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Sample records for cr ni mn

  1. 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

    2017-07-01

    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.

  2. Microstructure of Steel 5Cr21Mn9Ni4N Alloyed by Rare Earth

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The microstructure, composition and shape of precipitated phase under as-cast and finished product state of 5Cr21Mn9Ni4N steel with different rare earth (RE) amount were studied. Mechanical properties of 5Cr21Mn9Ni4N steels withont RE addition and with RE added by 0. 2 % in mass percent were tested respectively. The results indicate that the solid solution amount of RE is about 10-6 -10-5 order of magnitude in 5Cr21Mn9Ni4N steel. Dendrite of as-cast condition is refined obviously and dimension of interstitial phase is shortened when RE is added by 0. 10%-0. 20%. But the microstructure will be coarser if surplus RE is added. Precipitated phase under finished product state distributes evenly in nearly same size with RE added by 0.2% which leads to a largely improved high temperature mechanical property.

  3. Change in the properties of Fe-Cr-Ni and Fe-Cr-Mn austenitic steels under mixed and fast neutron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Shamardin, V.K. [State Sci. Centre of Russian Federation, Dimitrovgrad (Russian Federation). Res. Inst. of Atomic Reactors; Bulanova, T.M. [State Sci. Centre of Russian Federation, Dimitrovgrad (Russian Federation). Res. Inst. of Atomic Reactors; Golovanov, V.N. [State Sci. Centre of Russian Federation, Dimitrovgrad (Russian Federation). Res. Inst. of Atomic Reactors; Neustroyev, V.S. [State Sci. Centre of Russian Federation, Dimitrovgrad (Russian Federation). Res. Inst. of Atomic Reactors; Povstyanko, A.V. [State Sci. Centre of Russian Federation, Dimitrovgrad (Russian Federation). Res. Inst. of Atomic Reactors; Ostrovsky, Z.E. [State Sci. Centre of Russian Federation, Dimitrovgrad (Russian Federation). Res. Inst. of Atomic Reactors

    1996-10-01

    Detailed investigations are performed on mechanical properties, swelling and structure of different types of Fe-Cr-Ni and Fe-Cr-Mn austenitic stainless steels irradiated in the SM-2 high-flux research reactor and BOR-60 fast reactor. Steel irradiation temperatures are ranging from 100 up to 800 C and the maximum achieved level of damage doses is 60 dpa for Fe-Cr-Mn steel (with 4-5% of Ni) and 30 dpa for steels of the C-12Cr-20Mn-W-T type. Presented are dose dependencies of swelling and mechanical properties of Fe-Cr-Ni and Fe-Cr-Mn steels. It is shown that at temperatures below 530 C the investigated Fe-Cr-Mn steel systems are less susceptible to swelling as compared to Fe-Cr-Ni ones. Fe-Cr-Mn steels showed a lower value of irradiation embrittlement after irradiation in the mixed spectrum at temperatures from 100 up to 400 C and much higher embrittlement after irradiation from 350 up to 400 C in the fast spectrum in comparison with Fe-Cr-Ni steels. Higher hardening rate of Fe-Cr-Mn steels after their irradiation in BOR-60 is attributed to the presence of dislocation loops and defects of high density in the structure. The structural change features in Fe-Cr-Mn steels under irradiation are considered taking into account austenite stabilization in the initial state. (orig.).

  4. Room temperature magnetocaloric effect in Ni-Mn-In-Cr ferromagnetic shape memory alloy thin films

    Science.gov (United States)

    Akkera, Harish Sharma; Singh, Inderdeep; Kaur, Davinder

    2017-02-01

    The influence of Cr substitution for In on the martensitic phase transformation and magnetocaloric effect (MCE) has been investigated in Ni-Mn-Cr-In ferromagnetic shape memory alloy (FSMA) thin films fabricated by magnetron sputtering. Temperature dependent magnetization (M-T) measurements demonstrated that the martensitic transformation temperatures (TM) monotonously increase with the increase of Cr content due to change in valence electron concentration (e/a) and cell volume. From the study of isothermal magnetization curves (M-H), magnetocaloric effect around the martensitic transformation has been investigated in these FSMA thin films. The magnetic entropy change ∆SM of 7.0 mJ/cm3-K was observed in Ni51.1Mn34.9In9.5Cr4.5 film at 302 K in an applied field of 2 T. Further, the refrigerant capacity (RC) was also calculated for all the films in an applied field of 2 T. These findings indicate that the Cr doped Ni-Mn-In FSMA thin films are potential candidates for room temperature micro-length-scale magnetic refrigeration applications.

  5. First-Principles Study on the Half-Metallicity of Half-Heusler Alloys: XYZ (X=Mn, Ni; Y=Cr, Mn; Z=As, Sb)

    Institute of Scientific and Technical Information of China (English)

    LI Guan-Nan; JIN Ying-Jiu

    2009-01-01

    The electronic structures, magnetism, and half-metallicity of half-Heusler alloys XYZ (X=Mn, Ni; Y=Cr, Mn;Z=As, Sb) are investigated by means of the full-potential linearized augmented plane wave method within the generalized gradient approximation.We consider three types of atomic ordering (i.e.,α,β, and γ phases for all of the alloys) and find that the a phase is energetically the most stable.From the calculated density of states and the total magnetic moments, we find that NiMnZ (Z=As, Sb) and NiCrAs are half-metallic ferromagnets, MnCrAs is a half-metallic antiferromagnet, and NiCrSb (MnCrSb) is almost a half-metallic ferromagnet (antiferromagnet).

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

    Science.gov (United States)

    Ye, Qingfeng; Feng, Kai; Li, Zhuguo; Lu, Fenggui; Li, Ruifeng; Huang, Jian; Wu, Yixiong

    2017-02-01

    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 icorr 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 Rt 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 H2SO4 reveals that corrosion starts from Cr-depleted interdendrites.

  7. Factors Affecting Transformation Temperatures in Fe-Mn-Si-Cr-Ni Shape Memory Alloy

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    @@The effects of prestrain and annealing temperature on phase transformation temperatures in Fe14Mn5Si8Cr4Ni shape memory alloy have been studied. The results showed that when the annealing temperature was 673 K, both the Af and the Ms temperatures increased appreciably as the prestrain increased, the As temperature increased slightly with increasing prestrain; the resistivity difference at 303 K between the heating and cooling curve also increased with increasing prestrain, which agreed with the recovery strain. The shape memory effect in Fe-Mn-Si-Cr-Ni shape memory alloy is caused by the stress-induced γ → ε martensite transformation and its reverse transformation. When the prestrain was 10%, the Ms temperature decreased remarkably as the annealing temperature increased.

  8. Tensile properties and fracture surface of 07MnNiCrMoVDR steel welded joint at low temperature

    Institute of Scientific and Technical Information of China (English)

    Zhang Lihong; Chen Furong; Xie Ruijun

    2009-01-01

    The tensile properties and fracture surfuce of 07MnNiCrMoVDR steel welded joint at low temperature have been studied by universal testing machine and scanning electron microscope. The results show that the tensile properties of 07MnNiCrMoVDR steel welded joint are greatly affected by temperature. Tensile strength and yield strength of 07MnNiCrMoVDR steel welded joint increase, bat elongation and reduction of area decrease with temperature decreasing. The macro-fracture of 07 MnNiCrMoVDR steel welded joint exhibits that the shear lip is not significant and micro-fracture makes up of dimpled fracture and tear fracture, and dimple becomes tiny and uniform with temperature decreasing.

  9. Electronic and magnetic properties of Cr-Mn-Ni-Al compound with LiMgPdSb-type structure

    Science.gov (United States)

    Wang, L. Y.; Wang, X. T.; Guo, R. K.; Lin, T. T.; Liu, G. D.

    2016-10-01

    We investigate the electronic and magnetic properties of Cr-Mn-Ni-Al compound with a LiMgPdSn-type structure in three different atomic arrangement configurations (AAC) by using the first-principles calculations. It was found that Cr-Mn-Ni-Al compound with type I AAC exhibits a spin-gapless semiconductive characteristic. The type II AAC is the most stable one and exhibits an especial band structure where the Fermi level slightly crosses the top of the valence bands in spin-up channel and the bottom of conductive bands in spin-down channel, which leads to the electronic transport with the spin-resolved carrier type. The Cr-Mn-Ni-Al compound shows an ordinary metallic behavior in type III AAC. The three nonequivalent atomic arrangement configurations of Cr-Mn-Ni-Al are all in ferromagnetic ground state under their equilibrium lattice parameters.

  10. Metabolismo del Mg, Cu, Zn, Cr, Mn, y Ni en la diabetes melitus

    OpenAIRE

    1995-01-01

    En los últimos años, a los elementos traza y al mg se las ha implicado en la patologenesis de las complicaciones crónicas de la diabetes mellitus (dm). Las alteraciones del estado mineral asociadas a la dm podrían estar influidas, entre otros factores, por el grado de control metabólico y la asociación, o no, de otras patologías metabólicas como la hipertensión arterial (hta), la dislipemia y la obesidad. A pesar de que el mg, cu, zn, cr, mn y ni son cationes de localización principalmente in...

  11. Effect of aging on the microstructure and tensile properties of Fe-Ni-Mn-Cr maraging alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hossein Nedjad, S. [Faculty of Materials Engineering, Sahand University of Technology, P.O. Box 51335-1996, Tabriz (Iran, Islamic Republic of)], E-mail: hossein@sut.ac.ir; Meimandi, S.; Mahmoudi, A.; Abedi, T.; Yazdani, S. [Faculty of Materials Engineering, Sahand University of Technology, P.O. Box 51335-1996, Tabriz (Iran, Islamic Republic of); Shirazi, H.; Nili Ahmadabadi, M. [School of Metallurgy and Materials Engineering, University of Tehran, P.O. Box 14395-731, Tehran (Iran, Islamic Republic of)

    2009-02-15

    Effect of aging on the microstructure and mechanical properties of chromium-containing Fe-Ni-Mn maraging alloys was studied. An Fe-10Ni-7Mn-2Cr (wt.%) alloy exhibited strong age hardenability but suffered from premature intergranular brittleness after aging. Further chromium addition resulted in partial austenite retention in Fe-10Ni-7Mn-6Cr (wt.%) and Fe-10Ni-7Mn-9Cr (wt.%) alloys at ambient temperature. The retained austenite exhibited mechanical instability during tensile loading at ambient temperature and transformed into martensite substantially, aiming at large tensile ductility. Age hardenability of the studied alloys decreased by increasing of retained austenite. In an Fe-10Ni-7Mn-6Cr (wt.%) alloy, transmission electron microscopy studies represented pronounced precipitation of a face-centered tetragonal (fct) {theta}-NiMn intermetallics in martensite and weak precipitation of a needle-shaped phase in retained austenite. After aging of the partially transformed alloy, yield strength increased moderately while tensile ductility decreased drastically. The ductility loss is mainly attributed to the premature intergranular fracture initiating within the aged martensite.

  12. Corrosion Behavior of Thermally Sprayed NiCrBSi Coating on 16MnR Low-Alloy Steel in KOH Solution

    Science.gov (United States)

    Zeng, Q.; Sun, J.; Emori, W.; Jiang, S. L.

    2016-05-01

    NiCrBSi coatings were selected as protective material and air plasma-sprayed on 16MnR low-alloy steel substrates. Corrosion behavior of 16MnR substrates and NiCrBSi coatings in KOH solution were evaluated by polarization resistance ( R p), potentiodynamic polarization curves, electrochemical impedance spectroscopy, and immersion corrosion tests. Electrolytes were solutions with different KOH concentrations. NiCrBSi coating showed superior corrosion resistance in KOH solution compared with the 16MnR. Corrosion current density of 16MnR substrate was 1.7-13.0 times that of NiCrBSi coating in the given concentration of KOH solution. By contrast, R p of NiCrBSi coating was 1.2-8.0 times that of the substrate, indicating that the corrosion rate of NiCrBSi coating was much lower than that of 16MnR substrate. Capacitance and total impedance value of NiCrBSi coating were much higher than those of 16MnR substrate in the same condition. This result indicates that corrosion resistance of NiCrBSi coating was better than that of 16MnR substrate, in accordance with polarization results. NiCrBSi coatings provided good protection for 16MnR substrate in KOH solution. Corrosion products were mainly Ni/Fe/Cr oxides.

  13. Concentrations of heavy metals (Mn, Co, Ni, Cr, Ag, Pb) in coffee.

    Science.gov (United States)

    Nędzarek, Arkadiusz; Tórz, Agnieszka; Karakiewicz, Beata; Clark, Jeremy Simon; Laszczyńska, Maria; Kaleta, Agnieszka; Adler, Grażyna

    2013-01-01

    Technologies involved in roasting coffee beans, as well as the methods used to prepare infusions, vary according to culture, and contribute to differences in the concentration of elements in the drink. Concentrations of six elements: manganese (Mn), cobalt (Co), nickel (Ni), chrome (Cr), silver (Ag) and lead (Pb) were investigated in coffee infusions from eleven samples of coffee, roasted and purchased in four countries: Bosnia and Herzegovina, Brazil, Lebanon and Poland. Metal concentrations were determined using an induction coupled plasma technique in combination with mass spectrometry (ICP-MS, Perkin Elmer) which measures total metal (ionic and non-ionic) content. Metal intake estimated for individual countries (in the respective order; mean consumption per person per year) was as follows: Mn: 26.8-33.1, 28.3-29.5, 29.7, 12.6-18.9 mg; Co: 0.33-0.48, 0.42-0.35, 0.32, 0.12-0.17 mg; Ni: 3.83-5.68, 4.85-5.51, 4.04, 2.06-2.24 mg; Cr: 0.17-0.41, 0.21-0.47, 0.17, 0.09-0.28 mg; Ag: 0.16-1.13, 0.26-0.70, 0.61, 0.33-1.54 mg, Pb: 4.76-7.56, 3.59-5.13, 3.33, 1.48-2.43 mg. This finding gives new data for Mn, Co, Ni, Cr, and Ag intake from coffee , and suggests that the amounts are negligible. However, the data for Pb consumption in heavy drinkers, for example in Bosnia and Herzegovina, indicate that Pb intake from coffee may contribute to the disease burden. The high lead level in some coffees suggests the need for a more precise control of coffee contamination.

  14. Effects of the partial substitution of Ni by Cr on the transport, magnetic, and magnetocaloric properties of Ni50Mn37In13

    Science.gov (United States)

    Pandey, Sudip; Quetz, Abdiel; Aryal, Anil; Saleheen, Ahmad Us; Rodionov, Igor; Blinov, Mikhail; Prudnikova, Mariya; Dubenko, Igor; Prudnikov, Valerii; Mazumdar, Dipanjan; Granovsky, Alexander; Stadler, Shane; Ali, Naushad

    2017-05-01

    The structural, magnetic, and magnetotransport properties of Ni50-xCrxMn37In13 Heusler alloys have been synthesized and investigated by x-ray diffraction (XRD), field and pressure dependent magnetization, and electrical resistivity measurements. The partial substitution of Ni by Cr in Ni50Mn37In13 significantly improves the magnetocaloric effect in the vicinity of the martensitic transition (TM). This system also shows a large negative entropy change at the Curie temperature (TC), making it a candidate material for application in a refrigeration cycle that exploits both positive and negative magnetic entropy changes. The refrigeration capacity (RC) values at TM and TC increase significantly by more than 20 % with Cr substitution. The application of hydrostatic pressure increases the temperature stability of the martensitic phase in Ni45Cr5Mn37In13. The influence of Cr substitution on the transport properties of Ni48Cr2Mn37In13 is discussed. An asymmetric magnetoresistance, i.e., a spin-valve-like behavior, has been observed near TM for Ni48Cr2Mn37In13.

  15. Abrasive Wear of Fe-Mn-Si-Cr-Ni Shape Memory Stainless Steel: Preliminary Results

    Science.gov (United States)

    Silva, Christian Egidio Da; Bernardi, Heide Heloise; Otubo, Jorge

    2011-07-01

    This study was developed to understand the influence of chemical composition and austenitic grain size on the wear resistance in stainless shape memory steel. A two-body abrasive wear device was used to understand the wear mechanism involved. They were tested pins with the following chemical composition: Fe-10.3Mn-5.3Si-9.9Cr-4.9Ni-0.006C and Fe-14.2Mn-5.3Si-8.8Cr-4.6Ni-0.008C after being austenitized at 900 and 1050 °C, followed by water quenching. The surface characterization was performed by optical microscopy and scanning electron microscopy, and the roughness profile evaluation was also conducted. The weight loss was measured after conducting the wear testing, and the wear rates were estimated. The results demonstrated that the alloy with less manganese and higher chromium content has the best wear resistance (between 17.5 and 18.9%). With an increase of the austenitic grain size there was a small reduction on the wear resistance (between 3.0 and 4.1%). The chemical composition demonstrated to have higher influence on the wear behavior than the austenitic grain size.

  16. Sol-Gel Synthesis of LaMO3 (M = Cr, Mn, Fe, Co, Ni) Nanocrystalline Powders

    Institute of Scientific and Technical Information of China (English)

    Chen Zhanheng; Xing Xianran; Dai Jing; Huang Xiaowei; Li Hongwei

    2004-01-01

    Sol-gel synthesis of LaMO3 ( M = Cr, Mn, Fe, Co, Ni) nanocrystalline Powders was investigated. DSC measurement shows that precursors decomposed at about 403 K and 620 K to bum out of N, C, and H. The calcined samples at 1073 K were determined by XRD to be single phase. SEM observation shows that the prepared samples are nanocrystalline powders in broad sense. The average grain size of LaM'O3 (M'= Cr, Mn, Fe, Ni) is 150 ~700 nm,and the grain size of LaCoO3 is about 30 nm.

  17. Mechanical characteristics and swelling of austenitic Fe-Cr-Mn steels irradiated in the SM-2 and BOR-60 reactors. [0. 4C-12Cr-19Mn-2Ni-Mo-N; 0. 4C-12Cr-14Mn-5Ni-Mo-2Al-B; 0. 4C-17Cr-17Mn-Cu-Mo-Nb-N; Fe-Cr-Ni steel: 0. 8C-16Cr-15Ni-3Mo-Nb; 316; 304

    Energy Technology Data Exchange (ETDEWEB)

    Shamardin, V.K.; Bulanova, T.M.; Neustroev, V.S. (Lenin (V.I.) Research Inst. of Atomic Reactors, Dimitrovgrad (USSR)); Ivanov, L.I.; Djomina, E.V.; Platov, Yu.M. (AN SSSR, Moscow (USSR). A.A. Baikov Inst. of Metallurgy)

    Three types of austenitic Fe-Cr-Mn stainless steels were irradiated simultaneously with Fe-Cr-Ni austenitic steel at temperatures from 400 to 800deg C in the mixed spectrum of the high flux SM-2 reactor to 10 dpa and 700 appm of He and in the BOR-60 reactor to 60 dpa without He generation. The paper presents the swelling and mechanical properties of steels irradiated in the BOR-60 and SM-2 as a function of the concentration of transmuted He and the value of atomic displacement. (orig.).

  18. First-principles and Monte Carlo studies of the Ni2(Mn,Cr)Ga Heusler alloys electronic and magnetic properties

    Science.gov (United States)

    Zagrebin, M. A.; Sokolovskiy, V. V.; Smolyakova, E. E.; Buchelnikov, V. D.

    2017-02-01

    Structural, magnetic and electronic properties of a series of Ni2Mn1-x Cr x Ga Heusler alloys have been studied by means of ab initio calculations and Monte Carlo simulations. The optimized lattice parameters of all investigated compositions are close to 5.81 Å and weakly depend on Cr excess. The martensitic transformation in Ni-Mn-Cr-Ga alloys occurs in all compositional range. Tetragonal distortions weakly depend on Cr concentration. Besides, an increase in energy difference between austenite and martensite with increasing Cr content was observed. For electronic and magnetic properties, it was observed that Ni2Mn1-x Cr x Ga demonstrate the metallic behavior. Using the SPR-KKR calculations of magnetic exchange constants, we have shown that the largest contribution to the total exchange energy is associated between nearest neighbor Ni-Mn pair. These inter-sublattice interactions in austenitic phase are higher then intra-sublattice interactions (Ni-Ni and Mn(Cr)-Mn(Cr)). Estimated Curie temperatures for Ni2Mn1-x Cr x Ga are found to decrease with increasing Cr content. All obtained results are in good agreement with experimental data.

  19. Effect of Si and Nb on the solidification mode of a Cr-Ni-Mn-N austenitic hydrogen-resistant steels%Si和Nb对Cr-Ni-Mn-N奥氏体抗氢钢凝固方式的影响

    Institute of Scientific and Technical Information of China (English)

    谭军; 袁金才; 李守新; 万晔; 马禄铭; 李依依

    2002-01-01

    @@ Introduction Nitronic 50 is a Nitrogen-strengthened Cr-Ni-Mn austenitic stainless steel, with high strength and good corrosion resistance[1]. However, these properties are greatly influenced by the microstructure. When used in weld and cast condition, the microstructure with δ-ferrite as leading phase is responsible for larger resistantce to hot cracking than that with austenite as leading phase[2].

  20. Effect of Cr addition on the structural, magnetic and mechanical properties of magnetron sputtered Ni-Mn-In ferromagnetic shape memory alloy thin films

    Science.gov (United States)

    Akkera, Harish Sharma; Kaur, Davinder

    2016-12-01

    The effect of Cr substitution for In on the structural, martensitic phase transformation and mechanical properties of Ni-Mn-In ferromagnetic shape memory alloy (FSMA) thin films was systematically investigated. X-ray diffraction results revealed that the Ni-Mn-In-Cr thin films possessed purely austenitic cubic L21 structure at lower content of Cr, whereas higher Cr content, the Ni-Mn-In-Cr thin films exhibited martensitic structure at room temperature. The temperature-dependent magnetization ( M- T) and resistance ( R- T) results confirmed that the monotonous increase in martensitic transformation temperatures ( T M) with the addition of Cr content. Further, the room temperature nanoindentation studies revealed the mechanical properties such as hardness ( H), elastic modulus ( E), plasticity index ( H/ E) and resistance to plastic deformation ( H 3/ E 2) of all the samples. The addition of Cr content significantly enhanced the hardness (28.2 ± 2.4 GPa) and resistance to plastic deformation H 3/ E 2 (0.261) of Ni50.4Mn34.96In13.56Cr1.08 film as compared with pure Ni-Mn-In film. As a result, the appropriate addition of Cr significantly improved the mechanical properties with a decrease in grain size, which could be further attributed to the grain boundary strengthening mechanism. These findings indicate that the Cr-doped Ni-Mn-In FSMA thin films are potential candidates for microelectromechanical systems applications.

  1. Preparation and electrochemical properties of LiMn1.95M0.05O4 (M = Cr, Ni)

    Institute of Scientific and Technical Information of China (English)

    YU Zemin; ZHAO Liancheng

    2007-01-01

    The preparation process and electrochemical properties of LiMn2O4 and LiMn1.95M0.05O4 (M = Cr, Ni) were studied.The results show that the decomposition temperature range of xerogel prepared with lithium acetate and manganese acetate as raw materials is large and the decomposition speed is slow.Oxygen consumed is apt to get a prompt supplement during the preparation of LiMn2O4,and carbonization of the organic matter can be reduced or avoided,which is favorable to the combination of lithium and manganese.Using lithium acetate,manganese acetate, chromium nitrate,and nickel nitrate as raw materials and adopting the citric acid complexing method,it has been found that the prepared powders have high purity,high quality stability,and even doping characters. With the increase of sintering temperature,the particle size and crystal lattice constant of LiMn1.95M0.05O4 (M = Cr, Ni) enhance.However,the purity of the product is relatively high and has no obvious change,which is advantageous to the control of the quality of LiMn1.95M0.05O4 (M = Cr, NJ).Doping with a small amount of Cr3+ and Ni2+ can stabilize the spinel structure of LiMn2O4,suppress the Jahn-Teller effect,and improve the cycling properties but reduce the initial capacity.

  2. Microstructure and Mechanical Properties After Shock Wave Loading of Cast CrMnNi TRIP Steel

    Science.gov (United States)

    Eckner, Ralf; Krüger, L.; Ullrich, C.; Rafaja, D.; Schlothauer, T.; Heide, G.

    2016-10-01

    The mechanical response of shock wave-prestrained high-alloy Cr16-Mn7-Ni6 TRIP steel was investigated under compressive and tensile loading at room temperature. Previous shock wave loading was carried out using a flyer-plate assembly with different amounts of explosives in order to achieve shock pressures of 0.3, 0.6, 0.9, and 1.2 Mbar. A significant increase in hardness and strength was observed as compared with the initial as-cast condition. In contrast, a slight decrease in strain hardening rates was measured together with a decrease in fracture elongation in the tensile test. Microstructural analyses of the shock-loaded samples were performed by light optical and scanning electron microscopy. The microstructure revealed a high density of deformation bands consisting of separated stacking faults, ɛ-martensite, or twins. Significant amounts of deformation-induced α'-martensite were only present at the highest shock pressure of 1.2 Mbar. The thickness of the deformation bands and the number of martensite nuclei at their intersections increased with increasing shock pressure. In all shock-loaded specimens, pronounced phase transformation occurred during subsequent mechanical testing. Consequently, the amount of the deformation-induced α'-martensite in the shock-loaded specimens was higher than in the unshocked as-cast samples.

  3. Electrokinetic recovery of Cd, Cr, As, Ni, Zn and Mn from waste printed circuit boards: effect of assisting agents.

    Science.gov (United States)

    Xiu, Fu-Rong; Zhang, Fu-Shen

    2009-10-15

    The printed circuit boards (PCBs) contains large number of heavy metal such as Cd, Cr, As, Ni, Zn and Mn. In this study, the use of electrokinetic (EK) treatment with different assisting agents has been investigated to recover the heavy metals from waste PCBs, and the effectiveness of different assisting agents (HNO(3), HCl, citric acid) was evaluated. The PCBs were first pre-treated by supercritical water oxidation (SCWO) process, then subjected to EK process. The heavy metal speciation, migration and recovery efficiency in the presence of different assisting agents during EK process were discussed. The mass loss of Cd, Cr, As and Zn during the SCWO process was negligible, but approximately 52% of Ni and 56% of Mn were lost in such a process. Experimental results showed that different assisting agents have significant effect on the behavior and recovery efficiency of different heavy metals. HCl was highly efficient for the recovery of Cd in waste PCBs due to the low pH and the stable complexation of Cl(-). Citric acid was highly efficient for the recovery of Cr, Zn and Mn. HNO(3) was low efficient for recovery of most heavy metals except for Ni.

  4. Effect of ageing temperature after tensile pre deformation on shape memory effect and precipitation process of Cr{sub 23}C{sub 6} carbide in a FeMnSiCrNiC alloy

    Energy Technology Data Exchange (ETDEWEB)

    Yang, S.Z. [College of Manufacturing Science and Engineering, Sichuan University, 24, South Section 1, Yihuan Road, Chengdu 610065, Sichuan (China); College of Material Science and Engineering, Xihua University, Chengdu 610039 (China); Li, N., E-mail: yangshizhou@163.com [College of Manufacturing Science and Engineering, Sichuan University, 24, South Section 1, Yihuan Road, Chengdu 610065, Sichuan (China); Wen, Y.H.; Peng, H.B. [College of Manufacturing Science and Engineering, Sichuan University, 24, South Section 1, Yihuan Road, Chengdu 610065, Sichuan (China)

    2011-11-25

    Highlights: {yields} Precipitation process of Cr{sub 23}C{sub 6} particles depends on diffusion capacity of Cr atom. {yields} Directional segregation of carbon atom can act as aligned Cr{sub 23}C{sub 6} in improving SME. {yields} Ageing temperature and ageing time greatly affect precipitation process of Cr{sub 23}C{sub 6}. {yields} NbC carbides in a FeMnSiCrNiNbC alloy are prone to dispersively precipitate. - Abstract: Researches showed that the shape memory effect (SME) of FeMnSiCrNiC alloys can be remarkably improved through aligned Cr{sub 23}C{sub 6} particles or carbon atom segregation inside grains. To further study on influencing factors in improving SME and aligned precipitation process of Cr{sub 23}C{sub 6} carbide in a FeMnSiCrNiC alloy, effect of ageing temperature after tensile pre deformation on shape memory effect and precipitation process of Cr{sub 23}C{sub 6} carbide in a FeMnSiCrNiC alloy was studied. The results showed that aligned precipitation of Cr{sub 23}C{sub 6} carbide in a FeMnSiCrNiC alloy mainly depends on diffusion capacity and directional segregation of carbon and chromium atoms, namely on ageing temperature, ageing time and the amount of tensile pre deformation.

  5. Effect of Cr addition on the structural, magnetic and mechanical properties of magnetron sputtered Ni-Mn-In ferromagnetic shape memory alloy thin films

    Energy Technology Data Exchange (ETDEWEB)

    Akkera, Harish Sharma [Indian Institute of Technology Roorkee, Functional Nanomaterials Research Lab, Department of Physics, Roorkee, Uttarakhand (India); Madanapalle Institute of Technology and Science, Department of Physics, Madanapalle, Chittoor, Andhra Pradesh (India); Kaur, Davinder [Indian Institute of Technology Roorkee, Functional Nanomaterials Research Lab, Department of Physics, Roorkee, Uttarakhand (India)

    2016-12-15

    The effect of Cr substitution for In on the structural, martensitic phase transformation and mechanical properties of Ni-Mn-In ferromagnetic shape memory alloy (FSMA) thin films was systematically investigated. X-ray diffraction results revealed that the Ni-Mn-In-Cr thin films possessed purely austenitic cubic L2{sub 1} structure at lower content of Cr, whereas higher Cr content, the Ni-Mn-In-Cr thin films exhibited martensitic structure at room temperature. The temperature-dependent magnetization (M-T) and resistance (R-T) results confirmed that the monotonous increase in martensitic transformation temperatures (T{sub M}) with the addition of Cr content. Further, the room temperature nanoindentation studies revealed the mechanical properties such as hardness (H), elastic modulus (E), plasticity index (H/E) and resistance to plastic deformation (H{sup 3}/E {sup 2}) of all the samples. The addition of Cr content significantly enhanced the hardness (28.2 ± 2.4 GPa) and resistance to plastic deformation H{sup 3}/E{sup 2} (0.261) of Ni{sub 50.4}Mn{sub 34.96}In{sub 13.56}Cr{sub 1.08} film as compared with pure Ni-Mn-In film. As a result, the appropriate addition of Cr significantly improved the mechanical properties with a decrease in grain size, which could be further attributed to the grain boundary strengthening mechanism. These findings indicate that the Cr-doped Ni-Mn-In FSMA thin films are potential candidates for microelectromechanical systems applications. (orig.)

  6. Microstructural evolution of a CoCrFeMnNi high-entropy alloy after swaging and annealing

    Energy Technology Data Exchange (ETDEWEB)

    Laplanche, G., E-mail: guillaume.laplanche@rub.de; Horst, O.; Otto, F.; Eggeler, G.; George, E.P.

    2015-10-25

    The processing parameters which govern the evolution of microstructure and texture during rotary swaging and subsequent heat treatments were studied in an equiatomic single-phase CoCrFeMnNi high-entropy alloy. After vacuum induction melting and casting, the diameter of the 40 mm cast ingot was reduced at room temperature to a final diameter of 16.5 mm by rotary swaging (diameter reduction of 60%/area reduction of 80%) and the alloy was then annealed at different temperatures for 1 h. The resulting microstructures were analyzed using scanning electron microscopy, energy-dispersive X-ray spectroscopy, electron backscatter diffraction and correlated with results of microhardness measurements. It was found that the microhardness first increases slightly upon annealing below the recrystallization temperature but then drops steeply at higher annealing temperatures due to the onset of recrystallization. Special emphasis was placed on how the microstructure evolves with respect to the radial and longitudinal position in the rod. Finally, a combination of swaging and heat treatment parameters were identified that can produce CoCrFeMnNi high-entropy alloys with a homogeneous composition and grain size and almost no texture. - Highlights: • Evolution of microstructure and texture in CoCrFeMnNi after swaging and annealing. • Rotary swaging results in major <111> + minor <100>-fiber textures. • Recrystallization (RX) in the deformed microstructure is heterogeneous. • Complete RX resulted in homogenous grain size distributions with no texture. • The low SFE is likely the reason for the homogeneous microstructure after.

  7. Variations of Ni, Cr and Mn Concentration in Soils Formed Along a Toposequence of Ultrabasic Rocks in Western Mashhad

    Directory of Open Access Journals (Sweden)

    S. Akbari

    2016-02-01

    Full Text Available Introduction: Parent materials as one of the main soil formation factors have a great impact on the concentration of heavy metals in the soil. Heavy metals are released to the soil during weathering and pedogenic processes. Ultrabasic rocks are known as the potential natural source of heavy metals, especially Ni, Cr and Mn in the soil. Average concentrations of Ni and Cr in the soils are 84 and 34 mg kg-1, respectively; while, in soil derived from ultrabasic parent material, the concentration of these elements may reach up to 100000 mg kg-1. Binaloud zone in northeastern composed of different geological materials. There is a narrow band of ophiolitic rocks in this zone that located along Mashhad city. The geochemical behavior of ultrabsic rocks and the associated soil have been frequently studied mostly in humid regions. But, there are a few research works done in arid environments. The objective of this study was to investigate the physical and chemical properties and concentrations of Ni, Cr and Mn in soils formed along a toposequence of ultrabasic rocks in western Mashhad. Materials and Methods: The study area is located in the hilly land landscape of Binaloud zone in the Western part of Mashhad. Mean annual precipitation and temperature is 260 mm and 13.7 oC, respectively. Soil temperature and moisture regimes are thermic and aridic boarder on mesic, respectively. Studied soils developed on hornblendite rocks that are ultrabasic rocks with SiO2 less than 45% and contain ferromagnesian minerals. A toposequence was selected and, three soil profiles on shoulder, backslope and footslope geomorphic positions were described acoording to key to soil taxonmy 2014 and the soil horizons were sampled. Air-dried samples were passed through 2 mm sieve and were used for laboratory analysis. Pseudo-total concentrations of Ni, Cr and Mn were extracted by aqua regia digestion procedure. Free iron oxides (Fed and amorphous iron oxides (Feo were extracted by

  8. Effect of V content on microstructure and mechanical properties of the CoCrFeMnNiV{sub x} high entropy alloys

    Energy Technology Data Exchange (ETDEWEB)

    Stepanov, N.D., E-mail: stepanov@bsu.edu.ru [Laboratory of Bulk Nanostructured Materials, Belgorod State University, Belgorod 308015 (Russian Federation); Shaysultanov, D.G.; Salishchev, G.A. [Laboratory of Bulk Nanostructured Materials, Belgorod State University, Belgorod 308015 (Russian Federation); Tikhonovsky, M.A.; Oleynik, E.E.; Tortika, A.S. [National Science Center “Kharkov Institute of Physics and Technology” NAS of Ukraine, Kharkov 61108 (Ukraine); Senkov, O.N. [UES, Inc., 4401 Dayton-Xenia Rd., Dayton, OH 45432 (United States)

    2015-04-15

    Highlights: • Structure and mechanical properties of CoCrFeMnNiV{sub x} alloys reported. • Formation of intermetallic sigma phase due to V addition. • Volume fraction of sigma phase is proportional to cumulative Cr and V concentration. • Strengthening and loss of ductility due to increase in sigma phase volume fraction. - Abstract: Crystal structure, microstructure, microhardness and compression properties of CoCrFeMnNiV{sub x} (x = 0, 0.25, 0.5, 0.75, 1) high entropy alloys were examined. The alloys were produced by vacuum arc melting and studied in as-solidified and homogenized (annealing at 1000 °C for 24 h) conditions. The CoCrFeMnNi alloy was a single-phase fcc solid solution in both conditions. The CoCrFeMnNiV{sub 0.25} alloy had a single-phase fcc structure in as-solidified condition, but ∼2 vol.% fine particles of a sigma phase precipitated after annealing. The alloys with x = 0.5, 0.75 and 1.0 contained the sigma phase already in as-solidified condition. The sigma-phase volume fraction increased with an increase in the V content, and in CoCrFeMnNiV the sigma phase became the matrix phase. After homogenization treatment, the volume fraction of the sigma phase increased in all three alloys by ∼8% due to additional precipitation of fine particles inside the fcc phase. Phase composition and microstructure of the alloys was analyzed employing criteria for solid solution/intermetallic phase formation. The effect of alloys’ chemical composition on the volume fraction of constitutive phases was discussed. A modified valence electron concentration (VEC) criterion, which takes into account localized lattice distortions around V atoms, was suggested to correctly predict sigma phase formation in the CoCrFeNiMnV{sub x} alloys. It was demonstrated that the volume fraction of sigma phase was proportional to the cumulative Cr and V concentration. Mechanical properties of the alloys were greatly affected by the sigma phase. The CoCrFeMnNi and CoCrFeMnNi

  9. Effect of one-step recrystallization on the grain boundary evolution of CoCrFeMnNi high entropy alloy and its subsystems.

    Science.gov (United States)

    Chen, Bo-Ru; Yeh, An-Chou; Yeh, Jien-Wei

    2016-02-29

    In this study, the grain boundary evolution of equiatomic CoCrFeMnNi, CoCrFeNi, and FeCoNi alloys after one-step recrystallization were investigated. The special boundary fraction and twin density of these alloys were evaluated by electron backscatter diffraction analysis. Among the three alloys tested, FeCoNi exhibited the highest special boundary fraction and twin density after one-step recrystallization. The special boundary increment after one-step recrystallization was mainly affected by grain boundary velocity, while twin density was mainly affected by average grain boundary energy and twin boundary energy.

  10. Galvanomagnetic properties of Fe{sub 2}YZ (Y = Ti, V, Cr, Mn, Fe, Ni; Z = Al, Si) heusler alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kourov, N. I., E-mail: kourov@imp.uran.ru; Marchenkov, V. V.; Belozerova, K. A. [Russian Academy of Sciences, Institute of Metal Physics, Ural Branch (Russian Federation); Weber, H. W. [Atominstitut, Vienna University of Technology (Austria)

    2015-11-15

    The Hall effect and the magnetoresistance of Fe{sub 2}YZ Heusler alloys, where Y = Ti, V, Cr, Mn, Fe, and Ni, are the 3d transition metals and Z = Al and Si are the s, p elements of the third period of the periodic table, are studied at T = 4.2 K in magnetic fields H ≤ 100 kOe. It is shown that, in the high-field limit (H > 10 kOe), the value and the sign of the normal (R{sub 0}) and anomalous (R{sub s}) Hall coefficients change anomalously during transition from paramagnetic (Y = Ti, V) to ferromagnetic (Y = Cr, Mn, Fe, Ni) alloys. These coefficients have different signs for all alloys. Constant R{sub s} in the ferromagnetic alloys is positive, proportional to the residual resistivity ratio (R{sub s} ∝ ρ{sub 0}{sup 3.1}), and inversely proportional to spontaneous magnetization. The magnetoresistance of the alloys is a few percent and has a negative sign. A positive addition to transverse magnetoresistance is only detected in high magnetic fields, H > 10 kOe.

  11. PHONON DISPERSION ofFe-18°/oCr-10°/oMn-16°/oNi and Fe-18°/oCr-12°/oNi-2°/oMo ALLOYS

    Directory of Open Access Journals (Sweden)

    Mustafa Özduran

    2006-12-01

    Full Text Available In the present paper, to investigate the. phonon frequencies of face-centered-cubic (f.c.c. Fe-1 8%Cr-1 Oo/oMn-16%Ni andFe-18%Cr-12%Ni-2%Mo a1loys it has been used an empirical many-body potential (MBP developed by Akgün and Uğur,recently. The parametcrs defıning the MBP f.c.c. alloys m ay be computed by following a procedure deseri bed. The radial

  12. Effect of Carbon and Phosphorous on the Solidification Microstructure in a Cr-Ni-Mn-N Austenitic Hydrogen-resistant Steel

    Institute of Scientific and Technical Information of China (English)

    Jun TAN; Luming MA; Shouxin LI; Lijian RONG; Jincai YUAN; Yiyi LI

    2001-01-01

    The influence of carbon and phosphorus on the solidification microstructure of a Cr-Ni-Mn-N austenitic steel was studied. The button specimens were prepared by vacuum induction melting and magnetic convection. The experimental results show that the increase of C or P concentration in the steel can change the solidification modes of Cr-Ni-Mn-N austenitic steels and has a significant effect on the morphology of the dendrites. The content of δ-ferrite in the microstructure reduces with increasing the concentration of C or P in the steel, there is a gradient of the content of δ-ferrite formed from surface through the center of the specimens.

  13. Determination of optimum welding parameters in connecting high alloyed X53CrMnNiN219 and X45CrSi93 steels by friction welding

    Indian Academy of Sciences (India)

    Mehmet Uzkut; Bekir Sadik Ünlü; Mustafa Akdağ

    2011-07-01

    In this study, different welding parameters were applied to two different steels with high alloys and mechanical and metallographical investigations are performed. Thus, the optimum welding parameters were determined for these materials and working conditions. 12.30 diameter steel bars made up of 1.4871 (X53CrMnNiN219) and 1.4718 (X45CrSi93) steel were used as experimental material. The material loss increased with increase in friction and rotating pressure. No fracture at the welding region was observed and the highest fracture energy was identified in B5 group. Based on micro hardness investigation; the hardness profile reached its minimum value at the welding region.

  14. PTFE/30CrMnSiNi2A的重载摩擦性能%Friction Properties of PTFE/30CrMnSiNi2A Bearing at Heavy Load

    Institute of Scientific and Technical Information of China (English)

    丁水; 张绪虎; 吴阳; 叶呈武; 黄思原

    2012-01-01

    The self-lubricating bearings which were made up of PTFE and a ultrahigh strength steel 30CrMnSiNi2A were investigated by numerical simulation and experiments. The failure mode and influence of friction surface on the friction properties were analyzed. The wear mechanism was also studied based on the observation of the worn friction surface. It was found that the failure of self-lubricating bearing is attributed to the damage of lubricating layer,which is improved by excellent friction surface. Owing to the transferred lubricating film made by PTFE fabric, the friction coefficient reduced eventually.%采用PTFE与30CrMnSiNi2A钢制成自润滑轴承,在重载工况下进行了数值模拟及试验分析,研究了自润滑轴承的主要失效形式、摩擦面状态及性能对摩擦性能的影响,并分析了轴承的磨损机理.结果表明:该轴承在重载下以润滑层失效为主要破坏形式,改善摩擦面能够有效提高轴承的摩擦性能;在摩擦过程中PTFE不断被挤出,形成转移润滑膜,起到了减小摩擦因数的作用.

  15. Synthesis and characterization of (smif)2M(n) (n = 0, M = V, Cr, Mn, Fe, Co, Ni, Ru; n = +1, M = Cr, Mn, Co, Rh, Ir; smif =1,3-di-(2-pyridyl)-2-azaallyl).

    Science.gov (United States)

    Frazier, Brenda A; Bartholomew, Erika R; Wolczanski, Peter T; DeBeer, Serena; Santiago-Berrios, Mitk'El; Abruña, Hector D; Lobkovsky, Emil B; Bart, Suzanne C; Mossin, Susanne; Meyer, Karsten; Cundari, Thomas R

    2011-12-19

    A series of Werner complexes featuring the tridentate ligand smif, that is, 1,3-di-(2-pyridyl)-2-azaallyl, have been prepared. Syntheses of (smif)(2)M (1-M; M = Cr, Fe) were accomplished via treatment of M(NSiMe(3))(2)(THF)(n) (M = Cr, n = 2; Fe, n = 1) with 2 equiv of (smif)H (1,3-di-(2-pyridyl)-2-azapropene); ortho-methylated ((o)Mesmif)(2)Fe (2-Fe) and ((o)Me(2)smif)(2)Fe (3-Fe) were similarly prepared. Metatheses of MX(2) variants with 2 equiv of Li(smif) or Na(smif) generated 1-M (M = Cr, Mn, Fe, Co, Ni, Zn, Ru). Metathesis of VCl(3)(THF)(3) with 2 Li(smif) with a reducing equiv of Na/Hg present afforded 1-V, while 2 Na(smif) and IrCl(3)(THF)(3) in the presence of NaBPh(4) gave [(smif)(2)Ir]BPh(4) (1(+)-Ir). Electrochemical experiments led to the oxidation of 1-M (M = Cr, Mn, Co) by AgOTf to produce [(smif)(2)M]OTf (1(+)-M), and treatment of Rh(2)(O(2)CCF(3))(4) with 4 equiv Na(smif) and 2 AgOTf gave 1(+)-Rh. Characterizations by NMR, EPR, and UV-vis spectroscopies, SQUID magnetometry, X-ray crystallography, and DFT calculations are presented. Intraligand (IL) transitions derived from promotion of electrons from the unique CNC(nb) (nonbonding) orbitals of the smif backbone to ligand π*-type orbitals are intense (ε ≈ 10,000-60,000 M(-1)cm(-1)), dominate the UV-visible spectra, and give crystals a metallic-looking appearance. High energy K-edge spectroscopy was used to show that the smif in 1-Cr is redox noninnocent, and its electron configuration is best described as (smif(-))(smif(2-))Cr(III); an unusual S = 1 EPR spectrum (X-band) was obtained for 1-Cr.

  16. Microstructures and mechanical properties of compositionally complex Co-free FeNiMnCr{sub 18} FCC solid solution alloy

    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); Bei, H., E-mail: beih@ornl.gov [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2015-07-29

    Recently, a structurally-simple but compositionally-complex FeNiCoMnCr high entropy alloy was found to have excellent mechanical properties (e.g., high strength and ductility). To understand the potential of using high entropy alloys as structural materials for advanced nuclear reactor and power plants, it is necessary to have a thorough understanding of their structural stability and mechanical properties degradation under neutron irradiation. This requires us to develop a similar model alloy without Co because material with Co will make post-neutron-irradiation testing difficult due to the production of the {sup 60}Co radioisotope. To achieve this goal, a FCC-structured single-phase alloy with a composition of FeNiMnCr{sub 18} was successfully developed. This near-equiatomic FeNiMnCr{sub 18} alloy has good malleability and its microstructure can be controlled by thermomechanical processing. By rolling and annealing, the as-cast elongated-grained-microstructure is replaced by homogeneous equiaxed grains. The mechanical properties (e.g., strength and ductility) of the FeNiMnCr{sub 18} alloy are comparable to those of the equiatomic FeNiCoMnCr high entropy alloy. Both strength and ductility increase with decreasing deformation temperature, with the largest difference occurring between 293 and 77 K. Extensive twin-bands which are bundles of numerous individual twins are observed when it is tensile-fractured at 77 K. No twin bands are detected by EBSD for materials deformed at 293 K and higher. The unusual temperature-dependencies of UTS and uniform elongation could be caused by the development of the dense twin substructure, twin-dislocation interactions and the interactions between primary and secondary twinning systems which result in a microstructure refinement and hence cause enhanced strain hardening and postponed necking.

  17. Thermodynamic Stability of Transition-Metal-Substituted LiMn2-x Mx O4 (M=Cr, Fe, Co, and Ni) Spinels.

    Science.gov (United States)

    Lai, Chenying; Chen, Jiewei; Knight, James C; Manthiram, Arumugam; Navrotsky, Alexandra

    2016-07-01

    The formation enthalpies from binary oxides of LiMn2 O4 , LiMn2-x Crx O4 (x=0.25, 0.5, 0.75 and 1), LiMn2-x Fex O4 (x=0.25 and 0.5), LiMn2-x Cox O4 (x=0.25, 0.5, and 0.75) and LiMn1.75 Ni0.25 O4 at 25 °C were measured by high temperature oxide melt solution calorimetry and were found to be strongly exothermic. Increasing the Cr, Co, and Ni content leads to more thermodynamically stable spinels, but increasing the Fe content does not significantly affect the stability. The formation enthalpies from oxides of the fully substituted spinels, LiMnMO4 (M=Cr, Fe and Co), become more exothermic (implying increasing stability) with decreasing ionic radius of the metal and lattice parameters of the spinel. The trend in enthalpy versus metal content is roughly linear, suggesting a close-to-zero heat of mixing in LiMn2 O4 -LiMnMO4 solid solutions. These data confirm that transition-metal doping is beneficial for stabilizing these potential cathode materials for lithium-ion batteries.

  18. Role of Si in Improving the Shape Recovery of FeMnSiCrNi Shape Memory Alloys

    Science.gov (United States)

    Maji, Bikas C.; Krishnan, Madangopal; Gouthama; Ray, R. K.

    2011-08-01

    The effect of Si addition on the microstructure and shape recovery of FeMnSiCrNi shape memory alloys has been studied. The microstructural observations revealed that in these alloys the microstructure remains single-phase austenite ( γ) up to 6 pct Si and, beyond that, becomes two-phase γ + δ ferrite. The Fe5Ni3Si2 type intermetallic phase starts appearing in the microstructure after 7 pct Si and makes these alloys brittle. Silicon addition does not affect the transformation temperature and mechanical properties of the γ phase until 6 pct, though the amount of shape recovery is observed to increase monotonically. Alloys having more than 6 pct Si show poor recovery due to the formation of δ-ferrite. The shape memory effect (SME) in these alloys is essentially due to the γ to stress-induced ɛ martensite transformation, and the extent of recovery is proportional to the amount of stress-induced ɛ martensite. Alloys containing less than 4 pct and more than 6 pct Si exhibit poor recovery due to the formation of stress-induced α' martensite through γ- ɛ- α' transformation and the large volume fraction of δ-ferrite, respectively. Silicon addition decreases the stacking fault energy (SFE) and the shear modulus of these alloys and results in easy nucleation of stress-induced ɛ martensite; consequently, the amount of shape recovery is enhanced. The amount of athermal ɛ martensite formed during cooling is also observed to decrease with the increase in Si.

  19. Solid/liquid interaction between a multicomponent FeCrNiCoMnAl high entropy alloy and molten aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Hung-Hua [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 701, Taiwan (China); Tsai, Wen-Ta, E-mail: wttsai@mail.ncku.edu.tw [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 701, Taiwan (China); Kuo, Jui-Chao [Department of Materials Science and Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 701, Taiwan (China); Yang, Chih-Chao [Industrial Technology Research Institute, 31 Gongye 2nd Rd., Annan District, Tainan 709, Taiwan (China)

    2011-08-11

    Highlights: > The interfacial reaction between a high-entropy alloy and an Al melt was studied. The major findings obtained are as following. > The dissolution of Al into the HEA cause selective attack of the constituent phases. > A nanocrystalline layer and Al{sub 13}Cr{sub 2} precipitation were found at the interface. > The structure and chemical composition of the solidified Al were also modified. - Abstract: This study investigates the interfacial reaction between an as-cast multicomponent FeCrNiCoMnAl high-entropy alloy (HEA) and an Al melt at 700 deg. C. The microstructure, phase identification, and chemical composition were analyzed by using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), transmission electron microscopy (TEM) and electron back scattering diffraction (EBSD). The results showed that the contact between the solid substrate and the Al melt resulted in the formation of a region with complicated microstructure at the interface. The dissolution of the substrate alloying elements into the Al melt also caused chemical composition and phase changes in the solidified Al crust.

  20. Cu-Mn-Ni-Ag钎料高频感应钎焊2Cr13不锈钢接头的显微组织与性能%Microstructure andperformance of 2Cr13stainless steel joint by high frequency induction brazing usingCu-Mn-Ni-Agfiller alloy

    Institute of Scientific and Technical Information of China (English)

    郑义; 颜家振; 李宁; 曹永同; 帅帆

    2016-01-01

    The characteristic of Cu-Mn-Ni-Ag filler alloy and the microstructure and mechanical properties of the 2Cr13 stainless steel joint brazed by high frequency induction brazing using Cu-Mn-Ni-Ag filler alloywerestudied. The results show that the melting point of the Cu-Mn-Ni-Ag filler alloy is 880℃and it is composed of Ag-rich phase, Cu-Mn-Ni solid solution and a little Ni-Mn-Si compound; a layer of Fe-Mn-Ni-Cr-Cu solid solution forms at the interface between the filler alloy and base metal, and the brazing seam zone is composed of Ag-rich phase, Cu-Mn-Ni solid solution and a little Ni-Mn-Si compound. The brazing jointsfailsin the inside Cu-Mn-Ni solid solution and Ag-rich phase, and the fracture mode of the joints is mainly ductile dimple fracture, the best shear strength of the brazing joint at room temperature is 369 MPa, the high temperature shear strength of the brazing joints at 400℃, 500℃and 600℃are 251 MPa, 208 MPa and 84 MPa,respectively.%采用新型的Cu-Mn-Ni-Ag中温铜基钎料高频感应钎焊2Cr13不锈钢,并对钎料的工艺特性、钎焊接头的显微组织以及测试温度对钎焊接头力学性能的影响进行研究。结果表明:Cu-Mn-Ni-Ag钎料的熔点约为880℃,由富Ag相、Cu-Mn-Ni固溶体以及少量的Ni-Mn-Si化合物组成;钎料与2Cr13不锈钢产生良好的冶金结合,且钎焊接头组织致密;界面反应区的组织为Fe-Mn-Ni-Cr-Cu固溶体,钎缝区组织由富Ag相、Cu-Mn-Ni固溶体和少量的Ni-Mn-Si化合物组成;钎焊接头断裂于钎缝中间的富Ag相和CuMnNi固溶体上,为以剪切韧窝为主的韧性断裂,室温剪切强度最大可达369 MPa,在400℃、500℃和600℃下接头的剪切强度分别为251 MPa、208 MPa和84 MPa。

  1. Contamination assessment of heavy metals in the soils around Khouzestan Steel Company (KSC (Ni, Mn, Pb, Fe, Zn, Cr

    Directory of Open Access Journals (Sweden)

    Fatemeh hormozi Nejad

    2017-02-01

    Full Text Available Introduction Soil plays a vital role in human life as the very survival of mankind is tied to the preservation of soil productivity (Kabata- Pendies and Mukherjee, 2007. The purpose of this study is the assessment of heavy metal contamination (Zn, Mn, Pb, Fe, Ni, Cr of the soil around the Khuzestan Steel Complex. Materials and methods For this purpose, 13 surface soil samples (0-10 cm were taken. Also a control sample was taken from an area away from the steel complex. The coordinates of each point were recorded by Global Positioning System (GPS. The samples were transferred to the laboratory and then were air dried at room temperature for 72 hours. Then they were sieved through a 2mm sieve for determining physical and chemical parameters (soil texture, pH, OC, and a 63-micron sieve for measurement of heavy metal concentration. pH was measured using a calibrated pH meter at a 2: 1 mixture (soil: water, and soil texture was determined using a hydrometer. The amount of organic matter was measured using the Valkey black method (Chopin and Alloway, 2007. After preparation of the samples in the laboratory, the samples were analyzed using the ICP-OES method to assess concentration of heavy metals. Measurement of heavy metals concentration was carried out at the Zar azma laboratory in Tehran. To ensure the accuracy of the analysis of soil samples, replicate samples were also sent to the laboratory. In order to assess the heavy metal pollution in the soil samples, different indices including contamination factor (CF, contamination degree (Cd, anthropogenic enrichment percent (An%, and saturation degree of metals (SDM were calculated. Discussion In addition, the mean concentrations of heavy metals in soil samples were compared to the concentration of these metals in Control Sample and unpolluted soil standard. Measurement of soil pH showed that the soil has a tendency to alkalinity. Also, soil texture is sandy loam (Moyes, 2011. The results showed that

  2. New aspects of magnetocaloric effect in NiMn{sub 0.89}Cr{sub 0.11}Ge

    Energy Technology Data Exchange (ETDEWEB)

    Jaworska-Gołąb, T., E-mail: teresa.jaworska-golab@uj.edu.pl [Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-348 Kraków (Poland); Baran, S. [Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-348 Kraków (Poland); Duraj, R. [Institute of Physics, Cracow University of Technology, Podchorążych 1, 30-084 Kraków (Poland); Marzec, M. [Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-348 Kraków (Poland); Dyakonov, V. [Institute of Physics, Polish Academy of Sciences, al. Lotników 32/46, 02-668 Warszawa (Poland); A.A. Galkin Donetsk Physico-Technical Institute, 83-114 Donetsk (Ukraine); Sivachenko, A. [A.A. Galkin Donetsk Physico-Technical Institute, 83-114 Donetsk (Ukraine); Tyvanchuk, Yu. [Chemistry Department, Ivan Franko National University of Lviv, 79-005 Lviv (Ukraine); Szymczak, H. [Institute of Physics, Polish Academy of Sciences, al. Lotników 32/46, 02-668 Warszawa (Poland); Szytuła, A. [Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-348 Kraków (Poland)

    2015-07-01

    Investigations of structural and magnetic phase transitions in the NiMn{sub 0.89}Cr{sub 0.11}Ge half-Heusler alloy were carried out by DSC, XRD (80–400 K), magnetic susceptibility and magnetization (1.9–400 K, magnetic field up to 9.0 T, pressure up to 5.25 kbar) measurements. At high temperatures the sample is a single phase crystallizing in the hexagonal crystal structure (Ni{sub 2}In-type, space group P6{sub 3}/mmc) while below 260 K, down to 100 K, some amount of the hexagonal phase coexists with the orthorhombic (TiNiSi-type, space group Pnma) one. Strong magnetostructural coupling is observed. Magnetic data indicate that with increasing temperature magnetic properties of the sample change from antiferro- to ferro- and then to paramagnetic ones. The latter magnetic phase transition is associated with the crystal structure change and results in large magnetic entropy change equal to −51 J/kg K at μ{sub 0}H= 9.0 T near 260 K. Application of external pressure shifts T{sub C} towards lower temperatures. - Highlights: • # Pnma below 210 K, # P6{sub 3}/mmc above 260 K, for 210 K

  3. 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.

  4. Microstructure and fatigue crack growth behaviour of electron beam welding in 30CrMnSiNi2A steel

    Institute of Scientific and Technical Information of China (English)

    陈芙蓉; 霍立兴; 张玉凤; 张莉; 刘方军; 陈刚

    2003-01-01

    The effects of two post-weld heat treatment processes on the microstructure and fatigue properties of the electron beam welded joints of 30CrMnSiNi2A steel were studied. Electron beam local post-weld heat treatment (EBLPWHT), in a vacuum chamber, immediately after welding and a traditional furnace whole post-weld heat treatment (FWPWHT) were accepted. The experimental results show that, after EBLPWHT, the main microstructure of weld is changed from coarse acicular martensite into lath martensite, and base metal is changed from ferrite and perlite into upper bainite and residual austenite, however the microstructures of different zones of joints in FWPWHT conditions are tempered sorbite. The fatigue crack growth rate da/dN of welds and base metal are not obviously changed among EBLPWHT, FWPWHT test and as-welded (AW) test, as the mechanical properties of materials have a certain but not large effect on the da/dN of welded joints. The resistance to near threshold fatigue crack growth data of welded joints can be largely improved by EBLPWHT and it is related to microstructure and crack closure effect.

  5. High-field magnetization of heusler alloys Fe2 XY ( X = Ti, V, Cr, Mn, Fe, Co, Ni; Y = Al, Si)

    Science.gov (United States)

    Kourov, N. I.; Marchenkov, V. V.; Korolev, A. V.; Belozerova, K. A.; Weber, H. W.

    2015-10-01

    The magnetization curves of ferromagnetic Heusler alloys Fe2 XY (where X = Ti, V, Cr, Mn, Fe, Co, Ni are transition 3 d elements and Y = Al, Si are the s and p elements of the third period of the Periodic Table) have been measured at T = 4.2 K in the field range H ≤ 70 kOe. It has been shown that the high-field ( H ≥ 20 kOe) magnetization is described within the Stoner model.

  6. Influence of strain aging on shape memory effect of Fe-Mn-Si-Cr-Ni-C alloys with different Cr content%形变时效对不同Cr含量Fe-Mn-Si-Cr-Ni-C合金记忆效应的影响

    Institute of Scientific and Technical Information of China (English)

    叶邦斌; 彭华备; 熊隆荣; 文玉华; 李宁

    2009-01-01

    研究了时效工艺对不同Cr含量Fe-Mn-Si-Cr-Ni-C合金形状记忆效应的影响,通过SEM分析了其微观组织变化.结果表明:Cr含量为12wt%的Fe-Mn-Si-Cr-Ni-C合金具有与Cr含量为8wt%的合金相当的形状记忆效应.直接时效时只有少量Cr23C6析出相在晶界和晶内析出.形变后时效不仅使得析出的Cr23C6数量更多,粒径更小,而且Cr23C6的析出具有方向性.形变时效后合金的形状回复率显著高于直接时效合金的形状回复率.

  7. Extratores para Cd, Cu, Cr, Mn, Ni, Pb e Zn em LATOSSOLOS tratados com biossólido e cultivados com milho Extractants for Cd, Cu, Cr, Mn, Ni, Pb and Zn in biossolid-amanded Oxisols cultivated with corn

    Directory of Open Access Journals (Sweden)

    Ana Rosa Martins dos Anjos

    2001-06-01

    in agriculture needs more information on plant availability of heavy metals added to soil by this waste. The efficiency of the chemical extractants HCl 0.1 mol L-1, DTPA-TEA pH 7.3, Mehlich 3 and aqua regia for the evaluation of Cd, Cu, Cr, Mn, Ni, Pb and Zn availability in biosolid-amended soils, was studied in a pot (0.5 m³ experiment using corn as test plant. The soils used were a dystrophic Typic Hapludox (LAd and a dystrophic Rhodic Hapludox (LVd. The statistic design consisted of: random blocks in a 4x4 factorial outline, 4 treatments (LVd+sludge, LVd, LAd+sludge, LAd, 4 extraction methods (HCl 0.1 mol L-1, Mehlich 3, DTPA-TEA 0.005 mol L-1 pH 7,3 and aqua regia and 4 replications. Seventy-eight Mg ha-1 of biosolids on dry base were applied every two months to the soils, one year before planting corn. In five applications 388 Mg ha-1 of biosolids were applied. The metal contents of the various parts of the plants were correlated with the contents removed by the extraction methods. The results show that the total contents of Cr, Cu, Mn, Ni, and Zn did not exceed the critical limits established by USEPA and the European Community regulations even at the biosolid application rate of 388 Mg ha-1. Mehlich 3 was an effective extractor only in the evaluation of the bioavailability of Cu and Zn in corn grown on soils treated with biosolids. Cd, Cr, Ni and Pb presented no availability to corn plants.

  8. Phytoremediation of Cd, Cr, Cu, Mn, Fe, Ni, Pb and Zn from aqueous solution using Phragmites cummunis, Typha angustifolia and Cyperus esculentus.

    Science.gov (United States)

    Chandra, Ram; Yadav, Sangeeta

    2011-07-01

    A comparative bioaccumulation pattern and ultra structural changes were studied in Phragmites cummunis, Typha angustifolia and Cyperus esculentus in mixed metals solution of cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb) and zinc (Zn). P. cummunis was observed to be a shoot accumulator for Cr, Fe, Mn, Ni, Pb, and Zn. However, T. angustifolia was found to be a root accumulator for Cd, Cr, Cu, Fe, Ni and Pb. In addition, C. esculentus also accumulated most of the tested heavy metals in the roots, while Mn and Fe were translocated up to leaves. Further, the long term metal treatment showed maximum accumulation of all heavy metals in P. cummunis followed by T. angustifolia and C. esculentus. Among heavy metals, Fe was accumulated maximum, i.e., >1000 microg g(-1) by all three plants. Simultaneously, the adverse effects on biochemical parameters were noted earlier in C. esculentus than T. angustifolia and P. cummunis. Ultra structural observation showed the cellular changes in wetland plants after longer exposure. Results revealed that P. cummunis and T. angustifolia had more potential for tested metals than C. esculentus. This study established that these wetland plants could be used for heavy metals phytoremediation from metal containing industrial wastewater.

  9. 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.

  10. A novel training-free cast Fe-Mn-Si-Cr-Ni shape memory alloy based on formation of martensite in a domain-specific manner

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Yuhua; Peng, Huabei; Wang, Chaoping; Yu, Qinxu; Li, Ning [College of Manufacturing Science and Engineering, Sichuan University, Chengdu (China)

    2011-02-15

    The proposed key to producing a good shape memory effect in Fe-Mn-Si alloys is to reduce or even prevent the collisions between martensite bands. A method for realizing this is to make stress-induced martensite bands form in a domain-specific manner. We developed a novel training-free cast Fe-18Mn-5.5Si-9.5Cr-4Ni alloy with residual lathy delta ferrite based on this idea. The recovery strain reached 6.4% only after annealing the cast Fe-18Mn-5.5Si-9.5Cr-4Ni alloy. Microstructure observations indicated that the lathy delta ferrite made the stress-induced martensite form in a domain-specific manner by first subdividing grains into smaller domains. We hypothesize that through adjusting alloy compositions, solidification parameters, and heat treatment technique, the shape recovery of cast Fe-Mn-Si alloys can be further improved. Such a finding will provide a novel method for developing training-free Fe-Mn-Si shape memory alloys. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Transient Liquid Phase Bonding of Cu-Cr-Zr-Ti Alloy Using Ni and Mn Coatings: Microstructural Evolution and Mechanical Properties

    Science.gov (United States)

    Venkateswaran, T.; Ravi, K. R.; Sivakumar, D.; Pant, Bhanu; Janaki Ram, G. D.

    2017-08-01

    High-strength copper alloys are used extensively in the regenerative cooling parts of aerospace structures. Transient liquid phase (TLP) bonding of a Cu-Cr-Zr-Ti alloy was attempted in the present study using thin layers of elemental Ni and Mn coatings applied by electroplating. One of the base metals was given a Ni coating of 4 µm followed by a Mn coating of 15 µm, while the other base metal was given only the Ni coating (4 µm). The bonding cycle consisted of the following: TLP stage—heating to 1030 °C and holding for 15 min; homogenization stage—furnace cooling to 880 °C and holding for 2 h followed by argon quenching to room temperature. Detailed microscopy and electron probe microanalysis analysis of the brazed joints were carried out. The braze metal was found to undergo isothermal solidification within the 15 min of holding time at 1030 °C. At the end of TLP stage, the braze metal showed a composition of Cu-17Ni-9Mn (wt.%) at the center of the joint with a steep gradient in Ni and Mn concentrations from the center of the braze metal to the base metal interfaces. After holding for 2 h at 880 °C (homogenization stage), the compositional gradients were found to flatten significantly and the braze metal was found to develop a homogeneous composition of Cu-11Ni-7Mn (wt.%) at the center of the joint. In lap-shear tests, failures were always found to occur in the base metal away from the brazed region. The copper alloy base metal was found to undergo significant grain coarsening due to high-temperature exposure during brazing and, consequently, suffer considerable reduction in yield strength.

  12. Survey of trace elements (Al, As, Cd, Cr, Co, Hg, Mn, Ni, Pb, Se, and Si) in retail samples of flavoured and bottled waters.

    Science.gov (United States)

    Barroso, M F; Ramos, S; Oliva-Teles, M T; Delerue-Matos, C; Sales, M G F; Oliveira, M B P P

    2009-01-01

    Concentrations of eleven trace elements (Al, As, Cd, Cr, Co, Hg, Mn, Ni, Pb, Se, and Si) were measured in 39 (natural and flavoured) water samples. Determinations were performed using graphite furnace electrothermetry for almost all elements (Al, As, Cd, Cr, Co, Mn, Ni, Pb, and Si). For Se determination hydride generation was used, and cold vapour generation for Hg. These techniques were coupled to atomic absorption spectrophotometry. The trace element content of still or sparkling natural waters changed from brand to brand. Significant differences between natural still and natural sparkling waters (p differences between flavoured and natural waters. The concentration of each element was compared with the presence of flavours, preservatives, acidifying agents, fruit juice and/or sweeteners, according to the labelled composition. It was shown that flavoured waters generally increase the trace element content. The addition of preservatives and acidifying regulators had a significant influence on Mn, Co, As and Si contents (p difference in Mn, Co, Se and Si content.

  13. Effects of Mn and Cu on the Mechanical Properties of a High Strength Low Alloy NiCrMoV Steel

    Institute of Scientific and Technical Information of China (English)

    A.Abdollah-zadeh; M. Belbasy

    2005-01-01

    The present study focuses on the effects of Mn and Cu on the mechanical properties, in particular, strength and toughness of a low alloy steel containing Ni, Cr, Mo and V. Specimens with different amounts of Mn (0.23%~0.85%)and Cu (0.15%~0.45%) were cast and forged, and then austenitized at 870℃ for 1 h, followed by oil quenching. All specimens were tempered at 650℃ for 1 h. The results show that as the amounts of Mn and Cu increase respectively from 0.35% to 0.85% and from 0.15% to 0.45%, the yield and tensile strength increase. The highest impact energies were observed in the specimen with 0.35% Mn and in the specimen with 0.25% Cu. The impact energy decreases with increasing the Mn and Cu from 0.35% to 0.85% and from 0.25% to 0.45%, respectively. Furthermore, the variation of Mn and Cu does not cause a considerable change in the tempered martensite microstructure. The optimum strength and toughness is observed in 0.35% Mn containing steel and in the 0.25% Cu containing steel.

  14. Changing Rule of Carbon-Enriched Zone and Diffusion Behavior of Carbon in Aging 0Cr6Mn13Ni10MoTi/1Cr5Mo Dissimilar Welded Joints

    Institute of Scientific and Technical Information of China (English)

    Zheng LIU; Ligang WANG; Lai WANG

    2004-01-01

    The microstructures, the changing rule of carbon-enriched zone, the diffusion behaviors of elements C and Cr, and the carbide type of 0Cr6Mn13Ni10MoTi/1Cr5Mo dissimilar welded joints after aging at 500℃ for various times and after long-term service in technical practice were investigated by using the optical microscopy, electron probe microanalysis, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results show that in aging 0Cr6Mn13Ni10MoTi/1Cr5Mo dissimilar welded joints, the main carbides are M3C and a few carbides are M7C3 and M23C6. The M3C carbide decomposition and dissolution with increasing aging time or aging temperature and the anti-diffusion of C and Cr cause the decrease and disappearance of the carbon-enriched zone. The results are different from those of the A302/1Cr5Mo dissimilar welded joints in previous studies.

  15. Microstructures of Al7.5Cr22.5Fe35Mn20Ni15 High-Entropy Alloy and Its Polarization Behaviors in Sulfuric Acid, Nitric Acid and Hydrochloric Acid Solutions

    Directory of Open Access Journals (Sweden)

    Chun-Huei Tsau

    2016-08-01

    Full Text Available This paper investigates the microstructures and the polarization behaviors of Al7.5Cr22.5Fe35Mn20Ni15 high-entropy alloy in 1M (1 mol/L deaerated sulfuric acid (H2SO4, nitric acid (HNO3, and hydrochloric acid (HCl solutions at temperatures of 30–60 °C. The three phases of the Al7.5Cr22.5Fe35Mn20Ni15 high-entropy alloy are body-centered cubic (BCC dendrites, face-centered cubic (FCC interdendrites, and ordered BCC precipitates uniformly dispersed in the BCC dendrites. The different phases were corroded in different acidic solutions. The passivation regions of the Al7.5Cr22.5Fe35Mn20Ni15 alloy are divided into three and two sub-regions in the solutions of H2SO4 and HNO3 at 30–60 °C, respectively. The passivation region of the Al7.5Cr22.5Fe35Mn20Ni15 alloy is also divided into two sub-domains in 1M deaerated HCl solution at 30 °C. The Al7.5Cr22.5Fe35Mn20Ni15 alloy has almost equal corrosion resistance in comparison with 304 stainless steel (304SS in both the 1M H2SO4 and 1M HCl solutions. The polarization behaviors indicated that the Al7.5Cr22.5Fe35Mn20Ni15 alloy possessed much better corrosion resistance than 304SS in 1M HNO3 solution. However, in 1M NaCl solution, the corrosion resistance of the Al7.5Cr22.5Fe35Mn20Ni15 alloy was less than 304SS.

  16. AlM2B2 (M  =  Cr, Mn, Fe, Co, Ni): a group of nanolaminated materials

    Science.gov (United States)

    Kádas, K.; Iuşan, D.; Hellsvik, J.; Cedervall, J.; Berastegui, P.; Sahlberg, M.; Jansson, U.; Eriksson, O.

    2017-04-01

    Combining theory with experiments, we study the phase stability, elastic properties, electronic structure and hardness of layered ternary borides AlCr2B2, AlMn2B2, AlFe2B2, AlCo2B2, and AlNi2B2. We find that the first three borides of this series are stable phases, while AlCo2B2 and AlNi2B2 are metastable. We show that the elasticity increases in the boride series, and predict that AlCr2B2, AlMn2B2, and AlFe2B2 are more brittle, while AlCo2B2 and AlNi2B2 are more ductile. We propose that the elasticity of AlFe2B2 can be improved by alloying it with cobalt or nickel, or a combination of them. We present evidence that these ternary borides represent nanolaminated systems. Based on SEM measurements, we demonstrate that they exhibit the delamination phenomena, which leads to a reduced hardness compared to transition metal mono- and diborides. We discuss the background of delamination by analyzing chemical bonding and theoretical work of separation in these borides.

  17. Drinking water interlaboratory ring test. Part IV. Results of some cationic analytes. Al, Zn, Cd, Cr, Pb, Ni, Mn, Fe, Cu and V; Circuito interlaboratorio Unichim sulle acque potabili. Parte IV. Risultati di alcuni cationi metallici. Al, Zn, Cd, Co, Cr, Pb, Ni, Mn, Fe, Cu e V

    Energy Technology Data Exchange (ETDEWEB)

    Cavaterra, E.; Divo, C.; Bottazzini, N. [Unichim, Milan (Italy); Alava, F. [Bergamo Ambiente e Servizi, Bergamo (Italy); Bettinelli, M. [Electric Power Production Company, Piacenza (Italy); Bonfiglioli, F. [Azienda Mediterranea Gas e Acqua SpA, Genoa (Italy)

    2002-01-01

    In this paper results of statistical treatment of experimental data obtained in some cycles of an interlaboratory ring test of content of Al, Zn, Cd, Co, Cr, Pb, Ni, Mn, Fe, Cu and V in drinking water are reported. Means, variances and parameters of precision and accuracy of some analytical techniques and methods employed by laboratories participating to the ring test will be reported and discussed. [Italian] Nel presente lavoro vengono riportati i risultati dell'elaborazione statistica dei dati sperimentali ottenuti in alcuni cicli del circuito interlaboratorio e relativi ai seguenti cationi metallici: Al, Zn, Cd, Co, Cr, Pb, Ni, Mn, Fe, Cu e V. Vengono riportati e discussi i valori medi e la varianza ed infine i dati di accuratezza e precisione delle tecniche o metodi d'analisi impiegati dai laboratori partecipanti al circuito.

  18. A Novel Training-Free Processed Fe-Mn-Si-Cr-Ni Shape Memory Alloy Undergoing δ → γ Phase Transformation

    Science.gov (United States)

    Peng, Huabei; Wang, Gaixia; Du, Yangyang; Wang, Shanling; Chen, Jie; Wen, Yuhua

    2016-07-01

    We not only suppress the formation of twin boundaries but also introduce a high density of stacking faults by taking advantage of δ → γ phase transformation in a processed Fe-19.38Mn-5.29Si-8.98Cr-4.83Ni shape memory alloy. As a result, its shape memory effect is remarkably improved after heating at 1533 K (1260 °C) (single-phase region of δ ferrite) and air cooling due to δ → γ phase transformation.

  19. Ferromagnetism on a paramagnetic host background: the case of rutile TM:TiO{sub 2} single crystals (TM = Cr, Mn, Fe, Co, Ni, Cu)

    Energy Technology Data Exchange (ETDEWEB)

    Sangaletti, L [Dipartimento di Matematica e Fisica, Universita Cattolica, Via dei Musei 41, 25121 Brescia (Italy); Mozzati, M C [CNISM and Dipartimento di Fisica ' A Volta' , Universita di Pavia, Via Bassi 6, 27100 Pavia (Italy); Galinetto, P [CNISM and Dipartimento di Fisica ' A Volta' , Universita di Pavia, Via Bassi 6, 27100 Pavia (Italy); Azzoni, C B [CNISM and Dipartimento di Fisica ' A Volta' , Universita di Pavia, Via Bassi 6, 27100 Pavia (Italy); Speghini, A [Dipartimento Scientifico e Tecnologico, Universita di Verona, Strada Le Grazie 15, 37134 Verona (Italy); Bettinelli, M [Dipartimento Scientifico e Tecnologico, Universita di Verona, Strada Le Grazie 15, 37134 Verona (Italy); Calestani, G [Dipartimento di Chimica Generale ed Inorganica, Chimica Analitica, Chimica Fisica, Universita di Parma, Parco Area delle Scienze 17/A, 43100 Parma (Italy)

    2006-08-16

    Single crystals of TiO{sub 2} rutile doped with Cr, Mn, Fe, Co, Ni, and Cu were grown with the flux method in a Na{sub 2}B{sub 4}O{sub 7} melt. The samples, checked in their structural and phase homogeneity by x-ray diffraction and micro-Raman spectroscopy, were single-phase needle-shaped crystals several millimetres long. Paramagnetic and ferromagnetic behaviours at room temperature were observed and they are discussed also in connection with the magnetic properties of undoped TiO{sub 2} crystals.

  20. Coupling between magnetic and optical properties of GaN:TM (TM: V, Cr, Mn, Fe, Co, Ni): First-principle study with LDA-SIC approximation

    Science.gov (United States)

    Salmani, El mehdi; Mounkachi, Omar; Ez-Zahraouy, Hamid; Benyoussef, Abdelilah; Hamedoun, Mohammed; Hlil, El kebir

    2013-11-01

    Electronic structure, magnetic and optical properties of GaN:TM (TM: V, Cr, Mn, Fe, Co, Ni), based dilute magnetic semiconductors (DMS), are investigated using first-principles calculations. The energy difference between the ferromagnetic and disorder local moment states has been evaluated. Moreover, the optical absorption spectra obtained by ab-initio calculations confirm the ferromagnetic stability based on the charge state of magnetic impurities. Our results show that the ferromagnetic state is stable when TM introduce simultaneously magnetic moment and intrinsic carriers in (Ga, TM)N. Some studied ferromagnetic DMS exhibit half-metallic behavior, which is suitable for spintronics applications.

  1. Strong pressure dependences of the magnetization and Curie temperature for CrTe and MnAs with NiAs-type structure

    CERN Document Server

    Yamada, H; Kondo, K; Goto, T

    2002-01-01

    To study the strong magneto-volume effects observed in CrTe and MnAs with NiAs-type crystal structure, first-principle band calculations are carried out by a self-consistent linear muffin-tin orbital method within the atomic sphere approximation. The equilibrium volume of the unit cell is obtained as a function of the magnetization M, which gives the volume magnetostriction. The dependence on M of the bulk modulus is also estimated. The coefficients a sub 0 and b sub 0 in the Landau expansion, DELTA E(M) = a sub 0 M sup 2 /2 + b sub 0 M sup 4 /4, are estimated by the fixed-spin-moment method. The calculated results for CrTe and MnAs are compared with those for bcc Fe. It is shown that the values of vertical bar a sub 0 vertical bar and b sub 0 for CrTe and MnAs are so small that the correction term from the magneto-volume coupling constants becomes significant. This fact gives a strong pressure dependence of the spontaneous magnetization. The pressure dependence of the Curie temperature is also discussed by m...

  2. 07MnNiCrMoVDR钢在硫化氢溶液中的腐蚀疲劳裂纹扩展速率数学模型%Crack Growth Rate of 07MnNiCrMoVDR Steel in H2S Solution

    Institute of Scientific and Technical Information of China (English)

    纪冬梅; 周昌玉; 胡毓仁

    2005-01-01

    The corrosion fatigue characteristics of 07MnNiCrMoVDR steel in H2S are studied in this paper. Experiments on corrosion fatigue crack growth rate are carried out. On the basis of the experimental data, the crack growth rates under the different environments are predicted with the neural network. The network is trained with the three main influence factors, that is, the solution concentration, the loading frequency and the stress ratio as the input nodes, and the crack growth rate coefficient C as the output node. On the basis of the datum predicted by the trained network, the relationship between the crack growth rate and these three influence factors is obtained.Then the mathematical model of the crack growth rate of 07MnNiCrMoVDR steel in H2S solution is obtained by regression.%本文通过试验研究07MnNiCrMoVDR钢在硫化氢水溶液中的腐蚀疲劳裂纹扩展特性,根据试验数据,利用神经网络,以介质浓度、载荷频率、应力比作为输入节点,裂纹扩展速率系数C作为输出节点,训练该网络预测不同条件下的裂纹扩展速率.根据由神经网络所预测的数据找出这三个影响因素在裂纹扩展速率系数C中的关系表达式,从而回归出07MnNiCrMoVDR钢在硫化氢水溶液中的腐蚀疲劳裂纹扩展速率数学模型.

  3. The partitioning of transitional metals (Fe, Mn, Ni, Cr) in mangrove sediments downstream of a ferralitised ultramafic watershed (New Caledonia)

    OpenAIRE

    Marchand, Cyril; Fernandez, J. M.; Moreton, B; Landi, L.; Lallier-Vergès, Elisabeth; Baltzer, F

    2012-01-01

    International audience; In New Caledonia, one third of the Island is composed of ultramafic rocks, and lateritic soils enriched in Fe, Ni and Cr. Open-cast mining occurs all around the Island, and processes of erosion and sedimentation, which occur naturally along the coastline, are strongly amplified by mining activities. Due to their position, at the interface between land and sea, mangroves receive extensive amounts of particles emanating from rivers through estuaries. The purpose of this ...

  4. The magnetic Curie temperature and exchange coupling between cations in tetragonal spinel oxide Mn{sub 2.5}M{sub 0.5}O{sub 4} (M = Co, Ni, Mn, Cr, and Mg) films

    Energy Technology Data Exchange (ETDEWEB)

    Kuo, K.; Cheng, C. W.; Chern, G. [Physics Department and SPIN Research Center, National Chung Cheng University, Chia-Yi, Taiwan, 621 (China)

    2012-04-01

    Mn{sub 3}O{sub 4} is a Jahn-Taller tetragonal ferrite that has a relatively low Curie temperature (T{sub c}) of {approx}43 K due to weak coupling between the canting spins. In this study, we fabricated a series of 100-nm-thick Mn{sub 2.5}M{sub 0.5}O{sub 4} (M = Co, Ni, Mn, Cr, and Mg) films via oxygen-plasma-assisted molecular beam epitaxy and measured the structural and magnetic properties of these films. These films show single phase quality, and the c-axis lattice parameter of pure Mn{sub 3}O{sub 4} is 0.944 nm, with a c/a ratio {approx}1.16, consistent with the bulk values. The replacement of Mn by M (M = Co, Ni, Cr, and Mg) changes the lattice parameters, and the c/a ratio varies between 1.16 and 1.06 depending upon the cation distribution of the films. The magnetic Curie temperatures of these films also vary in the range of 25-66 K in that Ni and Co enhance the T{sub c} whereas Mg reduces the T{sub c} (Cr shows no effect on the T{sub c}). These changes to the T{sub c} are related to both the element electronic state and the cation distributions in these compounds. As a non-collinear spin configuration can induce electrical polarization, the present study provides a systematic way to enhance the magnetic transition temperature in tetragonal spinel ferrites.

  5. Core-shell Prussian blue analogue molecular magnet Mn(1.5)[Cr(CN)6]·mH2O@Ni(1.5)[Cr(CN)6]·nH2O for hydrogen storage.

    Science.gov (United States)

    Bhatt, Pramod; Banerjee, Seemita; Anwar, Sharmistha; Mukadam, Mayuresh D; Meena, Sher Singh; Yusuf, Seikh M

    2014-10-22

    Core-shell Prussian blue analogue molecular magnet Mn1.5[Cr(CN)6]·mH2O@Ni1.5[Cr(CN)6]·nH2O has been synthesized using a core of Mn1.5[Cr(CN)6]·7.5H2O, surrounded by a shell of Ni1.5[Cr(CN)6]·7.5H2O compound. A transmission electron microscopy (TEM) study confirms the core-shell nature of the nanoparticles with an average size of ∼25 nm. The core-shell nanoparticles are investigated by using x-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS) and elemental mapping, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and infrared (IR) spectroscopy. The Rietveld refinement of the XRD pattern reveals that the core-shell compound has a face-centered cubic crystal structure with space group Fm3m. The observation of characteristic absorption bands in the range of 2000-2300 cm(-1) in IR spectra corresponds to the CN stretching frequency of Mn(II)/Ni(II)-N≡C-Cr(III) sequence, confirming the formation of Prussian blue analogues. Hydrogen absorption isotherm measurements have been used to investigate the kinetics of molecular hydrogen adsorption into core-shell compounds of the Prussian blue analogue at low temperature conditions. Interestingly, the core-shell compound shows an enhancement in the hydrogen capacity (2.0 wt % at 123 K) as compared to bare-core and bare-shell compounds. The hydrogen adsorption capacity has been correlated with the specific surface area and TGA analysis of the core-shell compound. To the best of our knowledge, this is the first report on the hydrogen storage properties of core-shell Prussian blue analogue molecular magnet that could be useful for hydrogen storage applications.

  6. Structural stability, mechanical properties, electronic structures and thermal properties of XS (X = Ti, V, Cr, Mn, Fe, Co, Ni) binary compounds

    Science.gov (United States)

    Liu, Yangzhen; Xing, Jiandong; Fu, Hanguang; Li, Yefei; Sun, Liang; Lv, Zheng

    2017-08-01

    The properties of sulfides are important in the design of new iron-steel materials. In this study, first-principles calculations were used to estimate the structural stability, mechanical properties, electronic structures and thermal properties of XS (X = Ti, V, Cr, Mn, Fe, Co, Ni) binary compounds. The results reveal that these XS binary compounds are thermodynamically stable, because their formation enthalpy is negative. The elastic constants, Cij, and moduli (B, G, E) were investigated using stress-strain and Voigt-Reuss-Hill approximation, respectively. The sulfide anisotropy was discussed from an anisotropic index and three-dimensional surface contours. The electronic structures reveal that the bonding characteristics of the XS compounds are a mixture of metallic and covalent bonds. Using a quasi-harmonic Debye approximation, the heat capacity at constant pressure and constant volume was estimated. NiS possesses the largest CP and CV of the sulfides.

  7. Concentration of heavy metal As, Pb, Mn, Ni, Sn, Zn, Cr, Fe and radon gas in bottom sediment from abandoned tin mines in the Phuket Province

    Directory of Open Access Journals (Sweden)

    Suteerasak, T.

    2006-05-01

    Full Text Available This research is aimed at analyzing the heavy metals: As, Pb, Mn, Ni, Sn, Zn, Cr, Fe, and radon gas emission in bottom sediment from six abandoned tin mines in Phuket Province. Fe, Mn, and Sn were found in higher concentrations (but non-polluting than Cr and Ni. As, Pb, and Zn were polluting at lower levels. The concentration ranges for As, Pb, and Zn were 75.3-169, 98.6-547.5, and 120.4-323.3 mg/kg respectively. The activity of radon gas emission from bottom sediment from an abandoned tin mine in Amphur Muang was in the range of 162-212 Bq/kg., in the Amphur Katoo mine the range was 122-266 Bq/kg. and in the Amphur Talang mine the range was 180-263 Bq/kg. All these sites have higher concentrations of radon gas emissions than other similar sites. The heavy metals and radon gas come from geochemical materials such as soil and granite rock, found around the abandoned tin mines.

  8. 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.

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

    Science.gov (United States)

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

    2017-05-01

    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.

  10. Phase diagram and magnetocaloric effects in Ni{sub 1-x}Cr{sub x}MnGe{sub 1.05}

    Energy Technology Data Exchange (ETDEWEB)

    Aryal, Anil, E-mail: aryalanil@siu.edu; Quetz, Abdiel; Pandey, Sudip; Eubank, Michael; Dubenko, Igor; Ali, Naushad [Department of Physics, Southern Illinois University, Carbondale, Illinois 62901 (United States); Samanta, Tapas; Stadler, Shane [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803 (United States)

    2015-05-07

    The structural and magnetic properties of the Ni{sub 1−x}Cr{sub x}MnGe{sub 1.05} system (for x = 0, 0.035, 0.070, 0.105) have been studied by x-ray diffraction (XRD), differential scanning calorimetry (DSC), and magnetization measurements. A change in crystal structure from orthorhombic to hexagonal was observed in the XRD data at chromium concentrations of x = 0.035, 0.070, and 0.105. The values of the cell parameters and volume of the unit cell for orthorhombic and hexagonal phase were determined. It was found that the partial substitution of Cr for Ni in Ni{sub 1−x}Cr{sub x}MnGe{sub 1.05} results in a first order magnetostructural transition from antiferromagnetic to ferromagnetic (FM) at T{sub M} = 132 K for x = 0.105. A FM to paramagnetic second order transition has been observed at T{sub C} = 204 K. A magnetic entropy change of |ΔS{sub M}| = 4.5 J/kg K for ΔH = 5 T was observed in the vicinity of T{sub C} and T{sub M} for x = 0.105. The values of the latent heat (L = 2.2 J/g) and corresponding total entropy changes (ΔS{sub T} = 16 J/kg K) have been determined from DSC measurements. A concentration-dependent phase diagram of transition temperatures has been constructed using the magnetic and DSC data.

  11. Large adiabatic temperature change in magnetoelastic transition in Ni50Mn35Cr2Sn13 Heusler alloy of granular nanostructure

    Science.gov (United States)

    Prakash, H. R.; Sharma, S. K.; Ram, S.; Chatterjee, S.

    2016-05-01

    The Ni-Mn-Sn alloys are a pioneering series of magnetocaloric materials of a huge heat-energy exchanger in the martensite transition. A small additive of nearly 2 at% Cr effectively tunes the valence electron density of 8.090 electrons per atom and a large change in the entropy ΔSM←A = 4.428 J/kg-K (ΔSM→A = 3.695 J/kg-K in the recycle) at the martensite ← austenite phase transition as it is useful for the magnetic refrigeration and other cooling devices. The Cr additive tempers the tetragonality with the aspect ratio c/a = 0.903 of the martensite phase and exhibits an adiabatic temperature change of 10 K. At room temperature, a hysteresis loop exhibits 48.91 emu/g saturation magnetization and 82.1Oe coercivity.

  12. Monte Carlo and Ab-initio calculation of TM (Ti, V, Cr, Mn, Fe, Co, Ni) doped MgH2 hydride: GGA and SIC approximation

    Science.gov (United States)

    Salmani, E.; Laghrissi, A.; Laamouri, R.; Benchafia, E.; Ez-Zahraouy, H.; Benyoussef, A.

    2017-02-01

    MgH2: TM (TM: V, Cr, Mn, Fe, Co, Ni) based dilute magnetic semiconductors (DMS) are investigated using first principle calculations. Our results show that the ferromagnetic state is stable when TM introduces magnetic moments as well as intrinsic carriers in TM: Co, V, Cr, Ti; Mg0.95TM0.05H2. Some of the DMS Ferro magnets under study exhibit a half-metallic behavior, which make them suitable for spintronic applications. The double exchange is shown to be the underlying mechanism responsible for the magnetism of such materials. The exchange interactions obtained from first principle calculations and used in a classical Ising model by a Monte Carlo approach resulted in ferromagnetic states with Curie temperatures within the ambient conditions.

  13. Electronic structure and half-metallicity in new Heusler alloys CoYO2 (Y = Sc, Ti, V, Cr, Mn, Fe, Ni, Cu, and Zn)

    Science.gov (United States)

    Esteki, S.; Ahmadian, F.

    2017-09-01

    First-principles calculations based on density functional theory (DFT) using the self-consistent full-potential linearized augmented plane wave (FPLAPW) method were applied to study the electronic structures and magnetic properties of new Heusler alloys CoYO2 (Y = Sc, Ti, V, Cr, Mn, Fe, Ni, Cu, and Zn). The calculated formation energies of these compounds were negative, therefore, they can be synthesized experimentally. All compounds were stable in ferromagnetic AlCu2Mn-type structure. In AlCu2Mn-type structure, CoScO2, CoFeO2, and CoNiO2 compounds were HM ferromagnets, CoCuO2 was a nearly half-metal, CoZnO2 was a spin gapless semiconductor, and other compounds were conventional ferromagnets. In CuHg2Ti-type structure, CoTiO2 compound had a nearly HM characteristic, CoVO2 was a spin gapless semiconductor, and other compounds were conventional ferromagnets. The origin of the half-metallic band gap for CoScO2 alloy Heusler alloy was well understood. The total magnetic moments of the three HM compounds obeyed Slater-Pauling rules (Mtot = 22-Ztot and Mtot = 32-Ztot). CoScO2 had the widest region of half-metallicity between the three half-metals indicating its high robustness of half-metallicity with respect to the variation of lattice constants.

  14. Molten Pool Behavior and Mechanical Properties of Pulsed Current Double-Sided Synchronization GTA Welded Fe-18Cr-17Mn-Ni-N

    Science.gov (United States)

    Qiang, Wei; Wang, Kehong; Feng, Yuehai; Chen, Jiahe

    2016-12-01

    Double-sided synchronization vertical gas tungsten arc welding (DSSVW) procedure was used to weld high-nitrogen low-nickel stainless steel Fe-18Cr-17Mn-Ni-N without groove and filler wire. First, the molten pool behaviors and appearances of pulsed current DSSVW (PC-DSSVW) and constant current DSSVW (CC-DSSVW) were comparatively analyzed. The periodic variation occurs in the width of both the anode region of the arc and the molten pool tail during PC-DSSVW, while the contact angle first increases and then decreases, and both the width of the anode region and the length of arc plume increase progressively in CC-DSSVW. It is found that the weld appearance of PC-DSSVW is superior to that of CC-DSSVW. Second, the forces of the DSSVW molten pool were analyzed. The result indicates that the molten pool of the DSSVW procedure is in a state of unstable equilibrium, and it will easily lose balance after being disturbed, resulting in the asymmetrical weld or hump bead. Third, the PC-DSSVW experiments at various welding speeds were conducted to study the influence of welding speed on the weld profile, microstructure, tensile strength and impact toughness. Furthermore, the solidification mode of Fe-18Cr-17Mn-Ni-N was predicted to help determine the microstructure of the welded joint. Results indicate that the weld width, weld reinforcement and melting area all increase with decreasing welding speed, and Fe-18Cr-17Mn-Ni-N solidifies as A mode. The microstructure of the base metal (BM) and heat-affected zone (HAZ) is equiaxed austenite and that of the fusion zone (FZ) is austenite dendrite with some chromium carbides dispersed in the grain boundary; with decreasing welding speed, grains become coarse. The maximum tensile strength (UTS) and elongation of PC-DSSVW joint are 860 MPa and 8.1%, and the elongation decreases dramatically with decreasing welding speed. The impact toughness decreases substantially compared to the BM, achieving 48.2% of the BM.

  15. Molten Pool Behavior and Mechanical Properties of Pulsed Current Double-Sided Synchronization GTA Welded Fe-18Cr-17Mn-Ni-N

    Science.gov (United States)

    Qiang, Wei; Wang, Kehong; Feng, Yuehai; Chen, Jiahe

    2017-02-01

    Double-sided synchronization vertical gas tungsten arc welding (DSSVW) procedure was used to weld high-nitrogen low-nickel stainless steel Fe-18Cr-17Mn-Ni-N without groove and filler wire. First, the molten pool behaviors and appearances of pulsed current DSSVW (PC-DSSVW) and constant current DSSVW (CC-DSSVW) were comparatively analyzed. The periodic variation occurs in the width of both the anode region of the arc and the molten pool tail during PC-DSSVW, while the contact angle first increases and then decreases, and both the width of the anode region and the length of arc plume increase progressively in CC-DSSVW. It is found that the weld appearance of PC-DSSVW is superior to that of CC-DSSVW. Second, the forces of the DSSVW molten pool were analyzed. The result indicates that the molten pool of the DSSVW procedure is in a state of unstable equilibrium, and it will easily lose balance after being disturbed, resulting in the asymmetrical weld or hump bead. Third, the PC-DSSVW experiments at various welding speeds were conducted to study the influence of welding speed on the weld profile, microstructure, tensile strength and impact toughness. Furthermore, the solidification mode of Fe-18Cr-17Mn-Ni-N was predicted to help determine the microstructure of the welded joint. Results indicate that the weld width, weld reinforcement and melting area all increase with decreasing welding speed, and Fe-18Cr-17Mn-Ni-N solidifies as A mode. The microstructure of the base metal (BM) and heat-affected zone (HAZ) is equiaxed austenite and that of the fusion zone (FZ) is austenite dendrite with some chromium carbides dispersed in the grain boundary; with decreasing welding speed, grains become coarse. The maximum tensile strength (UTS) and elongation of PC-DSSVW joint are 860 MPa and 8.1%, and the elongation decreases dramatically with decreasing welding speed. The impact toughness decreases substantially compared to the BM, achieving 48.2% of the BM.

  16. Microstructural observation of helium implanted and creep ruptured Fe 25%Ni 15%Cr alloys containing various MC and MN formers

    Science.gov (United States)

    Yamamoto, Norikazu; Nagakawa, Johsei; Murase, Yoshiharu; Shiraishi, Haruki

    1998-10-01

    Transmission electron microscopic observations have been carried out on Fe-25%Ni-15%Cr austenitic alloys with various MX (M=V, Ti, Nb, Zr; X=C, N) stabilizers after helium implantation and creep rupture at 923 K. It is shown that suppression of helium embrittlement can be achieved through a higher dispersion density of incoherent precipitates because of their high capability of bubble entrapment. A good agreement between the average distance of grain boundary bubbles exceeding the minimum critical size and the spacing of cavity traces on intergranularly fractured surfaces is obtained. This suggests that the enhancement of grain boundary decohesion by helium is a result of unstable growth of super-critical helium bubbles.

  17. First-principles study of TMNa{sub n} (TM = Cr, Mn, Fe, Co, Ni; n = 4-7) clusters

    Energy Technology Data Exchange (ETDEWEB)

    Pradhan, Kalpataru; Sen, Prasenjit [Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211019 (India); Reveles, J Ulises; Khanna, Shiv N [Department of Physics, Virginia Commonwealth University, Richmond, VA 23284-2000 (United States)], E-mail: prasen@hri.res.in

    2008-06-25

    Geometry, electronic structure and magnetic properties of TMNa{sub n} (TM Cr-Ni; n = 4-7) clusters are studied within a gradient-corrected density functional theory (DFT) framework. Two complementary approaches, the first adapted to all-electron calculations on free clusters and the second based on the plane-wave projector augmented wave (PAW) method within a supercell approach, are used. Except for NiNa{sub n}, the clusters in this series are found to retain the atomic moments of the TM atoms, and the magnetic moment presented an odd-even oscillation with respect to the number of Na atoms. The origin of these odd-even oscillations is explained from the nature of the chemical bonding in these clusters. Differences and similarities between the chemical bonding and the magnetic properties of these clusters and the TMNa{sub n} (TM = Sc, V and Ti; n = 4-6) clusters on the one hand and TM-doped Au and Ag clusters on the other hand are discussed.

  18. Assessment of heavy metal (Cu, Ni, Fe, Co, Mn, Cr, Zn) pollution in effluent dominated rivulet water and their effect on glycogen metabolism and histology of Mastacembelus armatus

    OpenAIRE

    Javed, Mehjbeen; Usmani, Nazura

    2013-01-01

    The present study was conducted to examine the contamination of rivulet situated at Kasimpur, Aligarh (27.218° N; 79.378° E). It receives the wastewater of Harduaganj Thermal Power Plant (HTPS) containing fly ash and heavy metals. Among the heavy metals estimated in the rivulet water, Fe (8.71 mgL-1) was present in the highest concentration followed by Cu (0.86 mgL-1), Zn (0.30 mgL-1) Mn (0.21 mgL-1), Ni (0.12 mgL-1), Co (0.11 mgL-1) and Cr (0.10 mgL-1). The values for the heavy metals such a...

  19. Powder metallurgy and mechanical alloying effects on the formation of thermally induced martensite in an FeMnSiCrNi SMA

    Directory of Open Access Journals (Sweden)

    Pricop Bogdan

    2015-01-01

    Full Text Available By ingot metallurgy (IM, melting, alloying and casting, powder metallurgy (PM, using as-blended elemental powders and mechanical alloying (MA of 50 % of particle volume, three types of FeMnSiCrNi shape memory alloy (SMA specimens were fabricated, respectively. After specimen thickness reduction by hot rolling, solution treatments were applied, at 973 and 1273 K, to thermally induce martensite. The resulting specimens were analysed by X-ray diffraction (XRD and scanning electron microscopy (SEM, in order to reveal the presence of ε (hexagonal close-packed, hcp and α’ (body centred cubic, bcc thermally induced martensites. The reversion of thermally induced martensites, to γ (face centred cubic, fcc austenite, during heating, was confirmed by dynamic mechanical analysis (DMA, which emphasized marked increases of storage modulus and obvious internal friction maxima on DMA thermograms. The results proved that the increase of porosity degree, after PM processing, increased internal friction, while MA enhanced crystallinity degree.

  20. Concentrations of Mn, Fe, Cu, Zn, Cr, Cd, Pb, Ni in selected Nigerian tubers, legumes and cereals and estimates of the adult daily intakes.

    Science.gov (United States)

    Akinyele, I O; Shokunbi, O S

    2015-04-15

    This study was designed to determine the levels of microminerals (manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), chromium (Cr)) and heavy metals (cadmium (Cd), lead (Pb) and nickel (Ni)) in some tubers, legumes and cereals obtained from the markets in Abeokuta city, South-West Nigeria. The food samples were digested by dry ashing procedure and their minerals were determined by atomic absorption spectrophotometer. The results show mean values of 1.67-32.00, 7.25-61.58, 1.59-10.56, 6.65-46.99, 0.02-0.58, legumes and cereals from various parts of the world. The daily intakes of the metals through tubers, legumes and cereals were found to be lower than the provisional tolerable daily intakes proposed by Joint FAO/WHO Expert Committee on Food Additives.

  1. Cr(III,Mn(II,Fe(III,Co(II,Ni(II,Cu(II and Zn(II Complexes with Diisobutyldithiocarbamato Ligand

    Directory of Open Access Journals (Sweden)

    Mohammad Tarique

    2011-01-01

    Full Text Available The synthesis of sulphur and nitrogen containing dithiocarbamato ligand derived from diisobutylamine as well as its coordination compounds with 3d series transition metals is presented. These synthesized compounds were characterized on the basis of elemental analysis, conductometric measurements and IR spectral studies. The analytical data showed the stoichiometry 1:2 and 1:3 for the compounds of the types ML2 {M=Mn(II, Co(II, Ni(II, Cu(II and Zn(II} and M'L3{M'=Cr(III and Fe(III} respectively. The conductometric measurements proved the non-electrolytic behaviour of all the compounds. The bidentate nature of dithiocarbamato moiety was confirmed on the basis of IR spectral data.

  2. Effects of Nitrogen and Tensile Direction on Stress Corrosion Cracking Susceptibility of Ni-Free FeCrMnC-Based Duplex Stainless Steels

    Science.gov (United States)

    Ha, Heon-Young; Lee, Chang-Hoon; Lee, Tae-Ho; Kim, Sangshik

    2017-01-01

    Stress corrosion cracking (SCC) behavior of Ni-free duplex stainless steels containing N and C (Febalance-19Cr-8Mn-0.25C-(0.03, 0.21)N, in wt %) was investigated by using a slow strain rate test (SSRT) in air and aqueous NaCl solution with different tensile directions, including parallel (longitudinal) and perpendicular (transverse) to the rolling direction. It was found that alloying N was effective in increasing the resistance to SCC, while it was higher along the longitudinal direction than the transverse direction. The SCC susceptibility of the two alloys was assessed based on the electrochemical resistance to pitting corrosion, the corrosion morphology, and the fractographic analysis. PMID:28772651

  3. Concentrations of As, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Mo, Na, Ni, Pb, and Zn in uruguayan rice determined by atomic absorption spectrometry

    Directory of Open Access Journals (Sweden)

    Mario E. Rivero Huguet

    2011-04-01

    Full Text Available The United Nations General Assembly declared the year 2004 the International Year of Rice and the concept "Rice is life". The largest nutritional problems occurring globally are protein-energy malnutrition, and Ca, Fe, I, Zn, and vitamin A deficiency. In this report, 49 rice samples (Oryza sativa L. were digested by dry ashing in order to determine As, Cd, Cr, and Pb by ETA-AAS; while Ca, Co, Cu, Fe, K, Mg, Mo, Mn, Na, Ni, and Zn were determined by FAAS; and Hg by CV-AAS using microwave-assisted decomposition. The following concentration ranges were obtained for Ca (9.1-15 mg/100 g, Cd (2.30-4.12 µg/kg, Co (41-60 µg/kg, Cu (1.33-180 mg/kg, Fe (4.41-7.15 mg/kg, K (167-217 mg/100 g, Mg (45-121 mg/100 g, Mo (0.52-0.97 mg/kg, Mn (5.45-25.4 mg/kg, Na (0.95-2.50 mg/100g, Ni (0.53-0.72 mg/kg, and Zn (5.86-12.6 mg/kg. Mean recoveries of elements from fortified rice were: 87±12% for As, 95.3±8.9% for Ca, 106.2±7.7% for Cd, 103.3±6.5% for Co, 89.4±8.1% for Cr, 99.3±4.6% for Cu, 103±10% for Fe, 96.3±9.3% for Hg, 95.4±12% for K, 98.3±8.0% for Mg, 93.4±7.8% for Mo, 95.3±9.9% for Mn, 89±12% for Na, 90.3±9.7% for Ni, 91.2±5.5% for Pb and 92.0±9.4% for Zn. The concentrations of the minerals and microelements studied fall within the typical range of rice grown around the world. Potassium was the most abundant mineral, followed by Mg and Ca; among microelements, the concentrations of Cu, Fe, Mo, Mn, Na, and Zn in rice were outstanding. It was also found that the milling process highly affects the K, Mg, Mn, Na, and Zn concentrations, while it has little influence on Ca, Co, Cu, and Fe. On the other hand, there is a loss of Ca, Fe, and Mn during the parboiling process. Recent studies have shown the potential to exploit the genetic variation of rice seeds with regard to the concentration of some minerals (Ca, Fe, Zn, etc. without affecting yield or adding new traits. All rice samples tested showed lower levels of As, Cd, Hg, and Pb in comparison

  4. Assessment of heavy metal (Cu, Ni, Fe, Co, Mn, Cr, Zn) pollution in effluent dominated rivulet water and their effect on glycogen metabolism and histology of Mastacembelus armatus.

    Science.gov (United States)

    Javed, Mehjbeen; Usmani, Nazura

    2013-01-01

    The present study was conducted to examine the contamination of rivulet situated at Kasimpur, Aligarh (27.218° N; 79.378° E). It receives the wastewater of Harduaganj Thermal Power Plant (HTPS) containing fly ash and heavy metals. Among the heavy metals estimated in the rivulet water, Fe (8.71 mgL(-1)) was present in the highest concentration followed by Cu (0.86 mgL(-1)), Zn (0.30 mgL(-1)) Mn (0.21 mgL(-1)), Ni (0.12 mgL(-1)), Co (0.11 mgL(-1)) and Cr (0.10 mgL(-1)). The values for the heavy metals such as Fe, Ni and Mn were beyond the limits set by UNEPGEMS. Bioaccumulation of these heavy metals was detected in tissues such as gills, liver, kidney, muscle and integument of the fish Mastacembelus armatus. Accumulation of Fe (213.29 - 2601.49 mgkg(-1).dw) was highest in all the organs. Liver was the most influenced organ and integument had the least metal load. The accumulation of Fe, Zn, Cu and Mn, observed in the tissues were above the values recommended by FAO/WHO. Biochemical estimation related to blood glucose, liver and muscle glycogen conducted showed significant (p < 0.01) elevation in blood glucose content over control (17.73%), whereas liver glycogen dropped significantly (p < 0.01) over control (-89.83%), and similarly muscle glycogen also decreased significantly (p < 0.05) over control (-71.95%), suggesting enhanced glycolytic capacity to fuel hepatic metabolism. Histopathological alterations were also observed in selected organs (gills, liver and kidney) of Mastacembelus armatus.

  5. Effect of Tempering on Microstructure and Property of Cr-Ni-Mn Stainless Steel Wire%回火对Cr-Ni-Mn不锈钢丝微观组织和性能的影响

    Institute of Scientific and Technical Information of China (English)

    杨建春; 刘国权; 董秀萍; 白鸿柏

    2011-01-01

    用等应变应力对比法分析了回火温度对金属橡胶材料(构件)力学性能的影响,用SEM观察微观组织形貌.结果表明:冷拔态不锈钢丝在450℃以下回火消除残余变形应力,并伴有ε碳化物析出,构件强度波动;500℃以上回火发生恢复再结晶,内部微观组织由形变α'马氏体转变为α铁素体,伴有孔洞缩小和溢出,构件强度降低,而450~500℃同火,ε碳化物析出达到平衡,微小裂纹焊合,且未发生恢复再结晶,构件有较高的强度.综合分析,450~500℃是Cr-Ni-Mn不锈钢丝制备金属橡胶材料(构件)较为理想的回火温度.%The influences of tempering temperature on mechanical properties of the metal rubber components were studied by the comparisons way of stress at equal strain. The microstructure of cool-drawing stainless steel wire was observed after tempering by SEM. The results show that the residual stress of cool-drawing stainless steel wire, which is caused by the deformation, is relieved, and ε carbonides are precipitated when tempered at 450 ℃, the strength of the components is undulate; recovery and recrystallization occurrs at 500 ℃, the inner microstructure transforms from α' martensite into α ferrite, and the inner micro-cavity shrinks and spills out, the strength of the components decreases; however, when tempered at 450 ℃~500 ℃, the precipitation of ε carbonides reaches the balance, the micro-cracks seam, but there is no recovery and recrystallization, the strength of the components is higher. In summary, tempering at 450 ℃ ~500 ℃ is suitable for the metal rubber material (components) which is made of cool-drawing Cr-Ni-Mn stainless steel wire.

  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. A role of {alpha}' martensite introduced by thermo-mechanical treatment in improving shape memory effect of an Fe-Mn-Si-Cr-Ni alloy

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Huabei; Wen, Yuhua; Liu, Gang; Wang, Chaoping; Li, Ning [College of Manufacturing Science and Engineering, Sichuan University Chengdu (China)

    2011-05-15

    The evolution of {alpha}' martensite with different thermo-mechanical treatment and its effect on the shape memory effect were studied in an Fe-14Mn-5Si-8Cr-4Ni alloy. The {alpha}' martensite was introduced by only 5% pre-deformation, and its amount increased with increasing pre-deformation up to 20%. The {alpha}' martensite started to transform into austenite when the annealing temperature was 773 K. As the annealing temperature increased to 1 073 K, the {alpha}' martensite almost transformed fully into austenite. The {alpha}' martensite introduced by the thermo-mechanical treatment could prevent collisions between different {epsilon} martensite bands during deformation. The intrusion of {alpha}' martensite was another key reason that the stress-induced {epsilon} martensite bands in Fe-Mn-Si based shape memory alloys formed in a domain-specific manner in addition to that of uniformly distributed stacking faults after thermo-mechanical treatment. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Combinatorial pulsed laser deposition of Fe, Cr, Mn, and Ni-substituted SrTiO3 films on Si substrates.

    Science.gov (United States)

    Kim, Dong Hun; Bi, Lei; Aimon, Nicolas M; Jiang, Peng; Dionne, Gerald F; Ross, C A

    2012-03-12

    Combinatorial pulsed laser deposition (CPLD) using two targets was used to produce a range of transition metal-substituted perovskite-structured Sr(Ti(1-x)M(x))O(3-δ) films on buffered silicon substrates, where M = Fe, Cr, Ni and Mn and x = 0.05-0.5. CPLD produced samples whose composition vs distance fitted a linear combination of the compositions of the two targets. Sr(Ti(1-x)Fe(x))O(3-δ) films produced from a pair of perovskite targets (SrTiO(3) and SrFeO(3) or SrTiO(3) and SrTi0(0.575)Fe(0.425)O(3)) had properties similar to those of films produced from single targets, showing a single phase microstructure, a saturation magnetization of 0.5 μ(B)/Fe, and a strong out-of-plane magnetoelastic anisotropy at room temperature. Films produced from an SrTiO(3) and a metal oxide target consisted of majority perovskite phases with additional metal oxide (or metal in the case of Ni) phases. Films made from SrTiO(3) and Fe(2)O(3) targets retained the high magnetic anisotropy of Sr(Ti(1-x)Fe(x))O(3-δ), but had a much higher saturation magnetization than single-target films, reaching for example an out-of-plane coercivity of >2 kOe and a saturation magnetization of 125 emu/cm(3) at 24%Fe. This was attributed to the presence of maghemite or magnetite exchange-coupled to the Sr(Ti(1-x)Fe(x))O(3-δ). Films of Sr(Ti(1-x)Cr(x))O(3-δ) and Sr(Ti(1-x)Mn(x))O(3-δ) showed no room temperature ferromagnetism, but Sr(Ti(1-x)Ni(x))O(3-δ) did show a high anisotropy and magnetization attributed mainly to the perovskite phase. Combinatorial synthesis is shown to be an efficient process for enabling evaluation of the properties of epitaxial substituted perovskite films as well as multiphase films which have potential for a wide range of electronic, magnetic, optical, and catalytic applications.

  9. HEAVY METALS (Hg, Cu, Mn, Cr e Ni CONTENTS IN THE RIO DAS PEDRAS LAGOON, MOJI-GUAÇU RIVER BASIN (SÃO PAULO STATE, BRAZIL = HISTÓRICO DA PRESENÇA DE METAIS PESADOS (Hg, Cu, Mn, Cr e Ni NA LAGOA RIO DAS PEDRAS, BACIA DO RIO MOJI-GUAÇU -SP, BRASIL

    Directory of Open Access Journals (Sweden)

    Claudinéia Raquel de Oliveira

    2003-01-01

    Full Text Available The presence of heavy metals in a sediment profile from the Rio das Pedras lagoon, located at the Moji-Guaçu river floodplain, São Paulo, was investigated. Samples were stratified at each 1 cm, sieved in 63 m m and digested in a strong acid solution (HNO3 + HF + HClO4 in PTFE bomb. The extracts were analyzed by emission plasma spectrometry (ICP-AES for Al, Cu, Mn, Cr and Ni contents. For Hg, the direct pyrolysis of samples and atomic fluorescence spectrometry detector AFS were employed. By using Al as a normalizer agent, an enrichment of metals concentration, with exception for Mn was observed. Average concentration for Cu (0.12 mg g-1 and Mn (1.12 mg g-1 were considered high in comparison to those concentrations in an unpolluted environment. Probably, these data are related to the agricultural activity (sugarcane plantation around the lagoon, or to the Moji-Guaçu river transport in the flood season. Hg, Cr and Niconcentrations were similar the those verified in unpolluted areas. The chronology inventigation, determined by the 210Pb technique, indicated that the 25 cm long sediment profile shows a 135 years of deposition history of the suspended material in this lagoon. = A presença de metais pesados em perfil de sedimento coletado na Lagoa Rio das Pedras, localizada na planície de inundação do rio Moji-Guaçu, São Paulo, foi investigada. Amostras estratificadas a cada 1 cm foram peneiradas a 63 m m e digeridas através de ataque ácido (HNO3 + HF + HClO4 em bombas de PTFE. Os extratos obtidos foram analisados quanto aos teores de Al, Cu, Mn, Cr e Ni por espectrometria de emissão de plasma (ICP-AES. Para Hg, empregou-se a pirólise direta da amostra e detecção por AFS. Utilizando-se Al como elemento normalizador, observou-se enriquecimento nos teores de metais pesados para anos recentes, exceto para Mn. As concentrações médias de Cu (0,12 mg g-1 e Mn (1,12 mg g-1 para amostras de sedimentos foram elevadas, em comparação

  10. 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.

  11. Effect of H2O on metal-silicate partitioning of Ni, Co, V, Cr, Mn and Fe: Implications for the oxidation state of the Earth and Mars

    Science.gov (United States)

    Clesi, V.; Bouhifd, M. A.; Bolfan-Casanova, N.; Manthilake, G.; Fabbrizio, A.; Andrault, D.

    2016-11-01

    This study investigates the metal-silicate partitioning of Ni, Co, V, Cr, Mn and Fe during core mantle differentiation of terrestrial planets under hydrous conditions. For this, we equilibrated a molten hydrous CI chondrite model composition with various Fe-rich alloys in the system Fe-C-Ni-Co-Si-S in a multi-anvil over a range of P, T, fO2 and water content (5-20 GPa, 2073-2500 K, from 1 to 5 log units below the iron-wüstite (IW) buffer and for XH2O varying from 500 ppm to 1.5 wt%). By comparing the present experiments with the available data sets on dry systems, we observes that the effect of water on the partition coefficients of moderately siderophile elements is only moderate. For example, for iron we observed a decrease in the partition coefficient of Fe (Dmet/silFe) from 9.5 to 4.3, with increasing water content of the silicate melt, from 0 to 1.44 wt%, respectively. The evolution of metal-silicate partition coefficients of Ni, Co, V, Cr, Mn and Fe are modelled based on sets of empirical parameters. These empirical models are then used to refine the process of core segregation during accretion of Mars and the Earth. It appears that the likely presence of 3.5 wt% water on Mars during the core-mantle segregation could account for ∼74% of the FeO content of the Martian mantle. In contrast, water does not play such an important role for the Earth; only 4-6% of the FeO content of its mantle could be due to the water-induced Fe-oxidation, for a likely initial water concentration of 1.8 wt%. Thus, in order to reproduce the present-day FeO content of 8 wt% in the mantle, the Earth could initially have been accreted from a large fraction (between 85% and 90%) of reducing bodies (similar to EH chondrites), with 10-15% of the Earth's mass likely made of more oxidized components that introduced the major part of water and FeO to the Earth. This high proportion of enstatite chondrites in the original constitution of the Earth is consistent with the 17O,48Ca,50Ti,62Ni

  12. Assessment of heavy metals/metalloid (As, Pb, Cd, Ni, Zn, Cr, Cu, Mn) concentrations in edible fish species tissue in the Pearl River Delta (PRD), China.

    Science.gov (United States)

    Leung, H M; Leung, A O W; Wang, H S; Ma, K K; Liang, Y; Ho, K C; Cheung, K C; Tohidi, F; Yung, K K L

    2014-01-15

    The major aim of this study was to investigate heavy metal content of edible fish in the PRD. Eleven species of fish (consisting of 711 individuals) [catfish (Clarias fuscus), tilapia (Oreochromis mossambicus), grass carp (Ctenopharyngodon idellus), bighead carp (Aristichthys nobilis), mandarin fish (Siniperca kneri), snakehead (Channa asiatiea), black bass (Micropterus salmoides), mangrove snapper (Lutjanus griseus), star snapper (Lutjanu stellatus), snubnose pompano (Trachinotus blochii) and orange-spotted grouper (Epinephelus coioides)] were collected for the analyses of heavy metals. Overall concentrations (mg/kg, ww) in the fish muscles were: As (0.03-1.53), Pb (0.03-8.62), Cd (0.02-0.06), Ni (0.44-9.75), Zn (15.7-29.5), Cr (0.22-0.65), Cu (0.79-2.26), Mn (0.82-6.91). Significant level of Pb were found in tilapia at all locations. It is recommended that heavy metal concentrations in different fish species must be determined on a regular basis in the future so as to reduce human health risks from acute and chronic food intoxication.

  13. A New Resource-Saving, High Chromium and Manganese Super Duplex Stainless Steels 29Cr-12Mn-2Ni-1Mo-xN

    Institute of Scientific and Technical Information of China (English)

    MA Zheng-huan; ZHAO Xiang-juan; GE Chang-sheng; DING Tie-suo; LI Jun; XIAO Xue-shan

    2011-01-01

    A new family of resource saving, high chromium and manganese super duplex stainless steels (DSSs), with a composition in mass percent, % of Cr 0.29, Mn 0.12, Ni 2.0, Mo i. 0, and N 0. 51-0. 68, has been developed by examining the effect of N on the microstructure, mechanical properties and corrosion properties. The results show that these alloys have a balanced ferrite-austenite relation. The austenite volume fraction decreases with the solution treatment temperature, but it increases with an increase in N content. The increases in nitrogen enhance the ultimate tensile strength (UTS) and reduce the ductility of the material slightly. The pitting corrosion potential increases first and then decreases with an increase in nitrogen content when the amount of N arrives to 0.68%. The yield stress and ultimate tensile strength of solution treated samples were more than 680 and 900 MPa, the elongation of experimental alloys are higher than 30%, respectively, what is more, the pitting potentials were beyond 1 100 mV.

  14. 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.

  15. Solid-state reactions during mechanical alloying of ternary Fe-Al-X (X=Ni, Mn, Cu, Ti, Cr, B, Si) systems: A review

    Science.gov (United States)

    Hadef, Fatma

    2016-12-01

    The last decade has witnessed an intensive research in the field of nanocrystalline materials due to their enhanced properties. A lot of processing techniques were developed in order to synthesis these novel materials, among them mechanical alloying or high-energy ball milling. In fact, mechanical alloying is one of the most common operations in the processing of solids. It can be used to quickly and easily synthesize a variety of technologically useful materials which are very difficult to manufacture by other techniques. One advantage of MA over many other techniques is that is a solid state technique and consequently problems associated with melting and solidification are bypassed. Special attention is being paid to the synthesis of alloys through reactions mainly occurring in solid state in many metallic ternary Fe-Al-X systems, in order to improve mainly Fe-Al structural and mechanical properties. The results show that nanocrystallization is the common result occurring in all systems during MA process. The aim of this work is to illustrate the uniqueness of MA process to induce phase transformation in metallic Fe-Al-X (X=Ni, Mn, Cu, Ti, Cr, B, Si) systems.

  16. Shape Memory Effect of As-aged Fe-14Mn-5Si-8Cr-4Ni-0.2C Alloy

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The effects of aging temperature on shape memory effect, mechanical properties and microstructure of Fe-14Mn-5Si-8Cr-4Ni-0.2C shape memory alloy have been studied. The results showed that the second phase particles rich in chromium, manganese and silicon precipitate during aging, and thereby increase the hardness and strength of the alloy. The shape recovery ratio can be remarkably improved by aging and a maximum value can be obtained at 1223 K, which is 68% higher than that of the specimen in solid solution state. When the aging temperature is below 1223 K, the amount of second phase particles increases as the aging temperature increases. The size of austenite grain increases with increasing aging temperature. When the temperature is over 1223 K, the second phase particles can not precipitate. The lack of second phase particles and the increase of grain size make the hardness and shape recovery ratio drastically decrease, when the temperature is over 1223 K.

  17. Solid-state reactions during mechanical alloying of ternary Fe–Al–X (X=Ni, Mn, Cu, Ti, Cr, B, Si) systems: A review

    Energy Technology Data Exchange (ETDEWEB)

    Hadef, Fatma, E-mail: hadef77@yahoo.fr [Laboratoire de Recherche sur la Physico-Chimie des Surfaces et Interfaces, LRPCSI, Université 20 Août 1955, BP 26, Route d’El-Haddaiek, Skikda 21000 (Algeria); Département de Physique, Faculté des Sciences, Université 20 Août 1955, BP 26, Route d’El-Haddaiek, Skikda 21000 (Algeria)

    2016-12-01

    The last decade has witnessed an intensive research in the field of nanocrystalline materials due to their enhanced properties. A lot of processing techniques were developed in order to synthesis these novel materials, among them mechanical alloying or high-energy ball milling. In fact, mechanical alloying is one of the most common operations in the processing of solids. It can be used to quickly and easily synthesize a variety of technologically useful materials which are very difficult to manufacture by other techniques. One advantage of MA over many other techniques is that is a solid state technique and consequently problems associated with melting and solidification are bypassed. Special attention is being paid to the synthesis of alloys through reactions mainly occurring in solid state in many metallic ternary Fe–Al–X systems, in order to improve mainly Fe–Al structural and mechanical properties. The results show that nanocrystallization is the common result occurring in all systems during MA process. The aim of this work is to illustrate the uniqueness of MA process to induce phase transformation in metallic Fe–Al–X (X=Ni, Mn, Cu, Ti, Cr, B, Si) systems. - Highlights: • A review of state of the art on binary Fe–Al alloys was presented. • Structural and microstructural properties of MA ternary Fe–Al–X alloys were summerized. • MA process is a powerful tool for producing metallic alloys at the nanometer scale.

  18. Effect of Heat Treatment on Delayed Fracture Resistance of High Strength Steel 30CrMnSi2NiNb

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The steel specimens of nominal composition 0.3C-1.0Cr-1.0Mn-2.0Si-1.0Ni-0.04Nb were quenched and tempered or isothermally quenched from various temperatures. It is found that the steel quenched and tempered with a tensile strength of 1 500-1 600 MPa has a KISCC (critical stress intensity factor) value below 15.0 MPa*m1/2. The steel isothermally quenched with a tensile strength of 1 350-1 750 MPa has a KISCC value about 20.0 MPa*m1/2. In addition, with increase of isothermal quenching temperature, the tensile strength decreases greatly and KISCC value does not pronouncedly change. The microstructure of isothermally quenched specimens is composed of bainite and retained austenite. The delayed fracture resistance is dependent on the stability of austenite, which is in turn related to the retained austenite volume fraction and carbon content in austenite.

  19. 双真空熔炼(VIM+VAR)30CrMnSiNi2A钢屈服强度的影响因素分析%Factors Governing Yield Strength of 30CrMnSiNi2A Steel Melted by VIM+VAR

    Institute of Scientific and Technical Information of China (English)

    刘天琦; 支敏学; 朱杰远; 李志; 刘宪民; 赵振业

    2003-01-01

    对影响双真空(VIM+VAR)熔炼30CrMnSiNi2A钢屈服强度(σ0.2)的因素进行了分析.结果表明,C, Si对该钢σ0.2影响较大,为了确保σ0.2满足技术规范的要求,C, Si含量宜控制在上限;在规定200~300℃回火温度范围内,较高的温度回火对提高σ0.2有利.

  20. Research on tests and numerical analysis of corrosion and wear damage of mooring chain steel 22MnCrNiMo%海洋系泊链钢22MnCrNiMo 腐蚀磨损试验与数值分析研究

    Institute of Scientific and Technical Information of China (English)

    粟京; 刘刚; 孙佳君

    2015-01-01

    A numerical analysis method is proposed to calculate accumulative damages of corrosion and wear of chain link in service period.Both the corrosion of chain annulus in seawater environment and the wear of contact surface between adjacent links can be considered by using non-linear finite element analy-sis.For determining mechanical properties of the chain steel used in the finite element analysis,mechani-cal tests with the low-carbon and low-alloy steel 22MnCrNiMo are carried out to obtain its material hard-ness,seawater erosion and corrosion wear resistance.Numerical results and experimental data are com-pared to verify the feasibility and accuracy of the proposed method.%建立了锚链在海洋环境中腐蚀磨损(简称“磨蚀”)累积损伤数值分析方法,该方法采用非线性有限元分析,能够同时考虑锚链链环间接触面在海水中的腐蚀和磨损耦合损伤。针对22MnCrNiMo 低碳低合金钢材料,进行了力学性能、海水侵蚀以及磨蚀性能等多方面的试验研究,确定了基于该材料的锚链链环间接触面在海水中磨蚀损伤数值分析中的相关参数。通过对计算结果与试验结果的比较分析,验证了锚链链环间接触面磨蚀累积损伤数值分析方法的可行性与准确性。

  1. Influence of Cr, Mn, Co, Ni Substitution on Magnetic Properties and Magnetocaloric Effect in LaFe11.5Si1.5%Cr,Mn,Co,Ni替代对LaFe11.5Si1.5磁性与磁热效应的影响

    Institute of Scientific and Technical Information of China (English)

    胡义嘎; 松林; 王高峰; 李福安; 特古斯

    2011-01-01

    The effects of substitution of Fe by Cr, Mn, Co and Ni on the structure, magnetic and magnetocaloric properties of LaFe11.5Si1.5 were investigated by means of X-ray diffraction and magnetic measurements. The results showed that the compounds investigated mainly crystallized in NaZn13-type cubic structure. For Cr, Mn, Co and Ni substituted compounds, the impurity phases were mainly 1.3% α-Fe and 2.5% LaFeSi, both Curie temperature and saturation magnetization decreased with these impurity phases in LaFe11.5Si1.5, while increased for Co-substitution. The thermal hysteresis reduced for all substitution. The maximum value of magnetic entropy change ∣△Sm∣ for a magnetic field change of 0 ~5 T was about 23.8, 19.8, 26.4, 20.0 and 25.9 J·(kg·K) -1 for T = Cr, Mn, Fe, Co and Ni, respectively.%通过X射线衍射和磁性测量手段研究了由Cr,Mn,Co,Ni原子替代LaFe11.5Si1.5化合物中的Fe原子,对化合物结构、磁性与磁热效应的影响.结果表明:替代后的所有化合物的主相均为NaZn13型立方结构并存在杂相,衍射数据精修图表明杂相分别为1.3%的α-Fe相和2.5%的LaFeSi相.Cr,Mn和Ni的替代Fe使LaFe11.5 Si1.5化合物的居里温度与饱和磁化强度下降,而Co的替代化合物的居里温度与饱和磁化强度且增加.所有的替代均使化合物的热滞下降.对Cr,Mn,Fe,Co,Ni替代Fe的化合物在0~5.0T的磁场下最大磁熵变-△Sm分别为23.8,19.8,26.4,20.0和25.9 J·(kg·K)-1.

  2. Chemical reactions during sintering of Fe-Cr-Mn-Si-Ni-Mo-C-steels with special reference to processing in semi-closed containers

    Directory of Open Access Journals (Sweden)

    Cias A.

    2015-01-01

    Full Text Available Sintering of Cr, Mn and Si bearing steels has recently attracted both experimental and theoretical attention and processing in semiclosed containers has been reproposed. This paper brings together relevant thermodynamic data and considers the kinetics of some relevant chemical reactions. These involve iron and carbon, water vapour, carbon monoxide and dioxide, hydrogen and nitrogen of the sintering atmospheres and the alloying elements Cr, Mn, Mo and Si. The paper concludes by presenting mechanical properties data for three steels sintered in local microatmosphere with nitrogen, hydrogen, nitrogen-5% hydrogen and air as the furnace gas.

  3. Optimization of the Arc Spraying Process Parameters of the Fe–Base Mn-Si-Cr-Mo-Ni Coatings for the Best Wear Performance

    Directory of Open Access Journals (Sweden)

    Justinas GARGASAS

    2016-05-01

    Full Text Available In this paper, the use of Fe–base Mn-Si-Cr-Mo-Ni and Fe–base Mn-Si-Cr wires for thermal arc spraying is presented. For this purpose the mechanical and physical properties of coatings were evaluated. The quality of the coating’s was dependent on the selected equipment, spray materials, technological parameters of the spray and spray technology. The aim was to qualify and optimize the parameters for spray coating to get the best coatings properties with good tribological properties. All coatings were deposited on mild steel S235JR substrates. Two experimental cored wires of unique chemical composition – STEIN-MESYFIL 932 V and STEIN-MESYFIL 954 V – were used for thermal arc spraying. The wires of 1.6 mm diameter were used for the surfacing material. Hardness, porosity and oxide measurements were used to verify the spray parameters and analyze the coatings. Rubber wheel test, which is based on the standard ASTM G65, was used. Dry-sand, rubber-wheel procedure according ASTM G65 was used to investigate low stress abrasion, whereas for high stress abrasion investigations a rubber wheel was used. This experiment was carried out by changing the speed of disc friction, travel distance and measuring the mass loss of surface friction. Miller Test according to ASTM G75-95 Standard was carried out in experiment with friction. The samples were immersed in water with corundum and polished with 22 N load, for 8 hours. Furthermore a correlation was performed between the spraying current and voltage parameter. The coatings’ cross sections were examined using scanning electron microscope (SEM and optical microscopy. The influence of the composite components of the coatings’ microstructure, such as porosity, microhardness, oxide inclusions, on the tribological properties of thermal sprayed coatings is discussed in this paper. DOI: http://dx.doi.org/10.5755/j01.ms.22.1.7339

  4. Optimization of the Arc Spraying Process Parameters of the Fe–Base Mn-Si-Cr-Mo-Ni Coatings for the Best Wear Performance

    Directory of Open Access Journals (Sweden)

    Justinas GARGASAS

    2016-05-01

    Full Text Available In this paper, the use of Fe–base Mn-Si-Cr-Mo-Ni and Fe–base Mn-Si-Cr wires for thermal arc spraying is presented. For this purpose the mechanical and physical properties of coatings were evaluated. The quality of the coating’s was dependent on the selected equipment, spray materials, technological parameters of the spray and spray technology. The aim was to qualify and optimize the parameters for spray coating to get the best coatings properties with good tribological properties. All coatings were deposited on mild steel S235JR substrates. Two experimental cored wires of unique chemical composition – STEIN-MESYFIL 932 V and STEIN-MESYFIL 954 V – were used for thermal arc spraying. The wires of 1.6 mm diameter were used for the surfacing material. Hardness, porosity and oxide measurements were used to verify the spray parameters and analyze the coatings. Rubber wheel test, which is based on the standard ASTM G65, was used. Dry-sand, rubber-wheel procedure according ASTM G65 was used to investigate low stress abrasion, whereas for high stress abrasion investigations a rubber wheel was used. This experiment was carried out by changing the speed of disc friction, travel distance and measuring the mass loss of surface friction. Miller Test according to ASTM G75-95 Standard was carried out in experiment with friction. The samples were immersed in water with corundum and polished with 22 N load, for 8 hours. Furthermore a correlation was performed between the spraying current and voltage parameter. The coatings’ cross sections were examined using scanning electron microscope (SEM and optical microscopy. The influence of the composite components of the coatings’ microstructure, such as porosity, microhardness, oxide inclusions, on the tribological properties of thermal sprayed coatings is discussed in this paper. DOI: http://dx.doi.org/10.5755/j01.ms.22.1.7339

  5. PECULIARITIES OF PROCESSES OF CARBIDE FORMATION AND DISTRIBUTION OF Cr, Mn AND Ni IN WHITE CAST IRONS

    Directory of Open Access Journals (Sweden)

    V. V. Netrebko

    2015-01-01

    Full Text Available During crystallization of castings from white cast iron, carbides Me3С, Me7С3, Me23С6 were formed depending on chromium and carbon content. Impeded chromium diffusion caused formation of thermodynamically unstable and non-uniform phases (carbides. During heat treatment process stable equilibrium phases were formed as a result of rearrangement of the carbides’ crystal lattice, replacement of iron, manganese, nickel and silicon atoms by chromium atoms. The allocated atoms concentrated, forming inclusions of austenite inside the carbides. Holding during 9 hours at 720 °С and annealing decreased the non-uniformity of chromium distribution in the metallic base of cast iron containing 11,5 % Cr, and increased it in the cast iron containing 21,5 % Cr. Holding during 4.5 hours at 1050 °С and normalization decreased the non-uniformity of chromium distribution in the metallic base of cast iron containing 21,5 % Cr, and increased it in cast iron containing 11,5 % Cr.

  6. Composite Coating Prepared by Plasma Alloying AlCoCrCuFex MnNiCx High-entropy Alloy on the Surface of HT250 Cast Iron%HT250铸铁表面等离子合金化AlCoCrCuFex MnNiCx高熵合金复合涂层

    Institute of Scientific and Technical Information of China (English)

    卢金斌; 彭竹琴; 马明星; 李俊魁; 齐振东; 贺亚勋

    2015-01-01

    Objective To improve the abrasion resistance of the surface on cast iron by plasma alloying high entropy alloy coat-ing process. Methods High entropy alloy coating was prepared on the surface of HT250 cast iron by plasma alloying Al, Co, Cr, Cu, Mn and Ni powders in equal molar ratio. The microstructure of the coating was studied by SEM, EDS, XRD, and its micro-hardness distribution was tested by the microhardness tester. Results Due to melting of a small amount of iron, the atoms such as Fe and C dissolved into the coating to get AlCoCrCuFexMnNiCx, the thickness of which was about 0. 2 mm. The mixing entropy of both the composition and the microstructure of the coating distributed in a high-medium-low gradient. The microstructure of the coating was mainly composed of high-entropy alloy dendrite and interdendrite cementite andσphase etc, and the coating contained mainly FCC, BCC, Fe3 C and σ phase. The microhardness of the coating was about 350 ~600HV0. 2, which was significantly higher than that of the matrix (200 ~230HV0. 2). Conclusion The composite coating including high entropy alloy and carbide could be formed on the surface of cast iron by plasma alloying, which improved the microhardness of the cast iron, and thus helped to improve the abrasion resistance of the surface on cast iron.%目的:通过等离子合金化高熵合金涂层,提高铸铁表面耐磨性。方法采用等离子合金化法,以等摩尔比的Al,Co,Cr,Cu,Mn,Ni单质金属粉在HT250铸铁表面制备高熵合金复合涂层。通过SEM, EDS,XRD等分析涂层的组织,测试涂层的显微硬度分布。结果由于铸铁基体少量熔化,基体中的Fe和C元素进入涂层,形成了厚度约为0.2 mm的AlCoCrCuFexMnNiCx 高熵合金涂层。从涂层表面到基材,体系的混合熵呈高熵-中熵-低熵的梯度变化。涂层主要由高熵合金的枝晶和枝晶间渗碳体、σ相等组织构成,主要有FCC,BCC,Fe3 C及σ相。涂层的显微硬度大约为350~600HV0.2,

  7. 渗碳温度对22Si2MnCrNi2MoA钢渗碳层的影响%Influence of carburizing temperature on microstructure and properties of carburized layers of a 22Si2MnCrNi2MoA steel

    Institute of Scientific and Technical Information of China (English)

    黄斌; 朱洪武; 杨忠; 周乐育; 刘雅政

    2013-01-01

    Influence of carburizing temperature on carburized layers of a 22Si2MnCrNi2MoA steel solid-carburized was studied by OM,SEM,XRD and hardness measurements.The relationship between carburizing temperature and carbon concentration,micro-hardness and retained austenite of the carburized layers were examined.The results indicate that with the carburizing temperature increasing for carburizing time of 6 h,the carbon concentration of the carburized layers gradually increases,and the distribution gradient of the carbon concentration gets smoother.The relationship between the micro-hardness of the carburized layers and carbon concentration obeys normal distribution.It is recommended that the surface carbon concentration of the carburized steel should be controlled in the range of 0.80% and 0.90% in order to obtain martensite microstructure with high hardness.When the surface carbon concentration is more than 0.80%-0.90%,aging treatment for a long time or deep cryogenic treatment are required to remove retained austenite in the carburized layers.%通过固体渗碳试验研究了加热温度对钎具用钢22Si2MnCrNi2MoA渗碳层的影响,分析了渗碳温度-碳浓度-显微硬度-残留奥氏体的关系以及残留奥氏体的控制措施.结果表明:当渗碳时间为6h时,随着渗碳温度的升高,渗碳层的碳浓度逐渐增加,碳浓度分布梯度越来越平缓.22Si2MnCrNi2MoA钢渗碳层的显微硬度-碳浓度关系符合正态分布.在渗碳处理过程中,为了使渗碳表层获得硬度很高的马氏体组织,22Si2MnCrNi2MoA钢渗碳层表面碳浓度应该控制在0.80% ~0.90%之间.当表面碳浓度超过0.80%~0.90%时,渗碳完成后需采取后续的工艺措施来消除已经存在的残留奥氏体,如采用长时间自然时效或深冷处理等.

  8. Synthesis and Electrochemical Properties of LiNi0.5Mn1.5O4 Cathode Materials with Cr3+ and F- Composite Doping for Lithium-Ion Batteries

    Science.gov (United States)

    Li, Jun; Li, Shaofang; Xu, Shuaijun; Huang, Si; Zhu, Jianxin

    2017-06-01

    A Cr3+ and F- composite-doped LiNi0.5Mn1.5O4 cathode material was synthesized by the solid-state method, and the influence of the doping amount on the material's physical and electrochemical properties was investigated. The structure and morphology of the cathode material were characterized by XRD, SEM, TEM, and HRTEM, and the results revealed that the sample exhibited clear spinel features. No Cr3+ and F- impurity phases were found, and the spinel structure became more stable. The results of the charge/discharge tests, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) test results suggested that LiCr0.05Ni0.475Mn1.475O3.95F0.05 in which the Cr3+ and F- doping amounts were both 0.05, had the optimal electrochemical properties, with discharge rates of 0.1, 0.5, 2, 5, and 10 C and specific capacities of 134.18, 128.70, 123.62, 119.63, and 97.68 mAh g-1 , respectively. After 50 cycles at a rate of 2 C, LiCr0.05Ni0.475Mn1.475O3.95F0.05 showed extremely good cycling performance, with a discharge specific capacity of 121.02 mAh g-1 and a capacity retention rate of 97.9%. EIS test revealed that the doping clearly decreased the charge-transfer resistance.

  9. Microstructural characterization of a Zr-Ti-Ni-Mn-V-Cr based AB{sub 2}-type battery alloy

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Zhan

    1999-01-01

    Transmission Electron Microscopy (TEM), combined with X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) was employed to investigate a proprietary and multicomponent AB{sub 2} type Nickel-Metal Hydride (Ni-MH) battery alloy. This material was prepared by High Pressure Gas Atomization (HPGA) and examined in both the as-atomized and heat treated condition. TEM examination showed a heavily faulted dendritic growth structure in as-atomized powder. Selected Area Diffraction (SAD) showed that this region consisted of both a cubic C15 structure with lattice constant a=7.03 and a hexagonal C14 structure with lattice parameter a=4.97 {angstrom}, c=8.11 {angstrom}. The Orientation Relationship (OR) between the C14 and C15 structures was determined to be (111)[1{bar 1}0]{sub C15}//(0001)[11{bar 2}0]{sub C14}. An interdendritic phase possessing the C14 structure was also seen. There was also a very fine grain region consisting of the C14 structure. Upon heat treatment, the faulted structure became more defined and appeared as intercalation layers within the grains. Spherical particles rich in Zr and Ni appeared scattered at the grain boundaries instead of the C14 interdendritic phase. The polycrystalline region also changed to a mixture of C14 and C15 structures. These results as well as phase stability of the C15 and C14 structures based on a consideration of atomic size factor and the average electron concentration are discussed.

  10. Resolving surface chemical states in XPS analysis of first row transition metals, oxides and hydroxides: Cr, Mn, Fe, Co and Ni

    Energy Technology Data Exchange (ETDEWEB)

    Biesinger, Mark C., E-mail: biesingr@uwo.ca [Surface Science Western, University of Western Ontario, University of Western Ontario Research Park, Room LL31, 999 Collip Circle, London, Ontario, N6G 0J3 (Canada); ACeSSS (Applied Centre for Structural and Synchrotron Studies), University of South Australia, Mawson Lakes, SA 5095 (Australia); Payne, Brad P. [Department of Chemistry, University of Western Ontario, London, Ontario, N6A 5B7 (Canada); Grosvenor, Andrew P. [Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan, S7N 5C9 (Canada); Lau, Leo W.M. [Surface Science Western, University of Western Ontario, University of Western Ontario Research Park, Room LL31, 999 Collip Circle, London, Ontario, N6G 0J3 (Canada); Department of Chemistry, University of Western Ontario, London, Ontario, N6A 5B7 (Canada); Gerson, Andrea R.; Smart, Roger St.C. [ACeSSS (Applied Centre for Structural and Synchrotron Studies), University of South Australia, Mawson Lakes, SA 5095 (Australia)

    2011-01-15

    Chemical state X-ray photoelectron spectroscopic analysis of first row transition metals and their oxides and hydroxides is challenging due to the complexity of their 2p spectra resulting from peak asymmetries, complex multiplet splitting, shake-up and plasmon loss structure, and uncertain, overlapping binding energies. Our previous paper [M.C. Biesinger et al., Appl. Surf. Sci. 257 (2010) 887-898.] in which we examined Sc, Ti, V, Cu and Zn species, has shown that all the values of the spectral fitting parameters for each specific species, i.e. binding energy (eV), full wide at half maximum (FWHM) value (eV) for each pass energy, spin-orbit splitting values and asymmetric peak shape fitting parameters, are not all normally provided in the literature and data bases, and are necessary for reproducible, quantitative chemical state analysis. A more consistent, practical and effective approach to curve fitting was developed based on a combination of (1) standard spectra from quality reference samples, (2) a survey of appropriate literature databases and/or a compilation of literature references and (3) specific literature references where fitting procedures are available. This paper extends this approach to the chemical states of Cr, Mn, Fe, Co and Ni metals, and various oxides and hydroxides where intense, complex multiplet splitting in many of the chemical states of these elements poses unique difficulties for chemical state analysis. The curve fitting procedures proposed use the same criteria as proposed previously but with the additional complexity of fitting of multiplet split spectra which has been done based on spectra of numerous reference materials and theoretical XPS modeling of these transition metal species. Binding energies, FWHM values, asymmetric peak shape fitting parameters, multiplet peak separation and peak area percentages are presented. The procedures developed can be utilized to remove uncertainties in the analysis of surface states in nano

  11. Influence of annealing temperature on the electrochemical and surface properties of the 5-V spinel cathode material LiCr0.2Ni0.4Mn1.4O4 synthesized by a sol–gel technique

    DEFF Research Database (Denmark)

    Younesi, Reza; Malmgren, Sara; Edström, Kristina

    2014-01-01

    LiCr0.2Ni0.4Mn1.4O4 was synthesized by a sol–gel technique in which tartaric acid was used as oxide precursor. The synthesized powder was annealed at five different temperatures from 600 to 1,000 °C and tested as a 5-V cathode material in Li-ion batteries. The study shows that annealing at higher...... values higher than 85 % at C/2, C, and 2C rates at 25 °C after 50 cycles. Annealing at 600–800 °C resulted in formation of spinel particles smaller than 200 nm, while almost micron-sized particles were obtained at 900– 1,000 °C. Chromium deficiency was detected at the surface of the active materials...... annealed at low temperatures. The XPS results indicate presence of Cr6+ impurity when the annealing temperature was not high enough. The study revealed that increased annealing temperature is beneficial for both improved electrochemical performance of LiCr0.2Ni0.4Mn1.4O4 and for avoiding formation of Cr6...

  12. Microstructure of AlCoCrCuFeNiMnV0.2Cx high-entropy alloy by plasma transferred arc cladding%等离子熔覆AlCoCrCuFeNiMnV0.2Cx高熵合金的组织结构

    Institute of Scientific and Technical Information of China (English)

    王智慧; 王兴阳; 贺定勇; 崔丽; 周正; 赵秋颖

    2015-01-01

    利用等离子熔覆技术在Q235钢板上制备AlCoCrCuFeNiMnV0.2Cx(x=0,0.02,0.05,0.1,0.2,摩尔比)高熵合金熔覆层,采用XRF、OM、SEM、XRD、显微硬度计等分析了熔覆层的合金成分、微观组织、物相结构以及显微硬度.结果表明,熔覆层基体组织均为典型的树枝晶结构,由FCC+ BCC固溶体组成,枝晶为BCC相,枝晶间为FCC相.当x为0.05 ~0.2时,熔覆层组织中有大量VC相在枝晶内析出,其形态多呈十字状和多边形颗粒状.由于碳的固溶强化作用和VC的析出相强化作用,随着碳含量的增加,熔覆层显微硬度呈增大的趋势,当x=0.2时,显微硬度达到572.4 HV.

  13. Microstructure and properties of AlCoCrCuFexMnNi high-entropy alloy coating prepared by plasma surface alloying%等离子合金化AlCoCrCuFexMnNi高熵合金涂层的组织与性能

    Institute of Scientific and Technical Information of China (English)

    卢金斌; 彭竹琴; 李俊魁; 马明星; 齐振东; 贺亚勋; 龚正

    2016-01-01

    在45#钢基体上采用等离子束合金化法制备AlCoCrCuFexMnNi高熵合金涂层。采用SEM,EDS,XRD等研究高熵合金涂层的组织,利用显微硬度计测试涂层的显微硬度分布。结果表明:采用等离子束合金化Al,Co, Cr,Cu,Mn和Ni等摩尔单质金属粉,在等离子束作用下45#钢基材中的Fe元素参与表面合金化,形成了厚度约为1 mm的AlCoCrCuFexMnNi七主元高熵合金涂层,涂层主要由BCC结构的枝晶和FCC结构的枝晶间组织组成。另外,还有σ相主要分布在枝晶间,涂层从表面到基材,体系的混合熵呈高熵−中熵−低熵梯度变化。涂层的维氏显微硬度(HV0.2)达到670~400的梯度分布。%The AlCoCrCuFexMnNi high-entropy alloy (HEA) coating was prepared on 45# steel substrate by plasma alloying method. Microstructure of the HEA coating was analyzed by SEM, EDS and XRD. The microhardness distribution of coating was tested by microhardness tester. The results show that the principal element of Fe in the 45# steel substrate participates in surface alloying process during the plasma irradiation alloying. The microstructure of the AlCoCrCuFexMnNi HEA coating with a thickness of 1 mm is mainly composed of dendritic structure and interdendritic structure. The alloy mainly composes of FCC, BCC andσ phases. From the surface of high entropy alloying coating to substrate, there is a gradual distribution of the mixing entropy from high entropy, medium entropy to low entropy. The microhardness of the coating reaches 670−400 HV0.2.

  14. Combination of Different In Situ Characterization Techniques and Scanning Electron Microscopy Investigations for a Comprehensive Description of the Tensile Deformation Behavior of a CrMnNi TRIP/TWIP Steel

    Science.gov (United States)

    Weidner, Anja; Biermann, Horst

    2015-08-01

    The class of low-carbon, high-alloy CrMnNi steels exhibits outstanding mechanical properties with respect to high strength and ductility due to either transformation-induced plasticity (TRIP) or twinning-induced plasticity (TWIP) effect depending on chemical composition and deformation temperature. However, the ongoing deformation mechanisms like the formation of stacking faults, martensitic phase transformation or deformation-induced twinning are overlapping and the kinetics of the microstructure evolution are quite complex. Therefore, in addition to macroscopic deformation tests and microstructural investigations by scanning electron microscopy, a combination of several in situ characterization techniques with either high lateral and/or temporal resolution as well as providing integral volume information were chosen in order to give a thoroughly and comprehensive description of the deformation behavior of CrMnNi TRIP/TWIP steels. In addition, the complementary in situ techniques like in situ nanoindentation, micro-digital image correlation, and acoustic emission measurements provide excellent possibility for description of materials behavior on a multiscale level from the submicrometer scale up to the macroscopic range. The results obtained by the complementary techniques can support the future modeling of the deformation behavior of TRIP/TWIP steels dependent on chemical composition, temperature, grain size and grain orientation.

  15. Welding and corrosion resistance of the new nitrogen alloyed steel X2 CrNiMnMoN241764. Caracteristicas de soldadura y resistencia a la corrosion de nuevo acero X2 CrNiMnMoN 241764 aleado con nitrogeno

    Energy Technology Data Exchange (ETDEWEB)

    Arit, N.; Henser, H.; GroB, V.

    1994-01-01

    Remanit 4565 S is a new developed nitrogen alloyed austenitic stainless steel. Characteristic features are: improved strength and toughness, delayed precipitation of carbides and intermetallic phases, improved corrosion resistance. Welding fabrication is possible without the risk of pore formation. TIG-welded joints are as resistant as the base metal, using filler metal SG-NiCr 20 Mo 15 (Thermanit Nimo C) respectively SG-NiCr 28 Mo(Thermanit 30/40 E) according to the area of application. (Author) 8 refs.

  16. Nucleation and growth kinetics of La0.7Sr0.3Cr0.4Mn0.6O3-δ SOFC perovskite: Symmetry alteration evolution induced by Cu2+ and Ni2+ impregnation

    Directory of Open Access Journals (Sweden)

    A. Concha-Balderrama

    2016-12-01

    Full Text Available La0.7Sr0.3Cr0.4Mn0.6O3-δ perovskite nanoparticles have been synthetized using an ethylene glycol modified sol-gel method and impregnated by Cu0.75Ni0.25 nanoparticles. The phase transitions and nucleation kinetics were studied by time resolved x-ray diffraction, Rietveld, Raman spectroscopy and high resolution transmission electron microscopy. Findings have shown that, an atomic disorder dominates from room temperature to 400 °C. Nanoparticles with crystal size <26 nm start through nuclei formation of La0.7Sr0.3Cr0.4Mn0.6O3-δ and SrCrO4 solid solutions with Pm3¯m cubic and P21/n monoclinic symmetry respectively in the range of 600–650 °C. Symmetry reduction from the Pm3¯m⟶R3¯c space group had been obtained at a lower temperature (750 °C than those reported in the literature in oxygen atmosphere and it was confirmed by an octahedral distortion, which takes place in the crystallographic direction[22̅1]/(12̅2. The Johnson-Mehl-Avrami model had described the whole process, where the existence of two phases was shown before it reached its complete D3d6 point group symmetry.

  17. Estudo de metais pesados (Co, Cu, Fe, Cr, Ni, Mn, Pb e Zn na Bacia do Tarumã-Açu Manaus (AM Heavy metal (Co, Cu, Fe, Cr, Ni, Mn, Pb e Zn study in the Tarumã-Açu Basin Manaus (AM

    Directory of Open Access Journals (Sweden)

    Genilson Pereira Santana

    2007-01-01

    Full Text Available Os resíduos gerados em domicílios incluem diversos produtos, como pesticidas, produtos farmacêuticos, detergentes, óleos de cozinha, metais pesados contidos em baterias e outros utensílios. Esses resíduos são lançados continuamente em aterro sanitário ou lixões em cidades como Manaus. O chorume produzido nesses aterros, quando não tratados, contamina recursos hídricos superficiais e subterrâneos. Neste estudo foi feita uma avaliação das conseqüências da liberação do chorume no sistema hídrico da bacia do Tarumã-Açu. Amostras de água e sedimento foram coletadas nos igarapés Matrinxã, Acará, Bolívia, bacia do Tarumã-Açu e dentro do aterro sanitário (Manaus - Amazonas - Brasil em março 2001. As amostras de água foram filtradas em filtro Milipore (0,45 mm de poro e, em seguida, tratadas com HNO3 concentrado. As amostras de sedimento foram peneiradas em malha de 0,053 mm e digeridas com HCl:HNO3 (1:3 a 150ºC. As concentrações de alguns metais pesados (Co, Cu, Fe, Cr, Ni, Mn, Pb e Zn foram determinadas nas amostras de água e sedimento por espectrometria de absorção atômica de chama. Os resultados revelaram que a concentração dos metais pesados é muito acima dos permitidos pela resolução 357/2005 do CONAMA em praticamente todos os locais amostrados, mostrando que o Aterro Sanitário é um dos principais responsáveis pelo impacto ambiental observado nos corpos hídricos estudados. As análises dos componentes principais (PCA e hierárquica de cluster (HCA, revelam que os pontos de coleta localizados dentro do aterro sanitário apresentam características diferentes dos outros locais amostrados. Além disso, o HCA e PCA mostraram que existe uma similaridade entre os pontos de coleta localizados fora do aterro o que permite afirmar que o chorume do aterro se dissolve por todo corpo hídrico estudado.Domestic sewage involves several products, such as pesticides, pharmaceutics products, detergents, soybean oil

  18. Properties of Zr-Ti-V-Mn-Ni hydride alloy

    Institute of Scientific and Technical Information of China (English)

    文明芬; 翟玉春; 王新海; 陈廉

    2002-01-01

    Six kinds of Zr-based hydride alloy were designed. XRD analyses show that the main phase of Zr1-xTix-(NiCoMnV)2.1 alloy is Laves C15 when x is between 0 and 0.5,but the more the content of Ti, the more the Laves C14 phases. The amount of Laves C14 can be up to the amount of Laves C15 after substituted V and Fe by V-Fe alloy in Zr0.6-Ti0.4(NiCoMnVFeCr)1.7 alloy. The electrochemical measurements show that the discharge capacity of Zr0.9Ti0.1-(NiCoMnV)2.1 electrode is about 340mA * h/g at 60mA/g, but with increasing the amount of Ti, the discharge capacity of alloy electrode abruptly decreases; at 300mA/g current density, its Kr can be up to 91%. The discharge capacity of Zr0.6-Ti0.4-(NiCoMn(V-Fe)Cr)1.62 alloy electrode is about 200mA * h/g at first cycle, the maximum capacity is more than that of the electrode with pure V, and about 315mA * h/g.

  19. Spectroscopic and thermal degradation behavior of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes with thiopental sodium anesthesia drug

    Science.gov (United States)

    Refat, Moamen S.

    2013-04-01

    A new series of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes have been synthesized with thiopental sodium anesthesia drug. The elemental analyses of the complexes are confined to stoichiometry of the formulas [M(TPL)3]ṡnH2O (M = Cr(III) or Fe(III); n = 6 or 5), [M(TPL)2(H2O)2]ṡnH2O (M = Mn(II), Co(II) or Ni(II); n = 0 or 4), and [M(TPL)2] (M = Cu(II) or Zn(II); n = 2 or 0) respectively, where TPL is thiopental chelating agent. Structures have been discussed and suggested upon elemental analyses, infrared, Raman, electronic, electron spin resonance, 1H NMR spectral data and magnetic studies. The X-ray powder diffraction (XRD) was performed of metal complexes. The XRD patterns indicate crystalline nature for the complexes. The measured low molar conductance values in dimethylsulfoxide indicate that the complexes are non-electrolyte nature. Spectroscopic discussion refer that coordination take place through three types: Cdbnd N (pyrimidine moiety) nitrogen and C2sbnd S (2-thiolate group) for Cr(III), Mn(II) and Fe(III), C6dbnd O (amido group) oxygen and C2sbnd S (2-thiolate group) for Co(II) and Ni(II), and Cu(II) and Zn(II) ions coordinated via Cdbnd N (pyrimidine moiety) nitrogen, C2dbnd S (2-thiolate group) and C6dbnd O (amido group) oxygen, respectively. The thermal behavior (TG/DTG/DTA) of the complexes was studied and kinetic parameters were determined by Horowitz-Metzger and Coats-Redfern methods. The thiopental and its complexes have been screened for their antimicrobial (G+ and G-) bacteria (Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa) and fungi (Aspergillus flavus and Candida albicans) activities by minimum inhibitory concentration (MIC) method.

  20. Investigation of the Welding Performance of 1Cr18Mn8Ni5N Stainless Steel with A-TIG Welding%奥氏体不锈钢A-TIG焊焊接性能研究

    Institute of Scientific and Technical Information of China (English)

    魏钰; 许静远; 刘爱阳; 王海燕

    2012-01-01

    研究了1Cr18Mn8Ni5N不锈钢薄板A-TIG焊与常规TIG焊和填丝TIG焊的焊接规范和焊接接头性能.结果表明:与常规TIG焊相比,A-TIG焊焊缝宽度减小,焊缝组织中晶粒细化,焊接接头的抗拉强度显著提高,且高于母材的抗拉强度;与填丝TIG焊相比,A-TIG只需小电流且不需要填丝即可达到相同的焊接性能,同时可以降低成本,提高生产效率.%The welding specification and welding joint property of the activating flux TIG welding (A-TIG welding) , conventional TIG welding and filler metal TIG welding in the welding experiments of thin plates of lCrl8Mn8Ni5N stainless steel are investigated. The results show that compared with conventional TIG welding, A-TIG welding can decrease the weld width, refine the grains of the welding bead microstructure and improve the tensile strength of the welding joint; A-TIG welding only needs small welding current and no filler metal for achieving the same welding performance as filler metal TIG welding, which reduces cost and improves the production efficiency.

  1. Study on the behavior of the heavy metals Cu, Cr, Ni, Zn, Fe, Mn and {sup 137}Cs in an estuarine ecosystem using Mytilus galloprovincialis as a bioindicator species: the case of Thermaikos gulf, Greece

    Energy Technology Data Exchange (ETDEWEB)

    Catsiki, Vassiliki-Angelique [Hellenic Centre for Marine Research, Mavro Lithari, 46.7 Km Athens-Sounio, Anavyssos Attikis 19013 (Greece)]. E-mail: cats@ath.hcmr.gr; Florou, H. [National Centre for Scientific Research ' Demokritos' , Ag. Paraskevi 153 10, Athens (Greece)

    2006-07-01

    Mussels are worldwide recognized as pollution bioindicators and used in Mussel Watch programs, because they accumulate pollutants in their tissues at elevated levels in relation to pollutant biological availability in the marine environment. The present study deals with the use of Mytilus galloprovincialis as a local bioindicator of heavy metal and {sup 137}Cs contamination in an estuarine ecosystem (Thermaikos gulf, Greece in Eastern Mediterranean). M. galloprovincialis samples were collected monthly from two aquaculture farms during the period April to October 2000. Analyses for the heavy metals Cu, Cr, Ni, Zn, Fe, Mn and {sup 137}Cs showed that the concentrations measured were low and similar to those from other non-polluted Mediterranean areas. In terms of the two sampling stations, there were no statistically significant differences between them. On the contrary, the seasonal evolution of either heavy metals or {sup 137}Cs levels presented high variation. The levels were found to increase during the cold period of the year, especially for Cu, Zn, Mn and Cr which are essential for life. Stable metals were positively inter-related and moreover, metals more involved in biochemical activities seem to present more correlations than others with less significant role in the metabolism of the organisms.

  2. The effect of MC and MN stabilizer additions on the creep rupture properties of helium implanted Fe-25% Ni-15% Cr austenitic alloy

    Science.gov (United States)

    Yamamoto, Norikazu; Nagakawa, Johsei; Shiraishi, Haruki

    1995-10-01

    Helium embrittlement resistance of Fe-25% Ni-15% Cr austenitic alloys with various MX (M = V, Ti, Nb, Zr; X = C, N) stabilizers was compared through post helium implantation creep testing at 923 K. While significant deterioration by helium in terms of creep rupture time and elongation occurred for all materials investigated, the suppression of the deterioration, especially in rupture time, was discerned for the materials in which semi-coherent MC (M = Ti, Ti + Nb, V + Ti) particles were distributed at high density. The material which contains the incoherent M 23C 6 as predominant precipitates seems to be less degraded by helium than those containing the MXs (M = Zr, V; X = C, N), if compared at the same number density of precipitates. Therefore, it is suggested that the high density dispersion of incoherent M 23C 6 as well as semi-coherent Ti containing MC particles would be beneficial in reducing the detrimental helium influences on mechanical properties.

  3. Microstructural analysis of thermally induced and deformation induced martensitic transformations in Fe-12.5 wt.% Mn-5.5 wt.% Si-9 wt.% Cr-3.5 wt.% Ni alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kirindi, T. [Department of Computer Technology, Faculty of Education, Kirikkale University, 71450 Yahsihan, Kirikkale (Turkey)]. E-mail: talipkirindi@yahoo.com; Dikici, M. [Department of Physics, Faculty of Science and Arts, Kirikkale University, 71450 Yahsihan, Kirikkale (Turkey)

    2006-01-05

    Martensitic transformations induced by thermally and compression deformation at room temperature in Fe-12.5 wt.% Mn-5.5 wt.% Si-9 wt.% Cr-3.5 wt.% Ni alloy were studied in detail by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). From microstructural observations, it was seen that heat treated samples exhibited regular overlapping of stacking faults and {epsilon} martensite plates were formed parallel to each other. Also, TEM investigations showed that the orientation relationship between {gamma} (fcc) and {epsilon} (hcp) phases corresponds to Shoji-Nishiyama type. With applied low plastic deformation rate, only {epsilon} martensite occurred in austenite grain. As a consequence, 4 and 25% plastic deformation at room temperature caused {epsilon} martensite formation in austenite phase and the new {epsilon} (hcp) and {alpha}' (bcc) martensite formation in martensite phases, respectively. Orientation relationship between {epsilon} and {alpha}' phases was found by the electron diffraction analysis.

  4. Chromium and iron contained half-Heusler MnNiGe-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Budzynski, M. [UMCS, Institute of Physics, 1 sq.M.Curie-Skłodowska, 20-031 Lublin (Poland); Valkov, V.I.; Golovchan, A.V.; Kamenev, V.I. [Donetsk Institute for Physics and Engineering, 72, R.Luxemburg str., 83114 Donetsk (Ukraine); Mitsiuk, V.I., E-mail: vmitsiuk@gmail.com [Scientific-Practical Materials Research Center of National Academy of Sciences of Belarus, 19 P.Brovky Str., 220072 Minsk (Belarus); Sivachenko, A.P. [Donetsk Institute for Physics and Engineering, 72, R.Luxemburg str., 83114 Donetsk (Ukraine); Surowiec, Z. [UMCS, Institute of Physics, 1 sq.M.Curie-Skłodowska, 20-031 Lublin (Poland); Tkachenka, T.M. [Scientific-Practical Materials Research Center of National Academy of Sciences of Belarus, 19 P.Brovky Str., 220072 Minsk (Belarus)

    2015-12-15

    The magnetic characteristics of chromium and iron containing MnNiGe-based alloys with several types of quenching and annealing were investigated. It was found that the quenched Mn{sub 0.89}Cr{sub 0.11}NiGe has a spontaneous and magnetic field induced magnetostructural first-order transitions at room temperature. These transitions might be accompanied by a large magnetocaloric effect. In general, Mn{sub 0.89}Cr{sub 0.11}NiGe can be classified as promising material for use in the magnetocaloric application at room temperatures. The first order magnetostructural phase transition from the ferromagnetic to paramagnetic state is not realized in MnNi0.90Fe0.10Ge. In contrast to Mn{sub 0.89}Cr{sub 0.11}NiGe, however, the FM state in quenched-on-wheel MnNi0.90Fe0.10Ge is preserved to the lowest temperatures. Based on the set of the magnetic properties, it has been concluded that the iron containing MnNiGe-based alloys are less promising for practical use.

  5. Performance and sulfur poisoning of Ni/CeO2 impregnated La0.75Sr0.25Cr0.5Mn0.5O3-δ anode in solid oxide fuel cells

    Science.gov (United States)

    Li, Yiqian; Zhang, Yaohui; Zhu, Xingbao; Wang, Zhihong; Lü, Zhe; Huang, Xiqiang; Zhou, Yongjun; Zhu, Lin; Jiang, Wei

    2015-07-01

    In this study, comparison experiments are conducted based on yttria-stabilized zirconia (YSZ) electrolyte supported single solid oxide fuel cells (SOFCs) with pure La0.75Sr0.25Cr0.5Mn0.5O3-δ (LSCrM) or Ni/CeO2 impregnated LSCrM anodes. The single cells are tested in dry H2 and H2/H2S (50 ppm) mixture, respectively. Compared with the pure LSCrM anode, the cell with Ni/CeO2 impregnated LSCrM presents a significant performance improvement when the pure H2 is fueled to the anode, and shows a good stability during a constant-current discharge testing (398 mA cm-2). When the fuel is switched to H2/H2S mixture, the cell with Ni/CeO2 impregnated LSCrM anode still shows a remarkable constant-current discharge (120 mA cm-2) performance compared with pure LSCrM anode. The Ni/CeO2 impregnation can improve the electrochemical performance of the LSCrM anode without any sacrifice of sulfur tolerance ability. The Ni/CeO2 impregnated LSCrM might be a potential anode material for solid oxide fuel cell operating in sulfur-containing fuels. The XRD and XPS results demonstrate that the anode poisoning product is composed of adsorbed sulfur, metal sulfides and sulfate radical. The mass spectrum result confirms that the poisoning mechanism involves the reaction of sulfur with anode rather than the direct reaction between H2S gas and anode.

  6. Preparation of nanoporous Ni and Ni-Cu by dealloying of rolled Ni-Mn and Ni-Cu-Mn alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hakamada, Masataka, E-mail: masataka-hakamada@aist.go.j [Materials Research Institute for Sustainable Development, National Institute of Advanced Industrial Science and Technology (AIST), 2266-98 Anagahora, Shimosihidami, Moriyama, Nagoya 463-8560 (Japan); Mabuchi, Mamoru [Department of Energy Science and Technology, Graduate School of Energy Science, Kyoto University, Kyoto 606-8501 (Japan)

    2009-10-19

    Nanoporous Ni, Ni-Cu and Cu with ligament sizes of 10-20 nm were fabricated by dealloying rolled Ni-Mn, Cu-Ni-Mn and Cu-Mn alloys, respectively. Unlike conventional Raney nickel composed of brittle Ni-Al intermetallic compounds, the initial alloys had good workability. Ni and Cu atoms formed a homogeneous solid solution in the nanoporous architecture. The ligament sizes of nanoporous Ni and Ni-Cu were smaller than that of nanoporous Cu, reflecting the difference between the surface diffusivities of Ni and Cu.

  7. Synergistic damage mechanism of corrosion and cavitation-erosion for plasma ion nitrided 18Cr-8Ni-1.1Mn-0.43C stainless steel in seawater

    Science.gov (United States)

    Chong, Sang-Ok; Kim, Seong-Jong

    2017-01-01

    In this work, it was investigated that resistance of combination damages of electrochemical corrosion and cavitation-erosion for plasma ion nitrided 18Cr-8Ni-1.1Mn-0.43C stainless steel at various process temperatures under cavitation environment in seawater. The plasma ion nitriding treatment was performed with a gas mixture ratio of 25% N2 and 75% H2 at a temperature of 623, 673, 723, and 773 K for 10 h, at a chamber pressure of 250 Pa. Expanded austenite (γN) was produced at whole plasma ion nitriding temperatures and especially phases of CrN and γ‧ were observed at 773 K in X-ray diffraction (XRD) analysis. In Tafel analysis, the highest corrosion potential and corrosion current density were analyzed on the untreated (non-cavitation) specimen among specimens under the cavitation condition. Under cavitation environment, the highest corrosion potential and the lowest corrosion current density presented at 673 K. As a result of observation of surface morphologies after anodic polarization experiment under cavitation environment, uniform corrosion was observed on the untreated specimen and plasma ion nitrided specimens, while localized corrosion was shown on the untreated substrate under non-cavitation environment. Furthermore, greater damage depth and severe morphologies were observed at plasma ion nitrided specimens than untreated substrate, whereas the greatest weight loss at 723 K was indicated due to the high pitting corrosion potential and wide passivity potential region.

  8. DNA interaction, antimicrobial, anticancer activities and molecular docking study of some new VO(II), Cr(III), Mn(II) and Ni(II) mononuclear chelates encompassing quaridentate imine ligand.

    Science.gov (United States)

    Abdel-Rahman, Laila H; Abu-Dief, Ahmed M; Aboelez, Moustafa O; Hassan Abdel-Mawgoud, Azza A

    2017-05-01

    The present study was conducted to synthesis of some new imine Cr(III), VO(II), Mn(II) and Ni(II) complexes derived from the condensation of 2-amino phenol with 2-hydroxynapthaldehyde were synthesized. The prepared HNPN imine ligand was analyzed by its melting point, IR, (1)H NMR and (13)C NMR spectroscopies. The investigated HNPN imine complexes were characterized by elemental analysis, FT IR, UV-vis and thermal analysis (TGA) under nitrogen atmosphere from ambient temperature to 750°C. The experimental results revealed that the investigated complexes contain hydrated water molecules. The molar conductance values of complexes are relatively low, indicating the non-electrolytic nature of these complexes. Magnetic susceptibility measurements show that the investigated complexes are paramagnetic. Moreover, the stability constants of the preparing complexes were determined spectrophotometrically. All the complexes were found to be monomeric 1:1 (M:L) stoichiometry in nature with octahedral geometry for Cr(III), tetrahedral for Mn(II), square planner for Ni(II) and square pyramidal for VO(II). Moreover, the prepared HNPN imine ligand and its complexes were evaluated for antimicrobial effect against some types of bacteria such as Bacillus subtilis (+ve), Escherichia coli(-ve) and Staphylococcus aureus (+ve) and some types of fungi such as Aspergillusniger, Candida glabrata and Trichophyton rubrum. The results of these studies indicate that the metal complexes exhibit a stronger antibacterial and antifungal efficiency compared to their corresponding imine ligand. Moreover, the interaction of the investigated complexes with CT-DNA was checked using spectral studies, viscosity measurements and gel electrophoreses. The absorption titration studies revealed that each of these complexes is an avid binder to calf thymus-DNA. Also, there was appreciable changes in the relative viscosity of DNA, which is consistent with enhanced hydrophobic interaction of the aromatic rings and

  9. Effects of partial Mn-substitution on magnetic and magnetocaloric properties in Pr{sub 0.7}Ca{sub 0.3}Mn{sub 0.95}X{sub 0.05}O{sub 3} (Cr, Ni, Co and Fe) manganites

    Energy Technology Data Exchange (ETDEWEB)

    Selmi, A. [Laboratoire de Physique des Matériaux, Faculté des Sciences de Sfax, Sfax University, B.P. 1171, 3000 Sfax (Tunisia); M’nassri, R., E-mail: rafik_mnassri@yahoo.fr [Higher Institute of Applied Sciences and Technology of Kasserine, Kairouan University, B.P. 471, 1200 Kasserine (Tunisia); Cheikhrouhou-Koubaa, W. [Laboratoire de Physique des Matériaux, Faculté des Sciences de Sfax, Sfax University, B.P. 1171, 3000 Sfax (Tunisia); Chniba Boudjada, N. [Institut NEEL, B.P. 166, 38042 Grenoble Cedex 9 (France); Cheikhrouhou, A. [Laboratoire de Physique des Matériaux, Faculté des Sciences de Sfax, Sfax University, B.P. 1171, 3000 Sfax (Tunisia)

    2015-01-15

    Highlights: • Pr{sub 0.7}Ca{sub 0.3}Mn{sub 0.95}X{sub 0.05}O{sub 3}(X = Cr, Ni, Co and Fe) ceramics were prepared by solid state method. • The manganite phases crystallize in an orthorhombic (Pnma) structure. • The samples exhibit a second order paramagnetic (PM)–ferromagnetic (FM) phase transition at the Curie temperature T{sub C}. • Maximum RCP equal to 405 J/kg observed for Pr{sub 0.7}Ca{sub 0.3}Mn{sub 0.95}Cr{sub 0.05}O{sub 3}. • Second order phase transition is confirmed by Arrott plots and universal curves of entropy change. • The experimental ΔS{sub M} are well predicted by the phenomenological universal curve. - Abstract: Structural, magnetic and magnetocaloric properties of Pr{sub 0.7}Ca{sub 0.3}Mn{sub 0.95}X{sub 0.05}O{sub 3}(X = Cr, Ni, Co and Fe) ceramics have been investigated by X-ray diffraction (XRD) and magnetic measurements. Powder samples have been elaborated using the solid state reaction method at high temperature. The Rietveld analysis of the powder X-ray diffraction shows that the samples crystallize in the orthorhombic structure with Pnma space group. Magnetic measurements show that all our materials exhibit a paramagnetic–ferromagnetic transition with decreasing temperature. The Arrott plots of ours materials reveal the occurrence of a second-order phase transition. The maximum values of magnetic entropy change |ΔS{sub M}{sup max}| are 2.92, 2.96, 3.1, and 2.38 J kg{sup −1} K{sup −1} and the relative cooling power (RCP) values are 405.8, 378.2, 352.2 and 337.4 J kg{sup −1} for a magnetic-field change from 0 to 5 T for Cr, Ni, Co and Fe respectively. The large RCP found in our substituted samples will be interesting for magnetic refrigeration over a wide temperature range ∼130 K around its paramagnetic to ferromagnetic transition temperature. With the scaling laws of ΔS{sub M}, the experimental ΔS{sub M} collapse onto a universal curve for several ceramics, where an average curve is obtained. With the

  10. Synthesis and electrochemical properties of LiNi0.4Mn1.5Cr0.1O4 and Li4Ti5O12

    CSIR Research Space (South Africa)

    Liu, GQ

    2011-08-01

    Full Text Available particles are about 0.5 um, and well distributed. The submicron particles should exhibit better electrochemical properties than large particles. 6 Because the chemical bond of Cr-O is strong, the Cr-doped compound LNMCO can enhance the structure...

  11. Standard Specification for Electric Fusion-Welded Ni-Cr-Co-Mo Alloy (UNS N06617), Ni-Fe-Cr-Si Alloys (UNS N08330 and UNS N08332), Ni-Cr-Fe-Al Alloy (UNS N06603), Ni-Cr-Fe Alloy (UNS N06025), and Ni-Cr-Fe-Si Alloy (UNS N06045) Pipe

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2014-01-01

    Standard Specification for Electric Fusion-Welded Ni-Cr-Co-Mo Alloy (UNS N06617), Ni-Fe-Cr-Si Alloys (UNS N08330 and UNS N08332), Ni-Cr-Fe-Al Alloy (UNS N06603), Ni-Cr-Fe Alloy (UNS N06025), and Ni-Cr-Fe-Si Alloy (UNS N06045) Pipe

  12. Characterization of TiC-FeCrMn Cermets Produced by Powder Metallurgy Method

    Directory of Open Access Journals (Sweden)

    Märt Kolnes

    2015-09-01

    Full Text Available TiC-NiMo cermets combine relatively low density with high hardness. Because nickel is known as a toxin and allergen and allergy to nickel is a phenomenon which has assumed growing importance in recent years there has been a flurry of activity to find alternatives to the nickel binder in cermets. It is also the global research and technical development trend in the powder metallurgy cermets industry. In present research TiC-based cermets with FeCrMn binder system were fabricated. Three different sintering conditions were used (vacuum sintering, sinter/HIP and sintering under low Ar pressure. Because of high vapor pressure of manganese different sintering conditions and technologies were investigated to depress the Mn-loss during sintering. Chemical composition of TiC-FeCrMn cermets after different sintering conditions were analyzed by energy-dispersive X-ray spectroscopy (EDS and mechanical properties – hardness and fracture toughness were evaluated on the samples. Results of research showed that Ni-free TiC-based CrMn-steels bonded cermets compare unfavorably with cermets bonded with CrNi austenitic steels in terms of fracture toughness and corrosion resistance. Noticeable Mn-loss during vacuum sintering can be avoided when sintering under low Ar gas pressure.DOI: http://dx.doi.org/10.5755/j01.ms.21.3.7364

  13. Martensitic Transformation in Ni-Mn-Sn-Co Heusler Alloys

    Directory of Open Access Journals (Sweden)

    Alexandre Deltell

    2015-04-01

    Full Text Available Thermal and structural austenite to martensite reversible transition was studied in melt spun ribbons of Ni50Mn40Sn5Co5, Ni50Mn37.5Sn7.5Co5 and Ni50Mn35Sn10Co5 (at. % alloys. Analysis of X-ray diffraction patterns confirms that all alloys have martensitic structure at room temperature: four layered orthorhombic 4O for Ni50Mn40Sn5Co5, four layered orthorhombic 4O and seven-layered monoclinic 14M for Ni50Mn37.5Sn7.5Co5 and seven-layered monoclinic 14M for Ni50Mn35Sn5Co5. Analysis of differential scanning calorimetry scans shows that higher enthalpy and entropy changes are obtained for alloy Ni50Mn37.5Sn7.5Co5, whereas transition temperatures increases as increasing valence electron density.

  14. Study of the properties of flux cored wire of Fe-C-Si-Mn-Cr-Mo-Ni-V-Co system for the strengthening of nodes and parts of equipment used in the mineral mining

    Science.gov (United States)

    Gusev, A. I.; Kozyrev, N. A.; Usoltsev, A. A.; Kryukov, R. E.; Osetkovsky, I. V.

    2017-09-01

    The effect of the introduction of vanadium and cobalt into the charge of the powder surfacing wire of Fe-C-Si-Mn-Cr-Mo-Ni system is studied. In the laboratory conditions, the samples of flux cored wires were produced. The surfacing made by the prepared wire was produced under the flux AN-26C, on the plates of steel St3 in 6 layers with the help of ASAW-1250 welding tractor. Reduction of carbon content in the deposited layer to 0.19-0.2% with simultaneous change in the content of chromium, nickel, molybdenum and other elements present in it contributes to the enlargement of the martensite needles and the increase in the size of the former austenite grain. The obtained dependences of hardness of the deposited layer and its wear resistance on the mass fraction of elements, included in the composition of powder wires of the proposed system, can be used to predict the hardness of the welded layer and its wear resistance under different operating conditions for mining equipment and coal mining equipment.

  15. SCC investigation of low alloy ultra-high strength steel 30CrMnSiNi2A in 3.5wt%NaCl solution by slow strain rate technique

    Institute of Scientific and Technical Information of China (English)

    Liu Jianhua; Guo Qiang; Yu Mei; Li Songmei

    2014-01-01

    To evaluate stress corrosion cracking (SCC) mechanism of low alloy ultra-high strength steel 30CrMnSiNi2A in environment containing NaCl, SCC behavior of the steel in 3.5wt%NaCl solution is investigated by slow strain rate technique (SSRT) with various strain rates and applied potentials, surface analysis technique, and electrochemical measurements. SCC susceptibility of the steel increases rapidly with strain rate decreasing from 1 · 10?5 s?1 to 5 · 10?7 s?1, and becomes stable when strain rate is lower than 5 · 10?7 s?1. SCC propagation of the steel in the solution at open circuit potential (OCP) needs sufficient hydrogen which is supplied at a certain strain rate. Fracture surface at OCP has similar characteristics with that at cathodic polarization ?1000 mVSCE, which presents characteristic fractography of hydrogen induced cracking (HIC). All of these indicate that SCC behavior of the steel in the solution at OCP is mainly controlled by HIC rather than anodic dissolution (AD).

  16. Effect of heat treatment on the structure and hardness of high-entropy alloys CoCrFeNiMnV x ( x = 0.25, 0.5, 0.75, 1)

    Science.gov (United States)

    Shaysultanov, D. G.; Stepanov, N. D.; Salishchev, G. A.; Tikhonovsky, M. A.

    2017-06-01

    High-entropy alloys CoCrFeNiMnVKharkov Institute of Physics and Technology, ul. Akademicheskaya 1, Kharkov 61108 (Kharkov Institute of Physics and Technology, ul. Akademicheskaya 1, Kharkov 61108 = 0.25, 0.5, 0.75, 1) were prepared by vacuum arc melting. The structure and microhardness of the alloys have been studied in the cast state and after annealing at temperatures of 700-1100°C. It has been found that the alloys consist of the fcc (γ) solid solution and intermetallic sigma (σ) phase. The volume fraction of the σ phase increases with increasing vanadium content. As a result of annealing, phase transformations occur, including the precipitation of σ particles from the γ phase and, vice versa, the precipitation of γ particles from the σ phase. It has been shown that the change in the volume fraction of the σ phase upon annealing occurs due to the changes in the total content of σ-forming elements, chromium and vanadium, in accordance with the lever rule. With increasing temperature, the volume fraction of the σ phase varies nonmonotonically; first, it increases, then it decreases. The microhardness of the alloys correlates well with the change in the volume fraction of the σ phase. The mechanisms of the phase transformations and quantitative relationships between chemical and phase compositions of the alloys and their hardness are discussed.

  17. Statistical theory of diffusion in concentrated bcc and fcc alloys and concentration dependencies of diffusion coefficients in bcc alloys FeCu, FeMn, FeNi, and FeCr

    Energy Technology Data Exchange (ETDEWEB)

    Vaks, V. G.; Khromov, K. Yu., E-mail: khromov-ky@nrcki.ru; Pankratov, I. R. [National Research Center “Kurchatov Institute,” (Russian Federation); Popov, V. V. [Russian Academy of Sciences, Mikheev Institute of Metal Physics, Ural Branch (Russian Federation)

    2016-07-15

    The statistical theory of diffusion in concentrated bcc and fcc alloys with arbitrary pairwise interatomic interactions based on the master equation approach is developed. Vacancy–atom correlations are described using both the second-shell-jump and the nearest-neighbor-jump approximations which are shown to be usually sufficiently accurate. General expressions for Onsager coefficients in terms of microscopic interatomic interactions and some statistical averages are given. Both the analytical kinetic mean-field and the Monte Carlo methods for finding these averages are described. The theory developed is used to describe sharp concentration dependencies of diffusion coefficients in several iron-based alloy systems. For the bcc alloys FeCu, FeMn, and FeNi, we predict the notable increase of the iron self-diffusion coefficient with solute concentration c, up to several times, even though values of c possible for these alloys do not exceed some percent. For the bcc alloys FeCr at high temperatures T ≳ 1400 K, we show that the very strong and peculiar concentration dependencies of both tracer and chemical diffusion coefficients observed in these alloys can be naturally explained by the theory, without invoking exotic models discussed earlier.

  18. SCC investigation of low alloy ultra-high strength steel 30CrMnSiNi2A in 3.5wt% NaCl solution by slow strain rate technique

    Directory of Open Access Journals (Sweden)

    Liu Jianhua

    2014-10-01

    Full Text Available To evaluate stress corrosion cracking (SCC mechanism of low alloy ultra-high strength steel 30CrMnSiNi2A in environment containing NaCl, SCC behavior of the steel in 3.5wt% NaCl solution is investigated by slow strain rate technique (SSRT with various strain rates and applied potentials, surface analysis technique, and electrochemical measurements. SCC susceptibility of the steel increases rapidly with strain rate decreasing from 1 × 10−5 s−1 to 5 × 10−7 s−1, and becomes stable when strain rate is lower than 5 × 10−7 s−1. SCC propagation of the steel in the solution at open circuit potential (OCP needs sufficient hydrogen which is supplied at a certain strain rate. Fracture surface at OCP has similar characteristics with that at cathodic polarization −1000 mVSCE, which presents characteristic fractography of hydrogen induced cracking (HIC. All of these indicate that SCC behavior of the steel in the solution at OCP is mainly controlled by HIC rather than anodic dissolution (AD.

  19. EPR spectroscopy of a family of Cr(III) 7M(II) (M = Cd, Zn, Mn, Ni) "wheels": studies of isostructural compounds with different spin ground states

    DEFF Research Database (Denmark)

    Piligkos, Stergios; Weihe, Høgni; Bill, Eckhard

    2009-01-01

    Spinning wheels: The presented highly resolved multifrequency continuous wave EPR spectra (e.g., see figure) of the heterooctametalic "wheels" Cr(7)M provide rare examples of high nuclearity polymetallic systems where detailed information on the spin-Hamiltonian parameters of the ground and excited...... examples of high nuclearity polymetallic systems where detailed information on the spin-Hamiltonian parameters of the ground and excited spin states is observed. We interpret the EPR spectra by use of restricted size effective subspaces obtained by the rigorous solution of spin-Hamiltonians of dimension up...... to 10(5) by use of the Davidson algorithm. We show that transferability of spin-Hamiltonian parameters across complexes of the Cr(7)M family is possible and that the spin-Hamiltonian parameters of Cr(7)M do not have sharply defined values, but are rather distributed around a mean value....

  20. Experimental Study on Edge-cracking in Austenitic Stainless Steel Cr15Mn9Cu2NiN during Hot Rolling%奥氏体不锈钢热轧边裂实验研究

    Institute of Scientific and Technical Information of China (English)

    朱亮; 魏鹏; 侯国清; 苏婷婷

    2012-01-01

    Austenitic stainless steel Crl5Mn9Cu2NiN is prone to suffer from edge cracking during hot rolling. Hot rolling test is conducted on an experimental hot rolling device, which is designed cooperate with thermal simulator. Formation mechanism of edge cracks is researched through this test. The resuks show thai, when press quantity reaches to a certain amount, samples will crack on edge at all test temperatures. All the edge cracks propagate along austenitic grain boundaries. In the range of 1000~l 1 50℃ deformation, cracking tendency of samples are severe, which is related to the reduction of ductility in austenitic stainless steel. The characteristic of microstructures in hot rolled specimens is deformation substructures and twins boundaries in coarse grains in this temperature range. But at 1200℃ deformation, the grain size of specimens is smaller, and all substructures and twins boundaries disappear in the grains.%奥氏体不锈钢Cr15Mn9Cu2NiN在热轧过程中容易产生边裂.在热模拟试验机上开发出热轧实验装置,进行热轧实验,分析该不锈钢边部裂纹产生的原因.结果表明,压下量达到一定程度时,在所有变形温度下,试样边部均会产生裂纹,裂纹均沿奥氏体晶界扩展.在1000~1150℃变形时裂纹倾向较大,分析认为这与奥氏体不锈钢在此温度区间内的延性下降有关.在该温度区间内,轧后试样的微观组织具有晶粒租大和晶粒内部变形亚结构与孪晶共同存在的特征,而在1200℃变形时,晶粒尺寸较小,晶粒内部的变形亚结构和孪晶全部消失.

  1. 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.

  2. Thermodynamic Modeling of the Al-Cr-Mn Ternary System

    Science.gov (United States)

    Cui, Senlin; Jung, In-Ho

    2017-03-01

    The phase diagram information available in the literature on the Al-Cr-Mn system was comprehensively evaluated and optimized for the first time to obtain a set of Gibbs energies of all the solid and liquid phases in the Al-Cr-Mn system. The Modified Quasi-chemical Model (MQM) was utilized to describe the Gibbs energy of the liquid phase of the Al-Cr-Mn system. The Compound Energy Formalism (CEF) was used to model the solid solution phases. A revision of the Al-Mn system was simultaneously conducted to consider the γ_H (Al8Mn5) phase. The liquid Cr-Mn phase was also remodeled using the Modified Quasi-chemical Model (MQM) to obtain a consistent description of the ternary Al-Cr-Mn liquid phase. Accurate description of the phase diagram of the entire Al-Cr-Mn system was obtained from the thermodynamic models with optimized parameters in the present study, and the model parameters can be used to predict the thermodynamic properties of the ternary system.

  3. Magnetic and charge ordering properties of Bi{sub 0.2}Ca{sub 0.8}Mn{sub 0.9}X{sub 0.1}O{sub 3} (where X = Ti, Cr, Fe, Co, Ni, Cu)

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Kamlesh [Department of Physics, Indian Institute of Technology Roorkee, Roorkee 247667 (India); Vaithyanathan, V.; Inbanathan, S.S.R. [Post Graduate and Research Department of Physics, The American College, Madurai 625002 (India); Varma, G.D., E-mail: gdvarfph@iitr.ernet.in [Department of Physics, Indian Institute of Technology Roorkee, Roorkee 247667 (India)

    2012-08-25

    Highlights: Black-Right-Pointing-Pointer Structural, magnetic and transport properties of Bi{sub 0.2}Ca{sub 0.8}Mn{sub 0.9}X{sub 0.1}O{sub 3} (where X = Ti, Cr, Fe, Co, Ni, Cu) have been studied. Black-Right-Pointing-Pointer T{sub CO} decreases by {approx}10 K and {approx}33 K, in Ni{sup 2+} and Cu{sup 2+} doped samples, while it increases by 42 K in Ti{sup 4+} doped sample. Black-Right-Pointing-Pointer In case of Fe{sup 3+}, Co{sup 3+} and Cr{sup 3+} doped samples charge-ordering (CO) completely disappears. Black-Right-Pointing-Pointer Furthermore, the enhancement in resistivity in all the doped samples with respect to undoped one has been observed. Black-Right-Pointing-Pointer The magnetic exchange interactions between Mn and doped ions explain magnetic and electrical properties. - Abstract: Structural, magnetic and transport properties of Bi{sub 0.2}Ca{sub 0.8}Mn{sub 0.9}X{sub 0.1}O{sub 3} (where X = Ti, Cr, Fe, Co, Ni, Cu) have been investigated. The parent sample Bi{sub 0.2}Ca{sub 0.8}MnO{sub 3} (BCMO) exhibits robust charge-ordered antiferrromagnetic (COAFM) phase with charge ordering temperature (T{sub CO}) {approx}155 K and AFM Neel temperature (T{sub N}) {approx}105 K. T{sub CO} decreases by {approx}10 K and {approx}33 K, respectively, in Ni{sup 2+} and Cu{sup 2+} doped samples, while it increases by 42 K in Ti{sup 4+} doped sample. In case of Fe{sup 3+}, Co{sup 3+} and Cr{sup 3+} doped samples charge-ordering (CO) completely melts. The paramagnetic (PM) to ferromagnetic (FM) transition temperatures (T{sub C}) of doped samples have lower values as compared to undoped one. In addition, a spin glass (SG) state is observed in all the samples and the magnetic state at T < T{sub C} is akin to a cluster glass (CG) for undoped and Ni, Cu, Ti doped samples formed due to the presence of FM clusters in COAFM matrix. Furthermore, the enhancement in resistivity in all the doped samples with respect to undoped one has been observed. Based on the present study it has

  4. High temperature wear performance of HVOF-sprayed Cr3C2-WC-NiCoCrMo and Cr3C2-NiCr hardmetal coatings

    Science.gov (United States)

    Zhou, Wuxi; Zhou, Kesong; Li, Yuxi; Deng, Chunming; Zeng, Keli

    2017-09-01

    A novel Cr3C2-WC-NiCoCrMo and commercial Cr3C2-NiCr thermal spray-grade powders with particle size of -45 + 15 μm were prepared by an agglomeration and sintering process. Cr3C2-WC-NiCoCrMo and Cr3C2-NiCr coatings were deposited by high velocity oxygen fuel (HVOF) spraying. The fundamental properties of both coatings were evaluated and friction wear test against Al2O3 counterbodies of both coatings at high temperatures (450 °C, 550 °C, 650 °C) were carried out ball-on-disk high temperature tribometer. All specimens were characterized by optical microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS) and 3D non-contact surface mapping profiler. The results have shown that the Cr3C2-WC-NiCoCrMo coating exhibited lower porosity, higher micro-hardness compared to the Cr3C2-NiCr coating. The Cr3C2-WC-NiCoCrMo coating also exhibited better wear resistance and higher friction coefficient compared to the Cr3C2-NiCr coating when sliding against the Al2O3 counterpart. Wear rates of both coatings increased with raising temperature. Both coatings experienced abrasive wear; hard phase particles (WC and Cr3C2) with different sizes, distributed in the matrix phase, will effectively improve the resistance against wear at high temperatures.

  5. Austenite Formation from Martensite in a 13Cr6Ni2Mo Supermartensitic Stainless Steel

    OpenAIRE

    2016-01-01

    The influence of austenitization treatment of a 13Cr6Ni2Mo supermartensitic stainless steel (X2CrNiMoV13-5-2) on austenite formation during reheating and on the fraction of austenite retained after tempering treatment is measured and analyzed. The results show the formation of austenite in two stages. This is probably due to inhomogeneous distribution of the austenite-stabilizing elements Ni and Mn, resulting from their slow diffusion from martensite into austenite and carbide and nitride dis...

  6. 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.)

  7. Microstructural characterization of a Zr-Ti-Ni-Mn-V-Cr based AB2-type battery alloy

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Zhan [Iowa State Univ., Ames, IA (United States)

    1999-01-01

    Transmission Electron Microscopy (TEM), combined with X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) was employed to investigate a proprietary and multicomponent AB2 type Nickel-Metal Hydride (Ni-MH) battery alloy. This material was prepared by High Pressure Gas Atomization (HPGA) and examined in both the as-atomized and heat treated condition. TEM examination showed a heavily faulted dendritic growth structure in as-atomized powder. Selected Area Diffraction (SAD) showed that this region consisted of both a cubic C15 structure with lattice constant a=7.03 and a hexagonal C14 structure with lattice parameter a=4.97 Å, c=8.11 Å. The Orientation Relationship (OR) between the C14 and C15 structures was determined to be (111)[1$\\bar{1}$0]C15//(0001)[11$\\bar{2}$0]C14. An interdendritic phase possessing the C14 structure was also seen. There was also a very fine grain region consisting of the C14 structure. Upon heat treatment, the faulted structure became more defined and appeared as intercalation layers within the grains. Spherical particles rich in Zr and Ni appeared scattered at the grain boundaries instead of the C14 interdendritic phase. The polycrystalline region also changed to a mixture of C14 and C15 structures. These results as well as phase stability of the C15 and C14 structures based on a consideration of atomic size factor and the average electron concentration are discussed.

  8. Cavitation Erosion Behavior of CrMnN Duplex Stainless Steel in Distilled Water and 3% NaCl Solution

    Institute of Scientific and Technical Information of China (English)

    Suzhen LUO; Yugui ZHENG; Wei LIU; Heming JING; Zhiming YAO; Wei KE

    2003-01-01

    The cavitation erosion (CE) behavior of CrMnN ferrite-austenite duplex stainless steel in distilled water and 3% NaCl solution was investigated by using a magnetostrictive-induced CE facility. The damaged surfaces were observed by scanning electron microscope (SEM). It was found that the CE resistance of CrMnN steel was higher than that of 0Cr13Ni5Mo steel. The mass loss rate of CrMnN steel in distilled water was similar to that in 3% NaCl except at the early stage of CE. The failure mode of ferrite phase was brittle fracture, which had adverse effect on the resistance to CE, while the failure of austenite phase was a ductile failure in CrMnN steel. The excellent resistance to CE was related to the good mechanical properties of austenitic phase and the consumption of CE energy by plastic deformation involving slip and twinning.

  9. The formation model of Ni-Cr oxides on NiCoCrAlY-sprayed coating

    Energy Technology Data Exchange (ETDEWEB)

    Liang, G.Y., E-mail: gyliang@mail.xjtu.edu.cn [Department of Material Physics, MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Science, Xi' an Jiaotong University, Xi' an 710049 (China); Zhu, C.; Wu, X.Y.; Wu, Y. [Department of Material Physics, MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Science, Xi' an Jiaotong University, Xi' an 710049 (China)

    2011-05-15

    The atomic arrangement and distribution of oxides (Cr{sub 2}O{sub 3}, NiCr{sub 2}O{sub 4} and NiO) on the sprayed-NiCoCrAlY coating after oxidation are analyzed. The formation and the growth model of Ni-Cr oxide phases are discussed according to the matching relationship between atoms. The outline character and a scale of spinel NiCr{sub 2}O{sub 4} are discussed. The results show that Cr atoms can form two close-packed arrangements in the crystal plane of Cr{sub 2}O{sub 3} perpendicular to <0 0 1> orientation. The atomic spacing in the first arrangement corresponds to double that of Ni/Ni{sub 3}Al in {l_brace}1 1 1{r_brace} crystal face. This suggests that Ni/Ni{sub 3}Al is the substrate for Cr{sub 2}O{sub 3} to grow along <0 0 1> direction. The lattice mismatch between Cr{sub 2}O{sub 3} and Ni/Ni{sub 3}Al is less than that of Al{sub 2}O{sub 3}, which indicates that Cr{sub 2}O{sub 3} is easier to form than Al{sub 2}O{sub 3} during the oxidation process. The atomic spacing in another close-packed arrangement of Cr{sub 2}O{sub 3} perpendicular to <0 0 1> orientation is approximately equal to that of Ni or Cr in the plane of NiCr{sub 2}O{sub 4} and NiO perpendicular to <1 1 1> orientation. So Cr{sub 2}O{sub 3} can be the substrate for NiCr{sub 2}O{sub 4} and NiO to grow in the <0 0 1> direction. NiCr{sub 2}O{sub 4} and NiO can grow directly along the <1 1 1> orientation on each other. NiCr{sub 2}O{sub 4} can grow outward in the planes of Cr{sub 2}O{sub 3} perpendicular to <0 0 1> and grow inward along <1 1 1> orientation of NiO.

  10. Creep behavior of plasma sprayed NiCr and NiCrAl coating-based systems

    Institute of Scientific and Technical Information of China (English)

    Xiancheng ZHANG; Changjun LIU; Fuzhen XUAN; Zhengdong WANG; Shan-Tung TU

    2011-01-01

    The creep behavior of the plasma sprayed NiCr and NiCrAl coating/Nickel alloy 690substrate systems at 1033 K was investigated. Results showed that there was almost no difference in the creep lives between the NiCr and NiCrAl coated specimens at a given stress level, since the contents of Cr used in the NiCr and NiCrAl powders are almost same. The relationship between the minimum creep rate and the applied stress followed the well-known Norton's power law, εmin=Aσn, with the values of A=2.66× 10-16 Mpa-n.h-1 and n=6.48. The relation between the applied stress and time to rupture of the coated specimens can be estimated by using Larson-Miller equation. The θ projection method can be used to accurately characterize the creep behavior of the coated specimens.

  11. Influence of Heat-treatment on Shape Memory Effect of FeMnSiCrNi Alloy Locknut Component%热处理对FeMnSiCrNi合金防松螺母形状记忆效应的影响

    Institute of Scientific and Technical Information of China (English)

    杜彦良; 李俊良; 沈英明

    2005-01-01

    研究了固溶处理工艺、预应变大小和恢复退火温度对FeMnSiCrNi合金螺母形状记忆效应的影响规律.结果表明:对于这种螺母,最佳的固溶处理温度为950℃,最适当的预应变为5%,恢复处理温度不超过400℃.

  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. Inlfuence of carbon content on microstructure and mechanical properties of Mn13Cr2 and Mn18Cr2 cast steels

    Institute of Scientific and Technical Information of China (English)

    Lu Dingshan; Liu Zhongyi; Li Wei

    2014-01-01

    In this paper, a comparison study was carried out to investigate the inlfuence of carbon content on the microstructure, hardness, and impact toughness of water-quenched Mn13Cr2 and Mn18Cr2 cast steels. The study results indicate that both steels' water-quenched microstructures are composed of austenite and a smal amount of carbide. The study also found that, when the carbon contents are the same, there is less carbide in Mn18Cr2 steel than in Mn13Cr2 steel. Therefore, the hardness of Mn18Cr2 steel is lower than that of Mn13Cr2 steel but the impact toughness of Mn18Cr2 steel is higher than that of Mn13Cr2 steel. With increasing the carbon content, the hardness increases and the impact toughness decreases in these two kinds of steels, and the impact toughness of Mn18Cr2 steel substantialy exceeds that of Mn13Cr2 steel. Therefore, the water-quenched Mn18Cr2 steel with high carbon content could be applied to relatively high impact abrasive working conditions, while the as-cast Mn18Cr2 steel could be only used under working conditions of relatively low impact abrasive load due to lower impact toughness.

  14. 热-机械训练对Fe-20Mn-5Si-5Cr-3Ni形状记忆合金性能的影响%Effect of Thermal-mechanical Cycle Training on Properties of Fe-20Mn-5Si-5Cr-3Ni Shape Memory Alloy

    Institute of Scientific and Technical Information of China (English)

    程晓敏; 胡胜; 吴兴文; 周小芳

    2008-01-01

    研究了热-机械训练对Fe-20Mn-5Si-5Cr-3Ni合金形状记忆效应(SME)的影响,对合金在HCI、NaOH和NaC1溶液中的耐腐蚀性进行了实验研究.结果表明,热-机械训练能够有效提高合金的形状回复率,在600℃进行中间退火,形状回复率较好;热-机械训练次数为3次时,形状回复率达到最大值(98%).Fe-20Mn-5Si-5Cr-3Ni合金的耐腐蚀性在NaOH溶液中较好,在NaC1溶液中次之,在HC1溶液中较差.

  15. Atomic site occupation determined by magnetism in the Heusler alloy Mn{sub 2}CoGa doped with Cr

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y.J. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300401 (China); Li, G.J.; Liu, E.K.; Chen, J.L.; Wang, W.H. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Meng, F.B. [School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300401 (China); Wu, G.H., E-mail: ghwu@aphy.iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-12-01

    The atomic configuration and magnetic properties of Mn{sub 2}CoM{sub x}Ga{sub 1−x} (M=Cr and Ni) Heusler alloys have been investigated by experiments and calculations. Doping with Ni leads to a magnetic moment change of 5.92 μ{sub B}/atom, giving rise to a local FM structure in the ferrimagnetic matrix. On the other hand, a moment change of 3.61 μ{sub B}/atom is experimentally observed in Cr-doped alloys, which is very large compared with the atomic moment of about 2 μ{sub B}/Cr atom in other Heusler alloys. Electronic-structure calculations are presented which indicate that, in contrast with Ni-doped alloys, the magnetism favors the doped Cr atoms to occupy unusual atomic sites. This is opposite to the effect of the covalent bonding in Ni-doped alloys and disobeys the empirical site-occupation rule for Heusler alloys. Due to the difference in electronegativity of the dopants, the covalent bonding in Mn{sub 2}CoGa doped with Ti, V and Cr is weaker than in alloys doped with Fe, Co and Ni. Because Cr has a higher magnetic moment than Ti and V, the magnetism determines, in this weak-covalent environment, an atomic site occupation by Cr which does not obey the empirical rule. This provides clear evidence for the impact of magnetism on the crystalline structure of Heusler alloys.

  16. New quantum tunneling steps in Mn11Cr/Mn12 mixed crystal

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Magnetic properties of Mn11Cr and Mn12 mixed crystal at low temperature are studied.A new set of quantum tunneling steps discovered in magnetization curves suggests that there may exist another kind of single molecular magnet in this mixed crystal.

  17. Electrodeposition of Ni-Cr alloy on aluminum substrate

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Ni-Cr alloys with mass fraction of 1.4%-23.9 %Cr, 76.1%-98.6 % Ni, and hardness of 70.5-80.5HR were electrodeposited on aluminium substrate from the trivalent chromium sulphate-chloride solution using citric acid as complexing agent. The aluminium was pretreated by means of degreasing and eroding, polishing and twice chemicai immersion of zinc. The effects of electrodeposition parameters such as current density, temperature, pH value and bath concentration on the composition and hardness of deposits were investigated. The results show that the Cr content increases with the increase of current density and the decrease of temperature, and that it increases with the increase of pH value to a maximum and then decreases. The increase of Cr content leads to the increase of hardness of the Ni-Cr layers. The deposits with high Cr content are of good corrosion resistance. Good adherence of Ni-Cr deposits to aluminium substrate is obtained. The Ni-Cr alloys are the Ni-Cr solid solution with fcc crystalline structure. The Ni-Cr alloy deposits are fine, bright and smooth and compact.

  18. 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.

  19. 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.

  20. Magnetic and conventional shape memory behavior of Mn-Ni-Sn and Mn-Ni-Sn(Fe) alloys

    Science.gov (United States)

    Turabi, A. S.; Lázpita, P.; Sasmaz, M.; Karaca, H. E.; Chernenko, V. A.

    2016-05-01

    Magnetic and conventional shape memory properties of Mn49Ni42Sn9(at.%) and Mn49Ni39Sn9Fe3(at.%) polycrystalline alloys exhibiting martensitic transformation from ferromagnetic austenite into weakly magnetic martensite are characterized under compressive stress and magnetic field. Magnetization difference between transforming phases drastically increases, while transformation temperature decreases with the addition of Fe. Both Mn49Ni42Sn9 and Mn49Ni39Sn9Fe3 alloys show remarkable superelastic and shape memory properties with recoverable strain of 4% and 3.5% under compression at room temperature, respectively. These characteristics can be counted as extraordinary among the polycrystalline NiMn-based magnetic shape memory alloys. Critical stress for phase transformation was increased by 34 MPa in Mn49Ni39Sn9Fe3 and 21 MPa in Mn49Ni42Sn9 at 9 T, which can be qualitatively understood in terms of thermodynamic Clausius-Clapeyron relationships and in the framework of the suggested physical concept of a volume magnetostress.

  1. Synthesis of high-voltage cathode material LiCr0.2Ni0.4Mn1.4O4 by solid method%固相法合成高电压正极材料镍铬锰酸锂

    Institute of Scientific and Technical Information of China (English)

    李渊; 刘恒; 徐艺林; 王巍

    2012-01-01

    5V尖晶石型LiNi0.5Mn15.O4以其高能量密度、价格低廉、无环境污染等特点被视为最具发展潜力的锂离子电池正极材料之一.分别采用蔗糖、葡萄糖、柠檬酸3种不同碳源,通过固相混合、掺铬、球磨、高温煅烧制备出镍铬锰酸锂.通过XRD、SEM、粒度测量和电池充放电性能测试,对样品的结构、形貌、粒径、粒径分布及电性能等进行了分析.结果表明,加柠檬酸可制得粒径更细、粒径分布更窄的亚微米级的尖晶石型LiCr0.2Ni0.4Mn1.4O4,且其具有更好的电化学性能,在3.4~5.2V、1C下放电比容量可达149 mA·h/g,循环100次后容量保持率为98.0%.%5 V spinel LiNi0.5Mn1.5O4 is one of the most potential cathode materials for lithium-ion batteries because of its advantages of high energy density, low cost, and no pollution to the environment etc.Different carbon sources, such as sucrose, glucose,and citric acid,were adopted respectively as first,and then LiCr0.2Ni0.4Mn1.4O4 was prepared by solid mixture,doping chromium,ball milling,and high temperature calcination.Structure, morphology, particle size,particle size distribution,and electrical performance of the samples were analyzed by XRD, EM, particle size measurement and constant current charge-discharge cycling test.Results showed that submicron spinel LiCr0.2Ni0.4Mn1.4O4 with thinner particle size, narrower size distribution , and better electrical performance was obtained when glucose was added.Specific capacity of LiCr0.2Ni0.4Mn1.4O4 cathode material was 149 mA·h/g charged at 3.4~5.2 V and 1 C and retained 98 % of the initial capacity after 100 cycles.

  2. Effects of Cr and Ni on interdiffusion and reaction between U and Fe-Cr-Ni alloys

    Science.gov (United States)

    Huang, K.; Park, Y.; Zhou, L.; Coffey, K. R.; Sohn, Y. H.; Sencer, B. H.; Kennedy, J. R.

    2014-08-01

    Metallic U-alloy fuel cladded in steel has been examined for high temperature fast reactor technology wherein the fuel cladding chemical interaction is a challenge that requires a fundamental and quantitative understanding. In order to study the fundamental diffusional interactions between U with Fe and the alloying effect of Cr and Ni, solid-to-solid diffusion couples were assembled between pure U and Fe, Fe-15 wt.%Cr or Fe-15 wt.%Cr-15 wt.%Ni alloy, and annealed at high temperature ranging from 580 to 700 °C. The microstructures and concentration profiles that developed from the diffusion anneal were examined by scanning electron microscopy, and X-ray energy dispersive spectroscopy (XEDS), respectively. Thick U6Fe and thin UFe2 phases were observed to develop with solubilities: up to 2.5 at.% Ni in U6(Fe,Ni), up to 20 at.%Cr in U(Fe, Cr)2, and up to 7 at.%Cr and 14 at.% Ni in U(Fe, Cr, Ni)2. The interdiffusion and reactions in the U vs. Fe and U vs. Fe-Cr-Ni exhibited a similar temperature dependence, while the U vs. Fe-Cr diffusion couples, without the presence of Ni, yielded greater activation energy for the growth of intermetallic phases - lower growth rate at lower temperature but higher growth rate at higher temperature.

  3. 新型Cr-Ni-Mo和Cr-Ni-Co堆焊合金空蚀性能%Cavitation Erosion Resistance of Novel Cr-Ni-Mo and Cr-Ni-Co Overlaying Alloys

    Institute of Scientific and Technical Information of China (English)

    徐桂芳; 秦敏明; 雷玉成; 陈希章; 李涛

    2012-01-01

    New type Cr-Ni-Mo and Cr-Ni-Co overlaying alloys were prepared by argon tungsten-arc welding (TIG) on 304 stainless steel, and tested by cavitation vibrating device. The cavitation erosion resistance of alloys was compared through the analysis of mass loss. The alloy layer was analyzed by scanning electron microscopy (SEM), X-ray diffractometer (XRD) and microhardness tester. Results indicate that the cavitation erosion resistance of Cr-Ni-Mo and Cr-Ni-Co overlaying alloys is better than that of 304 stainless steel, and the resistance of Cr-Ni-Co is better than Cr-Ni-Mo. In the process of cavitation the damage is preferred to appear in grain boundary. Phase transformation from austenite to martensite happens in the cavitation process of Cr-Ni-Co alloy, and it is helpful to absorb the energy and delay the process of cavitation erosion, and enhance the cavitation erosion resistance effectively. The cavitation erosion resistance of overlaying alloys is related to hardness and work hardening ability.%采用钨极氩弧焊(TIG)将新型Cr-Ni-Mo和Cr-Ni-Co合金堆焊于304不锈钢表面进行空蚀试验,通过失重比较不同合金的抗空蚀性能.采用扫描电镜(SEM)、X射线衍射(XRD)仪和显微硬度计对合金层进行分析.结果表明:Cr-Ni-Mo和Cr-Ni-Co合金的耐空蚀性能均优越于304不锈钢,其中Cr-Ni-Co优于Cr-Ni-Mo;空蚀破坏优先出现在堆焊层的晶界处;Cr-Ni-Co合金在空蚀过程中发生了因奥氏体向马氏体的转变,有利于能量吸收,延缓了空蚀的进行,提高其耐空蚀性能;堆焊合金的抗空蚀能力与合金本身的硬度和加工硬化能力有关.

  4. Microstructure and mechanical properties of thermal sprayed nanostructured Cr3C2-Ni20Cr coatings

    OpenAIRE

    Cecilio Alvares da Cunha; Nelson Batista de Lima; Jose Roberto Martinelli; Ana Helena de Almeida Bressiani; Armando Guilherme Fernando Padial; Lalgudi Venkataraman Ramanathan

    2008-01-01

    Cr3C2-Ni20Cr coatings have been used for corrosion and wear resistant applications. However, one of the shortcomings of these coatings is its low hardness, and consequent low wear resistance, for long term high temperature applications. Nanostructured coatings of many materials have exhibited higher hardness and strength compared with conventional coatings of the same material. Consequently, nanostructured coatings of other materials, including Cr3C2-Ni20Cr have been attempted to enhance over...

  5. Oxidation Behaviour of Sputtered Ni-3Cr-20Al Alloy

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The oxidation behavior of sputtered Ni-3Cr-20Al coating at 900°C in air was investigated. A dense Al2O3 layer was formed on the sputtered Ni-3Cr-20Al coating after 200 h oxidation.However, owing to the segregation of Ni3Al during oxidation Focess at high temperature, the spinel NiAl2O4 was also formed in the Al2O3 layer. It was found that the formation of NiAl2O4had no detrimental effect on the oxidation resistance of the sputtered Ni-3Cr-20Al coating due to the excellent adhesion shown by the Al2O3 and NiAl2O4 complex oxide scale.

  6. Interatomic potential to study the formation of NiCr clusters in high Cr ferritic steels

    Science.gov (United States)

    Bonny, G.; Bakaev, A.; Olsson, P.; Domain, C.; Zhurkin, E. E.; Posselt, M.

    2017-02-01

    Under irradiation NiSiPCr clusters are formed in high-Cr ferritic martensitic steels as well as in FeCr model alloys. In the literature little is known about the origin and contribution to the hardening of these clusters. In this work we performed density functional theory (DFT) calculations to study the stability of small substitutional NiCr-vacancy clusters and interstitial configurations in bcc Fe. Based on DFT data and experimental considerations a ternary potential for the ferritic FeNiCr system was developed. The potential was applied to study the thermodynamic stability of NiCr clusters by means of Metropolis Monte Carlo (MMC) simulations. The results of our simulations show that Cr and Ni precipitate as separate fractions and suggest only a limited synergetic effect between Ni and Cr. Therefore our results suggest that the NiCrSiP clusters observed in experiments must be the result of other mechanisms than the synergy of Cr and Ni at thermal equilibrium.

  7. Damping of Ni-Mn-Ga epoxy resin composites

    Institute of Scientific and Technical Information of China (English)

    Wei Liang; He Yu; Liu Yufeng; Yang Naibin

    2013-01-01

    By combining the advantages of efficient damping and high mechanical properties, Ni-Mn-Ga particle composites have a very good prospect for applications in damping structure design. In this paper, a ferromagnetic shape memory alloy Ni-Mn-Ga composite is prepared. Ni-Mn-Ga particle/bisphenol-A epoxy composite cantilever beam vibration tests under a magnetic field and without the magnetic field are conducted to analyze the structural damping ratios n. Meanwhile, the damping characteristics of the Ni-Mn-Ga composite are studied through the axial loading-unloading method and the acoustic emission signals method. The damping coefficient of the composite for different Ni-Mn-Ga volume fractions is obtained. The interface properties of the composite are discussed by micro examination and axial loading. The relationships between the damping of the composite and that of the component materials are discussed. The specific damping capacity (SDC) and acoustic emission counts diagram of different specimens with different Ni-Mn-Ga volume fractions are analyzed.

  8. Photoemission of Mn6Cr single-molecule magnets

    Science.gov (United States)

    Heinzmann, U.; Merschjohann, F.; Helmstedt, A.; Gryzia, A.; Winter, A.; Steppeler, S.; Müller, N.; Brechling, A.; Sacher, M.; Richthofen, C.-G. Freiherr v.; Glaser, T.; Voss, S.; Fonin, M.; Rüdiger, U.

    2009-11-01

    We present the status of new experimental studies of X-ray absorption spectroscopy, magnetic circular dichroism in photoemission and spin-resolved photoelectron spectroscopy of Mn6Cr single-molecule magnet systems by use of circularly-polarized synchrotron radiation of the electron storage rings in Maxlab Lund, Sweden und BESSY, Berlin, Germany.

  9. Effects of Cr and Ni on Interdiffusion and Reaction between U and Fe-Cr-Ni Alloys

    Energy Technology Data Exchange (ETDEWEB)

    K. Huang; Y. Park; L. Zhou; K.R. Coffey; Y.H. Sohn; B.H. Sencer; J. R. Kennedy

    2014-08-01

    Metallic U-alloy fuel cladded in steel has been examined for high temperature fast reactor technology wherein the fuel cladding chemical interaction is a challenge that requires a fundamental and quantitative understanding. In order to study the fundamental diffusional interactions between U with Fe and the alloying effect of Cr and Ni, solid-to-solid diffusion couples were assembled between pure U and Fe, Fe–15 wt.%Cr or Fe–15 wt.%Cr–15 wt.%Ni alloy, and annealed at high temperature ranging from 580 to 700 °C. The microstructures and concentration profiles that developed from the diffusion anneal were examined by scanning electron microscopy, and X-ray energy dispersive spectroscopy (XEDS), respectively. Thick U6Fe and thin UFe2 phases were observed to develop with solubilities: up to 2.5 at.% Ni in U6(Fe,Ni), up to 20 at.%Cr in U(Fe, Cr)2, and up to 7 at.%Cr and 14 at.% Ni in U(Fe, Cr, Ni)2. The interdiffusion and reactions in the U vs. Fe and U vs. Fe–Cr–Ni exhibited a similar temperature dependence, while the U vs. Fe–Cr diffusion couples, without the presence of Ni, yielded greater activation energy for the growth of intermetallic phases – lower growth rate at lower temperature but higher growth rate at higher temperature.

  10. Chemical zoning and diffusion of Ca, Al, Mn, and Cr in olivine of springwater pallasite

    Science.gov (United States)

    Zhou, Y.; Steele, Ian M.

    1993-01-01

    The pallasites, consisting mainly of Fe-Ni metal and olivine, are thought to represent the interior of a planetary body which slowly cooled from high temperature. Although the olivines are nearly homogeneous, ion microprobe studies revealed variations of Ca, Ti, Co, Cr, and Ni near grain edges. These variations were thought to represent diffusion in response to falling temperature of the parent body. Pallasite cooling rates have been estimated based on kamacite taenite textures but results differ by x100. In principle elemental profiles in olivine can allow estimates of cooling rate if diffusion coefficients are known; in addition, given a cooling rate, diffusion coefficients could be derived. Data are presented which show that apparent diffusion profiles can be measured for Al, Ca, Cr, and Mn which qualitatively agree with expected diffusion rates and have the potential of providing independent estimates of pallasite cooling rates.

  11. Electroplating process of amorphous Fe-Ni-Cr alloy

    Institute of Scientific and Technical Information of China (English)

    何湘柱; 夏畅斌; 王红军; 龚竹清; 蒋汉瀛

    2001-01-01

    A novel process of electroplating amorphous Fe-Cr-Ni alloy in chloride aqueous solution with Fe( Ⅱ ), Ni ( lⅡ ) and Cr( Ⅲ ) was reported. Couple plasma atomic emission spectrometry (ICP-AES), X-ray diffractometry(XRD),scanning electronic microscopy(SEM), microhardness test and rapid heating-cooling method were adopted to detect the properties of the amorphous Fe-Ni-Cr deposit, such as composition, crystalline structure, micrograph, hardness, and adherence between deposit and substrate. The effects of the operating parameters on the electrodeposit of the amorphous FeNi-Cr alloy were discussed in detail. The results show that a 8.7 μm thick mirror-like amorphous Fe-Ni-Cr alloy deposit,with Vicker's hardness of 530 and composition of 45%~55% Fe, 33%~37% Ni, 9%~23% Cr was obtained by electroplating for 20 min at room temperature( 10 30 C ), cathode current 10~16 A/dm2, pH = 1.0~3.0. The XRD pat terns show that there only appears a broad hump around 2θ of 41 °~47 °for the amorphous Fe-Ni-Cr alloy deposit, while the SEM micrographs show that the deposit contains only a few fine cracks but no pinholes.

  12. 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.

  13. Magnetic interactions in martensitic Ni-Mn based Heusler systems

    Energy Technology Data Exchange (ETDEWEB)

    Aksoy, Seda

    2010-04-22

    In this work, magnetic, magnetocaloric and structural properties are investigated in Ni-Mn-based martensitic Heusler alloys with the aim to tailor these properties as well as to understand in detail the magnetic interactions in the various crystallographic states of these alloys. We choose Ni{sub 50}Mn{sub 34}In{sub 16} as a prototype which undergoes a martensitic transformation and exhibits field-induced strain and the inverse magnetocaloric effect. Using the structural phase diagram of martensitic Ni-Mn-based Heusler alloys, we substitute gallium and tin for indium to carry these effects systematically closer to room temperature by shifting the martensitic transformation. A magneto-calorimeter is designed and built to measure adiabatically the magnetocaloric effect in these alloys. The temperature dependence of strain under an external magnetic field is studied in Ni{sub 50}Mn{sub 50-x}Z{sub x} (Z: Ga, Sn, In and Sb) and Ni{sub 50}Mn{sub 34}In{sub 16-x}Z{sub x} (Z: Ga and Sn). An argument based on the effect of the applied magnetic field on martensite nucleation is adopted to extract information on the direction of the magnetization easy axis in the martensitic unit cell in Heusler alloys. Parallel to these studies, the structure in the presence of an external field is also studied by powder neutron diffraction. It is demonstrated that martensite nucleation is influenced by cooling the sample under a magnetic field such that the austenite phase is arrested within the martensitic state. The magnetic interactions in Ni{sub 50}Mn{sub 37}Sn{sub 13} and Ni{sub 50}Mn{sub 40}Sb{sub 10} are characterized by using neutron polarization analysis. Below the martensitic transformation temperature, M{sub s}, an antiferromagnetically correlated state is found. Ferromagnetic resonance experiments are carried out on Ni{sub 50}Mn{sub 37}Sn{sub 13} and Ni{sub 50}Mn{sub 34}In{sub 16} to gain more detailed information on the nature of the magnetic interactions. The experimental

  14. Low-cost Fe--Ni--Cr alloys for high temperature valve applications

    Energy Technology Data Exchange (ETDEWEB)

    Muralidharan, Govindarajan

    2017-03-28

    An Fe--Ni--Cr alloy is composed essentially of, in terms of weight percent: 1 to 3.5 Al, up to 2 Co, 15 to 19.5 Cr, up to 2 Cu, 23 to 40 Fe, up to 0.3 Hf, up to 4 Mn, 0.15 to 2 Mo, up to 0.15 Si, up to 1.05 Ta, 2.8 to 4.3 Ti, up to 0.5 W, up to 0.06 Zr, 0.02 to 0.15 C, 0.0001 to 0.007 N, balance Ni, wherein, in terms of atomic percent: 6.5.ltoreq.Al+Ti+Zr+Hf+Ta.ltoreq.10, 0.33.ltoreq.Al/(Al+Ti+Zr+Hf+Ta).ltoreq.0.065, 4.ltoreq.(Fe+Cr)/(Al+Ti+Zr+Hf+Ta).ltoreq.10, the alloy being essentially free of Nb and V.

  15. Effect of Cr doping on structure of LiMnO2

    Institute of Scientific and Technical Information of China (English)

    谷亦杰; 周恒辉; 陈继涛; 常文保

    2003-01-01

    The monoclinic and orthorhombic ordered-rocksalt polymorphs of LiMnO2 are of interest as high-capacity cathode materials for rechargeable Li batteries. LiMnO2 and LiMn1-xCrxO2 were prepared by a high temperature solid-state route. In comparison with undoping Cr orthorhombic LiMnO2, monoclinic LiMnO2 was preserved with Cr doping. The volume of m-LiMnO2 decreasing with increasing Cr confirms that the length of bond around Cr ion decreases with Mn substituted by Cr ion. A phase transformation mechanism was proposed for understanding the structure relationship between the LiMnO2 and chromium-substituted LiMnO2 oxides.

  16. Effect of Cr content on mechanical and electrical properties of Ni-Cr thin films

    Energy Technology Data Exchange (ETDEWEB)

    Danisman, M., E-mail: muratdan@gmail.co [Yildiz Technical University, Faculty of Chemistry-Metallurgy, Metallurgical and Materials Engineering Department, Esenler 34220, Istanbul (Turkey); Cansever, N. [Yildiz Technical University, Faculty of Chemistry-Metallurgy, Metallurgical and Materials Engineering Department, Esenler 34220, Istanbul (Turkey)

    2010-03-18

    NiCr has been a popular choice for strain gage and electrical resistance application in various fields of engineering and science. Therefore, the phases at this binary system have been thoroughly investigated in the last decade. For Ni-Cr thin film production, sputtering from alloy targets is mostly discussed as a deposition method. However, Cr content in Ni-Cr alloy has major influence on different properties of the NiCr thin films. In order to investigate the effect of Cr content in Ni-Cr system, Ni over Cr thin films with a total thickness of 500 nm was deposited on glass substrates with different Cr/Ni thickness ratios as 0.1, 0.25 and 0.6. After deposition, thin films were annealed at 600 {sup o}C for 180 s in a Rapid Thermal Process (RTP) system to investigate the effect of different Cr contents on phase formation. The phase formations and lattice parameters were analyzed with low glancing angle X-ray Diffraction (XRD) and the Cr content in the thermally treated thin films was calculated with Energy Dispersive Spectrometry (EDS). Also, film composition along depth was also calculated by EDS analysis from the cross-section view of the annealed samples. Field Emission Scanning Electron Microscope (FESEM) images were taken from the cross-section view of the samples in order to observe the final film thicknesses and structures. Sheet resistance of each sample was measured with linear four point probe technique and resistivity of each phase was calculated. Furthermore, nanohardness and Young's Modulus of each sample was calculated by using nanoindentation method.

  17. Composite Ni/NiO-Cr2O3 Catalyst for Alkaline Hydrogen Evolution Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Bates, MK; Jia, QY; Ramaswamy, N; Allen, RJ; Mukerjee, S

    2015-03-12

    We report a Ni-Cr/C electrocatalyst with unpreeedented massactivity for the hydrogen evolution reaction (HER). in alkaline electrolyte. The HER Oietics of numerous binary and ternary Ni-alloys and composite Ni/metal-euride/C samples were evaluated in aquebus 0.1 M KOH electrolyte. The highest HER mass-activity was observed for Ni-Cr materials which exhibit metallic Ni as well as NiOx and Cr2O3 phases as determined by X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) analysis. The onset of the HER is significantly improved compared to munerous binary dor ternary Ni-alloys, inCluding Ni Mg materials. It is likely that at adjacent Ni/NiOx sites, the oxide acts as a sink for OHads, while the metallic Ni acts as a, sink for the H-ads, intermediate of the HER, thus minimizing the high activation energy of hydrogen evolution via water reduction. This is confirmed by in situ XAS studies that show that the synergistic HER enhancement is due to NiO content and that the Cr2O3 appears to stabilize the composite NiO component-under HER conditions (where NiOx would typically be reduced to metallic Ni-0). Furthermore, in contrast to Pt, the Ni(O-x)/Cr2O3 catalyst appears resistant to poisoning by the anion.exchange ionomer (AEI), a serloua consideration when applied to an anionic polymer electrolyte interface. Furthermore, we report a: detailed model of the double layer interface which helps explain the observed ensemble effect in the presence of AEI.

  18. CASSCF/CI calculations for first row transition metal hydrides - The TiH(4-phi), VH(5-delta), CrH(6-sigma-plus), MnH(7-sigma-plus), FeH(4,6-delta) and NiH(2-delta) states

    Science.gov (United States)

    Walch, S. P.; Bauschlicher, C. W., Jr.

    1983-01-01

    Calculations are performed for the predicted ground states of TiH(4-phi), VH(5-delta), CrH(6-sigma-plus), MnH(7-sigma-plus), Fett(4,6-delta) and NiH(2-delta). For FeH both the 6-delta and 4-delta states are studied, since both are likely candidates for the ground state. The ground state symmetries are predicted based on a combination of atomic coupling arguments and coupling of 4s(2)3d(n) and 4s(1)3d(n+1) terms in the molecular system. Electron correlation is included by a CASSCF/CI (SD) treatment. The CASSCF includes near-degeneracy effects, while correlation of the 3d electrons in included at the CI level.

  19. Magnetic properties of Ni(II)-Mn(III) LDHs

    Energy Technology Data Exchange (ETDEWEB)

    Giovannelli, F., E-mail: fabien.giovannelli@univ-tours.fr [LEMA, UMR 6157 CNRS-CEA, Universite Francois Rabelais, 3 place Jean Jaures, 41029 Blois (France); Zaghrioui, M.; Autret-Lambert, C. [LEMA, UMR 6157 CNRS-CEA, Universite Francois Rabelais, 3 place Jean Jaures, 41029 Blois (France); Delorme, F.; Seron, A. [BRGM, 3 Avenue Claude Guillemin, BP 36009, 45060 Orleans Cedex 2 (France); Chartier, T.; Pignon, B. [LEMA, UMR 6157 CNRS-CEA, Universite Francois Rabelais, 3 place Jean Jaures, 41029 Blois (France)

    2012-11-15

    The synthesis of Ni{sub 1-x}Mn{sub x}(OH){sub 2}(CO{sub 3}){sub x/2}{center_dot}nH{sub 2}O Layered Double Hydroxides (LDHs) for x = 0.2, 0.25 and 0.33, their characterisation by electron microscopy, X-ray diffraction and their magnetic properties are reported in this study. When x increases, the crystallinity of the nanoparticles is improved. The low temperature magnetic behaviour of these compounds is characteristic of the competition between in plane ferromagnetic and interlayer antiferromagnetic interactions. The ferromagnetism is due to in plane Ni cations interaction and decreases when manganese content increases (Tc decreases from 26 to 15 K when x increases from 0.2 to 0.33). It was found that the substitution of Ni by Mn ions favours the in plane antiferromagnetic order. This study demonstrates that magnetic interactions occur in LDH with non magnetic interlayer anions. -- Highlights: Black-Right-Pointing-Pointer The synthesis of Ni{sub 1-x}Mn{sub x}(OH){sub 2}(CO{sub 3}){sub x/2}{center_dot}nH{sub 2}O Layered Double Hydroxides have been performed. Black-Right-Pointing-Pointer The low temperature magnetic behaviour of these compounds has been studied. Black-Right-Pointing-Pointer The substitution of Ni by Mn ions favours the in plane antiferromagnetic order.

  20. Electrochemical behavior of Co-Cr and Ni-Cr dental cast alloys

    Institute of Scientific and Technical Information of China (English)

    Viswanathan S. SAJI; Han-Cheol CHOE

    2009-01-01

    The cast structures influencing the electrochemical corrosion behavior of Co-Cr and Ni-Cr dental alloys were studied using potentiodynamic polarization and AC impedance in 0.9% (mass fraction) NaCl solution at (37±1) ℃. The phase and microstructure of the alloys that were fabricated using two different casting methods viz. centrifugal casting and high frequency induction casting, were examined using X-ray diffraction analysis, scanning electron microscopy and energy dispersive spectroscopy. The roles of alloying elements and the passive film homogeneity on the corrosion resistance of Co-Cr-Mo and Ni-Cr-Mo dental cast alloys were reviewed. The results of electrochemical study show that the dependence of corrosion resistance on the microstructure associated with the casting methods is marginal. The Co-Cr alloy exhibits more desirable corrosion resistance properties than the Ni-Cr alloy. There is severe preferential dissolution of Ni-rich, Cr and Mo depleted zones in the Ni-Cr alloy.

  1. Mechanical and Tribological Properties of HVOF-Sprayed (Cr3C2-NiCr+Ni) Composite Coating on Ductile Cast Iron

    Science.gov (United States)

    Ksiazek, Marzanna; Boron, Lukasz; Radecka, Marta; Richert, Maria; Tchorz, Adam

    2016-08-01

    The aim of the investigations was to compare the microstructure, mechanical, and wear properties of Cr3C2-NiCr+Ni and Cr3C2-NiCr coatings deposited by HVOF technique (the high-velocity oxygen fuel spray process) on ductile cast iron. The effect of nickel particles added to the chromium carbide coating on mechanical and wear behavior in the system of Cr 3 C 2 -NiCr+Ni/ductile cast iron was analyzed in order to improve the lifetime of coated materials. The structure with particular emphasis of characteristic of the interface in the system of composite coating (Cr 3 C 2 -NiCr+Ni)/ductile cast iron was studied using the optical, scanning, and transmission electron microscopes, as well as the analysis of chemical and phase composition in microareas. Experimental results show that HVOF-sprayed Cr3C2-NiCr+Ni composite coating exhibits low porosity, high hardness, dense structure with large, partially molten Ni particles and very fine Cr3C2 and Cr7C3 particles embedded in NiCr alloy matrix, coming to the size of nanocrystalline. The results were discussed in reference to examination of bending strength considering cracking and delamination in the system of composite coating (Cr 3 C 2 -NiCr+Ni)/ductile cast iron as well as hardness and wear resistance of the coating. The composite structure of the coating provides the relatively good plasticity of the coating, which in turn has a positive effect on the adhesion of coating to the substrate and cohesion of the composite coating (Cr3C2-NiCr+Ni) in wear conditions.

  2. Effect of Age-Hardening Treatment on Microstructure and Sliding Wear-Resistance Performance of WC/Cu-Ni-Mn Composite Coatings

    Science.gov (United States)

    Liu, Jun; Yang, Shuai; Liu, Kai; Gui, Chibin; Xia, Weisheng

    2017-06-01

    The Cu-Ni-Mn alloy-based hardfacing coatings reinforced by WC particles (WC/Cu-Ni-Mn) were deposited on a steel substrate by a manual oxy-acetylene weld hardfacing method. A sound interfacial junction was formed between the WC particles and the Cu-Ni-Mn alloy metal matrix binder even after the age-hardening treatment. The friction and wear behavior of the hardfacing coatings was investigated. With the introduction of WC particles, the sliding wear resistance of the WC/Cu-Ni-Mn hardfacing coatings was sharply improved: more than 200 times better than that of the age-hardening-treated Cu-Ni-Mn alloy coating. The sliding wear resistances of the as-deposited and the age-hardening-treated WC/Cu-Ni-Mn hardfacing coatings were 1.83 and 2.26 times higher than that of the commercial Fe-Cr-C hardfacing coating, which is mainly ascribed to the higher volume fraction of carbide reinforcement. Owing to the precipitation of the NiMn secondary phase in the Cu-Ni-Mn metal matrix, the age-hardening-treated coating had better wear resistance than that of the as-deposited coating. The main sliding wear mechanisms of the age-hardening-treated coatings are adhesion and abrasion.

  3. Impact strength of GX8CrNi12, GX5CrNi18-9 and GX5CrNiMo19-11-2 cast steel at - 30 °C

    Directory of Open Access Journals (Sweden)

    B. Kalandyk

    2016-10-01

    Full Text Available The results of impact tests carried out at - 30 °C on cast alloyed GX8CrNi12, GX5CrNi18-9 and GX5CrNiMo19-11-2 steel grades are reported. It has been shown that at - 30 °C, the addition of 1 % Ni to cast GX8CrNi12 steel does not provide the required impact strength of 35 J/cm2. In contrast, other tested materials containing 8 ÷ 9 % Ni can easily reach exceeding 50 J/cm2. Numerous non-metallic inclusions present in the microstructure of cast GX5CrNi-Mo19-11-2 steel resulting from, among others, the miscalculated refining process were found to be one of the main causes of reduced impact strength as compared to the cast GX5CrNi18-9 steel.

  4. FMR measurements on CoCr/NiFe double layers

    OpenAIRE

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

    1988-01-01

    CoCr/NiFe double layers were measured by ferromagnetic resonance (FMR) for different angles of the applied field. Several resonance curves were observed for CoCr, which are attributed to the different layers of a magnetically stratified CoCr. This was investigated by carrying out FMR measurements on a single CoCr sample and removing successive layers by ion beam milling. The origin of some of the curves is still unclear. One resonance curve is attributed to the top or bulk layer and another t...

  5. Dislocation Mechanism of Twinning in Ni-Mn-Ga

    Science.gov (United States)

    Zárubová, N.; Ge, Y.; Gemperlová, J.; Gemperle, A.; Hannula, S.-P.

    2012-03-01

    Tensile tests were performed in situ in a transmission electron microscope to investigate the twinning mechanism in non-modulated Ni-Mn-Ga martensite. The reorientation of the twin variants occurs via twinning dislocations. Their generation and movement were followed; the glide plane and Burgers vector were verified. Individual twinning dislocations were visualized.

  6. Bottom and top AF/FM interfaces of NiFe/FeMn/NiFe trilayers

    Science.gov (United States)

    Nascimento, V. P.; Passamani, E. C.; Alvarenga, A. D.; Biondo, A.; Pelegrini, F.; Saitovitch, E. Baggio

    2008-01-01

    X-ray reflectivity analyses were performed in the Si/WTi (7 nm)/NiFe (30 nm)/FeMn (13 nm)/NiFe (10 nm)/WTi (7 nm) exchange-biased system prepared by magnetron sputtering under three different argon working pressures. Layer-by-layer analyses were realized in order to obtain the interfacial roughness parameters quantitatively. For a fixed argon pressure, the root-mean-square roughness (including the atomic grading) of the upper (FeMn/NiFe) interface are greater than that for the lower one in all studied samples. Argon working pressure also has severe influence over the NiFe/FeMn interfaces, being more pronounced at the upper interfaces.

  7. The Hot Corrosion Performance of NiCr-Cr3 C2 Cermet Coating to Boiler Tube

    Institute of Scientific and Technical Information of China (English)

    DINGZhang-xiong; TUGuo-fu

    2004-01-01

    Three kinds of NiCr-Cr3 C2 cermet coatings were designed and deposited by the subsonic velocity flame spraying, and their performances of hot corrosion performance were evaluated in comt)arison with 102G,20G boiler tube steel, FeCrAl, NiCrTi, Ni5OCr and NiCrAIMoFe-Cr3 C2 coatings, which are widely used at present for protection of boiler tubes. Meanwhile, the influence of sealer on the hot corrosion resistance of warious coatings and the mechanisms of coating corrosion were explored.

  8. Composition dependence on the martensitic structures of the Mn-rich NiMnGa alloys

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Chengbao; Muhammad, Yousaf; Deng Lifeng; Wu Wei; Xu Huibin

    2004-05-17

    The Mn-rich Ni{sub 50}Mn{sub 25+x}Ga{sub 25-x} (x=0-5) alloys were developed to investigate the structural transitions and magnetic properties. Structural transitions from austenite to 5M, 7M, and non-modulated martensite were observed with the increase of Mn content. The lattice parameter a elongates, as where b and c contract, and the unit cell volume reduces with increasing Mn content. The martensitic transformation start temperatures M{sub s} increase monotonically from 10.7 deg. C for x=2 to 102.7 deg. C for x=5. The saturation magnetization was measured at 5 K, where all the samples exhibit a martensitic structure. The average magnetic moments per Mn atom vary from 4.38 {mu}{sub B} to 2.93 {mu}{sub B} for x=0 to x=5. The negative effect of excess Mn atoms changes from -3.00 {mu}{sub B} for x=2 to -7.25 {mu}{sub B} for x=5. The excess Mn atoms modify the electronic structures of the unsubstituted Mn atoms, resulting in the sharp decrease of the magnetic moments of the unsubstituted Mn atoms with increasing Mn content. Structural incommensurability was observed with 7M for powder and non-modulated for bulk samper in a specific range of compositions and proved to be reversible when performing martensitic transformation. The 7M and non-modulated martensites Ni{sub 50}Mn{sub 30}Ga{sub 20} possess similar saturation magnetizations and Curie temperatures. The non-modulated martensite was estimated to have a lower free energy than 7M, and should be more stable for a reverse martensitic transformation, leading to a higher austenite start temperature A{sub s}, which is consistent with the experimental result.

  9. Cr-Ni ALLOY ELECTRODEPOSITION AND COMPARISON WITH CONVENTIONAL PURE Cr COATING TECHNIQUE

    OpenAIRE

    Moniruzzaman, M; M.M. Rakib; F.T. Matin

    2012-01-01

    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...

  10. Study of Fe-12Cr-20Mn-W-C austenitic steels irradiated in the SM-2 reactor

    Energy Technology Data Exchange (ETDEWEB)

    Shamardin, V.K.; Bulanova, T.M.; Neustroyev, V.S.; Ostrovsky, Z.E.; Kosenkov, V.M. (V.I. Lenin Research Inst. of Atomic Reactors, Dimitrovgrad (Russia)); Ivanov, L.I.; Djomina, E.V. (A.A. Baikov Inst. of Metallurgy, Academy of Science, Moscow (Russia))

    1992-09-01

    A comparison has been made between the mechanical properties and swelling of austenitic stainless steels EP-838 (Fe-Cr-Mn) and 316SS (Fe-Cr-Ni) irradiated in the mixed-neutron spectrum of the SM-2 reactor in the temperture range 400-800deg C (every 100deg C) to 16 dpa dose with 1000 and 3000 appm helium generation, correspondingly, determined by nickel content. EP-838 exhibited less susceptibility to void swelling and radiation hardening. Fe-12Cr-20Mn-W-0.1C steel without nickel irradiated at 100deg C to 21 dpa exhibited significant radiation hardening accompanied by [alpha]-phase formation in the steel structure. (orig.).

  11. Study of Fe-12Cr-20Mn-W-C austenitic steels irradiated in the SM-2 reactor

    Science.gov (United States)

    Shamardin, V. K.; Bulanova, T. M.; Neustroyev, V. S.; Ostrovsky, Z. E.; Kosenkov, V. M.; Ivanov, L. I.; Djomina, E. V.

    1992-09-01

    A comparison has been made between the mechanical properties and swelling of austenitic stainless steels EP-838 (Fe-Cr-Mn) and 316SS (Fe-Cr-Ni) irradiated in the mixed-neutron spectrum of the SM-2 reactor in the temperature range 400-800°C (every 100°C) to 16 dpa dose with 1000 and 3000 appm helium generation correspondingly, determined by nickel content. EP-838 exhibited less susceptibility to void swelling and radiation hardening. Fe-12Cr-20Mn-W-0.1C steel without nickel irradiated at 100°C to 21 dpa exhibited significant radiation hardening accompanied by α-phase formation in the steel structure.

  12. 25CrMnMo钢强韧化研究

    Institute of Scientific and Technical Information of China (English)

    徐天兵

    2004-01-01

    研究了热处理对新型热轧调质无缝油管用25CrMnMo钢性能的影响.试验结果表明,该钢在920 ℃保温30 min水冷,650 ℃回火70 min后有较好的强度和韧性.通过选择不同的调质工艺可以满足API 5CT标准中N80Q和P110等高钢级油管的性能要求.

  13. Austenite phase formation in rapidly solidified Fe-Cr-Mn-C steels

    Energy Technology Data Exchange (ETDEWEB)

    Chen, S.R.; Davies, H.A.; Rainforth, W.M.

    1999-12-10

    Steels having compositions (wt%) 0.05--0.5C, 12.5--20Cr, 8--25Mn and 0--0.51N have been chill-block melt-spun to ribbons in order to investigate systematically, by X-ray diffractometry and electron microscopy, the effects of rapid solidification and of solute concentrations on the formation of the austenite phase. The austenite is most easily formed at (wt%) 16Cr--8Mn for 0.3C ribbons while {alpha}{prime}-martensite or {epsilon}-martensite was observed at lower concentrations of Cr or Mn and {alpha}-ferrite appeared for Cr {gt} 18 wt%. The volume fraction of austenite in the steel ribbons studied was found, by multiple regression analysis, to obey the equation {gamma}(%) = 94 + 26.8C + Mn x (8.4 {minus} 0.08Mn {minus} 0.44Cr) {minus} (Cr {minus} 17.7){sup 2}. Thus, the effect of Mn on {gamma} formation followed a non-linear function, containing an interaction term including the Cr and Mn contents, and first- and second-order terms involving the Mn concentration. This indicates the ranges over when Mn is a {gamma}-former or an {alpha}-former. Iso-austenitic lines, constructed on the basis of this new equation, are nearly orthogonal to those in the Schaeffler diagram for Cr-Mn steels so that use of the latter for prediction of the austenite content in the present case would be inappropriate.

  14. Reaction diffusion in the NiCrAl and CoCrAl systems

    Science.gov (United States)

    Levine, S. R.

    1978-01-01

    The paper assesses the effect of overlay coating and substrate composition on the kinetics of coating depletion by interdiffusion. This is accomplished by examining the constitution, kinetics and activation energies for a series of diffusion couples primarily of the NiCrAl/Ni-10Cr or CoCrAl/Ni-10Cr type annealed at temperatures in the range 1000-1205 C for times up to 500 hr. A general procedure is developed for analyzing diffusion in multicomponent multiphase systems. It is shown that by introducing the concept of beta-source strength, which can be determined from appropriate phase diagrams, the Wagner solution for consumption of a second phase in a semiinfinite couple is successfully applied to the analysis of MCrAl couples. Thus, correlation of beta-recession rate constants with couple composition, total and diffusional activation energies, and interdiffusion coefficients are determined.

  15. Correlation between Cr~(6+) and Mn~(2+) Adsorption in Rock-soil Medium with Combined Pollution

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    [Objective] The aim was to study the correlation between Cr6+ and Mn2+ adsorption in rock-soil medium with combined pollution. [Method] Combining single Cr6+ and Mn2+ adsorption test with combined pollution test, the adsorption laws of Cr6+ and Mn2+ were studied, and the correlation between Cr6+ and Mn2+ adsorption was analysed by using correlation analysis and regression analysis. [Result] According to the comparative analysis on adsorption tests, the adsorption time, adsorption amount and adsorption speed...

  16. Exchange bias effect in polycrystalline NiO/NiMn{sub 2}O{sub 4} composite

    Energy Technology Data Exchange (ETDEWEB)

    Freitas Cabral, A.J. [Instituto de Ciências Exatas e Naturais, Universidade Federal do Pará (UFPA), Belém, PA (Brazil); Peña Serna, J.; Rache Salles, B.; Novak, M.A. [Instituto de Física, Universidade Federal do Rio de janeiro (UFRJ), Rio de Janeiro, RJ (Brazil); Pinto, A.L. [Centro Brasileiro de Pesquisas Físicas (CBPF), Rio de Janeiro, RJ (Brazil); Rocha Remédios, C.M. [Instituto de Ciências Exatas e Naturais, Universidade Federal do Pará (UFPA), Belém, PA (Brazil)

    2015-05-05

    Highlights: • Antiferromagnetic NiO/ferrimagnetic NiMn{sub 2}O{sub 4} oxide composites. • Grains are well faceted, indicating that the specimen was well crystallized. • The micrographs suggests that NiO and NiMn{sub 2}O{sub 4} may be stuck to each other. • EB effect in NiO/NiMn{sub 2}O{sub 4} oxide composites. • EB effect increases with the amount of NiO. - Abstract: Calcination of aqueous solutions formed by different molar ratios between the nickel and manganese chlorides led to the formation of antiferromagnetic NiO/ferrimagnetic NiMn{sub 2}O{sub 4} oxide composites, as determined by X-ray powder diffraction technique and Rietveld refinement. Low temperature zero field cooled and field cooled magnetic hysteresis cycles show an exchange bias effect, presumably due to interaction at the interfaces between the antiferromagnetic and ferrimagnetic materials.

  17. Characterization of NiCrAlC PTA coatings

    OpenAIRE

    2012-01-01

    Surface tailoring with plasma transferred arc (PTA) hardfacing involves the deposition of powder mixtures to produce coatings with an almost unlimited chemical composition. PTA hardfacing is particularly important for processing low weldability alloys, such as those for high-temperature applications, of which NiCrAlC is an example. This study analyzed NiCrAlC coatings processed by PTA using a mixture of elemental powders. Deposition on AISI316L plates was carried out with currents of 100 A an...

  18. Mechanical characteristics and swelling of austenitic Fe-Cr-Mn steels irradiated in the SM-2 and BOR-60 reactors

    Science.gov (United States)

    Shamardin, V. K.; Bulanova, T. M.; Neustroev, V. S.; Ivanov, L. I.; Djomina, E. V.; Platov, Yu. M.

    1991-03-01

    Three types of austenitic Fe-Cr-Mn stainless steels were irradiated simultaneously with Fe-Cr-Ni austenitic steel at temperatures from 400 to 800°C in the mixed spectrum of the high flux SM-2 reactor to 10 dpa and 700 appm of He and in the BOR-60 reactor to 60 dpa without He generation. The paper presents the swelling and mechanical properties of steels irradiated in the BOR-60 and SM-2 as a function of the concentration of transmuted He and the value of atomic displacement.

  19. V, Cr, and Mn in the earth, moon, EPB, and SPB and the origin of the moon - Experimental studies

    Science.gov (United States)

    Drake, Michael J.; Capobianco, Christopher J.; Newsom, Horton E.

    1989-01-01

    The abundances of V, Cr, and Mn inferred for the mantles of the earth and moon decrease in that order and are similar in both mantles (but distinct from those in the mantles of the Eucrite Parent Body and Shergottite Parent Body), suggesting a common origin for the mantles of the earth and the moon. This hypothesis was investigated on the basis of a comparison between the depletions of V, Cr, and Mn in the mantles of the earth and the moon, and the metal/silicate partition coefficients of these elements at 1260 C and 1 bar pressure among a S-bearing metallic liquid, a silicate melt, and a FeNi alloy. It was found that the earth and the moon depletions of V, Cr, and Mn are not correlated with metal/silicate partition coefficients; the V and Cr partitioned into S-rich metallic liquids under reducing conditions more strongly than Mn, consistent with the relative volatilities of these elements. This indicates that the depletion patterns of these elements in the mantles of the earth and moon cannot be attributed primarily to terrestrial core formation.

  20. [Effect of aurum coating on corrosion resistance of Ni-Cr alloy].

    Science.gov (United States)

    Chen, Zhi-hong; Liu, Li; Mao, Ying-jie

    2007-02-01

    To evaluate the effect of aurum coating on corrosion resistance of Ni-Cr alloy in artificial saliva environment. The corrosion potential (E(corr)), self-corrosion current density (I(corr)), and polarization resistance (R(p)) of three alloys were measured using electrochemical methods to compare the difference of corrosion resistance between aurum-coated Ni-Cr alloy and Ni-Cr alloy or Au alloy. Meanwhile, microstructural and phase diffraction was examined with field scanning electromicroscopy (FSEM) and surface chemical analysis was performed by energy diffraction X-ray (EDX). The I(corr) of aurum-coated Ni-Cr alloy was (0.70 +/- 0.20) x 10(-6) A/cm2, which was significantly higher than that of Au alloy (P Cr alloy (P coated Ni-Cr alloy was (34.77 +/- 12.61) KOmega.cm2, which was higher than that of Ni-Cr alloy (P Cr alloy coated with aurum was better than that of Ni-Cr alloy. The results of EDX indicated that released Ni and Cr of Ni-Cr alloy coated with aurum after test were less than those of Ni-Cr alloy (P coated Ni-Cr alloy is higher than that of Ni-Cr alloy.

  1. Fate of half-metallicity near interfaces: The case of NiMnSb/MgO and NiMnSi/MgO

    KAUST Repository

    Zhang, Ruijing

    2014-08-27

    The electronic and magnetic properties of the interfaces between the half-metallic Heusler alloys NiMnSb, NiMnSi, and MgO have been investigated using first-principles density-functional calculations with projector augmented wave potentials generated in the generalized gradient approximation. In the case of the NiMnSb/MgO (100) interface, the half-metallicity is lost, whereas the MnSb/MgO contact in the NiMnSb/MgO (100) interface maintains a substantial degree of spin polarization at the Fermi level (∼60%). Remarkably, the NiMnSi/MgO (111) interface shows 100% spin polarization at the Fermi level, despite considerable distortions at the interface, as well as rather short Si/O bonds after full structural optimization. This behavior markedly distinguishes NiMnSi/MgO (111) from the corresponding NiMnSb/CdS and NiMnSb/InP interfaces. © 2014 American Chemical Society.

  2. Fate of half-metallicity near interfaces: the case of NiMnSb/MgO and NiMnSi/MgO.

    Science.gov (United States)

    Zhang, Rui-Jing; Eckern, Ulrich; Schwingenschlögl, Udo

    2014-08-27

    The electronic and magnetic properties of the interfaces between the half-metallic Heusler alloys NiMnSb, NiMnSi, and MgO have been investigated using first-principles density-functional calculations with projector augmented wave potentials generated in the generalized gradient approximation. In the case of the NiMnSb/MgO (100) interface, the half-metallicity is lost, whereas the MnSb/MgO contact in the NiMnSb/MgO (100) interface maintains a substantial degree of spin polarization at the Fermi level (∼60%). Remarkably, the NiMnSi/MgO (111) interface shows 100% spin polarization at the Fermi level, despite considerable distortions at the interface, as well as rather short Si/O bonds after full structural optimization. This behavior markedly distinguishes NiMnSi/MgO (111) from the corresponding NiMnSb/CdS and NiMnSb/InP interfaces.

  3. Shape memory effect in Fe-Mn-Ni-Si-C alloys with low Mn contents

    Energy Technology Data Exchange (ETDEWEB)

    Min, X.H., E-mail: MIN.Xiaohua@nims.go.jp [National Institute for Materials Science, Tsukuba 305-0047 (Japan); Sawaguchi, T.; Ogawa, K. [National Institute for Materials Science, Tsukuba 305-0047 (Japan); Maruyama, T. [Awaji Materia Co., Ltd. 2-3-13, Kanda ogawamachi, Chiyoda, Tokyo 101-0052 (Japan); Yin, F.X. [National Institute for Materials Science, Tsukuba 305-0047 (Japan); Tsuzaki, K. [National Institute for Materials Science, Tsukuba 305-0047 (Japan); Graduate School of Pure and Applied Sciences, University of Tsukuba, Ibaraki 305-0047 (Japan)

    2011-06-15

    Highlights: {yields} A class of new Fe-Mn-Ni-Si-C shape memory alloys with low Mn contents has been designed. {yields} A Mn content for the onset of the {alpha}' martensite is less than 13 mass%, and the {epsilon} martensite still exists in the alloy with a 9 mass% Mn. {yields} The shape recovery strain decreases considerably when the Mn content is reduced from 13 to 11 mass%. {yields} The sudden decrease in the shape recovery strain is mainly caused by the formation of {alpha}' martensite. - Abstract: An attempt was made to develop a new Fe-Mn-Si-based shape memory alloy from a Fe-17Mn-6Si-0.3C (mass%) shape memory alloy, which was previously reported to show a superior shape memory effect without any costly training treatment, by lowering its Mn content. The shape memory effect and the phase transformation behavior were investigated for the as-solution treated Fe-(17-2x)Mn-6Si-0.3C-xNi (x = 0, 1, 2, 3, 4) polycrystalline alloys. The shape recovery strain exceeded 2% in the alloys with x = 0-2, which is sufficient for an industrially applicable shape memory effect; however, it suddenly decreased in the alloys between x = 2 and 3 although the significant shape recovery strain still exceeded 1%. In the alloys with x = 3 and 4, X-ray diffraction analysis and transmission electron microscope observation revealed the existence of {alpha}' martensite, which forms at the intersection of the {epsilon} martensite plates and suppresses the crystallographic reversibility of the {gamma} austenite to {epsilon} martensitic transformation.

  4. Effect of Ni, Fe and Mn in different proportions on microstructure and pollutant-catalyzed properties of Ni-Fe-Mn-O negative temperature coefficient ceramic nanocompositions

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Yonglin, E-mail: leiyonglin@163.com [Engineering Research Center of Biomass Materials, Ministry of Education, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Lin, Xiaoyan, E-mail: linxy@swust.edu.cn [Engineering Research Center of Biomass Materials, Ministry of Education, School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Liao, Huiwei, E-mail: liaohw@swust.edu.cn [School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China)

    2017-06-15

    The effect of Ni, Fe and Mn in different proportions on microstructure and pollutant-catalyzed properties of Ni-Fe-Mn-O negative temperature coefficient ceramic nanocompositions was studied. Structural and physical characterization of all the samples was carried out by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) method, Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetric (TG). The results revealed that the interplanar spacing decreased with increasing Fe content, the grain size decreased with increasing Ni content, the substitution of Ni{sup 2+} in the tetrahedral sites by Fe{sup 2+} increased with increasing Fe content. And increase of iron could improve Ni-Fe-Mn-O high temperature stability. The low-temperature thermal removal efficiencies of 30 mg/L methyl orange solution for NiFeMnO{sub 4}, Ni{sub 0.6}Fe{sub 0.9}Mn{sub 1.5}O{sub 4,} Ni{sub 0.6}Fe{sub 1.8}Mn{sub 0.6}O{sub 4} and Ni{sub 0.3}Fe{sub 2.1}Mn{sub 0.6}O{sub 4} systems were 83.8%, 75.2%, 78.5% and 60.3% at 2400 min, respectively. And the microwave combining with H{sub 2}O{sub 2} removal efficiencies of 30 mg/L methyl orange solution for NiFeMnO{sub 4}, Ni{sub 0.6}Fe{sub 0.9}Mn{sub 1.5}O{sub 4,} Ni{sub 0.6}Fe{sub 1.8}Mn{sub 0.6}O{sub 4} and Ni{sub 0.3}Fe{sub 2.1}Mn{sub 0.6}O{sub 4} systems were 96.5%,93.8%, 98.7% and 98% at 6.0 min, respectively. These results indicated that the Ni-Fe-Mn-O ceramics with appropriate increase of iron were useful for industrial applications on degrading organic pollute. - Highlights: • The relationship of composition and catalytic properties of Ni-Fe-Mn-O was proposed. • The interplanar spacing decreased with increasing Fe content. • The grain size decreased with increasing Ni content. • The substitution of Ni{sup 2+} in the tetrahedral site by Fe{sup 2+} with increasing Fe content.

  5. Thermal Arrest Memory Effect in Ni-Mn-Ga Alloys

    Directory of Open Access Journals (Sweden)

    A. Rudajevova

    2008-01-01

    Full Text Available Dilatation characteristics were measured to investigate the thermal arrest memory effect in Ni53.6Mn27.1Ga19.3 and Ni54.2Mn29.4Ga16.4 alloys. Interruption of the martensite-austenite phase transformation is connected with the reduction of the sample length after thermal cycle. If a total phase transformation took place in the complete thermal cycle following the interruption, then the sample length would return to its original length. Analysis of these results has shown that the thermal arrest memory effect is a consequence of a stress-focusing effect and shape memory effect. The stress-focusing effect occurs when the phase transformation propagates radially in a cylindrical sample from the surface, inward to the center. Evolution and release of the thermoelastic deformations in both alloys during heating and cooling are analyzed.

  6. Phase stability and magnetic-field-induced martensitic transformation in Mn-rich NiMnSn alloys

    Directory of Open Access Journals (Sweden)

    Q. Tao

    2012-12-01

    Full Text Available A series of Ni50-xMn41+xSn9 (x = 0–19 alloys from Ni-rich to Mn-rich composition were prepared, and the composition dependence of phase transitions and magnetic properties were investigated. No γ-phase can be observed until x = 17. Martensitic transformation from ferromagnetic austenite to weak-magnetic or ferromagnetic martensite was observed in alloys with Mn content between 52 and 58, and magnetic-field-induced transformation was confirmed. A large magnetization change of 44 Am2/kg across the martensitic transformation is observed in Ni37Mn54Sn9. Our results indicate that Mn-rich Ni-Mn-Sn alloys show promise as metamagnetic shape memory alloys.

  7. Preparation, structural and magnetic characterization of DyCrMnO 5

    Science.gov (United States)

    Martínez-Lope, M. J.; Retuerto, M.; García-Hernández, M.; Alonso, J. A.

    2009-03-01

    The title compound has been first synthesized by a citrate technique followed by thermal treatments under moderate oxygen pressure conditions, and characterized by X-ray and neutron powder diffraction (NPD) and magnetization measurements. The crystal structure of DyCrMnO 5 has been refined from NPD data in the space group Pbam; a=7.2617(6) Å, b=8.5161(6) Å, and c=5.7126(5) Å at 295 K. This oxide is isostructural with RMn 2O 5 oxides ( R=rare earths) and it contains infinite chains of (Cr, Mn) 4+O 6 octahedra-sharing edges, linked together by (Mn, Cr) 3+O 5 pyramids and DyO 8 units. The high degree of antisite disordering exhibited by DyCrMnO 5 is noteworthy. The octahedral positions are occupied by roughly 50% of Mn and Cr cations, and the pyramidal groups contain two thirds of Mn and one third of Cr cations. We assume that Mn and Cr cations at the octahedral positions exhibit a tetravalent oxidation state, whereas the metals at the pyramidal positions are trivalent, in order to preserve the electroneutrality of this oxide. The susceptibility vs temperature curve of DyCrMnO 5 does not suggest the establishment of a long-range magnetic structure even at low temperatures; the NPD technique does not provide any signal of magnetic ordering, since the reflections do not show any magnetic contribution.

  8. Fatigue behaviors and damage mechanism of a Cr-Mn-N austenitic steel

    DEFF Research Database (Denmark)

    Lv, Z.; Cai, P.; Yu, Tianbo;

    2017-01-01

    Four-point bending fatigue tests were conducted on a Cr-Mn-N austenitic steel at room temperature, at frequency of 20 Hz and the stress ratio of R = 0.1, in air. The fatigue strength of this Cr-Mn-N austenitic steel was measured to be 503 MPa in the maximum stress from the S-N curve obtained...

  9. Mn-Cr intersite independent magnetic behavior and electronic structures of LaMn3Cr4O12: Study from first-principles

    Science.gov (United States)

    Lv, Shuhui; Li, Hongping; Liu, Xiaojuan; Meng, Jian

    2011-07-01

    The magnetic and electronic structures of LaMn3Cr4O12 are investigated using the full-potential linearized augmented plane wave method within both the generalized gradient approximation (GGA) and GGA + U (electronic correlation) methods. The calculated results indicate that LaMn3Cr4O12 is an antiferromagnetic insulator. The magnetic ordering is demonstrated to be G-type within both Mn-site and Cr-site spins. However, there is no obvious magnetic coupling between Mn-site and Cr-site sublattices, which is verified by the separate distribution of their corresponding partial density of states. Moreover, the magnetic coupling constants of JCr-Cr and JMn-Mn are predicted to be - 5.0 (- 2.8) and - 0.83 (- 0.63) meV within GGA (GGA + U), respectively, consistent with the experimentally observed two independent Néel temperatures (TN1 and TN2). The calculated densities of states reveal the experimentally reported charge formula of LaMn3+3Cr3+4O12.

  10. Replacement of Ni by Mn in High-Ni-Containing Austenitic Cast Steels used for Turbo-Charger Application

    Science.gov (United States)

    Jung, Seungmun; Jo, Yong Hee; Jeon, Changwoo; Choi, Won-Mi; Lee, Byeong-Joo; Oh, Yong-Jun; Kim, Gi-Yong; Jang, Seongsik; Lee, Sunghak

    2017-02-01

    High-temperature tensile properties of austenitic cast steels fabricated by replacing Ni by Mn in a 20 wt pct Ni-containing steel were investigated. In a steel where 8 wt pct Ni was replaced by 9.2 wt pct of Mn, 17.4 and 9.8 pct of ferrite existed in equilibrium phase diagrams and actual microstructures, respectively, because a role of Mn as an austenite stabilizer decreased, and led to deterioration of high-temperature properties. When 2 to 6 wt pct Ni was replaced by 2.3 to 6.9 wt pct Mn, high-temperature properties were comparable to those of the 20 wt pct Ni-containing steel because ferrites were absent, which indicated the successful replacement of 6 wt pct Ni by Mn, with cost reduction of 27 pct.

  11. Magnetic properties and electronic structure of Mn-Ni-Ga magnetic shape memory alloys.

    Science.gov (United States)

    D'Souza, Sunil Wilfred; Roy, Tufan; Barman, Sudipta Roy; Chakrabarti, Aparna

    2014-12-17

    Influence of disorder, antisite defects, martensite transition and compositional variation on the magnetic properties and electronic structure of Mn(2)NiGa and Mn(1+x)Ni(2-x)Ga magnetic shape memory alloys have been studied by using full potential spin-polarized scalar relativistic Korringa-Kohn-Rostocker (FP-SPRKKR) method. Mn(2)NiGa is ferrimagnetic and its total spin moment increases when disorder in the occupancy of MnNi (Mn atom in Ni position) is considered. The moment further increases when Mn-Ga antisite defect [1] is included in the calculation. A reasonable estimate of TC for Mn(2)NiGa is obtained from the exchange parameters for the disordered structure. Disorder influences the electronic structure of Mn(2)NiGa through overall broadening of the density of states and a decrease in the exchange splitting. Inclusion of antisite defects marginally broaden the minority spin partial DOS (PDOS), while the majority spin PDOS is hardly affected. For Mn(1+x)Ni(2-x)Ga where 1 ⩾ x ⩾ 0, as x decreases, Mn(Mn) moment increases while Mn(Ni) moment decreases in both austenite and martensite phases. For x ⩾ 0.25, the total moment of the martensite phase is smaller compared to the austenite phase, which indicates possible occurrence of inverse magnetocaloric effect. We find that the redistribution of Ni 3d- Mn(Ni) 3d minority spin electron states close to the Fermi level is primarily responsible for the stability of the martensite phase in Mn-Ni-Ga.

  12. Hydrogen storage properties of nano-composites of Mg and Zr-Ni-Cr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Yang, J.; Ciureanu, M.; Roberge, R. [H Power Enterprises of Canada, 1069 Begin Street, St. Laurent, Quebec (Canada)

    2000-05-01

    Mg and Zr-Ni-Cr alloy nano-composite hydrogen storage materials have been prepared by high energy mechanical milling (MM) of Mg powders with either crystalline ZrNiCr and ZrNi{sub 1.6}Cr{sub 0.4} powders or mechanically milled amorphous ZrNiCr and ZrNi{sub 1.6}Cr{sub 0.4} powders. Nano-composites of amorphous Zr-Ni-Cr alloy and Mg have better desorption kinetics compared to crystalline Zr-Ni-Cr alloy and Mg nano-composites. Amorphous ZrNi{sub 1.6}Cr{sub 0.4} and Mg nano-composites desorb larger amount of H{sub 2} much faster than amorphous ZrNiCr and Mg nano-composites. The nano-composite of 35 wt.% amorphous ZrNi{sub 1.6}Cr{sub 0.4} and Mg releases 4.3 wt.% H{sub 2} at 300C in 30 min. X-ray diffraction revealed that there are no reactions between Mg and Zr-Ni-Cr alloys in the milling, activation, and subsequent cycling processes, proving that amorphous ZrNi{sub 1.6}Cr{sub 0.4} is an effective hydrogen absorption and desorption catalyst.

  13. Study on wear resistant cast B-containing 1Cr18Ni9Ti stainless steel

    Institute of Scientific and Technical Information of China (English)

    Kuang Jiacai; Jiang Zhiqiang; Zhang Shiyin; Ye Chang; Liu Qicheng

    2009-01-01

    The developed 1Cr18Ni9Ti austenitic stainless steel containing 1.63 wt.%B have been characterized by X-ray diffraction (XRD), electron probe microanalyzer (EPMA), optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and Vickers microhardness measurement. The microstructural evolution and property of high boron stainless steel after solution treatment at the temperature of 1050℃ are also investigated. The results show that the main compositions of borides are Fe, Cr and B, and with small amount of Ni, Mn and C elements. Silicon is insoluble in the borides. The hardness of borides is over 1,500 HV. It has been found that borides do not decompose during solution treatment, but part of borides dissolves into the matrix. The effect of increasing the solubility of boron element in the austenitic matrix favours the hardness enhancement by 8.54%. High boron stainless steel has excellent wear resistance in corrosive environment. Lifetime of transfer pipe made of high boron-containing stainless steel is 1.5-1.8 times longer than that of boron-free 1Cr18Ni9Ti stainless steel.

  14. PREPARATION AND PROPERTIES OF Ni-Cr AND Fe-Cr-Al FILMS BY VACUUM EVAPORATION

    Institute of Scientific and Technical Information of China (English)

    X. W. Shi; Z.Y. Liu; D.C. Zeng; C.M. Li

    2003-01-01

    Ni-Cr and Fe-Cr-Al films deposited on the Al2O3 substrate are studied by a method of vacuum evaporation in this paper. Influence of resistance value on density and evaporation parameters of the films reveals that the resistance of films and the adhesion of films to substrates are determined by the evaporation time and the substrate temperate under the condition of the maximum vacuity of 6.2×10-4 pa, respectively.

  15. A comparative study of magnetic behaviors in TbNi{sub 2}, TbMn{sub 2} and TbNi{sub 2}Mn

    Energy Technology Data Exchange (ETDEWEB)

    Wang, J. L., E-mail: jianli@uow.edu.au [Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, NSW 2522 (Australia); Bragg Institute, ANSTO, Lucas Heights, NSW 2234 (Australia); Md Din, M. F.; Hong, F.; Cheng, Z. X.; Dou, S. X. [Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, NSW 2522 (Australia); Kennedy, S. J.; Studer, A. J. [Bragg Institute, ANSTO, Lucas Heights, NSW 2234 (Australia); Campbell, S. J. [School of Physical, Environmental and Mathematical Sciences, The University of New South Wales, Canberra, ACT 2600 (Australia); Wu, G. H. [Institute of Physics, Chinese Academy of Science, Beijing 100190 (China)

    2014-05-07

    All TbNi{sub 2}, TbMn{sub 2}, and TbNi{sub 2}Mn compounds exhibit the cubic Laves phase with AB{sub 2}-type structure in spite of the fact that the ratio of the Tb to transition-metal components in TbNi{sub 2}Mn is 1:3. Rietveld refinement indicates that in TbNi{sub 2}Mn the Mn atoms are distributed on both the A (8a) and B (16d) sites. The values of the lattice constants were measured to be a = 14.348 Å (space group F-43 m), 7.618 Å, and 7.158 Å (space group Fd-3 m) for TbNi{sub 2}, TbMn{sub 2}, and TbNi{sub 2}Mn, respectively. The magnetic transition temperatures T{sub C} were found to be T{sub C} = 38 K and T{sub C} = 148 K for TbNi{sub 2} and TbNi{sub 2}Mn, respectively, while two magnetic phase transitions are detected for TbMn{sub 2} at T{sub 1} = 20 K and T{sub 2} = 49 K. Clear magnetic history effects in a low magnetic field are observed in TbMn{sub 2} and TbNi{sub 2}Mn. The magnetic entropy changes have been obtained.

  16. Observations of defect structure evolution in proton and Ni ion irradiated Ni-Cr binary alloys

    Science.gov (United States)

    Briggs, Samuel A.; Barr, Christopher M.; Pakarinen, Janne; Mamivand, Mahmood; Hattar, Khalid; Morgan, Dane D.; Taheri, Mitra; Sridharan, Kumar

    2016-10-01

    Two binary Ni-Cr model alloys with 5 wt% Cr and 18 wt% Cr were irradiated using 2 MeV protons at 400 and 500 °C and 20 MeV Ni4+ ions at 500 °C to investigate microstructural evolution as a function of composition, irradiation temperature, and irradiating ion species. Transmission electron microscopy (TEM) was applied to study irradiation-induced void and faulted Frank loops microstructures. Irradiations at 500 °C were shown to generate decreased densities of larger defects, likely due to increased barriers to defect nucleation as compared to 400 °C irradiations. Heavy ion irradiation resulted in a larger density of smaller voids when compared to proton irradiations, indicating in-cascade clustering of point defects. Cluster dynamics simulations were in good agreement with the experimental findings, suggesting that increases in Cr content lead to an increase in interstitial binding energy, leading to higher densities of smaller dislocation loops in the Ni-18Cr alloy as compared to the Ni-5Cr alloy.

  17. Oxidation - Nitridation of Ni-Cr-Al alloys

    Directory of Open Access Journals (Sweden)

    Han Susan

    2004-01-01

    Full Text Available A series of alloys containing 24-36 wt pct Cr and 13.5 - 25.0 wt pct Al was reacted with air at 1100°C for 260 h. The products of isothermal reaction were scales of a-Al2O3 plus small amounts of Cr2O3. These grew according to parabolic kinetics, interrupted by episodic weight losses caused by partial spallation. No nitridation occurred during the isothermal exposures. Reaction during thermal cycling for up to 260 one hour cycles was much more severe. Repeated scale spallation led to subsurface alloy depletion in aluminium and, to a lesser extent, chromium. This caused transformation of the prior alloy three-phase structures (a-Cr+b-NiAl+g-Ni to single-phase g-nickel solution. Destruction of the external scale allowed gas access to this metal which was able to dissolve both oxygen and nitrogen. Inward diffusion of the two oxidants led to development of a complex internal precipitation zone: Al2O3 and Cr2O3 beneath the surface, then Al2O3 then AIN, then AIN + Cr2N and finally AIN alone in the deepest region. Diffusion-controlled kinetics were in effect initially, but mechanical damage to the internal precipitation zone led to more rapid gas access and approximately linear kinetics in the long term.

  18. Thermomechanical behavior of rapidly solidified Fe-25Cr-20Ni

    Energy Technology Data Exchange (ETDEWEB)

    Draissia, M.; Boukhris, N.; Debili, M.Y. [LM2S, Dept. de Physique, Faculte des Sciences, Univ. Badji-Mokhtar, Annaba, Algerie (Turkey)

    2004-07-01

    The thermomechanical treatment at 1050 C under a stress of about 30 MPa, of milled ribbons from Fe-25Cr-20Ni (0.060%Ni-0.1%Ti) refractory stainless steel, leads to a recrystallisation of the as-melt-spun structure which is intermediate between cellular and columnar dendritic. The mean grain size in the relatively high density zones (85%) may be considered as low and do not exceed 10{mu}m. Other grains appear abnormally large and reach 30 {mu}m. The origin of these grains, must be researched in an exaggerate growth phenomenon under a local deformation near the critical work hardening. (orig.)

  19. Phase diagram and magnetocaloric effects in Ni1-xCrxMnGe1.05

    Science.gov (United States)

    Aryal, Anil; Quetz, Abdiel; Pandey, Sudip; Eubank, Michael; Samanta, Tapas; Dubenko, Igor; Stadler, Shane; Ali, Naushad

    2015-05-01

    The structural and magnetic properties of the Ni1-xCrxMnGe1.05 system (for x = 0, 0.035, 0.070, 0.105) have been studied by x-ray diffraction (XRD), differential scanning calorimetry (DSC), and magnetization measurements. A change in crystal structure from orthorhombic to hexagonal was observed in the XRD data at chromium concentrations of x = 0.035, 0.070, and 0.105. The values of the cell parameters and volume of the unit cell for orthorhombic and hexagonal phase were determined. It was found that the partial substitution of Cr for Ni in Ni1-xCrxMnGe1.05 results in a first order magnetostructural transition from antiferromagnetic to ferromagnetic (FM) at TM = 132 K for x = 0.105. A FM to paramagnetic second order transition has been observed at TC = 204 K. A magnetic entropy change of | Δ S M | = 4.5 J/kg K for ΔH = 5 T was observed in the vicinity of TC and TM for x = 0.105. The values of the latent heat (L = 2.2 J/g) and corresponding total entropy changes (ΔST = 16 J/kg K) have been determined from DSC measurements. A concentration-dependent phase diagram of transition temperatures has been constructed using the magnetic and DSC data.

  20. Development of banded microstructure in 34CrNiMo6 steel

    Directory of Open Access Journals (Sweden)

    A. Nagode

    2016-07-01

    Full Text Available In this paper the development of a banded microstructure in hot-rolled 34CrNiMo6 steel which consisted of bainitic and martensitic bands is explained. The chemical compositions of the bands were measured with energy dispersive x-ray spectroscopy (EDS, which showed that the martensitic bands contained more alloying elements (Mn, Cr, Mo, Si than bainitic bands. By using Oberhoffer reagent, the segregations of phosphorus were also revealed. These phosphorus segregations coincided with the positive segregations of the alloying elements. The continuous cooling transformation (CCT diagrams of steel were calculated. They confirmed the formation of martensite in positive segregations and the formation of bainite in negative segregations.

  1. Role of oxygen diffusion at Ni/Cr2O3 interface in intergranular oxidation of Ni-Cr alloy

    Science.gov (United States)

    Medasani, Bharat; Sushko, Maria; Schreiber, Daniel; Rosso, Kevin; Bruemmer, Stephen

    Certain Ni-Cr alloys used in nuclear systems experience intergranular oxidation and stress corrosion cracking when exposed to high-temperature water leading to their degradation and unexpected failure. To develop a mechanistic understanding of grain boundary oxidation processes, we proposed a mesoscale metal alloy oxidation model that combines quantum Density Functional Theory (DFT) with mesoscopic Poisson-Nernst-Planck/classical DFT. This framework encompasses the chemical specificity of elementary diffusion processes and mesoscale reactive dynamics, and allows modeling oxidation processes on experimentally relevant length scales from first principles. As a proof of concept, a preliminary model was previously employed that limited oxygen diffusion pathways to those through the oxide phase and did not allow oxygen diffusion in the alloy or across oxide/alloy interfaces. In this work, we expand the model to include oxygen diffusion pathways along Ni/Cr2O3 interfaces and demonstrate the increasing importance of such pathways for intergranular oxidation of Ni-Cr alloys with high Cr content. This work is supported by the U.S. Dept. of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. Simulations are performed using PNNL Institutional Computing facility.

  2. Moessbauer Investigation of Electrodeposited Sn-Zn, Sn-Cr, Sn-Cr-Zn and Fe-Ni-Cr Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Kuzmann, E.; Stichleutner, S. [Eoetvoes University, Department of Nuclear Chemistry and Research Group of Nuclear Methods in Structural Chemistry HAS (Hungary); El-Sharif, M.; Chisholm, C. U. [Glasgow Caledonian University (United Kingdom); Sziraki, L.; Homonnay, Z.; Vertes, A. [Eoetvoes University, Department of Nuclear Chemistry and Research Group of Nuclear Methods in Structural Chemistry HAS (Hungary)

    2002-06-15

    {sup 57}Fe and {sup 119}Sn CEMS, XRD and electrochemical measurements were used to investigate the effect of the preparation parameters and the components on the structure and phase composition of electrodeposited Fe-Ni-Cr alloys in connection with their corrosion behavior. XRD of the electrodeposits reflect an amorphous-like character. {sup 57}Fe CEM spectra of Fe-Ni-Cr electrodeposited samples, prepared in a continuous flow plating plastic circulation cell with variation of current density, electrolyte velocity and temperature, can be evaluated as a doublet associated with a highly disordered paramagnetic solid solution phase. This phase was identified earlier in Fe-Ni-Cr electrodeposits that were prepared by another plating method and contained both ferromagnetic and paramagnetic metastable phases. This is the first time that we have succeeded to prepare Fe-Ni-Cr alloys containing only the metastable paramagnetic phase. The effect of the plating parameters on the structure is also analysed by the quadrupole splitting distribution method. {sup 119}Sn CEM spectra of all Sn-containing plated alloys show a broad line envelop which can be decomposed at least into two components. One can be associated with {beta}-tin. The other one can be assigned to an alloy phase. The structure and distribution of microenvironments of these phases depends on the plating parameters especially on the parameters of the reverse pulse applied.

  3. Optimizing Tc in the (Mn,Cr,Ga)As and (Mn,Ga)(As,P) Ternary Alloys

    OpenAIRE

    Xu, J. L.; van Schilfgaarde, M.

    2005-01-01

    We explore two possible ways to enhance the critical temperature $T_c$ in the dilute magnetic semiconductor Mn$_{0.08}$Ga$_{0.92}$As. Within the context of the double-exchange and RKKY pictures, the ternary alloys Mn$_{x}$Cr$_{0.08-x}$Ga$_{0.92}$As and Mn$_{0.08}$Ga$_{0.92}$As$_y$P$_{1-y}$ might be expected to have $T_c$ higher than the pseudobinary Mn$_{0.08}$Ga$_{0.92}$As. To test whether the expectations from model pictures are confirmed, we employ linear response theory within the local-d...

  4. Ferromagnetic interactions and martensitic transformation in Fe doped Ni-Mn-In shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Lobo, D. N.; Priolkar, K. R., E-mail: krp@unigoa.ac.in [Department of Physics, Goa University, Taleigao Plateau, Goa 403 206 (India); Emura, S. [Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Nigam, A. K. [Tata Institute of Fundamental Research, Dr. Homi Bhabha Road, Colaba, Mumbai 400 005 (India)

    2014-11-14

    The structure, magnetic, and martensitic properties of Fe doped Ni-Mn-In magnetic shape memory alloys have been studied by differential scanning calorimetry, magnetization, resistivity, X-ray diffraction (XRD), and EXAFS. While Ni{sub 2}MnIn{sub 1−x}Fe{sub x} (0 ≤ x ≤ 0.6) alloys are ferromagnetic and non martensitic, the martensitic transformation temperature in Ni{sub 2}Mn{sub 1.5}In{sub 1−y}Fe{sub y} and Ni{sub 2}Mn{sub 1.6}In{sub 1−y}Fe{sub y} increases for lower Fe concentrations (y ≤ 0.05) before decreasing sharply for higher Fe concentrations. XRD analysis reveals presence of cubic and tetragonal structural phases in Ni{sub 2}MnIn{sub 1−x}Fe{sub x} at room temperature with tetragonal phase content increasing with Fe doping. Even though the local structure around Mn and Ni in these Fe doped alloys is similar to martensitic Mn rich Ni-Mn-In alloys, presence of ferromagnetic interactions and structural disorder induced by Fe affect Mn-Ni-Mn antiferromagnetic interactions resulting in suppression of martensitic transformation in these Fe doped alloys.

  5. Development and High Temperature Property Evaluation of Ni-Co-Cr-Al Composite Electroforms

    Science.gov (United States)

    Srivastava, Meenu; Siju; Balaraju, J. N.; Ravisankar, B.

    2015-05-01

    Ni-Co-Cr-Al composite electroforms were developed with cobalt content of 10 and 40 wt.%. Cr and Al nano-particles were suspended in sulphamate electrolyte and co-deposited in the Ni-Co matrices. The surface morphology was investigated using field emission scanning electron microscope and the composition analyzed by energy-dispersive x-ray analysis. The oxidation resistance of the electroforms was studied from 600 to 1000 °C. The weight gain of Ni-10 wt.%Co-Cr-Al was less (better oxidation resistance) compared to Ni-Cr-Al and Ni-40 wt.%Co-Cr-Al. The x-ray diffraction studies revealed that the oxidation product formed on the surface of Ni-Cr-Al and Ni-10 wt.%Co-Cr-Al consisted of NiO and Al2O3, while Ni-40 wt.%Co-Cr-Al comprised oxides such as NiCo2O4, CrO3, CoO, NiO, and Al2O3. The hot corrosion behavior was investigated in 75%Na2SO4 + 25%NaCl environment at 800 °C. It was found that the hot corrosion resistance of the composite coating improved with increase in cobalt content. The probable composition suitable for high-temperature applications was found to be Ni-10 wt.%Co-Cr-Al.

  6. The Thermal Transformation Arrest Phenomenon in NiCoMnAl Heusler Alloys

    OpenAIRE

    Rie Y. Umetsu; Takeshi Kanomata; Kengo Oka; Takumi Kihara; Wataru Ito; Masashi Tokunaga; Xiao Xu; Ryosuke Kainuma

    2013-01-01

    In this report, we present findings of systematic research on NiCoMnAl alloys, with the purpose of acquiring a higher thermal transformation arrest temperature (TA). By systematic research, TA in the NiCoMnAl alloy systems was raised up to 190 K, compared to the highest TA of 130 K in NiCoMnIn. For a selected alloy of Ni40Co10Mn33Al17, magnetization measurements were performed under a pulsed high magnetic field, and the critical magnetic field-temperature phase diagram was determined. The mag...

  7. Effects of Bond Coating on NiCrBSi-Mo Composite Functional Coating Properties in Plasma Spraying NiCrBSi-Mo/Ni Coating

    Directory of Open Access Journals (Sweden)

    DU Ji-yu

    2017-09-01

    Full Text Available Nickel-based bond coating and composite functional coating were sprayed on leaf blade steel material FV520B successively by using air plasma spraying system. NiCrBSi-Mo powder deposition rate, coating porosity, bonding strength and surface hardness were tested. The results indicate that, for the NiCrBSi-Mo/Ni coating, bond coating with 180-220μm thickness can improve NiCrBSi-Mo powder deposition rate while the surface coating with lower porosity, higher bonding strength and high hardness is prepared; the increase of bond coating thickness can lead to increase of functional coating porosity in the bottom and speed up the process of porosity attenuating in the vertical direction.SEM analysis found that the increase of bond coating thickness results in the droplet deposition morphology change in the bending interface with the functional coating. The defects of bond coating have genetic influence on composite functional coating. Bond tensile test results show that excessive bond coating thickness will cause fracture in the interface between bond coating and functional coating during the stretching process; in different grinding surfaces, Vickers hardness of test blocks with a certain bood coating thickness attenuates slowly in the vertical direction. NiCrBSi-Mo/Ni coating not only maintains high surface hardness, but also increases the coating thickness to repair surface damage.

  8. Magnetic properties of (Co, Ni, Mn3O4 spinels

    Directory of Open Access Journals (Sweden)

    Durán, P.

    2004-06-01

    Full Text Available Magnetic properties of new materials, based on the general formula CoxNiyMnzO4 (x+y+z= 3, have been investigated as a function of magnetic field and temperature. The behavior observed in the paramagnetic regime (220 K ≤ T ≤ 400 K shows a direct correlation with the nominal cation concentration. The paramagnetic-ferrimagnetic transition which takes place at T = Tc depends on the overall composition, going from Tc = 120 K (for Co0.2NiMn1.8O4 up to Tc = 210 K (for Co1.2Ni0.3Mn1.5O4. A second transition is observed at lower temperatures, corresponding to a second ordered magnetic sublattice. This second transition takes place at about 60 K (for Co0.6NiMn1.4O4, increasing with the cobalt content up to about 160 K. Under an external magnetic field, both transitions merge into a single one, with a characteristic temperature Tmax, which rapidly decreases with increasing field. Magnetization loops M(H obtained at 5 K show a typical behavior of soft magnetic materials, with low coercive fields. Low conductivity values were observed at room‑temperature, increasing by a factor of 200-1000 at high temperatures (400 C, which make these compounds to be very interesting materials for potential applications as NTCR thermistors.Se han investigado las propiedades magnéticas de materiales de fórmula CoxNiyMnzO4 (x+y+z+ = 3, en función del campo magnético aplicado y de la temperatura. El comportamiento observado en el régimen paramagnético (220 K ≤ T ≤ 400 K está en relación directa con la concentración catiónica nominal. Se observa una transición paramagnética-ferrimagnética a T = Tc, cuyo valor depende de la composición global del compuesto, variando entre Tc = 120 K (Co0.2NiMn1.8O4 y Tc = 210 K (Co1.2Ni0.3Mn1.5O4. Se ha observado una segunda transición a una temperatura inferior, relacionada con una segunda subred magnéticamente ordenada. Esta segunda transición ocurre a T = 60 K (Co0.6NiMn1.4O4, aumentando progresivamente con la

  9. Corrosion behavior of CuCrNiAl alloy in HCl solutions

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The corrosion behavior of a CuCrNiAl alloy in HCl solutions was studied by means of metallograph, XRD, SEM/EDX and TEM methods. The results show that in low concentration of HCl solutions, Cu of CuCrNiAl alloy is more easily subject to corrsion than Cr; the dechromisation of the CuCrNiAl alloy occurs at a certain concentration of HCl solutions, at the same time Al of CuCrNiAl alloy is subject to corrosion also. The dechromisation corrosion occurs initially at the interface between Cr phase and Cu phase, then it gradually extends Cr phase until Cr phase is dissolved completely. It is also revealed that the tendency of dechromisaion of the CuCrNiAl alloy increases with the increase in concentration and temperature of HCl solutions.

  10. Pressure induced heli- to ferromagnetic transition in Mn0.615Cr0.385As

    DEFF Research Database (Denmark)

    Lebech, Bente

    1986-01-01

    The effect of applied pressure up to 13 kbar on the magnetic properties of Mn0.615Cr0.385As has been studied by powder neutron diffraction. Because of a slightly uneven distribution of Mn and Cr in the metal sublattice two helimagnetic (Ha and Hc types phases coexist at ambient pressure and 80 K....... On subjecting the sample to external pressure, the Ha type mode is converted into a ferromagnetic (F) mode. The results agree with the findings for the analogous phase Mn0.64Cr0.36As1−xPx, where the lattice is exposed to internal, chemically induced pressure....

  11. Structural alteration of hexagonal birnessite by aqueous Mn(II): Impacts on Ni(II) sorption

    Energy Technology Data Exchange (ETDEWEB)

    Lefkowitz, Joshua P.; Elzinga, Evert J.

    2017-09-01

    We studied the impacts of aqueous Mn(II) (1 mM) on the sorption of Ni(II) (200 μM) by hexagonal birnessite (0.1 g L- 1) at pH 6.5 and 7.5 with batch experiments and XRD, ATR-FTIR and Ni K-edge EXAFS analyses. In the absence of Mn(II)aq, sorbed Ni(II) was coordinated predominantly as triple corner-sharing complexes at layer vacancies at both pH values. Introduction of Mn(II)aq into Ni(II)-birnessite suspensions at pH 6.5 caused Ni(II) desorption and led to the formation of edge-sharing Ni(II) complexes. This was attributed to competitive displacement of Ni(II) from layer vacancies by either Mn(II) or by Mn(III) formed through interfacial Mn(II)-Mn(IV) comproportionation, and/or incorporation of Ni(II) into the birnessite lattice promoted by Mn(II)-catalyzed recrystallization of the sorbent. Similar to Mn(II)aq, the presence of HEPES or MES caused the formation of edge-sharing Ni(II) sorption complexes in Ni(II)-birnessite suspensions, which was attributed to partial reduction of the sorbent by the buffers. At pH 7.5, interaction with aqueous Mn(II) caused reductive transformation of birnessite into secondary feitknechtite that incorporated Ni(II), enhancing removal of Ni(II) from solution. These results demonstrate that reductive alteration of phyllomanganates may significantly affect the speciation and solubility of Ni(II) in anoxic and suboxic environments.

  12. Influence of thermal history on the electrochemical properties of Li[Ni0.5Mn1.5]O4

    Science.gov (United States)

    Liu, Guoqiang; Park, Kyu-Sung; Song, Jie; Goodenough, John B.

    2013-12-01

    The oxygen-stoichiometric spinel Li[Ni0.5Mn1.5]O4 is an insulator with ordered Ni(II) and Mn(IV). Although it delivers 4.7 V versus Li, the ordered phase gives poor performance as the cathode of a Li-ion battery. Here we demonstrate control of the degree of cation order by adjusting the oxygen stoichiometry with thermal history of the synthesis rather than by doping 2M(III) for Ni(II) + Mn(IV) (M = Cr, Mn, Fe, Co, Al, Ga). We report retention of capacity near 100 mAh g-1 at room temperature at 10C/10C charge/discharge rate with little capacity fade; at 55 °C, a capacity fade occurs as a result of reaction with the electrolyte, but it is reduced to a level comparable to that obtained by doping.

  13. The ferromagnetic shape-memory effect in Ni Mn Ga

    Science.gov (United States)

    Marioni, M. A.; O'Handley, R. C.; Allen, S. M.; Hall, S. R.; Paul, D. I.; Richard, M. L.; Feuchtwanger, J.; Peterson, B. W.; Chambers, J. M.; Techapiesancharoenkij, R.

    2005-04-01

    Active materials have long been used in the construction of sensors and devices. Examples are piezo-electric ceramics and shape memory alloys. The more recently developed ferromagnetic shape-memory alloys (FSMAs) have received considerable attention due to their large magnetic field-induced, reversible strains (up to 10%). In this article, we review the basic physical characteristics of the FSMA Ni-Mn-Ga (crystallography, thermal, mechanical and magnetic behavior). Also, we present some of the works currently under way in the areas of pulse-field and acoustic-assisted actuation, and vibration energy absorption.

  14. 53Mn-53Cr radiometric dating of secondary carbonates in CR chondrites: Timescales for parent body aqueous alteration

    Science.gov (United States)

    Jilly-Rehak, Christine E.; Huss, Gary R.; Nagashima, Kazuhide

    2017-03-01

    We present 53Mn-53Cr ages of secondary carbonates in Renazzo-like (CR) chondrites, determined by secondary ion mass spectrometry. The timing of aqueous alteration in CR chondrites has been unconstrained in the literature. We measured 53Mn-53Cr isotope systematics in carbonates from three different CR-chondrite lithologies. Calcite in the interchondrule matrix of Renazzo, calcite in the matrix of GRO 95577, and dolomite in a dark inclusion of Renazzo all show excesses in 53Cr, interpreted as the daughter product from the decay of 53Mn. The Renazzo calcite yields an initial ratio of (53Mn/55Mn)0 = (3.6 ± 2.7) × 10-6, and the Renazzo dark inclusion dolomite ranges from (53Mn/55Mn)0 = (3.1 ± 1.4) × 10-6 (corrected to the RSF of a calcite standard) to (3.7 ± 1.7) × 10-6 (corrected to an inferred dolomite RSF). When anchored to the D'Orbigny angrite, the Renazzo carbonates yield ages between 4563.6 and 4562.6 Ma, or ∼4.3-5.3 Myr after the formation of CV CAIs. Calcite measured in the heavily altered specimen GRO 95577 yields a shallower slope of (53Mn/55Mn)0 = (7.9 ± 2.8) × 10-7, corresponding to a much younger age of 4555.4 Ma, or ∼12.6 Myr after CAI formation. The two Renazzo ages are contemporaneous with Mn-Cr ages of carbonates in Tagish Lake, CI, and CM chondrites, but the GRO 95577 age is uniquely young. These findings suggest that early aqueous alteration on chondritic parent bodies was a common occurrence, likely driven by internal heating from 26Al decay after accretion. The young carbonate ages of GRO 95577 suggest that either the CR parent body was sufficiently large to sustain heating from 26Al for ∼8 Myr, or that late-stage impact events supplied heat to the region where GRO 95577 originated.

  15. Austenite Formation from Martensite in a 13Cr6Ni2Mo Supermartensitic Stainless Steel

    Science.gov (United States)

    Bojack, A.; Zhao, L.; Morris, P. F.; Sietsma, J.

    2016-05-01

    The influence of austenitization treatment of a 13Cr6Ni2Mo supermartensitic stainless steel (X2CrNiMoV13-5-2) on austenite formation during reheating and on the fraction of austenite retained after tempering treatment is measured and analyzed. The results show the formation of austenite in two stages. This is probably due to inhomogeneous distribution of the austenite-stabilizing elements Ni and Mn, resulting from their slow diffusion from martensite into austenite and carbide and nitride dissolution during the second, higher temperature, stage. A better homogenization of the material causes an increase in the transformation temperatures for the martensite-to-austenite transformation and a lower retained austenite fraction with less variability after tempering. Furthermore, the martensite-to-austenite transformation was found to be incomplete at the target temperature of 1223 K (950 °C), which is influenced by the previous austenitization treatment and the heating rate. The activation energy for martensite-to-austenite transformation was determined by a modified Kissinger equation to be approximately 400 and 500 kJ/mol for the first and the second stages of transformation, respectively. Both values are much higher than the activation energy found during isothermal treatment in a previous study and are believed to be effective activation energies comprising the activation energies of both mechanisms involved, i.e., nucleation and growth.

  16. 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.

  17. Effects of Ni vacancy, Ni antisite, Cr and Pt on the third-order elastic constants and mechanical properties of NiAl

    KAUST Repository

    Wu, Shaohua

    2014-12-01

    Effects of Ni vacancy, Ni antisite in Al sublattice, Cr in Al sublattice, Pt in Ni sublattice on the second-order elastic constants (SOECs) and third-order elastic constants (TOECs) of the B2 NiAl have been investigated using the first-principles methods. Lattice constant and the SOECs of NiAl are in good agreement with the previous results. The brittle/ductile transition map based on Pugh ratio G/B and Cauchy pressure Pc shows that Ni antisite, Cr, Pt and pressure can improve the ductility of NiAl, respectively. Ni vacancy and lower pressure can enhance the Vickers hardness Hv of NiAl. The density of states (DOS) and the charge density difference are also used to analysis the effects of vacancy, Ni antisite, Cr and Pt on the mechanical properties of NiAl, and the results are in consistent with the transition map. © 2014 Elsevier Ltd. All rights reserved.

  18. Effect of Mn Concentration on Magneto-mechnaical Properties in Directionally Solidified Ferromagnetic Shape Memory Ni-Mn-Ga Alloys

    Directory of Open Access Journals (Sweden)

    R.K Singh

    2016-06-01

    Full Text Available Heusler type alloys Ni50Mn25+xGa25-x  (x=2,3,4 and 5 based on near stoichiometric Ni2MnGa compositions were directionally solidified using modified Bridgman method. The alloys thus prepared were characterized for their chemical composition, crystal structure, microstructure, phase transformation, magnetic  and magneto-mechanical properties. The directionally solidified Ni50Mn30Ga20 alloy rod exhibited maximum magnetocrystalline value of 95 kJm-3 and lowest detwinning stresses for martensite phase of about 5MPa. The reversible room temperature magnetic field induced strain of 0.2% under external magnetic field of 0.6T and 0.05kN bias load was obtained for the directionally solidified Ni50Mn30Ga20 alloy.

  19. Personal opinions of welding procedure qualification on 09 MnNiDR%09MnNiDR的焊接工艺评定的个人见解

    Institute of Scientific and Technical Information of China (English)

    闫峰

    2012-01-01

      09 MnNiDR (previously known as 0.5 Ni) steel is low alloy and low temperature steel in nearly 10 years development and the use, compared with 16 MnDR steel, 09 MnNiDR had a high impact toughness under the low temperature,even if In-70 ℃, still had the more than 27J impact energy,compared with 3.5Ni、9Ni steel, the cost of material are clearly reduced.%  09MnNiDR(以前称为0.5Ni)钢,是近10年研制并使用的低合金低温钢,09MnNiDR与16MnDR钢相比能够在较低的温度下有很高的冲击韧性,在-70℃时仍具有大于27J的冲击功,与3.5Ni、9Ni钢相比,在材料的成本上有明显降低.

  20. Evaluation of hot corrosion protection of Cr-Al and CoNiCrAlY on IN-738LC

    Energy Technology Data Exchange (ETDEWEB)

    Khajavi, M.R. [Niroo Research Institute - Chemistry and Materials Research Center - Metallurgy Dept. End of Pounak-e-Bakhtari, P.O.Box 14665-517, Post Code 1468617151, Blvd., Shahrak-e-Gharb, Tehran (Iran)]|[Shiraz University - Materials Science and Engineering Department, Engineering School, Shiraz University, Shiraz (Iran); Pasha, A. [Niroo Research Institute - Chemistry and Materials Research Center - Metallurgy Dept. End of Pounak-e-Bakhtari, P.O.Box 14665-517, Post Code 1468617151, Blvd., Shahrak-e-Gharb, Tehran (Iran); Shariat, M.H. [Shiraz University - Materials Science and Engineering Department, Engineering School, Shiraz University, Shiraz (Iran)

    2004-07-01

    A program was conducted to evaluate the relative corrosion resistance of CoNiCrAlY and Chromium modified Aluminide on IN738-LC, used for turbine blades. The corrosion experiments were performed in a laboratory tube furnace. The microstructure of coatings was characterized by using optical and scanning electron microscopy techniques. The results indicated that at a temperature of 800 deg. C the CoNiCrAlY is more protective than Cr-Al coating. (authors)

  1. Influence of carbon content on wear resistance and wear mechanism of Mn13Cr2 and Mn18Cr2 cast steels

    Directory of Open Access Journals (Sweden)

    Ding-shan Lu

    2015-01-01

    Full Text Available By means of impact abrasion tests, micro-hardness tests, and worn surface morphology observation via SEM, a comparison research based upon different impact abrasive wear conditions was conducted in this research to study the influence of different carbon contents (1.25wt.%, 1.35wt.%, and 1.45 wt.% on the wear resistance and wear mechanism of water-quenched Mn13Cr2 and Mn18Cr2 cast steels. The research results show that the wear resistance of the Mn18Cr2 cast steel is superior to that of the Mn13Cr2 cast steel under the condition of the same carbon content and different impact abrasive wear conditions because the Mn18Cr2 cast steel possesses higher worn work hardening capacity as well as a more desirable combination of high hardness and impact toughness than that of the Mn13Cr2 cast steel. When a 4.5 J impact abrasive load is applied, the wear mechanism of both steels is that plastic deformation fatigue spalling and micro-cutting coexist, and the former dominates. When the carbon content is increased, the worn work hardening effect becomes increasingly dramatic, while the wear resistance of both steels decreases, which implies that an increase in impact toughness is beneficial to improving the wear resistance under severe impact abrasive wear conditions. Under the condition of a 1.0 J impact abrasive load, the wear mechanism of both steels is that plastic deformation fatigue spalling and micro-cutting coexist, and the latter plays a leading role. The worn work hardening effect and wear resistance intensify when the carbon content is increased, which implies that a higher hardness can be conducive to better wear resistance under low impact abrasive condition.

  2. Hot corrosion performance of a NiCr coated Ni-based alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sidhu, T.S.; Prakash, S.; Agrawal, R.D. [Indian Institute of Technology, Roorkee (India)

    2006-07-15

    The hot corrosion performance of high velocity oxy-fuel sprayed Ni-20Cr wire coating on a Ni-based superalloy is evaluated for 1000 h at 900{sup o}C under cyclic conditions in a coal-fired boiler. The performance of bare and Ni-20Cr coated Superni 75 is assessed via thermogravimetric data, metal thickness loss corresponding to the corrosion scale formation, scale thickness loss and the depth of internal corrosion attack. The better hot corrosion resistance of the coated alloy is mainly attributed to the formation of a thick band of chromium oxide just above the scale-substrate interface and chromium oxide stringers along the splat boundaries, as well as to the nickel oxide and the dense and uniform fine grain structure of the as sprayed coating.

  3. Room-temperature ferromagnetism in Mn-doped CuCrO2 nanopowders

    Directory of Open Access Journals (Sweden)

    DENG Linyan

    2015-08-01

    Full Text Available (Cu1-xMnxCrO2 (0≤x≤6 at% and Cu(Cr1-yMnyO2 (0≤y≤6 at% nanopowders were prepared by combining solid-state reaction and ball milling.It is found that all the samples have a pure 3R-CuCrO2 delafossite structure.The lattice expansion supports the Mn entrance into the Cu and Cr sublattices,respectively,in (Cu1-xMnxCrO2 and Cu(Cr1-yMnyO2,which is further proved by X-ray photoelectron spectroscopy to some degree.Room-temperature ferromagnetism is achieved in B-site Mn-doped samples,originating from the hole-mediated Cr3+-Mn3+ double-exchange interaction.The saturation magnetization of this CuMO2 delafossite (M=Cr,Mn is about an order of magnitude higher than literature values,and gradually decreases with the Mn addition due to the combined influence of the number of the M-M pairs,the M-M distances and the hole density.

  4. 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.)

  5. Influence of Co substitution for Ni and Mn on the structural and electrochemical characteristics of LiNi 0.5Mn 1.5O 4

    Science.gov (United States)

    Ito, Atsushi; Li, Decheng; Lee, Yunsung; Kobayakawa, Koichi; Sato, Yuichi

    LiNi 0.5- xCo 2 xMn 1.5- xO 4 (0 ≤ 2 x ≤ 0.2) was prepared by spray drying, then re-annealing in O 2. Their structural and electrochemical properties were studied by ex-situ XRD, GITT, and charge-discharge testing. The substitution of cobalt for Ni and Mn in the LiNi 0.5Mn 1.5O 4 resulted in significant structural and electrochemical variations, such as the change in structural transformation with lithium extraction, the increase in the lithium diffusion coefficient and the decrease in the area specific impedance. Moreover, the improved kinetic properties caused by the Co substitution for Ni and Mn result in an improved cyclic performance at a high rate and at elevated temperature as well as the rate capability.

  6. Remarkably Improved Electrochemical Performance of Li- and Mn-Rich Cathodes upon Substitution of Mn with Ni.

    Science.gov (United States)

    Kumar Nayak, Prasant; Grinblat, Judith; Levi, Elena; Penki, Tirupathi Rao; Levi, Mikhael; Sun, Yang-Kook; Markovsky, Boris; Aurbach, Doron

    2017-02-08

    Li- and Mn-rich transition-metal oxides of layered structure are promising cathodes for Li-ion batteries because of their high capacity values, ≥250 mAh g(-1). These cathodes suffer from capacity fading and discharge voltage decay upon prolonged cycling to potential higher than 4.5 V. Most of these Li- and Mn-rich cathodes contain Ni in a 2+ oxidation state. The fine details of the composition of these materials may be critically important in determining their performance. In the present study, we used Li1.2Ni0.13Mn0.54Co0.13O2 as the reference cathode composition in which Mn ions are substituted by Ni ions so that their average oxidation state in Li1.2Ni0.27Mn0.4Co0.13O2 could change from 2+ to 3+. Upon substitution of Mn with Ni, the specific capacity decreases but, in turn, an impressive stability was gained, about 95% capacity retention after 150 cycles, compared to 77% capacity retention for Li1.2Ni0.13Mn0.54Co0.13O2 cathodes when cycled at a C/5 rate. Also, a higher average discharge voltage of 3.7 V is obtained for Li1.2Ni0.27Mn0.4Co0.13O2 cathodes, which decreases to 3.5 V after 150 cycles, while the voltage fading of cathodes comprising the reference material is more pronounced. The Li1.2Ni0.27Mn0.4Co0.13O2 cathodes also demonstrate higher rate capability compared to the reference Li1.2Ni0.13Mn0.54Co0.13O2 cathodes. These results clearly indicate the importance of the fine composition of cathode materials containing the five elements Li, Mn, Ni, Co, and O. The present study should encourage rigorous optimization efforts related to the fine composition of these cathode materials, before external means such as doping and coating are applied.

  7. An x-ray absorption spectroscopy study of Ni-Mn-Ga shape memory alloys.

    Science.gov (United States)

    Sathe, V G; Dubey, Aditi; Banik, Soma; Barman, S R; Olivi, L

    2013-01-30

    The austenite to martensite phase transition in Ni-Mn-Ga ferromagnetic shape memory alloys was studied by extended x-ray absorption fine structure (EXAFS) and x-ray absorption near-edge structure (XANES) spectroscopy. The spectra at all the three elements', namely, Mn, Ga and Ni, K-edges in several Ni-Mn-Ga samples (with both Ni and Mn excess) were analyzed at room temperature and low temperatures. The EXAFS analysis suggested a displacement of Mn and Ga atoms in opposite direction with respect to the Ni atoms when the compound transforms from the austenite phase to the martensite phase. The first coordination distances around the Mn and Ga atoms remained undisturbed on transition, while the second and subsequent shells showed dramatic changes indicating the presence of a modulated structure. The Mn rich compounds showed the presence of antisite disorder of Mn and Ga. The XANES results showed remarkable changes in the unoccupied partial density of states corresponding to Mn and Ni, while the electronic structure of Ga remained unperturbed across the martensite transition. The post-edge features in the Mn K-edge XANES spectra changed from a double peak like structure to a flat peak like structure upon phase transition. The study establishes strong correlation between the crystal structure and the unoccupied electronic structure in these shape memory alloys.

  8. Spin reversal in Gd(Me,MnO3 (Me = Co, Ni

    Directory of Open Access Journals (Sweden)

    Gutiérrez, D.

    2004-06-01

    Full Text Available Partial substitution of the rare-earth by calcium at the cationic site of the ABO3 perovskites may show extraordinary effects of spin reversal due to a negative polarization between the rare-earth and the manganese networks, as it occurs in the solid solution Gd1‑xCaxMnO3. We present herein similar effects in gadolinium perovskites of the Gd(Me,MnO3 type, in which the manganese sublattice has been partially substituted by transition metal elements Me, leaving the gadolinium network intact. The spin reversal phenomena is observed at a critical concentration of x(Me = 1/3, which implies an optimum number of pairs Mn3+-Mn4+. Néel temperatures of 48 and 67 K are obtained for Me = Co and Ni, respectively, at the optimum concentration of substituent. A comparison between these different solid solutions allows us to generalize the interpretation of two interacting magnetic sublattices : a Mn-based ferromagnetic one and a negatively-aligned gadolinium network.La sustitución parcial del lantánido por el elemento calcio en el sitio catiónico (sitio A de la perovskita ABO3 puede dar lugar a efectos importantes ligados a una inversión del espín. Dicha inversión se debe a una interacción negativa entre la tierra rara y la subred de manganeso, tal como ocurre en la solución solida Gd1-xCaxMnO3. Se presentan en este trabajo efectos similares que ocurren en las perovskitas de gadolinio de fórmula Gd(Me,MnO3, en las cuales la subred de manganeso (sitio B ha sido reemplazada parcialmente por otros metales de transición Me, dejando intacta la subred de gadolinio. Se observa el fenómeno de inversión de espín para una concentración crítica x(Me = 1/3, para la cual se logra una cantidad óptima de pares Mn3+‑Mn4+. Para esta concentración crítica se observan temperaturas de Néel antiferromagnéticas del orden de 48 y 67 K, respectivamente para Me = Co y Ni. Un análisis comparativo entre estos diferentes sistemas permite generalizar la

  9. 53Mn-53Cr chronology of Ca-Fe silicates in CV3 chondrites

    Science.gov (United States)

    MacPherson, Glenn J.; Nagashima, Kazuhide; Krot, Alexander N.; Doyle, Patricia M.; Ivanova, Marina A.

    2017-03-01

    High precision secondary ion mass-spectrometry (SIMS) analyses of kirschsteinite (CaFeSiO4) in the reduced CV3 chondrites Vigarano and Efremovka yield well resolved 53Cr excesses that correlate with 55Mn/52Cr, demonstrating in situ decay of the extinct short-lived radionuclide 53Mn. To ensure proper correction for relative sensitivities between 55Mn+ and 52Cr+ ions, we synthesized kirschsteinite doped with Mn and Cr to measure the relative sensitivity factor. The inferred initial ratio (53Mn/55Mn)0 in chondritic kirschsteinite is (3.71 ± 0.50) × 10-6. When anchored to 53Mn-53Cr relative and U-corrected 207Pb-206Pb absolute ages of the D'Orbigny angrite, this ratio corresponds to kirschsteinite formation 3.2-0.7+08 Ma after CV Ca-, Al-rich inclusions. The kirschsteinite data are consistent within error with the data for aqueously-formed fayalite from the Asuka 881317 CV3 chondrite as reported by Doyle et al. (2015), supporting the idea that Ca-Fe silicates in CV3 chondrites are cogenetic with fayalite (and magnetite) and formed during metasomatic alteration on the CV3 parent body. Concentrically-zoned crystals of kirschsteinite and hedenbergite indicate that they initially formed as near end-member compositions that became more Mg-rich with time, possibly as a result of an increase in temperature.

  10. 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.

  11. The Thermal Transformation Arrest Phenomenon in NiCoMnAl Heusler Alloys

    Directory of Open Access Journals (Sweden)

    Rie Y. Umetsu

    2013-08-01

    Full Text Available In this report, we present findings of systematic research on NiCoMnAl alloys, with the purpose of acquiring a higher thermal transformation arrest temperature (TA. By systematic research, TA in the NiCoMnAl alloy systems was raised up to 190 K, compared to the highest TA of 130 K in NiCoMnIn. For a selected alloy of Ni40Co10Mn33Al17, magnetization measurements were performed under a pulsed high magnetic field, and the critical magnetic field-temperature phase diagram was determined. The magnetic phase diagram for Ni50-xCoxMn50-yAly was also established. Moreover, from the discussion that the formerly called “kinetic arrest phenomenon” has both thermodynamic and kinetic factors, we suggest a terminology change to the “thermal transformation arrest phenomenon”.

  12. Effects of helium injection mode on void formation in Fe-Ni-Cr alloys

    Science.gov (United States)

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

    1988-09-01

    The effect of the helium injection mode on void formation during ion irradiation of the pure solution-annealing alloys Fe-15Ni-7Cr, Fe-35Ni-7Cr, Fe-45Ni-7Cr, Fe-10Ni-13Cr, Fe-40Ni-13Cr, Fe-45Ni-15Cr was examined. Ion irradiation was carried out with 4 MeV Ni ions at 948 K to doses of 30 to 100 dpa with: (1) no helium injection, (2) simultaneous helium injection and (3) helium preinjection and aging. Swelling variation with helium injection differed among the 7Cr alloys and 13-15Cr alloys. Only the simultaneous helium injection mode produced a bimodal cavity size distribution in the high Ni alloys. The critical radius, as estimated from the cavity size distributions appears to have increased with increasing dose, but no clear variation of the critical radius with composition was observed. Helium preinjection and one-hour aging at 948 K formed helium bubbles along the residual dislocations, while subsequent Ni irradiation caused void formation along the dislocation lines. The calculated helium concentration deduced from observable helium bubbles was low compared with the injected helium concentration in the alloys containing higher Ni and lower Cr.

  13. Sliding wear behaviors of electrodeposited Ni composite coatings containing micrometer and nanometer Cr particles

    Institute of Scientific and Technical Information of China (English)

    ZHAO Guo-gang; ZHOU Yue-bo; ZHANG Hai-jun

    2009-01-01

    Micrometer and nanometer Cr particles were co-deposited with Ni by electroplating from a nickel sulfate bath containing a certain content of Cr particles. Cr microparticles are in a size range of 1-5 (m and Cr nanoparticles have an average size of 40 nm. The friction and the wear performance of the co-deposited Ni-Cr composite coatings were comparatively evaluated by sliding against Si3N4 ceramic balls under non-lubricated conditions. It is found that the incorporation of Cr particles enhances the microhardness and wear resistance of Ni coatings. The wear resistance of Ni composite coating containing Cr nanoparticles is higher than that of the Ni composite coating containing Cr microparticles with a comparable Cr particle content. The co-deposition of smaller nanometer Cr particles with Ni effectively reduces the size of Ni crystals and significantly increases the hardness of the composite coatings due to grain-refinement strengthening and dispersion-strengthening, resulting in a significant improvement of wear resistance of the Ni-Cr nanocomposite coatings.

  14. Magnetic analysis of martensitic and austenitic phases in metamagnetic NiMn(In, Sn) alloys

    Energy Technology Data Exchange (ETDEWEB)

    Lázpita, P., E-mail: patricia.lazpita@ehu.es [University of Basque Country (UPV/EHU), Leioa (Spain); Escolar, J. [University of Basque Country (UPV/EHU), Leioa (Spain); Chernenko, V.A. [University of Basque Country (UPV/EHU), Leioa (Spain); BCMaterials, Parque Tecnológico de Bizkaia, Ed. 500, Derio 48160 (Spain); Ikerbasque, Basque Foundation for Science, Bilbao 48013 (Spain); Barandiarán, J.M. [University of Basque Country (UPV/EHU), Leioa (Spain); BCMaterials, Parque Tecnológico de Bizkaia, Ed. 500, Derio 48160 (Spain)

    2015-09-25

    Highlights: • NiMnIn austenite and martensite have similar Ising-type critical exponents. • NiMnIn critical exponents rule out disordered states as spin-glass in martensite. • In NiMnIn alloys, magnetism arises mainly from moments localized at Mn atoms. • NiCoMnSn critical exponents are close to the ones from tricritical mean field model. • NiCoMnSn complex magnetic state results from three different magnetic atoms. - Abstract: Two different metamagnetic shape memory alloys of nominal composition Ni{sub 50}Mn{sub 36}In{sub 14} and Ni{sub 42}Co{sub 8}Mn{sub 39}Sn{sub 11} have been studied by means of modified Arrott plots to give insight into the magnetic states of both the austenitic and martensitic phases. For Ni{sub 50}Mn{sub 36}In{sub 14} alloy, the same critical exponents (β = 0.32 and γ = 2.0) are obtained in austenite and martensite. They suggest that localized moments at Mn atoms are responsible for the magnetism of both phases according to the Ising model. The martensite, however, displays a rather complex behavior because β continuously changes with temperature. In Ni{sub 43}Co{sub 6.5}Mn{sub 39}Sn{sub 11.5}, critical exponents in the austenite are β = 0.27 and γ = 1.0. They are close to the tricritical mean field model, but no reliable fits were obtained in the martensite. The results are discussed in terms of microscopically different magnetic states in two alloys reflecting a complex interplay between the ferromagnetic and antiferromagnetic contributions.

  15. Effect of Cr and Ni on diffusion bonding of Fe3Al with steel

    Indian Academy of Sciences (India)

    Wang Juan; Li Yajiang; Ma Haijun

    2005-02-01

    Microstructure at the diffusion bonding interface between Fe3Al and steel including Q235 low carbon steel and Cr18–Ni8 stainless steel was analysed and compared by means of scanning electron microscopy and transmission electron microscopy. The effect of Cr and Ni on microstructure at the Fe3Al/steel diffusion bonding interface was discussed. The experimental results indicate that it is favourable for the diffusion of Cr and Ni at the interface to accelerate combination of Fe3Al and steel during bonding. Therefore, the width of Fe3Al/Cr18–Ni8 interface transition zone is more than that of Fe3Al/Q235. And Fe3Al dislocation couples with different distances, even dislocation net occurs at the Fe3Al/Cr18–Ni8 interface because of the dispersive distribution of Cr and Ni in Fe3Al phase.

  16. A sulfur segregation study of PWA 1480, NiCrAl, and NiAl alloys

    Science.gov (United States)

    Jayne, D. T.; Smialek, J. L.

    1993-01-01

    Some nickel based superalloys show reduced oxidation resistance from the lack of an adherent oxide layer during high temperature cyclic oxidation. The segregation of sulfur to the oxide-metal interface is believed to effect oxide adhesion, since low sulfur alloys exhibit enhanced adhesion. X ray Photoelectron Spectroscopy (XPS) was combined with an in situ sample heater to measure sulfur segregation in NiCrAl, PWA 1480, and NiAl alloys. The polished samples with a 1.5 to 2.5 nm (native) oxide were heated from 650 to 1100 C with hold times up to 6 hr. The sulfur concentration was plotted as a function of temperature versus time at temperature. One NiCrAl sulfur study was performed on the same casting used by Browning to establish a base line between previous Auger Electron Spectroscopy (AES) results and the XPS results of this study. Sulfur surface segregation was similar for PWA 1480 and NiCrAl and reached a maximum of 30 at% at 800 to 850 C. Above 900 C the sulfur surface concentration decreased to about 3 at% at 1100 C. These results are contrasted to the minimal segregation observed for low sulfur hydrogen annealed materials which exhibit improved scale adhesion.

  17. Sintering behaviour and mechanical properties of Cr3C2–NiCr cermets

    Indian Academy of Sciences (India)

    A Özer; Y K Tür

    2013-10-01

    Cr3C2–NiCr cermets are used as metal cutting tools due to their relatively high hardness and low sintering temperatures. In this study, a powder mixture consisting of 75 wt% Cr3C2–25 wt% NiCr was sintered at four different temperatures and characterized for itsmicrostructure and mechanical properties. The highest relative density obtained was 97% when sintered at 1350 °C. As the relative density increased, elastic modulus, transverse rupture strength, fracture toughness and hardness of the samples reached to a maximum of 314 GPa, 810 MPa, 10.4 MPa.m1/2 and 11.3 GPa, respectively. However, sintering at 1400 °C caused further grain growth and pore coalescence which resulted in decreasing density and degradation of all mechanical properties. Fracture surface investigation showed that the main failure mechanism was the intergranular fracture of ceramic phase accompanied by the ductile fracture of the metal phase which deformed plastically during crack propagation and enhanced the fracture toughness.

  18. The role of particle size on the electrochemical properties at 25 and at 55 deg. C of the LiCr{sub 0.2}Ni{sub 0.4}Mn{sub 1.4}O{sub 4} spinel as 5 V-cathode materials for lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Aklalouch, Mohamed [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas (CSIC) c/Sor Juana Ines de la Cruz, 3 28049-Madrid (Spain); ECME, Faculte des Sciences et Techniques Marrakech, Universite Cadi Ayyad, Av. A. El Khattabi, B.P.549 Marrakech (Morocco); Rojas, Rosa M.; Rojo, Jose Maria [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas (CSIC) c/Sor Juana Ines de la Cruz, 3 28049-Madrid (Spain); Saadoune, Ismael [ECME, Faculte des Sciences et Techniques Marrakech, Universite Cadi Ayyad, Av. A. El Khattabi, B.P.549 Marrakech (Morocco); Amarilla, Jose Manuel, E-mail: amarilla@icmm.csic.e [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas (CSIC) c/Sor Juana Ines de la Cruz, 3 28049-Madrid (Spain)

    2009-12-01

    The role of the particle size on the electrochemical properties at 25 and at 55 deg. C of the LiCr{sub 0.2}Ni{sub 0.4}Mn{sub 1.4}O{sub 4} spinel synthesized by combustion method has been determined. Samples with different particle size were obtained by heating the raw spinel from 700 to 1100 deg. C, for 1 h in air. X-ray diffraction patterns revealed that all the prepared materials are single-phase spinels. The main effect of the thermal treatment is the remarkable increase of the particles size from approx60 to approx3000 nm as determined by transmission electron microscopy. The electrochemical properties were determined at high discharge currents (1C rate) in two-electrode Li-cells. At 25 and at 55 deg. C, in spite of the great differences in particle size, the discharge capacity drained by all samples is similar (Q{sub dch} approx 135 mAh g{sup -1}). Instead, the cycling performances strongly change with the particle size. The spinels with PHI > 500 nm show better cycling stability at 25 and at 55 deg. C than those with PHI < 500 nm. The samples heated at 1000 and 1100 deg. C, with high potential (E approx 4.7 V), elevate capacity (Q approx 135 mAh g{sup -1}), and remarkable cycling performances (capacity retention after 250 cycles >96%) are very attractive materials as 5V-cathodes for high-energy Li-ion batteries.

  19. Oxidation sulfidation resistance of Fe-Cr-Ni alloys

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, Ken (Naperville, IL); Baxter, David J. (Woodridge, IL)

    1984-01-01

    High temperature resistance of Fe-Cr-Ni alloy compositions to oxidative and/or sulfidative conditions is provided by the incorporation of about 1-8 wt. % of Zr or Nb and results in a two-phase composition having an alloy matrix as the first phase and a fine grained intermetallic composition as the second phase. The presence and location of the intermetallic composition between grains of the matrix provides mechanical strength, enhanced surface scale adhesion, and resistance to corrosive attack between grains of the alloy matrix at temperatures of 500.degree.-1000.degree. C.

  20. Effect of Cr/C Ratio on Microstructure and Corrosion Performance of Cr3C2-NiCr Composite Fabricated by Laser Processing

    Science.gov (United States)

    Lou, Deyuan; Liu, Dun; He, Chunlin; Bennett, Peter; Chen, Lie; Yang, Qibiao; Fearon, Eamonn; Dearden, Geoff

    2016-01-01

    The present study focuses on the effect of different Cr/C ratios on the microstructure, microhardness, and corrosion resistance of Ni-based laser clad hardfacings, reinforced by in situ synthesized chromium carbide particles. Cr3C2-NiCr composites have been laser processed with graphite/Cr/Ni powder blends with varying Cr/C ratios. Following phase analysis (x-ray diffraction) and microstructure investigation (scanning electron microscopy; energy dispersive x-ray analysis; transmission electron microscopy), the solidification of laser melt pool is discussed, and the corrosion resistances are examined. Several different zones (planar, dendritic, eutectic and re-melt zone) were formed in these samples, and the thicknesses and shapes of these zones vary with the change of Cr/C ratio. The sizes and types of carbides and the content of reserved graphite in the composites change as the Cr/C ratio varies. With the content of carbides (especially Cr3C2) grows, the microhardness is improved. The corrosive resistance of the composites to 0.2M H2SO4 aqueous solution decreases as the Cr/C ratio reduces owing to not only the decreasing Cr content in the NiCr matrix but also the galvanic corrosion formed within the carbide and graphite containing Ni matrix.

  1. Spin-driven ordering of Cr in the equiatomic high entropy alloy NiFeCrCo

    Energy Technology Data Exchange (ETDEWEB)

    Niu, C.; Zaddach, A. J.; Oni, A. A.; Sang, X.; LeBeau, J. M.; Koch, C. C.; Irving, D. L., E-mail: dlirving@ncsu.edu [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Hurt, J. W. [Department of Physics, Furman University, Greenville, South Carolina 29613 (United States)

    2015-04-20

    Spin-driven ordering of Cr in an equiatomic fcc NiFeCrCo high entropy alloy (HEA) was predicted by first-principles calculations. Ordering of Cr is driven by the reduction in energy realized by surrounding anti-ferromagnetic Cr with ferromagnetic Ni, Fe, and Co in an alloyed L1{sub 2} structure. The fully Cr-ordered alloyed L1{sub 2} phase was predicted to have a magnetic moment that is 36% of that for the magnetically frustrated random solid solution. Three samples were synthesized by milling or casting/annealing. The cast/annealed sample was found to have a low temperature magnetic moment that is 44% of the moment in the milled sample, which is consistent with theoretical predictions for ordering. Scanning transmission electron microscopy measurements were performed and the presence of ordered nano-domains in cast/annealed samples throughout the equiatomic NiFeCrCo HEA was identified.

  2. Resistance behaviour and interdiffusion of layered CuNi-NiCr films

    Energy Technology Data Exchange (ETDEWEB)

    Brueckner, W. [Institut fuer Festkoerper- und Werkstofforschung Dresden e.V. (Germany); Schumann, J. [Institut fuer Festkoerper- und Werkstofforschung Dresden e.V. (Germany); Baunack, S. [Institut fuer Festkoerper- und Werkstofforschung Dresden e.V. (Germany); Pitschke, W. [Institut fuer Festkoerper- und Werkstofforschung Dresden e.V. (Germany); Knuth, T. [Microtech GmbH, Teltow (Germany)

    1995-03-15

    On the basis of sputtered NiCr/CuNi/NiCr triple layers and multilayers, investigations of the electrical resistance R and its temperature coefficient TCR, as well as of the concentration depth profiles and of the temperature dependence of the lattice parameter have been carried out to study the influences of the interfaces in the as-deposited state as well as annealed ones. Furthermore, the temperature dependence of the film stress has been considered. As to the resistance, the influence of the diffusion zone can be described by a parallel resistor R{sub i} having {Delta}TCR{sub i}. These quantities are dependent on both deposition and annealing and were determined for the two configurations on silicon wafers in the as-deposited state as well as in the 300 C annealed one. The AES investigations show distinct interdiffusion effects after annealing above 300 C. The Ni impoverishment observed in the CuNi results in a lattice parameter decrease. The film stress is only slightly influenced by interfacial effects. ((orig.))

  3. Effects of Cr and Ni on interdiffusion and reaction between U and Fe–Cr–Ni alloys

    Energy Technology Data Exchange (ETDEWEB)

    Huang, K.; Park, Y.; Zhou, L.; Coffey, K.R. [Advanced Materials Processing and Analysis Center, Department of Materials Science and Engineering, University of Central Florida, Orlando, FL (United States); Sohn, Y.H., E-mail: Yongho.Sohn@ucf.edu [Advanced Materials Processing and Analysis Center, Department of Materials Science and Engineering, University of Central Florida, Orlando, FL (United States); Sencer, B.H.; Kennedy, J.R. [Fundamental Fuel Properties Department, Nuclear Fuel and Materials Division Idaho National Laboratory, Idaho Falls, ID (United States)

    2014-08-01

    Metallic U-alloy fuel cladded in steel has been examined for high temperature fast reactor technology wherein the fuel cladding chemical interaction is a challenge that requires a fundamental and quantitative understanding. In order to study the fundamental diffusional interactions between U with Fe and the alloying effect of Cr and Ni, solid-to-solid diffusion couples were assembled between pure U and Fe, Fe–15 wt.%Cr or Fe–15 wt.%Cr–15 wt.%Ni alloy, and annealed at high temperature ranging from 580 to 700 °C. The microstructures and concentration profiles that developed from the diffusion anneal were examined by scanning electron microscopy, and X-ray energy dispersive spectroscopy (XEDS), respectively. Thick U{sub 6}Fe and thin UFe{sub 2} phases were observed to develop with solubilities: up to 2.5 at.% Ni in U{sub 6}(Fe,Ni), up to 20 at.%Cr in U(Fe, Cr){sub 2}, and up to 7 at.%Cr and 14 at.% Ni in U(Fe, Cr, Ni){sub 2}. The interdiffusion and reactions in the U vs. Fe and U vs. Fe–Cr–Ni exhibited a similar temperature dependence, while the U vs. Fe–Cr diffusion couples, without the presence of Ni, yielded greater activation energy for the growth of intermetallic phases – lower growth rate at lower temperature but higher growth rate at higher temperature.

  4. Bonding Ni-Cr alloy to tooth structure with adhesive resin cements.

    Science.gov (United States)

    Penugonda, B; Scherer, W; Cooper, H; Kokoletsos, N; Koifman, V

    1992-01-01

    This study was to determine the shear bond strengths of Ni-Cr alloy to Ni-Cr alloy (Group I), Ni-Cr alloy to enamel (Group II), and Ni-Cr alloy to dentin (Group III) using Imperva Dual, DC Metabond, All-Bond, Geristore, and Panavia. All bonded specimens were thermocycled 2000 x (5 degrees C-55 degrees C) after 24 hours and subjected to shear bond testing on a Universal Instron Testing Machine. In all groups of the study, Imperva Dual and CB Metabond had significantly (p bond values than Panavia.

  5. Morphological, structural, microhardness and corrosion characterisations of electrodeposited Ni-Mo and Cr coatings

    National Research Council Canada - National Science Library

    Lima-Neto, Pedro de; Correia, Adriana N; Vaz, Gustavo L; Casciano, Paulo N. S

    2010-01-01

    The corrosion resistance of electrodeposited Cr and Ni-Mo coatings and the influence of heat treatment on the crystallographic structure, morphology and microhardness properties were investigated here...

  6. A thermodynamic analysis of the system Fe-Cr-Ni-C-O

    OpenAIRE

    Luoma, Rauno

    2002-01-01

    A thermodynamic database for the system Fe-Cr-Ni-C-O has been built using previously assessed binary and ternary systems. Six ternary systems, Fe-Cr-O, Fe-C-O, Fe-Ni-O, Cr-Ni-O, Cr-C-O, and Ni-C-O, have been assessed. Quaternary and quinary systems were calculated using only interpolation models. This method of building a database is known as the Calphad method and it is widely used in modern thermodynamics. An associated solution model with a non-ideally interacting species, namely 'Fe',...

  7. Phase stability and magnetic behavior of FeCrCoNiGe high-entropy alloy

    Science.gov (United States)

    Huang, Shuo; Vida, Ádám; Molnár, Dávid; Kádas, Krisztina; Varga, Lajos Károly; Holmström, Erik; Vitos, Levente

    2015-12-01

    We report an alternative FeCrCoNiGe magnetic material based on FeCrCoNi high-entropy alloy with Curie point far below the room temperature. Investigations are done using first-principles calculations and key experimental measurements. Results show that the equimolar FeCrCoNiGe system is decomposed into a mixture of face-centered cubic and body-centered cubic solid solution phases. The increased stability of the ferromagnetic order in the as-cast FeCrCoNiGe composite, with measured Curie temperature of 640 K, is explained using the exchange interactions.

  8. Promising Cu-Ni-Cr-Si alloy for first wall ITER applications

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, A. [Research and Development Inst. of Power Engineering, Moscow (Russian Federation); Abramov, V. [Research and Development Inst. of Power Engineering, Moscow (Russian Federation); Rodin, M. [Research and Development Inst. of Power Engineering, Moscow (Russian Federation)

    1996-10-01

    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 {proportional_to}0.2 dpa at 293 C are investigated. Embrittlement of Cu-Ni-Cr-Si alloy can be avoided by annealing. (orig.).

  9. Magnetodielectric coupling in frustrated spin systems: the spinels MCr{sub 2}O{sub 4} (M = Mn, Co and Ni)

    Energy Technology Data Exchange (ETDEWEB)

    Mufti, N; Nugroho, A A; Blake, G R; Palstra, T T M [Solid State Chemistry Laboratory, Zernike Institute for Advanced Materials, Rijksuniversiteit Groningen, Nijenborgh 4, 9747AG Groningen (Netherlands)

    2010-02-24

    We have studied the magnetodieletric coupling of polycrystalline samples of the spinels MCr{sub 2}O{sub 4} (M = Mn, Co and Ni). Dielectric anomalies are clearly observed at the onset of the magnetic spiral structure (T{sub s}) and at the 'lock-in' transition (T{sub f}) in MnCr{sub 2}O{sub 4} and CoCr{sub 2}O{sub 4}, and also at the onset of the canted structure (T{sub s}) in NiCr{sub 2}O{sub 4}. The strength of the magnetodielectric coupling in this system can be explained by spin-orbit coupling. Moreover, the dielectric response in an applied magnetic field scales with the square of the magnetization for all three samples. Thus, the magnetodielectric coupling in this state appears to originate from the P{sup 2}M{sup 2} term in the free energy.

  10. Impact of Mn(II)-Manganese Oxide Reactions on Ni and Zn Speciation.

    Science.gov (United States)

    Hinkle, Margaret A G; Dye, Katherine G; Catalano, Jeffrey G

    2017-03-01

    Layered Mn oxide minerals (phyllomanganates) often control trace metal fate in natural systems. The strong uptake of metals such as Ni and Zn by phyllomanganates results from adsorption on or incorporation into vacancy sites. Mn(II) also binds to vacancies and subsequent comproportionation with structural Mn(IV) may alter sheet structures by forming larger and distorted Mn(III)O6 octahedra. Such Mn(II)-phyllomanganate reactions may thus alter metal uptake by blocking key reactive sites. Here we investigate the effect of Mn(II) on Ni and Zn binding to phyllomanganates of varying initial vacancy content (δ-MnO2, hexagonal birnessite, and triclinic birnessite) at pH 4 and 7 under anaerobic conditions. Dissolved Mn(II) decreases macroscopic Ni and Zn uptake at pH 4 but not pH 7. Extended X-ray absorption fine structure spectroscopy demonstrates that decreased uptake at pH 4 corresponds with altered Ni and Zn adsorption mechanisms. These metals transition from binding in the interlayer to sheet edges, with Zn increasing its tetrahedrally coordinated fraction. These effects on metal uptake and binding correlate with Mn(II)-induced structural changes, which are more substantial at pH 4 than 7. Through these structural effects and the pH-dependence of Mn(II)-metal competitive adsorption, system pH largely controls metal binding to phyllomanganates in the presence of dissolved Mn(II).

  11. Magnetic phase transitions in PrMn 2- xCr xGe 2

    Science.gov (United States)

    Dincer, I.; Elerman, Y.; Elmali, A.; Ehrenberg, H.; Fuess, H.; Duman, E.; Acet, M.

    2002-07-01

    The structural and magnetic properties of PrMn 2- xCr xGe 2 (0⩽ x⩽1.0) were studied by X-ray diffraction and magnetization measurements. The powder samples crystallize in the ThCr 2Si 2-type structure, and the lattice constants at room temperature show almost no variation as Cr substitutes Mn. The observed phase transitions are summarized in a proposed magnetic x- T phase diagram and compared with previous Moessbauer spectroscopy and neutron diffraction results for x=0.

  12. Synthesis and characterization of NiMnIn nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Aksoy, Seda, E-mail: eaksoy@itu.edu.tr

    2015-01-01

    The off-stoichiometric Ni{sub 50}Mn{sub 34}In{sub 16} intermetalic Heusler nanoparticles have been prepared by laser ablation in distilled water from the target alloy using femtosecond laser system. The properties of the particles were characterized by electron microscopy and magnetometer techniques. The particle mean size of 28 nm was estimated by using the scanning electron microscopy images. However, the transmission electron microscopy results revealed that spherical cluster-like particles have been also produced. The magnetic field-induced structural transition was found in the particles with a starting temperature of around 250 K. - Highlights: • Ni–Mn–In Heusler nanoparticles are prepared by laser ablation method. • Structural properties are characterized by SEM and TEM. • Magnetic properties are discussed by the temperature-dependent magnetization and the magnetic field-dependent magnetization measurements.

  13. Thermodynamic stability of austenitic Ni-Mn-Cu cast iron

    Directory of Open Access Journals (Sweden)

    A. Janus

    2014-07-01

    Full Text Available The performed research was aimed at determining thermodynamic stability of structures of Ni-Mn-Cu cast iron castings. Examined were 35 alloys. The castings were tempered at 900 °C for 2 hours. Two cooling speeds were used: furnace-cooling and water-cooling. In the alloys with the nickel equivalent value less than 20,0 %, partial transition of austenite to martensite took place. The austenite decomposition ratio and the related growth of hardness was higher for smaller nickel equivalent value and was clearly larger in annealed castings than in hardened ones. Obtaining thermodynamically stable structure of castings requires larger than 20,0 % value of the nickel equivalent.

  14. Electronic, structural, and magnetic properties of the quaternary Heusler alloy NiCoMnZ (Z=Al, Ge, and Sn)

    Energy Technology Data Exchange (ETDEWEB)

    Halder, Madhumita, E-mail: mhalder@phy.iitb.ac.in [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Mukadam, M.D. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Suresh, K.G., E-mail: suresh@phy.iitb.ac.in [Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 (India); Yusuf, S.M. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2015-03-01

    The electronic, magnetic, and structural properties of the Heusler alloys NiCoMnZ (Z=Al, Ge, and Sn) have been investigated both theoretically and experimentally. NiCoMnGe and NiCoMnSn have ordered cubic Heusler structure (with a possible disorder between Ni and Co), while NiCoMnAl has a B2 type disordered Heusler structure with random occupancy between Mn and Al atom at their crystallographic sites. Electronic structure calculation shows that NiCoMnGe and NiCoMnSn are normal ferromagnets, whereas NiCoMnAl is nearly half metallic (∼100% spin polarization) in nature with its magnetic moment close to an integer value following the Slater–Pauling rule. Ab-initio calculations show ∼56% and ∼60% spin polarization for NiCoMnGe and NiCoMnSn, respectively. Magnetization measurements show all the three compounds have a high Curie temperature (>583 K). - Highlights: • Electronic, magnetic, and structural properties of Heusler alloys NiCoMnZ (Z=Al, Ge, and Sn) have been investigated. • NiCoMnGe and NiCoMnSn are normal ferromagnets, while NiCoMnAl is nearly half metallic. • All the three compounds have a high Curie temperature. • NiCoMnGe and NiCoMnSn have ordered cubic structure; while NiCoMnAl has a B2 type disordered structure.

  15. NiCrAl/Ni3Al微叠层材料的断裂韧度测算%Measurement and Calculation for Fracture Toughness of NiCrAl/Ni3Al Microlaminates

    Institute of Scientific and Technical Information of China (English)

    关春龙; 左宏森; 祁颖; 马李

    2008-01-01

    利用电子束物理气相沉积技术(EB-PVD)制备了NiCrAl/Ni3Al微叠层复合材料.建立了具有中心穿透裂纹有限宽NiCrAl叠层的Ⅰ型裂纹扩展模型,推导出它的断裂韧度表达式,并利用带预制裂纹的NiCrAl/Ni3Al叠层试样的四点弯曲断裂数据,估算出NiCrAl的断裂韧度,叠层后增强Ni3Al单体的断裂抗力.实验结果表明,制备态NiCrAl/Ni3Al微叠层复合材料试样的拉伸断口呈现出裂纹扩展和裂纹瞬断两个区域;随着温度的升高,塑性增加.

  16. Effects of Mn on the mechanical properties and high temperature oxidation of 9Cr2WVTa steel

    Science.gov (United States)

    Jin, Xiaojie; Chen, Shenghu; Rong, Lijian

    2017-10-01

    The mechanical properties and high temperature oxidation behaviors of 9Cr2WVTa steels with Mn contents in the range of 0.04-0.93 wt% were investigated. There are no obvious differences in the tensile properties at room temperature and high temperature, only a slight reduction in the impact toughness when Mn content reaches 0.93 wt%. Remarkably, the high temperature oxidation resistance is significantly improved with an increase of Mn content. After 500 h of oxidation, a (Fe0.6Cr0.4)2O3 oxide scale is developed on the steel with 0.04 wt% Mn, Mn1.5Cr1.5O4 oxides are occasionally detected when Mn content reaches 0.47 wt%, while a thin compact scale with a mixture of Mn1.5Cr1.5O4 and Cr1.3Fe0.7O3 oxides is formed on the steel containing 0.93 wt% Mn. Addition of Mn promotes the formation of Mn-oxides, which lowers oxygen partial pressure and accelerates external oxidation of Cr. At last, the presence of Mn-Cr spinels and Cr-rich oxides improves the oxidation resistance.

  17. Hydroxyapatite coating on pretreated CoNiCrMo prosthesis

    Institute of Scientific and Technical Information of China (English)

    WANG Tao; A. Dorner-Reisel

    2005-01-01

    In order to improve the quality of the bio-active coating on medical grade CoNiCrMo substrate, hydroxyapatite(HA) coatings were produced via low-temperature dip-coating route on substrates treated using various surface pre-treating methods. The surface and cross-sectional morphologies of HA coatings were observed by SEM, as well as the bonding strength between coatings and substrates after different pre-treatments were characterized according to ASTM C633. The low-temperature HA dip-coating method with the substrate merely oxidized at 600℃ can provide a high quality HA coating for CoNiCrMo, of which the bonding strength reaches (58±5)MPa, higher than that of the clinically used HA coatings on Ti-alloys produced via plasma spray route, as well as a HA coating with full crystallinity and high phase-purity, which is more in-vivo stable than plasma sprayed HA coating.

  18. Neutron diffraction studies of the Na-ion battery electrode materials NaCoCr2(PO4)3, NaNiCr2(PO4)3, and Na2Ni2Cr(PO4)3

    Science.gov (United States)

    Yahia, H. Ben; Essehli, R.; Avdeev, M.; Park, J.-B.; Sun, Y.-K.; Al-Maadeed, M. A.; Belharouak, I.

    2016-06-01

    The new compounds NaCoCr2(PO4)3, NaNiCr2(PO4)3, and Na2Ni2Cr(PO4)3 were synthesized by sol-gel method and their crystal structures were determined by using neutron powder diffraction data. These compounds were characterized by galvanometric cycling and cyclic voltammetry. NaCoCr2(PO4)3, NaNiCr2(PO4)3, and Na2Ni2Cr(PO4)3 crystallize with a stuffed α-CrPO4-type structure. The structure consists of a 3D-framework made of octahedra and tetrahedra that are sharing corners and/or edges generating channels along [100] and [010], in which the sodium atoms are located. Of significance, in the structures of NaNiCr2(PO4)3, and Na2Ni2Cr(PO4)3 a statistical disorder Ni2+/Cr3+ was observed on both the 8g and 4a atomic positions, whereas in NaCoCr2(PO4)3 the statistical disorder Co2+/Cr3+ was only observed on the 8g atomic position. When tested as negative electrode materials, NaCoCr2(PO4)3, NaNiCr2(PO4)3, and Na2Ni2Cr(PO4)3 delivered specific capacities of 352, 385, and 368 mA h g-1, respectively, which attests to the electrochemical activity of sodium in these compounds.

  19. Cavitation erosion of laser processed Fe-Cr-Mn and Fe-Cr-Co alloys

    Directory of Open Access Journals (Sweden)

    M. Szkodo

    2008-12-01

    Full Text Available Purpose: Purpose of this paper is attempt explanation how laser beam processing influence on the cavitation performance of the Fe-Cr-Mn and Fe-Cr-Co alloys. This kind of alloys are frequently used in Polish power plants to routine repairs of damaged blades working under cavitation loading.Design/methodology/approach: Padding welds of investigated alloys were tested for three cases: after laser melting, after laser heating of the solid state and without additional processing. Cw. CO2 laser was employed as a source of radiation. The rotating disk rig was used in cavitation erosion investigations. The chemical composition, microstructure, and phase identification of the processed and subjected to cavitation loading alloys were examined using light microscopy, X-ray diffractometry and scanning electron microscopy, respectively.Findings: Phase transformation for processed and unprocessed alloys was observed. Obtained results revealed that laser processing contributes to delaying of austenite → martensite phase transformation. Kinetic of this transformation is different for investigated alloys and depends on the chemical composition and applied laser processing. Research limitations/implications: Reported research ought to be completed and full cavitation curves (volume loss in time for laser beam processed alloys must be done. Practical implications: For low intensity of cavitation loading, like in field conditions laser beam processing can increase of cavitation erosion resistance of investigated alloys due to increase of hardness.Originality/value: Confirmation that creation of the transformed and hardfacing structures by laser techniques leads in many cases to considerable changes in cavitation erosion properties of the processed materials.

  20. Environmentally Assisted Cracking of Commercial Ni-Cr-Mo Alloys - A Review

    Energy Technology Data Exchange (ETDEWEB)

    Rebak, R B

    2004-11-09

    Nickel-Chromium-Molybdenum alloys (Ni-Cr-Mo) are highly resistant to general corrosion, localized corrosion and environmentally assisted cracking (EAC). Cr acts as a beneficial element under oxidizing acidic conditions and Mo under reducing conditions. All three elements (Ni, Cr and Mo) act synergistically to provide resistance to EAC in environments such as hot concentrated chloride solutions. Ni-Cr-Mo alloys may suffer EAC in environments such as hot caustic solutions, hot wet hydrofluoric acid (HF) solutions and in super critical water oxidation (SCWO) applications. Not all the Ni-Cr-Mo alloys have the same susceptibility to cracking in the mentioned environments. Most of the available data regarding EAC is for the oldest Ni-Cr-Mo alloys such as N10276 and N06625.

  1. NiMnGa/Si Shape Memory Bimorph Nanoactuation

    Science.gov (United States)

    Lambrecht, Franziska; Lay, Christian; Aseguinolaza, Iván R.; Chernenko, Volodymyr; Kohl, Manfred

    2016-12-01

    The size dependences of thermal bimorph and shape memory effect of nanoscale shape memory alloy (SMA)/Si bimorph actuators are investigated in situ in a scanning electron microscope and by finite element simulations. By combining silicon nanomachining and magnetron sputtering, freestanding NiMnGa/Si bimorph cantilever structures with film/substrate thickness of 200/250 nm and decreasing lateral dimensions are fabricated. Electrical resistance and mechanical beam bending tests upon direct Joule heating demonstrate martensitic phase transformation and reversible thermal bimorph effect, respectively. Corresponding characteristics are strongly affected by the large temperature gradient in the order of 50 K/µm forming along the nano bimorph cantilever upon electro-thermal actuation, which, in addition, depends on the size-dependent heat conductivity in the Si nano layer. Furthermore, the martensitic transformation temperatures show a size-dependent decrease by about 40 K for decreasing lateral dimensions down to 200 nm. The effects of heating temperature and stress distribution on the nanoactuation performance are analyzed by finite element simulations revealing thickness ratio of SMA/Si of 90/250 nm to achieve an optimum SME. Differential thermal expansion and thermo-elastic effects are discriminated by comparative measurements and simulations on Ni/Si bimorph reference actuators.

  2. Thermodynamic Analysis on the Coprecipitation of Ni-Co-Mn Hydroxide

    Science.gov (United States)

    Li, Ling; Li, Yunjiao; Li, Lin; Chen, Nanxiong; Han, Qiang; Zhang, Xianzhen; Xu, Hu

    2017-10-01

    The thermodynamic data of various species in Ni-H2O, Co-H2O, Mn-H2O, and Ni-Co-Mn-H2O systems were obtained by thermodynamic calculation. The potential-pH diagrams for Ni-H2O, Co-H2O, and Mn-H2O systems at different ion activities at 323 K (50 °C), as well as Ni-Co-Mn-H2O complex systems at activity 1.00 at 298 K, 323 K, and 373 K (25 °C, 50 °C, and 100 °C) were constructed, respectively. The costable regions of Ni(OH)2, Co(OH)2, and Mn(OH)2 are verified to be thermodynamically stable in aqueous solution, which indicates the thermodynamic possibility of Ni-Co-Mn hydroxide coprecipitation. The potential-pH diagrams show that the temperature and ion activity have significant effects on the coprecipitation process. As the temperature increases or the ion activity decreases, the coprecipitation region of the Ni-Co-Mn hydroxide narrows. Moreover, the metal oxides, rather than the metal hydroxide, are more easily formed when the temperature increases. Experimental confirmation was performed to further verify the constructed potential-pH diagrams. The Ni-Co-Mn hydroxide with typical hexagonal CdI2 structure and quasi-spherical morphology was successfully obtained, and the SEM results show the uniform distribution of the elements Ni, Co, and Mn. The experimental results confirm the reliability of the prediction of thermodynamics analysis.

  3. Core Formation in the Earth and Moon: New Constraints From V, Cr, and Mn Partitioning Experiments

    Science.gov (United States)

    Chabot, N. L.; Agee, C. B.

    2002-05-01

    The mantles of the Earth and Moon are similarly depleted in V, Cr, and Mn relative to the concentrations of these elements in chondritic meteorites [1,2]. The similar depletions have been suggested to be due to a common genesis of the Earth and Moon, with the Moon inheriting its mantle, complete with V, Cr, and Mn depletions, from the Earth during the impact-induced formation of the Moon. We have conducted multi-anvil experiments that systematically examined the effects of pressure, temperature, and silicate and metallic compositions on liquid metal-liquid silicate partitioning of V, Cr, and Mn. Increasing temperature is found to significantly increase the metal-silicate partition coefficients for all three elements. Increasing the S or C content of the metallic liquid also causes the partition coefficients to increase. Silicate composition has an effect consistent with Cr and Mn being divalent and V being trivalent. Over our experimental range of 3-14 GPa, the partitioning behavior of V, Cr, and Mn did not vary with pressure. With the effects of oxygen fugacity, metallic and silicate compositions, temperature and pressure understood, the partition coefficient for each element was expressed as a function of these thermodynamic variables and applied to different core formation scenarios. Our new metal-silicate experimental partitioning data can explain the mantle depletions of V, Cr, and Mn by core formation in a high temperature magma ocean under oxygen fugacity conditions two log units below the iron-wuestite buffer, conditions similar to those proposed by [3] from their metal-magnesiowuestite study. In contrast, more oxidizing conditions proposed in recent core formation models [4] cannot account for the V, Cr, and Mn depletions. Additionally, because we observe little or no pressure effect on V, Cr, and Mn partitioning in our experiments, we conclude that the mantle depletions of these elements during core formation are not dependent on planet size. Accordingly

  4. Magnetic phase transitions and magnetocaloric effect in the Fe-doped MnNiGe alloys

    Institute of Scientific and Technical Information of China (English)

    Zhang Cheng-Liang; Wang Dun-Hui; Chen Jian; Wang Ting-Zhi; Xie Guang-Xi; Zhu Chun

    2011-01-01

    The magnetic phase transition and magnetocaloric effects in Fe-doped MnNiGe alloys are investigated. The substitution of Fe for Ni decreases the structural transition temperature remarkably,resulting in the magnetostructural transition occurring between antiferromagnetic and ferromagnetic states in MnNil-xFex Ge alloy. Owing to the enhanced ferromagnetic coupling induced by the substitution of Fe,metamagnetic behaviour is also observed in TiNiSi-type phase of MnNil_yFe.Ge alloys at temperature below the structural transition temperature.

  5. Laser Remelting of Plasma Sprayed NiCrA1Y and NiCrAlY-A12O3 Coatings

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Two types of plasma sprayed coatings (NiCrAIY and NiCrAIY-AI2O3) were remelted by a 5 kW cw CO2 laser. With increasing laser power and decreasing traverse speed in the ranges of 200~700 W and 5~30 mm/s respectively, the melted track grew in width and depth. In the optimum range of laser parameters, a homogeneous remelted layer without voids, cavities, unmelted particles and microcracks was formed. On the surface of remelted layers, AI2O3 and YAIO3 were detected.As a result of isothermal oxidation tests, weight gains of laser remelted coatings were obviously lower than that only plasma sprayed, especially laser remelted NiCrAIY-AI2O3 coatings. The effects of laser remelting and incorporation of Al2O3 second phase in NiCrAIY matrix on high temperature oxidation resistance were discussed.

  6. 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.

  7. Pressure induced heli- to ferromagnetic transition in Mn0.615Cr0.385As

    DEFF Research Database (Denmark)

    Lebech, Bente

    1986-01-01

    The effect of applied pressure up to 13 kbar on the magnetic properties of Mn0.615Cr0.385As has been studied by powder neutron diffraction. Because of a slightly uneven distribution of Mn and Cr in the metal sublattice two helimagnetic (Ha and Hc types phases coexist at ambient pressure and 80 K........ On subjecting the sample to external pressure, the Ha type mode is converted into a ferromagnetic (F) mode. The results agree with the findings for the analogous phase Mn0.64Cr0.36As1−xPx, where the lattice is exposed to internal, chemically induced pressure.......The effect of applied pressure up to 13 kbar on the magnetic properties of Mn0.615Cr0.385As has been studied by powder neutron diffraction. Because of a slightly uneven distribution of Mn and Cr in the metal sublattice two helimagnetic (Ha and Hc types phases coexist at ambient pressure and 80 K...

  8. Wear resistance of a Cr3C2-NiCr detonation spray coating

    Science.gov (United States)

    Wang, Jun; Wang, Jun; Sun, Baode; Guo, Qixin; Nishio, Mitsuhiro; Ogawa, Hiroshi

    2002-06-01

    Coatings can be applied to surfaces to improve the surface characteristics over those of the bulk properties and are widely used in tribological applications either to reduce wear and/or to modify friction during contact. One of the foremost coating methods for combating wear is thermal spraying. To prolong the life of steel slab continuous casting rolls, Cr3C2-NiCr detonation spray coating was processed on the roll surface in a steelmaking plant in China. This article studies the mechanical properties and wear resistance of this coating. The abrasive and dry frictional wear testing were performed using a pin-on-disk tester. Experimental results show that the wear resistance of the coated samples, i.e., coating reduces the risk of seizure compared to uncoated samples, is much better than those of the uncoated steel at room and elevated temperatures with any load and sliding velocity. The coating wear mechanisms under different test conditions are discussed.

  9. Characterization of transition behavior in SA508 Gr.4N Ni-Cr-Mo low alloy steels with microstructural alteration by Ni and Cr contents

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ki-Hyoung; Park, Sang-gyu [Department of Materials Science and Engineering, KAIST, Daejeon 305-701 (Korea, Republic of); Nuclear Materials Research Division, KAERI, Daejeon 305-353 (Korea, Republic of); Kim, Min-Chul, E-mail: mckim@kaeri.re.kr [Nuclear Materials Research Division, KAERI, Daejeon 305-353 (Korea, Republic of); Lee, Bong-Sang [Nuclear Materials Research Division, KAERI, Daejeon 305-353 (Korea, Republic of); Wee, Dang-Moon [Department of Materials Science and Engineering, KAIST, Daejeon 305-701 (Korea, Republic of)

    2011-11-25

    Highlights: {yields} We offer information for determining optimum alloying contents of SA508 Gr.4N steel. {yields} This study shows improvement of toughness with increasing Ni and Cr contents. {yields} Ni content is more effective on the impact toughness than on the fracture toughness. {yields} Cr content is more effective on the fracture toughness. {yields} We offer detailed information on relationship between toughness and microstructure. - Abstract: SA508 Gr.4N Ni-Cr-Mo low alloy steel, in which Ni and Cr contents are higher than in commercial reactor pressure vessel (RPV) steels, may be a candidate RPV material with the improved strength and toughness due to its tempered martensitic microstructure. This study aims at assessing the effects of microstructural factors with alloying element contents on the transition properties of Ni-Cr-Mo low alloy steels. Model alloys with different Ni and Cr contents were fabricated and their Charpy impact toughness and fracture toughness were examined in the transition region according to ASTM E23 and E1921 standard procedures, respectively. The test results showed extensive improvements of both impact toughness and fracture toughness with increasing Ni and Cr contents. However, Ni content was more effective on the impact toughness than on the fracture toughness, while Cr content was more effective on the fracture toughness. In order to identify a difference in effects of alloying elements contents on the fracture toughness and impact toughness, the relations between the transition properties and the scale of the microstructural features such as packets and carbides are discussed in detail.

  10. Hyperfine field distributions in disordered Mn2CoSn and Mn2NiSn Heusler alloys

    Indian Academy of Sciences (India)

    N Lakshmi; Anil Pandey; K Venugopalan

    2002-08-01

    Heusler alloys, Mn2CoSn and Mn2NiSn, were prepared and characterized by X-ray studies. Mössbauer studies using Sn-119 were carried out to investigate the hyperfine fields present at the Sn site in these alloys. The hyperfine field distribution in these alloys as well as X-ray studies point to the chemical disorder present in both alloys. Co-existence of a paramagnetic portion along with the magnetic hyperfine part was observed in Mn2CoSn even at low temperatures, while this was not found in Mn2NiSn spectra. Hyperfine fields at Sn site were calculated using Blandin and Campbell model and compared with the experimental results.

  11. Synthesis and Characterization of NiCr Self-assembled Nanorings

    NARCIS (Netherlands)

    Serdio, Victor M.; Gracia-Pinilla, Miguel A.; Velumani, S.; Perez-Tijerina, Eduardo G.; Wiel, van der Wilfred G.

    2010-01-01

    Formation of NiCr nanorings out of 2-3 nm NiCr nanoparticles prepared by DC magnetron sputtering with inert gas condensation is reported. An RF quadrupole mass filter has been used to get the particle size distribution and control the particle size in the plasma stream of grown material. The deposit

  12. Electroless deposition of NiCrB diffusion barrier layer film for ULSI-Cu metallization

    Science.gov (United States)

    Wang, Yuechun; Chen, Xiuhua; Ma, Wenhui; Shang, Yudong; Lei, Zhengtao; Xiang, Fuwei

    2017-02-01

    NiCrB films were deposited on Si substrates using electroless deposition as a diffusion barrier layer for Cu interconnections. Samples of the prepared NiCrB/SiO2/Si and NiCrB/Cu/NiCrB/SiO2/Si were annealed at temperatures ranging from 500 °C to 900 °C. The reaction mechanism of the electroless deposition of the NiCrB film, the failure temperature and the failure mechanism of the NiCrB diffusion barrier layer were investigated. The prepared samples were subjected to XRD, XPS, FPP and AFM to determine the phases, composition, sheet resistance and surface morphology of samples before and after annealing. The results of these analyses indicated that the failure temperature of the NiCrB barrier film was 900 °C and the failure mechanism led to crystallization and grain growth of the NiCrB barrier layer after high temperature annealing. It was found that this process caused Cu grains to reach Si substrate through the grain boundaries, and then the reaction between Cu and Si resulted in the formation of highly resistive Cu3Si.

  13. Austenite Formation from Martensite in a 13Cr6Ni2Mo Supermartensitic Stainless Steel

    NARCIS (Netherlands)

    Bojack, A.; Zhao, L.; Morris, P.F.; Sietsma, J.

    2016-01-01

    The influence of austenitization treatment of a 13Cr6Ni2Mo supermartensitic stainless steel (X2CrNiMoV13-5-2) on austenite formation during reheating and on the fraction of austenite retained after tempering treatment is measured and analyzed. The results show the formation of austenite in two stage

  14. Ferromagnetic resonance studies and magnetization curvesof Co-Cr and Co-Cr/Ni-Fe thin films

    NARCIS (Netherlands)

    Stam, Maria Theresia Helena Clasina Wilhelmina

    1989-01-01

    In this thesis CoCr and CoCr/NiFe double layers are studied by ferromagnetic resonance. The coercivity and the initial susceptibility of these layers are measured. An approximation of the Kooy and Enz model which is suitable for calculating the initial suceptibility is presented [3.36]. A theoretica

  15. Effect of Ni content on microwave absorbing properties of MnAl powder

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhen-zhong; Lin, Pei-hao, E-mail: gllph2002@163.com; Huang, Wei-chao; Pan, Shun-kang; Liu, Ye; Wang, Lei

    2016-09-01

    MnAlNi powder was prepared by the process of vacuum levitation melting and high-energy ball milling, The morphology and phase structure of the powder were analyzed by Scanning Electron Microscope(SEM), X-ray diffraction(XRD) and the effect of the Ni content on microwave absorbing properties of MnAl powder was investigated by an vector network analyzer. The addition of Ni, which improved the microwave absorbing properties of MnAl powder but not changed the composition of Al{sub 8}Mn{sub 5} alloy. The minimum reflectivity of (Al{sub 8}Mn{sub 5}){sub 0.95}Ni{sub 0.05} powder with a coating thickness (d) of 1.8 mm was about −40.8 dB and has better bandwidth effect, the absorbing mechanism of AlMnNi powders on the electromagnetic was related to the electromagnetic loss within the absorbing coatings and the effect of coating thickness on the interference loss of electromagnetic wave. - Highlights: • The grain size and cell volume of Al{sub 8}Mn{sub 5} alloy phase were decreased with the increasing of Ni. • ε″ and μ″ of powder moves toward low frequency region at the beginning then moves high. • The minimum reflectivity of (Al{sub 8}Mn{sub 5}){sub 0.95}Ni{sub 0.05} powder was −40.8 dB with 1.8 mm thickness. • The lowest reflection loss peak of (Al{sub 8}Mn{sub 5}){sub 0.95}Ni{sub 0.05} was −46.3 dB with 2.2 mm thickness.

  16. Tribological Properties of WC-Co/NiCrBSi and Mo/NiCrBSi Plasma Spray Coatings under Boundary Lubrication Conditions

    Directory of Open Access Journals (Sweden)

    A. Vencl

    2017-06-01

    Full Text Available The tungsten carbide based WC-Co/NiCrBSi (50/50 and molybdenum based Mo/NiCrBSi (75/25 coatings were investigated under boundary lubricated sliding conditions, and their tribological properties were analysed and compared. These two coatings are in service for a long time, but there are very few papers dealing with their tribological properties, especially in lubricated sliding conditions. The NiCrBSi self-fluxing alloy is one of the popularly used materials for thermal sprayed coating, with relatively high hardness, reasonable wear resistance and high temperature corrosion. Tungsten carbide (WC is one of the most widely used commercial hard coating materials, and is added to the NiCrBSi coating to improve its hardness and wear resistance. Molybdenum (Mo is added to the NiCrBSi coating to reduce its coefficient of friction, i.e. to improve its dry sliding wear resistance. The results showed that WC-Co/NiCrBSi coating was more wear resistant, but caused higher wear of the counter-body material. Coefficients of friction were similar for both coatings.

  17. Excess Ni-doping induced enhanced room temperature magneto-functionality in Ni-Mn-Sn based shape memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Pramanick, S.; Giri, S.; Majumdar, S., E-mail: sspsm2@iacs.res.in [Department of Solid State Physics, Indian Association for the Cultivation of Science, 2A and B Raja S. C. Mullick Road, Jadavpur, Kolkata 700 032 (India); Chatterjee, S. [UGC-DAE Consortium for Scientific Research, Kolkata Centre, Sector III, LB-8, Salt Lake, Kolkata 700 098 (India)

    2014-09-15

    Present work reports on the observation of large magnetoresistance (∼−30% at 80 kOe) and magnetocaloric effect (∼12 J·kg{sup −1}·K{sup −1} for 0–50 kOe) near room temperature (∼290 K) on the Ni-excess ferromagnetic shape memory alloy Ni{sub 2.04}Mn{sub 1.4}Sn{sub 0.56}. The sample can be thought of being derived from the parent Ni{sub 2}Mn{sub 1.4}Sn{sub 0.6} alloy, where excess Ni was doped at the expense of Sn. Such Ni doping enhances the martensitic transition temperature and for the Ni{sub 2.04}Mn{sub 1.4}Sn{sub 0.56} it is found to be optimum (288 K). The doped alloy shows enhanced magneto-functional properties as well as reduced saturation magnetization as compared to the undoped counterpart at low temperature. A probable increment of antiferromagnetic correlation between Mn-atoms on Ni substitution can be accounted for the enhanced magneto-functional properties as well as reduction in saturation moment.

  18. Magnetic and Structural Properties in Co/Cu/Co Sandwiches with Ni and Cr Buffer Layers

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The magnetic and structural properties in Co/Cu/Co sandwiches with Ni and Cr buffer layers were investigated. It was found that the coercivity in Ni layer buffered samples decreases with increasing Ni layer thickness, while that in Cr layer buffered ones increases with increasing Cr layer thickness, leading to a large difference in field sensitivity of their giant magnetoresistance (GMR) properties. X-ray diffraction and high resolution transmission electron microscope images exhibited that there is a strong fcc (111) texture in the samples with Ni buffer layer. But there are only randomly oriented polycrystalline grains in Cr buffered sandwiches. According to atomic force microscope topography, the surface roughness of Cr buffered sandwiches is smaller than that of Ni buffered ones. It is demonstrated that buffer layer influences both magnetic and structural properties in Co/Cu/Co sandwiches as well as their GMR characteristics.

  19. NiCr thin film strain gauges fabricated on glass substrates

    Energy Technology Data Exchange (ETDEWEB)

    Danisman, Murat [Yildiz Technical Univ., Istanbul (Turkey). Metallurgical and Engineering Dept.; Cansever, Nurhan [Gedik Univ., Istanbul (Turkey). Electronic Engineering Dept.

    2013-10-01

    In order to investigate the strain gauge characteristics of NiCr thin films, 500 nm NiCr (80 wt.-% and 20 wt.-%, respectively) thin films were deposited on glass substrates by DC magnetron sputtering. After deposition, NiCr thin films were characterized by using X-Ray diffraction analysis, scanning electron microscope and four-point probe techniques inview of crystallization, phases, film structure and electrical resistivity. After characterization, NiCr thin films were shaped into strain gauges by photo lithography and wet etching techniques. Strain gauges were tested with different loads, and strain values were calculated by comparing the results with commercial NiCr strain gauges with the same surface area. Resistivity change vs. strain was plotted, and the gauge factor of fabricated thin film strain gauges was evaluated as 1.23. (orig.)

  20. Comparative study of Co, Cr and Al-doped LiMnO2 prepared by ion exchange

    Indian Academy of Sciences (India)

    Xian Ming Wu; Run Xiu Li; Shang Chen; Ze Qiang He; Ming Fei Xu

    2008-04-01

    The Co, Cr and Al-doped LiMnO2 powders were prepared by ion exchange. Phase identification, surface morphology and electrochemical properties were studied by X-ray diffraction, scanning electron microscopy and galvanostatic charge–discharge experiments. The results show that the doped LiMnO2 keeps the structure of LiMnO2. As compared to LiMnO2, Co, Cr and Al-doped LiMnO2 offers higher discharge capacity and better cycling performance. The discharge capacities of Co, Cr and Al-doped LiMnO2 decreases yet the cycling performance improves with the increase of doping concentration. For these doped LiMnO2 at the same doping concentration, Cr-doping shows the highest discharge capacity and best cycling performance, Aldoping offers the lowest discharge capacity and Co-doping shows the worst cycling performance.

  1. Simulated magnetocaloric properties of MnCr2O4 spinel

    Directory of Open Access Journals (Sweden)

    Mahmoud A. Hamad

    2016-03-01

    Full Text Available The magnetocaloric properties of MnCr2O4 spinel have been simulated based on a phenomenological model. The simulation of magnetization as function of temperature is used to explore magnetocaloric properties such as magnetic entropy change, heat capacity change, and relative cooling power. The results imply the prospective application of MnCr2O4 spinel to achieve magnetocaloric effect at cryogenic temperatures (20–60 K near Curie temperatures (38–44 K. According to the obtained results it is recommended that MnCr2O4 spinel can be used as a promising practical material in the active magnetic regenerator cycle that cools hydrogen gas.

  2. Emittance of TD-NiCr after simulated reentry

    Science.gov (United States)

    Clark, R. K.; Dicus, D. L.; Lisagor, W. B.

    1978-01-01

    The effects of simulated reentry heating on the emittance of TD-NiCr were investigated. Groups of specimens with three different preconditioning treatments were exposed to 6, 24, and 30 half-hour simulated reentry exposure cycles in a supersonic arc tunnel at each of three conditions intended to produce surface temperatures of 1255, 1365, and 1475 K. Emittance was determined at 1300 K on specimens which were preconditioned only and specimens after completion of reentry simulation exposure. Oxide morphology and chemistry were studied by scanning electron microscopy and X-ray diffraction analysis. A consistent relationship was established between oxide morphology and total normal emittance. Specimens with coarser textured oxides tended to have lower emittances than specimens with finer textured oxides.

  3. Diffusive Interaction Between Ni-Cr-Al Alloys

    Science.gov (United States)

    Tkacz-Śmiech, Katarzyna; Danielewski, Marek; Bożek, Bogusław; Berent, Katarzyna; Zientara, Dariusz; Zajusz, Marek

    2017-05-01

    In high-temperature coatings, welded parts, and a range of other applications, components in the contact zone interdiffuse at elevated temperatures and may react to change the phase composition. The diffusion zone can be complex and can consist of sequential layers of intermediate phases, solid solutions, and in the case of multicomponent systems also of multiphase layers. In this work, the interdiffusion in Ni-Cr-Al alloys is studied experimentally and modeled numerically. The diffusion multiples were prepared by hot isostatic pressing and post-annealing at 1473 K (1200 °C). The concentration profiles were measured with wide-line EDS technique which allowed obtaining high-accuracy diffusion paths. The experimental profiles and diffusion paths were compared with numerical results simulated with application of very recent model of interdiffusion in muticomponent-multiphase systems. The calculated and experimental data show good agreement.

  4. 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.

  5. Chemical shift of Mn and Cr K-edges in X-ray absorption spectroscopy with synchrotron radiation

    Indian Academy of Sciences (India)

    D Joseph; A K Yadav; S N Jha; D Bhattacharyya

    2013-11-01

    Mn and Cr K X-ray absorption edges were measured in various compounds containing Mn in Mn2+, Mn3+ and Mn4+ oxidation states and Cr in Cr3+ and Cr6+ oxidation states. Few compounds possess tetrahedral coordination in the 1st shell surrounding the cation while others possess octahedral coordination. Measurements have been carried out at the energy dispersive EXAFS beamline at INDUS-2 Synchrotron Radiation Source at Raja Ramanna Centre for Advanced Technology, Indore. Energy shifts of ∼8–16 eV were observed for Mn K edge in the Mn-compounds while a shift of 13–20 eV was observed for Cr K edge in Cr-compounds compared to values in elementalMn and Cr, respectively. The different chemical shifts observed for compounds having the same oxidation state of the cation but different anions or ligands show the effect of different chemical environments surrounding the cations in determining their X-ray absorption edges in the above compounds. The above chemical effect has been quantitatively described by determining the effective charges on Mn and Cr cations in the above compounds.

  6. Study on Oxidation Behavior of NiMoCr Metallic Interconnector for SOFC%固体氧化物燃料电池(SOFC)用NiMOCr金属连接体氧化行为研究

    Institute of Scientific and Technical Information of China (English)

    卢凤双; 田宇鹏

    2011-01-01

    金属作为固体氧化物燃料电池(SOFC)连接体材料已成为可能并成为研究热点.本论文对SOFC用NiMoCr合金分别在SOFC阴极和阳极气氛条件下的高温氧化性能作了详细的研究.结果表明:阳极(燃料极)条件下氧化所形成的是MnCr2O4尖晶石;阴极(空气极)条件下氧化所形成的是不含Cr的致密NiMnO4型尖晶石,能有效抑制Cr的挥发,降低阴极Cr毒化现象,并提高合金表面氧化物的导电性能.%At present, the metallic interconnector used for solid oxidation fuel cell (SOFC) is actively researched. In this paper, high temperature oxidation behaviors in the cathode and anode environment of SOFC were separately studied. The results show that the MnCr2O4 appears in the anode environment and NiMn2O4 appears in the cathode environment which can reduce poisoning of the cathode because of restraining the volatilization of Cr and increasing the conduction of electricity of oxidation layer.

  7. Inter-Diffusion between NiO Coating and the Oxide Scale on Fe-22Cr Alloy

    DEFF Research Database (Denmark)

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

    2003-01-01

    The effect of Ni and NiO coatings on Fe-22Cr during oxidation at 1173K in 1% H2O was examined with respect to scale microstructure for oxidation times between 0 and 504 hours. Upon oxidation of the as pre-treated Fe-22Cr, Cr2O3 and a spinel developed. Oxidation and inter-diffusion between the Ni...... coating and Fe-22Cr occurred simultaneously. The scale consisted of NiO, a Fe-Ni spinel and Cr2O3. For the NiO coated alloy, a thin spinel layer developed between the NiO coating and the Cr2O3 scale. The microstructures of the scales are discussed with respect to calculated isotherms in the Fe-Cr-O, Cr-Ni-O...

  8. Modeling and Characterization of the Magnetocaloric Effect in Ni2MnGa Materials

    Energy Technology Data Exchange (ETDEWEB)

    Nicholson, Don M [ORNL; Odbadrakh, Khorgolkhuu [ORNL; Rios, Orlando [ORNL; Hodges, Jason P [ORNL; Ludtka, Gerard Michael [ORNL; Porter, Wallace D [ORNL; Sefat, Athena Safa [ORNL; Rusanu, Aurelian [ORNL; Evans III, Boyd Mccutchen [ORNL

    2012-01-01

    Magnetic shape memory alloys have great promise as magneto-caloric effect refrigerant materials due to their combined magnetic and structural transitions. Computational and experimental research is reported on the Ni2MnGa material system. The magnetic states of this system have been explored using the Wang-Landau statistical approach in conjunction with the Locally Self-consistent Multiple-Scattering (LSMS) method to explore the magnetic states responsible for the magnet-caloric effect in this material. The effects of alloying agents on the transition temperatures of the Ni2MnGa alloy were investigated using differential scanning calorimetry (DSC) and superconducting quantum interference device (SQUID). Neutron scattering experiments were performed to observe the structural and magnetic phase transformations at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) on alloys of Ni-Mn-Ga and Ni-Mn-Ga-Cu-Fe. Data from the observations are discussed in comparison with the computational studies.

  9. Magnetic, phase transformation and magnetocaloric studies in ferromagnetic Ni55Mn20Ga25 Heusler alloy

    Science.gov (United States)

    Babita, I.; Gopalan, R.; Ram, S.

    2009-01-01

    The phase transformation and magnetic entropy change (ΔSM) in the Ni55Mn20Ga25 Heusler alloy has been studied. The temperature dependence of magnetization study shows the direct transition from ferromagnetic martensitic phase to paramagnetic austenitic phase occurred at 353 K. By compositional tuning the first order martensitic transformation (TM ~200 K for parent compound Ni2MnGa) and second order magnetic phase transition temperatures (TC ~375 K for parent compound Ni2MnGa) can be merged. This occurs for Ni55Mn20Ga25 alloy at 353 K. The magnetic entropy change, ΔSM-value of -7.0 Jkg-1K-1 has been obtained in a field change of 1.2 T. The origin of enhancement in ΔSM -value is attributed to the essential coincidence of TM and TC.

  10. Magnetic proximity effect and shell-ferromagnetism in metastable Ni50Mn45Ga5

    Science.gov (United States)

    Krenke, Thorsten; ćakır, Aslı; Scheibel, Franziska; Acet, Mehmet; Farle, Michael

    2016-12-01

    The present study on magnetic and structural properties of Ni50Mn45Ga5 confirms that structural metastability is an inherent property of Ni50Mn50-xXx Heusler alloys with X as In, Ga, and Sn. The ternary alloy transforms during temper-annealing into a dual-phase composite alloy. The two phases are identified to be cubic L21, Ni50Mn25Ga25, and tetragonal L10 Ni50Mn50. Depending on the annealing temperature, the magnetic-proximity effect giving rise to shell-ferromagnetism has been observed when annealing is carried out under an external magnetic field. The upper and lower remanence values MR+ and MR- have the same sign even at high temperatures. Such alloys can be promising candidates for heat- and magnetic-field-resistant magnetic recording media.

  11. Low temperature magneto-structural transitions in Mn3Ni20P6

    Science.gov (United States)

    Cedervall, Johan; Beran, Premysl; Vennström, Marie; Danielsson, Therese; Ronneteg, Sabina; Höglin, Viktor; Lindell, David; Eriksson, Olle; André, Gilles; Andersson, Yvonne; Nordblad, Per; Sahlberg, Martin

    2016-05-01

    X-ray and neutron powder diffraction has been used to determine the crystal and magnetic structure of Mn3Ni20P6. The crystal structure can be described as cubic with space group Fm 3 barm (225) without any nuclear phase transformation within studied temperature interval from room temperature down to 4 K. The magnetic structure of Mn3Ni20P6 is complex with two independent magnetic positions for the Mn atoms and the compound passes three successive magnetic phase transitions during cooling. At 30 K the spins of the Mn atoms on the Wyckoff 4a site (Mn1) order to form a primitive cubic antiferromagnetic structure with propagation vector k=(0 0 1). Between 29 and 26 K the Mn atoms on the Wyckoff 8c site (Mn2) order independently on already ordered Mn1 magnetic structure forming a commensurate antiferromagnetic structure with propagation vector k=(0 0 ½) and below 26 K, both Mn positions order to form an incommensurate helical structure with propagation vector k=(0 0 ~0.45). Magnetization vs. temperature curve of Mn3Ni20P6 shows a steep increase indicating some magnetic ordering below 230 K and a sharp field dependent anomaly in a narrow temperature range around 30 K.

  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. Crack Free Tungsten Carbide Reinforced Ni(Cr) Layers obtained by Laser Cladding

    OpenAIRE

    Amado Paz, José Manuel; Tobar Vidal, María José; YAÑEZ CASAL, ARMANDO JOSE; Amigó Borrás, Vicente; Candel Bou, Juan Jose

    2011-01-01

    The development of hardfacing coatings has become technologically significant in many industries A common approach is the production of metal matrix composites (MMC) layers. In this work NiCr-WC MMC hardfacing layers are deposited on C25 steel by means of laser cladding. Spheroidal fused tungsten carbides is used as reinforcement phase. Three different NiCr alloys with different Cr content were tested. Optimum conditions to obtain dense, uniform carbide distribution and hardness close to nomi...

  14. Protective Aluminide Coatings for NiCr Alloys in Combustion Environments

    Energy Technology Data Exchange (ETDEWEB)

    Pint, Bruce A [ORNL; Maziasz, Philip J [ORNL; Schauer, J [TRW; Levin, V [TRW

    2008-01-01

    Laboratory exposures that simulated the oxidation-related attack in natural gas-fired reciprocating engines were conducted on Ni-Cr alloys with and without aluminide coatings. Exposure of uncoated Ni-Cr alloy specimens to humid air at 800 C resulted in a mass loss due to CrO{sub 2}(OH){sub 2} evaporation and internal oxidation. Both model and commercial aluminide coatings reduced the amount of attack. The reaction products and Al interdiffusion were evaluated.

  15. Cr, Cu, Mn, Mo, Ni, and Steel Price Drivers

    Science.gov (United States)

    Papp, John F.; Corathers, Lisa A.; Edelstein, Daniel L.; Fenton, Michael D.; Kuck, Peter H.; Magyar, Michael J.

    2007-01-01

    Summary This report contains the 55 slide images from a presentation made by the author at the meeting of the Metal Powder Industries Federation held in Denver, CO, on May 15, 2007. The Metal Powder Industries Federation (MPIF) invited the U.S. Geological Survey (USGS) to speak at their annual meeting about the price drivers for chromium, copper, manganese, molybdenum, nickel, and steel. These metals are of interest to MPIF because the prices of these raw materials used by their industry were at historically high levels. Because the USGS closely monitors, yet neither buys nor sells, metal commodities, it is an unbiased source of metal price information and analysis. The authors used information about these and other metals collected and published by the USGS (U.S. production, trade, stocks, and prices) and about consumption and stocks internationally by country from industry organizations that publish such information, because metal markets are influenced by activities and events over the entire globe. By seeking a common cause for common behavior among the various metal commodities, the authors found that major price drivers on metal commodities were inflation, major international events such as wars and recessions, and major national events such as the dissolution of the Soviet Union in 1991 and economic growth in China, which started with the open door policy in the 1970s but did not have significant market impact until starting in the 1990s. Metal commodity prices also responded to commodity-specific events.

  16. An efficient control of Curie temperature $T_C$ in Ni-Mn-Ga alloys

    OpenAIRE

    Khovailo, V. V.; Chernenko, V. A.; Cherechukin, A. A.; Takagi, T.; Abe, T.

    2003-01-01

    We have studied the influence of alloying with a fourth element on the temperature of ferromagnetic ordering $T_C$ in Ni-Mn-Ga Heusler alloys. It is found that $T_C$ increases or decreases, depending on the substitution. The increase of $T_C$ is observed when Ni is substituted by either Fe or Co. On the contrary, the substitution of Mn for V or Ga for In strongly reduces $T_C$.

  17. Hot Corrosion Performance of AlO-CrO/NiCoCrAlYTa and AlO/NiCoCrAlYTa Coatings Deposited by Atmospheric Plasma Spraying

    Science.gov (United States)

    Tao, Chong; Wang, Lei; Cheng, Nailiang; Hu, Hengfa; Liu, Yang; Song, Xiu

    2016-04-01

    AlO-CrO/NiCoCrAlYTa and AlO/NiCoCrAlYTa coatings were deposited on 316L stainless steel substrate using atmospheric plasma spraying, respectively, in order to improve the oxidation and corrosion resistance. The hot corrosion performance of the coatings at 700 and 900 °C were studied, and the detailed microstructures and phase composition of the coatings were analyzed using x-ray diffraction, scanning electron microscope with energy dispersive spectrometer, and transmission electron microscope. The results show that both coatings are structurally featured by slatted layers, consisting of amorphous phase, Cr2O3, Ni3Al, and Al2O3. The hot corrosion resistance of AlO-CrO/NiCoCrAlYTa coating is better than that of AlO/NiCoCrAlYTa coating. This improvement is attributed to lower porosity and more compact Cr2O3 in AlO-CrO/NiCoCrAlYTa coating which performs better than Al2O3 in blocking further inward progress of corrosion and oxidization.

  18. 30CrMnSi耐磨铸钢的研制%Study on 30CrMnSi Abrasive Resistance Cast Steel

    Institute of Scientific and Technical Information of China (English)

    赵晓钟; 贺安荣

    2007-01-01

    30CrMnSi合金钢有较高的耐磨性和优良的综合力学性能,具有生产工艺简单,安全可靠性较高,综合成本较低的特点,代替奥氏体锰钢做湿式矿磨机衬板,收到较好的使用效果。

  19. Simulated magnetocaloric properties of MnCr2O4 spinel

    OpenAIRE

    2016-01-01

    The magnetocaloric properties of MnCr2O4 spinel have been simulated based on a phenomenological model. The simulation of magnetization as function of temperature is used to explore magnetocaloric properties such as magnetic entropy change, heat capacity change, and relative cooling power. The results imply the prospective application of MnCr2O4 spinel to achieve magnetocaloric effect at cryogenic temperatures (20–60 K) near Curie temperatures (38–44 K). According to the obtained results it is...

  20. Chemical effect on the K shell fluorescence yield of Fe, Mn, Co, Cr and Cu compounds

    Indian Academy of Sciences (India)

    U Turgut

    2004-11-01

    Chemical effects on the K shell fluorescence yields of Fe, Mn, Co, Cr and Cu compounds were investigated. Samples were excited using 59.5 keV energy photons from a 241Am radioisotope source. K X-rays emitted by samples were counted by a Si(Li) detector with a resolution 160 eV at 5.9 keV. Chemical effects on the K shell fluorescence yields (K) for Fe, Mn, Co, Cr and Cu compounds were observed. The values are compared with theoretical, semiempirical fit and experimental ones for the pure elements.

  1. Sucrose-aided combustion synthesis of nanosized LiMn{sub 1.99-y}Li{sub y}M{sub 0.01}O{sub 4} (M = Al{sup 3+}, Ni{sup 2+}, Cr{sup 3+}, Co{sup 3+}, y = 0.01 and 0.06) spinels. Characterization and electrochemical behavior at 25 and at 55 C in rechargeable lithium cells

    Energy Technology Data Exchange (ETDEWEB)

    Amarilla, J.M.; Pico, F.; Rojo, J.M.; Rojas, R.M. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas (CSIC), Sor Juana Ines de la Cruz no. 3, Cantoblanco, 28049 Madrid (Spain); Petrov, K.; Avdeev, G. [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria)

    2009-06-15

    Doubly doped LiMn{sub 1.99-y}Li{sub y}M{sub 0.01}O{sub 4} (M = Al{sup 3+}, Ni{sup 2+}, Cr{sup 3+}, Co{sup 3+}; y = 0.01 and 0.06) spinels have been synthesized by the sucrose-aided combustion method. Combined TG/DTA and XRD studies have shown that stoichiometric single-phase spinels are formed after annealing of the samples at 700 C for 1 h. The samples obtained are nanocrystalline materials having a narrow size-distribution and a coherent domain size between 40 and 60 nm, depending on the amount of fuel (sucrose) used in the synthesis. The influence of the Li-excess, the type of M{sup n+}-dopant cation and the amount of fuel used in the synthesis on the electrochemical behavior of the spinels in a Li-cell at room and at elevated temperature (55 C) has been studied. At 25 C all the spinels synthesized have a good capacity retention after 100 cycles, QRt-100 > 92%. At 55 C the increase of the Li-excess improves the cycling performances. Rate capability studies show that the spinels retain >90% of their capacity even at 5C rate. The synergic effect of the Li-excess and the particle size on the electrochemical properties of the spinels as cathode material has been settled. The LiMn{sub 1.93}Li{sub 0.06}M{sub 0.01}O{sub 4}, (M = Al{sup 3+}, Ni{sup 2+}) spinels, with cyclabilities >99.9% by cycle at both 25 and 55 C, and high rate capabilities, are the ones that show the best electrochemical properties. (author)

  2. New type of Schottky diode-based Cu-Al-Mn-Cr shape memory material films

    Science.gov (United States)

    Aksu Canbay, C.; Dere, A.; Mensah-Darkwa, Kwadwo; Al-Ghamdi, Ahmed; Karagoz Genç, Z.; Gupta, R. K.; Yakuphanoglu, F.

    2016-07-01

    Cr-doped CuAlMn shape memory alloys were produced by arc melting method. The effects of Cr content on microstructure and transformation parameters of were investigated. The alloys were characterized by X-ray analysis, optical microscope observations and differential scanning calorimetry measurements. The grain size of the alloys was decreased by the addition of Cr into CuAlMn alloy system. The martensite transformation temperature was shifted both the lower temperature and higher temperature with the addition of chromium. This change was explained on the basis of the change in the thermodynamics such as enthalpy, entropy and activation energy values. The obtained results indicate that the phase transformation temperatures of the CuAlMn alloy system can be controlled by addition of Cr. We fabricated a Schottky barrier diode and observed that ideality factor and barrier height increase with increasing temperature. The diodes exhibited a thermal sensor behavior. This indicates that Schottky diode-based Cu-Al-Mn-Cr shape memory material films can be used as a sensor in high-temperature measurement applications.

  3. Microstructure and magnetic performance of Ni-substituted high density MnZn ferrite

    Institute of Scientific and Technical Information of China (English)

    YU Zhong; LAN Zhongwen; CHEN Shengming; SUN Yueming; SUN Ke

    2006-01-01

    The effects of NiO on microstructure and magnetic properties of Mn-Zn ferrite with a nominal composition of Zn0.32Mn0.60-xNixFe2.08O4 were investigated. The calcined powder of Mn-Zn ferrite was characterized by X-ray diffraction (XRD), the fracture surface of Mn-Zn ferrite was checked by scanning electronic microscope (SEM), and then the magnetic properties were measured. As a result, the substitution of Ni can cause the crystallattice constant of MnZn ferrite to decline, and the grain size to decrease, therefore improve the magnetic performance of MnZn ferrite whose density exceeds 5.0 g·cm-3.

  4. 20CrMnMo钢稀土渗碳研究%Study on RE Carburizing of 20CrMnMo Steel

    Institute of Scientific and Technical Information of China (English)

    徐建军; 杜晓东

    2012-01-01

    RE carburization was carried out on 20CrMnMo steel. The carburizing kinetics of carburizing depth was dealed with, the microstructure of the carburized layer was observed, the hardness and abrasion resistance of the carburized layer were examined. The results show that a large amount of dispersed granular carbides precipitated in the carburized layer of 20CrMnMo steel RE carburized. The microstructure of surface layer after directly quenching consists of acicular martensite, fine granular carbides and a little residual austenite. The test results showed 10 persent improvement in hardness, 32 persent improvement in abrasion resistance,The touching fatigue life is sharply improved too.%采用稀土渗碳工艺对20CrMnMo钢进行渗碳处理,研究了渗层增厚的动力学、渗碳层组织和性能.结果表明:稀土渗碳层中沉淀析出了大量弥散分布的粒状碳化物,淬火后表层组织为针状马氏体、大量细小颗粒碳化物、少量残余奥氏体.渗碳层的硬度与传统工艺相比提高了10%,耐磨性提高了32%,接触疲劳寿命也有大幅提高.

  5. Magnetostructural transition behavior in Fe-doped Heusler Mn-Ni-In ribbon materials

    Science.gov (United States)

    Li, Hongwei; Fang, Yue; Feng, Shutong; Zhai, Qijie; Luo, Zhiping; Zheng, Hongxing

    2016-11-01

    In the present work, we investigated magnetostructural transition behavior in Mn-rich Heusler Mn50-xFexNi41In9 (x=0, 1, 2, 3 at%) ribbon materials. Microstructural observations showed that substituting Mn with Fe in Mn50Ni41In9 led to striking grain refinement from ∼50 μm to 5-10 μm, and formation of a secondary phase when Fe content was increased up to 2 at%. Differential scanning calorimetric and thermomagnetic measurements indicated that a paramagnetic→ferromagnetic transition in austenite occurred first, followed with a weak-magnetic martensitic transition upon cooling for the Mn50-xFexNi41In9 (x=0, 1, 2). In case of Mn47Fe3Ni41In9, the martensitic transformation happened between paramagnetic austenite and weak-magnetic martensite, without the presence of the magnetic transition in austenite. The effective refrigeration capacity of Mn49Fe1Ni41In9 reached 137.1 J kg-1 under a magnetic field change of 30 kOe.

  6. Unique Sandwiched Carbon Sheets@Ni-Mn Nanoparticles for Enhanced Oxygen Evolution Reaction.

    Science.gov (United States)

    Zhang, Yan; Zhang, Huijuan; Yang, Jiao; Bai, Yuanjuan; Qiu, Huajun; Wang, Yu

    2016-05-11

    A unique sandwich-like architecture, where Ni-Mn nanoparticles are enveloped in coupled carbon sheets (CS@Ni-Mn), has been successfully fabricated. In the synthesis process, a great quantity of uniform NiMnO3 nanosheets generated by a universal hydrothermal method acts as precursors and templates and the cheap, environmentally friendly and recyclable glucose functions as a green carbon source. Via subsequent hydrothermal reaction and thermal annealing, sandwiched nanocomposites with Ni-Mn nanoparticles embedded inside and carbon sheets encapsulating outside can be massively prepared. The novel sandwich-like CS@Ni-Mn possesses numerous advantages, such as an intrinsic porous feature, large specific surface area, and enhanced electronic conductivity. Moreover, as a promising NiMn-based oxygen evolution reaction (OER) catalyst, the special sandwiched nanostructure demonstrates improved electrochemical properties in 1 M KOH, including a low overpotential of about 250 mV, a modest Tafel slope of 40 mV dec(-1), excellent stability over 2000 cycles, and durability for 40 h.

  7. Origin of spontaneous exchange bias in Co/NiMn bilayer structure

    Science.gov (United States)

    Akbulut, A.; Akbulut, S.; Yildiz, F.

    2016-11-01

    Spontaneous exchange bias (EB) is reported for as deposited Si/Pt(tPt)/Ni45Mn55(tAFM/Co(tFM)/Pt(30 Å) thin film system without requiring any post annealing, deposition with field or field cooling procedures. Magnetic properties of this system were investigated with respect to thicknesses of buffer Pt layer (tPt), antiferromagnetic NiMn layer (tAFM) and ferromagnetic Co layer (tFM). Exchange coupling between NiMn and Co layers enhanced considerably by increasing tPt. In order to observe a spontaneous EB in the system, Pt buffer layer must be thicker than a certain thickness, and NiMn layer must be grown directly on the buffer layer. On the other hand, significant increments in the coercive fields (HC) were reported for thinner Pt buffer layers. The thickness ranges for Co and NiMn layers were also determined to obtain spontaneous EB. This spontaneous EB is discussed to be a result of NiMn (111) texture which is induced by Pt buffer layer. Greater EB fields (HEB) are measured for the samples in the negative field direction by the effect of annealing and field cooling (from 400 K to 300 K at 2 kOe).

  8. Possible martensitic transformation and ferrimagnetic properties in Heusler alloy Mn{sub 2}NiSn

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Ying-Ni, E-mail: duanyingni@163.com [Department of Medical Engineering and Technology, Xinjiang Medical University, Urumqi 830011, Xinjiang (China); Fan, Xiao-Xi; Kutluk, Abdugheni [Department of Medical Engineering and Technology, Xinjiang Medical University, Urumqi 830011, Xinjiang (China); Du, Xiu-Juan [School of Applied Science, Taiyuan University of Science and Technology, Taiyuan 030024, Shanxi (China); Zhang, Zheng-Wei [Chemistry and Chemical Engineering Laboratory, The Xinjiang Technical Institute of Physics & Chemistry, Chinese Academy of Sciences, Urumqi 830011, Xinjiang (China); Song, Yu-Ling [College of Physics and Electronic Engineering, Nanyang Normal University, Nanyang 473061, Henan (China)

    2015-07-15

    The electronic structure and magnetic properties of Hg{sub 2}CuTi-type Mn{sub 2}NiSn have been studied by performing the first-principle calculations. It is found that the phase transformation from the cubic to the tetragonal structure reduces the total energy, indicating that the martensitic phase is more stable and the phase transition from austenite to martensite may happen at low temperature for Hg{sub 2}CuTi-type Mn{sub 2}NiSn. Concerning the magnetism of Hg{sub 2}CuTi-type Mn{sub 2}NiSn, both austenitic and martensitic phases are suggested to be ferrimagnets. Furthermore, martensitic transformation decreases the magnetic moment per formula unit compared with austenitic phase. The results are helpful to accelerate the use of Mn{sub 2}NiSn alloys in the series for magnetic shape memory applications. - Highlights: • It is found that the phase transition from austenite to martensite may happen at low temperature for Mn{sub 2}NiSn with the Hg{sub 2}CuTi-type structure. • Both austenitic and martensitic Mn{sub 2}NiSn are ferrimagnets. • Martensitic transformation decreases the magnetization.

  9. Phonon dispersions of Ni-Mn-Al shape memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Mehaddene, T. [Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II)/Physik-Department E13, Technische Universitaet Muenchen, D-85747 Garching (Germany)], E-mail: mtarik@ph.tum.de; Neuhaus, J.; Petry, W.; Hradil, K. [Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II)/Physik-Department E13, Technische Universitaet Muenchen, D-85747 Garching (Germany); Bourges, P. [Laboratoire Leon Brillouin (LLB), CEA Saclay, F-91191 Gif sur Yvette Cedex (France); Hiess, A. [Insitut Laue Langevin (ILL), F-38042 Grenoble Cedex 9 (France)

    2008-05-25

    Normal modes of vibration of a Ni-Mn-Al single crystal have been measured by inelastic neutron scattering. The force constants have been fitted to the Born-von Karman model using axially symmetric forces. Dispersion curves of both acoustical and optical phonons have been determined along the high symmetry [1 0 0], [1 1 0] and [1 1 1] directions. The temperature dependence of the normal modes revealed an anomalous softening of the TA{sub 2}[1 1 0] phonons observed in the range of 0.1-0.25 reciprocal lattice units in good agreement with recent ab initio calculations. Contrary to the acoustical TA{sub 2}[1 1 0] modes. The optical TO{sub 2}[1 1 0] modes with the same polarisation showed a normal behaviour with temperature, namely a decrease in frequency upon heating due to increasing anharmonicity. Elastic scattering performed along the [1 1-bar0] direction did not reveal any significant elastic or diffuse scattering.

  10. Behavior of NiCrAlY coating on the TC6 titanium alloy

    Institute of Scientific and Technical Information of China (English)

    Changqing Xia; Xiaomin Peng; Jia Li

    2008-01-01

    A NiCrAlY coating was deposited on the TC6 titanium substrate by arc ion plating (AIP). The structure and morphologies of the NiCrAlY coating were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and the influence of vacuum heat treatment on the element diffusion behavior was studied. The results showed that the γ'-Ni3Al phase was precipitated on the NiCrAlY coating after heat treatment. The Ni3(Al,Ti), TiNi, and Ti2Ni intermetallic layers appeared at the interface from the outside to the inside at 700℃, and the thickness of the intermetallic layers increased with the increase in temperature. At 700℃ Ti and Ni were the major diffusion elements, and the diffusion of Cr was observed when the heat treatment temperature increased up to 870℃. The violent inward diffusion of Ni at 950℃ resulted in the degradation of the NiCrAlY coating.

  11. Effects of Cr and Cr/Mn Combined Additions on Semi-Solid Microstructures of Al-Mg-Si Alloys Produced by D-SSF Process

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The effects of Cr and Cr/Mn combined additions on the semi-solid microstructure of wrought Al-Mg-Si alloys are investigated. In the Cr-added alloy, the Al7Cr compound is formed with homogeneously distributed in the α-Al matrix after homogenization. Both of the Al7Cr and α-Al12Mn3Si2 dispersiod particles are found in the homogenized microstructure of the Cr/Mn-added alloy. In the semi-solid microstructures, the smallest α-Al grains are obtained in the 60% cold-rolled alloys. After prolonged holding time, the α-Al grain size of the Cr/Mn-added alloy is smaller than that of the Cr-added alloy. Heavy deformation by cold-rolling accelerates spheroidization of the α-Al grains. The D-SSF process is found to be useful to modify the microstructures of both the Cr-added and Cr/Mn-added Al-Mg-Si alloys.

  12. Effect of NaOH on the vitrification process of waste Ni-Cr sludge.

    Science.gov (United States)

    Chou, I-Cheng; Wang, Ya-Fen; Chang, Cheng-Ping; Wang, Chih-Ta; Kuo, Yi-Ming

    2011-01-30

    This study investigated the effect of NaOH on the vitrification of electroplating sludge. Ni, the major metal in the electroplating sludge, is the target for recovery in the vitrification. Sludge and encapsulation materials (dolomite, limestone, and cullet) were mixed and various amounts of NaOH were added to serve as a glass modifier and a flux. A vitrification process at 1450 °C separated the molten specimens into slag and ingot. The composition, crystalline characteristics, and leaching characteristics of samples were measured. The results indicate that the recovery of Ni is optimal with a 10% NaOH mass ratio; the recoveries of Fe, Cr, Zn, Cu, and Mn all exhibited similar trends. The results of the toxicity characteristic leaching procedure (TCLP) show that leaching characteristics of the slag meet the requirements of regulation in Taiwan. In addition, a semi-quantitative X-ray diffraction analysis revealed that the main crystalline phase of slag changed from Ca(3)(Si(3)O(9)) to Na(4)Ca(4)(Si(6)O(18)) with a NaOH mass ratio of over 15%, because the Ca(2+) ions were replaced with Na(+) ions during the vitrification process. Na(4)Ca(4)(Si(6)O(18)), a complex mineral which hinders the mobility of metals, accounts for the decrease of metal recovery.

  13. Biocorrosion investigation of two shape memory nickel based alloys: Ni-Mn-Ga and thin film NiTi.

    Science.gov (United States)

    Stepan, L L; Levi, D S; Gans, E; Mohanchandra, K P; Ujihara, M; Carman, G P

    2007-09-01

    Thin film nitinol and single crystal Ni-Mn-Ga represent two new shape memory materials with potential to be used as percutaneously placed implant devices. However, the biocompatibility of these materials has not been adequately assessed. Immersion tests were conducted on both thin film nitinol and single crystal Ni-Mn-Ga in Hank's balanced salt solution at 37 degrees C and pH 7.4. After 12 h, large pits were found on the Ni-Mn-Ga samples while thin film nitinol displayed no signs of corrosion. Further electrochemical tests on thin film nitinol samples revealed breakdown potentials superior to a mechanically polished nitinol disc. These results suggest that passivation or electropolishing of thin film nitinol maybe unnecessary to promote corrosion resistance.

  14. Mechanical properties and microstructure of vaccum plasma sprayed Cr3C2 - 25(Ni20Cr) coatings

    OpenAIRE

    MRDAK MIHAILO R.

    2015-01-01

    This paper analyzes vacuum plasma spray VPS - Cr3C2 - 25(Ni20Cr) coatings. Commercial powder marked Sulzer Metco Woka 7205 is used. The powder is deposited with a plasma gun F4 at a distance of 340 mm from the substrate. The main objective of the study was to eliminate, at the reduced pressure of inert gas Ar, the degradation of primary Cr3C2 carbide into Cr23C6 carbide which significantly reduces the microhardness and mechanical properties of the coating. The coating is deposited with a thic...

  15. MODELING OF NI-CR-MO BASED ALLOYS: PART II - KINETICS

    Energy Technology Data Exchange (ETDEWEB)

    Turchi, P A; Kaufman, L; Liu, Z

    2006-07-07

    The CALPHAD approach is applied to kinetic studies of phase transformations and aging of prototypes of Ni-Cr-Mo-based alloys selected for waste disposal canisters in the Yucca Mountain Project (YMP). Based on a previous study on alloy stability for several candidate alloys, the thermodynamic driving forces together with a newly developed mobility database have been used to analyze diffusion-controlled transformations in these Ni-based alloys. Results on precipitation of the Ni{sub 2}Cr-ordered phase in Ni-Cr and Ni-Cr-Mo alloys, and of the complex P- and {delta}-phases in a surrogate of Alloy 22 are presented, and the output from the modeling are compared with experimental data on aging.

  16. Mechanical Properties and Microstructures of Ni20Cr Micro-wires with Abnormal Plastic Deformation

    Science.gov (United States)

    Zhou, Xiuwen; Liu, Xudong; Qi, Yidong; Wu, Weidong

    2017-05-01

    Ni80Cr20 (Ni20Cr, wt%) micro-wires were fabricated by the cold-drawing method with single die. Abnormal engineering strains were approximately 17.3-46.6 % for each pass. The relationship between mechanical properties and microstructures of Ni20Cr micro-wires were investigated under different engineering strains and annealing conditions. Experiment results indicate that the as-drawn NiCr micro-wires present obviously brittle fractures. The ultimate tensile strength (UTS) significantly increases from 781 to 1,147 MPa and the elongation decreases from 17.2 % to 1 % with engineering strains increasing. The deformed microstructures of Ni20Cr micro-wire were analyzed in detail including two-phase (solid solution/amorphous phase), edge dislocations and twins. With the annealing temperature increasing, specimens had experienced three stages and their mechanical properties were improved. After annealing at 890 °C (with 6.5 g stress) for 7.3 s in N2, the Ni20Cr micro-wires benefited for the second drawing pass. The results are very importance in fabricating Ni20Cr micro-wire with the diameter from 25 to 10 μm.

  17. Diffusional creep and creep degradation in the dispersion-strengthened alloy TD-NiCr

    Science.gov (United States)

    Whittenberger, J. D.

    1972-01-01

    Dispersoid-free regions were observed in TD-NiCr (Ni-20Cr-2ThO2) after slow strain rate testing in air from 1145 to 1590 K. Formation of the dispersoid-free regions appears to be the result of diffusional creep. The net effect of this creep is the degradation of TD-NiCr to a duplex microstructure. Degradation is further enhanced by the formation of voids and integranular oxidation in the thoria-free regions. These regions apparently provided sites for void formation and oxide growth since the strength and oxidation resistance of Ni-20Cr is much less than Ni-20Cr-2ThO2. This localized oxidation does not appear to reduce the static load bearing capacity of TD-NiCr since long stress rupture lives were observed even with heavily oxidized microstructures. But this oxidation does significantly reduce the ductility and impact resistance of the material. Dispersoid-free bands and voids were also observed for two other dispersion strengthened alloys, TD-NiCrAl and IN-853. Thus, it appears that diffusional creep is charactertistic of dispersion-strengthened alloys and can play a major role in the creep degradation of these materials.

  18. Standard Specification for Ni-Fe-Cr-Mo-Cu-N Low-Carbon Alloys (UNS N08925, UNS N08031, UNS N08354, and UNS N08926), and Cr-Ni-Fe-N Low-Carbon Alloy (UNS R20033) Bar and Wire, and Ni-Cr-Fe-Mo-N Alloy (UNS N08936) Wire

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2016-01-01

    Standard Specification for Ni-Fe-Cr-Mo-Cu-N Low-Carbon Alloys (UNS N08925, UNS N08031, UNS N08354, and UNS N08926), and Cr-Ni-Fe-N Low-Carbon Alloy (UNS R20033) Bar and Wire, and Ni-Cr-Fe-Mo-N Alloy (UNS N08936) Wire

  19. TEM investigations on NiMnInCo and Fe70Pd30 ferromagnetic shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Erkartal, Burak; Lotnyk, Andriy; Kienle, Lorenz [Synthesis and Real Structure, CAU Kiel, Kaiserstr. 2, 24143 Kiel (Germany); Duppel, Viola [Max-Planck-Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart (Germany); Niemann, Robert; Faehler, Sebastian; Schultz, Ludwig [IFW Dresden, P. O. Box 270116, 01171 Dresden (Germany); Bechtold, Christoph; Zamponi, Christiane; Quandt, Eckhard [Inorganic Functional Materials, CAU Kiel, Kaiserstr. 2, 24143 Kiel (Germany)

    2011-07-01

    NiMnInCo meta-magnetic shape memory alloys have attracted considerable interest because they can be utilized for the magnetocaloric effect. Here we focus on TEM investigations of an epitaxially grown NiMnInCo thin film sputtered on (001) oriented MgO substrate with Cr buffer layer. Besides the presence of 6M, 7M modulated martensites, structural analysis by precession electron diffraction confirm also a non-modulated tetragonal phase. EDX elemental maps recorded on a cross-section indicate defects of the Cr buffer layer at the interface. Additionally, columnar regions with lower In content were observed. Further interest was concentrated on Fe70Pd30 due to the exceptional strain in response to a variation of a moderate magnetic field. Fe70Pd30 was deposited by magnetron sputtering on (001) MgO substrates coated with different metallic buffer layers. HRTEM micrographs and diffraction patterns confirm the tetragonal single crystal growth of the Fe70Pd30 films of 1.2 micrometer thickness.

  20. Preparation and Investigation of Electrodeposited Ni-NANO-Cr2O3 Composite Coatings

    Science.gov (United States)

    Jiang, Jibo; Feng, Chenqi; Qian, Wei; Yu, Libin; Ye, Fengying; Zhong, Qingdong; Han, Sheng

    2016-12-01

    The electrodeposition of Ni-nano-Cr2O3 composite coatings was studied in electrolyte containing different contents of Cr2O3 nanoparticles (Cr2O3 NPs) on mild steel surfaces. Some techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), microhardness, the potentiodynamic polarization curves (Tafel) and electrochemical impedance spectroscopy (EIS) were used to compare pure Ni coatings and Ni-nano-Cr2O3 composite coatings. The results show that the incorporation of Cr2O3 NPs resulted in an increase of hardness and corrosion resistance, and the maximum microhardness of Ni-nano-Cr2O3 composite coatings reaches about 495 HV. The coatings exhibit an active-passive transition and relatively large impedance values. Moreover, the effect of Cr2O3 NPs on Ni electrocrystallization is also investigated by cyclic voltammetry (CV) and EIS spectroscopy, which demonstrates that the nature of Ni-based composite coatings changes attributes to Cr2O3 NPs by offering more nucleation sites and less charge transfer resistance.

  1. The Microstructural Evolution of Vacuum Brazed 1Cr18Ni9Ti Using Various Filler Metals

    Directory of Open Access Journals (Sweden)

    Yunxia Chen

    2017-04-01

    Full Text Available The microstructures and weldability of a brazed joint of 1Cr18Ni9Ti austenitic stainless steel with BNi-2, BNi82CrSiBFe and BMn50NiCuCrCo filler metals in vacuum were investigated. It can be observed that an interdiffusion region existed between the filler metal and the base metal for the brazed joint of Ni-based filler metals. The width of the interdiffusion region was about 10 μm, and the microstructure of the brazed joint of BNi-2 filler metal was dense and free of obvious defects. In the case of the brazed joint of BMn50NiCuCrCo filler metal, there were pits, pores and crack defects in the brazing joint due to insufficient wettability of the filler metal. Crack defects can also be observed in the brazed joint of BNi82CrSiBFe filler metal. Compared with BMn50NiCuCrCo and BNi82CrSiBFe filler metals, BNi-2 filler metal is the best material for 1Cr18Ni9Ti austenitic stainless steel vacuum brazing because of its distinct weldability.

  2. A less expensive NiMnGa based Heusler alloy for magnetic refrigeration

    OpenAIRE

    Mejia, CS; Gomes, AM; de Oliveira, LAS

    2012-01-01

    We present a study of the substitution of Mn by Cu on the compound Ni2Mn1-xCuxGa0.9Al0.1, showing that the substitution of a small amount of Al on the Ga site does not affect the magnetic and magnetocaloric potential compared to Ni-2(Mn,Cu)Ga alloy. The samples were prepared with 10% substitution of Al and with Cu concentrations of x = 0.0, 0.2, and 0.3. Magnetization measurements as a function of temperature performed from 10 to 400 K, with an applied field of 0.02 T showed a ferromagnetic s...

  3. Mechanical and Magnetostrictive Properties of Fe-Doped Ni52Mn24Ga24 Single Crystals

    Institute of Scientific and Technical Information of China (English)

    冯雪; 方岱宁; 黄克智

    2002-01-01

    To improve the magnetic and mechanical properties of a Heusler alloy of Ni52Mn24Ga24, iron was doped withsome contents. Single crystals ot the pseudoquaternary Heusler alloy of Ni52Mn9Fe15 Ga24 have been synthesizedfor mechanicai and magnetostrictive measurements. The magnetostriction loops and stress-strain curves weremeasured under different coupled magnetic-mechanicai loads. The experimental results show that the brittlenessof the sample is clearly improved and Young's modulus of 13. 7 GPa is obtained in the [001] direction due to thepart substitution of Fe for Mn. Furthermore, the toughness and Vickers hardness of the sample are also given byuse of the indentation technique.

  4. CuMnNiSi钎料钎焊不锈钢接头组织性能研究%Structure and Property of Stainless Steel Brazed Joint with CuMnNiSi Filler Metal

    Institute of Scientific and Technical Information of China (English)

    杨光; 李宁; 颜家振; 苑博

    2011-01-01

    采用新型的Cu-Mn-Ni-Si钎料真空钎焊2Cr13不锈钢,研究了钎焊温度和保温时间对接头组织和室温力学性能的影响.结果表明:钎焊接头组织由钎缝中心区Cu-Mn基固溶体和钎缝界面反应区的(Fe,Ni,Mn)- Si化合物组成.随着钎焊温度的增加,钎缝界面处化合物层厚度减小,Cu-Mn基固溶体相应增多,接头室温剪切强度随之增加,在钎焊时间15min、钎焊温度1050℃时达到321 MPa.在钎焊温度1000℃时,接头室温剪切强度随着钎焊保温时间的延长先增加后降低,在钎焊保温时间30min时取得最大值305 MPa.%The effects of brazing temperature and holding time on the microstructure and mechanical property at room-temperature of the brazed stainless steel joint with Cu-Mn-Ni-Si filler metal in vacuum were studied. The results show that the brazed joint is made up of Cu-Mn based solid solution in the middle area of the brazing seam and (Fe.Ni, Mn)-Si intermetallic phase in the reaction area near the interface. The volume of intermetallic phase decreases and joint clearance is primarily occupied by Cu-Mn based solid solution with the increase of brazing temperature, the shear strength of the brazed joint at room-temperature increases with the increase of the brazing temperature and reaches 321 Mpa when brazing holding time is 15 min and brazing temperature is 1050 °C . The shear strength of the brazed joint at room-temperature increases first and then decreases with the increase of the brazing holding times, and reaches 305 Mpa when the brazing holding time is 30 min.

  5. Electrochemical Behavior and Hydrophobic Properties of CrN and CrNiN Coatings in Simulated Proton Exchange Membrane Fuel Cell Environment

    Directory of Open Access Journals (Sweden)

    JIN Jie

    2016-10-01

    Full Text Available The CrN and CrNiN coatings were prepared on the surface of 304 stainless steel by closed field unbalanced magnetron sputtering.X ray diffraction and field emission scanning electron microscopy were used to characterize the structure and morphology of the coatings.The electrochemical corrosion properties under the simulated proton exchange membrane fuel cell(PEMFC environment, interfacial contact resistance and hydrophobic properties of the two kinds of different coatings were investigated by electrochemical methods,contact resistance test and hydrophobic test,respectively.The results indicate that CrN coating mainly consists of CrN and Cr2N phase,CrN and Cr2N phases in the CrNiN coating are less compared to CrN film, and Ni exist as element in CrNiN coating; dynamic polarization tests show the coating is of better corrosion resistance,whereas the corrosion resistance of CrNiN coating is worse than that of CrN coating,constant potential polarization test shows the corrosion current density of CrN and CrNiN coatings are equivalent; CrN and CrNiN coatings significantly reduce the interfacial contact resistance of the 304 stainless steel,among which CrN coating has the smallest contact resistance; and CrNiN coating which has better hydrophobicity than that of CrN coating is more beneficial for the water management in proton exchange membrane fuel cell.

  6. Hardness and wear properties of laminated Cr-Ni coatings formed by electroplating

    Science.gov (United States)

    Riyadi, Tri Widodo Besar; Masyrukan

    2017-04-01

    In this work, a laminated structure of Cr-Ni coating was prepared using electroplating on carbon steel substrates. Two baths of chrome and nickel electrolyte solutions were prepared to deposit laminated Cr and Ni layers. Chrome was firstly plated on a steel substrate in constant routes whereas nickel was subsequently electroplated on the Cr coating using varied plating times. The effect of Ni plating time on the thickness, hardness and wear specific of the Ni layer was investigated. The results show that an increase of plating times increased the thickness and hardness of the Ni layer, but reduced the wear specific. This study showed that Ni can be a potential candidate as a material replacement for chromium plating maintenance.

  7. Exchange biased FeNi/FeMn bilayers with coercivity and switching field enhanced by FeMn surface oxidation

    Directory of Open Access Journals (Sweden)

    A. V. Svalov

    2013-09-01

    Full Text Available FeNi/FeMn bilayers were grown in a magnetic field and subjected to heat treatments at temperatures of 50 to 350 °C in vacuum or in a gas mixture containing oxygen. In the as-deposited state, the hysteresis loop of 30 nm FeNi layer was shifted. Low temperature annealing leads to a decrease of the exchange bias field. Heat treatments at higher temperatures in gas mixture result in partial oxidation of 20 nm thick FeMn layer leading to a nonlinear dependence of coercivity and a switching field of FeNi layer on annealing temperature. The maximum of coercivity and switching field were observed after annealing at 300 °C.

  8. Nanocomposite coatings based on Ti-N-Cr/Ni-Cr-B-Si-Fe, gained by two technologies

    Directory of Open Access Journals (Sweden)

    N.K. Erdybayeva

    2009-01-01

    Full Text Available The first results of manufacturing and investigations of a new type of nanocomposite protective coatings are presented. They were manufactured using a combination of two technologies: plasma-detonation coating deposition with the help of plasma jets and thin coating vacuum-arc deposition. We investigated structure, morphology, physical and mechanical properties of the coatings of 80-90 μm thickness, as well as defined the hardness, elastic Young modulus and their corrosion resistance in different media. Grain dimensions of the nanocomposite coatings on Ti-N-Cr base varied from 2.8 to 4 nm. The following phases and compounds formed as a result of plasma interaction with the thick coating surface were found in the coatings: Ti-N-Cr (200, (220, y-Ni3-Fe, a hexagonal Cr2-Ti, Fe3-Ni, (Fe, NiN and the following Ti-Ni compounds: Ti2Ni, Ni3Ti, Ni4Ti, etc. We also found that the nanocomposite coating microhardness increased to H = 31.6 ± 1.1 GPa. The Young elastic modulus was determined to be E = 319 ± 27 GPa – it was derived from the loading-unloading curves. The protective coating demonstrated the increased corrosion resistance in acidic and alkaline media in comparison with that of the stainless steel substrate.

  9. Room temperature ferromagnetism in Mn-doped NiO nanoparticles

    Science.gov (United States)

    Layek, Samar; Verma, H. C.

    2016-01-01

    Mn-doped NiO nanoparticles of the series Ni1-xMnxO (x=0.00, 0.02, 0.04 and 0.06) are successfully synthesized using a low temperature hydrothermal method. Samples up to 6% Mn-doping are single phase in nature as observed from powder x-ray diffraction (XRD) studies. Rietveld refinement of the XRD data shows that all the single phase samples crystallize in the NaCl like fcc structure with space group Fm-3m. Unit cell volume decreases with increasing Mn-doping. Pure NiO nanoparticles show weak ferromagnetism, may be due to nanosize nature. Introduction of Mn within NiO lattice improves the magnetic properties significantly. Room temperature ferromagnetism is found in all the doped samples whereas the magnetization is highest for 2% Mn-doping and then decreases with further doping. The ZFC and FC branches in the temperature dependent magnetization separate well above 350 K indicating transition temperature well above room temperature for 2% Mn-doped NiO Nanoparticle. The ferromagnetic Curie temperature is found to be 653 K for the same sample as measured by temperature dependent magnetization study using vibrating sample magnetometer (VSM) in high vacuum.

  10. Electrical manipulation of ferromagnetic NiFe by antiferromagnetic IrMn

    Science.gov (United States)

    Tshitoyan, V.; Ciccarelli, C.; Mihai, A. P.; Ali, M.; Irvine, A. C.; Moore, T. A.; Jungwirth, T.; Ferguson, A. J.

    2015-12-01

    We demonstrate that an antiferromagnet can be employed for a highly efficient electrical manipulation of a ferromagnet. In our study, we use an electrical detection technique of the ferromagnetic resonance driven by an in-plane ac current in a NiFe/IrMn bilayer. At room temperature, we observe antidampinglike spin torque acting on the NiFe ferromagnet, generated by an in-plane current driven through the IrMn antiferromagnet. A large enhancement of the torque, characterized by an effective spin-Hall angle exceeding most heavy transition metals, correlates with the presence of the exchange-bias field at the NiFe/IrMn interface. It highlights that, in addition to the strong spin-orbit coupling, the antiferromagnetic order in IrMn governs the observed phenomenon.

  11. Martensitic transformation in Cu-doped NiMnGa magnetic shape memory alloys

    Institute of Scientific and Technical Information of China (English)

    Li Pan-Pan; Wang Jing-Min; Jiang Cheng-Bao

    2011-01-01

    This paper studies the martensitic transformation in the Cu-doped NiMnGa alloys. The orthorhombic martensite transforms to L21 cubic austenite by Cu substituting for Ni in the Ni50-x:CuxMn31Ga19 (x=2-10) alloys, the martensitic transformation temperature decreases significantly with the rate of 40 K per Cu atom addition. The variation of the Fermi sphere radius (kF) is applied to evaluate the change of the martensitic transformation temperature. The increase of kF leads to the increase of the martensitic transformation temperature.

  12. The change of NiCrBSi alloys’ phase composition after plasma spraying

    Directory of Open Access Journals (Sweden)

    A. Dudek

    2008-08-01

    Full Text Available Material for investigations was NiCrBSi powder for components’ coatings which improve their corrosion resistance as well as resistance to friction wear and erosion. Plasma spraying method was used to produce a coating with thickness of 300 μm on low-alloy steel which was then remelted with the base material. Using X-ray quality analysis, phase composition was determined for: NiCrBSi powder, obtained coating and the alloyed surface layer. Crystallinity degree was also calculated for NiCrBSi layer sprayed on the base material.

  13. Martensitic transformation and magnetic properties of manganese-rich Ni-Mn-In and Ni-Mn-Sn Heusler alloys; Untersuchung der martensitischen Umwandlung und der magnetischen Eigenschaften Mangan-reicher Ni-Mn-In- und Ni-Mn-Sn-Heusler-Legierungen

    Energy Technology Data Exchange (ETDEWEB)

    Krenke, T.

    2007-06-29

    In the present work, the martensitic transition and the magnetic properties of Manganese rich Ni{sub 50}Mn{sub 50-x}Sn{sub x} and Ni{sub 50}Mn{sub 50-y}In{sub y} alloys with 5 at%{<=}x(y){<=}25 at% were investigated. Calorimetry, X-ray and neutron diffraction, magnetization, and strain measurements were performed on polycrystalline samples. It was shown that alloys close to the stoichiometric composition Ni{sub 50}Mn{sub 25}Sn{sub 25} and Ni{sub 50}Mn{sub 25}Sn{sub 25} do not exhibit a structural transition on lowering of the temperature, whereas alloys with x{<=}15 at% Tin and y{<=}16 at% Indium transform martensitically. The structural transition temperatures increase linearly with decreasing Tin or Indium content. The crystal structures of the low temperature martensite are modulated as well as unmodulated. Alloys with compositions close to stoichiometry are dominated by ferromagnetic interactions, whereas those close to the binary composition Ni{sub 50}Mn{sub 50} order antiferromagnetically. Ferromagnetic order and structural instability coexist in a narrow composition range between 13 at%{<=}x{<=}15 at% and 15 at%{<=}x{<=}16 at% for Ni{sub 50}Mn{sub 50-x}Sn{sub x} and Ni{sub 50}Mn{sub 50-y}In{sub y} respectively. As a consequence, interesting magnetoelastic effects are observed. The Ni{sub 50}Mn{sub 34}In{sub 16} alloy shows a magnetic field-induced structural transition, whereby application of an external magnetic field in the martensitic state stabilizes the high temperature L2{sub 1} structure. Evidence for this was given by neutron diffraction experiments in external magnetic fields. Moreover, the structural transition temperatures of this alloy show large magnetic field dependencies. By use of calorimetry, M(T), and strain measurements, changes in M{sub s} up to -11 K/Tesla are observed. Such large values have, until now, not been observed in Heusler alloys. Since during transformation the volume changes reversibly, magnetic field-induced strains of about

  14. Application of atomic Hirshfeld surface analysis to intermetallic systems: is Mn in cubic CeMnNi4 a thermoelectric rattler atom?

    Science.gov (United States)

    Jørgensen, Mads R V; Skovsen, Iben; Clausen, Henrik F; Mi, Jian-Li; Christensen, Mogens; Nishibori, Eiji; Spackman, Mark A; Iversen, Bo B

    2012-02-06

    The Mn atom in the cubic polymorph of CeMnNi(4) appears to be located in an oversized cage-like structure, and anomalously large atomic displacement parameters (ADPs) for the Mn atom indicate that it is a potential "rattler" atom. Here, multitemperature synchrotron powder X-ray diffraction data measured between 110 and 900 K are used to estimate ADPs for the Mn "guest" atom and the "host" structure atoms in cubic CeMnNi(4). The ADPs are subsequently fitted with Debye and Einstein models, giving Θ(D) = 301(2) K for the "host" structure and Θ(E) = 165(2) K for the Mn atom. This is higher than typical Einstein temperatures for rattlers in thermoelectric skutterudites and clathrates (Θ(E) = 50-80 K), indicating that the Mn atom in cubic CeMnNi(4) is more strongly bonded. In order to probe the chemical interactions of the potential Mn rattler atom, atomic Hirshfeld surface (AHS) analysis is carried out and compared with AHS analysis of well-established guest atom rattlers in archetypical skutterudites, MCoSb(3). Surprisingly, the skutterudite rattlers have more deformed AHSs than the Mn atom in cubic CeMnNi(4). This is related to the highly ionic nature of the skutterudite rattlers, which is not taken into account in the neutral spherical atom approach of the AHS. Additionally, visualization of void spaces in the two materials using the procrystal electron density shows that while the Mn atom is tightly fitting in the CeMnNi(4) structure then the La atom in the skutterudite is truly situated in an oversized cage of the host structure. Overall, we conclude that the Mn atom in cubic CeMnNi(4) cannot be coined a rattler.

  15. Interfacial Ferromagnetism in LaNiO3/CaMnO3 Superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Grutter, Alexander J.; Yang, Hao; Kirby, B. J.; Fitzsimmons, M. R.; Aguiar, Jeffery A.; Browning, Nigel D.; Jenkins, C. A.; Arenholz, Elke; Mehta, V. V.; Alaan, U. S.; Suzuki, Y.

    2013-08-01

    We observe interfacial ferromagnetism in superlattices of the paramagnetic metal LaNiO3 and the antiferromagnetic insulator CaMnO3. LaNiO3 exhibits a thickness dependent metal-insulator transition and we find the emergence of ferromagnetism to be coincident with the conducting state of LaNiO3. That is, only superlattices in which the LaNiO3 layers are metallic exhibit ferromagnetism. Using several magnetic probes, we have determined that the ferromagnetism arises in a single unit cell of CaMnO3 at the interface. Together these results suggest that ferromagnetism can be attributed to a double exchange interaction among Mn ions mediated by the adjacent itinerant metal.

  16. Interfacial ferromagnetism in LaNiO3/CaMnO3 superlattices.

    Science.gov (United States)

    Grutter, A J; Yang, H; Kirby, B J; Fitzsimmons, M R; Aguiar, J A; Browning, N D; Jenkins, C A; Arenholz, E; Mehta, V V; Alaan, U S; Suzuki, Y

    2013-08-23

    We observe interfacial ferromagnetism in superlattices of the paramagnetic metal LaNiO3 and the antiferromagnetic insulator CaMnO3. LaNiO3 exhibits a thickness dependent metal-insulator transition and we find the emergence of ferromagnetism to be coincident with the conducting state of LaNiO3. That is, only superlattices in which the LaNiO3 layers are metallic exhibit ferromagnetism. Using several magnetic probes, we have determined that the ferromagnetism arises in a single unit cell of CaMnO3 at the interface. Together these results suggest that ferromagnetism can be attributed to a double exchange interaction among Mn ions mediated by the adjacent itinerant metal.

  17. On the rich magnetic phase diagram of (Ni, Co)-Mn-Sn Heusler alloys

    Science.gov (United States)

    Grünebohm, A.; Herper, H. C.; Entel, P.

    2016-10-01

    We put a spotlight on the exceptional magnetic properties of the metamagnetic Heusler alloy (Ni, Co)-Mn-Sn by means of first principles simulations. In the energy landscape we find a multitude of local minima, which belong to different ferrimagnetic states and are close in total magnetization and energy. All these magnetic states correspond to the local high spin state of the Mn atoms with different spin alignments and are related to the magnetic properties of Mn. Compared to pure Mn, the magneto-volume coupling is reduced by Ni, Co and Sn atoms in the lattice and no local low-spin Mn states appear. For the cubic phase we find a ferromagnetic ground state whereas the global energy minimum is a tetragonal state with a complicated spin structure and vanishing magnetization which so far has been overlooked in simulations.

  18. Crack Free Tungsten Carbide Reinforced Ni(Cr) Layers obtained by Laser Cladding

    Science.gov (United States)

    Amado, J. M.; Tobar, M. J.; Yáñez, A.; Amigó, V.; Candel, J. J.

    The development of hardfacing coatings has become technologically significant in many industries A common approach is the production of metal matrix composites (MMC) layers. In this work NiCr-WC MMC hardfacing layers are deposited on C25 steel by means of laser cladding. Spheroidal fused tungsten carbides is used as reinforcement phase. Three different NiCr alloys with different Cr content were tested. Optimum conditions to obtain dense, uniform carbide distribution and hardness close to nominal values were defined. The effect of Cr content respect to the microstructure, susceptibility for cracking and the wear rate of the resulting coating will also be discussed.

  19. Structure, magnetism, and electron-transport properties of Mn2CrGa-based nanomaterials

    Directory of Open Access Journals (Sweden)

    Wenyong Zhang

    2016-05-01

    Full Text Available Mn2CrGa in the disordered cubic structure has been synthesized using rapid quenching and subsequent annealing. The cubic phase transforms to a stable tetragonal phase when a fraction of Cr or Ga is replaced by Pt or Al, respectively. All samples are ferrimagnetic with high Curie temperatures (Tc; Mn2CrGa exhibits the highest Tc of about 813 K. The tetragonal samples have appreciable values of magnetocrystalline anisotropy energy, which leads to an increase in coercivity (Hc that approaches about 10 kOe in the Pt-doped sample. The Hc linearly increases with a decrease of temperature, concomitant with the anisotropy change with temperature. All samples are metallic and show negative magnetoresistance with room-temperature resistivities on the order of 1 mΩcm. The magnetic properties including high Tc and low magnetic moment suggest that these tetragonal materials have potential for spin-transfer-torque-based devices.

  20. ALLOYING EFFECT OF Ni AND Cr ON THE WETTABILITY OF COPPER ON W SUBSTRATE

    Institute of Scientific and Technical Information of China (English)

    X.H.Yang; P.Xiao; S.H.Liang; J.T.Zou; Z.K.Fan

    2008-01-01

    By the sessile drop technique, the wettability of Cu/W systems with the additions of Ni and Cr has been studied under vacuum atmosphere. Effects of Ni and Cr contents and wetting temperatures on the wettability and the wetting mechanisms of copper on W substrate have been investigated in detail. The results show that the wetting angles of Cu on the W substrate are decreased with an increase in the content of Ni or Cr, and also decrease with raising the wetting temperatures. SEM, EPMA, and X-ray diffraction have been used to analyze the interracial characteristics of the CuNi/W and CuCr/W systems. The results reveal that there is a transition layer about 2-3 μm in the interface of Cu-4.0 wt pet Ni/W, in which the intermetallic phase Ni4W is precipitated. As to CuCr/W system, no reaction occurs at the interface. The two factors are that the contents of Cr and Ni and the infiltration temperature must be chosen appropriately in order to control the interfacial dissolution and reaction when the Cu-W alloys are prepared by the infiltration method.

  1. High Temperature Behavior of Cr3C2-NiCr Coatings in the Actual Coal-Fired Boiler Environment

    Science.gov (United States)

    Bhatia, Rakesh; Sidhu, Hazoor Singh; Sidhu, Buta Singh

    2015-03-01

    Erosion-corrosion is a serious problem observed in steam-powered electricity generation plants, and industrial waste incinerators. In the present study, four compositions of Cr3C2-(Ni-20Cr) alloy coating powder were deposited by high-velocity oxy-fuel spray technique on T-91 boiler tube steel. The cyclic studies were performed in a coal-fired boiler at 1123 K ± 10 K (850 °C ± 10 °C). X-ray diffraction, scanning electron microscopy/energy dispersive X-ray analysis and elemental mapping analysis techniques were used to analyze the corrosion products. All the coatings deposited on T-91 boiler tube steel imparted hot corrosion resistance. The 65 pctCr3C2 -35 pct (Ni-20Cr)-coated T-91 steel sample performed better than all other coated samples in the given environment.

  2. The ability of Typha domingensis to accumulate and tolerate high concentrations of Cr, Ni, and Zn.

    Science.gov (United States)

    Mufarrege, M M; Hadad, H R; Di Luca, G A; Maine, M A

    2015-01-01

    The tolerance and removal efficiency of Typha domingensis exposed to high concentrations of Cr, Ni, and Zn in single and combined treatments were studied. Sediment and two plants were disposed in each plastic reactor. The treatments were 100 and 500 mg L(-1) of Cr, Ni, and Zn (single solutions); 100 mg L(-1) Cr + Ni + Zn (multi-metal solutions) and 500 mg L(-1) Cr + Ni + Zn (multi-metal solutions); and a control. Even though the concentrations studied were extremely high, simulating an accidental metal dump, the three metals were efficiently removed from water. The highest removal was registered for Cr. The presence of other metals favored Cr and did not favor Ni and Zn removal from water. After 25 days, senescence and chlorosis of plants were observed in Ni and Comb500 treatments, while Cr and Zn only caused growth inhibition. T. domingensis accumulated high metal concentrations in tissues. The roots showed higher metal concentration than submerged parts of leaves. Cr translocation to aerial parts was enhanced by the presence of Ni and Zn. Our results demonstrate that in the case of an accidental dump of high Cr, Ni, and Zn concentrations, a wetland system dominated by T. domingensis is able to retain metals, and the macrophyte is able to tolerate them the time necessary to remove them from water. Thus, the environment will be preserved since the wetland would act as a cushion.

  3. Electron microscopy characterization of Ni-Cr-B-Si-C laser deposited coatings.

    Science.gov (United States)

    Hemmati, I; Rao, J C; Ocelík, V; De Hosson, J Th M

    2013-02-01

    During laser deposition of Ni-Cr-B-Si-C alloys with high amounts of Cr and B, various microstructures and phases can be generated from the same chemical composition that results in heterogeneous properties in the clad layer. In this study, the microstructure and phase constitution of a high-alloy Ni-Cr-B-Si-C coating deposited by laser cladding were analyzed by a combination of several microscopy characterization techniques including scanning electron microscopy in secondary and backscatter imaging modes, energy dispersive spectroscopy (EDS), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). The combination of EDS and EBSD allowed unequivocal identification of micron-sized precipitates as polycrystalline orthorhombic CrB, single crystal tetragonal Cr5B3, and single crystal hexagonal Cr7C3. In addition, TEM characterization showed various equilibrium and metastable Ni-B, Ni-Si, and Ni-Si-B eutectic products in the alloy matrix. The findings of this study can be used to explain the phase formation reactions and to tune the microstructure of Ni-Cr-B-Si-C coatings to obtain the desired properties.

  4. Effect of NiCrAlY Content on Mechanical and Dielectric Properties of NiCrAlY/Al2O3 Composite Coatings%NiCrAlY含量对NiCrAlY/Al2O3涂层机械性能及介电性能的影响

    Institute of Scientific and Technical Information of China (English)

    武志红; 周万城; 罗发; 朱冬梅

    2013-01-01

    采用大气等离子喷涂技术,以镍基合金(NiCrAlY合金)粉为吸收剂、氧化铝(Al2O3)为基体,制备出NiCrAlY/Al2O3(NA)复合涂层.分析了复合涂层的相组成及显微结构,研究了 NiCrAlY含量变化对复合涂层的机械性能及介电性能的影响.结果表明:喷涂后的涂层中出现了刚玉、铬刚玉等非金属相及唯一的金属相Ni.随着NiCrAlY含量的增加,复合涂层的抗弯强度、断裂韧性逐渐增强;在8.2~12.4 GHz频率范围内,涂层的介电常数实部与虚部值都随着NiCrAlY含量的变化而明显变化,且在NiCrAlY含量为25%时达到最高值,这主要与喷涂过程中分离出金属Ni的含量、冷却后的形状及分布状态有关.%NiCrAlY/Al2O3 (NA) composite coatings were fabricated by a plasma spraying method with nickel-based (NiCrAlY) par-tides as an absorber and A12O3 as a matrix. The phase composition and microstructure of these coatings were characterized by X-ray diffraction and scanning electron microscopy, respectively. The mechanical and dielectric properties of the NA composite coatings with different NiCrAlY contents were investigated. The results indicate that the non-metallic phases (i.e., corundum and chromium corundum) and the metal phase nickel generate in the composite coatings. The bending resistance and fracture toughness all increased with increasing NiCrAlY content. The real part and the imaginary part of permittivity both changed in the frequency range of 8.2-12A GHz, and they reached the maximum values at NiCrAlY content of 25% mainly due to various amounts, solidified shapes and distributions of nickel in the composite coatings.

  5. [Effect of different heat treatment on mechanical properties and microstructure of laser welding CoCr-NiCr dissimilar alloys].

    Science.gov (United States)

    Liang, Rui-ying; Li, Chang-yi; Han, Ya-jing; Hu, Xin; Zhang, Lian-yun

    2008-11-01

    To evaluate the effect of heat treatment and porcelain-fused-to-metal (PFM) processing on mechanical properties and microstructure of laser welding CoCr-NiCr dissimilar alloys. Samples of CoCr-NiCr dissimilar alloys with 0.5 mm thickness were laser-welded single-side under the setting parameters of 280 V, 10 ms pulse duration. After being welded, samples were randomly assigned to three groups, 10 each. Group1 and 2 received heat treatment and PFM processing, respectively. Group 3 was control group without any treatment. Tensile strength, microstructure and element distribution of samples in the three groups were tested and observed using tensile test, metallographic examinations, scanning electron microscope (SEM), and energy dispersive spectroscopy (EDS) analysis. After heat treatment and PFM processing, tensile strength of the samples were (537.15 +/- 43.91) MPa and (534.58 +/- 48.47) MPa respectively, and elongation rates in Group 1 and 2 were (7.65 +/- 0.73)% and (7.40 +/- 0.45)%. Ductile structure can be found on tensile fracture surface of samples and it was more obvious in heat treatment group than in PFM group. The results of EDS analysis indicated that certain CoCr alloy diffused towards fusion zone and NiCr side after heat treatment and PFM processing. Compared with PFM processing group, the diffusion in the heat treatment group was more obvious. Heat treatment and PFM processing can improve the mechanical properties and microstructure of welded CoCr-NiCr dissimilar alloy to a certain degree. The improvements are more obvious with heat treatment than with porcelain treatment.

  6. 等离子喷涂NiCrAl涂层工艺优化研究%Optimization of process parameters for plasma spraying of NiCrAl

    Institute of Scientific and Technical Information of China (English)

    纪朝辉; 郑广智; 邹慧; 王志平

    2010-01-01

    采用Metco443NS(成分NiCrAl)粉末和PARXAIR-3710等离子喷涂系统制备NiCrAl涂层,为了使NiCrAl等离子喷涂涂层获得优良的涂层性能,选择涂层结合强度为判据,通过正交试验对NiCrAl等离子喷涂工艺进行了优化.利用扫描电镜, Axio Imager.A 1 m金相图像分析系统等手段对涂层界面形貌和孔隙率进行分析,同时对涂层的结合强度以及显微硬度进行测试.确定优化后的喷涂工艺参数为: 喷涂电流为700 A,喷涂距离140 mm,主气流量56.6 L/min,辅气流量28.3 L/min.研究结果表明, 喷涂电流、喷涂距离、主气流量、辅气流量对NiCrAl涂层结合强度具有不同的影响,在优化的喷涂工艺参数条件下, NiCrAl涂层结合强度为59.23 MPa,显微硬度为268HV, 孔隙率为4.97%.

  7. 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)

  8. Surface tension of molten Ni-(Cr, Co, W) alloys and segregation of elements

    Institute of Scientific and Technical Information of China (English)

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

    2008-01-01

    Surface tension of molten Ni-(Cr, Co, W) alloys was measured at the temperature of 1 773-1 873 K in an Ar+3%H2 atmosphere using an improved sessile drop method. The segregation of Cr, Co and W in alloy was calculated and analyzed using Butler's equation. The results show a good agreement between measured and calculated data. The surface tension of molten Ni-(Cr,Co, W) alloys decreases with increasing temperature. In Ni-(Cr, Co, W) alloys, the element with lower surface tension tends to segregate on the surface of molten alloy while that with higher surface tension tends to segregate inside of the molten alloy. The larger the differences in surface tension, atom radius and electron configuration between solvent and solute are, the more significant the segregation is. As a result, Ni segregates onto the surface and Co and W segregate inside the alloys.

  9. Local Structure and Short-Range Order in a NiCoCr Solid Solution Alloy

    Science.gov (United States)

    Zhang, F. X.; Zhao, Shijun; Jin, Ke; Xue, H.; Velisa, G.; Bei, H.; Huang, R.; Ko, J. Y. P.; Pagan, D. C.; Neuefeind, J. C.; Weber, W. J.; Zhang, Yanwen

    2017-05-01

    Multielement solid solution alloys are intrinsically disordered on the atomic scale, and many of their advanced properties originate from the local structural characteristics. The local structure of a NiCoCr solid solution alloy is measured with x-ray or neutron total scattering and extended x-ray absorption fine structure (EXAFS) techniques. The atomic pair distribution function analysis does not exhibit an observable structural distortion. However, an EXAFS analysis suggests that the Cr atoms are favorably bonded with Ni and Co in the solid solution alloys. This short-range order (SRO) may make an important contribution to the low values of the electrical and thermal conductivities of the Cr-alloyed solid solutions. In addition, an EXAFS analysis of Ni ion irradiated samples reveals that the degree of SRO in NiCoCr alloys is enhanced after irradiation.

  10. An index to PGE-Ni-Cr deposits and occurrences in selected mineral-occurrence databases

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The data in Ni_Cr_PGE shapefile was obtained by compiling records of sites containing nickel, chromium, or one of the platinum group elements from published...

  11. Improving Corrosion Resistance of Q235 Steel by Ni-Cr Alloyed Layer

    Institute of Scientific and Technical Information of China (English)

    HUANG Jun; ZHANG Pingze; WU Hongyan; BI Qiang

    2012-01-01

    Ni-Cr alloyed layer was formed on surface of Q235 steel by double glow plasma surface metallurgy to improve the corrosion resistance of substrate.The composition and microstructure of alloyed layer was analyzed by SEM and XRD.Potentiodynamic polarization and electrochemical impedance spectroscopy was applied to evaluate the corrosion resistance of the alloyed layer.The results showed working pressure had a great effect on structure of Ni-Cr alloyed layer,and the dense and smooth alloyed layer was prepared at 50 Pa working pressure.Compared with substrate,Ni-Cr alloyed layer exhibited higher corrosion potential,lower corrosion current density and larger charge transfer resistance,which indicated that Ni-Cr alloyed layer significantly modified the corrosion resistance of Q235 steel.

  12. Research and fabrication of NiCrAlY thin-film strain gauges%NiCrAlY薄膜应变计的研制

    Institute of Scientific and Technical Information of China (English)

    张洁; 杨晓东; 蒋书文; 蒋洪川; 赵晓辉; 张万里

    2015-01-01

    NiCrAlY thin film strain gauges are deposited on the nickel-based superalloy by radio-frequency magnetron sputtering. The effects of stabilized heat treatment at 1 000℃ on structure and surface morphology of NiCrAlY thin films are investigated and the electromechanical properties of NiCrAlY thin film strain gauges are measured. After stabilized heat treatment at 1 000℃,a layer of Al2 O3 is formed on the surface of NiCrAlY thin film,which is important cause for excellent high-temperature oxidation resistance. The variation of strain gauge resistance with temperature is linear in the temperature range from room temperature to 800℃. The temperature coefficient of resistance( TCR) is about 290 × 10-6/℃,and gauge factor( GF) is about 2. 1 at room temperature.%采用射频磁控溅射法在Ni基高温合金拉伸件上制备NiCrAlY薄膜应变计。研究了热稳定处理对NiCrAlY薄膜结构、表面形貌的影响,并且测试了NiCrAlY薄膜应变计的电学与应变性能。结果表明:热稳定处理后 NiCrAlY 薄膜应变计由于在表面形成了一层 Al2 O3膜,具有抗高温氧化的特性,在室温~800℃范围内,应变计电阻同温度呈线性变化,电阻温度系数( TCR)约为290×10-6/℃,室温下的应变计系数( GF)为2.1。

  13. Neutron diffraction study of MnNiGa{sub 2}—Structural and magnetic behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Wang, J. L., E-mail: jianli@uow.edu.au [Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, NSW 2522 (Australia); Bragg Institute, ANSTO, Lucas Heights, NSW 2234 (Australia); School of Physical, Environmental and Mathematical Sciences, The University of New South Wales, Canberra, ACT 2600 (Australia); Ma, L.; Wu, G. H. [Institute of Physics, Chinese Academy of Science, Beijing 100190 (China); Hofmann, M. [FRM-II, Technische Universität München, 85747 Garching (Germany); Avdeev, M.; Kennedy, S. J. [Bragg Institute, ANSTO, Lucas Heights, NSW 2234 (Australia); Campbell, S. J. [School of Physical, Environmental and Mathematical Sciences, The University of New South Wales, Canberra, ACT 2600 (Australia); Md Din, M. F.; Dou, S. X. [Institute for Superconductivity and Electronic Materials, University of Wollongong, Wollongong, NSW 2522 (Australia); Hoelzel, M. [FRM-II, Technische Universität München, 85747 Garching (Germany); Fachbereich Materialwissenschaften, Technische Universität Darmstadt, 64287 Darmstadt (Germany)

    2014-05-07

    MnNiGa{sub 2} crystallizes in the L21 (Heusler) structure and has a ferromagnetic ordering temperature T{sub C} ∼ 192 K. Rietveld refinement of the neutron diffraction patterns indicates that the Ga atoms occupy the equivalent 8c position, while Mn and Ni share the 4a (0, 0, 0) and 4b (0.5, 0.5, 0.5) sites with a mixed occupancy of Mn and Ni atoms. It is found that that ∼83% of Mn and ∼17% Ni are located at the 4a site while ∼83% of Ni and ∼17% Mn occupy the 4b site. There is no evidence of a magneto-volume effect around T{sub C}. In agreement with this finding, our detailed critical exponent analyses of isothermal magnetization curves and the related Arrott plots confirm that the magnetic phase transition at T{sub C} is second order.

  14. Martensitic transformation in NiMnGa/Si bimorph nanoactuators with ultra-low hysteresis

    Science.gov (United States)

    Lambrecht, F.; Sagardiluz, N.; Gueltig, M.; Aseguinolaza, I. R.; Chernenko, V. A.; Kohl, M.

    2017-05-01

    We report on the fabrication and in-situ characterization of temperature-dependent electrical resistance and deflection characteristics of free-standing NiMnGa/Si bimorph cantilevers with a NiMnGa layer thickness of 200 nm and a minimum lateral width of 50 nm. The martensitic transformation in the initial NiMnGa/Si bimorph films and nanomachined NiMnGa/Si bimorph cantilevers proceeds in a wide temperature range with a hardly detectable temperature hysteresis width below 1 K. This remarkable behavior is ascribed to the internal stress in the bimorph system that exceeds the stress limit of the critical point terminating the stress-temperature phase diagram as it is known for ferromagnetic shape memory alloys. Temperature-dependent deflection characteristics reveal a competition between the bimorph effect and the shape memory effect, causing beam deflection in opposite directions. The observation of the shape memory effect strongly depends on the NiMnGa/Si thickness ratio, causing a maximum deflection change per beam length of 3% in agreement with finite element simulations.

  15. Effects of Mn and Ni doping on the superconductivity of SmFeAs(O,F)

    Energy Technology Data Exchange (ETDEWEB)

    Singh, S.J., E-mail: shivjees@gmail.com; Shimoyama, J.; Yamamoto, A.; Ogino, H.; Kishio, K.

    2013-11-15

    Highlights: •Doping effects of Mn and Ni on the superconducting properties of Sm 1111 is studied. •We found that these doping strongly deteriorate the superconducting properties. •The slope of upper critical field is improved by Mn doping. •Electron type charge carrier dominates in the transport properties. •Our result suggests that the disorder plays an important role. -- Abstract: We have studied the effects of 3d metal Manganese (Mn) and Nickel (Ni) doping on the superconducting properties of SmFeAs(O,F) bulk samples, synthesized through low temperature synthesis route. Ni-doping depresses the superconductivity but the resistivity becomes still metallic nature. These observations indicate that Ni works as electron donors. In contrast, Mn-doping suppresses the superconductivity faster than the Ni and led to enhanced resistivity especially in the low temperature region, suggesting that Mn ions act as scattering centers. The effects of the transition metal doping in conducting layer (FeAs) has been discussed by the variation of the lattice parameters and resistivity with doping. The temperature dependence of resistivity under external magnetic field has been studied and indicates that the slope of the upper critical field (μ{sub 0}dH{sub c2}/dT) is slightly improved by Mn doping and reached up to −9.5 T K{sup −1}. The normal state thermoelectric power (S) decreases rapidly with Mn and Ni doping, and shows the negative value in the whole temperature region for all samples, suggesting that an electron-type charge carrier dominates in the transport properties.

  16. Cytocompatibility evaluation of NiMnSn meta-magnetic shape memory alloys for biomedical applications.

    Science.gov (United States)

    Guiza-Arguello, Viviana R; Monroe, James A; Karaman, Ibrahim; Hahn, Mariah S

    2016-07-01

    Recently, magnetic shape memory alloys (MSMAs) have emerged as an interesting extension to conventional shape memory alloys (SMAs) due to their capacity to undergo reversible deformation in response to an externally applied magnetic field. Meta-magnetic SMAs (M-MSMAs) are a class of MSMAs that are able to transform magnetic energy to mechanical work by harnessing a magnetic-field induced phase transformation, and thus have the capacity to impose up to 10 times greater stress than conventional MSMAs. As such, M-MSMAs may hold substantial promise in biomedical applications requiring extracorporeal device activation. In the present study, the cytotoxicity and ion release from an Ni50 Mn36 Sn14 atomic percent composition M-MSMA were evaluated using NIH/3T3 fibroblasts. Initial studies showed that the viability of cells exposed to NiMnSn ion leachants was 60 to 67% of tissue culture polystyrene (TCP) controls over 10 to 14 days of culture. This represents a significant improvement in cytocompatibility relative to NiMnGa alloys, one of the most extensively studied MSMA systems, which have been reported to induce 80% cell death in only 48 h. Furthermore, NiMnSn M-MSMA associated cell viability was increased to 80% of TCP controls following layer-by-layer alloy coating with poly(allylamine hydrochloride)/poly(acrylic acid) [PAH/PAA]. Ion release measures revealed that the PAH/PAA coatings decreased total Sn and Mn ion release by 50% and 25%, respectively, and optical microscopy evaluation indicated that the coatings reduced NiMnSn surface oxidation. To our knowledge, this study presents the first cytotoxicity evaluation of NiMnSn M-MSMAs and lays the groundwork for their further biological evaluation. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 853-863, 2016.

  17. 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.

  18. Redox Dynamics of Mixed Metal (Mn, Cr, and Fe) Ultrafine Particles

    Energy Technology Data Exchange (ETDEWEB)

    Nico, Peter S.; Kumfer, Benjamin M.; Kennedy, Ian M.; Anastasio, Cort

    2008-08-01

    The impact of particle composition on metal oxidation state, and on changes in oxidation state with simulated atmospheric aging, are investigated experimentally in flame-generated nanoparticles containing Mn, Cr, and Fe. The results demonstrate that the initial fraction of Cr(VI) within the particles decreases with increasing total metal concentration in the flame. In contrast, the initial Mn oxidation state was only partly controlled by metal loading, suggesting the importance of other factors. Two reaction pathways, one reductive and one oxidative, were found to be operating simultaneously during simulated atmospheric aging. The oxidative pathway depended upon the presence of simulated sunlight and O{sub 3}, whereas the reductive pathway occurred in the presence of simulated sunlight alone. The reductive pathway appears to be rapid but transient, allowing the oxidative pathway to dominate with longer aging times, i.e. greater than {approx}8 hours. The presence of Mn within the particles enhanced the importance of the oxidative pathway, leading to more net Cr oxidation during aging implying that Mn can mediate oxidation by removal of electrons from other particulate metals.

  19. Formation of NiCrAlY laser cladding with preplaced method; Funtai tofu reza kuraddingu ho ni yoru NiCrAlY himaku no keisei

    Energy Technology Data Exchange (ETDEWEB)

    Iwamoto, H. [Chiyoda Chemical Engineering and Construction Co. Ltd., Tokyo (Japan)] Sumikawa, T. [Isuzu Motors Ltd., Tokyo (Japan)] Nishida, K. [Ehime Univ., Ehime (Japan). Graduate School; Nishida, M.; Araki, T. [Ehime Univ., Ehime (Japan). Faculty of Engineering

    1997-05-05

    Cladding technique on the surface of structure materials using high corrosion resistance and wear resistance materials has been used in many fields as compared to conventional one. The heat source for cladding was mainly arc welding, however, these recent years, laser cladding where laser having special characteristics like high control, high output density and so forth is used as a heat source, has been studied. In this report, in order to cope with the change in composition of base material, coating layer formation with preplaced method was studied systematically using NiCrAlY powder formed by mixing mechanically commercial metal powder with raw material powder and low power (1200W) CO2 laser. As a result, good NiCrAlY cladded layer with good composition and with no defect was achieved using basic powder formed by mixing mechanically the metallic powder and commercial organic binder. Cladding of broad area was possible by weaving method even at low power (1200W) CO2 laser. Cladded layer with lower dilution ratio and higher cross sectional area was achieved with smaller powder particle diameter. 9 refs., 11 figs., 4 tabs.

  20. Magnetic properties and hyperfine interactions in Cr8, Cr7Cd, and Cr7Ni molecular rings from 19F-NMR

    Science.gov (United States)

    Bordonali, L.; Garlatti, E.; Casadei, C. M.; Furukawa, Y.; Lascialfari, A.; Carretta, S.; Troiani, F.; Timco, G.; Winpenny, R. E. P.; Borsa, F.

    2014-04-01

    A detailed experimental investigation of the 19F nuclear magnetic resonance is made on single crystals of the homometallic Cr8 antiferromagnetic molecular ring and heterometallic Cr7Cd and Cr7Ni rings in the low temperature ground state. Since the F- ion is located midway between neighboring magnetic metal ions in the ring, the 19F-NMR spectra yield information about the local electronic spin density and 19F hyperfine interactions. In Cr8, where the ground state is a singlet with total spin ST = 0, the 19F-NMR spectra at 1.7 K and low external magnetic field display a single narrow line, while when the magnetic field is increased towards the first level crossing field, satellite lines appear in the 19F-NMR spectrum, indicating a progressive increase in the Boltzmann population of the first excited state ST = 1. In the heterometallic rings, Cr7Cd and Cr7Ni, whose ground state is magnetic with ST = 3/2 and ST = 1/2, respectively, the 19F-NMR spectrum has a complicated structure which depends on the strength and orientation of the magnetic field, due to both isotropic and anisotropic transferred hyperfine interactions and classical dipolar interactions. From the 19F-NMR spectra in single crystals we estimated the transferred hyperfine constants for both the F--Ni2+ and the F--Cd2+ bonds. The values of the hyperfine constants compare well to the ones known for F--Ni2+ in KNiF3 and NiF2 and for F--Cr3+ in K2NaCrF6. The results are discussed in terms of hybridization of the 2s, 2p orbitals of the F- ion and the d orbitals of the magnetic ion. Finally, we discuss the implications of our results for the electron-spin decoherence.

  1. Structural features of Ni-Cr-Si-B materials obtained by different technologies

    Science.gov (United States)

    Kornienko, E. E.; Nikulina, A. A.; Belousova, N. S.; Lazurenko, D. V.; Ivashutenko, A. S.; Kuz'min, V. I.

    2016-11-01

    This study considers the structural features of Ni-Cr-Si-B (Ni - base; 15.1 % Cr; 2 % Si; 2 % B; 0.4 % C) materials obtained by different methods. The self-fluxing coatings were deposited by plasma spraying on the tubes from low carbon steel. Bulk cylinder specimens of 20 mm diameter and 15 mm height were obtained by spark plasma sintering (SPS). The structure and phase composition of these materials were investigated by optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffractometry (XRD). The major phases of coatings and sintered materials are γ-Ni, Ni3B, CrB and Cr7C3. We demonstrate that the particle unmelted in the process of plasma spraying or SPS consist of γ-Ni-NEB eutectic and also CrB and Cr7C3 inclusions. The prolonged exposure of powder to high temperatures as well as slow cooling rates by SPS provide for the growth of the structural components as compared to those of plasma coatings materials. High cooling rates at the plasma spraying by melted particles contribute to the formation of supersaturated solid solution of Cr, Si and Fe in γ-Ni. The structure of the melted particles in sintering material has gradient composition: the core constituted of Ni grains of 10 μm with γ-Ni-Ni3B eutectic on the edges. The results of the experiment demonstrate that the sintering material has a smaller microhardness in comparison with plasma coatings (650 and 850 MPa, respectively), but at the same time the material has higher density (porosity less than 1 %) than plasma coatings (porosity about 2.. .3 %).

  2. Microstructure and Sliding Wear Performance of Cr7C3-(Ni,Cr)3(Al,Cr) Coating Deposited from Cr7C3 In Situ Formed Atomized Powder

    Science.gov (United States)

    Zhu, Hong-Bin; Shen, Jie; Gao, Feng; Yu, Yueguang; Li, Changhai

    2017-01-01

    This work is aimed at developing a new type of Cr7C3-(Ni,Cr)3(Al,Cr) coating for parts used in heavy-duty diesel engines. The feedstock, in which the stripe-shaped Cr7C3 was in situ formed, was firstly prepared by vacuum melting and gas atomization and then subjected by high-velocity oxy-fuel spraying to form the coatings. The carbon content, microstructure and phase constitution of the powders, as well as the sprayed coatings, were analyzed by chemical analysis, SEM and XRD. The hardness and sliding wear performance of the sprayed coatings were also tested and compared to a commercial Cr3C2-NiCr coating used on piston rings. The results showed that the content of carbon in feedstock was almost the same as designed, and that the volume content of in situ formed Cr7C3 was increased with carbon and chromium added. The major phases of the powders and sprayed coatings are Cr7C3 and Cr-alloyed Ni3Al. Only a small amount of carbon lost during the spraying process. As Cr7C3 content increased in the coatings, the microhardness at room temperature was firstly increased to about 1000Hv0.3. The microhardness of the coatings stayed almost constant, while the testing temperature was raised up to 700 °C for 0.5 h, which illustrates the potential application of the investigated coatings under high temperature conditions. The coatings containing 70 and 77 vol.% Cr7C3 showed the most promising wear resistance, lower friction coefficient and better tribological compatibility to gray cast iron counterpart than other tested Cr7C3-(Ni,Cr)3(Al,Cr) coatings and the reference Cr3C2-NiCr coating.

  3. Microstructure and Sliding Wear Performance of Cr7C3-(Ni,Cr)3(Al,Cr) Coating Deposited from Cr7C3 In Situ Formed Atomized Powder

    Science.gov (United States)

    Zhu, Hong-Bin; Shen, Jie; Gao, Feng; Yu, Yueguang; Li, Changhai

    2016-12-01

    This work is aimed at developing a new type of Cr7C3-(Ni,Cr)3(Al,Cr) coating for parts used in heavy-duty diesel engines. The feedstock, in which the stripe-shaped Cr7C3 was in situ formed, was firstly prepared by vacuum melting and gas atomization and then subjected by high-velocity oxy-fuel spraying to form the coatings. The carbon content, microstructure and phase constitution of the powders, as well as the sprayed coatings, were analyzed by chemical analysis, SEM and XRD. The hardness and sliding wear performance of the sprayed coatings were also tested and compared to a commercial Cr3C2-NiCr coating used on piston rings. The results showed that the content of carbon in feedstock was almost the same as designed, and that the volume content of in situ formed Cr7C3 was increased with carbon and chromium added. The major phases of the powders and sprayed coatings are Cr7C3 and Cr-alloyed Ni3Al. Only a small amount of carbon lost during the spraying process. As Cr7C3 content increased in the coatings, the microhardness at room temperature was firstly increased to about 1000Hv0.3. The microhardness of the coatings stayed almost constant, while the testing temperature was raised up to 700 °C for 0.5 h, which illustrates the potential application of the investigated coatings under high temperature conditions. The coatings containing 70 and 77 vol.% Cr7C3 showed the most promising wear resistance, lower friction coefficient and better tribological compatibility to gray cast iron counterpart than other tested Cr7C3-(Ni,Cr)3(Al,Cr) coatings and the reference Cr3C2-NiCr coating.

  4. Properties of Cr3C2-NiCr Cermet Coating Sprayed by High Power Plasma and HVOF Processes

    OpenAIRE

    Otsubo, Fumitaka; Era, Hidenori; Kishitake, K; Uchida, T.

    2000-01-01

    The structure, hardness and shear adhesion strength have beeninvestigated in Cr3C2-NiCr cermet coatings sprayed onto a mild steelsubstrate by 200 kW high power plasma spraying (HPS) and high velocityoxy-fuel (HVOF) processes. Amorphous and supersaturated nickel phasesform in both as-sprayed coatings. The hardness of the HVOF coating ishigher than that of the HPS coating because the HVOF coating containsmore non-melted Cr3C2 carbide particles. On heat-treating at 873 K, theamorphous phase deco...

  5. Spin dependent transport properties of Mn-Ga/MgO/Mn-Ga magnetic tunnel junctions with metal(Mg, Co, Cr) insertion layer

    Energy Technology Data Exchange (ETDEWEB)

    Liang, S. H.; Tao, L. L.; Liu, D. P., E-mail: dpliu@iphy.ac.cn; Han, X. F., E-mail: xfhan@iphy.ac.cn [State Key Laboratory of Magnetism, Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Lu, Y. [Institut Jean Lamour, UMR 7198, CNRS-Nancy Université, BP 239, 54506 Vandoeuvre (France)

    2014-04-07

    We report a first principles theoretical investigation of spin polarized quantum transport in Mn{sub 2}Ga/MgO/Mn{sub 2}Ga and Mn{sub 3}Ga/MgO/Mn{sub 3}Ga magnetic tunneling junctions (MTJs) with the consideration of metal(Mg, Co, Cr) insertion layer effect. By changing the concentration of Mn, our calculation shows a considerable disparity in transport properties: A tunneling magnetoresistance (TMR) ratio of 852% was obtained for Mn{sub 2}Ga-based MTJs, however, only a 5% TMR ratio for Mn{sub 3}Ga-based MTJs. In addition, the influence of insertion layer has been considered in our calculation. We found the Co insertion layer can increase the TMR of Mn{sub 2}Ga-based MTJ to 904%; however, the Cr insertion layer can decrease the TMR by 668%; A negative TMR ratio can be obtained with Mg insertion layer. Our work gives a comprehensive understanding of the influence of different insertion layer in Mn-Ga based MTJs. It is proved that, due to the transmission can be modulated by the interfacial electronic structure of insertion, the magnetoresistance ratio of Mn{sub 2}Ga/MgO/Mn{sub 2}Ga MTJ can be improved by inserting Co layer.

  6. Efficient carbon dioxide electrolysis with metal nanoparticles loaded La0·75Sr0·25Cr0·5Mn0·5O3-δ cathodes

    Science.gov (United States)

    Zhu, Changli; Hou, Linxi; Li, Shisong; Gan, Lizhen; Xie, Kui

    2017-09-01

    Solid oxide electrolysis cells with La0·75Sr0·25Cr0·5Mn0·5O3-δ (LSCM) cathode can electrolyze CO2 to generate chemical fuels. Nevertheless, the cathode performance is limited by its electrocatalytic activity. In this work, metal nanoparticles including Ni, Cu and NiCu metals are successfully impregnated in LSCM electrode to improve its activity. XRD, XPS, SEM and TEM together confirm the metal nanocatalysts are homogeneously distributed on LSCM backbone and therefore create active electrochemical interface for CO2 splitting. Electrical properties of LSCM with impregnated metal nanoparticles are investigated and correlated to electrode performances. Electrochemical measurements show that the NiCu-LSCM demonstrates the optimum performance without degradation after operation for ∼100 h and ∼10 redox cycles. It is believed that the enhanced performance of CO2 electrolysis may be attributed to the synergetic effect of metal nanocatalyst and LSCM ceramic electrode.

  7. CFCC-SiC基底NiCr/NiSi薄膜热电偶制备及性能研究%Fabrication and Characteration of NiCr-NiSi Thin Film Thermocouples on CFCC-SiC Substrate

    Institute of Scientific and Technical Information of China (English)

    马旭轮; 苑伟政; 马炳和; 邓进军

    2014-01-01

    在碳纤维增韧补强碳化硅陶瓷复合材料( CFCC-SiC)表面制备了NiCr/NiSi薄膜热电偶。传感器结构自下而上依次为CFCC-SiC陶瓷基底、SiO2过渡层,Al2 O3绝缘层及NiCr/NiSi热电偶层。对所制备传感器进行了静态标定,其在300℃~700℃范围内具有稳定的热电动势输出,平均Seebeck系数为41.71μV/℃,传感器极限使用温度约为750℃。%NiCr/NiSi thin film thermocouples were fabricated on the surface of carbon fiber reinforced silicon carbide ceramic composites(CFCC-SiC). Structure of the sensor from bottom to top is sequentially CFCC-SiC ceramic substrate, SiO2 buffer layer,Al2 O3 insulated layer and NiCr/NiSi thin film thermocouple layer. The static calibration result of the thin film thermocouples shows that the sensor has a stable thermal electromotive force output from 300℃ to 700℃. The average Seebeck coefficient of the sensor is about 41. 71μV/℃,and its ultimate-use temperature is about 750℃.

  8. EFFECT OF VACUUM HEAT TREATMENT ON OXIDATION BEHAVIOR OF SPUTTERED NiCrA1Y COATING

    Institute of Scientific and Technical Information of China (English)

    M.H.Li; X.F.Sun; Z.Y.Zhang; H.R.Guan; W.Y.Hu; Z.Q.Hu

    2002-01-01

    A bond coat for thermal barrier coating (TBC), NiCrAlY coating, is subjected to vac-uum heat treatment in order to remove internal stress before ceramic top coat is de-posited. The effect of vacuum heat treatment on the oxidation behavior of the sputteredNiCrAlY coating has been investigated. The as-sputtered NiCrAlY coating consists ofγ-Ni and β-NiAl phases. After vacuum heat treatment, the sputtered NiCrAlY coatingmainly consists of γ-Ni3Al, β-NiAl, γ-Ni, and trace of α-Al2O3 phases. The isother-mal oxidation of sputtered NiCrAlY coating with and without vacuum heat treatmenthas been performed at 1000C. It is shown that α-Al2O3 formed during vacuum heattreatment acts as nuclei for the formation of α-Al2O3, and the protective α-Al2O3scale is formed more rapidly on the vacuum heat treated NiCrAlY coating than thatformed on the untreated coating. Also the α-Al2O3 scale has a better adherence to thevacuum heat treated NiCrAlY coating. Therefore the vacuum heat treatment improvesthe oxidation resistance of sputtered NiCrAlY coating.

  9. High-Power Diode Laser-Treated 13Cr4Ni Stainless Steel for Hydro Turbines

    Science.gov (United States)

    Mann, B. S.

    2014-06-01

    The cast martensitic chromium nickel stainless steels such as 13Cr4Ni, 16Cr5Ni, and 17Cr4Ni PH have found wide application in hydro turbines. These steels have adequate corrosion resistance with good mechanical properties because of chromium content of more than 12%. The 13Cr4Ni stainless steel is most widely used among these steels; however, lacks silt, cavitation, and water impingement erosion resistances (SER, CER, and WIER). This article deals with characterizing 13Cr4Ni stainless steel for silt, cavitation, and water impingement erosion; and studying its improved SER, CER, and WIER behavior after high-power diode laser (HPDL) surface treatment. The WIER and CER have improved significantly after laser treatment, whereas there is a marginal improvement in SER. The main reason for improved WIER and CER is due to its increased surface hardness and formation of fine-grained microstructure after HPDL surface treatment. CER and WIER of HPDL-treated 13Cr4Ni stainless steel samples have been evaluated as per ASTM G32-2003 and ASTM G73-1978, respectively; and these were correlated with microstructure and mechanical properties such as ultimate tensile strength, modified ultimate resilience, and microhardness. The erosion damage mechanism, compared on the basis of scanning electron micrographs and mechanical properties, is discussed and reported in this article.

  10. Ni-Cr thin film resistor fabrication for GaAs monolithic microwave integrated circuits

    Energy Technology Data Exchange (ETDEWEB)

    Vinayak, Seema [Solid State Physics Laboratory, Lucknow Road, Delhi-110054 (India)]. E-mail: seema_vinayak@rediffmail.com; Vyas, H.P. [Solid State Physics Laboratory, Lucknow Road, Delhi-110054 (India); Muraleedharan, K. [Defence Metallurgical Research Laboratory, Kanchanbagh, Hyderabad-500058 (India); Vankar, V.D. [Indian Institute of Technology Delhi, Hauz Khas, New Delhi- 110016 (India)

    2006-08-30

    Different Ni-Cr alloys were sputter-deposited on silicon nitride-coated GaAs substrates and covered with a spin-coated polyimide layer to develop thin film metal resistors for GaAs monolithic microwave integrated circuits (MMICs). The contact to the resistors was made through vias in the polyimide layer by sputter-deposited Ti/Au interconnect metal. The variation of contact resistance, sheet resistance (R {sub S}) and temperature coefficient of resistance (TCR) of the Ni-Cr resistors with fabrication process parameters such as polyimide curing thermal cycles and surface treatment given to the wafer prior to interconnect metal deposition has been studied. The Ni-Cr thin film resistors exhibited lower R {sub S} and higher TCR compared to the as-deposited Ni-Cr film that was not subjected to thermal cycles involved in the MMIC fabrication process. The change in resistivity and TCR values of Ni-Cr films during the MMIC fabrication process was found to be dependent on the Ni-Cr alloy composition.

  11. Giant magnetocaloric effect in isostructural MnNiGe-CoNiGe system by establishing a Curie-temperature window

    KAUST Repository

    Liu, E. K.

    2013-03-28

    An effective scheme of isostructural alloying was applied to establish a Curie-temperature window in isostructural MnNiGe-CoNiGe system. With the simultaneous accomplishment of decreasing structural-transition temperature and converting antiferromagnetic martensite to ferromagnetic state, a 200 K Curie-temperature window was established between Curie temperatures of austenite and martensite phases. In the window, a first-order magnetostructural transition between paramagnetic austenite and ferromagnetic martensite occurs with a sharp jump in magnetization, showing a magnetic entropy change as large as −40 J kg−1 K−1 in a 50 kOe field change. This giant magnetocaloric effect enables Mn1− x Co x NiGe to become a potential magnetic refrigerant.

  12. Anisotropic magnetoresistance and current-perpendicular-to-plane giant magnetoresistance in epitaxial NiMnSb-based multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, B.; Sakuraba, Y., E-mail: Yuya.Sakuraba@nims.go.jp; Sukegawa, H.; Li, S.; Furubayashi, T. [National Institute for Materials Science (NIMS), 1-2-1, Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Qu, G.; Hono, K. [National Institute for Materials Science (NIMS), 1-2-1, Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Graduate School Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8571 (Japan)

    2016-01-14

    We fabricated (001)-oriented C1{sub b}-NiMnSb epitaxial films on MgO substrate by a magnetron sputtering system and systematically investigated the structure, magnetic property, and anisotropic magnetoresistance (AMR) effect. NiMnSb film was deposited using a stoichiometric NiMnSb target which has Mn-deficient (Mn ∼ 28.7 at. %) off-stoichiometric composition ratio. We have investigated bulk spin-polarization in NiMnSb films by measuring AMR on the basis of recent study for half-metallic L2{sub 1}-Heusler compounds. Although the negative sign of AMR ratio, which is indicative of half-metallic nature, was observed in the single layer NiMnSb films, the magnitude of AMR ratio (−0.10% at RT) was about half of the largest value reported for half-metallic L2{sub 1}-Heusler compounds. The current-perpendicular-to-plane (CPP) giant magnetoresistance (GMR) devices of NiMnSb/Ag/NiMnSb show MR ratio of 13.2% at 10 K and 4.2% at 300 K, which is higher than the previous result for NiMnSb/Cu/NiMnSb CPP-GMR devices [Caballero et al., J. Magn. Magn. Mater. 198–199, 55 (1999)], but much less than the CPP-GMR using L2{sub 1}-Heusler electrodes. The reduction of intrinsic bulk spin-polarization originating from the Mn-deficiency in NiMnSb layer is expected to be the main reason for small MR values.

  13. Microstructural evidence of presence of beryllium in Ni-Cr alloys for dental prostheses; Evidencia microestrutural da presenca de berilio em ligas Ni-Cr para proteses dentarias

    Energy Technology Data Exchange (ETDEWEB)

    Alkmin, L.B.; Nunes, C.A., E-mail: lba@ppgem.eel.usp.b [Universidade de Sao Paulo (EEL/USP), Lorena, SP (Brazil). Escola de Engenharia; Coelho, G.C. [Centro Universitario de Volta Redonda (UNIFOA), Volta Redonda, RJ (Brazil); Santos, C. [Protmat Materiais Avancados, Guaratingueta, SP (Brazil)

    2010-07-01

    This study aimed to characterize the microstructure of commercial Ni-Cr alloys for dental prosthesis, with special focus on those containing Be. For this, the materials were characterized in terms of chemical composition, phases and melting point temperature. The following techniques were used: X-ray fluorescence, ICP-OES, scanning electron microscopy, electron probe microanalysis, X-ray diffraction and differential thermal analysis. The results clearly showed the presence of a typical eutectic, formed by the Ni{sub ss} and NiBe phases in those alloys containing Be, which can be considered a 'fingerprint' of the presence of this element in these alloys. (author)

  14. Corrosion behavior of NiCr alloys in HCl-containing oxidation atmosphere at 700-800 ℃

    Institute of Scientific and Technical Information of China (English)

    张轲; 牛焱; 潘太军; 吴维(山文)

    2004-01-01

    Corrosion behaviors of pure Ni and three NiCr alloys were investigated in an HCl-containing oxidizing atmosphere at 700 ℃ and 800 ℃. All materials suffer from accelerated corrosion at both temperatures. NiCr alloys show an initial mass loss due to the formation of volatile CrCl3 and CrO2Cl2. Some chlorides are detected at the scale/substrate interface and many voids are also found there. NiCr alloys with higher chromium content have better corrosion resistance. However, Ni50Cr is inferior to Ni25Cr due to its two-phase structure, which makes it easy for chlorine to diffuse along grain boundary and to occur inner oxidation. The relevant corrosion mechanism was also discussed.

  15. Electron Microscopy Characterization of Ni-Cr-B-Si-C Laser Deposited Coatings

    NARCIS (Netherlands)

    Hemmati, I.; Rao, J. C.; Ocelik, V.; De Hosson, J. Th. M.

    During laser deposition of Ni-Cr-B-Si-C alloys with high amounts of Cr and B, various microstructures and phases can be generated from the same chemical composition that results in heterogeneous properties in the clad layer. In this study, the microstructure and phase constitution of a high-alloy

  16. Toughening mechanism for Ni-Cr-B-Si-C laser deposited coatings

    NARCIS (Netherlands)

    Hemmati, I.; Ocelik, V.; De Hosson, J. Th. M.

    2013-01-01

    Laser deposited coatings were made from Colmonoy 69 Ni-Cr-B-Si-C alloy and Nb-modified Colmonoy 69 using laser cladding with powder injection. Addition of Nb was done to decrease the structural scale of Cr boride precipitates by providing Nb-rich nucleation agents. The purpose of the study was to ev

  17. Exchange biasing of single-domain Ni nanoparticles spontaneously grown in an antiferromagnetic MnO matrix

    Energy Technology Data Exchange (ETDEWEB)

    Shoemaker, Daniel P; Grossman, Madeleine; Seshadri, Ram [Materials Department, Materials Research Laboratory, University of California, Santa Barbara, CA 93106 (United States); Department of Chemistry and Biochemistry, Materials Research Laboratory, University of California, Santa Barbara, CA 93106 (United States)], E-mail: dshoe@mrl.ucsb.edu

    2008-05-14

    Exchange biased composites of ferromagnetic single-domain Ni nanoparticles embedded within and on the surface of large grains of MnO have been prepared by the reduction of Ni{sub x}Mn{sub 3-x}O{sub 4} monoliths in flowing 5% H{sub 2}/N{sub 2}. The Ni precipitates are 20-30 nm in extent, and the majority are completely encased within MnO. The manner in which the Ni nanoparticles are spontaneously formed-starting from a single homogeneous phase-ensures a high degree of dispersion of the Ni and large Ni/MnO interface/volume ratios. The interfaces between ferromagnetic Ni and antiferromagnetic MnO result in magnetic exchange bias below the Neel temperature of MnO. A threefold change in exchange bias fields (from 40 to 120 Oe at 5 K) is observed, depending on the starting Ni content x in the precursor Ni{sub x}Mn{sub 3-x}O{sub 4}, with smaller x values-fewer or smaller Ni nanoparticles-resulting in larger exchange fields. The exchange bias leads to significant hardening of the magnetization, with coercive fields scaling nearly linearly with the exchange field. The strategies outlined here suggest new and simple routes for creating highly interfacial, functional biphasic composites of nanoparticles embedded within or supported on an oxide matrix.

  18. Effect of Plastic Deformation on Magnetic Properties of Fe-40%Ni-2%Mn Austenitic Alloy

    Institute of Scientific and Technical Information of China (English)

    Selva Büyükakkas; H Aktas; S Akturk

    2007-01-01

    The effects of plastic deformation on the magnetic properties of austenite structure in an Fe-40%Ni-2%Mn alloy is investigated by using Mssbauer spectroscopy and Differential Scanning Calorimetry (DSC) techniques The morphology of the alloy has been obtained by using Scanning Electron Microscopy (SEM). The magnetic behaviour of austenite state is ferromagnetic. After plastic deformation, a mixed magnetic structure including both paramagnetic and ferromagnetic states has been obtained at the room temperature. The volume fraction changes, the effective hyperfine fields of the ferromagnetic austenite phase and isomery shift values have also been determined by Mssbauer spectroscopy. The Curie point (TC) and the Neel temperature (TN) have been investigated by means of DSC system for non-deformed and deformed Fe-Ni-Mn alloy. The plastic deformation of the alloy reduces the TN and enhances the paramagnetic character of austenitic Fe-Ni-Mn alloy.

  19. The structural and elastic properties of TMB4 (TM = V, Cr, Mn) under pressure: A first-principles study

    Science.gov (United States)

    Wu, Xiao-Long; Zhou, Xiao-Lin; Chang, Jing

    2014-08-01

    The structural and elastic properties of 3d transition metal tetraboride TMB4 (TM = V, Cr, Mn) have been studied by using density functional theory (DFT) within the local density approximation (LDA) and generalized gradient approximation (GGA) for exchange-correlation function. Our results are in agreement well with available experimental data and previous theoretical studies. The full elastic constants and bulk shear modulus of TMB4 (TM = V, Cr, Mn) are obtained in the wide pressure range. Results indicated that these phases of TMB4 (TM = V, Cr, Mn) are strongly pressure dependent. And the CrB4 in Immm structure is the most ultraincompressible among the considered phases at 0 GPa. By the mechanical stability criteria, it is predicted that these phases of TMB4 (TM = V, Cr, Mn) compounds are stable up to 100 GPa. In addition, the calculated B/G ratio indicated that all the structures of TMB4 (TM = V, Cr, Mn) possess brittle nature in the range of pressure from 0 GPa to 100 GPa except the Pnnm structure of MnB4, which is higher than 1.75, indicating that the Pnnm structure of MnB4 is prone to ductility when the pressure is above 73 GPa.

  20. High-temperature oxidation studies of cold-sprayed Ni-20Cr and Ni-50Cr coatings on SAE 213-T22 boiler steel

    Science.gov (United States)

    Bala, Niraj; Singh, Harpreet; Prakash, Satya

    2009-05-01

    The high-temperature oxidation behavior of cold-sprayed Ni-20Cr and Ni-50Cr coatings on SAE 213-T22 boiler steel has been investigated at 900 °C in air under cyclic heating and cooling conditions for 50 cycles. The kinetics of oxidation of coated and bare boiler steel has been established with the help of weight change measurements. It was observed that all the coated and bare steels obeyed parabolic rate law of oxidation. X-ray diffraction, FE-SEM/EDAX and X-ray mapping techniques were used to analyse the oxidation products of the coated and uncoated boiler steel. The uncoated steel suffered corrosion in the form of intense spalling and peeling of its oxide scale, which was perhaps due to the formation of unprotective Fe 2O 3 oxide scale. Both the coatings showed better resistance to the air oxidation as compared to the uncoated steel. The Ni-50Cr coating was found to be more protective than the Ni-20Cr-coated steel. The formation of oxides and spinels of nickel and chromium may be contributing to the development of air oxidation resistance in the coatings.

  1. Cr20Ni80镍铬合金电热丝的热处理%Heat treatment of Cr20Ni80 alloy heating wire

    Institute of Scientific and Technical Information of China (English)

    潘丽霞; 杨燕

    2013-01-01

    通过研究固溶温度和时效温度对Cr20Ni80镍铬合金电热丝硬度、电阻率和线膨胀系数的影响,以确定Cr20Ni80合金的固溶及时效工艺.结果表明,最佳处理工艺为1150℃固溶处理+930℃×10h时效,电热丝的线膨胀系数明显下降,而电阻率无明显变化.%By studying the influence of solid solution temperature and aging temperature on hardness,resistivity,and linear expansion coefficient of Cr20Ni80 alloy heating wire,solid solution and aging process of Cr20Ni80 alloy were determined.The results show that after solid solution at 1150 ℃ and aged at 930 ℃ for 10 h,the linear expansion coefficient decreases significantly,electrical resistivity no change,hardness decreases slightly.

  2. 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

  3. Inverse magnetocaloric effect in Mn{sub 2}NiGa and Mn{sub 1.75}Ni{sub 1.25}Ga magnetic shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Sanjay, E-mail: sanju8419@gmail.com; Barman, S. R. [UGC-DAE Consortium for Scientific Research, Khandwa Road, Indore 452001 (India); Esakki Muthu, S.; Arumugam, S. [Centre for High Pressure Research, School of Physics, Bharathidasan University, Tiruchirappalli 620024 (India); Senyshyn, A. [Forschungsneutronenquelle Heinz Maier-Leibnitz FRM-II, Technische Universität München, Lichtenbergstrasse 1, 85747 Garching b. München (Germany); Rajput, P. [European Synchrotron Radiation Facility, 6 rue Jules Horowitz, F-38000 Grenoble (France); Suard, E. [Institut Laue-Langevin, BP 156, 38042 Grenoble Cedex 9 (France)

    2014-02-03

    Inverse magnetocaloric effect is demonstrated in Mn{sub 2}NiGa and Mn{sub 1.75}Ni{sub 1.25}Ga magnetic shape memory alloys. The entropy change at the martensite transition is larger in Mn{sub 1.75}Ni{sub 1.25}Ga, and it increases linearly with magnetic field in both the specimens. Existence of inverse magnetocaloric effect is consistent with the observation that magnetization in the martensite phase is smaller than the austenite phase. Although the Mn content is smaller in Mn{sub 1.75}Ni{sub 1.25}Ga, from neutron diffraction, we show that the origin of inverse magnetocaloric effect is the antiferromagnetic interaction between the Mn atoms occupying inequivalent sites.

  4. Diffusional transport during the cyclic oxidation of gamma + beta, Ni-Cr-Al(Y, Zr) alloys

    Science.gov (United States)

    Nesbitt, J. A.; Heckel, R. W.

    1988-01-01

    The cyclic oxidation behavior of several cast gamma + beta, Ni-Cr-Al(Y, Zr) alloys and one low-pressure plasma spraying gamma + beta, Ni-Co-Cr-Al(Y) alloy was studied. Cyclic oxidation was found to result in a decreasing Al concentration at the oxide-metal interface due to a high rate of Al consumption coupled with oxide scale cracking and spalling. Diffusion paths plotted on the ternary phase diagram showed higher Ni concentrations with increasing cyclic oxidation exposures. The alloy with the highest rate of Al consumption and the highest Al content underwent breakaway oxidation following 500 1-hr cycles at 1200 C.

  5. Obesidad y enfermedad renal crónica en niños y adolescentes

    OpenAIRE

    Pérez Clemente, Lourdes María

    2015-01-01

    La obesidad y la enfermedad renal crónica forman parte de las grandes epidemias del siglo XXI. El objetivo fue confirmar que los niños obesos tienen un riesgo mayor de enfermedad renal crónica que los que no lo son. Se realizó un estudio observacional, analítico y transversal que incluyó a niños y adolescentes con obesidad exógena. Para comparar los resultados obtenidos en los obesos se seleccionó un grupo de niños normopesos. Se determinaron variables emográficas, antropométricas, clínica...

  6. Diffusional transport during the cyclic oxidation of gamma + beta, Ni-Cr-Al(Y, Zr) alloys

    Science.gov (United States)

    Nesbitt, J. A.; Heckel, R. W.

    1988-01-01

    The cyclic oxidation behavior of several cast gamma + beta, Ni-Cr-Al(Y, Zr) alloys and one low-pressure plasma spraying gamma + beta, Ni-Co-Cr-Al(Y) alloy was studied. Cyclic oxidation was found to result in a decreasing Al concentration at the oxide-metal interface due to a high rate of Al consumption coupled with oxide scale cracking and spalling. Diffusion paths plotted on the ternary phase diagram showed higher Ni concentrations with increasing cyclic oxidation exposures. The alloy with the highest rate of Al consumption and the highest Al content underwent breakaway oxidation following 500 1-hr cycles at 1200 C.

  7. Critical behavior of Y2NiMnO6 double perovskite

    Science.gov (United States)

    Nhalil, Hariharan; Nair, Harikrishnan S.; Elizabeth, Suja

    2016-05-01

    Critical behavior of double perovskite Y2NiMnO6 near the second-order ferromagnetic transition is studied. Scaling exponents calculated frommodified Arrot plots are confirmed by Kouvel-Fisher method and satisfy the Widom's scaling relation. The exponents do not follow any conventional theoretical models.β values areconsistent with 3D-Ising model whileδconformsto TCMF and γ valueclosely relates to the 3D-Heisenberg model. Critical exponents are compared with similar R2NiMnO6 double perovskites which shows that a decrease in size of R ion changes exponents from mean-field to the 3D-Ising model.

  8. Modeling and Characterization of the Magnetocaloric Effect in Ni2MnGa Materials

    Energy Technology Data Exchange (ETDEWEB)

    Nicholson, Don M [ORNL; Odbadrakh, Khorgolkhuu [ORNL; Shassere, Benjamin [ORNL; Rios, Orlando [ORNL; Hodges, Jason P [ORNL; Ludtka, Gerard Michael [ORNL; Porter, Wallace D [ORNL; Safa-Sefat, Athena [ORNL; Rusanu, Aurelian [ORNL; Brown, Greg [ORNL; Evans III, Boyd Mccutchen [ORNL

    2014-01-01

    Magnetic shape memory alloys have great promise as magneto-caloric effect refrigerant materials due to their combined magnetic and structural transitions. Computational and experimental research is reported on the Ni2MnGa material system. The magnetic states of this system are explored using the Wang-Landau statistical approach in conjunction with the Locally Self-consistent Multiple-Scattering method. The effects of alloying agents on the transition temperatures of the Ni2MnGa alloy are investigated using differential scanning calorimetry and superconducting quantum interference device. Experiments are performed at the Spallation Neutron Source at Oak Ridge National Laboratory to observe the structural and magnetic phase transformations.

  9. Hydrogen-induced amorphization in LaNi_(3-x)Mn_x compounds

    Institute of Scientific and Technical Information of China (English)

    王伟; 陈云贵; 陶明大; 吴朝玲

    2010-01-01

    Effects of Mn content on the hydrogen-induced amorphization of LaNi3-xMnx(x=0.0,0.1,0.3 and 0.5) hydrogen storage alloys were studied systematically.All the alloys were prepared using a rapid quenching and annealing method.As the charging time increased,the hydrogen-induced amorphization occurred gradually in all the compounds for the first cycle.During the discharge process,discharge potential plateau was not observed in LaNi3.As Mn content increased,however,structural changes were inhibited partly,and a p...

  10. Thickness dependent exchange bias in martensitic epitaxial Ni-Mn-Sn thin films

    Directory of Open Access Journals (Sweden)

    Anna Behler

    2013-12-01

    Full Text Available A thickness dependent exchange bias in the low temperature martensitic state of epitaxial Ni-Mn-Sn thin films is found. The effect can be retained down to very small thicknesses. For a Ni50Mn32Sn18 thin film, which does not undergo a martensitic transformation, no exchange bias is observed. Our results suggest that a significant interplay between ferromagnetic and antiferromagnetic regions, which is the origin for exchange bias, is only present in the martensite. The finding is supported by ab initio calculations showing that the antiferromagnetic order is stabilized in the phase.

  11. Heat treatment and effects of Cr and Ni in low alloy steel

    Indian Academy of Sciences (India)

    Mohammad Abdur Razzak

    2011-12-01

    The effects of Cr and Ni on low carbon steel was observed. Undissolved carbide particles refine the austenite grain size. In the presence of nickel, chromium carbide is less effective in austenite grain refinement than chromium carbide in absence of nickel at temperature below 975°C. Nickel does not produce any austenite grain refinement but presence of nickel promotes the formation of acicular ferrites. It was also found that Ni and Cr as chromium carbide also refines the ferrite grain size and morphology. Cr as chromium carbide is more effective in refining ferrite grain size than nickel.

  12. Resiliencia en niños enfermos crónicos: aspectos teóricos

    OpenAIRE

    Castro, Elisa Kern de; Moreno-Jiménez, Bernardo

    2007-01-01

    El presente trabajo examina cuestiones relacionadas a la enfermedad crónica, el desarrollo infantil y la resiliencia. La resiliencia es un concepto evolutivo y de la salud que se refiere a la capacidad de adaptación positiva de niños, jóvenes y adultos frente a circunstancias adversas y de riesgo, como es la enfermedad crónica pediátrica. Actualmente existen pocos estudios sobre el tema, pero las evidencias revelan que niños enfermos crónicos se adaptan de una manera superior a la que se espe...

  13. Influence of isothermal quenching of LAMC CrMnSi cast steel on impact toughness

    Institute of Scientific and Technical Information of China (English)

    JIN Bao-shi; HUANG Zhi-qiu; SHEN Da-dong

    2005-01-01

    The influence of isothermal quenching process of low-alloy and medium carbon (LAMC) CrMnSi cast steel on the impact toughness was investigated. The microstructure and mechanical property of LAMC CrMnSi cast steel were analyzed by the laser optical modulator, the scanning electron microscopy, the energy dispersive spectrometer, the hardness and impact tests. The experimental results show that the dual phases of bainite and residual austenite can be obtained by the severity isothermal quenching, the fractographies of specimens change from quasi-cleavage to dimple at 310 ℃ for 60 min, the impact toughness for specimens at the room temperature isothermally achieves 130 J/cm2, meantime and its hardness is more than 45(HRC).

  14. Fatigue properties of 48MnV steel with twin arc spraying 3Cr13 coatings

    Institute of Scientific and Technical Information of China (English)

    ZHANG Guo-qing; SU Bing; PU Geng-qiang; WANG Cheng-tao

    2005-01-01

    The fatigue behaviors of 48MnV steel, both uncoated and coated with different thicknesses of 3Cr13 deposits using twin arc spraying, were investigated. The fatigue properties of the 48MnV steel, determined under axial loading conditions, can be substantially decreased by coating 3Cr13 films, deposited by twin arc spraying. And the fatigue behavior of the thinner coatings is better than that of the thicker ones, of which the fatigue limits decrease by 9%- 14%. The decrease in fatigue life attributes to the less mechanical properties of the coatings in comparison with those of the substrate, their relative bad bonding strength and trapped oxide or Al2O3 particles retain in the matrix after blasting responsible for the initiation of fatigue cracks.

  15. In-plane magnetic anisotropies in Ni/FeMn and Ni90Fe10/FeMn exchange biased bilayers

    Science.gov (United States)

    Pires, M. J. M.; de Oliveira, R. B.; Martins, M. D.; Ardisson, J. D.; Macedo, W. A. A.

    2007-12-01

    The in-plane magnetic anisotropy in Ni/FeMn and Ni90Fe10/FeMn exchange-biased bilayers prepared by co-evaporation under molecular beam epitaxy conditions is investigated employing longitudinal magneto-optical Kerr effect (MOKE) and ferromagnetic resonance (FMR). The exchange anisotropy was induced by a magnetic field cooling immediately after the deposition of the bilayers. Besides the induced term, the presence of an additional uniaxial anisotropy in the FM layers was detected both by MOKE and FMR, and the characteristic directions of these two anisotropy terms are not coincident. The interplay between the anisotropy contributions is discussed considering micromagnetic simulations and the in-plane resonance condition for different magnetic field orientation. X-ray diffraction, X-ray photoelectron spectroscopy, and Mössbauer spectroscopy were used to complement the characterization of the samples.

  16. 溅射Ni16Cr2.5Al微晶涂层及其氧化行为%An Investigation of Deposition Structure of Ni16Cr2.5Al Microcrys Tauine and Its Oxidation Behavisor

    Institute of Scientific and Technical Information of China (English)

    曹硕; 邱巍

    2004-01-01

    NiCrAl是NiCrAlY型包覆涂层的主要成分,对NiCrAl涂层的沉积形态及其氧化行为的研究具有重要科学意义.磁控溅射在不锈钢Fe18Cr9Ni0.1Ti基体上制备出Ni16Cr2.5Al微晶涂层(基体分倾斜45°和竖直90°两种方式悬挂),使用SEM/EDAX,X-ray,对Ni16Cr2.5Al微晶涂层及其氧化膜进行了分析,以探索高温合金用涂层形成及其氧化膜形成机制.

  17. Crystal field and low energy excitations measured by high resolution RIXS at the L edge of Cu, Ni and Mn

    DEFF Research Database (Denmark)

    Ghiringhelli, G.; Piazzalunga, A.; Wang, X.;

    2009-01-01

    of the 3d transition metals with unprecedented energy resolution, of the order of 100 meV for Mn, Ni and Cu. We present here some preliminary spectra on CuO, malachite, NiO, , MnO and . The dd excitations are very well resolved allowing accurate experimental evaluation of 3d state energy splitting. The low...

  18. Paduan Ni-Cu-Mn Sebagai Logam Alternatif Kedokteran Gigi: Efek Perendaman dalam Larutan 0,1% Sodium Sulfida

    Directory of Open Access Journals (Sweden)

    Bambang Irawan

    2015-09-01

    Full Text Available In this study, the ternary base alloys of nickel-copper-manganese (Ni-Cu-Mn alloys are prepared and these ternary alloys systems, which were constituted from higher nickel and lower copper contents than copper-base alloy ones, were evaluated by a tarnish test. Tarnish tests conducted in a 0,1% sodium sulphide solution (pH=12 at 37◦C. All test specimens were case into square paddles of 15 mm x 20 mm x 2,5 mm using the lost-wax technique with a phosphate-bonded investment. The surface of the specimens were then prepared with abrasion papers down to a 600 grit finish. Tarnish attack was quantitatively evaluated by Fibre colorimetry. The results of tarnish test showed that ternary nickel-copper-manganese alloys, such as 40Ni-30Cu-30Mn and 50Ni-30Cu-20Mn, have superior tarnishment resistance than other alloys, e.g. 20Ni-40Cu-40Mn, 30Ni-30Cu-40Mn and 30Ni-40Cu-30Mn. It was also found that 40Ni-30Cu-30Mn and 50Ni-30Cu-20Mn alloys have lower values of colour change vector than the other alloys given above.

  19. [CrIII(NCMe)6]3+--a labile CrIII source enabling formation of Cr[M(CN)6] (M=V, Cr, Mn, Fe) Prussian blue-type magnetic materials.

    Science.gov (United States)

    Nelson, Kendric J; Daniels, Matthew C; Reiff, William M; Troff, Shayla A; Miller, Joel S

    2007-11-26

    The kinetic inertness of the hexaaquachromium(III) (kH2O=2.4x10(-6) s(-1)) has led to challenges with respect to incorporating CrIII ions into Prussian blue-type materials; however, hexakis(acetonitrile)chromium(III) was shown to be substantially more labile (approximately 10(4) times) and enables a new synthetic route for the synthesis of these materials via nonaqueous solvents. The synthesis, spectroscopic, and physical properties of Cr[M(CN)6] (M=V, Cr, Mn, Fe) Prussian blue analogues synthesized from [CrIII(NCMe)6]3+ and the corresponding [MIII(CN)6]3- are described. All these compounds {(NEt4)0.02CrIII[VIII(CN)6]0.98(BF4)(0.08).0.10MeCN (1), CrIII[CrIII(CN)6].0.16MeCN (2), CrIII[MnIII(CN)6].0.10MeCN (3), and (NEt4)0.04CrIII0.64CrIV0.40[FeII(CN)6]0.40[FeIII(CN)6]0.60(BF4)(0.16).1.02MeCN (4)} are ferrimagnets exhibiting cluster-glass behavior. Strong antiferromagnetic coupling was observed for M=V, Cr, and Mn with Weiss constants (theta) ranging from -132 to -524 K; and in 2, where the strongest coupling is observed (theta=-524 K), the highest Tc (110 K) value was observed. Weak antiferromagnetic coupling was observed for M=Fe (theta=-12 K) leading to the lowest Tc (3 K) value in this series. Weak coupling and the low Tc value observed in 4 were additionally contributed by the presence of both [FeII(CN)6]4- and [FeIII(CN)6]3- as confirmed by 57Fe-Mössbauer spectroscopy.

  20. Biosorption study of Ni2+ and Cr3+ by Sargassum filipendula: kinetics and equilibrium

    Directory of Open Access Journals (Sweden)

    A. A. Seolatto

    2014-03-01

    Full Text Available In this work, the biosorption of Cr3+ and Ni2+ by Sargassum filipendula pre-treated with CaCl2 was studied. Kinetic and equilibrium experiments were carried out for mono- and multi-component solutions in a batch reactor at pH 3.0 and 30 ºC. The results from the kinetic experiments showed that Cr3+ adsorbs slower than Ni2+. This behavior was explained by means of a mechanistic analysis, which showed that Cr3+ uptake presented three adsorption stages, whereas Ni2+ adsorption presents only two. The mono-component equilibrium data, along with binary kinetic data obtained from mono-component experiments, showed that, although the kinetics for Cr3+ removal are slower, the biomass had a stronger affinity for this ion. Almost all Ni2+ is desorbed from the biomass as Cr3+ adsorbs. The binary equilibrium data also presented this behavior. The binary data was also modeled by using modified forms of the Langmuir, Jain and Snoeyink, and Langmuir-Freundlich isotherms. However, the prediction obtained presented low accuracy. An alternative modeling with artificial neural networks was presented and the results showed that this technique could be a promising tool to represent binary equilibrium data. The main contribution of this work was to obtain experimental data for Cr3+/Ni2+ adsorption, which is a system rarely found in the literature and that provides information that could be used in process modeling and simulation.

  1. 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)

  2. K X-ray satellite spectra of Ti, V, Cr and Mn induced by photons

    Indian Academy of Sciences (India)

    M V R Murti; S S Raju; B Seetharami Reddy; V Koteswara Rao; L S Mombaswala; T Seshi Reddy; S Lakshminarayana; K Premachand

    2008-04-01

    K X-ray emission spectra of Ti, V, Cr and Mn generated by photon excitation have been studied with a crystal spectrometer. The measured energy shifts of K satellite relative to the diagram line are compared with values obtained by electron excitation and with different theoretical estimates. The present experimental values of KL1/KL0 relative intensities are compared with values obtained by electron excitation.

  3. Magnetic and magnetoelastic properties of M-substituted cobalt ferrites (M=Mn, Cr, Ga, Ge)

    Energy Technology Data Exchange (ETDEWEB)

    Song, Sang-Hoon [Iowa State Univ., Ames, IA (United States)

    2007-12-15

    Magnetic and magnetoelastic properties of a series of M-substituted cobalt ferrites, CoMxFe2-xO4 (M=Mn, Cr, Ga; x=0.0 to 0.8) and Ge-substituted cobalt ferrites Co1+xGexFe2-2xO4 (x=0.0 to 0.6) have been investigated.

  4. Numerical analysis of rheological and tribological behavior influence on 16MnCr5 forging fibering

    Science.gov (United States)

    Gavrus, A.; Pintilie, D.; Nedelcu, R.

    2016-10-01

    The present research work is focus on the influence of the rheological constitutive equation and friction law formulation on 16MnCr5 forging fibering. Numerical analysis using FE Forge® and Abaqus code show the importance of the rheological softening terms on the metals fibers morphology and position coordinate. Calibration of friction law and sensitivity of softening parameters corresponding to a Hansel-Spittel rheological equation have been studied.

  5. Enhancement of electrochemical performance by simultaneous substitution of Ni and Mn with Fe in Ni-Mn spinel cathodes for Li-ion batteries

    Science.gov (United States)

    Kiziltas-Yavuz, Nilüfer; Yavuz, Murat; Indris, Sylvio; Bramnik, Natalia N.; Knapp, Michael; Dolotko, Oleksandr; Das, Bijoy; Ehrenberg, Helmut; Bhaskar, Aiswarya

    2016-09-01

    LiNi0.5-xFe2xMn1.5-xO4 (x = 0, 0.1, 0.15, 0.2) spinel cathode materials are synthesized using citric acid-assisted sol-gel method with final calcination temperature of 1000 °C. The structure and morphology of the materials are characterized by using synchrotron and neutron powder diffraction as well as scanning electron microscopy. Different from the parent LiNi0.5Mn1.5O4 (LNMO) material, the Fe-doped spinels do not contain a rock-salt type impurity phase. However, they contain additional layered (C2/m) and spinel Fe3O4 (Fd 3 bar m) phases in small amounts. The substitution of Fe into the spinel structure has been confirmed by Mössbauer spectroscopy. The Fe-doped spinels exhibit improved cycling stability (with a C/2 charge-discharge rate) and rate capability compared to the parent LNMO at room temperature in a voltage range 3.5-5.0 V. Among all these samples, the composition LiNi0.4Fe0.2Mn1.4O4 shows the best room temperature cycling stability (capacity retention of 92% after 300 cycles) as well as the highest initial discharge capacity (134 mAh g-1). The delivered capacities at high C-rates (especially at 10C and 20C) with respect to the capacity delivered at C/2 are higher for all Fe-doped samples compared to the parent LNMO. Furthermore, Fe-doping improves the thermal stability of the Ni-Mn spinels in the delithiated state.

  6. Structure and surface composition of NiCr sputtered thin films

    Directory of Open Access Journals (Sweden)

    Petrović S.

    2006-01-01

    Full Text Available Thin films of nichrome were deposited by d.c. sputtering of a target (80%Ni 20%Cr w.t by Ar+ions at a working pressure of 10-1 Pa and at room temperature. The phase composition and grain size were studied by X-ray Diffraction (XRD, while the surface chemical composition was determined by Low Energy Ion Scattering (LEIS. Analysis of phase composition showed that the NiCr thin films were a solid solution of chromium in a nickel matrix with increased nickel lattice parameters. LEIS analysis showed the presence of Ni Cr and O in the first atomic layer. There is a strong suspicion that surface passivation occurred by forming Cr2O3 oxide at the surface.

  7. The kinetics of Cr layer coated on TiNi films for hydrogen absorption

    Indian Academy of Sciences (India)

    M Singh; Vaibhav Kulsherstha; Anil Kumar; N K Acharaya; Y K Vijay

    2007-01-01

    The effect of hydrogen absorption on electrical resistance with temperature for TiNi and TiNi–Cr thin films was investigated. The TiNi thin films of thickness 800 Å were deposited at different angles ( = 0°, 30°, 45°, 60° and 75°) under 10−5 Torr pressure by thermal evaporation on the glass substrate at room temperature. A layer of Cr of thickness 100 Å was coated on the TiNi thin films. The changing rate of hydrogen absorption increases after Cr layer coating because Cr enhances the catalytic properties of hydrogen absorption in thin films. The rate of hydrogen absorption increases with temperature at lower range but at higher range of temperature it was found to decrease and also it was found that the hydrogen absorption increases with angle of deposition.

  8. Interfacial layers in high-temperature-oxidized NiCrAl

    Science.gov (United States)

    Larson, L. A.; Browning, R.; Poppa, H.; Smialek, J.

    1983-01-01

    The utility of Auger electron spectroscopy combined with ball cratering for depth analysis of oxide and diffusion layers produced in a Ni-14Cr-24Al alloy by oxidation in air at 1180 C for 25 hr is demonstrated. During postoxidation cooling, the oxide layers formed by this alloy spalled profusely. The remaining very thin oxide was primarily Cr2O3 with a trace of Ni. The underlying metal substrate exhibited gamma/gamma-prime and beta phases with a metallic interfacial layer which was similar to the bulk gamma/gamma-prime phase but slightly enriched in Cr and Al. These data are compared to electron microprobe results from a nominally identical alloy. The diffusion layer thickness is modelled with a simple mass balance equation and compared to recent results on the diffusion process in NiCrAl alloys.

  9. Disordering and grain boundaries of (Ni,Fe)Cr2O4 spinels from atomistic calculations.

    Science.gov (United States)

    Chartier, Alain; Golovchuk, Bogdan; Gossé, Stéphane; Van Brutzel, Laurent

    2013-10-07

    A novel empirical potential has been developed to evaluate the thermodynamic stability of Ni(1-x)Fe(x)Cr2O4 spinels. The simulations confirm the hypothesis that the NiCr2O4-FeCr2O4 pseudo-binary has normal structure spinel up to 1000 K and stabilizes as a solid solution. However, the disordering energy (normal to inverse spinel) is found higher for FeCr2O4 than for NiCr2O4 spinel. The formation energies of tilt, twist, and random grain boundaries have been calculated in pure NiCr2O4 and FeCr2O4. The same behavior has been found for both spinels. Detail analysis of the grain boundaries structure shows that the cation coordination number is a key parameter for the stability of the grain boundaries. With this criterion, we evidenced that the structural and energetic differences are caused only by nickel and iron cations.

  10. Compositional Zoning and Mn-Cr Systematics in Carbonates from the Y791198 CM2 Carbonaceous Chondrite

    Science.gov (United States)

    Brearley, Adrian J.; Hutcheon, Ian D.; Browning, Lauren

    2001-01-01

    Cathodoluminescence and microprobe analyses show that carbonates in Y791198 exhibit complex zoning. Cr-Mn dating suggests formation of carbonates 10 Ma after CAI formation Additional information is contained in the original extended abstract..

  11. Phase separation in NiCrN coatings induced by N2 addition in the gas phase: A way to generate magnetic thin films by reactive sputtering of a non-magnetic NiCr target

    Science.gov (United States)

    Luciu, I.; Duday, D.; Choquet, P.; Perigo, E. A.; Michels, A.; Wirtz, T.

    2016-12-01

    Magnetic coatings are used for a lot of applications from data storage in hard discs, spintronics and sensors. Meanwhile, magnetron sputtering is a process largely used in industry for the deposition of thin films. Unfortunately, deposition of magnetic coatings by magnetron sputtering is a difficult task due to the screening effect of the magnetic target lowering the magnetic field strength of the magnet positioned below the target, which is used to generate and trap ions in the vicinity of the target surface to be sputtered. In this work we present an efficient method to obtain soft magnetic thin films by reactive sputtering of a non-magnetic target. The aim is to recover the magnetic properties of Ni after dealloying of Ni and Cr due to the selective reactivity of Cr with the reactive nitrogen species generated during the deposition process. The effects of nitrogen content on the dealloying and DC magnetron sputtering (DCMS) deposition processes are studied here. The different chemical compositions, microstructures and magnetic properties of DCMS thin films obtained by sputtering in reactive gas mixtures with different ratios of Ar/N2 from a non-magnetic Ni-20Cr target have been determined. XPS data indicate that the increase of nitrogen content in the films has a strong influence on the NiCr phase decomposition into Ni and CrN, leading to ferromagnetic coatings due to the Ni phase. XRD results show that the obtained Ni-CrN films consist of a metallic fcc cubic Ni phase mixed with fcc cubic CrN. The lattice parameter decreases with the N2 content and reaches the theoretical value of the pure fcc-Ni, when Cr is mostly removed from the Ni-Cr phase. Dealloying of Cr from a Ni80-Cr20 solid solution is achieved in our experimental conditions and the deposition of Ni ferromagnetic coatings embedding CrN from a non-magnetic target is possible with reactive DC magnetron sputtering.

  12. Transient Oxidation of a γ-Ni-28Cr-11Al Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Hu, L; Hovis, D B; Heuer, A H [Case Western

    2012-04-02

    γ-NiCrAl alloys with relatively low Al contents tend to form a layered oxide scale during the early stages of oxidation, rather than an exclusive α-Al2O3 scale, the so-called 'thermally grown oxide' (TGO). A layered oxide scale was established on a model γ-Ni-28Cr-11Al (at.%) alloy after isothermal oxidation for several minutes at 1100 °C. The layered scale consisted of an NiO layer at the oxide/gas interface, an inner Cr2O3 layer, and an α-Al2O3 layer at the oxide/alloy interface. The evolution of such an NiO/Cr2O3/Al2O3 layered structure on this alloy differs from that proposed in earlier work. During heating, a Cr2O3 outer layer and a discontinuous inner layer of Al2O3 initially formed, with metallic Ni particles dispersed between the two layers. A rapid transformation occurred in the scale shortly after the sample reached maximum temperature (1100°C), when two (possibly coupled) phenomena occurred: (i) the inner transition alumina transformed to α-Al2O3, and (ii) Ni particles oxidized to form the outer NiO layer. Subsequently, NiO reacted with Cr2O3 and Al2O3 to form spinel. Continued growth of the oxide scale and development of the TGO was dominated by growth of the inner α-Al2O3 layer.

  13. Effect of Dy addition on mechanical and magnetic properties of Mn-rich Ni-Mn-Ga ferromagnetic shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gao, L., E-mail: lgao@shou.edu.cn [College of Engineering Science and Technology, Shanghai Ocean University, Shanghai 201306 (China); Dong, G.F. [Department of Physics, Dalian University, Dalian 116622 (China); Gao, Z.Y.; Cai, W. [School of Materials Science and Engineering, P.O. Box 405, Harbin Institute of Technology, Harbin, 150001 (China)

    2012-04-15

    Highlights: Black-Right-Pointing-Pointer The Dy addition significantly improves the compressive properties of Ni-Mn-Ga alloy. Black-Right-Pointing-Pointer The mechanism of the improved mechanical properties by adding Dy is discussed. Black-Right-Pointing-Pointer Dy doping results in a change of the fracture type of Ni-Mn-Ga alloy. Black-Right-Pointing-Pointer Curie temperature almost remained unchanged at low Dy content and then decreases. - Abstract: The effects of partial substitution of rare earth Dy for Ga on the mechanical and magnetic properties of Mn-rich Ni{sub 50}Mn{sub 29}Ga{sub 21-x}Dy{sub x} (0 {<=} x {<=} 5) ferromagnetic shape memory alloys were investigated in detail. The results show that an appropriate amount of Dy addition significantly improves the mechanical properties of Ni-Mn-Ga alloy. With an increase in Dy content, the compressive strength enhances rapidly at first and then becomes stable when the Dy content is more than 1 at.%. However, the compressive strain increases dramatically and reaches a maximum value with 1 at.% Dy addition. Further increase in Dy content makes the compressive strain of the alloys decrease gradually. The mechanism of the improved mechanical properties is also discussed. Moreover, Dy doping changes the fracture type from intergranular fracture of Ni-Mn-Ga alloy to transgranular cleavage fracture of Ni-Mn-Ga-Dy alloys. The Curie temperature remains almost unchanged at low Dy content and subsequently decreases.

  14. Effect of Fe substitution on the phase stability and magnetic properties of Mn-rich Ni-Mn-Ga ferromagnetic shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Singh, R.K., E-mail: rksingh1978@yahoo.co.i [Defence Metallurgical Research Laboratory, Hyderabad 500 058 (India); Manivel Raja, M.; Mathur, R.P. [Defence Metallurgical Research Laboratory, Hyderabad 500 058 (India); Shamsuddin, M. [Department of Metallurgical Engineering, Institute of Technology, Banaras Hindu University, Varanasi 221 005 (India)

    2011-03-15

    The influence of Fe additions on the martensitic transformation and magnetic properties of Mn-rich Ni-Mn-Ga alloys was investigated by substituting either 1 at% Fe for each atomic species or by substituting Ni with varying amounts of Fe. The magnetic structure of the alloys was studied using {sup 57}Fe Moessbauer spectroscopy. Moessbauer spectra revealed typical paramagnetic features in Mn-rich Ni-Mn-Ga-Fe alloys owing to the preferential site occupancy of Fe atoms at Ni sites. The evolution of the magnetic properties and phase stability has been correlated with the chemical and atomic ordering in these alloys. - Research highlights: Fe atoms preferentially occupy Ni sites over vacant Ga sites in Mn-rich Ni-Mn-Ga alloys. Such chemical order suppresses the magnetic hyperfine field of Fe atoms due to the interaction with the surrounding Ga and Mn atoms. Accordingly, the Curie temperature and saturation magnetization decrease. This short range ordering also influences the phase stability.

  15. Charge transfer and interfacial magnetism in (LaNiO3)n/(LaMnO3)2 superlattices

    OpenAIRE

    Hoffman, Jason; Tung, I. C.; Nelson-Cheeseman, Brittany; Liu, Ming; Freeland, John; Bhattacharya, Anand

    2013-01-01

    (LaNiO3)n/(LaMnO3)2 superlattices were grown using ozone-assisted molecular beam epitaxy, where LaNiO3 is a paramagnetic metal and LaMnO3 is an antiferromagnetic insulator. The superlattices exhibit excellent crystallinity and interfacial roughness of less than 1 unit cell. X-ray spectroscopy and dichroism measurements indicate that electrons are transferred from the LaMnO3 to the LaNiO3, inducing magnetism in LaNiO3. Magnetotransport measurements reveal a transition from metallic to insulati...

  16. Effect of Cu surface segregation on the exchange coupling field of NiFe/FeMn bilayers

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The NiFe/FeMn bilayers with different buffer layers (Ta or Ta/Cu) were prepared by magnetron sputtering.Results show that the exchange coupling field of NiFe/FeMn films with Ta buffer is higher than that of the films with Ta/ Cu buffer. We analysed the reasons by investigating the crystallographic texture, surface roughness and surface segregation of both films, respectively. We found that the decrease of the exchange coupling fields of NiFe/FeMn films with Ta/Cu buffer layers was mainly caused by the Cu surface segregation on NiFe surface.

  17. A study of the oxide dispersion and recrystallization in NiCrAl prepared from preoxidized powder

    Science.gov (United States)

    Glasgow, T. K.

    1975-01-01

    The SAP technique of dispersion strengthening (formation of an oxide dispersion by preoxidation of metal powders) was applied to atomized powder of the alloy Ni-17Cr-5Al-0.2 Y. SAP-NiCrAl was worked by extrusion and rod rolling at 1205 C and by swaging at 760 C. A variety of annealing treatments were applied after working to determine the recrystallization response. NiCrAlY, similarly prepared from atomized powder, but without a preoxidation treatment, was examined for comparison. The SAP-NiCrAl of this study exhibited oxide particle size and spacing much larger than that usually observed in oxide dispersion strengthened alloys; nonetheless, it was possible to achieve abnormal (secondary) recrystallization in the SAP-NiCrAl as has been reported for other oxide dispersion strengthened alloys. In contrast, unoxidized NiCrAlY exhibited only primary recrystallization.

  18. Annealing effect on the electrical properties and composition of a NiCrAl thin film resistor

    Science.gov (United States)

    Chuang, Nai-Chuan; Lin, Jyi-Tsong; Chen, Huey-Ru

    2015-12-01

    The composition of NiCrAl thin film resistors, under different annealing conditions in a N2 atmosphere, was investigated. The Auger electron spectrum (AES) has been used in studying the composition of NiCrAl thin films. The concentration ratio of Cr to Ni decreases when the annealing temperature increases. The electrical properties of a NiCrAl thin film resistor are affected by the concentrations of Cr and Ni, which lead to a higher temperature coefficient of resistance (TCR) and a lower sheet resistivity. The TCR of a NiCrAl thin film resistor is -5 ppm/°C at a 250 °C annealing temperature.

  19. Removal of Ni (II and Cr (VI ions from aqueous solution using by-product from the production of aluminium

    Directory of Open Access Journals (Sweden)

    A. Štrkalj

    2015-01-01

    Full Text Available In this paper comparative adsorption equilibrium studies of Ni (II and Cr (VI ions on commercial activated carbon (CAC and carbon anode dust (CAD are presented. The equilibrium studies confirmed that Freundlich model best describes the adsorption systems CAC + Cr (VI, CAD + Ni (II and CAD + Cr (VI. The Dubinin-Radushevich isotherm can be used to describe system CAC + Ni (II.The results indicate that the intra-particle diffusion model is applicable for adsorption system CAC + Cr (VI and pseudo-second kinetic model is applicable for adsorption systems CAC + Ni (II, CAD + Cr (VI and CAD + Ni (II. Obtained results indicate that adsorption of Ni (II and Cr (VI ions on CAC and CAD depends on the temperature.

  20. Redox reactions and the influence of natural Mn oxides on Cr oxidation in a contaminated site in northern Italy: evidence from Cr stable-isotopes and EPR spectroscopy

    Directory of Open Access Journals (Sweden)

    Marafatto F. F.

    2013-04-01

    Full Text Available Hexavalent chromium-contaminated groundwaters and sediments in northern Italy have been studied using the Cr stable-isotope systematics and electron spin resonance spectroscopy (ESR, in order to explore redox changes and soil-groundwater interactions. The isotopic data indicate a possible Cr(VI source released into the environment from an industrial plant. EPR spectra on the sediments which constitute the aquifers show a broad asymmetric absorption due to coupled Fe(III and coupled Cr(III ions and a well resolved hyperfine structure due to manganese ions, resulting from Mn(IV and Mn(II. The isotopic and EPR data support the hypothesis of Cr(III being oxidized by Mn oxides which are widespread in the aquifer, possibly related to the oscillation of the phreatic level. The obtained results highlight the usefulness of chromium stable isotopes as environmental tracers and support the observations that naturally occurring Mn oxides in soils may catalize Cr oxidation from the stable Cr(III form to the toxic Cr(VI soluble form, yielding valuable information in planning remediation interventions.

  1. Solid-state synthesis and thermoelectric properties of Cr-doped MnSi{sub 1.73}

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Dong-Kil; You, Sin-Wook; Kim, Il-Ho [Korea National University of Transportation, Chungju (Korea, Republic of)

    2014-11-15

    Cr-doped HMSs (higher manganese silicides), MnSi{sub 1.73} : Cr{sub x} (x = 0, 0.005, 0.01, 0.02, 0.03), were prepared by using a solid-state reaction and hot pressing. X-ray diffraction analysis and Rietveld refinement confirmed the synthesis of MnSi{sub 1.73}. The Cr atoms were confirmed to be soluble in the HMS structure because the lattice constant increased with increasing Cr content (x), and the solid solubility limit of Cr was estimated as x = 0.01. All specimens showed p-type conduction and exhibited degenerate semiconductor characteristics at all temperatures examined (323 - 823 K). The Seebeck coefficient was decreased and the electrical conductivity was increased by Cr doping. The dimensionless thermoelectric figure of merit ZT was obtained as 0.36 at 823 K for MnSi{sub 1.73} : Cr{sub 0.005} and MnSi{sub 1.73} : Cr{sub 0.01} because the power factor was increased and the thermal conductivity was decreased by Cr doping.

  2. Self-template synthesis of hollow ellipsoid Ni-Mn sulfides for supercapacitors, electrocatalytic oxidation of glucose and water treatment.

    Science.gov (United States)

    Cheng, Cheng; Kong, Dechen; Wei, Chengzhen; Du, Weimin; Zhao, Jianbo; Feng, Yeqin; Duan, Qingling

    2017-04-19

    In this work, we have successfully developed a simple self-template route for preparation of hollow ellipsoid Ni-Mn sulfides. This route involves the synthesis of solid Ni-Mn ellipsoids via a chemical precipitation method. Then, using thioacetamide (TAA) as the sulfur source, the solid Ni-Mn ellipsoids can be easily converted to hollow ellipsoid Ni-Mn sulfides in ethanol via sulfidation reaction. The as-synthesized hollow ellipsoid Ni-Mn sulfides possess large specific surface areas and porous structures. Benefiting from these structural and compositional advantages, the electrochemical performance of the hollow ellipsoid Ni-Mn sulfides is studied. As expected, the hollow ellipsoid Ni-Mn sulfides show a high specific capacitance of 1636.8 F g(-1) at 2.0 A g(-1) and good cycling stability (only 4.9% loss after 4000 cycles) as electrode materials for supercapacitors. Furthermore, electrocatalytic oxidation of glucose based on the synthesized hollow ellipsoid Ni-Mn sulfides is also performed. The hollow ellipsoid Ni-Mn sulfides present high sensitivity and selectivity, good stability and a low detection limit (0.02 μM). In addition, the as-synthesized hollow ellipsoid Ni-Mn sulfides exhibit good ability to remove the Congo red dyes from water, which gives them potential application in water treatment. The current work makes a major contribution to the design and preparation of hollow metal sulfide structures, as well as their potential applications in supercapacitors, electrocatalytic oxidation of glucose and water treatment.

  3. Magnetoresistance in ferromagnetic shape memory alloy NiMnFeGa

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Z.H.; Ma, X.Q. [Department of Physics, University of Science and Technology Beijing, Beijing 100083 (China); Zhu, Z.Y.; Luo, H.Z.; Liu, G.D.; Chen, J.L. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Wu, G.H., E-mail: ghwu@aphy.iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Zhang Xiaokai; Xiao, John Q. [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States)

    2011-08-15

    The magnetoresistance (MR){l_brace}=[R(H)-R(0)]/R(0){r_brace} properties in ferromagnetic shape memory alloy of NiMnFeGa ribbons and single crystals, and NiFeGa ribbons have been investigated. It is found that the NiMnFeGa melt-spun ribbon exhibited GMR effect, arising from the spin-dependent scattering from magnetic inhomogeneities consisting of antiferromagnetically coupled Mn atoms in B2 structure. In the absence of these magnetic inhomogeneities, Heusler alloys seem to show a common linear MR behavior at around 0.8T{sub C}, regardless of sample structures. This may be explained by the s-d model. At low temperatures, conventional AMR behaviors due to the spin-orbital coupling are observed. This is most likely due to the diminished MR from s-d model because of much less spin fluctuation, and is not associated with martensite phase. MR anomaly at intermediate field ({rho}{sub perpendicular} >{rho}{sub ||}) is also observed in single crystal samples, which may be related to unique features of Heusler alloys. - Highlights: > NiMnFeGa melt-spun ribbon exhibited GMR effect with a large negative MR up to -13%. > GMR behavior is arising from the spin-dependent scattering from magnetic inhomogeneities. > In the absence of these magnetic inhomogeneities, Heusler alloys seem to show a common linear MR behavior at around 0.8T{sub C}. > Conventional AMR behaviors due to the spin-orbital coupling are observed in NiMnFeGa single crystal and Ni{sub 2}FeGa ribbon samples at low temperatures.

  4. Cation distribution in spinel (Mn,Co,Cr){sub 3}O{sub 4} at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Purwanto, A.; Fajar, A.; Mugirahardjo, H. [National Nuclear Energy Agency (BATAN), Serpong Tengerang (Indonesia). Center for Technology of Nuclear Industrial Materials; Fergus, J.W.; Wang, K. [Auburn Univ., AL (United States). Materials Research and Education Center

    2010-06-15

    As part of a study of the long-term operation of solid-oxide fuel cells, three (Mn,Co,Cr){sub 3}O{sub 4} samples have been synthesized and characterized. X-ray and neutron diffraction patterns from the powder samples at room temperature were measured and the data were co-refined. The neutron data were indispensible in locating Mn, Co and Cr within the crystallographic unit cell with their respective atomic occupancies. Two of these samples have been identified as cubic Mn{sub 0.76}Co{sub 0.58}Cr{sub 1.66}O{sub 4} and Mn{sub 1.28}Co{sub 1.72}O{sub 4}. The third is a twophase sample containing cubic Mn{sub 1.66}Co{sub 1.34}O{sub 4} and tetragonal Mn{sub 2.05}Co{sub 0.91}O{sub 4} in a 59.1 (6):40.9 (6)% mass fraction ratio. Cr, which might be introduced from reaction with chromia during oxidation of interconnect materials, exhibits a preference for the octahedral site rather than the tetrahedral site. Without Cr, Mn dominates the octahedral site. (orig.)

  5. Dielectric function of the ferromagnetic semiconductor CdMnCrTe studied by using spectroscopic ellipsometry

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Younghun; Um, Youngho [University of Ulsan, Ulsan (Korea, Republic of)

    2014-11-15

    We describe the pseudo-dielectric function of Cd{sub 1-x-y}Mn{sub x}Cr{sub y}Te ferromagnetic semiconductor alloys by using spectroscopic ellipsometry in the 1.0 ∼ 6.0 eV spectral range at room temperature. The ellipsometry data include structures that can be attributed to the effects of Cr concentration on the E{sub 0}, E{sub 1}, E{sub 1} + Δ{sub 1}, and E{sub 2} critical points. Critical-point (CP) parameters were obtained by fitting standard critical point (SCP) model line shapes to the numerically-calculated second- energy derivatives of ε(ω) = ε{sub 1}(ω) + iε{sub 2}(ω). The E{sub 0}, E{sub 1}, E{sub 1} + Δ{sub 1}, and E{sub 2} energies decreased with Cr content y; this phenomenon is related to the hybridization of the valence and the conduction bands in CdTe with the 3d states of Mn and Cr.

  6. Synthesis and characterization of La(Cr,Fe,Mn)O{sub 3} nanoparticles obtained by co-precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Fabian, F.A., E-mail: fernandafabianro@gmail.com [Universidade Federal de Sergipe, Campus Prof. Aluísio Campos, Departamento de Física, 49100-000 São Cristóvão, SE (Brazil); Pedra, P.P.; Filho, J.L.S. [Universidade Federal de Sergipe, Campus Prof. Aluísio Campos, Departamento de Física, 49100-000 São Cristóvão, SE (Brazil); Duque, J.G.S.; Meneses, C.T. [Universidade Federal de Sergipe, Campus Prof. Alberto Carvalho, Departamento de Física, 49500-000 Itabaiana, SE (Brazil)

    2015-04-01

    Magnetic and structural properties have been investigated in La(Cr,Fe,Mn)O{sub 3} nanoparticles obtained by co-precipitation method. The X-ray diffraction measurements allied to Rietveld method confirm the formation of LaCrO{sub 3}, LaFeO{sub 3} and LaMnO{sub 3} nanoparticles with crystal structure orthorhombic (Pbnm), orthorhombic (Pnma) and rhombohedral (R-3c), respectively. We also verified an decreasing in the average crystallite size from 73 to 26 nm, depending of the transition metal. The magnetic measurements reveal an antiferromagnetic behavior for the LaCrO{sub 3} sample with T{sub N}~289 K, and a weak ferromagnetic ordering for the LaMnO{sub 3} sample with T{sub c}~200 K. - Highlights: • La(Cr,Fe,Mn)O{sub 3} nanoparticles were synthesized by coprecipitation method. • XRD results confirm the formation single phase in the compounds studied. • Magnetic property in the La(Fe,Cr,Mn)O{sub 3} nanoparticles dependent on the TM. • La(Cr,Fe)O{sub 3} nanoparticles presented behavior antiferromagnetic and LaMnO{sub 3} ferromagnetic.

  7. Fabrication and mechanical properties of AlCoNiCrFe high-entropy alloy particle reinforced Cu matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jian, E-mail: chenjian@xatu.edu.cn [School of Materials Science and Chemical Engineering, Xi' an Technological University, Xi' an, Shaanxi 710021 (China); Niu, Pengyun; Wei, Ting [School of Materials Science and Chemical Engineering, Xi' an Technological University, Xi' an, Shaanxi 710021 (China); Hao, Liang [College of Architecture and Civil Engineering, Xi' an University of Science and Technology, Xi' an 710054 (China); Liu, Yunzi [School of Materials Science and Chemical Engineering, Xi' an Technological University, Xi' an, Shaanxi 710021 (China); Wang, Xianhui, E-mail: xhwang693@xaut.edu.cn [School of Materials Science and Engineering, Xi' an University of Technology, Xi' an, Shaanxi 710048 (China); Peng, Yuli [School of Materials Science and Chemical Engineering, Xi' an Technological University, Xi' an, Shaanxi 710021 (China)

    2015-11-15

    The AlCoNiCrFe high-entropy alloy was prepared by mechanical alloying and the AlCoNiCrFe high-entropy alloy reinforced Cu matrix composites were subsequently fabricated by powder metallurgy. The phase constituents and morphology of the alloying powders were characterized by X-ray diffractometer and scanning electron microscope, the microstructures of the Cu base composites were characterized by scanning electron microscope and transmission electron microscope, and the compression tests were made as well. The results show that the AlCoNiCrFe high-entropy alloy can form after milling for 24 h. During sintering process, no grain growth occurs and no intermetallic phases present in the AlCoNiCrFe high-entropy alloy in the Cu base composite. Compression tests show that the AlCoNiCrFe high-entropy alloy has a better strengthening effect than metallic glasses and the yield strength of the Cu matrix composite reinforced with the AlCoNiCrFe high-entropy alloy is close to the value predicted by the Voigt model based on the equal strain assumption. - Graphical abstract: AlCoNiCrFe HEA has a better strengthening effect than metallic glasses for particulate reinforced metal matrix composites. The yield strength of the Cu base composite reinforced with the AlCoNiCrFe HEA is close to the upper bound calculated by Voigt model. - Highlights: • AlCoNiCrFe high-entropy alloy was prepared by mechanical alloying. • A novel Cu base composite reinforced with AlCoNiCrFe was fabricated. • No grain growth and no intermetallic phase present in AlCoNiCrFe during sintering. • AlCoNiCrFe has a better strengthening effect than metallic glassy in composites.

  8. The fcc-bcc crystallographic orientation relationship in AlxCoCrFeNi high-entropy alloys

    NARCIS (Netherlands)

    Rao, J. C.; Ocelik, V.; Vainchtein, D.; Tang, Z.; Liaw, P. K.; De Hosson, J. Th. M.

    2016-01-01

    This paper concentrates on the crystallographic-orientation relationship between the various phases in the Al-Co-Cr-Fe-Ni high-entropy alloys. Two types of orientation relationships of bcc phases (some with ordered B2 structures) and fcc matrix were observed in Al0.5CoCrFeNi and Al0.7CoCrFeNi alloys

  9. Effects of simultaneous boron and nitrogen implantation on microhardness and fatigue properties of Fe-13cr-15ni alloys

    Science.gov (United States)

    Rao, G. R.; Lee, E. H.; Chin, B. A.; Mansur, L. K.

    1994-12-01

    Eight complex austenitic stainless steel alloys based on the composition Fe-13Cr-15Ni-2Mo-2Mn-0.2Ti-0.8Si-0.06C were implanted simultaneously with 400-keV B+ and 550-keV N+ ions and were investigated for changes in fatigue properties and surface microhardness. The nearsurface hardness of all eight alloys improved, but the fatigue life of each decreased. These findings were contrary to those obtained in an earlier study using four simple Fe-13Cr-15Ni alloys, where the dual implantation improved fatigue life by up to 250 pct. While unimplanted specimens failed by slip-band crack initiation, it was hypothesized that the dual implantation suppressed slip to the extent that fewer slip-band cracks were initiated and these were subjected to accelerated crack propagation. In addition, grain-boundary cracking was promoted, yielding a lower fatigue life. Support for this hypothesis was obtained by a study of single crystals of Fe-15Cr-15Ni, which were also implanted with B+ and N+. The dual implantation caused a lower fatigue life due to concentration of slip along a few slip bands to relieve applied stress. Evidence of grain-boundary cracking was obtained using the four simple alloys, which were subjected to triple ion implantation with B+, N+, and C+. The triple implantation decreased the fatigue life of the alloys and caused accelerated growth of fewer slip bands and grain-boundary cracking due to suppression of surface slip bands. This study thus shows the existence of an optimum level of strengthening when multiple ion implantation is used to improve the fatigue properties of alloys.

  10. Manganese-mediated ferromagnetism in La2Fe1-Mn2Cr1-O6 perovskite oxides

    Indian Academy of Sciences (India)

    R M Tiwari; Mrudul Gadhvi; Abanti Nag; N Y Vasanthacharya; J Gopalakrishnan

    2010-07-01

    We have investigated the structure and magnetic properties of the perovskite oxides of the formula La2Fe1-Mn2Cr1-O6 (0 < < 1.0). For 0 < ≤ 0.5, the members adopt the orthorhombic (Pbnm) structure, where the transition metal atoms are disordered at the 4b sites and the MO6 (M = Fe, Mn, Cr) octahedra become increasingly distorted with increasing . For 0.65 ≤ < 1.0, the members adopt the rhombohedral (R-3c) structure that is similar to LaMnO3+ ( ≥ 0.1) where the MO6 octahedra are undistorted. While the magnetic properties of the latter series are largely similar to the parent LaMnO3+ arising from the double-exchange (DE) between mixed valent MnIII/MnIV, the magnetic properties of the orthorhombic members show a distinct (albeit weak) ferromagnetism (C ∼ 200 K) that seems to arise from a MnIII-mediated superexchange (SE) between FeIII/CrIII in the disordered perovskite structure containing FeIII, MnIII and CrIII.

  11. Structure and composition of magnetocaloric Ni-Mn-In-Co thin films on the nanoscale - a TEM study

    Energy Technology Data Exchange (ETDEWEB)

    Erkartal, Burak; Schuermann, Ulrich; Kienle, Lorenz [Institute for Materials Science, Synthesis and Real Structure, Christian Albrechts University, Kiel (Germany); Duppel, Viola [Nanochemistry Max Planck Institute for Solid State Research, Stuttgart (Germany); Niemann, Robert; Schultz, Ludwig; Faehler, Sebastian [IFW Dresden (Germany)

    2012-08-15

    A complementary set of electron microscopy techniques is applied for the determination of structural and chemical segregation phenomena within a 300 nm thick metamagnetic Ni-Mn-In-Co thin film. The structure is predominantly composed of distinct modulated martensites of the 5M-, 6M-, 7M-, and 8M-type. Additionally these modulated structures exhibit twinning and stacking disordering. The nature of the disordering and the structural misfit at the twin interface were analyzed via high resolution micrographs. Next to an adhesion layer of Cr interdiffusion on the nanoscale was observed producing a penternary chemically and structurally homogeneous precipitate. The structure can be assigned to a twinned non-modulated pseudocubic model. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. In Situ Thermo-magnetic Investigation of the Austenitic Phase During Tempering of a 13Cr6Ni2Mo Supermartensitic Stainless Steel

    Science.gov (United States)

    Bojack, A.; Zhao, L.; Morris, P. F.; Sietsma, J.

    2014-12-01

    The formation of austenite during tempering of a 13Cr6Ni2Mo supermartensitic stainless steel (X2CrNiMoV13-5-2) was investigated using an in situ thermo-magnetic technique to establish the kinetics of the martensite to austenite transformation and the stability of austenite. The austenite fraction was obtained from in situ magnetization measurements. It was found that during heating to the tempering temperature 1 to 2 vol pct of austenite, retained during quenching after the austenitization treatment, decomposed between 623 K and 753 K (350 °C and 480 °C). The activation energy for martensite to austenite transformation was found by JMAK-fitting to be 233 kJ/mol. This value is similar to the activation energy for Ni and Mn diffusion in iron and supports the assumption that partitioning of Ni and Mn to austenite are mainly rate determining for the austenite formation during tempering. This also indicates that the stability of austenite during cooling after tempering depends on these elements. With increasing tempering temperature the thermal stability of austenite is decreasing due to the lower concentrations of austenite-stabilizing elements in the increased fraction of austenite. After cooling from the tempering temperature the retained austenite was further partially decomposed during holding at room temperature. This appears to be related to previous martensite formation during cooling.

  13. Microhardness of Ni-Cr alloys under different casting conditions Microdureza de ligas de Ni-Cr fundidas sob diferentes condições

    Directory of Open Access Journals (Sweden)

    José Roberto de Oliveira Bauer

    2006-03-01

    Full Text Available This study evaluated the microhardness of Ni-Cr alloys used in fixed prosthodontics after casting under different conditions. The casting conditions were: (1-flame/air torch flame made of a gas/oxygen mixture and centrifugal casting machine in a non-controlled casting environment; (2-induction/argon electromagnetic induction in an environment controlled with argon; (3-induction/vacuum electromagnetic induction in a vacuum environment; (4-induction/air electromagnetic induction in a non-controlled casting environment. The 3 alloys used were Ni-Cr-Mo-Ti, Ni-Cr-Mo-Be, and Ni-Cr-Mo-Nb. Four castings with 5 cylindrical, 15 mm-long specimens (diameter: 1.6 mm in each casting ring were prepared. After casting, the specimens were embedded in resin and polished for Vickers microhardness (VH measurements in a Shimadzu HMV-2 (1,000 g for 10 s. A total of 5 indentations were done for each ring, one in each specimen. The data was subjected to two-way ANOVA and Tukey's multiple comparison tests (alpha = 0.05. The VH values of Ni-Cr-Mo-Ti (422 ± 7.8 were statistically higher (p 0.05 and lower than the values obtained in the conditions induction/air and flame/air torch (p 0.05. The microhardness of the alloys is influenced by their composition and casting method. The hardness of the Ni-Cr alloys was higher when they were cast with the induction/air and flame/air torch methods.Este estudo avaliou a microdureza de ligas de Ni-Cr usadas em prótese fixa fundidas sob diferentes condições. As condições de fundição foram: (1-maçarico chama composta por uma mistura de gás/oxigênio e centrífuga sem o controle do ambiente de fundição; (2-indução/argônio indução eletromagnética com o ambiente controlado com argônio; (3-indução/vácuo indução eletromagnética com o ambiente sob vácuo; (4-indução/ar indução eletromagnética sem o controle da atmosfera. Foram utilizadas três ligas: Ni-Cr-Mo-Ti, Ni-Cr-Mo-Be e Ni-Cr-Mo-Nb. Foram realizadas 4

  14. Molybdenum depletion around P-phases Ni-Cr-Mo-W weld metals; Empobrecimento de molibdenio ao redor da fase P em metais de solda de ligas Ni-Cr-Mo-W

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Cleiton Carvalho; Miranda, Helio Cordeiro de; Farias, Jesualdo Pereira [Universidade Federal do Ceara (UFC), CE (Brazil). Departamento de Engenharia Metalurgica e de Materiais; Afonso, Conrado Ramos Moreira; Ramirez, Antonio Jose [Laboratorioo Nacional de Luz Sincroton (LNLS), SP (Brazil)

    2010-07-01

    This work evaluated the local chemical composition in matrix/precipitate interface in a Ni-Cr-Mo-W alloy weld metals deposited on substrate of C-Mn steel. The microstructural characterization was carried out through optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). The results had shown that the presence of secondary phases precipitates in the interdendritic region. Through SEM analysis were observed indications of depletion of Mo around these phases. These precipitates were identified as P-phase by TEM analysis. The Mo depletion indications were confirmed through EDS. The Mo depletion was a result of a reheating due to several welding heat cycles deposited to promote the coating layer. (author)

  15. Electrical and Structural Properties of Ni-60%Cr Thin Film in an Embedded Resistor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae-Yoo; Son, Hwa-Jin; Lim, Seung-Kyu; Lee, Kwang-Keun; Suh, Su-Jeong [Sungkyunkwan University, Suwon (Korea, Republic of)

    2014-02-15

    The NiCr alloy has relatively large resistivity, good resistant to oxidation and low temperature coefficients of resistance (TCR) compared to other resistor metarials. These properties of NiCr thin films are dependent on the processing conditions including the deposition environment and subsequent annealing treatments. To establish optimizing conditions, Ni-60%Cr thin films were deposited by a sputtering method to control the resistivity and TCR. The experiments were carried out under various process pressures to determine the optimum conditions to achieve a high resistivity and low TCR. The thermal stability of Ni-60%Cr thin films at various heat treatment temperatures was also evaluated. The electrical properties of the sputtered Ni-60%Cr thin films were investigated by probe station and their crystal structures were observed by X-Ray Diffraction (XRD). The surface morphology was observed by field emission scanning electron microscopy (FE-SEM) and high resolution transmission electron microscopy (HR-TEM). As a result, a stable resistivity and TCR was respectively observed at 3-15 mTorr and 3-7 mTorr. The heat treatment results revealed an increase in thermal resistance with increasing temperature with a concomitant decrease in the TCR, and a near-zero TCR was obtained at 673 K.

  16. One-pot synthesis of Mn-doped TiO2 grown on graphene and the mechanism for removal of Cr(VI) and Cr(III).

    Science.gov (United States)

    Chen, Zengping; Li, Yaru; Guo, Meng; Xu, Fengyun; Wang, Peng; Du, Yu; Na, Ping

    2016-06-05

    Mn-doped TiO2 grown on reduced graphene oxide(rGO) was synthesized by one-pot hydrothermal method and the photocatalytic removal of Cr by the material was investigated under sunlight. The materials were characterized by a combination of scanning electron microscopy, transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, Brunauer-Emmett-Teller method, UV-vis diffuse reflectance spectra, photoluminescence spectra, electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy. Cr(total) removal efficiency of the material is 97.32% in 30min and 99.02% in 60min under sunlight irradiation, as the initial concentration of Cr(VI) is 20mg/L. The high photocatalytic activity under visible light is considered mainly due to the Mn-doping, and rGO plays an important role in the synergetic effect of adsorption and photocatalysis to sustain the high efficient removal of Cr(VI) and Cr(III). Cr(VI) adsorbed on the surface of rGO is reduced to Cr(III) by photo electrons which are transported through rGO, and the reaction product Cr(III) continues to be adsorbed. The process contributes to the release of abundant photocatalytic sites of Mn-TiO2 and improves photocatalytic efficiency. The excellent adsorption and photocatalytic effect with the explanation of the synergetic mechanism are very useful not only for fundamental research but also for the potential practical applications.

  17. Annealing effect on the electrical properties and microstructure of embedded Ni-Cr thin film resistor

    Energy Technology Data Exchange (ETDEWEB)

    Lai Lifei [Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); NingBo University of Technology, Ningbo 315016 (China); Zeng Wenjin; Fu Xianzhu [Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055 (China); Sun Rong, E-mail: rong.sun@siat.ac.cn [Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055 (China); Du Ruxu [Chinese University of Hong Kong, Shatin, Hong Kong (Hong Kong)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer Annealing effect on the properties of embedded Ni-Cr thin film resistor. Black-Right-Pointing-Pointer A good annealing condition was achieved. Black-Right-Pointing-Pointer The rarely observed hexagonal Ni (0 1 1), (0 0 2) and (1 0 3) were found. Black-Right-Pointing-Pointer The segregation of chromium in thin film can affect the resistivity and TCR. Black-Right-Pointing-Pointer The results obtained would be helpful in achieving a good embedded resistor. - Abstract: Ni-Cr (80/20 at.%) alloy was deposited on the copper foil substrate as embedded thin film resistor (ETFR) materials by DC magnetron sputtering method. Electrical properties and microstructure of Ni-Cr ETFR under different annealing conditions were investigated. Results indicated that the ETFR exhibited the smallest temperature coefficient of resistance (TCR) after annealing at 250 Degree-Sign C for 540 s in N{sub 2}. The structure, stress, composition and surface morphology of ETFR materials were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS) and atomic force microscopy (AFM). The rarely reported hexagonal Ni (0 1 1), (0 0 2) and (1 0 3) in Ni-Cr thin film were found in Ni-Cr (80/20 at.%) ETFR materials. The chemical states on the surface of the ETFR materials after annealing were mainly Cr{sub 2}O{sub 3}. The segregation of chromium during annealing can affect the resistivity and temperature coefficient of resistance (TCR). The different surface morphology of ETFR in annealing will affect the resistivity.

  18. Controllable Hydrothermal Conversion from Ni-Co-Mn Carbonate Nanoparticles to Microspheres

    Directory of Open Access Journals (Sweden)

    Yanqing Tang

    2016-11-01

    Full Text Available Starting from Ni-Co-Mn carbonate nanoparticles prepared by microreaction technology, uniform spherical particles of Ni1/3Co1/3Mn1/3CO3 with a size of 3–4 μm were obtained by a controllable hydrothermal conversion with the addition of (NH42CO3. Based on characterizations on the evolution of morphology and composition with hydrothermal treatment time, we clarified the mechanism of this novel method as a dissolution-recrystallization process, as well as the effects of (NH42CO3 concentration on the morphology and composition of particles. By changing concentrations and the ratio of the starting materials for nano-precipitation preparation, we achieved monotonic regulation on the size of the spherical particles, and the synthesis of Ni0.4Co0.2Mn0.4CO3 and Ni0.5Co0.2Mn0.3CO3, respectively. In addition, the spherical particles with a core-shell structure were preliminarily verified to be available by introducing nano-precipitates with different compositions in the hydrothermal treatment in sequence.

  19. DyNi{sub 2}Mn-magnetisation and Moessbauer spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wang Jianli; Campbell, Stewart James, E-mail: stewart.campbell@adfa.edu.au [University of New South Wales, School of Physical, Environmental and Mathematical Sciences (Australia); Kennedy, Shane Joseph [ANSTO, Bragg Institute (Australia); Dou Shixue [University of Wollongong, Institute for Superconductivity and Electronic Materials (Australia); Wu Guangheng [Chinese Academy of Science, Institute of Physics (China)

    2012-03-15

    The physical properties of DyNi{sub 2}Mn doped with {sup 57}Fe have been investigated by X-ray diffraction, magnetisation (10-300 K) and {sup 57}Fe Moessbauer spectroscopy measurements (5-300 K). DyNi{sub 2}Mn({sup 57}Fe) crystallizes in the MgCu{sub 2}-type cubic structure (Fd{sup }-3m space group). The ordering temperature is found to be T{sub C} = 99(2) K, much higher than those of DyNi{sub 2} ({approx}22 K) and DyMn{sub 2} ({approx}35 K). Analyses of isothermal M-H curves and the related Arrott plots confirm that the magnetic phase transition at T{sub C} is second order. The magnetic entropy change around T{sub C} is 4.0 J/kg K for a magnetic field change of 0 T to 5 T. The spectra above T{sub C} exhibit features consistent with quadrupolar effects while below T{sub C} the spectra exhibit magnetic hyperfine splitting. The Debye temperature for DyNi{sub 2}Mn has been determined as {theta}{sub D} = 200(20) K from a fit to the variable temperature isomer shift IS(T).

  20. Microwave synthesis and electrochemical characterization of Mn/Ni mixed oxide for supercapacitor application

    Energy Technology Data Exchange (ETDEWEB)

    Prasankumar, T.; Jose, Sujin P., E-mail: sujamystica@yahoo.com [School of Physics, Madurai Kamaraj University, Madurai-625021, Tamil Nadu (India); Ilangovan, R.; Venkatesh, K. S. [Department of Nanoscience and Technology, Alagappa University, Karaikudi-630003, Tamil Nadu (India)

    2015-06-24

    Nanostructured Mn/Ni mixed metal oxide was synthesized at ambient temperature by facile microwave irradiation technique. The crystal structure and surface morphology were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. X-ray diffraction analysis confirmed the formation of Mn/Ni mixed oxide in rhombohedral phase and the grain size calculated was found to be 87 nm. The irregular spherical morphology of the prepared sample was exhibited by the SEM images. The characteristic peaks of FTIR at about 630 cm{sup −1} and 749 cm{sup −1} were attributed to the Mn-O and Ni-O stretching vibrations respectively. The presence of both Mn and Ni in the prepared sample was validated by the EDS spectra which in turn confirmed the formation of mixed oxide. Cyclic voltammetry and galvanostatic chargedischarge measurements were employed to investigate the electrochemical performance of the mixed oxide. The cyclic voltammetry curves demonstrated good capacitive performance of the sample in the potential window −0.2V to 0.9V. The charge discharge study revealed the suitability of the prepared mixed oxide for the fabrication of supercapacitor electrode.

  1. Magnetic-Field-Induced Strains of Bonded Ni-Mn-Ga Melt-Spun Ribbons

    Institute of Scientific and Technical Information of China (English)

    QUO Shi-Hai; ZHANG Yang-Huan; LI Jian-Liang; QI Yan; QUAN Bai-Yun; WANG Xin-Lin

    2006-01-01

    Non-stoichiometric Ni50Mn27Ga23 polycrystalline ribbons are prepared by melt-spinning technique. The magnetic-field-induced strain (MFIS) of Ni-Mn-Ga bulk alloy prepared by bonding the melt-spun ribbons is obtained. The experimental results show that Ni50Mn27Ga23 bonded ribbons exhibit a typical thermal-elastic shape memory effect in the thickness direction. The martensitic transformation strain of bonded ribbons is an expansive strain of about 0.3% without the magnetic fieid and a contractive strain of about -0.46% at the magnetic field of 1T. The field can not only enhance the value of the martensitic transformation strain of the bonded ribbons, but can also change the direction of the strain. The bonded ribbons alloy presents negative MFIS and obtains a larger value of the strain though influenced by the adhesive between the ribbons. Therefore, the preparation technique of the Ni-Mn-Ga bulk alloy by bonding melt-spun ribbons is helpful to get rid of the size restriction of the ribbon and to broaden the applications of the ribbons.

  2. Morphological, structural, microhardness and corrosion characterisations of electrodeposited Ni-Mo and Cr coatings

    Energy Technology Data Exchange (ETDEWEB)

    Lima-Neto, Pedro de; Correia, Adriana N.; Vaz, Gustavo L.; Casciano, Paulo N.S., E-mail: pln@ufc.b [Universidade Federal do Ceara (UFC), Fortaleza, CE (Brazil). Dept. de Quimica Analitica e Fisico-Quimica

    2010-07-01

    The corrosion resistance of electrodeposited Cr and Ni-Mo coatings and the influence of heat treatment on the crystallographic structure, morphology and microhardness properties were investigated here. The characterisations were carried out using scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX) techniques. Corrosion tests were performed at room temperature in 10{sup -1} mol dm{sup -3} NaCl solutions and by potentiodynamic linear polarization technique. The Mo content in the layer and current efficiency increased with the molybdate ion concentration in the plating solution, while the surface morphology evolved from rough and homogeneous to cracked surface with the increase of the amount of Mo in the layer. The electrochemical corrosion tests showed that the Cr coatings have better corrosion resistance than the Ni-Mo coatings in chloride medium and that all the studied coatings corrode in chloride medium. Ni-13Mo coating has the nobler corrosion behavior among the studied Ni-Mo coatings. The microhardness of the Ni-13Mo coatings increased as the annealing temperature increased which is related with the precipitation of Ni, Ni{sub 4}Mo and NiMo phases during the heat treatment of this coating. Ni-13Mo coating is a potential substitute for chromium coating in industrial applications when operating at temperatures higher than 100 deg C and good microhardness properties are required. (author)

  3. 20CrNi2Mo渗碳轴承钢的变形抗力%Deformation resistance of carburizing bearing steel 20CrNi2Mo

    Institute of Scientific and Technical Information of China (English)

    李彬周; 张建; 李长生; 李忠之; 乔兵

    2014-01-01

    Using the MMS‐300 thermal mechanical simulator ,the deformation resistance of 20CrNi2Mo steel with strain 0~0.8 and strain rate 0.01s-1 ~10s-1 at 850℃ ~1 150℃ in single pass axial compression process is tested and studied ,and the relation‐ship among deformation temperature ,strain rate ,degree of deformation and deformation resistance has been determined .The re‐sults show that the deformation resistance is affected remarkably by both strain rate and deformation temperature ,the deformation resistance decreases with the increase of temperature ,and it increases with the increase of strain rate .In addition ,the interaction of deformation temperature ,strain rate and degree of deformation affects the deformation resistance together .Through multiple non-linear regression analysis ,the deformation resistance model for the 20CrNi2Mo steel is established ,and this model proved to have good curve fitting characteristics and relatively high precision .%利用M M S‐300热/力模拟实验机,在变形温度850℃~1150℃、应变量0~0.8和应变速率0.01 s-1~10s-1条件下对20CrNi2Mo钢进行高温单道次压缩实验,分析变形温度、变形速率和变形程度对变形抗力的影响。结果表明,变形温度和变形速率对20CrNi2Mo钢变形抗力的影响最为强烈:20CrNi2Mo钢变形抗力随变形温度的升高而减小,随变形速率的提高而增大;且变形温度、变形速率和应变量3个因素之间相互作用,共同影响变形抗力。利用多元非线性回归建立了20CrNi2Mo钢高温变形抗力数学模型,与实测值比较表明,模型拟合程度较好。

  4. Structural and magnetic properties of Cr-substituted NiZnCo ferrite nanopowders

    Energy Technology Data Exchange (ETDEWEB)

    Li, Le-Zhong, E-mail: lezhongli@cuit.edu.cn; Tu, Xiao-Qiang; Wang, Rui; Peng, Long

    2015-05-01

    Cr-substituted NiZnCo ferrite nanopowders, Ni{sub 0.5−x}Zn{sub 0.5}Cr{sub x}Co{sub 0.1}Fe{sub 1.9}O{sub 4} (0≤x≤0.20), were synthesized by sol–gel auto-combustion method. The effect of Cr substitution on the structural and magnetic properties have been investigated. Differential thermal analysis-thermogravimetry (DTA-TG), X-ray diffraction (XRD), Fourier transform infrared spectro-scopy (FT-IR) and vibrating sample magnetometer (VSM) measurements were used to characterize chemical, structural and magnetic properties. The DTA-TG results indicate that there are three steps of combustion process. FT-IR spectra confirm the formation of spinel structure during the self-propagation combustion. XRD results indicate that the lattice parameter and the X-ray density decrease, and the average crystallite size increase with increasing Cr substitution. And Fe{sub 2}O{sub 3} secondary impurity phase formed with excess Cr substitution. The saturation magnetization increases with the increase of Cr substitution when x≤0.05, and decreased when x>0.05. Meanwhile, the coercivity monotonically decreases with the increase of Cr substitution. - Highlights: • Effects of substitution of Ni{sup 2+} by Cr{sup 3+} on structural and magnetic properties of NiZnCo ferrite nanopowders are studied. • There is a Fe{sub 2}O{sub 3} impurity phase formation when x>0.10. • Maximum saturation magnetization is achieved at x=0.05. • Coercivity decreases with the increase of Cr substitution.

  5. Size effects on magnetic actuation in Ni-Mn-Ga shape-memory alloys.

    Science.gov (United States)

    Dunand, David C; Müllner, Peter

    2011-01-11

    The off-stoichiometric Ni(2)MnGa Heusler alloy is a magnetic shape-memory alloy capable of reversible magnetic-field-induced strains (MFIS). These are generated by twin boundaries moving under the influence of an internal stress produced by a magnetic field through the magnetocrystalline anisotropy. While MFIS are very large (up to 10%) for monocrystalline Ni-Mn-Ga, they are near zero (<0.01%) in fine-grained polycrystals due to incompatibilities during twinning of neighboring grains and the resulting internal geometrical constraints. By growing the grains and/or shrinking the sample, the grain size becomes comparable to one or more characteristic sample sizes (film thickness, wire or strut diameter, ribbon width, particle diameter, etc), and the grains become surrounded by free space. This reduces the incompatibilities between neighboring grains and can favor twinning and thus increase the MFIS. This approach was validated recently with very large MFIS (0.2-8%) measured in Ni-Mn-Ga fibers and foams with bamboo grains with dimensions similar to the fiber or strut diameters and in thin plates where grain diameters are comparable to plate thickness. Here, we review processing, micro- and macrostructure, and magneto-mechanical properties of (i) Ni-Mn-Ga powders, fibers, ribbons and films with one or more small dimension, which are amenable to the growth of bamboo grains leading to large MFIS, and (ii) "constructs" from these structural elements (e.g., mats, laminates, textiles, foams and composites). Various strategies are proposed to accentuate this geometric effect which enables large MFIS in polycrystalline Ni-Mn-Ga by matching grain and sample sizes.

  6. COMPOSITION TRIANGLE DIAGRAMS OF Ni-Mn-Ga MAGNETIC SHAPE MEMORY ALLOYS

    Institute of Scientific and Technical Information of China (English)

    Y.F. Wang; J.M. Wang; C.B. Jiang; H.B. Xu

    2006-01-01

    A statistical work has been done to collect the composition ranges of Ni-Mn-Ga alloys exhibiting different structures and martensite start temperature (Ms), large magnetostrain or the co-existence of magnetic and structural transitions. The alloys with five-layered ( 5M), seven-layered(7M) modulated and non-modulated (T) martensitic structures were mapped in the graph. An empirical formula has been presented to reflect the effect of elements nickel (Ni), manganese (Mn)and gallium (Ga), on the martensite start temperature (Ms). The martensitic structure is sensitive to the composition and the martensitic transformation temperature is most drastically affected by the Ni content. The alloys with large magnetostrain or co-existence effect of the magnetic and structural transitions were also listed in a limited area.

  7. Calorimetric Investigation of Thermal Stability of 304H Cu (Fe-17.7Cr-9.3Ni-2.95Cu-0.91Mn-0.58Nb-0.24Si-0.1C-0.12N-Wt Pct) Austenitic Stainless Steel

    Science.gov (United States)

    Tripathy, Haraprasanna; Subramanian, Raju; Hajra, Raj Narayan; Rai, Arun Kumar; Rengachari, Mythili; Saibaba, Saroja; Jayakumar, Tammana

    2016-12-01

    The sequence of phase instabilities that take place in a Fe-17.7Cr-9.3Ni-0.58Nb-2.95Cu-0.12N (wt pct) austenitic stainless steel (304H Cu grade) as a function of temperature has been investigated using dynamic calorimetry. The results obtained from this investigation are supplemented by Thermocalc-based equilibrium and Scheil-Gulliver nonequilibrium solidification simulation. The following phase transformation sequence is found upon slow cooling from liquid: L → L + γ → L + γ + MX → γ + MX + δ → γ +MX + M23C6 → γ + MX + M23C6 + Cu. Under slow cooling, the solidification follows austenite + ferrite (AF) mode, which is in accordance with Thermocalc prediction and Scheil-Gulliver simulation. However, higher cooling rates result in skeletal δ-ferrite formation, due to increased segregation tendency of Nb and Cr to segregate to interdendritic liquid. The solidification mode is found to depend on combined Nb + Cu content. Experimental estimates of enthalpy change associated with melting and secondary phase precipitation are also obtained. In addition a semi-quantitative study on the dissolution kinetics of M23C6 type carbides has also been investigated. The standard solution treatment at 1413 K (1140 °C) is found to be adequate to dissolve both Cu and M23C6 into γ-austenite; but the complete dissolution of MX type carbonitrides occurs near the melting region.

  8. Development of Cr{sub 3}C{sub 2}-25(Ni20Cr) nanostructured coatings; Desenvolvimento de revestimentos nanostruturados de Cr{sub 3}C{sub 2}-25(Ni20Cr)

    Energy Technology Data Exchange (ETDEWEB)

    Cunha, Cecilio Alvares da

    2012-07-01

    This study is divided in two parts. The first part is about the preparation of nanostructured Cr{sub 3}C{sub 2}-25(Ni20Cr) powders by high energy milling followed by characterization of the milled and the as received powder. Analyses of some of the data obtained were done using a theoretical approach. The second part of this study is about the preparation and characterization of coatings prepared with the nanostructured as well as the as received Cr{sub 3}C{sub 2}-25(Ni20Cr) powders. The high temperature erosion-oxidation (E-O) behavior of the coatings prepared with the two types of powders has been compared based on a technological approach. The average crystallite size of the Cr{sub 3}C{sub 2}-25(Ni20Cr) powder decreased rapidly from 145 nm to 50 nm in the initial stages of milling and thereafter decreased slowly to a steady state value of around 10 nm with further increase in milling time. This steady state corresponds to the beginning of a dynamic recovery process. The maximum lattice strain ({epsilon} = 1,17%) was observed in powders milled for 16 hours, and this powders critical crystallite size was 28 nm. In contrast, the lattice parameter attained a minimum for powders milled for 16 hours. Upon reaching the critical crystallite size, the dislocation density attained a steady state regime and all plastic deformation introduced in the material there after was in the form of events occurring at the grain boundaries, due mainly to grain boundary sliding. The deformation energy stored in the crystal lattice of the Cr{sub 3}C{sub 2}-25(Ni20Cr) powders milled for different times was determined from enthalpy variation measurements. These results indicated that the maximum enthalpy variation ({delta}H = 722 mcal) also occurred for powders milled for 16 hours. In a similar manner, the maximum specific heat variation ({delta}C{sub p} = 0,278 cal/gK) occurred for powders milled for 16 hours. The following mechanical properties of Cr{sub 3}C{sub 2}-25(Ni20Cr) coatings

  9. Corrosion resistance of stainless steels and high Ni-Cr alloys to acid fluoride wastes

    Energy Technology Data Exchange (ETDEWEB)

    Smith, H.D.; Mackey, D.B.; Pool, K.H. [Pacific Northwest Lab., Richland, WA (United States); Schwenk, E.B. [Westinghouse Hanford Co., Richland, WA (United States)

    1992-04-01

    TRUEX processing of Hanford Site waste will utilize potentially corrosive acid fluoride processing solutions. Appropriate construction materials for such a processing facility need to be identified. Toward this objective, candidate stainless steels and high Ni-Cr alloys have been corrosion tested in simulated acid fluoride process solutions at 333K. The high Ni-Cr alloys exhibited corrosion rates as low as 0.14 mm/y in a solution with an HF activity of about 1.2 M, much lower than the 19 to 94 mm/y observed for austenitic stainless steels. At a lower HF activity (about 0.008 M), stainless steels display delayed passivation while high Ni-Cr alloys display essentially no reaction.

  10. Microstructural characterization of Ni-22Fe-22Cr-6Al metallic foam by transmission electron microscopy.

    Science.gov (United States)

    Kim, Hyung Giun; Lee, Taeg Woo; Lee, Jae Young; Lee, Eui Sung; Oh, Kwon Oh; Lee, Chang Woo; Lim, Sung Hwan

    2012-01-01

    Ni-22Fe-22Cr-6Al metallic foam, prepared using a thermomechanical treatment and alloying elements, was studied via transmission electron microscopy (TEM) in order to clarify the relationship between the mechanical properties and the nanoscale microstructural characteristics. Due to the unique porous structure of the metallic foam, TEM specimens were prepared using an embedding-process-assisted-ion-milling technique and a focused-ion-beam method. The Cr-, Fe- and Al-clustered regions around the surface of the metallic foam were investigated using elemental maps. The Ni(3)Al (γ') precipitates, which can affect the mechanical properties of the Ni-Fe-Cr (γ) matrix, were characterized in the metallic foam.

  11. Effect of thermal spray processes on microstructures and properties of Ni-20%Cr coatings

    Directory of Open Access Journals (Sweden)

    Pittaya Kuntasudjai

    2006-05-01

    Full Text Available Ni-20%Cr coatings were produced using different thermal spray techniques, which were spray and fuse, flame spray and arc spray. The Ni-20%Cr powder was sprayed onto a mild steel substrate using the spray and fuse and the flame spray systems, while the Ni-20%Cr wire was sprayed using the arc spray system. SEM microstructures of the coatings suggested the spraying conditions used were able to produce dense microstructures. However, the microstructure of the arc sprayed coatings showed fine lamellar characteristics compared to the coatings prepared by the spray and fuse and the flame spray techniques. Chemical elements and oxide were quantified by EDS-SEM technique. Differences in microstructure and coating characteristics such as content of porosity and oxide due to different processing techniques significantly affected the coating properties such as adhesion strength, hardness and wear rate.

  12. 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.

  13. Spectroscopy and atomic physics of highly ionized Cr, Fe, and Ni for tokamak plasmas

    Science.gov (United States)

    Feldman, U.; Doschek, G. A.; Cheng, C.-C.; Bhatia, A. K.

    1980-01-01

    The paper considers the spectroscopy and atomic physics for some highly ionized Cr, Fe, and Ni ions produced in tokamak plasmas. Forbidden and intersystem wavelengths for Cr and Ni ions are extrapolated and interpolated using the known wavelengths for Fe lines identified in solar-flare plasmas. Tables of transition probabilities for the B I, C I, N I, O I, and F I isoelectronic sequences are presented, and collision strengths and transition probabilities for Cr, Fe, and Ni ions of the Be I sequence are given. Similarities of tokamak and solar spectra are discussed, and it is shown how the atomic data presented may be used to determine ion abundances and electron densities in low-density plasmas.

  14. Facile synthesis and characterization of magnetic NiCr ferrospinel embedded in conducting polymer

    Energy Technology Data Exchange (ETDEWEB)

    Ai Lunhong, E-mail: ah_aihong@163.co [Laboratory of Applied Chemistry and Pollution Control Technology, College of Chemistry and Chemical Engineering, China West Normal University, Nanchong 637002 (China); Jiang Jing, E-mail: 0826zjjh@163.co [Laboratory of Applied Chemistry and Pollution Control Technology, College of Chemistry and Chemical Engineering, China West Normal University, Nanchong 637002 (China)

    2009-11-13

    Conducting polymer/NiCr-ferrospinel nanocomposites were synthesized by in situ polymerization of aniline in the presence of NiCr{sub 0.5}Fe{sub 1.5}O{sub 4} nanoparticles via a reverse microemulsion route. The structure, morphology and magnetic properties of products were characterized by powder X-ray diffraction (XRD), infrared spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and magnetic measurements. Structure and morphology analysis indicated that the NiCr{sub 0.5}Fe{sub 1.5}O{sub 4} particles with the crystallite size in the range of 12-18 nm were embedded in the polymer matrix. The magnetization under applied magnetic field for nanocomposites exhibited a clearly hysteretic behavior. The formation mechanism of nanocomposites was proposed as well.

  15. Corrosion and oxidation properties of NiCr coatings sprayed in presence of gas shroud system

    Energy Technology Data Exchange (ETDEWEB)

    Morks, M.F., E-mail: mhanna@swin.edu.au [Industrial Research Institute Swinburne, Swinburne University of Technology, Hawthorn, Melbourne, VIC 3122 (Australia); Berndt, C.C. [Industrial Research Institute Swinburne, Swinburne University of Technology, Hawthorn, Melbourne, VIC 3122 (Australia)

    2010-04-15

    The oxidation of a NiCr bond coat during air plasma spraying was controlled by designing a gas shroud system attached to the plasma torch nozzle. Two nozzles, termed as 'normal' and 'high-speed' nozzles examined the effect of nozzle internal design on the microstructure and phase structure of coatings. X-ray diffraction and SEM morphologies showed that the shroud system reduced the oxidation of NiCr particles during the spray process. Compared with conventional air plasma spraying, the argon gas shroud reduced the coating hardness because the volume fraction of partially melted particles increased. The high-speed nozzle reduced the oxidation and hardness of NiCr coatings due to the increase of partially melted particles in the coatings.

  16. Oxidation protection of NiCoCrAlY coatings on γ-TiAl

    Institute of Scientific and Technical Information of China (English)

    WANG Qi-min; GUO Ming-hu; KE Pei-ling; GONG Jun; SUN Chao; WEN Li-shi

    2005-01-01

    The effect of NiCoCrAlY overlay coatings on the oxidation resistance of γ-TiAl was studied at 900 ℃ in static air. To hinder the interdiffusion of the elements, the Al/Al2O3 layer was added between the coating and the alloy. The results show that the TiAl alloy exhibits poor oxidation resistance. NiCoCrAlY coating can not effectively protect the γ-TiAl substrate from high temperature oxidation because of the serious interdiffusion between the coating and the substrates. With Al/Al2O3 diffusion barrier, the NiCoCrAlY coating exhibits excellent oxidation protection on γ-TiAl alloy.

  17. Effect of MnO2 on properties of NiFe2O4 spinel based inert anode

    Institute of Scientific and Technical Information of China (English)

    XI; Jin-hui; YAO; Guang-chun; LIU; Yi-han; ZHANG; Xiao-ming

    2005-01-01

    In order to improve the properties of NiFe2O4 spinel based inert anode, some additive MnO2 were added to raw materials. NiFe2O4 spinel with MnO2 was made by solid-phase reaction at 1200℃for 6 h. XRD were carried out and the effects of MnO2 on density, conductivity and corrosion resistance were measured. XRD shows when MnO2 was added no new phases exist and MnO2 and NiFe2O4 formed solid solution; Mn4+ replaced parts of Fe3+ and the sample still had the structure of NiFe2O4 spinel. The crystal lattice of NiFe2 O4 spinel became aberrated when MnO2 was added, which can promote sintering, and improve density. Because Mn4+ replaces parts of Fe3+ and produces conduction electron, which can improve conductivity.The corrosion resistance of the samples was enhanced. When MnO2 is 1.0%, the sample's corrosion rate is 1/5 of that of the sample without MnO2. The reason is that Al2 O3 in the melt reacts with Mn4+ in the sample to produce MnAl2O4. MnAl2 O4 forms a dense protecting coat, which can prevent melt from eroding further.Because the key problem with inert anodes is anode corrosion, so we consider the optimal amount of MnO2 is 1.0%.

  18. Effect of Nb on the Microstructure and Mechanical Properties of Cast NiAl-Cr(Mo) Eutectic Alloy

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The microstructure and mechanical behaviors of NiAl-28Cr-5Mo-1Nb eutectic alloy were investigated by using scanning electron microscopy, X-ray diffraction, transmission electron microscopy and compression tests, respectively. The alloy is mainly composed of three phases, which are the gray lamellar Cr(Mo) plate, black NiAl matrix and semicontinuously distributed Cr2Nb-type Laves phase. Through Nb addition, NiAl-Cr(Mo)/Nb alloy exhibits a reasonable balance of high temperature strength and room temperature compression ductility and its mechanical behaviors are superior to the NiAl-28Cr-6Mo eutectic alloy at all temperature. The elevated temperature compression deformation behavior of NiAl-Cr(Mo)/Nb alloy can be properly described by power-law equation.

  19. Coordination polymer template synthesis of hierarchical MnCo2O4.5 and MnNi6O8 nanoparticles for electrochemical capacitors electrode

    Science.gov (United States)

    Wang, Kuaibing; Xu, Jiangyan; Lu, Aimin; Shi, Ying; Lin, Zixia

    2016-08-01

    Two types of ternary metal oxides, MnCo2O4.5 and MnNi6O8 nanoparticles have been separately synthesized through chemical transformation from the corresponding bimetallic coordination polymer particles precursor under high-heating conditions. Series of electrochemical measurements are performed to examine the MnCo2O4.5 and MnNi6O8 electrodes, and the result shows that MnCo2O4.5 structure, especially for Mn/Co-600, has much higher capacitance than that of MnNi6O8 nanoparticles, indicating MnCo2O4.5 electrode is more suitable for applying in neutral electrolyte system. The Mn/Co-600 electrode exhibits a specific capacitance of 158 F g-1 at 5 mV s-1, good rate capability of 53.8% with a 20 times current density increase, good cycle performance (92.9% capacitance retention after 1000 cycles) and high power density (a specific power of 5760 W kg-1 at 4.0 A g-1) with low charge transfer resistance value of 1.8 Ω.

  20. Magnetic phase transitions in PrMn{sub 2-x}Cr{sub x}Ge{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Dincer, I. E-mail: dincer@tu-darmstadt.de; Elerman, Y.; Elmali, A.; Ehrenberg, H.; Fuess, H.; Duman, E.; Acet, M

    2002-07-01

    The structural and magnetic properties of PrMn{sub 2-x}Cr{sub x}Ge{sub 2} (0{<=}x{<=}1.0) were studied by X-ray diffraction and magnetization measurements. The powder samples crystallize in the ThCr{sub 2}Si{sub 2}-type structure, and the lattice constants at room temperature show almost no variation as Cr substitutes Mn. The observed phase transitions are summarized in a proposed magnetic x-T phase diagram and compared with previous Moessbauer spectroscopy and neutron diffraction results for x=0.

  1. Magnetic interactions and electronic structure of $\\rm{Pt_{2}Mn_{1−x}Y_{x}Ga (Y = Cr and Fe)$ system: An $\\it{ab-initio}$ calculation

    Indian Academy of Sciences (India)

    TUFAN ROY; APARNA CHAKRABARTI

    2017-07-01

    First-principles density functional theory-based calculations have been carried out to predict the effects of Mn replacement by Fe and Cr on electronic as well as magnetic properties of $\\rm{Pt_{2}MnGa}$ and $\\rm{Ni_{2}MnGa}$. All the materials studied here are predicted to have conventional Heusler alloy structure in their ground state and they are found to be electronically stable on the basis of their respective formation energy. The replacement of Mn by Fe leads to a ferromagnetic ground state whereas in case of Mn replacement by Cr an intrasublattice antiferromagnetic configuration has been observed to have lower energy. We study the magnetic exchange interaction between the atoms for the materials with ferromagnetic and antiferromagnetic configurations to show the effects of Fe and Cr substitution at Mn site on the magnetic interactions of these systems. Detailed analysis of electronic structure in terms of density of states has been carried out to study the effect of substitution.

  2. Searching for 0+ states in 50Cr: Implications for the superallowed β decay of 50Mn

    Science.gov (United States)

    Leach, K. G.; Garrett, P. E.; Ball, G. C.; Bender, P. C.; Bildstein, V.; Brown, B. A.; Burbadge, C.; Faestermann, T.; Hadinia, B.; Holt, J. D.; Laffoley, A. T.; Jamieson, D. S.; Jigmeddorj, B.; Radich, A. J.; Rand, E. T.; Stroberg, S. R.; Svensson, C. E.; Towner, I. S.; Wirth, H.-F.

    2016-07-01

    A 52Cr(p ,t )50Cr two-neutron pickup reaction was performed using the Q3D magnetic spectrograph at the Maier-Leibnitz-Laboratorium in Garching, Germany. Excited states in 50Cr were observed up to an excitation energy of 5.3 MeV. Despite significantly increased sensitivity and resolution over previous work, no evidence of the previously assigned first excited 0+ state was found. As a result, the 02+ state is reassigned at an excitation energy of Ex=3895.0 (5 ) keV in 50Cr. This reassignment directly impacts direct searches for a nonanalog Fermi β+ decay branch in 50Mn. These results also show better systematic agreement with the theoretical predictions for the 0+ state spectrum in 50Cr using the same formalism as the isospin-symmetry-breaking correction calculations for superallowed nuclei. The experimental data are also compared to ab-initio shell-model predictions using the IM-SRG formalism based on N N and 3 N forces from chiral-EFT in the p f -shell for the first time.

  3. Solvent Extraction of Co, Ni and Mn from NCM Sulfate Leaching Solution of Li(NCMO2 Secondary Battery Scraps

    Directory of Open Access Journals (Sweden)

    Hong Hyun Seon

    2017-06-01

    Full Text Available As a part of the study on recycling Li(NCMO2 lithium-ion battery scraps, solvent extraction experiments were performed using different extraction agents such as PC88A, Cyanex272 and D2EHPA to separate Co, Ni and Mn from the leaching solution. When the ratio of Mn to Ni was about 0.4 in the leaching solution, the separation factor for Co and Mn was found to be less than 10 so that the separation of Co and Ni was insufficient. When solvent extraction was done using the solution with the lower Mn/Ni ratio of 0.05 where Mn was removed by potassium permanganate and chlorine dioxide, more than 99% of Mn could be extracted through five courses of extraction using 30vol% D2EHPA while the extraction rates of Co and Ni were around 17% and 11%, respectively. In the case that Mn was removed from the solution, the extraction rate of Co was higher than 99% whereas less than 7% Ni was extracted using Cyanex272 suggesting that Co and Ni elements were effectively separated.

  4. Formation of Hierarchical Structure Composed of (Co/Ni)Mn-LDH Nanosheets on MWCNT Backbones for Efficient Electrocatalytic Water Oxidation.

    Science.gov (United States)

    Jia, Gan; Hu, Yingfei; Qian, Qinfeng; Yao, Yingfang; Zhang, Shiying; Li, Zhaosheng; Zou, Zhigang

    2016-06-15

    Active, stable, and cost-effective electrocatalysts are attractive alternatives to the noble metal oxides that have been used in water splitting. The direct nucleation and growth of electrochemically active LDH materials on chemically modified MWCNTs exhibit considerable electrocatalytic activity toward oxygen evolution from water oxidation. CoMn-based and NiMn-based hybrids were synthesized using a facile chemical bath deposition method and the as-synthesized materials exhibited three-dimensional hierarchical configurations with tunable Co/Mn and Ni/Mn ratio. Benefiting from enhanced electrical conductivity with MWCNT backbones and LDH lamellar structure, the Co5Mn-LDH/MWCNT and Ni5Mn-LDH/MWCNT could generated a current density of 10 mA cm(-2) at overpotentials of ∼300 and ∼350 mV, respectively, in 1 M KOH. In addition, the materials also exhibited outstanding long-term electrocatalytic stability.

  5. Abrasive Wear Behaviors of Light-weight Austenitic Fe-24Mn-7Al-1C Steel and Mn13Cr2 Steel

    Institute of Scientific and Technical Information of China (English)

    Shi-guang PENG; Ren-bo SONG; Zhi-dong TAN; Chang-hong CAI; Ke GUO; Zhong-hong WANG

    2016-01-01

    The impact abrasive wear behaviors of light-weight austenitic Fe-24Mn-7Al-1C steel with increasing impact wear conditions were studied by comparing with the modified Hadfield (Mn13Cr2)steel.Wear tests were performed with the MLD-10 abrasive wear testing machine.Main parameters such as impact energy,impacting frequency and wear time were evaluated.To explore the abrasive wear behaviors under different impact energies,the parameters in-cluding mass loss,wear resistance and hardness were evaluated in detail.The microstructures of the steels were fur-ther analyzed using optical microscopy (OM),scanning electron microscopy (SEM),transmission electron micros-copy (TEM)and X-ray diffraction (XRD).Results showed that the light-weight austenitic Fe-24Mn-7Al-1C steel had a better wear resistance than Mn13Cr2 steel under the impact energy tested.The wear resistance of light-weight austenitic Fe-24Mn-7Al-1C steel was about 1.09-1.17 times as high as that of Mn13Cr2 steel under low and medi-um impact energy (0.5-2.0 J)conditions,and 1.41 times under high impact energy (4.0 J)condition.In Mn13Cr2 steel,the evolution of dislocation substructure with increasing impact energy showed typical stacking fault,interac-tion of twins and dislocations,as well as mechanical twins.The high work-hardening rate in Fe-24Mn-7Al-1C steel was caused by Taylor lattice and high density of dislocation tangles.

  6. Experimental Study on HSM 40CrNiMoA%高速铣削硬态40CrNiMoA的试验研究

    Institute of Scientific and Technical Information of China (English)

    查文炜

    2006-01-01

    针对硬态40CrNiMoA(47 HRC),在干切和空气油雾环境下,选用黛杰整体硬质合金(K30)涂层(涂层材料为TiNlN)立铣刀在Mikron UCP 710高速加工中心上作了试验研究.并通过试验结果对两种铣削环境下的铣削力作了比较,得出不同铣削参数和铣削环境下高速铣削硬态40CrNiMoA(47 HRC)铣削力的变化规律.

  7. Characteristics of the Energetic Igniters Through Integrating Al/NiO Nanolaminates on Cr Film Bridge.

    Science.gov (United States)

    Yan, YiChao; Shi, Wei; Jiang, HongChuan; Xiong, Jie; Zhang, WanLi; Li, Yanrong

    2015-12-01

    The energetic igniters through integrating Al/NiO nanolaminates on Cr film bridges have been investigated in this study. The microstructures demonstrate well-defined geometry and sharp interfaces. The depth profiles of the X-ray photoelectron spectroscopy of Al/NiO nanolaminates annealed at 550 °C with a bilayer thickness of 250 nm show that the interdiffusion between the Al layer and NiO layer has happened and the annealing temperature cannot provide enough energy to make the diffusion process much more complete. The electrical explosion characteristics employing a capacitor discharge firing set at the optimized charging voltage of 40 V show that the flame duration time is about 700 μs, and an excellent explosion performance is obtained for (Al/NiO)n/Cr igniters with a bilayer thickness of 1000 nm.

  8. Rust Layer Formed on Low Carbon Weathering Steels with Different Mn, Ni Contents in Environment Containing Chloride Ions

    Directory of Open Access Journals (Sweden)

    Gui-qin FU

    2016-11-01

    Full Text Available The rusting evolution of low carbon weathering steels with different Mn, Ni contents under a simulated environment containing chloride ions has been investigated to clarify the correlation between Mn, Ni and the rust formed on steels. The results show that Mn contents have little impact on corrosion kinetics of experimental steels. Content increase of Ni both enhances the anti-corrosion performance of steel substrate and the rust. Increasing Ni content is beneficial to forming compact rust. Semi-quantitative XRD phase analysis shows that the quantity ratio of α/γ*(α-FeOOH/(γ-FeOOH+Fe3O4 decreases as Mn content increases but it increases as Ni content increases. Ni enhances rust layer stability but Mn content exceeding 1.06 wt.% is disadvantageous for rust layer stability. The content increase of Mn does not significantly alter the parameters of the polarization curve. However, as Ni contents increases, Ecorr has shifted to the positive along with decreased icorr values indicating smaller corrosion rate especially as Ni content increases from 0.42 wt.% to 1.50 wt.%.DOI: http://dx.doi.org/10.5755/j01.ms.22.4.12844

  9. EFFECT OF Cr AND Al CONTENT ON THE STACKING FAULT ENERGY IN γ-Fe-Mn ALLOYS

    Institute of Scientific and Technical Information of China (English)

    X.Tian; Y.S.Zhang

    2003-01-01

    The effects of Cr and Al content were investigated on the stacking fault energy in austenitic Fe-31Mn-(0-7.26)Cr-0.96C and Fe-31Mn-(0-8.68)Al-0.85C alloys by the thermodynamic analysis. The results show that the additions of chromium or aluminum increase the non-magnetic component of the stacking fault energy in the γ-FeMn alloys, and the effect of aluminum is larger than that of chromium. The change in the magnetic entropy caused in the antiferromagnetic transition increases the free energy difference between the γ and ε phases in the γ-Fe-Mn alloys. The effects of chromium and aluminum on the magnetic component were discussed on the basis of the influence of both upon the antiferromagnetic transition in the γ-Fe-Mn alloys.

  10. Structural features of Ni-Cr-Si-B materials obtained by different technologies

    OpenAIRE

    Kornienko, E. E.; Nikulina, A. A.; Belousova, N. S.; Lazurenko, D. V.; Ivashutenko, Alexander Sergeevich; Kuzmin, V. I.

    2016-01-01

    This study considers the structural features of Ni-Cr-Si-B (Ni - base; 15.1 % Cr; 2 % Si; 2 % B; 0.4 % C) materials obtained by different methods. The self-fluxing coatings were deposited by plasma spraying on the tubes from low carbon steel. Bulk cylinder specimens of 20 mm diameter and 15 mm height were obtained by spark plasma sintering (SPS). The structure and phase composition of these materials were investigated by optical microscopy (OM), scanning electron microscopy (SEM), transmissio...

  11. The research of axial corrosion fatigue on 10Ni3CrMoV steel

    Science.gov (United States)

    Xie, Xing; Yi, Hong; Xu, Jian; Xie, Kun

    2017-09-01

    Fatigue life had been studied with 10CrNi3MoV steel at different load ratios and in different environmental medias. The microstructure and micro-topography had been observed and analyzed by means of SEM, EDS and TEM. Our findings indicated that, the fatigue life of 10Ni3CrMoV steel in seawater was shorter than in air, the difference in longevity was larger with the decreasing of axis stress. Corrosion pits had a great influence on corrosion fatigue life.

  12. Neutron cross section covariances in the resonance region: 52Cr, 56Fe, 58Ni

    Energy Technology Data Exchange (ETDEWEB)

    Oblozinsky, P.; Cho, Y.-S.; Mattoon, C.M.; Mughabghab, S.F.

    2010-08-03

    We evaluated covariances for neutron capture and elastic scattering cross sections on major structural materials, {sup 52}Cr, {sup 56}Fe and {sup 58}Ni, in the resonance region which extends beyond 800 keV for each of them. Use was made of the recently developed covariance formalism based on kernel approximation along with data in the Atlas of Neutron Resonances. The data of most interest for AFCI applications, elastic scattering cross section uncertainties at energies above about few hundred keV, are on the level of about 12% for {sup 52}Cr, 7-8% for {sup 56}Fe and 5-6% for {sup 58}Ni.

  13. Adherent Al2O3 scales formed on undoped NiCrAl alloys

    Science.gov (United States)

    Smialek, James L.

    1987-01-01

    Changes in the spalling behavior of Al2O3 scales formed on an undoped NiCrAl alloy are described. Two samples of Ni-15Cr-13Al (wt pct), one a control and the other sanded, were subjected to 25 oxidation cycles. It is observed that adherent scales formed on the sanded sample; however, the control sample had speckled, spalled scales. The data reveal that the adherent scales are caused by repeated removal of surface layers after each oxidation cycle. It is determined that interfacial segregation of sulfur influences spallation and sulfur removal increases bonding. The effect of moisture on scale adhesions is investigated.

  14. Using Alloys of Cr-Ni-Co system as metallic bond in powder metallurgy products

    Directory of Open Access Journals (Sweden)

    A. M. Gazaliyev

    2015-10-01

    Full Text Available There is studied the possibility of using alloys of the Cr-Ni-Cо system as a metallic bond in producing ceramet. As the basic material there was used titanium carbide. There were measured such mechanical properties as bending strength, tensile strength, impact viscosity. There is considered a possibility of using ceramet with a metallic bond of the Cr-Ni-Co system as a refractory material. As a heat resistance indicator there was estimated the limit of long durability. It is established that in the studied range of temperatures the material properties are the function of the bond content.

  15. Investigation of Ion Release from Ni-Cr Alloy in Various Acidity Conditions

    OpenAIRE

    Stipetić, J.; Ćatić, A.; A. Čelebić; Baučić, I.; Rinčić, N.; Rajić-Meštrović, S.

    2002-01-01

    Cytotoxicity is in direct correlation to the level of ion release, with non-precious alloys having higher ion release than that of precious alloys. The most often used non-precious dental alloy is Ni-Cr alloy. The aim of the investigation was to determine the type and quantity of ions released from Ni-Cr alloy (Wiron 99(r), Bego, Germany), in acid solutions with different pH values, and to determine the influence of the type of acid solution, its pH value, and duration of interaction on io...

  16. STUDY ON Ni-Cr SYSTEM SOLAR SELECTIVE THIN FILMS PREPARED BY MAGNETRON REACTIVE SPUTTERING PROCESS

    Institute of Scientific and Technical Information of China (English)

    B.W. Wang; H. Shen

    2002-01-01

    Ni-Cr System solar selective thin solid films were prepared by d.c. magnetron reactivesputtering under the atmosphere of O2 and N2. Ni-Cr alloy was chosen as targetmaterial and copper sheets as substrate. Using SEM, Spectrophotometer and Talystepto analyze the relations between the selective characteristic and the structure, theformation and the thickness of the thin films. The aim is to obtain good solar selectivethin films with high absorptance and low emittance, which is applied to flat plate solarheat collectors.

  17. Fabrication of conventional and nanostructured NiCrC coatings via HVAF technique

    Institute of Scientific and Technical Information of China (English)

    TAO Kai; ZHANG Jie; CUI Hua; ZHOU Xiang-lin; ZHANG Ji-shan

    2008-01-01

    The conventional and nanostructured NiCrC (with chemical composition of 80%NiCr-20%CrC) coatings with high quality were fabricated via high velocity air-fuel(HVAF) spraying technique. The microstructures of these coatings were characterized by means of metallographic microscopy, scanning electron microscopy, transmission electron microscopy and X-ray diffractometry. A Vickers microhardness tester was used to determine the mechanical properties of the as-sprayed coatings. The single-line approximation(SLA) method was employed to calculate the grain size and microstrain of as-sprayed nanostructured coating based on the XRD data. The results show that nanostructured NiCrC coating possesses a more uniform and denser microstructure, much higher microhardness and better fracture toughness than its conventional counterpart. Both TEM observation and calculation results based on XRD profile show that as-sprayed nanostructured NiCrC coating has a homogeneous nanocrystalline microstructure with an average grain size of 40 nm.

  18. Some TEM observations of Al2O3 scales formed on NiCrAl alloys

    Science.gov (United States)

    Smialek, J.; Gibala, R.

    1979-01-01

    The microstructural development of Al2O3 scales on NiCrAl alloys has been examined by transmission electron microscopy. Voids have been observed within grains in scales formed on a pure NiCrAl alloy. Both voids and oxide grains grew measurably with oxidation time at 1100 C. The size and amount of porosity decreased towards the oxide-metal growth interface. It was postulated that the voids resulted from an excess number of oxygen vacancies near the oxide-metal interface. Short-circuit diffusion paths were discussed in reference to current growth stress models for oxide scales. Transient oxidations of pure, Y-doped, and Zr-doped NiCrAl was also examined. Oriented alpha-(Al,Cr)2O3 and Ni(Al,Cr)2O4 scales often coexisted in layered structures on all three alloys. Close-packed oxygen planes and directions in the corundum and spinel layers were parallel. The close relationships between oxide layers provided a gradual transition from initial transient scales to steady state Al2O3 growth.

  19. Microstructural design of hardfacing Ni-Cr-B-Si-C alloys

    OpenAIRE

    Hemmati, I.; Huizenga, R. M.; Ocelik, V.; De Hosson, J.Th.M.

    2013-01-01

    This work reports the procedure for selection of alloying elements to refine the microstructure of hardfacing Ni-Cr-B-Si-C alloys by providing in situ formed nucleation agents. It is concluded that the refining element should be able to spontaneously produce precipitates at high temperatures with little solubility in their <