a given alloy. A comparison of two types of alloys suitable for MH electrodes LaNi 5 able to store 1.36 w/o hydrogen with Zr(Ti)-Ni alloys of the AB 2 Laves phase type structure showed that the latter could absorb higher amounts of hydrogen. We report part of studies on Zr-V-Cr-Ni of the 15 C type Laves phase structure using our original procedure for pasted electrodes. The substitution of Cr for V atoms in ZrV 0.5 Ni 1 . 5 did not increase the discharge capacity. However, it proved to have a remarkable effect on the discharge capacity C at low temperatures. C at - 12 deg. C as compared to 20 deg.C increases up to ∼ 65 % for Cr containing alloys. (authors)

  14. Effect of heat treatment on the microstructure of Co-Cr-W alloy fabricated by laser additive manufacturing

    Science.gov (United States)

    Ren, Bo; Chen, Changjun; Zhang, Min

    2018-04-01

    Stellite 6 cobalt-based alloy powder was used to produce Co-Cr-W alloy using laser additive manufacturing technology, and then different heat treatment strategies were carried out on the deposited sample. The characteristics of microstructure under different heat treatment conditions were investigated using scanning electron microscopy with energy dispersive spectroscopy, transmission electron microscope, and x-ray diffraction. The results show that the as-deposited sample has few cracks or pores, and the microstructure is typical dendritic structure, and lamellar eutectic carbides are rich in Cr in interdendritic. The matrix mainly consists of γ phases and a few ɛ phases. Some γ phases transform into ɛ phases after 900°C/6 h aging treatment and lamellar eutectic carbides transform into blocky carbides presenting as a network, most of the carbides are rich in Cr and a few are rich in W. When heat treated at 1200°C/1 h followed by water cooling and then treated at 900°C/6 h followed by furnace cooling, it can be found that some γ phases transform into ɛ phases. The carbides transform into elliptical M23C6 carbides that are rich in Cr with the size of 1 to 3 μm and a part of W-rich carbides.

  15. Magnetic susceptibilities of liquid Cr-Au, Mn-Au and Fe-Au alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ohno, S.; Shimakura, H. [Niigata University of Pharmacy and Applied Life Sciences, Higashijima, Akiha-ku, Niigata 956-8603 (Japan); Tahara, S. [Faculty of Science, University of the Ryukyus, Nishihara-cho, Okinawa 903-0213 (Japan); Okada, T. [Niigata College of Technology, Kamishin’eicho, Nishi-ku, Niigata 950-2076 (Japan)

    2015-08-17

    The magnetic susceptibility of liquid Cr-Au, Mn-Au, Fe-Au and Cu-Au alloys was investigated as a function of temperature and composition. Liquid Cr{sub 1-c}Au{sub c} with 0.5 ≤ c and Mn{sub 1-c}Au{sub c} with 0.3≤c obeyed the Curie-Weiss law with regard to their dependence of χ on temperature. The magnetic susceptibilities of liquid Fe-Au alloys also exhibited Curie-Weiss behavior with a reasonable value for the effective number of Bohr magneton. On the Au-rich side, the composition dependence of χ for liquid TM-Au (TM=Cr, Mn, Fe) alloys increased rapidly with increasing TM content, respectively. Additionally, the composition dependences of χ for liquid Cr-Au, Mn-Au, and Fe-Au alloys had maxima at compositions of 50 at% Cr, 70 at% Mn, and 85 at% Fe, respectively. We compared the composition dependences of χ{sub 3d} due to 3d electrons for liquid binary TM-M (M=Au, Al, Si, Sb), and investigated the relationship between χ{sub 3d} and E{sub F} in liquid binary TM-M alloys at a composition of 50 at% TM.

  16. Ostwald ripening of decomposed phases in Cu-Ni-Cr alloys

    International Nuclear Information System (INIS)

    Hernandez-Santiago, Felipe; Lopez-Hirata, Victor; Dorantes-Rosales, Hector J.; Saucedo-Munoz, Maribel L.; Gonzalez-Velazquez, Jorge L.; Paniagua-Mercado, Ana Ma.

    2008-01-01

    A study of the coarsening process of the decomposed phases was carried out in the Cu-34 wt.% Ni-4 wt.% Cr and Cu-45 wt.% Ni-10 wt.% Cr alloys using transmission electron microscopy. As aging progressed, the morphology of the coherent decomposed Ni-rich phase changed from cuboids to platelets aligned in the Cu-rich matrix directions. Prolonged aging caused the loss of coherency between the decomposed phases and the morphology of the Ni-rich phase changed to ellipsoidal. The variation of mean radius of the coherent decomposed phases with aging time followed the modified LSW theory for thermally activated growth in ternary alloy systems. The linear variation of the density number of precipitates and matrix supersaturation with aging time, also confirmed that the coarsening process followed the modified LSW theory in both alloys. The coarsening rate was faster in the symmetrical Cu-45 wt.% Ni-10 wt.% Cr alloy due to its higher volume fraction of precipitates. The activation energy for thermally activated growth was determined to be about 182 and 102 kJ mol -1 in the Cu-34 wt.% Ni-4 wt.% Cr and Cu-45 wt.% Ni-10 wt.% Cr alloys, respectively. The lower energy for the former alloy seems to be related to an increase in the atomic diffusion process as the chromium content increases. The size distributions of precipitates in the Cu-Ni-Cr alloys were broader and more symmetric than that predicted by the modified LSW theory for ternary alloys

  17. DO22-(Cu,Ni)3Sn intermetallic compound nanolayer formed in Cu/Sn-nanolayer/Ni structures

    International Nuclear Information System (INIS)

    Liu Lilin; Huang, Haiyou; Fu Ran; Liu Deming; Zhang Tongyi

    2009-01-01

    The present work conducts crystal characterization by High Resolution Transmission Electron Microscopy (HRTEM) on Cu/Sn-nanolayer/Ni sandwich structures associated with the use of Energy Dispersive X-ray (EDX) analysis. The results show that DO 22 -(Cu,Ni) 3 Sn intermetallic compound (IMC) ordered structure is formed in the sandwich structures at the as-electrodeposited state. The formed DO 22 -(Cu,Ni) 3 Sn IMC is a homogeneous layer with a thickness about 10 nm. The DO 22 -(Cu,Ni) 3 Sn IMC nanolayer is stable during annealing at 250 deg. C for 810 min. The formation and stabilization of the metastable DO 22 -(Cu,Ni) 3 Sn IMC nanolayer are attributed to the less strain energy induced by lattice mismatch between the DO 22 IMC and fcc Cu crystals in comparison with that between the equilibrium DO 3 IMC and fcc Cu crystals.

  18. Investigation into the dehydration of selenate doped Na2M(SO4)2·2H2O (M = Mn, Fe, Co and Ni): Stabilisation of the high Na content alluaudite phases Na3M1.5(SO4)3-1.5x(SeO4)1.5x (M = Mn, Co and Ni) through selenate incorporation

    Science.gov (United States)

    Driscoll, L. L.; Kendrick, E.; Knight, K. S.; Wright, A. J.; Slater, P. R.

    2018-02-01

    In this paper we report an investigation into the phases formed on dehydration of Na2M(SO4)2-x(SeO4)x·2H2O (0 ≤ x ≤ 1; M = Mn, Fe, Co and Ni). For the Fe series, all attempts to dehydrate the samples doped with selenate resulted in amorphous products, and it is suspected that a side redox reaction involving the Fe and selenate may be occurring leading to phase decomposition and hence the lack of a crystalline product on dehydration. For M = Mn, Co, Ni, the structure observed was shown to depend upon the transition metal cation and level of selenate doping. An alluaudite phase, Na3M1.5(SO4)3-1.5x(SeO4)1.5x, was observed for the selenate doped compositions, with this phase forming as a single phase for x ≥ 0.5 M = Co, and x = 1.0 M = Ni. For M = Mn, the alluaudite structure is obtained across the series, albeit with small impurities for lower selenate content samples. Although the alluaudite-type phases Na2+2y(Mn/Co)2-y(SO4)3 have recently been reported [1,2], doping with selenate appears to increase the maximum sodium content within the structure. Moreover, the selenate doped Ni based samples reported here are the first examples of a Ni sulfate/selenate containing system exhibiting the alluaudite structure.

  19. Multiscale Modeling of Grain Boundary Segregation and Embrittlement in Tungsten for Mechanistic Design of Alloys for Coal Fired Plants

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Jian; Tomar, Vikas; Zhou, Naixie; Lee, Hongsuk

    2013-06-30

    Based on a recent discovery of premelting-like grain boundary segregation in refractory metals occurring at high temperatures and/or high alloying levels, this project investigated grain boundary segregation and embrittlement in tungsten (W) based alloys. Specifically, new interfacial thermodynamic models have been developed and quantified to predict high-temperature grain boundary segregation in the W-Ni binary alloy and W-Ni-Fe, W-Ni-Ti, W-Ni-Co, W-Ni-Cr, W-Ni-Zr and W-Ni-Nb ternary alloys. The thermodynamic modeling results have been experimentally validated for selected systems. Furthermore, multiscale modeling has been conducted at continuum, atomistic and quantum-mechanical levels to link grain boundary segregation with embrittlement. In summary, this 3-year project has successfully developed a theoretical framework in combination with a multiscale modeling strategy for predicting grain boundary segregation and embrittlement in W based alloys.

  20. A first-principles study of cementite (Fe{sub 3}C) and its alloyed counterparts: Elastic constants, elastic anisotropies, and isotropic elastic moduli

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, G., E-mail: g-ghosh@northwestern.edu [Department of Materials Science and Engineering, Robert R. McCormick School of Engineering and Applied Science, Northwestern University, 2220 Campus Drive, Evanston, IL 60208-3108 (United States)

    2015-08-15

    A comprehensive computational study of elastic properties of cementite (Fe{sub 3}C) and its alloyed counterparts (M{sub 3}C (M = Al, Co, Cr, Cu, Fe, Hf, Mn, Mo, Nb, Ni, Si, Ta, Ti, V, W, Zr, Cr{sub 2}FeC and CrFe{sub 2}C) having the crystal structure of Fe{sub 3}C is carried out employing electronic density-functional theory (DFT), all-electron PAW pseudopotentials and the generalized gradient approximation for the exchange-correlation energy (GGA). Specifically, as a part of our systematic study of cohesive properties of solids and in the spirit of materials genome, following properties are calculated: (i) single-crystal elastic constants, C{sub ij}, of above M{sub 3}Cs; (ii) anisotropies of bulk, Young’s and shear moduli, and Poisson’s ratio based on calculated C{sub ij}s, demonstrating their extreme anisotropies; (iii) isotropic (polycrystalline) elastic moduli (bulk, shear, Young’s moduli and Poisson’s ratio) of M{sub 3}Cs by homogenization of calculated C{sub ij}s; and (iv) acoustic Debye temperature, θ{sub D}, of M{sub 3}Cs based on calculated C{sub ij}s. We provide a critical appraisal of available data of polycrystalline elastic properties of alloyed cementite. Calculated single crystal properties may be incorporated in anisotropic constitutive models to develop and test microstructure-processing-property-performance links in multi-phase materials where cementite is a constituent phase.

  1. Oxygen reduction reaction on a highly-alloyed Pt-Ni supported carbon electrocatalyst in acid solution

    CSIR Research Space (South Africa)

    Zheng, H

    2010-08-31

    Full Text Available Alloyed electrocatalysts such as PtNi/C[1-2], PtCo/C[3], PtCr/C[4], PtFe/C [5-6], and non-alloyed Pt-TiO2/C were reportedly investigated for methanol tolerance during Oxygen reduction reaction (ORR). The high methanol tolerance...

  2. The studies of the martensite transformations in a Ti36.5Ni48.5Hf15 alloy

    International Nuclear Information System (INIS)

    Han, S.; Jin, S.; Chinese Academy of Sciences, Beijing; Zou, W.; Zhang, Z.; Yang, D.

    1995-01-01

    In recent years, high temperature shape memory alloy (SMA) has attracted much interest by many groups of researchers. Many kinds of alloys, such as TiNiPd and NiAL alloys were reported to have shape memory effect in high temperatures. But for different kinds of reasons, these alloys were not put to practical use. TiNi alloys have been considered the best shape memory materials until now. Adding a third element whose characteristics are similar to Ti or Ni in TiNi binary alloys can produce a new style SMA, which has been done in many cases. In most circumstances, Ni was substituted and only a few investigations on the TiNi alloys was Ti replaced. But in recent years, many investigators have given more attention to this subject. In 1976, Eckelmeyer showed that Zr was one of the element that can raise the phase transformation temperatures of TiNi alloys. In 1990, Krupp obtained a patent on TiNiZr SMA with high transformation temperatures for TiNi alloys. J.H. Mulder also published his work on TiNiZr alloys in 1992. In their previous work, a new type of high temperature SMA Ti 36.5 Ni 48.5 Hf 15 alloy were investigated in more detail by DSC measurement, TEM and high-resolution observations

  3. Hot rolling effect on the characters of Zr-0.6Nb-0.5Fe-0.5Cr alloy

    International Nuclear Information System (INIS)

    Sungkono; Siti Aidah

    2015-01-01

    Characters of Zr-0.6Nb-0.5Fe-0.5Cr alloy after hot rolling have been studied. The objective of this research was to obtain of hot rolling effect on the characteristics of microstructures, hardness and phases formed in Zr-0.6Nb-0.5Fe-0.5Cr alloy. The hot rolling process of alloy carried out at temperature of 800 °C with retention time of 1.5 and 2 hours and a thickness reduction between 5 to 25 %. The results of this experiment showed that the Zr-0.6Nb-0.5Fe-0.5Cr alloy has Widmanstaetten structure with microstructure evolving into deformed columnar grains and deformed elongated grains with increasing thickness reduction. Besides, the longer the retention time at temperature of 800 °C is the larger are the grain structures and formation of α-Zr and Zr_3Fe phase. The hardness of Zr-0.6Nb-0.5Fe-0.5Cr alloy has same trends i.e the larger thickness reduction gives higher hardness. The Zr-0.6Nb-0.5Fe-0.5Cr alloy can under go hot rolling deformation at a thickness reduction of 25 % and the formation of α-Zr and Zr_3Fe can increased of hardness and strength of Zr-0.6 Nb-0.5 Fe-0.5 Cr alloy. (author)

  4. Production of Renewable Hydrogen from Glycerol Steam Reforming over Bimetallic Ni-(Cu,Co,Cr Catalysts Supported on SBA-15 Silica

    Directory of Open Access Journals (Sweden)

    Alicia Carrero

    2017-02-01

    Full Text Available Glycerol steam reforming (GSR is a promising alternative to obtain renewable hydrogen and help the economics of the biodiesel industry. Nickel-based catalysts are typically used in reforming reactions. However, the choice of the catalyst greatly influences the process, so the development of bimetallic catalysts is a research topic of relevant interest. In this work, the effect of adding Cu, Co, and Cr to the formulation of Ni/SBA-15 catalysts for hydrogen production by GSR has been studied, looking for an enhancement of its catalytic performance. Bimetallic Ni-M/SBA-15 (M: Co, Cu, Cr samples were prepared by incipient wetness co-impregnation to reach 15 wt % of Ni and 4 wt % of the second metal. Catalysts were characterized by inductively coupled plasma atomic emission spectroscopy (ICP-AES, N2-physisorption, X-ray powder diffraction (XRD, hydrogen temperature programmed reduction (H2-TPR, transmission electron microscopy (TEM, scanning electron microscopy (SEM, and thermogravimetric analyses (TGA, and tested in GSR at 600 °C and atmospheric pressure. The addition of Cu, Co, and Cr to the Ni/SBA-15 catalyst helped to form smaller crystallites of the Ni phase, this effect being more pronounced in the case of the Ni-Cr/SBA-15 sample. This catalyst also showed a reduction profile shifted towards higher temperatures, indicating stronger metal-support interaction. As a consequence, the Ni-Cr/SBA-15 catalyst exhibited the best performance in GSR in terms of glycerol conversion and hydrogen production. Additionally, Ni-Cr/SBA-15 achieved a drastic reduction in coke formation compared to the Ni/SBA-15 material.

  5. Experimental and Computational Investigation of High Entropy Alloys for Elevated-Temperature Applications

    Energy Technology Data Exchange (ETDEWEB)

    Liaw, Peter [Univ. of Tennessee, Knoxville, TN (United States); Zhang, Fan [CompuTherm LLC, Madison, WI (United States); Zhang, Chuan [CompuTherm LLC, Madison, WI (United States); Wang, Gongyao [Univ. of Tennessee, Knoxville, TN (United States); Xie, Xie [Univ. of Tennessee, Knoxville, TN (United States); Diao, Haoyan [Univ. of Tennessee, Knoxville, TN (United States); Kuo, Chih-Hsiang [Univ. of Tennessee, Knoxville, TN (United States); An, Zhinan [Univ. of Tennessee, Knoxville, TN (United States); Hemphill, Michael [Univ. of Tennessee, Knoxville, TN (United States)

    2016-07-30

    To create and design novel structural materials with enhanced creep-resistance, fundamental studies have been conducted on high-entropy alloys (HEAs), using (1) thermodynamic calculations, (2) mechanical tests, (3) neutron diffraction, (4) characterization techniques, and (5) crystal-plasticity finite-element modeling (CPFEM), to explore future candidates for next-generation power plants. All the constituent binary and ternary systems of the Al-Cr-Cu-Fe-Mn-Ni and Al-Co-Cr-Fe-Ni systems were thermodynamically modeled within the whole composition range. Comparisons between the calculated phase diagrams and literature data are in good agreement. Seven types of HEAs were fabricated from Al-Cr-Cu-Fe-Mn-Ni and Al-Co-Cr-Fe-Ni systems. The AlxCrCuFeMnNi HEAs have disordered [face-centered cubic (FCC) + body-centered cubic (BCC)] crystal structures, not FCC or BCC single structure. Excessive alloying of the Al element results in the change of both microstructural and mechanical properties in AlxCoCrFeNi HEAs. There are mainly three structural features in AlxCoCrFeNi: (1) the morphology, (2) the volume fractions of the constitute phases, and (3) existing temperatures of all six phases. After homogenization, the Al0.3CoCrFeNi material is a pure FCC solid solution. After aging at 700 °C for 500 hours, the optimal microstructure combinations, the FCC matrix, needle-like B2 phase within grains, and granular σ phase along grain boundary, is achieved for Al0.3CoCrFeNi. The cold-rolling process is utilized to reduce the grain size of Al0.1CoCrFeNi and Al0.3CoCrFeNi. The chemical elemental partitioning of FCC, BCC, B2, and σphases at different temperatures, before and after mechanical tests, in Al-Cr-Cu-Fe-Mn-Ni and Al-Co-Cr-Fe-Ni systems are quantitatively characterized by both synchrotron X-ray diffraction, neutron diffraction with levitation, scanning electron microscopy (SEM), advanced atom probe

  6. Magnetic domain structure in a metamagnetic shape memory alloy Ni45Co5Mn36.7In13.3

    International Nuclear Information System (INIS)

    Murakami, Y.; Yano, T.; Shindo, D.; Kainuma, R.; Oikawa, K.; Ishida, K.

    2006-01-01

    Correlation between the magnetism and the martensitic transformation in Ni 45 Co 5 Mn 36.7 In 13.3 has been revealed by electron holography and Lorentz microscopy. The parent phase exhibits typical closure magnetic domains due to low magnetocrystalline anisotropy. Upon cooling, the magnetic flux density of the parent phase monotonically increases, while the magnetic domain structure remains almost unchanged; in other words, the effect of premartensitic lattice modulation appears to be small in this alloy. The magnetic domains disappear immediately when the martensitic transformation occurs

  7. The influence of wall thickness on the microstructure of bronze BA1055 with the additions of Si, Cr, Mo and/or W

    Directory of Open Access Journals (Sweden)

    B.P. Pisarek

    2008-12-01

    Full Text Available Aluminium bronzes belong to the high-grade constructional materials applied on the put under strongly load pieces of machines, about good sliding, resistant properties on corrosion both in the cast state how and after the thermal processing. It moves to them Cr and Si in the aim of the improvement of their usable proprieties. Additions Mo and/or W were not applied so far in the larger concentration, these elements were introduced to the melts of the copper as the components of modifiers. It was worked out therefore the new kind of bronzes casting including these elements. Make additions to the Cu-Al-Fe-Ni bronze of Si, Cr, Mo and/or W in the rise of these properties makes possible. The investigations of the influence of the wall thickness of the cast on size of crystallites were conducted: the primary phase β and intermetallic phase κ and the width separates of the secondary phase α precipitate at phase boundary. It results from conducted investigations, that in the aluminium bronze BA1055 after simultaneous makes additions Si, Cr, Mo and in the primary phase β it undergoes considerable reducing size. The addition W reduce size of the grain phase β in the thin walls of the cast 3-6 mm, and addition Cr in the range of the thickness of the wall of the cast 3-6 mm it favors to reducing size the phase β, in walls 12-25 mm the growth causes it. The addition Mo does not influence the change of the size of the grain of the β phase significantly. The make addition singly or simultaneously of the Cr, Mo and W to the bronze CuAl10Fe5Ni5Si it influences the decrease of the quantity separates of the phase α on the interface boundary and of width it separates independently from the thickness of the wall of the cast. The simultaneous make addition of the Si, Cr, Mo and W it enlarges the surface of the phase κFe, κMo. The make addition to the bronze CuAl10Fe5Ni5Si of the Cr, Mo or W the quantity of crystallizing hard phase κ enlarges and the

  8. Oxidation performance of a Fe-13Cr alloy with additions of rare earth elements

    International Nuclear Information System (INIS)

    Martinez-Villafane, A.; Chacon-Nava, J.G.; Gaona-Tiburcio, C.; Almeraya-Calderon, F.; Dominguez-Patino, G.; Gonzalez-Rodriguez, J.G.

    2003-01-01

    The influence of rare earth elements (REE's) i.e. Neodymium (Nd) and Praseodymium (Pr) on the oxidation behavior of a Fe-13Cr alloy has been studied, and its role on the oxidation rate and oxide morphology and formation is discussed. Specimens were isothermally oxidized in oxygen at 800 deg. C for 24 h. It was found that a small addition (≤0.03 wt.%) of either Nd or Pr, reduced the oxidation rate of the Fe-13Cr base alloy. Moreover, the simultaneous addition of both elements to the alloy produced a dramatic reduction in the oxidation kinetics. Analysis by scanning electronic microscope (SEM) revealed that the morphology of oxides formed on Fe-13Cr specimens with and without REE's specimens was very different. In fact, a fine-grained oxide morphology was observed for alloys with REE's addition. For these alloys only, chromium enrichment at the metal/scale interface was observed. From transmission electronic microscope (TEM) analysis, it was found the following: at the early stages of oxide formation, after 0.25 h, Cr 2 O 3 , Fe 3 O 4 , α-Fe 2 O 3 and γ-Fe 2 O 3 were formed; at 6 h, Cr 2 O 3 , FeCr 2 O 4 and α-Fe 2 O 3 were identified and, for exposure times greater than 6 h, Cr 2 O 3 , α-Fe 2 O 3 and a spinel which was presumably transformed into a solid solution (Fe 2 O 3 ·Cr 2 O 3 ) were found

  9. Effects of Aging and W Addition on the Corrosion Resistance and Mechanical Properties of Fe-Cr-Mn-N Stainless Steels

    International Nuclear Information System (INIS)

    Jeon, Yu Taek; Joo, Uk Hyon; Park, Yong Soo; Kim, Young Sik

    2000-01-01

    The characteristics of the mechanical properties and sensitization behaviors in Fe-Cr-Mn stainless steels by W addition and aging treatment were studied. Yield strength, tensile strength, elongation and impact energy decreased, and hardness increased slightly by aging treatment. W-containing alloys showed especially a larger degree of brittle characteristics due to the hard chi(χ) phase formed from the decomposition of ferrite. Carbides precipitated in grain boundary had a bad effect on impact energy rather than on strength and hardness. Ni addition suppressed the formation of ferrite and resulted in some improvement of mechanical properties. Anodic polarization tests showed that the corrosion resistance of aged alloys decreased by the formation of carbides and secondary austenite. It was observed that W addition made no improvement of the pitting potential and passive current density of aged alloys in the HCI solution. But Ni and W decreased critical current density in the sulfuric acid and made easier formation of passive film, contributing to corrosion resistance. From the results of EPR (Electrochemical Potentiokinetic Reactivation). DOS (Degree of Sensitization) increased with aging time and carbides and ferrite were preferentially attacked. It was observed that Ni delayed the sensitization. It can be concluded from the previous results that the selective dissolution of ferrite is due to the ferrite decomposition to chi (χ) phase and secondary austenite. In the secondary austenite. Cr and W which are known to improve the corrosion resistance were depleted. Therefore, it seems that ferrite phase became sensitive to corrosion

  10. Comparative study of NiW, NiMo and MoW prepared by mechanical alloying

    International Nuclear Information System (INIS)

    Gonzalez, G.; Sagarzazu, A.; Villalba, R.; Ochoa, J.

    2007-01-01

    The present work concern the amorphisation process induced by mechanical alloying in the NiW, NiMo and MoW systems. The alloys chosen combine a group of transition elements varying from very similar atomic radius and electronic valences (MoW) to different ones (NiW and NiMo). The three systems achieved an amorphous state after 50 h of milling. The mechanism of amorphisation proposed for NiW and NiMo was the combined effect of an excess concentration of the solute atoms entering into the structure of one of the elements and a critical concentration of defects. Continuous formation of an amorphous phase at the interface of the crystalline phase was observed during the process. MoW seems to amorphize by continuous reduction of grain size down to a critical value where the amorphisation takes place

  11. Growth rate of dislocation loop in Fe-Ni-Cr alloy under Kr+ ion and electron irradiation

    International Nuclear Information System (INIS)

    Kimoto, T.; Allen, C.W.; Rehn, L.E.

    1991-10-01

    In order to examine the effect of irradiating particle species on the growth rate of radiation-induced dislocation loops, a solution-annealed Fe-25Ni-15Cr-0.02C alloy was irradiated at 723 K first by 1.5 MeV Kr + ions for 2520 sec, then by 1.5 MeV Kr + ions and 1.0 MeV electrons simultaneously for 780 sec, and finally by 1.0 MeV electrons for 780 sec with the HVEM-Tandem Facility in Argonne National Laboratory. The calculated damage rate by 1.5 MeV Kr + ions was 5.8 x 10 -4 dpa/s, and that by 1.0 MeV electrons was 1 x 10 -4 dpa/s. The growth rate of a dislocation loop located at the center of the specimen was 7 x 10 -3 nm/s for the Kr + ion irradiation, 4 x 10 -2 nm/s for the simultaneous Kr + and electron irradiation, and (2--3) x 10 -2 nm/s for the electron irradiation. This implies that the electron irradiation is about 19 times more effective in the growth of radiation-induced dislocation loops than the Kr + ion irradiation. The dislocation loop growth rate under the simultaneous Kr + and electron irradiation is higher than the sum of the growth rates under the individual Kr + and electron irradiations. 5 refs., 4 figs

  12. Effect of Ni and Cr on IGSCC growth rate of Ni-Cr-Fe alloys in PWR primary water

    International Nuclear Information System (INIS)

    Arioka, K.; Yamada, T.; Aoki, M.; Miyamoto, T.

    2015-01-01

    The purpose of this research is to examine the dependence of SCC (Stress Corrosion Crack) growth on nickel and chromium in PWR primary water; the objective is to obtain the basic knowledge to understand SCC behavior of steam generator tubing materials. The second objective is to understand whether accelerated testing at higher temperatures is appropriate for predicting SCC initiation and growth at lower temperatures. For these objectives, SCC growth was measured in PWR primary water at 290, 320, 330, 340, and 360 C. degrees under static load conditions. Tests were performed using 0.5 T compact tension type specimen using 20%CW X%Ni-16%Cr-Fe alloys in the range of nickel concentration between 16 to 60% and laboratory melted nuclear grade 20% cold worked Alloy 800 (USN N08800, CW800NG). Four important patterns were observed. First, significant effect of nickel on IGSCC resistance was observed at 340 and 360 C. degrees. The rate of IGSCC growth decreases with increasing nickel concentration in the range of nickel concentration between 10% to 25% nickel; and then, the rate of IGSCC increases with increasing nickel concentration in the range of Ni content between 50% and 76%. This trend is quite similar to the results reported by Coriou and Staehle tested in deaerated pure water at 350 C. degrees. However, no significant dependence of Ni content on IGSCC in PWR water at 320 and 290 C. degrees was observed. The change in SCC growth dependence on nickel concentration suggested that the main rate limiting processes on IGSCC growth seems to change between 320 and 340 C. degrees. Secondly, significant beneficial effects of chromium in alloys were observed at 320 C. degrees. However, no beneficial effect of chromium addition in alloys was observed at 360 C. degrees. Thirdly, peak temperatures in growth rate of IGSCC were observed in almost all test materials except for 20%CW Alloy 600. Finally, intergranular attack was observed in some alloys at lower temperature, and the

  13. Ab initio investigation of the surface properties of austenitic Fe-Ni-Cr alloys in aqueous environments

    Energy Technology Data Exchange (ETDEWEB)

    Rák, Zs., E-mail: zrak@ncsu.edu; Brenner, D.W.

    2017-04-30

    Highlights: • The trend in the surface energies of austenitic stainless steels is: (111) < (100) < (110). • On the (111) orientation Ni segregates to the surface and Cr segregates into the bulk. • The surface stability of the alloys in contact with water decrease with temperature and pH. - Abstract: The surface energetics of two austenitic stainless steel alloys (Type 304 and 316) and three Ni-based alloys (Alloy 600, 690, and 800) are investigated using theoretical methods within the density functional theory. The relative stability of the low index surfaces display the same trend for all alloys; the most closely packed orientation and the most stable is the (111), followed by the (100) and the (110) surfaces. Calculations on the (111) surfaces using various surface chemical and magnetic configurations reveal that Ni has the tendency to segregate toward the surface and Cr has the tendency to segregate toward the bulk. The magnetic frustration present on the (111) surfaces plays an important role in the observed segregation tendencies of Ni and Cr. The stability of the (111) surfaces in contact with aqueous solution are evaluated as a function of temperature, pH, and concentration of aqueous species. The results indicate that the surface stability of the alloys decrease with temperature and pH, and increase slightly with concentration. Under conditions characteristic to an operating pressurized water reactor, the Ni-based alloy series appears to be of better quality than the stainless steel series with respect to corrosion resistance and release of aqueous species when in contact with aqueous solutions.

  14. Annealing effect on redistribution of atoms in austenite of Fe-Ni-Mo and Fe-Ni-Si alloys

    International Nuclear Information System (INIS)

    Rodionov, Yu.L.; Isfandiyarov, G.G.; Zambrzhitskij, V.N.

    1980-01-01

    Using the Moessbauer spectrum method, studied has been the change in the fine atomic structure of the Fe-(28-36)%Ni austenite alloys with Mo and Si additives during annealing in the 200-800 deg C range. Also, the energy of the activation of processes, occurring at the annealing temperatures of below 500 deg C has been researched. On the basis of the obtained results a conclusion is drawn that the annealing of the investigated alloys at 300-500 deg C is conducive to the redistribution of the atoms of the alloying element and to the formation of regions with a higher content of Ni and Mo(Si) atoms

  15. Magnetic and transport properties of La0.3Ca0.7Mn0.9T0.1O3 (T = Cr, Fe, and W)

    International Nuclear Information System (INIS)

    Sudyoadsuk, T.; Suryanarayanan, R.; Winotai, P.

    2005-01-01

    We have carried out structural, magnetic and magneto transport measurements of the electron-doped manganite La 0.3 Ca 0.7 MnO 3 substituted with 10% of Cr, Fe and W on the Mn site. The substitution by Cr, Fe and W suppresses the charge order transition present at 260 K in the parent compound. All the samples show a semiconducting behavior. Whereas the parent compound does not show any magneto resistance (MR) even in a field of 14 T, a maximum MR of 6% in 5 T at 25 K is observed for the Cr substituted sample that is attributed to a spin-cluster glass like states induced by Cr. The Fe and W substituted samples showed a MR of 1.5 and 3%, respectively which may be attributed to a smaller number of FM domains/spin-clusters and to an increase in anti-ferromagnetic interaction

  16. Electrochemical investigations and characterization of a metal hydride alloy (MmNi3.6Al0.4Co0.7Mn0.3) for nickel metal hydride batteries

    International Nuclear Information System (INIS)

    Begum, S. Nathira; Muralidharan, V.S.; Basha, C. Ahmed

    2009-01-01

    The use of new hydrogen absorbing alloys as negative electrodes in rechargeable batteries has allowed the consideration of nickel/metal hydride (Ni/MH) batteries to replace the conventional nickel cadmium alkaline or lead acid batteries. In this study the performance of trisubstituted hydrogen storage alloy (MmNi 3.6 Al 0.4 Co 0.7 Mn 0.3 ) electrodes used as anodes in Ni/MH secondary batteries were evaluated. MH electrodes were prepared and the electrochemical utilization of the active material was investigated. Cyclic voltammetric technique was used to analyze the beneficial effect of the alloy by various substitutions. The electrochemical impedance spectroscopic measurements of the Ni/MH battery were made at various states of depth of discharge. The effect of temperature on specific capacity is studied and specific capacity as a function of discharge current density was also studied and the results were analyzed. The alloy metal hydride electrode was subjected to charge/discharge cycle for more than 200 cycles. The discharge capacities of the alloy remains at 250 mAh/g with a nominal fading in capacity (to the extent of ∼20 mAh/g) on prolonged cycling

  17. Study of fatigue and fracture behavior of NbCr{sub 2}-based alloys: Phase stability in Nb-Cr-Ni ternary system

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, J.H.; Liaw, P.K. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering; Liu, C.T. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

    1997-12-01

    Phase stability in a ternary Nb-Cr-Ni Laves phase system was studied in this paper. Their previous study in NbCr{sub 2}-based transition-metal Laves phases has shown that the average electron concentration factor, e/a, is the dominating factor in controlling the phase stability of NbCr{sub 2}-based Laves phases when the atomic size ratios are kept identical. Since Ni has ten out-shell electrons, the substitution of Ni for Cr in NbCr{sub 2} will increase the average electron concentration of the alloy, thus leading to the change of the crystal structures from C15 to C14. In this paper, a number of pseudo-binary Nb(Cr,Ni){sub 2} alloys were prepared, and the crystal structures of the alloys after a long heat-treatment at 1000 C as a function of the Ni content were determined by the X-ray diffraction technique. The boundaries of the C15/C14 transition were determined and compared to their previous predictions. It was found that the electron concentration and phase stability correlation is obeyed in the Nb-Cr-Ni system. However, the e/a ratio corresponding to the C15/C14 phase transition was found to move to a higher value than the predicted one. The changes in the lattice constant, Vickers hardness and fracture toughness were also determined as a function of the Ni content, which were discussed in light of the phase stability difference of the alloys.

  18. A sulfidation-resistant nickel-base alloy

    International Nuclear Information System (INIS)

    Lai, G.Y.

    1989-01-01

    For applications in mildly to moderately sulfidizing environments, stainless steels, Fe-Ni-Cr alloys (e.g., alloys 800 and 330), and more recently Fe-Ni-Cr-Co alloys (e.g., alloy 556) are frequently used for construction of process equipment. However, for many highly sulfidizing environments, few existing commercial alloys have adequate performance. Thus, a new nickel-based alloy containing 27 wt.% Co, 28 wt.% Cr, 4 wt.% Fe, 2.75 wt.% Si, 0.5 wt.% Mn and 0.05 wt.% C (Haynes alloy HR-160) was developed

  19. Optimization of Ni-Based WC/Co/Cr Composite Coatings Produced by Multilayer Laser Cladding

    Directory of Open Access Journals (Sweden)

    Andrea Angelastro

    2013-01-01

    Full Text Available As a surface coating technique, laser cladding (LC has been developed for improving wear, corrosion, and fatigue properties of mechanical components. The main advantage of this process is the capability of introducing hard particles such as SiC, TiC, and WC as reinforcements in the metallic matrix such as Ni-based alloy, Co-based alloy, and Fe-based alloy to form ceramic-metal composite coatings, which have very high hardness and good wear resistance. In this paper, Ni-based alloy (Colmonoy 227-F and Tungsten Carbides/Cobalt/Chromium (WC/Co/Cr composite coatings were fabricated by the multilayer laser cladding technique (MLC. An optimization procedure was implemented to obtain the combination of process parameters that minimizes the porosity and produces good adhesion to a stainless steel substrate. The optimization procedure was worked out with a mathematical model that was supported by an experimental analysis, which studied the shape of the clad track generated by melting coaxially fed powders with a laser. Microstructural and microhardness analysis completed the set of test performed on the coatings.

  20. Supercritical water corrosion of high Cr steels and Ni-base alloys

    International Nuclear Information System (INIS)

    Jang, Jin Sung; Han, Chang Hee; Hwang, Seong Sik

    2004-01-01

    High Cr steels (9 to 12% Cr) have been widely used for high temperature high pressure components in fossil power plants. Recently the concept of SCWR (supercritical water-cooled reactor) has aroused a keen interest as one of the next generation (Generation IV) reactors. Consequently Ni-base (or high Ni) alloys as well as high Cr steels that have already many experiences in the field are among the potential candidate alloys for the cladding or reactor internals. Tentative inlet and outlet temperatures of the anticipated SCWR are 280 and 510 .deg. C respectively. Among many candidate alloys there are austenitic stainless steels, Ni base alloys, ODS alloys as well as high Cr steels. In this study the corrosion behavior of the high Cr steels and Ni base (or high Ni) alloys in the supercritical water were investigated. The corrosion behavior of the unirradiated base metals could be used in the near future as a guideline for the out-of-pile or in-pile corrosion evaluation tests

  1. Peculiarities of phase transformation in Ni3Fe powder alloy

    International Nuclear Information System (INIS)

    Nuzhdin, A.A.

    1990-01-01

    Ordering process in sintered powder alloy Ni 3 Fe by normal and high temperatures was studied. Thermal stresses connected with porosity level of material effect on transformation peculiarities. The changes of electric conductivity, thermal expansion coefficient, bulk modulus during transformation were studied. The analysis of this changes was made

  2. Effect of сopper сoating on fibers made of aluminum alloy, titanium, and FeCrAl alloy on surface morphology and activity in CO oxidation

    Science.gov (United States)

    Lukiyanchuk, I. V.; Rudnev, V. S.; Serov, M. M.; Krit, B. L.; Lukiyanchuk, G. D.; Nedozorov, P. M.

    2018-04-01

    The catalytic activity of both copper fibers and copper-coated fibers of a diameter of 50-100 μm made of aluminum alloy, technical grade titanium, and FeCrAl alloy in CO oxidation has been estimated. Metal fibers have been fabricated by the method of pendant drop melt extraction (PDME). The fibers copper plating was carried out by chemical and electrochemical methods. The composition and structure of samples and coatings before and after catalytic tests have been characterized by the methods of scanning electron microscopy, energy-dispersive analysis, and X-ray fluorescence analysis. It has been shown that the catalytic activity of copper-coated fibers made of FeCrAl alloy in the reaction of CO oxidation is not inferior to that of copper fibers.

  3. Tensile and fracture toughness properties of the nanostructured oxide dispersion strengthened ferritic alloy 13Cr-1W-0.3Ti-0.3Y2O3

    International Nuclear Information System (INIS)

    Eiselt, Ch.Ch.; Klimenkov, M.; Lindau, R.; Moeslang, A.; Odette, G.R.; Yamamoto, T.; Gragg, D.

    2011-01-01

    The realization of fusion power as an attractive energy source requires advanced structural materials that can cope with ultra-severe thermo-mechanical loads and high neutron fluxes experienced by fusion power plant components, such as the first wall, divertor and blanket structures. Towards this end, two variants of a 13Cr-1W-0.3Ti-0.3Y 2 O 3 reduced activation ferritic (RAF-) ODS steel were produced by ball milling phase blended Fe-13Cr-1W, 0.3Y 2 0 3 and 0.3Ti powders in both argon and hydrogen atmospheres. The milled powders were consolidated by hot isostatic pressing (HIP). The as-HIPed alloys were then hot rolled into 6 mm plates. Microstructural, tensile and fracture toughness characterization of the hot rolled alloys are summarized here and compared to results previously reported for the as-HIPed condition.

  4. Synthesis, structural and magnetic characterization of soft magnetic nanocrystalline ternary FeNiCo particles

    Energy Technology Data Exchange (ETDEWEB)

    Toparli, Cigdem [Department of Metallurgical & Materials Eng., Istanbul Technical University, 34469 Istanbul (Turkey); Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf (Germany); Ebin, Burçak [Department of Metallurgical & Materials Eng., Istanbul Technical University, 34469 Istanbul (Turkey); Nuclear Chemistry and Industrial Material Recycling, Department of Chemistry and Chemical Engineering, Chalmers University of Technology, S-412 96 Gothenburg (Sweden); Gürmen, Sebahattin, E-mail: gurmen@itu.edu.tr [Department of Metallurgical & Materials Eng., Istanbul Technical University, 34469 Istanbul (Turkey)

    2017-02-01

    The present study focuses on the synthesis, microstructural and magnetic properties of ternary FeNiCo nanoparticles. Nanocrystalline ternary FeNiCo particles were synthesized via hydrogen reduction assisted ultrasonic spray pyrolysis method in single step. The effect of precursor concentration on the morphology and the size of particles was investigated. The syntheses were performed at 800 °C. Structure, morphology and magnetic properties of the as-prepared products were characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM) studies. Scherer calculation revealed that crystallite size of the ternary particles ranged between 36 and 60 nm. SEM and TEM investigations showed that the particle size was strongly influenced by the precursor concentration and Fe, Ni, Co elemental composition of individual particles was homogeneous. Finally, the soft magnetic properties of the particles were observed to be a function of their size. - Highlights: • Ternary FeNiCo alloy nanocrystalline particles were synthesized in a single step. • Cubic crystalline structure and spherical morphology was observed by XRD, SEM and TEM investigations. • The analysis of magnetic properties indicates the soft magnetic features of particles.

  5. Swelling of Fe-Mn and Fe-Cr-Mn alloys at high neutron fluence

    International Nuclear Information System (INIS)

    Garner, F.A.; Brager, H.R.

    1986-06-01

    Swelling data on neutron-irradiated simple Fe-Cr-Mn and Fe-Mn alloys, as well as commercial Fe-Cr-Mn base alloys are now becoming available at exposure levels approaching 50 dpa. The swelling rate decreases from the ∼1%/dpa found at lower exposures, probably due to the extensive formation of ferritic phases. As expected, commercial alloys swell less than the simple alloys

  6. Evaluation of austenitic stainless steels for transpassive corrosion by metal purification technology. Synergistic effect of Si and P on intergranular corrosion of Fe-18Cr-14Ni alloys

    International Nuclear Information System (INIS)

    Mayuzumi, Masami; Ohta, Joji; Kako, Kenji; Kawakami, Eishi

    2001-01-01

    The synergistic effect of Si, Mn, C, P, and S on the transpassive corrosion of HP18Cr-14Ni alloys was studied in 13N nitric acid. The specimens were fabricated using a cold crucible method in a high-vacuum chamber to reduce contamination. The additions of Si<1% and Mn<2% had no effect on the corrosion behavior of HP18Cr-14Ni alloys, and the addition of Si<1% also had no effect on the corrosion behavior of HP18Cr-14Ni-1Mn alloys, although 1% Si induced intergranular corrosion in both the alloys. Thus, HP18Cr-14Ni-1Mn-0.5Si alloys were selected to evaluate the effects of C, P and S (100 ppm each). The addition of P, and the co-addition of C, P, and S to HP18Cr-14Ni-1Mn-0.5Si induced intergranular corrosion of the same degree in the solution annealed condition. This result suggests the synergistic effect of Si and P to induce intergranular corrosion, since the single addition of Si or P to this level did not lead to intergranular corrosion of HP18Cr-14Ni alloys. HP18Cr-14Ni-1Mn-0.5Si alloys containing C, P, and S at the 100 ppm level each showed superior corrosion resistance compared to a commercial Type 304L in 13N nitric acid. (author)

  7. Syngas Production from Catalytic CO2 Reforming of CH4 over CaFe2O4 Supported Ni and Co Catalysts: Full Factorial Design Screening

    Directory of Open Access Journals (Sweden)

    M. Anwar Hossain

    2018-01-01

    Full Text Available In this study, the potential of dry reforming reaction over CaFe2O4 supported Ni and Co catalysts were investigated. The Co/CaFe2O4 and Ni/CaFe2O4 catalysts were synthesized using wet impregnation method by varying the metal loading from 5-15 %. The synthesized catalysts were tested in methane dry reforming reaction at atmospheric pressure and reaction temperature ranged 700-800 oC. The catalytic performance of the catalysts based on the initial screening is ranked as 5%Co/CaFe2O4 < 10%Co/CaFe2O4 < 5%Ni/CaFe2O4 < 10%Ni/CaFe2O4 according to their performance. The Ni/CaFe2O4 catalyst was selected for further investigation using full factorial design of experiment. The interaction effects of three factors namely metal loading (5-15 %, feed ratio (0.4-1.0, and reaction temperature (700-800 oC were evaluated on the catalytic activity in terms of CH4 and CO2 conversion as well as H2 and CO yield. The interaction between the factors showed significant effects on the catalyst performance at metal loading, feed ratio and reaction temperature of 15 %, 1.0, and 800 oC. respectively. The 15 wt% Ni/CaFe2O4 was subsequently characterized by Thermogravimetric (TGA, X-ray Diffraction (XRD, Field Emission Scanning Electron Microscopy (FESEM, Energy Dispersive X-ray Spectroscopy (EDX, X-ray Photoelectron Spectroscopy (XPS, N2-physisorption, Temperature Programmed Desorption (TPD-NH3, TPD-CO2, and Fourier Transform Infra Red (FTIR to ascertain its physiochemical properties.  This study demonstrated that the CaFe2O4 supported Ni catalyst has a good potential to be used for syngas production via methane dry reforming. Copyright © 2018 BCREC Group. All rights reserved Received: 5th May 2017; Revised: 8th August 2017; Accepted: 9th August 2017; Available online: 22nd January 2018; Published regularly: 2nd April 2018 How to Cite: Hossain, M.A., Ayodele, B.V., Cheng, C.K., Khan, M.R. (2018. Syngas Production from Catalytic CO2 Reforming of CH4 over CaFe2O4 Supported

  8. Resistencia a la corrosión a alta temperatura de recubrimientos NiCrAlY y NiCrFeNbMoTiAl depositados por APS

    Directory of Open Access Journals (Sweden)

    José Luis Tristancho-Reyes

    2014-12-01

    Full Text Available La corrosión a alta temperatura de las tuberías utilizadas en equipos generadores de vapor (calderas ha sido reconocida como un grave problema que trae consigo el adelgazamiento de éstas y, por consiguiente, la falla de los equipos. En la última década se han incrementado las investigaciones que involucran recubrimientos protectores que ayudan de alguna manera a prolongar la vida útil de estos equipos. Esta investigación determinó el comportamiento de los recubrimientos NiCrAlY y NiCrFeNbMoTiAl depositados por proyección térmica asistida por plasma (APS sobre la aleación SA213 – T22 (2¼Cr – 1Mo, en un ambiente corrosivo de 80%V2O5–20%K2SO4 a 800°C. Los valores de la cinética de corrosión fueron determinados mediante resistencia a la polarización lineal (RPL y espectroscopia de impedancia electroquímica (EIE. Los resultados obtenidos muestran una menor cinética de corrosión en el recubrimiento NiCrFeNbMoTiAl que la presentada por el recubrimiento NiCrAlY, corroborado por Microscopia Electrónica de Barrido (MEB.

  9. Amorphization of C-implanted Fe(Cr) alloys

    International Nuclear Information System (INIS)

    Knapp, J.A.; Follstaedt, D.M.; Sorensen, N.R.; Pope, L.E.

    1991-01-01

    The amorphous phase formed by implanting C into Fe alloyed with Cr, which is a prototype for the amorphous phase formed by implanting C into stainless steels, is compared to that formed by implanting C and Ti into Fe and steels. The composition range of the phase has been examined; higher Cr and C concentrations are required than needed with Ti and C. The friction and wear benefits obtained by implanting stainless steels with C only do not persist for the long durations and high wear loads found with Ti and C. However, the amorphous Fe-Cr-C alloys exhibit good aqueous corrosion resistance. (orig.)

  10. Characterization of dissimilar welding: carbon steel E309L-E308L-ERNiCr3-ENiCrFe3 alloy 600; Caracterizacion de la soldadura disimilar: acero al carbono E309L-E308L-ERNiCr3-ENiCrFe3 aleacion 600

    Energy Technology Data Exchange (ETDEWEB)

    Mucino G, O.

    2015-07-01

    Most BWR type reactors have internal support components, which need to be attached to the inner surface by welding. Specifically, in these joints two materials interact, such as stainless steel and nickel base alloys. Nickel base alloys such as alloy 82 (ERNiCr3) and alloy 182 (ENiCrFe-3) are used for the joining of both dissimilar materials. For joints made with both nickel base alloys, the alloy 182 is prone to stress corrosion cracking (SCC); so it is essential to carry out studies related to this contribution material. In the nuclear industry any study related to this alloy is of importance because experience is gained in its behavior when is part of a system of an operation reactor. This work presents the characterization of the weld deposit of a stainless steel coating (with electrodes E309L and E308L) on a carbon steel plate type A36 and the joining with an Inconel 600 plate, simulating the joining of the internal coating of vessel and the heel of the support leg of the envelope of a BWR reactor. In this work, the mechanical and micro-structural characterization of the alloy deposit 182 was performed. (Author)

  11. Hydrogen absorption/desorption properties in the TiCrV based alloys

    Directory of Open Access Journals (Sweden)

    A. Martínez

    2012-10-01

    Full Text Available Three different Ti-based alloys with bcc structure and Laves phase were studied. The TiCr1.1V0.9, TiCr1.1V0.45Nb0.45 and TiCr1.1V0.9 + 4%Zr7Ni10 alloys were melted in arc furnace under argon atmosphere. The hydrogen absorption capacity was measured by using aparatus type Sievert's. Crystal structures, and the lattice parameters were determined by using X-ray diffraction, XRD. Microestructural analysis was performed by scanning electron microscope, SEM and electron dispersive X-ray, EDS. The hydrogen storage capacity attained a value of 3.6 wt. (% for TiCr1.1V0.9 alloy in a time of 9 minutes, 3.3 wt. (% for TiCr1.1V0.45Nb0.45 alloy in a time of 7 minutes and 3.6 wt. (% TiCr1.1V0.9 + 4%Zr7Ni10 with an increase of the hydrogen absorption kinetics attained in 2 minutes. This indicates that the addition of Nb and 4%Zr7Ni10 to the TiCrV alloy acts as catalysts to accelerate the hydrogen absorption kinetics.

  12. Neutron activation of 21 elements by means of the Mg+d reaction (Esub(d) 22 Mev)

    International Nuclear Information System (INIS)

    Zatolokin, B.V.; Krasnov, N.N.; Konstantinov, I.O.; Bolotskikh, V.I.

    1981-01-01

    For the first time the activation of 21 elements (Mn, Al, Ti, V, Cr, Mg, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ag, Cd, Sn, Sb, Ta, W and Pb) by neutrons produced as a result of magnesium target irradiation by deuterons at 22 MeV energy is investigated. The reduced exposure dose rates of point samples of 1 g mass at 1 cm distance from a source are presented. The data on variation in time of exposure dose rates of 1 g mass samples irradiated during 100 hours are indicated. In the framework of a two-group approximation the neutron spectrum is estimated by the results of measurement of two threshold detector activity. It is shown that for the first hours after irradiation Mn, Mg, Al, W, Cu and Ta have the highest exposure dose rates, Cr, Pb, Cd and Sn - the lowest. In four days after irradiation Sb, Ta, Co, Ag and Ti have the highest dose rates, Pb, Fe, Cu and Cr - the lowest. The data obtained can be used in constructing separate accelerator units and in fast neutron activation analysis [ru

  13. Investigation of decomposition of solid solution of Ni-Cr-Fe 77/16/7 over-saturated in carbon during tempering at various temperatures

    International Nuclear Information System (INIS)

    Duffaut, Francois

    1966-01-01

    In its first part, this research thesis reports the investigation of the structure of the tempered Ni-Cr-Fe 77/16/7 alloy by using optical and electronic microscopy. The second part addresses the relationship between the structural status of the alloy and its electrochemical behaviour. The third part reports the investigation of the Portevin - Le Chatelier phenomenon in relationship with the decomposition of the solid solution. A last part addresses the investigation of a possible microstructure ordering of the Ni-Cr-Fe 77/16/7 alloy

  14. Corrosion aspects of Ni-Cr-Fe based and Ni-Cu based steam generator tube materials

    International Nuclear Information System (INIS)

    Dutta, R.S.

    2009-01-01

    This paper reviews corrosion related issues of Ni-Cr-Fe based (in a general sense) and Ni-Cu based steam generator tube materials for nuclear power plants those have been dealt with for last more than four decades along with some updated information on corrosion research. The materials include austenitic stainless steels (SSs), Alloy 600, Monel 400, Alloy 800 and Alloy 690. Compatibility related issues of these alloys are briefly discussed along with the alloy chemistry and microstructure. For austenitic SSs, stress corrosion cracking (SCC) behaviour in high temperature aqueous environments is discussed. For Alloy 600, intergranular cracking in high temperature water including hydrogen-induced intergranular cracking is highlighted along with the interactions of material in various environments. In case of Monel 400, intergranular corrosion and pitting corrosion at ambient temperature and SCC behaviour at elevated temperature are briefly described. For Alloy 800, the discussion covers SCC behaviour, surface characterization and microstructural aspects of pitting, whereas hydrogen-related issues are also highlighted for Alloy 690.

  15. Microstructural characterization of Y{sub 2}O{sub 3} ODS-Fe-Cr model alloys

    Energy Technology Data Exchange (ETDEWEB)

    Castro, V. de [Department of Materials, University of Oxford, Oxford OX1 3PH (United Kingdom)], E-mail: vanessa.decastro@materials.ox.ac.uk; Leguey, T.; Munoz, A.; Monge, M.A.; Pareja, R. [Departamento de Fisica, Universidad Carlos III de Madrid, 28911 Leganes (Spain); Marquis, E.A.; Lozano-Perez, S.; Jenkins, M.L. [Department of Materials, University of Oxford, Oxford OX1 3PH (United Kingdom)

    2009-04-30

    Two Fe-12 wt% Cr alloys, one containing 0.4 wt% Y{sub 2}O{sub 3} and the other Y{sub 2}O{sub 3}-free, have been produced by mechanical alloying followed by hot isostatic pressing. These oxide dispersion strengthened and reference alloys were characterized both in the as-HIPed state and after tempering by transmission electron microscopy and atom-probe tomography. The as-HIPed alloys exhibited the characteristic microstructure of lath martensite and contained a high density of dislocations. Small voids with sizes <10 nm were also observed. Both alloys also contained M{sub 3}C and M{sub 23}C{sub 6} carbides (M = Cr, Fe) probably as a result of C ingress during milling. After tempering at 1023 K for 4 h the microstructures had partially recovered. In the recovered regions, martensite laths were replaced by equiaxed grains in which M{sub 23}C{sub 6} carbides decorated the grain boundaries. In the ODS alloy nanoparticles containing Y were commonly observed within grains, although they were also present at grain boundaries and adjacent to large carbides.

  16. Hydroponic phytoremediation of Cd, Cr, Ni, As, and Fe: can Helianthus annuus hyperaccumulate multiple heavy metals?

    Science.gov (United States)

    January, Mary C; Cutright, Teresa J; Van Keulen, Harry; Wei, Robert

    2008-01-01

    Sundance sunflowers were subjected to contaminated solutions containing 3, 4, or 5 heavy metals, with and without EDTA. The sunflowers exhibited a metal uptake preference of Cd=Cr>Ni, Cr>Cd>Ni>As and Fe>As>Cd>Ni>Cr without EDTA and Cr>Cd>Ni, Fe>As>Cd>Cr>Ni with EDTA. As uptake was not affected by other metals, but it decreased Cd and Ni concentration in the stems. The presence of Fe improved the translocation of the other metals regardless of whether EDTA was present. In general, EDTA served as a hindrance to metal uptake. For the experiment with all five heavy metals, EDTA decreased Cd in the roots and stems from 2.11 to 1.36 and from 2.83 to 2.3 2mg g(-1) biomass, respectively. For the same conditions, Ni in the stems decreased from 1.98 to 0.94 mg g(-1) total metal uptake decreased from 14.95 mg to 13.89 mg, and total biomass decreased from 2.38 g to 1.99 g. These results showed an overall negative effect in addition of EDTA. However it is unknown whether the negative effect was due to toxicity posed by EDTA or the breaking of phytochelatin-metal bonds. The most important finding was the ability of Sundance sunflowers to achieve hyperaccumulator status for both As and Cd under all conditions studied. Ni hyperaccumulator status was only achieved in the presence of three metals without EDTA.

  17. Formation and crystallization kinetics of Nd-Fe-B-based bulk amorphous alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Qiong; Ge, Hongliang; Zhang, Pengyue; Li, Dongyun; Wang, Zisheng [China Jiliang University, Magnetism Key Laboratory of Zhejiang Province, Hangzhou (China)

    2014-06-15

    In order to improve the glass-forming ability (GFA) of Nd-Fe-B ternary alloys to obtain fully amorphous bulk Nd-Fe-B-based alloy, the effects of Mo and Y doping on GFA of the alloys were investigated. It was found that the substitution of Mo for Fe and Y for Nd enhanced the GFA of the Nd-Y-Fe-Mo-B alloys. It was also revealed that the GFA of the samples was optimized by 4 at.% Mo doping and increased with theYcontent. The fully amorphous structures were all formed in the Nd{sub 6-x}Y{sub x}Fe{sub 68}Mo{sub 4}B{sub 22} (x =1-5) alloy rods with 1.5 mm-diameter. After subsequent crystallization, the devitrified Nd{sub 3}Y{sub 3}Fe{sub 68}Mo{sub 4}B{sub 22} alloy rod exhibited a uniform distribution of grains with a coercivity of 364.1 kA/m. The crystallization behavior of Nd{sub 3}Y{sub 3}Fe{sub 68}Mo{sub 4}B{sub 22} BMG was investigated in isothermal situation. The Avrami exponent n determined by JAM plot is lower than 2.5, implying that the crystallization is mainly governed by a growth of particles with decreasing nucleation rate. (orig.)

  18. Effect of alloying element on mechanical and oxidation properties of Ni-Cr-Mo-Co alloys at 950 °C

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong-Jin, E-mail: djink@kaeri.re.kr; Jung, Su Jin; Mun, Byung Hak; Kim, Sung Woo; Lim, Yun Soo; Kim, Woo Gon; Hwang, Seong Sik; Kim, Hong Pyo

    2016-12-01

    Graphical abstract: Mo rich carbide was developed leading to significant increase of elongation to rupture and creep rupture time of Ni-Cr-Co-Mo alloy at 950 °C. Al addition improved corrosion resistance caused by enhancement of oxide/matrix interface stability. Abstract: The very-high-temperature reactor (VHTR) is a promising Generation-IV reactor design given its clear advantage regarding the production of massive amounts of hydrogen and in generating highly efficient electricity despite the fact that a material challenge remains at a high temperature of around 950 °C, where hydrogen production is possible under high pressure. In particular, among the many components composing a VHTR, the temperature of the intermediate heat exchanger (IHX) is expected to be the highest, with a coolant environment of up to 950 °C. Therefore, this work focuses on the mechanical and oxidation properties at 950 °C as a function of the alloying elements of Cr, Co, Mo, Al, and Ti constituting nickel-based alloys fabricated in a laboratory. The tensile, creep, and oxidation properties of the alloying elements were analyzed with SEM, TEM-EDS, and by assessing the weight change.

  19. Laser cladding Ni-base composite coating on titanium alloy with pre-placed B4C+NiCoCrAlY

    International Nuclear Information System (INIS)

    Qingwu Meng; Lin Geng; Zhenzhu Zheng

    2005-01-01

    Using a CO 2 laser, a process of cladding Ni-base composite coating on Ti6Al4V with pre-placed B 4 C and NiCoCrAlY was studied. A good metallurgical bonding coating without cracks and pores was obtained in reasonable ratio of components and low energy laser process. Morphology and microstructure of the coating were analyzed with OM, XRD, SEM and EDS. It is certain that there was a reaction between B 4 C and Ti during in-situ producing TiB 2 and TiC. The Ni-base composite coating is strengthened with TiB 2 and TiC reinforcement phases. Vickers hardness tester measured that the average microhardness of the coating is HV1200 and it is 3.5 times of the Ti6Al4V substrate. The high hard coating containing several reinforcement phases greatly enhances wear resistance of titanium alloy. (orig.)

  20. Postirradiation deformation behavior in ferritic Fe-Cr alloys

    International Nuclear Information System (INIS)

    Hamilton, M.L.; Gelles, D.S.; Gardner, P.L.

    1992-06-01

    It has been demonstrated that fast-neutron irradiation produces significant hardening in simple Fe-(3-18)Cr binary alloys irradiated to about 35 dpa in the temperature range 365 to 420 degrees C, whereas irradiation at 574 degrees C produces hardening only for 15% or more chromium. The irradiation-induced changes in tensile properties are discussed in terms of changes in the power law work-hardening exponent. The work-hardening exponent of the lower chromium alloys decreased significantly after low-temperature irradiation (≤ 420 degrees C) but increased after irradiation at 574 degrees C. The higher chromium alloys failed either in cleavage or in a mixed ductile/brittle fashion. Deformation microstructures are presented to support the tensile behavior

  1. Pressure-induced positive electrical resistivity coefficient in Ni-Nb-Zr-H glassy alloy

    Science.gov (United States)

    Fukuhara, M.; Gangli, C.; Matsubayashi, K.; Uwatoko, Y.

    2012-06-01

    Measurements under hydrostatic pressure of the electrical resistivity of (Ni0.36Nb0.24Zr0.40)100-xHx (x = 9.8, 11.5, and 14) glassy alloys have been made in the range of 0-8 GPa and 0.5-300 K. The resistivity of the (Ni0.36Nb0.24Zr0.40)86H14 alloy changed its sign from negative to positive under application of 2-8 GPa in the temperature range of 300-22 K, coming from electron-phonon interaction in the cluster structure under pressure, accompanied by deformation of the clusters. In temperature region below 22 K, the resistivity showed negative thermal coefficient resistance by Debye-Waller factor contribution, and superconductivity was observed at 1.5 K.

  2. Heterobimetallic [NiFe] Complexes Containing Mixed CO/CN- Ligands: Analogs of the Active Site of the [NiFe] Hydrogenases.

    Science.gov (United States)

    Perotto, Carlo U; Sodipo, Charlene L; Jones, Graham J; Tidey, Jeremiah P; Blake, Alexander J; Lewis, William; Davies, E Stephen; McMaster, Jonathan; Schröder, Martin

    2018-03-05

    The development of synthetic analogs of the active sites of [NiFe] hydrogenases remains challenging, and, in spite of the number of complexes featuring a [NiFe] center, those featuring CO and CN - ligands at the Fe center are under-represented. We report herein the synthesis of three bimetallic [NiFe] complexes [Ni( N 2 S 2 )Fe(CO) 2 (CN) 2 ], [Ni( S 4 )Fe(CO) 2 (CN) 2 ], and [Ni( N 2 S 3 )Fe(CO) 2 (CN) 2 ] that each contain a Ni center that bridges through two thiolato S donors to a {Fe(CO) 2 (CN) 2 } unit. X-ray crystallographic studies on [Ni( N 2 S 3 )Fe(CO) 2 (CN) 2 ], supported by DFT calculations, are consistent with a solid-state structure containing distinct molecules in the singlet ( S = 0) and triplet ( S = 1) states. Each cluster exhibits irreversible reduction processes between -1.45 and -1.67 V vs Fc + /Fc and [Ni( N 2 S 3 )Fe(CO) 2 (CN) 2 ] possesses a reversible oxidation process at 0.17 V vs Fc + /Fc. Spectroelectrochemical infrared (IR) and electron paramagnetic resonance (EPR) studies, supported by density functional theory (DFT) calculations, are consistent with a Ni III Fe II formulation for [Ni( N 2 S 3 )Fe(CO) 2 (CN) 2 ] + . The singly occupied molecular orbital (SOMO) in [Ni( N 2 S 3 )Fe(CO) 2 (CN) 2 ] + is based on Ni 3d z 2 and 3p S with the S contributions deriving principally from the apical S-donor. The nature of the SOMO corresponds to that proposed for the Ni-C state of the [NiFe] hydrogenases for which a Ni III Fe II formulation has also been proposed. A comparison of the experimental structures, and the electrochemical and spectroscopic properties of [Ni( N 2 S 3 )Fe(CO) 2 (CN) 2 ] and its [Ni( N 2 S 3 )] precursor, together with calculations on the oxidized [Ni( N 2 S 3 )Fe(CO) 2 (CN) 2 ] + and [Ni( N 2 S 3 )] + forms suggests that the binding of the {Fe(CO)(CN) 2 } unit to the {Ni(CysS) 4 } center at the active site of the [NiFe] hydrogenases suppresses thiolate-based oxidative chemistry involving the bridging thiolate S donors

  3. Characterization investigations during mechanical alloying and sintering of Ni-W solid solution alloys dispersed with WC and Y{sub 2}O{sub 3} particles

    Energy Technology Data Exchange (ETDEWEB)

    Genc, Aziz, E-mail: agenc@itu.edu.t [Particulate Materials Laboratories, Department of Metallurgical and Materials Engineering, Istanbul Technical University, Maslak, 34469 Istanbul (Turkey); Luetfi Ovecoglu, M. [Particulate Materials Laboratories, Department of Metallurgical and Materials Engineering, Istanbul Technical University, Maslak, 34469 Istanbul (Turkey)

    2010-10-15

    Research highlights: {yields} Characterization investigations on the Ni-W solid solution alloys fabricated via mechanical alloying and the evolution of the properties of the powders with increasing MA durations. {yields} Reinforcement of the selected Ni-W powders with WC and Y{sub 2}O{sub 3} particles and further MA together for 12 h. {yields} There is no reported literature on the development and characterization of Ni-W solid solution alloys matrix composites fabricated via MA. {yields} Sintering of the developed composites and the characterization investigations of the sintered samples. {yields} Identification of new 'pomegranate-like' structures in the bulk of the samples. - Abstract: Blended elemental Ni-30 wt.% W powders were mechanically alloyed (MA'd) for 1 h, 3 h, 6 h, 12 h, 24 h, 36 h and 48 h in a Spex mixer/mill at room temperature in order to investigate the effects of MA duration on the solubility of W in Ni and the grain size, hardness and particle size. Microstructural and phase characterizations of the MA'd powders were carried out using X-ray diffractometer (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). On the basis of achieved saturation on the solid solubility, hardness and particle size, the Ni-30 wt.% W powders MA'd for 48 h were chosen as the matrix which was reinforced with different amounts of WC and/or with 1 wt.% Y{sub 2}O{sub 3} particles. The reinforced powders were further MA'd for 12 h. The MA'd powders were sintered at 1300 {sup o}C for 1 h under Ar and H{sub 2} gas flowing conditions. Microstructural characterizations of the sintered samples were conducted via XRD and SEM. Sintered densities were measured by using the Archimedes' method. Vickers microhardness tests were performed on both MA'd powders and the sintered samples. Sliding wear experiments were done in order to investigate wear behaviors of the sintered samples.

  4. Influence of intermetallic Fe and Co on crystal structure disorder and magnetic property of Ni50Mn32Al18 Heusler alloy

    International Nuclear Information System (INIS)

    Notonegoro, H. A.; Kurniawan, B.; Manaf, A.; Setiawan, J.; Nanto, D.

    2016-01-01

    This works reports a study on structure and magnetic properties influenced by both Fe and Co on Ni 50 Mn 32 Al 18 Heusler alloy as a candidate of magnetocaloric effect (MCE) materials. The Ni-Fe-Mn-Co-Al sample was prepared by arc melting furnace (AMF) in high purity argon atmosphere. X-ray diffraction investigation and magnetic hysteresis were conducted to characterize the synthesized sample. X-ray diffraction using Cu-Kα pattern shows that both Fe and Co introduce a tungsten type disorder of Ni 50 Mn 32 Al 18 Heusler alloy which partially replace the site position of Ni and Mn respectively. However, in this tungsten type disorder, it is difficult to distinguish the exact position of each constituent atom. Therefore, we believe it may allow any exchange interaction of each electron possessed the atom. Interestingly, it produced a significant increase in the value of the hysteresis magnetic saturation. (paper)

  5. Artificial Neural Network-Based Three-dimensional Continuous Response Relationship Construction of 3Cr20Ni10W2 Heat-Resisting Alloy and Its Application in Finite Element Simulation

    Science.gov (United States)

    Li, Le; Wang, Li-yong

    2018-04-01

    The application of accurate constitutive relationship in finite element simulation would significantly contribute to accurate simulation results, which plays a critical role in process design and optimization. In this investigation, the true stress-strain data of 3Cr20Ni10W2 heat-resisting alloy were obtained from a series of isothermal compression tests conducted in a wide temperature range of 1203-1403 K and strain rate range of 0.01-10 s-1 on a Gleeble 1500 testing machine. Then the constitutive relationship was modeled by an optimally constructed and well-trained back-propagation artificial neural network (BP-ANN). The evaluation of the BP-ANN model revealed that it has admirable performance in characterizing and predicting the flow behaviors of 3Cr20Ni10W2 heat-resisting alloy. Meanwhile, a comparison between improved Arrhenius-type constitutive equation and BP-ANN model shows that the latter has higher accuracy. Consequently, the developed BP-ANN model was used to predict abundant stress-strain data beyond the limited experimental conditions and construct the three-dimensional continuous response relationship for temperature, strain rate, strain, and stress. Finally, the three-dimensional continuous response relationship was applied to the numerical simulation of isothermal compression tests. The results show that such constitutive relationship can significantly promote the accuracy improvement of numerical simulation for hot forming processes.

  6. Study the microstructure of three and four component phases in Al-Ni-Fe-La alloys

    KAUST Repository

    Kolobylina, Natalia

    2016-12-21

    Aluminium alloys play a key role in modern engineering since they are the most used non-ferrous material. They have been widely used in automotive, aerospace, and construction engineering due to their good corrosion resistance, superior mechanical properties along with good machinability, weldability, and relatively low cost. The progress in practical application has been determined by intensive research and development works on the Al alloys. A new class of Al–REM–TM aluminum alloys (REM indicates rare earth metal and TM is transition metal) was revealed in the end of the last century. These alloys differ from conventional ones by their extraordinary ability to form metal glasses and nanoscale composites in a wide range of compositions. Having low density, these alloys possess unique mechanical characteristics and corrosion resistance. Two as received alloys, namely Al85Ni9Fe2La4 and Al85Ni7Fe4La4 were obtained in the form of ingots from melts of corresponding compositions upon cooling in air were studied by scanning/transmission electron microscopy (STEM), energy dispersive X-ray (EDX) microanalysis and X-ray diffraction (XRD). The microstructural analyses were performed in a aberration corrected TITAN 80-300 TEM/STEM (FEI, USA) attached with EDX spectrometer with ultrathin window (EDAX, USA). The specimens for transmission electron microscopy (TEM) were prepared by an electrochemical or ion etching. It was found that the received alloys exhibits along with fcc Al and Al4La (Al11La3) particles, these alloys contain a ternary phase Al3Ni1 Fe isostructural to the Al3Ni phase and a quaternary phase Al8Fe2 NiLa isostructural to the Al8Fe2Eu phase and monoclinic phase Al9(Fe,Ni)2 isostructural to the Al9Co2. The study by HRSTEM together with a new atomic resolution energy dispersive X-ray microanalysis method demonstrated that Fe and Ni atoms substituted one another in the Al8Fe2–NiLa quaternary compound. Besides, several types of defects were determined: first

  7. Preparation and electrochemical properties of La_0_._7_0Mg_xNi_2_._4_5Co_0_._7_5Al_0_._3_0 (x = 0, 0.30, 0.33, 0.36, 0.39) hydrogen storage alloys

    International Nuclear Information System (INIS)

    Tian, Xiao; Wei, Wei; Duan, Ruxia; Zheng, Xinyao; Zhang, Huaiwei; Tegus, O.; Li, Xingguo

    2016-01-01

    The as-cast alloy with the composition of La_0_._7_0Ni_2_._4_5Co_0_._7_5Al_0_._3_0 was prepared by vacuum arc melting. La–Mg–Ni-based La_0_._7_0Mg_xNi_2_._4_5Co_0_._7_5Al_0_._3_0 hydrogen storage alloy has been synthesized by high-energy vibratory milling blending of the La_0_._7_0Ni_2_._4_5Co_0_._7_5Al_0_._3_0 as-cast alloy and elemental Mg, followed by an isothermal annealing. The microstructures and electrochemical properties of the La_0_._7_0Ni_2_._4_5Co_0_._7_5Al_0_._3_0 and La_0_._7_0Mg_xNi_2_._4_5Co_0_._7_5Al_0_._3_0 alloys were investigated by XRD, SEM and electrochemical measurements. The XRD analysis and Rietveld refinement showed that the as-cast La_0_._7_0Ni_2_._4_5Co_0_._7_5Al_0_._3_0 alloy consists of single LaNi_5 phase, whereas the La_0_._7_0Mg_xNi_2_._4_5Co_0_._7_5Al_0_._3_0 alloys contain the LaNi_5 and (La, Mg)_2Ni_7. The electrochemical measurements indicated that the maximum discharge capacity and discharge potential characteristic of the La_0_._7_0Mg_xNi_2_._4_5Co_0_._7_5Al_0_._3_0 alloys increases first and then decreases with increasing x. The maximum discharge capacity and discharge potential characteristic of alloy reaches the optimum when x is 0.36. The cyclic stability of the La_0_._7_0Mg_xNi_2_._4_5Co_0_._7_5Al_0_._3_0 alloy with a smaller quantity of Mg is better than that of the alloy with a larger quantity of Mg. - Highlights: • La–Mg–Ni-based alloy was synthesized by melting, milling and subsequent annealing. • Mg atoms exist in the La_2Ni_7 phase prior to LaNi_5 phase. • The La_0_._7_0Mg_xNi_2_._4_5Co_0_._7_5Al_0_._3_0 alloys consist of the LaNi_5 and (La, Mg)_2Ni_7. • The more Mg element the alloys contain, the easier aggregation Mg atom is. • The C_m_a_x of La_0_._7_0Mg_xNi_2_._4_5Co_0_._7_5Al_0_._3_0 alloy first increases and then decreases with rising x.

  8. Characterization on the coatings of Ni-base alloy with nano- and micron-size Sm{sub 2}O{sub 3} addition prepared by laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Shihong [School of Materials Science and Engineering, Anhui University of Technology, Maanshan City, Anhui Province 243002 (China); School of Nano and Advanced Materials Engineering, Changwon National University, 9, Sarim-Dong, Changwon, Gyeongnam 641-773 (Korea, Republic of)], E-mail: zsh10110903@hotmail.com; Li Mingxi [School of Materials Science and Engineering, Anhui University of Technology, Maanshan City, Anhui Province 243002 (China); Yoon, Jae Hong; Cho, Tong Yul [School of Nano and Advanced Materials Engineering, Changwon National University, 9, Sarim-Dong, Changwon, Gyeongnam 641-773 (Korea, Republic of)

    2008-12-01

    The coating materials are the powder mixture of micron-size Ni-base alloy powders with both 1.5 wt.% micron-size and nano-size Sm{sub 2}O{sub 3} powders, which are prepared on Q235 steel plate by 2.0 kW CO{sub 2} laser deposition. The results indicate that with rare earth oxide Sm{sub 2}O{sub 3} addition, the width of planar crystallization is smaller than that of the Ni-base alloy coatings. Micron- and nano-Sm{sub 2}O{sub 3}/Ni-base alloy coatings have similar microstructure showing the primary phase of {gamma}-Ni dendrite and eutectic containing {gamma}-Ni and Cr{sub 23}C{sub 6} phases. However, compared to micron-Sm{sub 2}O{sub 3}/Ni-base alloy, preferred orientation of {gamma}-Ni dendrite of nano-Sm{sub 2}O{sub 3}/Ni-base alloy is weakened. Planar crystal of several-{mu}m thickness is first grown and then dendrite growth is observed at 1.5% micron-Sm{sub 2}O{sub 3}/Ni-base alloy coating whereas equiaxed dendrite is grown at 1.5% nano-Sm{sub 2}O{sub 3}/Ni-base alloy coating. Hardness and wear resistance of the coating improves with decreasing Sm{sub 2}O{sub 3} size from micron to nano. The improvement on tribological property of nano-Sm{sub 2}O{sub 3}/Ni-base alloy over micron-Sm{sub 2}O{sub 3}/Ni-base alloy coatings can be attributed to the better resistance of equiaxed dendrite to adhesion interactions during the wear process. In 6 M HNO{sub 3} solution, the corrosion resistance is greatly improved with nano-Sm{sub 2}O{sub 3} addition since the decrease of corrosion ratio along grain-boundary in nano-Sm{sub 2}O{sub 3}/Ni-base alloy coating contributes to harmonization of corrosion potential.

  9. Two-dimensional nano-lattice in Fe-Co-Ni-Al-Cu alloys

    International Nuclear Information System (INIS)

    Kalanov, M.U.; Ibragimova, E.M.; Khamraeva, R.N.; Rustamova, V.M.; Ummatov, H.D.

    2007-01-01

    Full text: The high coercive strength of the dispersionally solidified alloys on the base of Fe-Co-Ni-Al-Cu system appears as a result of the special thermomagnetic annealing, when particles of the strong magnetic phase are distinguished in non-magnetic matrix along an external magnetic field direction. The neutron studying allows one to reveal the correlation between magnetization and inclusion axes, and also existence of magnetic microcell and perfectness of the lattice. This work presents results of neutron diffraction study with a double-crystal spectrometer (0.145 nm). Plate like samples of size 18 12 4 mm 3 were cut from a single crystal of alloy UNDK35 T5 along (100) plane. Magnetic field of 6 kOe was applied perpendicular to the neutron beam. Zero-field spectrum had only random variation of the background. Under the applied magnetic field two maxima appeared at the angles of 12 and 24 minute. In the case of the magnetic field directed in parallel to the scattering vector, the two maxima disappeared as expected. It is evidence that nuclear scattering is less than magnetic one and the observed maxima correspond to (10) and (20) reflections from a two dimensional ferro-magnetic microcell. The cell parameter of the magnetic microcell was found 40.6 nm. The coherent scattering region size was 120-160 nm. The ferro-magnetic rod diameter estimated from the peak widths was 16 nm. The diffraction pattern for the demagnetized sample strongly differs from the initial magnetized sample, where a diffuse reflection was observed near Bragg reflection and related with residual magnetization. So, the magnetic inclusions created in the Fe-Co-Ni-Al-Cu system at the thermomagnetic annealing by means of disintegration of the solid solution are strong ferro-magnetic and one-domain. These particles form the two-dimensional magnetic microcell and interact each to other within 3-4 periods of the cell. (authors)

  10. CO methanation over supported bimetallic Ni-Fe catalysts: From computational studies towards catalyst optimization

    DEFF Research Database (Denmark)

    Kustov, Arkadii; Frey, Anne Mette; Larsen, Kasper Emil

    2007-01-01

    with compositions 25Fe75Ni and 50Fe50Ni showed significantly better activity and in some cases also a higher selectivity to methane compared with the traditional monometallic Ni and Fe catalysts. A catalyst with composition 25Fe75Ni was found to be the most active in CO hydrogenation for the MgAl2O4 support at low...... metal loadings. At high metal concentrations, the maximum for the methanation activity was found for catalysts with composition 50Ni50Fe both on the MgAl2O4 and Al2O3 supports. This difference can be attributed to a higher reducibility of the constituting metals with increasing metal concentration......DFT calculations combined with a computational screening method have previously shown that bimetallic Ni-Fe alloys should be more active than the traditional Ni-based catalyst for CO methanation. That was confirmed experimentally for a number of bimetallic Ni-Fe catalysts supported on MgAl2O4. Here...

  11. Pack cementation diffusion coatings for Fe-base and refractory alloys. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Rapp, R.A. [Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering

    1998-03-10

    With the aid of computer-assisted calculations of the equilibrium vapor pressures in halide-activated cementation packs, processing conditions have been identified and experimentally verified for the codeposition of two or more alloying elements in a diffusion coating on a variety of steels and refractory metal alloys. A new comprehensive theory to treat the multi-component thermodynamic equilibria in the gas phase for several coexisting solid phases was developed and used. Many different processes to deposit various types of coatings on several types of steels were developed: Cr-Si codeposition for low- or medium-carbon steels, Cr-Al codeposition on low-carbon steels to yield either a Kanthal-type composition (Fe-25Cr-4Al in wt.%) or else a (Fe, Cr){sub 3}Al surface composition. An Fe{sub 3}Al substrate was aluminized to achieve an FeAl surface composition, and boron was also added to ductilize the coating. The developmental Cr-lean ORNL alloys with exceptional creep resistance were Cr-Al coated to achieve excellent oxidation resistance. Alloy wires of Ni-base were aluminized to provide an average composition of Ni{sub 3}Al for use as welding rods. Several different refractory metal alloys based on Cr-Cr{sub 2}Nb have been silicided, also with germanium additions, to provide excellent oxidation resistance. A couple of developmental Cr-Zr alloys were similarly coated and tested.

  12. Local atomic order in nanocrystalline Fe-based alloys obtained by mechanical alloying

    International Nuclear Information System (INIS)

    Jartych, E.

    2003-01-01

    Using the 57 Fe Moessbauer spectroscopy, a local atomic order in nanocrystalline alloys of iron with Al, Ni, W and Mo has been determined. Alloys were prepared by mechanical alloying method. Analysis of Moessbauer spectra was performed on the basis of the local environment model in terms of Warren-Cowley parameters. It was shown that impurity atoms are not randomly distributed in the volume of the first and the second co-ordination spheres of 57 Fe nuclei and they form clusters

  13. Application of newly developed heat resistant materials for USC boilers

    International Nuclear Information System (INIS)

    Sato, T.; Tamura, K.; Fukuda, Y.; Matsuda, J.

    2004-01-01

    This paper describes the research on the development and improvement of new high strength heat resistant steels such as SUPER304H (18Cr-9Ni-3Cu-Nb-N), NF709 (20Cr-25Ni-1.5Mo-Nb-Ti-N) and HR3C (25Cr-20Ni-Nb-N) as boiler tube, and NF616 (9Cr-0.5Mo-1.8W-Nb-V) and HCM12A (11Cr-0.4Mo-2W-Nb-V-Cu) as thick section pipe. The latest manufacturing techniques applied for these steels are introduced. In addition the high temperature strength of Alloy617 (52Ni-22Cr-13Co-9Mo-Ti-Al) that is one of the candidate materials for the next generation 700 □ USC boilers is described. (orig.)

  14. Sliding friction and wear behavior of high entropy alloys at room and elevated temperatures

    Science.gov (United States)

    Kadhim, Dheyaa

    Structure-tribological property relations have been studied for five high entropy alloys (HEAs). Microhardness, room and elevated (100°C and 300°C) temperature sliding friction coefficients and wear rates were determined for five HEAs: Co0.5 Cr Cu0.5 Fe Ni1.5 Al Ti0.4; Co Cr Fe Ni Al0.25 Ti0.75; Ti V Nb Cr Al; Al0.3CoCrFeNi; and Al0.3CuCrFeNi2. Wear surfaces were characterized with scanning electron microscopy and micro-Raman spectroscopy to determine the wear mechanisms and tribochemical phases, respectively. It was determined that the two HEAs Co0.5 Cr Cu0.5 Fe Ni1.5 Al Ti0.4 and Ti V Nb Cr Al exhibit an excellent balance of high hardness, low friction coefficients and wear rates compared to 440C stainless steel, a currently used bearing steel. This was attributed to their more ductile body centered cubic (BCC) solid solution phase along with the formation of tribochemical Cr oxide and Nb oxide phases, respectively, in the wear surfaces. This study provides guidelines for fabricating novel, low-friction, and wear-resistant HEAs for potential use at room and elevated temperatures, which will help reduce energy and material losses in friction and wear applications.

  15. Ni-Cr based dental alloys; Ni release, corrosion and biological evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Reclaru, L., E-mail: lucien.reclaru@pxgroup.com [PX Holding S.A., Dep R and D Corrosion and Biocompatibility Group, Bd. des Eplatures 42, CH-2304 La Chaux-de-Fonds (Switzerland); Unger, R.E.; Kirkpatrick, C.J. [Institute for Pathology, REPAIR Lab, University Medical Center, Johannes Gutenberg University Mainz, Langenbeckstr.1, D-55101 Mainz (Germany); Susz, C.; Eschler, P.-Y.; Zuercher, M.-H. [PX Holding S.A., Dep R and D Corrosion and Biocompatibility Group, Bd. des Eplatures 42, CH-2304 La Chaux-de-Fonds (Switzerland); Antoniac, I. [Materials Science and Engineering Faculty, Politehnica of Bucharest, 060042 Bucharest (Romania); Luethy, H. [Institute of Dental Materials Science and Technology, University of Basel, Hebelstrasse 3, CH-4056 Basel (Switzerland)

    2012-08-01

    In the last years the dental alloy market has undergone dramatic changes for reasons of economy and biocompatibility. Nickel based alloys have become widely used substitute for the much more expensive precious metal alloys. In Europe the prevalence of nickel allergy is 10-15% for female adults and 1-3% for male adults. Despite the restrictions imposed by the EU for the protection of the general population in contact dermatitis, the use of Ni-Cr dental alloys is on the increase. Some questions have to be faced regarding the safety risk of nickel contained in dental alloys. We have collected based on many EU markets, 8 Ni-Cr dental alloys. Microstructure characterization, corrosion resistance (generalized, crevice and pitting) in saliva and the quantities of cations released in particular nickel and CrVI have been evaluated. We have applied non parametric classification tests (Kendall rank correlation) for all chemical results. Also cytotoxicity tests and an evaluation specific to TNF-alpha have been conducted. According to the obtained results, it was found that their behavior to corrosion was weak but that nickel release was high. The quantities of nickel released are higher than the limits imposed in the EU concerning contact with the skin or piercing. Surprisingly the biological tests did not show any cytotoxic effect on Hela and L929 cells or any change in TNF-alpha expression in monocytic cells. The alloys did not show any proinflammatory response in endothelial cells as demonstrated by the absence of ICAM-1 induction. We note therefore that there is really no direct relationship between the in vitro biological evaluation tests and the physico-chemical characterization of these dental alloys. Clinical and epidemiological studies are required to clarify these aspects. - Highlights: Black-Right-Pointing-Pointer Nickel released was higher than the limits imposed in EU in contact with the skin. Black-Right-Pointing-Pointer No direct relationship between the

  16. The effect of carbon distribution on deformation and cracking of Ni-16Cr-9Fe-C alloys

    International Nuclear Information System (INIS)

    Hertzberg, J.L.; Was, G.S.

    1995-01-01

    Constant extension rate tensile (CERT) tests and constant load tensile (CLT) tests were conducted on controlled purity Ni-16Cr-9Fe-C alloys. The amount and form of carbon were varied in order to investigate the roles of carbon in solution and as intergranular (IG) carbides in the deformation and IG cracking behavior in 360 C argon and primary water environments. Results show that the strength, ductility and creep resistance of these alloys are increased with carbon present in solid solution, while IG cracking on the fracture surface is suppressed. Alloys containing carbon in the form of IG carbides, however, exhibit reduced strength and ductility relative to carbon in solution, while maintaining high IG cracking resistance with respect to carbon-free alloys. CERT results of commercial alloy 600 and controlled purity, carbon containing alloys yield comparable failure strains and IG cracking amounts. CLT comparisons with creep tests of alloy 600 suggest that alloys containing IG carbides are more susceptible to creep than those containing all carbon in solid solution

  17. Moessbauer spectra studied of spin-wave excitation for amorphous alloys

    International Nuclear Information System (INIS)

    Huang Zhigao

    1992-01-01

    The average hyperfine fields of amorphous Fe 70 Co 20 Zr 10 , Fe 80 Co 10 Zr 10 and Fe 86 Co 4 -Zr 10 alloys at different temperature were measured by the Moessbauer technique. According to Bloch's T 3/2 relation, spin-wave excitations of above amorphous alloys were studied and their B 3/2 values were found to be 0.40 +- 0.02, 0.45 +- 0.02 and 0.88 +- 0.04, respectively. Comparing the B 3/2 values of crystals, a-Fe-(Co, Ni)-ME, a-Fe-(Cr, Mn, W)-ME and a-Fe-B or TM-Zr invar alloys, the obvious difference among them was observed. Above results can be explained well by the exchange coupling fluctuation and the disorder of spatial arrangement. In this work, the difference between the stiffness coefficients obtained from the inelastic neutron scattering and the magnetization measurements for amorphous Invar alloys was also explained

  18. The investigation of Fe-Mn-based alloys with shape memory effect by small-angle scattering of polarized neutrons

    International Nuclear Information System (INIS)

    Kopitsa, G.P.; Runov, V.V.; Grigoriev, S.V.; Bliznuk, V.V.; Gavriljuk, V.G.; Glavatska, N.I.

    2003-01-01

    The small-angle polarized neutron scattering (SAPNS) technique has been used to study a nuclear and magnetic homogeneity in the distribution of both substituent (Si, Cr, Ni) and interstitial (C, N) alloying elements on the mesoscopic range in Fe-Mn-based alloys with shape memory effect (SME). The four groups of alloys with various basic compositions: FeMn 18 (wt%), FeMn 20 Si 6 , FeMn 20 Cr 9 N 0.2 and FeMn 17 Cr 9 Ni 4 Si 6 were investigated. It was found that the small-angle scattering of neutrons and depolarization on these alloys are very small altogether. The scattering did not exceed 1.5% from the incident beam and depolarization ∼2% for all samples. It means that these alloys are well nuclear and magnetically homogeneous on the scale of 10-1000 A. However, the difference in the homogeneity depending on the compositions still takes place. Thus, the adding of Si in FeMn 18 and FeMn 20 Cr 9 N 0.2 alloys improves the homogeneity pronouncedly. At once, the effect of the doping by C or N atoms on the homogeneity in FeMn 20 Si 6 and FeMn 17 Cr 9 Ni 4 Si 6 alloys is multivalued and depend on the presence of substitutional atoms (Ni and Cr). The capability of SAPNS as a method for the study of mesoscopic homogeneity in materials with SME and testing of the quality of their preparation is discussed

  19. Effect of Heat Treatment on Morphology of Fe-Rich Intermetallics in Hypereutectic Al-Si-Cu-Ni Alloy with 1.26 pct Fe

    Science.gov (United States)

    Sha, Meng; Wu, Shusen; Wan, Li; Lü, Shulin

    2013-12-01

    Cobalt is generally considered as the element that can neutralize the negative effects of iron in Al alloys, such as inducing fracture and failure for stress concentration. Nevertheless, Fe-rich intermetallics would be inclined to form coarse plate-like δ-Al4(Fe, Co, Ni)Si2 particles when the content of Fe was high, which could also cause inferior mechanical properties. The dissolution and transformation of δ-Al4(Fe, Co, Ni)Si2 phase in solution heat-treated samples of Al-20Si-1.85Cu-1.05Ni-1.26Fe-1.35Co alloy were studied using optical microscopy, image analysis, and scanning electron microscopy. The effects of solution heat treatment time ranging from 0 to 9 hours at 783.15 K (510 °C) on mechanical properties were also investigated. The coarse plate-like δ-Al4(Fe, Co, Ni)Si2 particles varied slowly through concurrent dissolution along widths and at the plate tips as solution treatment time increased, which could be explained from diffusion-induced grain boundary migration. Solution heat treatment also has an important influence on mechanical properties. The maximum ultimate tensile strength and yield strength after T6 treatment were 258 and 132 MPa, respectively, while the maximum hardness was 131 HB. Compared with those of the samples in the as-cast state, they increased by 53, 42, and 28 pct, respectively. Moreover, δ-Al4(Fe, Co, Ni)Si2 phase, which appears as a coarse plate-like particle in two dimensions, is actually a cuboid in three dimensions. The length of this cuboid is close to the width, while the height is much smaller.

  20. Low temperature thermal conductivity of amorphous (Fe, Ni, Co) (P, B, Si) alloys and their change by heat treatment

    International Nuclear Information System (INIS)

    Pompe, G.; Gaafar, M.; Buettner, P.; Francke, T.

    1983-01-01

    The thermal conductivity of amorphous metallic alloys (Fe, Ni, Co)/sub 1-x/ (B, P, Si)/sub x/ is measured in the temperature range 2 to 100 K in the as-produced and heat-treated states. By taking into account the results of Matey and Anderson the influence of the nature of the metalloid and the number of metallic components can be discussed. The change of the thermal conductivity due to a structural relaxation caused by a heat treatment is very different. In the whole range of temperature a rise of the phonon thermal conductivity of the Fe-Co-B alloy is obtained, whereas no change is observed for the Fe-B alloy. At low temperature ( 80 B 20 is investigated. (author)