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Sample records for dealloying mn-cu alloy

  1. De-alloyed platinum nanoparticles

    Science.gov (United States)

    Strasser, Peter [Houston, TX; Koh, Shirlaine [Houston, TX; Mani, Prasanna [Houston, TX; Ratndeep, Srivastava [Houston, TX

    2011-08-09

    A method of producing de-alloyed nanoparticles. In an embodiment, the method comprises admixing metal precursors, freeze-drying, annealing, and de-alloying the nanoparticles in situ. Further, in an embodiment de-alloyed nanoparticle formed by the method, wherein the nanoparticle further comprises a core-shell arrangement. The nanoparticle is suitable for electrocatalytic processes and devices.

  2. Dislocation structure evolution and characterization in the compression deformed Mn-Cu alloy

    International Nuclear Information System (INIS)

    Zhong, Y.; Yin, F.; Sakaguchi, T.; Nagai, K.; Yang, K.

    2007-01-01

    Dislocation densities and dislocation structure arrangements in cold compressed polycrystalline commercial M2052 (Mn-20Cu-5Ni-2Fe) high damping alloy with various strains were determined in scanning mode by X-ray peak profile analysis and electron backscatter diffraction (EBSD). The results indicate that the Mn-Cu-Ni-Fe alloy has an evolution behavior quite similar to the dislocation structure in copper. The dislocation arrangement parameter shows a local minimum in the transition range between stages III and IV that can be related to the transformation of the dislocation arrangement in the cell walls from a polarized dipole wall (PDW) into a polarized tile wall (PTW) structure. This evolution is further confirmed by the results of local misorientation determined by EBSD. In addition, during deformation, the multiplication of dislocation densities in the MnCu alloy is significantly slower than that in copper, and the transition of the dislocation structure is strongly retarded in the MnCu alloy compared with copper. These results can be explained by the mechanism of elastic anisotropy on the dislocation dynamics, as the elastic anisotropy in the MnCu alloy is larger than that in copper, which can strongly retard the multiplication of the dislocation population and the transformation of the dislocation structure. These results are important for research into the plastic working behavior of Mn-Cu-Ni-Fe high damping alloy

  3. Electrodeposition and Characterization of Mn-Cu-Zn Alloys for Corrosion Protection Coating

    Science.gov (United States)

    Tsurtsumia, Gigla; Gogoli, David; Koiava, Nana; Kakhniashvili, Izolda; Jokhadze, Nunu; Lezhava, Tinatin; Nioradze, Nikoloz; Tatishvili, Dimitri

    2017-12-01

    Mn-Cu-Zn alloys were electrodeposited from sulphate bath, containing citrate or EDTA and their mixtures as complexing ligands. The influence of bath composition and deposition parameters on alloys composition, cathodic current efficiency and structural and electrochemical properties were studied. At a higher current density (≥ 37.5 A dm-2) a uniform surface deposit of Mn-Cu-Zn was obtained. Optimal pH of electrolyte (0.3 mol/dm3Mn2+ + 0.6 mol/dm3 (NH4)2SO4 +0.1 mol/dm3Zn2++0.005 mol/dm3 Cu2++ 0.05mol/dm3Na3Cit + 0.15mol/dm3 EDTA; t=300C; τ=20 min) for silvery, nonporous coating of Mn-Cu-Zn alloy was within 6.5-7.5; coating composition: 71-83% Mn, 6-7.8% Cu, 11.5-20% Zn, current efficiency up to 40%. XRD patterns revealed BCT (body centred tetragonal) γ-Mn solid phase solution (lattice constants a=2.68 Å c=3.59 Å). Corrosion measurements of deposited alloys were performed in aerated 3.5% NaCl solution. The corrosion current density (icorr) of the electrodeposited alloys on carbon steel was 10 times lower than corrosion rate of pure zinc and manganese coatings. Triple alloy coatings corrosion potential (Ecorr = -1140 mV vs. Ag/AgCl) preserved negative potential value longer (more than three months) compared to carbon steel substrate (Ecorr = -670 mV vs. Ag/AgCl). Tafel polarization curves taken on Mn-Cu-Zn alloy coating in aerated 3.5% NaCl solution did not show a typical passivation behaviour which can be explained by formation oflow solubility of adherent corrosion products on the alloy surface. Corrosion test of Mn-Cu-Zn electrocoating in chlorine environment shows that it is the best cathodic protective coating for a steel product.

  4. Effect of alloying elements on solidification of primary austenite in Ni-Mn-Cu cast iron

    OpenAIRE

    A. Janus; A. Kurzawa

    2011-01-01

    Within the research, determined were direction and intensity of alloying elements influence on solidification way (directional orvolumetric) of primary austenite dendrites in hypoeutectic austenitic cast iron Ni-Mn-Cu. 50 cast shafts dia. 20 mm were analysed.Chemical composition of the alloy was as follows: 1.7 to 3.3 % C, 1.4 to 3.1 % Si, 2.8 to 9.9 % Ni, 0.4 to 7.7 % Mn, 0 to 4.6 % Cu, 0.14 to0.16 % P and 0.03 to 0.04 % S. The discriminant analysis revealed that carbon influences solidifica...

  5. Effect of alloying elements on solidification of primary austenite in Ni-Mn-Cu cast iron

    Directory of Open Access Journals (Sweden)

    A. Janus

    2011-04-01

    Full Text Available Within the research, determined were direction and intensity of alloying elements influence on solidification way (directional orvolumetric of primary austenite dendrites in hypoeutectic austenitic cast iron Ni-Mn-Cu. 50 cast shafts dia. 20 mm were analysed.Chemical composition of the alloy was as follows: 1.7 to 3.3 % C, 1.4 to 3.1 % Si, 2.8 to 9.9 % Ni, 0.4 to 7.7 % Mn, 0 to 4.6 % Cu, 0.14 to0.16 % P and 0.03 to 0.04 % S. The discriminant analysis revealed that carbon influences solidification of primary austenite dendrites most intensively. It clearly increases the tendency to volumetric solidification. Influence of the other elements is much weaker. This means that the solidification way of primary austenite dendrites in hypoeutectic austenitic cast iron Ni-Mn-Cu does not differ from that in an unalloyed cast iron.

  6. Structural disordering of de-alloyed Pt bimetallic nanocatalysts

    DEFF Research Database (Denmark)

    Spanos, Ioannis; Dideriksen, Knud; Kirkensgaard, Jacob Judas Kain

    2015-01-01

    Platinum bimetallic alloys are well-known for their ability to catalyze the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). PtxCo1-x colloidal nanoparticles were synthesized with varying initial Pt : Co ratios, but constant size to investigate how the initial meta...... dependence on the initial metal composition. Our results suggest that not only the ORR activity, but also the corrosion resistance of the synthesized NPs, are dependent on the structural disorder resulting from the de-alloying process.......Platinum bimetallic alloys are well-known for their ability to catalyze the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). PtxCo1-x colloidal nanoparticles were synthesized with varying initial Pt : Co ratios, but constant size to investigate how the initial metal...... nanoparticles almost completely de-alloy during acid leaching, i.e. under reaction conditions in a fuel cell. To scrutinize the resulting particle structure after de-alloying we used pair distribution function (PDF) analysis and X-ray diffraction (XRD) gaining insight into the structural disorder and its...

  7. Effect of alloying elements on branching of primary austenite dendrites in Ni-Mn-Cu cast iron

    Directory of Open Access Journals (Sweden)

    A. Janus

    2011-04-01

    Full Text Available Within the research, determined were direction and intensity of influence of individual alloying elements on branching degree of primary austenite dendrites in austenitic cast iron Ni-Mn-Cu. 30 cast shafts dia. 20 mm were analysed. Chemical composition of the alloywas as follows: 2.0 to 3.3 % C, 1.4 to 3.1 % Si, 2.8 to 9.5 % Ni, 0.4 to 7.7 % Mn, 0 to 4.6 % Cu, 0.14 to 0.16 % P and 0.03 to 0.04 % S.Analysis was performed separately for the dendrites solidifying in directional and volumetric way. The average distance "x" between the2nd order arms was accepted as the criterion of branching degree. It was found that influence of C, Si, Ni, Mn and Cu on the parameter "x"is statistically significant. Intensity of carbon influence is decidedly higher than that of other elements, and the influence is more intensive in the directionally solidifying dendrites. However, in the case of the alloyed cast iron Ni-Mn-Cu, combined influence of the alloying elements on solidification course of primary austenite can be significant.

  8. Processing and Characterization of Fe-Mn-Cu-Sn-C Alloys Prepared by Ball Milling and Spark Plasma Sintering

    Science.gov (United States)

    Bączek, Elżbieta; Konstanty, Janusz; Romański, Andrzej; Podsiadło, Marcin; Cyboroń, Jolanta

    2018-03-01

    In this work, Fe-Mn-Cu-Sn-C alloys were prepared by means of powder metallurgy (PM). Powder mixtures were ball-milled for 8, 30 and 120 h and densified to abrasive wear was evaluated in both three-body abrasion and two-body abrasion tests. The SEM observations revealed an evident dependence of grain size and microstructural homogeneity on milling time. The XRD analysis showed a marked increase in austenite content in the as-sintered specimens with milling time. Although the proportion of deformation-induced martensite was small, the strengthening effect of abrasion on the subsurface layer of the investigated alloys was clearly indicated by Knoop hardness measurements.

  9. Microstructure and phase evolution during the dealloying of bi-phase Al–Ag alloy

    International Nuclear Information System (INIS)

    Song, T.T.; Gao, Y.L.; Zhang, Z.H.; Zhai, Q.J.

    2013-01-01

    Highlights: ► Selective leaching of α-Al(Ag) and Ag 2 Al occurs simultaneously during dealloying. ► Diffusion of Al and vacancy controlled mechanism dominate the etching of Ag 2 Al. ► The coarsening of ligaments in NPS follows a time dependence of d ∝t 2/5 . - Abstract: The chemical dealloying of bi-phase Al-35Ag alloy has been investigated within the parting limit. The dealloying of α-Al(Ag) and Ag 2 Al commenced simultaneously, and all α-Al(Ag) and part of Ag 2 Al were dealloyed, leaving residual Ag 2 Al to be dealloyed afterwards. The dealloying of the residual Ag 2 Al is associated with vacancy controlled mechanism and diffusion of Al atoms. It is revealed that the diffusions of the Al and Ag atoms during dealloying are significant. The Ag skeletons formed at the initial stage, and became coarsened gradually with a time dependence of d ∝t 2/5 , illustrating the vital role of diffusion of Ag atoms.

  10. Alloy composition dependence of formation of porous Ni prepared by rapid solidification and chemical dealloying

    Energy Technology Data Exchange (ETDEWEB)

    Qi Zhen [Key Laboratory of Liquid Structure and Heredity of Materials, Shandong University, Jingshi Road 73, Jinan 250061 (China); Zhang Zhonghua [Key Laboratory of Liquid Structure and Heredity of Materials, Shandong University, Jingshi Road 73, Jinan 250061 (China)], E-mail: zh_zhang@sdu.edu.cn; Jia Haoling [Key Laboratory of Liquid Structure and Heredity of Materials, Shandong University, Jingshi Road 73, Jinan 250061 (China); Qu Yingjie [Shandong Labor Occupational Technology College, Jingshi Road 388, Jinan 250022 (China); Liu Guodong; Bian Xiufang [Key Laboratory of Liquid Structure and Heredity of Materials, Shandong University, Jingshi Road 73, Jinan 250061 (China)

    2009-03-20

    In this paper, the effect of alloy composition on the formation of porous Ni catalysts prepared by chemical dealloying of rapidly solidified Al-Ni alloys has been investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis and N{sub 2} adsorption experiments. The experimental results show that rapid solidification and alloy composition have a significant effect on the phase constituent and microstructure of Al-Ni alloys. The melt spun Al-20 at.% Ni alloy consists of {alpha}-Al, NiAl{sub 3} and Ni{sub 2}Al{sub 3}, while the melt spun Al-25 and 31.5 at.% Ni alloys comprise NiAl{sub 3} and Ni{sub 2}Al{sub 3}. Moreover, the formation and microstructure of the porous Ni catalysts are dependent upon the composition of the melt spun Al-Ni alloys. The morphology and size of Ni particles in the Ni catalysts inherit from those of grains in the melt spun Al-Ni alloys. Rapid solidification can extend the alloy composition of Al-Ni alloys suitable for preparation of the Ni catalysts, and obviously accelerate the dealloying process of the Al-Ni alloys.

  11. Aging response of shape memory behavior in γ-MnCu alloys

    International Nuclear Information System (INIS)

    Tsuchiya, K.; Kawabata, O.; Umemoto, M.; Sato, H.; Marukawa, K.

    2000-01-01

    An effect of aging on shape memory behavior was investigated for Mn - 15 at % Cu alloy. It was revealed that aging of the alloy at 693 K significantly improves both shape memory effect (SME) and reversible shape memory effect (RSME). The reason of improved SME can be attributed to the decrease in the axial ratio, c/a, of fct martensite phase at room temperature. The enhancement of RSME might be related to the formation of Mn-rich zones associated with a higher antiferromagnetic ordering temperature. (orig.)

  12. Stress corrosion cracking and dealloying of copper-gold alloy in iodine vapor

    International Nuclear Information System (INIS)

    Galvez, M.F.; Bianchi, G.L.; Galvele, J.R.

    1993-01-01

    The susceptibility to stress corrosion cracking of copper-gold alloy in iodine vapor was studied and the results were analyzed under the scope of the surface mobility stress corrosion cracking mechanism. The copper-gold alloy undergoes stress corrosion cracking in iodine. Copper iodide was responsible of that behavior. The copper-gold alloy shows two processes in parallel: stress corrosion cracking and dealloying. As was predicted by the surface mobility stress corrosion cracking mechanism, the increase in strain rate induces an increase in the crack propagation rate. (Author)

  13. Electronic configuration of the c(2 x 2)MnCu two-dimensional alloy in layered structures supported on Cu(100)

    International Nuclear Information System (INIS)

    Gallego, S; Munoz, M C; Huttel, Y; Avila, J; Asensio, M C

    2003-01-01

    The c(2 x 2)MnCu surface alloy on Cu(100) can be considered as a purely two-dimensional magnetic system where the Mn atoms exhibit a large corrugation closely related to their high spin moment. In this paper we investigate the influence of the atomic environment on the electronic and magnetic properties of the two-dimensional alloyed layer, extending our study to the less known multilayered system made of MnCu two-dimensional alloy layers embedded in a Cu crystal. The analysis is based on angle-resolved photoelectron spectroscopy measurements and calculations using the Green function matching method, which allows us to treat exactly the projection of the three-dimensional lattice on the c(2 x 2) plane. A complete study of the valence band is performed along the two-dimensional Brillouin zone in a wide energy range. We show that the presence of Mn results in an important redistribution of the spin-polarized electronic states of the neighbouring Cu atoms. This redistribution is not accompanied by a net charge transfer between different atoms, and also the spin moment of Cu remains small. Most of the new features induced by Mn in the surface alloy are also present in the multilayered system, evidencing that they are specific to the two-dimensional alloyed layer and not surface effects

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  15. Partially and fully de-alloyed glassy ribbons based on Au: Application in methanol electro-oxidation studies

    Energy Technology Data Exchange (ETDEWEB)

    Paschalidou, Eirini Maria, E-mail: epaschal@unito.it [Dipartimento di Chimica e Centro Interdipartimentale NIS (Nanostructured Surfaces and Interfaces), Università di Torino, Via Pietro Giuria 7, 10125, Torino (Italy); Scaglione, Federico [Dipartimento di Chimica e Centro Interdipartimentale NIS (Nanostructured Surfaces and Interfaces), Università di Torino, Via Pietro Giuria 7, 10125, Torino (Italy); Gebert, Annett; Oswald, Steffen [Leibniz Institut für Festkörper- und Werkstoffforschung IFW, Helmholtzstraße 20, 01069, Dresden (Germany); Rizzi, Paola; Battezzati, Livio [Dipartimento di Chimica e Centro Interdipartimentale NIS (Nanostructured Surfaces and Interfaces), Università di Torino, Via Pietro Giuria 7, 10125, Torino (Italy)

    2016-05-15

    In this work, electrochemical de-alloying of an amorphous alloy, Au{sub 40}Cu{sub 28}Ag{sub 7}Pd{sub 5}Si{sub 20}, cast in ribbon form by melt spinning, has been performed, obtaining self standing nanoporous materials suitable for use as electrodes for electrocatalytic applications. The de-alloying encompasses removal of less noble elements and the crystallization of Au, resulting in interconnected ligaments whose size and morphology are described as a function of time. Depending on de-alloying time, the crystals may contain residual amounts of Cu, Ag and Pd, as shown by Auger Electron Spectroscopy (AES), Energy Dispersive Spectroscopy (EDS) and Cyclic Voltammetry (CV) in a basic solution. Current density peaks in the 0.16–0.28 V range (vs Ag/AgCl) indicate that the porous ribbons are active for the electro-oxidation of methanol. The partially de-alloyed samples, which still partially contain the amorphous phase because of the shorter etching times, have finer ligaments and display peaks at lower potential. However, the current density decreases rapidly during repeated potential scans. This is attributed to the obstruction of Au sites, mainly by the Cu oxides formed during the scans. The fully de-alloyed ribbons display current peaks at about 0.20 V and remain active for hundreds of scans at more than 60% of the initial current density. They can be fully re-activated to achieve the same performance levels after a brief immersion in nitric acid. The good activity is due to trapped Ag and Pd atoms in combination with ligament morphology. - Graphical abstract: Fine ligaments and pores made by de-alloying a glassy ribbon of a Au-based alloy, homogeneously produced across the thickness (25 μm) for studying methanol's electro-oxidation behavior. - Highlights: • Size and composition of nanoporous layers tailored in de-alloying Au-based glassy ribbons. • From amorphous precursor fine crystals occur in ligaments with residual Pd and Ag. • Fully de-alloyed

  16. High performance SERS on nanoporous gold substrates synthesized by chemical de-alloying a Au-based metallic glass

    Science.gov (United States)

    Xue, Yanpeng; Scaglione, Federico; Rizzi, Paola; Battezzati, Livio

    2017-12-01

    A Au20Cu48Ag7Pd5Si20 metallic glass precursor has been used to synthesize nanoporous gold by chemical de-alloying in a mixture of HNO3 and HF. Gold ligaments of size ranging from 45 to 100 nm were obtained as a function of HNO3 concentration, electrolyte temperature and de-alloying time. The as-prepared nanoporous gold exhibited strong surface enhanced Raman scattering (SERS) effect using 4,4‧-bi-pyridine as probe molecule. For application in melamine sensing, the detection limit of 10-6 M was achieved, which indicated that this biocompatible material has great potential as SERS active substrate.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-12-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-12-25

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

  19. In situ voltammetric de-alloying of fuel cell catalyst electrode layer: A combined scanning electron microscope/electron probe micro-analysis study

    Science.gov (United States)

    Srivastava, Ratndeep; Mani, Prasanna; Strasser, Peter

    In situ voltammetric de-alloying, i.e. partial selective dissolution of less noble alloy components, is a recently proposed, effective strategy to prepare active electrocatalysts for the oxygen reduction reaction (ORR) [S. Koh, P. Strasser, J. Am. Chem. Soc. 129 (2007) 12624-12625; R. Srivastava, P. Mani, N. Hahn, P. Strasser, Angew. Chem. Int. Ed. 46 (2007) 8988-8991]. However, in situ de-alloying of bimetallics inside electrode layers of membrane-electrode-assemblies (MEAs) seems to defy the requirement of keeping the membrane free of cationic contaminants; yet, when followed by ion exchange, de-alloyed cathodes result in previously unachieved single cell activities of polymer electrolyte membrane fuel cell cathode layers of up to 0.4 A mg Pt -1 at 900 mV cell voltage. The effects of voltammetric Cu de-alloying on the MEA have never been studied before. In the present study, we therefore address this issue and report detailed scanning electron microscope (SEM) imaging of the morphology and electron probe micro-analysis (EPMA) mapping of a MEA at various stages of the de-alloying and ion-exchange process. We investigate the significant loss of Cu from the cathode particle catalyst after de-alloying, demonstrate how the membrane can be cleaned from Cu-ion contamination using ion exchange with protons from liquid inorganic acids, and show that Cu ion exchange does ultimately not affect the activated catalyst particles inside the cathode layer. We correlate the microscopic study of the MEA with its cyclic voltammetric response curves as well as the single cell polarization data.

  20. Correlation between electron work functions of multiphase Cu-8Mn-8Al and de-alloying corrosion

    Science.gov (United States)

    Punburi, P.; Tareelap, N.; Srisukhumbowornchai, N.; Euaruksakul, C.; Yordsri, V.

    2018-05-01

    Low energy electron emission microscopy (LEEM) was used to measure local transition energy that was directly correlated to electron work function (EWF) of multiphase manganese-aluminum bronze alloys. We developed color mapping to distinguish the EWF of multiple phases and clarified that the EWF were in the following order: EWF of α > EWF of β > EWF of κ (EWFα > EWFβ > EWFκ). De-alloying corrosion took place due to the micro-galvanic cell at grain boundaries before it propagated into the β phase that had lower EWF than the α phase. The α phase was a stable phase because it contained high Cu while the β phase contained high Al and Mn. In addition, XRD analysis showed that the texture coefficient of the β phase revealed that almost all of the grains had (2 2 0) orientation, the lowest EWF compared to (1 1 1) and (2 0 0). Furthermore, transmission electron microscopy illustrated that there were fine Cu3Mn2Al precipitates in the Cu2MnAl matrix of the β phase. These precipitates formed micro-galvanic cells which played an important role in accelerating de-alloying corrosion.

  1. Electric charging/discharging characteristics of super capacitor, using de-alloying and anodic oxidized Ti-Ni-Si amorphous alloy ribbons.

    Science.gov (United States)

    Fukuhara, Mikio; Sugawara, Kazuyuki

    2014-01-01

    Charging/discharging behaviors of de-alloyed and anodic oxidized Ti-Ni-Si amorphous alloy ribbons were measured as a function of current between 10 pA and 100 mA, using galvanostatic charge/discharging method. In sharp contrast to conventional electric double layer capacitor (EDLC), discharging behaviors for voltage under constant currents of 1, 10 and 100 mA after 1.8 ks charging at 100 mA show parabolic decrease, demonstrating direct electric storage without solvents. The supercapacitors, devices that store electric charge on their amorphous TiO2-x surfaces that contain many 70-nm sized cavities, show the Ragone plot which locates at lower energy density region near the 2nd cells, and RC constant of 800 s (at 1 mHz), which is 157,000 times larger than that (5 ms) in EDLC.

  2. Insights into electrochemical dealloying of Cu out of Au-doped Pt-alloy nanoparticles at the sub-nano-scale

    Directory of Open Access Journals (Sweden)

    Matija Gatalo

    2018-03-01

    Full Text Available Pt alloy nanoparticles present the most probable candidate to be used as the cathode cathodic oxygen reduction reaction electrocatalyst for achieving commercialization targets of the low-temperature fuel cells. It is therefore very important to understand its activation and degradation processes. Besides the ones known from the pure Pt electrocatalysts, the dealloying phenomena possess a great threat since the leached less-noble metal can interact with the polymer membrane or even poison the electrocatalyst. In this study, we present a solution, supported by in-depth advance electrochemical characterization, on how to suppress the removal of Cu from the Pt alloy nanoparticles.

  3. DEALLOYING, MICROSTRUCTURE AND THE CORROSION/PROTECTION OF CAST MAGNESIUM ALLOYS

    Energy Technology Data Exchange (ETDEWEB)

    Sieradzki, Karl; Aiello, Ashlee; McCue, Ian

    2017-12-15

    The purpose of this project was to develop a greater understanding of micro-galvanic corrosion effects in cast magnesium alloys using both experimental and computational methods. Experimental accomplishments have been made in the following areas of interest: characterization, aqueous free-corrosion, atmospheric corrosion, ionic liquid dissolution, rate kinetics of oxide dissolution, and coating investigation. Commercial alloys (AZ91D, AM60, and AZ31B), binary-phase alloys (αMg-2at.%Al, αMg-5at.%Al, and Mg-8at.%Al), and component phases (Mg, Al, β-Mg, β-1%Zn, MnAl3) were obtained and characterized using energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Full immersion in aqueous chloride was used to characterize the corrosion behavior of alloys. Rotating disc electrodes (RDEs) were used to observe accelerated long-term corrosion behavior. Al surface redistribution for freely corroded samples was analyzed using SEM, EDS, and lithium underpotential deposition (Li UPD). Atmospheric corrosion was observed using contact angle evolution, overnight pH monitoring, and surface pH evolution studies. Ionic liquid corrosion characterization was performed using linear sweep voltammetry and potentiostatic dissolution in 150° choline chloride-urea (cc-urea). Two surface coatings were investigated: (1) Li-carbonate and (2) cc-urea. Li-carbonate coatings were characterized using X-ray photoelectron spectroscopy (XPS), SEM, and aqueous free corrosion potential monitoring. Hydrophobic cc-urea coatings were characterized using contact angle measurements and electrochemical impedance spectroscopy. Oxide dissolution rate kinetics were studied using inductively coupled plasma mass spectroscopy (ICP-MS). Computational accomplishments have been made through the development of Kinetic Monte Carlo (KMC) simulations which model time- and composition-dependent effects on the microstructure due to spatial redistribution of alloying

  4. Surface effects on the mechanical elongation of AuCu nanowires: De-alloying and the formation of mixed suspended atomic chains

    International Nuclear Information System (INIS)

    Lagos, M. J.; Autreto, P. A. S.; Galvao, D. S.; Ugarte, D.; Bettini, J.; Sato, F.; Dantas, S. O.

    2015-01-01

    We report here an atomistic study of the mechanical deformation of Au x Cu (1−x) atomic-size wires (nanowires (NWs)) by means of high resolution transmission electron microscopy experiments. Molecular dynamics simulations were also carried out in order to obtain deeper insights on the dynamical properties of stretched NWs. The mechanical properties are significantly dependent on the chemical composition that evolves in time at the junction; some structures exhibit a remarkable de-alloying behavior. Also, our results represent the first experimental realization of mixed linear atomic chains (LACs) among transition and noble metals; in particular, surface energies induce chemical gradients on NW surfaces that can be exploited to control the relative LAC compositions (different number of gold and copper atoms). The implications of these results for nanocatalysis and spin transport of one-atom-thick metal wires are addressed

  5. Surface effects on the mechanical elongation of AuCu nanowires: De-alloying and the formation of mixed suspended atomic chains

    Energy Technology Data Exchange (ETDEWEB)

    Lagos, M. J. [Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, R. Sergio B. de Holanda 777, 13083-859 Campinas-SP (Brazil); Laboratório Nacional de Nanotecnologia-LNNANO, 13083-970 Campinas-SP (Brazil); Autreto, P. A. S.; Galvao, D. S., E-mail: galvao@ifi.unicamp.br; Ugarte, D. [Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, R. Sergio B. de Holanda 777, 13083-859 Campinas-SP (Brazil); Bettini, J. [Laboratório Nacional de Nanotecnologia-LNNANO, 13083-970 Campinas-SP (Brazil); Sato, F.; Dantas, S. O. [Departamento de Física, ICE, Universidade Federal de Juiz de Fora, 36036-330 Juiz de Fora-MG (Brazil)

    2015-03-07

    We report here an atomistic study of the mechanical deformation of Au{sub x}Cu{sub (1−x)} atomic-size wires (nanowires (NWs)) by means of high resolution transmission electron microscopy experiments. Molecular dynamics simulations were also carried out in order to obtain deeper insights on the dynamical properties of stretched NWs. The mechanical properties are significantly dependent on the chemical composition that evolves in time at the junction; some structures exhibit a remarkable de-alloying behavior. Also, our results represent the first experimental realization of mixed linear atomic chains (LACs) among transition and noble metals; in particular, surface energies induce chemical gradients on NW surfaces that can be exploited to control the relative LAC compositions (different number of gold and copper atoms). The implications of these results for nanocatalysis and spin transport of one-atom-thick metal wires are addressed.

  6. Dealloying of Cu-Based Metallic Glasses in Acidic Solutions: Products and Energy Storage Applications.

    Science.gov (United States)

    Wang, Zhifeng; Liu, Jiangyun; Qin, Chunling; Yu, Hui; Xia, Xingchuan; Wang, Chaoyang; Zhang, Yanshan; Hu, Qingfeng; Zhao, Weimin

    2015-04-29

    Dealloying, a famous ancient etching technique, was used to produce nanoporous metals decades ago. With the development of dealloying techniques and theories, various interesting dealloying products including nanoporous metals/alloys, metal oxides and composites, which exhibit excellent catalytic, optical and sensing performance, have been developed in recent years. As a result, the research on dealloying products is of great importance for developing new materials with superior physical and chemical properties. In this paper, typical dealloying products from Cu-based metallic glasses after dealloying in hydrofluoric acid and hydrochloric acid solutions are summarized. Several potential application fields of these dealloying products are discussed. A promising application of nanoporous Cu (NPC) and NPC-contained composites related to the energy storage field is introduced. It is expected that more promising dealloying products could be developed for practical energy storage applications.

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

    Directory of Open Access Journals (Sweden)

    A. Janus

    2014-07-01

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

  8. Group IVA Element (Si, Ge, Sn)-Based Alloying/Dealloying Anodes as Negative Electrodes for Full-Cell Lithium-Ion Batteries.

    Science.gov (United States)

    Liu, Dequan; Liu, Zheng Jiao; Li, Xiuwan; Xie, Wenhe; Wang, Qi; Liu, Qiming; Fu, Yujun; He, Deyan

    2017-12-01

    To satisfy the increasing energy demands of portable electronics, electric vehicles, and miniaturized energy storage devices, improvements to lithium-ion batteries (LIBs) are required to provide higher energy/power densities and longer cycle lives. Group IVA element (Si, Ge, Sn)-based alloying/dealloying anodes are promising candidates for use as electrodes in next-generation LIBs owing to their extremely high gravimetric and volumetric capacities, low working voltages, and natural abundances. However, due to the violent volume changes that occur during lithium-ion insertion/extraction and the formation of an unstable solid electrolyte interface, the use of Group IVA element-based anodes in commercial LIBs is still a great challenge. Evaluating the electrochemical performance of an anode in a full-cell configuration is a key step in investigating the possible application of the active material in LIBs. In this regard, the recent progress and important approaches to overcoming and alleviating the drawbacks of Group IVA element-based anode materials are reviewed, such as the severe volume variations during cycling and the relatively brittle electrode/electrolyte interface in full-cell LIBs. Finally, perspectives and future challenges in achieving the practical application of Group IVA element-based anodes in high-energy and high-power-density LIB systems are proposed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. 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

  10. FABRICATION OF NANOPOROUS Ni VIA DEALLOYING OF ZINC-NICKEL COATINGS

    OpenAIRE

    Seda , Oturak

    2015-01-01

    Dealloying is a selective leaching of one component in a multicomponent alloy so as to produce a nanoporous structure. In this study, it was aimed to produce nanoporous Ni coating by selective leaching of Zn in a Zn-Ni alloy. To achieve this, first the Zn-Ni alloy was obtained by electrodeposition in a bath containing Zn and Ni salts. Then, dealloying was performed at different concentrations of NaOH solution. Dealloying led to crack formation in the coatings which thus prevented the formatio...

  11. Chlorine triggered de-alloying of AuAg@Carbon nanodots: Towards fabrication of a dual signalling assay combining the plasmonic property of bimetallic alloy nanoparticles and photoluminescence of carbon nanodots

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadpour, Zahra; Safavi, Afsaneh, E-mail: safavi@susc.ac.ir; Abdollahi, Seyyed Hossein

    2017-03-22

    Integration of Au-Ag alloy and fluorescent carbon nanodots (C-dots) into a single platform resulted in a new dual sensing assay for chlorine. Selective etching of Ag from AuAg@C-dots was transformed into: (i) colorimetric signal by surface plasmon resonance (SPR) tuning of the alloy and (ii) fluorimetric signal by perturbation of fluorescence energy transfer between C-dots and alloy nanoparticles. Fast oxidizing of silver atoms incorporated in the bimetallic structure induced by chlorine resulted in selective de-alloying of bimetallic hybrid nanoparticles and an intense visible change of the colloidal dispersion color. On the other hand, the systematic change in Au/Ag ratio strongly affected the emission intensity of C-dots in the hybrid structure leading to an enhancement in the fluorescence signal. Thus, the assay enables the detection of chlorine both under visible and UV lights with high sensitivity. The detection limit (DL) values were calculated as 6.2 × 10{sup −7} M and 5.1 × 10{sup −7} M through colorimetric and fluorimetric pathways, respectively. Most importantly, it was demonstrated to be selective over common cations, anions and some reactive oxygen species (ROS). This assay was successfully applied to the determination of chlorine concentration in bleach solution and tap water. It is robust and is suitable for cost effective chlorine measurement in environmental samples. - Highlights: • A new dual signalling assay for hypochlorite ion is introduced. • Bimetallic Au-Ag nanoparticles are hybridized with fluorescent carbon nanodots. • It shows amplified colorimetric response with respect to monometallic counterparts. • This sensor is multifunctional, robust, rapid and sensitive. • The practical applicability is investigated for environmental monitoring.

  12. Dealloyed Ruthenium Film Catalysts for Hydrogen Generation from Chemical Hydrides

    Directory of Open Access Journals (Sweden)

    Ramis B. Serin

    2017-07-01

    Full Text Available Thin-film ruthenium (Ru and copper (Cu binary alloys have been prepared on a Teflon™ backing layer by cosputtering of the precious and nonprecious metals, respectively. Alloys were then selectively dealloyed by sulfuric acid as an etchant, and their hydrogen generation catalysts performances were evaluated. Sputtering time and power of Cu atoms have been varied in order to tailor the hydrogen generation performances. Similarly, dealloying time and the sulfuric acid concentration have also been altered to tune the morphologies of the resulted films. A maximum hydrogen generation rate of 35 mL min−1 was achieved when Cu sputtering power and time were 200 W and 60 min and while acid concentration and dealloying time were 18 M and 90 min, respectively. It has also been demonstrated that the Ru content in the alloy after dealloying gradually increased with the increasing the sputtering power of Cu. After 90 min dealloying, the Ru to Cu ratio increased to about 190 times that of bare alloy. This is the key issue for observing higher catalytic activity. Interestingly, we have also presented template-free nanoforest-like structure formation within the context of one-step alloying and dealloying used in this study. Last but not least, the long-time hydrogen generation performances of the catalysts system have also been evaluated along 3600 min. During the first 600 min, the catalytic activity was quite stable, while about 24% of the catalytic activity decayed after 3000 min, which still makes these systems available for the development of robust catalyst systems in the area of hydrogen generation.

  13. Effect of Chemical Composition on Number of Eutectic Colonies in Ni-Mn-Cu Cast Iron

    Directory of Open Access Journals (Sweden)

    Janus A.

    2013-03-01

    Full Text Available Determined were direction and intensity of influence of alloying additions on the number of eutectic graphite colonies in austenitic cast iron Ni-Mn-Cu. Chemical composition of the cast iron was 1.7 to 3.3% C, 1.4 to 3.1% Si, 2.8 to 9.9% Ni, 0.4 to 7.7% Mn, 0 to 4.6% Cu, 0.14 to 0.16% P and 0.03 to 0.04% S. Analysed were structures of mottled (20 castings and grey (20 castings cast iron. Obtained were regression equations determining influence intensity of individual components on the number of graphite colonies per 1 cm2 (LK. It was found that, in spite of high total content of alloying elements in the examined cast iron, the element that mainly decides the LK value is carbon, like in a plain cast iron.

  14. Slurry Erosion Behavior of Destabilized and Deep Cryogenically Treated Cr-Mn-Cu White Cast Irons

    Directory of Open Access Journals (Sweden)

    S. Gupta

    2016-12-01

    Full Text Available The effects of destabilization treatment and destabilization followed by cryogenic treatment have been evaluated on the microstructural evolution and sand-water slurry erosion behavior of Cr-Mn-Cu white cast irons. The phase transformations after the destabilization and cryotreatment have been characterized by bulk hardness measurement, optical and scanning electron microscopy, x-ray diffraction analysis. The static corrosion rate has been measured in tap water (with pH=7 and the erosion-corrosion behavior has been studied by slurry pot tester using sand-water slurry. The test results indicate that the cryogenic treatment has a significant effect in minimizing the as-cast retained austenite content and transforming into martensitic and bainitic matrix embedded with ultra-fine M7C3 alloy carbides. In contrast, by conventional destabilization treatment retained austenite in the matrix are not fully eliminated. The slurry erosive wear resistance has been compared with reference to destabilized and cryotreated high chromium iron samples which are commonly employed for such applications. The cryotreated Cr-Mn-Cu irons have exhibited a comparable erosive wear performance to those of high chromium irons. Higher hardness combined with improved corrosion resistance result in better slurry erosion resistance.

  15. Dealloying evidence on corroded brass by laser-induced breakdown spectroscopy mapping and depth profiling measurements

    Science.gov (United States)

    Cerrato, R.; Casal, A.; Mateo, M. P.; Nicolas, G.

    2017-04-01

    The dealloying phenomenon, also called demetalification, is a; consequence of a corrosion problem found in binary alloys where an enrichment of one of the two main elements of the alloy is produced at the expense of the leaching of the other element. In the present work, the ability of laser induced breakdown spectroscopy (LIBS) for the detection and characterization of dealloying films formed on metal has been tested. For this purpose, specific areas of brass specimens have been subjected to a chemical attack of the surface in order to produce a selective leaching of zinc or dezincification. For the lateral and in-depth characterization of the dealloyed areas by LIBS, depth profiles, 2D and 3D maps have been generated from the treated samples and from a reference non-treated sample. The differences in the maps and depth profiles between the corroded and non-corroded regions have allowed to reveal the localization and extension of the dealloying process along the brass sample surface and to estimate the thickness of the dezincification layers, demonstrating the capability of LIBS technique for the characterization of dealloying phenomena.

  16. "Dealloying" Phase Separation during Growth of Au on Ni(110)

    DEFF Research Database (Denmark)

    Nielsen, L. Pleth; Besenbacher, Flemming; Stensgaard, I.

    1995-01-01

    Combined scanning tunneling microscopy and ion-scattering studies have revealed a new "dealloying" phase transition during the growth of Au on Ni(110). The Au atoms, which initially alloy into the Ni(110) surface, phase separate into a vacancy-stabilized Au dimer-trimer chain structure at Au...... coverages larger than 0.4 monolayer. Using the effective-medium theory, we show that the resulting structure as well as the physical mechanism responsible for the phase transition are closely related to the surface stress induced by the substituted Au....

  17. Chitosan-based Schiff base-metal complexes (Mn, Cu, Co) as ...

    Indian Academy of Sciences (India)

    based Schiff base-metal complexes (Mn, Cu, Co) as heterogeneous, new catalysts for the -isophorone oxidation. C S Thatte ... A new chitosan-based Schiff base was prepared and complexed with manganese, cobalt and copper. These Schiff ...

  18. Lattice-Strain Control of Exceptional Activity in Dealloyed Core-Shell Fuel Cell Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Strasser, Peter

    2011-08-19

    We present a combined experimental and theoretical approach to demonstrate how lattice strain can be used to continuously tune the catalytic activity of the oxygen reduction reaction (ORR) on bimetallic nanoparticles that have been dealloyed. The sluggish kinetics of the ORR is a key barrier to the adaptation of fuel cells and currently limits their widespread use. Dealloyed Pt-Cu bimetallic nanoparticles, however, have been shown to exhibit uniquely high reactivity for this reaction. We first present evidence for the formation of a core-shell structure during dealloying, which involves removal of Cu from the surface and subsurface of the precursor nanoparticles. We then show that the resulting Pt-rich surface shell exhibits compressive strain that depends on the composition of the precursor alloy. We next demonstrate the existence of a downward shift of the Pt d-band, resulting in weakening of the bond strength of intermediate oxygenated species due to strain. Finally, we combine synthesis, strain, and catalytic reactivity in an experimental/theoretical reactivity-strain relationship which provides guidelines for the rational design of strained oxygen reduction electrocatalysts. The stoichiometry of the precursor, together with the dealloying conditions, provides experimental control over the resulting surface strain and thereby allows continuous tuning of the surface electrocatalytic reactivity - a concept that can be generalized to other catalytic reactions.

  19. Deposition of Mn-Cu-Ni-enriched sediments during glacial period in the Central Indian Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Borole, D.V.

    Two siliceous sediment cores collected from the Central Indian Basin have been analysed for organic carbon, biogenic silica, Al, Mn, Ni and Cu content. The concentrations of Mn, Cu and Ni showed one order of magnitude variation (an enrichment by a...

  20. Highly active dealloyed Cu@Pt core-shell electrocatalyst towards 2-propanol electrooxidation in acidic solution

    Energy Technology Data Exchange (ETDEWEB)

    Poochai, Chatwarin, E-mail: p_chatwarin@yahoo.com

    2017-02-28

    Highlights: • This is the first report on electrooxidation of 2-propanol in acidic media on dealloyed Cu@Pt/CP core-shell electrocatalyst. • The dealloyed Cu@Pt/CP is prepared using cyclic co-electrodeposition and selective Cu dealloying (CCEd-sCuD). • The structure of dealloyed Cu@Pt/CP is core-shell structure with Cu-rich core and Pt-rich surface. • The dealloyed Cu@Pt/CP shows high activity and great stability towards 2-propanol electrooxidation in acidic media. - Abstract: Dealloyed Cu@Pt core-shell electrocatalyst was fabricated by cyclic co-electrodeposition and selective Cu dealloying (CCEd-sCuD) on carbon paper (CP), namely Cu@Pt/CP. The Cu@Pt/CP exhibited a core-shell structure comprising with a Cu-rich core and a Pt-rich shell. The crystalline phases of Pt/CP and Cu@Pt/CP were a face-centered cubic (fcc). The compressive lattice strain approximately 0.85% was found in the Cu@Pt/CP owing to a lattice mismatch between a core and a shell region. In the core-region, Cu was formed Pt-Cu alloy as major and copper oxide and also metallic copper as minor. The morphology and grain size of the Cu@Pt/CP displayed a porous spherical shape with 100 nm in diameter, while those of Pt/CP seemed to be a cubic shape with smaller diameter of 40 nm. In electrochemical and catalytic activity, the surface of Cu@Pt/CP had a larger electrochemical active surface area (ECSA) than that of Pt/CP due to a porous formation caused by Cu dealloying. It is not surprising that the Cu@Pt/CP showed higher catalytic activity and greater stability towards 0.5 M 2-propanol electrooxidation in 0.5 M H{sub 2}SO{sub 4} in terms of peak current density (j{sub p}), peak potential (E{sub p}), onset potential (E{sub onset}), diffusion coefficient (D), and charge transfer resistance (R{sub ct}) which were caused by electronic structure modification, higher compressive lattice strain, and larger ECSA, compared with Pt/CP.

  1. Nanoporous PdCo Catalyst for Microfuel Cells: Electrodeposition and Dealloying

    Directory of Open Access Journals (Sweden)

    Satoshi Tominaka

    2011-01-01

    Full Text Available PdCo alloy is a promising catalyst for oxygen reduction reaction of direct methanol fuel cells because of its high activity and the tolerance to methanol. We have applied this catalyst in order to realize on-chip fuel cell which is a membraneless design. The novel design made the fuel cells to be flexible and integratable with other microdevices. Here, we summarize our recent research on the synthesis of nanostructured PdCo catalyst by electrochemical methods, which enable us to deposit the alloy onto microelectrodes of the on-chip fuel cells. First, the electrodeposition of PdCo is discussed in detail, and then, dealloying for introducing nanopores into the electrodeposits is described. Finally, electrochemical response and activities are fully discussed.

  2. Synthesis and luminescence properties of ZnS and metal (Mn, Cu)-doped-ZnS ceramic powder

    Science.gov (United States)

    Ummartyotin, S.; Bunnak, N.; Juntaro, J.; Sain, M.; Manuspiya, H.

    2012-03-01

    ZnS and metal (Mn, Cu)-doped-ZnS were successfully prepared by wet chemical synthetic route. The understanding of substituted metal ions (Mn, Cu) into ZnS leads to transfer the luminescent centre by small amount of metal dopant (Mn, Cu). Fourier transform infrared and X-ray diffraction were used to determine chemical bonding and crystal structure, respectively. It showed that small amount of metal (Mn, Cu) can be completely substituted into ZnS lattice. X-ray fluorescence was used to confirm the existence of metal-doped ZnS. Scanning electron microscope revealed that their particles exhibits blocky particle with irregular sharp. Laser confocal microscope and photoluminescence spectroscopy showed that ZnS and metal-doped-ZnS exhibited intense, stable, and tunable emission covering the blue to red end of the visible spectrum. ZnS, Mn-doped-ZnS and Cu-doped-ZnS generated blue, yellow and green color, respectively.

  3. Robust synthesis of gold cubic nanoframes through a combination of galvanic replacement, gold deposition, and silver dealloying.

    Science.gov (United States)

    Wan, Dehui; Xia, Xiaohu; Wang, Yucai; Xia, Younan

    2013-09-23

    A facile, robust approach to the synthesis of Au cubic nanoframes is described. The synthesis involves three major steps: 1) preparation of Au-Ag alloyed nanocages using a galvanic replacement reaction between Ag nanocubes and HAuCl4 ; 2) deposition of thin layers of pure Au onto the surfaces of the nanocages by reducing HAuCl4 with ascorbic acid, and; 3) formation of Au cubic nanoframes through a dealloying process with HAuCl4 . The key to the formation of Au cubic nanoframes is to coat the surfaces of the Au-Ag nanocages with sufficiently thick layers of Au before they are dealloyed. The Au layer could prevent the skeleton of a nanocage from being fragmented during the dealloying step. The as-prepared Au cubic nanoframes exhibit tunable localized surface plasmon resonance peaks in the near-infrared region, but with much lower Ag content as compared with the initial Au-Ag nanocages. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Nanoporous gold microelectrode prepared from potential modulated electrochemical alloying–dealloying in ionic liquid

    International Nuclear Information System (INIS)

    Jiang, Junhua; Wang, Xinying; Zhang, Lei

    2013-01-01

    Highlights: • A green chemistry method for producing nanoporous gold microelectrode was studied. • An ionic liquid plating bath was utilized for electrochemical alloying–dealloying. • Nanostructures of gold surface layers can be tuned by modulating potential. • Nanoporous gold microelectrode has high surface area and merit of a microelectrode. • Nitrite oxidation and reduction on nanoporous gold microelectrode were studied. -- Abstract: Nanoporous gold (NPG) microelectrodes with high surface area and open pore network were successfully prepared by applying modulated potential to a polycrystalline Au-disk microelectrode in ionic liquid electrolyte containing ZnCl 2 at elevated temperature. During cathodic process, Zn is electrodeposited and interacted with Au microdisk substrate to form a AuZn alloy phase. During subsequent anodic process, Zn is selectively dissolved from the alloy phase, leading to the formation of a NPG layer which can grow with repetitive potential modulation. Scanning-electron microscope and energy dispersive X-ray microscope measurements show that the NPG microelectrodes possessing nanoporous structures can be tuned via potential modulation, and chemically contain a small amount of Zn whose presence has no obvious influence on electrochemical responses of the electrodes. Steady-state and cyclic voltammetric studies suggest that the NPG microelectrodes have high surface area and keep diffusional properties of a microelectrode. Electrochemical nitrite reduction and oxidation are studied as model reactions to demonstrate potential applications of the NPG microelectrodes in electrocatalysis and electroanalysis. These facts suggest that the potential-modulated electrochemical alloying/dealloying in ionic liquid electrolyte offers a convenient green-chemistry method for the preparation of nanoporous microelectrodes

  5. The Concentration of Zn, Fe, Mn, Cu and Se in Fiber Fractions of Legumes in Indonesia

    Directory of Open Access Journals (Sweden)

    Evitayani

    2010-05-01

    Full Text Available This study was carried out to evaluate concentration of micro minerals (Zn, Fe, Mn, Cu and Se of forages and their distribution in fiber fraction (neutral detergent fiber/NDF and acid detergent fiber/ADF in West Sumatra during dry and rainy seasons. Four species of common legume namely Leucaena leucocephala, Centrocema pubescens, Calopogonium mucunoides and Acacia mangium were collected at native pasture during rainy and dry seasons. The results showed that micro minerals concentration of forages and their distribution in fiber fraction varied among species and season. In general, concentration of micro minerals was slightly higher in rainy season compared to dry season either in legumes forages. Data on legume forages showed that 75% of legumes were deficient in Zn and Mn, 62.5 % deficient in Cu and 50 % deficient in Se. There was no species of legume deficient in Fe. Distribution of micro minerals in NDF and ADF were also significantly affected by species and season and depends on the kinds of element measured. Generally, micro minerals were associated in fiber fractions and it yield much higher during dry season compared to rainy season. Iron (Fe and selenium (Se in forages were the highest elements associated in NDF and ADF, while the lowest was found in Copper (Cu. (Animal Production 12(2: 105-110 (2010Keywords: Seasons, forages, micro mineral distribution, fiber fraction

  6. Synthesis and magnetic properties of hexagonal Y(Mn,Cu)O{sub 3} multiferroic materials

    Energy Technology Data Exchange (ETDEWEB)

    Jeuvrey, L., E-mail: laurent.jeuvrey@univ-rennes1.fr [Sciences Chimiques de Rennes, UMR-CNRS 6226, Universite de Rennes 1, 35042 Rennes cedex (France); Pena, O. [Sciences Chimiques de Rennes, UMR-CNRS 6226, Universite de Rennes 1, 35042 Rennes cedex (France); Moure, A.; Moure, C. [Electroceramics Department, Instituto de Ceramica y Vidrio, CSIC, C/Kelsen 5, 28049, Madrid (Spain)

    2012-03-15

    Single-phase hexagonal-type solid solutions based on the multiferroic YMnO{sub 3} material were synthesized by a modified Pechini process. Copper doping at the B-site (YMn{sub 1-x}Cu{sub x}O{sub 3}; x<0.15) and self-doping at the A-site (Y{sub 1+y}MnO{sub 3}; y<0.10) successfully maintained the hexagonal structure. Self-doping was limited to y(Y)=2 at% and confirmed that excess yttrium avoids formation of ferromagnetic manganese oxide impurities but creates vacancies at the Mn site. Chemical substitution at the B-site inhibits the geometrical frustration of the Mn{sup 3+} two-dimensional lattice. The magnetic transition at T{sub N} decreases from 70 K down to 49 K, when x(Cu) goes from 0 to 15 at%. Weak ferromagnetic Mn{sup 3+}-Mn{sup 4+} interactions created by the substitution of Mn{sup 3+} by Cu{sup 2+}, are visible through the coercive field and spontaneous magnetization but do not modify the overall magnetic frustration. Presence of Mn{sup 3+}-Mn{sup 4+} pairs leads to an increase of the electrical conductivity due to thermally-activated small-polaron hopping mechanisms. Results show that local ferromagnetic interactions can coexist within the frustrated state in the hexagonal polar structure. - Highlights: Black-Right-Pointing-Pointer Hexagonal-type solid solutions of Y(Mn,Cu)O{sub 3} synthesized by Pechini process. Black-Right-Pointing-Pointer Chemical substitution at B site inhibits geometrical magnetic frustration. Black-Right-Pointing-Pointer Magnetic transition decreases with Cu-doping. Black-Right-Pointing-Pointer Local ferromagnetic Mn-Mn interactions coexist with the frustrated state.

  7. Crystal structure of the Re(Mn, Cu)6 (Re=Ce, Pr, Nd, Sm, Gd) and RE(Mn, Ni)3 (RE=Nd, Sm) compounds

    International Nuclear Information System (INIS)

    Kalychak, Ya.M.; Davydyuk, P.P.; Bodak, O.I.

    1984-01-01

    A crystalline structure of REE(Mn, Cu) 6 compounds is studied by the method of monocrystal and powder using Ce(Mn, Cu) 6 compound as an example. For the Cesub(0.143)Mnsub(0.220)Cusub(0.637) monocrystal a=0.65781(6), c=0.50454(6)nm, a diffraction class is 4/mmm. Isostructural compound lattice periods at Mn content of 0.220 a parts are equal to: a=0.65666(6), c=0.50280(6)nm for Pr(Mn, Cu) 6 ; a=0.6560(3), c=0.5013(3)nm for Nd(Mn, Cu) 6 ; a=0.65220(6), c=0.49975(9)nm for Sm(Mn, Cu) 6 ; a=0.6520(1), c=0.4965(1)nm for Gd(Mn, Cu) 6 . Nd(Mn, Ni) 3 and Sm(Mn, Ni) 3 structures are studied by the powder method. Diffractograms of these compounds are displayed successfully in the P6 3 /mmc space group at a=0.5183(3), c=1.676(1)nm for Smsub(0.25)Mnsub(0.35)Nisub(0.40) and at a=0.5152(2), c=1.6710(6)nm for Ndsub(0.25)Mnsub(0.25)Nisub(0.50). Refinement of the structure is conducted using Sm(Mn, Ni) 3 as an example to confirm the belonging of these compounds to the CeNi 3 type, when disposing Sm atoms in positions of Ce atoms and statistical mixture (Mn, Ni) atoms in positions of Ni atoms

  8. Alloys studied by neutron scattering

    International Nuclear Information System (INIS)

    Morii, Yukio

    1993-01-01

    Neutron scattering study on the martensitic transformation and spinodal decomposition of alloys is described. Lattice vibration mode [110]TA 1 in various noble metal bcc-based alloys was measured. An analysis of the (110) interplanar force constants revealed a relation between the force constants and the martensite phase at low temperatures. Time resolved experiments of spinodal decomposition of MnCu were carried out to investigate how the separated (decomposed) phase grows in time. In the late regime of the decomposition, the size of the precipitate increased with a power law oft 0.37 while the crystallite grew as t 0.236 . (author)

  9. Two phase titanium aluminide alloy

    Energy Technology Data Exchange (ETDEWEB)

    Deevi, Seetharama C. (Midlothian, VA); Liu, C. T. (Oak Ridge, TN)

    2001-01-01

    A two-phase titanic aluminide alloy having a lamellar microstructure with little intercolony structures. The alloy can include fine particles such as boride particles at colony boundaries and/or grain boundary equiaxed structures. The alloy can include alloying additions such as .ltoreq.10 at % W, Nb and/or Mo. The alloy can be free of Cr, V, Mn, Cu and/or Ni and can include, in atomic %, 45 to 55% Ti, 40 to 50% Al, 1 to 5% Nb, 0.3 to 2% W, up to 1% Mo and 0.1 to 0.3% B. In weight %, the alloy can include 57 to 60% Ti, 30 to 32% Al, 4 to 9% Nb, up to 2% Mo, 2 to 8% W and 0.02 to 0.08% B.

  10. Rapid and nondestructive measurement of labile Mn, Cu, Zn, Pb and As in DGT by using field portable-XRF.

    Science.gov (United States)

    Chen, Zheng; Williams, Paul N; Zhang, Hao

    2013-09-01

    The technique of diffusive gradients in thin films (DGT) is often employed to quantify labile metals in situ; however, it is a challenge to perform the measurements in-field. This study evaluated the capability of field-portable X-ray fluorescence (FP-XRF) to swiftly generate elemental speciation information with DGT. Biologically available metal ions in environmental samples passively preconcentrate in the thin films of DGT devices, providing an ideal and uniform matrix for XRF nondestructive detection. Strong correlation coefficients (r > 0.992 for Mn, Cu, Zn, Pb and As) were obtained for all elements during calibration. The limits of quantitation (LOQ) for the investigated elements of FP-XRF on DGT devices are 2.74 for Mn, 4.89 for Cu, 2.89 for Zn, 2.55 for Pb, and 0.48 for As (unit: μg cm(-2)). When Pb and As co-existed in the solution trials, As did not interfere with Pb detection when using Chelex-DGT. However, there was a significant enhancement of the Pb reading attributed to As when ferrihydrite binding gels were tested, consistent with Fe-oxyhydroxide surfaces absorbing large quantities of As. This study demonstrates the value of the FP-XRF technique to rapidly and nondestructively detect the metals accumulated in DGT devices, providing a new and simple diagnostic tool for on-site environmental monitoring of labile metals/metalloids.

  11. A-site-ordered perovskite MnCu3V4O12 with a 12-coordinated manganese(II).

    Science.gov (United States)

    Akizuki, Yasuhide; Yamada, Ikuya; Fujita, Koji; Nishiyama, Norimasa; Irifune, Tetuo; Yajima, Takeshi; Kageyama, Hiroshi; Tanaka, Katsuhisa

    2013-10-07

    A novel cubic perovskite MnCu3V4O12 has been synthesized at a high pressure and high temperature of 12 GPa and 1373 K. This compound crystallizes in the A-site-ordered perovskite structure (space group Im3) with lattice constant a = 7.26684(10) Å at room temperature. The most notable feature of this compound lies in the fact that the Mn(2+) ion is surrounded by 12 equidistant oxide ions to form a regular icosahedron; the situation of Mn(2+) is unprecedented for the crystal chemistry of an oxide. An anomalously large atomic displacement parameter U(iso)= 0.0222(8) Å(2) is found for Mn(2+) at room temperature, indicating that the thermal oscillation of the small Mn(2+) ion in a large icosahedron is fairly active. Magnetic susceptibility and electric resistivity measurements reveal that 3d electrons of Mn(2+) ions are mainly localized, while 3d electrons in Cu(2+) and V(4+) ions are delocalized and contribute to the metallic conduction.

  12. Microporous Ni@NiO nanoparticles prepared by chemically dealloying Al{sub 3}Ni{sub 2}@Al nanoparticles as a high microwave absorption material

    Energy Technology Data Exchange (ETDEWEB)

    Pang, Yu; Xie, Xiubo; Li, Da [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, No.37 Xueyuan Road, Beijing 100191 (China); Chou, Wusheng [School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China); Liu, Tong, E-mail: tongliu@buaa.edu.cn [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, No.37 Xueyuan Road, Beijing 100191 (China)

    2017-03-15

    The Al{sub 3}Ni{sub 2}@Al nanoparticles (NPs) were prepared from Ni{sub 45}Al{sub 55} master alloy by hydrogen plasma-metal reaction method, and were subsequently dealloyed to produce porous Ni@NiO NPs of 36 nm. The pore size ranges from 0.7 to 1.6 nm, leading to large specific surface area of 69.5 m{sup 2}/g and big pore volume of 0.507 cc/g. The saturation magnetization (M{sub S}) and coercivity (H{sub C}) of the microporous Ni@NiO NPs are 11.5 emu/g and 5.2 Oe. They exhibit high microwave absorption performance with a minimum reflection coefficient (RC) of −86.9 dB and an absorption bandwidth of 2.6 GHz (RC≤−10 dB) at thickness of 4.5 mm. The enhanced microwave absorption properties are attributed to the synergistic effect of the magnetic Ni core and dielectric NiO shell, and the micropore architecture. The NPs with micropore morphology and core/shell structure open a new way to modify the microwave absorption performance. - Graphical abstract: The microporous Ni/NiO nanoparticles prepared by chemically dealloying Al{sub 3}Ni{sub 2}@Al NPs exhibit high microwave absorption intensity (−86.9 dB) and wide absorption bandwidth (2.6 GHz for RC≤−10 dB). - Highlights: • Microporous Ni/NiO nanoparticals were prepared by chemically dealloying method. • They possessed micropores of 0.7–1.6 nm with a surface area of 69.5 m{sup 2}/g. • They showed high microwave absorption intensity and wide absorption bandwidth. • Microwave absorption mechanism was explained by micropore and core/shell structures.

  13. Evolution of corrosion of MnCuP weathering steel submitted to wet/dry cyclic tests in a simulated coastal atmosphere

    International Nuclear Information System (INIS)

    Hao Long; Zhang Sixun; Dong Junhua; Ke Wei

    2012-01-01

    Highlights: ► The evolution of rust on MnCuP weathering steel submitted to a simulated coastal atmosphere has been investigated. ► The corrosion evolution of MnCuP weathering steel can be divided into two stages with distinct rust properties. ► A protective rust layer with higher amounts of α-FeOOH and lower Fe 3 O 4 forms as the corrosion proceeds. ► The rust initially enhances and then stabilizes the cathodic process, but the anodic process tends to be inhibited. - Abstract: The evolution of rust on MnCuP weathering steel submitted to a simulated coastal atmosphere was investigated by corrosion weight gain, scanning electron microscopy, X-ray diffraction, and electrochemical methods. The results indicate that the higher corrosion rate during the first stage than that during the second stage is related closely to the rust composition and electrochemical properties. The corrosion rate evolution is caused by the formation of a protective rust layer with a higher relative amount of α-FeOOH. The rust initially enhances and then stabilizes the cathodic process, but the anodic process tends to be inhibited by the protective rust layer.

  14. Influences of ultrasonic irradiation on the morphology and structure of nanoporous Co nanoparticles during chemical dealloying

    Directory of Open Access Journals (Sweden)

    Hui Li

    2016-12-01

    Full Text Available The Co-61.8 wt% Al nanoparticles of 45 nm were prepared by hydrogen plasma-metal reaction (HPMR method. The nanoparticles display core shell structure with Al13Co4 and CoAl core and aluminum oxide shell (about 2 nm. Under ultrasonic irradiation, nanoporous fcc-Co nanoparticles were produced successfully by chemically dealloying the Co-Al nanoparticles at room temperature, whereas, without ultrasonic irradiation CoAl phase could hardly react with sodium hydroxide solution. At 323 K the Co-Al nanoparticles could be dealloyed to fcc-Co and hcp-Co phases even without ultrasonic irradiation. The surface area of the dealloyed nanoparticles under ultrasonic irradiation was larger than that of the dealloyed sample without ultrasonic irradiation at the same temperature. It is believed that the microjet and shock-wave induced by ultrasonic irradiation give rise to particles size reduction, interparticle collision and surface cleaning, and accelerate the dealloying process and the phase transformation.

  15. Silicon induced Fe deficiency affects Fe, Mn, Cu and Zn distribution in rice (Oryza sativa L.) growth in calcareous conditions.

    Science.gov (United States)

    Carrasco-Gil, Sandra; Rodríguez-Menéndez, Sara; Fernández, Beatriz; Pereiro, Rosario; de la Fuente, Vicenta; Hernandez-Apaolaza, Lourdes

    2018-02-01

    A protective effect by silicon in the amelioration of iron chlorosis has recently been proved for Strategy 1 species, at acidic pH. However in calcareous conditions, the Si effect on Fe acquisition and distribution is still unknown. In this work, the effect of Si on Fe, Mn, Cu and Zn distribution was studied in rice (Strategy 2 species) under Fe sufficiency and deficiency. Plants (+Si or-Si) were grown initially with Fe, and then Fe was removed from the nutrient solution. The plants were then analysed using a combined approach including LA-ICP-MS images for each element of interest, the analysis of the Fe and Si concentration at different cell layers of root and leaf cross sections by SEM-EDX, and determining the apoplastic Fe, total micronutrient concentration and oxidative stress indexes. A different Si effect was observed depending on plant Fe status. Under Fe sufficiency, Si supply increased Fe root plaque formation, decreasing Fe concentration inside the root and increasing the oxidative stress in the plants. Therefore, Fe acquisition strategies were activated, and Fe translocation rate to the aerial parts was increased, even under an optimal Fe supply. Under Fe deficiency, +Si plants absorbed Fe from the plaque more rapidly than -Si plants, due to the previous activation of Fe deficiency strategies during the growing period (+Fe + Si). Higher Fe plaque formation due to Si supply during the growing period reduced Fe uptake and could activate Fe deficiency strategies in rice, making it more efficient against Fe chlorosis alterations. Silicon influenced Mn and Cu distribution in root. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

  16. Formation of substrate-based gold nanocage chains through dealloying with nitric acid

    Directory of Open Access Journals (Sweden)

    Ziren Yan

    2015-06-01

    Full Text Available Metal nanocages have raised great interest because of their new properties and wide applications. Here, we report on the use of galvanic replacement reactions to synthesize substrate-supported Ag–Au nanocages from silver templates electrodeposited on transparent indium tin oxide (ITO film coated glass. The residual Ag in the composition was dealloyed with 10% nitric acid. It was found that chains of Au nanocages were formed on the substrate surface during dealloying. When the concentration of HNO3 increased to 20%, the structures of nanocages were damaged and formed crescent or semi-circular shapes. The transfer process on the substrate surface was discussed.

  17. Associations between standardized school performance tests and mixtures of Pb, Zn, Cd, Ni, Mn, Cu, Cr, Co, and V in community soils of New Orleans

    International Nuclear Information System (INIS)

    Zahran, Sammy; Mielke, Howard W.; Weiler, Stephan; Hempel, Lynn; Berry, Kenneth J.; Gonzales, Christopher R.

    2012-01-01

    In New Orleans a strong inverse association was previously identified between community soil lead and 4th grade school performance. This study extends the association to zinc, cadmium, nickel, manganese, copper, chromium, cobalt, and vanadium in community soil and their comparative effects on 4th grade school performance. Adjusting for poverty, food security, racial composition, and teacher-student ratios, regression results show that soil metals variously reduce and compress student scores. Soil metals account for 22%–24% while food insecurity accounts for 29%–37% of variation in school performance. The impact on grade point averages were Ni > Co > Mn > Cu ∼Cr ∼ Cd > Zn > Pb, but metals are mixtures in soils. The quantities of soil metal mixtures vary widely across the city with the largest totals in the inner city and smallest totals in the outer city. School grade point averages are lowest where the soil metal mixtures and food insecurity are highest. - Highlights: ► Mixtures of metals vary; largest totals in the inner city and lowest in the outer city. ► An inverse association between soil Pb and 4th grade school performance is known. ► Assuming the same exposure pathway, multiple metals are compared to performance. ► Soil metals account for 22%–24% of variation in school test performance. ► Soil metal plus food insecurity accounts for 54% of explained variance. - Controlling for potential confounding variables, the accumulation of metals (Pb, Zn, Cd, Ni, Mn, Cu, Cr, and Co) in neighborhood soils is significantly negatively associated with 4th grade school performance on standardized tests in New Orleans.

  18. Morphology and Activity Tuning of Cu 3 Pt/C Ordered Intermetallic Nanoparticles by Selective Electrochemical Dealloying

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Deli; Yu, Yingchao; Zhu, Jing; Liu, Sufen; Muller, David A.; Abruña, Héctor D.

    2015-02-11

    Improving the catalytic activity of Pt-based bimetallic nanoparticles is a key challenge in the application of proton-exchange membrane fuel cells. Electrochemical dealloying represents a powerful approach for tuning the surface structure and morphology of these catalyst nanoparticles. We present a comprehensive study of using electrochemical dealloying methods to control the morphology of ordered Cu3Pt/C intermetallic nanoparticles, which could dramatically affect their electrocatalytic activity for the oxygen reduction reaction (ORR). Depending on the electrochemical dealloying conditions, the nanoparticles with Pt-rich core–shell or porous structures were formed. We further demonstrate that the core–shell and porous morphologies can be combined to achieve the highest ORR activity. This strategy provides new guidelines for optimizing nanoparticles synthesis and improving electrocatalytic activity.

  19. Mineralogy and Genesis of the Polymetallic and Polyphased Low Grade Fe-Mn-Cu Ore of Jbel Rhals Deposit (Eastern High Atlas, Morocco

    Directory of Open Access Journals (Sweden)

    Michèle Verhaert

    2018-01-01

    Full Text Available The Jbel Rhals deposit, located in the Oriental High Atlas of Morocco, hosts a polymetallic Fe-Mn-Cu ore. Large metric veins of goethite and pyrolusite cut through Paleozoic schists that are overlaid by Permian-Triassic basalts and Triassic conglomerates. The genesis of this deposit is clearly polyphased, resulting from supergene processes superimposed over hydrothermal phases. The flow of Permian-Triassic basalts probably generated the circulation of hydrothermal fluids through the sedimentary series, the alteration of basalts and schists, and the formation of hydrothermal primary ore composed of carbonates (siderite and Cu-Fe sulfides. Several episodes of uplift triggered the exhumation of ores and host rocks, generating their weathering and the precipitation of a supergene ore assemblage (goethite, pyrolusite, malachite and calcite. In the Paleozoic basement, Fe-Mn oxihydroxides are mostly observed as rhombohedral crystals that correspond to the pseudomorphose of a primary mineral thought to be siderite; goethite precipitated first, rapidly followed by pyrolusite and other Mn oxides. Malachite formed later, with calcite, in fine millimetric veins cutting through host-rock schists, conglomerates and Fe-Mn ores.

  20. Health Risk Assessment of Fe, Mn, Cu, Cr in Drinking Water in some Wells and Springs of Shush and Andimeshk, Khuzestan Province, Southern Iran

    Directory of Open Access Journals (Sweden)

    Mohamad Sakizadeh

    2016-02-01

    Full Text Available Background: In the current study,the hazard quotient, the hazard index (HI and spatial variations of Fe,Mn,Cu and Cr in drinking water sources of Andimesk-Shush, Khuzestan Province, Southern Iranaquifer were assessed. Methods: We compared theconcentrations of aforementioned heavy metals in wells and springs inAndimeshk and Shush regions. The non-carcinogenic risk assessment of heavy metals was implemented usingUnited States Environmental Protection Agency (USEPA index.The spatial maps in the area were developed by geostatistical methods. Results: Mean concentrations of heavy metals in groundwater sources of the study area in decreasing order was as follows: Cu >Mn> Fe> Cr. Except for iron,mean heavy metal concentrations were higher than the standard levels. Manganese concentration in 41.5% of the samples exceeded the permissible limits. Copper was higher than the safety limit in 74% of the samples, and chromium in 54% of the cases. The spatial pattern of heavy metals concentrations indicated higher concentrations in the southern parts of the region. The mean hazard quotients of most samples for the four heavy metals were lower than one, indicating that there was no immediate threat due to the exposure to these heavy metals. The calculated accumulated hazards of these heavy metals produced different results, with hazard indices of higher than one. Conclusion: The accumulated hazard indicesfor the evaluated metals were higher than one, indicating that chronic ingestion of these waters threatens the health of local consumers on the long run.

  1. Synthesis of nanoporous CuO/TiO2/Pd-NiO composite catalysts by chemical dealloying and their performance for methanol and ethanol electro-oxidation

    Science.gov (United States)

    Niu, Mengying; Xu, Wence; Zhu, Shengli; Liang, Yanqin; Cui, Zhenduo; Yang, Xianjin; Inoue, Akihisa

    2017-09-01

    Nanoporous CuO/TiO2/Pd-NiO-x (x = 0, 1, 3, 5, 7 at%) catalysts have been synthesized by dealloying Cu-Ti-Pd-Ni alloy ribbons in acid solution. The nanoporous structure and chemical composition of the catalysts distribute uniformly. Based on the electrochemical active area (EASA), electrocatalytic activity and stability, the np-CuO/TiO2/Pd-NiO-3 catalyst possesses the best performance for methanol and ethanol electro-oxidation. For methanol and ethanol electro-oxidation, the anodic current densities in forward scan of the np-CuO/TiO2/Pd-NiO-3 catalyst are about 5.6 times and 2.1 times larger than that of the np-CuO/TiO2/Pd catalyst, respectively. The introduction of NiO provides more electrochemical active sites due to the improved geometrical and bifunctional mechanism. NiO promotes the adsorption of oxygen-containing species (OHads) on the catalyst surface, and electron effect between Pd and Ni is favorable for charge transfer. This accelerates the removal of intermediate products during the oxidation process. The electrocatalytic processes of methanol and ethanol oxidation in alkaline solution are controlled by both charge transfer and diffusion.

  2. Preparation of PtSnCu/C and PtSn/C electrocatalysts and activation by dealloying processes for ethanol electrooxidation

    International Nuclear Information System (INIS)

    Crisafulli, Rudy

    2013-01-01

    PtSnCu/C (with different Pt:Sn:Cu atomic ratios) and PtSn/C (50:50) electrocatalysts were prepared by borohydride (BR) and alcohol-reduction (AR) processes using H 2 PtCl 6 .6H 2 O, SnCl 2 .2H 2 O and CuCl 2 .2H 2 O as metal sources, NaBH 4 and ethylene glycol as reducing agents, 2-propanol and ethylene glycol/water as solvents and carbon black as support. In a further step, these electrocatalysts were activated by chemical (CD) and electrochemical (ED) dealloying processes through acid treatment and thin porous coating technique, respectively. These materials were characterized by energy dispersive X-ray, Xray diffraction, transmission electron microscopy, line scan energy dispersive Xray and cyclic voltammetry. Electrochemical studies for ethanol electro-oxidation were performed by cyclic voltammetry, chronoamperometry and in single Direct Ethanol Fuel Cell using Membrane Electrode Assembly (MEA). The anodic effluents were analysed by gas chromatography. The X-ray diffractograms of the as-synthesized electrocatalysts showed the typical face-centered cubic structure (FCC) of platinum and its alloys. After dealloying, the X-ray diffractograms showed that the Pt FCC structure was preserved. The crystallite sizes of the assynthesized electrocatalysts were in the range of PtSnCu/C (50:40:10) AR/ED > PtSnCu/C (50:10:40) BR/CD. PtSn/C (50:50) BR/CD, PtSnCu/C (50:10:40) BR/CD, PtSnCu/C (50:40:10) AR/CD electrocatalysts and Pt/C BASF, PtSn/C (75:25) BASF commercial electrocatalysts were tested in single Direct Ethanol Fuel Cell. The results showed the following performance for ethanol electro-oxidation: PtSn/C (50:50) BR/CD > PtSnCu/C (50:40:10) AR/CD > PtSnCu/C > PtSn/C (75:25) BASF > PtSnCu/C (50:10:40) BR/CD > Pt/C BASF. (author)

  3. Lattice-Strain Control of the Activity in Dealloyed Core-Shell Fuel Cell Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Strasser, P. [Berlin Institute of Technology (Technische Universitat Berlin); Koh, Shirlaine [University of Houston, Houston; Anniyev, Toyli [SLAC National Accelerator Laboratory; Greeley, Jeff [Argonne National Laboratory (ANL); More, Karren Leslie [ORNL; Yu, Chengfei [University of Houston, Houston; Liu, Zengcai [University of Houston, Houston; Kaya, Sarpa [SLAC National Accelerator Laboratory; Nordlund, Dennis [SLAC National Accelerator Laboratory; Ogasawara, Hirohito [SLAC National Accelerator Laboratory; Toney, Michael F. [SLAC National Accelerator Laboratory; Anders, Nilsson [SLAC National Accelerator Laboratory

    2010-01-01

    Electrocatalysis will play a key role in future energy conversion and storage technologies, such as water electrolysers, fuel cells and metal-air batteries. Molecular interactions between chemical reactants and the catalytic surface control the activity and efficiency, and hence need to be optimized; however, generalized experimental strategies to do so are scarce. Here we show how lattice strain can be used experimentally to tune the catalytic activity of dealloyed bimetallic nanoparticles for the oxygen-reduction reaction, a key barrier to the application of fuel cells and metal-air batteries. We demonstrate the core-shell structure of the catalyst and clarify the mechanistic origin of its activity. The platinum-rich shell exhibits compressive strain, which results in a shift of the electronic band structure of platinum and weakening chemisorption of oxygenated species. We combine synthesis, measurements and an understanding of strain from theory to generate a reactivity-strain relationship that provides guidelines for tuning electrocatalytic activity.

  4. Lattice-Strain Control of the Activity in Dealloyed Core-Shell Fuel Cell Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Strasser, Peter; Shirlaine, Koh; Anniyev, Toyli; Greeley, Jeffrey P.; More, Karren L.; Yu, Chengfei; Liu, Zengcai; Kaya, Sarp; Nordlund, Dennis; Ogasawara, Hirohito; Toney, Michael F.; Nilsson, Anders R.

    2010-04-30

    Electrocatalysis will play a key role in future energy conversion and storage technologies, such as water electrolysers, fuel cells and metal–air batteries. Molecular interactions between chemical reactants and the catalytic surface control the activity and efficiency, and hence need to be optimized; however, generalized experimental strategies to do so are scarce. Here we show how lattice strain can be used experimentally to tune the catalytic activity of dealloyed bimetallic nanoparticles for the oxygen-reduction reaction, a key barrier to the application of fuel cells and metal–air batteries. We demonstrate the core–shell structure of the catalyst and clarify the mechanistic origin of its activity. The platinum-rich shell exhibits compressive strain, which results in a shift of the electronic band structure of platinum and weakening chemisorption of oxygenated species. We combine synthesis, measurements and an understanding of strain from theory to generate a reactivity–strain relationship that provides guidelines for tuning electrocatalytic activity.

  5. Nanoporous Gold Films Prepared by a Combination of Sputtering and Dealloying for Trace Detection of Benzo[a]pyrene Based on Surface Plasmon Resonance Spectroscopy

    Directory of Open Access Journals (Sweden)

    Li Wang

    2017-06-01

    Full Text Available A wavelength-interrogated surface plasmon resonance (SPR sensor based on a nanoporous gold (NPG film has been fabricated for the sensitive detection of trace quantities of benzo[a]pyrene (BaP in water. The large-area uniform NPG film was prepared by a two-step process that includes sputtering deposition of a 60-nm-thick AuAg alloy film on a glass substrate and chemical dealloying of the alloy film in nitric acid. For SPR sensor applications, the NPG film plays the dual roles of analyte enrichment and supporting surface plasmon waves, which leads to sensitivity enhancement. In this work, the as-prepared NPG film was first modified with 1-dodecanethiol molecules to make the film hydrophobic so as to improve BaP enrichment from water via hydrophobic interactions. The SPR sensor with the hydrophobic NPG film enables one to detect BaP at concentrations as low as 1 nmol·L−1. In response to this concentration of BaP the sensor produced a resonance-wavelength shift of ΔλR = 2.22 nm. After the NPG film was functionalized with mouse monoclonal IgG1 that is the antibody against BaP, the sensor’s sensitivity was further improved and the BaP detection limit decreased further down to 5 pmol·L−1 (the corresponding ΔλR = 1.77 nm. In contrast, the conventional SPR sensor with an antibody-functionalized dense gold film can give a response of merely ΔλR = 0.9 nm for 100 pmol·L−1 BaP.

  6. Explosive device of conduit using Ti Ni alloy

    Directory of Open Access Journals (Sweden)

    A. Yu. Kolobov

    2014-01-01

    Full Text Available Presently, materials have been developed which are capable at changing temperate to return significant inelastic deformations, exhibit rubber-like elasticity, convert heat into mechanical work, etc. The aggregate of these effects is usually called the shape memory effect.At present a great number of compounds and alloys with a shape memory effect has been known.These are alloys based on titanium nickelide (TiNi, copper-based alloys (Cu-Al, Cu-Sn, Cu-Al-Ni, Cu-Zn-Si, etc., gold and silver (Ag-Cd, Au-Ag-Cd, Au-Cd-Cu, Au-Zn-Cu, etc., manganese (Mn-Cr, Fe-Cu, Mn-Cu-Ni, Mn-Cu-Zr, Mn-Ni, etc., iron (Fe-Mn, Fe-Ni, Fe-Al, etc., and other compounds.The alloys based on titanium nickelide (nitinol are the most widely used.Alloys with shape memory effect find various applications in engineering and medicine, namely connecting devices, actuators, transformable design, multipurpose medical implants, etc.There is a task of breaking fuel conduit during separating the spacecraft from the rocket in space technology.The paper examines the procedure for design calculation of the separating device of conduit with the use of Ti-Ni alloy. This device can be used instead of the pyro-knives.The device contains two semi-rings from Ti-Ni alloy. In the place of break on the conduit an annular radius groove is made.At a temperature of martensite passage the semi-rings undergo deformation and in the strained state are set in the device. With heating to the temperature of the austenitic passage of bushing macro-deformation the energy stored by the nitinol bushing is great enough to break the conduit on the neck.The procedures of design calculation and response time of device are given.

  7. A facile one-pot oxidation-assisted dealloying protocol to massively synthesize monolithic core-shell architectured nanoporous copper@cuprous oxide nanonetworks for photodegradation of methyl orange

    Science.gov (United States)

    Liu, Wenbo; Chen, Long; Dong, Xin; Yan, Jiazhen; Li, Ning; Shi, Sanqiang; Zhang, Shichao

    2016-11-01

    In this report, a facile and effective one-pot oxidation-assisted dealloying protocol has been developed to massively synthesize monolithic core-shell architectured nanoporous copper@cuprous oxide nanonetworks (C-S NPC@Cu2O NNs) by chemical dealloying of melt-spun Al 37 at.% Cu alloy in an oxygen-rich alkaline solution at room temperature, which possesses superior photocatalytic activity towards photodegradation of methyl orange (MO). The experimental results show that the as-prepared nanocomposite exhibits an open, bicontinuous interpenetrating ligament-pore structure with length scales of 20 ± 5 nm, in which the ligaments comprising Cu and Cu2O are typical of core-shell architecture with uniform shell thickness of ca. 3.5 nm. The photodegradation experiments of C-S NPC@Cu2O NNs show their superior photocatalytic activities for the MO degradation under visible light irradiation with degradation rate as high as 6.67 mg min-1 gcat-1, which is a diffusion-controlled kinetic process in essence in light of the good linear correlation between photodegradation ratio and square root of irradiation time. The excellent photocatalytic activity can be ascribed to the synergistic effects between unique core-shell architecture and 3D nanoporous network with high specific surface area and fast mass transfer channel, indicating that the C-S NPC@Cu2O NNs will be a promising candidate for photocatalysts of MO degradation.

  8. Synthesis, characterization and optimization of platinum-alloy nanoparticle catalysts in proton exchange membrane fuel cells

    Science.gov (United States)

    Srivastava, Ratndeep

    Renewable hydrogen-fuelled proton exchange membrane (PEMFC) fuel cells have consistently demonstrated great promise as a future source of energy due to their high conversion efficiency, lower temperature of operation and lack of greenhouse emissions. One of the major impediments in the commercialization of polymer electrolyte membrane fuel cells is the insufficient catalytic reactivity and higher cost of Pt electrocatalysts which are utilized for the electroreduction of oxygen from air. This dissertation focuses primarily on a family of Pt alloy fuel cell electrocatalysts referred to as de-alloyed core-shell electrocatalysts. These materials are bimetallic or multimetallic nanoparticles, mostly supported on conductive supports which were first described in a dissertation by Dr. S. Koh earlier in 2009.1 De-alloyed Pt nanoparticle electrocatalysts are formed from base metal rich binary Pt-M and ternary Pt-M1-M 2 (M, M1, M2 = Cu, Co, Ni, Fe and Cr) alloy nanoparticle precursors. The precursors are transformed and activated by electrochemical selective dissolution of the less noble metal component of the precursors (de-alloying). They have shown exceptional activity for oxygen reduction reaction (ORR) in idealized electrochemical half cell measurements, in particular rotating disk electrode experiments. However, these materials were never tested or implemented in realistic Membrane Electrode Assemblies (MEA) and single PEM fuel cells. The objective of this work was to implement de-alloyed Pt particle catalysts in realistic fuel cell electrode layers as well as a detailed characterization of their behavior and stability. The major challenges of MEA implementation consists of the behavior of the new nanostructured electrocatalysts inside the complex three-phase interface of polymer membrane ionomer, liquid water, metal catalyst, support, and reactant gas. Activity measurements were followed by medium and long-term durability analysis by potential cycling of the membrane

  9. Monolithic Au/CeO2 nanorod framework catalyst prepared by dealloying for low-temperature CO oxidation

    Science.gov (United States)

    Zhang, Xiaolong; Duan, Dong; Li, Guijing; Feng, Wenjie; Yang, Sen; Sun, Zhanbo

    2018-03-01

    Monolithic Au/CeO2 nanorod frameworks (NFs) with porous structure were prepared by dealloying melt-spun Al89.7Ce10Au0.3 ribbons. After calcination in O2, a 3D Au/CeO2 NF catalyst with large surface area was obtained and used for low-temperature CO oxidation. The small Au clusters/nanoparticles (NPs) were in situ supported and highly dispersed on the nanorod surface, creating many nanoscale contact interfaces. XPS results demonstrated that high-concentration oxygen vacancy and Au δ+/Au0 co-existed in the calcined sample. The Au/CeO2 nanorod catalyst calcined at 400 °C exhibited much higher catalytic activity for CO oxidation compared with the dealloyed sample and bare CeO2 nanorods. Moreover, its complete reaction temperature was as low as 91 °C. The designed Au/CeO2 NF catalyst not only possessed extreme sintering resistance but also exhibited high performance owing to the enhanced interaction between the Au clusters/NPs and CeO2 nanorod during calcination.

  10. Direct observation of the dealloying process of a platinum–yttrium nanoparticle fuel cell cathode and its oxygenated species during the oxygen reduction reaction

    DEFF Research Database (Denmark)

    Malacrida, Paolo; Sanchez Casalongue, Hernan G.; Masini, Federico

    2015-01-01

    Size-selected 9 nm PtxY nanoparticles have recently shown an outstanding catalytic activity for the oxygen reduction reaction, representing a promising cathode catalyst for proton exchange membrane fuel cells (PEMFCs). Studying their electrochemical dealloying is a fundamental step towards the nd...

  11. A comparative study of enhanced electrochemical stability of tin–nickel alloy anode for high-performance lithium ion battery

    International Nuclear Information System (INIS)

    Guan, Dongsheng; Li, Jianyang; Gao, Xianfeng; Yuan, Chris

    2014-01-01

    Highlights: • Sn and Sn–Ni alloy nanoparticles are synthesized by chemical co-precipitation method. • Sn–Ni alloy particles show different phase structure and morphology from Sn particles. • Cyclic voltammetry reveals distinct redox reaction behaviors at Sn and alloy anodes. • Impedance analyses show better stability of alloy electrodes over prolonged cycling. - Abstract: Sn and Sn–Ni alloy nanoparticles are synthesized readily by co-precipitation method for their applications in Li-ion batteries. It is found that nickel not only affects the phase structure and morphology of the alloy, but also impacts Li–Sn alloying and dealloying behaviors. In Li-ion batteries, the alloy electrodes deliver stronger cycling stability than the pure Sn anode. In tests the former exhibits a final capacity of 228.5 mA h g −1 over 50 cycles, while the latter displays 14.3 mA h g −1 . Smaller current for battery cycles increases capacities of the alloys beyond 408.4 mA h g −1 . The mechanism of enhanced stability of Sn–Ni alloys is examined. Redox reaction characteristics and Li-ion transfer kinetics at these anodes after different cycles are investigated by cyclic voltammetry and electrochemical impedance spectroscopy, which are considered to associate with buffering effects of nickel and structural integrity of electrodes. Li–Sn alloying and dealloying reactions cause volume changes and induce stress that releases in the formation of tiny cracks within the particles. The cracks accelerate side reactions and decelerate charge transport, detrimental to the electrode stability. Nickel cushions the volume variations and reduces the stress and cracks at Sn–Ni alloy anodes to allow them to maintain better electrode integrity and smaller charge resistance, thus yielding their improved Li-ion intercalation stability during long-term cycling

  12. Evaluation of the performance degradation at PAFC investigation of dealloying process of electrocatalysts with in-situ XRD

    Energy Technology Data Exchange (ETDEWEB)

    Nakajima, Noriyuki; Uchida, Hiroyuki; Watanabe, Masahiro [Yamanashi Univ., Kofu (Japan)] [and others

    1996-12-31

    As a complementary research project to the demonstration project of 5MW and 1 MW PAFC plants, the mechanism and rate of deterioration of the cells and stacks have been studied from 1995 FY, with the objective of establishing an estimation method for the service life-time of the cell stacks. This work has been performed in the Basic Research Project, as part of that project on PAFC`s, selecting four subjects (Electrocatalysts degradation, Electrolyte fill-level, Cell material corrosion, Electrolyte loss) as the essential factors relating to the life-time. In this study, the effect of temperature and potential on the dealloying process of electrocatalysts was examined in H{sub 3}PO{sub 4} electrolyte with X-ray diffraction measurement.

  13. Potentiodynamic polarization study of the corrosion behavior of palladium-silver dental alloys.

    Science.gov (United States)

    Sun, Desheng; Brantley, William A; Frankel, Gerald S; Heshmati, Reza H; Johnston, William M

    2018-04-01

    Although palladium-silver alloys have been marketed for over 3 decades for metal-ceramic restorations, understanding of the corrosion behavior of current alloys is incomplete; this understanding is critical for evaluating biocompatibility and clinical performance. The purpose of this in vitro study was to characterize the corrosion behavior of 3 representative Pd-Ag alloys in simulated body fluid and oral environments and to compare them with a high-noble Au-Pd alloy. The study obtained values of important electrochemical corrosion parameters, with clinical relevance, for the rational selection of casting alloys. The room temperature in vitro corrosion characteristics of the 3 Pd-Ag alloys and the high-noble Au-Pd alloy were evaluated in 0.9% NaCl, 0.09% NaCl, and Fusayama solutions. After simulated porcelain firing heat treatment, 5 specimens of each alloy were immersed in the electrolytes for 24 hours. For each specimen, the open-circuit potential (OCP) was first recorded, and linear polarization was then performed from -20 mV to +20 mV (versus OCP) at a rate of 0.125 mV/s. Cyclic polarization was subsequently performed on 3 specimens of each alloy from -300 mV to +1000 mV and back to -300 mV (versus OCP) at a scanning rate of 1 mV/s. The differences in OCP and corrosion resistance parameters (zero-current potential and polarization resistance) among alloys and electrolyte combinations were compared with the 2-factor ANOVA (maximum-likelihood method) with post hoc Tukey adjustments (α=.05). The 24-hour OCPs and polarization resistance values of the 3 Pd-Ag alloys and the Au-Pd alloy were not significantly different (P=.233 and P=.211, respectively) for the same electrolyte, but significant differences were found for corrosion test results in different electrolytes (Palloy and electrolyte (P=.249 and P=.713, respectively). The 3 Pd-Ag silver alloys appeared to be resistant to chloride ion corrosion, and passivation and de-alloying were identified for these

  14. The effects of doping and shell thickness on the optical and magnetic properties of Mn/Cu/Fe-doped and Co-doped ZnS nanowires/ZnO quantum dots/SiO2 heterostructures

    Science.gov (United States)

    Cao, Jian; Yang, Jinghai; Yang, Lili; Wei, Maobin; Feng, Bo; Han, Donglai; Fan, Lin; Wang, Bingji; Fu, Hao

    2012-07-01

    In this paper, we demonstrated the encapsulation of Mn/Cu/Fe-doped and co-doped ZnS nanowires (NWs) and ZnO quantum dots (QDs) with a layer of mesoporous SiO2 shell for the purpose of integrating dual emission and ferromagnetism property into one common nanostructure at room temperature. Within the ZnS:Mn2+Cu2+Fe2+/ZnO@SiO2 nanocomposites, ZnS:Mn2+Cu2+Fe2+ NWs and ZnO QDs provided color-tunable visible emission and UV emission, respectively. The color-tunable visible emission in the ZnS:Mn2+Cu2+Fe2+ NWs can be obtained by adjusting the concentrations of Mn2+, Cu2+, and Fe2+ ions. The ferromagnetism of the ZnS:Mn2+Cu2+Fe2+ NWs was observed around room temperature, the mechanism of which was explained by the super-exchange mechanism. The results of the effect of the ZnO QDs shell thickness on the optical properties of the ZnS:Mn2+/ZnO@SiO2 nanocomposites showed that the luminescence intensity of the yellow-orange emission and UV emission reached the highest value when the ratio of ZnS:Mn2+/ZnO equaled 1:5.

  15. Structure, activity, and stability of platinum alloys as catalysts for the oxygen reduction reaction

    DEFF Research Database (Denmark)

    Vej-Hansen, Ulrik Grønbjerg

    In this thesis I present our work on theoretical modelling of platinum alloys as catalysts for the Oxygen Reduction Reaction (ORR). The losses associated with the kinetics of the ORR is the main bottleneck in low-temperature fuel cells for transport applications, and more active catalysts...... and dealloying due to kinetic barriers, despite the thermodynamic driving force for dissolution. This is followed by our results on trying to decouple the strain and ligand effects for platinum skin structures, and determining whether there is any correlation between adsorption energy and surface stability......), depending on the length and time scales involved. Using DFT, we show how diffusion barriers in transition metal alloys in the L12 structure depend on the alloying energy, supporting the assumption that an intrinsically more stable alloy is also more stable towards diffusion-related degradation...

  16. [UV-Vis studies on the course of reaction of Au/Ag alloy colloid with hydrogen tetrachloroaurate(III) hydrate].

    Science.gov (United States)

    Jin, Yi-Liang; Yao, Jian-Lin; Gu, Ren-Ao

    2009-10-01

    Using citrate as protector, Au-Ag alloy nanoparticles with different molar ratios were prepared with hydrazine as the reducer. One plasmon band between monometallic Ag and Au was observed in their UV-Vis spectra. And the peak of alloy shifted linearly with the ratio of Au changing in the alloy. By UV-Vis spectra, the course of reaction of the alloy colloid with HAuCl4 was studied. The result shows that the UV-Vis spectra of the alloy colloid changed regularly with the adding volume of HAuCl4 increasing. And there is a linear interval in it with the change in the calculated ratio of Au. With the former studies, the course can be attributed to the dealloy of Au/Ag alloy.

  17. Hierarchical nanoporous platinum-copper alloy for simultaneous electrochemical determination of ascorbic acid, dopamine, and uric acid

    International Nuclear Information System (INIS)

    Zhao, Dianyun; Fan, Dawei; Wang, Jinping; Xu, Caixia

    2015-01-01

    A hierarchical nanoporous PtCu alloy was fabricated by two-step dealloying of a PtCuAl precursor alloy followed by annealing. The new alloy possesses interconnected hierarchical network architecture with bimodal distributions of ligaments and pores. It exhibits high electrochemical activity towards the oxidation of ascorbic acid (AA), dopamine (DA), and uric acid (UA) at working potentials of 0.32, 0.47 and 0.61 V (vs. a mercury sulfate reference electrode), respectively. The new alloy was placed on a glassy carbon electrode and then displayed a wide linear response to AA, DA, and UA in the concentration ranges from 25 to 800 μM, 4 to 20 μM, and 10 to 70 μM, respectively. The lower detection limits are 17.5 μM, 2.8 µM and 5.7 μM at an S/N ratio of 3. (author)

  18. Development of Bioresorbable Fe-Mn Alloys for Orthopaedic Implantation

    Science.gov (United States)

    Heiden, Michael

    appears that microstructural refinement alone cannot achieve the necessary degradation rates required for these applications. The generation of porosity in these materials is shown to be controllable on several different size scales. Nanoporous structures generated through dealloying of Zn-diffused Fe-Mn alloys are shown to be tailorable based on the adjustments of parameters in processing, such as altering: initial microstructure, Zn diffusion rate, dealloying rate, temperature and time of heat treatment after dealloying, and the type of medium used. Certain dealloyed structures are shown to increase cell attachment by up to 123% compared to polished smooth surfaces, but corrosion resistance is slightly increased. Finally, the properties of NaCl-leached Fe-30Mn alloys and Fe-30Mn-10HA biocomposites are presented. The combination of introducing 300 microm diameter pores and the generation of a separate Ca2Mn7O 14 phase after sintering at 1200ºC for three hours is found to contribute to enhanced bone stem cell attachment and differentiation, along with increased bone mineralization and increased degradation rates up to 0.82 +/- 0.04 mm/year, compared to 0.02 +/- 0.00 mm/year for nonporous Fe30Mn. Compared to nonporous Fe-30Mn alloys which would theoretically degrade for periods longer than 38 years, these porous biocomposites should degrade within a more clinically acceptable 1.5 years. However, based on studies presented here, the mechanical properties of these unique materials need to be further optimized to be suitable for more load-bearing applications.

  19. Corrosion characteristics of Hastelloy N alloy after He+ ion irradiation

    International Nuclear Information System (INIS)

    Lin Jianbo; Yu Xiaohan; Li Aiguo; He Shangming; Cao Xingzhong; Wang Baoyi; Li Zhuoxin

    2014-01-01

    With the goal of understanding the invalidation problem of irradiated Hastelloy N alloy under the condition of intense irradiation and severe corrosion, the corrosion behavior of the alloy after He + ion irradiation was investigated in molten fluoride salt at 700 °C for 500 h. The virgin samples were irradiated by 4.5 MeV He + ions at room temperature. First, the virgin and irradiated samples were studied using positron annihilation lifetime spectroscopy (PALS) to analyze the influence of irradiation dose on the vacancies. The PALS results showed that He + ion irradiation changed the size and concentration of the vacancies which seriously affected the corrosion resistance of the alloy. Second, the corroded samples were analyzed using synchrotron radiation micro-focused X-ray fluorescence, which indicated that the corrosion was mainly due to the dealloying of alloying element Cr in the matrix. Results from weight-loss measurement showed that the corrosion generally correlated with the irradiation dose of the alloy. (author)

  20. Rapid synthesis of rutile TiO2 nano-flowers by dealloying Cu60Ti30Y10 metallic glasses

    Science.gov (United States)

    Wang, Ning; Pan, Ye; Wu, Shikai; Zhang, Enming; Dai, Weiji

    2018-01-01

    The 3D nanostructure rutile TiO2 photocatalyst was rapidly synthesized by dealloying method using Cu60Ti30Y10 amorphous ribbons as precursors. The preparation period was kept down to just 3 h, which is much shorter than those of the samples by dealloying Cu60Ti30Al10, Cu70Ti30 and Cu60Ti30Sn10. The synthesized sample was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). XRD and XPS reveal the successful synthesis of rutile TiO2. The SEM and TEM images show that the synthesized rutile TiO2 nano-material presents homogeneous distributed 3D nanoflowers structure, which is composed of large quantities of fine rice-like nanorods (40-150 nm in diameter and 100-250 nm in length). BET specific surface areas of the samples were investigated by N2 adsorption-desorption isotherms, the fabricated rutile TiO2 exhibits very high specific surface area (194.08 m2/g). The photocatalytic activities of the samples were evaluated by degrading rhodamine B (RhB) dye (10 mg/L) under the irradiation of both simulated visible light (λ > 420 nm) and ultraviolet (UV) light (λ = 365 nm). The results show that the photocatalytic activity of rutile TiO2 prepared by dealloying Cu60Ti30Y10 amorphous ribbons is higher than those of commercial rutile and the sample synthesized by dealloying Cu70Ti30 precursors. The advantages of both short preparation period and superior photocatalytic activity suggest that Cu60Ti30Y10 metallic glasses are really a kind of perfect titanium source for rapidly fabricating high efficient TiO2 nano-materials. In addition, the influence of chemical composition of the amorphous precursors on preparation period of the rutile TiO2 nano-material was investigated from the point of view of standard electrode potentials.

  1. Facile fabrication of nanoporous PdFe alloy for nonenzymatic electrochemical sensing of hydrogen peroxide and glucose

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jinping [Key Laboratory of Chemical Sensing and Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China); Wang, Zhihong [School of Basic Medical Sciences, Shandong University of Traditional Chinese Medicine, Jinan 250355 (China); Zhao, Dianyun [Key Laboratory of Chemical Sensing and Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China); Xu, Caixia, E-mail: chm_xucx@ujn.edu.cn [Key Laboratory of Chemical Sensing and Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China)

    2014-06-01

    Graphical abstract: Nanoporous PdFe alloy, characterized by open three-dimensional bicontinuous nanospongy architecture, was easily fabricated by selectively dealloying PdFeAl source alloys, which exhibits greatly enhanced sensing performance and structure stability towards H{sub 2}O{sub 2} and glucose compared with NP-Pd and Pd/C catalysts. - Highlights: • NP-PdFe alloy is fabricated by a simple dealloying method. • NP-PdFe possesses open three-dimensional bicontinuous spongy morphology. • NP-PdFe shows high electrochemical sensing activities towards H{sub 2}O{sub 2} and glucose. • NP-PdFe shows good long-term stability for H{sub 2}O{sub 2} and glucose detection. • NP-PdFe shows good reproducibility for H{sub 2}O{sub 2} and glucose detection. - Abstract: Nanoporous (NP) PdFe alloy is easily fabricated through one step mild dealloying of PdFeAl ternary source alloy in NaOH solution. Electron microscopy characterization demonstrates that selectively dissolving Al from PdFeAl alloy generates three-dimensional bicontinuous nanospongy architecture with the typical ligament size around 5 nm. Electrochemical measurements show that the NP-PdFe alloy exhibits the superior electrocatalytic activity and durability towards hydrogen peroxide (H{sub 2}O{sub 2}) detection compared with NP-Pd and commercial Pd/C catalysts. In addition, NP-PdFe performs high sensing performance towards H{sub 2}O{sub 2} in a wide linear range from 0.5 to 6 mM with a low detection limit of 2.1 μM. This nanoporous structure also can sensitively detect glucose over a wide concentration range (1–32 mM) with a low detection limit of 1.6 μM and high resistance against chloride ions. Along with these attractive features, the as-made NP-PdFe alloy also has a good anti-interference towards ascorbic acid, uric acid, and dopamine.

  2. Preparation, characterization and degradation mechanisms of PtCu alloy nanoparticles for automotive fuel cells

    Science.gov (United States)

    Marcu, A.; Toth, G.; Srivastava, R.; Strasser, P.

    2012-06-01

    Electrochemically dealloyed PtCu alloy nanoparticles successfully meet the automotive technology target of having four times higher Pt mass activity for the electroreduction of molecular oxygen compared to current state-of-the-art platinum catalysts [1]. However, the catalysts must also maintain their activity throughout the aggressive automotive drive-cycles in order to be implemented in fuel cells cars. Here, the durability of dealloyed PtCu catalysts was systematically evaluated under various voltage-cycles using a rotating ring disk electrode. The stability of the non-noble metal alloy component was proven at electrode potentials below 0.6 V. The platinum stability was evaluated at potentials up to 1.1 V to avoid carbon corrosion and then up to 1.2 V to be closer to the more aggressive cycles developed in startup/shutdown events of the fuel cells. The major known failure modes such as non-noble metal dissolution, platinum dissolution, and particle growth/agglomeration were monitored in order to understand closely the PtCu nanoparticles behavior under different potential cycles and to provide a degradation fingerprint.

  3. Preparation of three-dimensional nanoporous Si using dealloying by metallic melt and application as a lithium-ion rechargeable battery negative electrode

    Science.gov (United States)

    Wada, Takeshi; Yamada, Junpei; Kato, Hidemi

    2016-02-01

    Silicon is a promising material for negative electrode in Li-ion batteries because of high gravimetric capacity. A Si nanomaterial that can accommodate volume expansion accompanied by lithiation is needed for practical application in Li-ion batteries. We prepare three-dimensional nanoporous interconnected silicon material with controlled pore and ligament sizes by dealloying using an Mg-Si precursor and Bi melt. The Mg atoms in the precursor selectively dissolve into Bi, and the remaining Si atoms self-organize into a nanoporous structure with characteristic length ranging from several ten to hundred nanometer. The Li-ion battery electrodes made from nanoporous silicon exhibit higher capacities, increased cycle lives, and improved rate performances compared with those made from commercial Si nanoparticles. Measurements on the electrical resistivity and electrode thickness change by lithiation/delithiation suggest that the superior performance of nanoporous Si electrode originates from the following: (1) The nanoporous Si has much lower electrical resistivity compared with that of the nanoparticle Si owing to the n-type dopant incorporated during dealloying. (2) The nanoporous Si-based electrode has higher porosity owing to the presence of intra-particle pores, which can accommodate Si expansion up to higher levels of lithiation.

  4. Structural and magnetic study of nanostructured (Fe79Mn21)80Cu20 alloy synthesized by ball milling

    International Nuclear Information System (INIS)

    Mizrahi, M.; Cabrera, A.F.; Stewart, S.J.; Troiani, H.E.; Cotes, S.M.; Desimoni, J.

    2004-01-01

    We have obtained by high-energy ball milling of the powder elements, a nanostructured (Fe 79 Mn 21 ) 80 Cu 20 FCC with a grain size distribution of an average crystallite size of 8 nm. Moessbauer spectroscopy, AC-susceptibility and magnetization measurement results indicate that the FCC alloy displays two magnetic behaviors; a paramagnetic component that orders along over a wide temperature range below 220 K, and a minor antiferromagnetic fraction that is still ordered at room temperature. The average hyperfine field (B hf =5.2 T) and the isomer shift (δ=0.07 mm/s) values at T=23 K show that Fe atoms are in a FCC structure that includes Mn and Cu atoms. In addition, we verified that presence of Cu stabilizes the FCC-Fe(Mn,Cu) phase

  5. Alloy materials

    Energy Technology Data Exchange (ETDEWEB)

    Hans Thieme, Cornelis Leo (Westborough, MA); Thompson, Elliott D. (Coventry, RI); Fritzemeier, Leslie G. (Acton, MA); Cameron, Robert D. (Franklin, MA); Siegal, Edward J. (Malden, MA)

    2002-01-01

    An alloy that contains at least two metals and can be used as a substrate for a superconductor is disclosed. The alloy can contain an oxide former. The alloy can have a biaxial or cube texture. The substrate can be used in a multilayer superconductor, which can further include one or more buffer layers disposed between the substrate and the superconductor material. The alloys can be made a by process that involves first rolling the alloy then annealing the alloy. A relatively large volume percentage of the alloy can be formed of grains having a biaxial or cube texture.

  6. Nanoporous PtFe alloys as highly active and durable electrocatalysts for oxygen reduction reaction

    Science.gov (United States)

    Duan, Huimei; Hao, Qin; Xu, Caixia

    2014-12-01

    Nanoporous PtFe alloys with two different bimetallic ratios are fabricated by selectively dealloying PtFeAl ternary alloys, characterized by nanoscaled bicontinuous network skeleton with interconnected hollow channels extending in all three dimensions. The reactive components in PtFeAl ternary alloy were sequentially leached out in a highly controllable manner, generating nanoporous architecture with different bimetallic ratios and the typical ligament size as small as 5 nm. These nanoporous PtFe alloys exhibit much enhanced electrocatalytic activity for oxygen reduction reaction compared with the PtFe/C and Pt/C catalysts. The specific and mass activities for oxygen reduction follow the order of nanoporous Pt75Fe25 > nanoporous Pt55Fe45 > PtFe/C > Pt/C. In the absence of any catalyst support, the structure stability of nanoporous PtFe alloys is greatly enhanced with less loss of the electrochemical surface area and the oxygen reduction activity upon long-term potential scan tests compared with PtFe/C and Pt/C catalysts. The as-made nanoporous PtFe alloys thus hold great application potential as promising cathode electrocatalyst in proton exchange membrane fuel cells with the advantages of easy preparation along with superior oxygen reduction activity and durability.

  7. Nanoporous PdZr surface alloy as highly active non-platinum electrocatalyst toward oxygen reduction reaction with unique structure stability and methanol-tolerance

    Science.gov (United States)

    Duan, Huimei; Xu, Caixia

    2016-06-01

    Nanoporous (NP) PdZr alloy with controllable bimetallic ratio is successfully fabricated by a simple dealloying method. By leaching out the more reactive Al from PdZrAl precursor alloy, NP-PdZr alloy with smaller ligament size was generated, characterized by the nanoscaled interconnected network skeleton and hollow channels extending in all three dimensions. Upon voltammetric scan in acid solution, the dissolution of surface Zr atoms generates the highly active Pd-Zr surface alloy with a nearly pure Pd surface and Pd-Zr alloy core. The NP-Pd80Zr20 surface alloy exhibits markedly enhanced specific and mass activities as well as higher catalytic stability toward oxygen reduction reaction (ORR) compared with NP-Pd and the state-of-the-art Pt/C catalysts. In addition, the NP-Pd80Zr20 surface alloy shows a better selectivity for ORR than methanol in the 0.1 M HClO4 and 0.1 M methanol mixed solution. X-ray photoelectron spectroscopy and density functional theory calculations both demonstrate that the weakened Pd-O bond and improved ORR performances in turn depend on the downshifted d-band center of Pd due to the alloying Pd with Zr (20 at.%). The as-made NP-PdZr alloy holds prospective applications as a cathode electrocatalyst in fuel-cell-related technologies with the advantages of superior overall ORR performances, unique structure stability, and easy preparation.

  8. Morphology, stresses, and surface reactivity of nanoporous gold synthesized from nanostructured precursor alloys

    Science.gov (United States)

    Rouya, Eric

    Nanoporous metallic materials (NMMs) are generally synthesized using dealloying, whereby the more reactive component is dissolved from a homogeneous alloy in a suitable electrolyte, and the more noble metal atoms simultaneously diffuse into 3-D clusters, forming a bi-continuous network of interconnected ligaments. Nanoporous gold (NPG) in particular is a well-known NMM; it is inert, bio-compatible, and capable of developing large surface areas with 1--100nm pores. While several studies have demonstrated its potential usefulness in fuel cell and sensing devices, its structural, mechanical, and electrocatalytic properties still require further investigation, particularly if NPG is synthesized from precursor alloy films exhibiting metastable nanostructures. In this dissertation, the electrodeposition (ECD) process, microstrucural characteristics, and metatstability of Au-Ni precursor alloys are investigated. The stresses evolved during Au-Ni alloy nucleation and growth are investigated in situ and correlated with microstructural and electrochemical data in order to identify the various stress-inducing mechanisms. In situ stresses generated during Au-Ni and Au-Ag dealloying were investigated, and additionally correlated with the growth stresses. Finally, the surface area and electrocatalytic properties of NPG are characterized using a variety of electrochemical techniques. Potentiostatically electrodeposited Au1-x-Nix (x: 0--90at%) films form a continuous series of metastable solid solutions and exhibit a nanocrystalline morphology, with ˜10--20 nm grains, the size of which decreases with increasing Ni content. The formation of a metastable structure was interpreted in terms of the limited surface diffusivities of adatoms at the growing interface and atomic volume differences (˜15%). Internal stresses generated during ECD of Ni-rich films can be explained assuming a 3-D Volmer-Weber growth mode, where the stress is initially compressive, then transitions into tension

  9. Fabrication of novel nanoporous copper powder catalyst by dealloying of ZrCuNiAl amorphous powders for the application of wastewater treatments.

    Science.gov (United States)

    Wang, Shushen; Liu, Lin

    2017-10-15

    The nanoporous copper (Cu) powders (NPCPs) co-existing with Cu 2 O was fabricated by dealloying of atomized Zr-Cu-Ni-Al amorphous powders. The as-fabricated NPCPs, with an inner core and outer shell, showed a large specific surface area of 7.52m 2 g -1 and exhibited significantly superior degradation ability in the presence of hydrogen peroxide (H 2 O 2 ) for the complete elimination of methyl orange (MO) under both acidic and neutral environments. The enhanced catalytic decomposition properties of H 2 O 2 by NPCPs were mainly attributed to the large specific surface area and three-dimensional continuous nanoporous structure with unique atomic steps on the ligament surfaces. The mechanistic investigations revealed that Cu 2 O/H 2 O 2 reactions in acidic environment and Cu 0 /H 2 O 2 reactions in neutral environment, respectively, were responsible for the high degradability of azo dyes, indicating that NPCPs/H 2 O 2 could be a good Fenton-like reagent in application of wastewater treatments. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Microporous Co@C Nanoparticles Prepared by Dealloying CoAl@C Precursors: Achieving Strong Wideband Microwave Absorption via Controlling Carbon Shell Thickness.

    Science.gov (United States)

    Li, Da; Liao, Haoyan; Kikuchi, Hiroaki; Liu, Tong

    2017-12-27

    Excellent magnetic features make Co-based materials promising candidates as high-performance microwave absorbers. However, it is still a significant challenge for Co-based absorbers to possess high-intensity and broadband absorption simultaneously, owing to the lack of dielectric loss and impedance matching. Herein, microporous Co@C nanoparticles (NPs) with carbon shell thicknesses ranging from 1.8-4.9 nm have been successfully synthesized by dealloying CoAl@C precursors. All of the samples exhibit high microwave absorption performance. The microporous Co@C sample possessing a carbon shell of 1.8 nm exhibits the highest absorption intensity among these samples with a minimum reflection loss (RL) of -141.1 dB, whose absorption bandwidth for RL ≤ -10 dB is 7.3 GHz. As the thickness of the carbon shell increases, the absorption bandwidth of the NPs becomes wider. For the sample with the carbon shell thickness of 4.9 nm, the absorption bandwidth for RL ≤ -10 dB reaches a record high of 13.2 GHz. The outstanding microwave attenuation properties are attributed to the dielectric loss of the carbon shell, the magnetic loss of the Co core, and the cooperation of the core-shell structure and microporous morphology. The strong wideband microwave absorption of the carbon-coated microporous Co NPs highlights their potential applications in microwave absorbing systems.

  11. Nonswelling alloy

    International Nuclear Information System (INIS)

    Harkness, S.D.

    1975-01-01

    An aluminum alloy containing one weight percent copper has been found to be resistant to void formation and thus is useful in all nuclear applications which currently use aluminum or other aluminum alloys in reactor positions which are subjected to high neutron doses

  12. Improved Oxygen Reduction Activity and Durability of Dealloyed PtCox Catalysts for Proton Exchange Membrane Fuel Cells: Strain, Ligand, and Particle Size Effects

    Science.gov (United States)

    Jia, Qingying; Caldwell, Keegan; Strickland, Kara; Ziegelbauer, Joseph M.; Liu, Zhongyi; Yu, Zhiqiang; Ramaker, David E.; Mukerjee, Sanjeev

    2015-01-01

    The development of active and durable catalysts with reduced platinum content is essential for fuel cell commercialization. Herein we report that the dealloyed PtCo/HSC and PtCo3/HSC nanoparticle (NP) catalysts exhibit the same levels of enhancement in oxygen reduction activity (~4-fold) and durability over pure Pt/C NPs. Surprisingly, ex situ high-angle annular dark field scanning transmission electron microscopy (HAADF STEM) shows that the bulk morphologies of the two catalysts are distinctly different: D-PtCo/HSC catalyst is dominated by NPs with solid Pt shells surrounding a single ordered PtCo core; however, the D-PtCo3/HSC catalyst is dominated by NPs with porous Pt shells surrounding multiple disordered PtCo cores with local concentration of Co. In situ X-ray absorption spectroscopy (XAS) reveals that these two catalysts possess similar Pt–Pt and Pt–Co bond distances and Pt coordination numbers (CNs), despite their dissimilar morphologies. The similar activity of the two catalysts is thus ascribed to their comparable strain, ligand, and particle size effects. Ex situ XAS performed on D-PtCo3/HSC under different voltage cycling stage shows that the continuous dissolution of Co leaves behind the NPs with a Pt-like structure after 30k cycles. The attenuated strain and/or ligand effects caused by Co dissolution are presumably counterbalanced by the particle size effects with particle growth, which likely accounts for the constant specific activity of the catalysts along with voltage cycling. PMID:26413384

  13. Electrical Resistance Alloys and Low-Expansion Alloys

    DEFF Research Database (Denmark)

    Kjer, Torben

    1996-01-01

    The article gives an overview of electrical resistance alloys and alloys with low thermal expansion. The electrical resistance alloys comprise resistance alloys, heating alloys and thermostat alloys. The low expansion alloys comprise alloys with very low expansion coefficients, alloys with very low...

  14. The effect of alloy elements on the microstructure and properties of austempered ductile irons

    Energy Technology Data Exchange (ETDEWEB)

    Lin, B.Y.; Chen, E.T.; Lei, T.S. [National Taiwan Institute of Technology, Taipei (Taiwan, Province of China). Dept. of Mechanical Engineering

    1995-05-01

    Ductile cast iron has already demonstrated excellent mechanical properties. If given proper austempering, it can exhibit even more outstanding characteristics. The process of austempering for ductile cast iron is similar to steel, and requires an adequate completely, and then rapidly quenching the austenitizing temperature allowing the matrix of ductile iron to be austenitized completely, and then rapidly quenching the austenitized ductile iron down to 300 C--400 C. Caution is required to prevent austenite from transforming into proeutectoid ferrite or pearlite. Finally, the ductile iron must be kept in an isothermal condition for a proper length of time. Many kinds of experimental techniques such as quantitative metallography, magnetic change, dilatometry, X-ray diffraction, electrical resistivity change etc., may be used to measure the phase transformation during the austempering of ductile irons. However, the method of measuring the change of electrical resistivity, not only provides continuous and complete data, but also the time to start and to finish for both stages of the reaction can be significantly determined. In this paper, the effect of alloy elements on the microstructure and property of ADI was investigated. First, the specimens containing Mn, Cu, Ni and Mo were made separately, then a PC-controlled vacuum heat treating system was used for the heat treatments.

  15. High-Activity Dealloyed Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Kongkanand, Anusorn [General Motors LLC, Pontiac, MI (United States)

    2014-09-30

    Reduction of costly Pt usage in proton exchange membrane fuel cell electrodes is one of the major challenges towards development and commercialization of fuel cell vehicles. Although few have met the initial-kinetic activity requirements in a realistic fuel cell device, no catalyst material has ever met the demanding fuel cell durability targets set by DOE. In this project, a team of 4 universities and 2 companies came together to investigate a concept that appeared promising in preliminary non-fuel cell tests then to further develop the catalyst to a mature level ready for vehicle implementation. The team consists of academia with technical leadership in their respective areas, a catalyst supplier, and a fuel cell system integrator.The tightly collaborative project enabled development of a highly active and durable catalyst with performance that significantly exceeds that of previous catalysts and meets the DOE targets for the first time (Figure 1A). The catalyst was then further evaluated in full-active-area stack in a realistic vehicle operating condition (Figure 1B). This is the first public demonstration that one can realize the performance benefit and Pt cost reduction over a conventional pure Pt catalyst in a long-term realistic PEMFC system. Furthermore, systematic analyses of a range of catalysts with different performance after fuel cell testing allowed for correlation between catalyst microstructure and its electrocatalytic activity and durability. This will in turn aid future catalyst development.

  16. One-pot preparation of nanoporous Ag-Cu@Ag core-shell alloy with enhanced oxidative stability and robust antibacterial activity.

    Science.gov (United States)

    Liu, Xue; Du, Jing; Shao, Yang; Zhao, Shao-Fan; Yao, Ke-Fu

    2017-08-31

    Metallic core-shell nanostructures have inspired prominent research interests due to their better performances in catalytic, optical, electric, and magnetic applications as well as the less cost of noble metal than monometallic nanostructures, but limited by the complicated and expensive synthesis approaches. Development of one-pot and inexpensive method for metallic core-shell nanostructures' synthesis is therefore of great significance. A novel Cu network supported nanoporous Ag-Cu alloy with an Ag shell and an Ag-Cu core was successfully synthesized by one-pot chemical dealloying of Zr-Cu-Ag-Al-O amorphous/crystalline composite, which provides a new way to prepare metallic core-shell nanostructures by a simple method. The prepared nanoporous Ag-Cu@Ag core-shell alloy demonstrates excellent air-stability at room temperature and enhanced oxidative stability even compared with other reported Cu@Ag core-shell micro-particles. In addition, the nanoporous Ag-Cu@Ag core-shell alloy also possesses robust antibacterial activity against E. Coli DH5α. The simple and low-cost synthesis method as well as the excellent oxidative stability promises the nanoporous Ag-Cu@Ag core-shell alloy potentially wide applications.

  17. A three-dimensional hierarchical nanoporous PdCu alloy for enhanced electrocatalysis and biosensing

    Energy Technology Data Exchange (ETDEWEB)

    Liu Aihua [Laboratory for Nanobioelectronics and Biosensors, Qingdao Institute of Bioenergy and Bioprocess Technology, and Key Laboratory for Biofuels, Chinese Academy of Sciences, Qingdao 266101 (China); Geng Haoran [School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China); Xu Caixia, E-mail: chm_xucx@ujn.edu.cn [School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China); Qiu Huajun, E-mail: qiuhuajun@gmail.com [Laboratory for Nanobioelectronics and Biosensors, Qingdao Institute of Bioenergy and Bioprocess Technology, and Key Laboratory for Biofuels, Chinese Academy of Sciences, Qingdao 266101 (China)

    2011-10-10

    Highlights: {yields} Nanotubular mesoporous PdCu (NM-PdCu) alloy is facilely fabricated via one-step metal replacement reaction between nanoporous Cu and H{sub 2}PdCl{sub 4}. {yields} The NM-PdCu exhibits remarkably improved structure stability and electrocatalytic activity towards formic acid and hydrogen peroxide oxidation compared with NP-Pd. {yields} When coupled with GOx, the GOx/NM-PdCu electrode can be used for sensitive detection of glucose over a wide concentration range. - Abstract: Nanoporous copper (NPC) obtained by dealloying CuAl alloy is used as both three-dimensional template and reducing agent for the fabrication of nanoporous PdCu alloy with hollow ligaments by a simple galvanic replacement reaction with H{sub 2}PdCl{sub 4} aqueous solution. Electron microscopy and X-ray diffraction characterizations demonstrate that after the replacement reaction, the ligaments become hollow tubular structure and the ligament shell is also comprised of small pores and nanoparticles with a typical size of {approx}4 nm (third order porosity). The as-prepared nanotubular mesoporous PdCu alloy (NM-PdCu) structure exhibits remarkably improved electrocatalytic activity towards the oxidation of formic acid and H{sub 2}O{sub 2} compared with nanoporous Pd (NP-Pd), and can be used for sensitive electrochemical sensing applications. After coupled with glucose oxidase (GOx), the enzyme modified NM-PdCu electrode can sensitively detect glucose over a wide linear range (0.5-20 mM).

  18. Translating VDM to Alloy

    DEFF Research Database (Denmark)

    Lausdahl, Kenneth

    2013-01-01

    specifications. However, to take advantage of the automated analysis of Alloy, the model-oriented VDM specifications must be translated into a constraint-based Alloy specifications. We describe how a sub- set of VDM can be translated into Alloy and how assertions can be expressed in VDM and checked by the Alloy...

  19. Controlled Thermal Expansion Alloys

    Data.gov (United States)

    National Aeronautics and Space Administration — There has always been a need for controlled thermal expansion alloys suitable for mounting optics and detectors in spacecraft applications.  These alloys help...

  20. Alloy Fabrication Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — At NETL’s Alloy Fabrication Facility in Albany, OR, researchers conduct DOE research projects to produce new alloys suited to a variety of applications, from gas...

  1. Processing and alloying of tungsten heavy alloys

    International Nuclear Information System (INIS)

    Bose, A.

    1993-01-01

    Tungsten heavy alloys are two-phase metal matrix composites with a unique combination of density, strength, and ductility. They are processed by liquid-phase sintering of mixed elemental powders. The final microstructure consists of a contiguous network of nearly pure tungsten grains embedded in a matrix of a ductile W-Ni-Fe alloy. Due to the unique property combination of the material, they are used extensively as kinetic energy penetrators, radiation shields. counterbalances, and a number of other applications in the defense industry. The properties of these alloys are extremely sensitive to the processing conditions. Porosity levels as low as 1% can drastically degrade the properties of these alloys. During processing, care must be taken to reduce or prevent incomplete densification, hydrogen embrittlement, impurity segregation to the grain boundaries, solidification shrinkage induced porosity, and in situ formation of pores due to the sintering atmosphere. This paper will discuss some of the key processing issues for obtaining tungsten heavy alloys with good properties. High strength tungsten heavy alloys are usually fabricated by swaging and aging the conventional as-sintered material. The influence of this on the shear localization tendency of a W-Ni-Co alloy will also be demonstrated. Recent developments have shown that the addition of certain refractory metals partially replacing tungsten can significantly improve the strength of the conventional heavy alloys. This development becomes significant due to the recent interest in near net shaping techniques such as powder injection moldings. The role of suitable alloying additions to the classic W-Ni-Fe based heavy alloys and their processing techniques will also be discussed in this paper

  2. 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.

  3. Biocompatibility of dental alloys

    Energy Technology Data Exchange (ETDEWEB)

    Braemer, W. [Heraeus Kulzer GmbH and Co. KG, Hanau (Germany)

    2001-10-01

    Modern dental alloys have been used for 50 years to produce prosthetic dental restorations. Generally, the crowns and frames of a prosthesis are prepared in dental alloys, and then veneered by feldspar ceramics or composites. In use, the alloys are exposed to the corrosive influence of saliva and bacteria. Metallic dental materials can be classified as precious and non-precious alloys. Precious alloys consist of gold, platinum, and small amounts of non-precious components such as copper, tin, or zinc. The non-precious alloys are based on either nickel or cobalt, alloyed with chrome, molybdenum, manganese, etc. Titanium is used as Grade 2 quality for dental purposes. As well as the dental casting alloys, high purity electroplated gold (99.8 wt.-%) is used in dental technology. This review discusses the corrosion behavior of metallic dental materials with saliva in ''in vitro'' tests and the influence of alloy components on bacteria (Lactobacillus casei and Streptococcus mutans). The test results show that alloys with high gold content, cobalt-based alloys, titanium, and electroplated gold are suitable for use as dental materials. (orig.)

  4. The effect of surface pre-conditioning treatments on the local composition of Zr-based conversion coatings formed on aluminium alloys

    Science.gov (United States)

    Cerezo, J.; Vandendael, I.; Posner, R.; de Wit, J. H. W.; Mol, J. M. C.; Terryn, H.

    2016-03-01

    This study investigates the effect of different alkaline, acidic and thermal pre-conditioning treatments applied to different Al alloy surfaces. The obtained results are compared to the characteristics of Zr-based conversion coatings that were subsequently generated on top of these substrates. Focus is laid on typical elemental distributions on the sample surfaces, in particular on the amount of precipitated functional additives such as Cu species that are present in the substrate matrix as well as in the conversion bath solutions. To this aim, Field Emission Auger Electron spectra, depth profiles and surface maps with superior local resolution were acquired and compared to scanning electron microscopy images of the sample. The results show how de-alloying processes, which occur at and around intermetallic particles in the Al matrix during typical industrial alkaline or acidic cleaning procedures, provide a significant source of crystallization cores for any following coating processes. This is in particular due for Cu-species, as the resulting local Cu structures on the surface strongly affect the film formation and compositions of state-of-the-art Zr-based films. The findings are highly relevant for industrial treatments of aluminium surfaces, especially for those that undergo corrosion protection and painting process steps prior to usage.

  5. Catalyst Alloys Processing

    Science.gov (United States)

    Tan, Xincai

    2014-10-01

    Catalysts are one of the key materials used for diamond formation at high pressures. Several such catalyst products have been developed and applied in China and around the world. The catalyst alloy most widely used in China is Ni70Mn25Co5 developed at Changsha Research Institute of Mining and Metallurgy. In this article, detailed techniques for manufacturing such a typical catalyst alloy will be reviewed. The characteristics of the alloy will be described. Detailed processing of the alloy will be presented, including remelting and casting, hot rolling, annealing, surface treatment, cold rolling, blanking, finishing, packaging, and waste treatment. An example use of the catalyst alloy will also be given. Industrial experience shows that for the catalyst alloy products, a vacuum induction remelt furnace can be used for remelting, a metal mold can be used for casting, hot and cold rolling can be used for forming, and acid pickling can be used for metal surface cleaning.

  6. High strength alloy

    International Nuclear Information System (INIS)

    Smelikov, V.G.; Obukhov, A.S.; Ryzhkov, I.V.; Koshelev, V.I.

    1995-01-01

    The magnesium-based alloy in question contains alloy components in the form of elements chosen from the Al, Zn, Mn, Zr and rare earth group, and compounds of nitrogen and oxygen with any of these elements in the following proportions (wt%): alloy components chosen from the Al, Zn, Mn, Zr, Th and rare earth group 0.6-8.0, compound of nitrogen and oxygen with any of the above 0.1-6.0, magnesium the remainder. (author)

  7. Machinability of Titanium Alloys

    Science.gov (United States)

    Rahman, Mustafizur; Wong, Yoke San; Zareena, A. Rahmath

    Titanium and its alloys find wide application in many industries because of their excellent and unique combination of high strength-to-weight ratio and high resistance to corrosion. The machinability of titanium and its alloys is impaired by its high chemical reactivity, low modulus of elasticity and low thermal conductivity. A number of literatures on machining of titanium alloys with conventional tools and advanced cutting tool materials is reviewed. The results obtained from the study on high speed machining of Ti-6Al-4V alloys with cubic boron nitride (CBN), binderless cubic boron nitride (BCBN) and polycrystalline diamond (PCD) are also summarized.

  8. Advances in titanium alloys

    International Nuclear Information System (INIS)

    Seagle, S.R.; Wood, J.R.

    1993-01-01

    As described above, new developments in the aerospace market are focusing on higher temperature alloys for jet engine components and higher strength/toughness alloys for airframe applications. Conventional alloys for engines have reached their maximum useful temperature of about 1000 F (540 C) because of oxidation resistance requirements. IMI 834 and Ti-1100 advanced alloys show some improvement, however, the major improvement appears to be in gamma titanium aluminides which could extend the maximum usage temperature to about 1500 F (815 C). This puts titanium alloys in a competitive position to replace nickel-base superalloys. Advanced airframe alloys such as Ti-6-22-22S, Beta C TM , Ti-15-333 and Ti-10-2-3 with higher strength than conventional Ti-6-4 are being utilized in significantly greater quantities, both in military and commercial applications. These alloys offer improved strength with little or no sacrifice in toughness and improved formability, in some cases. Advanced industrial alloys are being developed for improved corrosion resistance in more reducing and higher temperature environments such as those encountered in sour gas wells. Efforts are focused on small precious metal additions to optimize corrosion performance for specific applications at a modest increase in cost. As these applications develop, the usage of titanium alloys for industrial markets should steadily increase to approach that for aerospace applications. (orig.)

  9. Constructing superhydrophobic WO3@TiO2 nanoflake surface beyond amorphous alloy against electrochemical corrosion on iron steel

    Science.gov (United States)

    Yu, S. Q.; Ling, Y. H.; Wang, R. G.; Zhang, J.; Qin, F.; Zhang, Z. J.

    2018-04-01

    To eliminate harmful localized corrosion, a new approach by constructing superhydrophobic WO3@TiO2 hierarchical nanoflake surface beyond FeW amorphous alloy formed on stainless steel was proposed. Facile dealloying and liquid deposition was employed at low temperature to form a nanostructured layer composing inner WO3 nanoflakes coated with TiO2 nanoparticles (NPs) layer. After further deposition of PFDS on nanoflakes, the contact angle reached 162° while the corrosion potential showed a negative shift of 230 mV under illumination, resulting in high corrosion resistance in 3.5 wt% NaCl solution. The tradeoff between superhydrophobic surface and photo-electro response was investigated. It was found that this surface feature makes 316 SS be immune to localized corrosion and a pronounced photo-induced process of electron storage/release as well as the stability of the functional layer were detected with or without illumination, and the mechanism behind this may be related to the increase of surface potential due to water repellence and the delayed cathodic protection of semiconducting coating derived mainly from the valence state changes of WO3. This study demonstrates a simple and low-cost electrochemical approach for protection of steel and novel means to produce superhydrophobic surface and cathodic protection with controllable electron storage/release on engineering scale.

  10. Synthesis and Electrocatalytic Performance of Multi-Component Nanoporous PtRuCuW Alloy for Direct Methanol Fuel Cells

    Directory of Open Access Journals (Sweden)

    Xiaoting Chen

    2015-06-01

    Full Text Available We have prepared a multi-component nanoporous PtRuCuW (np-PtRuCuW electrocatalyst via a combined chemical dealloying and mechanical alloying process. The X-ray diffraction (XRD, transmission electron microscopy (TEM and electrochemical measurements have been applied to characterize the microstructure and electrocatalytic activities of the np-PtRuCuW. The np-PtRuCuW catalyst has a unique three-dimensional bi-continuous ligament structure and the length scale is 2.0 ± 0.3 nm. The np-PtRuCuW catalyst shows a relatively high level of activity normalized to mass (467.1 mA mgPt−1 and electrochemically active surface area (1.8 mA cm−2 compared to the state-of-the-art commercial PtC and PtRu catalyst at anode. Although the CO stripping peak of np-PtRuCuW 0.47 V (vs. saturated calomel electrode, SCE is more positive than PtRu, there is a 200 mV negative shift compared to PtC (0.67 V vs. SCE. In addition, the half-wave potential and specific activity towards oxygen reduction of np-PtRuCuW are 0.877 V (vs. reversible hydrogen electrode, RHE and 0.26 mA cm−2, indicating a great enhancement towards oxygen reduction than the commercial PtC.

  11. Laser surface alloying of aluminium-transition metal alloys

    International Nuclear Information System (INIS)

    Almeida, A.; Vilar, R.

    1998-01-01

    Laser surface alloying has been used as a tool to produce hard and corrosion resistant Al-transition metal (TM) alloys. Cr and Mo are particularly interesting alloying elements to produce stable high-strength alloys because they present low diffusion coefficients and solid solubility in Al. To produce Al-TM surface alloys a two-step laser process was developed: firstly, the material is alloyed using low scanning speed and secondly, the microstructure is modified by a refinement step. This process was used in the production of Al-Cr, Al-Mo and Al-Mo and Al-Nb surface alloys by alloying Cr, Mo or Nb powder into an Al and 7175 Al alloy substrate using a CO 2 laser . This paper presents a review of the work that has been developed at Instituto Superior Tecnico on laser alloying of Al-TM alloy, over the last years. (Author) 16 refs

  12. Shape memory alloys

    International Nuclear Information System (INIS)

    Kaszuwara, W.

    2004-01-01

    Shape memory alloys (SMA), when deformed, have the ability of returning, in certain circumstances, to their initial shape. Deformations related to this phenomenon are for polycrystals 1-8% and up to 15% for monocrystals. The deformation energy is in the range of 10 6 - 10 7 J/m 3 . The deformation is caused by martensitic transformation in the material. Shape memory alloys exhibit one directional or two directional shape memory effect as well as pseudoelastic effect. Shape change is activated by temperature change, which limits working frequency of SMA to 10 2 Hz. Other group of alloys exhibit magnetic shape memory effect. In these alloys martensitic transformation is triggered by magnetic field, thus their working frequency can be higher. Composites containing shape memory alloys can also be used as shape memory materials (applied in vibration damping devices). Another group of composite materials is called heterostructures, in which SMA alloys are incorporated in a form of thin layers The heterostructures can be used as microactuators in microelectromechanical systems (MEMS). Basic SMA comprise: Ni-Ti, Cu (Cu-Zn,Cu-Al, Cu-Sn) and Fe (Fe-Mn, Fe-Cr-Ni) alloys. Shape memory alloys find applications in such areas: automatics, safety and medical devices and many domestic appliances. Currently the most important appears to be research on magnetic shape memory materials and high temperature SMA. Vital from application point of view are composite materials especially those containing several intelligent materials. (author)

  13. Thermofluency in zirconium alloys

    International Nuclear Information System (INIS)

    Orozco M, E.A.

    1976-01-01

    A summary is presented about the theoretical and experimental results obtained at present in thermofluency under radiation in zirconium alloys. The phenomenon of thermofluency is presented in a general form, underlining the thermofluency at high temperature because this phenomenon is similar to the thermofluency under radiation, which ocurrs in zirconium alloys into the operating reactor. (author)

  14. Aluminum battery alloys

    Science.gov (United States)

    Thompson, David S.; Scott, Darwin H.

    1985-01-01

    Aluminum alloys suitable for use as anode structures in electrochemical cs are disclosed. These alloys include iron levels higher than previously felt possible, due to the presence of controlled amounts of manganese, with possible additions of magnesium and controlled amounts of gallium.

  15. Ductile transplutonium metal alloys

    Science.gov (United States)

    Conner, William V.

    1983-01-01

    Alloys of Ce with transplutonium metals such as Am, Cm, Bk and Cf have properties making them highly suitable as sources of the transplutonium element, e.g., for use in radiation detector technology or as radiation sources. The alloys are ductile, homogeneous, easy to prepare and have a fairly high density.

  16. Alloys in energy development

    Energy Technology Data Exchange (ETDEWEB)

    Frost, B.R.T.

    1984-02-01

    The development of new and advanced energy systems often requires the tailoring of new alloys or alloy combinations to meet the novel and often stringent requirements of those systems. Longer life at higher temperatures and stresses in aggressive environments is the most common goal. Alloy theory helps in achieving this goal by suggesting uses of multiphase systems and intermediate phases, where solid solutions were traditionally used. However, the use of materials under non-equilibrium conditions is now quite common - as with rapidly solidified metals - and the application of alloy theory must be modified accordingly. Under certain conditions, as in a reactor core, the rate of approach to equilibrium will be modified; sometimes a quasi-equilibrium is established. Thus an alloy may exhibit enhanced general diffusion at the same time as precipitate particles are being dispersed and solute atoms are being carried to vacancy sinks. We are approaching an understanding of these processes and can begin to model these complex systems.

  17. Alloying principles for magnesium base heat resisting alloys

    International Nuclear Information System (INIS)

    Drits, M.E.; Rokhlin, L.L.; Oreshkina, A.A.; Nikitina, N.I.

    1982-01-01

    Some binary systems of magnesium-base alloys in which solid solutions are formed, are considered for prospecting heat resistant alloys. It is shown that elements having essential solubility in solid magnesium strongly decreasing with temperature should be used for alloying maqnesium base alloys with high strength properties at increased temperatures. The strengthening phases in these alloys should comprise essential quantity of magnesium and be rather refractory

  18. The effect of surface pre-conditioning treatments on the local composition of Zr-based conversion coatings formed on aluminium alloys

    International Nuclear Information System (INIS)

    Cerezo, J.; Vandendael, I.; Posner, R.; Wit, J.H.W. de; Mol, J.M.C.; Terryn, H.

    2016-01-01

    Graphical abstract: - Highlights: • Field Emission Auger Electron Spectroscopy was used for local elemental analysis. • Acid and alkaline pre-conditioning treatments induces Cu-enrichment on AA6014. • A Cu-containing Zr-based conversion treatment for aluminium alloys was evaluated. • Cu-rich areas enhance the local formation of Zr-based conversion films on AA6014. • Thermal pre-conditioning treatments inhibits the formation of Zr-based coatings. - Abstract: This study investigates the effect of different alkaline, acidic and thermal pre-conditioning treatments applied to different Al alloy surfaces. The obtained results are compared to the characteristics of Zr-based conversion coatings that were subsequently generated on top of these substrates. Focus is laid on typical elemental distributions on the sample surfaces, in particular on the amount of precipitated functional additives such as Cu species that are present in the substrate matrix as well as in the conversion bath solutions. To this aim, Field Emission Auger Electron spectra, depth profiles and surface maps with superior local resolution were acquired and compared to scanning electron microscopy images of the sample. The results show how de-alloying processes, which occur at and around intermetallic particles in the Al matrix during typical industrial alkaline or acidic cleaning procedures, provide a significant source of crystallization cores for any following coating processes. This is in particular due for Cu-species, as the resulting local Cu structures on the surface strongly affect the film formation and compositions of state-of-the-art Zr-based films. The findings are highly relevant for industrial treatments of aluminium surfaces, especially for those that undergo corrosion protection and painting process steps prior to usage.

  19. Uranium-Niobium alloys

    International Nuclear Information System (INIS)

    Moura Neto, C. de

    1985-01-01

    The basic characteristics of the phase diagram of the U-Nb alloy are presented. Structural and morphological aspects of the kinectics of phase transformation are discussed, based in the phase diagram. (Author) [pt

  20. Characteristics of mechanical alloying of Zn-Al-based alloys

    International Nuclear Information System (INIS)

    Zhu, Y.H.; Hong Kong Polytechnic; Perez Hernandez, A.; Lee, W.B.

    2001-01-01

    Three pure elemental powder mixtures of Zn-22%Al-18%Cu, Zn-5%Al-11%Cu, and Zn-27%Al-3%Cu (in wt.%) were mechanically alloyed by steel-ball milling processing. The mechanical alloying characteristics were investigated using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy techniques. It was explored that mechanical alloying started with the formation of phases from pure elemental powders, and this was followed by mechanical milling-induced phase transformation. During mechanical alloying, phases stable at the higher temperatures formed at the near room temperature of milling. Nano-structure Zn-Al-based alloys were produced by mechanical alloying. (orig.)

  1. Machining of titanium alloys

    CERN Document Server

    2014-01-01

    This book presents a collection of examples illustrating the resent research advances in the machining of titanium alloys. These materials have excellent strength and fracture toughness as well as low density and good corrosion resistance; however, machinability is still poor due to their low thermal conductivity and high chemical reactivity with cutting tool materials. This book presents solutions to enhance machinability in titanium-based alloys and serves as a useful reference to professionals and researchers in aerospace, automotive and biomedical fields.

  2. Refractory alloy component fabrication

    International Nuclear Information System (INIS)

    Young, W.R.

    1984-01-01

    Purpose of this report is to describe joining procedures, primarily welding techniques, which were developed to construct reliable refractory alloy components and systems for advanced space power systems. Two systems, the Nb-1Zr Brayton Cycle Heat Receiver and the T-111 Alloy Potassium Boiler Development Program, are used to illustrate typical systems and components. Particular emphasis is given to specific problems which were eliminated during the development efforts. Finally, some thoughts on application of more recent joining technology are presented. 78 figures

  3. Texture in low-alloyed uranium alloys

    International Nuclear Information System (INIS)

    Sariel, J.

    1982-08-01

    The dependence of the preferred orientation of cast and heat-treated polycrystalline adjusted uranium and uranium -0.1 w/o chromium alloys on the production process was studied. The importance of obtaining material free of preferred orientation is explained, and a survey of the regular methods to determine preferred orientation is given. Dilatometry, tensile testing and x-ray diffraction were used to determine the extent of the directionality of these alloys. Data processing showed that these methods are insufficient in a case of a material without any plastic forming, because of unreproducibility of results. Two parameters are defined from the results of Schlz's method diffraction test. These parameters are shown theoretically and experimentally (by extreme-case samples) to give the deviation from isotropy. Application of these parameters to the examined samples showes that cast material has preferred orientation, though it is not systematic. This preferred orientation was reduced by adequate heat treatments

  4. Correlation between diffusion barriers and alloying energy in binary alloys

    DEFF Research Database (Denmark)

    Vej-Hansen, Ulrik Grønbjerg; Rossmeisl, Jan; Stephens, Ifan

    2016-01-01

    In this paper, we explore the notion that a negative alloying energy may act as a descriptor for long term stability of Pt-alloys as cathode catalysts in low temperature fuel cells.......In this paper, we explore the notion that a negative alloying energy may act as a descriptor for long term stability of Pt-alloys as cathode catalysts in low temperature fuel cells....

  5. Impact toughness of laser alloyed aluminium AA1200 alloys

    CSIR Research Space (South Africa)

    Mabhali, Luyolo AB

    2013-08-01

    Full Text Available Laser surface alloying of aluminium AA1200 was performed with a 4kW Nd:YAG laser and impact resistance of the alloys was investigated. The alloying powders were a mixture of Ni, Ti and SiC in different proportions. Surfaces reinforced...

  6. INVESTIGATION OF MAGNESIUM ALLOYS MACHINABILITY

    Directory of Open Access Journals (Sweden)

    Berat Barıs BULDUM

    2013-01-01

    Full Text Available Magnesium is the lightest structural metal. Magnesium alloys have a hexagonal lattice structure, which affects the fundamental properties of these alloys. Plastic deformation of the hexagonal lattice is more complicated than in cubic latticed metals like aluminum, copper and steel. Magnesium alloy developments have traditionally been driven by industry requirements for lightweight materials to operate under increasingly demanding conditions. Magnesium alloys have always been attractive to designers due to their low density, only two thirds that of aluminium and its alloys [1]. The element and its alloys take a big part of modern industry needs. Especially nowadays magnesium alloys are used in automotive and mechanical (trains and wagons manufacture, because of its lightness and other features. Magnesium and magnesium alloys are the easiest of all metals to machine, allowing machining operations at extremely high speed. All standard machining operations such as turning, drilling, milling, are commonly performed on magnesium parts.

  7. Structural thermodynamics of alloys

    CERN Document Server

    Manenc, Jack

    1973-01-01

    Technical progress has for a very long time been directly dependent on progress in metallurgy, which is itself connected with improvements in the technology of alloys. Metals are most frequently used in the form of alloys for several reasons: the quantity of pure metal in its native state in the earth's crust is very limited; pure metals must be extracted from ores which are themselves impure. Finally, the methods of treatment used lead more easily to alloys than to pure metals. The most typical case is that of iron, where a pure ore may be found, but which is the starting point for cast iron or steel, alloys of iron and carbon. In addition, the properties of alloys are in general superior to those of pure metals and modem metallurgy consists of controlling these properties so as to make them conform to the requirements of the design office. Whilst the engineer was formerly compelled to adapt his designs and constructions to the materials available, such as wood, stone, bronze, iron, cast iron and ordinary st...

  8. Shape memory alloy engine

    International Nuclear Information System (INIS)

    Tanaka, M.

    1992-01-01

    This paper discusses a shape memory alloy engine, developed for the purpose of extracting the mechanical energy from a small difference in temperature. The engine is mainly composed of two pulleys (high temperature and low temperature) and single belt made of the nickel titanium shape memory alloy. The alloy memorizes a shape arcing in the direction opposite to the direction of the belt arc around the pulleys. When the temperature of the belt which is in contact with the high temperature pulley rises above the transformation temperature, a return to the memorized shape generates a force which rotates the pulleys. To make the heat transfer more effective, the engine was designed so that the lower part of the two pulleys are embedded in hot and cold water, respectively. To predict the performance of the shape memory alloy engine, the stress change of the shape memory alloy caused by temperature change has been also investigated with the bending stress test, and a torque loss of the engine system was measured. The predicted results were coincident with the output power experiment

  9. INVESTIGATION OF MAGNESIUM ALLOYS MACHINABILITY

    OpenAIRE

    Berat Barıs BULDUM; Aydın SIK; Iskender OZKUL

    2013-01-01

    Magnesium is the lightest structural metal. Magnesium alloys have a hexagonal lattice structure, which affects the fundamental properties of these alloys. Plastic deformation of the hexagonal lattice is more complicated than in cubic latticed metals like aluminum, copper and steel. Magnesium alloy developments have traditionally been driven by industry requirements for lightweight materials to operate under increasingly demanding conditions. Magnesium alloys have always been attra...

  10. Welding of refractory alloys

    International Nuclear Information System (INIS)

    Lessmann, G.G.

    1984-01-01

    This review primarily summarizes welding evaluations supported by NASA-Lewis Research Center in the 1960s. A literature search run in preparation for this review indicates that more recent work is modest by comparison. Hence, this review restates these accomplishments briefly and addresses opportunities which have evolved in welding technology (such as lasers) in the intervening decade. Emphasis in this review is given to tantalum- and niobium-base alloys. Considerable work was also done to assure that a consistent comparison was made with tungsten. A wide variety of candidate alloys derived primarily from developments directed at aircraft propulsion applications were available. Early efforts by NASA were directed at screening studies to select promising structural alloys for the space power application. This objective required fine tuning of welding procedures, e.g., the demonstration of stringent standards for control of welding atmosphere to assure good corrosion resistance in liquid alkali metals. 16 figures, 6 tables

  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. Tungsten Alloy Outgassing Measurements

    CERN Document Server

    Rutherfoord, John P; Shaver, L

    1999-01-01

    Tungsten alloys have not seen extensive use in liquid argon calorimeters so far. Because the manufacturing process for tungsten is different from the more common metals used in liquid argon there is concern that tungsten could poison the argon thereby creating difficulties for precision calorimetry. In this paper we report measurements of outgassing from the tungsten alloy slugs proposed for use in the ATLAS FCal module and estimate limits on potential poisoning with reasonable assumptions. This estimate gives an upper limit poisoning rate of

  13. Galvanic corrosion in odontological alloys

    International Nuclear Information System (INIS)

    Riesgo, O.; Bianchi, G.L.; Duffo, G.S.

    1993-01-01

    Galvanic corrosion can occur when different alloys are placed in direct contact within the oral cavity or within tissues. Concern has been expressed associated with the coupling of selected restorative materials as well as implant material with various alloys used for restorative procedures. This could be critical if the crown or bridge had subgingival finish line with a metallic zone in contact with the tissue, and the implant was made in titanium alloy. The present work shows the results of galvanic coupling studies done on implants of titanium alloy connected to nickel-chromium and cobalt-chromium alloys. (Author)

  14. Borated aluminum alloy manufacturing technology

    International Nuclear Information System (INIS)

    Shimojo, Jun; Taniuchi, Hiroaki; Kajihara, Katsura; Aruga, Yasuhiro

    2003-01-01

    Borated aluminum alloy is used as the basket material of cask because of its light weight, thermal conductivity and superior neutron absorbing abilities. Kobe Steel has developed a unique manufacturing process for borated aluminum alloy using a vacuum induction melting method. In this process, aluminum alloy is melted and agitated at higher temperatures than common aluminum alloy fabrication methods. It is then cast into a mold in a vacuum atmosphere. The result is a high quality aluminum alloy which has a uniform boron distribution and no impurities. (author)

  15. Fracture of Shape Memory Alloys

    OpenAIRE

    Miyazaki, Shuichi; Otsuka, Kazuhiro

    1981-01-01

    The initiation and the propagation of cracks during both quenching and deformation in polycrystalline Cu-Al-Ni alloys have been investigated under various conditions. The fracture surfaces of Ti-Ni and Cu-Al-Ni alloys were also observed by a scanning electron microscope. From these results, it was concluded that the brittleness of Cu-Al-Ni alloy and other β phase alloys are due to large elastic anisotropy and large grain sizes, while that the large ductility in Ti-Ni alloy being due to the sm...

  16. Titanium and zirconium alloys

    International Nuclear Information System (INIS)

    Pinard Legry, G.

    1994-01-01

    Titanium and zirconium pure and base alloys are protected by an oxide film with anionic vacancies which gives a very good resistance to corrosion in oxidizing medium, in some ph ranges. Results of pitting and crevice corrosion are given for Cl - , Br - , I - ions concentration with temperature and ph dependence, also with oxygenated ions effect. (A.B.). 32 refs., 6 figs., 3 tabs

  17. High strength ferritic alloy

    International Nuclear Information System (INIS)

    1977-01-01

    A high strength ferritic steel is specified in which the major alloying elements are chromium and molybdenum, with smaller quantities of niobium, vanadium, silicon, manganese and carbon. The maximum swelling is specified for various irradiation conditions. Rupture strength is also specified. (U.K.)

  18. Amorphization of equimolar alloys with HCP elements during mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yu-Liang [Materials and Electro-Optics Research Division, Chung-Shan Institute of Science and Technology, Armaments Bureau, MND, P.O. Box 90008-8-5, Lung-Tan, Tao-Yuan 32599, Taiwan (China); Department of Materials Science and Engineering, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China); Tsai, Che-Wei; Juan, Chien-Chang; Chuang, Ming-Hao [Department of Materials Science and Engineering, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China); Yeh, Jien-Wei, E-mail: jwyeh@mx.nthu.edu.t [Department of Materials Science and Engineering, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China); Chin, Tsung-Shune [Department of Materials Science and Engineering, Feng Chia University, 100, Wenhwa Rd., Seatwen District, Taichung 40724, Taiwan (China); Chen, Swe-Kai [Center for Nanotechnology, Materials Science and Microsystems, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China)

    2010-09-10

    This study prepares two equimolar alloys, entirely composed of HCP elements, BeCoMgTi and BeCoMgTiZn, from elemental powders by mechanical alloying. No crystalline solid solutions and compounds formed during milling except an amorphous phase formed gradually until full amorphization was attained. The amorphization processes of these two alloys conform to type II according to the Weeber and Bakker classification based on binary alloys. The inhibition of crystalline solid solutions and compounds before amorphization relates to chemical compatibility, high entropy effect and large atomic size difference effect.

  19. Filler metal alloy for welding cast nickel aluminide alloys

    Science.gov (United States)

    Santella, Michael L.; Sikka, Vinod K.

    1998-01-01

    A filler metal alloy used as a filler for welding east nickel aluminide alloys contains from about 15 to about 17 wt. % chromium, from about 4 to about 5 wt. % aluminum, equal to or less than about 1.5 wt. % molybdenum, from about 1 to about 4.5 wt. % zirconium, equal to or less than about 0.01 wt. % yttrium, equal to or less than about 0.01 wt. % boron and the balance nickel. The filler metal alloy is made by melting and casting techniques such as are melting the components of the filler metal alloy and east in copper chill molds.

  20. Rare earth ferrosilicon alloy

    International Nuclear Information System (INIS)

    Caiquan, L.; Zeguang, T.; Zaizhang, L.

    1985-01-01

    In order to obtain RE ferrosilicon alloy with good quality and competitive price, it is essential that proper choice of raw materials, processing technology and equipments should be made based on the characteristics of Bai-Yun-Ebo mineral deposits. Experimental work and actual production practice indicate that pyrometallurgical method is suitable for the extraction and isolation of the rare earths and comprehensive utilization of the metal values contained in the feed material is capable of reducing cost of production of RE ferrosilicon alloy. In the Bai-Yun-Ebo deposit, the fluorite type medium lean ore (with respect to iron content) makes a reserve of considerable size. The average content of the chief constituents are given

  1. Metastable superconducting alloys

    International Nuclear Information System (INIS)

    Johnson, W.L.

    1978-07-01

    The study of metastable metals and alloys has become one of the principal activities of specialists working in the field of superconducting materials. Metastable crystalline superconductors such as the A15-type materials have been given much attention. Non-crystalline superconductors were first studied over twenty years ago by Buckel and Hilsch using the technique of thin film evaporation on a cryogenic substrate. More recently, melt-quenching, sputtering, and ion implantation techniques have been employed to produce a variety of amorphous superconductors. The present article presents a brief review of experimental results and a survey of current work on these materials. The systematics of superconductivity in non-crystalline metals and alloys are described along with an analysis of the microscopic parameters which underlie the observed trends. The unique properties of these superconductors which arise from the high degree of structural disorder in the amorphous state are emphasized

  2. Informatics Aided Design for Alloys

    Science.gov (United States)

    2009-02-28

    alloying discoveries/ predictions of new ternary cobalt based alloys that can have improved properties from conventional nickel based superalloys ...Using this approach we have proposed new ternary alloy additions for binary cobalt based intermetallics. Through comparison with some recent...that are even better than nickel base superalloys . This strategy has also been extended to the development of new type of design maps that identify

  3. Pareto-optimal alloys

    DEFF Research Database (Denmark)

    Bligaard, Thomas; Johannesson, Gisli Holmar; Ruban, Andrei

    2003-01-01

    Large databases that can be used in the search for new materials with specific properties remain an elusive goal in materials science. The problem is complicated by the fact that the optimal material for a given application is usually a compromise between a number of materials properties and the ......, the Pareto-optimal set, to determine optimal alloy solutions for the compromise between low compressibility, high stability, and cost....

  4. Alloy catalyst material

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to a novel alloy catalyst material for use in the synthesis of hydrogen peroxide from oxygen and hydrogen, or from oxygen and water. The present invention also relates to a cathode and an electrochemical cell comprising the novel catalyst material, and the process use...... of the novel catalyst material for synthesising hydrogen peroxide from oxygen and hydrogen, or from oxygen and water....

  5. Aluminum Alloy 7050 Extrusions.

    Science.gov (United States)

    1977-03-01

    tooling used in the 25-inch diameter casting trials at the laboratory was transferred to Lafayette Works and installed at a ladle casting station. The...for the laboratory casting trials was transferred to Alcoa’s Lafayette Works and installed on a ladle pour casting unit. After some minor adjustments...Fatigue Alloy Compressive Modulus of Elasticity Crack Propagation Ingot Fabricating Stress-Strain Stress-Corrosion Casting Heat

  6. Aluminum alloy impact sparkling

    Directory of Open Access Journals (Sweden)

    M. Dudyk

    2008-08-01

    Full Text Available The cast machine parts are widely used in many branches of industry. A very important issue is gaining the appropriate knowledge relating to the application of castings in places of explosion risks including but not limited to mining, chemical industry and rescue works. A possibility of explosion risks occurrence following the impact sparkling of the cast metal parts is still not solved problem in scientific research. In relation to this issue, in this article, the results of the study are presented, and relating to the tendency to impact sparkling of the aluminium alloys used in machine building. On the grounds of the results obtained, it was demonstrated that the registered impact sparkles bunches of feathers from the analyzed alloys: AlSi7Mg, (AK7; AlSi9Mg, (AK9; AlSi6Cu4, (AK64 and AlSi11, (AK11 show significant differences between each other. The quantitative analysis of the temperature distribution and nuclei surface area performed on the example of the alloy AK9 (subjected to defined period of corrosion allows for the statement that they are dangerous in conditions of explosion risk. Following this fact, designers and users of machine parts made from these materials should not use them in conditions where the explosive mixtures occur.

  7. Low activation vanadium alloys

    International Nuclear Information System (INIS)

    Witzenburg, W. van.

    1991-01-01

    The properties and general characteristics of vanadium-base alloys are reviewed in terms of the materials requirements for fusion reactor first wall and blanket structures. In this review attention is focussed on radiation response including induced radioactivity, mechanical properties, compatibility with potential coolants, physical and thermal properties, fabricability and resources. Where possible, properties are compared to those of other leading candidate structural materials, e.g. austenitic and ferritic/martensitic steels. Vanadium alloys appear to offer advantages in the areas of long-term activation, mechanical properties at temperatures above 600 deg C, radiation resistance and thermo-hydraulic design, due to superior physical and thermal properties. They also have a potential for higher temperature operation in liquid lithium systems. Disadvantages are associated with their ability to retain high concentrations of hydrogen isotopes, higher cost, more difficult fabrication and welding. A particular concern regarding use of vanadium alloys relates their reactivity with non-metallic elements, such as oxygen and nitrogen. (author). 33 refs.; 2 figs.; 2 tabs

  8. Large plastic stability in magnesium alloys: crystalline vs. amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Boissiere, R.; Puech, S.; Blandin, J.J. [Institut National Polytechnique de Grenoble (INPG), SIMaP Laboratory - GPM2 group, CNRS/UJF, Domaine Universitaire, Saint-Martin d' Heres (France)

    2008-04-15

    Except if strain induces damage, the plastic stability can be roughly estimated thanks to the value of the strain rate sensitivity parameter m. In conventional magnesium alloys, moderate values of m (typically close to 0.3) can be frequently obtained during high temperature deformation. Such values allow reaching significant elongations to fracture. For alloys displaying fine grains, superplastic properties associated with values of m of about 0.5 or more are achievable leading to large elongations to fracture in optimized conditions for which damage processes remain limited. Quite recently, amorphous magnesium alloys have been produced in bulk conditions. In appropriate conditions of deformation, these alloys display Newtonian behaviour (i.e. m=1). With such rheologies, the plastic stability is expected to be maximal. In this presentation, features in relation with high temperature deformation of amorphous and crystalline magnesium alloys will be compared and apparent similitudes and differences will be discussed. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  9. Chitosan-based Schiff base-metal complexes (Mn, Cu, Co) as ...

    Indian Academy of Sciences (India)

    catalyst was studied using a batch reactor and gas chromatography for product identification and quantifica- tion. The results were compared against the ... It has many applications in medicine such as wound dressings, artificial ...... a stable Schiff base, which can form a com- plex with metal ion, resulting in a promising cata-.

  10. Chitosan-based Schiff base-metal complexes (Mn, Cu, Co) as ...

    Indian Academy of Sciences (India)

    effective catalyst systems for the selective oxidation of cyclic olefins under milder conditions. The oxidation of β-isophorone to ketoisophorone is one example of such chemistry, which is an industrially important reac- tion. Ketoisophorone is an important intermediate in the industrial synthesis of vitamin E. Ketoisophorone.

  11. Neodymium alloys and their fabrication process

    International Nuclear Information System (INIS)

    Seon, F.; Boudot, B.

    1985-01-01

    Neodymium alloys, particularly neodymium-iron alloys, are prepared by reduction of a neodymium halogenide, preferentially neodymium fluoride by a reducing metal (e.g. Ca) with the addition of the metal M to introduce in the final alloy. From these alloys metallic neodymium can be obtained [fr

  12. Interaction Of Hydrogen With Metal Alloys

    Science.gov (United States)

    Danford, M. D.; Montano, J. W.

    1993-01-01

    Report describes experiments on interaction of hydrogen with number of metal alloys. Discusses relationship between metallurgical and crystallographic aspects of structures of alloys and observed distributions of hydrogen on charging. Also discusses effect of formation of hydrides on resistances of alloys to hydrogen. Describes attempt to correlate structures and compositions of alloys with their abilities to resist embrittlement by hydrogen.

  13. Stress Corrosion Cracking of Certain Aluminum Alloys

    Science.gov (United States)

    Hasse, K. R.; Dorward, R. C.

    1983-01-01

    SC resistance of new high-strength alloys tested. Research report describes progress in continuing investigation of stress corrosion (SC) cracking of some aluminum alloys. Objective of program is comparing SC behavior of newer high-strength alloys with established SC-resistant alloy.

  14. Amorphous Semiconductor Alloys

    Science.gov (United States)

    Madan, Arun

    1985-08-01

    Amorphous silicon (a-Si) based alloys have attracted a considerable amount of interest because of their applications in a wide variety of technologies. However, the major effort has concentrated on inexpensive photovoltaic device applications and has moved from a laboratory curiosity in the early 1970's to viable commercial applications in the 1980's. Impressive progress in this field has been made since the group at University of Dundee demonstrated that a low defect, device quality hydrogenated amorphous silicon (a-Si:H) 12 material could be produced using the radio frequency (r.f.) glow discharge in SiH4 gas ' and that the material could be doped n- and p-type.3 These results spurred a worldwide interest in a-Si based alloys, especially for photovoltaic devices which has resulted in a conversion efficiency approaching 12%. There is now a quest for even higher conversion efficiencies by using the multijunction cell approach. This necessitates the synthesis of new materials of differing bandgaps, which in principle amorphous semiconductors can achieve. In this article, we review some of this work and consider from a device and a materials point of view the hurdles which have to be overcome before this type of concept can be realized.

  15. Lightweight Multifunctional Linear Cellular Alloy Ballistic Structures

    Science.gov (United States)

    2006-04-26

    densities of 10, 15 and 20 % with the dimensions shown in Table 1. The alloy compositions were high strength maraging steel (M200) and Super Invar ... alloys made from LCA processing3 are shown in Table 3. Super Invar in the as-reduced state is a ductile (25-30%) austenitic alloy . When cooled to...Final Report for Lightweight Multifunctional Linear Cellular Alloy Ballistic Structures from Structured Alloys , Inc. Joe K

  16. Competition between elements during mechanical alloying in an octonary multi-principal-element alloy system

    International Nuclear Information System (INIS)

    Chen, Y.-L.; Hu, Y.-H.; Hsieh, C.-A.; Yeh, J.-W.; Chen, S.-K.

    2009-01-01

    The competition between the constituent elements of the Cu 0.5 NiAlCoCrFeTiMo alloy system during mechanical alloying was investigated and ranked with their alloying rates in getting alloyed in the mixture. By using XRD analysis, EDS mapping, extended X-ray absorption fine structure technique, and synchrotron radiation diffraction, the alloying sequence for the present alloy system is determined as Al → Cu → Co → Ni → Fe → Ti → Cr → Mo in the order of decreasing alloying rate. The alloying rate is found to correlate best with the melting point of the elements among metallurgical factors. The mechanism for this correlation is explained through the effect of melting point on solid-state diffusion and mechanical disintegration which are critical for the final alloying. This finding is valuable in predicting the alloying sequence of elements, and thus the phase evolution in multi-component alloys during mechanical alloying.

  17. Alloying Solid Solution Strengthening of Fe-Ga Alloys: A First-Principle Study

    National Research Council Canada - National Science Library

    Chen, Kuiying; Cheng, Leon M

    2006-01-01

    ... and Co in cubic solid solution of Fe-Ga alloys. Mayer bond order "BO" values were used to evaluate the atomic bond strengths in the alloys, and were then used to assess the alloying strengthening characteristics...

  18. 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...

  19. Laser surface alloying on aluminum and its alloys: A review

    Science.gov (United States)

    Chi, Yiming; Gu, Guochao; Yu, Huijun; Chen, Chuanzhong

    2018-01-01

    Aluminum and its alloys have been widely used in aerospace, automotive and transportation industries owing to their excellent properties such as high specific strength, good ductility and light weight. Surface modification is of crucial importance to the surface properties of aluminum and its alloys since high coefficient of friction, wear characteristics and low hardness have limited their long term performance. Laser surface alloying is one of the most effective methods of producing proper microstructure by means of non-equilibrium solidification which results from rapid heating and cooling. In this paper, the influence of different processing parameters, such as laser power and scanning velocity is discussed. The developments of various material systems including ceramics, metals or alloys, and metal matrix composites (MMCs) are reviewed. The microstructure, hardness, wear properties and other behaviors of laser treated layer are analyzed. Besides, the existing problems during laser surface treatment and the corresponding solutions are elucidated and the future developments are predicted.

  20. Alloying and Casting Furnace for Shape Memory Alloys, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The concept in the proposed project is to create a melting, alloying and casting furnace for the processing titanium based SMA using cold crucible techniques. The...

  1. Mechanical alloying of biocompatible Co-28Cr-6Mo alloy.

    Science.gov (United States)

    Sánchez-De Jesús, F; Bolarín-Miró, A M; Torres-Villaseñor, G; Cortés-Escobedo, C A; Betancourt-Cantera, J A

    2010-07-01

    We report on an alternative route for the synthesis of crystalline Co-28Cr-6Mo alloy, which could be used for surgical implants. Co, Cr and Mo elemental powders, mixed in an adequate weight relation according to ISO Standard 58342-4 (ISO, 1996), were used for the mechanical alloying (MA) of nano-structured Co-alloy. The process was carried out at room temperature in a shaker mixer mill using hardened steel balls and vials as milling media, with a 1:8 ball:powder weight ratio. Crystalline structure characterization of milled powders was carried out by X-ray diffraction in order to analyze the phase transformations as a function of milling time. The aim of this work was to evaluate the alloying mechanism involved in the mechanical alloying of Co-28Cr-6Mo alloy. The evolution of the phase transformations with milling time is reported for each mixture. Results showed that the resultant alloy is a Co-alpha solid solution, successfully obtained by mechanical alloying after a total of 10 h of milling time: first Cr and Mo are mechanically prealloyed for 7 h, and then Co is mixed in for 3 h. In addition, different methods of premixing were studied. The particle size of the powders is reduced with increasing milling time, reaching about 5 mum at 10 h; a longer time promotes the formation of aggregates. The morphology and crystal structure of milled powders as a function of milling time were analyzed by scanning electron microscopy and XR diffraction.

  2. Temperature-dependent structure, elasticity, and entropic stability of Bi phases on Cu(111)

    NARCIS (Netherlands)

    van Gastel, Raoul; Kaminski, D; Vlieg, E.; Poelsema, Bene

    2014-01-01

    We have used low energy electron microscopy (LEEM) to characterize the structure and stability of Bi phases on Cu{111}. As a function of temperature we find that the Cu{111}(3√×3√)R30∘-Bi surface alloy phase gradually dealloys and is fully depleted from Bi at a temperature of 803 K. The dealloying

  3. Manufacturing of High Entropy Alloys

    Science.gov (United States)

    Jablonski, Paul D.; Licavoli, Joseph J.; Gao, Michael C.; Hawk, Jeffrey A.

    2015-07-01

    High entropy alloys (HEAs) have generated interest in recent years due to their unique positioning within the alloy world. By incorporating a number of elements in high proportion they have high configurational entropy, and thus they hold the promise of interesting and useful properties such as enhanced strength and phase stability. The present study investigates the microstructure of two single-phase face-centered cubic (FCC) HEAs, CoCrFeNi and CoCrFeNiMn, with special attention given to melting, homogenization and thermo-mechanical processing. Large-scale ingots were made by vacuum induction melting to avoid the extrinsic factors inherent in small-scale laboratory button samples. A computationally based homogenization heat treatment was applied to both alloys in order to eliminate segregation due to normal ingot solidification. The alloys fabricated well, with typical thermo-mechanical processing parameters being employed.

  4. 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

  5. Multiple allergies to metal alloys

    Directory of Open Access Journals (Sweden)

    Mei-Eng Tu

    2011-06-01

    Conclusions: Metal alloys may induce multiple metal allergies. Patients suspected of having a metal allergy should be patch tested with an extended series of metals. We recommend adding palladium and gold, at least, to the standard series.

  6. Castable hot corrosion resistant alloy

    Science.gov (United States)

    Barrett, Charles A. (Inventor); Holt, William H. (Inventor)

    1988-01-01

    Some 10 wt percent nickel is added to an Fe-base alloy which has a ferrite microstructure to improve the high temperature castability and crack resistance while about 0.2 wt percent zirconium is added for improved high temperatur cyclic oxidation and corrosion resistance. The basic material is a high temperature FeCrAl heater alloy, and the addition provides a material suitable for burner rig nozzles.

  7. The microstructures of ordered alloys

    International Nuclear Information System (INIS)

    Sarma, G.M.K.; Ranganathan, S.

    1977-01-01

    The phenomenon of ordering in substitutional alloys confers special properties on them by introducing various types of structures and structural defects. Some of the important structural defects (translational and rotational antiphase boundaries, dissociated antiphase boundaries and superdislocations) and their observation by various microscopical methods, with particular emphasis on the applications of the electron microscope are described with illustrations drawn from the studies on nickel-molybdenum and nickel-tungsten alloys. (M.G.B.)

  8. Electrical conductivity in random alloys

    International Nuclear Information System (INIS)

    Mookerjee, A.; Yussouff, M.

    1983-06-01

    Starting from the augmented space formalism by one of us, and the use of the Ward identity and Bethe Salpeter equation, a complete formalism for the calculation of the electrical conductivity in tight-binding models of random binary alloys has been developed. The formalism is practical in the sense that viable calculations may be carried out with its help for realistics models of alloy systems. (author)

  9. Electrical conductivity in random alloys

    International Nuclear Information System (INIS)

    Mookerjee, A.; Thakur, P.K.; Yussouff, M.

    1984-12-01

    Based on the augmented space formalism introduced by one of us and the use of the Ward identity and the Bethe-Sapeter equation, a formalism has been developed for the calculation of electrical conductivity for random alloys. A simple application is made to a model case, and it is argued that the formalism enables us to carry out viable calculations on more realistic models of alloys. (author)

  10. Derivative spectrophotometry of cobalt alloys

    International Nuclear Information System (INIS)

    Spitsyn, P.K.

    1985-01-01

    The method of derivative spectrophotometry is briefly described, and derivative absorption spectra are presented for samarium, cobalt, and commercial Sm-Co alloys. It is shown that the use of derivative spectrophotometry not only improves the accuracy and selectivity of element determinations but also simplifies the analysis of alloys. Results of a statistical evaluation of the metrological characteristics of the analytical procedure described here are presented. 8 references

  11. Microstructural studies on Alloy 693

    Energy Technology Data Exchange (ETDEWEB)

    Halder, R.; Dutta, R.S. [Materials Science Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Sengupta, P., E-mail: praneshsengupta@gmail.com [Materials Science Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Samajdar, I. [Dept. of Metall. Engg. and Mater. Sci., Indian Institute of Technology Bombay, Mumbai 400 072 (India); Dey, G.K. [Materials Science Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)

    2014-10-15

    Superalloy 693, is a newly identified ‘high-temperature corrosion resistant alloy’. Present study focuses on microstructure and mechanical properties of the alloy prepared by double ‘vacuum melting’ route. In general, the alloy contains ordered Ni{sub 3}Al precipitates distributed within austenitic matrix. M{sub 6}C primary carbide, M{sub 23}C{sub 6} type secondary carbide and NbC particles are also found to be present. Heat treatment of the alloy at 1373 K for 30 min followed by water quenching (WQ) brings about a microstructure that is free from secondary carbides and Ni{sub 3}Al type precipitates but contains primary carbides. Tensile property of Alloy 693 materials was measured with as received and solution annealed (1323 K, 60 min, WQ) and (1373 K, 30 min, WQ) conditions. Yield strength, ultimate tensile strength (UTS) and hardness of the alloy are found to drop with annealing. It is noted that in annealed condition, considerable cold working of the alloy can be performed.

  12. Wettability of magnesium based alloys

    Science.gov (United States)

    Ornelas, Victor Manuel

    The premise of this project was to determine the wettability behavior of Mg-based alloys using three different liquids. Contact angle measurements were carried out along with utilizing the Zisman method for obtaining values for the critical surface tension. Adhesion energy values were also found through the use of the Young-Dupre equation. This project utilized the Mg-based alloy Mg-2Zn-2Gd with supplemented alpha-Minimum Essential Medium (MEM), Phosphate Buffer Saline solution (PBS), and distilled water. These three liquids are commonly used in cell cultivation and protein adsorption studies. Supplemented alpha-MEM consisted of alpha-MEM, fetal bovine serum, and penicillin-streptomycin. Mg-2Zn-2Gd was used because of observed superior mechanical properties and better corrosion resistance as compared to conventional Mg-alloys. These attractive properties have made it possible for this alloy to be used in biomedical devices within the human body. However, the successful use of this alloy system in the human body requires knowledge in the response of protein adsorption on the alloy surface. Protein adsorption depends on many parameters, but one of the most important factors is the wettability behavior at the surface.

  13. Alloy dissolution in argon stirred steel

    Science.gov (United States)

    Webber, Darryl Scott

    Alloying is required for the production of all steel products from small castings to large beams. Addition of large quantities of bulk alloys can result in alloy segregation and inconsistent alloy recovery. The objective of this research was to better understand alloy dissolution in liquid steel especially as it relates to Missouri S&Ts' patented continuous steelmaking process. A 45-kilogram capacity ladle with a single porous plug was used to evaluate the effect of four experimental factors on alloy dissolution: alloy species, alloy size or form, argon flow rate, and furnace tap temperature. Four alloys were tested experimentally including Class I low carbon ferromanganese, nickel and tin (as a surrogate for low melting alloys) and Class II ferroniobium. The alloys ranged in size and form from granular to 30 mm diameter lumps. Experimental results were evaluated using a theoretically based numerical model for the steel shell period, alloy mixing (Class I) and alloy dissolution (Class II). A CFD model of the experimental ladle was used to understand steel motion in the ladle and to provide steel velocity magnitudes for the numerical steel shell model. Experiments and modeling confirmed that smaller sized alloys have shorter steel shell periods and homogenize faster than larger particles. Increasing the argon flow rate shortened mixing times and reduced the delay between alloy addition and the first appearance of alloy in the melt. In addition, for every five degree increase in steel bath temperature the steel shell period was shortened by approximately four percent. Class II ferroniobium alloy dissolution was an order of magnitude slower than Class I alloy mixing.

  14. Corrosion Behaviour of New Zr Alloys

    DEFF Research Database (Denmark)

    Tolksdorf, E.

    1974-01-01

    Corrosion studies have indicated that the most promising replacements for Zicaloy-2 are ZrCrFe, ZrVFe and probably ZrNbTa, provided they are in their optimized condition. These alloys are conventionally manufactured alloys. An internally oxidized ZrMgO alloy is even superior, from the corrosion...... and hydrogen uptake points of view, to the above-mentioned alloys. This alloy is of particular interest because the addition of MgO leads to no neutron penalty and the dispersion-strengthening entails the possibility of tailoring an alloy with the desired mechanical properties....

  15. Corrosion of carbon-alloyed iron aluminides

    Indian Academy of Sciences (India)

    Unknown

    alloyed intermetallics were susceptible to galvanic corrosion, due to the presence of carbides. Keywords. Corrosion; iron aluminides; Fe3Al; potentiodynamic polarization. 1. Introduction. Ordered intermetallic alloys based on iron aluminides of.

  16. The comparison of corrosion resistance between Baosteel's alloy 690 tube and foreign alloy 690 tube

    International Nuclear Information System (INIS)

    Ma Mingjuan; Zhang Lefu; Li Yan

    2012-01-01

    Alloy 690 having excellent corrosion resistance is widely used for SG tubes. The intergranular corrosion and pitting corrosion resistance of Baosteel's alloy 690 tube, Country A alloy 690 tube and Country B alloy 690 tube have been analysed by comparison. It shows that: The intergranular corrosion of Baosteel's alloy 690 tube tested complied with ASTM G28 Standard could satisfy the technical requirement. However.some of Baosteel's alloy 690 tube in intergranular corrosion resistance had less performance than Country A. In addition, pitting corrosion tested with ASTM G48 Standard shown the Baosteel's alloy 690 tube better than Country B. (authors)

  17. Thermodynamic Database for Zirconium Alloys

    International Nuclear Information System (INIS)

    Jerlerud Perez, Rosa

    2003-05-01

    For many decades zirconium alloys have been commonly used in the nuclear power industry as fuel cladding material. Besides their good corrosion resistance and acceptable mechanical properties the main reason of using these alloys is the low neutron absorption. Zirconium alloys are exposed to a very severe environment during the nuclear fission process and there is a demand for better design of this material. To meet this requirement a thermodynamic database is developed to support material designers. In this thesis some aspects about the development of a thermodynamic database for zirconium alloys are presented. A thermodynamic database represents an important facility in applying thermodynamic equilibrium calculations for a given material providing: 1) relevant information about the thermodynamic properties of the alloys e.g. enthalpies, activities, heat capacity, and 2) significant information for the manufacturing process e.g. heat treatment temperature. The basic information in the database is first the unary data, i.e. pure elements; those are taken from the compilation of the Scientific Group Thermodata Europe (SGTE) and then the binary and ternary systems. All phases present in those binary and ternary systems are described by means of the Gibbs energy dependence on composition and temperature. Many of those binary systems have been taken from published or unpublished works and others have been assessed in the present work. All the calculations have been made using Thermo C alc software and the representation of the Gibbs energy obtained by applying Calphad technique

  18. New Theoretical Technique for Alloy Design

    Science.gov (United States)

    Ferrante, John

    2005-01-01

    During the last 2 years, there has been a breakthrough in alloy design at the NASA Lewis Research Center. A new semi-empirical theoretical technique for alloys, the BFS Theory (Bozzolo, Ferrante, and Smith), has been used to design alloys on a computer. BFS was used, along with Monte Carlo techniques, to predict the phases of ternary alloys of NiAl with Ti or Cr additions. High concentrations of each additive were used to demonstrate the resulting structures.

  19. Microstructural and technological optimisation of magnesium alloys

    OpenAIRE

    Facchinelli, Nicola

    2013-01-01

    Magnesium is one of the most abundance element in nature, and it's characterised by a lower density than aluminium. These characteristics confer great potential to magnesium alloys, which are so used for specialised applications, like for military purposes and in the aerospace industry. While some magnesium alloys, including the AM60B alloy, are historically associated to high pressure die casting, for such applications the magnesium alloy components are usually produced by the gravity castin...

  20. Self-disintegrating Raney metal alloys

    Science.gov (United States)

    Oden, Laurance L.; Russell, James H.

    1979-01-01

    A method of preparing a Raney metal alloy which is capable of self-disintegrating when contacted with water vapor. The self-disintegrating property is imparted to the alloy by incorporating into the alloy from 0.4 to 0.8 weight percent carbon. The alloy is useful in forming powder which can be converted to a Raney metal catalyst with increased surface area and catalytic activity.

  1. Fe-Cr-Ni system alloys

    International Nuclear Information System (INIS)

    Levin, F.L.

    1986-01-01

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

  2. PREPARATION OF URANIUM-ALUMINUM ALLOYS

    Science.gov (United States)

    Moore, R.H.

    1962-09-01

    A process is given for preparing uranium--aluminum alloys from a solution of uranium halide in an about equimolar molten alkali metal halide-- aluminum halide mixture and excess aluminum. The uranium halide is reduced and the uranium is alloyed with the excess aluminum. The alloy and salt are separated from each other. (AEC)

  3. Shape memory alloys – characterization techniques

    Indian Academy of Sciences (India)

    Abstract. Shape memory alloys are the generic class of alloys that show both thermal and mechan- ical memory. The basic physics involved in the shape memory effect is the reversible thermoelastic martensitic transformation. In general, there exists two phases in shape memory alloys, viz., a high- temperature phase or ...

  4. Shape memory alloys – characterization techniques

    Indian Academy of Sciences (India)

    Shape memory alloys are the generic class of alloys that show both thermal and mechanical memory. The basic physics involved in the shape memory effect is the reversible thermoelastic martensitic transformation. In general, there exists two phases in shape memory alloys, viz., a hightemperature phase or austenitic ...

  5. Impact toughness of laser surface alloyed Aluminium

    CSIR Research Space (South Africa)

    Mabhali, Luyolo AB

    2012-03-01

    Full Text Available Laser surface alloying of aluminium AA1200 was performed with a 4kW Nd:YAG laser and the impact resistance of the alloys was investigated. The alloying powders were a mixture of Ni, Ti and SiC in different proportions. Surfaces reinforced...

  6. Electrodeposition of engineering alloy coatings

    DEFF Research Database (Denmark)

    Christoffersen, Lasse

    Nickel based electrodeposited alloys were investigated with respect to their deposition process, heat treatment, hardness, corrosion resistance and combined wear-corrosion resistance. The investigated alloys were Ni-B, Ni-P and Ni-W, which are not fully developed for industrial utilisation...... at the moment. It was the intention of this study to investigate whether the mentioned alloy processes are able to substitute conventional deposition techniques for wear and corrosion resistance, namely Ni-P produced by electroless deposition and electrodeposited hard chromium. The considerations...... for substitution focussed on were increased deposition rates as well as improved corrosion and wear resistance.Some systems exhibited interesting deposition rates. Examples are 178 µm per hour of Ni-P(6), 85 µm per hour of Ni-P(15), 142 µm per hour of Ni-W(44) and 62 µm per hour of Ni-B(0.8) (weight percentages...

  7. Magnesium and related low alloys

    International Nuclear Information System (INIS)

    Bernard, J.; Caillat, R.; Darras, R.

    1959-01-01

    In the first part the authors examine the comparative corrosion of commercial magnesium, of a magnesium-zirconium alloy (0,4 per cent ≤ Zr ≤ 0,7 per cent) of a ternary magnesium-zinc-zirconium alloy (0,8 per cent ≤ Zn ≤ 1,2 per cent) and of english 'Magnox type' alloys, in dry carbon dioxide-free air, in damp carbon dioxide-free air, and in dry and damp carbon dioxide, at temperatures from 300 to 600 deg. C. In the second part the structural stability of these materials is studied after annealings, of 10 to 1000 hours at 300 to 450 deg. C. Variations in grain after these heat treatments and mechanical stretching properties at room temperature are presented. Finally various creep rate and life time diagrams are given for these materials, for temperatures ranging from 300 to 450 deg. C. (author) [fr

  8. Phosphorus containing sintered alloys (review)

    International Nuclear Information System (INIS)

    Muchnik, S.V.

    1984-01-01

    Phosphorus additives are considered for their effect on the properties of sintered alloys of different applications: structural, antifriction, friction, magnetic, hard, superhard, heavy etc. Data are presented on compositions and properties of phosphorus-containing materials produced by the powder metallurgy method. Phosphorus is shown to be an effective activator of sintering in some cases. When its concentration in the material is optimal it imparts the material such properties as strength, viscosity, hardness, wear resistance. Problems concerning powder metallurgy of amorphous phosphorus-containing alloys are reported

  9. 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

  10. Theoretical studies of metallic alloys

    International Nuclear Information System (INIS)

    Faulkner, J.S.; Wille, L.T.

    1991-07-01

    A new method to predict and understand the structure and phase stability of solid-solution alloys from a knowledge only of the atomic numbers of the constituent atoms is being developed. The coherent potential approximation will be used to obtain the electronic contribution to the energy and the Monte Carlo method of statistical mechanics will be used for the thermodynamic part of the calculation. An improved coherent potential approximation will be developed by combining the standard approach with the quadratic KKR (QKKR) band theory method. This will make it easier to predict the properties of alloys from first principles. The QKKR method will be developed further

  11. ALLOY DESIGN AND PROPERTY EVALUATION OF TI ALLOY ...

    African Journals Online (AJOL)

    eobe

    Abstract. Ti-Mo alloy containing Nb and Sn were arc melted and composition analyzed by EDX. The XRD analysis indicates that the crystal structure and mechanical properties are sensitive to Sn concentration. A combination of Sn and Nb elements in synergy hindered formation athermal ω phase and significantly.

  12. An introduction to surface alloying of metals

    CERN Document Server

    Hosmani, Santosh S; Goyal, Rajendra Kumar

    2014-01-01

    An Introduction to Surface Alloying of Metals aims to serve as a primer to the basic aspects of surface alloying of metals. The book serves to elucidate fundamentals of surface modification and their engineering applications. The book starts with basics of surface alloying and goes on to cover key surface alloying methods, such as carburizing, nitriding, chromizing, duplex treatment, and the characterization of surface layers. The book will prove useful to students at both the undergraduate and graduate levels, as also to researchers and practitioners looking for a quick introduction to surface alloying.

  13. Nd:YAG laser welding aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez, E. Jr.

    1992-02-01

    Autogenous Nd:YAG laser welding wrought 4047, 1100, 3003, 2219, 5052, 5086, 5456, and 6061 and cast A356 aluminum alloys to cast A356 aluminum alloy in restrained annular weld joints was investigated. The welds were 12.7 mm (0.375 in.) and 9.5 mm (0.375 in.) diameter with approximately 0.30 mm (0.012 in.) penetration. This investigation determined 4047 aluminum alloy to be the optimum alloy for autogenous Nd:YAG laser welding to cast A356 aluminum alloy. This report describes the investigation and its results.

  14. Optical Characterization of AlAsSb Digital Alloy and Random Alloy on GaSb

    Directory of Open Access Journals (Sweden)

    Bor-Chau Juang

    2017-10-01

    Full Text Available III-(As, Sb alloys are building blocks for various advanced optoelectronic devices, but the growth of their ternary or quaternary materials are commonly limited by spontaneous formation of clusters and phase separations during alloying. Recently, digital alloy growth by molecular beam epitaxy has been widely adopted in preference to conventional random alloy growth because of the extra degree of control offered by the ordered alloying. In this article, we provide a comparative study of the optical characteristics of AlAsSb alloys grown lattice-matched to GaSb using both techniques. The sample grown by digital alloy technique showed stronger photoluminescence intensity, narrower peak linewidth, and larger carrier activation energy than the random alloy technique, indicating an improved optical quality with lower density of non-radiative recombination centers. In addition, a relatively long carrier lifetime was observed from the digital alloy sample, consistent with the results obtained from the photoluminescence study.

  15. Mechanical properties of biomedical titanium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Niinomi, M. [Toyohashi Univ. of Technol. (Japan). Sch. of Production Syst. Eng.

    1998-03-15

    Titanium alloys are expected to be much more widely used for implant materials in the medical and dental fields because of their superior biocompatibility, bioaffinity, corrosion resistance and specific strength compared with other metallic implant materials. Pure titanium and Ti-6Al-4V, in particular, Ti-6Al-4V ELI have been, however, mainly used for implant materials among various titanium alloys to date. V free alloys like Ti-6Al-7Nb and Ti-5Al-2.5Fe have been recently developed for biomedical use. More recently V and Al free alloys have been developed. Titanium alloys composed of non-toxic elements like Nb, Ta, Zr and so on with lower modulus have been started to be developed mainly in the USA. The {beta} type alloys are now the main target for medical materials. The mechanical properties of the titanium alloys developed for implant materials to date are described in this paper. (orig.) 17 refs.

  16. Requirements of titanium alloys for aeronautical industry

    Science.gov (United States)

    Ghiban, Brânduşa; Bran, Dragoş-Teodor; Elefterie, Cornelia Florina

    2018-02-01

    The project presents the requirements imposed for aeronatical components made from Titanium based alloys. Asignificant portion of the aircraft pylons are manufactured from Titanium alloys. Strength, weight, and reliability are the primary factors to consider in aircraft structures. These factors determine the requirements to be met by any material used to construct or repair the aircraft. Many forces and structural stresses act on an aircraft when it is flying and when it is static and this thesis describes environmental factors, conditions of external aggression, mechanical characteristics and loadings that must be satisfied simultaneously by a Ti-based alloy, compared to other classes of aviation alloys (as egg. Inconel super alloys, Aluminum alloys). For this alloy class, the requirements are regarding strength to weight ratio, reliability, corrosion resistance, thermal expansion and so on. These characteristics additionally continue to provide new opportunities for advanced manufacturing methods.

  17. 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.)

  18. Applications of shape memory alloys in Japan

    International Nuclear Information System (INIS)

    Asai, M.; Suzuki, Y.

    2000-01-01

    In Japan, a first application of shape memory TiNi alloy was a moving flap in an air-conditioner which was developed as sensing function of shape memory alloy at Matsushista Electric Industrial Co. Then, shape memory utilized in a coffee maker, an electric rice-cooker, a thermal mixing valve and etc. were commercialized in Japan. And brassiere wires, a guide wire for medical treatment, an antenna for portable telephone and others were commercialized utilizing superelasticity. At the same time with these commercial products, there was not only progress in fabrication technology to effect accurate transformation temperature, but also the discovery of small hysteresis alloy such as R-phase or TiNiCu alloy and low transformation temperature alloy such as TiNiFe, TiNiV and TiNiCo alloys. Therefore the shape memory alloy market has expanded widely to electric appliances, automobile, residence, medical care and other field today. (orig.)

  19. Aeronautical Industry Requirements for Titanium Alloys

    Science.gov (United States)

    Bran, D. T.; Elefterie, C. F.; Ghiban, B.

    2017-06-01

    The project presents the requirements imposed for aviation components made from Titanium based alloys. A significant portion of the aircraft pylons are manufactured from Titanium alloys. Strength, weight, and reliability are the primary factors to consider in aircraft structures. These factors determine the requirements to be met by any material used to construct or repair the aircraft. Many forces and structural stresses act on an aircraft when it is flying and when it is static and this thesis describes environmental factors, conditions of external aggression, mechanical characteristics and loadings that must be satisfied simultaneously by a Ti-based alloy, compared to other classes of aviation alloys (as egg. Inconel super alloys, Aluminum alloys).For this alloy class, the requirements are regarding strength to weight ratio, reliability, corrosion resistance, thermal expansion and so on. These characteristics additionally continue to provide new opportunities for advanced manufacturing methods.

  20. Passive Corrosion Behavior of Alloy 22

    International Nuclear Information System (INIS)

    R.B. Rebak; J.H. Payer

    2006-01-01

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

  1. Magnetic alloys with vanishing anisotropies

    International Nuclear Information System (INIS)

    Couderchon, G.

    1991-01-01

    Co-based amorphous alloys and 80 Ni Permalloys have vanishingly-low anisotropies and show the highest permeabilities and lowest losses among commercial magnetic materials. In spit of their different atomic arrangements, these two types of material show close similarities in domain structure and in their temperature and frequency behavior. Information is also given concerning material technology and applications. (orig.)

  2. Iron-nickel-chromium alloys

    International Nuclear Information System (INIS)

    Karenko, M.K.

    1981-01-01

    A specification is given for iron-nickel-chromium age-hardenable alloys suitable for use in fast breeder reactor ducts and cladding, which utilize the gamma-double prime strengthening phase and are characterized in having a delta or eta phase distributed at or near grain boundaries. A range of compositions is given. (author)

  3. Palladium alloys for hydrogen diffusion

    International Nuclear Information System (INIS)

    1977-01-01

    A palladium-base alloy with tin and/or a silicon addition and its use in the production of hydrogen from water via a cycle of chemical reactions, of which the decomposition of HI into H 2 and I 2 is the most important, is described

  4. Electroless alloy/composite coatings

    Indian Academy of Sciences (India)

    The market for these coatings is expanding fast as the potential applications are on the rise. In the present article, an attempt has been made to review different electroless alloy/composite coatings with respect to bath types and their composition, properties and applications. Different characterisation studies have been ...

  5. Nickel, cobalt, and their alloys

    CERN Document Server

    2000-01-01

    This book is a comprehensive guide to the compositions, properties, processing, performance, and applications of nickel, cobalt, and their alloys. It includes all of the essential information contained in the ASM Handbook series, as well as new or updated coverage in many areas in the nickel, cobalt, and related industries.

  6. Heat treatment of nickel alloys

    International Nuclear Information System (INIS)

    Smith, D.F. Jr.; Clatworthy, E.F.

    1975-01-01

    A heat treating process is described that can be used to produce desired combinations of strength, ductility, and fabricability characteristics in heat resistant age-hardenable alloys having precipitation-hardening amounts of niobium, titanium, and/or tantalum in a nickel-containing matrix. (U.S.)

  7. Shape memory alloy based motor

    Indian Academy of Sciences (India)

    (Duerig et al 1990) of the alloy. Unlike conventional materials, which show only, limited effect on stress–strain behaviour (Duerig et al 1990; Mellor 1989), SMA shows marked temperature dependence, because of reversible austenite to martensite transformation. The underlying phenomenon of the shape memory effect is ...

  8. Hydrostatic extrusion of magnesium alloys

    NARCIS (Netherlands)

    Sillekens, W.H.; Bohlen, J.

    2012-01-01

    This chapter deals with the capabilities and limitations of the hydrostatic extrusion process for the manufacturing of magnesium alloy sections. Firstly, the process basics for the hydrostatic extrusion of materials in general and of magnesium in particular are introduced. Next, some recent research

  9. 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)

  10. Oxide characterization and hydrogen behaviors of Zr-based alloys

    International Nuclear Information System (INIS)

    Kim, Y. S.; Kim, D. J.; Kwon, S. H.; Lee, H. S.; Oh, S. J.; Yim, B. J.; Son, S. B.; Yun, S. P.

    2006-03-01

    The work scope and contents of the research are as follows : basic properties of zirconium alloys, hydrogen pick-up mechanism of zirconium alloy, effects of hydride on the corrosion behaviors of zirconium alloys, estimation on stress of oxide layer in the zirconium alloy, microstructure and characteristic of oxide in pre-hydrided zirconium alloys

  11. PERSPECTIVES OF MOLIBDENUM CONTAINING MATERIALS APPLICATION FOR ALLOYING OF IRONCARBON ALLOYS DURING MANUFACTURING OF CRITICAL CASTINGS

    Directory of Open Access Journals (Sweden)

    A. G. Slutsky

    2015-01-01

    Full Text Available Motor is one of most important part of automobile determine its economical effectiveness of usage. On the other hand, sleeves, pistons and rings are crucible parts as they determine the service life of a motor. These parts are producing in big scale – dozens of millions pieces. Increase of cylinder sleeves physical-mechanical properties results in prolongation of motor service life and improvement of motor’s characteristics. Nowadays low alloyed cast irons with perlite structure are used to manufacture motor’s sleeves. For alloying purposes such traditional elements as Cr, Ni, Cu, and V are applied. But it is interesting to use molybdenum for cast iron alloying. It is known that alloying of alloys allows considerable increasing of consumption properties of castings. But in spite of advantages of alloys alloying the increase of molybdenum containing iron-carbon alloys production is restricted by economical reasons – high cost of alloying additions. Expenditures on alloying additions can be reduced by the application cheap secondary alloys in the charge. So, the present paper is devoted to investigation of alloying peculiarities during the treatment of ferrous alloys with molybdenum applying different initial materials.

  12. Novel antibacterial biodegradable Fe-Mn-Ag alloys produced by mechanical alloying.

    Science.gov (United States)

    Sotoudehbagha, Pedram; Sheibani, Saeed; Khakbiz, Mehrdad; Ebrahimi-Barough, Somayeh; Hermawan, Hendra

    2018-07-01

    Various compositions and synthesis methods of biodegradable iron-based alloys have been studied aiming for the use of temporary medical implants. However, none is focused on nano-structured alloy and on adding antibacterial property to the alloy. In this study, new Fe-30Mn-(1-3)Ag alloys were synthesized by means of mechanical alloying and assessed for their microstructure, mechanical properties, corrosion rate, antibacterial activity and cytotoxicity. Results showed that the alloy with 3 wt% Ag content displayed the highest relative density, shear strength, micro hardness and corrosion rate. However, optimum cytotoxicity and the antibacterial activity were reached by the alloy with 1 wt% Ag content. The compositional and processing effects of the alloys' properties are further discussed in this work. Copyright © 2018 Elsevier B.V. All rights reserved.

  13. Preparation of TiMn alloy by mechanical alloying and spark plasma sintering for biomedical applications

    Science.gov (United States)

    Zhang, F.; Weidmann, A.; Nebe, B. J.; Burkel, E.

    2009-01-01

    TiMn alloy was prepared by mechanical alloying and subsequently consolidated by spark plasma sintering (SPS) technique for exploration of biomedical applications. The microstructures, mechanical properties and cytotoxicity of the TiMn alloys were investigated in comparison with the pure Ti and Mn metals. Ti8Mn and Ti12Mn alloys with high relative density (99%) were prepared by mechanical alloying for 60 h and SPS at 700 °C for 5 min. The doping of Mn in Ti has decreased the transformation temperature from α to β phase, increased the relative density and enhanced the hardness of the Ti metal significantly. The Ti8Mn alloys showed 86% cell viability which was comparable to that of the pure Ti (93%). The Mn can be used as a good alloying element for biomedical Ti metal, and the Ti8Mn alloy could have a potential use as bone substitutes and dental implants.

  14. Investigation on mechanical alloying process for v-cr-ti alloys

    International Nuclear Information System (INIS)

    Stanciulescu, M.; Carlan, P.; Mihalache, M.; Bucsa, G.; Abrudeanu, M.; Galateanu, A.

    2015-01-01

    Mechanical alloying (MA) is an efficient approach for fabricating oxide-dispersion alloys and structural materials including vanadium alloys for fusion and fission application. Dissolution behaviour of the alloying elements is a key issue for optimizing the mechanical alloying process in fabricating vanadium alloys. This paper studies the MA process of V-4wt.%Cr-4wt.%Ti alloy. The outcomes of the MA powders in a planetary ball mill are reported in terms of powder particle size and morphology evolution and elemental composition. The impact of spark-plasma sintering process on the mechanically alloyed powder is analysed. An optimal set of sintering parameters, including the maximum temperature, the dwell time and the heating rate are determined. (authors)

  15. Corrosion resistance of titanium alloys for dentistry

    International Nuclear Information System (INIS)

    Laskawiec, J.; Michalik, R.

    2001-01-01

    Titanium and its alloys belong to biomaterials which the application scope in medicine increases. Some properties of the alloys, such as high mechanical strength, low density, low Young's modulus, high corrosion resistance and good biotolerance decide about it. The main areas of the application of titanium and its alloys are: orthopedics and traumatology, cardiosurgery, faciomaxillary surgery and dentistry. The results of investigations concerning the corrosion resistance of the technical titanium and Ti6Al14V alloy and comparatively a cobalt alloy of the Vitallium type in the artificial saliva is presented in the work. Significantly better corrosion resistance of titanium and the Ti6Al14V than the Co-Cr-Mo alloy was found. (author)

  16. Bulk amorphous Mg-based alloys

    DEFF Research Database (Denmark)

    Pryds, Nini

    2004-01-01

    The present paper describes the preparation and properties of bulk amorphous quarternary Mg-based alloys and the influence of additional elements on the ability of the alloy to form bulk amorphous. The main goal is to find a Mg-based alloy system which shows both high strength to weight ratio...... and a low glass transition temperature. The alloys were prepared by using a relatively simple technique, i.e. rapid cooling of the melt in a copper wedge mould. The essential structural changes that are achieved by going from the amorphous to the crystalline state through the supercooled liquid state...... are discussed in this paper. On the basis of these measurements phase diagrams of the different systems were constructed. Finally, it is demonstrated that when pressing the bulk amorphous alloy onto a metallic dies at temperatures within the supercooled liquid region, the alloy faithfully replicates the surface...

  17. Theory of Random Anisotropic Magnetic Alloys

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    1976-01-01

    A mean-field-crystal-field theory is developed for random, multicomponent, anisotropic magnetic alloys. It is specially applicable to rare-earth alloys. A discussion is given of multicritical points and phase transitions between various states characterized by order parameters with different...... spatial directions or different ordering wave vectors. Theoretical predictions based on known parameters for the phase diagrams and magnetic moments for the binary rare-earth alloys of Tb, Dy, Ho, and Er, Tb-Tm, Nd-Pr, and pure double-hcp Nd agree qualitatively with the experimental observations....... Quantitative agreement can be obtained by increasing the interaction between different alloy elements, in particular for alloys with very different axial anisotropy, e.g., Tb-Tm. A model system consisting of a singlet-singlet and singlet-doublet alloy is discussed in detail. A simple procedure to include...

  18. Anodic oxidation of Ta/Fe alloys

    International Nuclear Information System (INIS)

    Mato, S.; Alcala, G.; Thompson, G.E.; Skeldon, P.; Shimizu, K.; Habazaki, H.; Quance, T.; Graham, M.J.; Masheder, D.

    2003-01-01

    The behaviour of iron during anodizing of sputter-deposited Ta/Fe alloys in ammonium pentaborate electrolyte has been examined by transmission electron microscopy, Rutherford backscattering spectroscopy, glow discharge optical emission spectroscopy and X-ray photoelectron spectroscopy. Anodic films on Ta/1.5 at.% Fe, Ta/3 at.% Fe and Ta/7 at.% Fe alloys are amorphous and featureless and develop at high current efficiency with respective formation ratios of 1.67, 1.60 and 1.55 nm V -1 . Anodic oxidation of the alloys proceeds without significant enrichment of iron in the alloy in the vicinity of the alloy/film interface and without oxygen generation during film growth, unlike the behaviour of Al/Fe alloys containing similar concentrations of iron. The higher migration rate of iron species relative to that of tantalum ions leads to the formation of an outer iron-rich layer at the film surface

  19. Swelling in neutron-irradiated titanium alloys

    International Nuclear Information System (INIS)

    Peterson, D.T.

    1982-04-01

    Immersion density measurements have been performed on a series of titanium alloys irradiated in EBR-II to a fluence of 5 x 10 22 n/cm 2 (E > 0.1 MeV) at 450 and 550 0 C. The materials irradiated were the near-alpha alloys Ti-6242S and Ti-5621S, the alpha-beta alloy Ti-64, and the beta alloy Ti-38644. Swelling was observed in all alloys with the greater swelling being observed at 550 0 C. Microstructural examination revealed the presence of voids in all alloys. Ti-38644 was found to be the most radiation resistant. Ti-6242S and Ti-5621S also displayed good radiation resistance, whereas considerable swelling and precipitation were observed in Ti-64 at 550 0 C

  20. Annealing behavior of high permeability amorphous alloys

    International Nuclear Information System (INIS)

    Rabenberg, L.

    1980-06-01

    Effects of low temperature annealing on the magnetic properties of the amorphous alloy Co 71 4 Fe 4 6 Si 9 6 B 14 4 were investigated. Annealing this alloy below 400 0 C results in magnetic hardening; annealing above 400 0 C but below the crystallization temperature results in magnetic softening. Above the crystallization temperature the alloy hardens drastically and irreversibly. Conventional and high resolution transmission electron microscopy were used to show that the magnetic property changes at low temperatures occur while the alloy is truly amorphous. By imaging the magnetic microstructures, Lorentz electron microscopy has been able to detect the presence of microscopic inhomogeneities in this alloy. The low temperature annealing behavior of this alloy has been explained in terms of atomic pair ordering in the presence of the internal molecular field. Lorentz electron microscopy has been used to confirm this explanation

  1. Phonons in fcc binary alloys

    International Nuclear Information System (INIS)

    Sharma, Amita; Rathore, R.P.S.

    1992-01-01

    Born-Mayer potential has been modified to account for the unpaired (three body) forces among the common nearest neighbours of the ordered binary fcc alloys i.e. Ni 3 Fe 7 , Ni 5 Fe 5 and Ni 75 Fe 25 . The three body potential is added to the two body form of Morse to formalize the total interaction potential. Measured inverse ionic compressibility, cohesive energy, lattice constant and one measured phonon frequency are used to evaluate the defining parameters of the potential. The potential seeks to bring about the binding among 140 and 132 atoms though pair wise (two body) and non-pair wise (three body) forces respectively. The phonon-dispersion relations obtained by solving the secular equation are compared with the experimental findings on the aforesaid alloys. (author). 19 refs., 3 figs

  2. Heat storage in alloy transformations

    Science.gov (United States)

    Birchenall, C. E.

    1980-01-01

    Heats of transformation of eutectic alloys were measured for many binary and ternary systems by differential scanning calorimetry and thermal analysis. Only the relatively cheap and plentiful elements Mg, Al, Si, P, Ca, Cu, Zn were considered. A method for measuring volume change during transformation was developed using x-ray absorption in a confined sample. Thermal expansion coefficients of both solid and liquid states of aluminum and of its eutectics with copper and with silicon also were determined. Preliminary evaluation of containment materials lead to the selection of silicon carbide as the initial material for study. Possible applications of alloy PCMs for heat storage in conventional and solar central power stations, small solar receivers and industrial furnace operations are under consideration.

  3. Magnesium-titanium alloys for biomedical applications

    Science.gov (United States)

    Hoffmann, Ilona

    Magnesium has been identified as a promising biodegradable implant material because it does not cause systemic toxicity and can reduce stress shielding. However, it corrodes too quickly in the body. Titanium, which is already used ubiquitously for implants, was chosen as the alloying element because of its proven biocompatibility and corrosion resistance in physiological environments. Thus, alloying magnesium with titanium is expected to improve the corrosion resistance of magnesium. Mg-Ti alloys with a titanium content ranging from 5 to 35 at.-% were successfully synthesized by mechanical alloying. Spark plasma sintering was identified as a processing route to consolidate the alloy powders made by ball-milling into bulk material without destroying the alloy structure. This is an important finding as this metastable Mg-Ti alloy can only be heated up to max. 200C° for a limited time without reaching the stable state of separated magnesium and titanium. The superior corrosion behavior of Mg 80-Ti20 alloy in a simulated physiological environment was shown through hydrogen evolution tests, where the corrosion rate was drastically reduced compared to pure magnesium and electrochemical measurements revealed an increased potential and resistance compared to pure magnesium. Cytotoxicity tests on murine pre-osteoblastic cells in vitro confirmed that supernatants made from Mg-Ti alloy were no more cytotoxic than supernatants prepared with pure magnesium. Mg and Mg-Ti alloys can also be used to make novel polymer-metal composites, e.g., with poly(lactic-co-glycolic acid) (PLGA) to avoid the polymer's detrimental pH drop during degradation and alter its degradation pattern. Thus, Mg-Ti alloys can be fabricated and consolidated while achieving improved corrosion resistance and maintaining cytocompatibility. This work opens up the possibility of using Mg-Ti alloys for fracture fixation implants and other biomedical applications. KEYWORDS: Magnesium, titanium, corrosion

  4. FE-based long range ordered alloys

    International Nuclear Information System (INIS)

    Liu, C.-T.; Inouye, H.; Schaffhauser, A.C.

    1981-01-01

    Malleable long range ordered alloys having high critical ordering temperatures exist in the V(Co,Fe) 3 and V(Co,Fe,Ni) 3 system having a specified composition with an electron density no greater than 8.00. Excellent high temperature properties occur in alloys in this system, having specified compositions. The alloys are fabricable by casting, deforming and annealing for sufficient time to provide ordered structure. (author)

  5. Alloy nanoparticle synthesis using ionizing radiation

    Science.gov (United States)

    Nenoff, Tina M [Sandia Park, NM; Powers, Dana A [Albuquerque, NM; Zhang, Zhenyuan [Durham, NC

    2011-08-16

    A method of forming stable nanoparticles comprising substantially uniform alloys of metals. A high dose of ionizing radiation is used to generate high concentrations of solvated electrons and optionally radical reducing species that rapidly reduce a mixture of metal ion source species to form alloy nanoparticles. The method can make uniform alloy nanoparticles from normally immiscible metals by overcoming the thermodynamic limitations that would preferentially produce core-shell nanoparticles.

  6. The oxidation and corrosion of ODS alloys

    Science.gov (United States)

    Lowell, Carl E.; Barrett, Charles A.

    1990-01-01

    The oxidation and hot corrosion of high temperature oxide dispersion strengthened (ODS) alloys are reviewed. The environmental resistance of such alloys are classified by oxide growth rate, oxide volatility, oxide spalling, and hot corrosion limitations. Also discussed are environmentally resistant coatings for ODS materials. It is concluded that ODS NiCrAl and FeCrAl alloys are highly oxidation and corrosion resistant and can probably be used uncoated.

  7. Characterization of aluminium alloys rapidly solidified

    International Nuclear Information System (INIS)

    Monteiro, W.A.

    1988-01-01

    This paper discussed the investigation of the microstructural and mechanical properties of the aluminium alloys (3003; 7050; Al-9% Mg) rapidly solidified by melt spinning process (cooling rate 10 4 - 10 6 K/s). The rapidly solidification process of the studied aluminium alloys brought a microcrystallinity, a minimum presence of coarse precipitation and, also, better mechanical properties of them comparing to the same alloys using ingot process. (author) [pt

  8. Recent developments in advanced aircraft aluminium alloys

    International Nuclear Information System (INIS)

    Dursun, Tolga; Soutis, Costas

    2014-01-01

    Highlights: • To compete with composites, performance of aluminium alloys should be increased. • Al–Li alloys have higher strength, fracture and fatigue/corrosion resistance. • Improvements of aerospace Al alloys are due to optimised solute content and ratios. • In selecting new materials, there should be no reduction in the level of safety. • The use of hybrid materials could provide additional opportunities for Al alloys. - Abstract: Aluminium alloys have been the primary material for the structural parts of aircraft for more than 80 years because of their well known performance, well established design methods, manufacturing and reliable inspection techniques. Nearly for a decade composites have started to be used more widely in large commercial jet airliners for the fuselage, wing as well as other structural components in place of aluminium alloys due their high specific properties, reduced weight, fatigue performance and corrosion resistance. Although the increased use of composite materials reduced the role of aluminium up to some extent, high strength aluminium alloys remain important in airframe construction. Aluminium is a relatively low cost, light weight metal that can be heat treated and loaded to relatively high level of stresses, and it is one of the most easily produced of the high performance materials, which results in lower manufacturing and maintenance costs. There have been important recent advances in aluminium aircraft alloys that can effectively compete with modern composite materials. This study covers latest developments in enhanced mechanical properties of aluminium alloys, and high performance joining techniques. The mechanical properties on newly developed 2000, 7000 series aluminium alloys and new generation Al–Li alloys are compared with the traditional aluminium alloys. The advantages and disadvantages of the joining methods, laser beam welding and friction stir welding, are also discussed

  9. Advanced powder metallurgy aluminum alloys and composites

    Science.gov (United States)

    Lisagor, W. B.; Stein, B. A.

    1982-01-01

    The differences between powder and ingot metallurgy processing of aluminum alloys are outlined. The potential payoff in the use of advanced powder metallurgy (PM) aluminum alloys in future transport aircraft is indicated. The national program to bring this technology to commercial fruition and the NASA Langley Research Center role in this program are briefly outlined. Some initial results of research in 2000-series PM alloys and composites that highlight the property improvements possible are given.

  10. PREPARATION OF ACTINIDE-ALUMINUM ALLOYS

    Science.gov (United States)

    Moore, R.H.

    1962-09-01

    BS>A process is given for preparing alloys of aluminum with plutonium, uranium, and/or thorium by chlorinating actinide oxide dissolved in molten alkali metal chloride with hydrochloric acid, chlorine, and/or phosgene, adding aluminum metal, and passing air and/or water vapor through the mass. Actinide metal is formed and alloyed with the aluminum. After cooling to solidification, the alloy is separated from the salt. (AEC)

  11. Microstructural characterization of EXCEL alloy

    International Nuclear Information System (INIS)

    Oroza Z E, Celiz; Saumell M, Lani; Versaci, R A; Bozzano, P B

    2012-01-01

    The microstructure of Excel alloy was studied by optical and scanning electron microscopy. X-ray diffraction was used to analyze the present phases. Characteristic peaks of α-Zr (HCP), β-Zr (BCC) and δhydride (FCC) were identified. The high relatives intensities of certain peaks suggest that samples are textured. Basal poles were dominant in radial-longitudinal planes and prismatic poles have the highest concentration in radial-tangential planes (author)

  12. Thermally activated martensite formation in ferrous alloys

    DEFF Research Database (Denmark)

    Villa, Matteo; Somers, Marcel A. J.

    2017-01-01

    Magnetometry was applied to investigate the formation of α/α´martensite in 13ferrous alloys during immersion in boiling nitrogen and during re-heating to room temperature at controlled heating rates in the range 0.0083-0.83 K s-1. Data showsthat in 3 of the alloys, those that form {5 5 7}γ...... martensite, no martensite developsduring cooling. For all investigated alloys, irrespective of the type of martensiteforming, thermally activated martensite develops during heating. The activationenergy for thermally activated martensite formation is in the range 8‒27 kJ mol-1and increases with the fraction...... of interstitial solutes in the alloy...

  13. 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

  14. Synthesis of shape memory alloys using electrodeposition

    Science.gov (United States)

    Hymer, Timothy Roy

    Shape memory alloys are used in a variety of applications. The area of micro-electro-mechanical systems (MEMS) is a developing field for thin film shape memory alloys for making actuators, valves and pumps. Until recently thin film shape memory alloys could only be made by rapid solidification or sputtering techniques which have the disadvantage of being "line of sight". At the University of Missouri-Rolla, electrolytic techniques have been developed that allow the production of shape memory alloys in thin film form. The advantages of this techniques are in-situ, non "line of sight" and the ability to make differing properties of the shape memory alloys from one bath. This research focused on the electrodeposition of In-Cd shape memory alloys. The primary objective was to characterize the electrodeposited shape memory effect for an electrodeposited shape memory alloy. The effect of various operating parameters such as peak current density, temperature, pulsing, substrate and agitation were investigated and discussed. The electrodeposited alloys were characterized by relative shape memory effect, phase transformation, morphology and phases present. Further tests were performed to optimize the shape memory by the use of a statistically designed experiment. An optimized shape memory effect for an In-Cd alloy is reported for the conditions of the experiments.

  15. Titanium alloys Russian aircraft and aerospace applications

    CERN Document Server

    Moiseyev, Valentin N

    2005-01-01

    This text offers previously elusive information on state-of-the-art Russian metallurgic technology of titanium alloys. It details their physical, mechanical, and technological properties, as well as treatments and applications in various branches of modern industry, particularly aircraft and aerospace construction. Titanium Alloys: Russian Aircraft and Aerospace Applications addresses all facets of titanium alloys in aerospace and aviation technology, including specific applications, fundamentals, composition, and properties of commercial alloys. It is useful for all students and researchers interested in the investigation and applications of titanium.

  16. Liquid metal corrosion considerations in alloy development

    International Nuclear Information System (INIS)

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

    1984-01-01

    Liquid metal corrosion can be an important consideration in developing alloys for fusion and fast breeder reactors and other applications. Because of the many different forms of liquid metal corrosion (dissolution, alloying, carbon transfer, etc.), alloy optimization based on corrosion resistance depends on a number of factors such as the application temperatures, the particular liquid metal, and the level and nature of impurities in the liquid and solid metals. The present paper reviews the various forms of corrosion by lithium, lead, and sodium and indicates how such corrosion reactions can influence the alloy development process

  17. Elaboration of a Mn-Ni alloy

    International Nuclear Information System (INIS)

    Meny, L.

    1957-06-01

    The manganese-nickel alloy with a high manganese content is used to produce very low thickness sensors for the measurement of neutron flows in a reactor. The author reports the elaboration of such an alloy with a 75 per cent content of manganese and 25 per cent content of nickel, by using a powder metallurgy approach. Purity and homogeneity were looked for more than good mechanical properties. In this note, the author presents the alloy fabrication apparatus, and reports some properties of sheets produced with this alloy

  18. Characterization of a NIMONIC TYPE super alloy

    International Nuclear Information System (INIS)

    Zamora Rangel, L.; Martinez Martinez, E.

    1985-01-01

    Mechanical properties of strength and thermofluence of a NIMONIC type super alloy under thermal treatment was determined. The relationship between microstructure, phases and precipitates was also studied. (author)

  19. Use of low fusing alloy in dentistry.

    Science.gov (United States)

    Wee, A G; Schneider, R L; Aquilino, S A

    1998-11-01

    Low fusing alloy has been used in dentistry for remount procedures in both fixed and removable prosthodontics, in implant prosthodontics for the fabrication of solid implant casts, in maxillofacial prosthetics as oral radiation shields, and in dental research for its unique properties. Previously, the use of low fusing alloy was thought to offer a high degree of dimensional accuracy. However, multiple in vitro studies have shown that its presumed dimensional accuracy may be questionable. This article reviews the physical properties, metallurgical considerations of low fusing alloy, its applications in dentistry, and a safe, simple method of using low fusing alloy.

  20. Nondestructive determination of mechanical properties. [aluminum alloys

    Science.gov (United States)

    Schneider, E.; Chu, S. L.; Salma, K.

    1984-01-01

    Aluminum alloys of types 1100, 3003, 5052, 6061, and 2024 were used to study the sensitivity of the acousto-elastic constant to changes in the microstructure. Results show that there is a strong relationship between the acousto-elastic constants and the yield strength and hardness. This relationship depends on whether the alloy is strain hardened or precipitation hardened. In strain hardened alloys, the constants increase as the amount of solid solution is decreased, while the behavior is the opposite in precipitation hardened alloys.

  1. Application of mechanical alloying to synthesis of intermetallic phases based alloys

    International Nuclear Information System (INIS)

    Dymek, S.

    2001-01-01

    Mechanical alloying is the process of synthesis of powder materials during milling in high energetic mills, usually ball mills. The central event in mechanical alloying is the ball-powder-ball collision. Powder particles are trapped between the colliding balls during milling and undergo deformation and/or fracture. Fractured parts are cold welded. The continued fracture and cold welding results in a uniform size and chemical composition of powder particles. The main applications of mechanical alloying are: processing of ODS alloys, syntheses of intermetallic phases, synthesis of nonequilibrium structures (amorphous alloys, extended solid solutions, nanocrystalline, quasi crystals) and magnetic materials. The present paper deals with application of mechanical alloying to synthesis Ni A l base intermetallic phases as well as phases from the Nb-Al binary system. The alloy were processed from elemental powders. The course of milling was monitored by scanning electron microscopy and X-ray diffraction. After milling, the collected powders were sieved by 45 μm grid and hot pressed (Nb alloys and NiAl) or hot extruded (NiAl). The resulting material was fully dense and exhibited fine grain (< 1 μm) and uniform distribution of oxide dispersoid. The consolidated material was compression and creep tested. The mechanical properties of mechanically alloys were superior to properties of their cast counterparts both in the room and elevated temperatures. Higher strength of mechanically alloyed materials results from their fine grains and from the presence of dispersoid. At elevated temperatures, the Nb-Al alloys have higher compression strength than NiAl-based alloys processed at the same conditions. The minimum creep rates of mechanically alloyed Nb alloys are an order of magnitude lower than analogously processed NiAl-base alloys. (author)

  2. Iron-based amorphous alloys and methods of synthesizing iron-based amorphous alloys

    Science.gov (United States)

    Saw, Cheng Kiong; Bauer, William A.; Choi, Jor-Shan; Day, Dan; Farmer, Joseph C.

    2016-05-03

    A method according to one embodiment includes combining an amorphous iron-based alloy and at least one metal selected from a group consisting of molybdenum, chromium, tungsten, boron, gadolinium, nickel phosphorous, yttrium, and alloys thereof to form a mixture, wherein the at least one metal is present in the mixture from about 5 atomic percent (at %) to about 55 at %; and ball milling the mixture at least until an amorphous alloy of the iron-based alloy and the at least one metal is formed. Several amorphous iron-based metal alloys are also presented, including corrosion-resistant amorphous iron-based metal alloys and radiation-shielding amorphous iron-based metal alloys.

  3. Combinatorial thin film materials science: From alloy discovery and optimization to alloy design

    International Nuclear Information System (INIS)

    Gebhardt, Thomas; Music, Denis; Takahashi, Tetsuya; Schneider, Jochen M.

    2012-01-01

    This paper provides an overview of modern alloy development, from discovery and optimization towards alloy design, based on combinatorial thin film materials science. The combinatorial approach, combining combinatorial materials synthesis of thin film composition-spreads with high-throughput property characterization has proven to be a powerful tool to delineate composition–structure–property relationships, and hence to efficiently identify composition windows with enhanced properties. Furthermore, and most importantly for alloy design, theoretical models and hypotheses can be critically appraised. Examples for alloy discovery, optimization, and alloy design of functional as well as structural materials are presented. Using Fe-Mn based alloys as an example, we show that the combination of modern electronic-structure calculations with the highly efficient combinatorial thin film composition-spread method constitutes an effective tool for knowledge-based alloy design.

  4. Ti-Pt Alloys form mechanical milling

    CSIR Research Space (South Africa)

    Nxumalo, S

    2009-12-01

    Full Text Available orthorhombic structure at a temperature of approximately 1000oC. The martensite phase results in shape memory effect being observed in this alloy at this temperature. Other alloys such as TiNi and TiPd have also been investigated for the martensitic...

  5. Design optimization of shape memory alloy structures

    NARCIS (Netherlands)

    Langelaar, M.

    2006-01-01

    This thesis explores the possibilities of design optimization techniques for designing shape memory alloy structures. Shape memory alloys are materials which, after deformation, can recover their initial shape when heated. This effect can be used for actuation. Emerging applications for shape memory

  6. Methods for Electrodepositing Composition-Modulated Alloys

    DEFF Research Database (Denmark)

    Leisner, Peter; Nielsen, Christian Bergenstof; Tang, Peter Torben

    1996-01-01

    Materials exhibiting unique mechanical, physical and chemical properties can be obtained by combining thin layers of different metals or alloys forming a multilayered structure. Two general techniques exist for electrodepositing composition-modulated alloy (CMA) materials; dual-bath and single...

  7. Machining of uranium and uranium alloys

    International Nuclear Information System (INIS)

    Morris, T.O.

    1981-01-01

    Uranium and uranium alloys can be readily machined by conventional methods in the standard machine shop when proper safety and operating techniques are used. Material properties that affect machining processes and recommended machining parameters are discussed. Safety procedures and precautions necessary in machining uranium and uranium alloys are also covered. 30 figures

  8. Review of tantalum and niobium alloy production

    International Nuclear Information System (INIS)

    Buckman, R.W. Jr.

    1984-01-01

    This paper concentrates on the current state of niobium- and tantalum-base alloy production. The materials requirements, alloy compositions of interest, and production status are discussed. Finally, a list of developments needed to support the SP-100 program will be identified. A bibliography is included

  9. Titanium and titanium alloys: fundamentals and applications

    National Research Council Canada - National Science Library

    Leyens, C; Peters, M

    2003-01-01

    ... number of titanium alloys have paved the way for light metals to vastly expand into many industrial applications. Titanium and its alloys stand out primarily due to their high specific strength and excellent corrosion resistance, at just half the weight of steels and Ni-based superalloys. This explains their early success in the aerospace and the...

  10. TERNARY ALLOYS OF URANIUM, COLUMBIUM, AND ZIRCONIUM

    Science.gov (United States)

    Foote, F.G.

    1960-08-01

    Ternary alloys of uranium are described which are useful as neutron- reflecting materials in a fast neutron reactor. They are especially resistant to corrosion caused by oxidative processes of gascous or aqueous origin and comprise uranium as the predominant metal with zirconiunn and niobium wherein the total content of the minor alloying elements is between 2 and 8% by weight.

  11. Electrodeposition of zinc--nickel alloys coatings

    Energy Technology Data Exchange (ETDEWEB)

    Dini, J W; Johnson, H R

    1977-10-01

    One possible substitute for cadmium in some applications is a zinc--nickel alloy deposit. Previous work by others showed that electrodeposited zinc--nickel coatings containing about 85 percent zinc and 15 percent nickel provided noticeably better corrosion resistance than pure zinc. Present work which supports this finding also shows that the corrosion resistance of the alloy deposit compares favorably with cadmium.

  12. Intermetallic alloys: Deformation, mechanical and fracture behaviour

    International Nuclear Information System (INIS)

    Dogan, B.

    1988-01-01

    The state of the art in intermetallic alloys development with particular emphasis on deformation, mechanical and fracture behaviour is documented. This review paper is prepared to lay the ground stones for a future work on mechanical property characterization and fracture behaviour of intermetallic alloys at GKSS. (orig.)

  13. Ternary alloy nanocatalysts for hydrogen evolution reaction

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 39; Issue 2. Ternary alloy nanocatalysts for ... It is to be noted that synthesis of nanocrystallineternary alloys with precise composition is a big challenge which can be overcome by choosing an appropriate microemulsion system. High electrocatalytic activity towards ...

  14. Fundamental irradiation studies on vanadium alloys

    International Nuclear Information System (INIS)

    Loomis, B.A.; Garner, F.A.; Ermi, A.M.

    1985-05-01

    A joint experiment on the irradiation response of simple vanadium alloys has been initiated under the auspices of the DAFS and BES progams. Specimen fabrication is nearly complete and the alloys are expected to be irradiated in lithium in FFTF-MOTA Cycles 7 and 8

  15. Grain refinement of zinc-aluminium alloys

    International Nuclear Information System (INIS)

    Zaid, A.I.O.

    2006-01-01

    It is now well-established that the structure of the zinc-aluminum die casting alloys can be modified by the binary Al-Ti or the ternary Al-Ti-B master alloys. in this paper, grain refinement of zinc-aluminum alloys by rare earth materials is reviewed and discussed. The importance of grain refining of these alloys and parameters affecting it are presented and discussed. These include parameters related to the Zn-Al alloys cast, parameters related to the grain refining elements or alloys and parameters related to the process. The effect of addition of other alloying elements e.g. Zr either alone or in the presence of the main grain refiners Ti or Ti + B on the grain refining efficiency is also reviewed and discussed. Furthermore, based on the grain refinement and the parameters affecting it, a criterion for selection of the optimum grain refiner is suggested. Finally, the recent research work on the effect of grain refiners on the mechanical behaviour, impact strength, wear resistance, and fatigue life of these alloys are presented and discussed. (author)

  16. Heat storage in alloy transformations. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Birchenall, C E; Gueceri, S I; Farkas, D; Labdon, M B; Nagaswami, N; Pregger, B

    1981-03-01

    A study conducted to determine the feasibility of using metal alloys as thermal energy storage media is described. The study had the following major elements: (1) the identification of congruently transforming alloys and thermochemical property measurements, (2) the development of a precise and convenient method for measuring volume change during phase transformation and thermal expansion coefficients, (3) the development of a numerical modeling routine for calculating heat flow in cylindrical heat exchangers containing phase-change materials, and (4) the identification of materials that could be used to contain the metal alloys. The elements selected as candidate media were limited to aluminum, copper, magnesium, silicon, zinc, calcium, and phosphorus on the basis of low cost and latent heat of transformation. Several new eutectic alloys and ternary intermetallic phases have been determined. A new method employing x-ray absorption techniques was developed to determine the coefficients of thermal expansion of both the solid and liquid phases and the volume change during phase transformation from data that are obtained during one continuous experimental test. The method and apparatus are discussed and the experimental results are presented. The development of the numerical modeling method is presented and results are discussed for both salt and metal alloy phase-change media. Candidate materials were evaluated to determine suitable materials for containment of the metal alloys. Graphite was used to contain the alloys during the volume change measurements. Silicon carbide has been identified as a promising containment material and surface-coated iron alloys were considered.

  17. Improving mechanical properties of aluminium alloy through ...

    African Journals Online (AJOL)

    This paper investigates the microstructure and mechanical properties of aluminum alloy (Al-Si-Fe) reinforced with coconut shell-ash particulate. The aluminium (Al-Si-Fe) alloy composite was produced by a double-stir casting process at a speed of 700 rpm for 10 and 5 minutes at first and second stirring respectively.

  18. Plasma deposition of amorphous metal alloys

    Science.gov (United States)

    Hays, Auda K.

    1986-01-01

    Amorphous metal alloy coatings are plasma-deposited by dissociation of vapors of organometallic compounds and metalloid hydrides in the presence of a reducing gas, using a glow discharge. Tetracarbonylnickel, phosphine, and hydrogen constitute a typical reaction mixture of the invention, yielding a NiPC alloy.

  19. Development of high performance ODS alloys

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Lin [Texas A & M Univ., College Station, TX (United States); Gao, Fei [Univ. of Michigan, Ann Arbor, MI (United States); Garner, Frank [Texas A & M Univ., College Station, TX (United States)

    2018-01-29

    This project aims to capitalize on insights developed from recent high-dose self-ion irradiation experiments in order to develop and test the next generation of optimized ODS alloys needed to meet the nuclear community's need for high strength, radiation-tolerant cladding and core components, especially with enhanced resistance to void swelling. Two of these insights are that ferrite grains swell earlier than tempered martensite grains, and oxide dispersions currently produced only in ferrite grains require a high level of uniformity and stability to be successful. An additional insight is that ODS particle stability is dependent on as-yet unidentified compositional combinations of dispersoid and alloy matrix, such as dispersoids are stable in MA957 to doses greater than 200 dpa but dissolve in MA956 at doses less than 200 dpa. These findings focus attention on candidate next-generation alloys which address these concerns. Collaboration with two Japanese groups provides this project with two sets of first-round candidate alloys that have already undergone extensive development and testing for unirradiated properties, but have not yet been evaluated for their irradiation performance. The first set of candidate alloys are dual phase (ferrite + martensite) ODS alloys with oxide particles uniformly distributed in both ferrite and martensite phases. The second set of candidate alloys are ODS alloys containing non-standard dispersoid compositions with controllable oxide particle sizes, phases and interfaces.

  20. Experimental Evaluation of New Alloy Coatings

    Science.gov (United States)

    1989-07-19

    are in agreement with the iridium-hafnium phase diagram1 1 . The iridium-50 at% hafnium alloy is an intermetallic compound HfIr , while the iridium-5...and -65 at% hafnium alloys are two-phase mixtures of hafnium-Hf2 Ir and HfIr - HfIr 3 , respectively. In Fig. 1, the observed weight changes for iridium

  1. Underwater laser beam welding of Alloy 690

    International Nuclear Information System (INIS)

    Hino, Takehisa; Tamura, Masataka; Kono, Wataru; Kawano, Shohei; Yoda, Masaki

    2009-01-01

    Stress Corrosion Clacking (SCC) has been reported at Alloy 600 welds between nozzles and safe-end in Pressurized Water Reactor (PWR) plant. Alloy 690, which has higher chromium content than Alloy 600, has been applied for cladding on Alloy 600 welds for repairing damaged SCC area. Toshiba has developed Underwater Laser Beam Welding technique. This method can be conducted without draining, so that the repairing period and the radiation exposure during the repair can be dramatically decreased. In some old PWRs, high-sulfur stainless steel is used as the materials for this section. It has a high susceptibility of weld cracks. Therefore, the optimum welding condition of Alloy 690 on the high-sulfur stainless steel was investigated with our Underwater Laser Beam Welding unit. Good cladding layer, without any crack, porosity or lack of fusion, could be obtained. (author)

  2. Corrosion resistance improvement of titanium base alloys

    Directory of Open Access Journals (Sweden)

    Mihai V. Popa

    2010-01-01

    Full Text Available The corrosion resistance of the new Ti-6Al-4V-1Zr alloy in comparison with ternary Ti-6Al-4V alloy in Ringer-Brown solution and artificial Carter-Brugirard saliva of different pH values was studied. In Ringer-Brown solution, the new alloy presented an improvement of all electrochemical parameters due to the alloying with Zr; also, impedance spectra revealed better protective properties of its passive layer. In Carter-Brugirard artificial saliva, an increase of the passive film thickness was proved. Fluoride ions had a slight negative influence on the corrosion and ion release rates, without to affect the very good stability of the new Ti-6Al-4V-1Zr alloy.

  3. Zirconium alloy barrier having improved corrosion resistance

    International Nuclear Information System (INIS)

    Adamson, R.B.; Rosenbaum, H.S.

    1983-01-01

    A nuclear fuel element for use in the core of a nuclear reactor has a composite cladding container having a substrate and a dilute zirconium alloy liner bonded to the inside surface of the substrate. The dilute zirconium alloy liner forms about 1 to about 20 percent of the thickness of the cladding and is comprised of zirconium and a metal selected from the group consisting of iron, chromium, iron plus chromium, and copper. The dilute zirconium alloy liner shields the substrate from impurities or fission products from the nuclear fuel material and protects the substrate from stress corrosion and stress cracking. The dilute zirconium alloy liner displays greater corrosion resistance, especially to oxidation by hot water or steam than unalloyed zirconium. The substrate material is selected from conventional cladding materials, and preferably is a zirconium alloy. (author)

  4. Machinability of experimental Ti-Ag alloys.

    Science.gov (United States)

    Kikuchi, Masafumi; Takahashi, Masatoshi; Okuno, Osamu

    2008-03-01

    This study investigated the machinability of experimental Ti-Ag alloys (5, 10, 20, and 30 mass% Ag) as a new dental titanium alloy candidate for CAD/CAM use. The alloys were slotted with a vertical milling machine and carbide square end mills under two cutting conditions. Machinability was evaluated through cutting force using a three-component force transducer fixed on the table of the milling machine. The horizontal cutting force of the Ti-Ag alloys tended to decrease as the concentration of silver increased. Values of the component of the horizontal cutting force perpendicular to the feed direction for Ti-20% Ag and Ti-30% Ag were more than 20% lower than those for titanium under both cutting conditions. Alloying with silver significantly improved the machinability of titanium in terms of cutting force under the present cutting conditions.

  5. Internal chlorination of Ni-Cr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Berztiss, D.; Hennesen, K.; Grabke, H.J. [Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany)

    1998-12-31

    In contrast to internal oxidation, sulfidation and carburization, very little information is available regarding internal chlorination, especially diffusion of chlorine in metallic alloys. This paper describes results of experiments on Ni-Cr alloys (<10 wt% Cr) exposed in an atmosphere containing radioactive HCl. The diffusion of chlorine in the alloy can be determined by measurement of residual {beta}-activity from the sample surface. Successively thin layers (0.5-10 {mu}m) of the alloy were removed by lapping and the surface activity was measured to obtain a depth profile. Both single and polycrystalline materials were tested. Through this work it should be determined if there is in fact solubility and diffusion of chlorine in Ni-based alloys as some authors have proposed or if the ingress of chlorine is mainly a grain boundary phenomenon. (orig.)

  6. The interaction of hydrogen with metal alloys

    Science.gov (United States)

    Danford, M. D.; Montano, J. W.

    1991-01-01

    Hydrogen diffusion coefficients were measured for several alloys, and these were determined to be about the same at 25 C for all alloys investigated. The relation of structure, both metallurgical and crystallographic, to the observed hydrogen distribution on charging was investigated, as well as the role of hydride formation in the hydrogen resistance of metal alloys. An attempt was made to correlate the structures and compositions of metal alloys as well as other parameters with the ratios of their notched tensile strengths in hydrogen to that in helium, R(H2/He), which are believed to represent a measure of their hydrogen resistance. Evidence supports the belief that hydrogen permeability and hydrogen resistance are increased by smaller grain sizes for a given alloy composition.

  7. Plating on stainless steel alloys

    International Nuclear Information System (INIS)

    Dini, J.W.; Johnson, H.R.

    1981-01-01

    Quantitative adhesion data are presented for a variety of electroplated stainless steel type alloys. Results show that excellent adhesion can be obtained by using a Wood's nickel strike or a sulfamate nickel strike prior to final plating. Specimens plated after Wood's nickel striking failed in the deposit rather than at the interface between the substrate and the coating. Flyer plate quantitative tests showed that use of anodic treatment in sulfuric acid prior to Wood's nickel striking even further improved adhesion. In contrast activation of stainless steels by immersion or cathodic treatment in hydrochloric acid resulted in very reduced bond strengths with failure always occurring at the interface between the coating and substrate

  8. Phase diagrams for surface alloys

    DEFF Research Database (Denmark)

    Christensen, Asbjørn; Ruban, Andrei; Stoltze, Per

    1997-01-01

    We discuss surface alloy phases and their stability based on surface phase diagrams constructed from the surface energy as a function of the surface composition. We show that in the simplest cases of pseudomorphic overlayers there are four generic classes of systems, characterized by the sign...... is based on density-functional calculations using the coherent-potential approximation and on effective-medium theory. We give self-consistent density-functional results for the segregation energy and surface mixing energy for all combinations of the transition and noble metals. Finally we discuss...

  9. Thermal stability of high temperature structural alloys

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, C.E.; Rasefske, R.K.; Castagna, A. [Lockheed Martin Corp., Schenectady, NY (United States)

    1999-03-01

    High temperature structural alloys were evaluated for suitability for long term operation at elevated temperatures. The effect of elevated temperature exposure on the microstructure and mechanical properties of a number of alloys was characterized. Fe-based alloys (330 stainless steel, 800H, and mechanically alloyed MA 956), and Ni-based alloys (Hastelloy X, Haynes 230, Alloy 718, and mechanically alloyed MA 758) were evaluated for room temperature tensile and impact toughness properties after exposure at 750 C for 10,000 hours. Of the Fe-based alloys evaluated, 330 stainless steel and 800H showed secondary carbide (M{sub 23}C{sub 6}) precipitation and a corresponding reduction in ductility and toughness as compared to the as-received condition. Within the group of Ni-based alloys tested, Alloy 718 showed the most dramatic structure change as it formed delta phase during 10,000 hours of exposure at 750 C with significant reductions in strength, ductility, and toughness. Haynes 230 and Hastelloy X showed significant M{sub 23}C{sub 6} carbide precipitation and a resulting reduction in ductility and toughness. Haynes 230 was also evaluated after 10,000 hours of exposure at 850, 950, and 1050 C. For the 750--950 C exposures the M{sub 23}C{sub 6} carbides in Haynes 230 coarsened. This resulted in large reductions in impact strength and ductility for the 750, 850 and 950 C specimens. The 1050 C exposure specimens showed the resolution of M{sub 23}C{sub 6} secondary carbides, and mechanical properties similar to the as-received solution annealed condition.

  10. 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.

  11. Characterization of zinc–nickel alloy electrodeposits obtained from ...

    Indian Academy of Sciences (India)

    Zinc alloy offers superior sacrificial protection to steel as the alloy dissolves more slowly than pure zinc. The degree of protection and the rate of dissolution depend on the alloying metal and its composition. Zinc-nickel alloy may also serve as at less toxic substitute for cadmium. In this paper the physico-chemical ...

  12. Study of fatigue behaviour of 7475 aluminium alloy

    Indian Academy of Sciences (India)

    Unknown

    controlled toughness alloy developed for applications that require a combination of high strength, superior fracture toughness and resistance to fatigue crack propagation both in air and aggressive environment. The 7475 alu- minium alloy is basically a modified version of 7075 alloy. Properties in 7075 alloy are improved by ...

  13. Recent research and developments on wrought magnesium alloys

    Directory of Open Access Journals (Sweden)

    Sihang You

    2017-09-01

    Full Text Available Wrought magnesium alloys attract special interests as lightweight structural material due to their homogeneous microstructure and enhanced mechanical properties compared to as-cast alloys. In this contribution, recent research and developments on wrought magnesium alloys are reviewed from the viewpoint of the alloy design, focusing on Mg-Al, Mg-Zn and Mg-rare earth (RE systems. The effects of different alloying elements on the microstructure and mechanical properties are described considering their strengthening mechanisms, e.g. grain refinement, precipitation and texture hardening effect. Finally, the new alloy design and also the future research of wrought magnesium alloys to improve their mechanical properties are discussed.

  14. Shot peening of aluminium alloys

    International Nuclear Information System (INIS)

    Le Guernic, Y.

    1998-01-01

    Shot peening is a process of cold-hammering where a metallic surface is pelted with spherical grains. Each grain bumping into the surface acts as a hammer head and creates a small crater. The overlapping of these craters produces a residual compression layer just underneath the surface. It is well known that cracks cannot spread in a compression zone. In most cases of fatigue rupture and stress corrosion cracks propagate from the surface towards the inside so shot peening allows a longer lifetime of castings. Moreover most materials present a better resistance due to the cold-hammering effect of shot peening. Metallic surfaces can be treated in workshops or directly on site. Typical pieces that undergo shot peening on site are storing tanks, gas and steam turbines, tubes of steam generators and piping in oil or nuclear or chemical industries. This article describes shot peening from a theoretical and general point of view and presents the application to aluminium-lithium alloys. In the case of aluminium alloys shot peening can be used to shape the piece (peen-forming). (A.C.)

  15. Development of Metallic Sensory Alloys

    Science.gov (United States)

    Wallace Terryl A.; Newman, John A.; Horne, Michael R.; Messick, Peter L.

    2010-01-01

    Existing nondestructive evaluation (NDE) technologies are inherently limited by the physical response of the structural material being inspected and are therefore not generally effective at the identification of small discontinuities, making the detection of incipient damage extremely difficult. One innovative solution to this problem is to enhance or complement the NDE signature of structural materials to dramatically improve the ability of existing NDE tools to detect damage. To address this need, a multifunctional metallic material has been developed that can be used in structural applications. The material is processed to contain second phase sensory particles that significantly improve the NDE response, enhancing the ability of conventional NDE techniques to detect incipient damage both during and after flight. Ferromagnetic shape-memory alloys (FSMAs) are an ideal material for these sensory particles as they undergo a uniform and repeatable change in both magnetic properties and crystallographic structure (martensitic transformation) when subjected to strain and/or temperature changes which can be detected using conventional NDE techniques. In this study, the use of a ferromagnetic shape memory alloy (FSMA) as the sensory particles was investigated.

  16. Vibrational entropies in metallic alloys

    Science.gov (United States)

    Ozolins, Vidvuds; Asta, Mark; Wolverton, Christopher

    2000-03-01

    Recently, it has been recognized that vibrational entropy can have significant effects on the phase stability of metallic alloys. Using density functional linear response calculations and molecular dynamics simulations we study three representative cases: (i) phase diagram of Al-rich Al-Sc alloys, (ii) stability of precipitate phases in CuAl_2, and (iii) phonon dynamics in bcc Zr. We find large vibrational entropy effects in all cases. In the Al-Sc system, vibrations increase the solid solubility of Sc in Al by decreasing the stability of the L12 (Al_3Sc) phase. This leads to a nearly ten-fold increase in the solid solubility of Sc in Al at T=800 K. In the Cu-Al system, our calculations predict that the tetragonal Laves phase of CuAl2 has 0.35 kB/atom higher vibrational entropy than the cubic CaF_2-type phase (the latter is predicted to be the T=0 K ground state of CuAl_2). This entropy difference causes a structural transformation in CuAl2 precipitates from the fluorite to the tetragonal Laves phase around T=500 K. Finally, we analyze the highly unusual dynamics of anharmonically stabilized bcc Zr, finding large diffuse-scattering intensity streaks between the bcc Bragg peaks.

  17. Oxide films on magnesium and magnesium alloys

    International Nuclear Information System (INIS)

    Shih, T.-S.; Liu, J.-B.; Wei, P.-S.

    2007-01-01

    Magnesium alloys are very active and readily ignite during heating and melting. In this study, we discuss the combustion of magnesium and magnesium alloys and propose prospective anti-ignition mechanisms for magnesium alloys during the heating process. When magnesium and magnesium alloys were heated in air, the sample surfaces produced layers of thermally formed oxides. These thermally formed oxides played an important role in affecting the combustion of the magnesium and magnesium alloys. When magnesium was heated in air, brucite that formed in the early stage was then transformed into periclase by dehydroxylation. By extending the heating time, more periclase formed and increased in thickness which was associated with microcracks formation. When magnesium was heated in a protective atmosphere (SF 6 ), a film of MgF 2 formed at the interface between the oxide layer and the Mg substrate. This film generated an anti-ignition behavior which protected the substrate from oxidation. When solution-treated AZ80 alloy was heated, spinel developed at the interface between the thermally formed oxide layer and the Mg substrate, improving the anti-ignition properties of the substrate. In addition, we also explain the effects of beryllium in an AZB91 alloy on the ignition-proofing behavior

  18. Activation analyses for different fusion structural alloys

    International Nuclear Information System (INIS)

    Attaya, H.; Smith, D.

    1991-01-01

    The leading candidate structural materials, viz., the vanadium alloys, the nickel or the manganese stabilized austenitic steels, and the ferritic steels, are analysed in terms of their induced activation in the TPSS fusion power reactor. The TPSS reactor has 1950 MW fusion power and inboard and outboard average neutron wall loading of 3.75 and 5.35 MW/m 2 respectively. The results shows that, after one year of continuous operation, the vanadium alloys have the least radioactivity at reactor shutdown. The maximum difference between the induced radioactivity in the vanadium alloys and in the other iron-based alloys occurs at about 10 years after reactor shutdown. At this time, the total reactor radioactivity, using the vanadium alloys, is about two orders of magnitude less than the total reactor radioactivity utilizing any other alloy. The difference is even larger in the first wall, the FW-vanadium activation is 3 orders of magnitude less than other alloys' FW activation. 2 refs., 7 figs

  19. 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

  20. 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.

  1. 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.

  2. Electric field gradients in copper alloys

    International Nuclear Information System (INIS)

    Whalley, L.R.

    1974-02-01

    The electric field gradients at Cu atoms which are near neighbors to the nickel impurity in a dilute CuNi alloy were measured. The technique used is zero field pure quadrupole resonance which was first demonstrated by Redfield [Redfield, Phys. Rev. 130, 589 (1963)]. The measured electric field gradients for this alloy system are 4.1 x 10 23 cm -3 , 0.84 x 10 23 cm -3 , 0.46 x 10 23 cm -3 and 0.146 x 10 23 cm -3 . These measured values are compared with the values calculated by Beal-Monod [Beal-Monod, Phys. Rev. 164, 360 (1967)]. In addition the following alloy systems were measured; CuCo, CuFe, and CuV. The nuclear relaxation of the alloys was measured but no satellite structure was detected. Results of these measurements show the similarity of the interactions measured here to the interactions in CuZn measured by Redfield. Since nickel has an unfilled 3d shell in its electronic structure, magnetic interactions in the CuNi alloy might be expected. Magnetic interactions were not found. Like the nickel alloy, the zinc alloy with copper exhibits no magnetic effects. (U.S.)

  3. The Influence of Forging Temperature on Mechanical Properties of Al-V Titanium Alloys,

    Science.gov (United States)

    Titanium alloys, *Forging, Aluminum alloys, Vanadium alloys, Mechanical properties, Heat treatment, High temperature, Press forging, Quenching, Toughness, Charpy impact tests , Notch toughness, Resistance

  4. Excitation dependent multicolor emission and photoconductivity of Mn, Cu doped In2S3 monodisperse quantum dots

    Science.gov (United States)

    Ghosh, Sirshendu; Saha, Manas; Ashok, Vishal Dev; Chatterjee, Arijit; De, S. K.

    2016-04-01

    Indium sulphide (In2S3) quantum dots (QDs) of average size 6 ± 2 nm and hexagonal nanoplatelets of average size 37 ± 4 nm have been synthesized from indium myristate and indium diethyl dithiocarbamate precursors respectively. The absorbance and emission band was tuned with variation of nanocrytal size from very small in the strong confinement regime to very large in the weak confinement regime. The blue emission and its shifting with size has been explained with the donor-acceptor recombination process. The 3d element doping (Mn2+ and Cu2+) is found to be effective for formation of new emission bands at higher wavelengths. The characteristic peaks of Mn2+ and Cu2+ and the modification of In3+ peaks in the x-ray photoelectric spectrum (XPS) confirm the incorporation of Mn2+ and Cu2+ into the In2S3 matrix. The simulation of the electron paramagnetic resonance signal indicates the coexistence of isotropic and axial symmetry for In and S vacancies. Moreover, the majority of Mn2+ ions and sulphur vacancies (VS ) reside on the surface of nanocrystals. The quantum confinement effect leads to an enhancement of band gap up to 3.65 eV in QDs. The formation of Mn 3d levels between conduction band edge and shallow donor states is evidenced from a systematic variation of emission spectra with the excitation wavelength. In2S3 QDs have been established as efficient sensitizers to Mn and Cu emission centers. Fast and slow components of photoluminescence (PL) decay dynamics in Mn and Cu doped QDs are interpreted in terms of surface and bulk recombination processes. Fast and stable photodetctors with high photocurrent gain are fabricated with Mn and Cu doped QDs and are found to be faster than pure In2S3. The fastest response time in Cu doped QDs is an indication of the most suitable system for photodetector devices.

  5. Two distinct halo populations in the solar neighborhood. II. Evidence from stellar abundances of Mn, Cu, Zn, Y, and Ba

    Science.gov (United States)

    Nissen, P. E.; Schuster, W. J.

    2011-06-01

    Context. Current models of galaxy formation predict that the Galactic halo was assembled hierarchically. By measuring abundance ratios in stars it may be possible to identify substructures in the halo resulting from this process. Aims: A previous study of 94 dwarf stars with -1.6 FIES spectra and used to derive abundance ratios from an LTE analysis based on MARCS model atmospheres. The analysis is made relative to two thick-disk stars, HD 22879 and HD 76932, such that very precise differential values are obtained. Results: Systematic differences between the "high-α" and "low-α" halo populations are found for [Cu/Fe], [Zn/Fe], and [Ba/Y], whereas there is no significant difference in the case of [Mn/Fe]. At a given metallicity, [Cu/Fe] shows a large scatter that is closely correlated with a corresponding scatter in [Na/Fe] and [Ni/Fe]. Conclusions: The metallicity trends of [Cu/Fe], [Zn/Fe], and [Ba/Y] can be explained from existing nucleosynthesis calculations if the high-α stars formed in regions with such a high star formation rate that only massive stars and type II supernovae contributed to the chemical enrichment. The low-α stars, on the other hand, most likely originate from systems with a slower chemical evolution, characterized by additional enrichment from type Ia supernovae and low-mass AGB stars. Based on observations made with the Nordic Optical Telescope on La Palma, and on data from the European Southern Observatory ESO/ST-ECF Science Archive Facility (programs 65.L-0507, 67.D-0086, 67.D-0439, 68.D-0094, 68.B-0475, 69.D-0679, 70.D-0474, 71.B-0529, 72.B-0585, 76.B-0133 and 77.B-0507).Tables 1, 2, and excerpt of Table 3 are available in electronic form at http://www.aanda.orgTables 1, 2, and full Table 3 are also available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/530/A15

  6. The effect of mustard gas on salivary trace metals (Zn, Mn, Cu, Mg, Mo, Sr, Cd, Ca, Pb, Rb.

    Directory of Open Access Journals (Sweden)

    Elham Zamani Pozveh

    Full Text Available We have determined and compared trace metals concentration in saliva taken from chemical warfare injures who were under the exposure of mustard gas and healthy subjects by means of inductively coupled plasma optical emission spectroscopy (ICP-OES for the first time. The influence of preliminary operations on the accuracy of ICP-OES analysis, blood contamination, the number of restored teeth in the mouth, salivary flow rate, and daily variations in trace metals concentration in saliva were also considered. Unstimulated saliva was collected at 10:00-11:00 a.m. from 45 subjects in three equal groups. The first group was composed of 15 healthy subjects (group 1; the second group consisted of 15 subjects who, upon chemical warfare injuries, did not use Salbutamol spray, which they would have normally used on a regular basis (group 2; and the third group contained the same number of patients as the second group, but they had taken their regular medicine (Salbutamol spray; group 3. Our results showed that the concentration of Cu in saliva was significantly increased in the chemical warfare injures compared to healthy subjects, as follows: healthy subjects 15.3± 5.45 (p.p.b., patients (group 2 45.77±13.65, and patients (Salbutamol spray; group 3 29 ±8.51 (P <0.02. In contrast, zinc was significantly decreased in the patients, as follows: healthy subjects 37 ± 9.03 (p.p.b., patients (group 2 12.2 ± 3.56, and patients (Salbutamol spray; group 3 20.6 ±10.01 (P < 0.01. It is important to note that direct dilution of saliva samples with ultrapure nitric acid showed the optimum ICP-OES outputs.

  7. Two distinct halo populations in the solar neighborhood II. Evidence from stellar abundances of Mn, Cu, Zn, Y, and Ba

    DEFF Research Database (Denmark)

    Nissen, Poul Erik; Schuster, William J.

    2011-01-01

    Context. Current models of galaxy formation predict that the Galactic halo was assembled hierarchically. By measuring abundance ratios in stars it may be possible to identify substructures in the halo resulting from this process. Aims. A previous study of 94 dwarf stars with −1.6 ..., on the other hand, most likely originate from systems with a slower chemical evolution, characterized by additional enrichment from type Ia supernovae and low-mass AGB stars....

  8. The Effect of Mustard Gas on Salivary Trace Metals (Zn, Mn, Cu, Mg, Mo, Sr, Cd, Ca, Pb, Rb)

    Science.gov (United States)

    Zamani Pozveh, Elham; Seif, Ahmad; Ghalayani, Parichehr; Maleki, Abbas; Mottaghi, Ahmad

    2015-01-01

    We have determined and compared trace metals concentration in saliva taken from chemical warfare injures who were under the exposure of mustard gas and healthy subjects by means of inductively coupled plasma optical emission spectroscopy (ICP-OES) for the first time. The influence of preliminary operations on the accuracy of ICP-OES analysis, blood contamination, the number of restored teeth in the mouth, salivary flow rate, and daily variations in trace metals concentration in saliva were also considered. Unstimulated saliva was collected at 10:00–11:00 a.m. from 45 subjects in three equal groups. The first group was composed of 15 healthy subjects (group 1); the second group consisted of 15 subjects who, upon chemical warfare injuries, did not use Salbutamol spray, which they would have normally used on a regular basis (group 2); and the third group contained the same number of patients as the second group, but they had taken their regular medicine (Salbutamol spray; group 3). Our results showed that the concentration of Cu in saliva was significantly increased in the chemical warfare injures compared to healthy subjects, as follows: healthy subjects 15.3± 5.45(p.p.b.), patients (group 2) 45.77±13.65, and patients (Salbutamol spray; group 3) 29 ±8.51 (P ICP-OES outputs. PMID:25965704

  9. The distribution of four trace elements (Fe, Mn, Cu, Zn in forage and the relation to scrapie in Iceland

    Directory of Open Access Journals (Sweden)

    Jóhannesson Torkell

    2010-05-01

    Full Text Available Abstract Background Previous studies indicated that the iron (Fe/manganese (Mn ratio in forage of sheep was significantly higher on scrapie-afflicted farms than on farms in other scrapie categories. This study was conducted to examine whether Fe and Mn in forage of sheep varied in general according to the scrapie status of different areas in the country. Copper (Cu and zinc (Zn were also included because of a possible relation to scrapie. Methods The country was subdivided into seven Areas (I-VII. Three Areas (I, IV, VII were designated scrapie-free (never diagnosed or eradicated and three as scrapie-endemic (II, III, VI; status of Area V was taken as unsettled. Of the harvest 2007 1552 samples were analysed from 344 farms all over the country, mostly grass silage from plastic bales (>90% and from the first cut (70% or more. Results were expressed as mg kg-1 dry matter. Results Fe varied enormously from less than 100 mg kg-1 to 5000 mg kg-1. Mn varied nearly thirtyfold (17-470 mg kg-1. Fe concentration was significantly lower in Area I than in Areas II, V and VI. Mn concentration was significantly higher in Areas I, IV and VII than in Areas II, III, V and VI. The Fe/Mn ratio was significantly less in Area I than in the other areas (except Area IV. Mean Cu concentration was 6.6-8.3 mg kg-1 and the mean Zn concentration was 24-29 mg kg-1. They differed significantly in some areas. Conclusions 1 Fe tended to be in lower amounts in sheep forage in scrapie-free than in endemic areas; 2 Mn was in higher amounts in forage in scrapie-free than endemic areas; 3 the Fe/Mn ratio was lower in scrapie-free than in endemic areas; 4 the Fe/Mn ratio may possibly be used as an indicator of scrapie status; 5 Cu and Zn in sheep forage were not related to scrapie; 6 further study on the role of Fe and Mn in the occurrence of scrapie in Iceland is needed.

  10. Fatigue Characteristics of Selected Light Metal Alloys

    Directory of Open Access Journals (Sweden)

    Cieśla M.

    2016-03-01

    Full Text Available The paper addresses results of fatigue testing of light metal alloys used in the automotive as well as aerospace and aviation industries, among others. The material subject to testing comprised hot-worked rods made of the AZ31 alloy, the Ti-6Al-4V two-phase titanium alloy and the 2017A (T451 aluminium alloy. Both low- and high-cycle fatigue tests were conducted at room temperature on the cycle asymmetry ratio of R=-1. The low-cycle fatigue tests were performed using the MTS-810 machine on two levels of total strain, i.e.Δεc= 1.0% and 1.2%. The high-cycle fatigue tests, on the other hand, were performed using a machine from VEB Werkstoffprufmaschinen-Leipzig under conditions of rotary bending. Based on the results thus obtained, one could develop fatigue life characteristics of the materials examined (expressed as the number of cycles until failure of sample Nf as well as characteristics of cyclic material strain σa=f(N under the conditions of low-cycle fatigue testing. The Ti-6Al-4V titanium alloy was found to be characterised by the highest value of fatigue life Nf, both in lowand high-cycle tests. The lowest fatigue life, on the other hand, was established for the aluminium alloys examined. Under the high-cycle fatigue tests, the life of the 2017A aluminium and the AZ31 magnesium alloy studied was determined by the value of stress amplitude σa. With the stress exceeding 150 MPa, it was the aluminium alloy which displayed higher fatigue life, whereas the magnesium alloy proved better on lower stress.

  11. PRODUCTION OF WELDMENTS FROM SINTERED TITANIUM ALLOYS

    Directory of Open Access Journals (Sweden)

    A. YE. Kapustyan

    2014-04-01

    Full Text Available Purpose. Limited application of details from powder titanium alloys is connected with the difficulties in obtaining of long-length blanks, details of complex shape and large size. We can solve these problems by applying the welding production technology. For this it is necessary to conduct a research of the structure and mechanical properties of welded joints of sintered titanium alloys produced by flash welding. Methodology. Titanium industrial powders, type PT5-1 were used as original substance. Forming of blanks, whose chemical composition corresponded to BT1-0 alloy, was carried out using the powder metallurgy method. Compounds were obtained by flash welding without preheating. Microstructural investigations and mechanical tests were carried out. To compare the results investigations of BT1-0 cast alloy were conducted. Findings. Samples of welded joints of sintered titanium blanks from VT1-0 alloy using the flash butt welding method were obtained. During welding the microstructure of basic metal consisting of grains of an a-phase, with sizes 40...70 mkm, is transformed for the seam weld and HAZ into the lamellar structure of an a-phase. The remaining pores in seam weld were practically absent; in the HAZ their size was up to 2 mkm, with 30 mkm in the basic metal. Attainable level of mechanical properties of the welded joint in sintered titanium alloys is comparable to the basic metal. Originality. Structure qualitative changes and attainable property complex of compounds of sintered titanium alloys, formed as a result of flash butt welding were found out. Practical value. The principal possibility of high-quality compounds obtaining of sintered titanium alloys by flash welding is shown. This gives a basis for wider application of sintered titanium alloys due to long-length blanks production that are correspond to deformable strand semi finished product.

  12. Welding the four most popular aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Irving, B.

    1994-02-01

    The fact that business is good in aluminum welding is a sure sign that more manufacturers and fabricators are using GMA and GTA welding to build new products out of this lightweight nonferrous metal. Among the most widely specified weldable grades are Alloys 6061, 5083, 5052 and 5454. A rundown on these four alloys, including properties and selected applications, is provided. Any company working with aluminum for the first time needs to know something about these four alloys. Alloys of copper-magnesium-silicon combination, of which 6061 is one, are heat-treatable. The three 5XXX series alloys, on the other hand, are nonheat-treatable. According to P.B. Dickerson, consultant, Lower Burrell, Pa., 5083, because of its high magnesium content, is the easiest of the four alloys to arc weld. Dickerson put the cut-off point in weldability at 3.5% magnesium. To prevent cracking, he added, both 6061 and 5052 require much more filler metal than do the other two alloys. Alloy 6061 consists of 0.25Cu, 0.6Si, 1.0Mg, and 0.20Cr. The main applications for 6061 aluminum are structural, architectural, automotive, railway, marine and pipe. It has good formability, weldability, corrosion resistance and strength. Although the 6XXX series alloys are prone to hot cracking, this condition can be readily overcome by correct choice of joint design and electrode. The most popular temper for 6061 is T6, although the -T651, -T4, and -F temper are also popular. The -T651 temper is like a -T6 temper, only it has received some final stretch hardening. The -T4 temper has been solution heat-treated and quenched. The -F temper is in the as-fabricated condition.

  13. Antibacterial biodegradable Mg-Ag alloys

    Directory of Open Access Journals (Sweden)

    D Tie

    2013-06-01

    Full Text Available The use of magnesium alloys as degradable metals for biomedical applications is a topic of ongoing research and the demand for multifunctional materials is increasing. Hence, binary Mg-Ag alloys were designed as implant materials to combine the favourable properties of magnesium with the well-known antibacterial property of silver. In this study, three Mg-Ag alloys, Mg2Ag, Mg4Ag and Mg6Ag that contain 1.87 %, 3.82 % and 6.00 % silver by weight, respectively, were cast and processed with solution (T4 and aging (T6 heat treatment.The metallurgical analysis and phase identification showed that all alloys contained Mg4Ag as the dominant β phase. After heat treatment, the mechanical properties of all Mg-Ag alloys were significantly improved and the corrosion rate was also significantly reduced, due to presence of silver. Mg(OH2 and MgO present the main magnesium corrosion products, while AgCl was found as the corresponding primary silver corrosion product. Immersion tests, under cell culture conditions, demonstrated that the silver content did not significantly shift the pH and magnesium ion release. In vitro tests, with both primary osteoblasts and cell lines (MG63, RAW 264.7, revealed that Mg-Ag alloys show negligible cytotoxicity and sound cytocompatibility. Antibacterial assays, performed in a dynamic bioreactor system, proved that the alloys reduce the viability of two common pathogenic bacteria, Staphylococcus aureus (DSMZ 20231 and Staphylococcus epidermidis (DSMZ 3269, and the results showed that the killing rate of the alloys against tested bacteria exceeded 90%. In summary, biodegradable Mg-Ag alloys are cytocompatible materials with adjustable mechanical and corrosion properties and show promising antibacterial activity, which indicates their potential as antibacterial biodegradable implant materials.

  14. Development of oxide dispersion strengthened turbine blade alloy by mechanical alloying

    Science.gov (United States)

    Merrick, H. F.; Curwick, L. R. R.; Kim, Y. G.

    1977-01-01

    There were three nickel-base alloys containing up to 18 wt. % of refractory metal examined initially for oxide dispersion strengthening. To provide greater processing freedom, however, a leaner alloy was finally selected. This base alloy, alloy D, contained 0.05C/15Cr / 2Mo/4W/2Ta/4.5Al/2.Ti/015Zr/0.01-B/Bal. Ni. Following alloy selection, the effect of extrusion, heat treatment, and oxide volume fraction and size on microstructure and properties were examined. The optimum structure was achieved in zone annealed alloy D which contained 2.5 vol. % of 35 mm Y2O3 and which was extruded 16:1 at 1038 C.

  15. Development of environmentally friendly cast alloys and composites. High zinc Al-base cast alloys

    Directory of Open Access Journals (Sweden)

    W.K. Krajewski

    2010-01-01

    Full Text Available This work is devoted to grain refinement of the foundry Al-20 wt% Zn (AlZn20 alloy, aiming at improving ductility of the sand-cast alloy The melted alloy was inoculated using traditional AlTi5B1 (TiBAl and AlTi3C0.15 (TiCAl master alloys and newly introduced (Zn,Al-Ti3 one. The performed structural examinations showed out significant increasing of the grain population of the inoculated alloy and plas-ticity increase represented by elongation. The high damping properties of the initial alloy, measured using an ultrasonic Olympus Epoch XT device, are basicly preserved after inoculation. Also tensile strength preserves its good values, while elongation shows an increase – which are beneficials of the employed grain-refining process.

  16. Hysteresis behaviour of thermoelastic alloys: some shape memory alloys models

    International Nuclear Information System (INIS)

    Lexcellent, C.; Torra, V.; Raniecki, B.

    1993-01-01

    The hysteretic behaviour of shape memory alloys (SMA) needs a more and more thin analysis because of its importance for technological applications. The comparison between different approaches allows to explicite the specifity of every model (macroscopic approach, micro-macro level, local description, phenomenological approach) and their points of convergence. On one hand, a thermodynamic treatment with a free energy expression as a mixing rule of each phase (parent or austenite phase and martensite) by adding a coupling term: the configurational energy, allowes modelling of material hysteresis loops. On the other hand, a phenomenological treatment based on a local investigation of two single crystals with a visualisation of microscopic parameters allows to perceive the phase transition mechanisms (nucleation, growth). All the obtained results show the importance of entropy production (or of the definition of the configurational energy term) for the correct description of hysteresis loops (subloops or external). (orig.)

  17. Electron microscopy of nuclear zirconium alloys

    International Nuclear Information System (INIS)

    Versaci, R.A.; Ipohorski, Miguel

    1986-01-01

    Transmission electron microscopy observations of the microstructure of zirconium alloys used in fuel sheaths of nuclear power reactors are reported. Specimens were observed after different thermal and mechanical treatment, similar to those actually used during fabrication of the sheaths. Electron micrographs and electron diffraction patterns of second phase particles present in zircaloy-2 and zircaloy-4 were also obtained, as well as some characteristic parameters. Images of oxides and hydrides most commonly present in zirconium alloys are also shown. Finally, the structure of a Zr-2,5Nb alloy used in CANDU reactors pressure tubes, is observed by electron microscopy. (Author) [es

  18. 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

  19. Current assisted superplastic forming of titanium alloy

    Directory of Open Access Journals (Sweden)

    Wang Guofeng

    2015-01-01

    Full Text Available Current assisted superplastic forming combines electric heating technology and superplastic forming technology, and can overcome some shortcomings of traditional superplastic forming effectively, such as slow heating rate, large energy loss, low production efficiency, etc. Since formability of titanium alloy at room temperature is poor, current assisted superplastic forming is suitable for titanium alloy. This paper mainly introduces the application of current assisted superplastic forming in the field of titanium alloy, including forming technology of double-hemisphere structure and bellows.

  20. Stress corrosion cracking of titanium alloys

    Science.gov (United States)

    Statler, G. R.; Spretnak, J. W.; Beck, F. H.; Fontana, M. G.

    1974-01-01

    The effect of hydrogen on the properties of metals, including titanium and its alloys, was investigated. The basic theories of stress corrosion of titanium alloys are reviewed along with the literature concerned with the effect of absorbed hydrogen on the mechanical properties of metals. Finally, the basic modes of metal fracture and their importance to this study is considered. The experimental work was designed to determine the effects of hydrogen concentration on the critical strain at which plastic instability along pure shear directions occurs. The materials used were titanium alloys Ti-8Al-lMo-lV and Ti-5Al-2.5Sn.

  1. Graded coatings for metallic implant alloys

    Energy Technology Data Exchange (ETDEWEB)

    Saiz, Eduardo; Tomsia, Antoni P.; Fujino, Shigeru; Gomez-Vega, Jose M.

    2002-08-01

    Graded glass and glass-hydroxyapatite coatings on Ti-based and Co-Cr alloys have been prepared using a simple enameling technique. The composition of the glasses has been tailored to match the thermal expansion of the alloys. By controlling the firing time, and temperature, it has been possible to control the reactivity between the glass and the alloy and to fabricate coatings (25 to 150 mu m thick) with excellent adhesion to the substrate, resistant to corrosion and able to precipitate hydroxyapatite during in vitro tests in simulated body fluid.

  2. Pulse reversal plating of nickel alloys

    DEFF Research Database (Denmark)

    Tang, Peter Torben

    2007-01-01

    Pulse plating has previously been reported to improve the properties of nickel and nickel alloy deposits. Typically, focus has been on properties such as grain size, hardness and smoothness. When pulse plating is to be utilised for microtechnologies such as microelectromechanical systems (MEMS......), internal stress and material distribution are even more important. With baths based upon nickel chloride, and nickel and cobalt chlorides, pulse reversal plating of both pure nickel and nickel-cobalt alloys has been used to fabricate tools for microinjection moulding. Pulse reversal plating of ternary soft...... magnetic alloys, comprising 45-65%Co, 15-35%Fe and 15-35%Ni, is also reported....

  3. Electrochemical Impedance Spectroscopy Of Metal Alloys

    Science.gov (United States)

    Macdowell, L. G.; Calle, L. M.

    1993-01-01

    Report describes use of electrochemical impedance spectroscopy (EIS) to investigate resistances of 19 alloys to corrosion under conditions similar to those of corrosive, chloride-laden seaside environment of Space Transportation System launch site. Alloys investigated: Hastelloy C-4, C-22, C-276, and B-2; Inconel(R) 600, 625, and 825; Inco(R) G-3; Monel 400; Zirconium 702; Stainless Steel 304L, 304LN, 316L, 317L, and 904L; 20Cb-3; 7Mo+N; ES2205; and Ferralium 255. Results suggest electrochemical impedance spectroscopy used to predict corrosion performances of metal alloys.

  4. Comparison of Lost Foam Casting of AM60B Alloy and A356 Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Han, Qingyou [ORNL; Dinwiddie, Ralph Barton [ORNL; Sklad, Philip S [ORNL; Currie, Kenneth [Tennessee Technological University; Vondra, Fred [Tennessee Technological University; Abdelrahman, Mohamed [Tennessee Technological University; Walford, Graham [Walford Technologies; Nolan, Dennis J [Foseco-Morval; Nedkova, Teodora [Kaiser Aluminum

    2007-01-01

    The article describes the research activities at Oak Ridge National Laboratory and Tennessee Technological University on lost foam casting of magnesium alloys. The work was focused on castings of simple geometries such as plate castings and window castings in order to compare the difference in castability between magnesium alloys and aluminum alloy using the lost foam casting process. Significant differences between lost foam aluminum casting and lost foam magnesium casting have been observed.

  5. Influence of the selected alloy additions on limiting the phase formation in Cu-Zn alloys

    OpenAIRE

    J. Kozana; St. Rzadkosz; M. Piękoś

    2010-01-01

    Influence of the selected alloy additions into copper and zinc alloys was investigated in order to find out the possibility of limiting the precipitation of unfavourable phase . The observation of microstructures and strength tests were performed. The results of metallographic and strength investigations indicate positive influence of small amounts of nickel, cobalt or tellurium. The precise determination of the influence of the selected alloy additions on limiting the gamma phase formation ...

  6. Local atomic order in nanocrystalline Fe-based alloys obtained by mechanical alloying

    International Nuclear Information System (INIS)

    Jartych, E.

    2003-01-01

    Using the 57 Fe Moessbauer spectroscopy, a local atomic order in nanocrystalline alloys of iron with Al, Ni, W and Mo has been determined. Alloys were prepared by mechanical alloying method. Analysis of Moessbauer spectra was performed on the basis of the local environment model in terms of Warren-Cowley parameters. It was shown that impurity atoms are not randomly distributed in the volume of the first and the second co-ordination spheres of 57 Fe nuclei and they form clusters

  7. The Examination of the Aluminum Alloy 7017 as a Replacement for the Aluminum Alloy 7039 in Lightweight Armor Systems

    Science.gov (United States)

    2016-07-01

    Alloy 7039 in Lightweight Armor Systems by Tyrone L Jones and Brian E Placzankis Approved for public release...2016 US Army Research Laboratory The Examination of the Aluminum Alloy 7017 as a Replacement for the Aluminum Alloy 7039 in Lightweight Armor ...Aluminum Alloy 7017 as a Replacement for the Aluminum Alloy 7039 in Lightweight Armor Systems 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM

  8. Corrosion Mechanisms in Brazed Al-Base Alloy Sandwich Structures as a Function of Braze Alloy and Process Variables

    Science.gov (United States)

    2013-02-01

    alloying additions are predicted to optimize corrosion performance and be compatible with AA 6061 and 5052 from the standpoint of mitigating...34Corrosion of metals and alloys . Determination of resistance to intergranular corrosion of solution heat- treatable aluminium alloys " 1996. 25. ASTM...binary aluminium alloys —I. Al-Cu alloys . Pitting and intergranular corrosion," Corros Sei 17, 3 (1977): p. 179. 42. I.L. Müller and J.R. Galvele

  9. Determination of local constitutive properties of titanium alloy matrix in boron-modified titanium alloys using spherical indentation

    International Nuclear Information System (INIS)

    Sreeranganathan, A.; Gokhale, A.; Tamirisakandala, S.

    2008-01-01

    The constitutive properties of the titanium alloy matrix in boron-modified titanium alloys are different from those of the corresponding unreinforced alloy due to the microstructural changes resulting from the addition of boron. Experimental and finite-element analyses of spherical indentation with a large penetration depth to indenter radius ratio are used to compute the local constitutive properties of the matrix alloy. The results are compared with that of the corresponding alloy without boron, processed in the same manner

  10. Reducing thermal conductivity of binary alloys below the alloy limit via chemical ordering

    International Nuclear Information System (INIS)

    Duda, John C; English, Timothy S; Jordan, Donald A; Norris, Pamela M; Soffa, William A

    2011-01-01

    Substitutional solid solutions that exist in both ordered and disordered states will exhibit markedly different physical properties depending on their exact crystallographic configuration. Many random substitutional solid solutions (alloys) will display a tendency to order given the appropriate kinetic and thermodynamic conditions. Such order-disorder transitions will result in major crystallographic reconfigurations, where the atomic basis, symmetry, and periodicity of the alloy change dramatically. Consequently, the dominant scattering mechanism in ordered alloys will be different than that in disordered alloys. In this study, we present a hypothesis that ordered alloys can exhibit lower thermal conductivities than their disordered counterparts at elevated temperatures. To validate this hypothesis, we investigate the phononic transport properties of disordered and ordered AB Lennard-Jones alloys via non-equilibrium molecular dynamics and harmonic lattice dynamics calculations. It is shown that the thermal conductivity of an ordered alloy is the same as the thermal conductivity of the disordered alloy at ∼0.6T melt and lower than that of the disordered alloy above 0.8T melt .

  11. HAYNES 244 alloy – a new 760 ∘C capable low thermal expansion alloy

    Directory of Open Access Journals (Sweden)

    Fahrmann Michael G.

    2014-01-01

    Full Text Available HAYNES® 244TM alloy is a new 760∘C capable, high strength low thermal expansion (CTE alloy. Its nominal chemical composition in weight percent is Ni – 8 Cr – 22.5 Mo – 6 W. Recently, a first mill-scale heat of 244 alloy was melted by Haynes International, and processed to various product forms such as re-forge billet, plate, and sheet. This paper presents key attributes of this new alloy (CTE, strength, low-cycle fatigue performance, oxidation resistance, thermal stability as they pertain to the intended use in rings and seals of advanced gas turbines.

  12. Reaction kinetics of oxygen on single-phase alloys, oxidation of nickel and niobium alloys

    International Nuclear Information System (INIS)

    Lalauze, Rene

    1973-01-01

    This research thesis first addresses the reaction kinetics of oxygen on alloys. It presents some generalities on heterogeneous reactions (conventional theory, theory of jumps), discusses the core reaction (with the influence of pressure), discusses the influence of metal self-diffusion on metal oxidation kinetics (equilibrium conditions at the interface, hybrid diffusion regime), reports the application of the hybrid diffusion model to the study of selective oxidation of alloys (Wagner model, hybrid diffusion model) and the study of the oxidation kinetics of an alloy forming a solid solution of two oxides. The second part reports the investigation of the oxidation of single phase nickel and niobium alloys (phase α, β and γ)

  13. Wear resistance of alloy вт-22 with non-ferrous alloys at reverse

    Directory of Open Access Journals (Sweden)

    А.М. Хімко

    2010-01-01

    Full Text Available  The article presents the results of tests of non hardened titanium alloy ВТ-22 with aviation non-ferrous alloys in reverse sliding friction. The main objective of the work is the selection of the optimum combination of materials depending on changes in loading conditions. Study of alloy ВТ-22 wear resistance was carried out in pairs with БрОФ-10-1, БрБ2, БрАЖ-9-4, ВТ-22, МЛ5, Д16Т, 7Х21ГАН5Ш and 95Х18Ш. The dependencies of the materials wear at pressures 10, 20 and 30 Mpa we determined. The linear nature of titanium alloy wear curves indicates that the change in the wear mechanism occurs gradually. The histograms of non-ferrous materials wear and the total wear of the friction pair are presented. It is established that the bronze БрАЖ-9-4 is the most preferable material for contact with non hardened titanium alloy ВТ-22, the least wear among the tested materials. The established coefficients of the titanium alloy ВТ-22 friction in pair with aviation structural non-ferrous alloys are presented. The results of research will be relevant for the engineering industry, where non hardened titanium alloy ВТ-22 in pair with non-ferrous alloys is applied.

  14. Grain refinement of an AZ63B magnesium alloy by an Al-1C master alloy

    Energy Technology Data Exchange (ETDEWEB)

    Yichuan Pan; Xiangfa Liu; Hua Yang [The Key Lab. of Liquid Structure and Heredity of Materials, Shandong Univ., Jinan (China)

    2005-12-01

    In order to develop a refiner of Mg-Al alloys, an Al-1C (in wt.%) master alloy was synthesized using a casting method. The microstructure and grain-refining performance of the Al-1C master alloy were investigated using X-ray diffraction (XRD), electron probe microanalysis (EPMA) and a grain-refining test. The microstructure of the Al-1C master alloy is composed of {alpha}-Al solid solution, Al{sub 4}C{sub 3} particles, and graphite phases. After grain refinement of AZ63B alloy by the Al-1C master alloy, the mean grain size reached a limit when 2 wt.% Al-C master alloy was added at 800 C and held for 20 min in the melt before casting. The minimum mean grain size is approximately 48 {mu}m at the one-half radius of the ingot and is about 17% of that of the unrefined alloy. The Al-1C master alloy results in better grain refinement than C{sub 2}Cl{sub 6} and MgCO{sub 3} carbon-containing refiners. (orig.)

  15. Strength and fracture of two-phase alloys: a comparison of two alloy systems

    International Nuclear Information System (INIS)

    Gurland, J.

    1978-01-01

    The functional roles of the hard and soft constituents in the deformation and fracture of two-phase alloys are discussed on the basis of two commercially important alloy systems, namely spheroidized carbon steels and cemented carbides, WC-Co. A modified rule of mixtures provides a structural approach to the yield and flow strength. Consideration of the fracture toughness is attempted by means of a phenomenological modelling of the fracture process on the microscale. While there are large differences in properties between the two alloys, the deformation and fracture processes show broad smilarities which are associated with the features of the interaction between constituents common to both alloys

  16. Cytotoxicity of alloying elements and experimental titanium alloys by WST-1 and agar overlay tests.

    Science.gov (United States)

    Song, Yo-Han; Kim, Min-Kang; Park, Eun-Jin; Song, Ho-Jun; Anusavice, Kenneth J; Park, Yeong-Joon

    2014-09-01

    This study was performed to evaluate the biocompatibility of nine types of pure metals using 36 experimental prosthetic titanium-based alloys containing 5, 10, 15, and 20wt% of each substituted metal. The cell viabilities for pure metals on Ti alloys that contain these elements were compared with that of commercially pure (CP) Ti using the WST-1 test and agar overlay test. The ranking of pure metal cytotoxicity from most potent to least potent was: Co>Cu>In>Ag>Cr>Sn>Au>Pd>Pt>CP Ti. The cell viability ratios for pure Co, Cu, In, and Ag were 13.9±4.6%, 21.7±10.4%, 24.1±5.7%, and 24.8±6.0%, respectively, which were significantly lower than that for the control group (pcytotoxic', whereas all Ti alloys were ranked as 'noncytotoxic'. The cytotoxicity of pure Ag, Co, Cr, Cu, and In suggests a need for attention in alloy design. The cytotoxicity of alloying elements became more biocompatible when they were alloyed with titanium. However, the cytotoxicity of titanium alloys was observed when the concentration of the alloying element exceeded its respective allowable limit. The results obtained in this study can serve as a guide for the development of new Ti-based alloy systems. Copyright © 2014 Academy of Dental Materials. All rights reserved.

  17. Ageing of zirconium alloy components

    Science.gov (United States)

    Chatterjee, S.; Shah, Priti Kotak; Dubey, J. S.

    2008-12-01

    India has two types (pressurized heavy water reactors (PHWRs) and boiling water reactors (BWRs)) of commercial nuclear reactors in operation, in addition to research reactors. Many of the life limiting critical components in these reactors are fabricated from zirconium alloys. The progressive degradation of these components caused by the cumulative exposure of high energy neutron irradiation with increasing period of reactor operation was monitored to assess the degree of ageing. The components/specimens examined included fuel element claddings removed from BWRs, pressure tubes and garter springs removed from PHWRs and calandria tube specimens used in PHWRs. The tests included tension test (for cladding, garter spring), fracture toughness test (for pressure tube), crush test (for garter spring), and measurement of irradiation induced growth (for calandria tube). Results of various tests conducted are presented and applications of the test results are elaborated for residual life estimation/life extension of the components.

  18. Shape memory alloy consortium (SMAC)

    Science.gov (United States)

    Jacot, A. Dean

    1999-07-01

    The application of smart structures to helicopter rotors has received widespread study in recent years. This is one of the major thrusts of the Shape Memory Alloy Consortium (SMAC) program. SMAC includes 3 companies and 4 Universities in a cost sharing consortium funded under DARPA Smart Materials and Structures program. This paper describes the objective of the SMAC effort, and its relationship to a previous DARPA smart structure rotorcraft program from which it originated. The SMAC program includes NiTinol fatigue/characterization studies, SMA actuator development, and ferromagnetic SMA material development. The paper summarizes the SMAC effort, and includes background and details on Boeing's development of a SMA torsional actuator for rotorcraft applications. SMA actuation is used to retwist the rotorcraft blade in flight, and result in a significant payload increase for either helicopters or tiltrotors. This paper is also augmented by several other papers in this conference with specific results from other SMAC consortium members.

  19. Incology alloy 908 data handbook

    Energy Technology Data Exchange (ETDEWEB)

    Toma, L.S.; Steeves, M.M. [Massachusetts Institute of Technology, Cambridge, MA (United States); Reed, R.P. [Cryogenic Materials Inc., Boulder, CO (United States)

    1994-03-01

    This handbook is a compilation of all available properties of Incoloy alloy 908 as of March, 1994. Data included in this paper cover mechanical, elastic, thermal and magnetic characteristics. The mechanical properties include tensile, fracture toughness, fatigue, and stress-rupture for both the base metal and related weld filler metals. Elastic properties listed are Young`s, shear and bulk moduli and Poisson`s ratio. Thermal expansion, thermal conductivity and specific heat and magnetization are also reported. Data presented are summarized in the main body and presented in detail in the supplements. Areas of ongoing research are briefly described, and topics for future research are suggested. The data have been compiled to assist in the design of large-scale superconducting magnets for fusion reactors.

  20. Silver-hafnium braze alloy

    Science.gov (United States)

    Stephens, Jr., John J.; Hosking, F. Michael; Yost, Frederick G.

    2003-12-16

    A binary allow braze composition has been prepared and used in a bonded article of ceramic-ceramic and ceramic-metal materials. The braze composition comprises greater than approximately 95 wt % silver, greater than approximately 2 wt % hafnium and less than approximately 4.1 wt % hafnium, and less than approximately 0.2 wt % trace elements. The binary braze alloy is used to join a ceramic material to another ceramic material or a ceramic material, such as alumina, quartz, aluminum nitride, silicon nitride, silicon carbide, and mullite, to a metal material, such as iron-based metals, cobalt-based metals, nickel-based metals, molybdenum-based metals, tungsten-based metals, niobium-based metals, and tantalum-based metals. A hermetic bonded article is obtained with a strength greater than 10,000 psi.

  1. Low content uranium alloys for nuclear fuels

    International Nuclear Information System (INIS)

    Aubert, H.; Laniesse, J.

    1964-01-01

    A description is given of the structure and the properties of low content alloys containing from 0.1 to 0.5 per cent by weight of Al, Fe, Cr, Si, Mo or a combination of these elements. A study of the kinetics and of the mode of transformation has made it possible to choose the most satisfactory thermal treatment. An attempt has been made to prepare alloys suitable for an economical industrial development having a small α grain structure without marked preferential orientation, with very fine and stable precipitates as well as a high creep-resistance. The physical properties and the mechanical strength of these alloys are given for temperatures of 20 to 600 deg C. These alloys proved very satisfactory when irradiated in the form of normal size fuel elements. (authors) [fr

  2. STACKING FAULT ENERGY IN HIGH MANGANESE ALLOYS

    Directory of Open Access Journals (Sweden)

    Eva Mazancová

    2009-04-01

    Full Text Available Stacking fault energy of high manganese alloys (marked as TWIP and TRIPLEX is an important parameter determining deformation mechanism type realized in above mentioned alloys. Stacking fault energy level can be asserted with a gliding of partial and/or full dislocations, b gliding mechanism and twinning deformation process in connection with increasing of fracture deformation level (deformation elongation and with increasing of simultaneously realized work hardening proces., c gliding mechanism and deformation induced e-martensite formation. In contribution calculated stacking fault energies are presented for various chemical compositions of high manganese alloys. Stacking fault energy dependences on manganese, carbon, iron and alluminium contents are presented. Results are confronted with some accessible papers.The aim of work is to deepen knowledge of presented data. The TWIP and TRIPLEX alloys can be held for promissing new automotive materials.

  3. LOST FOAM CASTING OF MAGNESIUM ALLOYS

    Energy Technology Data Exchange (ETDEWEB)

    Han, Qingyou [ORNL; Dinwiddie, Ralph Barton [ORNL; Sklad, Philip S [ORNL; Currie, Kenneth [Tennessee Technological University; Abdelrahman, Mohamed [Tennessee Technological University; Vondra, Fred [Tennessee Technological University; Walford, Graham [Walford Technologies; Nolan, Dennis J [Foseco-Morval

    2007-01-01

    The lost foam casting process has been successfully used for making aluminum and cast iron thin walled castings of complex geometries. Little work has been carried out on cast magnesium alloys using the lost foam process. The article describes the research activities at Oak Ridge National Laboratory and Tennessee Technological University on lost foam casting of magnesium alloys. The work was focused on castings of simple geometries such as plate castings and window castings. The plate castings were designed to investigate the mold filling characteristics of magnesium and aluminum alloys using an infrared camera. The pate castings were then characterized for porosity distribution. The window castings were made to test the castability of the alloys under lost foam conditions. Significant differences between lost foam aluminum casting and lost foam magnesium casting have been observed.

  4. Combustion synthesis of bulk nanocrystalline iron alloys

    Directory of Open Access Journals (Sweden)

    Licai Fu

    2016-02-01

    Full Text Available The controlled synthesis of large-scale nanocrystalline metals and alloys with predefined architecture is in general a big challenge, and making full use of these materials in applications still requires greatly effort. The combustion synthesis technique has been successfully extended to prepare large-scale nanocrystalline metals and alloys, especially iron alloy, such as FeC, FeNi, FeCu, FeSi, FeB, FeAl, FeSiAl, FeSiB, and the microstructure can be designed. In this issue, recent progress on the synthesis of nanocrystalline metals and alloys prepared by combustion synthesis technique are reviewed. Then, the mechanical and tribological properties of these materials with microstructure control are discussed.

  5. Phases in lanthanum-nickel-aluminum alloys

    International Nuclear Information System (INIS)

    Mosley, W.C.

    1992-01-01

    Lanthanum-nickel-aluminum (LANA) alloys will be used to pump, store and separate hydrogen isotopes in the Replacement Tritium Facility (RTF). The aluminum content (y) of the primary LaNi 5 -phase is controlled to produce the desired pressure-temperature behavior for adsorption and desorption of hydrogen. However, secondary phases cause decreased capacity and some may cause undesirable retention of tritium. Twenty-three alloys purchased from Ergenics, Inc. for development of RTF processes have been characterized by scanning electron microscopy (SEM) and by electron microprobe analysis (EMPA) to determine the distributions and compositions of constituent phases. This memorandum reports the results of these characterization studies. Knowledge of the structural characteristics of these alloys is a useful first step in selecting materials for specific process development tests and in interpreting results of those tests. Once this information is coupled with data on hydrogen plateau pressures, retention and capacity, secondary phase limits for RTF alloys can be specified

  6. Tough and corrosion resistant austenitic alloy

    International Nuclear Information System (INIS)

    Johnson, T.E.

    1977-01-01

    The invention concerns austenitic alloys of high corrosion resistance, which can be deformed hot and tempered, so that they can be forged, rolled, and drawn into tubes and other shapes. The alloys have a basis of nickel, chromium and iron. The silicon content is between 2 and 4% by weight, and the molybdenum content is between 0 and 2% by weight. The alloys can be hardened by ageing and contain up to 0.1% by weight of boron. The other alloying materials are 1 to 3.5% by weight of manganese, 4 to 7.5% by weight of cobalt, 2.5 to 8% by weight of copper and 0.05 to 0.25% by weight of carbon. (IHOE) [de

  7. Steam Initiated Surface Modification of Aluminium Alloys

    DEFF Research Database (Denmark)

    Din, Rameez Ud

    The extensive demand of aluminium alloys in various industries such as in transportationis mainly due to the high strength to weight ratio, which could be translated into fuel economy and efficiency. Corrosion protection of aluminium alloys is an important aspect for all applications which includes...... to 12 present various experimental results in the form of appended papers. The chapters consist of the experimental results obtained by the use of steam-based process and its effect on microstructureand corrosion resistance of the alloy as a function of steam pressure, use of various chemicals...... the use of aluminium alloys in the painted form requiring a conversion coating to improve the adhesion. Chromate based conversion coating processes are extremely good for these purposes, however the carcinogenic and toxic nature of hexavalent chromium led to the search for more benign and eco...

  8. Filler metal development for Hastelloy alloy XR

    International Nuclear Information System (INIS)

    Watanabe, Katsutoshi; Nakajima, Hajime; Sahira, Kensho

    1991-11-01

    In order to develop the filler metal for Hastelloy alloy XR structure with thick wall, the weldability and high temperature strength properties of Hastelloy alloy XR weldment were investigated using the filler metals, which were alloy-designed on the basis of multiple regression analysis. The former was examined through the chemical analysis in the deposited metal, bend test, FISCO cracking test, optical microscopy and hardness measurement. The latter was investigated by means of tensile and creep test. It was found from these results that the crack susceptibility in the weldment was apparent to be lowered without degrading the high temperature strength properties. Therefore, it is concluded that these filler metals possess excellent performance as the filler metal for Hastelloy alloy XR structure with thick wall. (author)

  9. NASA-427: A New Aluminum Alloy

    Science.gov (United States)

    Nabors, Sammy A.

    2015-01-01

    NASA's Marshall Space Flight Center researchers have developed a new, stronger aluminum alloy, ideal for cast aluminum products that have powder or paint-baked thermal coatings. With advanced mechanical properties, the NASA-427 alloy shows greater tensile strength and increased ductility, providing substantial improvement in impact toughness. In addition, this alloy improves the thermal coating process by decreasing the time required for heat treatment. With improvements in both strength and processing time, use of the alloy provides reduced materials and production costs, lower product weight, and better product performance. The superior properties of NASA-427 can benefit many industries, including automotive, where it is particularly well-suited for use in aluminum wheels.

  10. Stress-corrosion cracking of titanium alloys.

    Science.gov (United States)

    Blackburn, M. J.; Feeney, J. A.; Beck, T. R.

    1973-01-01

    In the light of research material published up to May 1970, the current understanding of the experimental variables involved in the stress-corrosion cracking (SCC) behavior of titanium and its alloys is reviewed. Following a brief summary of the metallurgy and electrochemistry of titanium alloys, the mechanical, electrochemical, and metallurgical parameters influencing SCC behavior are explored with emphasis on crack growth kinetics. Macro- and microfeatures of fractures are examined, and it is shown that many transgranular SCC failures exhibit morphological and crystallographic features similar to mechanical cleavage failures. Current SCC models are reviewed with respect to their ability to explain the observed SCC behavior of titanium and its alloys. Possible methods for eliminating or minimizing stress corrosion hazards in titanium or titanium alloy components are described.

  11. Towards an understanding of zirconium alloy corrosion

    International Nuclear Information System (INIS)

    Cox, B.

    1976-08-01

    A brief historical summary is given of the development of a programme for understanding the corrosion mechanisms operating for zirconium alloys. A general summary is given of the progress made, so far, in carrying through this programme. (author)

  12. Additive Manufacturing of Magnesium (Mg) Alloys

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed work is to investigate additive manufacturing techniques for Mg alloys.  It will leverage off research being conducted at University of Florida and...

  13. Pitting corrosion of 5052 aluminum alloy

    Science.gov (United States)

    Lockwood, F.; Lee, S.; Faunce, J.; Green, J. A. S.; Ptashnick, W. J.

    1985-01-01

    The relative degree of pitting of 5052 aluminum alloy in a prepaint cleaning process is correlated with the proportion of MgO in the surface oxide of the alloy. Magnesium oxide, formed on the surface during process heat treatments of the alloy, is soluble in the acidic environment of the particular cleaning solutions, thus allowing easier access of corrosive ion to the aluminum metal. The pitting mechanism involves the: (1) formation of microscopic, localized galvanic cells between aluminum (anode) and iron-containing constituents (cathodic sites) normally found in the matrix of 5052 (and other 5xxx aluminum alloys), (2) aggravation of pit formation by chloride, and (3) enhancement of cathodic reactions and hence the overall corrosion process due to penetration of the oxide layer by cupric and ferric ions, and dissolved O 2 present in the cleaning solutions. Pitting was eliminated by adding 0.1% NaNO 3 to the cleaning bath.

  14. Theory of Rare-Earth Alloys

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker

    1977-01-01

    A mean-field random alloy theory combined with a simple calculation of the exchange interaction J(c,Q) is shown to quantitatively account for the phase diagrams for alloys of rare-earth metals with Y, Lu, Sc, and other rare-earth metals. A concentration-dependent J(c,Q) explains the empirical 2...... to account for all alloys except the Sc based. The exceptional behavior of the Sc alloys is due to a low density of states for Sc. A brief discussion is given of the effect on the mean-field results of changes in volume or c/a ratio and of critical fluctuations. Since the physical mechanisms of these ideal...

  15. Shape Memory Alloy Adaptive Structures, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase I effort will demonstrate and scale up an innovative manufacturing process that yields aerospace grade shape memory alloy (SMA) solids and periodic...

  16. Room temperature creep in metals and alloys

    Energy Technology Data Exchange (ETDEWEB)

    Deibler, Lisa Anne [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Materials Characterization and Performance

    2014-09-01

    Time dependent deformation in the form of creep and stress relaxation is not often considered a factor when designing structural alloy parts for use at room temperature. However, creep and stress relaxation do occur at room temperature (0.09-0.21 Tm for alloys in this report) in structural alloys. This report will summarize the available literature on room temperature creep, present creep data collected on various structural alloys, and finally compare the acquired data to equations used in the literature to model creep behavior. Based on evidence from the literature and fitting of various equations, the mechanism which causes room temperature creep is found to include dislocation generation as well as exhaustion.

  17. Viscosity of Ga-Li liquid alloys

    Science.gov (United States)

    Vidyaev, Dmitriy; Boretsky, Evgeny; Verkhorubov, Dmitriy

    2018-03-01

    The measurement of dynamic viscosity of Ga-Li liquid alloys has been performed using low-frequency vibrational viscometer at five temperatures in the range 313-353 K and four gallium-based dilute alloy compositions containing 0-1.15 at.% Li. It was found that the viscosity of the considered alloys increases with decreasing temperature and increasing lithium concentration in the above ranges. It was shown that dependence of the viscosity of Ga-Li alloys in the investigated temperature range has been described by Arrhenius equation. For this equation the activation energy of viscous flow and pre-exponential factor were calculated. This study helped to determine the conditions of the alkali metals separating process in gallam-exchange systems.

  18. Sulfidation behavior of Fe20Cr alloys

    International Nuclear Information System (INIS)

    Pillis, Marina Fuser

    2001-01-01

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

  19. Thermodynamic properties of indium-antimony alloys

    International Nuclear Information System (INIS)

    Gerasimov, Ya.I.; Goryacheva, V.I.; Gejderikh, V.A.

    1988-01-01

    Method of electromotive forces is used to obtain thermodynamic parameters of reaction of In x Sb (1-x) phase formation from liquid indium and solid indium mono-antimonide. For alloy compositions with x=0.75-0.55 liquidus coordinates on phase diagram are determined. Nonmonotonous dependence of partial entropy and enthalpy of indium on composition of liquid alloys, that is connected with ordering, is detected. 20 refs.; 2 figs.; 2 tabs

  20. Anomalous lattice parameter of magnetic semiconductor alloys

    OpenAIRE

    CAETANO, Clovis; MARQUES, Marcelo; FERREIRA, Luiz G.; TELES, Lara K.

    2009-01-01

    The addition of transition metals (TM) to III-V semiconductors radically changes their electronic, magnetic and structural properties. In contrast to the conventional semiconductor alloys, the lattice parameter in magnetic semiconductor alloys, including the ones with diluted concentration (the diluted magnetic semiconductors - DMS), cannot be determined uniquely from the composition. By using first-principles calculations, we find a direct correlation between the magnetic moment and the anio...

  1. Composition profile determination in isomorphous binary alloys

    International Nuclear Information System (INIS)

    An, C.Y.; Bandeira, I.N.

    1983-07-01

    The inhomogeneity along the growth axis of the pseudo-binary alloys is due to the segregation of the solute which will be mixed in the melt due to convective and diffusive flows. A process for determination of the exact composition profile by measurements of the crystal density, for alloys of the type A sub(1-x) B sub(x), is shown. (Author) [pt

  2. Rapidly solidified long-range-ordered alloys

    International Nuclear Information System (INIS)

    Lee, E.H.; Koch, C.C.; Liu, C.T.

    1981-01-01

    The influence of rapid solidification processing on the microstructure of long-range-ordered alloys in the (Fe, Co, Ni) 3 V system has been studied by transmission electron microscopy. The main microstructural feature of the as-quenched alloys was a fine cell structure (approx. 300 nm diameter) decorated with carbide particles. This structure was maintained aftr annealing treatments which develop the ordered crystal structure. Other features of the microstructures both before and after annealing are presented and discussed. 6 figures

  3. Hydrogen Assisted Cracking of High Strength Alloys

    Science.gov (United States)

    2003-08-01

    equilibrium H content for unstressed exposure of the superalloy in a given H2 pressure ( PH2 ) and temperature (T) environment, coupled with enhancement...CRACKING OF HIGH STRENGTH ALLOYS Richard P. Ganqloff August, 2003 Page 72 of 194 decreasing pH , H2S addition, temperature , and other chemical variables...mechanism for stress corrosion cracking (SCC) and sulfide stress cracking for alloys in aqueous H2S -bearing electrolytes. Electrochemical reactions leading

  4. Phonon broadening in high entropy alloys

    Science.gov (United States)

    Körmann, Fritz; Ikeda, Yuji; Grabowski, Blazej; Sluiter, Marcel H. F.

    2017-09-01

    Refractory high entropy alloys feature outstanding properties making them a promising materials class for next-generation high-temperature applications. At high temperatures, materials properties are strongly affected by lattice vibrations (phonons). Phonons critically influence thermal stability, thermodynamic and elastic properties, as well as thermal conductivity. In contrast to perfect crystals and ordered alloys, the inherently present mass and force constant fluctuations in multi-component random alloys (high entropy alloys) can induce significant phonon scattering and broadening. Despite their importance, phonon scattering and broadening have so far only scarcely been investigated for high entropy alloys. We tackle this challenge from a theoretical perspective and employ ab initio calculations to systematically study the impact of force constant and mass fluctuations on the phonon spectral functions of 12 body-centered cubic random alloys, from binaries up to 5-component high entropy alloys, addressing the key question of how chemical complexity impacts phonons. We find that it is crucial to include both mass and force constant fluctuations. If one or the other is neglected, qualitatively wrong results can be obtained such as artificial phonon band gaps. We analyze how the results obtained for the phonons translate into thermodynamically integrated quantities, specifically the vibrational entropy. Changes in the vibrational entropy with increasing the number of elements can be as large as changes in the configurational entropy and are thus important for phase stability considerations. The set of studied alloys includes MoTa, MoTaNb, MoTaNbW, MoTaNbWV, VW, VWNb, VWTa, VWNbTa, VTaNbTi, VWNbTaTi, HfZrNb, HfMoTaTiZr.

  5. Thermomechanical macroscopic model of shape memory alloys

    International Nuclear Information System (INIS)

    Volkov, A.E.; Sakharov, V.Yu.

    2003-01-01

    The phenomenological macroscopic model of the mechanical behaviour of the titanium nickelide-type shape memory alloys is proposed. The model contains as a parameter the average phase shear deformation accompanying the martensite formation. It makes i possible to describe correctly a number of functional properties of the shape memory alloys, in particular, the pseudoelasticity ferroplasticity, plasticity transformation and shape memory effects in the stressed and unstressed samples [ru

  6. Properties isotropy of magnesium alloy strip workpieces

    OpenAIRE

    Р. Кавалла; В. Ю. Бажин

    2016-01-01

    The paper discusses the issue of obtaining high quality cast workpieces of magnesium alloys produced by strip roll-casting. Producing strips of magnesium alloys by combining the processes of casting and rolling when liquid melt is fed continuously to fast rolls is quite promising and economic. In the process of sheet stamping considerable losses of metal occur on festoons formed due to anisotropy of properties of foil workpiece, as defined by the macro- and microstructure and modes of rolling...

  7. Manufacturing development of low activation vanadium alloys

    International Nuclear Information System (INIS)

    Smith, J.P.; Johnson, W.R.; Baxi, C.B.

    1996-10-01

    General Atomics is developing manufacturing methods for vanadium alloys as part of a program to encourage the development of low activation alloys for fusion use. The culmination of the program is the fabrication and installation of a vanadium alloy structure in the DIII-D tokamak as part of the Radiative Divertor modification. Water-cooled vanadium alloy components will comprise a portion of the new upper divertor structure. The first step, procuring the material for this program has been completed. The largest heat of vanadium alloy made to date, 1200 kg of V-4Cr-4Ti, has been produced and is being converted into various product forms. Results of many tests on the material during the manufacturing process are reported. Research into potential fabrication methods has been and continues to be performed along with the assessment of manufacturing processes particularly in the area of joining. Joining of vanadium alloys has been identified as the most critical fabrication issue for their use in the Radiative Divertor Program. Joining processes under evaluation include resistance seam, electrodischarge (stud), friction and electron beam welding. Results of welding tests are reported. Metallography and mechanical tests are used to evaluate the weld samples. The need for a protective atmosphere during different welding processes is also being determined. General Atomics has also designed, manufactured, and will be testing a helium-cooled, high heat flux component to assess the use of helium cooled vanadium alloy components for advanced tokamak systems. The component is made from vanadium alloy tubing, machined to enhance the heat transfer characteristics, and joined to end flanges to allow connection to the helium supply. Results are reported

  8. Microscopic Analysis of Welded Dental Alloys

    OpenAIRE

    S. Porojan; L. Sandu; F. Topalâ

    2011-01-01

    Microplasma welding is a less expensive alternative to laser welding in dental technology. The aim of the study was to highlight discontinuities present in the microplasma welded joints of dental base metal alloys by visual analysis. Five base metal alloys designated for fixed prostheses manufacture were selected for the experiments. Using these plates, preliminary tests were conducted by microplasma welding in butt joint configuration, without filler material, bilaterall...

  9. Progress in Preparation and Research of High Entropy Alloys

    Directory of Open Access Journals (Sweden)

    CHEN Yong-xing

    2017-11-01

    Full Text Available The current high entropy alloys' studies are most in block, powder, coating, film and other areas. There are few studies of high entropy alloys in other areas and they are lack of unified classification. According to the current high entropy alloys' research situation, The paper has focused on the classification on all kinds of high entropy alloys having been researched, introduced the selecting principle of elements, summarized the preparation methods, reviewed the research institutions, research methods and research contents of high entropy alloys, prospected the application prospect of high entropy alloys, put forward a series of scientific problems of high entropy alloys, including less research on mechanism, incomplete performance research, unsystematic thermal stability study, preparation process parameters to be optimized, lightweight high entropy alloys' design, the expansion on the research field, etc, and the solutions have been given. Those have certain guiding significance for the expansion of the application of high entropy alloys subjects in the future research direction.

  10. Strength and microstructure of gallium alloys.

    Science.gov (United States)

    Miller, B H; Woldu, M; Nakajima, H; Okabe, T

    1999-03-01

    This study investigated the physical and mechanical properties and the microstructure of four different gallium alloys. For all gallium alloys, the compressive strengths measured at one hour (86-223 MPa) and 24 hours (265-286 MPa) after specimen preparation were found to be well within the range exhibited by many high-copper amalgams. The creep values and dimensional change of the gallium alloys were comparable to those of leading amalgams, except for the dimensional change value of one alloy. The set gallium alloys consisted of a multi-phase structure including beta-Sn, CuGa2, In4Ag9, Ag72Ga28, and Ga5Pd (except for one product that did not contain Pd) that was more complicated than the structure of dental amalgams. Although the gallium alloys had physical and mechanical properties comparable to those of high-copper amalgams, the microstructure, coupled with the instability of the element gallium itself, could make these materials more prone to corrosive attack compared to amalgams.

  11. Nanoprecipitation in a beta-titanium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Coakley, James, E-mail: j.coakley06@imperial.ac.uk [Department of Materials, Imperial College, South Kensington, London SW7 2AZ, England (United Kingdom); Vorontsov, Vassili A. [Department of Materials, Imperial College, South Kensington, London SW7 2AZ, England (United Kingdom); Littrell, Kenneth C. [Oak Ridge National Laboratory, Chemical and Engineering Materials Division, Oak Ridge, TN 37831 (United States); Heenan, Richard K. [Rutherford Appleton Laboratory, Didcot, Oxon OX11 0QX, England (United Kingdom); Ohnuma, Masato [Laboratory of Quantum Beam System Engineering, Hokkaido University, Sapporo 060-0808 (Japan); Jones, Nicholas G. [Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ, England (United Kingdom); Dye, David [Department of Materials, Imperial College, South Kensington, London SW7 2AZ, England (United Kingdom)

    2015-02-25

    Highlights: • In-situ SANS has been applied to study precipitation in β -Ti alloy. • Rate of precipitation is far more rapid in the cold-rolled alloy than non cold-rolled. • The rapid precipitation dramatically improves the alloy hardness. • Extensive ω phase is present after 400 °C/16 h heat-treatment. • SANS modelling and TEM-EDX shows the precipitates are Ti rich. - Abstract: This paper represents the first application of small angle neutron scattering (SANS) to the study of precipitate nucleation and growth in β-Ti alloys in an attempt to observe both the precipitation process in-situ and to quantify the evolving microstructure that affects mechanical behaviour. TEM suggests that athermal ω can be induced by cold-rolling Gum metal, a β-Ti alloy. During thermal exposure at 400°C, isothermal ω particles precipitate at a greater rate in cold-rolled material than in the recovered, hot deformed state. SANS modelling is consistent with disc shaped nanoparticles, with length and radius under 6nm after thermal exposures up to 16h. Modelling suggests that the nanoprecipitate volume fraction and extent of Nb partitioning to the β matrix is greater in the cold-rolled material than the extruded. The results show that nucleation and growth of the nanoprecipitates impart strengthening to the alloy.

  12. Nickel-base alloys for severe environments

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, R.K.; Flower, H.L. [Inco Alloys International Inc., Huntington, WV (United States); Hack, G.A.J. [Inco Alloys Ltd., Hereford (United Kingdom); Isobe, S. [Daido Steel Co. Ltd., Nagoya (Japan)

    1996-03-01

    Inconel alloys MA754 and MA758 are nickel-base, oxide dispersion-strengthened superalloys made by mechanical alloying. The simple nickel-chromium matrix, when combined with the strengthening effect of the yttrium oxide dispersoid during mechanical alloys, provides excellent creep properties, resistance to thermal fatigue, and surface stability suitable for operation without protective coatings. Gas turbine engine components are primary applications for alloy MA754, but this aerospace alloy has been applied in many other products that operate in severe conditions, and alloy MA758 was developed specifically for aggressive, elevated temperature industrial environments. Billets for large bar and plate are typically consolidated by hot isostatic pressing (HIP), because this technology allows production of forms suitable for a variety of industrial components. Material consolidated by HIP and conventionally worked by extrusion and hot rolling generally exhibits properties that are more isotropic than those of material consolidated by extrusion. However, the degree of anisotropy depends strongly on the specific processing of the consolidated billet. This article describes production of new mill shapes from HIP billets, and reviews current and potential applications such as skid rails for high-temperature walking-beam furnaces, heat treating furnace parts, equipment for handling molten glass, and furnace tubes.

  13. Surface energy of metal alloy nanoparticles

    Science.gov (United States)

    Takrori, Fahed M.; Ayyad, Ahmed

    2017-04-01

    The measurement of surface energy of alloy nanoparticles experimentally is still a challenge therefore theoretical work is necessary to estimate its value. In continuation of our previous work on the calculation of the surface energy of pure metallic nanoparticles we have extended our work to calculate the surface energy of different alloy systems, namely, Co-Ni, Au-Cu, Cu-Al, Cu-Mg and Mo-Cs binary alloys. It is shown that the surface energy of metallic binary alloy decreases with decreasing particle size approaching relatively small values at small sizes. When both metals in the alloy obey the Hume-Rothery rules, the difference in the surface energy is small at the macroscopic as well as in the nano-scale. However when the alloy deviated from these rules the difference in surface energy is large in the macroscopic and in the nano scales. Interestingly when solid solution formation is not possible at the macroscopic scale according to the Hume-Rothery rules, it is shown it may form at the nano-scale. To our knowledge these findings here are presented for the first time and is challenging from fundamental as well as technological point of views.

  14. Fabrication of Ti-Cu-Ni-Al amorphous alloys by mechanical alloying and mechanical milling

    International Nuclear Information System (INIS)

    Kishimura, Hiroaki; Matsumoto, Hitoshi

    2011-01-01

    Research highlights: → Ti-based amorphous alloys are produced by the mechanical alloying and by the mechanical milling. → The amorphization by the mechanical alloying is slower than that by the mechanical milling. → Activation energy and temperature of crystallization of both alloys are different. - Abstract: Ti-based amorphous alloy powders were synthesized by the mechanical alloying (MA) of pure elements and the mechanical milling (MM) of intermetallic compounds. The amorphous alloy powders were examined by X-ray diffraction (XRD), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). Scanning electron micrographs revealed that the vein morphology of these alloy powders shows deformation during the milling. The energy-dispersive X-ray spectral maps confirm that each constituent is uniformly dispersed, including Fe and Cr. The XRD and DSC results showed that the milling time required for amorphization for the MA of pure elements was longer than that of the MM for intermetallic compounds. The activation energy and crystallization temperature of the MA powder are different from those of the MM powder.

  15. 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.

  16. Corrosion and wear protective composition modulated alloy coatings based on ternary Ni-P-X alloys

    DEFF Research Database (Denmark)

    Leisner, P.; Benzon, M. E.; Christoffersen, Lasse

    1996-01-01

    Scattered reporting in the litterature describes a number of ternary Ni-P-X alloyes (where X can be Co, Cr, Cu, Mo, Pd, Re or W) with promising corrosin and wear protective performance. Based on a systematic study of Ni-P-X alloys it is the intention to produce coatings with improved corrosion...

  17. First principles analysis of hydrogen chemisorption on Pd-Re alloyed overlayers and alloyed surfaces

    DEFF Research Database (Denmark)

    Pallassana, Venkataraman; Neurock, Matthew; Hansen, Lars Bruno

    2000-01-01

    Gradient corrected periodic density functional theory (DFT-GGA) slab calculations were used to examine the chemisorption of atomic hydrogen on various Pd-Re alloyed overlayers and uniformly alloyed surfaces. Adsorption was examined at 33% surface coverage, where atomic hydrogen preferred the thre...

  18. AN ELECTROPLATING METHOD OF FORMING PLATINGS OF NICKEL, COBALT, NICKEL ALLOYS OR COBALT ALLOYS

    DEFF Research Database (Denmark)

    1997-01-01

    An electroplating method of forming platings of nickel, cobalt, nickel alloys or cobalt alloys with reduced stresses in an electrodepositing bath of the type: Watt's bath, chloride bath or a combination thereof, by employing pulse plating with periodic reverse pulse and a sulfonated naphthalene...... additive. This method makes it possible to deposit nickel, cobalt, nickel or cobalt platings without internal stresses....

  19. Improvement of magnetocaloric properties of Gd-Ge-Si alloys by alloying with iron

    Directory of Open Access Journals (Sweden)

    Erenc-Sędziak T.

    2013-01-01

    Full Text Available The influence of annealing of Gd5Ge2Si2Fex alloys at 1200°C and of alloying with various amount of iron on structure as well as thermal and magnetocaloric properties is investigated. It was found that annealing for 1 to 10 hours improves the entropy change, but reduces the temperature of maximum magnetocaloric effect by up to 50 K. Prolonged annealing of the Gd5Ge2Si2 alloy results in the decrease of entropy change due to the reduction of Gd5Ge2Si2 phase content. Addition of iron to the ternary alloy enhances the magnetocaloric effect, if x = 0.4 – 0.6, especially if alloying is combined with annealing at 1200°C: the peak value of the isothermal entropy change from 0 to 2 T increases from 3.5 to 11 J/kgK. Simultaneously, the temperature of maximum magnetocaloric effect drops to 250 K. The changes in magnetocaloric properties are related to the change in phase transformation from the second order for arc molten ternary alloy to first order in the case of annealed and/or alloyed with iron. The results of this study indicate that the minor addition of iron and heat treatment to Gd-Ge-Si alloys may be useful in improving the materials’ magnetocaloric properties..

  20. 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.

  1. Study on microstructure and properties of Mg-alloy surface alloying layer fabricated by EPC

    Directory of Open Access Journals (Sweden)

    Chen Dongfeng

    2010-02-01

    Full Text Available AZ91D surface alloying was investigated through evaporative pattern casting (EPC technology. Aluminum powder (0.074 to 0.104 mm was used as the alloying element in the experiment. An alloying coating with excellent properties was fabricated, which mainly consisted of adhesive, co-solvent, suspending agent and other ingredients according to desired proportion. Mg-alloy melt was poured under certain temperature and the degree of negative pressure. The microstructure of the surface layer was examined by means of scanning electron microscopy. It has been found that a large volume fraction of network new phases were formed on the Mg-alloy surface, the thickness of the alloying surface layer increased with the alloying coating increasing from 0.3 mm to 0.5 mm, and the microstructure became compact. Energy dispersive X-ray (EDX analysis was used to determine the chemical composition of the new phases. It showed that the new phases mainly consist of β-Mg17Al12, in addition to a small quantity of inter-metallic compounds and oxides. A micro-hardness test and a corrosion experiment to simulate the effect of sea water were performed. The result indicated that the highest micro-hardness of the surface reaches three times that of the matrix. The corrosion rate of alloying samples declines to about a fifth of that of the as-cast AZ91D specimen.

  2. The Influence of Novel Alloying Additions on the Performance of Magnesium Alloy AZ31B

    Science.gov (United States)

    2013-11-01

    properties were determined using dog- bone specimens with a 4-mm diameter and 16-mm gage length cut from the longitudinal section of the extruded bars...content of the major alloying elements (Al, Zn, [ manganese ] Mn) of the alloys was in reasonably good agreement with the standard composition. The

  3. Hot workability of magnesium alloys

    Science.gov (United States)

    Mwembela, Aaron Absalom

    For the alloy AZ91 (Mg-9.OAl-0.7Zn-0.13Mn) die cast specimens were subjected to torsion testing at 150, 180, 240, 300, 420 and 450°C at 0.05 0.5 and 5.0 s--1 The as-cast specimens exhibited hot shortness at 360°C and above; however in that domain, after prior thermomechanical processing (TMP) at 300°C, they showed much improved properties (which were reported along with as-cast properties at 300°C and below). For AZ31-Mn (Mg-3.2Al-1-1Zn-0.34Mn), AZ31 (Mg-2-8Al-0-88Zn-0.01Mn), AZ63 (Mg-5-5Al-2.7Zn-0.34Mn) and ZK60 (Mg-5.7Zn-0.65Zr-O-O1A]), the specimens were subjected to hot torsion testing in the range 180 to 450°C and 0.01, 0.1, and 1.0 s--1. In the temperature range below 300°C flow curves rise to a peak with failure occurring immediately thereafter. Above 300°C the flow curves exhibited a peak and a gradual decline towards steady state. The temperature and strain rate dependence of the strength is described by a sinh-Arrhenius equation with QHW between 125 and 144 kJ/mol; this indicates control by climb in comparison with creep in the range 200--400°C. The alloy strength and activation energy declined in the order AZ63, AZ31-Mn AZ91, AZ31 and ZK60, while ductility increased with decreasing strength. In working of Mg alloys from 150 to 450°C, the flow curves harden to a peak and work soften to a steady state regime above 300°C. At temperatures below 300°C, twinning is observed initially to bring grains into more suitable slip orientations. At high T a substructure develops due to basal and prismatic slip, Forming cells of augmented misorientation first near the grain boundaries and later towards the grain cores. Near the peak, new grains appear along the old boundaries (mantle) as a result of dynamic recrystallization DRX but not in the core of the initial grains. As T rises, the new grains are larger and the mantle broader, enhanced DRX results in higher ductility. At intermediate T, shear bands form through alignment of mantle zones resulting in

  4. Analysis of heavy alloying elements segregation in gravity cast experimental Mg-Al-Zn-RE alloy

    Directory of Open Access Journals (Sweden)

    A. Żydek

    2010-01-01

    Full Text Available Microstructure of experimental AZ91 alloy with an addition of rare earth elements (RE at a level of 4 wt.% was examined by means of light microscopy. The investigated AZ91 + 4 wt.% RE alloy was fabricated by adding cerium rich mish metal to molten commercial AZ91 alloy. In the microstructure of the resulting alloy, besides α solid solution, α + γ eutectic and discontinuous precipitates of γ phase, also the Al11RE3 phase with needle-like morphology and the polygonal Al10RE2Mn7 phase were revealed. No segregation of rare earth elements was found in the investigated gravity cast alloy, which was confirmed by statistical analysis of cerium concentrations in selected parts of the cast. Similar results were obtained for manganese. Ce and Mn concentrations were determined by a spectrophotometric method.

  5. On improving the fracture toughness of a NiAl-based alloy by mechanical alloying

    Science.gov (United States)

    Kostrubanic, J.; Koss, D. A.; Locci, I. E.; Nathal, M.

    1991-01-01

    Mechanical alloying (MA) has been used to process the NiAl-based alloy Ni-35Al-20Fe, such that a fine-grain (about 2 microns) microstructure is obtained through the addition of 2 vol pct Y2O3 particles. When compared to a conventionally processed, coarse-grained (about 28 microns) Ni-35-20 alloy without the Y2O3 particles, the MA alloy exhibits two to three times higher fracture toughness values, despite a 50-percent increase in yield strength. Room-temperature K(O) values as high as 34 MPa sq rt m are observed, accompanied by a yield strength in excess of 1100 MPa. Fractography confirms a change in fracture characteristics of the fine-grained MA alloy.

  6. Method for producing La/Ce/MM/Y base alloys, resulting alloys and battery electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Gschneidner, Jr., Karl A.; Schmidt, Frederick A.

    2016-12-20

    A carbothermic reduction method is provided for reducing a La-, Ce-, MM-, and/or Y-containing oxide in the presence of carbon and a source of a reactant element comprising Si, Ge, Sn, Pb, As, Sb, Bi, and/or P to form an intermediate alloy material including a majority of La, Ce, MM, and/or Y and a minor amount of the reactant element. The intermediate material is useful as a master alloy for in making negative electrode materials for a metal hydride battery, as hydrogen storage alloys, as master alloy additive for addition to a melt of commercial Mg and Al alloys, steels, cast irons, and superalloys; or in reducing Sm.sub.2O.sub.3 to Sm metal for use in Sm--Co permanent magnets.

  7. Corrosion resistant Ti alloy for sulphuric acid medium: Suitability of Ti-Mo alloys

    Energy Technology Data Exchange (ETDEWEB)

    Balusamy, T.; Jamesh, M.; Kumar, Satendra; Narayanan, T.S.N. Sankara [National Metallurgical Laboratory, Madras Centre, CSIR Complex, Taramani, Chennai 600 113 (India)

    2012-09-15

    The corrosion resistance of Ti-Mo (5, 10, 15 and 25 wt% molybdenum) alloys in 5-25% sulphuric acid was evaluated. The Ti-Mo alloys offered a better corrosion resistance than commercially pure titanium (CP-Ti). The higher impedance values, higher phase angle maximum, ability to reach the phase angle maximum at relatively lower frequencies, ability to exhibit a constant phase angle maximum over a wider range of frequencies, higher phase angle values at 0.01 Hz, have confirmed the formation of a stable passive oxide film on Ti-Mo alloys. The study recommends the use of Ti-Mo alloys, particularly Ti-25Mo alloy, as a suitable material of construction for sulphuric acid medium. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Alloy development for irradiation performance. Quarterly progress report for period ending December 31, 1980

    Energy Technology Data Exchange (ETDEWEB)

    1981-04-01

    Progress is reported in eight sections: analysis and evaluation studies, test matrices and test methods development, Path A Alloy Development (austenitic stainless steels), Path C Alloy Development (Ti and V alloys), Path D Alloy Development (Fe alloys), Path E Alloy Development (ferritic steels), irradiation experiments and materials inventory, and materials compatibility and hydrogen permeation studies. (DLC)

  9. Alloy development for irradiation performance. Quarterly progress report for period ending December 31, 1980

    International Nuclear Information System (INIS)

    1981-04-01

    Progress is reported in eight sections: analysis and evaluation studies, test matrices and test methods development, Path A Alloy Development (austenitic stainless steels), Path C Alloy Development (Ti and V alloys), Path D Alloy Development (Fe alloys), Path E Alloy Development (ferritic steels), irradiation experiments and materials inventory, and materials compatibility and hydrogen permeation studies

  10. Dispersion strengthening of precipitation hardened Al-Cu-Mg alloys prepared by rapid solidification and mechanical alloying

    Science.gov (United States)

    Gilman, P. S.; Sankaran, K. K.

    1988-01-01

    Several Al-4Cu-1Mg-1.5Fe-0.75Ce alloys have been processed from either rapidly solidified or mechanically alloyed powder using various vacuum degassing parameters and consolidation techniques. Strengthening by the fine subgrains, grains, and the dispersoids individually or in combination is more effective when the alloys contain shearable precipitates; consequently, the strength of the alloys is higher in the naturally aged rather than the artificially aged condition. The strengths of the mechanically alloyed variants are greater than those produced from prealloyed powder. Properties and microstructural features of these dispersion strengthened alloys are discussed in regards to their processing histories.

  11. Influence of alloying elements and density on aqueous corrosion behaviour of some sintered low alloy steels

    International Nuclear Information System (INIS)

    Kandavel, T.K.; Chandramouli, R.; Karthikeyan, P.

    2012-01-01

    Highlights: ► Corrosion of low alloy P/M steels under HCl acid pickling environment has been studied. ► Influence of density, strain and alloying elements on the rate of corrosion of the steels has been investigated. ► Residual porosity has significant effect on acid corrosion. ► Addition of the alloying elements Cu, Mo and Ti reduces the corrosion rate significantly. ► Carbide forming elements Mo and Ti improve further the resistance of the steels to aqueous corrosion. -- Abstract: Low alloy steels produced through powder metallurgy route of sintering followed by forging are promising candidate materials for high strength small components. Porosity in such steels poses a real challenge during acid pickling treatment, which is one of the processing steps during manufacturing. The present research work attempts to investigate the mechanism underlying the acid corrosion behaviour of some sintered low alloy steels under induced acid pickling conditions. Sintered-forged low alloy steel samples containing molybdenum (Mo), copper (Cu) and titanium (Ti) were subjected to aqueous corrosion attack by immersing the samples in 18% HCl (Hydrochloric acid) solution for 25 h. Sample weight loss and Fe (Iron) loss were estimated for the corroded samples. The morphology of the corroded surfaces was studied through metallography and scanning electron microscopy. Higher porosity alloys underwent enhanced corrosion rates. Both corrosion rate and iron loss are found to decrease linearly with reduction in porosity in all cases of the alloys. The alloying elements Mo, Ti and Cu, when added in combination, have played a complementary role in the reduction of corrosion rate by almost one order of magnitude compared to unalloyed steel. Presence of carbides of the carbide forming elements Mo and Ti played a positive role on the corrosion behaviour of the low alloy steels.

  12. The influence of alloy composition on residual stresses in heat treated aluminium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, J.S., E-mail: jeremy.robinson@ul.ie [Department of Mechanical, Aeronautical and Biomedical Engineering, University of Limerick (Ireland); Redington, W. [Materials and Surface Science Institute, University of Limerick (Ireland)

    2015-07-15

    The as quenched properties of eight different heat treatable aluminium alloys are related to residual stress magnitudes with the objective being to establish if there is a relationship between the residual stress and the as quenched alloy hardness and strength. Near surface residual stresses were assessed with X-ray diffraction using both the established sin{sup 2}ψ method and the more recent cos α technique. Through thickness residual stresses were also characterised using neutron diffraction. The alloys were chosen to encompass a wide range of strengths. The low to medium strength alloys were 6060 and 6082, medium to high strength 2618A, 2014A, 7075, 7010 and two variants of 7449, while the very high strength alloy was the powder metallurgy alloy N707. To assess the as quenched strength, dynamic hardness and tensile properties were determined from samples tested immediately after quenching to minimise the influence of precipitation hardening by natural aging. In addition, hot hardness measurements were made in situ on samples cooled to simulate quench paths. Within the experimental constraints of the investigation, the distribution of residual stress through the thickness was found to follow the same pattern for all the alloys investigated, varying from tensile in the interior to surface compression. The influence of alloy strength was manifested as a change in the observed residual stress magnitudes, and surface residual stresses were found to vary linearly with as quenched hardness and strength. - Highlights: • As quenched aluminium alloys contain high magnitude residual stresses. • Surface is compressive balance by a tensile core. • As quenched surface residual stress is linear function of alloy strength. • In situ hot hardness demonstrates rapid change in intrinsic hardness during rapid cooling.

  13. In vitro mechanical integrity of hydroxyapatite coated magnesium alloy.

    Science.gov (United States)

    Kannan, M Bobby; Orr, Lynnley

    2011-08-01

    The mechanical integrity of resorbable implants during service, especially in load bearing orthopaedic applications, is critical. The high degradation rate of resorbable magnesium and magnesium-based implants in body fluid may potentially cause premature in-service failure. In this study, a magnesium alloy (AZ91) was potentiostatically coated with hydroxyapatite at different cathodic voltages in an attempt to enhance the mechanical integrity. The mechanical integrity of the uncoated and hydroxyapatite coated alloys was evaluated after in vitro testing of the coated samples in simulated body fluid (SBF). The uncoated alloy showed 40% loss in the mechanical strength after five days exposure to SBF. However, the hydroxyapatite coated alloy exposed to SBF showed 20% improvement in the mechanical strength as compared to that of the uncoated alloy. The alloy coated potentiostatically at -2 V performed better than the -3 V coated alloy. The cross-sectional analysis of the coatings revealed relatively uniform coating thickness for the -2 V coated alloy, whereas the -3 V coated alloy exhibited areas of uneven coating. This can be attributed to the increase in hydrogen evolution on the alloy during -3 V coating as compared to -2 V coating. The scanning electron micrographs of the in vitro tested alloy revealed that hydroxyapatite coating significantly reduced the localized corrosion of the alloy, which is critical for better in-service mechanical integrity. Thus, the study suggests that the in vitro mechanical integrity of resorbable magnesium-based alloy can be improved by potentiostatic hydroxyapatite coating. © 2011 IOP Publishing Ltd

  14. Machinability evaluation of titanium alloys.

    Science.gov (United States)

    Kikuchi, Masafumi; Okuno, Osamu

    2004-03-01

    In the present study, the machinability of titanium, Ti-6Al-4V, Ti-6A1-7Nb, and free-cutting brass was evaluated using a milling machine. The metals were slotted with square end mills under four cutting conditions. The cutting force and the rotational speed of the spindle were measured. The cutting forces for Ti-6Al-4V and Ti-6Al-7Nb were higher and that for brass was lower than that for titanium. The rotational speed of the spindle was barely affected by cutting. The cross sections of the Ti-6Al-4V and Ti-6Al-7Nb chips were more clearly serrated than those of titanium, which is an indication of difficult-to-cut metals. There was no marked difference in the surface roughness of the cut surfaces among the metals. Cutting force and the appearance of the metal chips were found to be useful as indices of machinability and will aid in the development of new alloys for dental CAD/CAM and the selection of suitable machining conditions.

  15. Surface treatments for aluminium alloys

    Science.gov (United States)

    Ardelean, M.; Lascău, S.; Ardelean, E.; Josan, A.

    2018-01-01

    Typically, in contact with the atmosphere, the aluminium surface is covered with an aluminium oxide layer, with a thickness of less than 1-2μm. Due to its low thickness, high porosity and low mechanical strength, this layer does not protect the metal from corrosion. Anodizing for protective and decorative purposes is the most common method of superficial oxidation processes and is carried out through anodic oxidation. The oxide films, resulted from anodizing, are porous, have a thickness of 20-50μm, and are heat-resistant, stable to water vapour and other corrosion agents. Hard anodizing complies with the same obtains principles as well as decorative and protective anodization. The difference is in that hard anodizing is achieved at low temperatures and high intensity of electric current. In the paper are presented the results of decorative and hard anodization for specimens made from several aluminium alloys in terms of the appearance of the specimens and of the thickness of the anodized.

  16. Development the Mechanical Properties of (AL-Li-Cu Alloy

    Directory of Open Access Journals (Sweden)

    Ihsan Kadhom AlNaimi

    2017-11-01

    Full Text Available The aim of this research is to develop mechanical properties of a new aluminium-lithium-copper alloy. This alloy prepared under control atmosphere by casting in a permanent metal mould. The microstructure was examined and mechanical properties were tested before and after heat treatment to study the influence of heat treatment on its mechanical properties including; modulus of elasticity, tensile strength, impact, and fatigue. The results showed that the modulus of elasticity of the prepared alloy is higher than standard alloy about 2%. While the alloy that heat treated for 6 h and cooled in water, then showed a higher ultimate tensile stress comparing with as-cast alloy. The homogenous heat treatment gives best fatigue behaviour comparing with as-cast and other heat treatment alloys. Also, the impact test illustrates that the homogeneous heat treatment alloy gives the highest value.

  17. Impact and modal analysis for different alloy wheel compositions

    Science.gov (United States)

    Suman, Shwetabh; Abhimanyu Abrol, J.; Ravi, K.

    2017-11-01

    Wheels are an important component in the vehicle. The strength of the Alloy wheel rim is an important property of the Alloy wheel, which plays an important part in determining the overall performance of the vehicle, the structural integrity of the rim and the life of the Alloy wheel rim. With the advent of new Alloy wheel materials, new options are available to replace the conventional Aluminium Alloy wheels with new ones. The new Alloy wheel rim material and design need to be tested virtually for optimizing the appropriate design and material and the optimised wheel in virtual mode can be tested experimentally for the performance in real-time conditions before they can be used in the vehicles. The work in this project includes doing the impact and modal analysis for different alloy wheel compositions. From the results obtained, the optimum alloy wheel is suggested, which can be considered with further experimental validation.

  18. The Origin of the Name "Onion's Fusible Alloy"

    Science.gov (United States)

    Jensen, William B.

    2010-01-01

    In response to a reader query, this article traces the history of fusible alloys, including Newton's metal, D'Arcet's metal, Rose's metal, Onion's fusible alloy, and Wood's metal. (Contains 1 table and 1 figure.)

  19. PDTI metal alloy as a hydrogen or hydrocarbon sensitive metal

    Science.gov (United States)

    Hunter, Gary W. (Inventor)

    1996-01-01

    A hydrogen sensitive metal alloy contains palladium and titanium to provide a larger change in electrical resistance when exposed to the presence of hydrogen. The alloy can be used for improved hydrogen detection.

  20. Metallurgical characterization of experimental Ag-based soldering alloys

    Directory of Open Access Journals (Sweden)

    Argyro Ntasi

    2014-10-01

    Conclusion: The experimental alloys tested demonstrated similar microstructures and melting ranges. Ga and Sn might be used as alternative to Cu and Zn to modify the selected properties of Ag based soldering alloys.

  1. Enhanced Performance Near Net Shape Titanium Alloys by Thermohydrogen Processing

    National Research Council Canada - National Science Library

    Froes, F

    2001-01-01

    ...), powder metallurgy and cast titanium alloys. Fundamental results have been obtained which can now be used to develop optimum THP steps to refine the microstructure and improve the mechanical properties of titanium alloys...

  2. Bismuth alloy potting seals aluminum connector in cryogenic application

    Science.gov (United States)

    Flower, J. F.; Stafford, R. L.

    1966-01-01

    Bismuth alloy potting seals feedthrough electrical connector for instrumentation within a pressurized vessel filled with cryogenic liquids. The seal combines the transformation of high-bismuth content alloys with the thermal contraction of an external aluminum tube.

  3. STRUCTURE FORMATION OF ALLOYS ON IRON BASIS AFTER LASER ALLOYING

    Directory of Open Access Journals (Sweden)

    О. V. Diachenko

    2016-01-01

    Full Text Available The paper is devoted to investigations on influence of laser treatment regimes of gas-thermal and adhesive coatings from self-fluxing powders on iron basis and after melting with modifying plaster on their roughness and phase composition. One of mathematical planning methods that is a complete factor experiment method has been used for investigation of parameters’ influence on micro-geometry of coatings. The executed investigations have made it possible to observe a general regularity which does not depend on a type of alloying plaster: while increasing speed of laser beam relatively to treated part, beam diameter value of Ra parameter is becoming less. Decrease in height of surface irregularities in case of increasing laser beam speed is related with intensification of evaporation processes. An increase in beam diameter diminishes Ra parameter of the surface. This is due to the fact that decrease in power density occurs at high rate of beam defocusing. Overlapping coefficient does not exert a pronounced effect on Ra parameter of fused coatings. While increasing the speed of laser beam relatively to the part structure is transferred from dendrite into supersaturated one with carbide and boride precipitations. It has been established that technological parameters of laser treatment and particularly speed of laser beam influence on coating composition. While increasing the speed up to v5 = 5 × 10–3 m/s amount of chromium has become larger by 1.5-fold that resulted in increase of micro-hardness of the coating from 9.5–10.1 GPa up to 11.04–15.50 GPa.

  4. Ion-induced surface modification of alloys

    International Nuclear Information System (INIS)

    Wiedersich, H.

    1983-11-01

    In addition to the accumulation of the implanted species, a considerable number of processes can affect the composition of an alloy in the surface region during ion bombardment. Collisions of energetic ions with atoms of the alloy induce local rearrangement of atoms by displacements, replacement sequences and by spontaneous migration and recombination of defects within cascades. Point defects form clusters, voids, dislocation loops and networks. Preferential sputtering of elements changes the composition of the surface. At temperatures sufficient for thermal migration of point defects, radiation-enhanced diffusion promotes alloy component redistribution within and beyond the damage layer. Fluxes of interstitials and vacancies toward the surface and into the interior of the target induce fluxes of alloying elements leading to depth-dependent compositional changes. Moreover, Gibbsian surface segregation may affect the preferential loss of alloy components by sputtering when the kinetics of equilibration of the surface composition becomes competitive with the sputtering rate. Temperature, time, current density and ion energy can be used to influence the individual processes contributing to compositional changes and, thus, produce a rich variety of composition profiles near surfaces. 42 references

  5. The manufacture of superplastic magnesium alloy sheet

    Energy Technology Data Exchange (ETDEWEB)

    Grimes, R.; Jackson, M.; Moorhouse, B.; Dashwood, R. [Department of Materials, Imperial College London (United Kingdom)

    2008-04-15

    Probably because of their propensity to dynamically recrystallise, superplastic behaviour can be obtained from magnesium alloys considerably more easily than from comparable aluminium alloys. In some cases even as cast magnesium alloys can exhibit reasonable superplasticity and there appears no need for the special alloying additions or complex thermal mechanical treatments required by aluminium alloys such as AA2004 or AA7475. The paper describes the superplastic behaviour (in uniaxial tension) and microstructure of sheet processed from strip cast AZ31 and AZ91. The material was tested in the as-cast condition and after warm rolling to a number of gauges. Industrially useful superplastic capability was demonstrated in strip cast AZ31 and AZ91 in the as cast condition. Furthermore good superplastic capability was also demonstrated in sheet rolled from the cast metal and the ductilities obtained were not significantly influenced by rolling strain. Twin roll strip casting represents a feasible and simple route for the production of superplastic material either for use in the as cast condition or after rolling to the required gauge. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  6. Phase stability of transition metals and alloys

    International Nuclear Information System (INIS)

    Hixson, R.S.; Schiferl, D.; Wills, J.M.; Hill, M.A.

    1997-01-01

    This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). This project was focused on resolving unexplained differences in calculated and measured phase transition pressures in transition metals. Part of the approach was to do new, higher accuracy calculations of transmission pressures for group 4B and group 6B metals. Theory indicates that the transition pressures for these baseline metals should change if alloyed with a d-electron donor metal, and calculations done using the Local Density Approximation (LDA) and the Virtual Crystal Approximation (VCA) indicate that this is true. Alloy systems were calculated for Ti, Zr and Hf based alloys with various solute concentrations. The second part of the program was to do new Diamond Anvil Cell (DAC) measurements to experimentally verify calculational results. Alloys were prepared for these systems with grain size suitable for Diamond Anvil Cell experiments. Experiments were done on pure Ti as well as Ti-V and Ti-Ta alloys. Measuring unambiguous transition pressures for these systems proved difficult, but a new technique developed yielded good results

  7. Corrosion resistance of tantalum base alloys

    International Nuclear Information System (INIS)

    Gypen, L.A.; Brabers, M.; Deruyttre, A.

    1984-01-01

    The corrosion behaviour of substitutional Ta-Mo, Ta-W, Ta-Nb, Ta-Hf, Ta-Zr, Ta-Re, Ta-Ni, Ta-V, Ta-W-Mo, Ta-W-Nb, Ta-W-Hf and Ta-W-Re alloys has been investigated in various corrosive media, i.e. (1) concentrated sulfuric acid at 250 0 C and 200 0 C, (2) boiling hydrochloric acid of azeotropic composition, (3) concentrated hydrochloric acid at 150 0 C under pressure, (4) HF-Containing solutions and (5) 0.5% H 2 SO 4 at room temperature (anodisation). In highly corrosive media such as concentrated H 2 SO 4 at 250 0 C and concentrated HCl at 150 0 C tantalum is hydrogen embrittled, probably by stress induced precipitation of β-hydride. Both corrosion rate and hydrogen embrittlement in concentrated H 2 SO 4 at 250 0 C are strongly influenced by alloying elements. Small alloying additions of either Mo or Re decrease the corrosion rate and the hydrogen embrittlement, while Hf has the opposite effect. Hydrogen embrittlement in concentrated H 2 SO 4 at 250 0 C is completely eliminated by alloying Ta with 1 to 3 at % Mo (0.5 to 1.5 wt % Mo). These results can be explained in terms of oxygen deficiency of the Ta 2 O 5 film and the electronic structure of these alloys. (orig.) [de

  8. Precision forging technology for aluminum alloy

    Science.gov (United States)

    Deng, Lei; Wang, Xinyun; Jin, Junsong; Xia, Juchen

    2018-03-01

    Aluminum alloy is a preferred metal material for lightweight part manufacturing in aerospace, automobile, and weapon industries due to its good physical properties, such as low density, high specific strength, and good corrosion resistance. However, during forging processes, underfilling, folding, broken streamline, crack, coarse grain, and other macro- or microdefects are easily generated because of the deformation characteristics of aluminum alloys, including narrow forgeable temperature region, fast heat dissipation to dies, strong adhesion, high strain rate sensitivity, and large flow resistance. Thus, it is seriously restricted for the forged part to obtain precision shape and enhanced property. In this paper, progresses in precision forging technologies of aluminum alloy parts were reviewed. Several advanced precision forging technologies have been developed, including closed die forging, isothermal die forging, local loading forging, metal flow forging with relief cavity, auxiliary force or vibration loading, casting-forging hybrid forming, and stamping-forging hybrid forming. High-precision aluminum alloy parts can be realized by controlling the forging processes and parameters or combining precision forging technologies with other forming technologies. The development of these technologies is beneficial to promote the application of aluminum alloys in manufacturing of lightweight parts.

  9. A jumping shape memory alloy under heat.

    Science.gov (United States)

    Yang, Shuiyuan; Omori, Toshihiro; Wang, Cuiping; Liu, Yong; Nagasako, Makoto; Ruan, Jingjing; Kainuma, Ryosuke; Ishida, Kiyohito; Liu, Xingjun

    2016-02-16

    Shape memory alloys are typical temperature-sensitive metallic functional materials due to superelasticity and shape recovery characteristics. The conventional shape memory effect involves the formation and deformation of thermally induced martensite and its reverse transformation. The shape recovery process usually takes place over a temperature range, showing relatively low temperature-sensitivity. Here we report novel Cu-Al-Fe-Mn shape memory alloys. Their stress-strain and shape recovery behaviors are clearly different from the conventional shape memory alloys. In this study, although the Cu-12.2Al-4.3Fe-6.6Mn and Cu-12.9Al-3.8Fe-5.6Mn alloys possess predominantly L2(1) parent before deformation, the 2H martensite stress-induced from L2(1) parent could be retained after unloading. Furthermore, their shape recovery response is extremely temperature-sensitive, in which a giant residual strain of about 9% recovers instantly and completely during heating. At the same time, the phenomenon of the jumping of the sample occurs. It is originated from the instantaneous completion of the reverse transformation of the stabilized 2H martensite. This novel Cu-Al-Fe-Mn shape memory alloys have great potentials as new temperature-sensitive functional materials.

  10. 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.

  11. Materials developed by mechanical alloying and melt spinning

    OpenAIRE

    Suñol Martínez, Joan Josep; Fort, Joaquim

    2008-01-01

    Materials science is a multidisciplinary research topic related to the development of physics and technology. Mechanical alloying of ribbon flakes is a two steps route to develop advanced materials. In this work, a Fe based alloy was obtained using three pathways: mechanical alloying, melt-spinning and mechanical alloying of previously melt-spun samples. Processing conditions allow us to obtain amorphous or nanocrystalline structures. Furthermore, a bibliographic revision of mechanical al...

  12. 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.

  13. Properties and applications of ion-implanted alloys

    International Nuclear Information System (INIS)

    Myers, S.M.

    1979-01-01

    Ion implantation is a controlled and versatile means for near-surface alloying of metals. Supersaturated solutions, metastable compounds, amorphous phases, and equilibrium alloys have been produced. Uses include the investigation of new metastable phases, characterization of alloying reactions occurring in conventional materials, and improvement of surface properties such as hardness, wear, and corrosion. A brief review is given of the physical processes occurring during ion implantation, the types of alloys which result, and representative applications

  14. Microstructure and Aging of Powder-Metallurgy Al Alloys

    Science.gov (United States)

    Blackburn, L. B.

    1987-01-01

    Report describes experimental study of thermal responses and aging behaviors of three new aluminum alloys. Alloys produced from rapidly solidified powders and contain 3.20 to 5.15 percent copper, 0.24 to 1.73 percent magnesium, 0.08 to 0.92 percent iron, and smaller amounts of manganese, nickel, titanium, silicon, and zinc. Peak hardness achieved at lower aging temperatures than with standard ingot-metallurgy alloys. Alloys of interest for automobile, aircraft, and aerospace applications.

  15. Microstructures and properties of aluminum die casting alloys

    Energy Technology Data Exchange (ETDEWEB)

    M. M. Makhlouf; D. Apelian; L. Wang

    1998-10-01

    This document provides descriptions of the microstructure of different aluminum die casting alloys and to relate the various microstructures to the alloy chemistry. It relates the microstructures of the alloys to their main engineering properties such as ultimate tensile strength, yield strength, elongation, fatigue life, impact resistance, wear resistance, hardness, thermal conductivity and electrical conductivity. Finally, it serves as a reference source for aluminum die casting alloys.

  16. Relaxation resistance of heat resisting alloys with cobalt

    International Nuclear Information System (INIS)

    Borzdyka, A.M.

    1977-01-01

    Relaxation resistance of refractory nickel-chromium alloys containing 5 to 14 % cobalt is under study. The tests involve the use of circular samples at 800 deg to 850 deg C. It is shown that an alloy containing 14% cobalt possesses the best relaxation resistance exceeding that of nickel-chromium alloys without any cobalt by a factor of 1.5 to 2. The relaxation resistance of an alloy with 5% cobalt can be increased by hardening at repeated loading

  17. The physical metallurgy of mechanically-alloyed, dispersion-strengthened Al-Li-Mg and Al-Li-Cu alloys

    Science.gov (United States)

    Gilman, P. S.

    1984-01-01

    Powder processing of Al-Li-Mg and Al-Li-Cu alloys by mechanical alloying (MA) is described, with a discussion of physical and mechanical properties of early experimental alloys of these compositions. The experimental samples were mechanically alloyed in a Szegvari attritor, extruded at 343 and 427 C, and some were solution-treated at 520 and 566 C and naturally, as well as artificially, aged at 170, 190, and 210 C for times of up to 1000 hours. All alloys exhibited maximum hardness after being aged at 170 C; lower hardness corresponds to the solution treatment at 566 C than to that at 520 C. A comparison with ingot metallurgy alloys of the same composition shows the MA material to be stronger and more ductile. It is also noted that properly aged MA alloys can develop a better combination of yield strength and notched toughness at lower alloying levels.

  18. Mechanical alloying and sitering of TI - 10WT.% MG powders

    CSIR Research Space (South Africa)

    Machio, Christopher N

    2009-06-01

    Full Text Available A Ti-10wt.%Mg powder alloy has been produced by mechanical alloying. Elemental powders of Ti and Mg were ball milled in a Zoz-Simoloyer CM01 for 16 and 20 hours under argon. Mechanical alloying was followed by XRD, SEM and particle size analysis...

  19. Advanced alloy design technique: High temperature cobalt base superalloy

    Science.gov (United States)

    Dreshfield, R. L.; Freche, J. C.; Sandrock, G. D.

    1972-01-01

    Advanced alloy design technique was developed for treating alloys that will have extended life in service at high temperature and intermediate temperatures. Process stabilizes microstructure of the alloy by designing it so that compound identified with embrittlement is eliminated or minimized. Design process is being used to develop both nickel and cobalt-base superalloys.

  20. Fatigue Analysis of Magnesium Alloys Components for Car Industry

    Science.gov (United States)

    Marsavina, Liviu; Rusu, Lucian; Șerban, Dan Andrei; Negru, Radu Marcel; Cernescu, Anghel

    2017-12-01

    The use of magnesium alloys in the automotive industry increased in the last decade because of their low weight and relative good mechanical properties. However, the variable loading conditions require a good fatigue behavior. This paper summaries the fatigue properties of magnesium alloys and presents new fatigue curve results for die cast AM50 magnesium alloy.

  1. 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 ...

  2. 21 CFR 872.3710 - Base metal alloy.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Base metal alloy. 872.3710 Section 872.3710 Food... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3710 Base metal alloy. (a) Identification. A base metal alloy is a device composed primarily of base metals, such as nickel, chromium, or cobalt, that is...

  3. Sulfuric Acid Corrosion of Low Sb - Pb Battery Alloys | Ntukogu ...

    African Journals Online (AJOL)

    The corrosion properties of low Sb - Pb alloys developed for maintenance free motive power industrial batteries was studied by a bare grid constant current method and compared to those of the conventional Pb- 6% Sb alloy. Low Sb-Pb alloys with Se and As grain refiners were found to have higher corrosion rates than the ...

  4. SULFURIC ACID CORROSION OF LOW Sb - Pb BATTERY ALLOYS

    African Journals Online (AJOL)

    user

    1983-09-01

    Sep 1, 1983 ... (Manuscript received February,1983). ABSTRACT. The corrosion properties of low Sb - Pb alloys developed for maintenance free motive power industrial batteries was studied by a bare grid constant current method and compared to those of the conventional. Pb- 6% Sb alloy. Low Sb-Pb alloys with Se and ...

  5. Corrosion wear fracture of new {beta} biomedical titanium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Niinomi, M.; Fukunaga, K.-I. [Toyohashi Univ. of Technol. (Japan). Dept. of Production Syst. Eng.; Kuroda, D.; Morinaga, M.; Kato, Y.; Yashiro, T.; Suzuki, A.

    1999-05-15

    Metallic materials such as stainless steel, Co-Cr alloy, pure titanium and titanium alloys have been used for surgical implant materials. The {alpha} + {beta} type titanium alloy such as Ti-6Al-4V ELI has been most widely used as an implant material for artificial hip joint and dental implant because of its high strength and excellent corrosion resistance. Toxicity of alloying elements in conventional biomedical titanium alloys like Al and V, and the high modulus of elasticity of these alloy as compared to that of bone have been, however, pointed out [1,2]. New {beta} type titanium alloys composed of non-toxic elements like Nb, Ta, Zr, Mo and Sn with lower moduli of elasticity, greater strength and greater corrosion resistance were, therefore, designed in this study. The friction wear properties of titanium alloys are, however, low as compared to those of other conventional metallic implant materials such as stainless steels and Co-Cr alloy. Tensile tests and friction wear tests in Ringer`s solution were conducted in order to investigate the mechanical properties of designed alloys. The friction wear characteristics of designed alloys and typical conventional biomedical titanium alloys were evaluated using a pin-on-disk type friction wear testing system and measuring the weight loss and width of groove of the specimen. (orig.) 8 refs.

  6. 21 CFR 872.3060 - Noble metal alloy.

    Science.gov (United States)

    2010-04-01

    ... DEVICES DENTAL DEVICES Prosthetic Devices § 872.3060 Noble metal alloy. (a) Identification. A noble metal alloy is a device composed primarily of noble metals, such as gold, palladium, platinum, or silver, that... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Noble metal alloy. 872.3060 Section 872.3060 Food...

  7. Nitriding of super alloys for enhancing physical properties

    Science.gov (United States)

    Purohit, A.

    1984-06-25

    The invention teaches the improvement of certain super alloys by exposing the alloy to an atmosphere of elemental nitrogen at elevated temperatures in excess of 750/sup 0/C but less than 1150/sup 0/C for an extended duration, viz., by nitriding the surface of the alloy, to establish barrier nitrides of the order of 25 to 100 micrometers thickness. These barrier

  8. ZINTL IONS AS STRUCTURAL UNITS IN LIQUID ALLOYS

    NARCIS (Netherlands)

    VANDERLUGT, W

    1991-01-01

    Anion clustering according to a rule discovered by E. Zintl may occur in ionic alloys. The chemical bonds between the anions are predominantly covalent. The drastic consequences of this effect for the electronic and structural properties of liquid ionic alloys are demonstrated for alloys of alkali

  9. Friction factor of CP aluminium and aluminium–zinc alloys

    Indian Academy of Sciences (India)

    zinc alloys using ring compression test at different temperatures from 303 K to 773 K. It is found that CP aluminium exhibits stick- ing whereas Al–Zn alloys do not exhibit sticking at elevated temperatures. Hot working of Al–Zn alloy is easier.

  10. Development and application of titanium alloy casting technology in China

    Directory of Open Access Journals (Sweden)

    HAN Hai

    2005-11-01

    Full Text Available The development and research of casting titanium alloy and its casting technology, especially its application in aeronautical industry in China are presented. The technology of moulding, melting and casting of titanium alloy, casting quality control are introduced. The existing problem and development trend in titanium alloy casting technology are also discussed.

  11. 21 CFR 872.3080 - Mercury and alloy dispenser.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Mercury and alloy dispenser. 872.3080 Section 872...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3080 Mercury and alloy dispenser. (a) Identification. A mercury and alloy dispenser is a device with a spring-activated valve intended to measure and...

  12. Nanostructured Platinum Alloys for Use as Catalyst Materials

    Science.gov (United States)

    Hays, Charles C. (Inventor); Narayan, Sri R. (Inventor)

    2015-01-01

    A series of binary and ternary Pt-alloys, that promote the important reactions for catalysis at an alloy surface; oxygen reduction, hydrogen oxidation, and hydrogen and oxygen evolution. The first two of these reactions are essential when applying the alloy for use in a PEMFC.

  13. Structure of nanocomposites of Al–Fe alloys prepared by ...

    Indian Academy of Sciences (India)

    Wintec

    This difference in the product structure can be attributed to the difference in alloying mechanisms in MA and RSP. Keywords. Nanocomposites; Al–Fe; mechanical alloying; rapid solidification; quasicrystalline. 1. Introduction. Al–Fe alloys are attractive for applications at temperatures beyond those normally associated with ...

  14. Thin-film cryogenic resistors from aluminium alloys

    Science.gov (United States)

    Tadros, N. N.; Holdeman, L. B.

    The temperature dependence of the resistances of thin films sputtered from three commercially available aluminium alloys (5052, 5086, 5456) has been measured in the temperature range 1.5-4.2 K. The 5052-alloy films had a positive temperature coefficient of resistance (TCR) throughout this temperature range, whereas films of the other two alloys had a negative TCR.

  15. 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 ...

  16. Electronic-Structure-Based Design of Ordered Alloys

    DEFF Research Database (Denmark)

    Bligaard, Thomas; Andersson, M.P.; Jacobsen, Karsten Wedel

    2006-01-01

    We describe some recent advances in the methodology of using electronic structure calculations for materials design. The methods have been developed for the design of ordered metallic alloys and metal alloy catalysts, but the considerations we present are relevant for the atomic-scale computational...... discovery of a promising catalytic metal alloy surface with high reactivity and low cost....

  17. 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)

  18. Mechanical evaluation of cerebral aneurysm clip scissoring phenomenon: comparison of titanium alloy and cobalt alloy.

    Science.gov (United States)

    Tsutsumi, Keiji; Horiuchi, Tetsuyoshi; Hongo, Kazuhiro

    2017-09-13

    Cerebral aneurysm clip blades crossing during surgery is well known as scissoring. Scissoring might cause rupture of the aneurysm due to laceration of its neck. Although aneurysm clip scissoring is well known, there have been few reports describing the details of this phenomenon. Quasi-scissoring phenomenon was introduced mechanically by rotating the clip head attached to a silicone sheet. The anti-scissoring torque during the twist of the blades was measured by changing the depth and the opening width. The closing force was also evaluated. Sugita straight clips of titanium alloy and cobalt alloy were used in the present study. In both materials, the anti-scissoring torque and the closing force were bigger 3 mm in thickness than 1 mm. The initial closing forces and the anti-scissoring torque values at each rotation angles were increased in proportion to depth. Closing forces of titanium alloy clip were slightly higher than those of cobalt alloy clip. By contrast, anti-scissoring torque values of cobalt alloy clip were bigger than those of titanium alloy clip in all conditions. In condition of 3 mm in thickness and 3 mm in depth, anti-scissoring torque vales of titanium alloy clip decreased suddenly when an angle surpassed 70 degrees. Aneurysm clip scissoring phenomenon tends to occur when clipping the aneurysm neck only with blade tips. Based on the results of this experiment, titanium alloy clip is more prone to scissoring than cobalt alloy clip under the condition that the wide blade separation distance and the shallow blade length.

  19. from Ikpoba Reservoir, Benin City, Nigeria. *1WANGBOJE, O.

    African Journals Online (AJOL)

    Michael Horsfall

    ABSTRACT: This study determined the concentrations of Cd, Mn, Cu, Pb, Zn and Cr in. Synodontis clarias (Linnaeus, 1766) and ... concentrations of Cu and Zn in water, were significantly different (P<0.05) between stations. Manganese was ..... can be found in batteries, rust inhibitors, ammunition, solder, alloys and plastic.

  20. Joining Techniques for Ferritic ODS Alloys

    Energy Technology Data Exchange (ETDEWEB)

    V.G. Krishnardula; V.G. Krishnardula; D.E. Clark; T.C. Totemeier

    2005-06-01

    This report presents results of research on advanced joining techniques for ferritic oxide-dispersion strengthened alloys MA956 and PM2000. The joining techniques studied were resistance pressure welding (also known as pressure forge welding), transient liquid phase bonding, and diffusion bonding. All techniques were shown to produce sound joints in fine-grained, unrecrystallized alloys. Post-bond heat treatment to produce a coarse-grained, recrystallized microstructure resulted in grain growth across the bondline for transient liquid phase and diffusion bonds, giving microstructures essentially identical to that of the parent alloy in the recrystallized condition. The effects of bond orientation, boron interlayer thickness, and bonding parameters are discussed for transient liquid phase and diffusion bonding. The report concludes with a brief discussion of ODS joining techniques and their applicability to GEN IV reactor systems.

  1. Modeling of the mechanical alloying process

    Science.gov (United States)

    Maurice, D.; Courtney, T. H.

    1992-01-01

    Two programs have been developed to compute the dimensional and property changes that occur with repetitive impacts during the mechanical alloying process. The more sophisticated of the programs also maintains a running count of the fractions of particles present and from this calculates a population distribution. The programs predict powder particle size and shape changes in accord with the accepted stages of powder development during mechanical alloying of ductile species. They also predict hardness and lamellar thickness changes with processing, again with reasonable agreement with experimental results. These predictions offer support of the model (and thereby give insight into the possible 'actual' happenings of mechanical alloying) and hence allow refinement and calibration of the myriad aspects of the model. They also provide a vehicle for establishing control over the dimensions and properties of the output powders used for consolidation, thereby facilitating optimization of the consolidation process.

  2. Positron annihilation characterization of nanostructured ferritic alloys

    International Nuclear Information System (INIS)

    Alinger, M.J.; Glade, S.C.; Wirth, B.D.; Odette, G.R.; Toyama, T.; Nagai, Y.; Hasegawa, M.

    2009-01-01

    Nanostructured ferritic alloys (NFAs) were produced by mechanically alloying Fe-14Cr-3W-0.4Ti and 0.25Y 2 O 3 (wt%) powders followed by hot isostatic pressing consolidation at 850, 1000 and 1150 deg. C. Positron annihilation lifetime and orbital momentum spectroscopy measurements are in qualitative agreement with small angle neutron scattering, transmission electron microscopy and atom probe tomography observations, indicating that up to 50% of the annihilations occur at high densities of Y-Ti-O enriched nm-scale features (NFs). Some annihilations may also occur in small cavities. In Y-free control alloys, that do not contain NFs, positrons primarily annihilate in the Fe-Cr matrix and at features such as dislocations, while a small fraction annihilate in large cavities or Ar bubbles.

  3. Alloys having improved resistance to hydrogen embrittlement

    International Nuclear Information System (INIS)

    Kane, R.D.; Greer, J.B.; Jacobs, D.F.; Berkowitz, B.J.

    1983-01-01

    The invention involves a process of improving the hydrogen embrittlement resistance of a cold-worked high yield strength nickel/cobalt base alloy containing chromium, and molybdenum and/or tungsten and having individual elemental impurity concentrations as measured by Auger spectroscopy at the crystallographic boundaries of up to about 1 Atomic percent. These elemental impurities are capable of becoming active and mobile at a temperature less than the recrystallization temperature of the alloy. The process involves heat treating the alloy at a temperature above 1300 degrees F but below the temperature of recrystallization for a time of from 1/4 to 100 hours. This is sufficient to effect a reduction in the level of the elemental impurities at the crystallographic boundaries to the range of less than 0.5 Atomic percent without causing an appreciable decrease in yield strength

  4. Steam generated conversion coating on aluminium alloys

    DEFF Research Database (Denmark)

    Din, Rameez Ud; Jellesen, Morten Stendahl; Ambat, Rajan

    Aluminium and its alloys are widely used in aerospace industry owing to their high strength to weight ratio. The surface of aluminium under normal conditions has a thin oxide film (2.5-10 nm) responsible for its inherent corrosion resistance. This oxide film can further be converted or transformed...... into functional conversion coatings in order to enhance corrosion resistance and adhesion to paint systems. Chromium based conversion coatings have been extensively used on aluminium alloys to improve adhesion of subsequent paint layers and corrosion resistance. However, the use of hexavalent chromium is strictly...... and growth of oxide film on different intermetallic particles and corrosion behaviour of such alloys.Surface morphology was observed by using FEG-SEM, EDX and FIB-SEM. Metal oxide surface characterization and compositional depth profiling were investigated by using XPS and GD-OES respectively...

  5. Kinetics of hydrogen release from alloyed iron

    International Nuclear Information System (INIS)

    Gomozov, P.A.; Mogutnov, B.M.; Shvartsman, L.A.

    1977-01-01

    The kinetics of evolution of hydrogen from Armco-iron and alloys of iron with small amounts of carbon, phosphorus, sulfur, titanium, silicon and nickel was studied in the temperature range from 24 to 110 deg C. This process is described in terms of a kinetic equation which follows from the solution of the equation of diffusion with boundary conditions allowing for the rate of the chemical reaction on the surface of the specimen. A strong dependence is noted of the surface reaction on the presence of small amounts of alloying elements in the iron. The reaction of evolution of hydrogen from iron and its alloys in the temperature range from 24 to 110 deg C takes place in a combined diffusion-kinetic range

  6. Machinability of cast commercial titanium alloys.

    Science.gov (United States)

    Watanabe, I; Kiyosue, S; Ohkubo, C; Aoki, T; Okabe, T

    2002-01-01

    This study investigated the machinability of cast orthopedic titanium (metastable beta) alloys for possible application to dentistry and compared the results with those of cast CP Ti, Ti-6Al-4V, and Ti-6Al-7Nb, which are currently used in dentistry. Machinability was determined as the amount of metal removed with the use of an electric handpiece and a SiC abrasive wheel turning at four different rotational wheel speeds. The ratios of the amount of metal removed and the wheel volume loss (machining ratio) were also evaluated. Based on these two criteria, the two alpha + beta alloys tested generally exhibited better results for most of the wheel speeds compared to all the other metals tested. The machinability of the three beta alloys employed was similar or worse, depending on the speed of the wheel, compared to CP Ti. Copyright 2002 Wiley Periodicals, Inc.

  7. On the superconductivity of vanadium based alloys

    International Nuclear Information System (INIS)

    Brouers, F.; Rest, J. Van der

    1984-01-01

    The electron density of states of solid solutions of vanadium based transition metal alloys V 90 X 10 is computed with the aim of calculating the superconducting transition temperature using the McMillan formula. As observed experimentally for X on the left hand side of V in the periodic table, one obtains an increase of Tc while for X on the right hand side of V the critical temperature decreases. The detailed comparison with experiments indicate that when the bandwidths of the two constituents are different, one cannot neglect the variation of the electron-phonon interactions. Another important conclusion is that for alloys which are in the split-band limit like VAu, VPd and VPt, the agreement with experimental data can be obtained only by assuming that these alloys have a short-range order favouring clusters of pure vanadium. (Author) [pt

  8. Friction Stir Welding of Steel Alloys

    Science.gov (United States)

    Ding, R. Jeffrey; Munafo, Paul M. (Technical Monitor)

    2001-01-01

    The friction stir welding process has been developed primarily for the welding of aluminum alloys. Other higher melting allows such, as steels are much more difficult to join. Special attention must be given to pin tool material selection and welding techniques. This paper addresses the joining of steels and other high melting point materials using the friction stir welding process. Pin tool material and welding parameters will be presented. Mechanical properties of weldments will also be presented. Significance: There are many applications for the friction stir welding process other than low melting aluminum alloys. The FSW process can be expanded for use with high melting alloys in the pressure vessel, railroad and ship building industries.

  9. Seacoast stress corrosion cracking of aluminum alloys

    Science.gov (United States)

    Humphries, T. S.; Nelson, E. E.

    1981-01-01

    The stress corrosion cracking resistance of high strength, wrought aluminum alloys in a seacoast atmosphere was investigated and the results were compared with those obtained in laboratory tests. Round tensile specimens taken from the short transverse grain direction of aluminum plate and stressed up to 100 percent of their yield strengths were exposed to the seacoast and to alternate immersion in salt water and synthetic seawater. Maximum exposure periods of one year at the seacoast, 0.3 or 0.7 of a month for alternate immersion in salt water, and three months for synthetic seawater were indicated for aluminum alloys to avoid false indications of stress corrosion cracking failure resulting from pitting. Correlation of the results was very good among the three test media using the selected exposure periods. It is concluded that either of the laboratory test media is suitable for evaluating the stress corrosion cracking performance of aluminum alloys in seacoast atmosphere.

  10. Titanium by design: TRIP titanium alloy

    Science.gov (United States)

    Tran, Jamie

    Motivated by the prospect of lower cost Ti production processes, new directions in Ti alloy design were explored for naval and automotive applications. Building on the experience of the Steel Research Group at Northwestern University, an analogous design process was taken with titanium. As a new project, essential kinetic databases and models were developed for the design process and used to create a prototype design. Diffusion kinetic models were developed to predict the change in phase compositions and microstructure during heat treatment. Combining a mobility database created in this research with a licensed thermodynamic database, ThermoCalc and DICTRA software was used to model kinetic compositional changes in titanium alloys. Experimental diffusion couples were created and compared to DICTRA simulations to refine mobility parameters in the titanium mobility database. The software and database were able to predict homogenization times and the beta→alpha plate thickening kinetics during cooling in the near-alpha Ti5111 alloy. The results of these models were compared to LEAP microanalysis and found to be in reasonable agreement. Powder metallurgy was explored using SPS at GM R&D to reduce the cost of titanium alloys. Fully dense Ti5111 alloys were produced and achieved similar microstructures to wrought Ti5111. High levels of oxygen in these alloys increased the strength while reducing the ductility. Preliminary Ti5111+Y alloys were created, where yttrium additions successfully gettered excess oxygen to create oxides. However, undesirable large oxides formed, indicating more research is needed into the homogeneous distribution of the yttrium powder to create finer oxides. Principles established in steels were used to optimize the beta phase transformation stability for martensite transformation toughening in titanium alloys. The Olson-Cohen kinetic model is calibrated to shear strains in titanium. A frictional work database is established for common alloying

  11. Copper-rich invar by mechanical alloying

    Science.gov (United States)

    O'Donnell, K.; Qi, Qinian; Ilyushin, A. S.; Coey, J. M. D.

    1993-05-01

    An fcc alloy of composition Fe 64Cu 26Cr 7Ni 3 with a0 = 0.362 nm and an average crystalline size of 5 nm was produced by high-energy ball milling iron and copper powder in a stainless-steel container. The average number of electrons per atom is 8.7. The Curie temperature of the alloy is 410 K and the room-temperature magnetization is 48 JT -1 kg -1. The Mössbauer spectrum at 15 K shows a broad distribution of hyperfine field with an average of 15.6 T, which indicates coexistence of high and low moment states for iron. The alloy decomposes exothermically at 775 K to yield a mixture of bcc and fcc phases, but 50% of the iron remains in the fcc form with a low moment.

  12. The metallurgy of high temperature alloys

    Science.gov (United States)

    Tien, J. K.; Purushothaman, S.

    1976-01-01

    Nickel-base, cobalt-base, and high nickel and chromium iron-base alloys are dissected, and their microstructural and chemical components are assessed with respect to the various functions expected of high temperature structural materials. These functions include the maintenance of mechanical integrity over the strain-rate spectrum from creep resistance through fatigue crack growth resistance, and such alloy stability expectations as microstructural coarsening resistance, phase instability resistance and oxidation and corrosion resistance. Special attention will be given to the perennial conflict and trade-off between strength, ductility and corrosion and oxidation resistance. The newest developments in the constitution of high temperature alloys will also be discussed, including aspects relating to materials conservation.

  13. Mechanical and microstructural characterization of the nickel base alloy (Alloy 600) after heat treatment

    International Nuclear Information System (INIS)

    Fernandes, Stela Maria de Carvalho

    1993-01-01

    The characterization of microstructural and mechanical properties of cold rolled and heat treated alloys 600 made in Brazil were investigated. The recovery and recrystallization behavior as well as solubilization and aging have been studied using optical, scanning electron and transmission electron microscopy. Microhardness and tensile testing have been carried out. The recovery process of the cold rolled alloy 600 occurred until 600 deg C and the recrystallization stage was situated between 600 and 850 deg C. The primary recrystallization temperature was obtained at 850 deg C after 1 hour (isochronal heat treatments). The aged alloy 600 shows carbide precipitation on grains bu with ductility maintenance. (author)

  14. Formation and characterization of Al–Ti–Nb alloys by electron-beam surface alloying

    Energy Technology Data Exchange (ETDEWEB)

    Valkov, S., E-mail: stsvalkov@gmail.com [Institute of Electronics, Bulgarian Academy of Science, 72 Tzarigradsko Chaussee blvd., 1784 Sofia (Bulgaria); Petrov, P. [Institute of Electronics, Bulgarian Academy of Science, 72 Tzarigradsko Chaussee blvd., 1784 Sofia (Bulgaria); Lazarova, R. [Institute of Metal Science, Equipment and Technologies with Hydro and Aerodynamics Center, Bulgarian Academy of Science, 67 Shipchenski Prohod blvd., 1574 Sofia (Bulgaria); Bezdushnyi, R. [Department of Solid State Physics and Microelectronics, Faculty of Physics, Sofia University “St. Kliment Ohridsky”, 1164 Sofia (Bulgaria); Dechev, D. [Institute of Electronics, Bulgarian Academy of Science, 72 Tzarigradsko Chaussee blvd., 1784 Sofia (Bulgaria)

    2016-12-15

    Highlights: • Al–Ti–Nb surface alloys have been successfully obtained by electron-beam surface alloying technology. • The alloys consist of (Ti,Nb)Al{sub 3} fractions, distributed in the biphasic structure of (Ti,Nb)Al{sub 3} particles dispersed in α-Al. • The alloying speed does not affect the lattice parameters of (Ti,Nb)Al{sub 3} and, does not form additional stresses, strains etc. • It was found that lower velocity of the specimen motion during the alloying process develops more homogeneous structures. • The measured hardness of (Ti,Nb)Al{sub 3} compound reaches 775 HV[kg/cm{sup 2}] which is much greater than the values of NbAl{sub 3}. - Abstract: The combination of attractive mechanical properties, light weight and resistance to corrosion makes Ti-Al based alloys applicable in many industrial branches, like aircraft and automotive industries etc. It is known that the incorporation of Nb improves the high temperature performance and mechanical properties. In the present study on Al substrate Ti and Nb layers were deposited by DC (Direct Current) magnetron sputtering, followed by electron-beam alloying with scanning electron beam. It was chosen two speeds of the specimen motion during the alloying process: V{sub 1} = 0.5 cm/s and V{sub 2} = 1 cm/s. The alloying process was realized in circular sweep mode in order to maintain the melt pool further. The obtained results demonstrate a formation of (Ti,Nb)Al{sub 3} fractions randomly distributed in biphasic structure of intermetallic (Ti,Nb)Al{sub 3} particles, dispersed in α-Al solid solution. The evaluated (Ti,Nb)Al{sub 3} lattice parameters are independent of the speed of the specimen motion and therefore the alloying speed does not affect the lattice parameters and thus, does not form additional residual stresses, strains etc. It was found that lower velocity of the specimen motion during the alloying process develops more homogeneous structures. The metallographic analyses demonstrate a

  15. 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

  16. Non-alloyed Ni3Al based alloys – preparation and evaluation of mechanical properties

    Directory of Open Access Journals (Sweden)

    J. Malcharcziková

    2013-07-01

    Full Text Available The paper reports on the fabrication and mechanical properties of Ni3Al based alloy, which represents the most frequently used basic composition of nickel based intermetallic alloys for high temperature applications. The structure of the alloy was controlled through directional solidification. The samples had a multi-phase microstructure. The directionally solidified specimens were subjected to tensile tests with concurrent measurement of acoustic emission (AE. The specimens exhibited considerable room temperature ductility before fracture. During tensile testing an intensive AE was observed.

  17. Magnesium alloy AZ63A reinforcement by alloying with gallium and using high-disperse ZrO2 particles

    Directory of Open Access Journals (Sweden)

    J. Khokhlova

    2016-12-01

    Full Text Available The aim of this work was to obtain an experimental magnesium alloy by remelting standard AZ63A alloy with addition of gallium ligatures and ZrO2 particles. This allowed reinforcement of alloy and increase its hardness and Young's modulus. The chemical analysis of this alloy shows two types of structures which are evenly distributed in volume. Thus we can conclude that reinforcing effect is the result of formation of intermetallic phase Mg5-Ga2.

  18. Electrocatalysts having platium monolayers on palladium, palladium alloy, and gold alloy core-shell nanoparticles, and uses thereof

    Science.gov (United States)

    Adzic, Radoslav; Mo, Yibo; Vukmirovic, Miomir; Zhang, Junliang

    2010-12-21

    The invention relates to platinum-coated particles useful as fuel cell electrocatalysts. The particles are composed of a noble metal or metal alloy core at least partially encapsulated by an atomically thin surface layer of platinum atoms. The invention particularly relates to such particles having a palladium, palladium alloy, gold alloy, or rhenium alloy core encapsulated by an atomic monolayer of platinum. In other embodiments, the invention relates to fuel cells containing these electrocatalysts and methods for generating electrical energy therefrom.

  19. Fast LIBS Identification of Aluminum Alloys

    Directory of Open Access Journals (Sweden)

    Tawfik W.

    2007-04-01

    Full Text Available Laser-induced breakdown spectroscopy (LIBS has been applied to analysis aluminum alloy targets. The plasma is generated by focusing a 300 mJ pulsed Nd: YAG laser on the target in air at atmospheric pressure. Such plasma emission spectrum was collected using a one-meter length wide band fused-silica optical fiber connected to a portable Echelle spectrometer with intensified CCD camera. Spectroscopic analysis of plasma evolution of laser produced plasmas has been characterized in terms of their spectra, electron density and electron temperature assuming the LTE and optically thin plasma conditions. The LIBS spectrum was optimized for high S/N ratio especially for trace elements. The electron temperature and density were determined using the emission intensity and stark broadening, respectively, of selected aluminum spectral lines. The values of these parameters were found to change with the aluminum alloy matrix, i.e. they could be used as a fingerprint character to distinguish between different aluminum alloy matrices using only one major element (aluminum without needing to analysis the rest of elements in the matrix. Moreover, It was found that the values of T e and N e decrease with increasing the trace elements concentrations in the aluminum alloy samples. The obtained results indicate that it is possible to improve the exploitation of LIBS in the remote on-line industrial monitoring application, by following up only the values of T e and N e for aluminum in aluminum alloys as a marker for the correct alloying using an optical fiber probe.

  20. Stable carbides in transition metal alloys

    International Nuclear Information System (INIS)

    Piotrkowski, R.

    1991-01-01

    In the present work different techniques were employed for the identification of stable carbides in two sets of transition metal alloys of wide technological application: a set of three high alloy M2 type steels in which W and/or Mo were total or partially replaced by Nb, and a Zr-2.5 Nb alloy. The M2 steel is a high speed steel worldwide used and the Zr-2.5 Nb alloy is the base material for the pressure tubes in the CANDU type nuclear reactors. The stability of carbide was studied in the frame of Goldschmidt's theory of interstitial alloys. The identification of stable carbides in steels was performed by determining their metallic composition with an energy analyzer attached to the scanning electron microscope (SEM). By these means typical carbides of the M2 steel, MC and M 6 C, were found. Moreover, the spatial and size distribution of carbide particles were determined after different heat treatments, and both microstructure and microhardness were correlated with the appearance of the secondary hardening phenomenon. In the Zr-Nb alloy a study of the α and β phases present after different heat treatments was performed with optical and SEM metallographic techniques, with the guide of Abriata and Bolcich phase diagram. The α-β interphase boundaries were characterized as short circuits for diffusion with radiotracer techniques and applying Fisher-Bondy-Martin model. The precipitation of carbides was promoted by heat treatments that produced first the C diffusion into the samples at high temperatures (β phase), and then the precipitation of carbide particles at lower temperature (α phase or (α+β)) two phase field. The precipitated carbides were identified as (Zr, Nb)C 1-x with SEM, electron microprobe and X-ray diffraction techniques. (Author) [es

  1. Creep behavior of Zr-Nb alloys

    Energy Technology Data Exchange (ETDEWEB)

    Suh, Yong Chan; Kim, Young Suk; Cheong, Yong Mu; Kwon, Sang Chul; Kim, Sung Soo; Choo, Ki Nam [Korea Atomic Energy Research Institute, Taejeon (Korea)

    2000-01-01

    The creep characteristics of Zirconium alloy is affected by several parameters. Out-reactor creep increases both with an increasing amount of Nb, Sn and S contained in alpha-Zr and decreases with the increasing volume of alpha-Zr. Especially, the creep of Zr-2.5Nb alloy depends on the solubility of Nb in alpha-Zr, which is associated with the decomposition of beta-Zr. Since Zr of the hcp structure is strongly anisotropic, it shows the characteristics of texture and results in the anisotropy of creep. Due to the circumferential texture of Zr-2.5%Nb alloy (CANDU Pressure tube), the longitudinal slip is easier than the circumferential one, resulting in the high creep rate. The irradiation creep also increases with increasing neutron fluence. The neutron irradiation increases the strength of the zirconium alloys but decreases their creep strength. In contrast to the out-reactor creep, the irradiation creep is little sensitive to temperature, resulting in the lower activation energy. The most important factor to affect the in-reactor and out-reactor creep of niobium containing alloys seems to be the solution hardening by Nb or Sn which is soluble in alpha-zirconium and the texture as well. Irradiation growth is the mechanism which is caused only by the irradiation. It becomes saturated at lower fluence than the critical fluence but beyond it, shows the break-away growth. The onset of accelerated irradiation growth corresponds with the c-dislocation loop formation, though its mechanism needs better understanding. Generally, the irradiation growth of Zr-Nb alloys increases with an increase in fluence, cold working, dislocation, density and temperature, and with a decrease in the grain size. 141 refs., 59 figs., 10 tabs. (Author)

  2. The influence of the pure metal components of four different casting alloys on the electrochemical properties of the alloys.

    Science.gov (United States)

    Tuna, Süleyman H; Pekmez, Nuran Ozçiçek; Keyf, Filiz; Canli, Fulya

    2009-09-01

    The aim of this study was to investigate the influence of the pure metal components of the four different casting alloys on the corrosion behaviors of these alloys tested. Potentiodynamic polarization tests were carried out on four different types of casting alloys and their pure metals at 37 degrees C in an artificial saliva solution. The ions released from the alloys into the solutions during the polarization test were also determined quantitatively using inductively coupled plasma-mass spectrometry (ICP-MS). Ni-Cr (M1) and Co-Cr (M2) alloys had a more homogenous structure than palladium based (M3) and gold based (M4) alloys in terms of the pitting potentials of the casting alloys and those of the pure metals composing the alloys. The total ion concentration released from M3 and M4 was less than from M1 and M2. This may be because M3 and M4 alloys contained noble metals. It was also found that the noble metals in the M3 and M4 samples decreased the current density in the anodic branch of the potentiodynamic polarization curves. In other words, noble metals contributed positively to dental materials. Corrosion resistance of the casting alloys can be affected by the pure metals they are composed of. Au and Pd based noble alloys dissolved less than Ni-Cr and Co-Cr based alloys.

  3. Mechanical Alloying for Making Thermoelectric Compounds

    Science.gov (United States)

    Huang, Chen-Kuo; Fleurial, Jean-Pierre; Snyder, Jeffrey; Blair, Richard; May, Andrew

    2007-01-01

    An economical room-temperature mechanical alloying process has been shown to be an effective means of making a homogeneous powder that can be hot-pressed to synthesize a thermoelectric material having reproducible chemical composition. The synthesis of a given material consists of the room temperature thermomechanical-alloying process followed b y a hot-pressing process. Relative to synthesis of nominally the same material by a traditional process that includes hot melting, this s ynthesis is simpler and yields a material having superior thermoelect ric properties.

  4. A Study of Protection of Copper Alloys

    International Nuclear Information System (INIS)

    Kim, E. A.; Kim, S. H.; Kim, C. R.

    1974-01-01

    Volatile treatment of high capacity boiler water with hydrazine and ammonia is studied. Ammonia comes from the decomposition of excess hydrazine injected to treat dissolved oxygen. Ammonia is also injected for the control of pH. To find an effect of such ammonia on the copper alloy, the relations between pH and iron, and ammonia and copper are studied. Since the dependence of corrosion of iron on pH differs from that of copper, a range of pH was selected experimentally to minimize the corrosion rates of both copper and iron. Corrosion rates of various copper alloys are also compared

  5. Metals and Alloys Material Stabilization Process Plan

    Energy Technology Data Exchange (ETDEWEB)

    RISENMAY, H.R.; BURK, R.A.

    2000-05-18

    This Plan outlines the process for brushing metal and alloys in accordance with the path forward discussed in the Integrated Project Management Plan for the Plutonium Finishing Plant Stabilization and Deactivation Project, HNF-3617, and requirements set forth in the Project Management Plan for Materials Stabilization, HNF-3605. This plan provides the basis for selection of the location to process, the processes involved, equipment to be used, and the characterization of the contents of the can. The scope of the process is from retrieval of metals and alloys from storage to transfer back to storage in a repackaged configuration.

  6. Metals and Alloys Material Stabilization Process Plan

    International Nuclear Information System (INIS)

    RISENMAY, H.R.; BURK, R.A.

    2000-01-01

    This Plan outlines the process for brushing metal and alloys in accordance with the path forward discussed in the Integrated Project Management Plan for the Plutonium Finishing Plant Stabilization and Deactivation Project, HNF-3617, and requirements set forth in the Project Management Plan for Materials Stabilization, HNF-3605. This plan provides the basis for selection of the location to process, the processes involved, equipment to be used, and the characterization of the contents of the can. The scope of the process is from retrieval of metals and alloys from storage to transfer back to storage in a repackaged configuration

  7. Electromagnetic Characterization Of Metallic Sensory Alloy

    Science.gov (United States)

    Wincheski, Russell A.; Simpson, John; Wallace, Terryl A.; Newman, John A.; Leser, Paul; Lahue, Rob

    2012-01-01

    Ferromagnetic shape-memory alloy (FSMA) particles undergo changes in both electromagnetic properties and crystallographic structure when strained. When embedded in a structural material, these attributes can provide sensory output of the strain state of the structure. In this work, a detailed characterization of the electromagnetic properties of a FSMA under development for sensory applications is performed. In addition, a new eddy current probe is used to interrogate the electromagnetic properties of individual FSMA particles embedded in the sensory alloy during controlled fatigue tests on the multifunctional material.

  8. The Delayed Fracture of Aluminum Alloys.

    Science.gov (United States)

    1981-01-01

    equipment. 3) The Mg-H complex formed but decomposed so rapidly in the vacuum that its PLE could not be measured. -39- Two magnesium hydrides are...Zn-Mg Alloys," Corros. Sci., 1976, vol. 16, no. 7, p. 443. 15. C.D.S. Tuck: "Evidence for the Formation of Magnesium Hydride on the Grain Boundaries...1977). 17. W. Pistulka and G. Lang: "Accelerated Stress-Corrosion Test Methods for Al-Zn-Mg Type Alloys," Aluminium , Duesseldorf, 1977, vol. 53, no. 6

  9. Hydrogenation properties of Mg-Al alloys

    DEFF Research Database (Denmark)

    Andreasen, Anders

    2008-01-01

    to disproportionation with the formation of magnesium hydride and metallic aluminum as the final product. Experimental evidence renders this process reversible. It is observed that the enthalpy of hydride formation of magnesium is lowered upon alloying with Al due to a slightly endothermic disproportionation reaction......In this paper the properties of Mg-Al alloys in relation to hydrogen storage are reviewed. The main topics of this paper are materials preparation, hydrogen capacity, thermodynamics of hydride formation, and the kinetics of hydride formation and decomposition. Hydrogenation of Mg-Al leads...

  10. A bidirectional shape memory alloy folding actuator

    International Nuclear Information System (INIS)

    Paik, Jamie K; Wood, Robert J

    2012-01-01

    This paper presents a low-profile bidirectional folding actuator based on annealed shape memory alloy sheets applicable for meso- and microscale systems. Despite the advantages of shape memory alloys—high strain, silent operation, and mechanical simplicity—their application is often limited to unidirectional operation. We present a bidirectional folding actuator that produces two opposing 180° motions. A laser-patterned nickel alloy (Inconel 600) heater localizes actuation to the folding sections. The actuator has a thin ( < 1 mm) profile, making it appropriate for use in robotic origami. Various design parameters and fabrication variants are described and experimentally explored in the actuator prototype. (paper)

  11. An all aluminum alloy UHV components

    International Nuclear Information System (INIS)

    Sugisaki, Kenzaburo

    1985-01-01

    An all aluminum components was developed for use with UHV system. Aluminum alloy whose advantage are little discharge gas, easy to bake out, light weight, little damage against radieactivity radiation is used. Therefore, as it is all aluminum alloy, baking is possible. Baking temperature is 150 deg C in case of not only ion pump, gate valve, angle valve but also aluminum components. Ion pump have to an ultrahigh vacuum of order 10 -9 torr can be obtained without baking, 10 -10 torr order can be obtained after 24 hour of baking. (author)

  12. Thermal expansion: Metallic elements and alloys. [Handbook

    Science.gov (United States)

    Touloukian, Y. S.; Kirby, R. K.; Taylor, R. E.; Desai, P. D.

    1975-01-01

    The introductory sections of the work are devoted to the theory of thermal expansion of solids and to methods for the measurement of the linear thermal expansion of solids (X-ray methods, high speed methods, interferometry, push-rod dilatometry, etc.). The bulk of the work is devoted to numerical data on the thermal linear expansion of all the metallic elements, a large number of intermetallics, and a large number of binary alloy systems and multiple alloy systems. A comprehensive bibliography is provided along with an index to the materials examined.

  13. Plasticity of oxide dispersion strengthened ferritic alloys

    International Nuclear Information System (INIS)

    Zakine, C.; Prioul, C.; Alamo, A.; Francois, D.

    1993-01-01

    Two 13%Cr oxide dispersion strengthened (ODS) ferritic alloys, DT and DY, exhibiting different oxide particle size distribution and a χ phase precipitation were studied. Their tensile properties have been tested from 20 to 700 C. Experimental observations during room temperature tensile tests performed in a scanning electronic microscope have shown that the main damage mechanism consists in microcracking of the χ phase precipitates on grain boundaries. These alloys are high tensile and creep resistant between 500 and 700 C. Their strongly stress-sensitive creep behaviour can be described by usual creep laws and incorporating a threshold stress below which the creep rate is negligible. (orig.)

  14. Magnetic susceptibility of Dirac fermions, Bi-Sb alloys, interacting Bloch fermions, dilute nonmagnetic alloys, and Kondo alloys

    Energy Technology Data Exchange (ETDEWEB)

    Buot, Felix A., E-mail: fbuot@gmu.edu [Computational Materials Science Center, George Mason University, Fairfax, VA 22030 (United States); TCSE Center, Spintronics Group, Physics Department, University of San Carlos, Talamban, Cebu 6000 (Philippines); C& LB Research Institute, Carmen, Cebu 6005 (Philippines); Otadoy, Roland E.S.; Rivero, Karla B. [TCSE Center, Spintronics Group, Physics Department, University of San Carlos, Talamban, Cebu 6000 (Philippines)

    2017-03-01

    Wide ranging interest in Dirac Hamiltonian is due to the emergence of novel materials, namely, graphene, topological insulators and superconductors, the newly-discovered Weyl semimetals, and still actively-sought after Majorana fermions in real materials. We give a brief review of the relativistic Dirac quantum mechanics and its impact in the developments of modern physics. The quantum band dynamics of Dirac Hamiltonian is crucial in resolving the giant diamagnetism of bismuth and Bi-Sb alloys. Quantitative agreement of the theory with the experiments on Bi-Sb alloys has been achieved, and physically meaningful contributions to the diamagnetism has been identified. We also treat relativistic Dirac fermion as an interband dynamics in uniform magnetic fields. For the interacting Bloch electrons, the role of translation symmetry for calculating the magnetic susceptibility avoids any approximation to second order in the field. The expressions for magnetic susceptibility of dilute nonmagnetic alloys give a firm theoretical foundation of the empirical formulas used in fitting experimental results. The unified treatment of all the above calculations is based on the lattice Weyl-Wigner formulation of discrete phase-space quantum mechanics. For completeness, the magnetic susceptibility of Kondo alloys is also given since Dirac fermions in conduction band and magnetic impurities exhibit Kondo effect.

  15. A review on hot tearing of magnesium alloys

    Directory of Open Access Journals (Sweden)

    Jiangfeng Song

    2016-09-01

    Full Text Available Hot tearing is often a major casting defect in magnesium alloys and has a significant impact on the quality of their casting products. Hot tearing of magnesium alloys is a complex solidification phenomenon which is still not fully understood, it is of great importance to investigate the hot tearing behaviour of magnesium alloys. This review attempts to summarize the investigations on hot tearing of magnesium alloys over the past decades. The hot tearing criteria including recently developed Kou's criterion are summarized and compared. The numeric simulation and assessing methods of hot tearing, factors influencing hot tearing, and hot tearing susceptibility (HTS of magnesium alloys are discussed.

  16. Numerical predicting of recycling friendly wrought aluminium alloy compositions

    Directory of Open Access Journals (Sweden)

    Varužan Kevorkijan

    2013-09-01

    Full Text Available The model presented in this work enables the design of optimal (standard and non-standard “recycling-friendly” compositions and properties of wrought aluminium alloys with significantly increased amounts of post-consumed scrap. The following two routes were modelled in detail: (i the blending of standard and non-standard compositions of wrought aluminium alloys starting from post-consumed aluminium scrap sorted to various degrees simulated by the model; and (ii changing the initial standard composition of wrought aluminium alloys to non-standard “recycling friendly” ones - with broader concentration tolerance limits of alloying elements, without influencing the selected alloy properties, specified in advance.

  17. Vanadium-base alloys for fusion reactor applications

    International Nuclear Information System (INIS)

    Smith, D.L.; Loomis, B.A.; Diercks, D.R.

    1984-10-01

    Vanadium-base alloys offer potentially significant advantages over other candidate alloys as a structural material for fusion reactor first wall/blanket applications. Although the data base is more limited than that for the other leading candidate structural materials, viz., austenitic and ferritic steels, vanadium-base alloys exhibit several properties that make them particularly attractive for the fusion reactor environment. This paper presents a review of the structural material requirements, a summary of the materials data base for selected vanadium-base alloys, and a comparison of projected performance characteristics compared to other candidate alloys. Also, critical research and development (R and D) needs are defined

  18. Vanadium-base alloys for fusion reactor applications

    Energy Technology Data Exchange (ETDEWEB)

    Smith, D.L.; Loomis, B.A.; Diercks, D.R.

    1984-10-01

    Vanadium-base alloys offer potentially significant advantages over other candidate alloys as a structural material for fusion reactor first wall/blanket applications. Although the data base is more limited than that for the other leading candidate structural materials, viz., austenitic and ferritic steels, vanadium-base alloys exhibit several properties that make them particularly attractive for the fusion reactor environment. This paper presents a review of the structural material requirements, a summary of the materials data base for selected vanadium-base alloys, and a comparison of projected performance characteristics compared to other candidate alloys. Also, critical research and development (R and D) needs are defined.

  19. Phase transformations during sintering of mechanically alloyed TiPt

    CSIR Research Space (South Africa)

    Nxumalo, S

    2010-10-01

    Full Text Available first and high temperature melting phases form last12. This behaviour is what is observed in this work with the four phases with low melting points being formed which are Ti(Pt), Ti3Pt, TiPt and Ti3Pt5. It is therefore, probable that phase formation.... 1.0 Introduction TiPt is a potential alloy for use as a high temperature shape memory alloy (SMA). Shape memory alloys are alloys that will revert to the shape they had before deformation if the deformed alloy is annealed at a certain temperature...

  20. On the principles of microstructure scale development for titanium alloys

    International Nuclear Information System (INIS)

    Kolachev, B.A.; Mal'kov, A.V.; Gus'kova, L.N.

    1982-01-01

    Analysis of an existing standard scale of microstructures for two-phase (α+#betta#)-titanium alloy semiproducts is given. The basic principles of development of control microstructure scales for titanium alloys are presented on the base of investigations and generalization of literature data on connection of microstructure of titanium intermediate products from (α+#betta#)-alloys with their mechanical properties and service life characteristics. A possibilities of changing mechanical and operating properties at the expense of obtaining qualitatively and quantitatively regulated microstructure in the alloy are disclosed on the example of the (α+#betta#)-titanium alloy

  1. Stress corrosion in high-strength aluminum alloys

    Science.gov (United States)

    Dorward, R. C.; Hasse, K. R.

    1980-01-01

    Report describes results of stress-corrosion tests on aluminum alloys 7075, 7475, 7050, and 7049. Tests compare performance of original stress-corrosion-resistant (SCR) aluminum, 7075, with newer, higher-strength SCR alloys. Alloys 7050 and 7049 are found superior in short-transverse cross-corrosion resistance to older 7075 alloy; all alloys are subject to self-loading effect caused by wedging of corrosion products in cracks. Effect causes cracks to continue to grow, even at very-low externally applied loads.

  2. Corrosion behavior of friction stir welded AZ31B Mg alloy - Al6063 alloy joint

    Directory of Open Access Journals (Sweden)

    B. Ratna Sunil

    2016-12-01

    Full Text Available In the present work, AZ31B Mg alloy and Al6063 alloy-rolled sheets were successfully joined by friction stir welding. Microstructural studies revealed a sound joint with good mechanical mixing of both the alloys at the nugget zone. Corrosion performance of the joint was assessed by immersing in 3.5% NaCl solution for different intervals of time and the corrosion rate was calculated. The joint has undergone severe corrosion attack compared with both the base materials (AZ31B and Al6063 alloys. The predominant corrosion mechanism behind the high corrosion rate of the joint was found to be high galvanic corrosion. From the results, it can be suggested that the severe corrosion of dissimilar Mg–Al joints must be considered as a valid input while designing structures intended to work in corroding environment.

  3. Fabrication and Characterization of Thermoelectric Fe2VAl Alloy Powders by Mechanical Alloying.

    Science.gov (United States)

    Lee, Chung-Hyo

    2015-01-01

    A mixture of elemental Fe50V25Al25 powders has been subjected to mechanical alloying (MA) at room temperature to prepare the Heusler Fe2VAl thermoelectric alloy. Fe2VAI alloy with a grain size of 90 nm can be obtained by MA of Fe50V25Al25 powders for 60 h and subsequently annealed at 700 degrees C. Consolidation of the MA powders was performed in a spark plasma sintering (SPS) machine using graphite dies up to 900-1000 degrees C under 60 MPa. The shrinkage of consolidated samples during SPS was significant at about 400 degrees C. X-ray diffraction data shows that the SPS compact from 60 h MA powders consolidated up to 900 degrees C consists of only nanocrystalline Fe2VAl alloy with a grain size of 200 nm.

  4. Synthesis of Al/Al sub 3 Ti two-phase alloys by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Srinivasan, S.; Chen, S.R.; Schwarz, R.B.

    1991-01-01

    We have mechanically alloyed mixtures of elemental powders to prepare fine-grain two-phase A1/A1{sub 3}Ti powders at the compositions A1-20at% Ti and Al-10at% Ti. Hexane was used to prevent agglomeration of the powder during MA. Carbon from the decomposition of the hexane was incorporated in the powder. It reacted with Ti to form a fine dispersion of carbides in the final hot-pressed compact. We consolidated the mechanically alloyed powders by hot-pressing. Yield strength and ductility were measured in compression. At 25{degree}C, the compressive yield strengths were 1.25 and 0.6 GPa for the A1-20at% Ti and Al-10at% Ti alloys, respectively. The ductility of the A1-10at% Ti alloy exceeded 20% for 25 < T < 500{degree}C. 25 refs., 6 figs.

  5. Role of alloying additions on the properties of Cu–Al–Mn shape memory alloys

    International Nuclear Information System (INIS)

    Dasgupta, Rupa; Jain, Ashish Kumar; Kumar, Pravir; Hussain, Shahadat; Pandey, Abhishek

    2015-01-01

    Highlights: • Cu based SMAs with high transition temperature could be made using LM route. • The properties depend on alloying composition. • Property characterisation establishes feasibility of making SMAs. - Abstract: The effect of alloying seven different elements [Zn, Si, Fe, Ni, Mg, Cr and Ti] on the microstructure, hardness, phase precipitation and transformation temperature in a Cu–12.5Al–5Mn alloy with a view to possible improvements as a result of these additions is the focus of the reported study. The base alloy has been chosen keeping in mind its ability to exhibit shape memory properties and improved ductility over other Cu-based SMAs. The objective was to ascertain changes or improvements attained due to the individual tertiary additions. The samples were prepared through liquid metallurgy route using pure copper, aluminum, manganese and the respective quaternary alloying elements in right quantities to weigh 1000 g of the alloy in total and were melted together. Samples from the cast alloys were subject to homogenisation treatment at 200 °C for 2 h in a muffle furnace and furnace cooled. Samples from the homogenised alloys were heated and held for 2 h at 920 °C followed by ice quenching to obtain the desired martensitic structure for shape memory behaviour. The alloys in the cast, homogenised and quenched conditions were metallographically polished to observe the martensitic phase formation mainly in quenched samples which is a pre requisite for exhibiting shape memory properties in these alloys. X-ray Diffraction studies were carried out on the cast and quenched samples using Cu Kα target; and the phases identified indicate martensitic phase precipitation; however in some cases the precipitation is incomplete. Differential Scanning Calorimetric [DSC] studies were carried out on quenched samples from room temperature to 600 °C maintaining a constant rate of 10 °C/min. Results indicate clear transformation peaks in all the samples which

  6. Applications of thermodynamic calculations to Mg alloy design: Mg-Sn based alloy development

    International Nuclear Information System (INIS)

    Jung, In-Ho; Park, Woo-Jin; Ahn, Sang Ho; Kang, Dae Hoon; Kim, Nack J.

    2007-01-01

    Recently an Mg-Sn based alloy system has been investigated actively in order to develop new magnesium alloys which have a stable structure and good mechanical properties at high temperatures. Thermodynamic modeling of the Mg-Al-Mn-Sb-Si-Sn-Zn system was performed based on available thermodynamic, phase equilibria and phase diagram data. Using the optimized database, the phase relationships of the Mg-Sn-Al-Zn alloys with additions of Si and Sb were calculated and compared with their experimental microstructures. It is shown that the calculated results are in good agreement with experimental microstructures, which proves the applicability of thermodynamic calculations for new Mg alloy design. All calculations were performed using FactSage thermochemical software. (orig.)

  7. Role of alloying additions on the properties of Cu–Al–Mn shape memory alloys

    Energy Technology Data Exchange (ETDEWEB)

    Dasgupta, Rupa, E-mail: rupadasgupta@ampri.res.in; Jain, Ashish Kumar; Kumar, Pravir; Hussain, Shahadat; Pandey, Abhishek

    2015-01-25

    Highlights: • Cu based SMAs with high transition temperature could be made using LM route. • The properties depend on alloying composition. • Property characterisation establishes feasibility of making SMAs. - Abstract: The effect of alloying seven different elements [Zn, Si, Fe, Ni, Mg, Cr and Ti] on the microstructure, hardness, phase precipitation and transformation temperature in a Cu–12.5Al–5Mn alloy with a view to possible improvements as a result of these additions is the focus of the reported study. The base alloy has been chosen keeping in mind its ability to exhibit shape memory properties and improved ductility over other Cu-based SMAs. The objective was to ascertain changes or improvements attained due to the individual tertiary additions. The samples were prepared through liquid metallurgy route using pure copper, aluminum, manganese and the respective quaternary alloying elements in right quantities to weigh 1000 g of the alloy in total and were melted together. Samples from the cast alloys were subject to homogenisation treatment at 200 °C for 2 h in a muffle furnace and furnace cooled. Samples from the homogenised alloys were heated and held for 2 h at 920 °C followed by ice quenching to obtain the desired martensitic structure for shape memory behaviour. The alloys in the cast, homogenised and quenched conditions were metallographically polished to observe the martensitic phase formation mainly in quenched samples which is a pre requisite for exhibiting shape memory properties in these alloys. X-ray Diffraction studies were carried out on the cast and quenched samples using Cu Kα target; and the phases identified indicate martensitic phase precipitation; however in some cases the precipitation is incomplete. Differential Scanning Calorimetric [DSC] studies were carried out on quenched samples from room temperature to 600 °C maintaining a constant rate of 10 °C/min. Results indicate clear transformation peaks in all the samples which

  8. 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)

  9. 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.

  10. Dispersoid reinforced alloy powder and method of making

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Iver E.; Terpstra, Robert L.

    2017-10-10

    A method of making dispersion-strengthened alloy particles involves melting an alloy having a corrosion and/or oxidation resistance-imparting alloying element, a dispersoid-forming element, and a matrix metal wherein the dispersoid-forming element exhibits a greater tendency to react with a reactive species acquired from an atomizing gas than does the alloying element. The melted alloy is atomized with the atomizing gas including the reactive species to form atomized particles so that the reactive species is (a) dissolved in solid solution to a depth below the surface of atomized particles and/or (b) reacted with the dispersoid-forming element to form dispersoids in the atomized particles to a depth below the surface of said atomized particles. The atomized alloy particles are solidified as solidified alloy particles or as a solidified deposit of alloy particles. Bodies made from the dispersion strengthened alloy particles, deposit thereof, exhibit enhanced fatigue and creep resistance and reduced wear as well as enhanced corrosion and/or oxidation resistance at high temperatures by virtue of the presence of the corrosion and/or oxidation resistance imparting alloying element in solid solution in the particle alloy matrix.

  11. Comparison of three Ni-Hard I alloys

    Energy Technology Data Exchange (ETDEWEB)

    Dogan, Omer N.; Hawk, Jeffrey A.; Rice, J. (Texaloy Foundry Co., Inc., Floresville, Texas)

    2004-09-01

    This report documents the results of an investigation which was undertaken to reveal the similarities and differences in the mechanical properties and microstructural characteristics of three Ni-Hard I alloys. One alloy (B1) is ASTM A532 class IA Ni-Hard containing 4.2 wt. pct. Ni. The second alloy (B2) is similar to B1 but higher in Cr, Si, and Mo. The third alloy (T1) also falls in the same ASTM specification, but it contains 3.3 wt. pct. Ni. The alloys were evaluated in both as-cast and stress-relieved conditions except for B2, which was evaluated in the stress-relieved condition only. While the matrix of the high Ni alloys is composed of austenite and martensite in both conditions, the matrix of the low Ni alloy consists of a considerable amount of bainite, in addition to the martensite and the retained austenite in as cast condition, and primarily bainite, with some retained austenite, in the stress relieved condition. It was found that the stress relieving treatment does not change the tensile strength of the high Ni alloy. Both the as cast and stress relieved high Ni alloys had a tensile strength of about 350 MPa. On the other hand, the tensile strength of the low Ni alloy increased from 340 MPa to 452 MPa with the stress relieving treatment. There was no significant difference in the wear resistance of these alloys in both as-cast and stressrelieved conditions.

  12. Dispersoid reinforced alloy powder and method of making

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Iver E.; Terpstra, Robert L.

    2017-12-05

    A method of making dispersion-strengthened alloy particles involves melting an alloy having a corrosion and/or oxidation resistance-imparting alloying element, a dispersoid-forming element, and a matrix metal wherein the dispersoid-forming element exhibits a greater tendency to react with a reactive species acquired from an atomizing gas than does the alloying element. The melted alloy is atomized with the atomizing gas including the reactive species to form atomized particles so that the reactive species is (a) dissolved in solid solution to a depth below the surface of atomized particles and/or (b) reacted with the dispersoid-forming element to form dispersoids in the atomized particles to a depth below the surface of said atomized particles. The atomized alloy particles are solidified as solidified alloy particles or as a solidified deposit of alloy particles. Bodies made from the dispersion strengthened alloy particles, deposit thereof, exhibit enhanced fatigue and creep resistance and reduced wear as well as enhanced corrosion and/or oxidation resistance at high temperatures by virtue of the presence of the corrosion and/or oxidation resistance imparting alloying element in solid solution in the particle alloy matrix.

  13. Creep behavior of Ti3Al-Nb intermetallic alloys

    International Nuclear Information System (INIS)

    Yu, T.H.; Yue, W.J.; Koo, C.H.

    1997-01-01

    It is well known that Ti 3 Al-Nb alloys are potential materials for aerospace applications. The creep property is an important consideration when materials are used at high temperature. In this article, the effect of microstructure of Ti-25Al-10Nb alloy on the creep property was investigated, and the creep property of Ti-25Al-10Nb alloy modified by small addition of silicon 0.2 at.% or carbon 0.1 at.% was observed. The alloy with the addition of molybdenum to replace part of niobium 2 at.% was also studied. The experimental results show that the furnace-cooled Ti-25Al-10Nb alloy has superior creep resistance to the air-cooled Ti-25Al-10Nb alloy at 200 MPa, but exhibits poor creep resistance at 250 MPa or above. Small addition of silicon to the Ti-25Al-10Nb alloy may increase creep resistance. Small addition of carbon to the Ti-25Al-10Nb alloy may reduce creep resistance but raise rupture strain. Molybdenum is the most effective alloying element to increase creep resistance for the Ti-25Al-10Nb alloy. The creep mechanism of Ti-25Al-10Nb alloy is governed by dislocation climb. (orig.)

  14. The corrosion and passivity of sputtered Mg–Ti alloys

    International Nuclear Information System (INIS)

    Song, Guang-Ling; Unocic, Kinga A.; Meyer, Harry; Cakmak, Ercan; Brady, Michael P.; Gannon, Paul E.; Himmer, Phil; Andrews, Quinn

    2016-01-01

    Highlights: • A supersaturated single phase Mg–Ti alloy can be obtained by magnetron sputtering. • The anodic dissolution of Mg–Ti alloy is inhibited by Ti addition. • The alloy becomes passive when Ti content is high and the alloy has become Ti based. • The formation of a continuous thin passive film is responsible for the passivation of the alloy. - Abstract: This study explored the possibility of forming a “stainless” Mg–Ti alloy. The electrochemical behavior of magnetron-sputtered Mg–Ti alloys was measured in a NaCl solution, and the surface films on the alloys were examined by XPS, SEM and TEM. Increased corrosion resistance was observed with increased Ti content in the sputtered Mg–Ti alloys, but passive-like behavior was not reached until the Ti level (atomic %) was higher than the Mg level. The surface film that formed on sputtered Mg–Ti based alloys in NaCl solution was thick, discontinuous and non-protective, whereas a thin, continuous and protective Mg and Ti oxide film was formed on a sputtered Ti–Mg based alloy.

  15. Mechanical and irradiation properties of zirconium alloys irradiated in HANARO

    International Nuclear Information System (INIS)

    Kwon, Oh Hyun; Eom, Kyong Bo; Kim, Jae Ik; Suh, Jung Min; Jeon, Kyeong Lak

    2011-01-01

    These experimental studies are carried out to build a database for analyzing fuel performance in nuclear power plants. In particular, this study focuses on the mechanical and irradiation properties of three kinds of zirconium alloy (Alloy A, Alloy B and Alloy C) irradiated in the HANARO (High-flux Advanced Neutron Application Reactor), one of the leading multipurpose research reactors in the world. Yield strength and ultimate tensile strength were measured to determine the mechanical properties before and after irradiation, while irradiation growth was measured for the irradiation properties. The samples for irradiation testing are classified by texture. For the irradiation condition, all samples were wrapped into the capsule (07M-13N) and irradiated in the HANARO for about 100 days (E > 1.0 MeV, 1.1 10 21 n/cm 2 ). These tests and results indicate that the mechanical properties of zirconium alloys are similar whether unirradiated or irradiated. Alloy B has shown the highest yield strength and tensile strength properties compared to other alloys in irradiated condition. Even though each of the zirconium alloys has a different alloying content, this content does not seem to affect the mechanical properties under an unirradiated condition and low fluence. And all the alloys have shown the tendency to increase in yield strength and ultimate tensile strength. Transverse specimens of each of the zirconium alloys have a slightly lower irradiation growth tendency than longitudinal specimens. However, for clear analysis of texture effects, further testing under higher irradiation conditions is needed

  16. Clinical evaluations of cast gold alloy, machinable zirconia, and semiprecious alloy crowns: A multicenter study.

    Science.gov (United States)

    Park, Ji-Man; Hong, Yong-Shin; Park, Eun-Jin; Heo, Seong-Joo; Oh, Namsik

    2016-06-01

    Few studies have compared the marginal and internal fits of crowns fabricated from machinable palladium-silver-indium (Pd-Ag-In) semiprecious metal alloy. The purpose of this clinical study was to evaluate and compare the marginal and internal fits of machined Pd-Ag-In alloy, zirconia, and cast gold crowns. A prospective clinical trial was performed on 35 participants and 52 abutment teeth at 2 centers. Individuals requiring prosthetic restorations were treated with gold alloy or zirconia crowns (2 control groups) or Pd-Ag-In alloy crowns (experimental group). A replica technique was used to evaluate the marginal and internal fits. The buccolingual and mesiodistal cross-sections were measured, and a noninferiority comparison was conducted. The mean marginal gaps were 68.2 μm for the gold crowns, 75.4 μm for the zirconia crowns, and 76.9 μm for the Pd-Ag-In alloy crowns. In the 5 cross-sections other than the distal cross-section, the 2-sided 95% confidence limits for the differences between the Pd-Ag-In alloy crowns and the 2 control groups were not larger than the 25-μm noninferiority margin. The control groups displayed smaller internal gaps in the line angle and occlusal spaces compared with the Pd-Ag-In crown group. The marginal gaps of machinable Pd-Ag-In alloy crowns did not meet the noninferiority criterion in the distal margin compared with zirconia and gold alloy crowns. Nonetheless, all 3 crowns had clinically applicable precision. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  17. Influence of impurities and ion surface alloying on the corrosion resistance of E110 alloy

    International Nuclear Information System (INIS)

    Kalin, B. A.; Volkov, N. V.; Valikov, R. A.; Novikov, V. V.; Markelov, V. A.; Pimenov, Yu. V.

    2013-01-01

    The corrosion resistance of zirconium alloys depends on their structural-phase state, the type of core coolant and operating factors. The formation of a protective oxide film on the zirconium alloys is sensitive to the content of impurity atoms present in the charge base of alloys and accumulating in them in the manufacture of products. The impurity composition of the initial zirconium is determined by the method of its manufacture and generally remains unchanged in the products, deter-mining their properties, including their corrosion resistance. An increased content of impurities (C, N, Al, Mo, Fe) both individually and in their combination negatively affects the corrosion resistance of zirconium and its alloys. One of the potentially effective methods to increase the protective properties of oxide films on zirconium alloys is a surface alloying using the regime of mixing the atoms of a film, preliminarily coated on the surface, and the atoms of a target. This method makes it possible to form a given structural-phase state in the thin surface layer with unique physicochemical properties and thus to in-crease the corrosion resistance and wear resistance of fuel claddings. In this context, the object of investigation was samples of cladding tubes from alloy E110 with various content of impurity elements (nitrogen, aluminum, and carbon) with the aim to reduce the negative influence of impurities on the corrosion resistance by changing the structural-phase state of the surface layer of fuel claddings and fuel assembly components with alloying in the regime of ion mixing of atoms

  18. Two-dimensional model of laser alloying of binary alloy powder with interval of melting temperature

    Science.gov (United States)

    Knyzeva, A. G.; Sharkeev, Yu. P.

    2017-10-01

    The paper contains two-dimensional model of laser beam melting of powders from binary alloy. The model takes into consideration the melting of alloy in some temperature interval between solidus and liquidus temperatures. The external source corresponds to laser beam with energy density distributed by Gauss law. The source moves along the treated surface according to given trajectory. The model allows investigating the temperature distribution and thickness of powder layer depending on technological parameters.

  19. Grain Refinement of Permanent Mold Cast Copper Base Alloys

    Energy Technology Data Exchange (ETDEWEB)

    M.Sadayappan; J.P.Thomson; M.Elboujdaini; G.Ping Gu; M. Sahoo

    2005-04-01

    Grain refinement is a well established process for many cast and wrought alloys. The mechanical properties of various alloys could be enhanced by reducing the grain size. Refinement is also known to improve casting characteristics such as fluidity and hot tearing. Grain refinement of copper-base alloys is not widely used, especially in sand casting process. However, in permanent mold casting of copper alloys it is now common to use grain refinement to counteract the problem of severe hot tearing which also improves the pressure tightness of plumbing components. The mechanism of grain refinement in copper-base alloys is not well understood. The issues to be studied include the effect of minor alloy additions on the microstructure, their interaction with the grain refiner, effect of cooling rate, and loss of grain refinement (fading). In this investigation, efforts were made to explore and understand grain refinement of copper alloys, especially in permanent mold casting conditions.

  20. Method of treating Ti--Nb--Zr--Ta superconducting alloys

    International Nuclear Information System (INIS)

    Horiuchi, T.; Monju, Y.; Tatara, I.; Nagai, N.; Hisata, M.; Matsumoto, K.

    1975-01-01

    A superconducting alloy is formulated from 10 to 50 at. percent Ti, 20 to 50 at. percent Nb, 10 to 40 at. percent Zr, and 5 to 12 at. percent Ta. A Ti--Nb--Zr--Ta superconducting alloy with a fine, non-homogeneous structure is obtained by forming a β solid solution of Ti--Nb--Zr--Ta alloy by heating to a temperature within the β solid solution range, cooling, and then cold working the heated alloy. The cold worked alloy is heated to a temperature within the (β' + β'') alloy to maintain the peritectoid structure, cold worked, then heated to a temperature within the eutectoid range to form a multiphase alloy structure and then cooled and finally cold worked. (U.S.)

  1. In vitro and in vivo studies on biodegradable magnesium alloy

    Directory of Open Access Journals (Sweden)

    Lida Hou

    2014-10-01

    Full Text Available The microstructure, mechanical property, electrochemical behavior and biocompatibility of magnesium alloy (BioDe MSM™ were studied in the present work. The experimental results demonstrated that grain refining induced by extrusion improves the alloy strength significantly from 162 MPa for the as-cast alloy to 241 MPa for the as-extruded one. The anticorrosion properties of the as-extruded alloy also increased. Furthermore, the hemolysis ratio was decreased from 4.7% for the as-cast alloy to 2.9% for the as-extruded one, both below 5%. BioDe MSM™ alloy shows good biocompatibility after being implanted into the dorsal muscle and the femoral shaft of the New Zealand rabbit, respectively, and there are no abnormalities after short-term implantation. In vivo observation indicated that the corrosion rate of this alloy varies with different implantation positions, with higher degradation rate in the femur than in the muscle.

  2. Casting Characteristics of High Cerium Content Aluminum Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, D; Rios, O R; Sims, Z C; McCall, S K; Ott, R T

    2017-09-05

    This paper compares the castability of the near eutectic aluminum-cerium alloy system to the aluminum-silicon and aluminum-copper systems. The alloys are compared based on die filling capability, feeding characteristics and tendency to hot tear in both sand cast and permanent mold applications. The castability ranking of the binary Al–Ce systems is as good as the aluminum-silicon system with some deterioration as additional alloying elements are added. In alloy systems that use cerium in combination with common aluminum alloying elements such as silicon, magnesium and/or copper, the casting characteristics are generally better than the aluminum-copper system. In general, production systems for melting, de-gassing and other processing of aluminum-silicon or aluminum-copper alloys can be used without modification for conventional casting of aluminum-cerium alloys.

  3. Copper-Silver Alloy Depositions Using Thermionic Vacuum ARC (TVA)

    International Nuclear Information System (INIS)

    Akan, T.

    2004-01-01

    TVA is a plasma source generating pure metal vapor plasma and consists of a heated cathode emitting thermo electrons and an anode containing material to be evaporated. We used Cu and Ag pieces as anode materials and produced their alloys by electron bombarding. Cu-Ag alloys in various mass ratios were prepared by using the TVA and the TVA discharges were generated in the vapors of these alloys. The volt-ampere characteristics of the TVA discharges generated in the vapors of these alloys were investigated with respect to the ratio of Ag in the Cu-Ag alloy. Cu-Ag alloy thin films with various mass ratios were deposited onto the glass substrates by using their TVA discharges. The ratios of Cu and Ag in the thin Cu-Ag alloy films were found using scanning electron microscope-energy dispersive xray (SEM-EDX) microanalyses

  4. Microstructural characterization of a rapidly solidified Al-5 Sb alloy

    International Nuclear Information System (INIS)

    Zhang Zhonghua; Bian Xiufang; Wang Yan

    2003-01-01

    In the present work, the microstructure of a melt-spun Al-5 Sb alloy has been characterized using X-ray diffraction and transmission electron microscopy. The phases present in the melt-spun Al-5 Sb alloy were determined to be the equilibrium α-Al and AlSb, identical to those in the ingot-cast alloy. The microstructure of the melt-spun Al-5 Sb alloy is composed of primary AlSb phase embedded in the matrix comprising α-Al cells with intercellular nanoscale AlSb particles, different from that of the ingot-cast alloy composed of the primary AlSb phase within an α-Al/AlSb eutectic matrix. Rapid solidification has a marked effect on the morphology, size and distribution of the primary AlSb phase in the melt-spun Al-5 Sb alloy. Furthermore, some orientation relationships were determined in the melt-spun alloy

  5. Molecular dynamics study of atomic displacements in disordered solid alloys

    Science.gov (United States)

    Puzyrev, Yevgeniy S.

    The effects of atomic displacements on the energetics of alloys plays important role in the determining the properties of alloys. We studied the atomic displacements in disordered solid alloys using molecular dynamics and Monte-Carlo methods. The diffuse scattering of pure materials, copper, gold, nickel, and palladium was calculated. The experimental data for pure Cu was obtained from diffuse scattering intensity of synchrotron x-ray radiation. The comparison showed the advantages of molecular dynamics method for calculating the atomic displacements in solid alloys. The individual nearest neighbor separations were calculated for Cu 50Au50 alloy and compared to the result of XAFS experiment. The molecular dynamics method provided theoretical predictions of nearest neighbor pair separations in other binary alloys, Cu-Pd and Cu-Al for wide range of the concentrations. We also experimentally recovered the diffuse scattering maps for the Cu47.3Au52.7 and Cu85.2Al14.8 alloy.

  6. Mechanical properties of fine-grained sintered molybdenum alloy processed by mechanical alloying

    International Nuclear Information System (INIS)

    Takida, T.; Kurishita, H.; Mabuchi, M.; Igarashi, T.; Doi, Y.; Nagae, T.

    2001-01-01

    In order to improve the low-temperature toughness and room- and high-temperature strengths of molybdenum (Mo), sintered Mo alloys with fine grains and fine, dispersed particles were fabricated by hot isostatic pressing of spark plasma sintering with mechanically alloyed powder of Mo and 0.8 mol % ZrC or TaC (designated ZRC08 and TAC08). The fabricated Mo alloys showed no significant grain growth even after annealing at 2470 K for 3.6 ks due to the pinning effect of the particles against grain boundary migration. For the Mo alloys the impact three-point bending test was performed at 270 to 470 K and at 5 m s -1 and the static tensile test at 300 to 1970 K and at 4.2 x 10 - % to 8.3 x 10-2 s -1 . The fabricated alloys exhibited lower ductile-to brittle transition temperatures and higher tensile strengths up to 1770 K than fully recrystallized pure Mo. In particular, TAC08 was superior in low-temperature toughness and ZRC08 was superior in room- and high-temperature strengths. Furthermore, ZRC08 showed a large elongation of 551 % at 1770 K. These excellent mechanical properties of the fabricated Mo alloys are attributable to the fine-grained microstructure and grain-boundary strengthening by the fine particles. (author)

  7. 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.

  8. Fabrication and Magnetic Properties of Co₂MnAl Heusler Alloys by Mechanical Alloying.

    Science.gov (United States)

    Lee, Chung-Hyo

    2018-02-01

    We have applied mechanical alloying (MA) to produce nanocrystalline Co2MnAl Heusler alloys using a mixture of elemental Co50Mn25Al25 powders. An optimal milling and heat treatment conditions to obtain a Co2MnAl Heusler phase with fine microstructure were investigated by X-ray diffraction, differential scanning calorimeter and vibrating sample magnetometer measurements. α-(Co, Mn, Al) FCC phases coupled with amorphous phase are obtained after 3 hours of MA without any evidence for the formation of Co2MnAl alloys. On the other hand, a Co2MnAl Heusler alloys can be obtained by the heat treatment of all MA samples up to 650 °C. X-ray diffraction result shows that the average grain size of Co2MnAl Heusler alloys prepared by MA for 5 h and heat treatment is in the range of 95 nm. The saturation magnetization of MA powders decreases with MA time due to the magnetic dilution by alloying with nonmagnetic Mn and Al elements. The magnetic hardening due to the reduction of the grain size with ball milling is also observed. However, the saturation magnetization of MA powders after heat treatment increases with MA time and reaches to a maximum value of 105 emu/g after 5 h of MA. It can be also seen that the coercivity of 5 h MA sample annealed at 650 °C is fairly low value of 25 Oe.

  9. 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.

  10. Thermal Plasma Spheroidization of High-Nitrogen Stainless Steel Powder Alloys Synthesized by Mechanical Alloying

    Science.gov (United States)

    Razumov, Nikolay G.; Popovich, Anatoly A.; Wang, QingSheng

    2018-03-01

    This paper presents the results of experimental studies on the treatment of Fe-23Cr-11Mn-1N high-nitrogen stainless steel powder alloys, synthesized by the mechanical alloying (MA) of elemental powders in the flow of a thermal plasma. Fe-23Cr-11Mn-1N high-nitrogen stainless steel powder alloys were prepared by MA in the attritor under an argon atmosphere. For spheroidization of Fe-23Cr-11Mn-1N high-nitrogen stainless steel powder alloys, the TekSphero 15 plant manufactured by Tekna Plasma Systems Inc was used. The studies have shown the possibility of obtaining Fe-23Cr-11Mn-1N high-nitrogen spherical powders steel alloys from the powder obtained by MA. According to the results of a series of experiments, it was found that the results of plasma spheroidization of powders essentially depend on the size of the fraction due to some difference in the particle shape and flowability, and on the gas regime of the plasma torch. It is established that during the plasma spheroidization process, some of the nitrogen leaves the alloy. The loss rate of nitrogen depends on the size of the initial particles.

  11. 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.

  12. Laser alloyed Al-Ni-Fe coatings

    CSIR Research Space (South Africa)

    Pityana, SL

    2008-10-01

    Full Text Available The aim of this work was to produce crack-free thin surface layers consisting of binary (Al-Ni, Al-Fe) and ternary (Al-Ni-Fe) intermetallic phases by means of a high power laser beam. The laser surface alloying was carried out by melting Fe and Ni...

  13. R-HPDC of magnesium alloys

    CSIR Research Space (South Africa)

    Curle, UA

    2013-01-01

    Full Text Available different magnesium alloys (AM50A, AM60B, AZ91D) in a first attempt. All as-cast microstructures are characterised more by rosette shaped globules of the primary-(Mg) phase together with Mg(sub17)Al(sub12) as evidence of nonequilibrium cooling rates. Surface...

  14. Design of Refractory High-Entropy Alloys

    Science.gov (United States)

    Gao, M. C.; Carney, C. S.; Doğan, Ö. N.; Jablonksi, P. D.; Hawk, J. A.; Alman, D. E.

    2015-11-01

    This report presents a design methodology for refractory high-entropy alloys with a body-centered cubic (bcc) structure using select empirical parameters (i.e., enthalpy of mixing, atomic size difference, Ω-parameter, and electronegativity difference) and CALPHAD approach. Sixteen alloys in equimolar compositions ranging from quinary to ennead systems were designed with experimental verification studies performed on two alloys using x-ray diffraction, energy-dispersive spectroscopy, and scanning electron microscopy. Two bcc phases were identified in the as-cast HfMoNbTaTiVZr, whereas multiple phases formed in the as-cast HfMoNbTaTiVWZr. Observed elemental segregation in the alloys qualitatively agrees with CALPHAD prediction. Comparisons of the thermodynamic mixing properties for liquid and bcc phases using the Miedema model and CALPHAD are presented. This study demonstrates that CALPHAD is more effective in predicting HEA formation than empirical parameters, and new single bcc HEAs are suggested: HfMoNbTiZr, HfMoTaTiZr, NbTaTiVZr, HfMoNbTaTiZr, HfMoTaTiVZr, and MoNbTaTiVZr.

  15. Synthesis of ternary nitrides by mechanochemical alloying

    DEFF Research Database (Denmark)

    Jacobsen, C.J.H.; Zhu, J.J.; Lindelov, H.

    2002-01-01

    nitrides by mechanochemical alloying of a binary transition metal nitride (MxN) with an elemental transition metal. In this way, we have been able to prepare Fe3Mo3N and Co3Mo3N by ball-milling of Mo2N with Fe and Co, respectively. The transformation sequence from the starting materials ( the binary...

  16. Evaluation of ultraliner PVC alloy pipeliner.

    Science.gov (United States)

    2013-12-01

    In an effort to evaluate promising pipe lining techniques, the Agency installed two Ultraliner : PVC Alloy Pipeliners in the town of Barton, Vermont in May of 2003; one in an 18 : - : inch (450 : mm nominal) reinforced concrete pipe (RCP) and one in ...

  17. Corrosion of carbon-alloyed iron aluminides

    Indian Academy of Sciences (India)

    Unknown

    MS received 22 May 2000; revised 17 August 2000. Abstract. The corrosion behaviour of two carbon-alloyed intermetallics of composition Fe–28⋅1Al–2⋅1C and. Fe–27⋅5Al–3⋅7C has been studied and compared with that of binary intermetallics. Potentiodynamic polariza- tion studies indicated that the intermetallics ...

  18. Mechanical behaviour of aluminium–lithium alloys

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    response to the crying need for lightweight alloys for use as structurals in aerospace applications. .... bined with the advantages of reduced density, enhanced modulus and precipitation hardening provided by 2 wt. ..... Plastic deformation is accompanied by shearing of δ precipitates, which in turn results in co-planar slip, a ...

  19. Discontinuous precipitation in copper base alloys

    Indian Academy of Sciences (India)

    Discontinuous precipitation (DP) is associated with grain boundary migration in the wake of which alternate plates of the precipitate and the depleted matrix form. Some copper base alloys show ... 100 > ± 0.1, DP is observed. This criterion points to diffusional coherency strain theory to be the operative mechanism for DP.

  20. Reduction in Defect Content of ODS Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ritherdon, J

    2001-05-15

    The work detailed within this report is a continuation of earlier work carried out under contract number 1DX-SY382V. The earlier work comprises a literature review of the sources and types of defects found principally in Fe-based ODS alloys as well as experimental work designed to identify defects in the prototype ODS-Fe{sub 3}Al alloy, deduce their origins and to recommend methods of defect reduction. The present work is an extension of the experimental work already reported and concentrates on means of reduction of defects already identified rather than the search for new defect types. This report also includes results gathered during powder separation trials, conducted by the University of Groningen, Netherlands and coordinated by the University of Liverpool, involving the separation of different metallic powders in terms of their differing densities. The scope and objectives of the present work were laid out in the technical proposal ''Reduction in Defect Content in ODS Alloys-III''. All the work proposed in the ''Statement of Work'' section of the technical proposal has been carried out and all work extra to the ''Statement of Work'' falls within the context of an ODS-Fe{sub 3}Al alloy of improved overall quality and potential creep performance in the consolidated form. The outturn of the experimental work performed is reported in the following sections.