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Sample records for alloy aa5182 effect

  1. Emeraldine base as corrosion protective layer on aluminium alloy AA5182, effect of the surface microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Cecchetto, L. [Laboratoire d' Electrochimie et de Physicochimie des Materiaux et des Interfaces, CNRS-UJF-INP-Grenoble (UMR 5631), ENSEEG, BP 75, 38402 St. Martin d' Heres (France); Ambat, R. [School of Engineering Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Davenport, A.J. [School of Engineering Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Delabouglise, D. [Laboratoire d' Electrochimie et de Physicochimie des Materiaux et des Interfaces, CNRS-UJF-INP-Grenoble (UMR 5631), ENSEEG, BP 75, 38402 St. Martin d' Heres (France)]. E-mail: Didier.Delabouglise@lepmi.inpg.fr; Petit, J.-P. [Laboratoire d' Electrochimie et de Physicochimie des Materiaux et des Interfaces, CNRS-UJF-INP-Grenoble (UMR 5631), ENSEEG, BP 75, 38402 St. Martin d' Heres (France); Neel, O. [Centre de Recherche de Voreppe, Pechiney, Parc economique Centr' Alp, 38340 Voreppe (France)

    2007-02-15

    AA5182 aluminium alloy cold rolled samples were coated by thin films of emeraldine base (EB) obtained from a 5% solution in N-methylpyrrolidinone. Accelerated corrosion tests prove this coating very effective for corrosion protection of aluminium alloys in neutral environment. This study underlines the prominent role of surface cathodic intermetallic particles in pit initiation and coating break down in enhanced corrosion conditions and suggest that, beside the EB barrier properties, the enhanced corrosion resistance observed on the EB coated samples could partly arise from two other mains factors:- a weak redox activity of the polymer which passivate the metal, - a proton involving self-healing process taking place at the polymer-metal interface, which contributes to delay local acidification in first steps of corrosion on EB coated aluminium surfaces.

  2. Emeraldine base as corrosion protective layer on aluminium alloy AA5182, effect of the surface microstructure

    DEFF Research Database (Denmark)

    Cecchetto, L; Ambat, Rajan; Davenport, A.J.

    2007-01-01

    AA5182 aluminium alloy cold rolled samples were coated by thin Wlms of emeraldine base (EB) obtained from a 5% solution in N-methylpyrrolidinone. Accelerated corrosion tests prove this coating very eVective for corrosion protection of aluminium alloys in neutral environment. This study underlines...... the prominent role of surface cathodic intermetallic particles in pit initiation and coating break down in enhanced corrosion conditions and suggest that, beside the EB barrier properties, the enhanced corrosion resistance observed on the EB coated samples could partly arise from two other mains factors......: • a weak redox activity of the polymer which passivate the metal, • a proton involving self-healing process taking place at the polymer–metal interface, which contributes to delay local acidiWcation in Wrst steps of corrosion on EB coated aluminium surfaces....

  3. Effect of strain rate on shear properties and fracture characteristics of DP600 and AA5182-O sheet metal alloys

    Directory of Open Access Journals (Sweden)

    Rahmaan Taamjeed

    2015-01-01

    Full Text Available Shear tests were performed at strain rates ranging from quasi-static (.01 s−1 to 600 s−1 for DP600 steel and AA5182-O sheet metal alloys at room temperature. A miniature sized shear specimen was modified and validated in this work to perform high strain rate shear testing. Digital image correlation (DIC techniques were employed to measure the strains in the experiments, and a criterion to detect the onset of fracture based on the hardening rate of the materials is proposed. At equivalent strains greater than 20%, the DP600 and AA5182 alloys demonstrated a reduced work hardening rate at elevated strain rates. At lower strains, the DP600 shows positive rate sensitivity while the AA5182 was not sensitive to strain rate. For both alloys, the equivalent fracture strain and elongation to failure decreased with strain rate. A conversion of the shear stress to an equivalent stress using the von Mises yield criterion provided excellent agreement with the results from tensile tests at elevated strain rates. Unlike the tensile test, the shear test is not limited by the onset of necking so the equivalent stress can be determined over a larger range of strain.

  4. Recovery and recrystallization in the superplastic deformation of AA5182

    NARCIS (Netherlands)

    Chen, Z.; Kazantzis, A. V.; De Hosson, J. Th. M.

    The coarse-grained Al alloy AA5182 exhibits poor superplasticity with a maximum elongation to failure not exceeding 220% at 450 degrees C and at 10(-2) s(-1). The low values of the strain rate sensitivity indicate that the dislocation velocity is quite high and necking is developed quite soon during

  5. Recovery and recrystallization in the superplastic deformation of AA5182

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Z.; Kazantzis, A.V.; De Hosson, J.T.M. [Department of Applied Physics, Netherlands Institute for Materials Research, University of Groningen (Netherlands)

    2008-04-15

    The coarse-grained Al alloy AA5182 exhibits poor superplasticity with a maximum elongation to failure not exceeding 220 % at 450 C and at 10{sup -2} s{sup -1}. The low values of the strain rate sensitivity indicate that the dislocation velocity is quite high and necking is developed quite soon during extension. The size (often exceeding 1 {mu}m) and the distribution of the precipitates render them incapable of pinning the subgrain boundaries efficiently. As a result recovery and reconstruction by grain refinement occurs only within the necking region where the applied stress is concentrated. A fabrication method which will be able to introduce a large number of submicron sized precipitates will most likely result in sufficient pinning of the subgrain boundaries. This will promote recovery and reconstruction to take place more uniformly in the material rendering it appreciably superplastic. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  6. Mechanical Properties and Wear Behavior of AA5182/WC Nanocomposite Fabricated by Friction Stir Welding at Different Tool Traverse Speeds

    Science.gov (United States)

    Paidar, Moslem; Asgari, Ali; Ojo, Olatunji Oladimeji; Saberi, Abbas

    2018-03-01

    Grain growth inhibition at the heat-affected zone, improved weld strength and superior tribological properties of welds are desirable attributes of modern manufacturing. With the focused on these attributes, tungsten carbide (WC) nanoparticles were employed as reinforcements for the friction stir welding of 5-mm-thick AA5182 aluminum alloy by varying tool traverse speeds. The microstructure, microhardness, ultimate tensile strength, fracture and wear behavior of the resultant WC-reinforced welds were investigated, while unreinforced AA5182 welds were employed as controls for the study. The result shows that the addition of WC nanoparticles causes substantial grain refinement within the weld nugget. A decrease in traverse speed caused additional particle fragmentation, improved hardness value and enhanced weld strength in the reinforced welds. Improved wear rate and friction coefficient of welds were attained at a reduced traverse speed of 100 mm/min in the WC-reinforced welds. This improvement is attributed to the effects of reduced grain size/grain fragmentation and homogeneous dispersion of WC nanoparticles within the WC-reinforced weld nugget.

  7. Effect of temperature and displacement rate on behaviour of as-cast ...

    Indian Academy of Sciences (India)

    Effect of temperature and displacement rate on behaviour of as-cast. AA5182 ... Effects of tem- perature and strain rate on the progression of fracture in semi-solid state have been examined. 2. Experimental. Experiments were performed on AA5182 specimens drawn from the ... cooled jaws and heated via Joule heating.

  8. Deformation mechanism of aluminum-magnesium alloys at elevated temperatures

    NARCIS (Netherlands)

    Kazantzis, A. V.; Chen, Z. G.; De Hosson, J. Th M.

    2013-01-01

    The study concentrates on the formulation of a reliable constitutive equation for plastic forming of Al-Mg-based alloys above 400 A degrees C and at strain rates above 10(-3) s(-1). The deformation mechanisms of two coarse-grained Al-Mg alloys, also known as AA5182, with grain sizes 21 and 37 mu m

  9. Oxide growth on aluminium alloys in the presence of ammonium fluoborate

    International Nuclear Information System (INIS)

    Oliver, J.; Paterson, P.; Flavell, T.; Biddle, G.

    1996-01-01

    The aim of this study as to determine the mechanisms involved in using ammonium fluoborate as a reducing atmosphere when preheating a high magnesium content aluminium alloy. Rutherford Backscattering (RBS) has been the major technique used in the analysis of samples, it revealed significant reduction in both the diffusion of magnesium to the surface and the calculated oxide thickness in the presence of NH 4 BF 4 . At temperatures above 500 deg C in air, SEM images revealed depressions and voids due to incipient melting at various stages, around the grain boundaries. Grain boundaries effectively acted as pipes aiding the diffusion of magnesium to the surface. These results have been verified through compositional analysis with both RBS and auger electron spectroscopy (AES). Results from NH 4 BF 4 atmosphere preheat conditions showed significant improvements. It was verified experimentally that above 500 deg C , AA5182 alloys undergo incipient melting at the grain boundaries with magnesium diffusing through to the surface. 5 refs., 1 fig

  10. Oxide growth on aluminium alloys in the presence of ammonium fluoborate

    Energy Technology Data Exchange (ETDEWEB)

    Oliver, J.; Paterson, P.; Flavell, T. [Royal Melbourne Inst. of Tech., VIC (Australia); Biddle, G. [Alcoa Rolled Products (Australia)

    1996-12-31

    The aim of this study as to determine the mechanisms involved in using ammonium fluoborate as a reducing atmosphere when preheating a high magnesium content aluminium alloy. Rutherford Backscattering (RBS) has been the major technique used in the analysis of samples, it revealed significant reduction in both the diffusion of magnesium to the surface and the calculated oxide thickness in the presence of NH{sub 4}BF{sub 4}. At temperatures above 500 deg C in air, SEM images revealed depressions and voids due to incipient melting at various stages, around the grain boundaries. Grain boundaries effectively acted as pipes aiding the diffusion of magnesium to the surface. These results have been verified through compositional analysis with both RBS and auger electron spectroscopy (AES). Results from NH{sub 4}BF{sub 4} atmosphere preheat conditions showed significant improvements. It was verified experimentally that above 500 deg C , AA5182 alloys undergo incipient melting at the grain boundaries with magnesium diffusing through to the surface. 5 refs., 1 fig.

  11. Shape memory effect alloys

    International Nuclear Information System (INIS)

    Koshimizu, S.

    1992-01-01

    Although the pseudo- or super-elasticity phenomena and the shape memory effect were known since the 1940's, the enormous curiosity and the great interest to their practical applications emerged with the development of the NITINOL alloy (Nickel-Titanium Naval Ordance Laboratory) by the NASA during the 1960's. This fact marked the appearance of a new class of materials, popularly known as shape memory effect alloys (SMEA). The objective of this work is to present a state-of-the-art of the development and applications for the SMEA. (E.O.)

  12. Magnetoimpedance effect in Nanoperm alloys

    International Nuclear Information System (INIS)

    Hernando, B.; Alvarez, P.; Santos, J.D.; Gorria, P.; Sanchez, M.L.; Olivera, J.; Perez, M.J.; Prida, V.M.

    2006-01-01

    The influence of isothermal annealing (1 h at 600 deg. C in Ar atmosphere) on the soft magnetic properties and magnetoimpedance (MI) effect has been studied in ribbons of the following Nanoperm alloys: Fe 91 Zr 7 B 2 , Fe 88 Zr 8 B 4 , Fe 87 Zr 6 B 6 Cu 1 and Fe 8 Zr 1 B 1 . A maximum MI ratio of about 27% was measured for the nanocrystalline alloy Fe 87 Zr 6 B 6 Cu 1 at a driving frequency of 0.2 MHz. The thermal annealing led to magnetic softening for this alloy, while a hardening is observed for the Fe 8 Zr 1 B 1 alloy

  13. Hydrogen effects in aluminum alloys

    International Nuclear Information System (INIS)

    Louthan, M.R. Jr.; Caskey, G.R. Jr.; Dexter, A.H.

    1976-01-01

    The permeability of six commercial aluminum alloys to deuterium and tritium was determined by several techniques. Surface films inhibited permeation under most conditions; however, contact with lithium deuteride during the tests minimized the surface effects. Under these conditions phi/sub D 2 / = 1.9 x 10 -2 exp (--22,400/RT) cc (NTP)atm/sup -- 1 / 2 / s -1 cm -1 . The six alloys were also tested before, during, and after exposure to high pressure hydrogen, and no hydrogen-induced effects on the tensile properties were observed

  14. Irradiation effects in magnesium and aluminium alloys

    International Nuclear Information System (INIS)

    Sturcken, E.F.

    1979-01-01

    Effects of neutron irradiation on microstructure, mechanical properties and swelling of several magnesium and aluminium alloys were studied. The neutron fluences of 2-3 X 10 22 n/cm 2 , >0.2 MeV produced displacement doses of 20 to 45 displacements per atom (dpa). Ductility of the magnesium alloys was severely reduced by irradiation induced recrystallization and precipitation of various forms. Precipitation of transmuted silicon occurred in the aluminium alloys. However, the effect on ductility was much less than for the magnesium alloys. The magnesium and aluminium alloys had excellent resistance to swelling: The best magnesium alloy was Mg/3.0 wt% Al/0.19 wt% Ca; its density decreased by only 0.13%. The best aluminium alloy was 6063, with a density decrease of 0.22%. (Auth.)

  15. Effects of segregation of primary alloying elements on the creep response in magnesium alloys

    DEFF Research Database (Denmark)

    Huang, Y.D.; Dieringa, H.; Hort, N.

    2008-01-01

    The segregation of primary alloying elements deteriorates the high temperature creep resistance of magnesium alloys. Annealing at high temperatures alleviating their segregations can improve the creep resistance. Present investigation on the effect of segregation of primary alloying elements on t...

  16. Local environment effects in disordered alloys

    International Nuclear Information System (INIS)

    Cable, J.W.

    1978-01-01

    The magnetic moment of an atom in a ferromagnetic disordered alloy depends on the local environment of that atom. This is particularly true for Ni and Pd based alloys for which neutron diffuse scattering measurements of the range and magnitude of the moment disturbances indicate that both magnetic and chemical environment are important in determining the moment distribution. In this paper we review recent neutron studies of local environment effects in Ni based alloys. These are discussed in terms of a phenomenological model that allows a separation of the total moment disturbance at a Ni site into its chemical and magnetic components

  17. Thermal aging effects in refractory metal alloys

    Science.gov (United States)

    Stephens, Joseph R.

    1987-01-01

    The alloys of niobium and tantalum are attractive from a strength and compatibility viewpoint for high operating temperatures required in materials for fuel cladding, liquid metal transfer, and heat pipe applications in space power systems that will supply from 100 kWe to multi-megawatts for advanced space systems. To meet the system requirements, operating temperatures ranging from 1100 to 1600 K have been proposed. Expected lives of these space power systems are from 7 to 10 yr. A program is conducted at NASA Lewis to determine the effects of long-term, high-temperature exposure on the microstructural stability of several commercial tantalum and niobium alloys. Variables studied in the investigation include alloy composition, pre-age annealing temperature, aging time, temperature, and environment (lithium or vacuum), welding, and hydrogen doping. Alloys are investigated by means of cryogenic bend tests and tensile tests. Results show that the combination of tungsten and hafnium or zirconium found in commercial alloys such as T-111 and Cb-752 can lead to aging embrittlement and increased susceptibility to hydrogen embrittlement of ternary and more complex alloys. Modification of alloy composition helps to eliminate the embrittlement problem.

  18. Studies on neutron irradiation effects of iron alloys and nickel-base heat resistant alloys

    International Nuclear Information System (INIS)

    Watanabe, Katsutoshi

    1987-09-01

    The present paper describes the results of neutron irradiation effects on iron alloys and nickel-base heat resistant alloys. As for the iron alloys, irradiation hardening and embrittlement were investigated using internal friction measurement, electron microscopy and tensile testings. The role of alloying elements was also investigated to understand the irradiation behavior of iron alloys. The essential factors affecting irradiation hardening and embrittlement were thus clarified. On the other hand, postirradiation tensile and creep properties were measured of Hastelloy X alloy. Irradiation behavior at elevated temperatures is discussed. (author)

  19. Anisotropic work-hardening behaviour ofstructural steels and aluminium alloys at large strains

    Science.gov (United States)

    Bouvier, S.; Teodosiu, C.; Haddadi, H.; Tabacaru, V.

    2003-03-01

    Sheet metal forming processes may often involve intense forming sequences, leading to large strains and severe strain-path changes. Optimizing such technologies requires a good understanding and description of the anisotropic plastic behaviour of the deformed material, in connection with the evolution of its texture and microstructure. In this paper, we present the predictions provided by a model involving isotropic and kinematioc hardening and by a physically-based microstructural model, which introduces additional internal variables taking into accounthe directional strength of dislocation structures and their polarity. These models have been identified by using sequences of uniaxial traction and simple shear experiments, carried out on various steels (DC06, DP600, HSLA340) and aluminium alloys (AA5182-O, AA6016-T4). The microstructural model proved able predict the complex hardening behaviour displayed, especially by the ferritic steels, namely the transient work-hardening stagnation during reversed deformation in Bauschinger tests, the temporary work-softening during orthogonal tests, and the grain fragmentation at large monotonie strains.

  20. Effect of ternary alloying elements on microstructure and superelastictity of Ti-Nb alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, D.C.; Mao, Y.F.; Li, Y.L.; Li, J.J.; Yuan, M. [Key Laboratory of Low Di-mensional Materials and Application Technology of Ministry of Education, Xiangtan University, Xiangtan, Hunan 411105 (China); Faculty of Material and Optical-Electronic Physics, Xiangtan University, Xiangtan, Hunan 411105 (China); Lin, J.G., E-mail: lin_j_g@xtu.edu.cn [Key Laboratory of Low Di-mensional Materials and Application Technology of Ministry of Education, Xiangtan University, Xiangtan, Hunan 411105 (China); Faculty of Material and Optical-Electronic Physics, Xiangtan University, Xiangtan, Hunan 411105 (China)

    2013-01-01

    The effect of ternary alloying elements (X=Ta, Fe, Zr, Mo, Sn and Si) on the microstructure, the mechanical properties and the superelasticity of Ti--22Nb-X alloys were investigated. The 1% addition of a ternary alloying element (X=Ta, Fe, Zr, Mo, Sn and Si) has a slight influence on the microstructure of the Ti-22Nb alloy. All the alloys after solution-treatment at 1073 K for 1.8 ks contain {beta} and {alpha} Double-Prime phases. The elements of Sn, Si, Fe and Ta with a high number of valence electrons or a small atomic size have a strong solid-solution strengthening effect to the {beta} phases in the alloys and the alloys with high Md{sup Macron} and low Bo{sup Macron} exhibit low elastic moduli. All the alloying elements improve the superelasticity of Ti-22Nb-X alloys. The elements, Fe, Mo, Sn and Si, which are with a high number of valence electrons and a small atomic size, strongly increase {sigma}{sub SIM} of the Ti-22Nb alloy.

  1. Size Effect on Magnesium Alloy Castings

    Science.gov (United States)

    Li, Zhenming; Wang, Qigui; Luo, Alan A.; Zhang, Peng; Peng, Liming

    2016-06-01

    The effect of grain size on tensile and fatigue properties has been investigated in cast Mg alloys of Mg-2.98Nd-0.19Zn (1530 μm) and Mg-2.99Nd-0.2Zn-0.51Zr (41 μm). The difference between RB and push-pull fatigue testing was also evaluated in both alloys. The NZ30K05-T6 alloy shows much better tensile strengths (increased by 246 pct in YS and 159 pct in UTS) and fatigue strength (improved by ~80 pct) in comparison with NZ30-T6 alloy. RB fatigue testing results in higher fatigue strength compared with push-pull fatigue testing, mainly due to the stress/strain gradient in the RB specimen cross section. The material with coarse grains could be hardened more in the cyclic loading condition than in the monotonic loading condition, corresponding to the lower σ f and the higher σ f/ σ b or σ f/ σ 0.2 ratio compared to the materials with fine grains. The fatigue crack initiation sites and failure mechanism are mainly determined by the applied stress/strain amplitude. In LCF, fatigue failure mainly originates from the PSBs within the surface or subsurface grains of the samples. In HCF, cyclic deformation and damage irreversibly caused by environment-assisted cyclic slip is the crucial factor to influence the fatigue crack. The Coffin-Manson law and Basquin equation, and the developed MSF models and fatigue strength models can be used to predict fatigue lives and fatigue strengths of cast magnesium alloys.

  2. Effect of alloy elements on the anti-corrosion properties of low alloy ...

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Effect of alloy elements on corrosion of low alloy steel was studied under simulated offshore condi- tions. The results showed that the elements Cu, P, Mo, W, V had evident effect on corrosion resistance in the atmosphere zone; Cu, P, V, Mo in the splash zone and Cr, Al, Mo in the submerged zone. Keywords.

  3. Effects of chemical composition on the corrosion of dental alloys.

    Science.gov (United States)

    Galo, Rodrigo; Ribeiro, Ricardo Faria; Rodrigues, Renata Cristina Silveira; Rocha, Luís Augusto; de Mattos, Maria da Glória Chiarello

    2012-01-01

    The aim of this study was to determine the effect of the oral environment on the corrosion of dental alloys with different compositions, using electrochemical methods. The corrosion rates were obtained from the current-potential curves and electrochemical impedance spectroscopy (EIS). The effect of artificial saliva on the corrosion of dental alloys was dependent on alloy composition. Dissolution of the ions occurred in all tested dental alloys and the results were strongly dependent on the general alloy composition. Regarding the alloys containing nickel, the Ni-Cr and Ni-Cr-Ti alloys released 0.62 mg/L of Ni on average, while the Co-Cr dental alloy released ions between 0.01 and 0.03 mg/L of Co and Cr, respectively.The open-circuit potential stabilized at a higher level with lower deviation (standard deviation: Ni-Cr-6Ti = 32 mV/SCE and Co-Cr = 54 mV/SCE). The potenciodynamic curves of the dental alloys showed that the Ni-based dental alloy with >70 wt% of Ni had a similar curve and the Co-Cr dental alloy showed a low current density and hence a high resistance to corrosion compared with the Ni-based dental alloys. Some changes in microstructure were observed and this fact influenced the corrosion behavior for the alloys. The lower corrosion resistance also led to greater release of nickel ions to the medium. The quantity of Co ions released from the Co-Cr-Mo alloy was relatively small in the solutions. In addition, the quantity of Cr ions released into the artificial saliva from the Co-Cr alloy was lower than Cr release from the Ni-based dental alloys.

  4. Neutron irradiation effect on thermomechanical properties of shape memory alloys

    International Nuclear Information System (INIS)

    Abramov, V.Ya.; Ionajtis, R.R.; Kotov, V.V.; Loguntsev, E.N.; Ushakov, V.P.

    1996-01-01

    Alloys of Ti-Ni, Ti-Ni-Pd, Fe-Mn-Si, Mn-Cu-Cr, Mn-Cu, Cu-Al-Mn, Cu-Al-Ni systems are investigated after irradiation in IVV-2M reactor at various temperatures with neutron fluence of 10 19 - 10 20 cm -2 . The degradation of shape memory effect in titanium nickelide base alloys is revealed after irradiation. Mn-Cu and Mn-Cu-Cr alloys show the best results. Trends in shape memory alloy behaviour depending on irradiation temperature are found. A consideration is given to the possibility of using these alloys for components of power reactor control and protection systems [ru

  5. Effects of high energy ball milling on synthesis and characteristics of Ti-Mg alloys

    CSIR Research Space (South Africa)

    Chikwanda, HK

    2008-01-01

    Full Text Available The synthesis of Ti-Mg alloys using mechanical alloying method has been investigated. Effects of the mechanical alloying parameters on the resultant microstructural features have been studied. This work presents the effects of milling speed...

  6. Effect of reversible hydrogen alloying and plastic deformation on microstructure development in titanium alloys

    International Nuclear Information System (INIS)

    Murzinova, M.A.

    2011-01-01

    Hydrogen leads to degradation in fracture-related mechanical properties of titanium alloys and is usually considered as a very dangerous element. Numerous studies of hydrogen interaction with titanium alloys showed that hydrogen may be considered not only as an impurity but also as temporary alloying element. This statement is based on the following. Hydrogen stabilizes high-temperature β-phase, leads to decrease in temperature of β→α transformation and extends (α + β )-phase field. The BCC β-phase exhibits lower strength and higher ductility in comparison with HCP α -phase. As a result, hydrogen improves hot workability of hard-to-deform titanium alloys. Hydrogen changes chemical composition of the phases, kinetics of phase transformations, and at low temperatures additional phase transformation (β→α + TiH 2 ) takes place, which is accompanied with noticeable change in volumes of phases. As a result, fine lamellar microstructure may be formed in hydrogenated titanium alloys after heat treatment. It was shown that controlled hydrogen alloying improves weldability and machinability of titanium alloys. After processing hydrogenated titanium preforms are subjected to vacuum annealing, and the hydrogen content decreases up to safe level. Hydrogen removal is accompanied with hydrides dissolution and β→α transformation that makes possible to control structure formation at this final step of treatment. Thus, reversible hydrogen alloying of titanium alloys allows to obtain novel microstructure with enhanced properties. The aim of the work was to study the effect of hydrogen on structure formation, namely: i) influence of hydrogen content on transformation of lamellar microstructure to globular one during deformation in (α+β)-phase field; ii) effect of dissolved hydrogen on dynamic recrystallization in single α- and β- phase regions; iii) influence of vacuum annealing temperature on microstructure development. The work was focused on the optimization of

  7. Effects of alloying element and metallurgical structure on semiconducting characteristics of oxide film of zirconium alloy

    International Nuclear Information System (INIS)

    Inagaki, Masahisa; Kanno, Masayosi; Maki, Hideo.

    1991-01-01

    Semiconducting characteristics of oxide films formed on pure Zr, Zr-Sn binary alloy and Zr-Sn-X (X: Fe, Ni or Cr) ternary alloys were evaluated by photo-electrochemical method, in order to make clear the effects of alloying elements on oxidation mechanism of Zr alloy in BWR environment. Oxide films of the alloys showed the characteristics of n-type semiconductor. Maximum photocurrent (I max) was generated by an illumination of monochromatic light with the energy of 5 ∼ 6 eV, i.e. the band gap energy of the Zr alloy oxide was 5 ∼ 6 eV. This value is lower by 2 ∼ 3 eV than the theoretical band gap energy (8 eV) of stoichiometric ZrO 2 . These facts suggest that the generation of I max was resulted from an excitation of electrons trapped with anion vacancies (oxygen vacancies) of non-stoichiometric ZrO 2-x . Therefore, the value of I max is considered to be proportional to the density of anion vacancy. High corrosion resistant alloys showed lower value of I max. The changes of I max, due to change of chemical composition of alloys and due to the change of metallurgical structure, was able to be explained by the valence theory of oxide semiconductor, i.e. the decrease of 1 max was considered to be resulted from the decrease of anion vacancies due to the substitution of divalent cations (Ni 2+ ) and trivalent cations (Fe 3+ , Cr 3+ ) at Zr 4+ cation sites. From these results, it was concluded that oxidation rate of Zr alloy depended on the density of oxygen vacancies in oxide film. (author)

  8. Structure effect on wear resistance of alloys

    International Nuclear Information System (INIS)

    Stepina, A.I.; Sidorova, L.I.; Tolstenko, E.V.

    1982-01-01

    The dependence of wear resistance on hardness of steels with different microstructure is studied under conditions of gas-abrasion wear of surface layers. It is found out that at the same hardness the wear resistance of α-alloys is higher than that of γ-alloys in spite of considerable surface hardening of austenitic alloys. Fracture of surface in the process of abrasive wear occurs after achievement of definite values of microhardness and the width of a diffraction line for each structural class of alloys [ru

  9. Effect of Al alloying on the martensitic temperature in Ti-Ta shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ferrari, Alberto; Rogal, Jutta; Drautz, Ralf [Interdisciplinary Centre for Advanced Materials Simulation, Ruhr-Universitaet Bochum (Germany)

    2017-07-01

    Ti-Ta-based alloys are promising candidates as high temperature shape memory alloys (HTSMAs) for actuators and superelastic applications. The shape memory mechanism involves a martensitic transformation between the low-temperature α'' phase (orthorhombic) and the high-temperature β phase (body-centered cubic). In order to prevent the degradation of the shape memory effect, Ti-Ta needs to be alloyed with further elements. However, this often reduces the martensitic temperature M{sub s}, which is usually strongly composition dependent. The aim of this work is to analyze how the addition of a third element to Ti-Ta alloys affects M{sub s} by means of electronic structure calculations. In particular, it will be investigated how alloying Al to Ti-Ta alters the relative stability of the α'' and β phases. This understanding will help to identify new alloy compositions featuring both a stable shape memory effect and elevated transformation temperatures.

  10. Effect of Silicon in U-10Mo Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kautz, Elizabeth J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Devaraj, Arun [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kovarik, Libor [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lavender, Curt A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Joshi, Vineet V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2017-08-31

    This document details a method for evaluating the effect of silicon impurity content on U-10Mo alloys. Silicon concentration in U-10Mo alloys has been shown to impact the following: volume fraction of precipitate phases, effective density of the final alloy, and 235-U enrichment in the gamma-UMo matrix. This report presents a model for calculating these quantities as a function of Silicon concentration, which along with fuel foil characterization data, will serve as a reference for quality control of the U-10Mo final alloy Si content. Additionally, detailed characterization using scanning electron microscope imaging, transmission electron microscope diffraction, and atom probe tomography showed that Silicon impurities present in U-10Mo alloys form a Si-rich precipitate phase.

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

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  12. Effectiveness of Ti-micro alloying in relation to cooling rate on corrosion of AZ91 Mg alloy

    International Nuclear Information System (INIS)

    Candan, S.; Celik, M.; Candan, E.

    2016-01-01

    In this study, micro Ti-alloyed AZ91 Mg alloys (AZ91 + 0.5wt.%Ti) have been investigated in order to clarify effectiveness of micro alloying and/or cooling rate on their corrosion properties. Molten alloys were solidified under various cooling rates by using four stage step mold. The microstructural investigations were carried out by using scanning electron microscopy (SEM). Corrosion behaviors of the alloys were evaluated by means of immersion and electrochemical polarization tests in 3.5% NaCl solution. Results showed that the Mg 17 Al 12 (β) intermetallic phase in the microstructure of AZ91 Mg alloy formed as a net-like structure. The Ti addition has reduced the distribution and continuity of β intermetallic phase and its morphology has emerged as fully divorced eutectic. Compared to AZ91 alloy, the effect of the cooling rate in Ti-added alloy on the grain size was less pronounced. When AZ91 and its Ti-added alloys were compared under the same cooling conditions, the Ti addition showed notably high corrosion resistance. Electrochemical test results showed that while I corr values of AZ91 decrease with the increase in the cooling rate, the effect of the cooling rate on I corr values was much lower in the Ti-added alloy. The corrosion resistance of AZ91 Mg alloy was sensitive towards the cooling rates while Ti-added alloy was not affected much from the cooling conditions. - Highlights: • Effect the cooling rate on grain size was less pronounced in the Ti-added alloy. • The morphology of the β phase transformed into fully divorced eutectics. • Ti addition exhibited significantly higher corrosion resistance. • Ti micro alloying is more effective than faster cooling of the alloy on corrosion.

  13. Effect of neutron irradiation on vanadium alloys

    International Nuclear Information System (INIS)

    Braski, D.N.

    1986-01-01

    Neutron-irradiated vanadium alloys were evaluated for their susceptibility to irradiation hardening, helium embrittlement, swelling, and residual radioactivity, and the results were compared with those for the austenitic and ferritic stainless steels. The VANSTAR-7 and V-15Cr-5Ti alloys showed the greatest hardening between 400 and 600 0 C while V-3Ti-1Si and V-20Ti had lower values that were comparable to those of ferritic steels. The V-15Cr-5Ti and VANSTAR-7 alloys were susceptible to helium embrittlement caused by the combination of weakened grain boundaries and irradiation-hardened grain matrices. Specimen fractures were entirely intergranular in the most severe instances of embrittlement. The V-3Ti-1Si and V-20Ti alloys were more resistant to helium embrittlement. Except for VANSTAR-7 irradiated to 40 dpa at 520 0 C, all of the vanadium alloys exhibited low swelling that was similar to the ferritic steels. Swelling was greater in specimens that were preimplanted with helium using the tritium trick. The vanadium alloys clearly exhibit lower residual radioactivity after irradiation than the ferrous alloys

  14. Effect of neutron irradiation on vanadium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Braski, D.N.

    1986-01-01

    Neutron-irradiated vanadium alloys were evaluated for their susceptibility to irradiation hardening, helium embrittlement, swelling, and residual radioactivity, and the results were compared with those for the austenitic and ferritic stainless steels. The VANSTAR-7 and V-15Cr-5Ti alloys showed the greatest hardening between 400 and 600/sup 0/C while V-3Ti-1Si and V-20Ti had lower values that were comparable to those of ferritic steels. The V-15Cr-5Ti and VANSTAR-7 alloys were susceptible to helium embrittlement caused by the combination of weakened grain boundaries and irradiation-hardened grain matrices. Specimen fractures were entirely intergranular in the most severe instances of embrittlement. The V-3Ti-1Si and V-20Ti alloys were more resistant to helium embrittlement. Except for VANSTAR-7 irradiated to 40 dpa at 520/sup 0/C, all of the vanadium alloys exhibited low swelling that was similar to the ferritic steels. Swelling was greater in specimens that were preimplanted with helium using the tritium trick. The vanadium alloys clearly exhibit lower residual radioactivity after irradiation than the ferrous alloys.

  15. Effective and Environmentally Friendly Nickel Coating on the Magnesium Alloy

    Directory of Open Access Journals (Sweden)

    Ivana Škugor Rončević

    2016-12-01

    Full Text Available The low density and good mechanical properties make magnesium and its alloys attractive construction materials in the electronics, automotive, and aerospace industry, together with application in medicine due to their biocompatibility. Magnesium AZ91D alloy is an alloy with a high content of aluminum, whose mechanical properties overshadow the low corrosion resistance caused by the composition of the alloy and the existence of two phases: α magnesium matrix and β magnesium aluminum intermetallic compound. To improve the corrosion resistance, it is necessary to find an effective protection method for the alloy surface. Knowing and predicting electrochemical processes is an essential for the design and optimization of protective coatings on magnesium and its alloys. In this work, the formations of nickel protective coatings on the magnesium AZ91D alloy surface by electrodeposition and chemical deposition, are presented. For this purpose, environmentally friendly electrolytes were used. The corrosion resistance of the protected alloy was determined in chloride medium using appropriate electrochemical techniques. Characterization of the surface was performed with highly sophisticated surface-analytical methods.

  16. Effect of hydrogen on aluminium and aluminium alloys: A review

    DEFF Research Database (Denmark)

    Ambat, Rajan; Dwarakadasa, E.S.

    1996-01-01

    Susceptibility of aluminium and its alloys towards hydrogen embrittlement has been well established. Still a lot of confusion exists on the question of transport of hydrogen and its possible role in stress corrosion cracking. This paper reviews some of the fundamental properties of hydrogen...... in aluminium and its alloys and its effect on mechanical properties. The importance of hydrogen embrittlement over anodic dissolution to explain the stress corrosion cracking mechanism of these alloys is also examined in considerable detail. The various experimental findings concerning the link between...... hydrogen embrittlement and stress corrosion cracking are also discussed....

  17. Synergistic alloying effect on microstructural evolution and mechanical properties of Cu precipitation-strengthened ferritic alloys

    International Nuclear Information System (INIS)

    Wen, Y.R.; Li, Y.P.; Hirata, A.; Zhang, Y.; Fujita, T.; Furuhara, T.; Liu, C.T.; Chiba, A.; Chen, M.W.

    2013-01-01

    We report the influence of alloying elements (Ni, Al and Mn) on the microstructural evolution of Cu-rich nanoprecipitates and the mechanical properties of Fe–Cu-based ferritic alloys. It was found that individual additions of Ni and Al do not give rise to an obvious strengthening effect, compared with the binary Fe–Cu parent alloy, although Ni segregates at the precipitate/matrix interface and Al partitions into Cu-rich precipitates. In contrast, the co-addition of Ni and Al results in the formation of core–shell nanoprecipitates with a Cu-rich core and a B2 Ni–Al shell, leading to a dramatic improvement in strength. The coarsening rate of the core–shell precipitates is about two orders of magnitude lower than that of monolithic Cu-rich precipitates in the binary and ternary Fe–Cu alloys. Reinforcement of the B2 Ni–Al shells by Mn partitioning further improves the strength of the precipitation-strengthened alloys by forming ultrastable and high number density core–shell nanoprecipitates

  18. Shape memory effects in a uranium + 14 at. % niobium alloy

    International Nuclear Information System (INIS)

    Vandermeer, R.A.; Ogle, J.C.; Snyder, W.B. Jr.

    1978-01-01

    There is a class of alloys that, on cooling from elevated temperatures, experience a martensitic phase change. Some of these, when stressed in the martensitic state to an apparently plastic strain, recover their predeformed shape simply by heating. This striking shape recovery is known as the ''shape memory effect'' (SME). Up to a certain limiting strain, epsilon/sub L/, 100% shape recovery may be accomplished. This memory phenomenon seems to be attributable to the thermoelastic nature of and deformational modes associated with the phase transformation in the alloy. Thus, shape recovery results when a stress-biased martensite undergoes a heat-activated reversion back to the parent phase from which it originated. There are uranium alloys that demonstrate SME-behavior. Uranium-rich, uranium--niobium alloys were the first to be documented; New experimental observations of SME in a polycrystalline uranium--niobium alloy are presented. This alloy can exhibit a two-way memory under cetain circumstances. Additional indirect evidence is presented suggesting that the characteristics of the accompanying phase transformation in this alloy meet the criteria or ''selection rules'' deemed essential for SME

  19. Effect of diluted alloying elements on mechanical properties of iron

    International Nuclear Information System (INIS)

    Hassan, A.A.S.

    1996-01-01

    Iron and its alloys have extensive applications. The effect of solute additions on mechanical properties of iron was investigated to check the efficiency of solute atoms on strength and surface e life. Additions in the range of 0.1 wt.% and 0.3 wt.% of alloying elements of Cu,Ni and Si were used. Samples of grains size ranged from 6-40 m which have been prepared by annealing followed by furnace cooling. The recrystallization temperature increases with alloying addition (475 degree C for Fe-0.3 wt. % C alloy compared to 375 degree C for pure iron). Si and Cu additions inhibit grain growth of iron whereas Ni addition enhances it.Addition of Si or Ni to iron induced softening below room temperature whereas addition of Cu caused hardening. The work hardening parameters decreased due to alloying additions. The strength coefficient K was 290 M N/m2 for Fe-03 wt % Ni compared to 340 M N/m2 for pure iron. The work hardening exponent n is 0.12 for fe-0.3 wt. Cu alloy compared to 0.17 for pure iron. All the investigated alloys fulfilled the Hall-Petch relation at liquid Nitrogen and at room temperature. Alloying addition which caused softening addition which caused hardening increased the Half-Petch parameters. Ni addition favors ductility of iron whereas Cu addition reduces it. Alloying additions generally lead to brittle fracture and decrease the crack resistance of iron. 9 tabs., 55 figs., 103 refs

  20. Effect of Solute Segregation on Fracture Behavior of Mg Alloy

    Science.gov (United States)

    Kawa, Tomoaki; Yamaguchi, Masatake; Ikeo, Naoko; Mukai, Toshiji

    Improving mechanical properties of magnesium and understanding fracture behavior under impact loading are necessary to apply magnesium alloys to structural components of automobiles. We have investigated the fracture behavior of binary magnesium alloys by three-point bending experiment and conducted a first principle calculation to estimate the effect of solute segregation on fracture energy. In this paper, we have focused on experimental result of impact three-point bending test for Mg-0.3at.%Y alloy and the results of the test were compared with that of AZ31 commercially available alloy [1]. As a result, the crack propagation speed of Mg-0.3at.%Y was found to be slower than that of AZ31 alloys. Moreover, the absorbed energy of Mg-0.3at.%Y was more than twice as high as that of AZ31 alloys. These results suggested that yttrium solute in magnesium improved the fracture toughness of magnesium under impact loading. Then, fracture surface was observed by SEM to consider the effect of microstructure on crack propagation speed.

  1. Effect of iron and silicon in aluminium and its alloys

    International Nuclear Information System (INIS)

    Kovacs, I.

    1990-01-01

    The iron and silicon are the main impurities in aluminium, they are always present in alloys made from commercially pure base material. The solid solubility of iron in aluminium is very low, therefore its largest amount forms intermetallic compounds the kind of which depends strongly on the other impurities of alloying elements. Although the solid solubility of silicon is much larger than that of the iron, it is the constituent of both the primary and the secondary particles, the structure of which depends in general on the iron-silicon concentration ratio. These Fe and Si containing particles can cause various and basic changes in the macroscopic properties of the alloy. Since commercially pure aluminium has extensive consumer and industrial use, it is very important to know, not only from scientific but also from practical point of view, the effect of iron and silicon on the physical and mechanical properties of aluminium and its alloys. The aim of the ''International Workshop on the Effect of Iron and Silicon in Aluminium and its Alloys'' was to clarify the present knowledge on this subject. The thirty papers presented at the Workshop and collected in this Proceedings cover many important fields of the subject. I hope that they will contribute to both the deeper understanding of the related phenomena and the improvement of technologies for producing better aluminium alloys

  2. In vivo effects of dental casting alloys

    Czech Academy of Sciences Publication Activity Database

    Venclíková, Z.; Benada, Oldřich; Bártová, J.; Joska, L.; Mrklas, L.; Procházková, J.; Stejskal, V.D.M.; Podzimek, Š.

    2006-01-01

    Roč. 27, č. 1 (2006), s. 25-32 ISSN 0172-780X R&D Projects: GA MZd NK7437 Institutional research plan: CEZ:AV0Z50200510 Keywords : dental alloys * metals * gingiva Subject RIV: EE - Microbiology, Virology Impact factor: 0.924, year: 2006

  3. The effect of selected alloying element additions on properties of Mg-based alloy as bioimplants: A literature review

    Science.gov (United States)

    Zhang, Li-Nan; Hou, Zeng-Tao; Ye, Xin; Xu, Zhao-Bin; Bai, Xue-Ling; Shang, Peng

    2013-09-01

    This review investigates the current application limitations of Mg and Mg alloys. The key issues hindering the application of biodegradable Mg alloys as implants are their fast degradation rate and biological consideration. We have discussed the effect of some selected alloying element additions on the properties of the Mg-based alloy, especially the nutrient elements in human (Zn, Mn, Ca, Sr). Different grain sizes, phase constituents and distributions consequently influence the mechanical properties of the Mg alloys. Solution strengthening and precipitation strengthening are enhanced by the addition of alloying elements, generally improving the mechanical properties. Besides, the hot working process can also improve the mechanical properties. Combination of different processing steps is suggested to be adopted in the fabrication of Mg-based alloys. Corrosion properties of these Mg-based alloys have been measured in vitro and in vivo. The degradation mechanism is also discussed in terms of corrosion types, rates, byproducts and response of the surrounding tissues. Moreover, the clinical response and requirements of degradable implants are presented, especially for the nutrient elements (Ca, Mn, Zn, Sr). This review provides information related to different Mg alloying elements and presents the promising candidates for an ideal implant.

  4. Effects and mechanisms of grain refinement in aluminium alloys

    Indian Academy of Sciences (India)

    Unknown

    grain refine the solidified product. The mechanism of grain refinement is of considerable ... The present paper attempts to review the literature on the nucleant effects and solute effects on grain refinement and ... cast alloys. Firstly, reduced mechanical properties have been noted in plate products for structural application.

  5. Point defects and diffusion in alloys: correlation effects

    International Nuclear Information System (INIS)

    Barbe, Vincent

    2006-01-01

    Kinetic models in alloys aim at predicting the transport properties of a system starting from the microscopic jump frequencies of defects. Such properties are of prior importance in systems which stay out of equilibrium for a long time, as for example irradiated alloys in nuclear reactors. We hereby propose several developments of the recent self-consistent mean field (SCMF) kinetic theory, which deals particularly with the correlation effects due to the coupling of atomic and defect fluxes. They are taken into account through a non-equilibrium distribution function of the system, which is derived from the time evolution of small clusters (of two or more atoms or defects). We therefore introduce a set of 'dynamic' interactions called effective Hamiltonian. The SCMF theory is extended to treat high jump frequency ratios for the vacancy mechanism, as well as the transport through interstitial defects. We use in both cases an atomic model which accounts for the thermodynamic properties of the alloy, as e.g. the short-range order. Those models are eventually applied to predict the diffusion properties in two model alloys of nuclear interest: the concentrated Fe-Ni-Cr solid solution and the dilute Fe(P) alloy. We present adapted atomic models and compare our predictions to experimental data. (author)

  6. The Effect of Cold Work on Properties of Alloy 617

    Energy Technology Data Exchange (ETDEWEB)

    Wright, Richard [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2014-08-01

    Alloy 617 is approved for non-nuclear construction in the ASME Boiler and Pressure Vessel Code Section I and Section VIII, but is not currently qualified for nuclear use in ASME Code Section III. A draft Code Case was submitted in 1992 to qualify the alloy for nuclear service but efforts were stopped before the approval process was completed.1 Renewed interest in high temperature nuclear reactors has resulted in a new effort to qualify Alloy 617 for use in nuclear pressure vessels. The mechanical and physical properties of Alloy 617 were extensively characterized for the VHTR programs in the 1980’s and incorporated into the 1992 draft Code Case. Recently, the properties of modern heats of the alloy that incorporate an additional processing step, electro-slag re-melting, have been characterized both to confirm that the properties of contemporary material are consistent with those in the historical record and to increase the available database. A number of potential issues that were identified as requiring further consideration prior to the withdrawal of the 1992 Code Case are also being re-examined in the current R&D program. Code Cases are again being developed to allow use of Alloy 617 for nuclear design within the rules of the ASME Boiler and Pressure Vessel Code. In general the Code defines two temperature ranges for nuclear design with austenitic and nickel based alloys. Below 427°C (800°F) time dependent behavior is not considered, while above this temperature creep and creep-fatigue are considered to be the dominant life-limiting deformation modes. There is a corresponding differentiation in the treatment of the potential for effects associated with cold work. Below 427°C the principal issue is the relationship between the level of cold work and the propensity for stress corrosion cracking and above that temperature the primary concern is the impact of cold work on creep-rupture behavior.

  7. Enhancement of antibiotic effect via gold:silver-alloy nanoparticles

    International Nuclear Information System (INIS)

    Moreira dos Santos, Margarida; Queiroz, Margarida João; Baptista, Pedro V.

    2012-01-01

    A strategy for the development of novel antimicrobials is to combine the stability and pleiotropic effects of inorganic compounds with the specificity and efficiency of organic compounds, such as antibiotics. Here we report on the use of gold:silver-alloy (Au:Ag-alloy) nanoparticles, obtained via a single-step citrate co-reduction method, combined to conventional antibiotics to enhance their antimicrobial effect on bacteria. Addition of the alloy nanoparticles considerably decreased the dose of antibiotic necessary to show antimicrobial effect, both for bacterial cells growing in rich medium in suspension and for bacterial cells resting in a physiological buffer on a humid cellulose surface. The observed effect was more pronounced than the sum of the individual effects of the nanoparticles and antibiotic. We demonstrate the enhancement effect of Au:Ag-alloy nanoparticles with a size distribution of 32.5 ± 7.5 nm mean diameter on the antimicrobial effect of (i) kanamycin on Escherichia coli (Gram-negative bacterium), and (ii) a β-lactam antibiotic on both a sensitive and resistant strain of Staphylococcus aureus (Gram-positive bacterium). Together, these results may pave the way for the combined use of nanoparticle–antibiotic conjugates towards decreasing antibiotic resistance currently observed for certain bacteria and conventional antibiotics.

  8. Enhancement of antibiotic effect via gold:silver-alloy nanoparticles

    Science.gov (United States)

    dos Santos, Margarida Moreira; Queiroz, Margarida João; Baptista, Pedro V.

    2012-05-01

    A strategy for the development of novel antimicrobials is to combine the stability and pleiotropic effects of inorganic compounds with the specificity and efficiency of organic compounds, such as antibiotics. Here we report on the use of gold:silver-alloy (Au:Ag-alloy) nanoparticles, obtained via a single-step citrate co-reduction method, combined to conventional antibiotics to enhance their antimicrobial effect on bacteria. Addition of the alloy nanoparticles considerably decreased the dose of antibiotic necessary to show antimicrobial effect, both for bacterial cells growing in rich medium in suspension and for bacterial cells resting in a physiological buffer on a humid cellulose surface. The observed effect was more pronounced than the sum of the individual effects of the nanoparticles and antibiotic. We demonstrate the enhancement effect of Au:Ag-alloy nanoparticles with a size distribution of 32.5 ± 7.5 nm mean diameter on the antimicrobial effect of (i) kanamycin on Escherichia coli (Gram-negative bacterium), and (ii) a β-lactam antibiotic on both a sensitive and resistant strain of Staphylococcus aureus (Gram-positive bacterium). Together, these results may pave the way for the combined use of nanoparticle-antibiotic conjugates towards decreasing antibiotic resistance currently observed for certain bacteria and conventional antibiotics.

  9. Enhancement of antibiotic effect via gold:silver-alloy nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Moreira dos Santos, Margarida, E-mail: margarida.santos@fct.unl.pt; Queiroz, Margarida Joao; Baptista, Pedro V. [Universidade Nova de Lisboa, CIGMH, Departamento Ciencias da Vida, Faculdade de Ciencias e Tecnologia (Portugal)

    2012-05-15

    A strategy for the development of novel antimicrobials is to combine the stability and pleiotropic effects of inorganic compounds with the specificity and efficiency of organic compounds, such as antibiotics. Here we report on the use of gold:silver-alloy (Au:Ag-alloy) nanoparticles, obtained via a single-step citrate co-reduction method, combined to conventional antibiotics to enhance their antimicrobial effect on bacteria. Addition of the alloy nanoparticles considerably decreased the dose of antibiotic necessary to show antimicrobial effect, both for bacterial cells growing in rich medium in suspension and for bacterial cells resting in a physiological buffer on a humid cellulose surface. The observed effect was more pronounced than the sum of the individual effects of the nanoparticles and antibiotic. We demonstrate the enhancement effect of Au:Ag-alloy nanoparticles with a size distribution of 32.5 {+-} 7.5 nm mean diameter on the antimicrobial effect of (i) kanamycin on Escherichia coli (Gram-negative bacterium), and (ii) a {beta}-lactam antibiotic on both a sensitive and resistant strain of Staphylococcus aureus (Gram-positive bacterium). Together, these results may pave the way for the combined use of nanoparticle-antibiotic conjugates towards decreasing antibiotic resistance currently observed for certain bacteria and conventional antibiotics.

  10. Effect of Bi on the corrosion resistance of zirconium alloys

    International Nuclear Information System (INIS)

    Yao Meiyi; Zhou Bangxin; Li Qiang; Zhang Weipeng; Zhu Li; Zou Linghong; Zhang Jinlong; Peng Jianchao

    2014-01-01

    In order to investigate systematically the effect of Bi addition on the corrosion resistance of zirconium alloys, different zirconium-based alloys, including Zr-4 (Zr-l.5Sn-0.2Fe-0.1Cr), S5 (Zr-0.8Sn-0.35Nb-0.4Fe-0.1Cr), T5 (Zr-0.7Sn-l.0Nb-0.3Fe-0.1Cr) and Zr-1Nb, were adopted to prepare the zirconium alloys containing Bi of 0∼0.5% in mass fraction. These alloys were denoted as Zr-4 + xBi, S5 + xBi, T5 + xBi and Zr-1Nb + xBi, respectively. The corrosion behavior of these specimens was investigated by autoclave testing in lithiated water with 0.01 M LiOH or deionized water at 360 ℃/18.6 MPa and in superheated steam at 400 ℃/10.3 MPa. The microstructure of the alloys was examined by TEM and the second phase particles (SPPs) were analyzed by EDS. Microstructure observation shows that the addition of Bi promotes the precipitation of Sn as second phase particles (SPPs) because Sn is in solid solution in α-Zr matrix in Zr-4, S5 and T5 alloys. The concentration of Bi dissolved in α-Zr matrix increase with the increase of Nb in the alloys, and the excess Bi precipitates as Bi-containing SPPs. The corrosion results show that the effect of Bi addition on the corrosion behavior of different zirconium-based alloys is very complicated, depending on their compositions and corrosion conditions. In the case of higher Bi concentration in α-Zr, the zirconium alloys exhibit better corrosion resistance. However, in the case of precipitation of Bi-containing SPPs, the corrosion resistance gets worse. This indicates that the solid solution of Bi in α-Zr matrix can improve the corrosion resistance, while the precipitation of the Bi-containing SPPs is harmful to the corrosion resistance. (authors)

  11. Effect of alloying on elastic properties of ZrN based transition metal nitride alloys

    KAUST Repository

    Kanoun, Mohammed

    2014-09-01

    We report the effect of composition and metal sublattice substitutional element on the structural, elastic and electronic properties of ternary transition metal nitrides Zr1-xMxN with M=Al, Ti, Hf, V, Nb, W and Mo. The analysis of the elastic constants, bulk modulus, shear modulus, Young\\'s modulus, and Poisson\\'s ratio provides insights regarding the mechanical behavior of Zr1-xMxN. We predict that ternary alloys are more ductile compared to their parent binary compounds. The revealed trend in the mechanical behavior might help for experimentalists on the ability of tuning the mechanical properties during the alloying process by varying the concentration of the transition metal. © 2014 Elsevier B.V.

  12. The Effect of Alloying Elements on Thermal Conductivity and Casting Characteristic in High Pressure Die Casting of Aluminum Alloy

    Science.gov (United States)

    Kim, Cheol-Woo; Cho, Jae-Ik; Choi, Se-Weon; Kim, Young-Chan; Kang, Chang-Seog

    Recently, demand of aluminum alloys for use in high thermal conductivity application is increases but the most aluminum die casting alloys exhibit very lower thermal properties because of their high concentrations of alloying elements. However, those alloying elements are essential to obtain sufficient fluidity and mechanical strength. Therefore, the purpose of this study is to analyze the effect of alloying elements in die casting alloys, Si, Cu, Mg, Fe and Mn, in thermal conductivity, die casting characteristics and mechanical properties and find out the appropriate amount of each alloying element for development of heat sink component. The results showed that Mn had the most deleterious effect in thermal conductivity and Si and Fe contents were important to improve strength and limit casting defects, such as hot tearing and die soldering. The alloy with 0.2 1.0wt%Cu, 0.3 0.6wt%Fe and 1.0 2.0wt%Si showed very good combination of high thermal conductivity and good casting characteristics.

  13. Effect of metal primers and tarnish treatment on bonding between dental alloys and veneer resin.

    Science.gov (United States)

    Choo, Seung-Sik; Huh, Yoon-Hyuk; Cho, Lee-Ra; Park, Chan-Jin

    2015-10-01

    The aim of this study was to evaluate the effect of metal primers on the bonding of dental alloys and veneer resin. Polyvinylpyrrolidone solution's tarnish effect on bonding strength was also investigated. Disk-shape metal specimens (diameter 8 mm, thickness 1.5 mm) were made from 3 kinds of alloy (Co-Cr, Ti and Au-Ag-Pd alloy) and divided into 4 groups per each alloy. Half specimens (n=12 per group) in tarnished group were immersed into polyvinylpyrrolidone solution for 24 hours. In Co-Cr and Ti-alloy, Alloy Primer (MDP + VBATDT) and MAC-Bond II (MAC-10) were applied, while Alloy Primer and V-Primer (VBATDT) were applied to Au-Ag-Pd alloys. After surface treatment, veneering composite resin were applied and shear bond strength test were conducted. Alloy Primer showed higher shear bond strength than MAC-Bond II in Co-Cr alloys and Au-Ag-Pd alloy (PAg-Pd alloy surfaces presented significantly decreased shear bond strength. Combined use of MDP and VBATDT were effective in bonding of the resin to Co-Cr and Au-Ag-Pd alloy. Tarnish using polyvinylpyrrolidone solution negatively affected on the bonding of veneer resin to Co-Cr and Au-Ag-Pd alloys.

  14. Effect of alloy content on microstructure and microchemistry of ...

    Indian Academy of Sciences (India)

    This paper presents the results of an experimental study on the microstructural evolution in 9Cr reduced activation ferritic/martensitic steels during short term thermal exposures. Since the microstructure is strongly influenced by the alloying additions, mainly W, Ta and C contents, the effect of varying W and Ta contents on ...

  15. Effect of alloying on the electronic structure and magnetic properties ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 26; Issue 1. Effect of alloying on the electronic structure and magnetic properties of Fe, Co and Ni with Au and Ag. Ashish Bhattacharjee Mesbahuddin Ahmed Abhijit Mookerjee Amal Halder. Volume 26 Issue 1 January 2003 pp 199-205 ...

  16. Effect of heat treatment on Fe-B-Si-Nb alloy powder prepared by mechanical alloying

    Directory of Open Access Journals (Sweden)

    Rodrigo Estevam Coelho

    2005-06-01

    Full Text Available The effect of heat treatment on crystallization behavior of Fe73.5B15Si10Nb1.5 alloy powder prepared by mechanical alloying was studied. The powder samples were prepared by mechanical alloying (MA and for different milling times (1, 5, 25, 70 and 100 hours. Crystalline powders of iron, boron, silicon and niobium were sealed with tungsten carbide balls in a cylindrical vial under nitrogen atmosphere. The ball-to-powder weight ratio was 20 to 1. A Fritsch Pulverizette 5 planetary ball mill was used for MA the powders at room temperature and at 250 rpm. To study the microstructural evolution, a small amount of powder was collected after different milling times and examined by X-ray diffraction, using CuKalpha radiation (lambda = 0.15418 nm. The crystallization behavior was studied by differential thermal analysis, from 25 up to 1000 °C at a heating rate of 25 °C min-1.

  17. Chemical-disorder effects in half-metallic Heusler alloys

    Science.gov (United States)

    Skomski, Ralph; Jin, Yunlong; Waybright, Jace; Kharel, Parashu; Pathak, Rohit; Choudhary, Renu; Kashyap, Arti; Sellmyer, D. J.

    The electronic structure, magnetism, and conductivity of disordered Heusler alloys are investigated theoretically and experimentally. Emphasis is on Heuslers that are predicted to be half-metallic or spin-gapless semiconducting in their fully ordered states, such as CoFeCrAl. Experimental alloys often exhibit resistivities of the order of 200 μΩ cm, which is consistent with both dirty-metal and spin-gapless semiconducting behaviors, but a distinction can be made by comparing the residual resistivities of samples having different degrees of order. The corresponding analysis shows that careful processing is necessary to keep the alloys in the spin-gapless semiconducting regime. Several types of disorder occur in Y-type Heusler alloys, with different negative effects on half-metallicity and spin-gapless semiconductivity. A2 (or bcc) disorder is most harmful but can be limited experimentally in CoFeCrAl thin films. B2 (or CsCl) disorder is less harmful, whereas L21 (normal Heusler) disorder, corresponding to Fe-Co solid solubility is least harmful. The residual resistivity of the partially diorderd alluys is discussed as a carrier-localization effect. This work is supported by DOE BES (DE-FG02-04ER46152, R.S.) and NSF DMREF (SusChEM 1436385, D.J.S.).

  18. X-ray diffraction broadening effects in metallic alloys

    International Nuclear Information System (INIS)

    Kimmel, G.; Dayan, D.

    1996-01-01

    Although an extensive work had been done in the last decade in the field of line broadening analysis of XRPD there is still little agreement whether this method can be accepted as a characterization tool. The purpose of the present work is to demonstrate that a valuable information can be retrieved from line broadening effects in XRPD. In this work it was focused on the line broadening effects accompanied with typical processes in metallic systems. The following systems were studied:, pure iron, steels, and alloying effects in uranium alloys. The broadening analysis was linked to different variables like hardness, Izod notch toughness, amount of cold work, surface treatment, concentration of additional elements in solid solutions. The Williamson-Hall method was adopted providing fast and global view of resolved 'strain'-'size' effects, considering the entire diffraction spectrum. The size effect was occasionally approved by direct observations of STM or SEM for example. The results of the broadening analysis were well correlated with other measured parameters like toughness and hardness. It was found that alloying in metallic system is sometimes expressed by pure strain effect but cold work results in a mix of strain and size broadening. The complete view of our results lead us to believe that broadening effect can be quantified. Hence, it is recommended to establish a quantitative XRD line broadening analysis method as a novel tool for characterization of metallic materials. (author)

  19. The two way memory effect in TiNi alloys

    Energy Technology Data Exchange (ETDEWEB)

    Filip, P.; Mazanec, K. [Technical Univ. of Ostrava (Czech Republic). Inst. of Materials Engineering

    1996-08-01

    The two way memory effect (TWME) in shape memory alloys represents a reversible spontaneous shape changes during cooling and heating processes. This is a consequence of reversible phase transformations observed without application of any external stresses. The TWME is usually obtained after a thermomechanical treatment often called training. The different opinions were published concerning the influence of R-phase formation in TiNi based alloys on the stability of TWME. Stachowiak and McCormick have stated that the formation of R-phase diminishes the extent of obtained reversible strain as well as the stability of TWME. In contrast to this conclusion, the authors observed enhanced stability of TWME in the cases when the R-phase formation precedes the martensitic transformation B2 {yields} B19{prime}. Repeating the heating cycles at loading of the memory materials, the complex degradation mechanisms of TiNi alloys occurs. The dislocation generation in the matrix of TiNi alloys (work hardening) strongly influences the maximum level of generated stresses and the extent of reversible strain. As a contribution to the explanation of physical principles of TWME, the present paper is devoted to the study of substructure after so called hard training at which the specimens are deformed ({var_epsilon} = 4%) and cyclically heated and cooled down at constrained conditions.

  20. [Effects of four dental alloys on apoptosis related gene and protein expression of fibroblast L929].

    Science.gov (United States)

    Meng, He; Ding, Jie; Li, Ren; Liang, Ruiying; Wu, Wenhui

    2013-06-01

    To investigate the effects of the leaching liquids of 4 differents kinds of dental alloys (Au alloy, Ag-Pd alloy, Co-Cr alloy, Ni-Cr alloy) on apoptosis related gene and protein of fibroblast L929. The L929 cells of mouse were treated in vitro with leaching liquids of 4 different kinds of dental alloys, Au alloy (group A), Ag-Pd alloy(group B), Co-Cr alloy(group C) and Ni-Cr alloy(group D). The RPMI1640 cell medium containing 10% fetal calf serum was served as a control(group E). The effects of these alloys on the expression of caspase-3, 8, 9 of L929 cells were examined by reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry method. Results After 48 h culture, the mRNA levels of caspase-3 and caspase-9 demonstrated significant differences between the groups expect group A and group E. The mRNA levels of caspase-8 had no change in all groups. The expression of caspase-3 and caspase-9 were significant differences between the groups expect group A and C, group B and D. The expression of caspase-8 had no change in all grotps. The leaching liquids of 4 different kinds of dental alloys expect Au alloy may induce cell appotosis through mitochondrion pathway.

  1. Effect of V or Zr addition on the mechanical properties of the mechanically alloyed Al-8wt%Ti alloys

    International Nuclear Information System (INIS)

    Moon, I.H.; Lee, J.H.; Lee, K.M.; Kim, Y.D.

    1995-01-01

    Mechanical alloying (MA) of Al-Ti alloy, being a solid state process, offers the unique advantage of producing homogeneous and fine dispersions of thermally stable Al 3 Ti phase, where the formation of the fine Al 3 Ti phase by the other method is restricted from the thermodynamic viewpoint. The MA Al-Ti alloys show substantially higher strength than the conventional Al alloys at the elevated temperature due to the presence of Al 3 Ti as well as Al 4 C 3 and Al 2 O 3 , of which the last two phases were introduced during MA process. The addition of V or Zr to Al-Ti alloy was known to decrease the lattice mismatch between the intermetallic compound and the aluminum matrix, and such decrease in lattice mismatching can influence positively the high temperature mechanical strength of the MA Al-Ti by increasing the resistance to dispersoid coarsening at the elevated temperature. In the present study, therefore, the mechanical behavior of the MA Al-Ti-V and Al-Ti-Zr alloys were investigated in order to evaluate the effect of V or Zr addition on the mechanical properties of the MA Al-8Ti alloy at high temperature

  2. Calculations of hydrogen diffusivity in Zr-based alloys: Influence of alloying elements and effect of stress

    Energy Technology Data Exchange (ETDEWEB)

    Yu, J. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Jiang, C. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Zhang, Y. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2017-06-01

    This report summarizes the progress on modeling hydrogen diffusivity in Zr-based alloys. The presence of hydrogen (H) can detrimentally affect the mechanical properties of many metals and alloys. To mitigate these detrimental effects requires fundamental understanding of the thermodynamics and kinetics governing H pickup and hydride formation. In this work, we focus on H diffusion in Zr-based alloys by studying the effects of alloying elements and stress, factors that have been shown to strongly affect H pickup and hydride formation in nuclear fuel claddings. A recently developed accelerated kinetic Monte Carlo method is used for the study. It is found that for the alloys considered here, H diffusivity depends weakly on composition, with negligible effect at high temperatures in the range of 600-1200 K. Therefore, the small variation in compositions of these alloys is likely not a major cause of the very different H pickup rates. In contrast, stress strongly affects H diffusivity. This effect needs to be considered for studying hydride formation and delayed hydride cracking.

  3. The effects of radiation on aluminium alloys in the core of energy nuclear reactors

    International Nuclear Information System (INIS)

    Petrossian, V.G.

    1995-01-01

    One of the attractive directions in the worldwide practice of nuclear installations is the replacement of expensive zirconium alloy with more cheap materials, particularly aluminium allo. For Heat Supply Nuclear Plants (HSNP) with approximately 473 K core temperatures, the use of heat-resistant aluminium alloys seems to be reasonable. The present work is concerned with the studies on radiation effects on aluminium alloy, and interaction between the alloy and coolant in the reactor core. (author). 2 refs., 3 figs., 1 tab

  4. Recrystallization microstructure modelling from superimposed ...

    Indian Academy of Sciences (India)

    The recovered cold rolled microstructure obtained from orientation image microstructure of Al–4%Mg–0.5%Mn alloy (AA5182 alloy) was superimposed on the grid of cellular automata based microstructure model. The Taylor factors of deformed/cold rolled orientations were considered as the driving force for recrystallization.

  5. Bulletin of Materials Science | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    The recovered cold rolled microstructure obtained from orientation image microstructure of Al–4%Mg–0.5%Mn alloy (AA5182 alloy) was superimposed on the grid of cellular automata based microstructure model. The Taylor factors of deformed/cold rolled orientations were considered as the driving force for recrystallization.

  6. Effects of Alloying Elements on Room and High Temperature Tensile Properties of Al-Si Cu-Mg Base Alloys =

    Science.gov (United States)

    Alyaldin, Loay

    In recent years, aluminum and aluminum alloys have been widely used in automotive and aerospace industries. Among the most commonly used cast aluminum alloys are those belonging to the Al-Si system. Due to their mechanical properties, light weight, excellent castability and corrosion resistance, these alloys are primarily used in engineering and in automotive applications. The more aluminum is used in the production of a vehicle, the less the weight of the vehicle, and the less fuel it consumes, thereby reducing the amount of harmful emissions into the atmosphere. The principal alloying elements in Al-Si alloys, in addition to silicon, are magnesium and copper which, through the formation of Al2Cu and Mg2Si precipitates, improve the alloy strength via precipitation hardening following heat treatment. However, most Al-Si alloys are not suitable for high temperature applications because their tensile and fatigue strengths are not as high as desired in the temperature range 230-350°C, which are the temperatures that are often attained in automotive engine components under actual service conditions. The main challenge lies in the fact that the strength of heat-treatable cast aluminum alloys decreases at temperatures above 200°C. The strength of alloys under high temperature conditions is improved by obtaining a microstructure containing thermally stable and coarsening-resistant intermetallics, which may be achieved with the addition of Ni. Zr and Sc. Nickel leads to the formation of nickel aluminide Al3Ni and Al 9FeNi in the presence of iron, while zirconium forms Al3Zr. These intermetallics improve the high temperature strength of Al-Si alloys. Some interesting improvements have been achieved by modifying the composition of the base alloy with additions of Mn, resulting in an increase in strength and ductility at both room and high temperatures. Al-Si-Cu-Mg alloys such as the 354 (Al-9wt%Si-1.8wt%Cu-0.5wt%Mg) alloys show a greater response to heat treatment as a

  7. Effect of dissolved oxygen on IGSCC of Alloy 600

    International Nuclear Information System (INIS)

    Maeng, W.Y.; Choi, M.S.; Kim, U.C.

    2002-01-01

    The effect of dissolved oxygen on the SCC of Alloy 600 was studied by the slow strain rate test(SSRT) method. The SSRT tests were carried out in aerated and in deaerated pure water at 360 C at the strain rate of 2.5 x 10 -7 /s. Hump specimens were used to shorten test time. The SCC susceptibility was higher in the deaerated water environment than in aerated water environments. The shape of load-deformation curves of the tests in those two environments indicates that oxygen content in water significantly influences the SCC susceptibility of Alloy 600. It was considered that the increase of SCC resistance in aerated water is due to the high corrosion potential of the metal surface, and the according decrease of corrosion current due to the formation of a protective oxide layer. (authors)

  8. Pressure-induced Invar effect in Fe-Ni alloys.

    Science.gov (United States)

    Dubrovinsky, L; Dubrovinskaia, N; Abrikosov, I A; Vennström, M; Westman, F; Carlson, S; van Schilfgaarde, M; Johansson, B

    2001-05-21

    We have measured the pressure-volume (P-V) relations for cubic iron-nickel alloys for three different compositions: Fe 0.64Ni (0.36), Fe 0.55Ni (0.45), and Fe 0.20Ni (0.80). It is observed that for a certain pressure range the bulk modulus does not change or can even decrease to some minimum value, after which it begins to increase under still higher pressure. In our experiment, we observe for the first time a new effect, namely, that the Fe-Ni alloys with high Ni concentrations, which show positive thermal expansion at ambient pressure, become Invar system upon compression over a certain pressure range.

  9. Effect of different oxidation treatments on the bonding strength of new dental alloys

    International Nuclear Information System (INIS)

    Lee, Sang-Bae; Lee, Ju-hye; Kim, Woong-Chul; Oh, Sae-Yoon; Kim, Kyoung-Nam; Kim, Ji-Hwan

    2009-01-01

    The influences of heat treatment and addition of a small amount of base metal (In, Sn, and Ir) for oxidation in Au-Pt-based alloy were investigated by electron spectroscopy and scanning electron microscopy. Au-Pt-based alloys were prepared by argon-arc melting furnace and then they are heat treated. Oxidation on alloy was significantly affected by addition of base metal (In and Sn) and heat treatment. The bond strength of the alloys was not dependent on the changing heat treatment. These results indicated that the Sn and In could be effective as oxidation elements for porcelain bonding to gold alloys.

  10. Effect of chemical composition of copper alloys on their hot-brittleness and weldability

    International Nuclear Information System (INIS)

    Zakharov, M.V.

    1985-01-01

    Effect of different alloying elements on the hot crack formation in argon-arc welding of M1 copper has been studied. It is shown that the effective crystallization interval has a determining influence on hot-brittleness of low-alloyed high-thermal- and electric conducting welded copper alloys. The narrow is this interval the lower is linear schrinkage and the alloys inclined to the formation of crystallization cracks in welding to a lesser degree. Alloying elements with low solubility in copper in solid state broadening the crystallization interval affect negatively the alloy hot-brittleness. Such additives as zirconium are useful at 0.02-0.O5% content and at > 0.1% content are intolerable. As to cadmium, tin, magnesium, cerium and antimony additives they don't practically strengthen copper and its alloys at 700-800 deg C and they should not be introduced

  11. The effect of zinc on the microstructure and phase transformations of casting Al-Cu alloys

    Directory of Open Access Journals (Sweden)

    Manasijević Ivana I.

    2016-01-01

    Full Text Available Copper is one of the main alloying elements for aluminum casting alloys. As an alloying element, copper significantly increases the tensile strength and toughness of alloys based on aluminum. The copper content in the industrial casting aluminum alloys ranges from 3,5 to 11 wt.%. However, despite the positive effect on the mechanical properties, copper has a negative influence on the corrosion resistance of aluminum and its alloys. In order to further improve the properties of Al-Cu alloys they are additional alloyed with elements such as zinc, magnesium and others. In this work experimental and analytical examination of the impact of zinc on the microstructure and phase transformations of Al-Cu alloys was carried out. In order to determine the effect of the addition of zinc to the structure and phase transformations of Al-Cu alloys two alloys of Al-Cu-Zn system with selected compositions were prepared and then examined using scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDX. The experimental results were compared with the results of thermodynamic calculations of phase equilibria.

  12. First-principles study of alloying effects on fluorine incorporation in Al x Ga1‑x N alloys

    Science.gov (United States)

    Wang, Rong; Tan, Wei; Zhang, Jian; Chen, Feng-Xiang; Wei, Su-Huai

    2018-02-01

    Incorporation of fluorine (F) into the AlGaN layer is crucial to the fabrication of enhancement-mode (E-mode) AlGaN/GaN high electron mobility transistors (HEMTs). However, the understanding of properties of F doping in AlGaN alloys is rather limited. Using first-principles calculations and the special quasirandom structure (SQS) approach, we investigate the alloying effects on the doping properties of F-incorporated Al x Ga1‑x N alloys. We find that substitutional F on N sites (FN) and interstitial F (Fi) are dominant defects for F in Al x Ga1‑x N alloys. For these two types of defects, both the global composition x and the local motif surrounding the dopant play important roles. On contrary, the incorporation of substitutional F on Ga sites (FGa) or Al sites (FAl) are affected only by the composition x. We also find that there exists a large asymmetric bowing for the effective formation energies of FN and Fi. These results are explained in terms of local structural distortion and electronic effects. The mechanism discussed in this paper can also be used in understanding doping in other semiconductor alloys.

  13. Effect of alloying addition and microstructural parameters on mechanical properties of 93% tungsten heavy alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ravi Kiran, U., E-mail: uravikiran@gmail.com [Defence Metallurgical Research Laboratory, Kanchanbagh, Hyderabad 500 058 (India); Panchal, A.; Sankaranarayana, M. [Defence Metallurgical Research Laboratory, Kanchanbagh, Hyderabad 500 058 (India); Nageswara Rao, G.V.S. [National Institute of Technology, Warangal 506004 (India); Nandy, T.K. [Defence Metallurgical Research Laboratory, Kanchanbagh, Hyderabad 500 058 (India)

    2015-07-29

    Liquid phase sintering, heat treatment and swaging studies on three tungsten heavy alloys, 93W–4.9Ni–2.1Fe (wt%), 93W–4.2Ni–1.2Fe–1.6Co (wt%) and 93W–4.9Ni–1.9Fe–0.2Re (wt%) were carried out in detail with respect to microstructure, tensile and impact properties. All the alloys were sintered and swaged to 40% deformation. The results indicate that Re addition reduces the grain size of the alloy compared to W–Ni–Fe and W-Ni-Fe-Co alloys. W–Ni–Fe–Re alloy shows superior tensile properties in heat treated condition as compared to W–Ni–Fe and W–Ni–Fe–Co alloys. SEM study of fractured specimens clearly indicates that the failure in case of W–Ni–Fe–Re was due to transgranular cleavage of tungsten grains and W–W de-cohesion. W–Ni–Fe and W–Ni–Fe–Co alloys also failed by mixed mode failure. However, in these cases, ductile dimples corresponding the failure of the matrix phase was rarely seen. Thermo-mechanical processing resulted in significant changes in mechanical properties. While W–Ni–Fe–Re alloy showed the highest tensile strength (1380 MPa), W–Ni–Fe–Co exhibited the highest elongation (12%) to failure. A detailed analysis involving microstructure, mechanical properties and failure behavior was undertaken in order to understand the property trends.

  14. Effect of Alloy 625 Buffer Layer on Hardfacing of Modified 9Cr-1Mo Steel Using Nickel Base Hardfacing Alloy

    Science.gov (United States)

    Chakraborty, Gopa; Das, C. R.; Albert, S. K.; Bhaduri, A. K.; Murugesan, S.; Dasgupta, Arup

    2016-04-01

    Dashpot piston, made up of modified 9Cr-1Mo steel, is a part of diverse safety rod used for safe shutdown of a nuclear reactor. This component was hardfaced using nickel base AWS ER NiCr-B alloy and extensive cracking was experienced during direct deposition of this alloy on dashpot piston. Cracking reduced considerably and the component was successfully hardfaced by application of Inconel 625 as buffer layer prior to hardface deposition. Hence, a separate study was undertaken to investigate the role of buffer layer in reducing the cracking and on the microstructure of the hardfaced deposit. Results indicate that in the direct deposition of hardfacing alloy on modified 9Cr-1Mo steel, both heat-affected zone (HAZ) formed and the deposit layer are hard making the thickness of the hard layer formed equal to combined thickness of both HAZ and deposit. This hard layer is unable to absorb thermal stresses resulting in the cracking of the deposit. By providing a buffer layer of Alloy 625 followed by a post-weld heat treatment, HAZ formed in the modified 9Cr-1Mo steel is effectively tempered, and HAZ formed during the subsequent deposition of the hardfacing alloy over the Alloy 625 buffer layer is almost completely confined to Alloy 625, which does not harden. This reduces the cracking susceptibility of the deposit. Further, unlike in the case of direct deposition on modified 9Cr-1Mo steel, dilution of the deposit by Ni-base buffer layer does not alter the hardness of the deposit and desired hardness on the deposit surface could be achieved even with lower thickness of the deposit. This gives an option for reducing the recommended thickness of the deposit, which can also reduce the risk of cracking.

  15. The Effect of Impurities on the Processing of Aluminum Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zi-Kui Liu; Shengjun Zhang; Qingyou Han; Vinod Sikka

    2007-04-23

    For this Aluminum Industry of the Future (IOF) project, the effect of impurities on the processing of aluminum alloys was systematically investigated. The work was carried out as a collaborative effort between the Pennsylvania State University and Oak Ridge National Laboratory. Industrial support was provided by ALCOA and ThermoCalc, Inc. The achievements described below were made. A method that combines first-principles calculation and calculation of phase diagrams (CALPHAD) was used to develop the multicomponent database Al-Ca-K-Li-Mg-Na. This method was extensively used in this project for the development of a thermodynamic database. The first-principles approach provided some thermodynamic property data that are not available in the open literature. These calculated results were used in the thermodynamic modeling as experimental data. Some of the thermodynamic property data are difficult, if not impossible, to measure. The method developed and used in this project allows the estimation of these data for thermodynamic database development. The multicomponent database Al-Ca-K-Li-Mg-Na was developed. Elements such as Ca, Li, Na, and K are impurities that strongly affect the formability and corrosion behavior of aluminum alloys. However, these impurity elements are not included in the commercial aluminum alloy database. The process of thermodynamic modeling began from Al-Na, Ca-Li, Li-Na, K-Na, and Li-K sub-binary systems. Then ternary and higher systems were extrapolated because of the lack of experimental information. Databases for five binary alloy systems and two ternary systems were developed. Along with other existing binary and ternary databases, the full database of the multicomponent Al-Ca-K-Li-Mg-Na system was completed in this project. The methodology in integrating with commercial or other aluminum alloy databases can be developed. The mechanism of sodium-induced high-temperature embrittlement (HTE) of Al-Mg is now understood. Using the thermodynamic

  16. EFFECTS OF EXTREME AND UNUSUAL CONDITIONS ON LANA ALLOYS: INTERIM REPORT, FY14 (U)

    Energy Technology Data Exchange (ETDEWEB)

    Shanahan, Kirk L.

    2014-04-25

    The TTP proposed research aimed at determining: a) the rate at which these changes occurred and the effect of initial conditions, especially in the early phases of Hydrogen Heat Treatment (HHT), b) whether or not different LANA alloys would show similar effects, and c) whether common contaminants/poisons impacted LANA alloy hydride chemistry similarly to what had been found for Pd and Pd-alloy hydride chemistry.

  17. Effect of aging on mixed-mode I/III fracture toughness of 2034 aluminum alloys

    International Nuclear Information System (INIS)

    Kamat, S.V.; Hirth, J.P.

    1996-01-01

    The effect of aging on the mixed-mode I/III fracture toughness was evaluated for two 2034 Al type alloys with different Mn content. The effect of aging was found to be significantly different in the two alloys. Alloy 1 which had < 0.1 wt% Mn exhibited a significant reduction in fracture toughness with increasing mode III loading contribution. In this alloy, increasing aging time resulted in less reduction of fracture toughness with increasing mode III loading contribution. On the other hand, alloy 2 which had 1.08 wt% Mn exhibited a marginal effect of mixed-mode loading on fracture toughness. In this alloy increasing aging time did not result in a significant change in the mixed-mode fracture behavior. The results are discussed in light of the microstructures, fracture mechanisms and deformation field ahead of the crack tip under mixed-mode loading

  18. Effects and mechanisms of grain refinement in aluminium alloys

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Grain refinement plays a crucial role in improving characteristics and properties of cast and wrought aluminium alloys. Generally Al–Ti and Al–Ti–B master alloys are added to the aluminium alloys to grain refine the solidified product. The mechanism of grain refinement is of considerable controversy in the scientific ...

  19. Effects and mechanisms of grain refinement in aluminium alloys

    Indian Academy of Sciences (India)

    2016-08-26

    Aug 26, 2016 ... Grain refinement plays a crucial role in improving characteristics and properties of cast and wrought aluminium alloys. Generally Al–Ti and Al–Ti–B master alloys are added to the aluminium alloys to grain refine the solidified product. The mechanism of grain refinement is of considerable controversy in the ...

  20. The effect lead impurities on the corrosion resistance of alloy 600 and alloy 690 in high temperature water

    International Nuclear Information System (INIS)

    Sakai, T.; Nakagomi, N.; Kikuchi, T.; Aoki, K.; Nakayasu, F.; Yamakawa, K.

    1998-01-01

    Degradation of nickel-based alloy steam generator (SG) tubing caused by lead-induced corrosion has been reported recently in some PWR plants. Several laboratory studies also have shown that lead causes intergranular or transgranular stress corrosion cracking (IGSCC or TGSCC) of the tubing materials. Information from previous studies suggests two possible explanations for the mechanism of lead-induced corrosion. One is selective dissolution of tube metal elements, resulting in formation of a lead-containing nickel-depleted oxide film as observed in mildly acidic environments. The other explanation is an increase in potential, as has been observed in lead-contaminated caustic environments, although not in all volatile treatment (AVT) water such as the ammonium-hydrazine water chemistry. These observation suggest that an electrochemical reaction between metal elements and dissolved lead might be the cause of lead-induced corrosion. The present work was undertaken to clarify the lead-induced corrosion mechanism of nickel-based alloys from an electrochemical viewpoint, focusing on mildly acidic and basic environments. These are the probable pH conditions in the crevice region between the tube and tube support plate of the SG where corrosion damage could occur. Measurements of corrosion potential and electrochemical polarization of nickel-based alloys were performed to investigate the effect of lead on electrochemical behavior of the alloys. Then, constant extension rate tests (CERT) were carried out to determine the corrosion susceptibility of the alloys in a lead-contaminated environment. (J.P.N.)

  1. Effect of neutron irradiation on Mo-Si amorphous alloys

    International Nuclear Information System (INIS)

    Ito, Fumitake; Hasegawa, Masayuki; Suzuki, Kenji; Honda, Toshihisa; Fukunaga, Toshiharu.

    1982-01-01

    The irradiation effects on Mo-Si amorphous alloys were investigated by means of X-ray diffraction and positron annihilation, and their electric resistance at low temperature was measured to examine the superconductivity of the alloys. The specimens of Mo 68 Si 32 and Mo 45 Si 55 were irradiated with the neutron fluence (E > 1 MeV) of about 9 x 10 18 n/cm 2 without temperature control in the Japanese Material Testing Reactor (JMTR). For these irradiated specimens, the X-ray diffraction experiment was performed to examine the irradiation effects on the radial distribution function, and the angular correlation curves for the positron annihilation were also measured. Both experiments showed that there was almost no irradiation effect. However, the width of the superconductive transition measured in Mo 68 Si 32 became extremely narrow due to neutron irradiation, and the transition temperature rose from 6.89 K to 7.03 K. On the other hand, in Mo 45 Si 55 , the width showed a tendency to become somewhat narrow, but the transition temperature shifted to the lower side. (Asami, T.)

  2. A Comparative Study Between Strain And Stress Based Forming Limit Analysis By Applying Several Phenomenological Yield Criteria

    International Nuclear Information System (INIS)

    Butuc, Marilena C.; Vincze, Gabriela T.; Gracio, Jose J.; Barata da Rocha, A.

    2005-01-01

    The present work aims at analyzing a comparative study between the strain-based forming limit criterion (FLD) and the stress-based forming limit criterion (FLSD), under linear and complex strain paths. The selected material is an AA5182-0 aluminium alloy. Some relevant remarks about stress-based forming limit criterion concept are presented

  3. Temperature Effects on the Tensile Properties of Precipitation-Hardened Al-Mg-Cu-Si Alloys

    Directory of Open Access Journals (Sweden)

    J.B. Ferguson

    2016-02-01

    Full Text Available Because the mechanical performance of precipitation-hardened alloys can be significantly altered with temperature changes, understanding and predicting the effects of temperatures on various mechanical properties for these alloys are important. In the present work, an analytical model has been developed to predict the elastic modulus, the yield stress, the failure stress, and the failure strain taking into consideration the effect of temperatures for precipitation-hardenable Al-Mg-Cu-Si Alloys (Al-A319 alloys. In addition, other important mechanical properties of Al-A319 alloys including the strain hardening exponent, the strength coefficient, and the ductility parameter can be estimated using the current model. It is demonstrated that the prediction results based on the proposed model are in good agreement with those obtained experimentally in Al-A319 alloys in the as-cast condition and after W and T7 heat treatments.

  4. EFFECTS OF LASER SHOCK PEENING ON SCC BEHAVIOR OF ALLOY 600

    Energy Technology Data Exchange (ETDEWEB)

    Abhishek Telang; Amrinder Gill; S.R.Mannava; Vijay K. Vasudevan; Dong Qian; Sebastien P. Teysseyre

    2013-08-01

    In this study, the effects of laser shock peening (LSP) on stress corrosion cracking (SCC) behavior of Alloy 600 in tetrathionate solution were investigated. The degree of sensitization was quantified using double loop electrochemical potentiokinetic reactivation (DLEPR) tests. The sensitized Alloy 600 was demonstrated to be susceptible to intergranular SCC in tetrathionate solution. Following LSP, residual stresses and the amount of plastic strain introduced in Alloy 600 were characterized. The effects of LSP on SCC susceptibility of Alloy 600 in tetrathionate solution were evaluated by slow strain rate tests and constant load tests. Results indicate a significant increase in resistance to crack initiation and decreased susceptibility to SCC after LSP.

  5. Improvement of shape memory effect in Fe-Mn-Si alloy by slight tantalum addition

    International Nuclear Information System (INIS)

    Yang, Cheng-Hsiu; Lin, Hsin-Chih; Lin, Kun-Ming

    2009-01-01

    The effects of slight tantalum (Ta) addition on the microstructures, precipitates, martensitic transformation and shape memory performance of Fe-30Mn-6Si-based alloys were investigated. Experimental results show that the slight Ta addition will increase the c/a ratio of ε martensite, reduce the M s temperature and improve the alloy's shape recovery ability. After TMT at 650 deg. C, the alloy's M s temperature is reduced and lots of (Fe, Mn) 3 Si and TaC precipitates form. The effective nuclei and well-aligned precipitates within the grain interior after TMT will improve significantly the alloy's shape memory performance.

  6. Effect of mechanical alloying on FeCrC reinforced Ni alloys

    Energy Technology Data Exchange (ETDEWEB)

    Yilmaz, S. Osman [Univ. of Namik Kemal, Tekirdag (Turkey); Teker, Tanju [Adiyaman Univ. (Turkey). Dept. of Metallurgical and Materials Engineering; Demir, Fatih [Batman Univ. (Turkey)

    2016-05-01

    Mechanical alloying (MA) is a powder metallurgy processing technique involving cold welding, fracturing and rewelding of powder particles in a high-energy ball mill. In the present study, the intermetallic matrix composites (IMCs) of Ni-Al reinforced by M{sub 7}C{sub 3} were produced by powder metallurgical routes via solid state reaction of Ni, Al and M{sub 7}C{sub 3} particulates by mechanical alloying processes. Ni, Al and M{sub 7}C{sub 3} powders having 100 μm were mixed, mechanical alloyed and the compacts were combusted in a furnace. The mechanically alloyed (MAed) powders were investigated by X-ray diffraction (XRD), microhardness measurement, optic microscopy (OM), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The presence of the carbides depressed the formation of unwanted NiAl intermetallic phases. The mechanical alloyed M{sub 7}C{sub 3} particles were unstable and decomposed partially within the matrix during alloying and sintering, and the morphology of the composites changed with the dissolution ratio of M{sub 7}C{sub 3} and sintering temperature.

  7. Effect of mechanical alloying on FeCrC reinforced Ni alloys

    International Nuclear Information System (INIS)

    Yilmaz, S. Osman; Teker, Tanju

    2016-01-01

    Mechanical alloying (MA) is a powder metallurgy processing technique involving cold welding, fracturing and rewelding of powder particles in a high-energy ball mill. In the present study, the intermetallic matrix composites (IMCs) of Ni-Al reinforced by M 7 C 3 were produced by powder metallurgical routes via solid state reaction of Ni, Al and M 7 C 3 particulates by mechanical alloying processes. Ni, Al and M 7 C 3 powders having 100 μm were mixed, mechanical alloyed and the compacts were combusted in a furnace. The mechanically alloyed (MAed) powders were investigated by X-ray diffraction (XRD), microhardness measurement, optic microscopy (OM), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The presence of the carbides depressed the formation of unwanted NiAl intermetallic phases. The mechanical alloyed M 7 C 3 particles were unstable and decomposed partially within the matrix during alloying and sintering, and the morphology of the composites changed with the dissolution ratio of M 7 C 3 and sintering temperature.

  8. Effects of Friction Stir Welding Speed on AA2195 alloy

    Directory of Open Access Journals (Sweden)

    Lee Ho-Sung

    2016-01-01

    Full Text Available The application of friction stir welding (FSW to aerospace has grown rapidly due to the high efficiency and environmental friendly nature of the process. FSW is achieved by plastic flow of frictionally heated material in solid state and offers many advantages of avoiding hot cracking and limiting component distortion. Recently low density, high modulus and high strength AA2195 are used as substitute for conventional aluminum alloys since the weight saving is critical in aerospace applications. One of the problems for this alloy is weld metal porosity formation leading to hot cracking. Combination of FSW and AA2195 provides synergy effect to improve mechanical properties and weight saving of aerospace structure such as cryogenic fuel tanks for launch systems. The objective of this paper is to investigate the effect of friction stir welding speed on mechanical and microstructural properties of AA2195. The friction stir welded materials were joined with four different tool rotation speeds (350~800 rpm and five welding speeds (120~360 mm/min, which are the two prime welding parameters in this process.

  9. The effect of recasting on bond strength between porcelain and base-metal alloys.

    Science.gov (United States)

    Madani, Azam S; Rokni, Shahin Rezaii; Mohammadi, Abolghasem; Bahrami, Mehran

    2011-04-01

    Long-term success of metal ceramic restorations depends on metal ceramic bond strength. The purpose of this study was to determine whether recasting of base-metal alloys has any effect on metal ceramic bond strength. Super Cast and Verabond base-metal alloys were used to cast 260 wax patterns. The alloy specimens were equally divided into five groups and cast as: group A 0.0%, B 25%, C 50%, D 75%, and E 100% once-cast alloy. Each group was divided into two subgroups: the first group was cast with Super Cast and the second with Verabond. In each subgroup half of the cast alloys were veneered with Vita VMK 68 and the others with Ceramco 3. Recasting decreased bond strength (p alloy. Group E with 100% new Super Cast alloy veneered with Vita VMK 68 porcelain had the highest bond strength (30.75 ± 9.58 MPa), and group B including 25% new and 75% recast Super Cast alloy veneered with the same porcelain had the lowest bond strength (21.72 ± 5.19 MPa). By adding over 50% once-cast alloy in base-metal alloys, metal-ceramic bond strength decreases significantly. © 2011 by The American College of Prosthodontists.

  10. Effect of Ternary Addition of Iron on Shape Memory Characteristics of Cu-Al Alloys

    Science.gov (United States)

    Raju, T. N.; Sampath, V.

    2011-07-01

    The effect of alloying Cu-Al alloys with Fe on their transformation temperatures and shape memory properties was investigated by differential scanning calorimetry and bend test. It was found that the minor additions of iron resulted in change of transformation temperatures and led to excellent shape memory properties of the alloys. Since the transformation temperatures are high, they are an ideal choice for high-temperature applications.

  11. Local lattice relaxations in random metallic alloys: Effective tetrahedron model and supercell approach

    DEFF Research Database (Denmark)

    Ruban, Andrei; Simak, S.I.; Shallcross, S.

    2003-01-01

    We present a simple effective tetrahedron model for local lattice relaxation effects in random metallic alloys on simple primitive lattices. A comparison with direct ab initio calculations for supercells representing random Ni0.50Pt0.50 and Cu0.25Au0.75 alloys as well as the dilute limit of Au...

  12. Thermal Exposure Effects on Properties of Al-Li Alloy Plate Products

    Science.gov (United States)

    Shah, Sandeep; Wells, Douglas; Wagner, John; Babel, Henry

    2003-01-01

    The objective of this viewgraph representation is to evaluate the effects of thermal exposure on the mechanical properties of both production mature and developmental Al-Li alloys. The researchers find for these alloys, the data clearly shows that there is no deficit in mechanical properties at lower exposure temperatures in some cases, and a signficant deficit in mechanical properties at higher exposure temperatures in all cases. Topics considered include: Al-Li alloys composition, key characteristics of Al-Li alloys and thermal exposure matrix.

  13. Cooperative effect of silicon and other alloying elements on creep resistance of titanium alloys: insight from first-principles calculations.

    Science.gov (United States)

    Li, Yang; Chen, Yue; Liu, Jian-Rong; Hu, Qing-Miao; Yang, Rui

    2016-07-28

    Creep resistance is one of the key properties of titanium (Ti) alloys for high temperature applications such as in aero engines and gas turbines. It has been widely recognized that moderate addition of Si, especially when added together with some other elements (X), e.g., Mo, significantly improves the creep resistance of Ti alloys. To provide some fundamental understandings on such a cooperative effect, the interactions between Si and X in both hexagonal close-packed α and body-centered cubic β phases are systematically investigated by using a first-principles method. We show that the transition metal (TM) atoms with the number of d electrons (Nd) from 3 to 7 are attractive to Si in α phase whereas those with Nd > 8 and simple metal (SM) alloying atoms are repulsive to Si. All the alloying atoms repel Si in the β phase except for the ones with fewer d electrons than Ti. The electronic structure origin underlying the Si-X interaction is discussed based on the calculated electronic density of states and Bader charge. Our calculations suggest that the beneficial X-Si cooperative effect on the creep resistance is attributable to the strong X-Si attraction.

  14. Effect of Sn addition on the microstructure and superelasticity in Ti-Nb-Mo-Sn alloys.

    Science.gov (United States)

    Zhang, D C; Yang, S; Wei, M; Mao, Y F; Tan, C G; Lin, J G

    2012-09-01

    Ti-7.5Nb-4Mo-xSn (x=0-4at%) alloys were developed as the biomedical materials. The effect of the Sn content on the microstructure and superelasticity of the alloys was investigated. It is found that Sn is a strong stabilizer of the β phase, which is effective in suppressing the formation of α″ and ω phases in the alloys. Moreover, the Sn addition has a significant impact on the mechanical properties of the alloys. With the increase of Sn addition, the yield stress of the alloys increase, but their elastic modulus, the fracture strength and the ductility decrease, and the deformation mode of the alloys changes from (322) twining to α″ transformation and then to slip. The Ti-7.5Nb-4Mo-1Sn and Ti-7.5Nb-4Mo-3Sn alloys exhibit a good superelasticity with a high σ(SIM) due to the relatively high athermal ω phases containing or the solution hardening at room temperature. Under the maximum strain of 5%, Ti-7.5Nb-4Mo-3Sn (at%) alloy exhibits higher super elastic stability than that of Ti-7.5Nb-4Mo-1Sn alloy. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. Effects of sodium tartrate anodizing on fatigue life of TA15 titanium alloy

    Directory of Open Access Journals (Sweden)

    Fu Chunjuan

    2015-08-01

    Full Text Available Anodizing is always used as an effective surface modification method to improve the corrosion resistance and wear resistance of titanium alloy. The sodium tartrate anodizing is a new kind of environmental anodizing method. In this work, the effects of sodium tartrate anodizing on mechanical property were studied. The oxide film was performed on the TA15 titanium alloy using sodium tartrate as the film former. The effects of this anodizing and the traditional acid anodizing on the fatigue life of TA15 alloy were compared. The results show that the sodium tartrate anodizing just caused a slight increase of hydrogen content in the alloy, and had a slight effect on the fatigue life. While, the traditional acid anodizing caused a significant increase of hydrogen content in the substrate and reduced the fatigue life of the alloy significantly.

  16. Alloying effects on the high-temperature oxidation resistance of Cr-Cr{sub 2}Nb

    Energy Technology Data Exchange (ETDEWEB)

    Tortorelli, P.F.; DeVan, J.H.

    1994-09-01

    Alloying effects on the high-temperature oxidation resistance of Cr-Cr{sub 2}Nb were examined on the basis of isothermal exposures to air at 950 C. Additions of either Re and Al or Fe, Ni, and Al had relatively little effect on weight gains relative to the Cr-6% Nb binary alloy. One alloying element that improved the mechanical behavior of Cr-Cr{sub 2}Nb alloys substantially increased the oxidation rates and spallation susceptibilities of Cr-6 and -12% Nb alloys. However, the addition of another element completely offset these deleterious effects. The presence of this latter element resulted in the best overall oxidation behavior (in terms of both weight gains and spallation tendencies) of all Cr-Cr{sub 2}Nb compositions. Its beneficial effect can be attributed to improvement in the oxidation resistance of the Cr-rich phase.

  17. Effect of hydrogen on the behavior of metals II - Hydrogen embrittlement of titanium alloy TV13CA - effect of oxygen - comparison with non-alloyed titanium

    International Nuclear Information System (INIS)

    Arditty, Jean-Pierre

    1973-01-01

    The effect of oxygen on the hydrogen embrittlement of non-alloyed titanium and the metastable β titanium alloy, TV13 CA, was studied during dynamic mechanical tests, the concentrations considered varying from 1000 to 5000 ppm (oxygen) and from 0 to 5000 ppm (hydrogen) respectively. TV13 CA alloy has a very high solubility for hydrogen. The establishment of a temperature range and a rate of deformation region in which the embrittlement of the alloy is maximum leads to the conclusion that an embrittlement mechanism occurs involving the dragging and accumulation of hydrogen by dislocations. This is the case for all annealings effected in the medium temperature range, which, by favoring the re-establishment of the stable two-phase α + β state of the alloy, produce hardening. The same is true for oxygen which, in addition to hardening the alloy by the solid solution effect, tends to increase its instability and, in consequence, favors the decomposition of the β phase. Nevertheless oxygen concentrations of up to 1500 ppm contribute to increasing the mechanical resistance without catastrophically reducing the deformation capacity. In the case of non-alloyed titanium, the hardening effect also leads to an increase in E 0.2p c and R, and to a reduction in the deformation capacity. Nevertheless, hydrogen is only very slightly soluble at room temperature and a distribution of the hydride phase linked to the thermal history of the sample predominates. Thus a fine acicular structure obtained from the β phase by quenching, enables an alloy having a good mechanical resistance to be conserved even when large quantities of hydrogen are present; the deformation capacity remains small. On the other hand, when the hydride phase separates the metallic phase into large grains, a very small elongation leads to a breakdown in mechanical resistance. (author) [fr

  18. Effect of manganese on the microstructure, mechanical properties and corrosion behavior of titanium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ji-Woo; Hwang, Moon-Jin; Han, Mi-Kyung [Department of Dental Materials and MRC for Biomineralization Disorders, School of Dentistry, Chonnam National University, Gwangju 500-757 (Korea, Republic of); Kim, Yong-Geun [Department of Ophthalmic Optics, Dongkang College, Gwangju 500-714 (Korea, Republic of); Song, Ho-Jun [Department of Dental Materials and MRC for Biomineralization Disorders, School of Dentistry, Chonnam National University, Gwangju 500-757 (Korea, Republic of); Park, Yeong-Joon, E-mail: yjpark@jnu.ac.kr [Department of Dental Materials and MRC for Biomineralization Disorders, School of Dentistry, Chonnam National University, Gwangju 500-757 (Korea, Republic of)

    2016-09-01

    The phase/microstructure, mechanical properties and corrosion behavior of a series of binary Ti−Mn alloys with 5, 10, 15 and 20 wt% Mn were investigated in order to understand the effects of Mn content on mechanical properties, oxidation behavior, and electrochemical corrosion properties of Ti−Mn alloys. The phase/microstructure of Ti-xMn alloys was analyzed using X-ray diffractometry, scanning electron microscopy, and transmission electron microscopy. All examined properties of the Ti−Mn alloys were sensitive to the Mn content. The tested Ti-xMn alloys had α-Ti, β-Ti, and α-TiMn phases. Ti−Mn alloy containing 5 wt% Mn composed of α-Ti, β-Ti, α-TiMn, and isothermal ω phases. The proportion of α-Ti phase decreased and precipitation of β-Ti phase increased with increasing wt% of Mn. Cast Ti−Mn exhibited higher hardness and better oxidation protection than commercially pure Ti (cp-Ti). The tested Ti-xMn alloys showed better corrosion resistance than the cp-Ti. Ti−Mn alloy containing 5 wt% Mn had the highest hardness and lowest modulus, and is a good candidate for dental implant alloy. - Highlights: • Mechanical properties of Ti−Mn alloys were sensitive to the content of Mn. • As Mn content increased, α-Ti phase decreased and β-Ti phase increased. • Ti−Mn exhibited higher hardness and better oxidation protection ability. • Ti−Mn displayed superior corrosion resistance than commercially pure Ti. • Ti−Mn alloy with 5 wt% Mn is a good candidate for dental casting alloy.

  19. Effects of Cr and Nb contents on the susceptibility of Alloy 600 type Ni-base alloys to stress-corrosion cracking in a simulated BWR environment

    International Nuclear Information System (INIS)

    Akashi, Masatsune

    1995-01-01

    In order to discuss the effects of chromium and niobium contents on the susceptibility of Alloy 600 type nickel-base alloys to stress-corrosion cracking in the BWR primary coolant environment, a series of creviced bent-beam (CBB) tests were conducted in a high-temperature, high-purity water environment. Chromium, niobium, and titanium as alloying elements improved the resistivity to stress-corrosion cracking, whereas carbon enhanced the susceptibility to it. Alloy-chemistry-based correlations have been defined to predict the relative resistances of alloys to stress-corrosion cracking. A strong correlation was found, for several heats of alloys, between grain-boundary chromium depletion and the susceptibility to stress-corrosion cracking

  20. Effect of Mo content on thermal and mechanical properties of Mo–Ru–Rh–Pd alloys

    International Nuclear Information System (INIS)

    Masahira, Yusuke; Ohishi, Yuji; Kurosaki, Ken; Muta, Hiroaki; Yamanaka, Shinsuke; Komamine, Satoshi; Fukui, Toshiki; Ochi, Eiji

    2015-01-01

    Metallic inclusions are precipitated in irradiated oxide fuels. The composition of the phases varies with the burnup and the conditions such as temperature gradients and oxygen potential of the fuel. In the present work, Mo x/(0.7+x) (Ru 0.5 Rh 0.1 Pd 0.1 ) (0.7)/(0.7+x) (x = 0, 0.05, 0.1, 0.15, 0.2, and 0.25) alloys were prepared by arc melting, followed by annealing in a high vacuum. The thermal and mechanical properties of the alloys such as elastic moduli, Debye temperature, micro-Vickers hardness, electrical resistivity, and thermal conductivity have been evaluated to elucidate the effect of Mo content on these physical properties of the alloys. The alloys with lower Mo contents show higher thermal conductivity. The thermal conductivity of the alloy with x = 0 is almost twice of that of the alloy with x = 0.25. The thermal conductivities of the alloys are dominated by electronic contribution, which has been evaluated using the Wiedemann–Franz–Lorenz relation from the electrical resistivity data. It is confirmed that the variation of the Mo contents of the alloys considerably affects the mechanical and thermal properties of the alloys

  1. Effect of recasting of nickel-chromium alloy on its porosity

    Directory of Open Access Journals (Sweden)

    Jayant Palaskar

    2010-01-01

    Full Text Available Statement of Problem: As per the review of literature very few studies have been carried on recasting of dental casting alloy and in particlular its effect on occurrence of porosities. Purpose of Study: This study was designed to find out occurrence of porosities in new alloy and recasted alloy using a scanning electron microscope. Materials and Methods: Different percentage combinations of new and once casted alloy were used to produce twenty five samples. Castings obtained from new alloy were used as control group. All the samples were scanned under scanning electron mocroscope and photographs were taken from three specific sites for comparison. Results: There is no significant difference in occurrence of porosities in casting obtained by using new alloy and recasted alloy. Conclusion: With in the limitations of the study it is conducted that the prorosities will not be affected by recasting of neckel-chromium alloy. Clinical Implication: Porosities in dental casting alloy can alter physical and mechanical properties of the mental which inturn may lead to failure of crown and bridge, and also cast partial denture prosthesis.

  2. Modification effect of Ni-38 wt.%Si on Al-12 wt.%Si alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wu Yuying [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Ji' nan 250061 (China)], E-mail: wyy532001@163.com; Liu Xiangfa [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Ji' nan 250061 (China); Shandong Binzhou Bohai Piston Co., Ltd., Binzhou 256602, Shandong (China); Jiang Binggang [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Ji' nan 250061 (China); Huang Chuanzhen [School of Mechanical Engineering, Shandong University, Jinan 250061 (China)

    2009-05-27

    Modification effect of Ni-38 wt.%Si on the Al-12 wt.%Si alloy has been studied by differential scanning calorimeter, torsional oscillation viscometer and liquid X-ray diffraction experiments. It is found that there is a modification effect of Ni-38 wt.%Si on Al-12 wt.%Si alloy, i.e. primary Si can precipitate in the microstructure of Al-12 wt.%Si alloy when Ni and Si added in the form of Ni-38 wt.%Si, but not separately. Ni-38 wt.%Si alloy brings 'genetic materials' into the Al-Si melt, which makes the melt to form more ordering structure, promotes the primary Si precipitated. Moreover, the addition of Ni-38 wt.%Si, which decreases the solidification supercooling degree of Al-12 wt.%Si alloy, is identical to the effect of heterogeneous nuclei.

  3. First Principles Calculations of Transition Metal Binary Alloys: Phase Stability and Surface Effects

    Science.gov (United States)

    Aspera, Susan Meñez; Arevalo, Ryan Lacdao; Shimizu, Koji; Kishida, Ryo; Kojima, Kazuki; Linh, Nguyen Hoang; Nakanishi, Hiroshi; Kasai, Hideaki

    2017-06-01

    The phase stability and surface effects on binary transition metal nano-alloy systems were investigated using density functional theory-based first principles calculations. In this study, we evaluated the cohesive and alloying energies of six binary metal alloy bulk systems that sample each type of alloys according to miscibility, i.e., Au-Ag and Pd-Ag for the solid solution-type alloys (SS), Pd-Ir and Pd-Rh for the high-temperature solid solution-type alloys (HTSS), and Au-Ir and Ag-Rh for the phase-separation (PS)-type alloys. Our results and analysis show consistency with experimental observations on the type of materials in the bulk phase. Varying the lattice parameter was also shown to have an effect on the stability of the bulk mixed alloy system. It was observed, particularly for the PS- and HTSS-type materials, that mixing gains energy from the increasing lattice constant. We furthermore evaluated the surface effects, which is an important factor to consider for nanoparticle-sized alloys, through analysis of the (001) and (111) surface facets. We found that the stability of the surface depends on the optimization of atomic positions and segregation of atoms near/at the surface, particularly for the HTSS and the PS types of metal alloys. Furthermore, the increase in energy for mixing atoms at the interface of the atomic boundaries of PS- and HTSS-type materials is low enough to overcome by the gain in energy through entropy. These, therefore, are the main proponents for the possibility of mixing alloys near the surface.

  4. Effect of Ti3+ ion on the Corrosion Behavior of Alloy 600

    International Nuclear Information System (INIS)

    Lee, Chang Bong; Lim, Han Gwi; Kim, Bok Hee; Kim, Ki Ju

    1999-01-01

    Alloy 600 has been widely used as a steam generator tubing material in pressurized water reactors(PWRs) nuclear power plants. Corrosion of steam generator tubing mainly occurs on the secondary water side. The purpose of this work is primarily concerned with examining the effect of Ti 3+ ion concentrations on the corrosion behavior of the Alloy 600 steam generator tubing material. Corrosion behavior of the Alloy 600 steam generator tubing material was studied in aqueous solutions with varying Ti 3+ ion concentration at room temperature. Potentiodynamic and potentiostatic polarization techniques were used to determine the corrosion and pitting potentials for the Alloy 600 test material. The addition of Ti 3+ ion to 1000ppm, showed inhibition effect on the corrosion of Alloy 600. But the corrosion of Alloy 600 was accelerated when the concentration of Ti 3+ ion exceeded 1000ppm, it is assumed that the effect of general corrosion of Alloy 600 is more sensitive than pitting corrosion. It is considered that the passive film which was formed on the Alloy 600 surface in the 100ppm Ti 3+ ion containing solution is mainly consisted of TiO 2

  5. Mechanical behavior and coupling between mechanical and oxidation in alloy 718: effect of solide solution elements

    International Nuclear Information System (INIS)

    Max, Bertrand

    2014-01-01

    Alloy 718 is the superalloy the most widely used in industry due to its excellent mechanical properties, as well as oxidation and corrosion resistance in wide range of temperatures and solicitation modes. Nevertheless, it is a well-known fact that this alloy is sensitive to stress corrosion cracking and oxidation assisted cracking under loading in the range of temperatures met in service. Mechanisms explaining this phenomenon are not well understood: nevertheless, it is well established that a relation exists between a change in fracture mode and the apparition of plastic instabilities phenomenon. During this study, the instability phenomenon, Portevin-Le Chatelier effect, in alloy 718 was studied by tensile tests in wide ranges of temperatures and strain rates. Different domains of plastic instabilities have been evidenced. Their characteristics suggest the existence of interactions between dislocations and different types of solute elements: interstitials for lower temperatures and substitutionals for higher testing temperatures. Mechanical spectroscopy tests have been performed on alloy 718 and various alloys which composition is comparable to that of alloy 718. These tests prove the mobility of molybdenum atoms in the alloy in the studied temperature range. Specific tests have been performed to study interaction phenomenon between plasticity and oxidation. These results highlight the strong effect of plastic strain rate on both mechanical behavior and intergranular cracking in alloy 718. The subsequent discussion leads to propose hypothesis on coupling effects between deformation mechanisms and oxidation assisted embrittlement in the observed cracking processes. (author)

  6. Effect of hydrogen addition on the microstructure of TC21 alloy

    International Nuclear Information System (INIS)

    Zhu Tangkui; Li Miaoquan

    2010-01-01

    Research highlights: → The aim of this paper is to study the effect of hydrogen content (0-0.887 wt.%H) on microstructure, phase composition, microhardness and β transus temperature of TC21 alloy. The results show that, with increasing hydrogen content, the β phase increases, the α/β interfaces of lamellar transformed β phase disappear, the lattice parameter of β phase increases and the β transus temperature decreases for the hydrogenated TC21 alloy. In comparison to the as-received TC21 alloy, the contrasts of primary α phase and transformed β phase under optical microscope in the TC21 alloy with high hydrogen content are reversed completely. Furthermore, the γ and δ hydrides are detected in the hydrogenated TC21 alloy. In addition, the variations of phase compositions for the hydrogenated TC21 alloy have influence on microhardness and β transus temperature. → In conclusion, this paper shows some significant rules about the influence of hydrogen on TC21 alloy. - Abstract: TC21 alloy was hydrogenated at 750 deg. C with different hydrogen contents ranging from 0 to 0.873 wt.%H, and its microstructural evolution and phase transformations were investigated by optical microscopy (OM) and X-ray diffraction (XRD). The microhardness and the β transus temperature for the hydrogenated TC21 alloy were determined by microhardness testing and metallographical approach, respectively. The results show that, hydrogen addition has a noticeable influence on microstructure, phase composition, microhardness and β transus temperature of TC21 alloy. With increasing hydrogen content, the β phase increases, the α/β interfaces of lamellar transformed β phase disappear, the lattice parameter of β phase increases and the β transus temperature decreases for the hydrogenated TC21 alloy. In comparison to the as-received TC21 alloy, the contrasts of primary α phase and transformed β phase under optical microscope in the hydrogenated TC21 alloy with high hydrogen

  7. Giant magnetocaloric effect in Gd5(Si2Ge2 alloy with low purity Gd

    Directory of Open Access Journals (Sweden)

    Cleber Santiago Alves

    2004-12-01

    Full Text Available Gd5(Ge1-xSi x, x < 4 based alloys are potential candidates for magnetic refrigeration in the range ~20 - ~290 K. However, one of the greatest obstacles for the use of that technology in large scale is the utilization of high pure Gd metal (99.99 wt. (% to produce the GdGeSi alloys, since the impurity elements decrease the intensity of the magnetocaloric effect (EMC¹. In this work, we prove that annealing of the Gd5Ge2Si2 can promote remarkable values for the EMC in comparison to those obtained for the alloy with high pure Gd. Also, the as cast alloy and the annealed alloy are not monophasic, but have at least two crystalline phases in their microstructure. Results for X-ray analysis, optical and electronic microscopy and magnetization measurements are reported.

  8. Long-term effects of Ag-containing alloys on mucous tissue present in biopsy samples.

    Science.gov (United States)

    Aoyagi, Hidekazu; Katagiri, Masataka

    2004-09-01

    The aim of this study was to investigate the long-term effects of alloys containing silver (mainly Ag-Sn alloy) on oral mucous tissue. We observed biopsy tissue specimens from patients diagnosed as having amalgam tattoo and/or metal pigmentation by light and electron microscopy and electron-probe microanalysis (EPMA). In most cases, Ag-Sn alloy was present in the tissue but it could not be confirmed if the alloy originated from amalgam. Distributions of both Ag-S and Ag-Sn have typical patterns. Most Ag forms Ag2S and is stably deposited in three patterns along the collagen, basement membrane, and fibrous cells without inducing any host reaction. On the other hand, Sn forms large granules that contain Ag, S, C, N, P, and Ca, and is in soft state in the tissue. Tissue reactions to the alloy become weaker as time passes.

  9. Effects of copper-based alloy on the synthesis of single-crystal diamond

    CERN Document Server

    Chen Li Xue; Ma Hong An; Jia Xiao Peng; Wakatsuki, M; Zou Guang Tian

    2002-01-01

    The catalytic effects of copper-based alloys in diamond growth have been investigated. A single crystal of diamond has been obtained by the temperature gradient method (TGM), using Cu-Mn-Co and Cu-Co alloys as catalysts. It was found that the melted Cu-Mn-Co and Cu-Co alloys show low viscosity. The eutectic temperatures of these two alloys with graphite were between 1130 and 1150 deg. C, and the temperature of the transition to diamond was over 1300 deg. C at 5.5 GPa. High-quality diamond could not be obtained in Cu-Co alloy by the TGM. Our results suggest that adding Cu to a catalyst cannot decrease the reaction temperature for diamond growth.

  10. Microstructures responsible for the invar and permalloy effects in Fe-Ni alloys

    Science.gov (United States)

    Ustinovshchikov, Yu. I.; Shabanova, I. N.; Lomova, N. V.

    2015-05-01

    The experimental studies of Fe68Ni32 and Fe23Ni77 alloys by transmission electron microscopy and X-ray electron spectroscopy show that the ordering-separation phase transition in these alloys occurs in a temperature range near 600°C. At temperatures higher than the transition temperature, the ordering energy of the alloy is positive, and the structures contain clusters enriched in one of the components. After heat treatment at the temperatures where the invar effect in the Fe68Ni32 alloy is maximal, a modulated microstructure forms. Below the transition temperature, the ordering energy is negative, which provides a tendency to formation of chemical compounds. After aging at these temperatures (where the Fe23Ni77 alloy exhibits high permalloy properties), highly dispersed completely coherent particles of the FeNi3 phase with structure L12 precipitate in a solid solution.

  11. Technical aspects of casting and their effect on the quality of Remanium CSe dental alloys

    Directory of Open Access Journals (Sweden)

    Dorota Klimecka-Tatar

    2016-03-01

    Full Text Available The study concerns on investigation of Remanium CSE alloy, one of the dental alloys used in metal-ceramic connection preparation. The alloys based on Ni-Cr-Mo are widely used in dental engineering because of their high mechanical, tribological properties as well as high corrosion resistance. The tested alloy has been processed in three ways – it has been remelted and then casted using three technologiescommonly used in dental laboratories, i.e. with: oxy-acetylene burner (1, induction furnace (2 and Volts arc (3. The aim of the study was to evaluate the effect of the melting and casting techniques on the mechanical strength and stereometric surface properties. The results revealed that the quality of Remanium CSe dental alloys significantly depend on the method of the material processing.

  12. The effect of tensile stress on hydrogen diffusion in metal alloys

    Science.gov (United States)

    Danford, M. D.

    1992-01-01

    The effect of tensile stress on hydrogen diffusion has been determined for Type 303 stainless steel, A286 CRES, and Waspaloy and IN100 nickel-base alloys. It was found that hydrogen diffusion coefficients are not significantly affected by stress, while the hydrogen permeabilities are greatly affected in Type 303 stainless steel and A286 CRES (iron-based alloys), but are affected little in Waspaloy (nickel-base) and not affected in all in IN100 (nickel base). These observations might be taken as an indication that hydrogen permeabilities are affected by stress in iron-based alloys, but only slightly affected in nickel-based alloys. However, it is too early to make such a generalization based on the study of only these four alloys.

  13. Interstitial-carbon-related defects in relaxed SiGe alloy: the effect of alloying

    Science.gov (United States)

    Mesli, A.; Nylandsted Larsen, A.

    2005-06-01

    Ci and CiCs are two main defects produced via the Watkins replacement mechanism when Si-based materials containing carbon are subjected to particle irradiation. In the present article we re-examine our experimental observations reported on these defects in relaxed Si1-xGex alloy layers in the light of very recent and thorough theoretical investigations (Venezuela et al 2004 Phys. Rev. B 69 115209 and Balsas et al 2004 Phys. Rev. B 70 085201). In addressing these defects two main issues are taken up. Firstly, the role of alloying upon the position of the electrical levels in the bandgap is considered: a linear shift towards the valence band with the same rate of all related levels is observed experimentally and predicted theoretically. Secondly, the dynamics of migration of interstitial carbon (Ci) in the process of forming CiCs is analysed. Our suggestion that Ci migrates via Si-based paths has now found theoretical justification.

  14. Effect of Mg, Si and Cu content on the microstructure of dilute 6000 series aluminium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Jaafar, Aiza, E-mail: cnaizza@gmail.com [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Rahmat, Azmi [School of Materials Engineering, Universiti Malaysia Perlis, Taman Muhibah, 02600 Jejawi, Arau Perlis (Malaysia); Hussain, Zuhailawati [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Zainol, Ismail [Chemistry Department, Faculty of Science and Mathematics, Universiti Pendidikan Sultan Idris, 35900 Tanjung Malim, Perak (Malaysia)

    2011-09-01

    Highlights: > The main precipitates formed in the artificially aged dilute alloys are needle-shaped. > The ageing temperature of 100 deg. C is found to be too low to form precipitates. > The number density of precipitates increases with increasing solute contents. > There is a correlation between Mg{sub 2}Si, Si and Cu content and alloys microstructure. > The precipitates kinetics is faster in the less dilute alloys. - Abstract: The effect of Mg, Si and Cu content on the microstructural development during ageing treatment of dilute 6000 series alloys have been investigated using transmission electron microscopy (TEM). Four dilute alloys were used in this study. These alloys were subjected to quenching and artificial ageing at 100 deg. C, 185 deg. C and 300 deg. C. The microstructural developments of the precipitates formed were monitored by TEM. The ageing temperature of 100 deg. C was found to be too low to form precipitates. It was found that needle or rod-shaped precipitates were formed in the alloys after ageing at 185 and 300 deg. C. Prolong ageing up to 1000 h at 300 deg. C resulted in the formation of Mg{sub 2}Si precipitate that coexists with the type of AlFeSi and Si precipitates. The results show a correlation between the Mg{sub 2}Si, Si and Cu content on the microstructure of the four dilute alloys after ageing treatment.

  15. Effect of Mg, Si and Cu content on the microstructure of dilute 6000 series aluminium alloys

    International Nuclear Information System (INIS)

    Jaafar, Aiza; Rahmat, Azmi; Hussain, Zuhailawati; Zainol, Ismail

    2011-01-01

    Highlights: → The main precipitates formed in the artificially aged dilute alloys are needle-shaped. → The ageing temperature of 100 deg. C is found to be too low to form precipitates. → The number density of precipitates increases with increasing solute contents. → There is a correlation between Mg 2 Si, Si and Cu content and alloys microstructure. → The precipitates kinetics is faster in the less dilute alloys. - Abstract: The effect of Mg, Si and Cu content on the microstructural development during ageing treatment of dilute 6000 series alloys have been investigated using transmission electron microscopy (TEM). Four dilute alloys were used in this study. These alloys were subjected to quenching and artificial ageing at 100 deg. C, 185 deg. C and 300 deg. C. The microstructural developments of the precipitates formed were monitored by TEM. The ageing temperature of 100 deg. C was found to be too low to form precipitates. It was found that needle or rod-shaped precipitates were formed in the alloys after ageing at 185 and 300 deg. C. Prolong ageing up to 1000 h at 300 deg. C resulted in the formation of Mg 2 Si precipitate that coexists with the type of AlFeSi and Si precipitates. The results show a correlation between the Mg 2 Si, Si and Cu content on the microstructure of the four dilute alloys after ageing treatment.

  16. Inhibitory effect of Ti-Ag alloy on artificial biofilm formation.

    Science.gov (United States)

    Nakajo, Kazuko; Takahashi, Masatoshi; Kikuchi, Masafumi; Takada, Yukyo; Okuno, Osamu; Sasaki, Keiichi; Takahashi, Nobuhiro

    2014-01-01

    Titanium-silver (Ti-Ag) alloy has been improved for machinability and mechanical properties, but its anti-biofilm properties have not been elucidated yet. Thus, this study aimed to evaluate the effects of Ti-Ag alloy on biofilm formation and bacterial viability in comparison with pure Ti, pure Ag and silver-palladium (Ag-Pd) alloy. Biofilm formation on the metal plates was evaluated by growing Streptococcus mutans and Streptococcus sobrinus in the presence of metal plates. Bactericidal activity was evaluated using a film contact method. There were no significant differences in biofilm formation between pure Ti, pure Ag and Ag-Pd alloy, while biofilm amounts on Ti-20% Ag and Ti-25% Ag alloys were significantly lower (p<0.05). In addition, Ti-Ag alloys and pure Ti were not bactericidal, although pure Ag and Ag-Pd alloy killed bacteria. These results suggest that Ti-20% Ag and Ti-25% Ag alloys are suitable for dental material that suppresses biofilm formation without disturbing healthy oral microflora.

  17. Effect of temperature variation on the cytotoxicity of cast dental alloys and commercially pure titanium.

    Science.gov (United States)

    Faria, Adriana Cláudia Lapria; Rodrigues, Renata Cristina Silveira; Antunes, Rossana Pereira de Almeida; de Mattos, Maria da Gloria Chiarello; Rosa, Adalberto Luiz; Ribeiro, Ricardo Faria

    2009-01-01

    Cell culture system has been used to evaluate alloy cytotoxicity under different environments, testing the extracts, but the effect of temperature variation on the cytotoxicity of dental alloys has not been analyzed. The aim of the present study was to investigate if temperature variation could affect dental alloy cytotoxicity, testing alloy extracts in an epithelial cell culture system. Discs of Ni-Cr, Co-Cr-Mo, Ni-Cr-Ti, Ti-6Al-4V and commercially pure titanium (cp Ti) were cast by arc melting, under argon atmosphere, injected by vacuum-pressure. Discs were immersed in artificial saliva and subjected to different temperatures: 37 degrees C and thermocycling (37 degrees C/5 degrees C/37 degrees C/55 degrees C/37 degrees C). After thermocycling, extracts were put in a subconfluent culture during 6 h, and the number of cells and their viability were used to evaluate cytotoxicity in these temperatures. For each alloy, data from temperature conditions were compared by Student's t-test (alpha=0.05). The cytotoxicity tests with alloy/metal extracts showed that Ni-Cr, Co-Cr-Mo, Ti-6Al-4V and cp Ti extracts (p>0.05) did not affect cell number or cell viability, while Ni-Cr-Ti (palloy was subjected to thermocycling. Within the limitations of the present study, the Ni-Cr-Ti alloy had cell number and viability decreased when subjected to temperature variation, while the other alloys/metal extracts did not show these results.

  18. Size effects in band gap bowing in nitride semiconducting alloys

    DEFF Research Database (Denmark)

    Gorczyca, I.; Suski, T.; Christensen, Niels Egede

    2011-01-01

    Chemical and size contributions to the band gap bowing of nitride semiconducting alloys (InxGa1-xN, InxAl1-xN, and AlxGa1-xN) are analyzed. It is shown that the band gap deformation potentials of the binary constituents determine the gap bowing in the ternary alloys. The particularly large gap bo...... bowing in In-containing nitride alloys can be explained by specific properties of InN, which do not follow trends observed in several other binaries....

  19. Effect of heat treatment on the microstructures and damping properties of biomedical Mg-Zr alloy

    International Nuclear Information System (INIS)

    Tsai, Ming-Hung; Chen, May-Show; Lin, Ling-Hung; Lin, Ming-Hong; Wu, Ching-Zong; Ou, Keng-Liang; Yu, Chih-Hua

    2011-01-01

    Research highlights: → When the as-quenched Mg-1Zr alloy was aged at temperatures ranging from 200 deg. C to 500 deg. C, a microstructural transformation sequence was found to be α-Mg → (α-Mg + twin dense ) → (α-Mg + twin loose ) → (α-Mg + α-Zr). → As the as-quenched Mg-1Zr alloy was subjected to aging treatment at 300 deg. C for 16 h, it exhibited the maximum damping properties. → The twin structure plays a crucial role in increasing the damping capacity of the Mg-1Zr alloy. - Abstract: In this study, we elucidated the effect of heat treatment on the microstructures and damping properties of the biomedical Mg-1 wt% Zr (K1) alloy by optical microscopy, transmission electron microscopy, energy-dispersive X-ray spectrometry, and experimental model analysis. The following microstructural transformation occurred when the as-quenched (AQ, i.e., solution heat treated and quenched) K1 alloy was subjected to aging treatment in the temperature range 200-500 deg. C: α-Mg → (α-Mg + twin dense ) → (α-Mg + twin loose ) → (α-Mg + α-Zr). This microstructural transformation was accompanied by variations in the damping capacity. The damping properties of the AQ K1 alloy subjected to aging treatment at 300 deg. C for 16 h were the best among those of the alloys investigated in the present study. The presence of twin structures in the alloy matrix was thought to play a crucial role in increasing the damping capacity of the K1 alloy. Hence, we state that a combination of solution treatment and aging is an effective means of improving the damping capacity of biomedical K1 alloys.

  20. Effect of heat treatment on the microstructures and damping properties of biomedical Mg-Zr alloy

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Ming-Hung [Department of Mechanical Engineering and Graduate Institute of Mechanical and Precision Engineering, National Kaoshiung University of Applied Sciences, Kaoshiung 807, Taiwan (China); Department of Dentistry, Chang Yin dental clinic, No.46-1, Yangming St., Banqiao City, Taipei County 220, Taiwan (China); Research Center for Biomedical Devices, Taipei Medical University, Taipei 110, Taiwan (China); Chen, May-Show [Research Center for Biomedical Devices, Taipei Medical University, Taipei 110, Taiwan (China); School of Oral Hygiene, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China); Department of Dentistry, Taipei Medical University Hospital, Taipei 110, Taiwan (China); Lin, Ling-Hung [Department of Dentistry, Taipei Medical University Hospital, Taipei 110, Taiwan (China); School of Dentistry, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China); Lin, Ming-Hong [Department of Mechanical Engineering and Graduate Institute of Mechanical and Precision Engineering, National Kaoshiung University of Applied Sciences, Kaoshiung 807, Taiwan (China); Wu, Ching-Zong, E-mail: chinaowu@tmu.edu.tw [Department of Dentistry, Taipei Medical University Hospital, Taipei 110, Taiwan (China); School of Dentistry, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China); Ou, Keng-Liang, E-mail: klou@tmu.edu.tw [Research Center for Biomedical Devices, Taipei Medical University, Taipei 110, Taiwan (China); Graduated Institute of Biomedical Materials and Engineering, Taipei Medical University, Taipei 110, Taiwan (China); Research Center for Biomedical Implants and Microsurgery Devices, Taipei Medical University, Taipei 110, Taiwan (China); Yu, Chih-Hua [Research Center for Biomedical Devices, Taipei Medical University, Taipei 110, Taiwan (China); Research Center for Biomedical Implants and Microsurgery Devices, Taipei Medical University, Taipei 110, Taiwan (China)

    2011-01-21

    Research highlights: > When the as-quenched Mg-1Zr alloy was aged at temperatures ranging from 200 deg. C to 500 deg. C, a microstructural transformation sequence was found to be {alpha}-Mg {yields} ({alpha}-Mg + twin{sub dense}) {yields} ({alpha}-Mg + twin{sub loose}) {yields} ({alpha}-Mg + {alpha}-Zr). > As the as-quenched Mg-1Zr alloy was subjected to aging treatment at 300 deg. C for 16 h, it exhibited the maximum damping properties. > The twin structure plays a crucial role in increasing the damping capacity of the Mg-1Zr alloy. - Abstract: In this study, we elucidated the effect of heat treatment on the microstructures and damping properties of the biomedical Mg-1 wt% Zr (K1) alloy by optical microscopy, transmission electron microscopy, energy-dispersive X-ray spectrometry, and experimental model analysis. The following microstructural transformation occurred when the as-quenched (AQ, i.e., solution heat treated and quenched) K1 alloy was subjected to aging treatment in the temperature range 200-500 deg. C: {alpha}-Mg {yields} ({alpha}-Mg + twin{sub dense}) {yields} ({alpha}-Mg + twin{sub loose}) {yields} ({alpha}-Mg + {alpha}-Zr). This microstructural transformation was accompanied by variations in the damping capacity. The damping properties of the AQ K1 alloy subjected to aging treatment at 300 deg. C for 16 h were the best among those of the alloys investigated in the present study. The presence of twin structures in the alloy matrix was thought to play a crucial role in increasing the damping capacity of the K1 alloy. Hence, we state that a combination of solution treatment and aging is an effective means of improving the damping capacity of biomedical K1 alloys.

  1. Effect of alumina air-abrasion on mechanical bonding between an acrylic resin and casting alloys.

    Science.gov (United States)

    Ishii, Takaya; Koizumi, Hiroyasu; Tanoue, Naomi; Naito, Koji; Yamashita, Miyuki; Matsumura, Hideo

    2009-06-01

    This study examined the effect of alumina air-abrasion with different pressure on bonding between an acrylic resin and casting alloys. Disk specimens (8 and 10 mm in diameter) were cast from a silver-palladium-copper-gold (Ag-Pd-Cu-Au, Castwell M.C.12) alloy and a titanium-aluminum-niobium alloy (Ti-6Al-7Nb, T-Alloy Tough). The disks were air-abraded with alumina particles (50-70 microm) under different air-pressures (0 unabraded, 0.1, and 0.6 MPa). The disk pairs were bonded together with a tri-n-butylborane (TBB)-initiated acrylic resin, and shear bond strengths were determined both before and after thermocycling. Bond strength varied from a maximum of 37.1 MPa to a minimum of 3.6 MPa for the Ag-Pd-Cu-Au alloy, whereas bond strength to Ti-6Al-7Nb alloy ranged from 34.7 MPa to 0.1 MPa. Specimens abraded with 0.6 MPa pressure recorded the greatest post-thermocycling bond strength (21.7 MPa and 17.9 MPa), and unabraded specimens showed the lowest strength (3.6 MPa and 0.1 MPa) for both alloys. Post-thermocycling bond strength to the Ag-Pd-Cu-Au alloy was higher than that to the Ti-6Al-7Nb alloy under identical air-abrading conditions. It can be concluded that alumina air-abrasion with an air-pressure of 0.6 MPa is effective in enhancing retentive characteristics of the TBB-initiated resin joined to the alloys.

  2. Effect of Fe-Content on the Mechanical Properties of Recycled Al Alloys during Hot Compression

    Directory of Open Access Journals (Sweden)

    Hongzhou Lu

    2017-07-01

    Full Text Available It is unavoidable that Fe impurities will be mixed into Al alloys during recycling of automotive aluminum parts, and the Fe content has a significant effect on the mechanical properties of the recycled Al alloys. In this work, hot compression tests of two Fe-containing Al alloys were carried out at elevated temperatures within a wide strain rate range from 0.01 s−1 to 10 s−1. The effect of Fe content on the peak stress of the stress vs. strain curves, strain rate sensitivity and activation energy for dynamic recrystallization are analyzed. Results show that the recycled Al alloy containing 0.5 wt % Fe exhibits higher peak stresses and larger activation energy than the recycled Al alloy containing 0.1 wt % Fe, which results from the fact that there are more dispersed AlMgFeSi and/or AlFeSi precipitates in the recycled Al alloy containing 0.5 wt % Fe as confirmed by SEM observation and energy spectrum analysis. It is also shown that the Fe content has little effect on the strain rate sensitivity of the recycled Al alloys.

  3. Effect of thermal cycling on change of titanium alloy properties

    International Nuclear Information System (INIS)

    Anufriev, V.P.; Bogachev, I.N.; Veksler, Yu.G.

    1980-01-01

    Investigated are the change of mechanical and physical properties of VT1-0, VT3-1 and VT-16 alloys, as well as resistances of their thermal fatigue under thermocycling (TC). It is shown that mechanical properties of the investigated alloys increase in the result of thermocycling. Maximum of the strength characteristics is obtained at 10 cycles on fine-grained alloys after TC. Maximum of strength and hardness on the samples with coarse grain is described and is shifted towards the lower number of cycles. VT1-0, VT3-1 and VT-16 alloys have high resistant ability against thermal fatigue in themocycling with maximal cycle temperature below recrystallization threshold

  4. [Effects of different dental alloys on cytotoxic and apoptosis related genes expression of mouse fibroblast cells L929].

    Science.gov (United States)

    Meng, He; Han, Dong; Zhan, De-Song

    2009-08-01

    To investigate effects of the leaching liquids of 5 different kinds of dental alloys on L929 cells at cell level and molecular level. The fibroblast L929 cells of mouse were cultivated in vitro in leaching liquids of 5 different kinds of dental alloys, Au alloy (n = 8), Ag-Pt alloy (n = 8), Co-Cr alloy (n = 8), Ni-Cr alloy (n = 8), and Cu alloy (n = 8). The RPMI 1640 cell medium containing 10% fetal beef serum was used as control. The cytotoxicities of the 5 dental alloys were evaluated by means of methyl thiazolyl tetrazolium (MTT), and the effects of these alloys on the expression of caspase-3, caspase-8, and caspase-9 mRNA of L929 cells were examined using reverse transcription polymerase chain reaction (RT-PCR) method. After 48 hours culture the cytotoxicity of Cu alloy group was in Grade 4 and those of the other groups were all in Grade 0. The mRNA levels of caspase-8 had no change in all groups (P > 0.05). The mRNA levels of caspase-3 were as follows: Cu alloy (0.474 +/- 0.001), the negative control (0.527 +/- 0.003), Au alloy (0.528 +/- 0.013), Co-Cr alloy (0.615 +/- 0.007), Ag-Pd alloy (0.673 +/- 0.009), and Ni-Cr alloy (0.803 +/- 0.037). The mRNA levels of caspase-9 were as follows: Cu alloy (0.532 +/- 0.041), Au alloy (0.574 +/- 0.013), the negative control (0.578 +/- 0.010), Co-Cr alloy (0.617 +/- 0.009), Ag-Pd alloy (0.703 +/- 0.018), and Ni-Cr alloy (0.811 +/- 0.037). There were significant differences between the groups except the negative control group and Au alloy group. The Cu alloy shows the highest cytotoxicity, and the leaching liquids of 5 different kinds of dental alloys may induce cell apoptosis through mitochondrion pathway.

  5. Effects of alloying elements on the kinetics of austenitization from pearlite in Fe-C-M alloys

    Science.gov (United States)

    Xia, Yuan; Enomoto, Masato; Yang, Zhigang; Li, Zhaodong; Zhang, Chi

    2013-03-01

    The effects of alloying elements on the kinetics of austenitization from pearlite structure were studied by computer simulation in Fe-C-M ternary alloys, where M is Mn, Cr, Si or Ni, assuming local equilibrium conditions at all transformation interfaces. A thin austenite film was assumed to nucleate at ferrite/cementite interfaces and grow in one dimension. The existence of a partition to no-partition transition temperature (PNTT) was rationalized. Above the PNTT, the growth rate of austenite is governed by the difference in carbon activity between austenite/cementite and ferrite/austenite interfaces; a substitutional element influences the reaction rate by affecting carbon activity. Below the PNTT, redistribution of M is necessary. The PNTT increases with the concentration of all alloy elements except Ni, which has a large segregation tendency in austenite from both ferrite and cementite, as well as repulsive interaction with carbon. The amount of overheating at PNTT from Ae1 increases in the order Si (∼Ni), Mn and Cr, essentially in agreement with a recently reported experiment.

  6. The effects of reactive elements on the oxidation of alumina-forming iron-chromium-aluminium alloys at high temperature

    International Nuclear Information System (INIS)

    Deakin, J.; Prunier, V.; Wood, G.C.; Stott, F.H.

    1995-01-01

    A study is being undertaken into the influence of sulphur and reactive elements on the growth and adhesion of alumina scales on iron-chromium-base alloys during thermal cycling in air from 1300 C. A low-sulphur- (< 10 ppm) containing alloy has shown considerable improvements in scale adhesion compared with an alloy containing a higher concentration of sulphur. Additions of reactive elements to the low sulphur-containing alloy had little further effect on scale adhesion, although second-phase precipitates facilitated preferential inward growth of the scale and the development of a very irregular scale/alloy interface. All the alloys showed evidence for stress development during scale growth, but this was often relieved by flow of the weak alloy. Although not extensive, all the low sulphur-containing alloys exhibited some scale failure, involving both a decohesion, buckling and tensile cracking route and a shear cracking and wedging route. (orig.)

  7. Effects of alloy chemistry, cold work, and water chemistry on corrosion fatigue and stress corrosion cracking of nickel alloys and welds.

    Energy Technology Data Exchange (ETDEWEB)

    Chopra, O. K.; Soppet, W. K.; Shack, W. J.; Energy Technology

    2001-04-01

    Reactor vessel internal components made of nickel-base alloys are susceptible to environmentally assisted cracking (EAC). A better understanding of the causes and mechanisms of this cracking may permit less conservative estimates of damage accumulation and requirements on inspection intervals. The objective of this work is to evaluate and compare the resistance of Alloys 600 and 690 and their welds, such as Alloys 82, 182, 52, and 152, to EAC in simulated light water reactor environments. The existing crack growth rate (CGR) data for these alloys under cyclic and constant loads have been evaluated to establish the effects of alloy chemistry, cold work, and water chemistry. The experimental fatigue CGRs are compared with CGRs that would be expected in air under the same mechanical loading conditions to obtain a qualitative understanding of the degree and range of conditions for significant environmental enhancement in growth rates. The existing stress corrosion cracking (SCC) data on Alloys 600 and 690 and Alloy 82, 182, and 52 welds have been compiled and analyzed to determine the influence of key parameters on growth rates in simulated PWR and BWR environments. The SCC data for these alloys have been evaluated with correlations developed by Scott and by Ford and Andresen.

  8. Effects of scandium and zirconium combination alloying on as-cast microstructure and mechanical properties of Al-4Cu-1.5Mg alloy

    Directory of Open Access Journals (Sweden)

    Xiang Qingchun

    2011-02-01

    Full Text Available The influences of minor scandium and zirconium combination alloying on the as-cast microstructure and mechanical properties of Al-4Cu-1.5Mg alloy have been experimentally investigated. The experimental results show that when the minor elements of scandium and zirconium are simultaneously added into the Al-4Cu-1.5Mg alloy, the as-cast microstructure of the alloy is effectively modified and the grains of the alloy are greatly refined. The coarse dendrites in the microstructure of the alloy without Sc and Zr additions are refined to the uniform and fine equiaxed grains. As the additions of Sc and Zr are 0.4% and 0.2%, respectively, the tensile strength, yield strength and elongation of the alloy are relatively better, which are 275.0 MPa, 176.0 MPa and 8.0% respectively. The tensile strength is increased by 55.3%, and the elongation is nearly raised three times, compared with those of the alloy without Sc and Zr additions.

  9. Effect of the combination of dithiooctanoate monomers and acidic adhesive monomers on adhesion to precious metals, precious metal alloys and non-precious metal alloys.

    Science.gov (United States)

    Ikemura, Kunio; Kojima, Katsunori; Endo, Takeshi; Kadoma, Yoshinori

    2011-01-01

    This study investigated the effect of the combination of a dithiooctanoate monomer and an acidic adhesive monomer on adhesion to precious metals, precious and non-precious metal alloys. From a selection of four dithiooctanoate monomers and six acidic adhesive monomers, 14 experimental primers containing a combination of 5.0 wt% of a dithiooctanoate monomer and 1.0 wt% of an acidic adhesive monomer in acetone were prepared. Tensile bond strengths (TBSs) of MMA-PMMA/TBBO resin to nine kinds of precious metals, precious metal alloys, and non-precious metal alloys after 2,000 thermal cycles were measured. Results showed that there were no significant differences in TBS among the primers to all the precious and non-precious metal adherends tested (p>0.05). Highest TBS values (46.5-55.8 MPa) for bonding to Au alloy, Au-Ag-Pd alloy, Co-Cr alloy, and Ni-Cr alloy were achieved with the primer which contained 5.0 wt% 10-methacryloyloxydecyl 6,8-dithiooctanoate (10-MDDT) and 1.0 wt% 6-methacryloyloxyhexyl phosphonoacetate (6-MHPA). Therefore, 5.0 wt% 10-MDDT and 1.0 wt% 6-MHPA was determined as the optimal combination for bonding to precious metals, precious and non-precious metal alloys.

  10. Surface effect theory in binary alloys: surfaces with cut-off

    International Nuclear Information System (INIS)

    Kumar, V.; Silva, C.E.T.G. da; Moran-Lopez, J.L.

    1981-01-01

    A surface effect theory in binary alloys which ore ordered with surfaces with cut-off is presented. This theory is based in a model of pair interaction between first neighbours and includes long and short range effects. The (120) surface with sup(-) (110) monoatomic cut-off and terrace in the (110) planes of an alloy with body centered cubic structure is presented as example. Results for the concentrations in all the different surface sites are given. (L.C.) [pt

  11. Anomalous effect of small doses of ionizing radiation on metals and alloys

    International Nuclear Information System (INIS)

    Chernov, I.P.; Mamontov, A.P.; Botaki, A.A.; Cherdantsev, P.A.; Chakhlov, B.V.; Sharov, S.R.; Timoshnikov, Yu.A.; Filipenko, L.A.

    1986-01-01

    The effect of small doses of 60 Co gamma rays on copper, tungsten, and WCo alloys has been investigated. A decrease in the concentration of material defects under the influence of small doses of ionizing radiation was found. Also the structural rearrangement of the crystal was found to be still in progress after irradiation ceased. The mechanism of the anomalous effect of small doses of ionizing radiation on metals and alloys is discussed in terms of the electron energy scheme. (U.K.)

  12. Effects of Palladium Content, Quaternary Alloying, and Thermomechanical Processing on the Behavior of Ni-Ti-Pd Shape Memory Alloys for Actuator Applications

    Science.gov (United States)

    Bigelow, Glen

    2008-01-01

    The need for compact, solid-state actuation systems for use in the aerospace, automotive, and other transportation industries is currently driving research in high-temperature shape memory alloys (HTSMA) having transformation temperatures above 100 C. One of the basic high temperature systems under investigation to fill this need is NiTiPd. Prior work on this alloy system has focused on phase transformations and respective temperatures, no-load shape memory behavior (strain recovery), and tensile behavior for selected alloys. In addition, a few tests have been done to determine the effect of boron additions and thermomechanical treatment on the aforementioned properties. The main properties that affect the performance of a solid state actuator, namely work output, transformation strain, and permanent deformation during thermal cycling under load have mainly been neglected. There is also no consistent data representing the mechanical behavior of this alloy system over a broad range of compositions. For this thesis, ternary NiTiPd alloys containing 15 to 46 at.% palladium were processed and the transformation temperatures, basic tensile properties, and work characteristics determined. However, testing reveals that at higher levels of alloying addition, the benefit of increased transformation temperature begins to be offset by lowered work output and permanent deformation or "walking" of the alloy during thermal cycling under load. In response to this dilemma, NiTiPd alloys have been further alloyed with gold, platinum, and hafnium additions to solid solution strengthen the martensite and parent austenite phases in order to improve the thermomechanical behavior of these materials. The tensile properties, work behavior, and dimensional stability during repeated thermal cycling under load for the ternary and quaternary alloys were compared and discussed. In addition, the benefits of more advanced thermomechanical processing or training on the dimensional stability of

  13. Effect of Boron Doping on Cellular Discontinuous Precipitation for Age-Hardenable Cu–Ti Alloys

    Directory of Open Access Journals (Sweden)

    Satoshi Semboshi

    2015-06-01

    Full Text Available The effects of boron doping on the microstructural evolution and mechanical and electrical properties of age-hardenable Cu–4Ti (at.% alloys are investigated. In the quenched Cu–4Ti–0.03B (at.% alloy, elemental B (boron is preferentially segregated at the grain boundaries of the supersaturated solid-solution phase. The aging behavior of the B-doped alloy is mostly similar to that of conventional age-hardenable Cu–Ti alloys. In the early stage of aging at 450 °C, metastable β′-Cu4Ti with fine needle-shaped precipitates continuously form in the matrix phase. Cellular discontinuous precipitates composed of the stable β-Cu4Ti and solid-solution laminates are then formed and grown at the grain boundaries. However, the volume fraction of the discontinuous precipitates is lower in the Cu–4Ti–0.03B alloy than the Cu–4Ti alloy, particularly in the over-aging period of 72–120 h. The suppression of the formation of discontinuous precipitates eventually results in improvement of the hardness and tensile strength. It should be noted that minor B doping of Cu–Ti alloys also effectively enhances the elongation to fracture, which should be attributed to segregation of B at the grain boundaries.

  14. Effect of base metal alloys recasting on marginal integrity of castable crowns.

    Science.gov (United States)

    Bajoghli, Farshad; Nosouhian, Saeid; Badrian, Hamid; Goroohi, Hossein; Saberian, Amir; Gadesi, Leyla

    2013-03-01

    Base metals have a wide use in casting methods. Sometimes they are reused in laboratories which may have an adverse effect on the restoration marginal integrity. This study aimed to investigate the effect of recasting of alloys on marginal integrity of restorations. Models with two types of finishing lines shoulder bevel 45° and shoulder 135° were produced and 15 wax copings were formed on each one of them. Each group containing 15 copings was divided into three subgroups A, B and C. Group A was casted with 100% new alloy, group B with 50% new and 50% recasted alloy and group C with 100% recasted alloy. Obtained metal copings were placed on dies and marginal gap size between restoration margin and the dies finishing line was measured using metric microscope and Moticam camera in four points, buccal, lingual, mesial and distal. A significant difference in mean marginal gap size exists among three types of alloys used (p-value = 0.036). A significant difference is observed between mean marginal gap size of two types of finishing lines for different alloys (p-value = 0.001). Using 100% recasted alloy is not recommended for any of the two types of finishing lines.

  15. Effect of Repeated Firings of Porcelain on Bond Strength of Two Base Metal Alloys

    Directory of Open Access Journals (Sweden)

    Gerami Panah F

    2001-05-01

    Full Text Available The formation of oxides on the surface of the metal are proven to contribute to the formation of strong bonding. However, The base metal alloys are expected to exhibit more oxidation than high gold alloys, increase in oxide layer thickness due to repeated firing in them can reduce the bond strength. The aim of this study was to compare the effect of repeated porcelain firing on the bond strength of two base metal alloys (Minalux and Verabond II. Sixteen metal plates (20x5x0.5 from each alloy were cast and prepared according to the manufacturers' instruction. Porcelain with uniform thickness (Imm was applied on the middle one third of metal plates. After this stage, each alloy group divided to three subgroups. Group I was fired for the second time to form the final glaze, group II and III were fired two and four more times respectively. Specimens were subjected to 3-point flexural test in a digital tritest machine. Results showed no significant differences between bond strength of two alloys. Also results showed repeated firing had no significant effect on bond strength. Due to these findings, this study support similarity of two alloys (Minalux and Verabond II in their bond strength with porcelain.

  16. Effects of Yb on the mechanical properties and microstructures of an Al-Mg alloy

    International Nuclear Information System (INIS)

    Song Min; Wu Zhenggang; He Yuehui

    2008-01-01

    This paper reported a first study of the effects of Yb on the microstructures and mechanical properties of an extruded Al-Mg alloy. It has been shown that the addition of 0.3 wt.% Yb decreases the mechanical properties of the alloy since Mg- and Yb-containing constituents decrease the concentration of Mg solute atoms in Al matrix, and thus the solution strengthening effect. However, the addition of 1 wt.% Yb substantially improves the mechanical behavior of the alloy because the concentration of Yb solute atoms in Al matrix is high enough to generate solution strengthening effect. The improvement in the mechanical properties is due to the large work-hardening and high dislocation density caused by the interaction between dislocations and Yb and Mg solute atoms. The Yb and Mg atoms inhibit the dynamic recovery and recrystallization of the alloy, thus provide a uniformly distributed dislocation structure with high density

  17. Effect of high power ultrasound on mechanical properties of Al-Si alloys

    Science.gov (United States)

    Srivastava, N.; Gupta, R.; Chaudhari, G. P.

    2018-03-01

    Effect of high power ultrasonic treatment on the solidification microstructures of Al-Si alloys containing varying content of solute Si (1, 2, 3 and 5 wt %) is investigated. Large variation in microstructures is seen and refinement of primary α-Al grains is observed. It is observed that increasing the weight percentage of solute along with ultrasonic treatment resulted in finer primary phase. By increasing the solute content from 1% to 5 wt.% in Al-Si alloys, hardness increased by about 38% without and 48% with ultrasonic treatment. Tensile strength of the alloys with ultrasonic treatment is higher as compared to those without ultrasonic treated.

  18. Shape memory effect and superelasticity of titanium nickelide alloys implanted with high ion doses

    International Nuclear Information System (INIS)

    Pogrebnjak, A D; Bratushka, S N; Beresnev, V M; Levintant-Zayonts, N

    2013-01-01

    The state of the art in ion implantation of superelastic NiTi shape memory alloys is analyzed. Various technological applications of the shape memory effect are outlined. The principles and techiques of ion implantation are described. Specific features of its application for modification of surface layers in surface engineering are considered. Key properties of shape memory alloys and problems in utilization of ion implantation to improve the surface properties of shape memory alloys, such as corrosion resistance, friction coefficient, wear resistance, etc. are discussed. The bibliography includes 162 references

  19. Pressure effects on Al89La6Ni5 amorphous alloy crystallization

    DEFF Research Database (Denmark)

    Zhuang, Yanxin; Jiang, Jianzhong; Zhou, T. J.

    2000-01-01

    The pressure effect on the crystallization of the Al89La6Ni5 amorphous alloy has been investigated by in situ high-pressure and high-temperature x-ray powder diffraction using synchrotron radiation. The amorphous alloy crystallizes in two steps in the pressure range studied (0-4 GPa). The first......(s). The applied pressure strongly affects the crystallization processes of the amorphous alloy. Both temperatures first decrease with pressure in the pressure range of 0-1 GPa and then increase with pressure up to 4 GPa. The results are discussed with reference to competing processes between the thermodynamic...

  20. The effects of. gamma. -irradiation on Ti-Ni shape-memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Guilin; Xu Feng; Liu Wenhong; Hu Wenxiang; Yu Fanghua; Zhang Yiping (Academia Sinica, Shanghai, SH (China). Shanghai Inst. of Nuclear Research); Wang Jingcheng; Shao Zichang (Shanghai Iron and Steel Research Inst, SH (China))

    1992-04-01

    Because gamma irradiation provides a means of introducing lattice defects into crystalline solids in a controlled fashion, it can be used to study the influence of lattice defects on the physical properties of solids such as shape-memory alloys (SMAs). The study described here shows that gamma irradiation can be used to ameliorate the performance of SMAs and to understand the mechanism of the shape memory further in these alloys. In particular it shows the effect of gamma irradiation on the martensitic transformation temperatures of Ti-Ni alloys. (UK).

  1. Effect of elastic interphase strains on extinction in aging nimonic type alloys

    International Nuclear Information System (INIS)

    Gitgarts, M.I.; Ivashin, V.V.

    1977-01-01

    The effect of νsup(')-phase separation processes on the variation of (3) CuKsub(α) diffraction line integral intensity in KhN67VMTYu alloy ageing has been investigated, the alloy being characterized by various degrees of volumetric inconsistency between the separation phase and matrix. The ageing of KhN67VMTYu alloy, in which the separation of the νsup(')-phase does not cause interphase strains, is not accompanied by abatement of extinction: the diffraction line intensity is practically the same for both aged and tempered specimens

  2. Degradation of bioabsorbable Mg-based alloys: Assessment of the effects of insoluble corrosion products and joint effects of alloying components on mammalian cells.

    Science.gov (United States)

    Grillo, Claudia A; Alvarez, Florencia; Fernández Lorenzo de Mele, Mónica A

    2016-01-01

    This work is focused on the processes occurring at the bioabsorbable metallic biomaterial/cell interfaces that may lead to toxicity. A critical analysis of the results obtained when degradable metal disks (pure Mg and rare earth-containing alloys (ZEK100 alloys)) are in direct contact with cell culture and those obtained with indirect methods such as the use of metal salts and extracts was made. Viability was assessed by Acridine Orange dye, neutral red and clonogenic assays. The effects of concentration of corrosion products and possible joint effects of the binary and ternary combinations of La, Zn and Mg ions, as constituents of ZEK alloys, were evaluated on a mammalian cell culture. In all cases more detrimental effects were found for pure Mg than for the alloys. Experiments with disks showed that gradual alterations in pH and in the amount of corrosion products were better tolerated by cells and resulted in higher viability than abrupt changes. In addition, viability was dependent on the distance from the source of ions. Experiments with extracts showed that the effect of insoluble degradation products was highly detrimental. Indirect tests with Zn ions revealed that harmful effects may be found at concentrations ≥ 150 μM and at ≥ 100 μM in mixtures with Mg. These mixtures lead to more deleterious effects than single ions. Results highlight the need to develop a battery of tests to evaluate the biocompatibility of bioabsorbable biomaterials. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Interstitial-carbon-related defects in relaxed SiGe alloy: the effect of alloying

    International Nuclear Information System (INIS)

    Mesli, A; Larsen, A Nylandsted

    2005-01-01

    C i and C i C s are two main defects produced via the Watkins replacement mechanism when Si-based materials containing carbon are subjected to particle irradiation. In the present article we re-examine our experimental observations reported on these defects in relaxed Si 1-x Ge x alloy layers in the light of very recent and thorough theoretical investigations (Venezuela et al 2004 Phys. Rev. B 69 115209 and Balsas et al 2004 Phys. Rev. B 70 085201). In addressing these defects two main issues are taken up. Firstly, the role of alloying upon the position of the electrical levels in the bandgap is considered: a linear shift towards the valence band with the same rate of all related levels is observed experimentally and predicted theoretically. Secondly, the dynamics of migration of interstitial carbon (C i ) in the process of forming C i C s is analysed. Our suggestion that C i migrates via Si-based paths has now found theoretical justification

  4. Effect of carbonitride precipitates on the abrasive wear behaviour of hardfacing alloy

    International Nuclear Information System (INIS)

    Yang Ke; Yu Shengfu; Li Yingbin; Li Chenglin

    2008-01-01

    Hardfacing alloy of martensitic stainless steel expect higher abradability to be achieved through the addition of nitrogen being provided by the fine scale precipitation of complex carbonitride particles. Niobium and titanium as the most effective carbonitride alloying elements were added in the Fe-Cr13-Mn-N hardfacing alloy to get carbonitride precipitates. Carbonitride was systematically studied by optical microscopy, scanning electronic microscopy and energy spectrum analysis. Abrasive wear resistance of hardfacing alloy in as-welded and heat-treated conditions was tested by using the belt abrasion test apparatus where the samples slide against the abrasive belt. It is found that carbonitride particles in the hardfacing alloy are complex of Cr, Ti and Nb distributing on the grain boundary or matrix of the hardfacing alloy with different number and size in as-welded and heat-treated conditions. A large number of carbonitrides can be precipitated with very fine size (nanoscale) after heat treatment. As a result, the homogeneous distribution of very fine carbonitride particles can significantly improve the grain-abrasion wear-resisting property of the hardfacing alloy, and the mass loss is plastic deformation with minimum depth of grooving by abrasive particles and fine delamination

  5. The Effect of Grain Size on the Strain Hardening Behavior for Extruded ZK61 Magnesium Alloy

    Science.gov (United States)

    Zhang, Lixin; Zhang, Wencong; Chen, Wenzhen; Duan, Junpeng; Wang, Wenke; Wang, Erde

    2017-12-01

    The effects of grain size on the tensile and compressive strain hardening behaviors for extruded ZK61 alloys have been investigated by uniaxial tensile and compressive tests along the extrusion directions. Cylindrical tension and compression specimens of extruded ZK61 alloys with various sized grain were fabricated by annealing treatments. Tensile and compressive tests at ambient temperature were conducted at a strain rate of 0.5 × 10-3 s-1. The results indicate that both tensile strain hardening and compressive strain hardening of ZK61 alloys with different grain sizes have an athermal regime of dislocation accumulation in early deformation. The threshold stress value caused dynamic recovery is predominantly related to grain size in tensile strain hardening, but the threshold stress values for different grain sizes are almost identical in compressive strain hardening. There are obvious transition points on the tensile strain hardening curves which indicate the occurrence of dynamic recrystallization (DRX). The tensile strain hardening rate of the coarse-grained alloy obviously decreases faster than that of fine-grained alloys before DRX and the tensile strain hardening curves of different grain sizes basically tend to parallel after DRX. The compressive strain hardening rate of the fine-grained alloy obviously increases faster than that of coarse-grained alloy for twin-induced strain hardening, but compressive strain hardening curves also tend to parallel after twinning is exhausted.

  6. Fractal study of Ni-Cr-Mo alloy for dental applications: effect of beryllium

    Energy Technology Data Exchange (ETDEWEB)

    Eftekhari, Ali

    2003-12-30

    Different Ni-based alloys with various compositions were prepared by varying the amounts of beryllium. Effect of the amount of beryllium added to the alloy on its corrosion in an electrolyte solution of artificial saliva was investigated. Fractal dimension was used as a quantitative factor for surface analysis of the alloys before and after storage in the artificial salvia. The fractal dimensions of the electrode surfaces were determined by means of the most reliable method in this context viz. time dependency of the diffusion-limited current for a system involving 'diffusion towards electrode surface'. The results showed that increase of the beryllium amount in the alloy composition significantly increases the alloy corrosion. It is accompanied by increase of the fractal dimension and roughness of the electrode surface, whereas a smooth and shiny surface is required for dentures. From the methodology point of view, the approach utilized for fractal analysis of the alloy surfaces (Au-masking of metallic surfaces) is a novel and efficient method for study of denture surfaces. Generally, this approach is of interest for corrosion studies of different metals and alloys, particularly where changes in surface structure have a significant importance.

  7. Effect of grain refinement on the fluidity of two commercial Al-Si foundry alloys

    Science.gov (United States)

    Dahle, A. K.; Tøndel, P. A.; Paradies, C. J.; Arnberg, L.

    1996-08-01

    The effect of grain refinement on the fluidity of AlSi7Mg and AlSi11Mg has been investigated by spiral tests. Two different types of grain refiners have been evaluated. An AlTi5Bl master alloy was added to different Ti contents. Since the commercial alloys had a high initial content of titanium, model alloys were made to investigate the fluidity at low grain refiner additions. Commercial alloys grain refined only by boron additions have also been investigated. The results from the fluidity measurements have been verified by measuring the dendrite coherency point of the different cast alloys. Although different, the two methods show similar trends. The spirals from each fraction grain refiner cast were subsequently investigated metallographically at the tip of the spirals and at a reference point a distance behind, but no obvious difference in structure was observed. For both alloys, an increase in fluidity is observed as the content of grain refiner increases above 0.12 pct Ti, while the fluidity is impaired with increased grain refinement below 0.12 pct Ti. The alloys grain refined with ~0.015 pct B show the highest fraction solid at dendrite coherency, the smallest grain size, and the best fluidity.

  8. Effect of Manufacturing Process on the Biocompatibility and Mechanical Properties of Ti-30Ta Alloy

    Science.gov (United States)

    Gill, P.; Munroe, N.; Pulletikurthi, C.; Pandya, S.; Haider, W.

    2011-07-01

    Ti alloys have been widely used in the aerospace, chemical, and biomedical industries for their high strength/weight ratio and corrosion resistance. However, Nitinol's usage in the latter industry has been fraught with concerns of allergic and toxic effects of Ni released from implants. Recently, much attention has been placed on the development of Ni-free Ti-Ta alloys, which are considered prime candidates for applications such as metal-on-metal spinal disk replacements, orthopedic implants, cardiovascular stents, dental posts, and guide wires. In this research, the biocompatibility of Ti-30Ta alloys manufactured by powder metallurgy (PM) and arc melting (ARC) were investigated. The corrosion resistance of each alloy was determined in accordance with ASTM F 2129-08 in phosphate buffered saline (PBS) and PBS with amino acids at 37 °C. The concentration of metal ions released during corrosion was measured by Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). Scanning Electron Microscopy (SEM) was used to assess the morphology of the alloys before and after corrosion. Vicker's hardness tests were performed to compare the hardness and tensile strength of the alloys. Human osteoblast cells were successfully grown on the surface of both alloys.

  9. Fractal study of Ni Cr Mo alloy for dental applications: effect of beryllium

    Science.gov (United States)

    Eftekhari, Ali

    2003-12-01

    Different Ni-based alloys with various compositions were prepared by varying the amounts of beryllium. Effect of the amount of beryllium added to the alloy on its corrosion in an electrolyte solution of artificial saliva was investigated. Fractal dimension was used as a quantitative factor for surface analysis of the alloys before and after storage in the artificial salvia. The fractal dimensions of the electrode surfaces were determined by means of the most reliable method in this context viz. time dependency of the diffusion-limited current for a system involving "diffusion towards electrode surface". The results showed that increase of the beryllium amount in the alloy composition significantly increases the alloy corrosion. It is accompanied by increase of the fractal dimension and roughness of the electrode surface, whereas a smooth and shiny surface is required for dentures. From the methodology point of view, the approach utilized for fractal analysis of the alloy surfaces (Au-masking of metallic surfaces) is a novel and efficient method for study of denture surfaces. Generally, this approach is of interest for corrosion studies of different metals and alloys, particularly where changes in surface structure have a significant importance.

  10. Effect of mechanical vibrations on the wear behavior of AZ91 Mg alloy

    Science.gov (United States)

    Chaturvedi, V.; Pandel, U.; Sharma, A.

    2018-02-01

    AZ91 Mg alloy is the most promising alloy used for structural applications. The vibration induced methods are effective and economic viable in term of mechanical properties. Sliding wear tests were performed on AZ91 Mg alloy using a pin-on- disc configuration. Wear rates were measured at 5 N and 10N at a sliding velocity of 1m/s for varied frequency within the range of 5- 25Hz and a constant amplitude of 2mm. Microstructures of worn surfaces and wear debris were characterized by field emission scanning electron microscopy (FESEM). It is observed that wear resistance of vibrated AZ91 alloy at 15Hz frequency ad 2mm amplitude was superior than cast AZ91 Mg alloy. Finer grain size and equiaxed grain shape both are important parameters for better wear resistance in vibrated AZ91 Mg alloys. FESEM analysis revealed that wear is considerably affected due to frictional heat generated by the relative motion between AZ91 Mg alloy and EN31 steel surface. No single mechanism was responsible for material loss.

  11. Effects of Sm addition on electromagnetic interference shielding property of Mg-Zn-Zr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Chubin [Chongqing University, College of Materials Science and Engineering, National Engineering Research Center for Magnesium Alloy, Chongqing (China); Gannan Normal University, Jiangxi Provincial Engineering Research Center for Magnesium Alloy, Ganzhou (China); Pan, Fusheng; Chen, Xianhua [Chongqing University, College of Materials Science and Engineering, National Engineering Research Center for Magnesium Alloy, Chongqing (China); Luo, Ning [Gannan Normal University, Jiangxi Provincial Engineering Research Center for Magnesium Alloy, Ganzhou (China)

    2017-06-15

    The electromagnetic interference (EMI) shielding of Sm-containing magnesium alloys in the 30-1500 MHz testing frequency range was investigated by coaxial cable method. The results demonstrated that Mg-3Zn alloys displayed the best electromagnetic shielding property. When 0.5 wt% of Zr was added for crystal grain refinement, the shielding effectiveness (SE) was apparently reduced. The addition of the rare earth element Sm in ZK magnesium alloys can improve the electromagnetic interference shielding of magnesium alloys. The main reason for the differences in electromagnetic interference shielding of magnesium alloys was the change in conductivity. The addition of Zr in Mg-Zn alloys can refine the grains and consequently improve the grain boundary area significantly. Therefore, the number of irregularly arranged atoms at the grain boundaries increased, decreasing the conductivity of magnesium alloys and leading to a decrease in the electromagnetic interference shielding. Following the Sm addition, the Mg-Zn-Sm phase was precipitated at the grain boundaries and in cores. The precipitation of Sm-containing rare earth phases could consume the solid-soluted Zn atoms within the Mg, resulting in an increase in electrical conductivity and electromagnetic interference shielding improvement. (orig.)

  12. Superficial effects during the activation of zirconium AB2 alloys

    International Nuclear Information System (INIS)

    Zerbino, J; Visitin, A; Triaca, W

    2005-01-01

    The activation of zirconium nickel alloys with and without the addition of chromium and titanium is investigated through electrochemical and optical techniques.These alloys show high hydrogen absorption capacity and are extensively used in metal hydride batteries.Recent investigations in aqueous 1 M KOH indicate oxide layer growth and occlusion of hydrogen species in the alloys during the application of different cathodic potential programmes currently used in the activation process.In this research several techniques such as voltammetry, ellipsometry, energy dispersive analysis of X-rays EDAX, and scanning electron microscopy SEM are applied on the polished massive alloy Zr 1 -xTi x , x=0.36 y 0.43, and Zr 1 -xTi x CrNi, x=0.1,0.2 y 0.4.Data analysis shows that the stability, compactness and structure of the passive layers are strongly dependent on the applied potential programme.The alloy activation depends on the formation of deepen crevices that remain after a new polishing. Microscopic observation shows increase in the crevices thickness after the cathodic sweep potential cycling, which produces fragmentation of the grains and oxide growth during the activation process.This indicates metal breaking and intergranular dissolution that take place together with oxide and hydride formation.In some cases the resultant crevice thickness is one or two orders higher than that of the superficial oxide growth indicating intergranular localised corrosion

  13. Neutron irradiation effects on the mechanical properties of thorium and thorium--carbon alloy

    International Nuclear Information System (INIS)

    Wang, S.C.P.

    1978-04-01

    The effects of neutron exposure to 3.0 x 10 18 neutrons/cm 2 on the mechanical properties of thorium and thorium-carbon alloy are described. Tensile measurements were done at six different test temperatures from 4 0 K to 503 0 K and at two strain rates. Thorium and thorium-carbon alloy are shown to display typical radiation hardening like other face-centered cubic metals. The yield drop phenomenon of the thorium-carbon alloy is unchanged after irradiation. The variation of shear stress and effective shear stress with test temperature was fitted to Seeger's and Fleischer's equations for irradiated and unirradiated thorium and thorium-carbon alloy. Neutron irradiation apparently contributes an athermal component to the yield strength. However, some thermal component is detected in the low temperature range. Strain-rate parameter is increased and activation volume is decreased slightly for both kinds of metal after irradiation

  14. EFFECT OF SILICON CONTENT ON MACHINABILITY OF Al-Si ALLOYS

    Directory of Open Access Journals (Sweden)

    Birol Akyüz

    2016-09-01

    Full Text Available In this study the effect of the change in the amount of Silicon (Si occuring in Al-Si alloys on mechanical and machinability properties of the alloy was investigated. The change in mechanical properties and microstructure, which depends on the increase in Si percentage, and the effects of this change on Flank Build-up (FBU, wear on the cutting edge, surface roughness, and machinability were also studied. Alloys in different ratios of Si (i.e. 2 to 12 wt %, were employed in the study. The specimens for tests were obtained by casting into metal moulds. The results obtained from experimental studies indicate improved mechanical properties and machinability, depending on the rise in Si percentage in Al-Si alloys. It is also observed that the increase in Si percentage enhanced surface quality.

  15. Band shift of 2D transition-metal dichalcogenide alloys: size and composition effects

    Science.gov (United States)

    Zhao, Yipeng; Zhang, Zhe; Ouyang, Gang

    2018-04-01

    Band engineering of 2D transition-metal dichalcogenides (2D-TMDs) is a vital task for their applications in electronic and optoelectronic nanodevices. In this study, we investigate the joint effect from size and composition contributions on the band shift of 2D-TMD alloys in terms of atomic bond relaxation consideration. A theoretical model is proposed to pursue the underlying mechanism, which can connect the band offset with the atomic bonding identities in the 2D-TMD alloys. We reveal that the bandgap of 2D-TMD alloys presents a bowing shape owing to the size-dependent interaction among atoms and shows blue shift or red shift due to different intermixing of components. It is demonstrated that both size and composition can be performed as the useful methods to modulate the band shift, which suggests an effective way to realize the desirable properties of 2D-TMD alloys.

  16. Alloying effects on superionic conductivity in lithium indium halides for all-solid-state batteries

    Science.gov (United States)

    Zevgolis, Alysia; Wood, Brandon C.; Mehmedović, Zerina; Hall, Alex T.; Alves, Thomaz C.; Adelstein, Nicole

    2018-04-01

    Alloying of anions is a promising engineering strategy for tuning ionic conductivity in halide-based inorganic solid electrolytes. We explain the alloying effects in Li3InBr6-xClx, in terms of strain, chemistry, and microstructure, using first-principles molecular dynamics simulations and electronic structure analysis. We find that strain and bond chemistry can be tuned through alloying and affect the activation energy and maximum diffusivity coefficient. The similar conductivities of the x = 3 and x = 6 compositions can be understood by assuming that the alloy separates into Br-rich and Cl-rich regions. Phase-separation increases diffusivity at the interface and in the expanded Cl-region, suggesting microstructure effects are critical. Similarities with other halide superionic conductors are highlighted.

  17. Effect of temperature variation on the cytotoxicity of cast dental alloys and commercially pure titanium

    Directory of Open Access Journals (Sweden)

    Adriana Cláudia Lapria Faria

    2009-10-01

    Full Text Available Cell culture system has been used to evaluate alloy cytotoxicity under different environments, testing the extracts, but the effect of temperature variation on the cytotoxicity of dental alloys has not been analyzed. OBJECTIVE: The aim of the present study was to investigate if temperature variation could affect dental alloy cytotoxicity, testing alloy extracts in an epithelial cell culture system. MATERIAL AND METHODS: Discs of Ni-Cr, Co-Cr-Mo, Ni-Cr-Ti, Ti-6Al-4V and commercially pure titanium (cp Ti were cast by arc melting, under argon atmosphere, injected by vacuum-pressure. Discs were immersed in artificial saliva and subjected to different temperatures: 37ºC and thermocycling (37ºC/5ºC/37ºC/55ºC/37ºC. After thermocycling, extracts were put in a subconfluent culture during 6 h, and the number of cells and their viability were used to evaluate cytotoxicity in these temperatures. For each alloy, data from temperature conditions were compared by Student's t-test (α=0.05. RESULTS: The cytotoxicity tests with alloy/metal extracts showed that Ni-Cr, Co-Cr-Mo, Ti-6Al-4V and cp Ti extracts (p>0.05 did not affect cell number or cell viability, while Ni-Cr-Ti (p<0.05 extract decreased cell number and viability when the alloy was subjected to thermocycling. CONCLUSION: Within the limitations of the present study, the Ni-Cr-Ti alloy had cell number and viability decreased when subjected to temperature variation, while the other alloys/metal extracts did not show these results.

  18. The Effects of Chemical Wash Additives on the Corrosion of Aerospace Alloys in Marine Environments

    Science.gov (United States)

    MacDowell, Louis; Calle, Luz Marina; Curran, Joseph; Hodge, Tim; Barile, Ronald; Heidersbach, Robert; Steinrock, T. (Technical Monitor)

    2002-01-01

    This paper presents the methodology for comparing the relative effectiveness of four chemical products used for rinsing airplanes and helicopters. The products were applied on a weekly basis to a series of flat alloy panels exposed to an oceanfront marine environment for one year. The results are presented along with comparisons of exposures of the same alloys that were not washed, were washed with seawater, or washed with de-ionized water.

  19. Deformation Cycling of a Ti - Ni Alloy with Superelasticity Effect Applied in Cardiology

    Science.gov (United States)

    Kaputkin, D. E.; Morozova, T. V.

    2014-07-01

    The study concerns the effect of the conditions and of the force of loading experienced by an implanted device from a Ti - Ni alloy during its transfer to the working zone, for example, in endoscopic implantation into the coronary sinus of the greater vena cava of heart. It is shown that preliminary deformation cycling (10 - 15 cycles) stabilizes the set of mechanical properties of the alloy.

  20. Neutron irradiation effects on magnetic properties of some Heusler alloys

    International Nuclear Information System (INIS)

    Onodera, Hideya; Shinohara, Takeshi; Yamamoto, Hisao; Watanabe, Hiroshi

    1975-01-01

    The neutron irradiation effects were studied with measurements of temperature dependence of magnetization in ordered and disordered Heusler alloys. The irradiation was carried out in JMTR with a total flux of fast neutrons of 10 20 nvt. Fully ordered Cu 2 MnIn, partially ordered Cu 2 MnAl and completely disordered Cu 2 MnSn were prepared with various temperature treatments. The magnetization-temperature curves of each specimen were measured before and after irradiation. In the irradiated Cu 2 MnIn, the disordering by the irradiation gave rise to a decrease of magnetization, and the temperature dependence of magnetization showed that the disordered region contained various regions with different degrees of disorder. For the distribution of the disordered region, the calculation based on the theory of temperature spike by Seitz and Koekler gave a feasible result that a disordered region comprised a central core with a radius of 5.4 A which was completely disordered and a periphery of 3.3 A thickness which was partially disordered. From the magnetization-temperature curves of Cu 2 MnAl, it was considered that the disordered regions induced by the irradiation had different properties from those induced by the heat treatment. The former were the localized and comprised regions corresponding to various degrees of disorder, while the latter spread spatially in a wide range with a certain degree of disorder. The ordering by enhanced diffusion occurred simultaneously to an extent comparable to the disordering, and so it played an important role in the magnetization in the partially disordered Cu 2 MnAl. In the disordered Cu 2 MnSn, however, the ordering effect was very small. It is supposed to be difficult for the A2 structure to transform into the L2 1 structure by the enhanced diffusion. (auth.)

  1. Effect of phosphorus additions on hot pressing temperature and some properties of WC-Co hard alloys

    International Nuclear Information System (INIS)

    Dotsenko, V.M.; Simkina, Eh.S.; Tsypin, N.V.

    1977-01-01

    Results of studies on the effect of phosphorus additions on hot pressing temperature and some properties of VK6 and VK15 hard alloys are given. It is shown that alloying of hard alloys with 3-6 wt % phosphorus gives opportunity to lower substantially (for 200-300 deg) their hot pressing temperature. Hardness and density of alloys with phosphorus do not practically change. Some decrease of strength and wear-resistance characteristics is observed which is obviously connected with irregular distribution of phosphorus in the alloy

  2. Evaluating bond strength of porcelain to dental alloys and the effects of repeated porcelain sintering on it

    Directory of Open Access Journals (Sweden)

    n. Rashidan

    1998-05-01

    Full Text Available   In this study, porcelain bond strength to three different alloys of Gold-base, pd-Ag and base-Metal were compared and the effect of repeated porcelain sintering on bond strength was evaluated. The obtained results showed best bond strength of porcelain with Gold-base alloy. Pd-Ag and Base-metal alloys showed less strength respectively. During repeated sintering of porcelain, bond strength has not changed in Base-metal and Gold-base alloys while it was weakened in pd-Ag alloy.

  3. Evaluating bond strength of porcelain to dental alloys and the effects of repeated porcelain sintering on it

    OpenAIRE

    n. Rashidan; F Geramipanah

    1998-01-01

      In this study, porcelain bond strength to three different alloys of Gold-base, pd-Ag and base-Metal were compared and the effect of repeated porcelain sintering on bond strength was evaluated. The obtained results showed best bond strength of porcelain with Gold-base alloy. Pd-Ag and Base-metal alloys showed less strength respectively. During repeated sintering of porcelain, bond strength has not changed in Base-metal and Gold-base alloys while it was weakened in pd-Ag alloy.

  4. Alloying effect on the electronic structures of hydrogen storage compounds

    Energy Technology Data Exchange (ETDEWEB)

    Yukawa, H.; Moringa, M.; Takahashi, Y. [Nagoya Univ. (Japan). Dept. of Mater. Sci. and Eng.

    1997-05-20

    The electronic structures of hydrogenated LaNi{sub 5} containing various 3d transition elements were investigated by the DV-X{alpha} molecular orbital method. The hydrogen atom was found to form a strong chemical bond with the Ni rather than the La atoms. The alloying modified the chemical bond strengths between atoms in a small metal octahedron containing a hydrogen atom at the center, resulting in the change in the hydrogen absorption and desorption characteristics of LaNi{sub 5} with alloying. (orig.) 7 refs.

  5. Convective effects on directional solidification of a simulated metal alloy

    Science.gov (United States)

    Mccay, T. D.; Mccay, M. H.; Lowry, S. A.; Smith, L. M.

    1988-01-01

    The first significant results of a ground-based experimental program which supports a low gravity space processing Spacelab experiment are reported. The phenomena which precipitate pluming and thus freckling in a metal alloy analog (ammonium chloride and water) are studied in detail and the sequential events leading to massive channeling and convection are optically documented. The pluming is shown to be other than a random burst of unstable fluid from a preferred channel but rather a natural occurrence resulting from a fundamental (Rayleigh-Benard) fluid dynamic instability at the density inversion interface. This extrapolates to critical size parameters appropriate to processing of actual metal alloys.

  6. An application of eddy current damping effect on single point diamond turning of titanium alloys

    Science.gov (United States)

    Yip, W. S.; To, S.

    2017-11-01

    Titanium alloys Ti6Al4V (TC4) have been popularly applied in many industries. They have superior material properties including an excellent strength-to-weight ratio and corrosion resistance. However, they are regarded as difficult to cut materials; serious tool wear, a high level of cutting vibration and low surface integrity are always involved in machining processes especially in ultra-precision machining (UPM). In this paper, a novel hybrid machining technology using an eddy current damping effect is firstly introduced in UPM to suppress machining vibration and improve the machining performance of titanium alloys. A magnetic field was superimposed on samples during single point diamond turning (SPDT) by exposing the samples in between two permanent magnets. When the titanium alloys were rotated within a magnetic field in the SPDT, an eddy current was generated through a stationary magnetic field inside the titanium alloys. An eddy current generated its own magnetic field with the opposite direction of the external magnetic field leading a repulsive force, compensating for the machining vibration induced by the turning process. The experimental results showed a remarkable improvement in cutting force variation, a significant reduction in adhesive tool wear and an extreme long chip formation in comparison to normal SPDT of titanium alloys, suggesting the enhancement of the machinability of titanium alloys using an eddy current damping effect. An eddy current damping effect was firstly introduced in the area of UPM to deliver the results of outstanding machining performance.

  7. Effect of Rare Earth Erbium on Microstructure and Mechanical Properties of A356 Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    LI Xiao-yan

    2018-01-01

    Full Text Available For conventional A356 aluminum alloy, the addition of rare earth elements is an effective way to modify its microstructures and improve its mechanical properties. The effect of rare earth Er on microstructures and properties of as-cast A356 aluminum alloy was studied by differential scanning calorimetry (DSC, X-ray diffraction (XRD and scanning electron microscopy (SEM. The results indicate that rare earth element Er is a good modifier for A356 aluminum alloy, which is able to improve obviously the microstructure of as-cast alloy. The addition of Er refines the primary α-Al phase, decreases the secondary dendrite arm spacing and the dendrite arm diameter, and modifies the eutectic Si in as-cast structure simultaneously. When the amount of Er reaches 0.4% (mass fraction, the same below, the refinement effect is the most significant, secondary dendrite arm spacing decreases from 53.6μm to 17.5μm and the morphology of eutectic Si transforms from thick lath-shaped to short rod-like or round granular. Compared with A356 alloy, the tensile strength and elongation of A356 aluminum alloy with the addition of 0.4%Er increase by 15.1% and 29.8% respectively.

  8. An application of eddy current damping effect on single point diamond turning of titanium alloys

    International Nuclear Information System (INIS)

    Yip, W S; To, S

    2017-01-01

    Titanium alloys Ti6Al4V (TC4) have been popularly applied in many industries. They have superior material properties including an excellent strength-to-weight ratio and corrosion resistance. However, they are regarded as difficult to cut materials; serious tool wear, a high level of cutting vibration and low surface integrity are always involved in machining processes especially in ultra-precision machining (UPM). In this paper, a novel hybrid machining technology using an eddy current damping effect is firstly introduced in UPM to suppress machining vibration and improve the machining performance of titanium alloys. A magnetic field was superimposed on samples during single point diamond turning (SPDT) by exposing the samples in between two permanent magnets. When the titanium alloys were rotated within a magnetic field in the SPDT, an eddy current was generated through a stationary magnetic field inside the titanium alloys. An eddy current generated its own magnetic field with the opposite direction of the external magnetic field leading a repulsive force, compensating for the machining vibration induced by the turning process. The experimental results showed a remarkable improvement in cutting force variation, a significant reduction in adhesive tool wear and an extreme long chip formation in comparison to normal SPDT of titanium alloys, suggesting the enhancement of the machinability of titanium alloys using an eddy current damping effect. An eddy current damping effect was firstly introduced in the area of UPM to deliver the results of outstanding machining performance. (paper)

  9. Effect of Ni interlayer on diffusion bonding of a W alloy and a Ta alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jian; Liu, Ruxia; Wei, Qinqin; Luo, Guoqiang; Shen, Qiang; Zhang, Lianmeng [Wuhan Univ. of Technology (China). The State Key Lab. of Advanced Technology for Materials Synthesis and Processing

    2017-11-01

    The combination of W and Ta is expected to be highly beneficial for many applications from aerospace, weapons, military and nuclear industry. In this paper, W and Ta alloys were successfully diffusion bonded with Ni interlayer. The process of the formation of W/Ni/Ta diffusion bonded joints was investigated by means of scanning electron microscopy, X-ray diffraction system, electron probe micro-analyzer, energy dispersive spectrometry and shear strength measurement. The results show that the shear strength increases when the bonding temperature increases and exhibits a maximum value of 244 MPa at 930 C. The bonding of W/Ni can be attributed to the bonding of Ni to tungsten grains and the bonding of Ni to a Ni-Fe-binder mainly by elemental diffusion. The fracture takes place in the Ni/Ta interface and Ni{sub 3}Ta and Ni{sub 2}Ta intermetallic compounds are formed on the fracture surfaces.

  10. Effect of cold working on the stress corrosion cracking resistance of nickel-chromium-iron alloys

    International Nuclear Information System (INIS)

    Yonezawa, T.; Onimura, K.

    1987-01-01

    In order to grasp the stress corrosion cracking resistance of cold worked nickel base alloys in PWR primary water, the effect of cold working on the stress corrosion cracking resistance of alloys 600, X-750 and 690, in high temperature water, have been studied. Stress corrosion cracking tests were conducted at 360 0 C (633K) in a simulated PWR primary water for about 12,000 hours (43.2Ms). From the test results, it is concluded that the stress corrosion cracking resistance in the cold worked Alloy 600 at the same applied stress level increases with an increase in cold working ratio, and the cold worked alloys of thermally treated 690 and X-750 have excellent stress corrosion cracking resistance. (Author)

  11. Hydrogen diffusion and distribution in alloy 600 and related effects on the plasticity

    International Nuclear Information System (INIS)

    Lecoester, F.; Brass, A.M.; Chene, J.; Noel, D.

    1997-01-01

    Hydrogen can play a part in several mechanisms proposed for explaining the stress corrosion cracking of nickel based alloy 600, used in steam generators of pressurized water nuclear reactors. This study presents data on diffusion and hydrogen trapping in alloy 600 as well as the embrittlement which results from it. Distribution data were obtained by deuterium analysis of samples cathodically charged with heavy water. Secondary ion mass spectrometry, liquid scintillation counting and tritium autoradiography have been used for analysis. Data on hydrogen embrittlement were obtained by imposed tensile tests on samples with or without cathodic charging. Different microstructures were studied. The results show that alloy 600 embrittlement greatly depend on the structure and increases with the degree of intergranular precipitation. An effect of hydrogen on the plasticity of the alloy was noted. (author)

  12. Effect of disorder on electronic and magnetic properties of Co2VGa Heusler alloy

    International Nuclear Information System (INIS)

    Seema, K.; Kumar, Ranjan

    2015-01-01

    This paper presents the effect of disorder on electronic, magnetic and half-metallic properties of Co 2 VGa Heusler alloy using density functional theory. Binary mixing is the most common form of atomic disorder in these compounds. We have considered three types of disorders: DO 3 , A2 and B2 disorder which corresponds to X-Y, X-Z and Y-Z mixing respectively. After structural optimization, we found that A2 disorder has high formation energy and is most unlikely to occur. The half-metallic nature of the alloy is destroyed in presence of DO 3 and A2 disorder. The destruction of half-metallicity is due to reconstruction of energy states. Also the loss of half-metallicity is accompanied by reversal of spin-polarization at the Fermi level. B2 disorder retains the half-metallic nature of the alloy but spin-polarization value is reduced as compared to the ordered alloy

  13. The Effect of Hydrogen and Hydrides on the Integrity of Zirconium Alloy Components Delayed Hydride Cracking

    CERN Document Server

    Puls, Manfred P

    2012-01-01

    By drawing together the current theoretical and experimental understanding of the phenomena of delayed hydride cracking (DHC) in zirconium alloys, The Effect of Hydrogen and Hydrides on the Integrity of Zirconium Alloy Components: Delayed Hydride Cracking provides a detailed explanation focusing on the properties of hydrogen and hydrides in these alloys. Whilst the focus lies on zirconium alloys, the combination of both the empirical and mechanistic approaches creates a solid understanding that can also be applied to other hydride forming metals.   This up-to-date reference focuses on documented research surrounding DHC, including current methodologies for design and assessment of the results of periodic in-service inspections of pressure tubes in nuclear reactors. Emphasis is placed on showing that our understanding of DHC is supported by progress across a broad range of fields. These include hysteresis associated with first-order phase transformations; phase relationships in coherent crystalline metallic...

  14. The effect of urea on the corrosion behavior of different dental alloys.

    Science.gov (United States)

    Geckili, Onur; Bilhan, Hakan; Bilgin, Tayfun; Anthony von Fraunhofer, J

    2012-01-01

    Intraoral corrosion of dental alloys has biological, functional, and esthetic consequences. Since it is well known that the salivary urea concentrations undergo changes with various diseases, the present study was undertaken to determine the effect of salivary urea concentrations on the corrosion behavior of commonly used dental casting alloys. Three casting alloys were subjected to polarization scans in synthetic saliva with three different urea concentrations. Cyclic polarization clearly showed that urea levels above 20 mg/100 ml decreased corrosion current densities, increased the corrosion potentials and, at much higher urea levels, the breakdown potentials. The data indicate that elevated urea levels reduced the corrosion susceptibility of all alloys, possibly through adsorption of organics onto the metal surface. This study indicates that corrosion testing performed in sterile saline or synthetic saliva without organic components could be misleading.

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

    International Nuclear Information System (INIS)

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

    2009-01-01

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

  16. Effect of nano-segregation phases on electrochemical property of high active Al alloy anode

    International Nuclear Information System (INIS)

    Liang, S Q; Zhang, Y; Mao, Z W; Tang, Y; Guan, D K

    2009-01-01

    The effect of nano-segregation phases formed during rolling process on the electrochemical property of Al-Mg-Sn-Bi-Ga-In alloy anode in alkaline solution (80 deg. C, Na 2 SnO 3 + 5mol/L NaOH)was analyzed according to the chronopotentiometry (E-T curves), hydrogen collection tests and modern microstructure analysis. The results show that when controlling the rolling temperature and pass deformation at 370 deg. C and 40% respectively, the Al alloy anode undergoes the dynamic recrystallization, which benefits to the uniform distribution of nano-segregation phases and improvement of electrochemical property of Al alloy anode. The optimum Al alloy anode has the more negative electrode potential of about -1.48V (vs.Hg/HgO) and the lower hydrogen evolution rate of 0.1889mL/ (min·cm 2 ).

  17. Synergetic effects in CO adsorption on Cu-Pd(111) alloys

    DEFF Research Database (Denmark)

    Lopez, Nuria; Nørskov, Jens Kehlet

    2001-01-01

    We present density functional calculations for the interaction of CO on different Cu-Pd(111) bulk and surface alloys. The modification of the adsorption properties with respect to hose of the adsorption on pure Cu(111) and Pd(111) is described in terms of changes in the adsorption sites and the c......We present density functional calculations for the interaction of CO on different Cu-Pd(111) bulk and surface alloys. The modification of the adsorption properties with respect to hose of the adsorption on pure Cu(111) and Pd(111) is described in terms of changes in the adsorption sites...... and the change of the electronic structure occurring upon alloying. The presence of cooperative, synergetic. effects is found to be important specially for Cu-rich bulk alloys. In this case. a larger adsorption energy is found for the inactive component than for the pure inactive system. This activation induces...

  18. Effect of disorder on electronic and magnetic properties of Co2VGa Heusler alloy

    Science.gov (United States)

    Seema, K.; Kumar, Ranjan

    2015-08-01

    This paper presents the effect of disorder on electronic, magnetic and half-metallic properties of Co2VGa Heusler alloy using density functional theory. Binary mixing is the most common form of atomic disorder in these compounds. We have considered three types of disorders: DO3, A2 and B2 disorder which corresponds to X-Y, X-Z and Y-Z mixing respectively. After structural optimization, we found that A2 disorder has high formation energy and is most unlikely to occur. The half-metallic nature of the alloy is destroyed in presence of DO3 and A2 disorder. The destruction of half-metallicity is due to reconstruction of energy states. Also the loss of half-metallicity is accompanied by reversal of spin-polarization at the Fermi level. B2 disorder retains the half-metallic nature of the alloy but spin-polarization value is reduced as compared to the ordered alloy.

  19. Effect of post annealing temperatures on microstructures and mechanical properties of cryorolled 5052 aluminium sheet alloy

    Science.gov (United States)

    Anas, N. M.; Umar, Z. A. A.; Zuhailawati, H.; Anasyida, A. S.

    2017-07-01

    The effect of post annealing temperature of cryorolled 5052 Al alloy after cryorolling process at 30% thickness reduction was investigated, focusing on the evolution of microstructures and mechanical properties. The evolution of microstructure was investigated using optical microscopy (OM). The mechanical behaviour of the samples have been evaluated through Vickers hardness and tensile test performed at room temperature. The results showed that the post annealing on cryorolled 5052 Al alloy have enhanced the ductility with sacrificing the hardness and strength. The lattice strain of post annealed 5052 Al alloy decreased with increasing of annealing temperatures. The evolution of microstructure of the post annealed 5052 Al alloy showed equiaxed grains at 200°C and grain coarsening as post annealing temperature increases to 350°C. The result of crystallite size confirmed the grain size increased as the post annealing temperature rises.

  20. Effect of microstructure and cutting speed on machining behavior of Ti6Al4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Telrandhe, Sagar V.; Mishra, Sushil; Saxena, Ashish K. [Indian Institute of Technology Bombay, Mumbai (India)

    2017-05-15

    Machining of aerospace and biomedical grade titanium alloys has always been a challenge because of their low conductivity and elastic modulus. Different machining methods and parameters have been adopted for high precision machining of titanium alloys. Machining of titanium alloys can be improved by microstructure optimization. The present study focuses on the effect of microstructure on ma- chinability of Ti6Al4V alloys at different cutting speeds. Samples were subjected to different annealing conditions resulting in different grain sizes and local micro-strains (misorientation). Cutting forces were significantly reduced after annealing; consequently, sub-surface residual stresses were reduced. Deformation twinning was also observed on samples annealed at a higher temperature due to larger grain size. Initial strain free grains and deformation twinning during machining reduces the cutting force at higher cutting speed.

  1. Effects of minor alloying additions on the strength and swelling behavior of an austenitic stainless steel

    International Nuclear Information System (INIS)

    Gessel, G.R.

    1978-06-01

    A set of 32 alloys consisting of various additions of the elements Mo, W, Al, Ti, Nb, C and Si to an Fe-7.5 Cr-20 Ni alloy were made in order to investigate the effects of these solute additions on alloy swelling and strength. Both single and multiple additions were examined. The influence of various solute elements on the swelling behavior in the range 500 to 730 0 C was investigated using 4 MeV Ni ion bombardment to a dose 170 dpa. It was found that on an atomic percent basis, the elements may be arranged in order of decreasing effectiveness in reducing peak temperature swelling as follows: Ti, C, Nb, Si, and Mo. Small amounts of aluminum enhance swelling. Additions of Si, Ti, or Nb truncate the high temperature swelling regime of the ternary alloy. Mo, W, and C do not have a strong effect on the temperature dependence of swelling. The results may be interpreted in terms of the effect of point defect trapping on void growth rates, and it is suggested that the changes in peak temperature are the result of small changes in the free vacancy formation energy. A method for treating certain multiple additions is proposed. The effect of these alloying additions on short time high temperature strength properties was estimated using hot hardness measurements over the temperature range 22 to 850 0 C. On an atom percent basis Nb and Ti were most effective in conferring solid solution strengthening and Si the least effective. In the regime 22 to approximately 650 0 C, the hardness data was found to fit an equation of the form: H = H 0 + b/T; where H is the hardness, T is the temperature, and H 0 and b are constants for a given alloy. An empirical method was devised to estimate the hot hardness of alloys containing more than one solute addition

  2. Long-term thermal degradation and alloying constituent effects on five boron/aluminum composites

    Science.gov (United States)

    Olsen, G. C.

    1982-01-01

    Thermal exposure effects on the properties of five boron/aluminum composite systems were experimentally investigated. The composite systems were 49 volume percent boron fibers (203 micron diameter) in aluminum-alloy matrices 1100 Al, 2024 Al, 3003 Al, 5052 Al, and 6061 Al. Specimens were thermally exposed up to 10,000 hours at 500 K and 590 K, up to 500 hours at 730 K, and up to 10,000 hours at 500 K and 590 K, up to 500 hours at 730 K, and up to 2000 thermal cycles between 200 K and 590 K. Composite longitudinal and transverse tensile strengths, longitudinal compression strength, and in-plane shear strength were determined. None of the systems was severely degraded by exposure at 590 K. The best performing system was B-2024 Al. Effects of matrix alloys on degradation mechanisms were experimentally investigated. Composite specimens and individual fibers were metallurgically analyzed with a scanning electron microscope and an electron microprobe to determine failure characteristics, chemical element distribution, and reaction layer morphology. Alloying constituents were found to be affect the composite degradation mechanisms as follows: alloys containing iron, but without manganese as a stabilizer, caused increased low-temperature degradation; alloys containing magnesium, iron, or manganese caused increased degradation; and alloys containing copper caused increased fiber strength.

  3. The effects of alloying elements on strength, hardenability, and ...

    African Journals Online (AJOL)

    They were then air cooled before being cold rolled to ~0.9mm and annealed. Dual phase heat treatment was carried out at 755oC followed by quenching in water. Tensile and hardenability tests were carried out. Results showed that alloying elements in steel increased strength in the dual phase steels by amounts ranging ...

  4. Effect of hydrogen on mechanical properties of -titanium alloys

    Indian Academy of Sciences (India)

    Monotonic and cyclic strength increase at the expense of ductility with increasing hydrogen concentration. The brittle to ductile transition temperature shifts to higher values and the fatigue crack propagation threshold value decreases. The microstructure of the metastable, usually two-phase -titanium alloys is strongly ...

  5. The effects of alloying elements on strength, hardenability, and ...

    African Journals Online (AJOL)

    Tensile and hardenability tests were carried out. Results showed that alloying elements in steel increased strength in the dual phase steels by amounts ranging from 150 Mpa for Nb-V steel to 226 MPa for Nb steel. Strain hardening exponent, n, was also increased from ~0.22 for annealed to 0.35 in the dual phase steels.

  6. Effect of alloying on the electronic structure and magnetic properties ...

    Indian Academy of Sciences (India)

    Unknown

    Keywords. Magnetism; alloys. 1. Introduction. Recently there have been several studies on the magne- tism of thin overlayers of transition metals like Fe on noble metal substrates (Blügel 1997; Mookerjee et al. 2000). It was noted that the magnetic moment on a sur- face 'magnetic' atom depended sensitively on both the.

  7. Alloying effect on K X-ray intensity ratio and production cross section values of Zn and Cr in Zn--Cr alloys

    International Nuclear Information System (INIS)

    Dogan, M.; Tirasoglu, E.; Karahan, İ.H.; Kup Aylikci, N.; Aylikci, V.; Kahoul, A.; Cetinkara, H.A.; Serifoglu, O.

    2013-01-01

    In this study, σ Kα , σ Kβ production cross-sections and K β /K α intensity ratios of Cr and Zn have been measured in pure metals and in different alloy compositions which have different composition values. And also, empirical and semi-empirical K-shell fluorescence yields (ω K ) and K β /K α intensity ratios from the available experimental data for elements with 23≤Z≤30 were calculated. The experimental data are fitted using the quantity (ω K /(1−ω K )) 1/4 vs. Z to deduce the empirical K-shell fluorescence yields and K β /K α intensity ratios. The effects of alloying on the fluorescence parameters and bath temperatures on alloy compositions were investigated. Our analysis indicates that these effects arise from reorganization of atom and charge transfer mechanism in alloys. - Highlights: ► The alloying effect on the X-ray fluorescence parameters is investigated. ► The concentration of alloy compositions is depending on the bath temperature. ► The changes on the K X-ray fluorescence parameters are observed

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

    Directory of Open Access Journals (Sweden)

    Pillis Marina Fuser

    2004-01-01

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

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

    International Nuclear Information System (INIS)

    Matkovic, Tanja; Matkovic, Prosper; Malina, Jadranka

    2004-01-01

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

  10. Effect of strain rate and temperature at high strains on fatigue behavior of SAP alloys

    DEFF Research Database (Denmark)

    Blucher, J.T.; Knudsen, Per; Grant, N.J.

    1968-01-01

    Fatigue behavior of three SAP alloys of two nominal compositions (7 and 13% Al2O3) was studied in terms of strain rate and temperature at high strains; strain rate had no effect on life at 80 F, but had increasingly greater effect with increasing temperature above 500 F; life decreased with decre......Fatigue behavior of three SAP alloys of two nominal compositions (7 and 13% Al2O3) was studied in terms of strain rate and temperature at high strains; strain rate had no effect on life at 80 F, but had increasingly greater effect with increasing temperature above 500 F; life decreased...

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

    Science.gov (United States)

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

    2016-08-01

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

  12. Effects of Sm addition on microstructure and mechanical properties of a Mg-10Y alloy

    Directory of Open Access Journals (Sweden)

    Li Quanan

    2014-01-01

    Full Text Available To further increase the mechanical properties, 0.5wt.% Sm was introduced to a Mg-10Y alloy in this study. The effects of Sm addition on the microstructures and mechanical properties of the Mg-10Y alloy, especially the aged Mg-10Y alloy, were investigated. The microstructure observation and tensile tests were performed by using an optical microscopy, a scanning electron microscopy and a universal material testing machine, respectively. The phase analysis was performed using X-ray diffractometer. The results show that the 0.5wt.% Sm addition can not only promote the formation of fine and dispersed Mg24Y5 phases, but also improve their morphology and distribution; it also increases the thermal stability of Mg24Y5 phases. Sm addition is seen to increase the ultimate tensile strength of Mg-10Y alloy at elevated temperatures (200, 250, 300 and 350 ℃, while decrease the elongation. But the elongation is still up to 7.5% even at 350 ℃. In the range of 250 ℃ to 300℃, the ultimate tensile strength of the alloy reaches its maximum (with a range average of 235 MPa and is not sensitive to the temperature change, which is very useful to the application of heat-resistant magnesium alloys. Even at 350 ℃, the ultimate tensile strength of Mg-10Y-0.5Sm is still up to 155 MPa. Considering both of the ultimate tensile strength and elongation, the maximum application temperature of the Mg-10Y-0.5Sm alloy can be up to 300 ℃. The strengthening mechanisms of Mg-10Y-0.5Sm alloy are mainly attributed to dispersion strengthening of Mg24Y5 phase particles with a certain solubility of Sm and grain refinement strengthening of α-Mg matrix.

  13. The effect of phosphorus on the microstructure and mechanical properties of ATI 718Plus alloy

    International Nuclear Information System (INIS)

    Wang, Minqing; Du, Jinhui; Deng, Qun; Tian, Zhiling; Zhu, Jing

    2015-01-01

    Since the discovery in the 1990s of the abnormal improvement produced by phosphorus in the stress rupture and creep life of Inconel 718 (hereafter referred to as 718), a great deal of additional research followed. However, the mechanism of the action of phosphorous in 718 is still in question. This paper details an experimental study that was intended to determine how phosphorus acts upon the microstructure and mechanical properties of Ni–Fe based alloy 718Plus. The results show that phosphorus has little effect on the strength and ductility of alloy 718Plus, but can significantly improve the stress rupture life. Phase constituents such as the δ and γ′ phases were quantitatively analyzed using electrolytic phase isolation and micro-chemical and XRD analysis as the phosphorous content of the alloy was increased. A full atom mapping of the distribution of phosphorus in the 718Plus alloy was quantitatively determined using APT (Atom Probe Tomography) technique. The results showed that there is no significant segregation of phosphorus at the γ′/γ and γ′/γ′ interface, but it significantly segregates at the grain boundaries and δ/γ interface. It was found that phosphorus is extremely depleted in the δ phase, which is believed to inhibit δ-phase precipitation by preventing δ phase nucleation and growth in the 718Plus alloy. Finally, the influence of phosphorus on the microstructure and mechanical properties of the 718Plus alloy was discussed

  14. Effect of Dynamic Composite Refinement and Modification on Microstructure of A356 Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    WANG Zheng-jun

    2017-01-01

    Full Text Available To make up for the inadequacy of Sr modification,Al-5Ti-1B-1RE master alloy refiner was prepared,then were used together with Al-10Sr master alloy for dynamic composite refinement and modification of A356 alloy.The A356 alloy microstructure of modification was studied and compared with the theoretical calculating results.The results show that the melt is fiercely stirred and vibrated by the JJ-1 laboratory electric stirrer;the refining effect of α-Al phase is excellent;the coarse and needle-like eutectic Si phase transforms into tiny,widely dispersed spherical particles and well-distributed at the grain boundaries.And mechanical property of the A356 alloy increases obviously.The grain size control study results are consistent with Johnson-Mehl equation theory.At the same time,the contents of gases of the A356 alloy are significantly reduced,which can not be achieved by Sr alone.Quantitative calculating results of degassing mechanism are consistent with the approximate calculating equations of thermodynamics and Stokes Law.

  15. Effects of Ag addition on the microstructures and properties of Al-Mg-Si-Cu alloys

    Science.gov (United States)

    He, Li-zi; Cao, Yi-heng; Zhou, Yi-zhou; Cui, Jian-zhong

    2018-01-01

    Effects of Ag addition on the microstructures, aging characteristics, tensile properties, electrochemical properties, and intergranular corrosion (IGC) properties of Al-1.1Mg-0.8Si-0.9Cu-0.35Mn-0.02Ti alloy were investigated using scanning electronic microscopy and transmission electronic microscopy. The aging process of Al-Mg-Si-Cu alloys was accelerated by the addition of Ag. The strength of peak-aged Al-Mg-Si-Cu alloys was enhanced by Ag addition because of the high density of β″- and L-phase age-hardening precipitates. The corrosion performance of the Al-Mg-Si-Cu alloy is closely related to the aging conditions and is independent of the Ag content. The IGC susceptibility is serious in the peak-aged alloy because of the continuous distribution of Cu-rich Q-phase precipitates along grain boundaries. Ag addition reduces the size of the grain-boundary-precipitate Q phase and the width of the precipitate-free zone and thus results in decreased IGC susceptibility of Al-Mg-Si-Cu alloys.

  16. Microstructure and age-hardening effects of aluminium alloys with additions of scandium and zirconium

    Energy Technology Data Exchange (ETDEWEB)

    Galun, R.; Mordike, B.L. [Inst. fuer Werkstoffkunde und Werkstofftechnik, Technische Univ. Clausthal, Clausthal-Zellerfeld (Germany); Maiwald, T.; Smola, B. [Zentrum fuer Funktionswerkstoffe GmbH, Clausthal-Zellerfeld (Germany); Mergen, R.; Manner, M.; Uitz, W. [Miba Gleitlager GmbH, Laakirchen (Australia)

    2004-12-01

    The aim of the work presented in this report was to produce age-hardenable aluminium alloys containing scandium and zirconium by a casting process with similar cooling conditions like an industrial casting process. Microstructure, precipitation structure and age-hardening response of different alloys with up to 0.4 wt.% Sc and Zr were investigated. Age-hardening experiments from the as-cast condition without solution annealing showed a significant increase of hardness of about 100% for Sc-rich alloys and of 50% for Zr-rich alloys compared to the as-cast condition. TEM investigations revealed the formation of precipitates of ternary Al{sub 3}(Sc{sub x}Zr{sub 1-x}) phases with a cubic cP4 crystal structure. In addition to the strengthening effect, a high thermal stability especially of the precipitates in Zr-rich alloys up to 400 C let these alloys look very promising for high-temperature applications. (orig.)

  17. Microstructure, electromagnetic shielding effectiveness and mechanical properties of Mg–Zn–Cu–Zr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xianhua, E-mail: xhchen@cqu.edu.cn [College of Materials Science and Engineering, Chongqing University, Chongqing 400045 (China); National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400045 (China); Liu, Lizi [College of Materials Science and Engineering, Chongqing University, Chongqing 400045 (China); Pan, Fusheng [College of Materials Science and Engineering, Chongqing University, Chongqing 400045 (China); National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400045 (China); Chongqing Academy of Science and Technology, Chongqing 401123 (China); Mao, Jianjun; Xu, Xiaoyang; Yan, Tao [College of Materials Science and Engineering, Chongqing University, Chongqing 400045 (China)

    2015-07-15

    Highlights: • The second phases were characterized systematically in Mg–Zn–Cu–Zr alloys. • Excellent EMI SE was successfully obtained by adding Cu. • Mechanism of EMI SE was analyzed. • Good mechanical properties could be achieved by adding low Cu content. - Abstract: The microstructure, electromagnetic interference (EMI) shielding effectiveness (SE) and mechanical properties of Mg–Zn–xCu–Zr alloys (x = 0–2.32 wt.%) were investigated in this study. The results indicated that the addition of Cu led to the formation of MgZnCu phase with a face-center cubic structure, and resulted in grain refinement. EMI SE increased significantly with increasing Cu content in extruded state. The alloy with 2.32 wt.% Cu exhibited optimal EMI shielding capacity with SE value of 84–117 dB. Meanwhile, it was found that good mechanical properties could be achieved by adding low Cu content. The extruded alloy with 0.37 wt.% Cu presented higher yield strength (276 MPa), ultimate tensile strength (346 MPa) and elongation (δ = 11.4%) compared with other extruded alloys. However, a higher Cu content would substantially deteriorate tensile properties of the alloys. Based on microstructure observation, the variation of EMI shielding capacity and mechanical properties have been discussed.

  18. Synergistic effect of Al and Gd on enhancement of mechanical properties of magnesium alloys

    Directory of Open Access Journals (Sweden)

    Bita Pourbahari

    2017-04-01

    Full Text Available The effect of Gd/Al ratio on the properties of as-cast Mg-Gd-Al-Zn alloys was investigated by changing the chemical composition from that of AZ61 to GZ61. At the ratio of 1, the Al2Gd phase becomes predominant and Mg17Al12 is hardly seen in the microstructure. As a potent inoculant, the Al2Gd phase resulted in intense grain refinement and enhancement of strength, ductility and toughness. For instance, the tensile strength and elongation to failure of Mg-3Gd-3Al-1Zn alloy were enhanced by ~4% and 180% compared with those of AZ61 alloy, respectively. However, at high Gd/Al ratios, the Al2Gd phase was replaced by (Mg,Al3Gd and Mg5Gd phases and very large grain sizes were achieved, which led to poor tensile properties and the appearance of cleavage facets on the fracture surfaces. Therefore, it can be deduced that the presence of Gd and Al, in appropriate amounts to reach Gd/Al ratio of ~ 1, is required for the achievement of grain refinement, good ductility, high strength, and the appearance of ductile fracture surfaces in the Mg-Gd-Al-Zn system. Conclusively, the Mg-Gd-Al-Zn alloys can be considered as a new class of structural magnesium alloy and it is superior to both AZ (Mg-Al-Zn and GZ (Mg-Gd-Zn series of alloys.

  19. Effects of V addition on recrystallization resistance of 7150 aluminum alloy after simulative hot deformation

    Energy Technology Data Exchange (ETDEWEB)

    Lai, Jing; Shi, Cangji; Chen, X.-Grant, E-mail: xgrant_chen@uqac.ca

    2014-10-15

    The effects of different V contents (0.01 to 0.19 wt.%) on the recrystallization resistance of 7150 aluminum alloys during post-deformation heat treatment were investigated. The microstructural evolutions at as-cast, as-homogenized conditions and after post-deformation annealing were studied using optical, scanning electron and transmission electron microscopes and using the electron backscattered diffraction technique. The precipitation of Al{sub 21}V{sub 2} dispersoids was observed in alloys containing 0.11 to 0.19 wt.% V after homogenization. The dispersoids were mainly distributed in the dendrite cells, and the precipitate-free zones occurred in the interdendritic regions and near grain boundaries. V addition could significantly enhance the recrystallization resistance during post-deformation annealing, particularly in the presence of a great number of Al{sub 21}V{sub 2} dispersoids. Recrystallized grain growth was effectively restricted because of the dispersoid pinning effect. The alloy containing 0.15 wt.% V exhibited the highest recrystallization resistance amongst all V-containing alloys studied. - Highlights: • Investigated the effect of V level on microstructure and flow stress of 7150 alloys • Characterized microstructures using optical microscopy, SEM, TEM and EBSD • Described the precipitation behavior of V-dispersoids in the dendritic structure • Studied the V effect on recrystallization resistance during post heat treatment • V addition greatly enhanced the recrystallization resistance during annealing.

  20. Effect of Mechanical Alloying Atmospheres and Oxygen Concentration on Mechanical Properties of ODS Ferritic Steels

    International Nuclear Information System (INIS)

    Noh, Sanghoon; Choi, Byoungkwon; Han, Changhee; Kim, Kibaik; Kang, Sukhoon; Chun, Youngbum; Kim, Taekyu

    2013-01-01

    Finely dispersed nano-oxide particles with a high number density in the homogeneous grain matrix are essential to achieve superior mechanical properties at high temperatures, and these unique microstructures can be obtained through the mechanical alloying (MA) and hot consolidation process. The microstructure and mechanical property of ODS steel significantly depends on its powder property and the purity after the MA process. These contents should be carefully controlled to improve the mechanical property at elevated temperature. In particular, appropriate the control of oxygen concentration improves the mechanical property of ODS steel at high temperature. An effective method is to control the mechanical alloying atmosphere by high purity inert gas. In the present study, the effects of mechanical alloying atmospheres and oxygen concentration on the mechanical property of ODS steel were investigated. ODS ferritic alloys were fabricated in various atmospheres, and the HIP process was used to investigate the effects of MA atmospheres and oxygen concentration on the microstructure and mechanical property. ODS ferritic alloys milled in an Ar-H 2 mixture, and He is effective to reduce the excess oxygen concentration. The YH 2 addition made an extremely reduced oxygen concentration by the internal oxygen reduction reaction and resulted in a homogeneous microstructure and superior creep strength

  1. Stress corrosion mechanisms of alloy-600 polycrystals and monocrystals in primary water: effect of hydrogen

    International Nuclear Information System (INIS)

    Foct, F.

    1999-01-01

    The aim of this study is to identify the mechanisms involved in Alloy 600 primary water stress corrosion cracking. Therefore, this work is mainly focussed on the two following points. The first one is to understand the influence of hydrogen on SCC of industrial Alloy 600 and the second one is to study the crack initiation and propagation on polycrystals and single crystals. A cathodic potential applied during slow strain rate tests does not affect crack initiation but increases the slow crack growth rate by a factor 2 to 5. Cathodic polarisation, cold work and 25 cm 3 STP/kg hydrogen content increase the slow CGR so that the K ISCC (and therefore fast CGR) is reached. The influence of hydrogenated primary water has been studied for the first time on Alloy 600 single crystals. Cracks cannot initiate on tensile specimens but they can propagate on pre-cracked specimens. Transgranular cracks present a precise crystallographic aspect which is similar to that of 316 alloy in MgCl 2 solutions. Moreover, the following results improve the description of the cracking conditions. Firstly, the higher the hydrogen partial pressure, the lower the Alloy 600 passivation current transients. Since this result is not correlated with the effect of hydrogen on SCC, cracking is not caused by a direct effect of dissolved hydrogen on dissolution. Secondly, hydrogen embrittlement of Alloy 600 disappears at temperatures above 200 deg.C. Thirdly, grain boundary sliding (GBS) does not directly act on SCC but shows the mechanical weakness of grain boundaries. Regarding the proposed models for Alloy 600 SCC, it is possible to draw the following conclusions. Internal oxidation or absorbed hydrogen effects are the most probable mechanisms for initiation. Dissolution, internal oxidation and global hydrogen embrittlement models cannot explain crack propagation. On the other hand, the Corrosion Enhanced Plasticity Model gives a good description of the SCC propagation. (author)

  2. Effect of surface oxidation on thermomechanical behavior of NiTi shape memory alloy wire

    Science.gov (United States)

    Ng, Ching Wei; Mahmud, Abdus Samad

    2017-12-01

    Nickel titanium (NiTi) alloy is a unique alloy that exhibits special behavior that recovers fully its shape after being deformed to beyond elastic region. However, this alloy is sensitive to any changes of its composition and introduction of inclusion in its matrix. Heat treatment of NiTi shape memory alloy to above 600 °C leads to the formation of the titanium oxide (TiO2) layer. Titanium oxide is a ceramic material that does not exhibit shape memory behaviors and possess different mechanical properties than that of NiTi alloy, thus disturbs the shape memory behavior of the alloy. In this work, the effect of formation of TiO2 surface oxide layer towards the thermal phase transformation and stress-induced deformation behaviors of the NiTi alloy were studied. The NiTi wire with composition of Ti-50.6 at% Ni was subjected to thermal oxidation at 600 °C to 900 °C for 30 and 60 minutes. The formation of the surface oxide layers was characterized by using the Scanning Electron Microscope (SEM). The effect of surface oxide layers with different thickness towards the thermal phase transformation behavior was studied by using the Differential Scanning Calorimeter (DSC). The effect of surface oxidation towards the stress-induced deformation behavior was studied through the tensile deformation test. The stress-induced deformation behavior and the shape memory recovery of the NiTi wire under tensile deformation were found to be affected marginally by the formation of thick TiO2 layer.

  3. Effects of Cu addition on microstructure and mechanical properties of as-cast Mg-6Zn magnesium alloy

    Directory of Open Access Journals (Sweden)

    Yu Zhang

    2017-07-01

    Full Text Available The application of Mg-Zn binary alloys is restricted due to their developed dendritic microstructure and poor mechanical properties. In this study, an alloying method was used to improve the mechanical properties of Mg-Zn alloy. The Mg-6Zn magnesium alloys microalloyed with varying Cu content (0, 0.8, 1.5, 2.0 and 2.5wt.% were fabricated by permanent mould casting, and the effects of Cu content on the microstructure and mechanical properties of as-cast Mg-6Zn alloys were studied using OM, SEM, XRD and tensile tests at room temperature. The obtained results show that the addition of Cu not only can refine the grains effectively, but also can modify the eutectic morphology and improve the mechanical properties of the alloys. The main phases of the studied alloys include α-Mg, MgZn2, Mg2Cu and CuMgZn. When the content of Cu exceeds 0.8wt.%, Mg2Cu phase appears. Meanwhile, the eutectic morphology is modified into dendritic shape or lamellar structure, which has an adverse effect on the tensile properties. Furthermore, among the investigated alloys, the alloy containing 0.8% Cu shows an optimal ultimate tensile strength of 196 MPa, while the alloy with 1.5wt.% Cu obtains an excellent elongation of 7.22%. The experimental alloys under different Cu contents show distinguishing fracture behaviors: the fracture of the alloy with 0.8wt.% Cu reveals a mixed mode of inter-granular and quasi-cleavage, while in other investigated alloys, the fracture behaviors are dominated by cleavage fracture.

  4. Segregation effects and phase developments during solidification of alloy 625

    DEFF Research Database (Denmark)

    Højerslev, Christian; Tiedje, Niels Skat; Hald, John

    2006-01-01

    The solidification behaviour of pure Alloy 625, and Alloy 625 enriched respectively in iron and carbon, was investigated in situ by hot-stage light optical microscopy. Using this technique planar front solidification for distances of several hundred microns was facilitated. After solidification...... sample in constitution, and consequently in gamma-phase composition. Niobium rich carbides formed prior to Laves phase; in carbon rich volumes only the carbides form. As compared to the pure sample, the sample enriched in iron had decreased global minimal solute concentration in the material...... that experienced planar front solidification. However, once the concentrations were corrected with respect to the dilution simply caused by the presence of iron, the solidification behaviour in this material was identical to that of the pure sample. The constitution in the material that solidified eutectic...

  5. Degradation of bioabsorbable Mg-based alloys: Assessment of the effects of insoluble corrosion products and joint effects of alloying components on mammalian cells

    Energy Technology Data Exchange (ETDEWEB)

    Grillo, Claudia A.; Alvarez, Florencia [Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), CCT La Plata-CONICET, Facultad de Ciencias Exactas, Departamento de Química, Universidad Nacional de La Plata, Casilla de Correo 16, Sucursal 4, 1900 La Plata (Argentina); Fernández Lorenzo de Mele, Mónica A., E-mail: mmele@inifta.unlp.edu.ar [Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), CCT La Plata-CONICET, Facultad de Ciencias Exactas, Departamento de Química, Universidad Nacional de La Plata, Casilla de Correo 16, Sucursal 4, 1900 La Plata (Argentina); Facultad de Ingeniería, Universidad Nacional de La Plata, Calle 1 esq. 47, 1900 La Plata (Argentina)

    2016-01-01

    This work is focused on the processes occurring at the bioabsorbable metallic biomaterial/cell interfaces that may lead to toxicity. A critical analysis of the results obtained when degradable metal disks (pure Mg and rare earth-containing alloys (ZEK100 alloys)) are in direct contact with cell culture and those obtained with indirect methods such as the use of metal salts and extracts was made. Viability was assessed by Acridine Orange dye, neutral red and clonogenic assays. The effects of concentration of corrosion products and possible joint effects of the binary and ternary combinations of La, Zn and Mg ions, as constituents of ZEK alloys, were evaluated on a mammalian cell culture. In all cases more detrimental effects were found for pure Mg than for the alloys. Experiments with disks showed that gradual alterations in pH and in the amount of corrosion products were better tolerated by cells and resulted in higher viability than abrupt changes. In addition, viability was dependent on the distance from the source of ions. Experiments with extracts showed that the effect of insoluble degradation products was highly detrimental. Indirect tests with Zn ions revealed that harmful effects may be found at concentrations ≥ 150 μM and at ≥ 100 μM in mixtures with Mg. These mixtures lead to more deleterious effects than single ions. Results highlight the need to develop a battery of tests to evaluate the biocompatibility of bioabsorbable biomaterials. - Highlights: • A metal disk setup is better in simulating in vivo situations than extracts and salts. • The biodegradation process and cell metabolism were interdependent. • Zn (100 μM) and Mg (8.2 × 10{sup 3} μM) mixtures are more toxic than single Zn or Mg. • Insoluble degradation products of Mg showed high negative effect on cell viability.

  6. Degradation of bioabsorbable Mg-based alloys: Assessment of the effects of insoluble corrosion products and joint effects of alloying components on mammalian cells

    International Nuclear Information System (INIS)

    Grillo, Claudia A.; Alvarez, Florencia; Fernández Lorenzo de Mele, Mónica A.

    2016-01-01

    This work is focused on the processes occurring at the bioabsorbable metallic biomaterial/cell interfaces that may lead to toxicity. A critical analysis of the results obtained when degradable metal disks (pure Mg and rare earth-containing alloys (ZEK100 alloys)) are in direct contact with cell culture and those obtained with indirect methods such as the use of metal salts and extracts was made. Viability was assessed by Acridine Orange dye, neutral red and clonogenic assays. The effects of concentration of corrosion products and possible joint effects of the binary and ternary combinations of La, Zn and Mg ions, as constituents of ZEK alloys, were evaluated on a mammalian cell culture. In all cases more detrimental effects were found for pure Mg than for the alloys. Experiments with disks showed that gradual alterations in pH and in the amount of corrosion products were better tolerated by cells and resulted in higher viability than abrupt changes. In addition, viability was dependent on the distance from the source of ions. Experiments with extracts showed that the effect of insoluble degradation products was highly detrimental. Indirect tests with Zn ions revealed that harmful effects may be found at concentrations ≥ 150 μM and at ≥ 100 μM in mixtures with Mg. These mixtures lead to more deleterious effects than single ions. Results highlight the need to develop a battery of tests to evaluate the biocompatibility of bioabsorbable biomaterials. - Highlights: • A metal disk setup is better in simulating in vivo situations than extracts and salts. • The biodegradation process and cell metabolism were interdependent. • Zn (100 μM) and Mg (8.2 × 10 3 μM) mixtures are more toxic than single Zn or Mg. • Insoluble degradation products of Mg showed high negative effect on cell viability.

  7. Effect of W Contents on Martensitic Transformation and Shape Memory Effect in Co-Al-W Alloys

    Science.gov (United States)

    Yang, X.; Qian, B. N.; Peng, H. B.; Wu, B. J.; Wen, Y. H.

    2018-04-01

    To clarify the effect of W contents on the shape memory effect (SME) in the Co-Al alloys and its influencing mechanism, the SME, martensitic transformation, and deformation behavior were studied in the Co-7Al-xW ( x = 0, 4, 6, 9 wt pct) alloys. The results showed that the additions of W all deteriorated the SME in Co-7Al alloy when deformed at room temperature. However, when deformed in liquid nitrogen, the SME in Co-7Al alloy could be remarkably improved from 43 to 78 pct after the addition of 4 pct W, above which the SME decreased rapidly with the increase of W content although the yield strength of the parent phase rose due to the solution strengthening of W. The deterioration in SME induced by the excessive addition of W could be ascribed to its resulting significant drop of the start temperature of martensitic transformation.

  8. Towards enhancing photocatalytic hydrogen generation: Which is more important, alloy synergistic effect or plasmonic effect?

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Zhenhe; Kibria, Md Golam; AlOtaibi, Bandar; Duchesne, Paul N.; Besteiro, Lucas V.; Gao, Yu; Zhang, Qingzhe; Mi, Zetian; Zhang, Peng; Govorov, Alexander O.; Mai, Liqiang; Chaker, Mohamed; Ma, Dongling

    2018-02-01

    Synergistic effect in alloys and plasmonic effect have both been explored for increasing the efficiency of water splitting. In depth understanding and comparison of their respective contributions in certain promising systems is highly desired for catalyst development, yet rarely investigated so far. We report herein our thorough investigations on a series of highly interesting nanocomposites composed of Pt, Au and C3N4 nanocomponents, which are designed to benefit from both synergistic and plasmonic effects. Detailed analyses led to an important conclusion that the contribution from the synergistic effect was at least 3.5 times that from the plasmonic effect in the best performing sample, Pt50Au50 alloy decorated C3N4. It showed remarkable turnover frequency of >1.6 mmol h-1 g-1 at room temperature. Our work provides physical insights for catalyst development by rationally designing samples to compare long-known synergistic effect with recently emerging, attractive plasmonic effect and represents the first case study in the field.

  9. Synthesis and evaluation of ageing effect on Cu–Al–Be–Mn quaternary Shape Memory Alloys

    Directory of Open Access Journals (Sweden)

    A.G. Shivasiddaramiah

    2016-09-01

    Full Text Available Copper based shape memory alloy exhibits high transformation temperature and ability to differ the achieved properties through alloying additions. A quaternary Cu–Al–Be–Mn shape memory alloys of 0.2–0.4 wt% of manganese, 0.4–0.5 wt% of Beryllium and 10–14 wt% of aluminium with remaining copper, showing β-phase at higher temperature and show shape memory effect when quenching to lower temperatures, SMA's were prepared by induction melting. The objective is to study the effect of thermal ageing at different temperatures Af (above austenitic phase finish temperature and at different time on shape memory effect and transformation temperatures. The aged specimens or SMA's were studied by DSC, OM and hardness measurements. The results from this study help to find the applications in different thermal conditions.

  10. Effect of phosphorus and heat treatment on microstructure of Al-25%Si alloy

    Directory of Open Access Journals (Sweden)

    Bo Dang

    2017-01-01

    Full Text Available It is known that phosphorus can refine the primary silicon and heat treatment can spheroidize the eutectic silicon. This paper presents an optimal combination of heat treatment processes and P refinement on hypereutectic Al-Si alloy. The optimal P addition amount, and the solution and aging temperatures for Al-25%Si alloy were obtained through the orthogonal experiment, and their modification effects were discussed. The results show that P addition has the greatest modification effect, followed by aging temperature, and the modification effect of solution temperature is the least. The optimized modification parameters are: addition of 0.6% P, solution at 540 篊 and aging at 160 篊 . In addition, the cooling curve, superheating and hardness of the alloy were also analyzed.

  11. Measuring and Modeling the Effects of Mechanical Twinning on the Behavior of Magnesium Alloys

    Science.gov (United States)

    Agnew, Sean; Wu, Peidong; Inal, Kaan; El Kadiri, Haitham; Wang, Jian; Tome, Carlos

    Our community has learned a great deal about twinning in Mg alloys over the past decade. Some of these things were known qualitatively in prior decades, but we have now developed a proficiency in characterization and computational modeling which permits a quantitative description of these twinning-induced effects over a wide range of strain rates, temperatures, loading conditions, and in a variety of alloy families. These capabilities could only be dreamed of by prior generations. This lecture will review the effects of the main twinning mode, {10.2} extension twinning (e.g., tension-compression yield asymmetry, yield plateau, anisotropy, rapid strain hardening, detwinning, etc.); characterization, primarily by diffraction-based techniques (electron, X-ray, and neutron); and modeling by crystal plasticity-based methods. Strategies to control these effects through microstructure, texture, and alloy design will be proposed. Finally, outstanding questions which merit further research will be highlighted.

  12. Poisoning effect of bismuth on modification behaviour of strontium in LM25 alloy

    International Nuclear Information System (INIS)

    Farahany, S.; Ourdjini, A.; Idris, M.H.; Thai, L.T.

    2011-01-01

    Nucleation and growth, temperature measurements and microstructure observations of silicon phase are presented for strontium modified Al-7% Si (LM25) cast alloy treated with bismuth. The results show that addition of bismuth in strontium modified alloys may have a poisoning effect resulting in lost modification of the silicon phase. With increasing Bi/Sr ratio, thermal analysis measurements showed that the eutectic growth temperature increased remarkably to 573 deg C and recalescence decreased to 0.2 deg C and the morphology of silicon displayed the same flake-like structure as in the unmodified alloys. Microstructural observation showed that a minimum Bi/Sr ratio of 1.2 which is equivalent to a Sr/Bi ratio of 0.43 is required for effective strontium modification and neutralization of the poisoning effect of bismuth. (author)

  13. Effect of thermal treatment on the electrochemical hydrogen absorption of ZrCrNi alloy

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz, F.C.; Peretti, H.A.; Corso, H.L [Centro Atomico Bariloche, Comision Nacional de Energia Atomica, Bariloche (Argentina); Visintin, A.; Real, S.G.; Castro, E.B.; Triaca, W.E. [Univ. Nacional de La Plata, La Plata (Argentina). Inst. de Investigaciones Fisiquimicas Teoricas y Aplicadas

    2006-07-01

    The catalytic effect of the secondary phases contained in a ZrCrNi alloy on its electrochemical properties was investigated. The purpose of the study was to improve the performance of Ni-MH battery electrodes. Four samples of the alloy were given annealing treatments at T=1250 K at variable times to obtain different concentrations of the secondary phases. Phase structure, morphology, and composition were studied using X-ray diffraction; radiation; scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) microanalysis. Results of the study were compatible with the presence of a major AB{sub 2} phase of C15 structure and the co-existence of C14 and C15 structures in both the as-melted and annealed alloys. The effect of the annealing in the ZrCrNi alloy resulted in a remarkable reduction of the discharge capacity and activation that was attributed to the dissolution of the secondary phases. The major catalytic effect was associated with the Zr{sub 8}Ni{sub 21} phase, by increasing the discharge capacity and favouring the activation. It was concluded that the presence of the catalytic phase in the alloy increased the hydrogen absorption capacity of the electrode due to an enhancement of the hydrogen production by electrolysis on the metal/catalytic phase and electrolyte interface. 6 refs., 1 fig.

  14. Effect of Solutes on Grain Refinement of As-Cast Fe-4Si Alloy

    Science.gov (United States)

    Li, Ming; Li, Jian-Min; Zheng, Qing; Wang, Geoff; Zhang, Ming-Xing

    2018-03-01

    Grain size is one of the key microstructural factors that control the mechanical properties of steels. The present work aims to extend the theories of grain refinement which were established for cast light alloys to steel systems. Using a designed Fe-4 wt pct Si alloy (all-ferrite structure during whole solidification process), the solute effect on grain refinement/grain coarsening in ferritic systems was comprehensively investigated. Experimental results showed that boron (B), which is associated with the highest Q value (growth restriction factor) in ferrite, significantly refined the as-cast structure of the Fe-4 wt pct Si alloy. Cu and Mo with low Q values had no effect on grain refinement. However, although Y and Zr have relatively high Q values, addition of these two solutes led to grain coarsening in the Fe-4Si alloy. Understanding the results in regards to the growth restriction factor and the driving force for the solidification led to the conclusion that in addition to the grain growth restriction effect, the changes of thermodynamic driving force for solidification due to the solute addition also played a key role in grain refinement in ferritic alloys.

  15. The effect of neutron irradiation on the mechanical properties of precipitation hardened copper alloys

    International Nuclear Information System (INIS)

    Fabritsiev, S.A.; Pokrovsky, A.S.

    1997-01-01

    The effects of neutron irradiation on strength and ductility properties of precipitation hardened (PH) copper alloys are discussed. The analysis is based on the experimental study of radiation damage of PH alloys irradiated in the mixed spectrum reactor SM-2 to fluences of 3.7-5.5 x 10 25 n/m 2 (E>0.1 MeV), corresponding to NRT displacement dose levels of 2.6-3.8 dpa. At irradiation temperatures of 100-285 C the processes of radiation hardening and reduction in the uniform elongation are the major effects. Irradiation at temperatures higher than 300 C causes a dramatic softening and improvement in uniform elongation of the Cu-Cr-Zr and Cu-Cr-Zr-Mg alloys. The threshold softening temperature for the PH alloys is shown to be about 300 C at a dose of 4.5 x 10 25 n/m 2 (E>0.1 MeV). The effect of the irradiation dose and temperature on the shift of the threshold temperature of PH copper-alloys softening is also considered. (orig.)

  16. Effects of alloying elements on the Snoek-type relaxation in Ti–Nb–X–O alloys (X = Al, Sn, Cr, and Mn)

    International Nuclear Information System (INIS)

    Lu, H.; Li, C.X.; Yin, F.X.; Fang, Q.F.; Umezawa, O.

    2012-01-01

    Highlights: ► The O Snoek-type relaxation in the Ti–Nb–X–O alloys was investigated. ► The dipole shape factor (δλ) and critical temperature T c were deduced from the peak. ► The δλ and T c were analyzed in terms of the d-orbital energy level (Md). ► With decreasing Md, the δλ increases and saturates at last while the T c decreases. ► The Md can be taken as a key parameter in designing high damping β-Ti alloys. - Abstract: The effect of alloying elements on the oxygen Snoek-type relaxation in the Ti–24Nb–X–1.7O alloys (X = 1Al, 2Al, 1Sn, 2Sn, 2Cr, 2Mn) was investigated in order to develop high damping materials based on point defect relaxation process. The relaxation strength of the Ti–Nb–Al–O and Ti–Nb–Sn–O alloys is the highest while that of the Ti–Nb–Mn–O and Ti–Nb–Cr–O alloys is the lowest. The dipole shape factor (δλ) and critical temperature T c , which are intrinsic to the Snoek-type relaxation, were figured out and analyzed in terms of the d-orbital energy level (Md) for each alloy based on the measured damping peak. With the decreasing Md, the δλ increases and saturates at last when the Md decreases to a certain value (about 2.435 eV), while the critical temperature T c decreases linearly. The parameter Md can be taken as a key parameter in designing high damping β-Ti alloys, that is, to design an intermediate value of Md at which the values of both δλ and T c are as high as possible.

  17. The Effects of Test Temperature, Temper, and Alloyed Copper on the Hydrogen-Controlled Crack Growth Rate of an Al-Zn-Mg-(Cu) Alloy

    Energy Technology Data Exchange (ETDEWEB)

    G.A. Young, Jr.; J.R. Scully

    2000-09-17

    The hydrogen embrittlement controlled stage II crack growth rate of AA 7050 (6.09 wt.% Zn, 2.14 wt% Mg, 2.19 wt.% Cu) was investigated as a function of temper and alloyed copper level in a humid air environment at various temperatures. Three tempers representing the underaged, peak aged, and overaged conditions were tested in 90% relative humidity (RH) air at temperatures between 25 and 90 C. At all test temperatures, an increased degree of aging (from underaged to overaged) produced slower stage II crack growth rates. The stage II crack growth rate of each alloy and temper displayed Arrhenius-type temperature dependence with activation energies between 58 and 99 kJ/mol. For both the normal copper and low copper alloys, the fracture path was predominantly intergranular at all test temperatures (25-90 C) in each temper investigated. Comparison of the stage II crack growth rates for normal (2.19 wt.%) and low (0.06 wt.%) copper alloys in the peak aged and overaged tempers showed the beneficial effect of copper additions on stage II crack growth rate in humid air. In the 2.19 wt.% copper alloy, the significant decrease ({approx} 10 times at 25 C) in stage II crack growth rate upon overaging is attributed to an increase in the apparent activation energy for crack growth. IN the 0.06 wt.% copper alloy, overaging did not increase the activation energy for crack growth but did lower the pre-exponential factor, {nu}{sub 0}, resulting in a modest ({approx} 2.5 times at 25 C) decrease in crack growth rate. These results indicate that alloyed copper and thermal aging affect the kinetic factors that govern stage II crack growth rate. Overaged, copper bearing alloys are not intrinsically immune to hydrogen environment assisted cracking but are more resistant due to an increased apparent activation energy for stage II crack growth.

  18. Effects of Thermal Exposure on Properties of Al-Li Alloys

    Science.gov (United States)

    Shah, Sandeep; Wells, Douglas; Stanton, William; Lawless, Kirby; Russell, Carolyn; Wagner, John; Domack, Marcia; Babel, Henry; Farahmand, Bahram; Schwab, David; hide

    2002-01-01

    Aluminum-Lithium (Al-Li) alloys offer significant performance benefits for aerospace structural applications due to their higher specific properties compared with conventional Al alloys. For example, the application of Al-Li alloy 2195 to the space shuffle external cryogenic fuel tank resulted in weight savings of over 7,000 lb, enabling successful deployment of International Space Station components. The composition and heat treatment of 2195 were optimized specifically for strength-toughness considerations for an expendable cryogenic tank. Time-dependent properties related to reliability, such as thermal stability, fatigue, and corrosion, will be of significant interest when materials are evaluated for a reusable cryotank structure. Literature surveys have indicated that there is limited thermal exposure data on Al-Li alloys. The effort reported here was designed to establish the effects of thermal exposure on the mechanical properties and microstructure of Al-Li alloys C458, L277, and 2195 in plate gages. Tensile, fracture toughness, and corrosion resistance were evaluated for both parent metal and friction stir welds (FSW) after exposure to temperatures as high as 300 F for up to 1000 hrs. Microstructural changes were evaluated with thermal exposure in order to correlate with the observed data trends. The ambient temperature parent metal data showed an increase in strength and reduction in elongation after exposure at lower temperatures. Strength reached a peak with intermediate temperature exposure followed by a decrease at highest exposure temperature. Friction stir welds of all alloys showed a drop in elongation with increased length of exposure. Understanding the effect of thermal exposure on the properties and microstructure of Al-Li alloys must be considered in defining service limiting temperatures and exposure times for a reusable cryotank structure.

  19. Theoretical Model for Volume Fraction of UC, 235U Enrichment, and Effective Density of Final U 10Mo Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Devaraj, Arun [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); Prabhakaran, Ramprashad [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); Joshi, Vineet V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); Hu, Shenyang Y. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); McGarrah, Eric J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL); Lavender, Curt A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)

    2016-04-12

    The purpose of this document is to provide a theoretical framework for (1) estimating uranium carbide (UC) volume fraction in a final alloy of uranium with 10 weight percent molybdenum (U-10Mo) as a function of final alloy carbon concentration, and (2) estimating effective 235U enrichment in the U-10Mo matrix after accounting for loss of 235U in forming UC. This report will also serve as a theoretical baseline for effective density of as-cast low-enriched U-10Mo alloy. Therefore, this report will serve as the baseline for quality control of final alloy carbon content

  20. The effect of copper, chromium, and zirconium on the microstructure and mechanical properties of Al-Zn-Mg-Cu alloys

    Science.gov (United States)

    Wagner, John A.; Shenoy, R. N.

    1991-01-01

    The present study evaluates the effect of the systematic variation of copper, chromium, and zirconium contents on the microstructure and mechanical properties of a 7000-type aluminum alloy. Fracture toughness and tensile properties are evaluated for each alloy in both the peak aging, T8, and the overaging, T73, conditions. Results show that dimpled rupture essentially characterize the fracture process in these alloys. In the T8 condition, a significant loss of toughness is observed for alloys containing 2.5 pct Cu due to the increase in the quantity of Al-Cu-Mg-rich S-phase particles. An examination of T8 alloys at constant Cu levels shows that Zr-bearing alloys exhibit higher strength and toughness than the Cr-bearing alloys. In the T73 condition, Cr-bearing alloys are inherently tougher than Zr-bearing alloys. A void nucleation and growth mechanism accounts for the loss of toughness in these alloys with increasing copper content.

  1. Effect of repeated firings on the color of opaque porcelain applied on different dental alloys.

    Science.gov (United States)

    Yilmaz, Burak; Ozçelik, Tuncer Burak; Wee, Alvin G

    2009-06-01

    Although metal ceramic fixed restorations are commonly preferred by clinicians, there remain a limited number of studies on how opaque porcelain color is affected by fabrication procedures, such as the number of firings and types of metal alloys. The purpose of this study was to determine the effects of various types of metal alloys on the color of opaque porcelain after repeated firings. Seven different types of metal ceramic alloys (3 base metals: Metalloy CC, chromium cobalt (B-MCC); Heraenium NA, nickel chromium (B-HNA); Argeloy NP, nickel chromium beryllium (B-ANP); 3 noble metals: Ceradelta, palladium silver (N-CD); Cerapall 2, palladium (N-CP2); V-Delta SF, gold palladium (N-VDSF); and 1 high noble metal: V-Gnathos Plus, gold platinum (HN-GP)) were used to support a 0.1-mm-thick layer of opaque porcelain (IPS d.SIGN Opaquer, shade B1) to determine the metal alloys' effect on the opaque porcelain color after repeated porcelain firings. Opaque porcelain was applied on specimens (16 mm x 1 mm) prepared from each type of alloy. The specimens (n=21) were subjected to 1 opaque firing, 4 consecutive dentin firing cycles, and 1 glaze firing cycle. Delta E values were calculated for all metal alloy groups from opaque firing (control group) to each subsequent firing stage within each tested alloy group. One-way ANOVA and Fisher's least significant difference tests were performed to determine the differences between alloys. In addition, DeltaE values calculated after repeated firings were analyzed by 1-way ANOVA and paired t test, to determine whether repeated dentin firing stages affected the color of opaque porcelain (alpha=.05). After the first and second dentin firings, the color shift in opaque porcelain was significant for all tested alloy groups (Palloy groups (P=.022 for B-ANP, P=.042 for N-VDSF, and Palloys). After glaze firing, the color change in opaque porcelain was significant in all but the N-CP2 group (P=.002 for N-VDSF, P=.014 for HN-GP, and Palloys

  2. A review of the effect of neutron irradiation on the deformation behaviour of copper and copper alloys

    International Nuclear Information System (INIS)

    Higgy, H.R.

    1976-08-01

    The basic mechanisms of irradiation hardening are described. The effects of neutron dose, alloying and pre-irradiation deformation on the deformation behaviour of neutron-irradiatied copper and its alloys are considered. The discrepancy in the reported data is discussed. Substitutional and interstitial additions are found to influence the rate of irradiation hardening, while pre-irradiation deformation has no influence. The deformation behaviour of copper is found to alter as a result of irradiation and alloying. (author)

  3. Magnetocaloric effect of Gd 5 Si 2 Ge 2 alloys in low magnetic field

    Indian Academy of Sciences (India)

    The magnetocaloric effect (MCE) is studied by measuring magnetic entropy change ( M) and adiabatic temperature change ( ad) in a magnetic field of 1.5 T using a vibrating sample magnetometer (VSM) and a home-made magnetocaloric effect measuring apparatus, respectively. The maximum M of the alloys ...

  4. Temperature effect on Sn-Bi alloy using ultrasonic pulse echo overlap method

    International Nuclear Information System (INIS)

    Mohammad Radzi Sudin; Mohd Salleh Mohd Deni; Mohd Khairi Saidin

    1996-01-01

    Sn-Bi alloy has a potential to replace toxic Sn-Pb welds. The effect of temperature up to melt point can be seen through changes of elasticity constant using Ultrasonic Pulse Echo overlap method. Although the effect of temperature will decrease the strength but there are no phase changes to stop it to be used as suitable welded material in electronic industry

  5. Shape memory effect of Fe-14% Mn-6% Si-9% Cr-6% Ni alloy polycrystals

    International Nuclear Information System (INIS)

    Inagaki, Hirosuke

    1992-01-01

    Factors affecting the shape memory effect in Fe-14% Mn-6% Si-9% Cr-6% Ni alloy polycrystals were studied in detail. It was found that the shape memory effect in this alloy was most influenced by the amount of deformation. With increasing amount of deformation, the shape memory effect diminished appreciably. Although the fraction of the initial dimensional change that could be restored was about 45% in the specimen strained by 4%, only 21% of the initial dimensional change was recovered in the specimen strained by 9%. Temperatures of deformation were found to be also an important factor that affected the shape memory effect. The maximum shape memory effect was observed in the specimens strained at temperatures between the M s and M d temperatures. In this alloy, however, specimens strained at temperatures below the M s temperature indicated a relatively large shape memory effect, too. It was further found that the shape memory effect was appreciably intensified by repeated straining and annealing, especially when straining was performed at 500deg C. It was suggested that the shape memory effect in Fe base alloys was strongly influenced by the dislocation substructure present in the starting material. (orig.) [de

  6. Effect of heat treatments on machinability of gold alloy with age-hardenability at intraoral temperature.

    Science.gov (United States)

    Watanabe, I; Baba, N; Watanabe, E; Atsuta, M; Okabe, T

    2004-01-01

    This study investigated the effect of heat treatment on the machinability of heat-treated cast gold alloy with age-hardenability at intraoral temperature using a handpiece engine with SiC wheels and an air-turbine handpiece with carbide burs and diamond points. Cast gold alloy specimens underwent various heat treatments [As-cast (AC); Solution treatment (ST); High-temperature aging (HA), Intraoral aging (IA)] before machinability testing. The machinability test was conducted at a constant machining force of 0.784N. The three circumferential speeds used for the handpiece engine were 500, 1,000 and 1,500 m/min. The machinability index (M-index) was determined as the amount of metal removed by machining (volume loss, mm(3)). The results were analyzed by ANOVA and Scheffé's test. When an air-turbine handpiece was used, there was no difference in the M-index of the gold alloy among the heat treatments. The air-turbine carbide burs showed significantly (pmachinability of the gold alloy using the air-turbine handpiece. The heat treatments had a small effect on the M-index of the gold alloy machined with a SiC wheel for a handpiece engine.

  7. Effect of ripple loads on sustained-load cracking in titanium alloys

    International Nuclear Information System (INIS)

    Pao, P.S.; Meyn, D.A.; Bayles, R.A.; Feng, C.R.; Yoder, G.R.

    1995-01-01

    In the present paper, the authors have extended their study on the effect of the ripple loads on the sustained-load cracking (SLC) behavior of two titanium alloys, Ti-6Al-4V (an α-β alloy) and Ti-15V-3Cr-3Al-3Sn (a β-α alloy), in an ambient air environment. The methodology which has been used successfully to treat ripple effects on stress-corrosion cracking (SCC) is employed again to address the influence of ripple loads on sustained-load cracking. Ripple loads can significantly reduce the apparent sustained load cracking resistance of titanium alloys in a relatively benign environment such as ambient air. For a ripple-load amplitude equal to 5% of the sustained load, the ripple-load cracking thresholds (K IRLC ) of beta-annealed Ti-6Al-4V and Ti-15V-3Cr-3al-3Sn are less than half of the respective sustained-load cracking thresholds (K ISLC ). The extent of ripple-load degradation for these alloys in ambient air -- relative to K ISLC , were found comparable to those observed in a much more aggressive 3.5% NaCl aqueous solution

  8. Effect of Rare Earth Metals on the Microstructure of Al-Si Based Alloys

    Directory of Open Access Journals (Sweden)

    Saleh A. Alkahtani

    2016-01-01

    Full Text Available The present study was performed on A356 alloy [Al-7 wt %Si 0.0.35 wt %Mg]. To that La and Ce were added individually or combined up to 1.5 wt % each. The results show that these rare earth elements affect only the alloy melting temperature with no marked change in the temperature of Al-Si eutectic precipitation. Additionally, rare earth metals have no modification effect up to 1.5 wt %. In addition, La and Ce tend to react with Sr leading to modification degradation. In order to achieve noticeable modification of eutectic Si particles, the concentration of rare earth metals should exceed 1.5 wt %, which simultaneously results in the precipitation of a fairly large volume fraction of insoluble intermetallics. The precipitation of these complex intermetallics is expected to have a negative effect on the alloy performance.

  9. Effect of hydrogen on the mechanical properties of titanium and its alloys

    Science.gov (United States)

    Beck, F. H.

    1975-01-01

    Occluded hydrogen resulting from cathodic charging of commercially pure titanium and titanium alloys, Ti-8Al-1Mo-1V and Ti-6Al-4V, was shown to cause embrittlement of the alloys. Embrittlement was a function of the interstitial hydrogen content rather than the amount of precipitated titanium hydride. The effects of hydrogen concentration on the critical strain for plastic instability along pure shear directions was determined for alloys Ti-8Al-1Mo-1V and Ti-5Al-2.5Sn. Hydrogen, in concentrations below that necessary for spontaneous hydride precipitation, increased the strain necessary for instability formation or instability failure. The strain rate sensitivity also increased with increasing hydrogen concentration. The effect of hydrogen on slip and twinning was determined for titanium single crystals. The critical resolved shear stress for prism slip was increased and the critical resolved shear stress for twinning was decreased with increasing hydrogen concentration.

  10. Effect of hydrogen on the corrosion behavior of the Mg–xZn alloys

    Directory of Open Access Journals (Sweden)

    Yingwei Song

    2014-09-01

    Full Text Available Hydrogen evolution reaction is inevitable during the corrosion of Mg alloys. The effect of hydrogen on the corrosion behavior of the Mg–2Zn and Mg–5Zn alloys is investigated by charging hydrogen treatment. The surface morphologies of the samples after charging hydrogen were observed using a scanning electron microscopy (SEM and the corrosion resistance was evaluated by polarization curves. It is found that there are oxide films formed on the surface of the charged hydrogen samples. The low hydrogen evolution rate is helpful to improve the corrosion resistance of Mg alloys, while the high hydrogen evolution rate can increases the defects in the films and further deteriorates their protection ability. Also, the charging hydrogen effect is greatly associated with the microstructure of Mg substrate.

  11. The effect of thermomechanical training on the microstructures of Fe-Mn-Si shape memory alloy

    International Nuclear Information System (INIS)

    Wang, D.F.; Chen, Y.R.; Gong, F.Y.; Liu, D.Z.; Liu, W.X.

    1995-01-01

    The shape memory effect and the microstructures of Fe-30Mn-6Si(wt%) alloy subjected to different training treatments have been studied in present paper. It has been found that the recovery strain increases significantly through the training treatment of 4% tensile pre-strain followed by recovery annealing at 700 C (treatment A) while the recovery strain decreases after the training treatment of 4% tensile pre-strain plus recovery annealing at 300 C (treatment B). The microstructures of the alloy after the above training treatments were investigated by TEM. It was found that the treatment A favoured the formation of oriented dislocations and stacking faults which results in the improvement of shape memory effect in Fe-Mn-Si alloy. (orig.)

  12. Effects of Er:YAG laser treatments on surface roughness of base metal alloys.

    Science.gov (United States)

    Kunt, Göknil Ergün; Güler, Ahmet Umut; Ceylan, Gözlem; Duran, Ibrahim; Ozkan, Pelin; Kirtiloğlu, Tuğrul

    2012-01-01

    We investigated the effects of different Er:YAG laser treatments on the surface roughness of base metal alloys. A total of 36 specimens were prepared of two base metal alloys (Wiron 99, Bellabond plus). The surfaces of the specimens were standardized by gradual wet grinding with 320-, 600-, 800- and 1,000-grit silicon carbide paper for 10 s each on a grinding machine at 300 rpm. Specimens of each alloy were randomly divided into six groups (n = 6) comprising a control group (group C), a group sandblasted with Al(2)O(3) powder at 60 psi for 10 s through a nozzle at a distance of 10 mm (group S), and four Er:YAG laser (Fotona AT) treatment groups. The laser treatment groups were as follows: 500 mJ, 10 Hz, 100 μs (group 500MSP); 500 mJ, 10 Hz, 300 μs (group 500SP); 400 mJ, 10 Hz, 100 μs (group 400MSP); and 400 mJ, 10 Hz, 300 μs (group 400SP). Surface roughness measurements (Ra) were performed using a profilometer. The data were analysed by two-way ANOVA, and mean values were compared using Tukey's HSD test (α = 0.05). According to the two-way ANOVA results, the base metal alloys and interaction between base metal alloy and surface treatment were not statistically significant different (p > 0.05), the surface treatments were significantly different (p metal alloy groups, no significant differences were observed among the control, 400MSP, and 400SP groups (p = 0.912), and these groups demonstrated the lowest Ra values. The highest Ra value was observed in group S (p laser treatment at 400 and 500 mJ/10 Hz is not an alternative method for surface roughening of base metal alloys.

  13. Effects of the addition of Co, Ni or Cr on the decolorization properties of Fe-Si-B amorphous alloys

    Science.gov (United States)

    Zhang, Changqin; Zhu, Zhengwang; Zhang, Haifeng

    2017-11-01

    Fe-based amorphous alloys show great potential in degrading azo dyes and other organic pollutants, and are widely investigated as a kind of environmental-friendly materials for wastewater remediation. In this paper, the effects of Co, Ni or Cr addition on the decolorization properties of Fe-Si-B amorphous alloys were studied, and the mechanism of their different effects was analyzed. Co addition could lower the activation energy of Fe-Si-B amorphous alloys in decolorizing azo dyes, and had no weakening effect on the decolorization capability of Fe-Si-B amorphous alloys. Ni addition led to partial crystallization of Fe-Si-B amorphous alloys, and the decolorization mechanism at low temperatures changed from chemical degradation to physical adsorption. Cr addition could enhance the corrosion resistance of Fe-Si-B amorphous alloys, but the amorphous alloys completely lost the decolorization capability no matter at lower or higher temperatures. The results of X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) indicated that the addition of Co, Ni or Cr could generate different surface structures that had significant influences on the decolorization process. Our work demonstrated that the effiecient decolorization of azo dyes by Fe-based alloys could be realized only when amorphous nature and incompact surface structure were simultaneously achieved for the alloys.

  14. Thermoelastic Stress Analysis: The Mean Stress Effect in Metallic Alloys

    Science.gov (United States)

    Gyekenyesi, Andrew L.; Baaklini, George Y.

    1999-01-01

    The primary objective of this study involved the utilization of the thermoelastic stress analysis (TSA) method to demonstrate the mean stress dependence of the thermoelastic constant. Titanium and nickel base alloys, commonly employed in aerospace gas turbines, were the materials of interest. The repeatability of the results was studied through a statistical analysis of the data. Although the mean stress dependence was well established, the ability to confidently quantify it was diminished by the experimental variations. If calibration of the thermoelastic response to mean stress can be successfully implemented, it is feasible to use the relationship to determine a structure's residual stress state.

  15. Simultaneous effect of mechanical alloying and arc-melting processes in the microstructure and hardness of an AlCoFeMoNiTi high-entropy alloy

    International Nuclear Information System (INIS)

    Baldenebro-Lopez, F.J.; Herrera-Ramírez, J.M.; Arredondo-Rea, S.P.; Gómez-Esparza, C.D.; Martínez-Sánchez, R.

    2015-01-01

    Highlights: • Multi-component systems of AlCoFeMoNiTi were produced by mechanical alloying. • Consolidated samples were fabricated by two different processing routes, sintering and arc melting. • Effect of routes of consolidation on microstructural evolution and microhardness is reported. • High hardness values are found in consolidated samples. • Alloying elements, grain size, and precipitates have a high effect on microhardness. - Abstract: A nanostructured AlCoFeMoNiTi high entropy alloy was synthesized through the mechanical alloying process. Bulk samples were obtained by two different routes to compare the microstructural evolution and hardness behavior: sintering and arc melting. Through electron microscopy analyses the formation of Mo-rich and Ti-rich phases were identified in the melted sample, while Ti-rich nano-precipitates were observed in the sintered sample. A higher microhardness value was achieved on the sintered sample than for the melted sample. The disadvantage of porosity in the sintered sample in comparison to the melted one was overcome by the hardening effect produced by the mechanical alloying

  16. Simultaneous effect of mechanical alloying and arc-melting processes in the microstructure and hardness of an AlCoFeMoNiTi high-entropy alloy

    Energy Technology Data Exchange (ETDEWEB)

    Baldenebro-Lopez, F.J. [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes 120, 31109 Chihuahua, Chih. (Mexico); Facultad de Ingeniería Mochis, Universidad Autónoma de Sinaloa, Prol. Ángel Flores y Fuente de Poseidón, S.N., 81223 Los Mochis, Sinaloa (Mexico); Herrera-Ramírez, J.M. [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes 120, 31109 Chihuahua, Chih. (Mexico); Arredondo-Rea, S.P. [Facultad de Ingeniería Mochis, Universidad Autónoma de Sinaloa, Prol. Ángel Flores y Fuente de Poseidón, S.N., 81223 Los Mochis, Sinaloa (Mexico); Gómez-Esparza, C.D. [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes 120, 31109 Chihuahua, Chih. (Mexico); Martínez-Sánchez, R., E-mail: roberto.martinez@cimav.edu.mx [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes 120, 31109 Chihuahua, Chih. (Mexico)

    2015-09-15

    Highlights: • Multi-component systems of AlCoFeMoNiTi were produced by mechanical alloying. • Consolidated samples were fabricated by two different processing routes, sintering and arc melting. • Effect of routes of consolidation on microstructural evolution and microhardness is reported. • High hardness values are found in consolidated samples. • Alloying elements, grain size, and precipitates have a high effect on microhardness. - Abstract: A nanostructured AlCoFeMoNiTi high entropy alloy was synthesized through the mechanical alloying process. Bulk samples were obtained by two different routes to compare the microstructural evolution and hardness behavior: sintering and arc melting. Through electron microscopy analyses the formation of Mo-rich and Ti-rich phases were identified in the melted sample, while Ti-rich nano-precipitates were observed in the sintered sample. A higher microhardness value was achieved on the sintered sample than for the melted sample. The disadvantage of porosity in the sintered sample in comparison to the melted one was overcome by the hardening effect produced by the mechanical alloying.

  17. Effects of Nd/Gd value on the microstructures and mechanical properties of Mg–Gd–Y–Nd–Zr alloys

    Directory of Open Access Journals (Sweden)

    Xuan Liu

    2016-09-01

    Full Text Available Four Mg–Gd–Y–Nd–Zr alloys were prepared by mold casting to investigate the effects of Nd/Gd ratios on microstructures and mechanical properties. The as-cast alloys mainly consist of α-Mg and β-Mg5(GdYNd. Volume fractions of the second phase increase and grains were slightly refined with the rising Nd/Gd ratio, when the alloying addition is equal. Meanwhile, fibers of second phase also increase in the extruded alloys when the Nd/Gd value increases. However, the Nd/Gd ratio could hardly influence the mechanical properties of the extruded alloys. The aging hardening response of the extruded alloy differs due to different Nd/Gd ratios. The potential mechanisms have also been discussed in detail.

  18. Effect of implantation of biodegradable magnesium alloy on BMP-2 expression in bone of ovariectomized osteoporosis rats

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yue, E-mail: 373073766@qq.com [Liaoning Medical University, 40 Songpo Road, Jinzhou, 121000 (China); Ren, Ling, E-mail: lren@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang, 110016 (China); Liu, Chang, E-mail: meixifan1971@163.com [Liaoning Medical University, 40 Songpo Road, Jinzhou, 121000 (China); Yuan, Yajiang, E-mail: yuan925@163.com [Liaoning Medical University, 40 Songpo Road, Jinzhou, 121000 (China); Lin, Xiao, E-mail: linx@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang, 110016 (China); Tan, Lili, E-mail: lltan@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang, 110016 (China); Chen, Shurui, E-mail: 272146792@qq.com [Liaoning Medical University, 40 Songpo Road, Jinzhou, 121000 (China); Yang, Ke, E-mail: kyang@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang, 110016 (China); Mei, Xifan, E-mail: meixifan1971@163.com [Liaoning Medical University, 40 Songpo Road, Jinzhou, 121000 (China)

    2013-10-01

    The study was focused on the implantation of a biodegradable AZ31 magnesium alloy into the femoral periosteal of the osteoporosis modeled rats. The experimental results showed that after 4 weeks implantation of AZ31 alloy in the osteoporosis modeled rats, the expression of BMP-2 in bone tissues of the rats was much enhanced, even higher than the control group, which should promote the bone formation and be beneficial for reducing the harmful effect of osteoporosis. Results of HE stains showed that the implantation of AZ31 alloy did not have obvious pathological changes on both the liver and kidney of the animal. - Highlights: • Mg alloy greatly increased expression of BMP-2 in osteoporosis modeled rat bone. • Mg alloy showed good biological safety. • Mg alloy is beneficial for reducing the symptom of osteoporosis.

  19. Effects of Ca on microstructure, mechanical and corrosion properties and biocompatibility of Mg-Zn-Ca alloys.

    Science.gov (United States)

    Yin, Ping; Li, Nian Feng; Lei, Ting; Liu, Lin; Ouyang, Chun

    2013-06-01

    Zn and Ca were selected as alloying elements to develop an Mg-Zn-Ca alloy system for biomedical application due to their good biocompatibility. The effects of Ca on the microstructure, mechanical and corrosion properties as well as the biocompatibility of the as-cast Mg-Zn-Ca alloys were studied. Results indicate that the microstructure of Mg-Zn-Ca alloys typically consists of primary α-Mg matrix and Ca₂Mg₆Zn₃/Mg₂Ca intermetallic phase mainly distributed along grain boundary. The yield strength of Mg-Zn-Ca alloy increased slightly with the increase of Ca content, whilst its tensile strength increased at first and then decreased. Corrosion tests in the simulated body fluid revealed that the addition of Ca is detrimental to corrosion resistance due to the micro-galvanic corrosion acceleration. In vitro hemolysis and cytotoxicity assessment disclose that Mg-5Zn-1.0Ca alloy has suitable biocompatibility.

  20. Effect Of Low-Temperature Annealing On The Properties Of Ni-P Amorphous Alloys Deposited Via Electroless Plating

    Directory of Open Access Journals (Sweden)

    Zhao Guanlin

    2015-06-01

    Full Text Available Amorphous Ni-P alloys were prepared via electroless plating and annealing at 200°C at different times to obtain different microstructures. The effects of low-temperature annealing on the properties of amorphous Ni-P alloys were studied. The local atomic structure of the annealed amorphous Ni-P alloys was analyzed by calculating the atomic pair distribution function from their X-ray diffraction patterns. The results indicate that the properties of the annealed amorphous Ni-P alloys are closely related to the order atomic cluster size. However, these annealed Ni-P alloys maintained their amorphous structure at different annealing times. The variation in microhardness is in agreement with the change in cluster size. By contrast, the corrosion resistance of the annealed alloys in 3.5 wt% NaCl solution increases with the decrease in order cluster size.

  1. Characterization of deformation mechanisms in zirconium alloys: effect of temperature and irradiation

    Science.gov (United States)

    Long, Fei

    Zirconium alloys have been widely used in the CANDU (CANada Deuterium Uranium) reactor as core structural materials. Alloy such as Zircaloy-2 has been used for calandria tubes; fuel cladding; the pressure tube is manufactured from alloy Zr-2.5Nb. During in-reactor service, these alloys are exposed to a high flux of fast neutron at elevated temperatures. It is important to understand the effect of temperature and irradiation on the deformation mechanism of zirconium alloys. Aiming to provide experimental guidance for future modeling predictions on the properties of zirconium alloys this thesis describes the result of an investigation of the change of slip and twinning modes in Zircaloy-2 and Zr-2.5Nb as a function of temperature and irradiation. The aim is to provide scientific fundamentals and experimental evidences for future industry modeling in processing technique design, and in-reactor property change prediction of zirconium components. In situ neutron diffraction mechanical tests carried out on alloy Zircaloy-2 at three temperatures: 100¢ªC, 300¢ªC, and 500¢ªC, and described in Chapter 3. The evolution of the lattice strain of individual grain families in the loading and Poisson's directions during deformation, which probes the operation of slip and twinning modes at different stress levels, are described. By using the same type of in situ neutron diffraction technique, tests on Zr-2.5Nb pressure tube material samples, in either the fast-neutron irradiated or un-irradiated condition, are reported in Chapter 4. In Chapter 5, the measurement of dislocation density by means of line profile analysis of neutron diffraction patterns, as well as TEM observations of the dislocation microstructural evolution, is described. In Chapter 6 a hot-rolled Zr-2.5Nb with a larger grain size compared with the pressure tubing was used to study the development of dislocation microstructures with increasing plastic strain. In Chapter 7, in situ loading of heavy ion

  2. On the effects of partial substitution of Co for Fe in FINEMET and Nb-containing HITPERM alloys

    CERN Document Server

    Blazquez, J S; Conde, C F; Conde, A; Greneche, J M

    2003-01-01

    A comparative study of the effects of partial substitution of Co for Fe on thermal stability, crystallization and magnetic properties of Co-containing FINEMET and HITPERM alloys series is presented. The difference in metalloid and Nb content between the two alloy series and the presence of Si in the nanocrystals in the case of FINEMET alloys appear as key parameters. A recrystallization process involving the alpha-Fe type phase in nanocrystalline alloys of both series is evident from thermomagnetic results as a significant decrease in magnetization at the second crystallization stage.

  3. Effect of Cr contents on the diffusion behavior of Te in Ni-based alloy

    Science.gov (United States)

    Jia, Yanyan; Li, Zhefu; Ye, Xiangxi; Liu, Renduo; Leng, Bin; Qiu, Jie; Liu, Min; Li, Zhijun

    2017-12-01

    The embrittlement of Ni-based structural alloys caused by fission production Te is one of the major challenges for molten salt reactors. It has been reported that solution element Cr can prevent the situation of intergranular cracks caused by Te. However, there is no detailed mechanism explanation on this phenomenon. In this study, the effect of Cr on Te diffusion in Ni-Cr binary system was investigated by diffusion experiments at 800 °C for 100 h. Results show that Te reacts with the alloy mainly forming Ni3Te2, and strip shaped Cr3Te4 is only found on the surface of Ni-15%Cr alloy. According to the discussion of thermodynamic chemical reaction process, Cr3Te4 exhibits the best stability and preferential formation compound in Te/Ni-Cr system as its Gibbs free energy of formation is the lowest. With the increase of Cr content in the alloy, the diffusion depth of Te along grain boundaries significantly decreases. Moreover, the formation process of reaction product and diffusion process are described. The diffusion of Te can be suppressed by high content of Cr in Ni-Cr alloy due to the formation of Cr3Te4 and thus the grain boundary is protected from Te corroding.

  4. Effect of Nb content on deformation behavior and shape memory properties of Ti–Nb alloys

    International Nuclear Information System (INIS)

    Tobe, H.; Kim, H.Y.; Inamura, T.; Hosoda, H.; Nam, T.H.; Miyazaki, S.

    2013-01-01

    Highlights: ► Reorientation of martensite variants occurred by the deformation of the {1 1 1} type I and 〈2 1 1〉 type II twins. ► Magnitude of twinning shear in Ti–20Nb is larger than that in Ti–23Nb. ► Ti–20Nb exhibited a higher stress for the reorientation of martensite variants when compared with Ti–23Nb. -- Abstract: Deformation behavior and shape memory properties of Ti–(20, 23) at.% Nb alloys in a single α″ martensite state were investigated. The Ti–20Nb alloy exhibited a higher stress for the reorientation of martensite variants when compared with the Ti–23Nb alloy. The recovery strain due to the shape memory effect in the Ti–20Nb alloy was smaller than that in the Ti–23Nb alloy. Transmission electron microscope (TEM) observation revealed that the reorientation of martensite variants occurred by the deformation of {1 1 1} type I and 〈2 1 1〉 type II twins. The Nb content dependence of the deformation behavior and shape memory properties was discussed considering the magnitude of twinning shear of the twins

  5. Investigation of processing effects on the corrosion resistance of Ti20Mo alloy in saline solutions

    International Nuclear Information System (INIS)

    Bolat, G.; Izquierdo, J.; Gloriant, T.; Chelariu, R.; Mareci, D.; Souto, R.M.

    2015-01-01

    Graphical abstract: - Highlights: • Alloy fabrication method affects both surface finish and corrosion resistance. • More porous surface finish and higher wettability produced by powder sintering. • Passive layer formed on sintered alloy breaks down in saline solution. • Increase in surface porosity facilitated electron transfer through the oxide film. • More corrosion resistant alloy produced by cold crucible levitation melting. - Abstract: The electrochemical properties of Ti20Mo alloys prepared using different fabrication procedures, namely cold crucible levitation melting (CCLM) and powder sintering, were investigated using linear potentiodynamic polarization and EIS measurements. The surface condition was established using AFM, with the observation of a more porous surface finish in the case of powder sintering. A major effect of surface conditioning on the corrosion resistance of Ti20Mo alloys was observed, where the compact finish exhibits a superior corrosion resistance in chloride-containing saline solutions. Less insulating surfaces towards electron exchange resulted for the more porous finish as revealed by scanning electrochemical microscopy (SECM)

  6. Effects of acidity and alkalinity on corrosion behaviour of Al-Zn-Mg based anode alloy

    Science.gov (United States)

    Ma, Jingling; Wen, Jiuba; Li, Quanan; Zhang, Qin

    2013-03-01

    Effects of 1 M HCl, 0.6 M NaCl with different pH values and 4 M NaOH solutions on the corrosion behaviour of Al-5Zn-1Mg-0.02In-0.05Ti-0.5Mn (wt%) alloy have been investigated using measurements of self-corrosion, potentiodynamic polarization, cyclic polarization experiment combined with open circuit potential technique and scanning electron microscopy. The corrosion behaviour of the alloy was found to be dependant on the Cl-, OH- ions and pH value. In acidic or slightly neutral solutions, general and pitting corrosion occurred simultaneously. In contrast, exposure to alkaline solutions results in general corrosion which was traced back to the dissolution of the resistive oxidation film on the surface of the alloy. Experience revealed that the alloy was susceptible to pitting corrosion in all chloride solution. The alloy undergoes two types of localized corrosion process, leading to the formation of hemispherical and crystallographic pits. Polarization resistance measurements which are in good agreement with those of self-corrosion, show that the corrosion kinetic is minimized in slightly neutral solutions (pH = 7).

  7. Effect of two-step aging on the mechanical properties of AA2219 DC cast alloy

    Energy Technology Data Exchange (ETDEWEB)

    Elgallad, E.M., E-mail: eelgalla@uqac.ca; Zhang, Z.; Chen, X.-G.

    2015-02-11

    With its combination of high specific strength, good machinability and excellent weldability, AA2219 direct chill (DC) cast alloy has become a new category of materials for manufacturing large molds for the plastics and automotive industries. The effect of two-step aging on the microstructural evolution and mechanical properties of AA2219 DC cast alloy was investigated. The precipitate microstructure was characterized under different heat treatment conditions using differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). The poor mechanical properties of the air-quenched alloy were attributed to the presence of quench-induced coarse θ′ and θ precipitates, which had very limited contribution to the precipitation hardening during the aging treatment. The two-step aging treatment of the air-quenched AA2219 alloy involved the precipitation of GP zones in the first step followed by their transformation into fine θ″ strengthening precipitates in the second step, which considerably improved the mechanical properties. After undergoing 120 °C/36 h+190 °C/8 h two-step aging, the hardness, YS and UTS of the air-quenched alloy were increased by 27%, 46% and 15%, respectively, compared with 190 °C/8 h one-step aging.

  8. The Al Effects of Co-Free and V-Containing High-Entropy Alloys

    Directory of Open Access Journals (Sweden)

    Songqin Xia

    2017-01-01

    Full Text Available In this study, five-component high-entropy alloys (HEAs AlxCrFeNiV (where x denotes the molar ratio, x = 0, 0.1, 0.3, 0.5, 0.75, 1, and 1.5 were prepared using an arc-melting furnace. The effects of the addition of the Al on the crystal structures were investigated using X-ray diffraction (XRD, scanning electron microscopy (SEM, and transmission electron microscopy (TEM. Also, two non-equiatomic ratio HEAs, AlxCrFeNiV (x = 0.3, and 0.5, were systematically studied through the use of various characterization methods in the as-cast state. The Al0.3CrFeNiV alloy displayed typical duplex body-centered cubic (BCC structures, including disordered BCC (A2, and NiAl-type ordered BCC (B2 phases. Meanwhile, in regard to the Al0.5CrFeNiV alloy, this alloy was found to contain an unknown phase which was enriched in Cr and V, as well as the coherent A2/B2 phases. Both of these alloys displayed very high yield and fracture strengths. However, their compression fracture strains were approximately 10%. Also, the fracture surfaces showed mainly cleavage fracture modes.

  9. EFFECTS OF IRRADIATION ON THERMAL CONDUCTIVITY OF ALLOY 690 AT LOW NEUTRON FLUENCE

    Directory of Open Access Journals (Sweden)

    WOO SEOG RYU

    2013-04-01

    Full Text Available Alloy 690 has been selected as a steam generator tubing material for SMART owing to a near immunity to primary water stress corrosion cracking. The steam generators of SMART are faced with a neutron flux due to the integrated arrangement inside a reactor vessel, and thus it is important to know the irradiation effects of the thermal conductivity of Alloy 690. Alloy 690 was irradiated at HANARO to fluences of (0.7−28 × 1019n/cm2 (E>0.1MeV at 250°C, and its thermal conductivity was measured using the laser-flash equipment in the IMEF. The thermal conductivity of Alloy 690 was dependent on temperature, and it was a good fit to the Smith-Palmer equation, which modified the Wiedemann-Franz law. The irradiation at 250°C did not degrade the thermal conductivity of Alloy 690, and even showed a small increase (1% at fluences of (0.7∼28 × 1019n/cm2 (E>0.1MeV.

  10. Extracting E versus k⃗ effective band structure from supercell calculations on alloys and impurities

    Science.gov (United States)

    Popescu, Voicu; Zunger, Alex

    2012-02-01

    The supercell approach to defects and alloys has circumvented the limitations of those methods that insist on using artificially high symmetry, yet this step usually comes at the cost of abandoning the language of E versus k⃗ band dispersion. Here we describe a computational method that maps the energy eigenvalues obtained from large supercell calculations into an effective band structure (EBS) and recovers an approximate E(k⃗) for alloys. Making use of supercells allows one to model a random alloy A1-xBxC by occupying the sites A and B via a coin-toss procedure, affording many different local environments (polymorphic description) to occur. We present the formalism and implementation details of the method and apply it to study the evolution of the impurity band appearing in the dilute GaN:P alloy. We go beyond the perfectly random case, realizing that many alloys may have nonrandom microstructures, and investigate how their formation is reflected in the EBS. It turns out that the EBS is extremely sensitive in determining the critical disorder level for which delocalized states start to appear in the intermediate band. In addition, the EBS allows us to identify the role played by atomic relaxation in the positioning of the impurity levels.

  11. Thermoelastic martensite and shape memory effect in ductile Cu-Al-Mn alloys

    Science.gov (United States)

    Kainuma, R.; Takahashi, S.; Ishida, K.

    1996-08-01

    Ductile shape memory (SM) alloys of the Cu-AI-Mn system have been developed by controlling the degree of order in the β phase. Additions of Mn to the binary Cu-Al alloy stabilize the β phase and widen the single-phase region to lower temperature and lower Al contents. It is shown that Cu-Al-Mn alloys with low Al contents have either the disordered A2 structure or the ordered L21 structure with a lower degree of order and that they exhibit excellent ductility. The disordered A2 phase martensitically transforms to the disordered Al phase with a high density of twins. The martensite phase formed from the ordered L21 phase has the 18R structure. The SM effect accompanies both the A2 → Al and L21 → 18R martensitic transformations. These alloys exhibit 15 pct strain to failure, 60 to 90 pct rolling reduction without cracking, and 80 to 90 pct recovery from bend test in the martensitic condition. Experimental results on the microstructure, crystal structure, mechanical properties, and shape memory behavior in the ductile Cu-AI-Mn alloys are presented and discussed.

  12. The effect of hydrogen peroxide concentration on metal ion release from dental casting alloys.

    Science.gov (United States)

    Al-Salehi, S K; Hatton, P V; Johnson, A; Cox, A G; McLeod, C

    2008-04-01

    There are concerns that tooth bleaching agents may adversely affect dental materials. The aim of this study was to test the hypothesis that increasing concentrations of hydrogen peroxide (HP) are more effective than water at increasing metal ion release from two typical dental casting alloys during bleaching. Discs (n = 28 for each alloy) were prepared by casting and heat treated to simulate a typical porcelain-firing cycle. Discs (n = 7) of each alloy were immersed in either 0%, 3%, 10% or 30% (w/v) HP solutions for 24 h at 37 degrees C. Samples were taken for metal ion release determination using inductively coupled plasma-mass spectrometry and the data analysed using a two-way anova followed by a one-way anova. The surface roughness of each disc was measured using a Talysurf contact profilometer before and after bleaching and the data analysed using a paired t-test. With the exception of gold, the differences in metal ion concentration after treatment with 0% (control) and each of 3%, 10% and 30% HP (w/v) were statistically significant (P Metal ion release from the two alloys increased with increasing HP concentrations (over 3000% increase in Ni and 1400% increase in Pd ions were recorded when HP concentration increased from 0% to 30%). Surface roughness values of the samples before and after bleaching were not significantly different (P > 0.05) Exposure of the two dental casting alloys to HP solutions increased metal ion release of all the elements except gold.

  13. The effect of remelting various combinations of new and used cobalt-chromium alloy on the mechanical properties and microstructure of the alloy.

    Science.gov (United States)

    Gupta, Sharad; Mehta, Aruna S

    2012-01-01

    Remelting previously cast base metal alloy can adversely affect the mechanical properties of the alloy and necessitates addition of new alloy. To study the effect of remelting different combinations of new and used cobalt-chromium (Co-Cr) alloy on its mechanical properties and microstructure. Using induction casting, 24 tensile test specimens were prepared for eight different combinations of new and used Co-Cr alloy. The test specimens were assessed for yield strength and percentage elongation. Microhardness was evaluated using Vickers's hardness tester. The tensile testing was carried out on a 50 kN servo-hydraulic universal testing machine. Microstructure analysis was done using an optical photomicroscope on the fractured samples after acid etching. The mean values (±standard deviation) and coefficient of variation were calculated. Student's 't' test was used for statistical analysis. Statistical significance was assumed at P=.05. The mean yield strength of eight different combination groups were as follows: group A: 849 MPa, group B ₁ : 834 MPa, group B ₂ : 915 MPa, group B ₃ : 897 MPa, group C ₁ : 874 MPa, group C ₂ : 859 MPa, group D ₁ : 845 MPa, and group D ₂ : 834 MPa. The mean percentage elongation for the different groups were as follows: group A: 7%, group B ₁ : 7%, group B ₂ : 8%, group B ₃ : 7%, group C ₁ : 8%, group C ₂ : 7%, group D ₁ : 7%, and group D 2 : 8%. The mean hardness values were as follows: group A: 373 VHN, group B ₁ : 373 VHN, group B ₂ : 346 VHN, group B ₃ : 346 VHN, group C ₁ : 364 VHN, group C ₂ : 343 VHN, group D ₁ : 376 VHN, and group D ₂ : 373 VHN. Repeated remelting of base metal alloy for dental casting without addition of new alloy can affect the mechanical properties of the alloy. Microstructure analysis shows deterioration upon remelting. However, the addition of 25% and 50% (by weight) of new alloy to the remelted alloy can bring about improvement both in mechanical properties and in

  14. Effect of Microstructure and Alloy Chemistry on Hydrogen Embrittlement of Precipitation-Hardened Ni-Based Alloys

    Science.gov (United States)

    Obasi, G. C.; Zhang, Z.; Sampath, D.; Morana, Roberto; Akid, R.; Preuss, M.

    2018-02-01

    The sensitivity to hydrogen embrittlement (HE) has been studied in respect of precipitation size distributions in two nickel-based superalloys: Alloy 718 (UNS N07718) and Alloy 945X (UNS N09946). Quantitative microstructure analysis was carried out by the combination of scanning and transmission electron microscopy and energy dispersive x-ray spectroscopy (EDS). While Alloy 718 is mainly strengthened by γ″, and therefore readily forms intergranular δ phase, Alloy 945X has been designed to avoid δ formation by reducing Nb levels providing high strength through a combination of γ' and γ″. Slow strain rate tensile tests were carried out for different microstructural conditions in air and after cathodic hydrogen (H) charging. HE sensitivity was determined based on loss of elongation due to the H uptake in comparison to elongation to failure in air. Results showed that both alloys exhibited an elevated sensitivity to HE. Fracture surfaces of the H precharged material showed quasi-cleavage and transgranular cracks in the H-affected region, while ductile failure was observed toward the center of the sample. The crack origins observed on the H precharged samples exhibited quasi-cleavage with slip traces at high magnification. The sensitivity is slightly reduced for Alloy 718, by coarsening γ″ and reducing the overall strength of the alloy. However, on further coarsening of γ″, which promotes continuous decoration of grain boundaries with δ phase, the embrittlement index rose again indicating a change of hydrogen embrittlement mechanism from hydrogen-enhanced local plasticity (HELP) to hydrogen-enhanced decohesion embrittlement (HEDE). In contrast, Alloy 945X displayed a strong correlation between strength, based on precipitation size and embrittlement index, due to the absence of any significant formation of δ phase for the investigated microstructures. For the given test parameters, Alloy 945X did not display any reduced sensitivity to HE compared with

  15. Effect of Microstructure and Alloy Chemistry on Hydrogen Embrittlement of Precipitation-Hardened Ni-Based Alloys

    Science.gov (United States)

    Obasi, G. C.; Zhang, Z.; Sampath, D.; Morana, Roberto; Akid, R.; Preuss, M.

    2018-04-01

    The sensitivity to hydrogen embrittlement (HE) has been studied in respect of precipitation size distributions in two nickel-based superalloys: Alloy 718 (UNS N07718) and Alloy 945X (UNS N09946). Quantitative microstructure analysis was carried out by the combination of scanning and transmission electron microscopy and energy dispersive x-ray spectroscopy (EDS). While Alloy 718 is mainly strengthened by γ″, and therefore readily forms intergranular δ phase, Alloy 945X has been designed to avoid δ formation by reducing Nb levels providing high strength through a combination of γ' and γ″. Slow strain rate tensile tests were carried out for different microstructural conditions in air and after cathodic hydrogen (H) charging. HE sensitivity was determined based on loss of elongation due to the H uptake in comparison to elongation to failure in air. Results showed that both alloys exhibited an elevated sensitivity to HE. Fracture surfaces of the H precharged material showed quasi-cleavage and transgranular cracks in the H-affected region, while ductile failure was observed toward the center of the sample. The crack origins observed on the H precharged samples exhibited quasi-cleavage with slip traces at high magnification. The sensitivity is slightly reduced for Alloy 718, by coarsening γ″ and reducing the overall strength of the alloy. However, on further coarsening of γ″, which promotes continuous decoration of grain boundaries with δ phase, the embrittlement index rose again indicating a change of hydrogen embrittlement mechanism from hydrogen-enhanced local plasticity (HELP) to hydrogen-enhanced decohesion embrittlement (HEDE). In contrast, Alloy 945X displayed a strong correlation between strength, based on precipitation size and embrittlement index, due to the absence of any significant formation of δ phase for the investigated microstructures. For the given test parameters, Alloy 945X did not display any reduced sensitivity to HE compared with

  16. Effect of Eu addition on the microstructures and mechanical properties of A356 aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Feng; Yan, Guangyuan; Xuan, Zhenjing [Key Laboratory of Materials Modification by Laser, Ion, and Electron Beams (Ministry of Education), School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Cao, Zhiqiang, E-mail: caozq@dlut.edu.cn [Laboratory of Special Processing of Raw Materials, Dalian University of Technology, Dalian 116024 (China); Wang, Tongmin, E-mail: tmwang@dlut.edu.cn [Key Laboratory of Materials Modification by Laser, Ion, and Electron Beams (Ministry of Education), School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China)

    2015-11-25

    The effect of Eu additions (0, 0.02, 0.04, 0.06, 0.08 and 0.1 wt.%) and T6 heat treatment on the microstructures and mechanical properties of A356 alloy have been investigated in the present work. Microstructures of the as-cast and T6 heat treated samples were examined by optical microscopy (OM) and scanning electron microscopy (SEM). It was found that 0.1%Eu modified the eutectic Si from a coarse plate-like form to a fully modified and fine fibrous one with a better uniform distribution. T6 treatment encouraged the spheroidization of eutectic Si particles. Correlating with the as-cast samples, the 0.1%Eu modified A356 alloy achieved likewise full modification of eutectic Si particles with lowest mean area and aspect ratio. In addition, the coarse and small Eu-rich intermetallics were both found in the 0.1%Eu modified A356 alloy. The cooling curves of A356 alloys showed that increasing Eu addition resulted in increasing nucleation undercooling and increasing growth undercooling. However, the recalescence (T{sub G} − T{sub Min}) increased by the initial addition of Eu, while it remained relatively stable for increasing additions (above 0.06%). The quenching experiment indicated that a large number of eutectic grains were located at or close to the tips of the aluminum dendrites with a jagged solid–liquid interface in unmodified alloy, while very few eutectic grains were formed in the interdendritic region with a smooth solid–liquid interface in 0.1%Eu modified alloy. An optimal combination of UTS (265 MPa) and EI (14.7%) of A356 alloy was achieved by the 0.1%Eu addition combined with T6 heat treatment. - Highlights: • The rare earth Eu is firstly used to improve the mechanical property of A356 alloy. • A fully modified and fine fibrous eutectic Si is observed by addition of 0.1 wt% Eu. • A complete spheroidization of 0.1wt%Eu modified eutectic Si is observed after T6. • Three kinds of Eu-rich intermetallics are found in the 0.1%Eu modified A356 alloy

  17. Effect of alloying on the properties of the Nb3Sn compound

    International Nuclear Information System (INIS)

    Efimov, Yu.V.; Mikhajlov, B.P.; Moroz, E.A.

    1979-01-01

    The effect of some alloying elements upon the structure and the superconducting properties of Nb 3 Sn was studied. The superconductivity transition point was determined from the variation of the magnetic susceptibility at temperatures above 4.2 K +-0.1K. The alloying of Nb 3 Sn by vanadium, molybdenum, titanium, zirconium, scandium, sodium silicon, tin, copper, carbon or oxygen was found to lower the superconductivity transition point. The drop in Tsub(k) correlates with the maximum solubility of the alloying element. Small additions of aluminium, gallium, germanium or indium give raise to Tsub(k) of Nb 3 Sn. Elements, poorly soluble in Nb 3 Sn (yttrium, scandium, copper) raise the critical current of the coats, whereas elements with a high solubility in this compound, lower the critical current

  18. Studying Si/SiGe disordered alloys within effective mass theory

    Science.gov (United States)

    Gamble, John; Montaño, Inès; Carroll, Malcolm S.; Muller, Richard P.

    Si/SiGe is an attractive material system for electrostatically-defined quantum dot qubits due to its high-quality crystalline quantum well interface. Modeling the properties of single-electron quantum dots in this system is complicated by the presence of alloy disorder, which typically requires atomistic techniques in order to treat properly. Here, we use the NEMO-3D empirical tight binding code to calibrate a multi-valley effective mass theory (MVEMT) to properly handle alloy disorder. The resulting MVEMT simulations give good insight into the essential physics of alloy disorder, while being extremely computationally efficient and well-suited to determining statistical properties. Sandia is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under Contract No. DE-AC04-94AL85000.

  19. 3D study of intermetallics and their effect on the corrosion morphology of rheocast aluminium alloy

    International Nuclear Information System (INIS)

    Mingo, B.; Arrabal, R.; Pardo, A.; Matykina, E.; Skeldon, P.

    2016-01-01

    In the present study, the effect of heat treatment T6.1 on the microstructure and corrosion behaviour of rheocast aluminium alloy A356 is investigated on the basis of 2D/3D characterization techniques and electrochemical and SKPFM measurements. Heat treatment strengthens the α-Al matrix, modifies the intermetallic particles and spheroidizes eutectic Si. These changes do not modify significantly the corrosion behaviour of the alloy. 3D SEM-Tomography clearly shows that the corrosion advances in the shape of narrow paths between closely spaced intermetallics without a major influence of eutectic Si. - Highlights: • T6.1 spheroidizes Si, strengthens the matrix and modifies the intermetallics. • Electrochemical behaviour of untreated and heat-treated alloys is similar. • 3D SEM-Tomography provides additional information on the corrosion morphology. • Corrosion advances as paths between intermetallics with little influence of Si.

  20. Annealing Effect on Corrosion Behavior of the Beta-Quenched HANA Alloy

    International Nuclear Information System (INIS)

    Kim, Hyun Gil; Kim, Il Hyun; Choi, Byung Kwan; Park, Sang Yoon; Park, Jeong Yong; Jeong, Yong Hwan

    2009-01-01

    The advanced fuel cladding materials named as HANA cladding have been developed at KAERI for application of high burn-up and that cladding showed an improved performance in both in-pile and out-of-pile conditions. However, the cladding performance could be changed by the annealing conditions during the tube manufacturing process. Especially, the corrosion resistance is considerably sensitive to their microstructure which is determined by a manufacturing process in the high Nb-containing zirconium alloys. They reported that the corrosion properties of the Nb-containing Zr alloys were considerably affected by the microstructure conditions such as the Nb concentration in the matrix and the second phase types. Therefore, the corrosion behavior of HANA cladding having the high Nb could be considerably affected by the annealing time and temperatures. The purpose of this study is focused on the annealing effect of the beta quenched HANA alloy to obtain the optimum annealing conditions

  1. Effect and kinetic mechanism of ultrasonic vibration on solidification of 7050 aluminum alloy

    Directory of Open Access Journals (Sweden)

    Ripeng Jiang

    2014-07-01

    Full Text Available The work described in this paper dealt with the effect of ultrasonic vibration on the solidification of 7050 aluminum alloy. Two experiments were carried out through introducing ultrasound into the semi-continuous direct-chill (DC casting of aluminum alloy and into alloy solidifying in a crucible, respectively. Results show that ultrasonic vibration can refine grains in the whole cross-section of a billet in the first experiment and is able to increase the cooling rate within the temperature range from 625 °C to 590 °C in the other one. The mechanism of particle resonance caused by ultrasonic vibration was illustrated on the basis of theoretical analysis of the kinetics and energy conversion during the solidification. It is demonstrated that the kinetic energy of resonant particles are mainly from the latent heat energy of solidification, which can shorten the cooling time, inhibit the crystal growth and then lead to the grain refinement.

  2. 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 (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.

  3. Effect of alloying elements on austempered ductile iron (ADI properties and its process: Review

    Directory of Open Access Journals (Sweden)

    Amir Sadighzadeh Benam

    2015-01-01

    Full Text Available Austempered ductile iron (ADI parts have a unique combination of high strength and toughness with excellent design flexibility and low cost. These excellent properties are directly related to its microstructure called "ausferrite" that is the result of austempering heat treatment applied to ductile irons. Alloying elements increase ADI austemperability and change speeds of austempering reactions. Thus, they can affect ADI resultant microstructure and mechanical properties. In this paper, the effects of alloying elements on ADI mechanical properties, microstructural changes, two-stage austempering reactions, processing windows, austemperability, and other aspects are reviewed.

  4. EFFECT OF THE TEMPERATURE ON THE FRICTION AND WEAR PROPERTIES OF BULK AMORPHOUS ALLOY

    OpenAIRE

    DAWIT ZENEBE SEGU; PYUNG HWANG; SEOCK-SAM KIM

    2014-01-01

    The present paper report the results of an experimental investigation of the temperature effect on the sliding friction and wear properties of the bulk metallic glass (BMG). To improve the friction and wear properties of the BMG, the disk specimens were developed in the alloy system of Fe67.6C7.1Si3.3B5.5P8.7Cr2.3Mo2.6Al2Co1.0 using hot metal and industrial ferro-alloys. The friction and wear test was performed using flat-on-flat contact configuration of unidirectional tribometer and Si3N4 ce...

  5. Effects of organic acid pickling on the corrosion resistance of magnesium alloy AZ31 sheet

    DEFF Research Database (Denmark)

    Nwaogu, Ugochukwu Chibuzoh; Blawert, C.; Scharnagl, N.

    2010-01-01

    Organic acids were used to clean AZ31 magnesium alloy sheet and the effect of the cleaning processes on the surface condition and corrosion performance of the alloy was investigated. Organic acid cleanings reduced the surface impurities and enhanced the corrosion resistance. Removal of at least 4...... mu m of the contaminated surface was required to reach corrosion rates less than 1 mm/year in salt spray condition. Among the three organic acids examined, acetic acid is the best choice. Oxalic acid can be an alternative while citric acid is not suitable for cleaning AZ31 sheet, because...

  6. Effect of ageing time and temperature on corrosion behaviour of aluminum alloy 2014

    Science.gov (United States)

    Gadpale, Vikas; Banjare, Pragya N.; Manoj, Manoranjan Kumar

    2018-03-01

    In this paper, the effect of corrosion behaviour of aluminium alloy 2014 were studied by potentiodynamic polarization in 1 mole of NaCl solution of aged sample. The experimental testing results concluded that, corrosion resistance of Aluminum alloy 2014 degraded with the increasing the temperature (150°C & 200°C) and time of ageing. Corroded surface of the aged specimens was tested under optical microscopes for microstructures for phase analysis. Optical micrographs of corroded surfaces showed general corrosion and pitting corrosion. The corrosion resistance of lower ageing temperature and lower ageing time is higher because of its fine distribution of precipitates in matrix phase.

  7. Effects of lead on oxidation behavior of Alloy 690TT within a high temperature aqueous environment

    Science.gov (United States)

    Hou, Qiang; Liu, Zhiyong; Li, Chengtao; Li, Xiaogang

    2017-12-01

    The chemical compositions, phases and structures of two oxide films on Alloy 690TT following exposure for 4400 h in pure water with and without lead at 320 °C were studied by surface analysis techniques. The analysis of a lead-doped oxide film prepared by a focused ion beam (FIB) demonstrated that both Cr-rich and Ni-rich oxides were alternatively distributed within the outer layer, whereas the inner layer was porous and poorly protected, causing severe corrosion of the alloy and a thicker film was formed. A duplex film model was proposed for the effects discussion of lead on the oxidation mechanism.

  8. Effects of Y, Nd and Sb on microstructure of Mg-6Al alloy

    Science.gov (United States)

    Li, Ke-jie

    2017-09-01

    Effects of Y, Nd and Sb on the microstructure of Mg-6Al magnesium alloy were investigated by optical microscope, SEM, EDS, XRD and TEM. The results showed that, with the increase of Sb content from 0.5% to 2.0wt%, the formation of Sb3Y5 (at 1.0% Sb) or YSb (at 2.0% Sb) phase is observed. Sb3Y5 nano-phase and dispersed Al2Y, SbY phases are found in the alloy when the content of Sb reaches 2.0%.

  9. Thermal conductivity prediction of closed-cell aluminum alloy considering micropore effect

    Directory of Open Access Journals (Sweden)

    Donghui Zhang

    2015-02-01

    Full Text Available Large quantities of micro-scale pores are observed in the matrix of closed-cell aluminum alloy by scanning electron microscope, which indicates the dual-scale pore characteristics. Corresponding to this kind of special structural morphology, a new kind of dual-scale method is proposed to estimate its effective thermal conductivity. Comparing with the experimental results, the article puts forward the view that the prediction accuracy can be improved by the dual-scale method greatly. Different empirical formulas are also investigated in detail. It provides a new method for thermal properties estimation and makes preparation for more suitable empirical formula for closed-cell aluminum alloy.

  10. Effect of stacking fault energy on high-temperature creep parameters of nickel-cobalt alloys

    International Nuclear Information System (INIS)

    Nerodenko, L.M.; Dabizha, E.V.

    1982-01-01

    Results of creep investigation are discussed for two alloys of the Ni-Co system. In terms of the structural creep model an analysis is made for the effect of stacking fault energy on averaged parameters of the dislocation structure: inovable dislocation density subgrain size, activation volume. The rate of steady-state creep is determined by the process of dislocation passing through the subgrain boundaries with activation energy of 171.0 and 211.5 kJ/mol for the Ni-25% Co and Ni-65% Co alloys, respectively

  11. Effects of biodegradable Mg–6Zn alloy extracts on apoptosis of intestinal epithelial cells

    International Nuclear Information System (INIS)

    Wang Zhanhui; Yan Jun; Li Jianan; Zheng Qi; Wang Zhigang; Zhang Xiaonong; Zhang Shaoxiang

    2012-01-01

    Highlights: ► We evaluated the effects of Mg–6Zn alloys on apoptosis of IEC-6 cells. ► The apoptosis was evaluated by investigating the expression of caspase-1 and Bcl-2. ► The IEC-6 cells displayed better cell functions in 60% or 20% extract. ► The conspicuous alkaline environment is disadvantageous to apoptosis of IEC cells. ► The excessive Mg concentration is disadvantageous to apoptosis of IEC-6 cells. - Abstract: In this study, intestinal epithelial cells (IEC)-6 were cultured in different concentration extracts of Mg–6Zn alloys for different time periods. To achieve a total of three concentrations (100%, 60% and 20% concentration), the extracts were serially diluted with Dulbecco's modified Eagle medium High Glucose to observe a dose–response relationship. We studied the indirect effects of Mg–6Zn alloys on IEC-6 cells apoptosis. The apoptosis of IEC-6 cells was measured using flow cytometry. And the apoptosis of IEC-6 cells was evaluated by investigating the expression of caspase-1and Bcl-2 using real-time polymerase chain reaction (PCR) and Western blotting tests. It was found that the levels of apoptosis in IEC-6 cells cultured in 100% Mg–6Zn alloy extracts were significantly higher than those in 60% and 20% extracts; the 100% extract can down-regulate expression of Bcl-2 after culture. The in vitro results indicated that the conspicuous alkaline environment and excessive Mg concentration, even Zn concentration caused by rapid corrosion of Mg–6Zn alloys promote IEC-6 cells apoptosis, although further experiments will be necessary to formally prove our conclusions. Therefore, the adjustment of the degradation rate is needed for using Mg–Zn alloy as a surgical suture material.

  12. Effect of ethyl vanillin on ZnNi alloy electrodeposition and its properties

    Indian Academy of Sciences (India)

    Administrator

    The brightener enhances current efficiency and throwing power of plating bath during coating. ... effect of deposition current density and thickness on corrosion behaviour of coating was examined. Keywords. Corrosion resistance ..... thickness indicating pore-free nature of alloy deposits. Figure 7. Microhardness of dull and ...

  13. Effects of surface finishing conditions on the biocompatibility of a nickel-chromium dental casting alloy.

    LENUS (Irish Health Repository)

    McGinley, Emma Louise

    2011-07-01

    To assess the effects of surface finishing condition (polished or alumina particle air abraded) on the biocompatibility of direct and indirect exposure to a nickel-chromium (Ni-Cr) d.Sign®10 dental casting alloy on oral keratinocytes. Biocompatibility was performed by assessing cellular viability and morphology, metabolic activity, cellular toxicity and presence of inflammatory cytokine markers.

  14. Effect of porosity on the tensile properties of low ductility aluminum alloys

    Directory of Open Access Journals (Sweden)

    Gustavo Waldemar Mugica

    2004-06-01

    Full Text Available The literature contains reports of several studies correlating the porosity and mechanical properties of aluminum alloys. Most of these studies determine this correlation based on the parameter of global volumetric porosity. These reports, however, fail to separate the effects of microstructural features and porosity on alloys, though recognizing the influence of the latter on their mechanical properties. Thus, when the decrease in tensile strength due to the porosity effect is taken into account, the findings are highly contradictory. An analysis was made of the correlation between mechanical properties and global volumetric porosity and volumetric porosity in the fracture, as well as of the beta-Al5FeSi phase present in 380 aluminum alloy. Our findings indicate that mechanical properties in tension relating to global volumetric porosity lead to overestimations of the porosity effect in detriment to the mechanical properties. Moreover, the proposed models that take into account the effects of particles, both Si and beta-Al5FeSi, are unapplicable to low ductility alloys.

  15. Effect of hydrogen on mechanical properties of β-titanium alloys

    Indian Academy of Sciences (India)

    M. Senthilkumar (Newgen Imaging) 1461 1996 Oct 15 13:05:22

    Abstract. Conflicting opinions exist in the literature on the manner in which hydrogen influences the mechanical properties of β-titanium alloys. This can be attributed to the β-stabilizing effect of hydrogen in these materials leading to major changes in the microstructure as a result of hydrogen charging. The resulting.

  16. Effect of alloying with zinc on SFE of aluminium by study of lattice ...

    Indian Academy of Sciences (India)

    '' are absent in the cold worked state and twin fault is found to be slightly present in the deformed lattice of the two initial compositions of the alloys. Similar to the effect of solute germanium and copper, respectively in Al–Ge and Al–Cu ...

  17. Effect of alloy type and surface conditioning on roughness and bond strength of metal brackets

    NARCIS (Netherlands)

    Nergiz, I.; Schmage, P.; Herrmann, W.; Ozcan, M.; Nergiz, [No Value

    2004-01-01

    The effect of 5 different surface conditioning methods on bonding of metal brackets to cast dental alloys was examined. The surface conditioning methods were fine (30-µm) or rough (125-µm) diamond bur, sandblasting (50-µm or 110-µm aluminum oxide [Al2O3]), and silica coating (30-µm silica). Fifty

  18. Relative effects of chromium and niobium on microstructure and mechanical properties as a function of oxygen content in TiAl alloys

    International Nuclear Information System (INIS)

    Lamirand, M.; Bonnentien, J.-L.; Ferriere, G.; Guerin, S.; Chevalier, J.-P.

    2007-01-01

    The effects of 2 at.% chromium and niobium on microstructure and mechanical properties of Ti-48Al-x(Cr, Nb) have been investigated for alloys with different oxygen content, ranging from ultra-high purity to doped alloys. Chromium and niobium additions have significant effects for the high purity alloys, whereas for alloys containing oxygen, no significant modification is observed due to the strong stabilizing effect of oxygen on the lamellar microstructure

  19. Effects of spherical quasi-crystal on microstructure and mechanical properties of ZA155 high zinc magnesium alloy

    Directory of Open Access Journals (Sweden)

    Zhang Jinshan

    2010-05-01

    Full Text Available Effects of spherical quasi-crystal contained in Mg-Zn-Y-Mn master alloy on the microstructure and as-cast mechanical properties of ZA155 high zinc magnesium alloy have been investigated by means of optical microscopy, XRD, SEM, EDS, tensile test, impact test and hardness test. Experimental results show that the addition of spherical quasi-crystal contained in the Mg-Zn-Y-Mn master alloy into the ZA155 high zinc magnesium alloy resulted in grain refinement of the matrix, changing the morphologies of φ-Al2Mg5Zn2 phase and τ-Mg32(Al, Zn49 phase from continuous net-like structures to discontinuous strip-like structure and blocky one, respectively. In the present research, the best comprehensive mechanical properties of reinforced ZA155 high zinc magnesium alloy has been obtained when 5.0wt% spherical quasi-crystal was introduced from the Mg-Zn-Y-Mn master alloy into the target alloy system. In such case, the room-temperature tensile strength reached 207 MPa, about 23% higher than that of the base alloy; the impact toughness peaked at 5.5 J/cm2, about 40% higher than that of the base alloy; and the elevated-temperature tensile strength reached 203 MPa, indicating improved heat resistance.

  20. Effects of cerium on as-cast microstructure and mechanical properties of Mg-3Sn-2Ca magnesium alloy

    International Nuclear Information System (INIS)

    Yang Mingbo; Pan Fusheng; Cheng Liang; Shen Jia

    2009-01-01

    The Mg-3Sn-2Ca-xCe (x = 0-2.0 wt.%) alloys were prepared by permanent mould casting method, the effects of Ce on the as-cast microstructure and mechanical properties of the alloys were investigated. The results indicated that the volume fraction and size of CaMgSn phase in the Mg-3Sn-2Ca alloy respectively were decreased by adding 0.5-2.0 wt.%Ce, and the average size of CaMgSn phase in the Mg-3Sn-2Ca alloys added 1.5 or 2.0 wt.%Ce was relatively smaller. The main phases in the as-cast Mg-3Sn-2Ca alloys with and without adding Ce were α-Mg, CaMgSn and Mg 2 Ca phases, and Mg 12 Ce phase were found in the alloys added more than 1.0 wt.%Ce. The addition of Ce improved the tensile and creep properties of Mg-3Sn-2Ca alloy, and the mechanical properties of Mg-3Sn-2Ca alloys added 1.5 or 2.0 wt.%Ce were relatively higher. The strengthening mechanism of Ce-containing Mg-3Sn-2Ca alloys was mainly attributed to the refinement of CaMgSn phase.

  1. Effect of Remelting of the Ni-22Cr-9Mo Alloy on its Microstructural and Electrochemical Properties

    Directory of Open Access Journals (Sweden)

    Augustyn-Nadzieja J.

    2017-03-01

    Full Text Available The Ni-Cr-Mo alloys are used as the alternative for the cobalt alloys in the manufacture of metal prosthetic elements, i.e. crowns, bridges and frame prostheses. The article attempts at a materials science characterization of the nickel-based alloy of the commercial name Argeloy N.P Be-Free by Argen. Within the study, examinations were made on the commercial alloy as well as the alloy which was remelted and cast by the los mould (lost wax method. Observations of the microstructure were performed with the use of optical and electron scanning microscopy. Also, X-ray structural tests were conducted as well as corrosion resistance tests in an artificial saliva solution (pH = 6,7. It was demonstrated that the examined Ni-22Cr-9Mo alloy characterized in a dendritic structure typical of the cast materials. The X-ray qualitative phase analysis revealed the phase γ'(Ni in both examined materials, as well as the presence of Cr23C6 type carbides and Nb2C, Ta2C (commercial alloy and NbC, Ta4C0,04 (cast alloy phases. The effect of the alloy’s remelting and the morphology of the passive layer on the corrosion resistance of the Ni-Cr-Mo alloy was examined.

  2. Strengthening effect of nano-scaled precipitates in Ta alloying layer induced by high current pulsed electron beam

    International Nuclear Information System (INIS)

    Tang, Guangze; Luo, Dian; Fan, Guohua; Ma, Xinxin; Wang, Liqin

    2017-01-01

    Highlights: • Ta alloying layer are fabricated by magnetron sputtering and high current pulsed electron beam. • Nano-scaled TaC precipitates forms within the δ-Fe grain after tempering treatment. • The mean diameter of TaC particles is about 5–8 nm. • The hardness of alloying layer increased by over 50% after formation of nano-scaled TaC particle. - Abstract: In this study, the combination of magnetron sputtering and high current pulsed electron beam are used for surface alloying treatment of Ta film on high speed steel. And the Ta alloying layer is about 6 μm. After tempering treatment, TaC phase forms in Ta alloying layer when the treated temperature is over 823 K. Through the TEM and HRTEM observation, a large amount of nano-scaled precipitates (mean diameter 5–8 nm) form within the δ-Fe grain in Ta alloying layer after tempering treatment and these nano-scaled precipitates are confirmed as TaC particles, which contribute to the strengthening effect of the surface alloying layer. The hardness of tempered alloying layer can reach to 18.1 GPa when the treated temperature is 823 K which increase by 50% comparing with the untreated steel sample before surface alloying treatment.

  3. Strengthening effect of nano-scaled precipitates in Ta alloying layer induced by high current pulsed electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Guangze; Luo, Dian; Fan, Guohua [School of Material Science & Engineering, Harbin Institute of Technology, Harbin 150001 (China); Ma, Xinxin, E-mail: maxin@hit.edu.cn [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Wang, Liqin [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2017-05-01

    Highlights: • Ta alloying layer are fabricated by magnetron sputtering and high current pulsed electron beam. • Nano-scaled TaC precipitates forms within the δ-Fe grain after tempering treatment. • The mean diameter of TaC particles is about 5–8 nm. • The hardness of alloying layer increased by over 50% after formation of nano-scaled TaC particle. - Abstract: In this study, the combination of magnetron sputtering and high current pulsed electron beam are used for surface alloying treatment of Ta film on high speed steel. And the Ta alloying layer is about 6 μm. After tempering treatment, TaC phase forms in Ta alloying layer when the treated temperature is over 823 K. Through the TEM and HRTEM observation, a large amount of nano-scaled precipitates (mean diameter 5–8 nm) form within the δ-Fe grain in Ta alloying layer after tempering treatment and these nano-scaled precipitates are confirmed as TaC particles, which contribute to the strengthening effect of the surface alloying layer. The hardness of tempered alloying layer can reach to 18.1 GPa when the treated temperature is 823 K which increase by 50% comparing with the untreated steel sample before surface alloying treatment.

  4. Effects of metallurgical factors on stress corrosion cracking of Ni-base alloys in high temperature water

    International Nuclear Information System (INIS)

    Yonezawa, T.; Sasaguri, N.; Onimura, K.

    1988-01-01

    Nickel-base Alloy 600 is the principal material used for the steam generator tubes of PWRs. Generally, this alloy has been proven to be satisfactory for this application, however when it is subjected to extremely high stress level in PWR primary water, it may suffer from stress corrosion cracking. The authors have systematically studied the effects of test temperature and such metallurgical factors as cold working, chemical composition and heat treatment on the stress corrosion cracking of Alloy 600 in high temperature water, and also on that of Alloy 690 which is a promising material for the tubes and may provide improved crrosion resistance for steam generators. The test materials, the stress corrosion cracking test and the test results are reported. When the test temperature was raise, the stress corrosion cracking of the nickel-base alloys was accelerated. The time of stress corrosion cracking occurrence decreased with increasing applied stress, and it occurred at the stress level higher than the 0.2 % offset proof stress of Alloy 600. In Alloy 690, stress corrosion cracking was not observed at such stress level. Cold worked Alloy 600 showed higher resistance to stress corrosion cracking than the annealed alloy. (Kako, I.)

  5. The effects of microstructural stability on the compressive response of two cast aluminum alloys up to 300 °C

    International Nuclear Information System (INIS)

    Shower, Patrick T.; Technology Division; University of Tennessee, Knoxville, TN; Roy, Shibayan; Technology Division; Indian Institute of Technology; Hawkins, Charles Shane; Technology Division)

    2017-01-01

    Here in this study, the high temperature compressive response of cast aluminum alloys 319 and RR350 is compared in light of their microstructures. The 319 alloy is widely used in thermally critical automotive applications and provides a baseline for comparison with the RR350 alloy, whose microstructural stability at high homologous temperatures was recently reported. Cylindrical compression samples from each alloy were tested at four temperatures up to 300 °C at a constant true strain rate that was varied over four orders of magnitude. Although both alloys are strengthened by metastable precipitates (nominally Al 2 Cu) in the as-aged condition, their mechanical response diverges at temperatures greater than 250 °C as the strengthening precipitates evolve in the 319 alloy and retain their as-aged morphology in the RR350 alloy. Deformation mechanisms of each alloy are examined using microstructural analysis and empirical activation energy calculations. The stability of the θ' phase in the RR350 alloy leads to effective precipitation hardening at homologous temperatures up to 0.6 and an extensive regime of grain boundary controlled deformation.

  6. On the occurrence of Portevin-Le Chatelier effect in fusion welded 2091 Al-Li based alloy joints

    Energy Technology Data Exchange (ETDEWEB)

    Vidal, A.C.; Darwish, F.A.; Solorzano, I.G. [Catholic Univ., Rio de Janeiro (Brazil)

    1995-09-01

    Al-Li based alloys are characterized by their lower density and higher stiffness, in comparison with conventional aluminum alloys. This makes the former very attractive for replacing the latter in structural and cryogenic applications, particularly in aeronautic and aerospace industries. The potential use of lithium-bearing also has stimulated studies on the weldability of these alloys as well as on the mechanical properties of the resulting welded joints. Al-Li-Cu-Mg alloy systems studied by Gomiero were found to exhibit serrations in their stress-strain curves, indicating the occurrence of Portevin-Le Chatelier (PLC) effects during plastic flow in these systems. The present study was therefore undertaken to determine the effect of fusion welding on the uniaxial tensile behavior of a 2091 (Al-Li-Cu-Mg-Zr) alloy. Microstructural aspects pertinent to the PLC effect are to be emphasized and the influence of post-weld heat treatment is to be presented and discussed.

  7. Thermal cooling effects in the microstructure and properties of cast cobalt-base biomedical alloys

    Science.gov (United States)

    Vega Valer, Vladimir

    Joint replacement prosthesis is widely used in the biomedical field to provide a solution for dysfunctional human body joints. The demand for orthopedic knee and hip implants motivate scientists and manufacturers to develop novel materials or to increase the life of service and efficiency of current materials. Cobalt-base alloys have been investigated by various researchers for biomedical implantations. When these alloys contain Chromium, Molybdenum, and Carbon, they exhibit good tribological and mechanical properties, as well as excellent biocompatibility and corrosion resistance. In this study, the microstructure of cast Co-Cr-Mo-C alloy is purposely modified by inducing rapid solidification through fusion welding processes and solution annealing heat treatment (quenched in water at room temperature. In particular the effect of high cooling rates on the athermal phase transformation FCC(gamma)↔HCP(epsilon) on the alloy hardness and corrosion resistance is investigated. The Co-alloy microstructures were characterized using metallography and microscopy techniques. It was found that the as cast sample typically dendritic with dendritic grain sizes of approximately 150 microm and containing Cr-rich coarse carbide precipitates along the interdendritic boundaries. Solution annealing gives rise to a refined microstructure with grain size of 30 microm, common among Co-Cr-Mo alloys after heat treating. Alternatively, an ultrafine grain structure (between 2 and 10 microm) was developed in the fusion zone for specimens melted using Laser and TIG welding methods. When laser surface modification treatments were implemented, the developed solidification microstructure shifted from dendritic to a fine cellular morphology, with possible nanoscale carbide precipitates along the cellular boundaries. In turn, the solidified regions exhibited high hardness values (461.5HV), which exceeds by almost 110 points from the alloy in the as-cast condition. The amount of developed athermal

  8. Microstructural Effects on Creep-Fatigue Life of Alloy 709

    Energy Technology Data Exchange (ETDEWEB)

    McMurtrey, Michael [Idaho National Lab. (INL), Idaho Falls, ID (United States); Carroll, Laura [Idaho National Lab. (INL), Idaho Falls, ID (United States); Wright, Jill [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2017-08-01

    Creep-fatigue tests were performed on plates of Alloy 709 from various heats and processing conditions, but often with inhomogeneous microstructures. After testing, metallographic analysis was performed and the specimens were generally found to either have a uniform grain size or a bimodal grain size distribution with either isolated or groups (bands) of large grains. Creep-fatigue life was characterized with respect to the length of the grain boundary perpendicular to the stress axis, and it was found that large grains (>400 μm) tended to be detrimental to creep-fatigue life, with the exception of elongated (parallel to the stress axis) grains and some specimens that underwent additional annealing.

  9. Ageing and memory effects in a mechanically alloyed nanoparticle system

    International Nuclear Information System (INIS)

    Osth, Michael; Herisson, Didier; Nordblad, Per; De Toro, Jose A.; Riveiro, Jose M.

    2007-01-01

    Ageing and memory experiments have been performed to explore the non-equilibrium dynamics of the mechanically alloyed nanoparticle system Fe 30 Ag 40 W 30 , which comprises a heterogeneous ensemble of magnetic particles with average moment ∼ 10 2 μ B dispersed in a metallic non-magnetic matrix. This system has earlier, from critical slowing down analysis, been reported to enter a spin glass like state at low temperatures [J. A. de Toro et al., Phys. Rev. B 69, (2004) 224407]. The wait time dependence of the magnetic relaxation observed after the application of a weak magnetic field and the memory of the thermal history in the low temperature phase recorded on continuous heating in a weak applied field show similar features as observed in corresponding experiments on canonical spin glasses

  10. Compressive strength, plastic flow properties, and surface frictional effects of 1100, 3003 and 6061 aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Pinkerton, Gary Wayne [Univ. of Illinois, Urbana-Champaign, IL (United States)

    1993-01-01

    The purpose of this study is to find aluminum alloys that are effective for use as wire vacuum seals in the 800MeV particle accelerator located at the Louis Anderson Meson Physics Facility (LAMPF) in Los Alamos, NM. Three alloys, Al 1100, Al 3003, and Al 6061, are investigated under uniaxial compression to determine stresses for a given height reduction from 0 to 70 percent, and to find plastic flow and surface interaction effects. Right-circular cylindrical specimens are compressed on-end (cylindrically) and radially (for modeling as compressed wire). Aluminum 1100 and 3003 alloys are compared for length to diameter ratios of 1 and 2 for both compression types, and are then compared to results of radial compression of annealed small diameter Al 1100 wire currently used at LAMPE. The specimens are also compressed between three different platen surfaces, polished steel, etched steel, and aluminum 6061-T6, to determine effects of friction. The Al 3003 alloy exhibits 20 to 25% lower stresses at all height reductions than Al 1100 for both cylindrical and radial compression.

  11. Compressive strength, plastic flow properties, and surface frictional effects of 1100, 3003 and 6061 aluminum alloys

    International Nuclear Information System (INIS)

    Pinkerton, G.W.

    1993-01-01

    The purpose of this study is to find aluminum alloys that are effective for use as wire vacuum seals in the 800MeV particle accelerator located at the Louis Anderson Meson Physics Facility (LAMPF) in Los Alamos, NM. Three alloys, Al 1100, Al 3003, and Al 6061, are investigated under uniaxial compression to determine stresses for a given height reduction from 0 to 70 percent, and to find plastic flow and surface interaction effects. Right-circular cylindrical specimens are compressed on-end (cylindrically) and radially (for modeling as compressed wire). Aluminum 1100 and 3003 alloys are compared for length to diameter ratios of 1 and 2 for both compression types, and are then compared to results of radial compression of annealed small diameter Al 1100 wire currently used at LAMPE. The specimens are also compressed between three different platen surfaces, polished steel, etched steel, and aluminum 6061-T6, to determine effects of friction. The Al 3003 alloy exhibits 20 to 25% lower stresses at all height reductions than Al 1100 for both cylindrical and radial compression

  12. Effect of natural and magnetic convections on the structure of electrodeposited zinc-nickel alloy

    Energy Technology Data Exchange (ETDEWEB)

    Levesque, A., E-mail: alexandra.levesque@univ-reims.fr [LACMDTI URCA, BP 1039, 51687 Reims Cedex2 (France); Chouchane, S. [Faculte des Sciences, Universite Badji Mokhtar, Annaba (Algeria); Douglade, J. [LACMDTI URCA, BP 1039, 51687 Reims Cedex2 (France); Rehamnia, R. [Faculte des Sciences, Universite Badji Mokhtar, Annaba (Algeria); Chopart, J.-P. [LACMDTI URCA, BP 1039, 51687 Reims Cedex2 (France)

    2009-06-30

    The effects of a magnetic field applied in a direction parallel or perpendicular to the cathode substrate plane, during electrodeposition process of Zn-Ni alloy have been investigated by means of chronoamperometric measurements, X-ray diffraction and EDX analysis. The modification of crystal orientation of the alloy by the superimposition of a high magnetic field is discussed for alloys with a content of nickel range 6-13 at%. Whatever the phase composition obtained without magnetic field, either {gamma}-Ni{sub 5}Zn{sub 21} or a mixture of the {gamma} and zinc phases, which depends on the concentration of Ni{sup 2+} in the electrolyte bath, the preferential orientation (1 0 1) of the zinc phase is always favoured with perpendicular and parallel magnetic field. There is no saturation of this effect with amplitude of B up to 8 T. A study of different geometric configurations of the cathode, which induce more or less natural convection, consolidates these results. The structural modifications of Zn-Ni alloy electrodeposits are thus probably due to a magnetohydrodynamic effect. An additional phenomenon is observed in presence of a perpendicular applied magnetic field since the (3 3 0) preferential orientation of the {gamma}-Ni{sub 5}Zn{sub 21} disappears with high values of B.

  13. Effect of natural and magnetic convections on the structure of electrodeposited zinc-nickel alloy

    International Nuclear Information System (INIS)

    Levesque, A.; Chouchane, S.; Douglade, J.; Rehamnia, R.; Chopart, J.-P.

    2009-01-01

    The effects of a magnetic field applied in a direction parallel or perpendicular to the cathode substrate plane, during electrodeposition process of Zn-Ni alloy have been investigated by means of chronoamperometric measurements, X-ray diffraction and EDX analysis. The modification of crystal orientation of the alloy by the superimposition of a high magnetic field is discussed for alloys with a content of nickel range 6-13 at%. Whatever the phase composition obtained without magnetic field, either γ-Ni 5 Zn 21 or a mixture of the γ and zinc phases, which depends on the concentration of Ni 2+ in the electrolyte bath, the preferential orientation (1 0 1) of the zinc phase is always favoured with perpendicular and parallel magnetic field. There is no saturation of this effect with amplitude of B up to 8 T. A study of different geometric configurations of the cathode, which induce more or less natural convection, consolidates these results. The structural modifications of Zn-Ni alloy electrodeposits are thus probably due to a magnetohydrodynamic effect. An additional phenomenon is observed in presence of a perpendicular applied magnetic field since the (3 3 0) preferential orientation of the γ-Ni 5 Zn 21 disappears with high values of B.

  14. Effects of deposition temperature on electrodeposition of zinc–nickel alloy coatings

    International Nuclear Information System (INIS)

    Qiao, Xiaoping; Li, Helin; Zhao, Wenzhen; Li, Dejun

    2013-01-01

    Highlights: ► Both normal and anomalous deposition can be realized by changing bath temperature. ► The Ni content in Zn–Ni alloy deposit increases sharply as temperature reach 60 °C. ► The abrupt change in coating composition is caused by the shift of cathodic potential. ► The deposition temperature has great effect on microstructure of Zn–Ni alloy deposit. -- Abstract: Zinc–nickel alloy coatings were electrodeposited on carbon steel substrates from the ammonium chloride bath at different temperatures. The composition, phase structure and morphology of these coatings were analyzed by energy dispersive spectrometer, X-ray diffractometer and scanning electron microscopy respectively. Chronopotentiometry and potentiostatic methods were also employed to analyze the possible causes of the composition and structure changes induced by deposition temperature. It has been shown that both normal and anomalous co-deposition of zinc and nickel could be realized by changing deposition temperature under galvanostatic conditions. The abrupt changes in the composition and phase structure of the zinc–nickel alloy coatings were observed when deposition temperature reached 60 °C. The sharply decrease of current efficiency for zinc–nickel co-deposition was also observed when deposition temperature is higher than 40 °C. Analysis of the partial current densities showed that the decrease of current efficiency with the rise of deposition temperature was due to the enhancement of the hydrogen evolution. It was also confirmed that the ennoblement of cathodic potential was the cause for the increase of nickel content in zinc–nickel alloy coatings as a result of deposition temperature rise. The good zinc–nickel alloy coatings with compact morphology and single γ phase could be obtained when the deposition temperature was fixed at 30–40 °C

  15. On the effect of Nb-based compounds on the microstructure of Al–12Si alloy

    International Nuclear Information System (INIS)

    Bolzoni, L.; Nowak, M.; Hari Babu, N.

    2015-01-01

    Cast Al alloys are important structural materials for the lightweighting of cars and, consequently, reduction of greenhouse gases emission and pollution. The microstructure and properties of cast Al alloys could be further improved by means of grain refinement, practise which cannot efficiently be performed with common Al–Ti–B grain refiners used for wrought Al alloys. In this work we proposed the employment of Nb+B inoculation as an alternative for the refinement of the primary α-Al dendrites of cast Al–Si alloy by studying the grain refinement induced by the Nb+B inoculants as a function of key aspects such as cooling rate, fading behaviour and simulated recyclability tests. It is found that the grain size of the Nb+B inoculated material is noticeably less sensitive to the cooling rate. Nb+B inoculants are still present and promote the refinement of the Al–12Si alloy even after few hours of contact time, although some fading is detected. Furthermore, Nb+B inoculants are also still effective for enhancing heterogeneous nucleation after three remelting of the inoculated alloy. The fading behaviour and ability to retain grain refining potency after remelting are highly relevant to industrial scale applications. - Highlights: • The influence of Nb+B inoculation on Al–12SSi is assessed. • The grain size decreases along with the amount of Nb+B compounds. • Nb+B inoculation makes the grain size less sensitive from the cooling rate. • Grain refinement is obtained via heterogeneous nucleation

  16. Investigation of alloying effects in aluminum dispersion strengthened with Al2O3

    International Nuclear Information System (INIS)

    Copeland, G.L.

    1975-10-01

    Two types of alloying elements were investigated to determine if the room-temperature strength could be improved and if, through lowering the oxide content, the high-temperature ductility could be improved. Mg was investigated for its solid solution strengthening in one type alloy. The other type alloy involved further dispersion strengthening through adding Fe, Mo, Zr, Cr, V, and Ti which form highly stable intermetallic compounds with Al. Fabrication techniques were developed which produced uniform and reproducible rods for testing. Prealloyed powders were produced by atomizing the molten alloys and collecting the powders in water. This procedure produced uniform powders with a very fine distribution of the intermetallic compounds. Fabrication into rods then included ball-milling, vacuum hot pressing, vacuum heat treating, and hot extrusion. Mg additions improved strengths up to 200 0 C with little effect above that temperature. Room-temperature tensile strengths up to 77,000 psi were obtained which are comparable to the strengths obtained in conventional aluminum alloys. The additional dispersion strengthening of the intermetallic compounds is additive to that of the oxide from room temperature to 450 0 C. No significant improvements in ductility are obtained by reducing the oxide content since even at very low ball-milling times (i.e., low oxide contents) the uniform elongation at 450 0 C is typically 0.5 percent. Good combinations of strength and ductility at 450 0 C were obtained in some of the alloys containing intermetallic compounds with no ball-milling. Typical properties at this temperature were tensile strengths of 7,000 psi, uniform elongation of 3 percent, and total elongation of 35 percent. (21 tables, 33 fig, 43 references) (auth)

  17. Effect of Co addition on crystallization and magnetic properties of FeSiBPCu alloy

    Directory of Open Access Journals (Sweden)

    Rui Xiang

    2014-12-01

    Full Text Available The effects of Co addition on the microstructure, crystallization processes and soft magnetic properties of (Fe1−xCox83Si4B8P4Cu1 (x=0.35, 0.5, 0.65 alloys were investigated. The experimental results demonstrated that the addition of Co decreased the thermal stability against crystallization of the amorphous phase, and thus improved the heat treatment temperature of this alloy. FeCoSiBPCu nanocrystalline alloys with a dispersed α′-FeCo phase were obtained by appropriately annealing the as-quenched ribbons at 763 K for 10 min. The α′-FeCo with grains size ranging from 9 to 28 nm was identified in primary crystallization. The coercivity (Hc markedly increased with increasing x and exhibited a minimum value at x=0.35, while the saturation magnetic flux density (Bs shows a slight decrease. The (Fe0.65Co0.3583Si4B8P4Cu1 nanocrystalline alloy exhibited a high saturation magnetic flux density Bs of 1.68 T, a low coercivity, Hc of 5.4 A/m and a high effective permeability µe of 29,000 at 1 kHz.

  18. Effect of Sb-Modification on the Microstructure and Mechanical Properties of Secondary Alloy 319

    Directory of Open Access Journals (Sweden)

    Medlen D.

    2016-06-01

    Full Text Available 319 alloy has been selected for the study in the present work due to its wide use in many applications. 319 alloy is used in automotive and aerospace industry for the complicated castings which must comply high strength requirements. In practice, the most common elements with the modifying effect are strontium, sodium and antimony. The addition of these elements leads to a change in the shape of eutectic silicon, resulting in an increase of the mechanical characteristics and the microstructure. An experimental program has been undertaken to explore the effect of antimony on chosen mechanical properties and the microstructure of investigated alloy. An analysis of the results of these experimental works is made in order to determine an optimum Sb (Al-10% Sb addition to produce material exhibiting desirable properties. Experimental works have showed that the addition of the Al-10% Sb results in similar or even higher mechanical properties than the conventional 319 alloy. Based on the carried out experiments the best combination of mechanical properties has been achieved by the addition of 2 000 ppm Al-10% Sb.

  19. Effect of Co Distribution on Plastic Deformation of Nanocrystalline Al-10.2 at.% Co Alloy

    Directory of Open Access Journals (Sweden)

    Rita I. Babicheva

    2015-01-01

    Full Text Available Molecular dynamics is employed to study stress-strain curves obtained during high strain rate deformation of nanocrystalline Al-10.2 at.% Co alloy with (i randomly distributed Co atoms (Al-Co substitutional solid solution and (ii Co atoms segregated in grain boundaries (GBs of the alloy. The effect of Co distribution, deformation temperature, and the presence of hydrostatic pressure on the stress-strain relation is analyzed. The results are compared to that for nanocrystalline pure Al. It is found that the strength of the Al-Co solid solution is lower than that of the pure Al, while GB segregations of Co increase its strength. The alloys, regardless of the type of Co distribution, under shear loading with no hydrostatic pressure demonstrate higher ductility in comparison with the pure Al. The shear modulus of the Al-Co alloy with the GB segregations is noticeably larger than that of the pure Al and the Al-Co solid solution in a wide range of temperatures. The results of the study show that the GB segregations of Co can have a positive effect on the mechanical properties of nanocrystalline Al.

  20. Cathodic cycling effects in the oxide films formed on zirconium alloys type AB2

    International Nuclear Information System (INIS)

    Zerbino, J.O; Visintin, A; Triaca, W

    2003-01-01

    The passive behavior of ZrNi alloys near the rest potential is studied through in situ voltammetry, ellipsometry, and microscopic observation.A significant oxide layer growth is observed in aqueous 1 M KOH during the application of different potential programs currently used in the activation processes of the alloy.The understanding of both the alloy activation process and the hydrogen absorption process is important in the strategies employed for the design of electrodes for nickel metal hydride batteries.The kinetics of the oxide layer formation, under potential cycling in the cathodic region related to the rest potential, plays a significant role in the activation process of metal alloy.Cathodic potential cycling increases the thickness and decreases the compactness of the passive oxide layer.The protonation of the oxide decreases the barrier effect and makes the anodic polarization more effective.Potential cycling gives rise to increasing surface oxidation, hydrogen absorption and hydride formation, and produces the consequent fragmentation of the material mainly through grain limits (J.Solid State Eletrochem. in press)

  1. Effects of metal primers on bonding of adhesive resin cement to noble alloys for porcelain fusing.

    Science.gov (United States)

    Okuya, Nobuhiro; Minami, Hiroyuki; Kurashige, Hisanori; Murahara, Sadaaki; Suzuki, Shiro; Tanaka, Takuo

    2010-03-01

    This study evaluated the effects of metal primers on the bonding of adhesive resin to four pure metals (Au, Pd, Ag, Cu) and two noble alloys for porcelain fusing (high-gold and high-palladium content alloys). Bonding surface was polished with 600-grit silicon carbide paper and primed with one of the three metal primers (V-Primer, Metaltite, and M.L. Primer). Bonded specimens were fabricated by applying adhesive resin (Super-Bond C&B) on the primed surface. Shear bond strength (SBS) was determined both before and after thermocycling (4-60 degrees C for 2,000 cycles). The highest SBS values to each pure metal after thermocycling were 33.5 MPa for Au by M.L. Primer, 35.0 MPa for Ag by V-Primer, and 34.4 MPa for Cu by Metaltite. SBS to high-gold content alloy after thermocycling was 33.3 MPa by M.L. Primer. None of the primers was effective for pure Pd and high-palladium content alloy after thermocycling.

  2. Effect of ternary alloying elements on microstructure and mechanical property of Nb-Si based refractory intermetallic alloy

    International Nuclear Information System (INIS)

    Kim, W.Y.; Kim, H.S.; Kim, S.K.; Ra, T.Y.; Kim, M.S.

    2005-01-01

    Microstructure and mechanical property at room temperature and at 1773 K of Nb-Si based refractory intermetallic alloys were investigated in terms of compression and fracture toughness test. Mo and V were chosen as ternary alloying elements because of their high melting points, atomic sizes smaller than Nb. Both ternary alloying elements were found to have a significant role in modifying the microstructure from dispersed structure to eutectic-like structure in Nb solid solution/Nb 5 Si 3 intermetallic composites. The 0.2% offset yield strength at room temperature increased with increasing content of ternary elements in Nb solid solution and volume fraction of Nb 5 Si 3 . At 1773 K, Mo addition has a positive role in increasing the yield strength. On the other hand, V addition has a role in decreasing the yield strength. The fracture toughness of ternary alloys was superior to binary alloys. Details will be discussed in correlation with ternary alloying, volume fraction of constituent phase, and the microstructure. (orig.)

  3. Effect of Nb on the Microstructure, Mechanical Properties, Corrosion Behavior, and Cytotoxicity of Ti-Nb Alloys

    Directory of Open Access Journals (Sweden)

    Mi-Kyung Han

    2015-09-01

    Full Text Available In this paper, the effects of Nb addition (5–20 wt % on the microstructure, mechanical properties, corrosion behavior, and cytotoxicity of Ti-Nb alloys were investigated with the aim of understanding the relationship between phase/microstructure and various properties of Ti-xNb alloys. Phase/microstructure was analyzed using X-ray diffraction (XRD, SEM, and TEM. The results indicated that the Ti-xNb alloys (x = 10, 15, and 20 wt % were mainly composed of α + β phases with precipitation of the isothermal ω phase. The volume percentage of the ω phase increased with increasing Nb content. We also investigated the effects of the alloying element Nb on the mechanical properties (including Vickers hardness and elastic modulus, oxidation protection ability, and corrosion behavior of Ti-xNb binary alloys. The mechanical properties and corrosion behavior of Ti-xNb alloys were found to be sensitive to Nb content. These experimental results indicated that the addition of Nb contributed to the hardening of cp-Ti and to the improvement of its oxidation resistance. Electrochemical experiments showed that the Ti-xNb alloys exhibited superior corrosion resistance to that of cp-Ti. The cytotoxicities of the Ti-xNb alloys were similar to that of pure titanium.

  4. Effect of Nb on the Microstructure, Mechanical Properties, Corrosion Behavior, and Cytotoxicity of Ti-Nb Alloys.

    Science.gov (United States)

    Han, Mi-Kyung; Kim, Jai-Youl; Hwang, Moon-Jin; Song, Ho-Jun; Park, Yeong-Joon

    2015-09-09

    In this paper, the effects of Nb addition (5-20 wt %) on the microstructure, mechanical properties, corrosion behavior, and cytotoxicity of Ti-Nb alloys were investigated with the aim of understanding the relationship between phase/microstructure and various properties of Ti-xNb alloys. Phase/microstructure was analyzed using X-ray diffraction (XRD), SEM, and TEM. The results indicated that the Ti-xNb alloys (x = 10, 15, and 20 wt %) were mainly composed of α + β phases with precipitation of the isothermal ω phase. The volume percentage of the ω phase increased with increasing Nb content. We also investigated the effects of the alloying element Nb on the mechanical properties (including Vickers hardness and elastic modulus), oxidation protection ability, and corrosion behavior of Ti-xNb binary alloys. The mechanical properties and corrosion behavior of Ti-xNb alloys were found to be sensitive to Nb content. These experimental results indicated that the addition of Nb contributed to the hardening of cp-Ti and to the improvement of its oxidation resistance. Electrochemical experiments showed that the Ti-xNb alloys exhibited superior corrosion resistance to that of cp-Ti. The cytotoxicities of the Ti-xNb alloys were similar to that of pure titanium.

  5. Effect of calcium on the microstructure and corrosion behavior of microarc oxidized Mg-xCa alloys.

    Science.gov (United States)

    Pan, Yaokun; Chen, Chuanzhong; Feng, Rui; Cui, Hongwei; Gong, Benkui; Zheng, Tingting; Ji, Yarou

    2018-01-16

    Magnesium alloys are potential biodegradable implants for biomedical applications, and calcium (Ca) is one kind of ideal element being examined for magnesium alloys and biodegradable ceramic coatings owing to its biocompatibility and mechanical suitability. In this study, microarc oxidation (MAO) coatings were prepared on Mg-xCa alloys to study the effect of Ca on the microstructure and corrosion resistance of Mg-xCa alloys and their surface MAO coatings. The electrochemical corrosion behavior was investigated using an electrochemical workstation, and the degradability and bioactivity were evaluated by soaking tests in simulated body fluid (SBF) solutions. The corrosion products were characterized by scanning electron microscopy, x-ray diffractometry, and Fourier transform infrared spectrometry. The effects of Ca on the alloy phase composition, microstructure, MAO coating formation mechanism, and corrosion behavior were investigated. Results showed that the Mg-0.82Ca alloy and MAO-coated Mg-0.82Ca exhibited the highest corrosion resistance. The number and distribution of Mg 2 Ca phases can be controlled by adjusting the Ca content in the Mg-xCa alloys. The proper amount of Ca in magnesium alloy was about 0.5-0.8 wt. %. The pore size, surface roughness, and corrosion behavior of microarc oxidized Mg-xCa samples can be controlled by the number and distribution of the Mg 2 Ca phase. The corrosion behaviors of microarc oxidized Mg-Ca in SBF solutions were discussed.

  6. Effect of extrusion processing on the microstructure, mechanical properties, biocorrosion properties and antibacterial properties of Ti-Cu sintered alloys.

    Science.gov (United States)

    Zhang, Erlin; Li, Shengyi; Ren, Jing; Zhang, Lan; Han, Yong

    2016-12-01

    Ti-Cu sintered alloys, Ti-Cu(S) alloy, have exhibited good anticorrosion resistance and strong antibacterial properties, but low ductility in previous study. In this paper, Ti-Cu(S) alloys were subjected to extrusion processing in order to improve the comprehensive property. The phase constitute, microstructure, mechanical property, biocorrosion property and antibacterial activity of the extruded alloys, Ti-Cu(E), were investigated in comparison with Ti-Cu(S) by X-ray diffraction (XRD), optical microscopy (OM), scanning electronic microscopy (SEM) with energy disperse spectroscopy (EDS), mechanical testing, electrochemical testing and plate-count method in order to reveal the effect of the extrusion process. XRD, OM and SEM results showed that the extrusion process did not change the phase constitute but refined the grain size and Ti2Cu particle significantly. Ti-Cu(E) alloys exhibited higher hardness and compressive yield strength than Ti-Cu(S) alloys due to the fine grain and Ti2Cu particles. With the consideration of the total compressive strain, it was suggested that the extrusion process could improve the ductility of Ti-Cu alloy(S) alloys. Electrochemical results have indicated that the extrusion process improved the corrosion resistance of Ti-Cu(S) alloys. Plate-count method displayed that both Ti-Cu(S) and Ti-Cu(E) exhibited strong antibacterial activity (>99%) against S. aureus. All these results demonstrated that hot forming processing, such as the extrusion in this study, refined the microstructure and densified the alloy, in turn improved the ductility and strength as well as anticorrosion properties without reduction in antibacterial properties. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. The effect of addition of various elements on properties of NiTi-based shape memory alloys for biomedical application

    Science.gov (United States)

    Kök, Mediha; Ateş, Gonca

    2017-04-01

    In biomedical applications, NiTi and NiTi-based alloys that show their shape memory effects at body temperature are preferred. In this study, the purpose is to produce NiTi and NiTi-based alloys with various chemical rates and electron concentrations and to examine their various physical properties. N45Ti55, Ni45Ti50Cr2.5Cu2.5, Ni48Ti51X (X=Mn, Sn, Co) alloys were produced in an arc melter furnace in this study. After the homogenization of these alloys, the martensitic phase transformation temperatures were determined with differential-scanner calorimeter. The transformation temperature was found to be below the 37 ° C (body temperature) in Ni45Ti50Cr2.5Cu2.5, Ni48Ti51X (X=Mn, Co) alloys; and the transformation temperature of the N45Ti55, Ni48Ti51Sn alloys was found to be over 37 ° C . Then, the micro and crystal structure analyses of the alloys were made, and it was determined that Ni45Ti50Cr2.5Cu2.5, Ni48Ti51X (X=Mn, Co) alloys, which were in austenite phase at room temperature, included B2 (NiTi) phase and Ti2Ni precipitation phase, and the alloys that were in the martensite phase at room temperature included B19ı (NiTi) phase and Ti2Ni phase. The common phase in both alloy groups is the Ti2Ni phase, and this type of phase is generally seen in NiTi alloys that are rich in titanium (Ti-rich).

  8. Alloying effects of refractory elements in the dislocation of Ni-based single crystal superalloys

    Directory of Open Access Journals (Sweden)

    Shiyu Ma

    2016-12-01

    Full Text Available The alloying effects of W, Cr and Re in the [100] (010 edge dislocation cores (EDC of Ni-based single crystal superalloys are investigated using first-principles based on the density functional theory (DFT. The binding energy, Mulliken orbital population, density of states, charge density and radial distribution functions are discussed, respectively. It is clearly demonstrated that the addition of refractory elements improves the stability of the EDC systems. In addition, they can form tougher bonds with their nearest neighbour (NN Ni atoms, which enhance the mechanical properties of the Ni-based single crystal superalloys. Through comparative analysis, Cr-doped system has lower binding energy, and Cr atom has evident effect to improve the systemic stability. However, Re atom has the stronger alloying effect in Ni-based single crystal superalloys, much more effectively hindering dislocation motion than W and Cr atoms.

  9. Mechanism of improvement of shape memory effect by training in Fe-Mn-Si-based alloys

    International Nuclear Information System (INIS)

    Kajiwara, S.; Ogawa, K.

    2000-01-01

    High-resolution electron microscopy study has been made on the ''trained'' sample of an Fe-14Mn-6Si-9Cr-5Ni (mass %) alloy in order to know the mechanism of improvement of shape memory effect. High densities of extremely thin hcp martensite plates with uniform distribution are produced by ''training'', which is regarded as the key factor for improving shape memory effect. (orig.)

  10. Effect of nanostructuring on the elastic properties of aluminum alloy AMg6

    Energy Technology Data Exchange (ETDEWEB)

    Prokhorov, V., E-mail: pvm@tisnum.ru; Perfilov, S. [Technological Institute for Superhard and Novel Carbon Materials. Centralnaya 7a, Moscow, Troitsk, 142190 (Russian Federation); Korobov, A., E-mail: aikor42@mail.ru; Kokshaiskii, A.; Volkov, A. [Department of Acoustics, Faculty of Physics, M.V. Lomonosov Moscow State University. Leninskie gory 1, Moscow, 119991 (Russian Federation)

    2015-10-28

    We experimentally investigated the nanostructuring effect on the elastic properties of aluminum alloy AMg6 (Al–Mg–Mn system). The n-AMg6 nanostuctured specimens were prepared from a commercial polycrystalline alloy by refining and homogenizing a mixture of small chips of the alloy in a planetary mill. The resulting product consists of 200-500-micron agglomerates of nanoparticles with average nanoparticle size ∼ 40–60 nanometer according to the X-ray analysis. The compacted nanopowder was extruded at a temperature of 300°C with a reduction of cross-sectional area at least 4 times to 90 mm diameter. High resolution transmission electron microscopy studies confirmed the presence of the nanostructure with a grain size of ∼60 nanometers. For the experiments, nine parallelepiped shape specimens of 20×20×40 mm{sup 3} size were cut from the central and peripheral parts of the n-AMg6 rod. We measured of the second-order and third-order elastic coefficients of the obtained samples by ultrasonic method. The same measurements were made on specimens of the primary AMg6 alloy for comparison.

  11. Effect of temperature on corrosion behavior of 3003 aluminum alloy in ethylene glycol–water solution

    Directory of Open Access Journals (Sweden)

    Chen Xin

    2016-08-01

    Full Text Available The effect of temperature on the corrosion behavior of 3003 aluminum alloy in ethylene glycol–water solution was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS techniques. The surface characterization was observed and determined by scanning electron microscopy (SEM, atomic force microscopy (AFM and energy dispersive spectrometer (EDS. The results demonstrate that the anodic aluminum dissolution and the cathodic oxygen reduction were accelerated by the increased temperature. However, as temperature was over 60 °C, the solubility and concentration of oxygen decreased, resulting in the inhibition of cathodic reaction. The cathodic reaction rate of 3003 aluminum alloy rose to the maximum at 60 °C. The Warburg impedance in Nyquist diagram diminished and then was replaced by a negative capacitance caused by the absorption of intermediate corrosion product on electrode. On the other hand, after potentiodynamic measurements, 3003 aluminum alloy suffered pitting corrosion. The dissolution of aluminum alloy around secondary phase particles expanded both horizontally and vertically.

  12. Effect of a weak transverse magnetic field on the microstructure in directionally solidified peritectic alloys

    Science.gov (United States)

    Li, Xi; Lu, Zhenyuan; Fautrelle, Yves; Gagnoud, Annie; Moreau, Rene; Ren, Zhongming

    2016-11-01

    Effect of a weak transverse magnetic field on the microstructures in directionally solidified Fe-Ni and Pb-Bi peritectic alloys has been investigated experimentally. The results indicate that the magnetic field can induce the formation of banded and island-like structures and refine the primary phase in peritectic alloys. The above results are enhanced with increasing magnetic field. Furthermore, electron probe micro analyzer (EPMA) analysis reveals that the magnetic field increases the Ni solute content on one side and enhances the solid solubility in the primary phase in the Fe-Ni alloy. The thermoelectric (TE) power difference at the liquid/solid interface of the Pb-Bi peritectic alloy is measured in situ, and the results show that a TE power difference exists at the liquid/solid interface. 3 D numerical simulations for the TE magnetic convection in the liquid are performed, and the results show that a unidirectional TE magnetic convection forms in the liquid near the liquid/solid interface during directional solidification under a transverse magnetic field and that the amplitude of the TE magnetic convection at different scales is different. The TE magnetic convections on the macroscopic interface and the cell/dendrite scales are responsible for the modification of microstructures during directional solidification under a magnetic field.

  13. Effect of cerium addition on the corrosion behaviour of carbon-alloyed iron aluminides

    International Nuclear Information System (INIS)

    Sriram, S.; Balasubramaniam, R.; Mungole, M.N.; Bharagava, S.; Baligidad, R.G.

    2006-01-01

    The effect of Ce addition on the microstructure and corrosion behavior of carbon-alloyed iron aluminides Fe-20.0Al-2.0C, Fe-18.5Al-3.6C and Fe-19.2Al-3.3C-0.07Ce (in at.%) has been studied. The potentiodynamic polarization behaviour of the alloys was evaluated in freely aerated 0.25 mol/l H 2 SO 4 . A 0.05% C steel was used for comparison purposes. All the alloys exhibited active-passive behaviour in the acidic solution. The addition of Ce destroyed passivity as indicated by lower breakdown potentials in polarization studies. This has been related to the finer distribution of the carbides in the microstructure. Corrosion rates were evaluated by immersion testing. The iron aluminide with Ce addition exhibited a lower corrosion rate compared to the aluminides without Ce addition. This has been attributed to modifications in surface film with Ce addition. Scanning electron microscopy of corroded surfaces indicated that the carbon-alloyed intermetallics were susceptible to localized galvanic corrosion due to the presence of carbides in the microstructure

  14. Effect of Cold Drawing and Heat Treatment on the Microstructure of Invar36 Alloy Wire

    International Nuclear Information System (INIS)

    Han, Seung Youb; Jang, Seon Ah; Eun, Hee-Chul; Choi, Jung-Hoon; Lee, Ki Rak; Park, Hwan Seo; Ahn, Do-Hee; Kim, Soo Young; Kim, Jea Youl; Shin, Sang Yong

    2016-01-01

    In this study, the effect of cold drawing and heat treatment on the microstructure of Invar36 alloy wire was investigated. Invar36 alloy wire is used as a transmission line core material, and is required to have high strength. The diameter of the Invar36 alloy wire specimens were reduced from 16 mm to 4.3 mm after three cold drawing and two heat treatment processes, thereby increasing tensile strength. Specimens were taken after each of the cold drawing and heat treatment processes, and their microstructure and tensile properties were analyzed. The Invar36 alloy wire had a γ-(Fe, Ni) phase matrix before the cold drawing and heat treatment processes. After the cold drawing processes, {220} and {200} textures were mainly achieved. After the heat treatment processes, a {200} recrystallization γ-(Fe, Ni) phase was formed with fine carbides. The recrystallization γ-(Fe, Ni) phase grains had low dislocation density, so they probably accommodated a large amount of deformation during the cold drawing processes.

  15. The effect of Electro Discharge Machining (EDM) on the corrosion resistance of dental alloys.

    Science.gov (United States)

    Ntasi, Argyro; Mueller, Wolf Dieter; Eliades, George; Zinelis, Spiros

    2010-12-01

    The aim of the present study was to evaluate the effect of Electro Discharge Machining (EDM) on the corrosion resistance of two types of dental alloys used for fabrication of implant retained superstructures. Two groups of specimens were prepared from a Co-Cr (Okta-C) and a grade II cpTi (Biotan) alloys respectively. Half of the specimens were subjected to EDM with Cu electrodes and the rest were conventionally finished (CF). The corrosion resistance of the alloys was evaluated by anodic polarization in Ringer's solution. Morphological and elemental alterations before and after corrosion testing were studied by SEM/EDX. Six regions were analyzed on each surface before and after corrosion testing and the results were statistically analyzed by paired t-test (a=0.05). EDM demonstrated inferior corrosion resistance compared to CF surfaces, the latter being passive in a wider range of potential demonstrating higher polarization resistance and lower I(corr) values. Morphological alterations were found before and after corrosion testing for both materials tested after SEM analysis. EDX showed a significant decrease in Mo, Cr, Co, Cu (Co-Cr) and Ti, Cu (cpTi) after electrochemical testing plus an increase in C. According to the results of this study the EDM procedure decreases the corrosion resistance of both the alloys tested, increasing thus the risk of possible adverse biological reactions. Copyright © 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  16. Strain rate effect on the cyclic deformation response of UFG Al alloys

    Energy Technology Data Exchange (ETDEWEB)

    Malekjani, Shokoufeh, E-mail: s.malekjani@deakin.edu.au [Centre for Material and Fibre Innovation, Deakin University, Geelong 3216 (Australia); Hodgson, Peter D., E-mail: peter.hodgson@deakin.edu.au [Centre for Material and Fibre Innovation, Deakin University, Geelong 3216 (Australia); Cizek, Pavel, E-mail: pavel.cizek@deakin.edu.au [Centre for Material and Fibre Innovation, Deakin University, Geelong 3216 (Australia); Hilditch, Timothy B., E-mail: tim.hilditch@deakin.edu.au [School of Engineering, Deakin University, Geelong 3216 (Australia)

    2012-06-30

    Highlights: Black-Right-Pointing-Pointer We studied the cyclic deformation response of UFG Al to strain rate change. Black-Right-Pointing-Pointer The materials considered for this study were commercially pure Al and 2024 Al alloy. Black-Right-Pointing-Pointer The cyclic softening rate in UFG pure Al was not strain rate sensitive. Black-Right-Pointing-Pointer However, the appearance of shear bands was found strain rate sensitive. Black-Right-Pointing-Pointer The stable behaviour of UFG 2024 Al alloy was also found insensitive to strain rate. - Abstract: Commercially pure aluminium and 2024 Al alloy were cryo-rolled and annealed to produce ultrafine grained (UFG) microstructures. Both materials were cyclically deformed under a fully reversed total strain amplitude control condition at different frequencies to study strain rate effects. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to identify microstructural changes and explain the mechanical properties. The cyclic stress response showed significant softening in commercial purity Al that was due to shear band formation and grain coarsening within these shear bands. While there was no strain rate sensitivity for commercial purity Al in terms of the mechanical response, the shear bands became noticeably more defined at lower strain rates. 2024 Al alloy had a cyclically stable response and microstructure that was not affected by strain rate.

  17. EFFECT OF CASTING MOULD ON MECHANICAL PROPERTIES OF 6063 ALUMINUM ALLOY

    Directory of Open Access Journals (Sweden)

    WASIU AJIBOLA AYOOLA

    2012-02-01

    Full Text Available Modern production methods for casting articles include the use of sand- mould, metal-mould, die, and centrifugal castings. Castings produced using sand mould is known to have peculiar microstructures depending on average size, distribution and shape of the moulding sand grains and the chemical composition of the alloy. These affect the surface finish, permeability and refractoriness of all the castings. In this paper, the effect of using CO2 process, metal mould, cement-bonded sand mould and naturally-bonded sand mould on the hardness, tensile and impact strengths of as-cast 6063 Aluminum alloy is presented. The results show that there is significant increase in hardness(33.7 HB of the alloy when naturally-bonded sand mould is used for its production over that of metal, CO2 and cement moulds. The stress-strain curves behaviour of the samples also indicated that sample from naturally bonded sand has highest tensile strength with superior ductility. The alloy shows highest impact strength when metal mould is used for sample preparation in comparison with other moulds.

  18. Effect of Refiner Addition Level on Zirconium-Containing Aluminium Alloys

    International Nuclear Information System (INIS)

    Jaradeh, M M R; Carlberg, T

    2012-01-01

    It is well known that in aluminium alloys containing Zr, grain refiner additions do not function as desired, producing an effect often referred to as nuclei poisoning. This paper investigates the structure of direct chill-cast ingots of commercial AA3003 aluminium alloys, with and without Zr, at various addition levels of Al5Ti1B master alloy. In Bridgman experiments simulating ingot solidification, Zr-containing alloys were studied after the addition of various amounts of Ti. It could be demonstrated, in both ingot casting and simulation experiments, that Zr poisoning can be compensated for by adding more Ti and/or Al5Ti1B. The results confirm better refinement behaviour with the addition of Ti + B than of only Ti. The various combinations of Zr and Ti also influenced the formation of AlFeMn phases, and the precipitation of large Al 6 (Mn,Fe) particles was revealed. AlZrTiSi intermetallic compounds were also detected.

  19. Effect of Refiner Addition Level on Zirconium-Containing Aluminium Alloys

    Science.gov (United States)

    Jaradeh, M. M. R.; Carlberg, T.

    2012-01-01

    It is well known that in aluminium alloys containing Zr, grain refiner additions do not function as desired, producing an effect often referred to as nuclei poisoning. This paper investigates the structure of direct chill-cast ingots of commercial AA3003 aluminium alloys, with and without Zr, at various addition levels of Al5Ti1B master alloy. In Bridgman experiments simulating ingot solidification, Zr-containing alloys were studied after the addition of various amounts of Ti. It could be demonstrated, in both ingot casting and simulation experiments, that Zr poisoning can be compensated for by adding more Ti and/or Al5Ti1B. The results confirm better refinement behaviour with the addition of Ti + B than of only Ti. The various combinations of Zr and Ti also influenced the formation of AlFeMn phases, and the precipitation of large Al6(Mn,Fe) particles was revealed. AlZrTiSi intermetallic compounds were also detected.

  20. The effect of temperature on the structural and magnetic behaviour of Fe-Ni Invar alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kadziolka-Gawel, M; Zarek, W; Popiel, E, E-mail: mariolakadz@op.p [Institute of Physics, University of Silesia, 4 Uniwersytecka Str., 40-407 Katowice (Poland)

    2010-03-01

    The crystal structure and magnetic properties of polycrystalline Fe{sub 1-x}Ni{sub x} alloys with x = 0.30, 0.325 and 0.375 were investigated in the temperature range 20Keffect methods. Two structural transitions were observed above 600K. In the first one bcc ({alpha}) {yields} fcc ({gamma}) and in the second one fcc ({gamma}) {yields} fcc ({gamma}) with a lower lattice constant. It was found that below 700K the lattice constant of the {gamma} phase does not depend on temperature. The transition {alpha} {yields} {gamma} changes the local environment of the Fe atoms and affects the magnetic properties of the Fe-Ni alloys. The disappearance of the ferromagnetic order in {gamma}-Fe{sub 0.70}Ni{sub 0.30} alloy can be explained by the presence of Fe atoms in the low (0{mu}{sub B}) and high (2.8{mu}{sub B}) spin state. The Fe atoms with zero magnetic moment can destroy the long range magnetic order in the investigated Fe-Ni alloys.

  1. Effect of quenching rate on the microstructure of a rapidly solidified Al-5Sb alloy

    International Nuclear Information System (INIS)

    Wang Yan; Zhang Zhonghua; Zheng Shaohua; Fan Suhua; Cheng Xin; Wang Weimin; Bian Xiufang; Geng Haoran

    2004-01-01

    In the present work, the effect of quenching rate (wheel speed) on the microstructure of a melt-spun Al-5Sb alloy has been investigated using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The phases were identified to be α-Al and AlSb in the alloy melt-spun at 500 and 1500 rpm. The microstructure of the alloy melt-spun at 500 rpm is composed of primary AlSb particles embedded in a matrix comprising equiaxed α-Al cells with intercellular nanoscale AlSb particles and α-Al/AlSb eutectic. Furthermore, intracellular nanoscale AlSb particles were also found in some areas. With increasing quenching rate to 1500 rpm, the matrix microstructure comprises elongated α-Al cells with intercellular nanoscale AlSb particles. The intercellular AlSb particles exhibiting intense Bragg reflections with monocrystalline characteristics possess the same crystallographic orientation but the intracellular ones are randomly oriented exhibiting spotty rings in the Al-5Sb alloy melt-spun at 500 rpm

  2. Effect of aging on the martensitic transformation temperature in Ag-Zn-Al alloys

    International Nuclear Information System (INIS)

    Takezawa, K.; Hoshi, H.; Marukawa, K.

    2000-01-01

    The relation between atomic ordering and martensitic transformation temperature, M s , in Ag-Zn-Al alloys was examined mainly by means of electrical resistivity measurements. Disordered bcc phase was frozen-in by quenching from a temperature above the critical temperature for ordering, T c . In a Ag-22.3at%Zn-8.9at%Al alloy, the M s temperature has been found to decrease by aging in the parent phase at temperatures between 253 and 293 K. The resistivity also decreased in accord with the M s temperature. This indicates that atomic ordering proceeds by aging. The relation between the decrease in the reverse transformation temperature, A f , and the degree of long range order was obtained. In a Ag-11.0at%Zn-15.5at%Al alloy, in which the M s temperature in the as-quenched state is higher and the T c temperature is lower than that of the former alloy, aging in the martensite phase was performed. In this case, the aging brought about the increase in the A f temperature. This is in contrast to the results of aging in the parent phase. Furthermore, the effect of aging in the parent phase at temperatures higher than T c was examined. Both the transformation temperature and the resistivity were found to become higher. These changes are due to lowering in the degree of short range order. (orig.)

  3. Effect of mixed alloy combinations on fretting corrosion performance of spinal screw and rod implants.

    Science.gov (United States)

    Mali, Sachin A; Singh, Vaneet; Gilbert, Jeremy L

    2017-07-01

    Spinal implants are made from a variety of materials to meet the unique mechanical demands of each application. However, the medical device community has raised concern about mixing dissimilar metals in an implant because of fear of inducing corrosion. There is a lack of systematic studies on the effects of mixing metals on performance of spinal implants, especially in fretting corrosion conditions. Hence, the goal was to determine whether mixing stainless steel (SS316L), titanium alloy (Ti6Al4V) and cobalt chromium (CoCrMo) alloy components in a spinal implant leads to any increased risk of corrosion degradation. Spinal constructs consisting of single assembly screw-connector-rod components were tested using a novel short-term cyclic fretting corrosion test method. A total of 17 alloy component combinations (comprised of SS316L, Ti6Al4V-anodized and CoCrMo alloy for rod, screws and connectors) were tested under three anatomic orientations. Spinal constructs having all SS316L were most susceptible to fretting-initiated crevice corrosion attack and showed higher average fretting currents (∼25 - 30 µA), whereas constructs containing all Ti6Al4V components were less susceptible to fretting corrosion with average fretting currents in the range of 1 - 6 µA. Mixed groups showed evidence of fretting corrosion but they were not as severe as all SS316L group. SEM results showed evidence of severe corrosion attack in constructs having SS316L components. There also did not appear to be any galvanic effects of combining alloys together. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1169-1177, 2017. © 2016 Wiley Periodicals, Inc.

  4. Effect of heating palladium-silver alloys on ceramic bond strength.

    Science.gov (United States)

    Li, Jie-yin; Li, Rui-nan; Chang, Shao-hai; Zhuang, Pei-lin; Liao, Juan-kun; Ye, Xiu-hua; Ye, Jian-tao

    2015-11-01

    The effects of different heat treatments on the internal oxidation and metal-ceramic bond in Pd-Ag alloys with different trace elements require further documentation. The purpose of this in vitro study was to determine whether heat treatment affects the metal-ceramic bond strength of 2 Pd-Ag alloys containing different trace elements. Thirteen cast specimens (25×3×0.5 mm) from each of 2 Pd-Ag alloy groups (W-1 and Argelite 61+3) were allocated to heat treatments before porcelain application: heating under reduced atmospheric pressure of 0.0014 MPa and 0.0026 MPa and heating under normal atmospheric pressure. Bond strengths were evaluated using a 3-point bending test according to ISO9693. Results were analyzed using 2-way ANOVA and Tukey HSD test (α=.05). Visual observation was used to determine the failure types of the fractured specimens. Scanning electron microscopy and energy dispersive spectroscopy were used to study morphologies, elemental compositions, and distributions in the specimens. The W-1 group had a mean bond strength significantly higher than that of Argelite 61+3 (PHeating under reduced atmospheric pressures of 0.0014 MPa and 0.0026 MPa resulted in similar bond strengths (P=.331), and both pressures had significantly higher bond strengths than that of heating under normal atmospheric pressure (P=.002, PHeating under different air pressures resulted in Pd-Ag alloys that contained either Sn or In and Ga, with various degrees of internal oxidation and different quantities of metallic nodules. Heating under reduced atmospheric pressure effectively improved the bond strength of the ceramic-to-Pd-Ag alloys. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  5. Influences of different degassing processes on refining effect and properties of 4004 Al alloy

    Directory of Open Access Journals (Sweden)

    Wang Liping

    2013-03-01

    Full Text Available In order to improve the plasticity of 4004 Al alloy and subsequently the productivity of 4004 Al foil, the research studied in detail the influence of the rotary impeller degassing process on the refining effect of 4004 Al alloy, in which the impacts of four major parameters: gas flow, rotational speed, refining time, and stewing time, on degassing rate of 4004 Al alloy was systematically studied by using an orthogonal experiment methodology. Results show that the rotational speed has the greatest impact on the degassing of 4004 Al alloy, followed by gas flow and refining time; stewing time has the least impact. The optimum purification parameters obtained by current orthogonal analysis were: rotor speed of 500 r·min-1, inert gas flow of 0.4 mL·h-1, refining time of 15 min, and stewing time of 6 min. Degassing rate using the optimum parameters reaches 68%. In addition, the comparison experiments among C2Cl6 refining, rotary impeller degassing, and combined treatment of C2Cl6 refining and rotary impeller degassing for 4004 Al alloy were performed. The experimental data indicated that the combined treatment of C2Cl6 refining and rotary impeller degassing has the best degassing effect. Degassing rate of C2Cl6 refining, rotary impeller degassing and combined refining treatment is 39%, 69.1% and 76.9%, respectively. The mechanical properties of the specimen refined by rotary impeller degassing were higher than those by C2Cl6 refining, but lower than those by combined refining treatment.

  6. Effect of ultraviolet irradiation on the osseointegration of a titanium alloy with bone

    Directory of Open Access Journals (Sweden)

    Ashish Yadav

    2017-01-01

    Full Text Available Introduction: Attempt has been made to analyze the potential of titanium (Ti alloy for osteointegration by the effect of surface photo functionalization in different aspects as follows: in Ringer's solution, in vitro cell growth, and in vivo study on rabbit. The present study was aimed to investigate the influence of ultraviolet (UV light on surface topography, corrosion behavior, and bioactivity of indigenously manufactured samples of Ti alloy mini-implant. Materials and Methods: The study includes surface modification of Ti samples by UV treatment, corrosion testing of the specimens using Potentiostat (GAMRY System, qualitative examination of modified surface topography using scanning electron microscope, and cellular viability test on Ti alloy surface (3-(4,5-Dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide ASSAY. To find the effect of UV light on implant bone integration, biochemical test was performed on the femur of rabbits. Results and Discussion: Corrosion resistance of untreated Ti alloy in Ringer's solution was found to be less, whereas corrosion rate was more. Corrosion resistance of UV-treated samples was found to increase significantly, thereby lowering the corrosion rate. Cell growth in UV-treated specimen was observed to be higher than that in untreated samples. It is important to mention that cell growth was significantly enhanced on samples which were UV treated for longer duration of time. Conclusions: There was a marked improvement in cell growth on UV-treated Ti alloy samples. Hence, it is expected that it would enhance the process of osseointegration of Ti with bone. Another important finding obtained was that the removal torque values of UV-treated implants were higher than that of untreated implants. The overall result reveals that UV treatment of implants does help us in speeding up the osseointegration process.

  7. Synergistic Effect of Gelatin and Glycerol on Electrodeposition of Zn-Ni Alloy

    Science.gov (United States)

    Rao, Vaishaka R.; Hegde, Ampar Chitharanjan

    2013-10-01

    The use of organic compounds which improves corrosion resistance has attracted growing interest in electroplating technology. In this direction, this article presents the experimental results of electrodeposition of Zn-Ni alloy on mild steel (MS) from acid chloride bath using gelatin and glycerol as additives. The bath composition and operating parameters have been optimized by the conventional Hull cell method. The effect of gelatin and glycerol, individually and in combination on the deposition process, was identified by a cyclic voltammetry (CV) study at different scan rates. Bright deposition of Zn-Ni alloy was found at optimal current density (c.d.) due to the preferential deposition of gelatin and glycerol by controlling the Ni content of the alloy. The CV study demonstrated that alloy deposition is diffusion controlled when additives were used individually and is adsorption controlled when used in combination. Corrosion behaviors at different current densities (c.d.s) were evaluated by potentiodynamic polarization and electrochemical impedance (EIS) methods. The surface morphology and phase structure of the coatings were analyzed by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) studies. The experimental results revealed that both gelatin and glycerol have synergistic effects in improving the electrocrystallization process and, hence, the corrosion stability of the coatings. At an optimal c.d. (3.0 A dm-2), the Zn-Ni alloy coating showed peak performance against corrosion with the least corrosion rate. Better corrosion protection at optimal c.d., which was attributed to specific Zn(101), γ-(411,330), and Zn(103) reflections, is evidenced by the XRD study.

  8. Corrosion of alloy 22 in phosphate ions effect and chloride containing solutions

    International Nuclear Information System (INIS)

    Carranza, Ricardo M.

    2009-01-01

    Alloy 22 belongs to Ni-Cr-Mo family. This alloy resists the most aggressive environments for industrial applications, in oxidizing as well as reducing conditions, because exhibits an excellent uniform and localized corrosion resistance in aqueous solution. Because of its outstanding corrosion resistant, this alloy is one of the candidate to be considered for the outer shell of the canister that would contain high level radioactive nuclear wastes in a geological repository. The aim of this work is to study ion phosphate influence over Alloy 22 corrosion behavior under aggressive conditions, such as high temperature and high ion chloride concentration, where this material might be susceptible to crevice corrosion. Two different types of samples were used: cylinder specimens for uniform corrosion behavior studies and Prismatic Crevice Assembly (PCA) specimens for localized corrosion studies. Electrochemical tests were performed in deaerated aqueous solution of 1 M NaCl and 1 M NaCl with different phosphate additions at 90 C degrees and pH near neutral. The anodic film and corrosion products obtained were studied by SEM/EDS. Cyclic Potentiodynamic Polarization (CPP) curves obtained for uniform corrosion studies, showed an increase of the passivity range in phosphate containing solutions. The passive current value was 1 μA/cm 2 approximately in all the tests. PCA electrochemical tests, that combined a CPP with a potentiostatic polarization step for 2 hours in between the forward and reverse scan, showed crevice corrosion development in some cases. The repassivation potential value, determined by the intersection of the forward and the reverse scan, increased with phosphate addition. A complete crevice corrosion inhibition effect was found for phosphate concentration higher than 0.3 M. These results indicate that the passivity potential range depend on phosphate presence and might be related with the incorporation of the anion in the passive film. Results of the tests

  9. Effect of electron count and chemical complexity in the Ta-Nb-Hf-Zr-Ti high-entropy alloy superconductor.

    Science.gov (United States)

    von Rohr, Fabian; Winiarski, Michał J; Tao, Jing; Klimczuk, Tomasz; Cava, Robert Joseph

    2016-11-15

    High-entropy alloys are made from random mixtures of principal elements on simple lattices, stabilized by a high mixing entropy. The recently discovered body-centered cubic (BCC) Ta-Nb-Hf-Zr-Ti high-entropy alloy superconductor appears to display properties of both simple crystalline intermetallics and amorphous materials; e.g., it has a well-defined superconducting transition along with an exceptional robustness against disorder. Here we show that the valence electron count dependence of the superconducting transition temperature in the high-entropy alloy falls between those of analogous simple solid solutions and amorphous materials and test the effect of alloy complexity on the superconductivity. We propose high-entropy alloys as excellent intermediate systems for studying superconductivity as it evolves between crystalline and amorphous materials.

  10. Effect of cold working and applied stress on the stress corrosion cracking resistance of nickel-chromium-iron alloys

    International Nuclear Information System (INIS)

    Yonezawa, T.; Onimura, K.; Itoh, H.; Saito, I.; Takamatsu, H.; Fujitani, T.

    1992-01-01

    In order to grasp the stress corrosion cracking quantitative resistance of Alloys 600 and 690 in PWR primary water, the authors have studied the effect of cold working and applied stress on the stress corrosion cracking resistance of Alloys 600 and 690, in high temperature water. Stress corrosion cracking tests were conducted at 360 degrees C (633K) in a simulated PWR primary water for about 12,000 hours or 24,000 hours. From the test results, it is concluded that the stress corrosion cracking resistance in the cold worked Alloy 600 at the same applied stress level increases with an increase in cold working ratio, and the cold worked Alloys of thermally treated 690 have the excellent stress corrosion cracking resistance. Further, in this paper, the planning of stress corrosion cracking test for weld joints and weld metal of Alloy 600 is described

  11. Effect of Aging Treatment on the Compressibility and Recovery of NiTi Shape Memory Alloys as Static Seals

    Science.gov (United States)

    Lu, Xiaofeng; Li, Gang; Liu, Luwei; Zhu, Xiaolei; Tu, Shan-Tung

    2017-07-01

    The improvement of the compressibility and recovery of the gaskets can decrease the leakage occurrence in bolted flange connections. In this study, the effect of aging treatment on the compressibility and recovery of NiTi shape memory alloys is investigated as static seals together with thermal analysis. The experimental results indicate that different phase transformations of NiTi alloys are exhibited in the DSC curves during aging treatment. The recovery coefficient of NiTi alloys aged at 500 °C for 2 h is quite low accompanied with a large residual strain. With increasing aging time at the aging temperature of 400 °C, the residual strain and area of hysteresis loop of NiTi alloys are both increased, whereas the recovery coefficient is decreased. Since the deformation associates the phase transformation behavior, aging treatment could improve the compressibility and recovery of NiTi alloys as static seals.

  12. Effect of Cr and Ti contents on the recovery, recrystallization, and mechanical properties of vanadium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gubbi, A.N.; Rowcliffe, A.F.; Alexander, D.J.; Grossbeck, M.L. [Oak Ridge National Laboratory, TN (United States)] [and others

    1996-04-01

    A series of vacuum-anneals at temperatures from 900 to 100{degrees}C for 1 to 4 h was carried out on small heats of vanadium alloys with Cr and Ti contents ranging from 2 to 6wt. %. The alloys examined on this work were V-3Cr-3Ti, V-4Cr-4Ti, V-5Cr-5Ti, V-6Cr-3Ti, and V-6Cr-6Ti. Optical miscroscopy, TEM, and microhardness testing were conducted. Variation in Cr and Ti over the range of 3 to 6 wt% had no discernible effect on recovery/recrystallization behavior. The hardness of both recovered and recrystallized structures increased with total (CR + Ti) content. In order to study the effect of Cr and Ti content on mechanical properties, Charpy impact testing and tensile testing were carried out on small heats of compositional variants. The V-4Cr-4Ti-Si alloy, in a fully recrystallized conditions, exhibited a high level of resistance to cleavage failure with a DBTT at {approx} 190{degrees}C. The alloy containing higher concentrations of Cr and Ti, in a fully recrystallized condition, exhibited a DBTT around -100{degrees}C, whereas the V-3Cr-3Ti alloy failed by pure ductile shear at liquid nitrogen temperature without any ductile-to-brittle transition. Tensile testing was conducted on SS-3 tensile specimens punched from 0.762-mm-thick plates of V-3Cr-3Ti and V-6Cr-6Ti. The tests were done in air at temperature at strain rates ranging from 10{sup -3} to 2x10{sup -1}/s. For V-6Cr-6Ti, both the 0.2% yield stress (YS) and the ultimate tensile strength (UTS) were higher than those for V-3Cr-3Ti at all strain rates. Both YS and UTS showed a similiar trend in incremental increase with strain rate for the two alloys. In the same token, both alloys exhibited an identical behavior of almost no change in uniform and total elongation up to a strain rate of 10{sup -1}/s and a decrease with further increase in strain rate.

  13. Effect of strontium on liquid structure of Al-Si hypoeutectic alloys using high-energy X-ray diffraction

    International Nuclear Information System (INIS)

    Srirangam, P.; Kramer, M.J.; Shankar, S.

    2011-01-01

    High-energy X-ray diffraction experiments were performed using a synchrotron beam source to investigate the effect of strontium on the liquid atomic structure of Al-Si hypoeutectic alloys. The high-temperature liquid diffraction experiments were carried out on Al alloys with 3, 7, 10 and 12.5 (eutectic) wt.% Si, respectively, with 0 and 0.04 wt.% addition of Sr to each of the alloys. Further, the diffraction data for all the alloys were obtained at various melt temperatures (5-220 K) above the respective liquidus temperature. It was observed that the addition of 0.04 wt.% Sr results in significant change in the liquid structure parameters, such as structure factor, pair distribution function, radial distribution function, coordination number and packing density, at any given melt temperature of the alloy. Salient observations were that, for any specific alloy and temperature, addition of Sr significantly decreases coordination number and packing density. Further, with the addition of Sr in the liquid alloy, the atomic coordination number and packing density increases with decreasing temperature and decreasing Si content of the alloy. The results coupled with prior knowledge have enabled an in-depth understanding of the nucleation environment of the solidifying phases, specifically the role of Sr in delaying the clustering tendencies (nucleation) of the eutectic Si phase.

  14. Effect of Cooling Rate on Microstructures and Mechanical Properties in SA508 Gr4N High Strength Low Alloy Steel

    International Nuclear Information System (INIS)

    Kim, Minchul; Park, Sanggyu; Choi, Kwonjae; Lee, Bongsang

    2013-01-01

    The microstructure of Ni-Cr-Mo low alloy steel is a mixture of tempered martensite and tempered lower bainite and that of Mn-Mo-Ni low alloy steel is predominantly tempered upper bainite. Higher strength and toughness steels are very attractive as an eligible RPV steel, so several researchers have studied to use the Ni-Cr-Mo low alloy steel for the NPP application. Because of the thickness of reactor vessel, there are large differences in austenitizing cooling rates between the surface and the center locations of thickness in RPV. Because the cooling rates after austenitization determine the microstructure, it would affect the mechanical properties in Ni-Cr-Mo low alloy steel, and it may lead to inhomogeneous characteristics when the commercial scale of RPV is fabricated. In order to apply the Ni-Cr-Mo low alloy steel to RPV, it is necessary to evaluate the changes of microstructure and mechanical properties with varying phase fractions in Ni-Cr-Mo low alloy steel. In this study, the effects of martensite and bainite fractions on mechanical properties in Ni-Cr-Mo low alloy steel were examined by controlling the cooling rate after austenitization. First of all, continuous cooling transformation(CCT) diagram was established from the dilatometric analyses. Then, the phase fractions at each cooling rate were quantitatively evaluated. Finally, the mechanical properties were correlated with the phase fraction, especially fraction of martensite in Ni-Cr-Mo low alloy steel

  15. [Effect of fluoride concentration on the corrosion behavior of cobalt-chromium alloy fabricated by two different technology processes].

    Science.gov (United States)

    Qiuxia, Yang; Ying, Yang; Han, Xu; Di, Wu; Ke, Guo

    2016-02-01

    This study aims to determine the effect of fluoride concentration on the corrosion behavior of cobalt-chromium alloy fabricated by two different technology processes in a simulated oral environment. A total of 15 specimens were employed with selective laser melting (SLM) and another 15 for traditional casting (Cast) in cobalt-chromium alloy powders and blocks with the same material composition. The corrosion behavior of the specimens was studied by potentiodynamic polarization test under different oral environments with varying solubilities of fluorine (0, 0.05%, and 0.20% for each) in acid artificial saliva (pH = 5.0). The specimens were soaked in fluorine for 24 h, and the surface microstructure was observed under a field emission scanning electron microscope after immersing the specimens in the test solution at constant temperature. The corrosion potential (Ecorr) value of the cobalt-chromium alloy cast decreased with increasing fluoride concentration in acidic artificial saliva. The Ecorr, Icorr, and Rp values of the cobalt-chromium alloy fabricated by two different technology processes changed significantly when the fluoride concentration was 0.20% (P technology processes exhibited a statistically significant difference. The Icorr value of the cobalt-chromium alloy cast was higher than that in the SLM group cobalt-chromium alloy when the fluoride concentration was 0.20% (P technology processes. The corrosion resistance of the cobalt-chromium alloy cast was worse than that of the SLM group cobalt-chromium alloy when the fluoride concentration was 0.20%.

  16. The effect of remelting various combinations of new and used cobalt-chromium alloy on the mechanical properties and microstructure of the alloy

    Directory of Open Access Journals (Sweden)

    Sharad Gupta

    2012-01-01

    Conclusion: Repeated remelting of base metal alloy for dental casting without addition of new alloy can affect the mechanical properties of the alloy. Microstructure analysis shows deterioration upon remelting. However, the addition of 25% and 50% (by weight of new alloy to the remelted alloy can bring about improvement both in mechanical properties and in microstructure.

  17. Effect of surface treatments on stress corrosion cracking susceptibility of nickel base alloys

    International Nuclear Information System (INIS)

    Iwanami, Masaru; Kaneda, Junya; Tamako, Hiroaki; Hato, Hisamitsu; Takamoto, Shinichi

    2009-01-01

    Effect of surface treatment on SCC susceptibility of Ni base alloys was investigated. Cracks were observed in all grinding specimens in a creviced bent beam (CBB) test. On the other hand, no cracks occurred in shot peening (SP), water jet peening (WJP) specimens. It was indicated that these surface treatments effectively reduced the SCC susceptibility of nickel-base alloys. As a result of a residual stress test, the surface of specimens with grinding had high tensile residual stress. However, SP and WJP improved surface residual stress to compressive stress. The depth of the compressive effect of WJP was almost the same as that of SP. However, the surface hardness of WJP specimens differed from that of SP and it was found that WJP had less impact on surface hardening. This difference was consistent with their surface microstructures. The surface of SP specimens had clearly the deformation region, but the surface of WJP specimens was localized. (author)

  18. Effect of Pressure on the Crystallisation of AlSi7Mg Alloy

    Directory of Open Access Journals (Sweden)

    Pastirčák R.

    2017-12-01

    Full Text Available This paper deals with influencing the crystallisation of Al alloys by a direct squeeze casting method. The effects of changed cooling rates of the casting is evaluated using a heat transfer coefficient at different casting conditions. The experimental results obtained by temperature measurement of the casting and the mould were used to predict the casting and mould surface temperatures using regression curves. The measured temperatures in the sub-surface layers were used to determine the amount of heat transferred from the casting to the mould. The amount of transferred heat increased 20-fold due to the effect of pressure. We also evaluated the effect of the acting pressure on the mechanical properties and microstructure of the alloy used. The process parameters were varied in the experiment.

  19. Effects of ion implantation on corrosion of zirconium and zirconium base alloys

    International Nuclear Information System (INIS)

    Zelenskij, V.F.; Petel'guzov, I.A.; Rekova, L.P.; Rodak, A.G.

    1989-01-01

    The influence of He and Ar ion bombardment on the corrosion of Zr and Zr-1%Nb and Zr-2.5%Nb alloys is investigated with the aims of finding the irradiation influence laws, obtaining the dependences of the effect of increasing the corrosiuon resistance on the type and dose of bombarding ions and of finding the conditions for the maximum effect. The prolonged corrosion test of specimens (3500 hours) have shown that the strongest effect is obtained for the irradiation with Ar ions up to the dose 1x10 16 ion/cm 2 . The kinetics of ion thermosorption after corrosion of irradiated materials is studied, the temperature threshold of implanted ion stability in zirconium and its alloys is found to be 400 deg C

  20. Effect of recasting on the thickness of metal-ceramic interface of nickel-chromium and cobalt-chromium alloys

    Directory of Open Access Journals (Sweden)

    Mirković Nemanja

    2008-01-01

    Full Text Available Introduction/Aim. This research was done to establish recasting effects of nickel-chromium and cobalt-chromium alloys on the thickness of their metal-ceramic interface in making fixed partial dentures. Metal-ceramic interface determines their functional integrity and prevents damages on ceramics during mastication. Investigation of metal-ceramic samples is supposed to show if base metal alloys for metalceramics are successfully recycled without any risk of reduction of metal-ceramic interface thickness. Methods. The research was performed as an experimental study. Per six metal-ceramic samples of nickel-chromium alloy (Wiron99 and cobalt-chromium alloy (Wirobond C were made each. Alloy residues were recycled through twelve casting generations with the addition of 50% of new alloy on the occasion of every recasting. Analysis Energy Dispersive X-ray (EDX (Oxford Instruments and Scanning Electon Microscop (SEM analysis (JEOL were used to determine thickness of metal-ceramic interface together with PC Software for quantification of visual information's (KVI POPOVAC. Results. Results of this research introduced significant differences between thickness of metal-ceramic interface in every examined recycle generation. Recasting had negative effect on thickness of metal-ceramic interface of the examined alloys. This research showed almost linear reduction of elastic modulus up to the 12th generation of recycling. Conclusion. Recasting of nickel-chromium and cobaltchromium alloys is not recommended because of reduced thickness of metal-ceramic interface of these alloys. Instead of recycling, the alloy residues should be returned to the manufacturers.

  1. Effects of Annealing Process on the Formability of Friction Stir Welded Al-Li Alloy 2195 Plates

    Science.gov (United States)

    Chen, Po-Shou; Bradford, Vann; Russell, Carolyn

    2011-01-01

    Large rocket cryogenic tank domes have typically been fabricated using Al-Cu based alloys like Al-Cu alloy 2219. The use of aluminum-lithium based alloys for rocket fuel tank domes can reduce weight because aluminum-lithium alloys have lower density and higher strength than Al-Cu alloy 2219. However, Al-Li alloys have rarely been used to fabricate rocket fuel tank domes because of the inherent low formability characteristic that make them susceptible to cracking during the forming operations. The ability to form metal by stretch forming or spin forming without excessive thinning or necking depends on the strain hardening exponent "n". The stain hardening exponent is a measure of how rapidly a metal becomes stronger and harder. A high strain hardening exponent is beneficial to a material's ability to uniformly distribute the imposed strain. Marshall Space Flight Center has developed a novel annealing process that can achieve a work hardening exponent on the order of 0.27 to 0.29, which is approximately 50% higher than what is typically obtained for Al-Li alloys using the conventional method. The strain hardening exponent of the Al-Li alloy plates or blanks heat treated using the conventional method is typically on the order of 0.17 to 0.19. The effects of this novel annealing process on the formability of friction stir welded Al-Li alloy blanks are being studied at Marshall Space Flight Center. The formability ratings will be generated using the strain hardening exponent, strain rate sensitivity and forming range. The effects of forming temperature on the formability will also be studied. The objective of this work is to study the deformation behavior of the friction stir welded Al-Li alloy 2195 blank and determine the formability enhancement by the new annealing process.

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

    International Nuclear Information System (INIS)

    Rebak, R B

    2005-01-01

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

  3. Effect of Sn addition on hot tearing susceptibility of AXJ530 alloy

    Science.gov (United States)

    Hai-kuo, Dong; Feng, Wang; Zhi, Wang; Jin-kun, Liu; Zheng, Liu; Ping-li, Mao

    2018-03-01

    The effects of different Sn additions (0, 0.5, 1.0, and 2.0 wt%) on hot tearing susceptibility (HTS) of AXJ530 alloy were studied using ‘T-shaped’ hot tearing mold at a pouring temperature of 700 °C and a mold temperature of 200 °C and paraffin permeation method. The dendrite coherency temperature was obtained by means of differential thermal analysis (DTA), and phases evolution, microstructures and morphology of the crack zone of AXJ530-xSn alloys were also investigated by using x-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). The experimental results show that the HTS of AXJ530-xSn alloys increases with Sn additions up to 1.0 wt%, and then exhibits a slight decrease with further Sn additions up to 2.0 wt%. The Sn additions into AXJ530 alloy can first form CaMgSn phase with high melting point, reduce amount of α-Mg+(Mg,Al)2Ca eutectic phase, increase the dendrite coherency temperature, decrease the thickness of liquid film and the feeding ability at the end of solidification, resulting in the rise of the HTS. However, the improvement in hot tearing resistance for AXJ530-2.0Sn alloy can be attributed to the grain refinement, lower dendrite coherency temperature and formation of the Mg17Al12 phase with a low melting point to feed more readily at the end of solidification, which improves the state of dendrite and the feeding channel.

  4. Effect of Adding Elements on Microstructure of Mg-3Si Alloy

    Directory of Open Access Journals (Sweden)

    CUI Bin

    2017-03-01

    Full Text Available The microstructure of alloy Mg-3Si(mass fraction/%, same as below after successive additions with different elements of Zn, Nd, Gd and Y was observed and the microstructure evolution was investigated by scanning electron microscopy and X-ray diffraction. The results show the primary Mg2Si particles co-exist with eutectic Mg2Si particles in binary alloy Mg-Si. With minor addition of Zn element, only primary Mg2Si can be found in ternary Mg-3Si-3Zn system while eutectic Mg2Si particles disappear. In quaternary alloy Mg-2.0Nd-3.0Zn-3.0Si, the addition of Nd element can effectively refine the primary Mg2Si particles and form some Mg41Nd5 particles. After continuous adding of Gd and Y elements into quaternary system, Gd5Si3 and YSi particles increase significantly in the alloy Mg-8.0Gd-4.0Y-2.0Nd-3.0Zn-3.0Si, while volume fraction of primary Mg2Si decrease significantly. Thermo-Calc calculation predicts that the Gibbs free energy for primary particles Gd5Si3, YSi is lower, and therefore Gd, Y atom and Si are more likely to form compounds. In Mg-8Gd-4Y-2Nd-3Zn-3Si alloy, room temperature Gibbs free energy for primary particles Mg2Si, Gd5Si3, YSi is -9.56×104, -8.72×104, -2.83×104J/mol, respectively, and the mass fraction of these particles is 8.07%, 5.27%, 1.40% respectively.

  5. Irradiation effect on the precipitation in Fe-Cr model alloys with around 15% of chromium

    International Nuclear Information System (INIS)

    Jaquet, Virginie

    2000-01-01

    The ferritic-martensitic steels containing around 12% of chromium are considered for nuclear applications. But, under working reactor conditions, they can become brittle because of the precipitation of a new chromium rich phase called α'. To answer this question, we study this phase separation in Fe-Cr (10 to 25%) model alloys under irradiation at 300 C with a weak flux of electron and under thermal annealing at 500 C. When the precipitation of the α' phase occurs, the alloys become harder. We measured the hardening by Vickers testings. The precipitates are detected by small-angle neutron scattering. Analysis of the intensities with a hard sphere model gives the mean precipitate size and density. These parameters obtained that way can explain the hardening. Under irradiation at 300 C, the growth kinetic is very slow - the precipitates remain very small with a typical radius of 7-8 Angstroms - and the density of precipitates rises up 10 19 per cm 3 . On the other hand, when the alloys are annealed at 500 C, the precipitates grow with a coarsening kinetic. Assuming that the only effect of irradiation is to enhance the diffusion, we calculate the precipitation kinetic with the cluster dynamic model. It is able to reproduce the thermal precipitation at 500 C but not the precipitation at 300 C. An other mechanism, induced by a coupling between fluxes of point defects and solute atoms, is clearly relevant under irradiation. The precipitation kinetic observed in the alloys irradiated at 300 C could relate to this mechanism: the negative coupling of fluxes in Fe-Cr alloys could slow down the precipitate growth. (author) [fr

  6. Effect of different ions on the anodic behaviour of alloy 800 chloride solutions at high temperature

    International Nuclear Information System (INIS)

    Lafont, C.J.; Alvarez, M.G.

    1993-01-01

    The anodic behaviour and passivity breakdown of alloy 800 in sodium bicarbonate and sodium phosphate aqueous solutions were studied in the temperature range from 100 degrees C to 280 degrees C by means of electrochemical techniques. The effect of phosphate or bicarbonate additions on the pitting susceptibility and pitting morphology of the alloy in chloride solutions was also examined. Experiments were performed in the following solutions: 0.1M NaHCO 3 , at 100 degrees C, 200 degrees C, 280 degrees C; 0.06M NaH 2 PO 4 + 0.04M Na 2 HPO 4 , at 100 degrees C, 200 degrees C and 280 degrees C, and 0.1M NaCl with different additions of bicarbonate ion (0.02M, 0.05M and 0.1M) and phosphate ion (0.01M, 0.05M and 0.1M) at 100 degrees C and 280 degrees C. The anodic polarization curves of alloy 800 in deaerated 0.1M NaHCO 3 and 0.06M NaH 2 PO 4 + 0.04M Na 2 HPO 4 solutions exhibited a similar shape at all the tested temperatures. No localized or generalized corrosion was detected on the metallic surface after polarization. The results obtained in chloride plus bicarbonate and chloride plus phosphate mixtures showed that the pitting potential of alloy 800 in chloride solutions was increased by the presence of bicarbonate or phosphate ions. In those solutions where the inhibitor concentration in the mixture is equal or higher than the chloride concentration , the behaviour of the alloy is similar to the one observed in the absence of chlorides. Changes in pitting morphology were found in phosphate containing solutions, while the pits found in bicarbonate containing solutions were similar to those formed in pure chloride solutions. (author). 3 refs., 4 figs

  7. Contribution to the study of the crystal field in rare earth alloys. Moessbauer effect on 161Dy

    International Nuclear Information System (INIS)

    Iraldi, Renato.

    1974-01-01

    Hyperfine interactions in Dy-Y and Dy-Sc alloys were studied using Moessbauer effect on 161 Dy. It was shown that all RE-RE and RE-Y alloys are equivalents systems as for the conduction electron structure and magnetic properties, when crystal fields and anisotropy effects are taken into account. On the other hand, quadrupolar interaction studies in Dy-Sc alloys showed that in these alloys electronic properties vary considerably with the concentration of Sc. These results are interpreted as being due to pressure effect that changes the properties of conduction electrons. A high charge density at the nucleus in Dy-Sc was observed. This phenomenon is also interpreted as being due to a pressure effect on dysprosium external shells [fr

  8. The W alloying effect on thermal stability and hardening of nanostructured Cu–W alloyed thin films

    Science.gov (United States)

    Zhao, J. T.; Zhang, J. Y.; Hou, Z. Q.; Wu, K.; Feng, X. B.; Liu, G.; Sun, J.

    2018-05-01

    In order to achieve desired mechanical properties of alloys by manipulating grain boundaries (GBs) via solute decoration, it is of great significance to understand the underlying mechanisms of microstructural evolution and plastic deformation. In this work, nanocrystalline (NC) Cu–W alloyed films with W concentrations spanning from 0 to 40 at% were prepared by using magnetron sputtering. Thermal stability (within the temperature range of 200 °C–600 °C) and hardness of the films were investigated by using the x-ray diffraction, transmission electron microscope (TEM) and nanoindentation, respectively. The NC pure Cu film exhibited substantial grain growth upon all annealing temperatures. The Cu–W alloyed films, however, displayed distinct microstructural evolution that depended not only on the W concentration but also on the annealing temperature. At a low temperature of 200 °C, all the Cu–W alloyed films were highly stable, with unconspicuous change in grain sizes. At high temperatures of 400 °C and 600 °C, the microstructural evolution was greatly controlled by the W concentrations. The Cu–W films with low W concentration manifested abnormal grain growth (AGG), while the ones with high W concentrations showed phase separation. TEM observations unveiled that the AGG in the Cu–W alloyed thin films was rationalized by GB migration. Nanoindentation results showed that, although the hardness of both the as-deposited and annealed Cu–W alloyed thin films monotonically increased with W concentrations, a transition from annealing hardening to annealing softening was interestingly observed at the critical W addition of ∼25 at%. It was further revealed that an enhanced GB segregation associated with detwinning was responsible for the annealing hardening, while a reduced solid solution hardening for the annealing softening.

  9. The W alloying effect on thermal stability and hardening of nanostructured Cu-W alloyed thin films.

    Science.gov (United States)

    Zhao, J T; Zhang, J Y; Hou, Z Q; Wu, K; Feng, X B; Liu, G; Sun, J

    2018-05-11

    In order to achieve desired mechanical properties of alloys by manipulating grain boundaries (GBs) via solute decoration, it is of great significance to understand the underlying mechanisms of microstructural evolution and plastic deformation. In this work, nanocrystalline (NC) Cu-W alloyed films with W concentrations spanning from 0 to 40 at% were prepared by using magnetron sputtering. Thermal stability (within the temperature range of 200 °C-600 °C) and hardness of the films were investigated by using the x-ray diffraction, transmission electron microscope (TEM) and nanoindentation, respectively. The NC pure Cu film exhibited substantial grain growth upon all annealing temperatures. The Cu-W alloyed films, however, displayed distinct microstructural evolution that depended not only on the W concentration but also on the annealing temperature. At a low temperature of 200 °C, all the Cu-W alloyed films were highly stable, with unconspicuous change in grain sizes. At high temperatures of 400 °C and 600 °C, the microstructural evolution was greatly controlled by the W concentrations. The Cu-W films with low W concentration manifested abnormal grain growth (AGG), while the ones with high W concentrations showed phase separation. TEM observations unveiled that the AGG in the Cu-W alloyed thin films was rationalized by GB migration. Nanoindentation results showed that, although the hardness of both the as-deposited and annealed Cu-W alloyed thin films monotonically increased with W concentrations, a transition from annealing hardening to annealing softening was interestingly observed at the critical W addition of ∼25 at%. It was further revealed that an enhanced GB segregation associated with detwinning was responsible for the annealing hardening, while a reduced solid solution hardening for the annealing softening.

  10. Effect of Ce on solidification and mechanical properties of A360 alloy

    International Nuclear Information System (INIS)

    Voncina, Maja; Kores, Stanislav; Mrvar, Primoz; Medved, Jozef

    2011-01-01

    Highlights: → We investigated the effect of Ce addition on the AA A360 alloy. → The purpose is to study the variations that occur during solidification and precipitation with different Ce additions, as well as their effect on the mechanical properties. → Ce addition decreases the eutectic (α Al + Mg 2 Si) temperature and eutectic recalescence and also solidus temperature. → The precipitation enthalpy decreases with the Ce addition, while precipitation takes place more rapidly and intensively, indicating increased reaction kinetics. → The mechanical properties like hardness and tensile strength also increase with the Ce addition. - Abstract: The effect of Ce addition on the AA A360 (Al-10%Si-0.5%Mg) alloy was investigated using equilibrium thermodynamic calculation, thermal analysis, differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The purpose is to study the variations that occur during solidification and precipitation with different Ce additions, as well as their effect on the mechanical properties. The results show that the Ce addition decreases the eutectic (α Al + Mg 2 Si) temperature. The solidus temperature also decreases with the increasing Ce addition. The precipitation enthalpy determined using DSC decreases with the Ce addition, while precipitation takes place more rapidly and intensively, indicating increased reaction kinetics. The mechanical properties like hardness and tensile strength also increase with the Ce addition. The phase that contributed to the hardness of the investigated alloy was composed of Al, Ce, Mg and Si.

  11. Effect of Aluminum Alloying on the Hot Deformation Behavior of Nano-bainite Bearing Steel

    Science.gov (United States)

    Yang, Z. N.; Dai, L. Q.; Chu, C. H.; Zhang, F. C.; Wang, L. W.; Xiao, A. P.

    2017-12-01

    Interest in using aluminum in nano-bainite steel, especially for high-carbon bearing steel, is gradually growing. In this study, GCr15SiMo and GCr15SiMoAl steels are introduced to investigate the effect of Al alloying on the hot deformation behavior of bearing steel. Results show that the addition of Al not only notably increases the flow stress of steel due to the strong strengthening effect of Al on austenite phase, but also accelerates the strain-softening rates for its increasing effect on stacking fault energy. Al alloying also increases the activation energy of deformation. Two constitutive equations with an accuracy of higher than 0.99 are proposed. The constructed processing maps show the expanded instability regions for GCr15SiMoAl steel as compared with GCr15SiMo steel. This finding is consistent with the occurrence of cracking on the GCr15SiMoAl specimens, revealing that Al alloying reduces the high-temperature plasticity of the bearing steel. On the contrary, GCr15SiMoAl steel possesses smaller grain size than GCr15SiMo steel, manifesting the positive effect of Al on bearing steel. Attention should be focused on the hot working process of bearing steel with Al.

  12. Effects of Sm on the grain refinement, microstructures and mechanical properties of AZ31 magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Ming [National Engineering Research Center of Light Alloy Net Forming, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); School of Mechanical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Hu, Xiaoyu [National Engineering Research Center of Light Alloy Net Forming, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Peng, Liming, E-mail: plm616@sjtu.edu.cn [National Engineering Research Center of Light Alloy Net Forming, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240 (China); Fu, Penghuai [National Engineering Research Center of Light Alloy Net Forming, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Peng, Yinghong [School of Mechanical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China)

    2015-01-03

    The effects of samarium (Sm) on the grain refinement, microstructures and mechanical properties of as-cast AZ31 (Mg–3Al–1Zn–0.3Mn) magnesium (Mg) alloy have been investigated. Very serious grain coarsening happens when Sm content is between 0.16% and 1.18%. This is due to both the reactions between Al and Sm which reduce the constitutional undercooling effect and the lack of Al{sub 2}Sm heterogeneous nuclei. However, excellent grain refinement effect is achieved at Sm content above 2.17%, which is because the in-situ formed Al{sub 2}Sm particles significantly promote heterogeneous nucleation. The main phases in AZ31–xSm alloys include α-Mg, β-Mg{sub 17}Al{sub 12}, Al{sub 11}Sm{sub 3} and Al{sub 2}Sm. The Mg{sub 17}Al{sub 12} phase is gradually suppressed by the increase in Sm content, and the Al{sub 2}Sm is present at a higher Sm content. Because of grain refinement strengthening and secondary phase strengthening effects, the room temperature tensile property of AZ31–3.13Sm alloy has the optimal value of YS78.7MPa–UTS216.7MPa-EL13.6%.

  13. Enhanced magnetoelectric effects in composite of piezoelectric ceramics, rare-earth iron alloys, and shape-optimized nanocrystalline alloys.

    Science.gov (United States)

    Zhang, Jitao; Li, Ping; Wen, Yumei; He, Wei; Yang, Aichao; Lu, Caijiang

    2014-03-01

    An enhancement for magnetoelectric (ME) effects is studied in a three-phase ME architecture consisting of two magnetostrictive Terfenol-D (Tb(0.3)Dy(0.7)Fe(1.92)) plates, a piezoelectric PZT (Pb(Zr,Ti)O3) plate, and a pair of shape-optimized FeCuNbSiB nanocrystalline alloys. By modifying the conventional shape of the magnetic flux concentrator, the shape-optimized flux concentrator has an improved effective permeability (μ(eff)) due to the shape-induced demagnetizing effect at its end surface. The flux concentrator concentrates and amplifies the external magnetic flux into Terfenol-D plate by means of changing its internal flux concentrating manner. Consequently, more flux lines can be uniformly concentrated into Terfenol-D plates. The effective piezomagnetic coefficients (d(33m)) of Terfenol-D plate and the ME voltage coefficients (α(ME)) can be further improved under a lower magnetic bias field. The dynamic magneto-elastic properties and the effective magnetic induction of Terfenol-D are taken into account to derive the enhanced effective ME voltage coefficients (α(ME,eff)), the consistency of experimental results and theoretical analyses verifies this enhancement. The experimental results demonstrate that the maximum d(33m) in our proposed architecture achieves 22.48 nm/A under a bias of 114 Oe. The maximum α(ME) in the bias magnetic range 0-900 Oe reaches 84.73 mV/Oe under the low frequency of 1 kHz, and 2.996 V/Oe under the resonance frequency of 102.3 kHz, respectively. It exhibits a 1.43 times larger piezomagnetic coefficient and a 1.87 times higher ME voltage coefficient under a smaller magnetic bias of 82 Oe than those of a conventional Terfenol-D/PZT/Terfenol-D composite. These shape-induced magnetoelectric behaviors provide the possibility of using this ME architecture in ultra-sensitive magnetic sensors.

  14. Effect of Sr Additive Amount and Holding Time on Microstructure of A390 Aluminum Alloy

    Science.gov (United States)

    Zhang, J. H.; Xing, S. M.; Han, Q. Y.; Guo, Q.; Wang, R. F.

    2017-11-01

    The microstructure of A390 alloy under different Sr additive amounts and holding times was studied by means of direct reading spectrum analysis, energy spectrum analysis, optical microscope and electron microscope. The results show that Sr has a good modification to eutectic Si, while it has a negative effect on primary silicon. The Sr addition will increase the size of primary silicon. When the addition amount of Al-10Sr alloy is 0.6%, the modification of eutectic silicon is the optimum. The Sr has a short incubation period and a fine modification at 10min, but it is more serious burning rate in small furnace smelting, and the modification effect disappears basically after 100min.

  15. Effect of deformation structure on fatigue behavior of an Al-Mg-Sc alloy

    Science.gov (United States)

    Zhemchuzhnikova, Daria; Kaibyshev, Rustam

    2014-08-01

    Effect of initial grain size on fatigue behavior of an Al-6%Mg-0.35%Mn-0.2%Sc- 0.08%Zr-0.07%Cr alloy was examined. The initial CG microstructure with an average grain size of ~ 22 μm was manufactured by casting followed by solution treatment at 360 °C for 12 h. To produce the UFG condition, the alloy was subjected to equal-channel angular pressing (ECAP) at 320 °C up to a total strain of ~ 14. Extensive grain refinement provided the formation of fully recrystallized structure with an average grain size of 700 nm. It was shown that the formation of UFG structure provided +60% increases in yield stress and +25% increases in fatigue strength. Fundamentals of this effect of microstructure on the static strength, fatigue resistance and fracture modes are discussed.

  16. Mean stress effects on high-cycle fatigue of Alloy 718

    International Nuclear Information System (INIS)

    Korth, G.E.

    1980-07-01

    This report covers an investigation of the effects of tensile mean stress on the high-cycle fatigue properties of Alloy 718. Three test temperatures (24, 427, and 649 degree C) were employed, and there were tests in both strain and load control. Results were compared with three different models: linear Modified-Goodman, Peterson cubic, and stress-strain parameter. The linear Modified-Goodman model gave good correlation with actual test data for low and moderate mean stress values, but the stress-strain parameter showed excellent correlation over the entire range of possible mean stresses and therefore is recommended for predicting mean stress effects of Alloy 718. 13 refs., 12 figs

  17. Effects of thermal relaxation on an amorphous superconducting Zr--Rh alloy

    International Nuclear Information System (INIS)

    Drehman, A.J.; Johnson, W.L.

    1978-05-01

    The electronic and superconducting properties of an amorphous transition metal alloy are used to evaluate the effects of low temperature annealing. It is observed that the superconducting transition temperature and the electrical resistivity relax exponentially in time from their initial value to a final relaxed value. From this an activation energy for the relaxation process is derived and an explanation is suggested which involves internal stress

  18. Effect of finishing process on the surface quality of Co-Cr-Mo dental alloys

    Directory of Open Access Journals (Sweden)

    Dorota Klimecka -Tatar

    2016-09-01

    Full Text Available Preparatory procedures for the material have a significant influence on the surface stereometry of the material. This study investigated the effect of the electropolishing process on the surface quality of metallic prosthetic constructions based on Co-Cr-Mo alloys. It has been found that the process of electropolishing prevents to excessive development of the surface of a material and consequently improves surface quality.

  19. Effect of ECAP temperature on microstructure and mechanical properties of Al–Zn–Mg–Cu alloy

    OpenAIRE

    Shaeri, M.H.; Shaeri, M.; Ebrahimi, M.; Salehi, M.T.; Seyyedein, S. H

    2016-01-01

    The effect of equal channel angular pressing (ECAP) at different temperatures (room temperature, 120, 150 and 180 °C) on microstructure and mechanical properties of Al-7075 solid solution alloy was investigated. Microstructure of the specimens was examined using orientation imaging microscopy, transmission electron microscopy as well as X-ray diffractometer, and mechanical properties were measured by Vickers microhardness and tensile tests. Microstructural investigations showed that after 3 o...

  20. Anomalous Hall effect in stoichiometric Heusler alloys with native disorder: A first-principles study

    Czech Academy of Sciences Publication Activity Database

    Kudrnovský, Josef; Drchal, Václav; Turek, Ilja

    2013-01-01

    Roč. 88, č. 1 (2013), "014422-1"-"014422-8" ISSN 1098-0121 R&D Projects: GA ČR(CZ) GAP204/11/1228 Institutional support: RVO:68378271 ; RVO:68081723 Keywords : anomalous Hall effect * Heusler alloys * native disorder * halfmetal * first-principles * linear response theory Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.664, year: 2013

  1. Effect of Boron Addition on the Mechanical Wear Resistance of Additively Manufactured Biomedical Titanium Alloy

    Science.gov (United States)

    Mantri, S. A.; Torgerson, T.; Ivanov, E.; Scharf, T. W.; Banerjee, R.

    2018-03-01

    The effect of the addition of boron to the biomedical alloy Ti-13Nb-13Zr (TNZ) has been studied. A noticeable change between TNZ and TNZ-0.5B has been observed both in terms of morphology, and size scale of the α precipitates along with the in situ formation of TiB precipitates during laser processing. These contrasting microstructures are responsible for differences in mechanical hardness and sliding wear properties and mechanisms.

  2. Effects of atomic and magnetic order on electronic transport in Pd-richPd-Fe alloys

    Czech Academy of Sciences Publication Activity Database

    Kudrnovský, Josef; Drchal, Václav; Khmelevskyi, S.; Turek, Ilja

    2011-01-01

    Roč. 84, č. 21 (2011), "214436-1"-"214436-8" ISSN 1098-0121 R&D Projects: GA ČR(CZ) GAP204/11/1228 Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z20410507 Keywords : residual resistivity * anisotropic magnetoresistance * anomalous Hall effect * PdFe-alloys * spin-orbit coupling * theory Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.691, year: 2011

  3. Magnetocaloric effect of Gd5 Si2 Ge2 alloys in low magnetic field

    Indian Academy of Sciences (India)

    Administrator

    (VSM) and a home-made magnetocaloric effect measuring apparatus, respectively. The maximum ΔSM of the alloys increases by 200% from 4⋅38 to 13⋅32 J kg–1 K–1, the maximum ΔTad increases by 105% from 1⋅9 to. 3⋅9 K when compared to the as-cast due to the homogeneous composition distribution and ...

  4. Magnetocaloric effect of Gd-Tb alloys: influence of the sample shape anisotropy

    Czech Academy of Sciences Publication Activity Database

    Kaštil, J.; Javorský, J.; Kamarád, Jiří; Šantavá, Eva

    2011-01-01

    Roč. 104, č. 1 (2011), s. 205-209 ISSN 0947-8396 R&D Projects: GA ČR GA202/09/0030 Institutional research plan: CEZ:AV0Z10100521 Keywords : magnetic refrigeration * magnetization * specific heat * magnetocaloric effect * Gd-Tb alloy * shape anisotropy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.630, year: 2011

  5. Investigation of localization effect in GaN-rich InGaN alloys and ...

    Indian Academy of Sciences (India)

    The temperature-dependent PL properties of GaN-rich InGa1−N alloys is investigated and -shaped temperature dependence is observed in all InGaN samples. It is found that the origin of localization effect in samples A and B are different from that in sample C. For samples A and B, In content fluctuations should be the ...

  6. Large roomtemperature magnetocaloric effect with negligible magnetic hysteresis losses in Mn1-xVxCoGe alloys

    International Nuclear Information System (INIS)

    Ma, S.C.; Zheng, Y.X.; Xuan, H.C.; Shen, L.J.; Cao, Q.Q.; Wang, D.H.; Zhong, Z.C.; Du, Y.W.

    2012-01-01

    The magnetic and magnetocaloric properties have been investigated in a series of Mn 1-x V x CoGe (x=0.01, 0.02, 0.03, and 0.05) alloys. The substitution of V for Mn reduces the structural transformation temperature of MnCoGe alloy effectively and results in a second-order magnetic transition in Mn 0.95 V 0.05 CoGe alloys. Large room temperature magnetocaloric effect and almost zero magnetic hysteresis losses are simultaneously achieved in the alloys with x=0.01, 0.02, and 0.03. The reasons for the negligible magnetic hysteresis losses and the potential application for the roomtemperature magnetic refrigeration are discussed. - Highlights: → V-substitution for Mn reduces the structural transformation temperature of MnCoGe. → FM-PM transition presents the second-order nature in Mn0.95V0.05CoGe. → The first-order FM-PM transitions are observed for alloys with x=0.01, 0.02, and 0.03. → Large room temperature MCEs are achieved in these alloys. → Negligible magnetic HL is achieved for these alloys simultaneously.

  7. The effect of additional elements on the magnetic properties of hot-rolled Nd-Fe-B alloys

    International Nuclear Information System (INIS)

    Chang, W.C.; Nakamura, H.; Paik, C.R.; Sugimoto, S.; Okada, M.; Homma, M.

    1992-01-01

    The magnetic properties of hot-rolled Nd 16 Fe bal. B 6 M 1.5 (M = Cu, Ga and Al) and Nd 16 Fe 76 B 5.5 Ga 1.5 Al 1 alloys were investigated, in order to study the role of additive elements in improving the magnetic properties in the Nd-Fe-B system. It is found that the original grain size of Cu, Ga or Ga-Al added alloys is much finer than that of the ternary and Al added alloys. But the grain size is almost identical for all the alloys after hot-rolling at 1000degC with 90% reduction in thickness. The coercivity of hot-rolled alloys with Cu, Ga or Ga-Al addition is not improved as was expected, because Nd-rich liquid phase in these alloys is very easily squeezed out during high-reduction-ratio rolling. Less quantity and nonuniform distribution of Nd-rich phase between distributed grains are believed to be the main reasons to depress the effect on the grain boundary smoothing. This effect is not the same as those observed in the Pr-Fe-B system. The highest magnetic properties achieved in this study are B r = 10 kG, i H c = 8.2 kOe, (BH) max = 18.5 MGOe for the Nd 16 Fe 76.5 B 6 Al 1.5 alloy. (orig.)

  8. Effects of heat pipe cooling on permanent mold castings of aluminum alloys

    International Nuclear Information System (INIS)

    Zhang, C.; Mucciardi, F.; Gruzleski, J.E.

    2002-01-01

    The temperature distribution within molds is a critical parameter in determining the ultimate casting quality in permanent mold casting processes, so there is a considerable incentive to develop a more effective method of mold cooling. Based on this consideration, a novel, effective and controllable heat pipe has been successfully developed and used as a new method of permanent mold cooling. Symmetric step casting of A356 alloy have been produced in an experimental permanent mold made of H13 tool steel, which is cooled by such heat pipes. The experimental results show that heat pipes can provide extremely high cooling rates in permanent mold castings of aluminum. The dendrite arm spacing of A356 alloy is refined considerably, and porosity and shrinkage of the castings are redistributed by the heat pipe cooling. Moreover, the heat pipe can be used to determine the time when the air gap forms at the interface between the mold and the casting. The effect of heat pipe cooling on solidification time of castings of A356 alloy with different coating types is also discussed in this paper. (author)

  9. Quantum-mechanical analysis of effect of alloying elements on ε-martensite start temperature of steels.

    Science.gov (United States)

    Jang, J H; Moon, J; Ha, H-Y; Lee, T-H; Suh, D-W

    2017-12-19

    With regard to the transformation mechanism of austenitic high manganese steel, the prediction of the ε-martensite start temperature is a critical consideration in alloy design. Evaluation of the ε-martensite start temperature makes it possible to predict the microstructure and to understand the phase transformation occurring during deformation. Here we use the quantum mechanical calculation of random alloys to understand the physics for ε-martensitic transformation in steels. We could find the linear relationship between the measured ε-martensite start temperatures and the crystal structure stability for various compositions. We also could estimate the effect of several alloying elements. It is expected that the effect of decreasing the temperatures for the same amount of alloying elements addition will be larger moving farther from Group VIII. By creating a free-energy model that reflects the temperature effect, we were able to calculate the average driving force required for the ε-martensitic transformations.

  10. Effects of deep cryogenic treatment on the solid-state phase transformation of Cu-Al alloy in cooling process

    Science.gov (United States)

    Wang, Yuhui; Liao, Bo; Liu, Jianhua; Chen, Shuqing; Feng, Yu; Zhang, Yanyan; Zhang, Ruijun

    2012-07-01

    The solid-state phase transformation temperature and duration of deep cryogenic treated and untreated Cu-Al alloys in cooling process were measured by differential scanning calorimetry measurement. The solid-state phase transformation activation energy and Avrami exponent were calculated according to these measurements. The effects of deep cryogenic treatment on the solid-state phase transformation were investigated based on the measurement and calculation as well as the observation of alloy's microstructure. The results show that deep cryogenic treatment can increase the solid-phase transformation activation energy and shorten the phase transformation duration, which is helpful to the formation of fine grains in Cu-Al alloy.

  11. Effect of directional solidification on the structure and properties of Ni3Al-based alloy single crystals alloyed with Cr, Mo, W, Ti, Co, Re, and REM

    Science.gov (United States)

    Povarova, K. B.; Bondarenko, Yu. A.; Drozdov, A. A.; Bazyleva, O. A.; Antonova, A. V.; Morozov, A. E.; Arginbaeva, E. G.

    2015-01-01

    The effect of the solidification rate ( R = 2, 5, 10, 20 mm/min) at the same solidification gradient ( G = 150°C/cm) on the structural parameters of single-crystal blade workpieces made of an alloy based on the γ'(Ni3Al) intermetallic compound and alloyed with cobalt and rhenium apart from chromium, molybdenum, titanium, and rare-earth metal microadditions is studied. The single crystals have a dendritic-cellular structure. Primary γ'-phase precipitates are observed in the interdendritic space of heterophase γ' + γ dendrites. An increase in the solidification rate from 2 to 20 mm/min at a solidification gradient of 150°C/min leads to refinement of all structural constituents by a factor of 1.5-2, with the morphology and the mutual position of the structural constituents being independent of the solidification rate. In experiments with moderate additional alloying with cobalt and rhenium, the yield strength increases by 10-20% and the long-term strength increases by at least 20-25% at a temperature of 900 and 1100°C upon holding for 100 and 500 h. The VKNA-25 alloy single crystals have moderate plasticity (δ = 6-20%) over the entire temperature range (20-1200°C) and have no sharp increase in the plasticity characteristic of a VKNA-1V alloy without cobalt and rhenium. During long-term tests, local raft structure regions misoriented with respect to the tension direction form in γ' + γ dendrites. γ'-Phase nanoparticles precipitate in the γ layers. During tests, refractorymetal-rich nanoparticles of a predominantly acicular-lamellar shape precipitate in dendrite arms.

  12. The Effect of Toluene Solution on the Hydrogen Absorption of the Mg-Ti Alloy Prepared by Synthetic Alloying

    Directory of Open Access Journals (Sweden)

    H. Suwarno

    2009-07-01

    Full Text Available The synthesis and characterization of the Mg–Ti alloy have been carried out through a mechanical alloying technique under toluene solution. The Mg and Ti powders are milled for 10, 20, and 30 h in a high energy ball mill. The milled alloys are then hydrided at a temperature of 300 oC in order to investigate the possibility used for hydrogen storage materials. The refinement analyses of the x-ray diffraction patterns show that mechanical alloying of the Mg–Ti powders under toluene solution results in the formation of the TiH2 and Mg2Ti phases. Quantitative analyses indicate that the mass fractions of the TiH2 and Mg2Ti phases are 62.90 % and 30.60 %, while the value for Mg and Ti amount to 2.6 wt% and 1.25 wt%. On hydriding at a temperature of 300 oC, the milled powders are transformed into Mg2TiH4, TiH2 and γ-MgH2 phases with the mass fractions of 25.48 wt%, 64.0 wt%, and 10.52 wt%, respectively. Microstructure analyses show that before milling the shape of particle is mostly a ball shape, after 30 h of milling the shape of particles changes into polygonal shape, and upon hydriding the shape of particles changes from a polygonal shape into an irregular one. The final composition of the specimen after hydriding exhibits that Mg-Ti alloy can be promoted as a hydrogen storage material.

  13. Segregation and temperature effect on the atomic structure of Bi30Ga70 liquid alloy

    Science.gov (United States)

    Sbihi, D. Es; Grosdidier, B.; Kaban, I.; Gruner, S.; Hoyer, W.; Gasser, J.-G.

    2009-06-01

    We investigate the structure of liquid monotectic alloy Bi30Ga70 above and below the critical point. The three-dimensional structure at 265 °C is modelled by means of the reverse Monte Carlo simulation technique using neutron and x-ray diffraction experimental data. It is shown that atomic segregation on the short-range scale exists in the liquid Bi30Ga70 slightly above the critical temperature (TC = 262 °C). We present also the structure factors of Bi30Ga70 liquid alloy under the critical point at 240 and 230 °C obtained with neutron diffraction to highlight the temperature effect in the atomic structure.

  14. Effect of Intermediate Annealing on Microstructure and Property of 5182 Aluminum Alloy Sheet for Automobile

    Directory of Open Access Journals (Sweden)

    WANG Yu

    2016-09-01

    Full Text Available Effect of intermediate annealing on the microstructure and properties of 5182 aluminum alloy sheet with full annealed state (5182-O was investigated by means of optical microscope, scanning electron microscope and universal testing machine. The results indicate that compared with 5182-O sheet without intermediate annealing, 5182-O sheet with intermediate annealing possesses too fine grain size, intermetallic compounds not broken enough, larger size intermetallic particles, less dispersed phase. Yield strength and ultimate tensile strength, work hardening exponent and normal anisotropy of plastic strain ratio decrease but planner anisotropy of plastic strain ratio increases. The mechanical properties and forming ability of 5182-O aluminum alloy sheet and its microstructure are not improved significantly after intermediate annealing.

  15. Evaluation of microstructural effects on the corrosion behaviour of AZ91D magnesium alloy

    DEFF Research Database (Denmark)

    Ambat, Rajan; Aung, Naing Naing; Zhou, W.

    2000-01-01

    The effect of microconstituents on the corrosion and electrochemical behaviour of AZ91D alloy prepared by die-casting and ingot casting route has been investigated in 3.5% NaCl solution at pH 7.25. The experimental techniques used include constant immersion technique, in-situ corrosion monitoring...... phase offered marginally lower corrosion rate and better passivation compared with the ingot. In die-cast and ingot, hydrogen evolution took place preferentially on beta phase. XRD pattern of non-corroded and corroded surface revealed the removal of beta phase from alloy surface during corrosion......, and potentiodynamic polarisation experiments. Surface examination and analytical studies were carried out using optical and scanning electron microscopy, EDX and XRD. The corrosion behaviour of microconstituents namely primary alpha, eutectic alpha and beta phases was significantly different. Goring of aluminum...

  16. Methods for evaluation of hydrogen effect on service behaviour of titanium base alloys

    International Nuclear Information System (INIS)

    Mal'kov, A.V.; Kolachev, B.A.

    1979-01-01

    A comparative evaluation of the effect of hydrogen upon the service ability of α, β, α+β and pseudo-α titanium alloys is carried out using the results of various mechanical tests. Presented are the values of the critical concentration of hydrogen, determined by impact strength tests, tensile tests of notched specimens, fracture toughness tests, slow failure tests and the determination of the energy of failure. A hypothesis is advanced that the failure energy of titanium alloys depends directly upon the type of stressed state. This hypothesis explains the S shapes of the curves describing the dependences of the impact strength, the coefficient of stress intensity and the ratios of the tensile strength of smooth and notched specimens upon the hydrogen content

  17. Effects of iron irradiation om microstructure and properties of zirconium alloys: A review

    International Nuclear Information System (INIS)

    Yan, Chun Guang; Wang, Yanli; Wang, Xitao; Wang, Rong Shan; Bai, Guang Hai

    2015-01-01

    Zirconium alloys are widely used in nuclear reactors as structural materials. During the operation, they are exposed to fast neutrons. Ion irradiation is used to simulate the damage introduced by neutron irradiation. In this article, we briefly review the neutron irradiation damage of zirconium alloys, then summarize the effect of ion irradiation on microstructural evolution, mechanical and corrosion properties, and their relationships. The microstructure components consist of dislocation loops, second phase precipitates, and gas bubbles. The microstructure parameters are also included such as domain size and microstrain determined by X-ray diffraction and the S-parameter determined by positron annihilation. Understanding the relationships of microstructure and properties is necessary for developing new advanced materials with higher irradiation tolerance.

  18. Effects of Laser Energies on Wear and Tensile Properties of Biomimetic 7075 Aluminum Alloy

    Science.gov (United States)

    Yuan, Yuhuan; Zhang, Peng; Zhao, Guoping; Gao, Yang; Tao, Lixi; Chen, Heng; Zhang, Jianlong; Zhou, Hong

    2018-03-01

    Inspired by the non-smooth surface of certain animals, a biomimetic coupling unit with various sizes, microstructure, and hardness was prepared on the surface of 7075 aluminum alloy. Following experimental studies were conducted to investigate the wear and tensile properties with various laser energy inputs. The results demonstrated that the non-smooth surface with biomimetic coupling units had a positive effect on both the wear resistance and tensile property of 7075 aluminum alloy. In addition, the sample with the unit fabricated by the laser energy of 420.1 J/cm2 exhibited the most significant improvement on the wear and tensile properties owing to the minimum grain size and the highest microhardness. Also, the weight loss of the sample was one-third of the untreated one's, and the yield strength, the ultimate tensile strength, and the elongation improved by 20, 20, and 34% respectively. Moreover, the mechanisms of wear and tensile properties improvement were also analyzed.

  19. The effect of irradiation and sputtering on the near-surface composition of dilute alloys

    International Nuclear Information System (INIS)

    Marwick, A.D.; Piller, R.C.

    1978-07-01

    A dilute nickel alloy has been irradiated with 75 keV Ni + ions at temperatures between -8.5 0 C and 550 0 C. Redistribution of solute atoms (Al, Mn, Ti, Cr) has been observed at all temperatures, and is ascribed to the action of point defect fluxes in inducing corresponding fluxes of solute atoms. The solute depth profiles were measured by simultaneous sputtering and SIMS. At temperatures above 350 0 C solute atoms migrate into a peak of concentration at 200 A depth, and are depleted at the surface. At lower temperatures, solute atoms migrate out of the damage region, and are enriched near the surface. The effects of these changes on the sputtering of the dilute components of the alloy are discussed. (author)

  20. Effect of plastic media blasting method on mechanical properties of Al 2024-T6 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Uner, Umit [1st Air Supply and Maintenance Centre, Eskisehir (Turkmenistan); Orak, Sezan; Sofuoglu, Mehmet Alper [Dept. of Mechanical Engineering, Eskisehir Osmangazi University, Eskisehir (Turkmenistan)

    2016-11-15

    We investigated the effect of Plastic media blasting (PMB) method on mechanical properties of Al 2024-T6 alloy for aircraft body coatings. Painting-stripping process with three cycles was performed using PMB for three different thicknesses. The relationship between surface morphology-deformation and defects was characterized. PMB affects the fatigue life and surface morphology of specimens. The fatigue life decreases when the specimen thickness decreases. In contrast, this method does not significantly affect the fatigue life of thick specimens. The surface roughness was between 0.30-0.65 Ra for processed specimens. The study will determine proper sheet metal thickness which is not affected seriously because of the method for Al 2024-T6 alloy.

  1. Effect of grain size on superelasticity in Fe-Mn-Al-Ni shape memory alloy wire

    Directory of Open Access Journals (Sweden)

    T. Omori

    2013-09-01

    Full Text Available Effects of grain size on superelastic properties in Fe-34Mn-15Al-7.5Ni alloy wires with a ⟨110⟩ fiber-texture were investigated by cyclic tensile tests. It was confirmed that the critical stress for induced martensitic transformation and the superelastic strain are functions of relative grain size d/D (d: mean grain diameter, D: wire diameter, and that the critical stress is proportional to (1–d/D2 as well as in Cu-based shape memory alloys. A large superelastic strain of about 5% was obtained in the specimen with a large relative grain size over d/D = 1.

  2. The effect of extrusion conditions on the properties and textures of AZ31B alloy

    Directory of Open Access Journals (Sweden)

    Qiang Liu

    2017-06-01

    Full Text Available The effect of extrusion conditions on the tensile properties and texture of AZ31B alloy has been investigated by means of optical microscopy (OM, scanning electron microscopy (SEM, electron backscattered diffraction (EBSD and tensile tests. It is found that the ultimate tensile strength (UTS, the yield strength (YS and elongation (EN of the extruded AZ31B alloy are more significantly influenced by extrusion velocities in contrast with temperature. Although the extrusion conditions are different, the {112¯0} 〈011¯0〉 texture is the chief texture in the AZ31B after extrusion. Moreover, the extrusion textures become scattered with increasing the temperatures at the same extrusion velocity. As the extrusion velocity is raised at the same temperature, the orientation density of textures increases and the separated textures become relatively concentrated. This leads to the changes of tensile properties at different extrusion conditions.

  3. An Investigation into the Effect of Aging on the Forming Limit Diagram of 6063 Aluminum Alloy

    International Nuclear Information System (INIS)

    Hosseini, S. M.; Hosseimpour, S. J.; Nourouzi, S.; Gorji, A. H.

    2011-01-01

    In this study, the effect of ageing on the forming limit diagram of a commercially available 6063 aluminum alloy has been investigated. For this purpose, initially the specimens have been aged at 200 deg. C and at various times. The hardness tests have been carried out and the hardness-aging time curve has been obtained for this alloy. Moreover, the mechanical properties were determined by tensile test. Then, the forming limit diagrams have been achieved by using the out-of-plane formability test method at four different conditions containing: annealed, under-aged, peak-aged, and over-aged. The results indicate that in comparing with the annealed condition the FLD 0 decreases significantly from the under-aged condition to the peak-aged condition and increases slightly from the peak-aged condition to the over-aged condition.

  4. Effects of HSHPT on the martensitic transformation behaviour of an NiTi alloy

    Directory of Open Access Journals (Sweden)

    Gurau Carmela

    2015-01-01

    Full Text Available High speed high pressure torsion (HSHPT is a novel severe plastic deformation technique that is used to produce bulk ultrafine-grained nickel-titanium shape memory alloys. In this study, the effect of grain refinement on phase transformation was investigated in a near equiatomic NiTi shape memory alloy subjected to processing by this technique. Phase transformations involving different degrees of deformation and stability of thermally-induced phase transformations were analyzed by differential scanning calorimetry (DSC. The measurements suggest that the martensitic transformation occurred even when the highest degree of deformation was applied. Optical microscopy (OM, scanning electron microscopy (SEM and transmission electron microscopy (TEM investigations bring to light that the true strain applied controls the evolution of the microstructure. The results are presented and discussed in detail in this paper.

  5. EFFECT OF ALLOYING ON TEMPERATURE OF TRANSFORMATION «PEARLITE – AUSTENITE» IN COMPLEX-ALLOYED WHITE CAST IRONS

    Directory of Open Access Journals (Sweden)

    T. V. Pastukhova

    2014-11-01

    Full Text Available Purpose. Pearlite is not accepted in the microstructure of wear resistant steels and cast irons. To prevent the pearlite by means of appropriate selection of mode of quenching requires the knowledge of the temperature of the critical points Ac1 and Ac3 for various steels and cast irons. Purpose of work is determine the effect of V (5-10% and Cr (up to 9% on the temperature range of the phase-structural transformation "pearlite®austenite in the complex-alloyed V-Cr-Mn-Ni white cast irons with spheroidal vanadium carbides. Methodology. Nine Mg-treated cast irons smelted in laboratory furnace were used for investigation. The metallographic and optical dilatometric analysis methods as well as energy-dispersive spectroscopy were used. Findings. It is shown that in irons studied the critical point Ac1 is in a temperature range from 710-780 °C (lower limit up to 730-850 °C (upper limit. The data on the concentrations of chromium and vanadium in a matrix of iron are presented, the regression equation describing the effect of vanadium and chromium on the temperature limits of the transformation «pearlite ® austenite» are obtained. Originality. It is shown that increase the chromium content leads to growth of lower and upper limits of the temperature interval of transformation "pearlite ® austenite"; vanadium increases only the upper limit of the range. It was found that the effect of chromium on the critical point Ac1 is attributed to its solubility in the metallic matrix (concentration of Cr in the austenite reaches 7%; vanadium, due to its slight dissolution in the matrix (vanadium content does not exceed 1.75%, affects the critical point indirectly by increasing of chromium concentration in the matrix due to enhanced carbon sequestration in VC carbides. Practical value. The temperature ranges of heating for quenching of V-Cr-Mn-Ni cast irons with spheroidal vanadium carbides, which provides the formation of austenitic-martensitic matrix without

  6. Castability of Magnesium Alloys

    Science.gov (United States)

    Bowles, A. L.; Han, Q.; Horton, J. A.

    There is intense research effort into the development of high pressure die cast-able creep resistant magnesium alloys. One of the difficulties encountered in magnesium alloy development for creep resistance is that many additions made to improve the creep properties have reportedly resulted in alloys that are difficult to cast. It is therefore important to have an understanding of the effect of alloying elements on the castability. This paper gives a review of the state of the knowledge of the castability of magnesium alloys.

  7. Solution chemistry effects on the stress corrosion cracking behavior of alloy 2090 (Al-Li-Cu) and alloy 2024 (Al-Cu-Mg)

    Science.gov (United States)

    Moran, James P.; Stoner, Glenn E.

    1989-01-01

    The SCC initiation behavior of alloys 2090 and 2024 is examined in various NaCl-based environments. The pre-exposure and bulk/local solution chemistry effects discovered by Holroyd et al. (1986) are investigated, with emphasis on the effect of bulk solution chemistries and atmospheric CO2 on the occluded cell environment and the role of the occluded environment in the crack initiation and early-stage propagation processes. It was found that constant immersion in NaCl does not promote SCC in alloy 2090 or alloy 2024. Upon removal from NaCl, SCC is quickly facilitated, but only in the presence of atmospheric CO2. The need for CO2 is attributed to an increase in carbonate concentrations, eventually allowing passivation of blunted fissures by precipitation of Li2CO3. It is inferred that any effects due to aging are small in magnitude, relative to the effects of subtle changes in the bulk/local solution chemistries.

  8. Effect of Mg-Zn-Nd spherical quasi-crystals on microstructure and mechanical properties of ZK60 alloy

    Directory of Open Access Journals (Sweden)

    Zhang Jinshan

    2011-08-01

    Full Text Available To improve the strength, toughness, heat-resistance and deformability of magnesium alloy, the microstructure and mechanical properties of ZK60 alloy strengthened by Mg-Zn-Nd spherical quasi-crystal phase (I-phase particles were investigated. Mg40Zn55Nd5 (I-phase particles in addition to α-Mg, MgZn phase and MgZn2 phases can be obtained in ZK60-based composites under normal casting condition by the addition of quasi-crystal containing Mg-Zn-Nd master alloy. The experimental results show that the introduction of Mg-Zn-Nd spherical quasi-crystal phase into ZK60 alloy makes a great contribution to the refinement of the matrix microstructures and the improvement of mechanical properties. While adding Mg-Zn-Nd spherical quasi-crystal master alloy of 4.0wt.%, the ultimate tensile strength and yield strength of ZK60-based composite at ambient temperature reach their peak values of 256.7 MPa and 150.4 MPa, which were about 17.8% and 24.1% higher respectively than those of the ZK60 alloy. The improved mechanical properties are mainly attributed to the pinning effect of the quasi-crystal particles (I-phase at the grain boundaries. This research results provide a new way for strengthening and toughening of magnesium alloys as well as a new application of Mg-based spherical quasi-crystals.

  9. Effect of solidification rate on the microstructure and microhardness of a melt-spun Al-8Si-1Sb alloy

    International Nuclear Information System (INIS)

    Karakoese, E.; Keskin, M.

    2009-01-01

    The properties of rapidly solidified hypoeutectic Al-8Si-1Sb alloy, produced by melt-spinning technique at a different solidification rates, were investigated using the X-ray diffraction (XRD), the optical microscopy (OM), the scanning electron microscopy (SEM) together with the energy dispersive spectroscopy (EDS), the differential scanning calorimetry (DSC) and the microhardness technique. The properties of rapidly solidified ribbons were then compared with those of the chill-casting alloy. The results show that rapid solidification has influence on the phase constitution of the hypoeutectic Al-8Si-1Sb alloy. The phases present in the hypoeutectic Al-8Si-1Sb ingot alloy were determined to be α-Al, fcc Si and intermetallic AlSb phases whereas only α-Al and fcc Si phases were identified in the melt-spinning alloy. The rapid solidification has a significant effect on the microstructure of the hypoeutectic Al-8Si-1Sb alloy. Particle size in the microstructure of the ribbons is too small to compare with particle size in the microstructure of the ingot alloy. Moreover, the significant change in hardness occurs that is attributed to changes in the microstructure.

  10. Effect of solidification rate on the microstructure and microhardness of a melt-spun Al-8Si-1Sb alloy

    Energy Technology Data Exchange (ETDEWEB)

    Karakoese, E. [Erciyes University, Institute of Science, 38039 Kayseri (Turkey); Keskin, M. [Erciyes University, Institute of Science, 38039 Kayseri (Turkey); Erciyes University, Physics Department, 38039 Kayseri (Turkey)], E-mail: keskin@erciyes.edu.tr

    2009-06-24

    The properties of rapidly solidified hypoeutectic Al-8Si-1Sb alloy, produced by melt-spinning technique at a different solidification rates, were investigated using the X-ray diffraction (XRD), the optical microscopy (OM), the scanning electron microscopy (SEM) together with the energy dispersive spectroscopy (EDS), the differential scanning calorimetry (DSC) and the microhardness technique. The properties of rapidly solidified ribbons were then compared with those of the chill-casting alloy. The results show that rapid solidification has influence on the phase constitution of the hypoeutectic Al-8Si-1Sb alloy. The phases present in the hypoeutectic Al-8Si-1Sb ingot alloy were determined to be {alpha}-Al, fcc Si and intermetallic AlSb phases whereas only {alpha}-Al and fcc Si phases were identified in the melt-spinning alloy. The rapid solidification has a significant effect on the microstructure of the hypoeutectic Al-8Si-1Sb alloy. Particle size in the microstructure of the ribbons is too small to compare with particle size in the microstructure of the ingot alloy. Moreover, the significant change in hardness occurs that is attributed to changes in the microstructure.

  11. [The effect of hydrogen peroxide on the electrochemical corrosion properties and metal ions release of nickel-chromium dental alloys].

    Science.gov (United States)

    Wang, Jue; Qiao, Guang-yan

    2013-04-01

    To investigate the effect of hydrogen peroxide on the electrochemical corrosion and metal ions release of nickel-chromium dental alloys. The corrosion resistance of nickel-chromium dental alloys was compared by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curve (PD) methods in artificial saliva after immersed in different concentrations of hydrogen peroxide for 112 h. The metal ions released from nickel-chromium dental alloys to the artificial saliva were detected after electrochemical measurements using inductively coupled plasma mass spectrometry (ICP-MS). The data was statistically analyzed by analysis of variance (ANOVA) using SPSS 13.0 software package. The electrochemical experiment showed that the sequence of polarization resistance in equivalent circuit (Rct), corrosion potential (Ecorr), pitting breakdown potential (Eb), and the difference between Ecorr and Eb representing the "pseudo-passivation" (δE) of nickel-chromium alloys in artificial saliva was 30% alloys to the artificial saliva, and the order of the concentrations of metal ions was 0% corrosion resistance of nickel-chromium dental alloys decrease after immersed in different concentrations of hydrogen peroxide for 112 h. Nickel-chromium dental alloys are more prone to corrosion in the artificial saliva with the concentration of hydrogen peroxide increased, and more metal ions are released in the artificial saliva.

  12. Magneto-caloric effect of a Gd50Co50 amorphous alloy near the freezing point of water

    Directory of Open Access Journals (Sweden)

    L. Xia

    2015-09-01

    Full Text Available In the present work, we report the magneto-caloric effect (MCE of a binary Gd50Co50 amorphous alloy near the freezing temperature of water. The Curie temperature of Gd50Co50 amorphous ribbons is about 267.5 K, which is very close to room temperature. The peak value of the magnetic entropy change (-ΔSmpeak and the resulting adiabatic temperature rise (ΔTad. of the Gd50Co50 amorphous ribbons is much higher than that of any other amorphous alloys previously reported with a Tc near room temperature. On the other hand, although the -ΔSmpeak of Gd50Co50 amorphous ribbons is not as high as those of crystalline alloys near room temperature, its refrigeration capacity (RC is still much larger than the RC values of these crystalline alloys. The binary Gd50Co50 amorphous alloy provides a basic alloy for developing high performance multi-component amorphous alloys near room temperature.

  13. Understanding effects of microstructural inhomogeneity on creep response – New approaches to improve the creep resistance in magnesium alloys

    Directory of Open Access Journals (Sweden)

    Yuanding Huang

    2014-06-01

    Full Text Available Previous investigations indicate that the creep resistance of magnesium alloys is proportional to the stability of precipitated intermetallic phases at grain boundaries. These stable intermetallic phases were considered to be effective to suppress the deformation by grain boundary sliding, leading to the improvement of creep properties. Based on this point, adding the alloying elements to form the stable intermetallics with high melting point became a popular way to develop the new creep resistant magnesium alloys. The present investigation, however, shows that the creep properties of binary Mg–Sn alloy are still poor even though the addition of Sn possibly results in the precipitation of thermal stable Mg2Sn at grain boundaries. That means other possible mechanisms function to affect the creep response. It is finally found that the poor creep resistance is attributed to the segregation of Sn at dendritic and grain boundaries. Based on this observation, new approaches to improve the creep resistance are suggested for magnesium alloys because most currently magnesium alloys have the commonality with the Mg–Sn alloys.

  14. Thermal Mechanical Processing Effects on Microstructure Evolution and Mechanical Properties of the Sintered Ti-22Al-25Nb Alloy.

    Science.gov (United States)

    Wang, Yuanxin; Lu, Zhen; Zhang, Kaifeng; Zhang, Dalin

    2016-03-11

    This work illustrates the effect of thermal mechanical processing parameters on the microstructure and mechanical properties of the Ti-22Al-25Nb alloy prepared by reactive sintering with element powders, consisting of O, B2 and Ti₃Al phases. Tensile and plane strain fracture toughness tests were carried out at room temperature to understand the mechanical behavior of the alloys and its correlation with the microstructural features characterized by scanning and transmission electron microscopy. The results show that the increased tensile strength (from 340 to 500 MPa) and elongation (from 3.6% to 4.2%) is due to the presence of lamellar O/B2 colony and needle-like O phase in B2 matrix in the as-processed Ti-22Al-25Nb alloys, as compared to the coarse lath O adjacent to B2 in the sintered alloys. Changes in morphologies of O phase improve the fracture toughness ( K IC ) of the sintered alloys from 7 to 15 MPa·m -1/2 . Additionally, the fracture mechanism shifts from cleavage fracture in the as-sintered alloys to quasi-cleavage fracture in the as-processed alloys.

  15. A study of microstructures responsible for the emergence of the invar and permalloy effects in Fe–Ni alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ustinovshikov, Y., E-mail: ust@ftiudm.ru; Shabanova, I.

    2013-11-25

    Highlights: •Phase transition ‘ordering-phase separation’ occurs in Fe–Ni alloys at about 600 °C. •A modulated structure is the main reason of the invar properties of Fe–Ni alloys. •A two-phase fully coherent γ + L1{sub 2} structure is the main cause of permalloy properties. -- Abstract: The paper presents experimental results obtained by transmission electron microscopy and X-ray photoelectron spectroscopy on the Fe{sub 68}Ni{sub 32} and Fe{sub 23}Ni{sub 77} alloys, which indicate that in these alloys, the phase transition ordering-phase separation occurs in the temperature range near 600 °C. Above the transition temperature, the sign of the ordering energy is positive; clusters enriched in atoms of one of the components are observed in the structure of the alloys. A modulated microstructure is formed after heat treatment at temperatures, at which the invar effect in the Fe{sub 68}Ni{sub 32} alloy is the maximum. Below the transition temperature, the sign of the ordering energy is negative, which determines a tendency to form chemical compounds. After aging at these temperatures, when the Fe{sub 23}Ni{sub 77} alloy has high permalloy properties, highly-dispersed fully coherent particles of the L1{sub 2} (γ′) phase are found to precipitate in the solid solution.

  16. The Effect of Rotation Stirring on Macrosegregation in Bi-Sn Alloy

    Directory of Open Access Journals (Sweden)

    Zulaida Yeni Muriani

    2017-01-01

    Full Text Available Macrosegregation is a defect that difficult to avoid in a metal alloy made by casting method. Macrosegregation can cause decreasing in mechanical properties of casting products. It will reduce their performance in industrial application. Macrosegregation is convinced occur during solidification time in liquid alloy. In the early solidified, The solids move upward/downward in liquid alloy during solidification are considered to contribute on macrosegregation formation. This movement occur due to the density differences between the solid and the surrounding liquid. This research want to observe the effect of stirring on macrosegregation formation for interfering on the movement of initial solidified solid. Stiring with rotation method is applied in this experiment at certain temperature. The temperature and the rotation speed of stirring are varied to observe the effect of rotation stirring on macrosegregation formation. The mold is covered by insulation jacket and kept the bottom part opened in order to obtain the directionally solidification. The result shows that the rotation stirring can change the macrostructure of casting but in case of composition distribution, the macrosegregation still appear. Increasing the rotation stirring will rise solid crystals up and the macrosegregation become more uniform and the treatment is better if conducting at lower temperature.

  17. On the PLC Effect in a Particle Reinforced AA2017 Alloy

    Directory of Open Access Journals (Sweden)

    Markus Härtel

    2018-01-01

    Full Text Available The Portevin–Le Châtelier (PLC effect often results in serrated plastic flow during tensile testing of aluminum alloys. Its magnitude and characteristics are often sensitive to a material’s heat treatment condition and to the applied strain rate and deformation temperature. In this study, we analyze the plastic deformation behavior of an age-hardenable Al-Cu alloy (AA2017 and of a particle reinforced AA2017 alloy (10 vol. % SiC in two different conditions: solid solution annealed (W and naturally aged (T4. For the W-condition of both materials, pronounced serrated flow is observed, while both T4-conditions do not show distinct serrations. It is also found that a reduction of the testing temperature (−60 °C, −196 °C shifts the onset of serrations to larger plastic strains and additionally reduces their amplitude. Furthermore, compressive jump tests (with alternating strain rates at room temperature confirm a negative strain rate sensitivity for the W-condition. The occurring PLC effect, as well as the propagation of the corresponding PLC bands in the W-condition, is finally characterized by digital image correlation (DIC and by acoustic emission measurements during tensile testing. The formation of PLC bands in the reinforced material is accompanied by distinct stress drops as well as by perceptible acoustic emission, and the experimental results clearly show that only type A PLC bands occur during testing at room temperature (RT.

  18. Effect of chemical composition and cooling conditions on solidification hot cracking of Ni-based alloys

    International Nuclear Information System (INIS)

    De Vito, Sophie

    2000-01-01

    Ni-based alloys 690 present solidification hot cracks during welding of vapour generators. Hot cracks are qualitatively known to be due to the formation of inter-dendritic liquid films and of secondary phases down to low temperatures. This study aims at establishing the link between thermodynamics, solidification and hot cracking. Experimental solidification paths of high purity alloys (with varying Nb and Si contents) are obtained from quenching during directional solidification and TIG-welding experiments. They are compared to Thermo-Calc computations, assuming no diffusion in the solid. From directional solidification samples, good agreement between computed and experimental solidification paths is shown in the quenched liquid. Secondary arms of dendrites are affected by solid state diffusion of Nb. Combined effect of diffusion and solute build-up in the liquid phase modifies micro-segregation in the solid region. Solidification paths from welding specimens are similar to those of the solid region of quenched samples. Nb solid state diffusion is negligible but undercooling compensates the effect of solid state diffusion in directional solidification. Evolution of liquid fraction at the end of the solidification is in accordance with the hot cracking classification of the alloys. Nb favours formation of inter-dendritic liquid films and eutectic-like phases down to low temperature. (author) [fr

  19. Effect of cutting parameters on machinability characteristics in milling of magnesium alloy with carbide tool

    Directory of Open Access Journals (Sweden)

    Kaining Shi

    2016-01-01

    Full Text Available Magnesium alloy has attracted more attentions due to its excellent mechanical properties. However, in process of dry cutting operation, many problems restrict its further development. In this article, the effect of cutting parameters on machinabilities of magnesium alloy is explored under dry milling condition. This research is an attempt to investigate the impact of cutting speed at multiple feed rates on cutting force and surface roughness, while a statistical analysis is adopted to determine the influential intensities accurately. The results showed that cutting force is affected by the positively constant intensity from feed rate and the increasingly negative intensity from cutting speed. In contrast, surface roughness is determined by the gradually increasing negative tendency from feed rate and the positive effect with constant intensity from cutting speed. Within the range of the experiments, feed rate is the leading contribution for cutting force while the cutting speed is the dominant factor for surface roughness according to the absolute intensity values. Meanwhile, the trends of influencing intensities between cutting force and surface roughness are opposite. Besides, it is also found that in milling magnesium alloy, chip morphology is highly sensitive to cutting speed while the chip quality mainly depends on feed rate.

  20. Novel magnesium alloy Mg–2La caused no cytotoxic effects on cells in physiological conditions

    Energy Technology Data Exchange (ETDEWEB)

    Weizbauer, Andreas, E-mail: weizbauer.andreas@mh-hannover.de [Laboratory for Biomechanics and Biomaterials, Department of Orthopedic Surgery, Hannover Medical School, Anna-von-Borries-Straße 1-7, 30625 Hannover (Germany); CrossBIT, Center for Biocompatibility and Implant-Immunology, Department of Orthopedic Surgery, Hannover Medical School, Feodor-Lynen-Str. 31, 30625 Hannover (Germany); Seitz, Jan-Marten [Institute of Materials Science, Leibniz Universität Hannover, An der Universität 2, 30823 Garbsen (Germany); Werle, Peter [ABB AG, Trafoweg 4, 06112 Halle (Germany); Hegermann, Jan [Institute of Functional and Applied Anatomy, Hannover Medical School, Carl-Neuberg-Straße 1, 30625 Hannover (Germany); Willbold, Elmar [Laboratory for Biomechanics and Biomaterials, Department of Orthopedic Surgery, Hannover Medical School, Anna-von-Borries-Straße 1-7, 30625 Hannover (Germany); CrossBIT, Center for Biocompatibility and Implant-Immunology, Department of Orthopedic Surgery, Hannover Medical School, Feodor-Lynen-Str. 31, 30625 Hannover (Germany); Eifler, Rainer [Institute of Materials Science, Leibniz Universität Hannover, An der Universität 2, 30823 Garbsen (Germany); Windhagen, Henning [Laboratory for Biomechanics and Biomaterials, Department of Orthopedic Surgery, Hannover Medical School, Anna-von-Borries-Straße 1-7, 30625 Hannover (Germany); Reifenrath, Janin [Small Animal Clinic, University of Veterinary Medicine Hannover, Bünteweg 9, 30559 Hannover (Germany); Waizy, Hazibullah [Laboratory for Biomechanics and Biomaterials, Department of Orthopedic Surgery, Hannover Medical School, Anna-von-Borries-Straße 1-7, 30625 Hannover (Germany)

    2014-08-01

    Using several different in vitro assays, a new biodegradable magnesium alloy Mg–2La, composed of 98% magnesium and 2% lanthanum, was investigated as a possible implant material for biomedical applications. An in vitro cytotoxicity test, according to EN ISO 10993-5/12, with L929 and human osteoblastic cells identified no toxic effects on cell viability at physiological concentrations (at 50% dilutions and higher). The metabolic activity of human osteoblasts in the 100% extract was decreased to < 70% and was therefore rated as cytotoxic. The degradation rates of Mg–2La were evaluated in phosphate buffered saline and four different cell culture media. The degradation rates were shown to be influenced by the composition of the solution, and the addition of fetal bovine serum slightly accelerated the corrosive process. The results of these in vitro experiments suggest that Mg–2La is a promising candidate for use as an orthopedic implant material. - Highlights: • A new magnesium alloy (Mg–2La) has been developed. • Magnesium alloy Mg–2La revealed no toxic effect in physiological concentrations. • Degradation rates were influenced by the corrosion media. • The addition of fetal bovine serum increased the corrosive process slightly.

  1. Effect of irradiation on the critical currents of alloy and compound superconductors

    International Nuclear Information System (INIS)

    Sekula, S.T.

    1977-06-01

    The effects of energetic-particle irradiation on the critical-current density J/sub c/(H) of several superconducting compounds and Nb-Ti alloys have been examined by a number of workers. The irradiations used in the investigations include electrons, fast neutrons, ions, and fission fragments. The results of these studies are reviewed and summarized. In the alloys, changes in J/sub c/(H) on irradiation depend on the metallurgical history of the material and indicate that radiation defects modify the strength of the interaction between the fluxoid array and the sample microstructure. Radiation defects in alloys can also affect J/sub c/(H) through small decreases in T/sub c/, the transition temperature and rho, the normal-state resistivity. Irradiations of A15 compounds up to moderate fluences (dependent on the type and energy of irradiating particle) lead to decreases in T/sub c/ of approximately 1 0 K and increases in J/sub c/(H) with dose for most of the samples investigated. This result can be qualitatively understood as resulting from radiation-induced changes in rho and the pinning force acting on the fluxoids. At higher dose levels, significant depressions of T/sub c/ and possibly gamma, the electronic specific heat coefficient, lead to drastic reductions in J/sub c/(H). The effect of various energetic particles and irradiation temperature on changes in J/sub c/(H) are discussed

  2. Bauschinger effect in α-γ dual phase alloys studied by in situ neutron diffraction

    International Nuclear Information System (INIS)

    Harjo, Stefanus; Tomota, Yo

    2002-01-01

    In situ neutron diffraction experiments during tension-compression deformation were performed on five Fe-Cr-Ni alloys with the volume fraction of ferrite (α) ranging from 0.0 to 100%. Tensile deformation was applied in a step by step manner up to a strain of 1.3-2.0% followed by compressive deformation, and neutron diffraction spectra were recorded during temporary stops of a deformation machine with fixed crosshead. (111) reflection of austenite and (110) of ferrite, respectively, were measured simultaneously by using a position sensitive detector. Elastic lattice strains in both constituent phases were evaluated from measured diffraction spectra as a function of external load. Based on these experimental results, heterogeneous deformation behavior in the α-γ dual phase alloys is discussed considering the Bauschinger effect. It is concluded that large compressive residual lattice strains detected in the γ phase after tensile pre-straining, causes the large Bauschinger effect in α-γ dual phase alloys. (author)

  3. Radiation therapy: dosimetry study of the effect of the composition of Pb alloys by PENELOPE

    Directory of Open Access Journals (Sweden)

    Jose McDonnell

    2011-02-01

    Full Text Available Radiotherapy is a widely used treatment for cancer. Currently applying the technique of Intensity Modulated Radiation Therapy, in which an important aspect is the modulation of the radiation beam to generate a non-uniform dose distribution in the tumor. One way to achieve the above non-uniform dose distribution is using solid compensators. In the market there are a number of materials used to manufacture compensators. Pb alloys on the market are: Cerromatrix, Rose, Wood, Newton, Darcet, whose compositions vary with respect to the composition of the lipowitz metal. This paper quantifies the dosimetric effects of the composition of commercial alloys, routinely used in radiotherapy. This quantification is important because of its impact on the total uncertainty of treatment accepted in the dosimetric calculations. To investigate the dosimetric effect of the composition of commercial alloys in the market we used the PENELOPE code, code that allows the simulation of radiation transport in different media by Monte Carlo method.The results show that there is a difference dosimetric respect lipowitz material, ranging from 7 % to 9 % for the materials investigated. These values indicate the importance of knowing exactly the dosimetric characteristics of the material used as compensator for their implications in the dose calculation.

  4. Invar Effect and non-collinear magnetism in FeCu alloys

    Energy Technology Data Exchange (ETDEWEB)

    Eisenbach, Markus [ORNL; Stocks, George Malcolm [ORNL

    2009-01-01

    The Invar effect has been observed in many Fe rich alloys, most famously Ni Invar. Generally the Invar behavior is associated with the strong coupling between the lattice and magnetic degrees of freedom, and therefore depends on the magnetic ordering in these alloys. Recent experimental works observed an Invar effect in fcc-FeCu solid solutions. In the present paper the magnetic states of fcc-FeCu solid solutions for various concentrations is investigated. The first principles calculations employ the locally selfconsistent multiple scattering (LSMS) real space method for solving the LDA Kohn-Sham equation to investigate the non collinear ordering of magnetic moments. The magnetic order for the low iron concentration is fount to be non-collinear, spin glass like, and the ferromagnetic order is not stable, whereas for the iron rich alloys for the ground state equilibrium lattice constants a magnetic order with parallel aligned Fe moments is stable. In this configuration the induced moments at the Cu sites order nontrivially on a cone with an opening of approximately 40 degrees around the Fe moment direction.

  5. Neutron irradiation effects on the microstructural development of tungsten and tungsten alloys

    Science.gov (United States)

    Hasegawa, Akira; Fukuda, Makoto; Yabuuchi, Kiyohiro; Nogami, Shuhei

    2016-04-01

    Data on the microstructural development of tungsten (W) and tungsten rhenium (Re) alloys were obtained after neutron irradiation at 400-800 °C in the Japan Materials Testing Reactor (JMTR), the experimental fast test reactor Joyo, and the High Flux Isotope Reactor (HFIR) for irradiation damage levels in the range of 0.09-1.54 displacement per atom (dpa). Microstructural observations showed that a small amount of Re (3-5%) in W-Re alloys is effective in suppressing void formation. In W-Re alloys with Re concentrations greater than 10%, acicular precipitates are the primary structural defects. In the HFIR-irradiated specimen, in which a large amount of Re was expected to be produced by the nuclear transmutation of W to Re because of the reactor's high thermal neutron flux, voids were not observed even in pure W. The synergistic effects of displacement damage and solid transmutation elements on microstructural development are discussed, and the microstructural development of tungsten materials utilized in fusion reactors is predicted.

  6. Effect of the electrode position conditions on the morphology and corrosion behavior of Ni-Co alloys part 2: Phase composition and corrosion behavior of Ni-Co alloys, electrodeposited from citrate electrolyte

    International Nuclear Information System (INIS)

    Ignatova, Katya; Avdeev, Georgi

    2016-01-01

    The changes in the phase composition (through X-Ray analysis) and the corrosion behaviors (through potentiodynamic polarization studies in 4 % NaCl) of Ni-Co alloys, electrodeposited from a citrate electrolyte by changing the Ni/Co ratio, content of organic additive (saccharine) and the content of sodium citrate in the solution, are studied. It is found that the increase of Ni/Co ratio from 1 to 5 increases the content of Ni in the Ni-Co alloy to 48 mass %. The proportion between the phases of Co and Ni with cubic face-centered crystal lattice is in approximate compliance with the proportion of the two metals in the alloy. The peaks in the difractograms are weak and stretched, which corresponds to the nano-sized structure of the alloy. The Ni-Co alloys with highest content of Ni have a higher corrosion resistance compared to those containing a higher percentage of Co. It is also shown that the Ni-Co coatings obtained in the presence of addition of saccharine show a much higher corrosion resistance than the coatings obtained in absence of additive. Ni-Co alloys, deposited from electrolyte with more sodium citrate show only a slight growth of Ni content and the effect of sodium citrate on corrosion behaviors of the alloy is insignificant. Keywords: phase composition, corrosion behavior, Ni-Co alloys, nanostructured alloys.

  7. Deformation mechanisms and irradiation effects in zirconium alloys. A multi-scale study

    International Nuclear Information System (INIS)

    Onimus, Fabien

    2015-01-01

    occurs at high doses, the nucleation and growth of loops, has been particularly studied. The effects of the hydrogen pick up and of an external applied stress on loops have been characterized by TEM. This work, which already contributes to a better understanding of deformation mechanisms and mechanical behavior of zirconium alloys, should improve, in a future prospect, the reliability and performance of pressurized water reactors fuel assemblies. (author) [fr

  8. Effect of fiber laser parameters on laser welded AZ31B Magnesium alloys

    Directory of Open Access Journals (Sweden)

    Mat Salleh Naqiuddin

    2017-01-01

    Full Text Available Recently, the usage of Magnesium (Mg alloys has been hugely applied in the industrial application such as in automotive, marine, and electronic due to its advantages of recyclability and lightweight. This alloys required low heat input to be weld since it is easily evaporated due to the Magnesium Oxide (MgO at the surface and it also possesses lower melting point compared to steel. Laser welding is more convenient to weld Mg alloys due to its high power and lower heat input. AZ31B was selected since it has strong mechanical properties among others Mg alloys due to the major alloying elements; Aluminium (Al and Zinc (Zn. Low power fiber laser machine with wavelength of 900 nm was used in this experiment. The intention of this work was to investigate the effect of low power fiber laser parameters and effect of shielding gas on weld penetration and microstructure. Another aim in this work was to produce the joint for this thin sheets metal. Penetration depth and microstructure evaluation were emphasized in the analysis section. Bead-on-Plate (BOP and laser lap welding was conducted on AZ31B with thicknesses of 1.0 mm and 0.6 mm for feasibility study using pulsed wave (PW mode. Defocusing features was used in order to find better focal position, which has less occurrence of evaporation (underfill. The effect of different angle of irradiation was also investigated. Two types of shielding gases, Argon (Ar and Nitrogen (N2 were used in order to study the effect of shielding gas. Lastly, the effect of pulsed energy on penetration types and depth of BOP welded samples was investigated. Focus point was found at focal length of 156 mm with 393.75 μm. For BOP experiment, higher pulsed energy used contributes to melt through defect. Meanwhile, Ns shielding gas proved to be better shielding gas in laser welding the AZ31B. Higher angle of irradiation could reduce the underfill defect. Fillet Lap joint of similar metal was successfully done where 2.0 J of

  9. Effects of neutron irradiation at 4500C and 16 dpa on the properties of various commercial copper alloys

    International Nuclear Information System (INIS)

    Brager, H.R.; Heinisch, H.L.; Garner, F.A.

    1985-01-01

    High-purity copper and eight copper alloys were irradiated to approx.16 dpa at approx.450 0 C in the MOTA experiment in FFTF. These alloys were also examined after aging at 400 0 C for 1000 hours. The radiation-induced changes in the electrical conductivity, tensile properties, and density were measured and compared to those of the aged materials. The changes in conductivity can be either positive or negative depending on the alloy. Changes in tensile properties of most, but not all, of the alloys seem to be primarily dependent on thermal effects rather than the effect of atomic displacements. Radiation at 450 0 C induced changes in density varying from 0.66% densification to 16.6% swelling. The latter occurred in Cu-O.1% Ag and implies a swelling rate of at least 1%/dpa. 6 references, 3 figures, 2 tables

  10. Alloying effect on the room temperature creep characteristics of a Ti-Zr-Be bulk metallic glass

    Science.gov (United States)

    Gong, Pan; Wang, Sibo; Li, Fangwei; Wang, Xinyun

    2018-02-01

    The effect of alloying elements (e.g. Fe, Al, and Ni) on the room temperature creep behavior of a lightweight Ti41Zr25Be34 bulk metallic glass (BMG) was investigated via nanoindentation tests. The generalized Kelvin model was adopted to describe the creep curves. The strain rate sensitivity m has been derived as a measure of the creep resistance. The compliance spectrum and retardation spectrum were also derived. The results show that the creep resistance of Ti41Zr25Be34 alloy can be obviously improved with the addition of alloying elements, and the most effective element is found to be Al. The mechanism for enhancing the creep resistance was discussed in terms of the scale variation of the shear transformation zone induced by alloying.

  11. Effect of microstructure and strain on the degradation behavior of novel bioresorbable iron-manganese alloy implants.

    Science.gov (United States)

    Heiden, Michael; Kustas, Andrew; Chaput, Kevin; Nauman, Eric; Johnson, David; Stanciu, Lia

    2015-02-01

    Advancing the understanding of microstructural effects and deformation on the degradability of Fe-Mn bioresorbable alloys (specifically, Fe-33%Mn) will help address the current problems associated with designing degradable fracture fixation implants for hard tissues. Potentiostatic polarization tests were conducted on a wide variety of metal samples to examine how different deformation processes affect the instantaneous rate of degradation of Fe-Mn alloys. Large-strain machining (LSM), a novel severe plastic deformation (SPD) technique was utilized during these experiments to modify the degradation properties of the proposed Fe-Mn alloy. It was discovered that Fe-33%Mn after LSM with a rake angle of 0° (effective strain = 2.85) showed the most promising increase in degradation rate compared to as-cast, annealed, and additional deformation conditions (rolled and other LSM parameters) for the same alloy. The mechanisms for enhancement of the corrosion rate are discussed. © 2014 Wiley Periodicals, Inc.

  12. Effect of 50-keV proton irradiation on the magnetism of a Fe66Ni34 Invar alloy

    Science.gov (United States)

    Matsushita, M.; Matsushima, Y.; Uruga, T.; Ishigami, R.; Iwase, A.

    2013-05-01

    The magnetism of Fe-Ni Invar alloys is very sensitive to the lattice constant, stress, and the number of nearest-neighbor Fe-Fe atomic pairs. Ion irradiation is a useful tool to alter the local atomic structure of a given material. Therefore, the effects of low-energy and light-ion irradiation on the magnetism of a Fe66Ni34 Invar alloy were investigated in this study. The Fe66Ni34 Invar alloy was irradiated with 50-keV protons at a fluence of 1×1015 ions/cm2 at room temperature. The Curie temperature was found to increase from 465 K (before irradiation) to 535 K (after irradiation). The X-ray absorption analysis of the fine structure of the alloy revealed that irradiation had no effect on the atomic structures surrounding Fe and Ni.

  13. Quantitative consideration for the tempering effect during multi-pass thermal cycle in HAZ of low-alloy steel

    International Nuclear Information System (INIS)

    Yu, Lina; Nakabayashi, Yuma; Saida, Kazuyoshi; Mochizuki, Masahito; Nishimoto, Kazutoshi; Kameyama, Masashi; Hirano, Shinro; Chigusa, Naoki

    2011-01-01

    A new Thermal Cycle Tempering Parameter (TCTP) to deal with the tempering effect during multi-pass thermal cycles has been proposed by extending Larson-Miller parameter (LMP). Experimental result revealed that the hardness in synthetic HAZ of the low alloy steel subjected to multi tempering thermal cycles has a good linear relationship with TCTP. By using this relationship, the hardness of the low-alloy steel reheated with tempering thermal cycles can be predicted when the original hardness is known. (author)

  14. Effect of Cold Rolling Reduction Rate on Corrosion Behaviour of Twin-roll Cast 8006 Aluminium Alloys

    OpenAIRE

    KÜÇÜK, İsrafil

    2018-01-01

    Utilization of aluminum alloys in automotive industry takes a crucial role in recent years due to their excellent properties such as corrosion resistance and light weight. 3003 and 8006 aluminum alloys have been particularly used as a heat exchanger compartment due to their corrosion resistance feature which has a perfect match for a heat exchanger fin stocks and a destructive salty environment in this car’s part. In the present work, an effect of cold rolling reduction (CRR) rate on the corr...

  15. Effect of plasma electrolytic oxidation on joining of AA 5052 aluminium alloy to polypropylene using friction stir spot welding

    OpenAIRE

    Aliasghari, S.; Ghorbani, M.; Skeldon, P.; Karami, H.; Movahedi, M.

    2017-01-01

    The effect of a plasma electrolytic oxidation (PEO) pre-treatment on joining of AA 5052 aluminium alloy and polypropylene by friction stir spot welding (FSSW) is investigated using lap tensile shear tests. Two surface conditions of the AA 5052 alloy are compared, one with a PEO pre-treatment in a silicate-based electrolyte, another without any pre-treatment. The resultant specimens are examined by high resolution scanning electron microscopy, thermogravimetric analysis and attenuated total re...

  16. Effects of metal primers on the bonding of an adhesive resin cement to noble metal ceramic alloys after thermal cycling.

    Science.gov (United States)

    Minami, Hiroyuki; Murahara, Sadaaki; Suzuki, Shiro; Tanaka, Takuo

    2011-12-01

    Although the effectiveness of primers for resin bonding to noble alloys has been demonstrated, no effective clinical technique for bonding to noble metal ceramic alloys has been established. The purpose of this study was to evaluate the effects of metal primers on the shear bond strength of an adhesive resin to noble metal ceramic alloys after thermal cycling. Sixty-three disk-shaped specimens (10 × 2.5 mm) were cast from high-gold-content alloys (Super Metal W-85: W85 or IFK88 GR: IFK88), a high-palladium-content alloy (Super Metal N-40: N40), and an Ag-Pd-Cu-Au alloy (Castwell M.C.12: MC12). Smaller-sized disk-shaped specimens (8 × 2.5 mm) were fabricated with MC12. Bonding surfaces were finished with 600-grit SiC-paper and airborne-particle abraded with 50-μm alumina. Pairs of disks were primed (V-Primer: VP; ML Primer: ML; or Metaltite: MT) and bonded with an adhesive resin (Super-Bond C&B). The bond strengths were determined before and after 20,000 and 50,000 thermal cycles (n=7). Data were analyzed by using a 3-way ANOVA and the Bonferroni test (α=.05). Failure modes were determined by optical microscope and SEM observation. Bond strengths to high-gold-content alloys with VP and MT significantly decreased after the thermal cycling (Palloys were not degraded up to 50,000 thermal cycles when primed with ML. None of the primers evaluated was effective for high-palladium-content alloy. Copyright © 2011 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  17. Effect of additive metals, Sn, Ga, and In in Ag-Pd-Au-Cu alloys on initial bond strength of 4-META adhesive cement to these alloys.

    Science.gov (United States)

    Goto, Shin-ichi; Churnjitapirom, Pornkiat; Miyagawa, Yukio; Ogura, Hideo

    2008-09-01

    The purpose of this study was to investigate the effects of three additives, Sn, Ga, and In, as well as the main constituents, Pd and Cu, of Ag-Pd-Au-Cu alloys on the initial bond strength of 4-META adhesive cement to these alloys. The Ag-Pd-Au-Cu alloys consisted of 20%, 30% or 40% Pd, and 10%, 15% or 20% Cu, 20% Au, and Ag as balance. Besides, additive metals (Sn, Ga, and In) of 2% and 4% were added to these compositions. The addition of three additives, in general, increased the initial bond strength of the cement in comparison to the mother compositions (0% additives), although the degrees of effectiveness of the three additives were different and varied with their contents. Among these additives, a remarkable increase in bond strength was observed with the addition of In. The increase in Cu content, in many cases, resulted in an increase in bond strength at high Pd contents (30% and 40%), but a decrease at low Pd content (20%) in some cases. The positive effects of the three additives and Cu could be due to the formation of a suitable oxide layer for strong bonding with 4-META.

  18. [Studies on Au-Ag-Pd-Cu alloys. (Part 3) Effects of additional elements to Au-Ag-Pd-Cu alloys (author's transl)].

    Science.gov (United States)

    Okazaki, K

    1981-01-01

    In the previous papers, the author pointed out that alloys containing 30 wt% Au, 15-25 wt% Pd and Cu were more favourable for Au-Ag-Pd-Cu quarternary dental alloys. In this paper, the experiments were carried out to find the effects of additional elements and so, Pt, Ir, Os, W, Mo, Cr, Mn, Co, Zn, In, Sn and Si were added to 30 wt% Au-30 wt% Ag-20 wt% Pd-20 wt% Cu alloys ranging 0.1 wt% to 2.0 wt% respectively. Then, tensile strength, elongation, hardness, corrosion resistivity and porosity ratio were tested on these specimen. Results were as follows. 1) The addition of 0.2 wt% Ir, 0.2 wt% Os and 1.0 wt% Co were comparatively effective for the fineness of grain sizes, elongation and tensile strength. 2) The addition of 0.2 wt% W, 1.0 wt% Mo and 0.2 wt% Si showed respectively bad effect for porosities or mechanical properties. 3) The addition of 1.0 wt% Cr, 2.0 wt% Mn, 1.0 wt% Co, 2.0 wt% Zn and 2.0 wt% In were good for the decrease of porosities respectively and showed that the porosity ratio was lower than 0.2%. 4) The additions of 2.0 wt% Zn-1.0 wt% Pt-0.5 wt% Co to Au-Ag-Pd-Cu alloy was especially good and showed 80 kg/mm2 of tensile strength, 5.1% of elongation, 249 of Vicker's hardness number and 0.4% of porosity ratio.

  19. Effects of La and Ce Addition on the Modification of Al-Si Based Alloys

    Directory of Open Access Journals (Sweden)

    Emad M. Elgallad

    2016-01-01

    Full Text Available This study focuses on the effects of the addition of rare earth metals (mainly lanthanum and cerium on the eutectic Si characteristics in Al-Si based alloys. Based on the solidification curves and microstructural examination of the corresponding alloys, it was found that addition of La or Ce increases the alloy melting temperature and the Al-Si eutectic temperature, with an Al-Si recalescence of 2-3°C, and the appearance of post-α-Al peaks attributed to precipitation of rare earth intermetallics. Addition of La or Ce to Al-(7–13% Si causes only partial modification of the eutectic Si particles. Lanthanum has a high affinity to react with Sr, which weakens the modification efficiency of the latter. Cerium, however, has a high affinity for Ti, forming a large amount of sludge. Due to the large difference in the length of the eutectic Si particles in the same sample, the normal use of standard deviation in this case is meaningless.

  20. Effect of microstructure refinement on low cycle fatigue behavior of Alloy 718

    Directory of Open Access Journals (Sweden)

    Mukhtarov Shamil

    2014-01-01

    Full Text Available Microstructure refinement down to d ∼ 0.1–1 μm is known to enhance processing properties of hard-to-deform materials and particularly can be used for facilitating superplastic forming or roll-forming. However refined microstructure can compromise service properties, particularly fatigue properties. In the present work, the fatigue behavior of the fine-grained Alloy 718 has been investigated. A number of fine-grained conditions with a grain size ∼0.1–1 μm were produced using multiple forging with a graduate decrease of the forging temperature. Part of the forged fine-grained conditions was also subjected to conventional solution annealing and ageing. In this case a small grain size was controlled by precipitates of the δ phase located on grain boundaries. Low cycle fatigue tests of the fine-grained conditions were carried out at room and elevated temperatures. The obtained properties are compared with those of the Alloy 718 in the coarse-grained conditions. The effect of the grain size on the fatigue strength of the fine-grained Alloy 718 is discussed in terms of the microstructure evolution and fracture mode.

  1. Effects of ultrasonic vibration on the microstructure and mechanical properties of high alloying TiAl.

    Science.gov (United States)

    Ruirun, Chen; Deshuang, Zheng; Tengfei, Ma; Hongsheng, Ding; Yanqing, Su; Jingjie, Guo; Hengzhi, Fu

    2017-01-24

    To modify the microstructure and enhance performances, the ultrasonic vibration is applied in the mould casting of TiAl alloy. The effects and mechanism of ultrasonic vibration on the solidifying microstructure and mechanical properties are investigated and the model for predicting lamellar colony size is established. After ultrasonic vibration, the coarse microstructure is well modified and lamellar colony is refined from 534 μm to 56 μm. Most of precipitated phases are dissolved into the lamellar colony leading to a homogenous element distribution. The phase ratio of α 2 -Ti 3 Al and γ-TiAl is increased, and the chemical composition is promoted to more close to equilibrium level by weakening the influence of β-alloying elements. The microhardness and yield strength are gradually improved by 23.72% and 181.88% due to the fine grain strengthening, while the compressive strength is enhanced by 24.47% through solution strengthening. The critical ultrasonic intensity (I b ) for TiAl alloy is estimated at 220 W cm -2 and the model for average lamellar colony size is established as . The ultrasonic refinement efficiency exponentially increases as the ultrasonic vibration time with a theoretic limit maximum value of E lim  = 88% and the dominating refinement mechanism by ultrasonic vibration is the cavitation-enhanced nucleation rather than cavitation-induced dendrite fragmentation.

  2. Hot deformation characteristics of AZ80 magnesium alloy: Work hardening effect and processing parameter sensitivities

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Y.; Wan, L.; Guo, Z. H.; Sun, C. Y.; Yang, D. J.; Zhang, Q. D.; Li, Y. L.

    2017-02-01

    Isothermal compression experiment of AZ80 magnesium alloy was conducted by Gleeble thermo-mechanical simulator in order to quantitatively investigate the work hardening (WH), strain rate sensitivity (SRS) and temperature sensitivity (TS) during hot processing of magnesium alloys. The WH, SRS and TS were described by Zener-Hollomon parameter (Z) coupling of deformation parameters. The relationships between WH rate and true strain as well as true stress were derived from Kocks-Mecking dislocation model and validated by our measurement data. The slope defined through the linear relationship of WH rate and true stress was only related to the annihilation coefficient Ω. Obvious WH behavior could be exhibited at a higher Z condition. Furthermore, we have identified the correlation between the microstructural evolution including β-Mg17Al12 precipitation and the SRS and TS variations. Intensive dynamic recrystallization and homogeneous distribution of β-Mg17Al12 precipitates resulted in greater SRS coefficient at higher temperature. The deformation heat effect and β-Mg17Al12 precipitate content can be regarded as the major factors determining the TS behavior. At low Z condition, the SRS becomes stronger, in contrast to the variation of TS. The optimum hot processing window was validated based on the established SRS and TS values distribution maps for AZ80 magnesium alloy.

  3. Effect of fluorides and chlorides upon corrosion behavior of alloy C-22

    International Nuclear Information System (INIS)

    Carranza, Ricardo M.

    2003-01-01

    Alloy C-22 is one of the candidates to fabricate the external wall of the high level nuclear waste containers. These packages are designed to maintain isolation of the waste for a minimum of 10,000 years. During this period they must resist atmospheric corrosion. Electrochemical techniques such as cyclic potentiodynamic polarization, electrochemical impedance spectroscopy and variation of corrosion potential in time and non-electrochemical techniques such as X-ray fluorescence (XRF) and microscopy were applied to determine the effect of fluorides and chlorides upon general and localized corrosion of different microstructures of alloy C-22. The corrosion rates obtained were about 0.1 μm/year. Crevice corrosion was detected only in those solutions where chlorides ions were present. Fluoride ions affected the passivity and trans passivity behavior of the alloy. They produced higher current densities than chlorides in both ranges. There were no differences in corrosion behavior of the different microstructures. Mixtures of chlorides and fluorides seem to be more detrimental than the separated ions regarding to localized corrosion and trans passivity. (author)

  4. Effect of Heat Treatment on Corrosion Behaviors of Mg-5Y-1.5Nd Alloys

    Directory of Open Access Journals (Sweden)

    Xiumin Ma

    2016-01-01

    Full Text Available Corrosion behavior of Mg-5Y-1.5Nd alloy was investigated after heat treatment. The microstructure and precipitation were studied by scanning electron microscope (SEM and energy dispersive spectrometer (EDS. The weight loss rates of different samples were arranged as T6-24 h>T6-6 h>T6-14 h>as-cast>T4. The open circuit potential (OCP showed that T4 sample had a more positive potential than that of other samples. The potentiodynamic polarization curves showed that the T6-24 h sample had the highest corrosion current density of 245.362 μA·cm−2, whereas the T4 sample had the lowest at 52.164 μA·cm−2. The EIS results confirmed that the heat treatment reduced the corrosion resistance for Mg-5Y-1.5Nd alloy, because the precipitations acted as the cathode of electrochemical reactions to accelerate the corrosion process. The corrosion rates of different samples were mainly determined by the amount and distribution of the precipitations. The precipitations played dual roles that depended on the amount and distribution. The presence of the phase in the alloys could deteriorate the corrosion performance as it could act as an effective galvanic cathode. Otherwise, a fine and homogeneous phase appeared to be a better anticorrosion barrier.

  5. Grain size effect on yield strength of titanium alloy implanted with aluminum ions

    Energy Technology Data Exchange (ETDEWEB)

    Popova, Natalya, E-mail: natalya-popova-44@mail.ru [Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); Institute of Strength Physics and Materials Science, SB RAS, 2/4, Akademicheskii Ave., 634021, Tomsk (Russian Federation); Nikonenko, Elena, E-mail: vilatomsk@mail.ru [Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); National Research Tomsk Polytechnic University, 30, Lenin Str., 634050, Tomsk (Russian Federation); Yurev, Ivan, E-mail: yiywork@mail.ru [Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); Kalashnikov, Mark, E-mail: kmp1980@mail.ru [Institute of Strength Physics and Materials Science, SB RAS, 2/4, Akademicheskii Ave., 634021, Tomsk (Russian Federation); Kurzina, Irina, E-mail: kurzina99@mail.ru [National Research Tomsk State University, 36, Lenin Str., 634050, Tomsk (Russian Federation)

    2016-01-15

    The paper presents a transmission electron microscopy (TEM) study of the microstructure and phase state of commercially pure titanium VT1-0 implanted by aluminum ions. This study has been carried out before and after the ion implantation for different grain size, i.e. 0.3 µm (ultra-fine grain condition), 1.5 µm (fine grain condition), and 17 µm (polycrystalline condition). This paper presents details of calculations and analysis of strength components of the yield stress. It is shown that the ion implantation results in a considerable hardening of the entire thickness of the implanted layer in the both grain types. The grain size has, however, a different effect on the yield stress. So, both before and after the ion implantation, the increase of the grain size leads to the decrease of the alloy hardening. Thus, hardening in ultra-fine and fine grain alloys increased by four times, while in polycrystalline alloy it increased by over six times.

  6. Effect of solute segregation on thermal creep in dilute nanocyrstalline Cu alloys

    International Nuclear Information System (INIS)

    Schäfer, Jonathan; Ashkenazy, Yinon; Albe, Karsten; Averback, Robert S

    2012-01-01

    Highlights: ► Segregating solutes lower the grain boundary free volume in nanocrystalline Cu. ► Lower free volume leads to reduced atomic mobility and higher creep resistance. ► Increase in creep resistance scales with atomic size of segregating solutes. ► Atomic processes in boundaries are similar to the ones in amorphous material. - Abstract: The effect of solute segregation on thermal creep in dilute nanocrystalline alloys (Cu–Nb, Cu–Fe, Cu–Zr) was studied at elevated temperatures using molecular dynamics simulations. A combined Monte-Carlo and molecular dynamics simulation technique was first used to equilibrate the distribution of segregating solutes. Then the creep rates of the diluted Cu samples were measured as functions of temperature, composition, load and accumulated strain. In Cu–Nb samples, the creep rates were observed to increase initially with strain, but then saturate at a value close to that obtained for alloys prepared by randomly locating the solute in the grain boundaries. This behavior is attributed to an increase in grain boundary volume and energy with added chemical disorder. At high temperatures, the apparent activation energy for creep was anomalously high, 3 eV, but only 0.3 eV at lower temperatures. This temperature dependence is found to correlate with atomic mobilities in bulk Cu–Nb glasses. Calculations of creep in nanocrystalline Cu alloys containing other solutes, Fe and Zr, show that the suppression of creep rate scales with their atomic volumes when dissolved in Cu.

  7. The effect of aging on the critical current density in superconducting Nb-Ti-Zr alloys

    International Nuclear Information System (INIS)

    Ishida, Fumihiko; Doi, Toshio

    1979-01-01

    The effect of aging temperature, cold-reduction prior to aging, O 2 content and composition on the variation in the critical current density, J sub(c), by isothermal aging was investigated in heavily cold-worked Nb-Ti-Zr alloys on the Nb-Ti side. The results are summarized as follows: (1) When these alloys are aged isothermally at temperatures from 350 to 500 0 C, J sub(c) increases initially, reaches a maximum value and then decreases. Increase in J sub(c) of three orders of magnitude is possible as a result of aging. (2) The maximum value of J sub(c) on the isothermal aging curve becomes higher at a lower aging temperature, at a less cold-reduction prior to aging or with a higher O 2 content. (3) The J sub(c) of aged alloy becomes a maximum in composition containing 35 at%Nb, 60 to 65 at%Ti and less than 5 at%Zr. (4) The maximum value of J sub(c) was obtained for Nb-60.0 at%Ti-5.0 at%Zr alloy containing 1200 wt ppm O 2 , aged at 350 0 C for 330 h after 98.44% cold-reduction. The values of J sub(c) at 4.2 K were 2.4 x 10 9 A/m 2 at 5.0 T, 1.1 x 10 9 A/m 2 at 7.0 T and 3.0 x 10 8 A/m 2 at 9.0 T, respectively. The upper critical field of this specimen was 11.3 T at 4.2 K and its critical temperature was 8.6 K. (author)

  8. Effect of tellurium on machinability and mechanical property of CuAlMnZn shape memory alloy

    International Nuclear Information System (INIS)

    Liu Na; Li Zhou; Xu Genying; Feng Ze; Gong Shu; Zhu Lilong; Liang Shuquan

    2011-01-01

    Highlights: → A novel free-machining Cu-7.5Al-9.7Mn-3.4Zn-0.3Te (wt.%) shape memory alloy has been developed. → The size of dispersed particles with richer Te is 2-5 μm. → The CuAlMnZnTe alloy has good machinability which approached that of BZn15-24-1.5 due to the addition of Te. → Its shape memory property keeps the same as that of CuAlMnZn alloy with free Te. → The CuAlMnZn shape memory alloy with and without Te both have good ductile as annealed at 700 deg. C for 15 min. - Abstract: The microstructure transition, shape memory effect, machinability and mechanical property of the CuAlMnZn alloy with and without Te have been studied using X-ray diffraction analysis, chips observation and scanning electron microscopy (SEM), tensile strength test and differential scanning calorimeter (DSC), and semi-quantitative shape memory effect (SME) test. The particles with richer Te dispersedly distributed in grain interior and boundary with size of 2-5 μm. After the addition of Te, the CuAlMnZnTe alloy machinability has been effectively increased to approach that of BZn15-24-1.5 and its shape memory property remains the same as the one of CuAlMnZn alloy. The CuAlMnZn shape memory alloys with and without Te both have good ductility as annealed at 700 deg. C for 15 min.

  9. Effects of Plate Thickness and Projection Shape on the Microstructure and Strength of High-Speed Solid-State Joined 2024 Alloy Studs and 5052 Alloy Plates

    Science.gov (United States)

    Kumai, Shinji; Hayashida, Keisuke; Takaya, Kento

    An advanced stud joining method was developed that produces a strong joint without mechanical property degradation of the base materials. Specially designed 2024-T3 aluminum alloy studs with a circular ridge projection were pressed against 5052-H34 aluminum alloy plates of 1 to 4 mm in thickness. A high-density discharge current was run through the stud, and flowed through the projection and plate surface for several milliseconds, prompting local heating, plastic deformation, and atomic diffusion at the contact point. The projection crushed and spread along the plate surface. Asymmetrical deformation occurred on both the inner side and the outer side of the projection. For thin plates, joining mainly occurred at the outer side. For thick plates, in contrast, the deformation was largely symmetrical. Effects of discharge voltage and the projection shape were also investigated in an attempt to optimize joining strength.

  10. The effects of zirconium and beryllium on microstructure evolution, mechanical properties and corrosion behaviour of as-cast AZ63 alloy

    International Nuclear Information System (INIS)

    Jafari, Hassan; Amiryavari, Peyman

    2016-01-01

    Alloying elements are able to strongly modify the microstructure characteristics of Mg–Al–Zn alloys which dominate mechanical and corrosion properties of the alloys. In this research, the individual effects of Zr and Be additions on the microstructure, mechanical and corrosion properties of as-cast AZ63 alloy were explored. The results revealed that the addition of Zr leads to microstructure refinement in as-cast AZ63 alloy, resulting in improved tensile and hardness properties. 0.0001 and 0.001 wt% Be containing cast AZ63 alloy exhibited microstructure coarsening, while morphological alteration from sixford symmetrical to irregular shape grain was observed for the alloy containing 0.01 and 0.1 wt% Be. No specific Be compound was detected. In addition, mechanical properties of AZ63 alloy containing Zr was improved due to the microstructure modification, while Be containing alloy responded reverse behaviour. The corrosion resistance of AZ63 alloy was improved after the addition of Zr and Be due to the grain refinement and passivation effects, respectively. However, when the Zr content exceeds 0.5 wt%, the formation of Al 2 Zr affected the corrosion resistance. In other words, AZ63–0.5Zr alloy provided the lowest corrosion rate.

  11. Degradation analysis of neutrons absorber bars Ag-In-Cd. Part 1: alloy depletion, neutrons absorption effectiveness and mechanical properties

    International Nuclear Information System (INIS)

    Castanheira, Myrthes; Terremoto, Luis Antonio A.; Silva, Jose Eduardo Rosa da; Zeituni, Carlos Alberto

    2002-01-01

    The original alloy of IEA-R1 reactor absorber bars (supposing similar to alloy 2533 with composition 81,5% Ag - 136% In -4,9% Cd) was designed to work for a life time equivalent to a neutron exposition of ∼10 21 n/cm 2 (thermal) so that the alloy can preserve the characteristic one phase. Analyzing the behavior of absorber bars Ag-In-Cd under irradiation, this work reports a semi quantitative assessment of the IEA-R1 absorber bars degradation current condition by viewpoint of alloy depletion, neutrons absorption effectiveness and mechanical properties, as a complement of visual inspections results carried out at 1998, 2000 and 2001 whose had pointed to visible degree of degradation accumulated along 29 years of operation in the reactor. (author)

  12. Effects of primary dicarboxylic acids on microstructure and mechanical properties of sub-microcrystalline Ni-Co alloys

    International Nuclear Information System (INIS)

    Vijayakumar, J.; Mohan, S.; Yadav, S. Sunil

    2011-01-01

    Highlights: → The electrodeposited Ni-Co alloys are mostly used in magnetic sensors and it has good mechanical and corrosion resistance properties. → The effect of dicarboxylic acid leads to preferred (2 0 0) crystalline orientation, this may improve magnetic properties dicarboxylic acid can alter the elemental composition of Ni-Co alloy. → Dicarboxylic acid acts as a good brightner. - Abstract: Nickel-cobalt alloys were deposited from sulfate electrolyte with oxalic, malonic and succinic acids as additives and their microstructure and mechanical properties were studied. The crystal structure, surface morphologies, and chemical composition of coatings were investigated using X-ray diffraction, scanning electron microscope, and energy dispersive spectroscopy. The crystal structure and surface morphology analysis showed that the addition of dicarboxylic acid leads to (2 0 0) crystal face and the surface were more compact and uniform due to the grain refining. Ni 60 -Co 40 alloy was achieved when succinic acid is used as additive.

  13. Effect of microalloying with boron on the microstructure and mechanical properties of Mg–Zn–Y–Mn alloy

    International Nuclear Information System (INIS)

    Yang, Kai; Zhang, Jinshan; Zong, Ximei; Wang, Wenxian; Xu, Chunxiang; Cheng, Weili; Nie, Kaibo

    2016-01-01

    The addition of boron to long-periodic stacking ordered (LPSO) phase-strengthened Mg–Zn–Y system alloys has been studied for the first time. The as-cast Mg 94 Zn 2.5 Y 2.5 Mn 1 alloy containing 0.003 wt% B with abundant LPSO phase and refined grains exhibited optimal mechanical performance with ultimate tensile strength and elongation of 252.5 MPa and 11.0%, respectively. - Highlights: • The effect of a trace amount of boron (B) on the formation of long-periodic stacking ordered (LPSO) phase was investigated. • Adding small amounts of B to the Mg–Zn–Y–Mn alloy can highly increase the volume fraction of LPSO phase. • The as-cast Mg–Zn–Y–Mn–B alloy has high strength (UTS=252.5 MPa) and good ductility (elongation=11.0%) in low Y/Zn ratio.

  14. Effect of addition of V and C on strain recovery characteristics in Fe-Mn-Si alloy

    International Nuclear Information System (INIS)

    Lin Chengxin; Wang Guixin; Wu Yandong; Liu Qingsuo; Zhang Jianjun

    2006-01-01

    Shape recoverable strain, recovery stress and low-temperature stress relaxation characteristics in an Fe-17Mn-5Si-10Cr-4Ni (0.08C) alloy and an Fe-17Mn-2Cr-5Si-2Ni-1V (0.23C) alloy have been studied by means of X-ray diffraction, transmission electron microscopy and measurement of recoverable strain and recovery stress. The amount of stress-induced ε martensite under tensile deformation at room temperature, recoverable strain and recovery stress are increased obviously with addition V and C in Fe-Mn-Si alloy, which is owing to the influence of addition V and C on strengthening austenitic matrix. Addition of V and C in Fe-Mn-Si alloy is evidently effective to reduce the degree of low-temperature stress relaxation, for the dispersed VC particles 50-180 nm in size precipitated during annealing restrain the stress induced martensitic transformation

  15. Effect of Isothermal Ageing on Structural and Magnetic Properties of Ni47Mn40Sn13 Ferromagnetic Shape Memory Alloy

    Directory of Open Access Journals (Sweden)

    A. Ghotbi varzaneh

    2015-12-01

    Full Text Available In this investigation, Ni47Mn40Sn13 ferromagnetic shape memory alloy was prepared by mechanical alloying. The metal powders were ball milled in argon atmosphere for 20 hours. X-ray diffraction pattern confirmed formation of crystalline structure of Heusler alloy. As-milled powder samples were sealed in quartz tubes under high vacuum and subjected to heat treatments at 950°C for different time durations. Then, the effect of isothermal ageing on structural, magnetic and electrical properties of samples was investigated. Results of electrical resistance displayed a metal-like behavior around martensitic transformation. The results showed that 16 hours of annealing was the optimal time for producing this alloy which could be an appropriate candidate for magnetic refrigerant.

  16. Effect of helium on swelling and microstructural evolution in ion-irradiated V-15Cr-5Ti alloy

    International Nuclear Information System (INIS)

    Loomis, B.A.; Kestel, B.J.; Gerber, S.B.; Ayrault, G.

    1986-03-01

    An investigation was made on the effects of implanted helium on the swelling and microstructural evolution that results from energetic single- and dual-ion irradiation of the V-15Cr-5Ti alloy. Single-ion irradiations were utilized for a simulated production of the irradiation damage that might be expected from neutron irradiation of the alloy in a reactor with a fast neutron energy spectrum (E > 0.1 MeV). Dual-ion irradiations were utilized for a simulated production of the simultaneous creation of helium atoms and irradiation damage in the alloy in the MFR environment. Experimental results are also presented on the radiation-induced segregation of the constituent atoms in the single- and dual-ion irradiated alloy

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

    Science.gov (United States)

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

    1977-01-01

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

  18. Effects of LWR environments on fatigue life of carbon and low-alloy steels

    International Nuclear Information System (INIS)

    Chopra, O.K.; Shack, W.J.

    1995-03-01

    SME Boiler and Pressure Vessel Code provides construction of nuclear power plant components. Figure I-90 Appendix I to Section III of the Code specifies fatigue design curves for structural materials. While effects of environments are not explicitly addressed by the design curves, test data suggest that the Code fatigue curves may not always be adequate in coolant environments. This paper reports the results of recent fatigue tests that examine the effects of steel type, strain rate, dissolved oxygen level, strain range, loading waveform, and surface morphology on the fatigue life of A 106-Gr B carbon steel and A533-Gr B low-alloy steel in water

  19. Use of Δ E effect in amorphous alloys for magnetic-field measurement

    Science.gov (United States)

    Churenkov, A. V.; Listvin, V. N.; Kozel, S. M.

    1993-11-01

    Use of the ΔE effect in magnetically soft amorphous alloys (MSAA) for magnetic-field measurement is examined theoretically and experimentally. An MSAA microresonator in the form of bracket attached on one end is proposed as a sensing element. The microresonator is excited photothermally by intensity-modulated laser radiation, and the oscillations are registered by a fiber-optic interferometer. The use of fiber guides makes the sensor entirely passive, and frequency encoding minimizes the effect on the output signal of random attenuations in the fiber.

  20. Effects of ultraviolet irradiation on bonding strength between Co-Cr alloy and citric acid-crosslinked gelatin matrix.

    Science.gov (United States)

    Inoue, Motoki; Sasaki, Makoto; Katada, Yasuyuki; Taguchi, Tetsushi

    2014-02-01

    Novel techniques for creating a strong bond between polymeric matrices and biometals are required. We immobilized polymeric matrices on the surface of biometal for drug-eluting stents through covalent bond. We performed to improve the bonding strength between a cobalt-chromium alloy and a citric acid-crosslinked gelatin matrix by ultraviolet irradiation on the surface of cobalt-chromium alloy. The ultraviolet irradiation effectively generated hydroxyl groups on the surface of the alloy. The bonding strength between the gelatin matrix and the alloy before ultraviolet irradiation was 0.38 ± 0.02 MPa, whereas it increased to 0.48 ± 0.02 MPa after ultraviolet irradiation. Surface analysis showed that the citric acid derivatives occurred on the surface of the cobalt-chromium alloy through ester bond. Therefore, ester bond formation between the citric acid derivatives active esters and the hydroxyl groups on the cobalt-chromium alloy contributed to the enhanced bonding strength. Ultraviolet irradiation and subsequent immobilization of a gelatin matrix using citric acid derivatives is thus an effective way to functionalize biometal surfaces.

  1. Effect of thione primers on adhesive bonding between an indirect composite material and Ag-Pd-Cu-Au alloy.

    Science.gov (United States)

    Imai, Hideyuki; Koizumi, Hiroyasu; Shimoe, Saiji; Hirata, Isao; Matsumura, Hideo; Nikawa, Hiroki

    2014-01-01

    The current study evaluated the effect of primers on the shear bond strength of an indirect composite material joined to a silverpalladium-copper-gold (Ag-Pd-Cu-Au) alloy (Castwell). Disk specimens were cast from the alloy and were air-abraded with alumina. Eight metal primers were applied to the alloy surface. A light-polymerized indirect composite material (Solidex) was bonded to the alloy. Shear bond strength was determined both before and after the application of thermocycling. Two groups primed with Metaltite (thione) and M. L. Primer (sulfide) showed the greatest post-thermocycling bond strength (8.8 and 6.5 MPa). The results of the X-ray photoelectron spectroscopic (XPS) analysis suggested that the thione monomer (MTU-6) in the Metaltite primer was strongly adsorbed onto the Ag-Pd-Cu-Au alloy surface even after repeated cleaning with acetone. The application of either the thione (MTU-6) or sulfide primer is effective for enhancing the bonding between a composite material and Ag-Pd-Cu-Au alloy.

  2. Effect of impurities on mechanical properties of vanadium alloys under liquid-lithium environment during neutron irradiation at HFIR

    Science.gov (United States)

    Fukumoto, K.; Kuroyanagi, Y.; Kuroiwa, H.; Narui, M.; Matsui, H.

    2011-10-01

    Vanadium alloys, including the highly purified V-4Cr-4Ti alloy, were irradiated in liquid lithium up to a damage level of 3.7 dpa in the HFIR at 425 °C and 598 °C. Neutron irradiation caused an increase of the ductile-brittle transition temperature (DBTT) and irradiation hardening was observed. Adding titanium to the V-Cr alloys was effective for increasing irradiation hardening at 425 °C. For highly purified (Zr-treated) V-4Cr-4Ti alloys the irradiation hardening was significantly reduced at both 425 °C and 598 °C. However, microstructural observations after the irradiation experiments showed that there was no significant difference in microstructure between the original and the highly purified specimens. It is suggested that the reduction of irradiation hardening in the highly purified V-4Cr-4Ti alloys was caused by the configuration and distribution of interstitial impurities in the neutron-irradiated specimen matrix. Controlling the impurities in V-4Cr-4Ti alloys has a very important effect for improving their mechanical properties that take place under neutron irradiation at around 400 °C.

  3. Effect of titanium addition on shape memory effect and recovery stress of training-free cast Fe–Mn–Si–Cr–Ni shape memory alloys

    International Nuclear Information System (INIS)

    Wang, Gaixia; Peng, Huabei; Sun, Panpan; Wang, Shanling; Wen, Yuhua

    2016-01-01

    The shape memory effect and recovery stress of cast Fe–17.2Mn–5.28Si–9.8Cr–4.57Ni (18Mn) and Fe–17.5Mn–5.29Si–9.68Cr–4.2Ni–0.09Ti (18Mn–Ti) alloys have been investigated by optical microscopy, scanning electron microscopy (SEM), electron backscattering diffraction (EBSD), and resistivity–temperature curves. The cast 18Mn and 18Mn–Ti alloys solidified as the ferritic mode for which liquid phase fully transforms into primary δ ferrite. The role of titanium is to indirectly refine the austenite through refining the primary δ ferrite. In this case, the austenitic grains of the cast 18Mn alloy were much bigger than that of the cast 18Mn–Ti alloy, although the two alloys underwent δ→γ phase transformation. Grain refinement suppresses the stress-induced ε martensitic transformation, and thus the shape memory effect of the cast 18Mn–Ti alloy is worse than that of the cast 18Mn alloy. On the contrary, the maximum recovery stress and the recovery stress at room temperature are higher for the cast 18Mn–Ti alloy annealed at 1073 K for 30 min than for the cast 18Mn alloy annealed at 973 K for 30 min, because grain refinement suppresses the relaxation of recovery stress caused by the plastic deformation and the stress-induced ε martensitic transformation during cooling process. It is difficult to obtain the training-free cast Fe–Mn–Si based shape memory alloys with excellent shape memory effect and high recovery stress only by grain refinement.

  4. Uniform and pitting corrosion events induced by SCN- anions on Al alloys surfaces and the effect of UV light

    International Nuclear Information System (INIS)

    Amin, Mohammed A.

    2011-01-01

    The influence of the alloying elements on the uniform and pitting corrosion processes of Al-6061, Al-4.5%Cu, Al-7.5%Cu, Al-6%Si and Al-12%Si alloys was studied in 0.50 M KSCN solution at 25 o C. Open-circuit potential, Tafel polarization, linear polarization resistance (LPR) and ICP-AES measurements were used to study the uniform corrosion process on the surfaces of the tested alloys. Cyclic polarization, potentiostatic current-time transients and impedance techniques were employed for pitting corrosion studies. Obtained results were compared with pure Al. Passivation kinetics of the tested Al samples were also studied as a function of applied potential, [SCN - ] and sample composition by means of potentiostatic current transients. The induction time, after which the growth of stable pits occurs, decreased with increasing applied potential and [SCN - ]. Regarding to uniform corrosion, alloyed Cu was found to enhance the corrosion rate, while alloyed Si suppressed it. Alloying elements of the tested samples diminished pitting attack to an extent depending on the percentage of the alloying element in the sample. Among the investigated materials, Al-Si alloys exhibited the highest corrosion resistance towards uniform and pitting corrosion processes in KSCN solutions. The passive and dissolution behaviour of Al was also studied under the conditions of continuous illumination (300-450 nm) based on cyclic polarization and potentiostatic techniques. The incident photons had a little influence on pit initiation and a marked effect on pit growth. These explained in terms of a photo-induced modification of the passive film formed on the anode surface, which render it more resistant to pitting. The effects of UV photons energy and period of illumination on the morphology of the pitted surfaces were also studied.

  5. Proximity effect tunneling into virtual bound state alloys

    International Nuclear Information System (INIS)

    Tang, I.M.; Roongkkeadsakoon, S.

    1984-01-01

    The effects of a narrow virtual bound state formed by transition metal impurities dissolved in the normal layer of a superconducting proximity effect sandwich are studied. Using standard renormalization techniques, we obtain the changes in the transition temperatures and the jumps in the specific heat at T/sub c/ as a function of the thickness of the normal layer, of the widths of the virtual bound states, and of the impurity concentrations. It is seen that narrow virtual bound states lead to decrease in the transition temperatures, while broad virtual bound states do not. It if further seen that the narrow virtual bound state causes the reduced specific heat jump at T/sub c/ to deviate from the BCS behavior expected of the pure sandwich

  6. Charge transfer, lattice distortion, and quantum confinement effects in Pd, Cu, and Pd-Cu nanoparticles; size and alloying induced modifications in binding energy

    International Nuclear Information System (INIS)

    Sengar, Saurabh K.; Mehta, B. R.; Gupta, Govind

    2011-01-01

    In this letter, effect of size and alloying on the core and valence band shifts of Pd, Cu, and Pd-Cu alloy nanoparticles has been studied. It has been shown that the sign and magnitude of the binding energy shifts is determined by the contributions of different effects; with quantum confinement and lattice distortion effects overlapping for size induced shifts in case of core levels and lattice distortion and charge transfer effects overlapping for alloying induced shifts at smaller sizes. These results are important for understanding gas molecule-solid surface interaction in metal and alloy nanoparticles in terms of valance band positions.

  7. Effect of ultrasonic casting on microstructure and its genetic effects on corrosion performance of 7085 aluminum alloy

    Science.gov (United States)

    Liu, Yu; Huang, Yuanchun; Xiao, Zhengbing

    2017-11-01

    The effect of ultrasonic casting on microstructure and its genetic effects on strength, exfoliating corrosion, stress corrosion and electrochemical behavior of 7085 aluminum alloy have been investigated by optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM), together with tensile testing, exfoliation corrosion testing, electrical conductivity testing and polarization curve. The results indicate that ultrasonic casting could refine the grain, alleviate segregation and inhibit the formation of coarse nonequilibrium phase in as-cast state; in addition, the dissolution of nonequilibrium phase in the ultrasonic ingot during homogenization turns out to be more thorough. What is more, the plate processed from ultrasonic ingot holds a lower ratio of recrystallization after solid solution, and the corrosion performance of the alloy was improved under T6 temper, without sacrifice of strength, owing to the dispersive distribution of strengthening phase in the matrix and the coarse, sparse GBPs.

  8. Helium effects on irradiation dmage in V alloys

    Energy Technology Data Exchange (ETDEWEB)

    Doraiswamy, N.; Alexander, D. [Argonne National Lab., IL (United States)

    1996-10-01

    Preliminary investigations were performed on V-4Cr-4Ti samples to observe the effects of He on the irradiation induced microstructural changes by subjecting 3 mm electropolished V-4Cr-4Ti TEM disks, with and without prior He implantation, to 200 keV He irradiation at room temperature and monitoring, in-situ, the microstructural evolution as a function of total dose with an intermediate voltage electron microscope directly connected to an ion implanter. A high density of black dot defects were formed at very low doses in both He pre-implanted and unimplanted samples.

  9. The effect of alloying on shake-up satellites: The case of Pd in SbPd{sub 2} and InPd{sub 2} surface alloys

    Energy Technology Data Exchange (ETDEWEB)

    Pancotti, A. [Instituto de Fisica ' Gleb Wataghin-Universidade Estadual de Campinas, Caixa Postal 6165, 13083-970 Campinas, SP (Brazil)], E-mail: pancotti@ifi.unicamp.br; Siervo, A. de [Laboratorio Nacional de Luz Sincrotron, Caixa Postal 6192, 13084-971 Campinas, SP (Brazil); Carazzolle, M.F. [Instituto de Fisica ' Gleb Wataghin-Universidade Estadual de Campinas, Caixa Postal 6165, 13083-970 Campinas, SP (Brazil); Landers, R. [Instituto de Fisica ' Gleb Wataghin-Universidade Estadual de Campinas, Caixa Postal 6165, 13083-970 Campinas, SP (Brazil); Laboratorio Nacional de Luz Sincrotron, Caixa Postal 6192, 13084-971 Campinas, SP (Brazil); Kleiman, G.G. [Instituto de Fisica ' Gleb Wataghin-Universidade Estadual de Campinas, Caixa Postal 6165, 13083-970 Campinas, SP (Brazil)

    2007-05-15

    A well-known final state effect in photoemission is that of the 'shake-up' satellite in core level and valence band spectra from Pd in the bulk metals. The satellite is explained in terms of the existence of two Pd final state configurations, 4d{sup 9}5s{sup 1} and 4d{sup 10}5s{sup 2}. The present paper is a preliminary report of studies of the suppression of the shake-up satellite in surface alloys of Pd with the 'sp metals', In and Sb, on Pd(1 1 1), whose surface structure was determined as being ({radical}3 x {radical}3)R30 deg. from LEED and X-ray photoelectron diffraction (XPD). Although satellite suppression has been reported for bulk alloys, no such report has been made for a metallic surface alloy system. From the satellite suppression and the related spectra asymmetry reduction, as well as the small binding energy shifts, we are able to interpret the results in terms of valence band splitting.

  10. Irradiation effects in alloys Hg1-x CdxTe

    International Nuclear Information System (INIS)

    Favre, J.; Konczykowski, M.; Ecole Polytechnique, 91 - Palaiseau; Blanchard, C.

    1989-01-01

    The Hall coefficient R H and resistivity ρ were measured in situ during low temperature irradiations by electrons and ions. It has been shown that excess free electrons were provided by created mercury defects. The position of the associated level is determined for various mercury contents. In CdTe, it lies in the gap; otherwise, it is degenerated with the conduction band. The analysis of the rate of the defect creation versus energy of impinging electrons and mercury content indicates that the energy threshold and charge are independent of the composition. The effects of C, O, Xe ions irradiations are similar to those of electrons. The stability of created defects strongly depends on mercury content [fr

  11. Effects of Nd-addition on the structural, hydrogen storage, and electrochemical properties of C14 metal hydride alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wong, D.F. [BASF/Battery Materials-Ovonic, 2983 Waterview Drive, Rochester Hills, MI 48309 (United States); Department of Chemical Engineering, Wayne State University, Detroit, MI 48202 (United States); Young, K., E-mail: kwo.young@basf.com [BASF/Battery Materials-Ovonic, 2983 Waterview Drive, Rochester Hills, MI 48309 (United States); Department of Chemical Engineering, Wayne State University, Detroit, MI 48202 (United States); Nei, J.; Wang, L. [BASF/Battery Materials-Ovonic, 2983 Waterview Drive, Rochester Hills, MI 48309 (United States); Ng, K.Y.S. [Department of Chemical Engineering, Wayne State University, Detroit, MI 48202 (United States)

    2015-10-25

    Nd-addition to the AB{sub 2}-based alloy Ti{sub 12}Zr{sub 22.8−x}V{sub 10}Cr{sub 7.5}Mn{sub 8.1}Co{sub 7.0}Ni{sub 32.2}Al{sub 0.4}Nd{sub x} is studied for its effects on the structure, gaseous-phase hydrogen storage, and electrochemical properties. This study follows a series of Cu, Mo, Fe, Y, Si, and La doping studies in similar AB{sub 2}-based alloys. Limited solubility of Nd in the main Laves phase promotes the formation of secondary phases (AB and Zr{sub 7}Ni{sub 10}) to provide catalytic effects and synergies for improved capacity and high-rate dischargeability (HRD) performance. The main C14 storage phase has smaller lattice constants and cell volumes, and these effects reduce the storage capacity at higher Nd levels. Different hydrogen absorption mechanisms can occur in these multi-component, multi-phase alloys depending on the interfaces of the phases, and they have effects on the alloy properties. Higher Nd-levels improve the HRD performance despite having lower bulk diffusion and surface exchange current. Magnetic susceptibility measurements indicate large percentage of larger metallic nickel clusters are present in the surface oxide of alloys with higher Nd-content, and AC impedance studies show very low charge-transfer resistance with high catalytic capability in the alloys. The −40 °C charge-transfer resistance of 8.9 Ω g in this Nd-series of alloys is the lowest measured out of the studies investigating doped AB{sub 2}-based MH alloys for improved low-temperature characteristics. The improvement in HRD and low-temperature performance appears to be related to the proportion of the highly catalytic NdNi-phase at the surface, which must offset the increased bulk diffusion resistance in the alloy. - Graphical abstract: Schematics of hydrogen flow and corresponding PCT isotherms in funneling mode. - Highlights: • Structural and hydrogen storage properties of Nd-substituted AB{sub 2} metal hydride are reported. • Nd contributes to the lowest

  12. Effects of Sn addition on the microstructure, mechanical properties and corrosion behavior of Ti–Nb–Sn alloys

    International Nuclear Information System (INIS)

    Moraes, Paulo E.L.; Contieri, Rodrigo J.; Lopes, Eder S.N.; Robin, Alain; Caram, Rubens

    2014-01-01

    Ti and Ti alloys are widely used in restorative surgery because of their good biocompatibility, enhanced mechanical behavior and high corrosion resistance in physiological media. The corrosion resistance of Ti-based materials is due to the spontaneous formation of the TiO 2 oxide film on their surface, which exhibits elevated stability in biological fluids. Ti–Nb alloys, depending on the composition and the processing routes to which the alloys are subjected, have high mechanical strength combined with low elastic modulus. The addition of Sn to Ti–Nb alloys allows the phase transformations to be controlled, particularly the precipitation of ω phase. The aim of this study is to discuss the microstructure, mechanical properties and corrosion behavior of cast Ti–Nb alloys to which Sn has been added. Samples were centrifugally cast in a copper mold, and the microstructure was characterized using optical microscopy, scanning electron microscopy and X-ray diffractometry. Mechanical behavior evaluation was performed using Berkovich nanoindentation, Vickers hardness and compression tests. The corrosion behavior was evaluated in Ringer's solution at room temperature using electrochemical techniques. The results obtained suggested that the physical, mechanical and chemical behaviors of the Ti–Nb–Sn alloys are directly dependent on the Sn content. - Graphical abstract: Effects of Sn addition to the Ti–30Nb alloy on the elastic modulus. - Highlights: • Sn addition causes reduction of the ω phase precipitation. • Minimum Vickers hardness and elastic modulus occurred for 6 wt.% Sn content. • Addition of 6 wt.% Sn resulted in maximum ductility and minimum compression strength. • All Ti–30Nb–XSn (X = 0, 2, 4, 6, 8 and 10%) alloys are passive in Ringer's solution. • Highest corrosion resistance was observed for 6 wt.% Sn content

  13. [The effect of epigallocatechin gallate (EGCG) on the surface properties of nickel-chromium dental casting alloys after electrochemical corrosion].

    Science.gov (United States)

    Qiao, Guang-yan; Zhang, Li-xia; Wang, Jue; Shen, Qing-ping; Su, Jian-sheng

    2014-08-01

    To investigate the effect of epigallocatechin gallate (EGCG) on the surface properties of nickel-chromium dental alloys after electrochemical corrosion. The surface morphology and surface structure of nickel-chromium dental alloys were examined by stereomicroscope and scanning electron microscopy before and after electrochemical tests in 0 g/L and 1.0 g/L EGCG artificial saliva. The surface element component and chemical states of nickel-chromium dental alloys were analyzed by X-ray photoelectron spectrograph after electrochemical tests in 0 g/L and 1.0 g/L EGCG artificial saliva. More serious corrosion happened on the surface of nickel-chromium alloy in 1.0 g/L EGCG artificial saliva than in 0 g/L EGCG. The diameters of corrosion pits were smaller, and the dendrite structure of the alloy surface was not affected in 0 g/L EGCG. While the diameters of corrosion pits were larger, the dendritic interval of the alloy surface began to merge, and the dendrite structure was fuzzy in 1.0 g/L EGCG. In addition, the O, Ni, Cr, Be, C and Mo elements were detected on the surface of nickel-chromium alloys after sputtered for 120 s in 0 g/L EGCG and 1.0 g/L EGCG artificial saliva after electrochemical corrosion, and the surface oxides were mainly NiO and Cr(2)O(3). Compared with 0 g/L EGCG artificial saliva, the content of O, NiO and Cr(2)O(3) were lower in 1.0 g/L EGCG. The results of surface morphology and the corrosion products both show that the corrosion resistance of nickel-chromium alloys become worse and the oxide content of corrosion products on the surface reduce in 1.0 g/L EGCG artificial saliva.

  14. Effects of Sn addition on the microstructure, mechanical properties and corrosion behavior of Ti–Nb–Sn alloys

    Energy Technology Data Exchange (ETDEWEB)

    Moraes, Paulo E.L., E-mail: pauloeduardo.leitedemoraes@gmail.com [University of Campinas, School of Mechanical Engineering, Rua Mendeleiev, 200, Campinas, SP 13083-860 (Brazil); Contieri, Rodrigo J., E-mail: contieri@fem.unicamp.br [University of Campinas, School of Mechanical Engineering, Rua Mendeleiev, 200, Campinas, SP 13083-860 (Brazil); Lopes, Eder S.N., E-mail: ederlopes@fem.unicamp.br [University of Campinas, School of Mechanical Engineering, Rua Mendeleiev, 200, Campinas, SP 13083-860 (Brazil); Robin, Alain, E-mail: alain@demar.eel.usp.br [University of São Paulo, School of Engineering of Lorena, Polo Urbo-Industrial Gleba AI-6, Lorena, SP 12600-00 (Brazil); Caram, Rubens, E-mail: caram@fem.unicamp.br [University of Campinas, School of Mechanical Engineering, Rua Mendeleiev, 200, Campinas, SP 13083-860 (Brazil)

    2014-10-15

    Ti and Ti alloys are widely used in restorative surgery because of their good biocompatibility, enhanced mechanical behavior and high corrosion resistance in physiological media. The corrosion resistance of Ti-based materials is due to the spontaneous formation of the TiO{sub 2} oxide film on their surface, which exhibits elevated stability in biological fluids. Ti–Nb alloys, depending on the composition and the processing routes to which the alloys are subjected, have high mechanical strength combined with low elastic modulus. The addition of Sn to Ti–Nb alloys allows the phase transformations to be controlled, particularly the precipitation of ω phase. The aim of this study is to discuss the microstructure, mechanical properties and corrosion behavior of cast Ti–Nb alloys to which Sn has been added. Samples were centrifugally cast in a copper mold, and the microstructure was characterized using optical microscopy, scanning electron microscopy and X-ray diffractometry. Mechanical behavior evaluation was performed using Berkovich nanoindentation, Vickers hardness and compression tests. The corrosion behavior was evaluated in Ringer's solution at room temperature using electrochemical techniques. The results obtained suggested that the physical, mechanical and chemical behaviors of the Ti–Nb–Sn alloys are directly dependent on the Sn content. - Graphical abstract: Effects of Sn addition to the Ti–30Nb alloy on the elastic modulus. - Highlights: • Sn addition causes reduction of the ω phase precipitation. • Minimum Vickers hardness and elastic modulus occurred for 6 wt.% Sn content. • Addition of 6 wt.% Sn resulted in maximum ductility and minimum compression strength. • All Ti–30Nb–XSn (X = 0, 2, 4, 6, 8 and 10%) alloys are passive in Ringer's solution. • Highest corrosion resistance was observed for 6 wt.% Sn content.

  15. Effects of Ce concentrations on ignition temperature and surface tension of Mg-9wt.%Al alloy

    Directory of Open Access Journals (Sweden)

    Deng Zhenghua

    2013-03-01

    Full Text Available Magnesium alloys are well known for their excellent properties, but the potential issues with oxidation and burning during melting and casting largely limit its industrial applications. The addition of Ce in magnesium alloys can significantly raise ignition-proof performance and change the structure of the oxide film on the surface of the molten metal as well as the surface tension values. Surface tension is an important physical parameter of the metal melts, and it plays an important role in the formation of surface oxide film. In this present work, the ignition temperature and the surface tension of Mg-9wt.%Al alloy with different Ce concentrations were studied. Surface tensions was measured using the maximum bubble pressure method (MBPM. Ignition temperature was measured using NiCr-NiSi type thermocouples and was monitored and recorded via a WXT-604 desk recording device. The results show that the ignition point of Mg-9wt.%Al alloy can be effectively elevated by adding Ce. The ignition temperature reaches its highest point of 720 ℃ when the addition of Ce is 1wt.%. The surface tension of the molten Mg-9wt.%Al alloy decreases exponentially with the increase of Ce addition at the same temperature. Similarly, the experiment also shows that the surface tension of Mg-9wt.%Al alloy decreases exponentially with the increase of temperature.

  16. Effect of Copper and Silicon on Al-5%Zn Alloy as a Candidate Low Voltage Sacrificial Anode

    Science.gov (United States)

    Pratesa, Yudha; Ferdian, Deni; Togina, Inez

    2017-05-01

    One common method used for corrosion protection is a sacrificial anode. Sacrificial anodes that usually employed in the marine environment are an aluminum alloy sacrificial anode, especially Al-Zn-In. However, the electronegativity of these alloys can cause corrosion overprotection and stress cracking (SCC) on a high-strength steel. Therefore, there is a development of the sacrificial anode aluminum low voltage to reduce the risk of overprotection. The addition of alloying elements such as Cu, Si, and Ge will minimize the possibility of overprotection. This study was conducted to analyze the effect of silicon and copper addition in Al-5Zn. The experiment started from casting the sacrificial anode aluminum uses electrical resistance furnace in a graphite crucible in 800°C. The results alloy was analyzed using Optical emission spectroscopy (OES), Differential scanning calorimetry, electrochemical impedance spectroscopy, and metallography. Aluminum alloy with the addition of a copper alloy is the most suitable and efficient to serve as a low-voltage sacrificial anode aluminum. Charge transfer resistivity of copper is smaller than silicon which indicates that the charge transfer between the metal and the electrolyte is easier t to occur. Also, the current potential values in coupling with steel are also in the criteria range of low-voltage aluminum sacrificial anodes.

  17. The Effects of Adding Elements of Zinc and Magnesium on Ag-Cu Eutectic Alloy for Warming Acupuncture

    Directory of Open Access Journals (Sweden)

    Yu Kyoung Kim

    2013-01-01

    Full Text Available The warming acupuncture for hyperthermia therapy is made of STS304. However, its needle point cannot be reached to a desirable temperature due to heat loss caused by low thermal conductivity, and the quantification of stimulation condition and the effective standard establishment of warming acupuncture are required as a heat source. Accordingly, in this study, after Ag-Cu alloys with different composition ratios were casted and then mixed with additives to improve their physical and mechanical properties, the thermal conductivity and biocompatibility of the alloy specimens were evaluated for selecting suitable material. Ag-Cu binary alloys and ternary alloys added 5 wt% Zn or 2 wt% Mg were casted and then cold drawn to manufacture needles for acupuncture, and their physical properties, thermal conductivity, and biocompatibility were evaluated for their potential use in warming acupuncture. The results of this study showed that the physical and mechanical properties of the Ag-Cu alloys were improved by additives and that the thermal conductivity, machinability, and biocompatibility of the Ag-Cu alloys were improved by Mg addition.

  18. The effects of adding elements of zinc and magnesium on ag-cu eutectic alloy for warming acupuncture.

    Science.gov (United States)

    Kim, Yu Kyoung; Park, Il Song; Kim, Keun Sik; Lee, Min Ho

    2013-01-01

    The warming acupuncture for hyperthermia therapy is made of STS304. However, its needle point cannot be reached to a desirable temperature due to heat loss caused by low thermal conductivity, and the quantification of stimulation condition and the effective standard establishment of warming acupuncture are required as a heat source. Accordingly, in this study, after Ag-Cu alloys with different composition ratios were casted and then mixed with additives to improve their physical and mechanical properties, the thermal conductivity and biocompatibility of the alloy specimens were evaluated for selecting suitable material. Ag-Cu binary alloys and ternary alloys added 5 wt% Zn or 2 wt% Mg were casted and then cold drawn to manufacture needles for acupuncture, and their physical properties, thermal conductivity, and biocompatibility were evaluated for their potential use in warming acupuncture. The results of this study showed that the physical and mechanical properties of the Ag-Cu alloys were improved by additives and that the thermal conductivity, machinability, and biocompatibility of the Ag-Cu alloys were improved by Mg addition.

  19. Effects of ageing treatment on microstructures and properties of Mg-Gd-Y-Zr alloys with and without Zn additions

    International Nuclear Information System (INIS)

    Liu, X.B.; Chen, R.S.; Han, E.H.

    2008-01-01

    Mg-10Gd-3Y-0.5Zr alloys with and without 1% Zn additions have been investigated using optical microscopy, scanning electron microscope and X-ray diffraction. The microstructures, ageing hardening behaviors and mechanical properties of the two alloys are compared. The extruded-T5 specimens exhibit remarkable age hardening responses during ageing from 200 to 250 deg. C. The highest peak hardness and strength of the two alloys are obtained when they are aged at 200 deg. C. Addition of 1% Zn to Mg-10Gd-3Y-0.5Zr alloy results in the greater magnitude ageing effect and better mechanical properties as well as better heat resistance. Furthermore, secondary ageing is carried out at 200 deg. C following preliminary ageing at 250 deg. C for both Mg-10Gd-3Y-0.5Zr and Mg-10Gd-3Y-1Zn-0.5Zr alloys. The ultimate tensile strength values after secondary ageing are slightly lower compared with the highest strength of the two alloys, but secondary ageing offers a better combination of high strength and ductility

  20. Effect of Cooling Rate on Morphology of TiAl3 Particles in Al–4Ti Master Alloy

    Directory of Open Access Journals (Sweden)

    Jianhua Zhao

    2017-02-01

    Full Text Available The Al–4Ti master alloy was fabricated by aluminum (Al and sponge titanium particle in a resistance furnace at different cooling rates. This work aims to investigate the relationship between the cooling rate and morphology of TiAl3. The microstructure and composition of master alloys at different cooling rates were characterized and analyzed by optical microscopy (OM, X-ray diffraction (XRD, differential scanning calorimetry (DSC, and SEM with energy dispersive spectroscopy (EDS. The results showed that various morphologies of TiAl3 particles in the Al–4Ti master alloy could be acquired at different cooling rates. Petal-like, blocky, and flake-like TiAl3 particles in the Al–4Ti master alloy were respectively acquired at the cooling rates of 3.36 K/s, 2.57 K/s, and 0.31 K/s. It was also found that the morphology of TiAl3 particles in the prepared master alloy changed from petal-like to blocky, then finally to flake-like, with the decrease of cooling rate. In addition, the morphology of the TiAl3 particles has no effect on the phase inversion temperature of Al–4Ti master alloy.

  1. Enhanced caloric effect induced by magnetoelastic coupling in NiMnGaCu Heusler alloys: Experimental study and theoretical analysis

    Science.gov (United States)

    Zhao, Dewei; Castán, Teresa; Planes, Antoni; Li, Zongbin; Sun, Wen; Liu, Jian

    2017-12-01

    On the basis of a phenomenological Landau model combined with comprehensive experimental studies, the magnetostructural transition behavior and field induced caloric effects for NiMnGaCu Heusler alloys have been investigated. In Ni50Mn25 -xGa25Cux alloys with x =5.5 , 6, and 6.5, both magnetocaloric entropy change (Δ S ) and elastocaloric temperature change (Δ T ) increase with the increment of Cu content. The maximum Δ S of 1.01 J /mol K and Δ T of 8.1 K are obtained for the alloy with x =6.5 . In order to explore the physical origin behind the large caloric effect, here we quantitatively propose a crucial coefficient of magnetoelastic coupling κ ˜ by utilizing a thermodynamic formalism within the framework of the Landau approach. It has been verified that the enhancement of the strength of magnetoelastic coupling between lattice and magnetic freedoms results in the increased caloric response for NiMnGaCu alloys. Thus, the strengthened coupling of the magnetoelastic effect can be considered as an effective way to improve the caloric performance for these alloys having the same sign of magnetic and elastic entropy changes contributed to the total caloric effect.

  2. The Effect of Precursor Ligands and Oxidation State in the Synthesis of Bimetallic Nano-Alloys

    KAUST Repository

    LaGrow, Alec P.

    2015-05-12

    The characteristics of bimetallic nanomaterials are dictated by their size, shape and elemental distribution. Solution synthesis is widely utilized to form nanomaterials, such as nanoparticles, with controlled size and shape. However, the effects of variables on the characteristics of bimetallic nanomaterials are not completely understood. In this study, we used a continuous-flow synthetic strategy to explore the effects of the ligands and the oxidation state of a metal precursor in a shape-controlled synthesis on the final shape of the nanomaterials and the elemental distribution within the alloy. We demonstrate that this strategy can tune the size of monodisperse PtM (M=Ni or Cu) alloy nanocrystals ranging from 3 to 16 nm with an octahedral shape using acetylacetonate or halide precursors of Pt(II), Pt(IV) and Ni or Cu (II). The nanoparticles formed from halide precursors showed an enrichment of platinum on their surfaces, and the bromides could oxidatively etch the nanoparticles during synthesis with the O2/Br- pair. The two nanocrystal precursors can be uti-lized independently and can control the size with a trend of Pt(acac)2effect of the ligand shell of a precursor during the synthesis of alloy nanoparticles as well as to control, in a scalable manner, the nanomaterial size and surface chemistry.

  3. TEM characterisation of stress corrosion cracks in nickel based alloys: effect of chromium content and chemistry of environment

    International Nuclear Information System (INIS)

    Delabrouille, F.

    2004-11-01

    Stress corrosion cracking (SCC) is a damaging mode of alloys used in pressurized water reactors, particularly of nickel based alloys constituting the vapour generator tubes. Cracks appear on both primary and secondary sides of the tubes, and more frequently in locations where the environment is not well defined. SCC sensitivity of nickel based alloys depends of their chromium content, which lead to the replacement of alloy 600 (15 % Cr) by alloy 690 (30 % Cr) but this phenomenon is not yet very well understood. The goal of this thesis is two fold: i) observe the effect of chromium content on corrosion and ii) characterize the effect of environment on the damaging process of GV tubes. For this purpose, one industrial tube and several synthetic alloys - with controlled chromium content - have been studied. Various characterisation techniques were used to study the corrosion products on the surface and within the SCC cracks: SIMS; TEM - FEG: thin foil preparation, HAADF, EELS, EDX. The effect of chromium content and surface preparation on the generalised corrosion was evidenced for synthetic alloys. Moreover, we observed the penetration of oxygen along triple junctions of grain boundaries few micrometers under the free surface. SCC tests show the positive effect of chromium for contents varying from 5 to 30 % wt. Plastic deformation induces a modification of the structure, and thus of the protective character, of the internal chromium rich oxide layer. SCC cracks which developed in different chemical environments were characterised by TEM. The oxides which are formed within the cracks are different from what is observed on the free surface, which reveals a modification of medium and electrochemical conditions in the crack. Finally we were able to evidence some structural characteristics of the corrosion products (in the cracks and on the surface) which turn to be a signature of the chemical environment. (author)

  4. Thermal and mechanical treatments for nickel and some nickel-base alloys: Effects on mechanical properties

    Science.gov (United States)

    Hall, A. M.; Beuhring, V. F.

    1972-01-01

    This report deals with heat treating and working nickel and nickel-base alloys, and with the effects of these operations on the mechanical properties of the materials. The subjects covered are annealing, solution treating, stress relieving, stress equalizing, age hardening, hot working, cold working, combinations of working and heat treating (often referred to as thermomechanical treating), and properties of the materials at various temperatures. The equipment and procedures used in working the materials are discussed, along with the common problems that may be encountered and the precautions and corrective measures that are available.

  5. Internal friction study of neutron-irradiation effects on an amorphous Cu40Ti60 alloy

    International Nuclear Information System (INIS)

    Dong, Y.; Wu, G.; Xiao, K.; Li, X.; He, Y.

    1988-01-01

    Effects of neutron irradiation on the structure of an amorphous Cu 40 Ti 60 alloy have been studied by internal friction measurements. After irradiation, the position of the first internal friction peak remains almost unchanged and the shoulder position shifts towards a higher temperature by about 5 K, which indicates that the Cu 40 Ti 60 glass becomes more stable. These results are finally discussed based on the concept of changes of chemical short-range ordering and geometrical short-range ordering due to radiation damage

  6. Effect of impurity and alloying microadditions on the Cr-Mo-V steel structure and properties

    International Nuclear Information System (INIS)

    Lanskaya, K.A.; Kulikova, L.V.; Yarovoj, V.V.

    1985-01-01

    The effect of impurity elements (nitrogen and aluminium) and alloying microadditions titanium and zirconium on the 12Kh1MF-steel-Cr-Mo-V structure, phase composition and properties is investigated. It is shown that the nitrogen and aluminium introduction leads to time decrease up to 12Kh1MF steel fracture. Introduction of zirconium into Cr-Mo-V steel (up to 5%) exerts positive influence on its properties owing to a structural factor. With titarium content of about 0.10% heat resisting steel properties increase, with subsequent increase of its content - they decrease. The cause of such decrease is titanium capacity to extend the ferrite region

  7. The chiral anomalous Hall effect in PdFe and AuFe alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wolff-Fabris, F. [NHMFL, Los Alamos National Laboratory, MS E536, Los Alamos, NM 87544 (United States)], E-mail: frederikwf@lanl.gov; Pureur, P.; Schaf, J. [Instituto de Fisica, UFRGS, Caixa Postal 15051, Porto Alegre 91501970 (Brazil); Vieira, V. [Instituto de Fisica e Matematica-UFPel, Caixa Postal 354, Pelotas 96010900 (Brazil); Campbell, I.A. [Laboratoire des Colloides, Verres et Nanomateriaux, Universite Montpellier II, Montpellier 34095 (France)

    2008-04-01

    We have made systematic measurements of the anomalous Hall effect in a PdFe and AuFe alloys. The Hall coefficient R{sub h} has been measured as a function of applied magnetic field and temperature. The experimental results demonstrate that it is necessary to consider a negative contribution in addition to the canonical Karplus-Luttinger term. This difference term can be identified to the theoretically predicted chiral or real space Berry phase term and can be understood in terms of the Aharonov-Bohm-like intrinsic microscopic current loops arising from successive scatterings by canted local spins.

  8. Effect of Grain Misorientation Angle on Twinning Propagation in Ti-15Mo Alloy

    Science.gov (United States)

    Im, Y.-D.; Lee, Y.-K.; Song, K. H.

    2018-03-01

    This study was carried out to evaluate the effect of grain misorientation angle distribution on the deformation behavior and twinning of Ti-15Mo alloy. Cold rolling exhibited a significant texture with grains oriented along the {111}//normal direction, which correlate with a higher fraction of low-angle boundaries. This material showed a lower yield strength and higher elongation than those of the hot rolled material. The twinning propagation mainly occurred between neighboring grains with a low-angle relation. Consequently, the texture development was correlated with low-angle boundaries and affected by the increase in the twinning density, which increased the strain hardening rate.

  9. Effect of Second Phase Particles on the Tensile Instability of a Nanostructured Al-1%Si Alloy

    DEFF Research Database (Denmark)

    Huang, Tian Lin; Wu, Gui Lin; Liu, Qing

    2014-01-01

    A nanostructured Al-1%Si alloy containing dispersed Si particles was produced by heavily cold-rolling to study the effect of second phase particles on the tensile instability of nanostructured metals. Tensile tests were conducted on the as-deformed sample and the samples after recovery annealing...... treatments. The structural features of deformed and annealed samples were characterized by transmission electron microscopy. By comparing with the behavior of nanostructured commercial purity Al without dispersed particles, a remarked improvement in the tensile stability was found. This is related...... to a prevention of localized deformation by the presence of finely dispersed Si particles in the nanoscale matrix structure....

  10. Effects of heat treatment on properties of multi-element low alloy wear-resistant steel

    Directory of Open Access Journals (Sweden)

    SONG Xu-ding

    2007-02-01

    Full Text Available The paper has studied the mechanical properties and heat treatment effects on multi-element low alloy wear-resistant steel (MLAWS used as a material for the liner of rolling mill torii. The results show that when quenched at 900-920℃ and tempered at 350-370℃, the MLAWS has achieved hardness above 60 HRC, tensile strength greater than 1 600 MPa, impact toughness higher than 18J/cm2 and fracture toughness greater than 37 MPa

  11. Analysis of the effect on growth kinetics of gamma prima phase in Inconel 713C alloys

    International Nuclear Information System (INIS)

    Thorp, S.I.; Versaci, R.A.; Ges, A.; Palacio, H.A.

    1993-01-01

    This work shows the analysis of the effect on growth kinetics of gamma prima phase in Inconel 713C alloy of two thermic treatments. In this study, SEM are used and the results are analyzed by means of the theory developed by Lifshitz, Slyozov and Wagner (LSW theory). The findings have revealed that with such theory it is not possible to determine if the process of growth is controlled either through diffusion or through diffusion in the interface as to the time employed in the experiment (2600 hours); the time required is approximately 10000 hours. (Author)

  12. Application of the Positron Annihilation Spectroscopy for Chromium Effect Investigation in Binary Fe-Cr Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Sojak, S.; Krsjak, V.; Slugen, V.; Stancek, S.; Petriska, M.; Vitazek, K.; Stacho, M. [Department of Nuclear Physics and Technology, Faculty of Electrical Engineering and Information Technology, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia)

    2008-07-01

    Positron annihilation spectroscopy (PAS) is one of the non-destructive techniques applied with advantage for evaluation of the radiation treated materials microstructure. In this work, the PAS was used for study of different Fe-Cr alloys implanted by ions of helium. Investigation was focused on the chromium effect and the radiation defects resistance. In particular, the vacancy type defects (mono-vacancies, vacancy clusters) have been studied. The results show that the specific content of chromium has important influence on the size and distribution of induced defects. (authors)

  13. Effectiveness of Hypochlorous Acid to Reduce the Biofilms on Titanium Alloy Surfaces in Vitro

    Directory of Open Access Journals (Sweden)

    Chun-Ju Chen

    2016-07-01

    Full Text Available Chemotherapeutic agents have been used as an adjunct to mechanical debridement for peri-implantitis treatment. The present in vitro study evaluated and compared the effectiveness of hypochlorous acid (HOCl, sodium hypochlorite (NaOCl, and chlorhexidine (CHX at eliminating Gram-negative (E. coli and P. gingivalis and Gram-positive (E. faecalis and S. sanguinis bacteria. The effect of irrigating volume and exposure time on the antimicrobial efficacy of HOCl was evaluated, and a durability analysis was completed. Live/dead staining, morphology observation, alamarBlue assay, and lipopolysaccharide (LPS detection were examined on grit-blasted and biofilm-contaminated titanium alloy discs after treatment with the three chemotherapeutic agents. The results indicated that HOCl exhibited better antibacterial efficacy with increasing irrigating volumes. HOCl achieved greater antibacterial efficacy as treatment time was increased. A decrease in antimicrobial effectiveness was observed when HOCl was unsealed and left in contact with the air. All the irrigants showed antibacterial activity and killed the majority of bacteria on the titanium alloy surfaces of biofilm-contaminated implants. Moreover, HOCl significantly lowered the LPS concentration of P. gingivalis when compared with NaOCl and CHX. Thus, a HOCl antiseptic may be effective for cleaning biofilm-contaminated implant surfaces.

  14. Effect of temperature on the anodizing process of aluminum alloy AA 5052

    Science.gov (United States)

    Theohari, S.; Kontogeorgou, Ch.

    2013-11-01

    The effect of temperature (10-40 °C) during the anodizing process of AA 5052 for 40 min in 175 g/L sulfuric acid solution at constant voltage (15 V) was studied in comparison with pure aluminum. The incorporated magnesium species in the barrier layer result in the further increase of the minimum current density passed during anodizing, as the temperature increases, by about 42% up to 30 °C and then by 12% up to 40 °C. Then during the anodizing process for 40 min a blocking effect on oxide film growth was gradually observed as the temperature increased until 30 °C. The results of EDAX analysis on thick films reveal that the mean amount of the magnesium species inside the film is about 50-70% less than that in the bulk alloy, while it is higher at certain locations adjacent to the film surface at 30 °C. The increase of anodizing temperature does not influence the porosity of thin films (formed for short times) on pure aluminum, while it reduces it on the alloy. At 40 °C the above mentioned blocking effects disappear. It means that the presence of magnesium species causes an impediment to the effect of temperature on iss, on the film thickness and on the porosity of thin films, only under conditions where film growth takes place without significant loss of the anodizing charge to side reactions.

  15. Effect of cerium addition on microstructures of carbon-alloyed iron ...

    Indian Academy of Sciences (India)

    All the alloys exhibited a typical two-phase microstructure consisting of Fe3AlC carbides in an iron aluminide matrix. In the alloy without Ce addition, large bulky carbides were equally distributed throughout the matrix with many smaller precipitates interspersed in between. In the alloy with Ce addition, the carbide grain sizes ...

  16. The effect of A5TB refiner on the fatigue strength of 6063AL alloy ...

    African Journals Online (AJOL)

    The study focuses on the influence of aluminium titanium boron (A5TB) master alloy on the fatigue behaviour of 6063Al alloy. Cylindrical cast rods of 6063Al alloy containing different proportions of A5TB ranging from 0 - 0.11 wt.% were produced and were machined to conform to a standard fatigue specimen. The test ...

  17. Effect of Electrical Discharge Machining on Stress Concentration in Titanium Alloy Holes

    Directory of Open Access Journals (Sweden)

    Wei-Hsuan Hsu

    2016-11-01

    Full Text Available Titanium alloys have several advantages, such as a high strength-to-weight ratio. However, the machinability of titanium alloys is not as good as its mechanical properties. Many machining processes have been used to fabricate titanium alloys. Among these machining processes, electrical discharge machining (EDM has the advantage of processing efficiency. EDM is based on thermoelectric energy between a workpiece and an electrode. A pulse discharge occurs in a small gap between the workpiece and electrode. Then, the material from the workpiece is removed through melting and vaporization. However, defects such as cracks and notches are often detected at the boundary of holes fabricated using EDM and the irregular profile of EDM holes reduces product quality. In this study, an innovative method was proposed to estimate the effect of EDM parameters on the surface quality of the holes. The method combining the finite element method and image processing can rapidly evaluate the stress concentration factor of a workpiece. The stress concentration factor was assumed as an index of EDM process performance for estimating the surface quality of EDM holes. In EDM manufacturing processes, Ti-6Al-4V was used as an experimental material and, as process parameters, pulse current and pulse on-time were taken into account. The results showed that finite element simulations can effectively analyze stress concentration in EDM holes. Using high energy during EDM leads to poor hole quality, and the stress concentration factor of a workpiece is correlated to hole quality. The maximum stress concentration factor for an EDM hole was more than four times that for the same diameter of the undamaged hole.

  18. Effect of Electrical Discharge Machining on Stress Concentration in Titanium Alloy Holes.

    Science.gov (United States)

    Hsu, Wei-Hsuan; Chien, Wan-Ting

    2016-11-24

    Titanium alloys have several advantages, such as a high strength-to-weight ratio. However, the machinability of titanium alloys is not as good as its mechanical properties. Many machining processes have been used to fabricate titanium alloys. Among these machining processes, electrical discharge machining (EDM) has the advantage of processing efficiency. EDM is based on thermoelectric energy between a workpiece and an electrode. A pulse discharge occurs in a small gap between the workpiece and electrode. Then, the material from the workpiece is removed through melting and vaporization. However, defects such as cracks and notches are often detected at the boundary of holes fabricated using EDM and the irregular profile of EDM holes reduces product quality. In this study, an innovative method was proposed to estimate the effect of EDM parameters on the surface quality of the holes. The method combining the finite element method and image processing can rapidly evaluate the stress concentration factor of a workpiece. The stress concentration factor was assumed as an index of EDM process performance for estimating the surface quality of EDM holes. In EDM manufacturing processes, Ti-6Al-4V was used as an experimental material and, as process parameters, pulse current and pulse on-time were taken into account. The results showed that finite element simulations can effectively analyze stress concentration in EDM holes. Using high energy during EDM leads to poor hole quality, and the stress concentration factor of a workpiece is correlated to hole quality. The maximum stress concentration factor for an EDM hole was more than four times that for the same diameter of the undamaged hole.

  19. A study of hydrogen environment effects on microstructure property behavior of NASA-23 alloy and related alloy systems

    International Nuclear Information System (INIS)

    Diwan, R.M.

    1990-01-01

    The influence of hydrogen on the tensile properties and ductility behavior of NASA-23 alloy were analyzed. NASA-23 and other referenced alloys in cast and hipped conditions were solution treated and aged under selected conditions and characterized using optical metallography, scanning electron microscopy, and electron microprobe analysis techniques. The yield strength of NASA-23 is not affected much by hydrogen under tensile tests carried at 5000 psig conditions; however, the ultimate strength and ductility properties are degraded. This implies that the physical mechanisms operating would be related to the plastic deformation process. The fracture surfaces characteristics of NASA-23 specimens tensile tested in hydrogen, helium, and air were also analyzed. These revealed surface cracks around specimen periphery with the fracture surface showing a combination of intergranular and transgranular modes of fracture. It is seen that the specimens charged in hydrogen seem to favor a more brittle fracture mode in comparison to air and helium charged specimens. The AMCC casting characterization program is to be analyzed for their hydrogen behavior. As a result of this program, the basic microstructural factors and fracture characteristics in some cases were analyzed

  20. A study of hydrogen environment effects on microstructure property behavior of NASA-23 alloy and related alloy systems

    Science.gov (United States)

    Diwan, Ravinder M.

    1990-01-01

    This work is part of the overall advanced main combustion chamber (AMCC) casting characterization program of the Materials and Processes Laboratory of the Marshall Space Flight Center. The influence of hydrogen on the tensile properties and ductility behavior of NASA-23 alloy were analyzed. NASA-23 and other referenced alloys in cast and hipped conditions were solution treated and aged under selected conditions and characterized using optical metallography, scanning electron microscopy, and electron microprobe analysis techniques. The yield strength of NASA-23 is not affected much by hydrogen under tensile tests carried at 5000 psig conditions; however, the ultimate strength and ductility properties are degraded. This implies that the physical mechanisms operating would be related to the plastic deformation process. The fracture surfaces characteristics of NASA-23 specimens tensile tested in hydrogen, helium, and air were also analyzed. These revealed surface cracks around specimen periphery with the fracture surface showing a combination of intergranular and transgranular modes of fracture. It is seen that the specimens charged in hydrogen seem to favor a more brittle fracture mode in comparison to air and helium charged specimens. The AMCC casting characterization program is to be analyzed for their hydrogen behavior. As a result of this program, the basic microstructural factors and fracture characteristics in some cases were analyzed.

  1. Effects of Alloying Elements (Cr, Mn) on Corrosion Properties of Carbon Steel in Synthetic Seawater

    International Nuclear Information System (INIS)

    Hyun, Youngmin; Kim, Heesan

    2016-01-01

    Effects of alloying elements, manganese and chromium, on corrosion resistance of carbon steel were examined using weight loss test and electrochemical tests (polarization test and electrochemical impedance spectroscopy (EIS)) in synthetic seawater at 60 ℃. The results from the weight loss test showed that chromium effectively improved corrosion resistance of carbon steel during the entire immersion time, but manganese improved corrosion resistance after the lowered corrosion resistance at the beginnings of immersion. Unlike the weight loss test, the electrochemical tests showed that the corrosion resistance did not increase with immersion time, in all the specimens. This disagreement is explained by the presence of rust involved in electrochemical reaction during electrochemical tests. The analysis of rust with transmission electron microscopy (TEM)−energy dispersive spectroscopy (EDS) showed that the amorphous-like rust layer located at the metal/rust interface with enriched alloying element (Cr, Mn) prevents diffusion of corrosive species into a metal/rust interface effectively, which leads to increased corrosion resistance. The initial corrosion behaviour is also affected by the rust types. In other words, manganese accelerated the formation of spinel oxides, negatively affecting corrosion resistance. Meanwhile, chromium accelerated the formation of goethite but impeded the formation of spinel oxides, positively affecting the corrosion resistance. From the above results, the corrosion resistance of steel is closely related with a rust type.

  2. The treatment effect of porous titanium alloy rod on the early stage talar osteonecrosis of sheep.

    Directory of Open Access Journals (Sweden)

    Xiao-Kang Li

    Full Text Available Osteonecrosis of the talus (ONT may severely affect the function of the ankle joint. Most orthopedists believe that ONT should be treated at an early stage, but a concise and effective surgical treatment is lacking. In this study, porous titanium alloy rods were prepared and implanted into the tali of sheep with early-stage ONT (IM group. The curative effect of the rods was compared to treatment by core decompression (DC group. No significant differences in bone reconstruction were observed between the two groups at 1 month after intervention. After 3 months, the macroscopic view of gross specimens of the IM group showed ordinary contours, but the specimens of the DC group showed obvious partial bone defects and cartilage degeneration. Quantitative analysis of the reconstructed trabeculae by micro-CT and histological study suggested that the curative effect of the IM group was superior to that of the DC group at 3 months after intervention. These favorable short-term results of the implantation of porous titanium alloy rods into the tali of sheep with early-stage ONT may provide insight into an innovative surgical treatment for ONT.

  3. Anisotropic Thermal Expansion and Cooperative Invar and Anti-Invar Effects in Mn Alloys

    Science.gov (United States)

    Yokoyama, Toshihiko; Eguchi, Keitaro

    2013-02-01

    We have investigated thermal expansion of a tetragonal Mn88Ni12 alloy by x-ray diffraction, Mn and Ni K-edge extended x-ray-absorption fine-structure spectroscopy, and the computational simulations based on the path-integral effective-classical-potential theory. It is found from the x-ray diffraction that the tetragonal lattice constant c exhibits almost no thermal expansion like an Invar alloy, while the lattice constant a shows even larger thermal expansion than usually expected from anharmonicity, implying significant anisotropy in thermal expansion. The extended x-ray-absorption fine-structure reveals that the Mn local environment is actually tetragonally distorted, while the Ni one retains its inherent cubiclike symmetry. Combined with the computational simulations, it is concluded that large thermal expansion along the a axis originates from the anti-Invar effect, while negligibly small thermal expansion along the c axis originates from the cooperative Invar effect. Namely, the tetragonally distorted more stable antiferromagnetic Mn state gives a significantly smaller (slightly longer) atomic radius along the a (c) axis than the radius of the spherical paramagnetic state.

  4. The effect of Mn and B on the magnetic and structural properties of nanostructured Fe60Al40 alloys produced by mechanical alloying.

    Science.gov (United States)

    Rico, M M; Alcázar, G A Pérez; Zamora, L E; González, C; Greneche, J M

    2008-06-01

    The effect of Mn and B on the magnetic and structural properties of nanostructured samples of the Fe60Al40 system, prepared by mechanical alloying, was studied by 57Fe Mössbauer spectrometry, X-ray diffraction and magnetic measurements. In the case of the Fe(60-x)Mn(x)Al40 system, 24 h milling time is required to achieve the BCC ternary phase. Different magnetic structures are observed according to the temperature and the Mn content for alloys milled during 48 h: ferromagnetic, antiferromagnetic, spin-glass, reentrant spin-glass and superparamagnetic behavior. They result from the bond randomness behaviour induced by the atomic disorder introduced by the MA process and from the competitive interactions of the Fe-Fe ferromagnetic interactions and the Mn-Mn and Fe-Mn antiferromagnetic interactions and finally the presence of Al atoms acting as dilutors. When B is added in the Fe60Al40 alloy and milled for 12 and 24 hours, two crystalline phases were found: a prevailing FeAl BCC phase and a Fe2B phase type. In addition, one observes an additional contribution attributed to grain boundaries which increases when both milling time and boron composition increase. Finally Mn and B were added to samples of the Fe60Al40 system prepared by mechanical alloying during 12 and 24 hours. Mn content was fixed to 10 at.% and B content varied between 0 and 20 at.%, substituting Al. X-ray patterns show two crystalline phases, the ternary FeMnAl BCC phase, and a (Fe,Mn)2B phase type. The relative proportion of the last phase increases when the B content increases, in addition to changes of the grain size and the lattice parameter. Such behavior was observed for both milling periods. On the other hand, the magnetic hyperfine field distributions show that both phases exhibit chemical disorder, and that the contribution attributed to the grain boundaries is less important when the B content increases. Coercive field values of about 10(2) Oe slightly increase with boron content

  5. Effects of alloying elements and thermomechanical treatment on 9Cr Reduced Activation Ferritic–Martensitic (RAFM) steels

    International Nuclear Information System (INIS)

    Tan, L.; Yang, Y.; Busby, J.T.

    2013-01-01

    RAFM steels are one of the candidate structural materials for fusion reactors, in which tantalum (Ta) and tungsten (W) are alloyed to replace niobium (Nb) and molybdenum (Mo) in conventional FM steels, respectively. This paper, using three RAFM heats, presents the effects of Ta and the primary austenite stabilizer carbon (C) on microstructure and strength. Thermomechanical treatment (TMT) was also applied to the heats, leading to significant increases in strength, attributable to the TMT-refined sub-grains and precipitates. The Ta-alloying favored the formation of (V, Ta)(N, C) and (Ta, V)C and exhibited greater strength. Fractographs also revealed the beneficial effects of TMT and Ta-alloying. However, extra C content, favoring a larger amount of M 23 C 6 precipitates, did not show strengthening effect

  6. Effect of Trace Ce on Microstructure and Properties of Near-rapidly Solidified Al-Zn-Mg-Cu Alloys

    Directory of Open Access Journals (Sweden)

    HUANG Gao-ren

    2018-03-01

    Full Text Available Through using DSC, XRD, SEM, EDS, static tensile test and other analysis methods of materials, the effect of trace Ce on microstructure and properties of near-rapidly solidified Al-Zn-Mg-Cu alloy was studied in order to find out rational homogenizing heat treatment process. The results show that Ce plays a role of refining grain and purifying molten alloy. The addition of Ce reduces dendritic spacing, refines the grain structures, eliminates dispersed shrinkage. The addition of Ce reduces the initial melting point of low melting eutectic phases by 3℃, under the same homogenization conditions. Trace Ce promotes the dissolution of low melting eutectic phases into the matrix, which improves the effect of homogenization. Homogenization temperatures of alloy A should be lower than 480℃and alloy B should be lower than 470℃; the addition of Ce decreases the homogenization temperature and improves the homogenization effect. The addition of Ce also greatly increases the tensile strength of the alloys.

  7. Effects of alloying and temperature on the high-temperature oxidation of Cr-Cr{sub 2}Nb

    Energy Technology Data Exchange (ETDEWEB)

    Tortorelli, P.F.; DeVan, J.H. [Oak Ridge National Lab., TN (United States); Carson, L.J. [Lincoln Univ., PA (United States)

    1993-06-01

    Effects of alloying additions and temperature on isothermal and cyclic oxidation resistance of Cr-Cr{sub 2}Nb alloys were examined for air exposures. An isothermal exposure temperature of 1100C led to rapid reaction of binary Cr-12 at.% Nb as manifested a high oxidation rate and nonprotective behavior. Generally parabolic kinetics, complicated by some isothermal scale cracking, were observed at 900--1000C. Scale damage was exacerbated by thermal cycling. The addition of 8 at.% Al to Cr-12 at.% Nb did not effect cyclic oxidation resistance, but there was some evidence that scale adherence on Cr-6 at.% Nb-8 at.% Al was better than that for binary Cr-6 at.% Nb. Alloying additions of Al (up to 18 at.%) or Re (2 at.%) did not improve the isothermal oxidation resistance of Cr-12 at.% Nb. However, the tendency for scale damage during both isothermal and thermal cycling exposures suggests that alloying additions that specifically improve scale plasticity or modify growth stresses could be effective for Cr-Nb alloys. 10 refs, 9 figs, 1 tab.

  8. Effects of La on the age hardening behavior and precipitation kinetics in the cast Al–Cu alloy

    International Nuclear Information System (INIS)

    Yao Dongming; Bai Zhihao; Qiu Feng; Li Yanjun; Jiang Qichuan

    2012-01-01

    Highlights: ► La addition enhances the hardness of the Al–Cu alloy. ► La addition facilitates the formation of the θ′ precipitates. ► La addition decreases the nucleation activation energy of the θ′ precipitates. - Abstract: The hardness and thermal stability are the important problems of the cast Al–Cu alloy related to the microstructural changes. In order to increase the possibilities of high temperature applications of the cast Al–Cu alloy, it is necessary to gain a more detail understanding of the correlation between the age hardening and the microstructure in the cast Al–Cu alloy, and the thermal stability of the θ′ precipitates at elevated temperatures. The aim of this work is to investigate the effects of La addition on the age hardening behavior and precipitation kinetics in the Al–Cu alloy in the temperature range from 435 to 523 K. The results indicated that La addition considerably increases the number of the θ′ precipitates and decreases their sizes, which results in the enhanced age hardening effect. The precipitation kinetics analysis showed that the activation energy (13 kJ/mol) of the θ′ precipitate nucleation of the modified alloy is smaller than that (19 kJ/mol) of the unmodified alloy. The decrease in the activation energy of the θ′ precipitate nucleation can be explained with both the enhanced nucleation process due to La/Cu/vacancy aggregating and the increased interaction between Al and Cu atoms.

  9. Phosphorus effect on structure and physical properties of iron-nickel alloys

    International Nuclear Information System (INIS)

    Berseneva, F.N.; Kalinin, V.M.; Rybalko, O.F.

    1982-01-01

    The structure and properties of iron-nickel alloys (30-50 % Ni) containing from 0.02 to 0.5 wt. % P have been investigated. It has been found that phosphorus solubility in iron-nickel alloys at most purified from impurities exceeds limiting solubility values usually observed for commercial alloys. Phosphide eutectics precipitation over the grain boundaries of studied alloys occurs but with phosphorus content equal 0.45 wt. %. The 0.4 wt. % P addition in invar alloys increases saturation magnetization and the Curie point and leads to a more homogeneous structure

  10. Effect of rolling temperature of the magnesium alloy AZ31B formability; Efeito da temperatura de laminacao na deformabilidade da liga de magnesio AZ31B

    Energy Technology Data Exchange (ETDEWEB)

    Catorceno, L.L.C.; Zimmermann, A.J.O.; Padilha, A.F., E-mail: litzy.catorceno@poli.usp.b [Universidade de Sao Paulo (DEMM/EP/USP), SP (Brazil). Escola Politecnica. Dept. de Engenharia Metalurgica e de Materiais

    2010-07-01

    The magnesium alloy AZ31B presents an interesting set of properties, which makes it potential candidate for applications in automotive and aeronautics. The main limitation of magnesium alloys is the low capacity of plastic forming at room temperature. The main motivation of this project is to understand and control the microstructure and crystallographic texture of magnesium alloys, to improve their formability. The effect of rolling temperature on the formability of the alloy was studied in this stage of the project. The alloy in the form of annealed and recrystallized sheets (2 mm thick) was deformed by rolling at four different temperatures: 25, 100, 200 and 250 deg C. The microstructural characterization was achieved using several complementary techniques of microstructural analysis, such as optical microscopy, scanning electron microscopy, X-ray analysis by energy dispersive, X-ray diffraction and microhardness. Results about the effect of rolling temperature on the alloy formability were presented and discussed. (author)

  11. Effect of the Strain Rate on the Tensile Properties of the AZ31 Magnesium Alloy

    International Nuclear Information System (INIS)

    Jeong, Seunghun; Park, Jiyoun; Choi, Ildong; Park, Sung Hyuk

    2013-01-01

    The effect of the strain rate at a range of 10‒4 ⁓ 3 × 10 2 s - 1 on the tensile characteristics of a rolled AZ31 magnesium alloy was studied. The normal tensile specimens were tested using a high rate hydraulic testing machine. Specimens were machined from four sheets with different thicknesses, 1, 1.5, 2 and 3 mm, along three directions, 0°, 45°, and 90° to the rolling direction. The results revealed that all the specimens had a positive strain rate sensitivity of strength, that is, the strength increased with increasing strain rate. This is the same tendency as other automotive steels have. Our results suggest that the AZ31 magnesium alloy has better collision characteristics at high strain rates because of improved strength with an increasing strain rate. Ductility decreased with an increasing strain rate with a strain rate under 1 s - 1, but it increased with an increasing strain rate over 1 s - 1. The mechanical properties of the AZ31 magnesium alloy depend on the different microstructures according to the thickness. Two and 3 mm thickness specimens with a coarse and non-uniform grain structure exhibited worse mechanical properties while the 1.5 mm thickness specimens with a fine and uniform grain structure had better mechanical properties. Specimens machined at 0° and 45° to the rolling direction had higher absorbed energy than that of the 90° specimen. Thus, we demonstrate it is necessary to choose materials with proper thickness and machining direction for use in automotive applications.

  12. Effective site-energy model: A thermodynamic approach applied to size-mismatched alloys

    Science.gov (United States)

    Berthier, F.; Creuze, J.; Legrand, B.

    2017-06-01

    We present a novel energetic model that takes into account atomistic relaxations to describe the thermodynamic properties of AcB1 -c binary alloys. It requires the calculation of the energies on each site of a random solid solution after relaxation as a function of both the local composition and the nominal concentration. These site energies are obtained by molecular static simulations using N -body interatomic potentials derived from the second-moment approximation (SMA) of the tight-binding scheme. This new model allows us to determine the effective pair interactions (EPIs) that drive the short-range order (SRO) and to analyze the relative role of the EPIs' contribution to the mixing enthalpy, with respect to the contribution due to the lattice mismatch between the constituents. We apply this formalism to Au-Ni and Ag-Cu alloys, both of them tending to phase separate in the bulk and exhibiting a large size mismatch. Rigid-lattice Monte Carlo (MC) simulations lead to phase diagrams that are in good agreement with both those obtained by off-lattice SMA-MC simulations and the experimental ones. While the phase diagrams of Au-Ni and Ag-Cu alloys are very similar, we show that phase separation is mainly driven by the elastic contribution for Au-Ni and by the EPIs' contribution for Ag-Cu. Furthermore, for Au-Ni, the analysis of the SRO shows an inversion between the tendency to order and the tendency to phase separate as a function of the concentration.

  13. Effect of RE elements on the microstructural evolution of as cast and SIMA processed Mg-4Al alloy

    International Nuclear Information System (INIS)

    Nayyeri, Mohammad Javad; Khomamizadeh, Farzad

    2011-01-01

    Research highlights: → In this article, we examined the effect of Rare Earth elements on the microstructural development of as cast and semisolid Mg-4Al alloy produced by SIMA process. → Our investigations contained metallographic observation, scanning electron microscope and quantitative metallographic methods. → Results showed that alloy's dendrites turn into larger fully dendritic shape with sharp and narrow arms from equiaxed rosette type as the amount of RE elements increased from 0 through 4 percent. → Also we studied the effect of RE elements on the quality and quantityof intragranular liquid droplets as well as kinetic of microstructural changes. → Moreover, the effect of REs on the other parameters such as fraction of liquid, shape factor and particle size was studied.In this article, we examined the effect of Rare Earth elements on the microstructural development of as cast and semisolid Mg-4Al alloy produced by SIMA process. Our investigations contained metallographic observation, scanning electron microscope and quantitative metallographic methods. Results showed that alloy's dendrites turn into larger fully dendritic shape with sharp and narrow arms from equiaxed rosette type as the amount of RE elements increased from 0 through 4 percent. Also we studied the effect of RE elements on the quality and quantityof intragranular liquid droplets as well as kinetic of microstructural changes. Moreover, the effect of REs on the other parameters such as fraction of liquid, shape factor and particle size was studied. - Abstract: In the present article, the effect of Rare Earth elements on the microstructural development of as cast and semisolid Mg-4Al alloy produced by SIMA process is studied. Investigation conducted by metallographic observation, scanning electron microscope and quantitative metallographic methods. Results showed that alloy's dendrites turn into larger fully dendritic shape with sharp and narrow arms from equiaxed rosette type as the

  14. Effect of nano-additives on microstructure, mechanical properties and wear behaviour of Fe–Cr–B hardfacing alloy

    International Nuclear Information System (INIS)

    Gou, Junfeng; Lu, Pengpeng; Wang, You; Liu, Saiyue; Zou, Zhiwei

    2016-01-01

    Graphical abstract: Wear rate of the hardfacing layers with different nano-additives content and the counterpart GCr15 steel balls under conditions: normal load = 15 N, rotating speed = 400 rpm, total sliding time = 20 min. - Highlights: • Nano-additives remarkably improved the microstructure of hardfacing layers. • The hardness of hardfacing layers increased linearly with the increase of nano-additives. • The wear rate of the hardfacing layer with 0.65 wt.% nano-additives decreased about 88% than that of the hardfacing layer without nano-additives. • According to observation of wear tracks of hardfacing layers, the main wear mechanism was adhesion wear. - Abstract: Fe–Cr–B hardfacing alloys with different nano-additives content were investigated. The effects of nano-additives on the microstructures of hardfacing alloy were studied by using optical microscope, scanning electron microscope, X-ray diffractometer. The hardness and the fracture toughness of hardfacing alloys were measured, respectively. The sliding wear tests were carried out using a ball-on-disc tribometer. The experimental results showed that primary carbide of hardfacing alloys was refined and its distribution became uniform with content of nano-additives increased. The hardfacing alloys are composed of Cr 7 C 3 , Fe 7 C 3 , α-Fe and Fe 2 B according to the results of X-ray diffraction. The hardness of hardfacing alloys increased linearly with the increase of nano-additives. The hardness of the hardfacing alloy with 1.5 wt.% nano-additives increased 54.8% than that of the hardfacing alloy without nano-additives and reached to 1011HV. The K IC of the hardfacing alloy with 0.65 wt.% nano-additives was 15.4 MPam 1/2 , which reached a maximum. The value increased 57.1% than that of the hardfacing alloy without nano-additives. The wear rates of the hardfacing layer with 0.65 wt.% and 1.0 wt.% nano-additives decreased about 88% than that of the hardfacing layer without nano-additives. The

  15. Effect of tool rotational speed and penetration depth on dissimilar aluminum alloys friction stir spot welds

    Directory of Open Access Journals (Sweden)

    Joaquín M. Piccini

    2017-03-01

    Full Text Available In the last years, the automotive industry is looking for the use of aluminum parts in replace of steel parts in order to reduce the vehicles weight. These parts have to be joined, for instance, by welding processes. The more common welding process in the automotive industry is the Resistance Spot Welding (RSW technique. However, RSW of aluminum alloys has many disadvantages. Regarding this situation, a variant of the Friction Stir Welding process called Friction Stir Spot Welding (FSSW has been developed, showing a strong impact in welding of aluminum alloys and dissimilar materials in thin sheets. Process parameters affect the characteristics of the welded joints. However, the information available on this topic is scarce, particularly for dissimilar joints and thin sheets. The aim of this work was to study the effect of the rotational speed and the tool penetration depth on the characteristics of dissimilar FSS welded joints. Defects free joints have been achieved with higher mechanical properties than the ones reported. The maximum fracture load was 5800 N. It was observed that the effective joint length of the welded spots increased with the tool penetration depth, meanwhile the fracture load increased and then decreased. Finally, welding at 1200 RPM produced welded joints with lower mechanical properties than the ones achieved at 680 and 903 RPM.

  16. Effect of Alloying Type and Lean Sintering Atmosphere on the Performance of PM Components

    Science.gov (United States)

    Sundaram, M. Vattur; Shvab, R.; Millot, S.; Hryha, E.; Nyborg, L.

    2017-12-01

    In order to be cost effective and to meet increasing performance demands, powder metallurgy steel components require continuous improvement in terms of materials and process development. This study demonstrates the feasibility of manufacturing structural components using two different alloys systems, i.e. lean Cr-prealloyed and diffusion bonded water atomised powders with different processing conditions. The components were sintered at two different temperatures, i.e. 1120 and 1250 °C for 30 minutes in three different atmospheres: vacuum, N2- 10%H2 atmosphere as well as lean N2-5%H2-0.5%CO-(0.1-0.4)%CH4 sintering atmosphere. Components after sintering were further processed by either low pressure carburizing, sinterhardening or case hardening. All trials were performed in the industrial furnaces to simulate the actual production of the components. Microstructure, fractography, apparent and micro hardness analyses were performed close to the surface and in the middle of the sample to characterize the degree of sintering (temperature and atmosphere) and the effect of heat treatment. In all cases, components possess mostly martensitic microstructure with a few bainitic regions. The fracture surface shows well developed sinter necks. Inter- and trans-granular ductile and cleavage fracture modes are dominant and their fraction is determined by the alloy and processing route.

  17. Effect of composition on corrosion resistance of high-alloy austenitic stainless steel weld metals

    International Nuclear Information System (INIS)

    Marshall, P.I.; Gooch, T.G.

    1993-01-01

    The corrosion resistance of stainless steel weld metal in the ranges of 17 to 28% chromium (Cr), 6 to 60% nickel (Ni), 0 to 9% molybdenum (Mo), and 0.0 to 0.37% nitrogen (N) was examined. Critical pitting temperatures were determined in ferric chloride (FeCl 3 ). Passive film breakdown potentials were assessed from potentiodynamic scans in 3% sodium chloride (NaCl) at 50 C. Potentiodynamic and potentiostatic tests were carried out in 30% sulfuric acid (H 2 SO 4 ) ar 25 C, which was representative of chloride-free acid media of low redox potential. Metallographic examination and microanalysis were conducted on the test welds. Because of segregation of alloying elements, weld metal pitting resistance always was lower than that of matching composition base steel. The difference increased with higher Cr, Mo, and N contents. Segregation also reduced resistance to general corrosion in H 2 SO 4 , but the effect relative to the base steel was less marked than with chloride pitting. Segregation of Cr, Mo, and N in fully austenitic deposits decreased as the Ni' eq- Cr' eq ratio increased. Over the compositional range studied, weld metal pitting resistance was dependent mainly on Mo content and segregation. N had less effect than in wrought alloys. Both Mo and N enhanced weld metal corrosion resistance in H 2 SO 4

  18. Effect of carbon nano tube (CNT) particles in magnetic abrasive finishing of Mg alloy bars

    Energy Technology Data Exchange (ETDEWEB)

    Heng, Lida; Wang, Rui; Kim, Min Soo; Mun, Sang Don; Yang, Gyun Eui [Chonbuk National University, Jeonju (Korea, Republic of)

    2015-11-15

    The Magnetic abrasive finishing (MAF) process is a surface finishing technique in which a magnetic field is used to control abrasive particles during surface finishing of a material. Because smooth surfaces are required for general use, the magnetic abrasive finishing process was developed for finishing surfaces. We studied the effect of CNT particles on the surface roughness of a workpiece. Magnesium alloy bars were used as the cylindrical workpiece and were finished using an MAF process at high workpiece revolution speeds of 1000, 5000, 10000 and 25000 rpm; diamond pastes with diameters of 0.5, 1, and 3 μ were used for comparison. The best value for surface roughness was equivalent to treatment at 0.02 μ m when 0.01 g of CNT particles was mixed together with the unbonded magnetic abrasive at 25000 rpm for 20 seconds. CNT particles were applied to the finishing process to improve the surface roughness of the material, because they have many advantageous properties such as very high strength, light weight, elasticity, and high thermal and air stability. CNT particles are particularly effective for the improvement of Mg alloy bar surface roughness in the MAF process.

  19. The effect of drilling parameters for surface roughness in drilling of AA7075 alloy

    Directory of Open Access Journals (Sweden)

    Yaşar Nafiz

    2017-01-01

    Full Text Available AA7075 aluminum alloy has been very popular significantly interest in the production of structural components in automotive and aviation applications due to its high strength, low density, good plasticity and better machinability comparable to many metals. Particularly, final products must have uniformly high quality to ensure essential safety standards in the aircraft industry. The optimization of hole quality which can variable according to tool geometry and drilling parameters is important in spite of high machinability rate of AA7075 alloy. In this study, the effects of drilling parameters on average surface roughness (Ra has been investigated in drilling of AA7075 with tungsten carbide drills. Machining experiments were performed with three different drill point angles and three different levels of cutting parameters (feed rate, cutting speed. The effects of drilling parameters on thrust force has been determined with ANOVA in %95 confidence level. Feed rate was determined as the most important factor on Ra according to ANOVA results. Moreover, it was shown that increasing feed rate leads to increase of Ra while increasing drill point angle leads to decrease of Ra. The optimum surface roughness was obtained with point angle of 130°, cutting speed of 40 m/min and feed rate of 0.1 mm/rev, thereby the validity of optimization was confirmed with Taguchi method.

  20. Effect of milling strategy and tool geometry on machining cost when cutting titanium alloys

    Directory of Open Access Journals (Sweden)

    Conradie, Pieter

    2015-11-01

    Full Text Available The growing demands on aerospace manufacturers to cut more difficult-to-machine materials at increasing material removal rates require that manufacturers enhance their machining capability. This requires a better understanding of the effects of milling strategies and tool geometries on cutting performance. Ti6Al4V is the most widely-used titanium alloy in the aerospace industry, due to its unique combination of properties. These properties also make the alloy very challenging to machine. Complex aerospace geometries necessitate large material removal, and are therefore generally associated with high manufacturing costs. To investigate the effect of milling strategy and tool geometry on cutting performance, the new constant engagement milling strategy was firstly compared with a conventional approach. Thereafter, a component was milled with different cutting tool geometries. Cost savings of more than 40% were realised by using a constant engagement angle milling strategy. A reduction of 38% in machining time was achieved by using tools with a land on the rake side of the cutting edge. These incremental improvements made it possible to enhance the overall performance of the cutting process.