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Sample records for cu alloy anode

  1. Development of Cu alloy anode and separator coated with Al-Ni intermetallic compound

    SciTech Connect

    Toyokura, K.; Hoshino, K.; Yamamoto, M.

    1996-12-31

    Anode made of Cu alloy and separator coated with Al-Ni intermetallic compound have been developed for VCFC. Anode of Ni alloy is usually used. However, the alternative of cost lower than Ni alloy anode should be needed, because Ni is expensive. Cu is attractive as an anode material for VCFC because it is inexpensive and electrochemically noble. However, the creep resistance of Cu is not sufficient, compared with Ni alloy. In this study, strengthening due to oxide-dispersed microstructure has been developed in Cu-Ni-Al alloy with the two-step sintering process. A wet-seal technique has been widely applied for gas-sealing and supporting of electrolyte in MCFC. Since the wet-seal area is exposed to a severe corrosive environment, corrosion resistance of material for wet sealing is related with the cell performance. Al-Ni plating with post-heat treating for stainless steel has been investigated. Stainless steel substrate was plated with Al after being coated with Ni, then heat-treated at 750 {degrees}C for 1 hour in Ar gas atmosphere. Due to the treatment, Al-Ni intermetallic compound ( mainly Al3Ni2 ) layer is formed on stainless steel surface. The long-term immersion test was carried out till 14,500 hours in 62 mol% Li{sub 2}CO{sub 3}-38 mol% K{sub 2}CO{sub 3} at 650 {degrees}C under air-30%CO{sub 2} atmosphere, for the purpose of evaluating the corrosion resistance and thermal stability of Al-Ni intermetallic compound layer in actual generating with VCFC.

  2. A NiFeCu alloy anode catalyst for direct-methane solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Zhu, Huaiyu; Yang, Guangming; Park, Hee Jung; Jung, Doh Won; Kwak, Chan; Shao, Zongping

    2014-07-01

    In this study, a new anode catalyst based on a NiFeCu alloy is investigated for use in direct-methane solid oxide fuel cells (SOFCs). The influence of the conductive copper introduced into the anode catalyst layer on the performance of the SOFCs is systematically studied. The catalytic activity for partial oxidation of methane and coking resistance tests are proposed with various anode catalyst layer materials prepared using different methods, including glycine nitrate process (GNP), physical mixing (PM) and impregnation (IMP). The surface conductivity tests indicate that the conductivities of the NiFe-ZrO2/Cu (PM) and NiFe-ZrO2/Cu (IMP) catalysts are considerably greater than that of NiFe-ZrO2/Cu (GNP), which is consistent with the SEM results. Among the three preparation methods, the cell containing the NiFe-ZrO2/Cu (IMP) catalyst layer performs best on CH4-O2 fuel, especially under reduced temperatures, because the coking resistance should be considered in real fuel cell conditions. The cell containing the NiFe-ZrO2/Cu (IMP) catalyst layer also delivers an excellent operational stability using CH4-O2 fuel for 100 h without any signs of decay. In summary, this work provides new alternative anode catalytic materials to accelerate the commercialization of SOFC technology.

  3. Performance of the nano-structured Cu-Ni (alloy) -CeO2 anode for solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Liu, Minquan; Wang, Shaolan; Chen, Ting; Yuan, Chun; Zhou, Yucun; Wang, Shaorong; Huang, Jun

    2015-01-01

    In this work, copper and nickel oxides (CuO-NiO) powders with various mole ratios were synthesized by the glycine nitrate process (GNP) and the Cu-Ni alloy was obtained by reducing the CuO-NiO powders at 600 °C for 0.75 h. Furthermore, Cu1-xNix (alloy) -CeO2 impregnated YSZ anodes were fabricated by the impregnation method and the optimized anode composition was evaluated. It was found that the optimized mole ratio of Cu:Ni was 5:5, while the weight ratio of Cu-Ni alloy to CeO2 was 3:1. Additionally, impregnated anode with 40 wt % loading of Cu0.5Ni0.5 (alloy)-CeO2 exhibited the best performance and the polarization resistance of such anode was only 0.097, 0.115, 0.145 and 0.212 Ω cm2 at 750, 700, 650 and 600 °C, respectively. Finally, the performance of the optimized anode in methane (CH4) was investigated and the carbon deposition is greatly suppressed compared to the Ni-based anode.

  4. Acid blue 29 decolorization and mineralization by anodic oxidation with a cold gas spray synthesized Sn-Cu-Sb alloy anode.

    PubMed

    do Vale-Júnior, Edilson; Dosta, Sergi; Cano, Irene Garcia; Guilemany, Josep Maria; Garcia-Segura, Sergi; Martínez-Huitle, Carlos Alberto

    2016-04-01

    The elevated cost of anodic materials used in the anodic oxidation for water treatment of effluents undermines the real application of these technologies. The study of novel alternative materials more affordable is required. In this work, we report the application of Sn-Cu-Sb alloys as cheap anodic material to decolorize azo dye Acid Blue 29 solutions. These anodes have been synthesized by cold gas spray technologies. Almost complete decolorization and COD abatement were attained after 300 and 600 min of electrochemical treatment, respectively. The influence of several variables such as supporting electrolyte, pH, current density and initial pollutant concentration has been investigated. Furthermore, the release and evolution of by-products was followed by HPLC to better understand the oxidative power of Sn-Cu-Sb electrodes.

  5. Electrochemical properties of melt spun Si-Cu-Ti-Zr-Ni alloy powders for the anode of Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Bae, Seong Min; Sohn, Keun Yong; Park, Won-Wook

    2014-07-01

    The Si-Cu-Ti-Zr-Ni alloys of various compositions were prepared using arc-melting under an argon atmosphere, and the alloys were re-melted several times to ensure chemical homogeneity. The alloyed ingots were melt-spun to produce rapidly solidified ribbons under vacuum in order to prevent oxidation. Finely dispersed silicon particles 50-100 nm in diameter mainly consisting of Cu3Si, NiSi2 and TiSi2 phases were formed in the matrices. The alloy ribbons were then fragmented using ball-milling to produce powders. In order to evaluate the electrochemical properties of the alloys, anode electrodes were fabricated by mixing the active alloy materials (80 wt. %) with Ketjenblack® (2 wt. %) as a conductive material and polyamide imide (PAI, 8 wt. %) binder, and the mixtures were dissolved in N-methyl-2-pyrrolidinone (NMP) and SFG6 (10 wt. %). The anode performances of Si-Cu-Ti-Zr-Ni alloy cells were measured in the range 0.01-1.5 V (versus Li/Li+). The results showed that the Si68(Cu47Ti34Zr11Ni8)32 alloy ribbons had the highest specific discharge capacities, and the Si68(Cu40Ti40Zr10Ni10)32 alloy ribbons had relatively stable electrochemical properties and cycle performances due to the very fine microstructure including partially distributed amorphous phase. The matrix phases of the Si-Cu-Ti-Zr-Ni alloy ribbons effectively accommodated the change in Si particle volume during cycling.

  6. Influence of the heat treatment condition of alloy AlCu4Mg1 on the microstructure and properties of anodic oxide layers

    NASA Astrophysics Data System (ADS)

    Morgenstern, R.; Dietrich, D.; Sieber, M.; Lampke, T.

    2017-03-01

    Due to their outstanding specific mechanical properties, high-strength, age-hardenable aluminum alloys offer a high potential for lightweight security-related applications. However, the use of copper-alloyed aluminum is limited because of their susceptibility to selective corrosion and their low wear resistance. These restrictions can be overcome and new applications can be opened up by the generation of protective anodic aluminum oxide layers. In contrast to the anodic oxidation of unalloyed aluminum, oxide layers produced on copper-rich alloys exhibit a significantly more complex pore structure. It is the aim of the investigation to identify the influence of microstructural parameters such as size and distribution of the strengthening precipitations on the coating microstructure. The aluminum alloy EN AW-2024 (AlCu4Mg1) in different heat treatment conditions serves as substrate material. The influence of the strengthening precipitations’ size and distribution on the development of the pore structure is investigated by the use of high-resolution scanning electron microscopy. Integral coating properties are characterized by non-destructive and light-microscopic thickness measurements and instrumented indentation tests.

  7. An anodic dissolution-based mechanism for the rapid cracking, ``pre-exposure`` phenomenon demonstrated by Al-Li-Cu alloys

    SciTech Connect

    Buchheit, R.G.; Wall, F.D.; Stoner, G.E.; Moran, J.P.

    1993-12-31

    Al-Li-Cu alloys have been observed to fail in less than 24 hours after removal from a one week immersion in aerated 3.5 w/o NaCl solution. Anodic dissolution-based mechanisms proposed previously for this phenomenon have been amended based on further experiment and characterization of the rapid cracking process. Amendments are based on studies of the relative electrochemical behavior of the microstructural elements in the subgrain boundary region, time to failure SCC testing in a simulated crack solution, evolution of crack potential and pH with time, fractographic examination of failed samples, and X-ray diffraction of films passivating crack walls. Results suggest that an active path exists along subgrain boundaries that is comprised of the highly reactive T{sub 1} (Al{sub 2}CuLi) precipitate phase and a solute depleted zone that does not readily passivate when exposed to the crack environment. The matrix phase does appear to passivate in the crack environment thereby confining the crack to the subgrain boundary region. This active path is enabled when cracks are isolated from a bulk environment, but is disabled otherwise. Potential and pH conditions required for cracking are discussed as is the formation of a hydrotalcite Li{sub 2}[Al{sub 2}(OH){sub 6}]{sub 2}{center_dot}CO{sub 3}{center_dot}3H{sub 2}O film that appears to be responsible for passivating crack walls.

  8. Cu-Ni-Fe anodes having improved microstructure

    DOEpatents

    Bergsma, S. Craig; Brown, Craig W.

    2004-04-20

    A method of producing aluminum in a low temperature electrolytic cell containing alumina dissolved in an electrolyte. The method comprises the steps of providing a molten electrolyte having alumina dissolved therein in an electrolytic cell containing the electrolyte. A non-consumable anode and cathode is disposed in the electrolyte, the anode comprised of Cu--Ni--Fe alloys having single metallurgical phase. Electric current is passed from the anode, through the electrolyte to the cathode thereby depositing aluminum on the cathode, and molten aluminum is collected from the cathode.

  9. Synergistic effects of Ni 1- xCo x-YSZ and Ni 1- xCu x-YSZ alloyed cermet SOFC anodes for oxidation of hydrogen and methane fuels containing H 2S

    NASA Astrophysics Data System (ADS)

    Grgicak, Catherine M.; Pakulska, Malgosia M.; O'Brien, Julie S.; Giorgi, Javier B.

    Preparation and performance of bimetallic Ni (1- x)Co x-YSZ and Ni (1- x)Cu x-YSZ anodes were tested to overcome common deficiencies of carbon and sulfur poisoning in SOFCs. Ni 1- xCo xO-YSZ and Ni (1- x)Cu xO-YSZ precursors were synthesized via co-precipitation of their respective chlorides. Single cell solid oxide fuel cells of these bimetallic anodes were tested in H 2, CH 4, and H 2S/CH 4 fuel mixtures. Addition of Cu 2+ into the NiO lattice resulted in large metal particle sizes and decreased SOFC performance. Addition of Co 2+ into the NiO lattice to form Ni 0.92Co 0.08O-YSZ anode precursor produced a cermet with a large BET surface area and active metal surface area, thus increasing the rate of hydrogen oxidation for this sample. The performance of both bimetallics was found to quickly degrade in dry CH 4 due to carbon deposition and lifting of the anode from the electrolyte. However, Ni 0.69Co 0.31-YSZ showed superior activity in a 10% (v/v) H 2S/CH 4 fuel mixture, surpassing performance with H 2 fuel, thereby demonstrating the exciting prospect of using sulfidated Ni (1- x)Co x-YSZ as SOFC anodes in sulfur containing methane streams. The active anode becomes a sulfidated alloy (Ni-Co-S) under operating conditions. This anode showed enhanced performance, which surpassed those of sulfidated Ni and Co anodes, thereby suggesting a synergistic behaviour in the Ni-Co-S anode.

  10. Cu-YSZ cermet solid oxide fuel cell anode prepared by high-temperature sintering

    NASA Astrophysics Data System (ADS)

    Tucker, Michael C.; Lau, Grace Y.; Jacobson, Craig P.; Visco, Steven J.; De Jonghe, Lutgard C.

    Porous YSZ-Cu alloy cermet structures are prepared by sintering above the metal melting point in reducing atmosphere. Unexpectedly good wetting of the molten metal within the YSZ network is obtained, resulting in cermets with fine structure and excellent electronic conductivity. Anode-supported solid oxide fuel cells are prepared with YSZ-Cu alloy cermet as the anode. Addition of infiltrated ceria catalyst improved the initial performance. Maximum power density of about 275 mA cm -2 and operation for about 110 h was achieved in the 700-800 °C range. After operation, AC impedance revealed that the high-frequency impedance was unchanged, whereas the low-frequency impedance increased. It was concluded that the Cu alloy network conductivity remains high, but catalyst stability needs improvement.

  11. Electrochemical performance of Sn-Sb-Cu film anodes prepared by layer-by-layer electrodeposition

    NASA Astrophysics Data System (ADS)

    Jiang, Qianlei; Xue, Ruisheng; Jia, Mengqiu

    2012-02-01

    A novel layer-by-layer electrodeposition and heat-treatment approach was attempted to obtain Sn-Sb-Cu film anode for lithium ion batteries. The preparation of Sn-Sb-Cu anodes started with galvanostatic electrochemically depositing antimony and tin sequentially on the substrate of copper foil collector. Sn-Sb and Cu-Sb alloys were formed when heated. The SEM analysis showed that the crystalline grains become bigger and the surface of the Sn-Sb-Cu anode becomes more denser after annealing. The energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analysis showed the antimony, tin and copper were alloyed to form SnSb and Cu2Sb after heat treatment. The X-ray photoelectron spectroscopy (XPS) analysis showed the surface of the Sn-Sb-Cu electrode was covered by a thin oxide layer. Electrochemical measurements showed that the annealed Sn-Sb-Cu anode has high reversible capacity and good capacity retention. It exhibited a reversible capacity of about 962 mAh/g in the initial cycle, which still remained 715 mAh/g after 30 cycles.

  12. Bacterial adherence to anodized titanium alloy

    NASA Astrophysics Data System (ADS)

    Pérez-Jorge Peremarch, C.; Pérez Tanoira, R.; Arenas, M. A.; Matykina, E.; Conde, A.; De Damborenea, J. J.; Gómez Barrena, E.; Esteban, J.

    2010-11-01

    The aim of this study was to evaluate Staphylococcus sp adhesion to modified surfaces of anodized titanium alloy (Ti-6Al-4V). Surface modification involved generation of fluoride-containing titanium oxide nanotube films. Specimens of Ti-6Al-4V alloy 6-4 ELI-grade 23- meets the requirements of ASTM F136 2002A (AMS 2631B class A1) were anodized in a mixture of sulphuric/hydrofluoric acid at 20 V for 5 and 60 min to form a 100 nm-thick porous film of 20 nm pore diameter and 230 nm-thick nanotube films of 100 nm in diameter. The amount of fluorine in the oxide films was of 6% and of 4%, respectively. Collection strains and six clinical strains each of Staphylococcus aureus and Staphylococcus epidermidis were studied. The adherence study was performed using a previously published protocol by Kinnari et al. The experiments were performed in triplicates. As a result, lower adherence was detected for collection strains in modified materials than in unmodified controls. Differences between clinical strains were detected for both species (p<0.0001, Kruskal-Wallis test), although global data showed similar results to that of collection strains (p<0.0001, Kruskal-Wallis test). Adherence of bacteria to modified surfaces was decreased for both species. The results also reflect a difference in the adherence between S. aureus and S. epidermidis to the modified material. As a conclusion, not only we were able to confirm the decrease of adherence in the modified surface, but also the need to test multiple clinical strains to obtain more realistic microbiological results due to intraspecies differences.

  13. Effect of Copper and Silicon on Al-5%Zn Alloy as a Candidate Low Voltage Sacrificial Anode

    NASA Astrophysics Data System (ADS)

    Pratesa, Yudha; Ferdian, Deni; Togina, Inez

    2017-05-01

    One common method used for corrosion protection is a sacrificial anode. Sacrificial anodes that usually employed in the marine environment are an aluminum alloy sacrificial anode, especially Al-Zn-In. However, the electronegativity of these alloys can cause corrosion overprotection and stress cracking (SCC) on a high-strength steel. Therefore, there is a development of the sacrificial anode aluminum low voltage to reduce the risk of overprotection. The addition of alloying elements such as Cu, Si, and Ge will minimize the possibility of overprotection. This study was conducted to analyze the effect of silicon and copper addition in Al-5Zn. The experiment started from casting the sacrificial anode aluminum uses electrical resistance furnace in a graphite crucible in 800°C. The results alloy was analyzed using Optical emission spectroscopy (OES), Differential scanning calorimetry, electrochemical impedance spectroscopy, and metallography. Aluminum alloy with the addition of a copper alloy is the most suitable and efficient to serve as a low-voltage sacrificial anode aluminum. Charge transfer resistivity of copper is smaller than silicon which indicates that the charge transfer between the metal and the electrolyte is easier t to occur. Also, the current potential values in coupling with steel are also in the criteria range of low-voltage aluminum sacrificial anodes.

  14. Effect of alloying elements Al and Ca on corrosion resistance of plasma anodized Mg alloys

    NASA Astrophysics Data System (ADS)

    Anawati, Asoh, Hidetaka; Ono, Sachiko

    2016-04-01

    Plasma anodizing is a surface treatment used to form a ceramic-type oxide film on Mg alloys by the application of a high anodic voltage to create intense plasma near the metal surface. With proper selection of the process parameters, the technique can produce high quality oxide with superior adhesion, corrosion resistance, micro-hardness, wear resistance and strength. The effect of alloying element Al on plasma anodizing process of Mg alloys was studied by comparing the anodizing curves of pure Mg, AZ31, and AZ61 alloys while the effect of Ca were studied on AZ61 alloys containing 0, 1, and 2 wt% Ca. Anodizing was performed in 0.5 M Na3PO4 solution at a constant current density of 200 Am-2 at 25°C. Anodic oxide films with lava-like structure having mix composition of amorphous and crystal were formed on all of the alloys. The main crystal form of the oxide was Mg3(PO4)2 as analyzed by XRD. Alloying elements Al and Ca played role in modifying the plasma lifetime during anodization. Al tended to extend the strong plasma lifetime and therefore accelerated the film thickening. The effect of Ca on anodizing process was still unclear. The anodic film thickness and chemical composition were altered by the presence of Ca in the alloys. Electrochemical corrosion test in 0.9% NaCl solution showed that the corrosion behavior of the anodized specimens depend on the behavior of the substrate. Increasing Al and Ca content in the alloys tended to increase the corrosion resistance of the specimens. The corrosion resistance of the anodized specimens improved significantly about two orders of magnitude relative to the bare substrate.

  15. Aluminum alloy anode materials for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Sun, Z. H.; Chen, Z. F.; Fu, Q. W.; Jiang, X. Y.

    2017-03-01

    Aluminum has larger theoretical capacity of 2235 mAh/g than that of graphite (372 mAh/g), but it has big disadvantages including shorter cycle life and higher irreversible capacity loss. Improving cycle performance can be obtained via alloying of aluminum. In this paper, two ternary aluminum alloy, Al7Cu2Fe and Al73Cu5Fe22 were prepared. The main phase of Al7Cu2Fe alloy was Al7Cu2Fe. The heat treatment increased the proportion of Al7Cu2Fe. The main phase of Al73Cu5Fe22 alloy was Al60Cu30Fe10. The heat treatment reduced the proportion of Al60Cu30Fe10. For two alloys, the heat treatment could increase discharge capacity compared with cast alloy. The discharge capacity was improved by 50%. The content of aluminum in alloys has little effect on improving cycle performance, and it has obvious influence on the phase structure of alloy with heat treatment.

  16. Microscale Alloy Type Lithium Ion Battery Anodes

    DTIC Science & Technology

    2015-09-01

    the backside might be protected with a layer of photoresist or hard mask that could be etched at a later time. As shown in Fig. 2, for the fabrication...The fabrication of microscale anodes designed for in situ atomic force microscopy testing is discussed. The anodes are partially confined in a nickel...

  17. Behavior of CuP and OFHC Cu anodes under electrodeposition conditions

    SciTech Connect

    Frankel, G.S.; Schrott, A.G.; Horkans, J.; Andricacos, P.C.; Isaacs, H.S.

    1992-08-01

    Films formed on CuP (with 0.05 wt % P) and OFHC Cu anodes in electroplating solutions were studied by X-ray Photoelectron Spectroscopy, X-ray Absorption Spectroscopy, electrochemical methods, and a newly developed gravimetric technique. The black film formed on CuP in Cl-containing solutions was found to resemble a porous sponge composed of CuCl but laden/with concentrated CuSO{sub 4} solution. The difference between the buoyancy-corrected measured mass change and the charge-equivalent mass change was found to have two components: a reversible part that comes and goes as the current is turned on and off, and an irreversible part that remains on the surface and increase in mass with time. The irreversible part results from the anodic film, which increases linearly with charge density but independent of current density. The reversible part of the mass change arises from the weight of the diffusion layer. In contrast to CuP, OFHC Cu releases much more Cu{sup +1} during anodic polarization and forms a poorly-adherent anodic film that is considerably heavier than the black film for a given charge density.

  18. Behavior of CuP and OFHC Cu anodes under electrodeposition conditions

    SciTech Connect

    Frankel, G.S.; Schrott, A.G.; Horkans, J.; Andricacos, P.C. . Thomas J. Watson Research Center); Isaacs, H.S. )

    1992-01-01

    Films formed on CuP (with 0.05 wt % P) and OFHC Cu anodes in electroplating solutions were studied by X-ray Photoelectron Spectroscopy, X-ray Absorption Spectroscopy, electrochemical methods, and a newly developed gravimetric technique. The black film formed on CuP in Cl-containing solutions was found to resemble a porous sponge composed of CuCl but laden/with concentrated CuSO{sub 4} solution. The difference between the buoyancy-corrected measured mass change and the charge-equivalent mass change was found to have two components: a reversible part that comes and goes as the current is turned on and off, and an irreversible part that remains on the surface and increase in mass with time. The irreversible part results from the anodic film, which increases linearly with charge density but independent of current density. The reversible part of the mass change arises from the weight of the diffusion layer. In contrast to CuP, OFHC Cu releases much more Cu{sup +1} during anodic polarization and forms a poorly-adherent anodic film that is considerably heavier than the black film for a given charge density.

  19. Optical properties of porous anodic alumina embedded Cu nanocomposite films

    NASA Astrophysics Data System (ADS)

    Liu, Huiyuan; Sun, Huiyuan; Liu, Lihu; Hou, Xue; Jia, Xiaoxuan

    2015-06-01

    Porous anodic alumina embedded Cu with iridescent colors were fabricated in copper sulfate electrolyte. The films display highly saturated colors after being synthesized by an ac electrodeposition method. Tunable color in the films is obtained by adjusting anodization time, and can be adjusted across the entire visible range. Theoretical results of the changes in the structural color according to the Bragg-Snell formula are consistent with the experimental results. The films could be used in many areas including decoration, display and multifunctional anti-counterfeiting applications.

  20. Solid solution lithium alloy cermet anodes

    SciTech Connect

    Richardson, Thomas J.

    2013-07-09

    A metal-ceramic composite ("cermet") has been produced by a chemical reaction between a lithium compound and another metal. The cermet has advantageous physical properties, high surface area relative to lithium metal or its alloys, and is easily formed into a desired shape. An example is the formation of a lithium-magnesium nitride cermet by reaction of lithium nitride with magnesium. The reaction results in magnesium nitride grains coated with a layer of lithium. The nitride is inert when used in a battery. It supports the metal in a high surface area form, while stabilizing the electrode with respect to dendrite formation. By using an excess of magnesium metal in the reaction process, a cermet of magnesium nitride is produced, coated with a lithium-magnesium alloy of any desired composition. This alloy inhibits dendrite formation by causing lithium deposited on its surface to diffuse under a chemical potential into the bulk of the alloy.

  1. Mechanical properties of anodized coatings over molten aluminum alloy.

    PubMed

    Grillet, Anne M; Gorby, Allen D; Trujillo, Steven M; Grant, Richard P; Hodges, V Carter; Parson, Ted B; Grasser, Thomas W

    2008-01-01

    A method to measure interfacial mechanical properties at high temperatures and in a controlled atmosphere has been developed to study anodized aluminum surface coatings at temperatures where the interior aluminum alloy is molten. This is the first time that the coating strength has been studied under these conditions. We have investigated the effects of ambient atmosphere, temperature, and surface finish on coating strength for samples of aluminum alloy 7075. Surprisingly, the effective Young's modulus or strength of the coating when tested in air was twice as high as when samples were tested in an inert nitrogen or argon atmosphere. Additionally, the effective Young's modulus of the anodized coating increased with temperature in an air atmosphere but was independent of temperature in an inert atmosphere. The effect of surface finish was also examined. Sandblasting the surface prior to anodization was found to increase the strength of the anodized coating with the greatest enhancement noted for a nitrogen atmosphere. Machining marks were not found to significantly affect the strength.

  2. Solid state thin film battery having a high temperature lithium alloy anode

    DOEpatents

    Hobson, David O.

    1998-01-01

    An improved rechargeable thin-film lithium battery involves the provision of a higher melting temperature lithium anode. Lithium is alloyed with a suitable solute element to elevate the melting point of the anode to withstand moderately elevated temperatures.

  3. Recycled tetrahedron-like CuCl from waste Cu scraps for lithium ion battery anode.

    PubMed

    Hou, Hongying; Yao, Yuan; Liu, Song; Duan, Jixiang; Liao, Qishu; Yu, Chengyi; Li, Dongdong; Dai, Zhipeng

    2017-07-01

    The wide applications of metal Cu inevitably resulted in a large quantity of waste Cu materials. In order to recover the useful Cu under the mild conditions and reduce the environmental emission, waste Cu scraps were recycled in the form of CuCl powders with high economic value added (EVA) via the facile hydrothermal route. The recycled CuCl powders were characterized in terms of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The results suggested that the recycled CuCl powders consisted of many regular tetrahedron-like micro-particles. Furthermore, in order to reduce the cost of lithium ion battery (LIB) anode and build the connection of waste Cu scraps and LIB, the recycled CuCl powders were evaluated as the anode active material of LIB. As expected, the reversible discharge capacity was about 171.8mAh/g at 2.0C even after 50 cycles, implying the satisfactory cycle stability. Clearly, the satisfactory results may open a new avenue to develop the circular economy and the sustainable energy industry, which would be very important in terms of both the resource recovery and the environmental protection. Copyright © 2017. Published by Elsevier Ltd.

  4. Biodegradation and cytotoxic properties of pulse anodized Mg alloys

    NASA Astrophysics Data System (ADS)

    Kim, Yu Kyoung; Park, Il Song; Lee, Sook Jeong; Lee, Min Ho

    2013-03-01

    Magnesium has the potential to be used as an implant material owing to its non-toxicity. On the other hand, magnesium alloys corrode rapidly in subcutaneous gas bubbles. Consequently, the approach of using magnesium alloys as a biodegradable biomaterial is not well established. Therefore, the aim of this study was to provide corrosion protection by anodizing to surface for a biodegradable material. Micro-arc oxidation by pulsed DC was applied to AZ91D and AZ31B, and the cell bioactivity was defined. The anodic film was characterized by XRD and SEM. The specific mass loss variation from immersion test and potentiodynamic electrochemical test was performed for the quantification of corrosion resistance. Although the AZ91D had better corrosion resistance properties but the result of the in vitro tests showed low cell viability compared with the AZ31B. The results of the cell staining and agar overlay test revealed the AZ31B group had good biocompatibility and a low corrosion rate. In this study, the surfaces of AZ91D and AZ31B showed the formation of a uniform film by pulse power anodization improving corrosion resistance. Also, the cytotoxicity of the materials was examined by the aluminum content change of compound metal.

  5. CuLi2Sn and Cu2LiSn: Characterization by single crystal XRD and structural discussion towards new anode materials for Li-ion batteries.

    PubMed

    Fürtauer, Siegfried; Effenberger, Herta S; Flandorfer, Hans

    2014-12-01

    The stannides CuLi2Sn (CSD-427095) and Cu2LiSn (CSD-427096) were synthesized by induction melting of the pure elements and annealing at 400 °C. The phases were reinvestigated by X-ray powder and single-crystal X-ray diffractometry. Within both crystal structures the ordered CuSn and Cu2Sn lattices form channels which host Cu and Li atoms at partly mixed occupied positions exhibiting extensive vacancies. For CuLi2Sn, the space group F-43m. was verified (structure type CuHg2Ti; a=6.295(2) Å; wR2(F²)=0.0355 for 78 unique reflections). The 4(c) and 4(d) positions are occupied by Cu atoms and Cu+Li atoms, respectively. For Cu2LiSn, the space group P63/mmc was confirmed (structure type InPt2Gd; a=4.3022(15) Å, c=7.618(3) Å; wR2(F²)=0.060 for 199 unique reflections). The Cu and Li atoms exhibit extensive disorder; they are distributed over the partly occupied positions 2(a), 2(b) and 4(e). Both phases seem to be interesting in terms of application of Cu-Sn alloys as anode materials for Li-ion batteries.

  6. CuLi2Sn and Cu2LiSn: Characterization by single crystal XRD and structural discussion towards new anode materials for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Fürtauer, Siegfried; Effenberger, Herta S.; Flandorfer, Hans

    2014-12-01

    The stannides CuLi2Sn (CSD-427095) and Cu2LiSn (CSD-427096) were synthesized by induction melting of the pure elements and annealing at 400 °C. The phases were reinvestigated by X-ray powder and single-crystal X-ray diffractometry. Within both crystal structures the ordered CuSn and Cu2Sn lattices form channels which host Cu and Li atoms at partly mixed occupied positions exhibiting extensive vacancies. For CuLi2Sn, the space group F-43m. was verified (structure type CuHg2Ti; a=6.295(2) Å; wR2(F²)=0.0355 for 78 unique reflections). The 4(c) and 4(d) positions are occupied by Cu atoms and Cu+Li atoms, respectively. For Cu2LiSn, the space group P63/mmc was confirmed (structure type InPt2Gd; a=4.3022(15) Å, c=7.618(3) Å; wR2(F²)=0.060 for 199 unique reflections). The Cu and Li atoms exhibit extensive disorder; they are distributed over the partly occupied positions 2(a), 2(b) and 4(e). Both phases seem to be interesting in terms of application of Cu-Sn alloys as anode materials for Li-ion batteries.

  7. Lithium insertion/extraction mechanism in alloy anodes for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Zhang, Wei-Jun

    The electrochemical performance of alloy anodes has been reviewed in a previous paper [1]. In this work, the fundamental understanding of lithium-insertion/extraction mechanism in alloy anodes is discussed. The article summarizes the different types of lithium-reaction processes observed in Si, Sn, Sb, Al, Mg and their alloys, with particular emphasis on the characteristics unique to alloy anodes, including the sloping voltage profiles, lithiation amorphization, cycling hysteresis and reaction-potential depression. These unique characteristics are discussed with respect to the effect of interface and surface energies on the phase transformation and thermodynamic stability of fine alloy particles.

  8. Surface Segregation in Cu-Ni Alloys

    NASA Technical Reports Server (NTRS)

    Good, Brian; Bozzolo, Guillermo; Ferrante, John

    1993-01-01

    Monte Carlo simulation is used to calculate the composition profiles of surface segregation of Cu-Ni alloys. The method of Bozzolo, Ferrante, and Smith is used to compute the energetics of these systems as a function of temperature, crystal face, and bulk concentration. The predictions are compared with other theoretical and experimental results.

  9. Micro and nano-texturization of intermetallic oxide alloys by a single anodization step: preparation of artificial self-cleaning surfaces.

    PubMed

    Feil, Adriano F; Weibel, Daniel E; Corsetti, Rodrigo R; Pierozan, Matheus D; Michels, Alexandre F; Horowitz, Flavio; Amaral, Lívio; Teixeira, Sérgio R

    2011-10-01

    Micro- and nanostructures of Ti-γCu (γ = 0, 30, 50, 70, and 100 wt %) intermetallic alloys were produced through a single anodization step. It was found that the original alloy composition influences the final oxide morphology obtained after anodization which presented formation of a microstructure with nanotubes, nanoparticles or nanopillars on the surface. Pure Ti and Cu oxide metals and their alloys presented hydrophilic or superhydrophilic properties immediately after anodization. When the anodized pure metal and/or Ti-γCu surfaces were functionalized with trimethoxypropylsilane (TPMSi), by dipping and coating with a thin perfluorinated layer, the treated substrates became in all cases superhydrophobic (water contact angles in the range of 152-166°), showing excellent self-cleaning properties with hysteresis below 3°. These results can be explained by a combination of nanomicro morphologies with low surface energy compounds in the topmost monolayers. The decrease in hysteresis was associated with a higher M-OH bond concentration on the anodized surfaces, which allowed for more complete TMPSi coating coverage. This study also indicates that easy and effective fabrication of superhydrophobic surfaces in pure metals and alloys is possible without involving traditional multistep processes.

  10. CuLi2Sn and Cu2LiSn: Characterization by single crystal XRD and structural discussion towards new anode materials for Li-ion batteries

    PubMed Central

    Fürtauer, Siegfried; Effenberger, Herta S.; Flandorfer, Hans

    2014-01-01

    The stannides CuLi2Sn (CSD-427095) and Cu2LiSn (CSD-427096) were synthesized by induction melting of the pure elements and annealing at 400 °C. The phases were reinvestigated by X-ray powder and single-crystal X-ray diffractometry. Within both crystal structures the ordered CuSn and Cu2Sn lattices form channels which host Cu and Li atoms at partly mixed occupied positions exhibiting extensive vacancies. For CuLi2Sn, the space group F-43m. was verified (structure type CuHg2Ti; a=6.295(2) Å; wR2(F²)=0.0355 for 78 unique reflections). The 4(c) and 4(d) positions are occupied by Cu atoms and Cu+Li atoms, respectively. For Cu2LiSn, the space group P63/mmc was confirmed (structure type InPt2Gd; a=4.3022(15) Å, c=7.618(3) Å; wR2(F²)=0.060 for 199 unique reflections). The Cu and Li atoms exhibit extensive disorder; they are distributed over the partly occupied positions 2(a), 2(b) and 4(e). Both phases seem to be interesting in terms of application of Cu–Sn alloys as anode materials for Li-ion batteries. PMID:25473128

  11. The corrosion protection of several aluminum alloys by chromic acid and sulfuric acid anodizing

    NASA Technical Reports Server (NTRS)

    Danford, M. D.

    1994-01-01

    The corrosion protection afforded 7075-T6, 7075-T3, 6061-T6, and 2024-T3 aluminum alloys by chromic acid and sulfuric acid anodizing was examined using electrochemical techniques. From these studies, it is concluded that sulfuric acid anodizing provides superior corrosion protection compared to chromic acid anodizing.

  12. Corrosion behavior of Pd-Cu and Pd-Co alloys in synthetic saliva.

    PubMed

    Goehlich, V; Marek, M

    1990-04-01

    Pd-based alloys are major alternatives to gold-based alloys for PFM applications. In electrolytes simulating oral fluids, these alloys exhibit electrode behavior similar to passivity of active metals, i.e., a potential region of almost constant current density up to a critical potential, above which the current increases. The objective of this study was to correlate the electrode behavior with the results of solution analyses and changes in the surface composition of the alloys. Binary alloys Pd-15 wt% Cu and Pd-19 wt% Co, as well as the pure components, were examined. Corrosion potentials vs. time, potentiodynamic anodic polarization curves, polarization resistances vs. time, and potentiostatic anodic charges were measured with synthetic saliva used as the electrolyte. The concentrations of Pd, Cu, and Co in the solution after various exposures were determined by atomic absorption. The surfaces of the alloys were examined by x-ray photoelectron spectroscopy before and after the exposures. The results show that selective dissolution of the less-noble components occurred on the surfaces of both alloys for all the exposures, leaving the surfaces highly enriched in Pd. This enrichment contributed to the potential changes and the passive-type behavior. Copper dissolved more than cobalt at longer exposures and higher potentials, in spite of its higher nobility. Dissolution of cobalt seemed to be limited by the formation of a surface film, which may be related to the transition character of this element.

  13. Corrosion characteristics of anodized Ti-(10-40wt%)Hf alloys for metallic biomaterials use.

    PubMed

    Jeong, Yong-Hoon; Choe, Han-Cheol; Brantley, William A

    2011-01-01

    The effect of anodizing on corrosion resistance of Ti-xHf alloys has been investigated. Ti-xHf alloys were prepared and anodized at 120, 170 and 220 V in 1 M H(3)PO(4) solution, and crystallized at 300 and 500°C. Corrosion experiments were carried out using a potentiostat in 0.15 M NaCl solution at 36.5 ± 1°C. The Ti-xHf alloys exhibited the α' and anatase phases. The pore size on the anodized surface increases as the applied voltage is increased, whereas the pore size decreases as the Hf content is increased. The anodized Ti-xHf alloys exhibited better corrosion resistance than non-anodized Ti-xHf alloys.

  14. Cu precipitation dynamics in Fe-Cu alloy

    NASA Astrophysics Data System (ADS)

    Ren, H.-P.; Wang, H.-Y.; Liu, Z.-C.

    2008-02-01

    The precipitation of copper during aging at 600°C in high-purity Fe-Cu alloy was examined by means of transmission electron microscopy, Nano-scale copper-rich clusters with B2-like structure were observed during either solution treatment or aging, which should play important role on precipitation strengthening. In addition, the precipitation process has been analyzed in terms of the evolution of microstructure by Monte Carlo method. An description of the coherent precipitation of copper in iron, based on vacancy diffusion mechanism, thermally activated jump frequencies and cohesive energy was discussed to deal with simultaneous precipitation of metastable and stable phases of Cu-containing steel during aging, which gives an estimation of the precipitation dynamics, as well as the evolution of Cu precipitates in a wide range of temperature.

  15. Building Self-Healing Alloy Architecture for Stable Sodium-Ion Battery Anodes: A Case Study of Tin Anode Materials.

    PubMed

    Mao, Jianfeng; Fan, Xiulin; Luo, Chao; Wang, Chunsheng

    2016-03-23

    The rational design of anode materials is a challenge in developing sodium ion batteries. Alloy anodes provide high gravimetric and volumetric capacities but suffer the short cycle life as a result of the continuous and accumulated pulverization, resulting from a large volume change during the cycling process. Herein, using pure Sn, an irreversible conversion reaction combined with an alloy reaction (SnO), and a reversible conversion reaction combined with an alloy reaction (Sn4P3) as samples, we demonstrate that the pulverization and aggregation of the alloy anode can be partially recovered and the accumulation of pulverization and aggregation during charge/discharge cycles can be terminated using a reversible conversion reaction combined with an alloy reaction. The cycling stability of three Sn-based anodes increases in order of Sn4P3 > SnO > Sn. The enhancement in Sn4P3 can be attributed to a reversible reaction of Sn4P3 + 9Na ↔ 4Sn + 3Na3P, which repairs the cracks, damage, and aggregation of Sn particles that occurred in the alloy process of 4Sn + 15Na ↔ Na15Sn4 during cycling and, hence, terminates the pulverization. The repair mechanism looks like the self-healing feature in nature, where the damage can be healed by itself. Therefore, the suggested mechanism can be called self-healing, while the repaired anode can be termed as the self-healing anode. The use of self-healing strategies to build an electrode architecture is new and highly desirable because it can increase the cycle life and provide a general approach toward stable electrode materials.

  16. Electrochemical Performance Estimation of Anodized AZ31B Magnesium Alloy as Function of Change in the Current Density

    NASA Astrophysics Data System (ADS)

    Girón, L.; Aperador, W.; Tirado, L.; Franco, F.; Caicedo, J. C.

    2017-06-01

    The anodized AZ31B magnesium alloys were synthesized via electrodeposition processes. The aim of this work was to determine the electrochemical behavior of magnesium alloys by using anodized alloys as a protective coating. The anodized alloys were characterized by x-ray diffraction, exhibiting the crystallography orientation for Mg and MgO phases. The x-ray photoelectron spectroscopy was used to determine the chemical composition of anodized magnesium alloys. By using electrochemical impedance spectroscopy and Tafel curves, it was possible to estimate the electrochemical behavior of anodized AZ31B magnesium alloys in Hank's balanced salt solution (HBSS). Scanning electron microscopy was performed to analyze chemical changes and morphological surface changes on anodized Mg alloys due to the reaction in HBSS/anodized magnesium surface interface. Electrochemical behavior in HBSS indicates that the coatings may be a promising material for biomedical industry.

  17. Electrochemical Performance Estimation of Anodized AZ31B Magnesium Alloy as Function of Change in the Current Density

    NASA Astrophysics Data System (ADS)

    Girón, L.; Aperador, W.; Tirado, L.; Franco, F.; Caicedo, J. C.

    2017-08-01

    The anodized AZ31B magnesium alloys were synthesized via electrodeposition processes. The aim of this work was to determine the electrochemical behavior of magnesium alloys by using anodized alloys as a protective coating. The anodized alloys were characterized by x-ray diffraction, exhibiting the crystallography orientation for Mg and MgO phases. The x-ray photoelectron spectroscopy was used to determine the chemical composition of anodized magnesium alloys. By using electrochemical impedance spectroscopy and Tafel curves, it was possible to estimate the electrochemical behavior of anodized AZ31B magnesium alloys in Hank's balanced salt solution (HBSS). Scanning electron microscopy was performed to analyze chemical changes and morphological surface changes on anodized Mg alloys due to the reaction in HBSS/anodized magnesium surface interface. Electrochemical behavior in HBSS indicates that the coatings may be a promising material for biomedical industry.

  18. Corrosion behavior of cast Ti-6Al-4V alloyed with Cu.

    PubMed

    Koike, Marie; Cai, Zhuo; Oda, Yutaka; Hattori, Masayuki; Fujii, Hiroyuki; Okabe, Toru

    2005-05-01

    It has recently been found that alloying with copper improved the inherently poor grindability and wear resistance of titanium. This study characterized the corrosion behavior of cast Ti-6Al-4V alloyed with copper. Alloys (0.9 or 3.5 mass % Cu) were cast with the use of a magnesia-based investment in a centrifugal casting machine. Three specimen surfaces were tested: ground, sandblasted, and as cast. Commercially pure titanium and Ti-6Al-4V served as controls. Open-circuit potential measurement, linear polarization, and potentiodynamic cathodic polarization were performed in aerated (air + 10% CO(2)) modified Tani-Zucchi synthetic saliva at 37 degrees C. Potentiodynamic anodic polarization was conducted in the same medium deaerated by N(2) + 10% CO(2). Polarization resistance (R(p)), Tafel slopes, and corrosion current density (I(corr)) were determined. A passive region occurred for the alloy specimens with ground and sandblasted surfaces, as for CP Ti. However, no passivation was observed on the as-cast alloys or on CP Ti. There were significant differences among all metals tested for R(p) and I(corr) and significantly higher R(p) and lower I(corr) values for CP Ti compared to Ti-6Al-4V or the alloys with Cu. Alloying up to 3.5 mass % Cu to Ti-6Al-4V did not change the corrosion behavior. Specimens with ground or sandblasted surfaces were superior to specimens with as-cast surfaces.

  19. Cermet anode compositions with high content alloy phase

    DOEpatents

    Marschman, S.C.; Davis, N.C.

    1989-10-03

    Cermet electrode compositions comprising NiO-NiFe[sub 2]O[sub 4]-Cu-Ni, and methods for making, are disclosed. Addition of nickel metal prior to formation and densification of a base mixture into the cermet allows for an increase in the total amount of copper and nickel that can be contained in the NiO-NiFe[sub 2]O[sub 4] oxide system. Nickel is present in a base mixture weight concentration of from 0.1% to 10%. Copper is present in the alloy phase in a weight concentration of from 10% to 30% of the densified composition. Such cermet electrodes can be formed to have electrical conductivities well in excess of 100 ohm[sup [minus]1] cm[sup [minus]1]. Other alloy and oxide system cermets having high content metal phases are also expected to be manufacturable in accordance with the invention.

  20. Cermet anode compositions with high content alloy phase

    DOEpatents

    Marschman, Steven C.; Davis, Norman C.

    1989-01-01

    Cermet electrode compositions comprising NiO-NiFe.sub.2 O.sub.4 -Cu-Ni, and methods for making, are disclosed. Addition of nickel metal prior to formation and densification of a base mixture into the cermet allows for an increase in the total amount of copper and nickel that can be contained in the NiO-NiFe.sub.2 O.sub.4 oxide system. Nickel is present in a base mixture weight concentration of from 0.1% to 10%. Copper is present in the alloy phase in a weight concentration of from 10% to 30% of the densified composition. Such cermet electrodes can be formed to have electrical conductivities well in excess of 100 ohm.sup.-1 cm.sup.-1. Other alloy and oxide system cermets having high content metal phases are also expected to be manufacturable in accordance with the invention.

  1. Effects of Zn-In-Sn elements on the electric properties of magnesium alloy anode materials.

    PubMed

    Yu, Zhan; Ju, Dongying; Zhao, Hongyang; Hu, Xiaodong

    2011-06-01

    A new magnesium alloy anode is based on an environmentally friendly electrode that contains none of mercury, lead and chromate, but it can enhance the electric properties of alloy significantly. Magnesium alloy adding eco-friendly elements Zn-In-Sn which was developed by orthogonal design were obtained by two casting methods. The effect of additive elements on performance of electrode material was studied. The effects of elements addition and casting method on electric properties and corrosive properties of Mg-Zn-In-Sn alloys were investigated by using electrochemical measurements, corrosive tests and observation of surface structure. The results show that Mg-Zn-In-Sn alloy anode has higher electromotive force and more stable work potential than that commercial magnesium alloy AZ91. It is suitable for anode material of magnesium battery for its small hydrogen evolution, less self-corrosion rate and easy to shed corrosive offspring off.

  2. Indium Helps Strengthen Al/Cu/Li Alloy

    NASA Technical Reports Server (NTRS)

    Blackburn, Linda B.; Starke, Edgar A., Jr.

    1992-01-01

    Experiments on Al/Cu/Li alloys focus specifically on strengthening effects of minor additions of In and Cd. Indium-bearing alloy combines low density with ability to achieve high strength through heat treatment alone. Tensile tests on peak-aged specimens indicated that alloy achieved yield strength approximately 15 percent higher than baseline alloy. Alloy highly suitable for processing to produce parts of nearly net shape, with particular applications in aircraft and aerospace vehicles.

  3. Indium Helps Strengthen Al/Cu/Li Alloy

    NASA Technical Reports Server (NTRS)

    Blackburn, Linda B.; Starke, Edgar A., Jr.

    1992-01-01

    Experiments on Al/Cu/Li alloys focus specifically on strengthening effects of minor additions of In and Cd. Indium-bearing alloy combines low density with ability to achieve high strength through heat treatment alone. Tensile tests on peak-aged specimens indicated that alloy achieved yield strength approximately 15 percent higher than baseline alloy. Alloy highly suitable for processing to produce parts of nearly net shape, with particular applications in aircraft and aerospace vehicles.

  4. Microstructure and properties of Cu-Ti-Ni alloys

    NASA Astrophysics Data System (ADS)

    Liu, Jia; Wang, Xian-hui; Guo, Ting-ting; Zou, Jun-tao; Yang, Xiao-hong

    2015-11-01

    The effects of Ni addition and aging treatments on the microstructure and properties of a Cu-3Ti alloy were investigated. The microstructure and precipitation phases were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy; the hardness, electrical conductivity, and elastic modulus of the resulting alloys were also tested. The results show that Ni addition increases the electrical conductivity and elastic modulus, but decreases the hardness of the aged Cu-3Ti alloy. Within the range of the experimentally investigated parameters, the optimal two-stage aging treatment for the Cu-3Ti-1Ni and Cu-3Ti-5Ni alloy was 300°C for 2 h and 450°C for 7 h. The hardness, electrical conductivity, and elastic modulus of the Cu-3Ti-1Ni alloy were HV 205, 18.2% IACS, and 146 GPa, respectively, whereas the hardness, electrical conductivity, and elastic modulus of the Cu-3Ti-5Ni alloy were HV 187, 31.32% IACS, and 147 GPa, respectively. Microstructural analyses revealed that β'-Ni3Ti and β'-Cu4Ti precipitate from the Cu matrix during aging of the Cu-3Ti-5Ni alloy and that some residual NiTi phase remains. The increased electrical conductivity is ascribed to the formation of NiTi, β'-Ni3Ti, and β'-Cu4Ti phases.

  5. Cell response of anodized nanotubes on titanium and titanium alloys.

    PubMed

    Minagar, Sepideh; Wang, James; Berndt, Christopher C; Ivanova, Elena P; Wen, Cuie

    2013-09-01

    Titanium and titanium alloy implants that have been demonstrated to be more biocompatible than other metallic implant materials, such as Co-Cr alloys and stainless steels, must also be accepted by bone cells, bonding with and growing on them to prevent loosening. Highly ordered nanoporous arrays of titanium dioxide that form on titanium surface by anodic oxidation are receiving increasing research interest due to their effectiveness in promoting osseointegration. The response of bone cells to implant materials depends on the topography, physicochemistry, mechanics, and electronics of the implant surface and this influences cell behavior, such as adhesion, proliferation, shape, migration, survival, and differentiation; for example the existing anions on the surface of a titanium implant make it negative and this affects the interaction with negative fibronectin (FN). Although optimal nanosize of reproducible titania nanotubes has not been reported due to different protocols used in studies, cell response was more sensitive to titania nanotubes with nanometer diameter and interspace. By annealing, amorphous TiO2 nanotubes change to a crystalline form and become more hydrophilic, resulting in an encouraging effect on cell behavior. The crystalline size and thickness of the bone-like apatite that forms on the titania nanotubes after implantation are also affected by the diameter and shape. This review describes how changes in nanotube morphologies, such as the tube diameter, the thickness of the nanotube layer, and the crystalline structure, influence the response of cells. Copyright © 2013 Wiley Periodicals, Inc.

  6. Properties of a new type Al/Pb-0.3%Ag alloy composite anode for zinc electrowinning

    NASA Astrophysics Data System (ADS)

    Yang, Hai-tao; Liu, Huan-rong; Zhang, Yong-chun; Chen, Bu-ming; Guo, Zhong-cheng; Xu, Rui-dong

    2013-10-01

    An Al/Pb-0.3%Ag alloy composite anode was produced via composite casting. Its electrocatalytic activity for the oxygen evolution reaction and corrosion resistance was evaluated by anodic polarization curves and accelerated corrosion test, respectively. The microscopic morphologies of the anode section and anodic oxidation layer during accelerated corrosion test were obtained by scanning electron microscopy. It is found that the composite anode (hard anodizing) displays a more compact interfacial combination and a better adhesive strength than plating tin. Compared with industrial Pb-0.3%Ag anodes, the oxygen evolution overpotentials of Al/Pb-0.3%Ag alloy (hard anodizing) and Al/Pb-0.3%Ag alloy (plating tin) at 500 A·m-2 were lower by 57 and 14 mV, respectively. Furthermore, the corrosion rates of Pb-0.3%Ag alloy, Al/Pb-0.3%Ag alloy (hard anodizing), and Al/Pb-0.3%Ag alloy (plating tin) were 13.977, 9.487, and 11.824 g·m-2·h-1, respectively, in accelerated corrosion test for 8 h at 2000 A·m-2. The anodic oxidation layer of Al/Pb-0.3%Ag alloy (hard anodizing) is more compact than Pb-0.3%Ag alloy and Al/Pb-0.3%Ag alloy (plating tin) after the test.

  7. Preparation of Cu-Ni/YSZ solid oxide fuel cell anodes using microwave irradiation

    NASA Astrophysics Data System (ADS)

    Islam, Shamiul; Hill, Josephine M.

    A microwave irradiation process is used to deposit Cu nanoparticles on the Ni/YSZ anode of an electrolyte-supported solid oxide fuel cell (SOFC). The reaction time in the microwave is only 15 s for the deposition of 6 wt% Cu (with respect to Ni) from a solution of Cu(NO 3) 2·3H 2O and ethylene glycol (HOCH 2CH 2OH). The morphology of the deposited Cu particles is spherical and the average size of the particles is less than 100 nm. The electrochemical performance of the microwave Cu-coated Ni/YSZ anodes is tested in dry H 2 and dry CH 4 at 1073 K, and the anodes are characterized with scanning electron microscopy, electrochemical impedance spectroscopy, and temperature-programmed oxidation. The results indicate that preparation of the anodes by the microwave technique produces similar performance trend as those reported for Cu-Ni/YSZ/CeO 2 anodes prepared by impregnation. Specifically, less carbon is formed on the Cu-Ni/YSZ than on conventional Ni/YSZ anodes when exposed to dry methane and the carbon that does form is more reactive.

  8. Modeling of anodic dissolution of U Pu Zr ternary alloy in the molten LiCl KCl electrolyte

    NASA Astrophysics Data System (ADS)

    Iizuka, Masatoshi; Kinoshita, Kensuke; Koyama, Tadafumi

    2005-02-01

    The metallic fuel anode in the molten salt electrorefining step for the pyrometallurgical reprocessing was modeled based on the findings from the anodic dissolution tests using a U Pu Zr ternary alloy. This anode model simulates selective dissolution of uranium and plutonium at lower anode potential, growth of a diffusion controlling layer consisting of a mixture of the molten salt electrolyte and the remaining zirconium metal, and simultaneous dissolution of all the constituents at higher anode potential. The calculation with this model reproduced well the actual anodic behavior of the U Pu Zr ternary alloy such as two-step rapid rise in the anode potential.

  9. Porous Co3O4/CuO composite assembled from nanosheets as high-performance anodes for lithium-ion batteries.

    PubMed

    Hao, Qin; Zhao, Dianyun; Duan, Huimei; Xu, Caixia

    2015-04-24

    Upon dealloying a carefully designed CoCuAl ternary alloy in NaOH solution at room temperature, a Co3 O4 /CuO nanocomposite with an interconnected porous microstructure assembled by a secondary structure of nanosheets was successfully fabricated. By using the dealloying strategy, the target metals directly grew to form uniform bimetallic oxide nanocomposites. Owing to the unique hierarchical structure and the synergistic effect of both active electrode materials, the Co3 O4 /CuO nanocomposite exhibits much enhanced electrochemical performance with higher capacities and better cycling stability compared to anodes of pure Co3 O4 . Moreover, it performs excellently in terms of cycle reversibility, Coulombic efficiency, and rate capability, at both low or high current rates. With the advantages of unique performance and ease of preparation, the as-made Co3 O4 /CuO nanocomposite demonstrates promising application potential as an advanced anode material for lithium-ion batteries.

  10. Solid state thin film battery having a high temperature lithium alloy anode

    DOEpatents

    Hobson, D.O.

    1998-01-06

    An improved rechargeable thin-film lithium battery involves the provision of a higher melting temperature lithium anode. Lithium is alloyed with a suitable solute element to elevate the melting point of the anode to withstand moderately elevated temperatures. 2 figs.

  11. Nanostructured Cu-CGO anodes fabricated using a microwave-assisted glycine-nitrate process

    NASA Astrophysics Data System (ADS)

    Shaikh, Shabana P. S.; Somalu, Mahendra R.; Muchtar, Andanastuti

    2016-11-01

    This work reports a study of nanostructured copper-doped gadolinium cermet (Cu-CGO) composite anodes prepared via conventional synthesis (CS) and microwave-synthesis (MS) involving the glycine-nitrate process (GNP). A detailed investigation on the mechanical properties, electrical conductivity and electrochemical performance of prepared Cu0.5(Ce0.9Gd0.1)0.5O2-δ anodes is included. The prepared samples were characterized by techniques, such as XRD, EDX, SEM and electrical characterizations. After reduction in 10% H2 and 90% N2, the DC conductivities of the Cu-CGO anodes prepared via CS-GNP and MS-GNP are found to be 5.43×103 and 1.09×104 S cm-1 at 700 °C, respectively. The electrochemical performances of the spin-coated anode symmetrical cells sintered at 700 °C are evaluated at cell operating temperatures of 600, 700 and 800 °C. The lowest area specific resistance (ASR) values for the Cu-CGO/CGO/Cu-CGO symmetrical cells prepared via the MS-GNP route at operating temperatures of 600, 700 and 800 °C are found to be 0.34, 0.71 and 1.10 Ω cm2, respectively. The as-prepared (via MS-GNP) Cu-CGO anode exhibits excellent electrical and electrochemical performance consistent with the uniform nanostructured morphology compared with the anode prepared via CS-GNP.

  12. Controlled CVD growth of Cu-Sb alloy nanostructures.

    PubMed

    Chen, Jing; Yin, Zongyou; Sim, Daohao; Tay, Yee Yan; Zhang, Hua; Ma, Jan; Hng, Huey Hoon; Yan, Qingyu

    2011-08-12

    Sb based alloy nanostructures have attracted much attention due to their many promising applications, e.g. as battery electrodes, thermoelectric materials and magnetic semiconductors. In many cases, these applications require controlled growth of Sb based alloys with desired sizes and shapes to achieve enhanced performance. Here, we report a flexible catalyst-free chemical vapor deposition (CVD) process to prepare Cu-Sb nanostructures with tunable shapes (e.g. nanowires and nanoparticles) by transporting Sb vapor to react with copper foils, which also serve as the substrate. By simply controlling the substrate temperature and distance, various Sb-Cu alloy nanostructures, e.g. Cu(11)Sb(3) nanowires (NWs), Cu(2)Sb nanoparticles (NPs), or pure Sb nanoplates, were obtained. We also found that the growth of Cu(11)Sb(3) NWs in such a catalyst-free CVD process was dependent on the substrate surface roughness. For example, smooth Cu foils could not lead to the growth of Cu(11)Sb(3) nanowires while roughening these smooth Cu foils with rough sand papers could result in the growth of Cu(11)Sb(3) nanowires. The effects of gas flow rate on the size and morphology of the Cu-Sb alloy nanostructures were also investigated. Such a flexible growth strategy could be of practical interest as the growth of some Sb based alloy nanostructures by CVD may not be easy due to the large difference between the condensation temperature of Sb and the other element, e.g. Cu or Co.

  13. Controlled CVD growth of Cu-Sb alloy nanostructures

    NASA Astrophysics Data System (ADS)

    Chen, Jing; Yin, Zongyou; Sim, Daohao; Tay, Yee Yan; Zhang, Hua; Ma, Jan; Hng, Huey Hoon; Yan, Qingyu

    2011-08-01

    Sb based alloy nanostructures have attracted much attention due to their many promising applications, e.g. as battery electrodes, thermoelectric materials and magnetic semiconductors. In many cases, these applications require controlled growth of Sb based alloys with desired sizes and shapes to achieve enhanced performance. Here, we report a flexible catalyst-free chemical vapor deposition (CVD) process to prepare Cu-Sb nanostructures with tunable shapes (e.g. nanowires and nanoparticles) by transporting Sb vapor to react with copper foils, which also serve as the substrate. By simply controlling the substrate temperature and distance, various Sb-Cu alloy nanostructures, e.g. Cu11Sb3 nanowires (NWs), Cu2Sb nanoparticles (NPs), or pure Sb nanoplates, were obtained. We also found that the growth of Cu11Sb3 NWs in such a catalyst-free CVD process was dependent on the substrate surface roughness. For example, smooth Cu foils could not lead to the growth of Cu11Sb3 nanowires while roughening these smooth Cu foils with rough sand papers could result in the growth of Cu11Sb3 nanowires. The effects of gas flow rate on the size and morphology of the Cu-Sb alloy nanostructures were also investigated. Such a flexible growth strategy could be of practical interest as the growth of some Sb based alloy nanostructures by CVD may not be easy due to the large difference between the condensation temperature of Sb and the other element, e.g. Cu or Co.

  14. Predictions of particle size and lattice diffusion pathway requirements for sodium-ion anodes using η-Cu6Sn5 thin films as a model system.

    PubMed

    Baggetto, Loïc; Jumas, Jean-Claude; Górka, Joanna; Bridges, Craig A; Veith, Gabriel M

    2013-07-14

    Geometrically well-defined Cu6Sn5 thin films were used as a model system to estimate the diffusion depth and diffusion pathway requirements of Na ions in alloy anodes. Cu6Sn5 anodes have an initial reversible capacity towards Li of 545 mA h g(-1) (Li3.96Sn or 19.8 Li/Cu6Sn5), close to the theoretical 586 mA h g(-1) (Li4.26Sn), and a very low initial irreversible capacity of 1.6 Li/Cu6Sn5 (Li0.32Sn). In contrast, the reaction with Na is limited with a reversible capacity of 160 mA h g(-1) compared to the expected 516 mA h g(-1) (Na3.75Sn). X-ray diffraction and (119)Sn-Mössbauer spectroscopy measurements show that this limited capacity likely results from the restricted diffusion of Na into the anode nanoparticles and not the formation of a low Na-content phase. Moreover, our results suggest that the η-Cu6Sn5 alloy should have optimized particle sizes of nearly 10 nm diameter to increase the Na capacity significantly. An alternative system consisting of a two-phase mixture of Cu6Sn5 and Sn of nominal composition 'Cu6Sn10' has been studied and is able to deliver a larger initial reversible storage capacity of up to 400 mA h g(-1). Finally, we have demonstrated that the presence of Cu in Cu6Sn5 and 'Cu6Sn10' suppresses the anomalous electrolyte decomposition normally observed for pure Sn.

  15. Activities of oxygen in liquid Cu-Sb and Cu-Ge alloys

    NASA Astrophysics Data System (ADS)

    Otsuka, Shinya; Matsumura, Yoshihiro; Kozuka, Zensaku

    1982-03-01

    In order to determine the activity coefficients of oxygen, γΩ in liquid Cu-Sb and Cu-Ge alloys at 1373 K as a function of alloy composition, the modified coulometric titrations, described previously, have been performed by using the galvanic cell: O in liquid Cu-Sb or Cu-Ge alloys/ZrO2 (+CaO)/Air, Pt. A pronounced point of inflection in the In γΩ vs alloy composition curve has been observed both for Cu-Sb and Cu-Ge alloys, as predicted by Jacob and Alcock’s quasichemical equation. The measured data itself, however, are significantly different from those predicted by their equation. The validity of Wagner’s solution model with one or two energy parameters has been also tested.

  16. Effect of Cu content on wear resistance and mechanical behavior of Ti-Cu binary alloys

    NASA Astrophysics Data System (ADS)

    Yu, Feifei; Wang, Hefeng; Yuan, Guozheng; Shu, Xuefeng

    2017-04-01

    Arc melting with nonconsumable tungsten electrode and water-cooled copper crucible was used to fabricate Ti-Cu binary alloys with different Cu contents in an argon atmosphere. The compositions and phase structures of the fabricated alloys were investigated by glow discharge optical emission spectroscopy (GDOES) and X-ray diffraction (XRD). Nanoindentation tests through continuous stiffness measurement were then performed at room temperature to analyze the mechanical behaviors of the alloys. Results indicated that the composition of each Ti-Cu binary alloy was Ti(100- x) Cu x ( x = 43, 60, 69, and 74 at.%). The XRD analysis results showed that the alloys were composed of different phases, indicating that different Cu contents led to the variations in alloy hardness. The wear tests results revealed that elemental Cu positively affects the wear resistance properties of the Ti-Cu alloys. Nanoindentation testing results showed that the moduli of the Ti-Cu alloys were minimally changed at increasing Cu content, whereas their hardness evidently increased according to the wear test results.

  17. Facile synthesis of dendritic Cu by electroless reaction of Cu-Al alloys in multiphase solution

    NASA Astrophysics Data System (ADS)

    Wang, Ying; Liang, Shuhua; Yang, Qing; Wang, Xianhui

    2016-11-01

    Two-dimensional nano- or micro-scale fractal dendritic coppers (FDCs) were synthesized by electroless immersing of Cu-Al alloys in hydrochloric acid solution containing copper chloride without any assistance of template or surfactant. The FDC size increases with the increase of Al content in Cu-Al alloys immersed in CuCl2 + HCl solution. Compared to Cu40Al60 and Cu45Al55 alloys, the FDC shows hierarchical distribution and homogeneous structures using Cu17Al83 alloy as the starting alloy. The growth direction of the FDC is <110>, and all angles between the trunks and branches are 60°. Nanoscale Cu2O was found at the edge of FDC. Interestingly, nanoporous copper (NPC) can also be obtained through Cu17Al83 alloy. Studies showed that the formation of FDC depended on two key factors: the potential difference between CuAl2 intermetallic and α-Al phase of dual-phase Cu-Al alloys; a replacement reaction that usually occurs in multiphase solution. The electrochemical experiment further proved that the multi-branch dendritic structure is very beneficial to the proton transfer in the process of catalyzing methanol.

  18. Facile synthesis of CuO nanoparticles as anode for lithium ion batteries with enhanced performance

    NASA Astrophysics Data System (ADS)

    Wang, Linlin; Tang, Kaibin; Zhang, Min; Zhang, Xiaozhu; Xu, Jingli

    2014-10-01

    Particle size effects on the electrochemical performance of the CuO particles toward lithium are essential. In this work, a low-cost, large-scale production but simple approach has been developed to fabricate CuO nanoparticles with an average size in 130 nm through thermolysis of Cu(OH)2 precursors. As anode materials for lithium ion batteries (LIBs), the CuO nanoparticles deliver a high reversible capacity of 540 mAh g-1 over 100 cycles at 0.5 C. It also exhibits a rate capacity of 405 mAh g-1 at 2 C. These results suggest that the facile synthetic method of producing the CuO nanoparticles can enhance cycle performance, superior to that of some different sizes of the CuO nanoparticles and many reported CuO-based anodes.

  19. Fabrication of the superhydrophobic surface on aluminum alloy by anodizing and polymeric coating

    NASA Astrophysics Data System (ADS)

    Liu, Wenyong; Luo, Yuting; Sun, Linyu; Wu, Ruomei; Jiang, Haiyun; Liu, Yuejun

    2013-01-01

    We reported the preparation of the superhydrophobic surface on aluminum alloy via anodizing and polymeric coating. Both the different anodizing processes and different polymeric coatings of aluminum alloy were investigated. The effects of different anodizing conditions, such as electrolyte concentration, anodization time and current on the superhydrophobic surface were discussed. The results showed that a good superhydrophobic surface was facilely fabricated by polypropylene (PP) coating after anodizing. The optimum conditions for anodizing were determined by orthogonal experiments. When the concentration of oxalic acid was 10 g/L, the concentration of NaCl was 1.25 g/L, anodization time was 40 min, and anodization current was 0.4 A, the best superhydrophobic surface on aluminum alloy with the contact angle (CA) of 162° and the sliding angle of 2° was obtained. On the other hand, the different polymeric coatings, such as polystyrene (PS), polypropylene (PP) and polypropylene grafting maleic anhydride (PP-g-MAH) were used to coat the aluminum alloy surface after anodizing. The results showed that the superhydrophobicity was most excellent by coating PP, while the duration of the hydrophobic surface was poor. By modifying the surface with the silane coupling agent before PP coating, the duration of the superhydrophobic surface was improved. The morphologies of the superhydrophobic surface were further confirmed by optical microscope (OM) and scanning electron microscope (SEM). Combined with the material of PP with the low surface free energy, the micro/nano-structures of the surface resulted in the superhydrophobicity of the aluminum alloy surface.

  20. Observations of a Cast Cu-Cr-Zr Alloy

    NASA Technical Reports Server (NTRS)

    Ellis, David L.

    2006-01-01

    Prior work has demonstrated that Cu-Cr-Nb alloys have considerable advantages over the copper alloys currently used in regeneratively cooled rocket engine liners. Observations indicated that Zr and Nb have similar chemical properties and form very similar compounds. Glazov and Zakharov et al. reported the presence of Cr2Zr in Cu-Cr-Zr alloys with up to 3.5 wt% Cr and Zr though Zeng et al. calculated that Cr2Zr could not exist in a ternary Cu-Cr-Zr alloy. A cast Cu-6.15 wt% Cr-5.25 wt% Zr alloy was examined to determine if the microstructure developed would be similar to GRCop-84 (Cu-6.65 wt% Cr-5.85 wt% Nb). It was observed that the Cu-Cr-Zr system did not form any Cr2Zr even after a thermal exposure at 875 C for 176.5 h. Instead the alloy consisted of three phases: Cu, Cu5Zr, and Cr.

  1. Reversion phenomena of Cu-Cr alloys

    NASA Technical Reports Server (NTRS)

    Nishikawa, S.; Nagata, K.; Kobayashi, S.

    1985-01-01

    Cu-Cr alloys which were given various aging and reversion treatments were investigated in terms of electrical resistivity and hardness. Transmission electron microscopy was one technique employed. Some results obtained are as follows: the increment of electrical resistivity after the reversion at a constant temperature decreases as the aging temperature rises. In a constant aging condition, the increment of electrical resistivity after the reversion increases, and the time required for a maximum reversion becomes shorter as the reversion temperature rises. The reversion phenomena can be repeated, but its amount decreases rapidly by repetition. At first, the amount of reversion increases with aging time and reaches its maximum, and then tends to decrease again. Hardness changes by the reversion are very small, but the hardness tends to soften slightly. Any changes in transmission electron micrographs by the reversion treatment cannot be detected.

  2. Cu--Ni--Fe anode for use in aluminum producing electrolytic cell

    DOEpatents

    Bergsma, S. Craig; Brown, Craig W.; Bradford, Donald R; Barnett, Robert J.; Mezner, Michael B.

    2006-07-18

    A method of producing aluminum in an electrolytic cell containing alumina dissolved in an electrolyte, the method comprising the steps of providing a molten salt electrolyte at a temperature of less than 900.degree. C. having alumina dissolved therein in an electrolytic cell having a liner for containing the electrolyte, the liner having a bottom and walls extending upwardly from said bottom. A plurality of non-consumable Cu--Ni--Fe anodes and cathodes are disposed in a vertical direction in the electrolyte, the cathodes having a plate configuration and the anodes having a flat configuration to compliment the cathodes. The anodes contain apertures therethrough to permit flow of electrolyte through the apertures to provide alumina-enriched electrolyte between the anodes and the cathodes. Electrical current is passed through the anodes and through the electrolyte to the cathodes, depositing aluminum at the cathodes and producing gas at the anodes.

  3. Observations Of A Cast Cu-Cr-Zr Alloy

    NASA Technical Reports Server (NTRS)

    Ellis, David L.

    2006-01-01

    The calculated phase diagram and observations of Zeng et al were confirmed. 1) Additional X-ray diffraction peaks for aged sample indicates possibility that additional metastable phases may form; 2) Cu5Zr was observed rather than the Cu9Zr2 proposed for the binary Cu-Zr phase diagram. Despite similarities between Zr and Nb, Cu-Cr-Zr does not appear to be a good candidate alloy system for rocket engine applications.

  4. Thermodynamics and surface properties of liquid Cu-B alloys

    NASA Astrophysics Data System (ADS)

    Passerone, A.; Muolo, M. L.; Valenza, F.; Novakovic, R.

    2009-09-01

    The study of the thermodynamic and the surface properties of liquid Cu-B alloys can help better understanding of a complex interfacial chemistry related to liquid Cu-brazes in contact with boride substrates. Despite a simplicity of the Cu-B phase diagram, only a few thermodynamic data are available in the literature, while in the case of the surface properties a complete lack of data is evident. The quasi-chemical approximation (QCA) for the regular solution has been applied to describe the mixing behaviour of liquid Cu-B alloys in terms of their thermodynamic and surface properties as well as the microscopic functions. In view of joining processes related to liquid Cu-brazes/solid boride systems a particular attention is paid to the surface properties of the Cu-rich part of the system and the calculated values are substantiated by the new surface tension experimental data of liquid Cu and Cu-10 at.% B alloy. The tests have been performed by the sessile-drop method under the same experimental conditions. Considering the experimental uncertainties, the effect of oxygen on the surface tension of liquid Cu and Cu-10 at.% B alloy has been analysed by simple model that combines the physical property data included in Butler's equation with the oxygen solubility data and it gives the same results as Belton's adsorption equation.

  5. Corrosion and anodic behaviour of zinc and its ternary alloys in alkaline battery electrolytes

    NASA Astrophysics Data System (ADS)

    Suresh Kannan, A. R.; Muralidharan, S.; Sarangapani, K. B.; Balaramachandran, V.; Kapali, V.

    Several attempts are being made to avoid the use of mercury-bearing zinc/zinc alloys as anodes in alkaline power sources. The work presented here suggests the possible use of some ternary alloys based on zinc of purity 99.9 to 99.95 wt.% as anodes in 10 M NaOH solution with sodium citrate, sodium stannate and calcium oxide as complexing agents and inhibitors. The corrosion of zinc and its alloys in 10 M NaOH solution is under cathodic control; in other alkaline electrolytes, it is under anodic control. Anode efficiency of up to 99.0% is achieved. The corrosion rates of zinc and its alloys are found to be comparable with those of mercury-bearing zinc in the chosen electrolytes. It is concluded that both dry cells and Zn-air batteries can be constructed with the above anodes and alkaline electrolytes. Thus, the presence of mercury, either in the anode or in the electrolyte, is avoided.

  6. Giant magnetoresistance of Co-Ni-Cu alloys produced by mechanical alloying

    NASA Astrophysics Data System (ADS)

    Zhang, Y. Q.; Zhang, Z. D.; Xiao, Q. F.; Geng, D. Y.; Zhao, X. G.; Zhang, W. S.; You, C. Y.

    2003-05-01

    The structure, magnetic properties and magnetoresistance (MR) effect of Co20NixCu80-x alloys produced by mechanical alloying and subsequent annealing have been investigated. After milling for 5 h, a supersaturated solid solution forms for all the alloys. Co20NixCu80-x alloys annealed at 973 K for 30 min segregated into two-phases of fcc-Co and fcc-Cu. The maximum value for MR ratio, at room temperature is 4.7% at a field of 1.2 T, and at 5 K is 15% at a field of 2 T for Co20Cu80 annealed at 718 K for 30 min. The MR ratio of Co-Ni-Cu alloys decreases monotonically with increasing Ni content. The MR and its dependence on particle size are discussed.

  7. Influence of Cu content on the cell biocompatibility of Ti-Cu sintered alloys.

    PubMed

    Zhang, Erlin; Zheng, Lanlan; Liu, Jie; Bai, Bing; Liu, Cong

    2015-01-01

    The cell toxicity and the cell function of Ti-Cu sintered alloys with different Cu contents (2, 5, 10 and 25 wt.%, respectively) have been investigated in comparison with commercial pure titanium in order to assess the influence of Cu content on the cell biocompatibility of the Ti-Cu alloys. The cytotoxicity was studied by examining the MG63 cell response by CCK8 assessment. The cell morphology was evaluated by acridine orange/ethidium bromide (AO/EB) fluorescence and observed under scanning electronic microscopy (SEM). The cell function was monitored by measuring the AKP activity. It has been shown by the AO/EB morphology results that the cell death on both cp-Ti sample and Ti-Cu samples is due to apoptosis rather than necrosis. Although more apoptotic cells were found on the Ti-2Cu and Ti-5Cu samples, no evidence of Cu content dependent manner of apoptosis has been found. SEM observation indicated very good cell adhesion and spread on the cp-Ti sample and the Ti-Cu samples with different Cu contents. CCK8 results displayed that increase in the Cu content in Ti-Cu alloys does not bring about any difference in the cell viability. In addition, AKP test results indicated that no difference in the differentiation of MG63 was found between the cp-Ti and the Ti-Cu samples and among the Ti-Cu samples. All results indicated that Ti-Cu alloys exhibit very good cell biocompatibility and the Cu content up to 25 wt.% in the Ti-Cu alloys has no influence on the cell proliferation and differentiation.

  8. Dendrite-Free Potassium-Oxygen Battery Based on a Liquid Alloy Anode.

    PubMed

    Yu, Wei; Lau, Kah Chun; Lei, Yu; Liu, Ruliang; Qin, Lei; Yang, Wei; Li, Baohua; Curtiss, Larry A; Zhai, Dengyun; Kang, Feiyu

    2017-09-20

    The safety issue caused by the dendrite growth is not only a key research problem in lithium-ion batteries but also a critical concern in alkali metal (i.e., Li, Na, and K)-oxygen batteries where a solid metal is usually used as the anode. Herein, we demonstrate the first dendrite-free K-O2 battery at ambient temperature based on a liquid Na-K alloy anode. The unique liquid-liquid connection between the liquid alloy and the electrolyte in our alloy anode-based battery provides a homogeneous and robust anode-electrolyte interface. Meanwhile, we manage to show that the Na-K alloy is only compatible in K-O2 batteries but not in Na-O2 batteries, which is mainly attributed to the stronger reducibility of potassium and relatively more favorable thermodynamic formation of KO2 over NaO2 during the discharge process. It is observed that our K-O2 battery based on a liquid alloy anode shows a long cycle life (over 620 h) and a low discharge-charge overpotential (about 0.05 V at initial cycles). Moreover, the mechanism investigation into the K-O2 cell degradation shows that the O2 crossover effect and the ether-electrolyte instability are the critical problems for K-O2 batteries. In a word, this study provides a new route to solve the problems caused by the dendrite growth in alkali metal-oxygen batteries.

  9. Spin density waves in dilute CuMn alloys

    SciTech Connect

    Cable, J.W. ); Tsunoda, Y. )

    1993-05-15

    Neutron scattering studies on concentrated CuMn alloys show static spin density waves (SDW) that are incommensurate with the lattice and which become dynamic above the freezing temperature [ital T][sub [ital f

  10. Adsorption orientation of sodium of polyaspartic acid effect on anodic films formed on magnesium alloy

    NASA Astrophysics Data System (ADS)

    Liu, YuPing; Zhang, Dingfei; Chen, Changguo; Zhang, Jiangang; Cui, libo

    2011-06-01

    We previously reported organic addition agent in improving the performance of anodic film formed on magnesium alloy. Here we report that the environment-friendly electrolyte with sodium of polyaspartic acid (PASP) affects the anodizing process including the microstructure, phase constituents and corrosion performance. We have used SEM, XRD, XPS and polarization curve to study in detail the electrolyte impact. Our results show that the anodic film in electrolyte with 19.2-28.8 g/L PASP is compact, smooth and high corrosion resistant. And also, increasing the PASP concentration ranging from 9.6 to 28.8 g/L results in enhancing the cell voltage, thickness and the content of compound including MgO and Mg 2SiO 4 in anodic film. Interestingly, the anodic film is non-stoichiometric oxide. Comparing with Tafel curves of the anodic film to the addition of PASP or not to, the corrosion current density is 1-2 magnitudes less than the later. Furthermore, a plausible model we propose that the anodizing process is regulated by two main plausible adsorption orientations of PASP at the surface anode. With the increasing of PASP content, the adsorption orientation may transit from "end-on" to "flat-on". This research using organic addition agent PASP may further broaden applications of organic additive in the anti-corrosion engineering and electrochemical surface treatment of magnesium alloy.

  11. Novel alloys to improve the electrochemical behavior of zinc anodes for zinc/air battery

    NASA Astrophysics Data System (ADS)

    Lee, Chang Woo; Sathiyanarayanan, K.; Eom, Seung Wook; Yun, Mun Soo

    In our continued efforts for improving the performance of zinc anodes for a Zn/air battery, we now report the preparation of three alloys and improved performances of anodes made up with these alloys. The alloys contained zinc, nickel, and indium with different weight percentages and were calcined at two different temperatures. Out of the six alloys, the alloy which has a composition of zinc 90%, nickel 7.5% and Indium 2.5% and fired at 500 °C is found to be the best. In the case of the hydrogen evolution reaction, this alloy had its potential shifted to a more negative potential. As far as the cyclic voltammograms were concerned, the difference between the anodic and cathodic part was minimal when compared with other alloys. Surprisingly, this alloy had reversibility even after 100 cycles of the cyclic voltammogram. This is a clear indication that dendrite formation was reduced to a considerable extent. Images taken with a scanning electron microscope also indicated reduced dendrite formation.

  12. FeSn2-TiC nanocomposite alloy anodes for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Leibowitz, Joshua; Allcorn, Eric; Manthiram, Arumugam

    2015-11-01

    FeSn2-TiC nanocomposite alloy anodes for lithium-ion batteries have been synthesized by a mechanochemical process involving high-energy mechanical milling of Fe/Ti, Ti/Sn, and carbon black. Characterization of the nanocomposites formed with x-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) reveals that this alloy is composed of crystalline nanoparticles of FeSn2 dispersed in a matrix of TiC. The FeSn2-TiC alloy shows an initial gravimetric capacity of 511 mAh g-1 (1073 mAh cm-3) with a first-cycle coulombic efficiency of 77% and a tap density of 2.1 g cm-3. The TiC buffer matrix in the nanocomposite anode accommodates the large volume change occurring during the charge-discharge process and leads to good cyclability compared to similar Sn-based anodes.

  13. Magnetic properties of Co-Cu metastable solid solution alloys

    NASA Astrophysics Data System (ADS)

    Fan, Xu; Mashimo, Tsutomu; Huang, Xinsheng; Kagayama, Tomoko; Chiba, Akira; Koyama, Keiichi; Motokawa, Mitsuhiro

    2004-03-01

    Metastable solid solution alloy powders and bulk alloys in the cobalt(Co)-copper(Cu) (10 90 mol % Co) system, which is an almost immiscible system at the ambient state, were prepared by mechanical alloying (MA) and shock compression. All MA-treated powders showed the x-ray diffraction patterns of a single phase of fcc structure. The lattice parameter increases with Cu concentration and is fundamentally on the line with Vegard’s law. The magnetization curves of CoxCu100-x (x=20 80) metastable bulk alloys at room temperature showed ferromagnetism, while the one of Co10Cu90 system showed paramagnetism. The saturation magnetic moment (Ms) curve versus electron numbers per atom at 0 K was found to be similar to the Slater-Pauling curves of other transition-metal binary systems and decreased with increasing Cu concentration and approached zero at about 28.8 electrons per atom. The magnetoresistance ratio at room temperature increased with Cu content in the ferromagnetic region, while the one of the paramagnetic Co10Cu90 alloy was negligibly small.

  14. Liquid K-Na Alloy Anode Enables Dendrite-Free Potassium Batteries.

    PubMed

    Xue, Leigang; Gao, Hongcai; Zhou, Weidong; Xin, Sen; Park, Kyusung; Li, Yutao; Goodenough, John B

    2016-11-01

    A K-Na liquid alloy allows a dendrite-free high-capacity anode; its immiscibility with an organic liquid electrolyte offers a liquid-liquid anode-electrolyte interface. Working with a sodiated Na2 MnFe(CN)6 cathode, the working cation becomes K(+) to give a potassium battery of long cycle life with an acceptable capacity at high charge/discharge rates.

  15. X-Ray Investigations on Molten Cu-Sb Alloys

    NASA Astrophysics Data System (ADS)

    Halm, Th.; Neumann, H.; Hoyer, W.

    1994-05-01

    Using X-ray diffraction, structure factors and pair correlation functions of several molten Cu-Sb alloys and pure antimony were determined and compared with published structural, thermodynamic and electronic properties. The eutectic concentration Cu37Sb63 was investigated in dependence on temperature, and a model structure factor was calculated applying a segregation model.

  16. Effect of preliminary plastic deformation on the anodic behavior of molybdenum-rhenium alloys

    SciTech Connect

    Amirkhanova, N.A.; Tatarinova, O.M.

    1988-07-01

    Two molybdenum-rhenium alloys obtained by the method of vacuum melting and containing 20% and 40% rhenium were investigated for their anodic behavior following heating and bulk forging to develop different degrees of deformation. Their stationary potentials were determined in solutions of a number of sodium salts and polarization measurements were made using a rotating disk electrode. The rate of removal for different working-stress values was determined on an apparatus simulating the electrochemical sizing process. Surface microstructure was observed by metallographic microscopy. The increase in the rate of anodic dissolution of the alloys was determined to be correct for degrees of deformation to 10%.

  17. Strengthening in rapidly solidified age hardened Cu-Cr and Cu-Cr-Zr alloys

    SciTech Connect

    Correia, J.B.; Davies, H.A.; Sellars, C.M.

    1997-01-01

    Cu-Cr and Cu-Cr-Zr alloy powders were produced by water atomization and consolidated by warm extrusion. Coherent Cr precipitation is associated with the peak hardness condition in these alloys. The mechanical properties obtained after aging treatments, namely the peak hardness, and the corresponding proof stress are related to the concentration of the alloying element initially in solid solution in the powders. The strengthening observed is interpreted in terms of theories of precipitation and dispersion strengthening and compared with similar analyses reported previously in the literature for these alloy systems.

  18. Structural evolution, thermomechanical recrystallization and electrochemical corrosion properties of Ni-Cu-Mg amorphous coating on mild steel fabricated by dual-anode electrolytic processing

    NASA Astrophysics Data System (ADS)

    Abdulwahab, M.; Fayomi, O. S. I.; Popoola, A. P. I.

    2016-07-01

    The electrolytic Ni-Cu based alloy coating with admixed interfacial blend of Mg have been successfully prepared on mild steel substrate by dual anode electroplating processes over a range of applied current density and dwell time. The electrocodeposition of Ni-Cu-Mg coating was investigated in the presence of other bath additives. The influence of deposition current on surface morphology, adhesion behavior, preferred crystal orientation, surface topography and electrochemical activity of Ni-Cu-Mg alloy coating on mild steel were systematically examined. The thermal stability of the developed composite materials was examined via isothermal treatment. Scanning electron microscope equipped with EDS, X-ray diffraction, Atomic force microscope, micro-hardness tester and 3 μmetrohm Potentiostat/galvanostat were used to compare untreated and isothermally treated electrocodeposited composite. The induced activity of the Ni-Cu-Mg alloy changed the surface modification and results to crystal precipitation within the structural interface by the formation of Cu, Ni2Mg3 phase. The obtained results showed that the introduction of Mg particles in the plating bath generally modified the surface and brings an increase in the hardness and corrosion resistance of Ni-Cu-Mg layers fabricated. Equally, isothermally treated composites demonstrated an improved properties indicating 45% increase in the micro-hardness and 79.6% corrosion resistance which further showed that the developed composite is thermally stable.

  19. Spark anodization of titanium-zirconium alloy: surface characterization and bioactivity assessment.

    PubMed

    Sharma, Ajay; McQuillan, A James; Sharma, Lavanya A; Waddell, John Neil; Shibata, Yo; Duncan, Warwick John

    2015-08-01

    Titanium (Ti) and its alloys have been popularly used as implant biomaterial for decades. Recently, titanium-zirconium (TiZr) alloy has been developed as an alternative implant material with improved strength in load bearing areas. Surface modification is one of the key factors to alter the surface properties to hasten osseointegration. Spark anodic oxidation (anodization) is one such method that is reported to enhance the bone formation around implants. This study aims to anodize TiZr and study its surface characteristics and cytocompatibility by cell culture experiments using osteoblast-like cells. Titanium (Ti) and TiZr discs were anodized in an electrolyte containing DL-α-glycerophosphate and calcium acetate (CA) at 300 V. The surface characteristics were analyzed by scanning electron microscopy, electron dispersive spectroscopy, X-ray diffraction (XRD), atomic force microscopy and goniometry. Using osteoblast-like cells viability, proliferation, differentiation and mineralization was assessed. The anodized surfaces demonstrated increased oxygen, entrapped calcium and phosphorous from the electrolyte used. XRD analysis confirmed the presence of anatase in the oxide layer. Average roughness increased and there was a significant decrease in contact angle (P < 0.01) following anodization. The anodized TiZr (aTiZr) surfaces were more nano-porous compared to anodized Ti (aTi). No significant difference was found in the viability of cells, but after 24 h the total number of cells was significantly higher (P < 0.01). Proliferation, alkaline phosphatase activity and calcium deposits were significantly higher on anodized surfaces compared to machined surfaces (P < 0.05, ANOVA). Anodization of TiZr resulted in a more nanoporous and hydrophilic surface than aTi, and osteoblast biocompatibility appeared comparable to aTi.

  20. Bone Cell–materials Interactions and Ni Ion Release of Anodized Equiatomic NiTi Alloy

    PubMed Central

    Bernard, Sheldon A.; Balla, Vamsi Krishna; Davies, Neal M.; Bose, Susmita; Bandyopadhyay, Amit

    2011-01-01

    Laser processed NiTi alloy was anodized for different durations in H2SO4 electrolyte with varying pH to create biocompatible surfaces with low Ni ion release as well as bioactive surfaces to enhance biocompatibility and bone cell-materials interactions. The anodized surfaces were assessed for their in vitro cell-materials interactions using human fetal osteoblast (hFOB) cells for 3, 7 and 11 days, and Ni ion release up to 8 weeks in simulated body fluids. The results were correlated with surface morphologies of anodized surfaces characterized using field-emission scanning electron microscopy (FESEM). The results show that the anodization creates a surface with nano/micro roughness depending on anodization conditions. The hydrophilicity of NiTi surface was found to improve after anodization due to lower contact angles in cell media, which dropped from 32° to < 5°. The improved wettability of anodized surfaces is further corroborated by their high surface energy comparable to that of cp Ti. Relatively high surface energy, especially polar component, and nano/micro surface features of anodized surfaces significantly increased the number of living cells and their adherence and growth on these surfaces. Finally, a significant drop in Ni ion release from 268 ± 11 to 136 ± 15 ppb was observed for NiTi surfaces after anodization. This work indicates that anodization of NiTi alloy has a positive influence on the surface energy and surface morphology, which in turn improve bone cell-materials interactions and reduce Ni ion release in vitro. PMID:21232641

  1. Development of corrosion resistant aluminum heat exchanger, Part 1: Development of new aluminum alloy sheets for sacrificial anode

    SciTech Connect

    Hagiwara, M.; Baba, Y.; Tanabe, Z.; Miura, T.; Hasegawa, Y.; Iijima, K.

    1986-01-01

    The sacrificial anodic effect of Al-Zn alloy reduced markedly in aluminium heat exchanger as car air conditioner manufactured by vacuum brazing conventionally used, as zinc elements preferentially evaporate in vacuum-heating. It was found that Al-Sn alloy had superior electrochemical characteristics than Al-Zn alloy (AA7072) as the sacrificial anodic material used in vacuum brazing. According to many experimental results, the new brazing sheet-fin with Al-Mn-Sn alloy core metal has been developed. This fin has favorable formability and prominent sacrificial anodic effect. Therefore, this fin is excellent material for car air conditioner manufactured by vacuum brazing.

  2. Supercoducting property of Zr-Cu-Al-Ni-Nb alloys

    NASA Astrophysics Data System (ADS)

    Okai, D.; Motoyama, G.; Kimura, H.; Inoue, A.

    The superconducting property of Zr55Cu(30-X)Al10Ni5NbX alloys prepared by arc melting and liquid quenching methods was investigated by magnetic susceptibility measurements. The crystalline alloys with X = 0∼25 at.% prepared by arc melting method exhibited superconductivity with maximum Tc,on of 10.1 K. The alloys (X = 10∼23 at.%) with crystalline particles embedded in an amorphous structure, which were fabricated by melt spinning method, showed superconductivity with Tc,on of less than 4.0 K. The superconducting property of the Zr-Cu-Al-Ni-Nb alloys was attributed to superconducting phases of Zr2Cu, Zr2Ni, Zr65Al10Nb25 and Zr-Nb contained in the Zr-Cu-Al-Ni-Nb alloys. The melt-spun Zr55Cu(30-X)Al10Ni5NbX (X = 10∼20 at.%) alloys exhibited glass transition at 718∼743 K and were found to be superconducting metallic glasses.

  3. Anodic oxidation of a Co–Ni–Cr–Mo alloy and its inhibitory effect on platelet activation.

    PubMed

    Nagai, Akiko; Suzuki, Yuta; Tsutsumi, Yusuke; Nozaki, Kosuke; Wada, Norio; Katayama, Keiichi; Hanawa, Takao; Yamashit, Kimihiro

    2014-05-01

    In this study, surface treatment of a Co–Ni–Cr–Mo alloy (MP35N) was attempted to attain biocompatibility using an anodic oxidation technique. To determine the optimal condition of the anodic oxidation treatment for stent applications, anodic polarization of the alloy was first conducted. After anodic oxidation, the surface topology and wettability were examined, and the composition and chemical states of the surface oxide were characterized. For biocompatibility, stent surfaces must have both cell adhesion and antithrombogenic properties. Therefore, the anodically oxidized surface was assessed with an endothelial cell attachment test and an in vitro platelet adhesion test. The results indicated that the topography, wettability, and composition of the surface oxide film on the alloy were changed by anodic oxidation at a voltage near the passive and transpassive region. The surface roughness and wettability increased after anodic oxidation. The major content of the oxide layer after anodic oxidation was Cr containing a small amount of Mo, and Ni and Co were almost eliminated from the layer. Platelet activation of the alloy decreased significantly after anodic oxidation at an optimal potential, whereas the cytocompatibility remained constant. Therefore, the anodic oxidation is an effective process for treating this alloy for stent applications.

  4. Electroless Cu Plating on Anodized Al Substrate for High Power LED.

    PubMed

    Rha, Sa-Kyun; Lee, Youn-Seoung

    2015-03-01

    Area-selective copper deposition on screen printed Ag pattern/anodized Al/Al substrate was attempted using a neutral electroless plating processes for printed circuit boards (PCBs), according to a range of variation of pH 6.5-pH 8 at 70 °C. The utilized basic electroless solution consisted of copper(II) sulfate pentahydrate, sodium phosphinate monohydrate, sodium citrate tribasic dihydrate, ammonium chloride, and nickel(II) sulfate hexahydrate. The pH of the copper plating solutions was adjusted from pH 6.5 to pH 8 using NH4OH. Using electroless plating in pH 6.5 and pH 7 baths, surface damage to the anodized Al layer hardly occurred; the structure of the plated Cu-rich films was a typical fcc-Cu, but a small Ni component was co-deposited. In electroless plating at pH 8, the surface of the anodized Al layer was damaged and the Cu film was composed of a lot of Ni and P which were co-deposited with Cu. Finally, in a pH 7 bath, we can make a selectively electroless plated Cu film on a PCB without any lithography and without surface damage to the anodized Al layer.

  5. Electrochemical behavior of anodized AA7075-T73 alloys as affected by the matrix structure

    NASA Astrophysics Data System (ADS)

    Huang, Yung-Sen; Shih, Teng-Shih; Chou, Jun-Hung

    2013-10-01

    A set of standard 7075-T73 alloy samples was prepared for comparison with samples that had been cold-rolled before the T73 treatment. One set of samples was subjected to cold rolling at room temperature and another deep-cooled in liquid nitrogen prior to rolling. Both sets of samples were then subjected to a T73 treatment. The microstructure of the different samples was observed and their micro-hardness was tested and recorded. The samples that had first been subjected to the deep-cooling treatment prior to rolling and T73 treatment (CRST73) showed few subgrains and smaller amounts of second phase particles in the matrix than was the case with the other two sets of samples. The experimental results also indicated that the matrix of the CRST73 samples mostly displayed disk-like precipitates of Mg2Zn and Al2Cu. After anodization, this batch of samples demonstrated superior corrosion resistance and the lowest passive current density during potentiodynamic polarization testing.

  6. Droplet Growth in Undercooled Cu-Co Alloys

    NASA Technical Reports Server (NTRS)

    Robinson, Michael B.; Li, Delin; Rathz, Thomas J.; Williams, Gary A.

    1999-01-01

    High undercooling usually leads to the refinement of microstructures, while an opposite tendency occurs in liquid immiscible alloys. In the Cu-Co system, there is a metastable liquid miscibility gap which may allow the study of droplet nucleation and growth by undercooling experiments. In the present work, two alloys of Cu50Co50 and Cu68Co32 (atomic) were undercooled using a melt fluxing technique in which the liquid separation temperature could be directly measured. It was observed that after separation the resultant melts were further undercooled by 315 K prior to solidification. The relationship between the largest droplet radius and undercooling was found to exhibit three regimes: a power law growth, linear growth, and saturation stage. In addition to dendrites and droplet-like morphology reported previously, an interconnected structure was formed for the Cu50Co50 alloy at intermediate undercooling. It played a crucial role in droplet coarsening at high undercooling.

  7. CuLi{sub 2}Sn and Cu{sub 2}LiSn: Characterization by single crystal XRD and structural discussion towards new anode materials for Li-ion batteries

    SciTech Connect

    Fürtauer, Siegfried; Effenberger, Herta S.; Flandorfer, Hans

    2014-12-15

    The stannides CuLi{sub 2}Sn (CSD-427095) and Cu{sub 2}LiSn (CSD-427096) were synthesized by induction melting of the pure elements and annealing at 400 °C. The phases were reinvestigated by X-ray powder and single-crystal X-ray diffractometry. Within both crystal structures the ordered CuSn and Cu{sub 2}Sn lattices form channels which host Cu and Li atoms at partly mixed occupied positions exhibiting extensive vacancies. For CuLi{sub 2}Sn, the space group F-43m. was verified (structure type CuHg{sub 2}Ti; a=6.295(2) Å; wR{sub 2}(F²)=0.0355 for 78 unique reflections). The 4(c) and 4(d) positions are occupied by Cu atoms and Cu+Li atoms, respectively. For Cu{sub 2}LiSn, the space group P6{sub 3}/mmc was confirmed (structure type InPt{sub 2}Gd; a=4.3022(15) Å, c=7.618(3) Å; wR{sub 2}(F²)=0.060 for 199 unique reflections). The Cu and Li atoms exhibit extensive disorder; they are distributed over the partly occupied positions 2(a), 2(b) and 4(e). Both phases seem to be interesting in terms of application of Cu–Sn alloys as anode materials for Li-ion batteries. - Highlights: • First single crystal investigation of CuLi{sub 2}Sn and Cu{sub 2}LiSn clarifies contradictions from literature. • Lithium atoms are ordered in channels, which is interesting for application as anode materials for lithium ion batteries. • Structural relationships to binary Cu–Sn-phases are shown. • Close structural relationship between both ternary phases exists.

  8. Au-Ag-Cu nano-alloys: tailoring of permittivity

    PubMed Central

    Hashimoto, Yoshikazu; Seniutinas, Gediminas; Balčytis, Armandas; Juodkazis, Saulius; Nishijima, Yoshiaki

    2016-01-01

    Precious metal alloys enables new possibilities to tailor materials for specific optical functions. Here we present a systematic study of the effects of a nanoscale alloying on the permittivity of Au-Ag-Cu metals at 38 different atomic mixing ratios. The permittivity was measured and analyzed numerically by applying the Drude model. X-ray diffraction (XRD) revealed the face centered cubic lattice of the alloys. Both, optical spectra and XRD results point towards an equivalent composition-dependent electron scattering behavior. Correlation between the fundamental structural parameters of alloys and the resulting optical properties is elucidated. Plasmonic properties of the Au-Ag-Cu alloy nanoparticles were investigated by numerical simulations. Guidelines for designing plasmonic response of nano- structures and their patterns are presented from the material science perspective. PMID:27118459

  9. Au-Ag-Cu nano-alloys: tailoring of permittivity

    NASA Astrophysics Data System (ADS)

    Hashimoto, Yoshikazu; Seniutinas, Gediminas; Balčytis, Armandas; Juodkazis, Saulius; Nishijima, Yoshiaki

    2016-04-01

    Precious metal alloys enables new possibilities to tailor materials for specific optical functions. Here we present a systematic study of the effects of a nanoscale alloying on the permittivity of Au-Ag-Cu metals at 38 different atomic mixing ratios. The permittivity was measured and analyzed numerically by applying the Drude model. X-ray diffraction (XRD) revealed the face centered cubic lattice of the alloys. Both, optical spectra and XRD results point towards an equivalent composition-dependent electron scattering behavior. Correlation between the fundamental structural parameters of alloys and the resulting optical properties is elucidated. Plasmonic properties of the Au-Ag-Cu alloy nanoparticles were investigated by numerical simulations. Guidelines for designing plasmonic response of nano- structures and their patterns are presented from the material science perspective.

  10. Ethylene binding to Au/Cu alloy nanoparticles

    NASA Astrophysics Data System (ADS)

    Gammage, Michael D.; Stauffer, Shannon; Henkelman, Graeme; Becker, Michael F.; Keto, John W.; Kovar, Desiderio

    2016-11-01

    Weak chemisorption of ethylene has been shown to be an important characteristic in the use of metals for the separation of ethylene from ethane. Previously, density functional theory (DFT) has been used to predict the binding energies of various metals and alloys, with Ag having the lowest chemisorption energy amongst the metals and alloys studied. Here Au/Cu alloys are investigated by a combination of DFT calculations and experimental measurements. It is inferred from experiments that the binding energy between a Au/Cu alloy and ethylene is lower than to either of the pure metals, and DFT calculations confirm that this is the case when Au segregates to the particle surface. Implications of this work suggest that it may be possible to further tune the binding energy with ethylene by compositional and morphological control of films produced from Au-surface segregated alloys.

  11. Anodic treatment of magnesium alloys, acid type, full coat. (SAE standard)

    SciTech Connect

    1995-02-01

    This specification establishes the engineering requirements for producing an acid-type, anodic coating on magnesium alloys and the properties of the coating. This process has been used typically to increase corrosion and abrasion resistance and to provide surfaces which will ensure maximum paint adheresion, but usage is not limited to such applications. This process is applicable to all magnesium alloys provided proper allowance is made for dimensional change.

  12. Thermal stability of active/inactive nanocomposite anodes based on Cu2Sb in lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Allcorn, Eric; Kim, Sang-Ok; Manthiram, Arumugam

    2015-12-01

    Various active/inactive nanocomposites of Cu2Sb-Al2O3@C, Cu2Sb-TiC, and Cu2Sb-TiC@C have been synthesized by high energy mechanical milling and investigated by differential scanning calorimetry (DSC) to determine the lithiated phase stability and heat generation arising from these electrodes. The milling process reduces the Li3Sb phase stability, relative to the un-milled samples, to below ∼200 °C. However, the incorporation of the reinforcing, inactive phases Al2O3, TiC, and carbon black offer a slight improvement. DSC curves also show that the low-temperature heat generation in the SEI-layer reaction range is not noticeably altered by either the milling process or the addition of the inactive phases. A strong exothermic peak is observed at ∼200 °C for the 0% state of charge electrodes of Cu2Sb-Al2O3@C and Cu2Sb-TiC@C that was caused by the incorporation of carbon black into the composite. This peak was not present in the electrodes of milled Cu2Sb or Cu2Sb-TiC, suggesting that efforts to extend the cycle life of alloy anodes should avoid carbon black due to its destabilizing effects on delithiated electrodes. Fourier Transform infrared spectroscopy analysis indicates that the reaction arising from the incorporation of carbon black is tied to a low-temperature breakdown of the lithium salt LiPF6.

  13. Anodic nanoporous SnO2 grown on Cu foils as superior binder-free Na-ion battery anodes

    NASA Astrophysics Data System (ADS)

    Bian, Haidong; Zhang, Jie; Yuen, Muk-Fung; Kang, Wenpei; Zhan, Yawen; Yu, Denis Y. W.; Xu, Zhengtao; Li, Yang Yang

    2016-03-01

    We present a convenient, low-cost strategy to fabricate one-dimensional, vertically oriented nanoporous assembly of SnO2 upon a Cu substrate as a potentially promising anode system for Na-ion batteries application. The major novelty of the fabrication stage resides in anodizing a Sn/Cu bilayer film that is created by a facile cold-rolling procedure amenable to large-scale production. The open, nanoporous morphology of SnO2 facilitates the diffusion of electrolytes to access the SnO2 surface. The high porosity of the SnO2 phase also provides large void space to effectively accommodate the volume expansion/contraction during sodiation/desodiation. As a result, the 1-D nanoporous SnO2 thus assembled on the Cu substrate can be directly used as an effective electrode system for Na-ion storage-without the need for additives, delivering a remarkable capacity of 326 mA h g-1 over 200 cycles at a current rate of 0.2 C.

  14. Dissolution of Plutonium Scrub Alloy and Anode Heel Materials in H-Canyon

    SciTech Connect

    PIERCE, RA

    2004-04-12

    H-Canyon has a ''gap'' in dissolver operations during the last three months of FY03. One group of material to be processed during the gap is pre-existing scrub alloy material. There are 14 cans of material containing approximately 3.8 kilograms of plutonium. Of the 14 cans, it was anticipated that four cans contain salts, two cans contain anode heel materials, and eight cans contain scrub alloy buttons. H-Canyon desires to process the materials using a flowsheet similar to the SS and C (sand, slag and crucible) dissolution flowsheet used in F-Canyon. The materials will be loaded into carbon steel cans and then placed into aluminum metal charging bundles. Samples were sent to Savannah River Technology Center (SRTC) for characterization and flowsheet testing -- four MSE salts, two anode heels, and seven scrub alloy buttons. SRTC dissolved and characterized each of the samples. Two of them, originally thought to be MSE salts, were found to be graphite mold materials and were unsuitable for processing in H-Canyon. Characterization studies confirmed that the identification of the remaining items as MSE salts, scrub alloy buttons, and anode heel materials was correct. The MSE salts and anode heels solids are comprised primarily of plutonium, potassium, sodium and chloride. Both the MSE salts and anode heels left behind small amounts of residual solids. The scrub alloy buttons are comprised primarily of plutonium and aluminum. The solids dissolve readily with light, effervescent gas generation at the material surface and only trace amounts of NOx generation. Of the seven button samples, four dissolved completely. Two button samples contained small amounts of tantalum that did not dissolve. The last of the seven scrub alloy samples left a trace amount of residual plutonium solids. It is anticipated that the presence of undissolved fissile material is a function of where the sample was located relative to the button surface.

  15. Template-free electrodeposition of AlFe alloy nanowires from a room-temperature ionic liquid as an anode material for Li-ion batteries.

    PubMed

    Chen, Gang; Chen, Yuqi; Guo, Qingjun; Wang, Heng; Li, Bing

    2016-08-15

    AlFe alloy nanowires were directly electrodeposited on copper substrates from trimethylamine hydrochloride (TMHC)-AlCl3 ionic liquids with small amounts of FeCl3 at room temperature without templates. Coin cells composed of AlFe alloy nanowire electrodes and lithium foils were assembled to characterize the alloy electrochemical properties by galvanostatic charge/discharge tests. Effects of FeCl3 concentration, potential and temperature on the alloy morphology, composition and cyclic performance were examined. Addition of Fe into the alloy changed the nanowires from a 'hill-like' bulk morphology to a free-standing morphology, and increased the coverage area of the alloy on Cu substrates. As an inactive element, Fe could also buffer the alloys' large volume changes during Li intercalation and deintercalation. AlFe alloy nanowires composed of a small amount of Fe with an average diameter of 140 nm exhibited an outstanding cyclic performance and delivered a specific capacity of about 570 mA h g(-1) after 50 cycles. This advanced template-free method for the direct preparation of high performance nanostructure AlFe alloy anode materials is quite simple and inexpensive, which presents a promising prospect for practical application in Li-ion batteries.

  16. The Effects of Joining Methods on the Resistivity of W-Cu Alloy and Cu Joint

    NASA Astrophysics Data System (ADS)

    Chen, Chunhuan; Liu, Xiaojing; Wang, Zhenbo

    In this paper, three joining methods are employed to join W-Cu alloy and Cu to investigate the effect of joining methods on the resistivity of the joint. The results show that W-Cu alloy is well bonding to the Cu substrate when joining by diffusion vacuum bonding and brazing in vacuum methods. Welding defects is apt to occur when joining by brazing in air. The lowest resistivity of the joint welded is obtained by vacuum diffusion bonding, which approximates to the W-Cu alloy while that for the joint brazed in air is the highest. Vacuum diffusion bonding method is the best choice when the demand of conductivity is vital while the mechanical reliability is not critical. Otherwise, brazing in vacuum is the prior option.

  17. Electrochemical Properties of Al-Cu Alloys in Nacl Solutions

    NASA Astrophysics Data System (ADS)

    Roman, Alejandra Silvina; Méndez, Claudia Marcela; Schvezov, Carlos Enrique; Ares, Alicia Esther

    In this paper the structure of aluminum based alloys and their corrosion behavior by using different electrochemical techniques as characterization methods are considered. Currently, it becomes imperative to know the role of the Al2Cu against the susceptibility to corrosion of these alloys. The present work aims to studying the electrochemical behavior of aluminum base alloys with the following compositions: Al-1wt.%Cu, Al-4.5wt.%Cu and Al-15wt.%Cu (with different grain structures), in 1M NaCl solutions, at room temperature. Cyclic potentiodynamic polarization tests were performed and were found that the alloys with more than 1wt.%Cu in the matrix have an unstable behavior and without tendency to reach passivity. The equivalent circuits derived from electrochemical impedance spectroscopy technique (EIS) generally showed two capacitive contributions. The susceptibility to corrosion becomes a complex function, not only of copper concentration and structure, but also with interdendritic spacings and distribution of phases in the alloys.

  18. Spin density waves in dilute CuMn alloys

    SciTech Connect

    Cable, J.W. ); Tsunoda, Y. )

    1992-01-01

    Neutron scattering studies on concentrated CuMn alloys show static spin density waves (SDW) that are incommensurate with the lattice and which become dynamic above the freezing temperature T[sub f] with a dispersion relation that is essentially vertical. We have examined the existence of both the static and the dynamic SDW in dilute CuMn alloys where the Mn atoms may be separated beyond the range of SDW stability. There is no such cutoff range in the Overhauser SDW model where the transition temperature is simply linear with concentration, but a recent calculation by loffe and Feigel'man gives magnetic order that does depend on an interaction range and the density of spins on the lattice. For CuMn alloys, they obtain spin-glass ordering at low Mn concentration with a crossover to short-range helical order near 10% Mn. Our neutron scattering measurements were made on single crystals of CuMn alloys containing 1.4 and 3.0% Mn. Elastic scans along <1[zeta]0> at temperatures well below T[sub f] yield the same type of intensity distribution as that previously observed for the more concentrated alloys and show the existence of static SDW at dilutions down to 1.4% Mn. Inelastic scans in the same Q region for the Cu-3% Mn alloy clearly show the presence of dynamic SDW at temperatures up to T/T[sub f] = 7.5. These results favor the SDW model of Overhauser as the best description of the magnetic order in dilute CuMn alloys.

  19. Spin density waves in dilute CuMn alloys

    SciTech Connect

    Cable, J.W.; Tsunoda, Y.

    1992-12-01

    Neutron scattering studies on concentrated CuMn alloys show static spin density waves (SDW) that are incommensurate with the lattice and which become dynamic above the freezing temperature T{sub f} with a dispersion relation that is essentially vertical. We have examined the existence of both the static and the dynamic SDW in dilute CuMn alloys where the Mn atoms may be separated beyond the range of SDW stability. There is no such cutoff range in the Overhauser SDW model where the transition temperature is simply linear with concentration, but a recent calculation by loffe and Feigel`man gives magnetic order that does depend on an interaction range and the density of spins on the lattice. For CuMn alloys, they obtain spin-glass ordering at low Mn concentration with a crossover to short-range helical order near 10% Mn. Our neutron scattering measurements were made on single crystals of CuMn alloys containing 1.4 and 3.0% Mn. Elastic scans along <1{zeta}0> at temperatures well below T{sub f} yield the same type of intensity distribution as that previously observed for the more concentrated alloys and show the existence of static SDW at dilutions down to 1.4% Mn. Inelastic scans in the same Q region for the Cu-3% Mn alloy clearly show the presence of dynamic SDW at temperatures up to T/T{sub f} = 7.5. These results favor the SDW model of Overhauser as the best description of the magnetic order in dilute CuMn alloys.

  20. Evaluation of lead anode reactions in acid sulfate electrolytes. 1: Lead alloys with cobalt additives

    SciTech Connect

    Yu, P.; O`Keefe, T.J.

    1999-04-01

    Lead alloys, such as lead-calcium-tin and lead-silver, are the primary insoluble anodes used in the electrowinning of metals. While some difficulties are encountered in their use, there is no obvious replacement that is economically and technically competitive. Two of the specific problems with lead include decreased cathode purity due to incorporation from corrosion products and the relatively high overpotential which increases cell voltage. To gain an improved understanding of the fundamental behavior of lead anodes, the polarization behavior of six different alloys in sulfuric acid was evaluated. Some tests were also made with Co(II) in the acid sulfate electrolyte. Notable differences were found in the multiple activation-passivation cycles, stability, and relative activity for oxygen evolution for the alloys, and the relative trends in behavior were established. Electrochemical impedance spectroscopy studies were also conducted at selected potentials. Overall, the data show that the electrochemical response, particularly the degree of polarization for the oxygen evolution reaction, of the lead alloy anodes are dependent on the surface phases and structures present. The ability to depolarize the anode reaction using Co(II) was particularly sensitive to the lead composition.

  1. Embedded Atom Method Potential for Ni-Cu Alloys and Its Applications for Ni, Cu growth on Cu(111)

    NASA Astrophysics Data System (ADS)

    Onat, Berk; Durukanoglu, Sondan

    2012-02-01

    We developed a semi-empirical, many-body type model potential to investigate static and dynamic properties of Ni-Cu alloys. The formalism is based on the embedded atom method with improved optimization techniques. The Ni-Cu alloy potential was determined by fitting to data on lattice parameters, cohesive energies for L10, L11, L12, and L13 phases, together with vacancy formation energies, bulk modulus and elastic properties for L12, L13 phases. Our preliminary calculations for energy barriers for the diffusing Ni and Cu atoms on Cu(111) based on the nudged elastic band method are found to be consistent with the available experimental and other theoretical results. Our ultimate goal is to describe the varying characteristics in growing islands of pure Cu, Ni atoms and mixed Ni-Cu combinations on Cu(111) [S. Pons et al., Surf. Sci., 511, 449, (2002)].

  2. PEO of pre-anodized Al-Si alloys: Corrosion properties and influence of sealings

    NASA Astrophysics Data System (ADS)

    Mohedano, M.; Matykina, E.; Arrabal, R.; Mingo, B.; Pardo, A.

    2015-08-01

    Voltage-controlled PEO coatings were developed on A356 aluminum alloys (gravity-cast and rheocast) with a pre-anodized layer. The influence of the alloy manufacturing process and the effect of Si-rich phase on the structure and composition of the oxide layers were evaluated using SEM, EDS and XRD. The pre-anodized oxide layer preserves the microstructure of the substrate due to the presence of secondary phases that have a different behavior relative to the matrix during anodizing. PEO coatings consisted of a mixture of α-Al2O3, γ-Al2O3 and mullite. The corrosion behavior and the effectiveness of different sealing techniques based on salts of nickel, cobalt, cerium and phosphonic acid were also studied. Post-treatments improved the hydrophobic properties of the coatings and showed a beneficial effect, significantly increasing the coating impedance and thereby reducing the susceptibility to corrosion.

  3. Anodic Behavior of Specimens Prepared from a Full-Diameter Alloy 22 Fabricated Container

    SciTech Connect

    King, K J; Estill, J C; Rebak, R B

    2005-02-05

    Alloy 22 (N06022) has been extensively tested for general and localized corrosion behavior both in the wrought and annealed condition and in the as-welded condition. The specimens for testing were mostly prepared from flat plates of material. It was important to determine if the process of fabricating a full diameter Alloy 22 container will affect the corrosion performance of the alloy. Specimens were prepared directly from a fabricated container and tested for corrosion resistance. Results show that both the anodic corrosion behavior and the localized corrosion resistance of specimens prepared from a welded fabricated container was the same as from flat welded plates.

  4. Fabrication of the micro/nano-structure superhydrophobic surface on aluminum alloy by sulfuric acid anodizing and polypropylene coating.

    PubMed

    Wu, Ruomei; Liang, Shuquan; Liu, Jun; Pan, Anqiang; Yu, Y; Tang, Yan

    2013-03-01

    The preparation of the superhydrophobic surface on aluminum alloy by anodizing and polypropylene (PP) coating was reported. Both the different anodizing process and different PP coatings of aluminum alloy were investigated. The effects of different anodizing conditions, such as electrolyte concentration, anodization time and current on the superhydrophobic surface were discussed. By PP coating after anodizing, a good superhydrophobic surface was facilely fabricated. The optimum conditions for anodizing were determined by orthogonal experiments. After the aluminium-alloy was grinded with 600# sandpaper, pretreated by 73 g/L hydrochloric acid solution at 1 min, when the concentration of sulfuric acid was 180 g/L, the concentration of oxalic acid was 5 g/L, the concentration of potassium dichromate was 10 g/L, the concentration of chloride sodium was 50 g/L and 63 g/L of glycerol, anodization time was 20 min, and anodization current was 1.2 A/dm2, anodization temperature was 30-35 degrees C, the best micro-nanostructure aluminum alloy films was obtained. On the other hand, the PP with different concentrations was used to the PP with different concentrations was used to coat the aluminum alloy surface after anodizing. The results showed that the best superhydrophobicity was achieved by coating PP, and the duration of the superhydrophobic surface was improved by modifying the coat the aluminum alloy surface after anodizing. The results showed that the best superhydrophobicity was surface with high concentration PP. The morphologies of micro/nano-structure superhydrophobic surface were further confirmed by scanning electron microscope (SEM). The material of PP with the low surface free energy combined with the micro/nano-structures of the surface resulted in the superhydrophobicity of the aluminum alloy surface.

  5. Influence of casting conditions and alloy additives on the Zn40Al2Cu alloy structure

    NASA Astrophysics Data System (ADS)

    Michalik, R.; Tomaszewska, A.; Woźnica, H.

    2011-05-01

    Zn-Al-Cu alloys are characterized by several advantageous properties that can include good castability, good tribological properties, and low energy value needed to form the product. In comparison to bronzes, Zn-Al-Cu alloys are characterized by a lower density. The purpose of this study was to determine the effect of casting conditions and the addition of silicon and rare earth elements on the structure of a Zn-40%Al alloy. The subjects of this examination were an unmodified alloy, an alloy with the addition of 1,5% Si, and an alloy with additions of 1,5%Si and rare earth elements. Samples were cast in sand and graphite molds. In order to determine the microstructure of the tested samples, metallographic examinations using a light microscope and a scanning electron microscope with energy dispersive spectroscopy (EDS) through an X-ray spectrometer were used.

  6. Studies on white anodizing on aluminum alloy for space applications

    NASA Astrophysics Data System (ADS)

    Siva Kumar, C.; Mayanna, S. M.; Mahendra, K. N.; Sharma, A. K.; Uma Rani, R.

    1999-10-01

    A process of white anodizing in an electrolyte system consisting of sulfuric acid, lactic acid, glycerol and sodium molybdate was studied for space applications. The influence of anodic film thickness and various operating parameters, viz., electrolyte formulation, operating temperature, applied current density, on the optical properties of the coating has been investigated to optimize the process. The coatings were characterized by atomic absorption spectroscopic analysis, thickness and microhardness evaluation. The space worthiness of the coating has been evaluated by humidity, thermal cycling, thermo-vacuum performance tests and measurement of optical properties. The anodic film developed herein provides solar absorptance value as low as 0.16, and infrared (IR) emittance of the order of 0.80. These results indicate that the process developed is suitable for thermal control applications in space environment.

  7. Production of Cu-Al-Ni Shape Memory Alloys by Mechanical Alloy

    SciTech Connect

    Goegebakan, Musa; Soguksu, Ali Kemal; Uzun, Orhan; Dogan, Ali

    2007-04-23

    The mechanical alloying technique has been used to produce shape memory Cu83Al13Ni4 alloy. The structure and thermal properties were examined by using scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The morphology of the surface suggests the presence of martensite.

  8. Structural Investigations of Nanocrystalline Cu-Cr-Mo Alloy Prepared by High-Energy Ball Milling

    NASA Astrophysics Data System (ADS)

    Kumar, Avanish; Pradhan, Sunil Kumar; Jayasankar, Kalidoss; Debata, Mayadhar; Sharma, Rajendra Kumar; Mandal, Animesh

    2017-02-01

    Cu-Cr-Mo alloy could be a suitable candidate material for collector electrodes in high-power microwave tube devices. An attempt has been made to synthesize ternary Cu-Cr-Mo alloys by mechanical alloying of elemental Cu, Cr, and Mo powders, to extend the solid solubility of Cr and Mo in Cu, using a commercial planetary ball mill. For the first ternary alloy, a mixture of 80 wt.% Cu, 10 wt.% Cr, and 10 wt.% Mo was mechanically milled for 50 h. For the second ternary alloy, a mixture of 50 wt.% Cr and 50 wt.% Mo was mechanically milled for 50 h to obtain nanocrystalline Cr(Mo) alloy, which was later added to Cu powder and milled for 40 h to obtain Cu-20 wt.%Cr(Mo) alloy. Both nanocrystalline Cu-Cr-Mo ternary alloys exhibited crystallite size below 20 nm. It was concluded that, with addition of nanocrystalline Cr(Mo) to Cu, it was possible to extend the solid solubility of Cr and Mo in Cu, which otherwise was not possible by mechanical alloying of elemental powders. The resulting microstructure of the Cu-20 wt.%Cr(Mo) alloy comprised a homogeneous distribution of fine and hard (Cr, Mo) particles in a copper matrix. Furthermore, Cu-20 wt.%Cr(Mo) alloy showed better densification compared with Cu-10 wt.%Cr-10 wt.%Mo alloy.

  9. Property of anodic coatings obtained in an organic, environmental friendly electrolyte on aluminum alloy 2024-T3

    NASA Astrophysics Data System (ADS)

    Zhang, R. F.; Shi, H. W.; Liu, Z. L.; Zhang, S. F.; Zhang, Y. Q.; Guo, S. B.

    2014-01-01

    Anodic coatings were obtained by micro arc oxidation on aluminum alloy 2024-T3 in a solution containing only 10 g/L sodium phytate. The morphology, composition, structure and corrosion resistance of anodic coatings were systematically investigated. The results show that the working voltage continually increases during 3 min and bright sparks appear after 25 s. Anodic coatings are evenly formed on the substrate and about 2 μm thick. XPS and XRD analyses reveal that the obtained coatings are mainly composed of α-Al2O3 and γ-Al2O3. Compared with the substrate, the corrosion resistance of the anodized aluminum alloys is improved.

  10. Nanostructured FeZrCuB alloys prepared by mechanosynthesis

    SciTech Connect

    Pereira, R. D.; Passamani, E. C.; Larica, C.; Freitas, J. C. C.; Takeuchi, A. Y.

    2007-08-01

    Nanostructured Fe{sub 84}Zr{sub 9}B{sub 6}Cu{sub 1} alloys were prepared by the mechanosynthesis method, following two alternative routes. In the first procedure, the alloy was directly obtained from the milling of the powder mixture of all elemental components. The resulting alloy was partially nanocrystalline, with dispersion of nanograins in an amorphous matrix. In the second route, Cu and B elemental powders were progressively added to a previously milled Fe{sub 90}Zr{sub 10} alloy. A nearly single amorphous phase was consequently obtained. The dispersion of nanograins was easily recovered in this case, after annealing the milled alloy. The hyperfine magnetic properties of the amorphous phase prepared by milling were comparable to those found in similar melt-spun alloys. The crystallization temperatures and activation energies, associated with the first and second crystallization stages, were found to be lower for the milled alloy when compared with the corresponding melt-spun alloy, an effect associated with the larger number of defects induced by the mechanosynthesis process.

  11. Carbon treated commercial aluminium alloys as anodes for aluminium-air batteries in sodium chloride electrolyte

    NASA Astrophysics Data System (ADS)

    Pino, M.; Herranz, D.; Chacón, J.; Fatás, E.; Ocón, P.

    2016-09-01

    An easy treatment based in carbon layer deposition into aluminium alloys is presented to enhance the performance of Al-air primary batteries with neutral pH electrolyte. The jellification of aluminate in the anode surface is described and avoided by the carbon covering. Treated commercial Al alloys namely Al1085 and Al7475 are tested as anodes achieving specific capacities above 1.2 Ah g-1vs 0.5 Ah g-1 without carbon covering. The influence of the binder proportion in the treatment as well as different carbonaceous materials, Carbon Black, Graphene and Pyrolytic Graphite are evaluated as candidates for the covering. Current densities of 1-10 mA cm-2 are measured and the influence of the alloy explored. A final battery design of 4 cells in series is presented for discharges with a voltage plateau of 2 V and 1 Wh g-1 energy density.

  12. Characterisation of the anodic layers formed on 2024 aluminium alloy, in tetraborate electrolyte containing molybdate ions

    NASA Astrophysics Data System (ADS)

    Moutarlier, V.; Pelletier, S.; Lallemand, F.; Gigandet, M. P.; Mekhalif, Z.

    2005-12-01

    Anodic layer growth on 2024 aluminium alloy at 70 °C, under 40 V, during 60 min, in 50 g L -1 di-sodium tetraborate solution containing di-sodium molybdate from 0.1 to 0.5 M (pH 10) is examined. Anodising behaviours strongly depend on additive concentration. Development of anodic films is favoured with weak molybdate additions (<0.3-0.4 M). The film thicknesses increase and the porosity of anodic layers decreases. Molybdenum (+VI), detected by X-ray photoelectron spectroscopy (XPS) analysis, is present in the anodic films and the Mo incorporation, studied by energy dispersive spectroscopy (EDS) analysis, increases with molybdate concentration. However, for high molybdate concentrations (>0.4 M), anodising behaviour becomes complex with the formation of a blue molybdenum oxide at the cathode. The growth of aluminium oxide is hindered. As the anodic layers are thinner, the Mo(+VI) incorporation significantly decreases. These two configurations implicate different corrosion performances in 5% sodium chloride solution at 35 °C. As the alkaline anodic layer formed with 0.3 M molybdate species is the thickest and the Mo incorporation is the more pronounced, its corrosion resistance is the highest. The effect of morphology and composition of anodic films on pitting corrosion is also discussed.

  13. ANODIC BEHAVIOR OF ALLOY 22 IN HIGH NITRATE BRINES AT TEMPERATURES HIGHER THAN 100C

    SciTech Connect

    G.O. LLEVBARE; J.C. ESTILL; A. YILMAZ; R.A. ETIEN; G.A. HUST M.L. STUART

    2006-04-20

    Alloy 22 (N06022) may be susceptible to crevice corrosion in chloride solutions. Nitrate acts as an inhibitor to crevice corrosion. Several papers have been published regarding the effect of nitrate on the corrosion resistance of Alloy 22 at temperatures 100 C and lower. However, very little is known about the behavior of this alloy in highly concentrated brines at temperatures above 100 C. In the current work, electrochemical tests have been carried out to explore the anodic behavior of Alloy 22 in high chloride high nitrate electrolytes at temperatures as high as 160 C at ambient atmospheres. Even though Alloy 22 may adopt corrosion potentials in the order of +0.5 V (in the saturated silver chloride scale), it does not suffer crevice corrosion if there is high nitrate in the solution. That is, the inhibitive effect of nitrate on crevice corrosion is active for temperatures higher than 100 C.

  14. Recycled hierarchical tripod-like CuCl from Cu-PCB waste etchant for lithium ion battery anode.

    PubMed

    Liu, Song; Hou, Hongying; Liu, Xianxi; Duan, Jixiang; Yao, Yuan; Liao, Qishu; Li, Jing; Yang, Yunzhen

    2017-02-15

    Hierarchical CuCl with high economic value added (EVA) was successfully recycled with 85% recovery from the acid Cu printed circuit board (Cu-PCB) waste etchant via facile liquid chemical reduction. The micro-structure and morphology of the recycled hierarchical CuCl were systematically characterized in terms of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET). Furthermore, the corresponding electrochemical performances as lithium ion battery (LIB) anode were also investigated in terms of galvanostatic charge/discharge, cyclic voltammetry (CV) and AC impedance. As expected, the recycled CuCl displayed a hierarchical tripod-like structure and large specific surface area of 21.2m(2)/g. As the anode in LIB, the reversible discharge capacity was about 201.4 mAh/g even after 100 cycles, implying the satisfactory cycle performance. Clearly, the satisfactory results may open a new avenue to develop the sustainable industry, which is very important in terms of both the resource recovery and the environmental protection.

  15. Structured SiCu thin films in LiB as anodes

    SciTech Connect

    Polat, Billur Deniz; Eryilmaz, Osman Levent; Erck, Robert; Keles, O.; Erdemir, A.; Amine, Khalil

    2014-09-16

    Both helical and inclined columnar Si–10 at.% Cu structured thin films were deposited on Cu substrates using glancing angle deposition (GLAD) technique. In order to deposit Cu and Si two evaporation sources were used. Ion assistance was utilized in the first 5 min of the GLAD to enhance the adhesion and the density of the films. These films were characterized by thin film XRD, GDOES, SEM, and EDS. Electrochemical characterizations were made by testing the thin films as anodes in half-cells for 100 cycles. The results showed that the columnar SiCu thin film delivered 2200 mAh g-1, where the helical one exhibited 2600 mAh g-1, and, their initial coulombic efficiencies were found to be 38%–50% respectively. For the columnar and the helical thin film anodes, sustainable 520 and 800 mAh g-1 with 90% and 99% coulombic efficiencies were achieved for 100 cycles. These sustainable capacities showed the importance of the thin film structure having nano-sized crystals and amorphous particles. The higher surface area of the helices increases the capacity of the electrode because the contact area of the thin film anode with Li ions is increased, and the polarization which otherwise forms on the anode surface due to SEI formation is decreased. In addition, because of larger interspaces between the helices the ability of the anode to accommodate the volumetric changes is improved, which results in a higher coulombic efficiency and capacity retention during cycling test.

  16. Stress Corrosion Cracking in Al-Zn-Mg-Cu Aluminum Alloys in Saline Environments

    NASA Astrophysics Data System (ADS)

    Holroyd, N. J. Henry; Scamans, G. M.

    2013-03-01

    80 to 85 kJ/mol, whereas for high-copper-containing alloys (>~0.8 wt pct), they are typically ranging from 20 to 40 kJ/mol for under- and peak-aged alloys, and based on limited data, around 85 kJ/mol for over-aged tempers. This means that crack propagation in saline environments is most likely to occur by a hydrogen-related process for low-copper-containing Al-Zn-Mg-Cu alloys in under-, peak- and over-aged tempers, and for high-copper alloys in under- and peak-aged tempers. For over-aged high-copper-containing alloys, cracking is most probably under anodic dissolution control. Future stress corrosion studies should focus on understanding the factors that control crack initiation, and insuring that the next generation of higher performance Al-Zn-Mg-Cu alloys has similar longer crack initiation times and crack propagation rates to those of the incumbent alloys in an over-aged condition where crack rates are less than 1 mm/month at a high stress intensity factor.

  17. Characterization of Cu Distribution in an Al-0.3%Cu Alloy Cold Rolled to 98%

    NASA Astrophysics Data System (ADS)

    Shuai, L. F.; Huang, T. L.; Wu, G. L.; Hansen, N.; Huang, X.

    2017-07-01

    In this study, the distribution of Cu element in a Al (99.9996% purity)-0.3%Cu alloy cold rolled to 98% has been characterized in detail by using three-dimensional atom probe (3DAP) and ChemiSTEM techniques. The cold rolled structure is a typical high strain lamellar structure with an average boundary spacing of 200 nm, indicating a strong role of the small amount of Cu element in stabilizing the microstructure to form the fine scale structure. A heavy segregation of Cu element in the lamellar boundaries of high angles has been observed and the Cu concentration in the boundaries can be as high as 20 times of the nominal concentration of the alloy, which is considered as the main reason for a formation of a stable nanoscale lamellar structure.

  18. Abnormal resistivity behavior of Cu-Ni and Cu-Co alloys in undercooled liquid state

    NASA Astrophysics Data System (ADS)

    Guo, Fengxiang; Lu, Ting; Qin, Jingyu; Zheng, Hongliang; Tian, Xuelei

    2012-11-01

    The resistivity behavior of undercooled liquid Cu-Ni and Cu-Co alloys had been studied in the contactless method, to probe the structure transition in undercooled melts during the cooling process. Over the entire concentration range, linear behavior of resistivity with temperature was obtained in liquid and undercooled liquid Cu-Ni system. It implied that the formation of icosahedral order might not influence the electron scattering in undercooled liquid Cu-Ni alloys. Similar results were obtained in Cu-Co system in the vicinity of liquidus temperature. A turning point was obvious in temperature coefficient of resistivity for undercooled liquid Cu-Co alloys around the bimodal line, which was interpreted to be responsible for metastable liquid-liquid phase separation. During liquid phase separation process, resistivity decreased and the temperature coefficient of resistivity was larger than that of homogeneous melts. In combination with transmission electron microscopy and scanning electron microscope studies on the as-solidified microstructure, this was interpreted as the formation of egg-type structure and concentration change in Cu-rich and Co-rich phases. The mechanism controlling the separation and droplets motion was also discussed in undercooled liquid Cu-Co system.

  19. Cu3P/RGO Nanocomposite as a New Anode for Lithium-Ion Batteries

    NASA Astrophysics Data System (ADS)

    Liu, Shuling; He, Xiaodong; Zhu, Jianping; Xu, Liqiang; Tong, Jianbo

    2016-10-01

    Cu3P/reduced graphene oxide (Cu3P/RGO) nanocomposite was successfully synthesized by a facile one-pot method as an advanced anode material for high-performance lithium-ion batteries. Cu3P nanostructures with a polyhedral shape with the mean diameter (80–100 nm) were homogeneously anchored on the surface of RGO. The flexible RGO sheets acted as elastic buffering layer which not only reduced the volume change, but also prevented the aggregation of Cu3P nanostructures, the cracking and crumbing of electrodes. On the other hand, the presence of Cu3P nanostructures could also avoid the agglomeration of RGO sheets and retain their highly active surface area. Therefore, as an advanced anode material for high-performance lithium-ion batteries, the as-prepared Cu3P/RGO exhibited high capacity of 756.15 mAhg‑1 at the current density 500 mAg‑1 after 80 cycles, superior cyclic stability and good rate capability.

  20. Cu3P/RGO Nanocomposite as a New Anode for Lithium-Ion Batteries.

    PubMed

    Liu, Shuling; He, Xiaodong; Zhu, Jianping; Xu, Liqiang; Tong, Jianbo

    2016-10-11

    Cu3P/reduced graphene oxide (Cu3P/RGO) nanocomposite was successfully synthesized by a facile one-pot method as an advanced anode material for high-performance lithium-ion batteries. Cu3P nanostructures with a polyhedral shape with the mean diameter (80-100 nm) were homogeneously anchored on the surface of RGO. The flexible RGO sheets acted as elastic buffering layer which not only reduced the volume change, but also prevented the aggregation of Cu3P nanostructures, the cracking and crumbing of electrodes. On the other hand, the presence of Cu3P nanostructures could also avoid the agglomeration of RGO sheets and retain their highly active surface area. Therefore, as an advanced anode material for high-performance lithium-ion batteries, the as-prepared Cu3P/RGO exhibited high capacity of 756.15 mAhg(-1) at the current density 500 mAg(-1) after 80 cycles, superior cyclic stability and good rate capability.

  1. Cu3P/RGO Nanocomposite as a New Anode for Lithium-Ion Batteries

    PubMed Central

    Liu, Shuling; He, Xiaodong; Zhu, Jianping; Xu, Liqiang; Tong, Jianbo

    2016-01-01

    Cu3P/reduced graphene oxide (Cu3P/RGO) nanocomposite was successfully synthesized by a facile one-pot method as an advanced anode material for high-performance lithium-ion batteries. Cu3P nanostructures with a polyhedral shape with the mean diameter (80–100 nm) were homogeneously anchored on the surface of RGO. The flexible RGO sheets acted as elastic buffering layer which not only reduced the volume change, but also prevented the aggregation of Cu3P nanostructures, the cracking and crumbing of electrodes. On the other hand, the presence of Cu3P nanostructures could also avoid the agglomeration of RGO sheets and retain their highly active surface area. Therefore, as an advanced anode material for high-performance lithium-ion batteries, the as-prepared Cu3P/RGO exhibited high capacity of 756.15 mAhg−1 at the current density 500 mAg−1 after 80 cycles, superior cyclic stability and good rate capability. PMID:27725701

  2. Mercury embrittlement of Cu-Al alloys under cyclic loading

    NASA Technical Reports Server (NTRS)

    Regan, T. M.; Stoloff, N. S.

    1977-01-01

    The effect of mercury on the room temperature, high cycle fatigue properties of three alloys: Cu-5.5 pct Al, Cu-7.3 pct Al, and Cu-6.3 pct Al-2.5 pct Fe has been determined. Severe embrittlement under cyclic loading in mercury is associated with rapid crack propagation in the presence of the liquid metal. A pronounced grain size effect is noted under mercury, while fatigue properties in air are insensitive to grain size. The fatigue results are discussed in relation to theories of adsorption-induced liquid metal embrittlement.

  3. Free-standing CuO nanoflake arrays coated Cu foam for advanced lithium ion battery anodes

    NASA Astrophysics Data System (ADS)

    Yang, Wanfeng; Wang, Jiawei; Ma, Wensheng; Dong, Chaoqun; Cheng, Guanhua; Zhang, Zhonghua

    2016-11-01

    For lithium ion batteries (LIBs), low electronic conductivity of CuO leads to rapid capacity decay and poor structural stability. Herein, we successfully fabricate three-dimensional CuO nanoflake arrays coated Cu foam by facile and efficient electrochemical oxidation. When being applied as anode material for LIBs, the CuO electrodes deliver stable reversible capacities of 523.9 mA h g-1 at 0.5 A g-1, 376.1 mA h g-1 at 1.0 A g-1 and 322.7 mA h g-1 at 2.0 A g-1 with high coulombic efficiency (>99%) after 100 cycles. A long cycle life of up to 400 cycles at 2.0 A g-1 is also achieved with the retention capacity of 193.5 mA h g-1. Moreover, the electrode exhibits excellent rate capability and can regain its original capacities as reversing to the low current densities. Noticeably, on-line differential electrochemical mass spectrometry and in situ Raman measurements confirm the formation of solid electrolyte interface film and the conversion mechanism for the CuO electrodes, respectively. The superior lithium storage performance can be attributed to the favorable nanoflake structures with high surface area and the perfect electrical contact between CuO and Cu substrate.

  4. In vitro study on the corrosion behavior of three commercial Ag-Pd-Cu-Au alloys in Ringer's and 0.1%Na2S solutions.

    PubMed

    Endo, K; Araki, Y; Kawashima, I; Yamane, Y; Ohno, H; Matsuda, K

    1989-12-01

    The corrosion resistance of three commercial Ag-Pd-Cu-Au alloys was estimated in Ringer's and 0.1% Na2S solutions by electrochemical techniques and surface analyses. In Ringer's solution, the three alloys showed high corrosion resistance and there was no significant difference in the anodic polarization characteristics of the three alloys. In the 0.1% Na2S solution, the Alloy A which had the lowest noble metal content (Au + Pd) exhibited the highest anodic reactivity with the largest amount of corrosion product on the alloy surface. It was determined that the Ag-rich phase of Ag-Pd-Cu-Au alloy was preferentially attacked to form Ag2S corrosion product. The polarization resistance data showed that the corrosion rate for Alloy A in 0.1% Na2S solution was determined to be 500 times higher than that in Ringer's solution. The corrosion rate of the alloy in the freely corroded condition can be estimated quantitatively and precisely by measuring the polarization resistance.

  5. -Interface effects on the magnetic moment of Co and Cu in CoCu granular alloys

    SciTech Connect

    Garcia Prieto, A.; Fdez-Gubieda, M.L.; Chaboy, J.; Laguna-Marco, M.A.; Muro, T.; Nakamura, T.

    2005-12-01

    We report on x-ray magnetic circular dichroism experiments performed on Co{sub 5}Cu{sub 95} annealed granular alloys with giant magnetoresistance. Results on the Co-L{sub 2,3} edge evidence a direct correlation between the Co orbital and spin magnetic moment and the Co clusters interfacial roughness. On the other hand, we have found dichroism on the Cu-L{sub 2,3} edge, revealing an induced magnetic polarization of the Cu interfacial atoms. The magnetic moment of the Cu atoms is mainly of spin character and is ferromagnetically coupled with the Co magnetic moment.

  6. Effect of Cu content on the antibacterial activity of titanium-copper sintered alloys.

    PubMed

    Liu, Jie; Li, Fangbing; Liu, Cong; Wang, Hongying; Ren, Baorui; Yang, Ke; Zhang, Erlin

    2014-02-01

    The phase constitution and the microstructure Ti-x Cu (x=2, 5, 10 and 25 wt.%) sintered alloys were investigated by XRD and SEM and the antibacterial activity was assessed in order to investigate the effect of the Cu content on the antibacterial activity. The results have shown that Ti2Cu was synthesized as a main secondary phase in all Ti-Cu alloys while Cu-rich phase was formed in the alloys with 5 wt.% or more copper. Antibacterial tests have showed that the Cu content influences the antibacterial rate seriously and only the alloys with 5 wt.% or high Cu have a strong and stable antibacterial rate, which indicates that the Cu content in Ti-Cu alloys must be at least 5 wt.% to obtain strong and stable antibacterial property. The Cu content also influenced the Cu ion release behavior. High Cu ion release concentration and high Cu ion release rate were observed for Ti-Cu alloys with high Cu content. It was concluded that the Cu content affects the Cu existence and the Cu ion release behavior, which in turn influences the antibacterial property. It was thought that the Cu-rich phase should play an important role in the strong antibacterial activity. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Alloy Cu3Pt nanoframes through the structure evolution in Cu-Pt nanoparticles with a core-shell construction

    PubMed Central

    Han, Lin; Liu, Hui; Cui, Penglei; Peng, Zhijian; Zhang, Suojiang; Yang, Jun

    2014-01-01

    Noble metal nanoparticles with hollow interiors and customizable shell compositions have immense potential for catalysis. Herein, we present an unique structure transformation phenomenon for the fabrication of alloy Cu3Pt nanoframes with polyhedral morphology. This strategy starts with the preparation of polyhedral Cu-Pt nanoparticles with a core-shell construction upon the anisotropic growth of Pt on multiply twinned Cu seed particles, which are subsequently transformed into alloy Cu3Pt nanoframes due to the Kirkendall effect between the Cu core and Pt shell. The as-prepared alloy Cu3Pt nanoframes possess the rhombic dodecahedral morphology of their core-shell parents after the structural evolution. In particular, the resulting alloy Cu3Pt nanoframes are more effective for oxygen reduction reaction but ineffective for methanol oxidation reaction in comparison with their original Cu-Pt core-shell precursors. PMID:25231376

  8. Advances of Ag, Cu, and Ag-Cu alloy nanoparticles synthesized via chemical reduction route

    NASA Astrophysics Data System (ADS)

    Tan, Kim Seah; Cheong, Kuan Yew

    2013-04-01

    Silver (Ag) and copper (Cu) nanoparticles have shown great potential in variety applications due to their excellent electrical and thermal properties resulting high demand in the market. Decreasing in size to nanometer scale has shown distinct improvement in these inherent properties due to larger surface-to-volume ratio. Ag and Cu nanoparticles are also shown higher surface reactivity, and therefore being used to improve interfacial and catalytic process. Their melting points have also dramatically decreased compared with bulk and thus can be processed at relatively low temperature. Besides, regularly alloying Ag into Cu to create Ag-Cu alloy nanoparticles could be used to improve fast oxidizing property of Cu nanoparticles. There are varieties methods have been reported on the synthesis of Ag, Cu, and Ag-Cu alloy nanoparticles. This review aims to cover chemical reduction means for synthesis of those nanoparticles. Advances of this technique utilizing different reagents namely metal salt precursors, reducing agents, and stabilizers, as well as their effects on respective nanoparticles have been systematically reviewed. Other parameters such as pH and temperature that have been considered as an important factor influencing the quality of those nanoparticles have also been reviewed thoroughly.

  9. An electrochemical and multispectroscopic study of corrosion of Ag-Pd-Cu-Au alloys.

    PubMed

    Niemi, L; Minni, E; Ivaska, A

    1986-06-01

    Corrosion of a multi-phase Ag-Pd-Cu-Au-based commercial dental casting alloy and a Cu-Pd-rich and Ag-rich single-phase alloy was studied by open-circuit potential measurements, atomic absorption spectrometry, and electron spectroscopy. The alloys were immersed in an artificial saliva solution for 24 hr while the open-circuit potentials of the alloys were measured. The potentials were found to stabilize at certain levels after a steep rise during the first hours of the experiment. Cu was found to dissolve considerably from the Cu-Pd-rich alloy, with simultaneous enrichment of Pd in the surface layer of the alloy. Ag dissolved slightly from the Ag-rich alloy, but both Cu and Ag were found to dissolve from the multi-phase alloy. Neither Pd nor Au dissolved from any of the alloys studied.

  10. Investigation of new type Cu-Hf-Al bulk glassy alloys

    NASA Astrophysics Data System (ADS)

    Nagy, E.; Rontó, V.; Sólyom, J.; Roósz, A.

    2009-01-01

    In the last years new type Cu-Hf-Al ternary alloys were developed with high glass forming ability and ductility. The addition of Al to Cu-Hf alloys results in improvements in glass formation, thermal stability and mechanical properties of these alloys. We have investigated new Cu-based bulk amorphous alloys in Cu-Hf-Al ternary system. The alloys with Cu49Hf42Al9, Cu46Hf45Al9, Cu50Hf42.5Al7.5 and Cu50Hf45Al5 compositions were prepared by arc melting. The samples were made by centrifugal casting and were investigated by X-ray diffraction method. Thermodynamic properties were examined by differential scanning calorimetry and the structure of the crystallising phases by scanning electron microscopy. The determination of liquidus temperatures of alloys were measured by differential thermal analysis.

  11. Alloy-Based Anode Materials toward Advanced Sodium-Ion Batteries.

    PubMed

    Lao, Mengmeng; Zhang, Yu; Luo, Wenbin; Yan, Qingyu; Sun, Wenping; Dou, Shi Xue

    2017-06-28

    Sodium-ion batteries (SIBs) are considered as promising alternatives to lithium-ion batteries owing to the abundant sodium resources. However, the limited energy density, moderate cycling life, and immature manufacture technology of SIBs are the major challenges hindering their practical application. Recently, numerous efforts are devoted to developing novel electrode materials with high specific capacities and long durability. In comparison with carbonaceous materials (e.g., hard carbon), partial Group IVA and VA elements, such as Sn, Sb, and P, possess high theoretical specific capacities for sodium storage based on the alloying reaction mechanism, demonstrating great potential for high-energy SIBs. In this review, the recent research progress of alloy-type anodes and their compounds for sodium storage is summarized. Specific efforts to enhance the electrochemical performance of the alloy-based anode materials are discussed, and the challenges and perspectives regarding these anode materials are proposed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Characterization of Localized Filament Corrosion Products at the Anodic Head on a Model Mg-Zn-Zr Alloy Surface

    DOE PAGES

    Rossouw, David; Fu, Dong; Leonard, Donovan N.; ...

    2017-02-15

    In this study, localized filament corrosion products at the anodic head on a model Mg-1%Zn-0.4%Zr alloy surface were characterized by electron microscopy techniques of site-specific lamella prepared by focused ion beam milling. It is revealed that the anodic head propagates underneath a largely intact thin and dense MgO surface film and comprises dense aggregates of nano-crystalline MgO within a nano-porous Mg(OH)2 network. In conclusion, the findings contribute new supportive direct imaging insight into the source of the enhanced H2 evolution that accompanies anodic dissolution of Mg and its alloys.

  13. Comparative study of the alloying effect on the initial oxidation of Cu-Au(100) and Cu-Pt(100)

    SciTech Connect

    Luo, Langli; Zhou, Guangwen; Kang, Yihong; Yang, Judith C.; Su, Dong; Stach, Eric A.

    2014-03-24

    Using in situ transmission electron microscopy, we show that the oxidation of the Cu-Au(100) results in the formation of Cu{sub 2}O islands that deeply embed into the Cu-Au substrate while the oxidation of the Cu-Pt(100) leads to the formation of Cu{sub 2}O islands that highly protrude above the Cu-Pt substrate. Their difference is attributed to the different mobilities of Pt and Au in the Cu base alloys for which the sluggish mobility of Pt in Cu results in trapped Pt atoms at the oxide/alloy interface while the faster mobility of Au in Cu leads to enhanced rehomogenization of the alloy composition.

  14. Advanced image analysis of the surface pattern emerging in Ni3Al intermetallic alloys on anodization

    NASA Astrophysics Data System (ADS)

    Salerno, Marco; Stępniowski, Wojciech; Cieślak, Grzegorz; Norek, Małgorzata; Michalska-Domańska, Marta; Karczewski, Krzysztof; Chilimoniuk, Paulina; Polkowski, Wojciech; Jóźwik, Paweł; Bojar, Zbigniew

    2016-07-01

    Anodization of Ni3Al alloy is of interest in the field of industrial manufacturing, thanks to the formation of protective oxide layer on the materials working in corrosive environments and high temperatures. However, homogeneous surface treatment is paramount for technological applications of this material. The anodization conditions have to be set outside the ranges of corrosion and “burning”, which is the electric field enhanced anodic dissolution of the metal. In order to check against occurrence of these events, proper quantitative means for assessing the surface quality have to be developed and established. We approached this task by advanced analysis of scanning electron microscope images of anodized Ni3Al plates. The anodization was carried out in 0.3 M citric acid at two temperatures of 0 and 30°C and at voltages in the range of 2 12 V. Different figures can be used to characterize the quality of the surface, in terms of uniformity. Here, the concept of regularity ratio spread is used for the first time on surfaces of technological interest. Additionally, the Minkowski parameters have been calculated and their meaning is discussed.

  15. Phosphorus-Based Alloy Materials for Advanced Potassium-Ion Battery Anode.

    PubMed

    Zhang, Wenchao; Mao, Jianfeng; Li, Sean; Chen, Zhixin; Guo, Zaiping

    2017-03-08

    Potassium-ion batteries (PIBs) are interesting as one of the alternative metal-ion battery systems to lithium-ion batteries (LIBs) due to the abundance and low cost of potassium. We have herein investigated Sn4P3/C composite as a novel anode material for PIBs. The electrode delivered a reversible capacity of 384.8 mA h g(-1) at 50 mA g(-1) and a good rate capability of 221.9 mA h g(-1), even at 1 A g(-1). Its electrochemical performance is better than any anode material reported so far for PIBs. It was also found that the Sn4P3/C electrode displays a discharge potential plateau of 0.1 V in PIBs, slightly higher than for sodium-ion batteries (SIBs) (0.01 V), and well above the plating potential of metal. This diminishes the formation of dendrites during cycling, and thus Sn4P3 is a relatively safe anode material, especially for application in large-scale energy storage, where large amounts of electrode materials are used. Furthermore, a possible reaction mechanism of the Sn4P3/C composite as PIB anode is proposed. This work may open up a new avenue for further development of alloy-based anodes with high capacity and long cycle life for PIBs.

  16. Corrosion and protection of heterogeneous cast Al-Si (356) and Al-Si-Cu-Fe (380) alloys by chromate adn cerium inhibitors

    NASA Astrophysics Data System (ADS)

    Jain, Syadwad

    In this study, the localized corrosion and conversion coating on cast alloys 356 (Al-7.0Si-0.3Mg) and 380 (Al-8.5Si-3.5Cu-1.6Fe) were characterized. The intermetallic phases presence in the permanent mold cast alloy 356 are primary-Si, Al5FeSi, Al8Si6Mg3Fe and Mg2Si. The die cast alloy 380 is rich in Cu and Fe elements. These alloying elements result in formation of the intermetallic phases Al 5FeSi, Al2Cu and Al(FeCuCr) along with primary-Si. The Cu- and Fe-rich IMPS are cathodic with respect to the matrix phase and strongly govern the corrosion behavior of the two cast alloys in an aggressive environment due to formation of local electrochemical cell in their vicinity. Results have shown that corrosion behavior of permanent mould cast alloy 356 is significantly better than the die cast aluminum alloy 380, primarily due to high content of Cu- and Fe-rich phases such as Al2Cu and Al 5FeSi in the latter. The IMPS also alter the protection mechanism of the cast alloys in the presence of inhibitors in an environment. The presence of chromate in the solution results in reduced cathodic activity on all the phases. Chromate provides some anodic inhibition by increasing pitting potentials and altering corrosion potentials for the phases. Results have shown that performance of CCC was much better on 356 than on 380, primarily due to inhomogeneous and incomplete coating deposition on Cu- and Fe- phases present in alloy 380. XPS and Raman were used to characterize coating deposition on intermetallics. Results show evidence of cyanide complex formation on the intermetallic phases. The presence of this complex is speculated to locally suppress CCC formation. Formation and breakdown of cerium conversion coatings on 356 and 380 was also analyzed. Results showed that deposition of cerium hydroxide started with heavy precipitation on intermetallic particles with the coatings growing outwards onto the matrix. Electrochemical analysis of synthesized intermetallics compounds in the

  17. Cu-Au Alloys Using Monte Carlo Simulations and the BFS Method for Alloys

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Good, Brian; Ferrante, John

    1996-01-01

    Semi empirical methods have shown considerable promise in aiding in the calculation of many properties of materials. Materials used in engineering applications have defects that occur for various reasons including processing. In this work we present the first application of the BFS method for alloys to describe some aspects of microstructure due to processing for the Cu-Au system (Cu-Au, CuAu3, and Cu3Au). We use finite temperature Monte Carlo calculations, in order to show the influence of 'heat treatment' in the low-temperature phase of the alloy. Although relatively simple, it has enough features that could be used as a first test of the reliability of the technique. The main questions to be answered in this work relate to the existence of low temperature ordered structures for specific concentrations, for example, the ability to distinguish between rather similar phases for equiatomic alloys (CuAu I and CuAu II, the latter characterized by an antiphase boundary separating two identical phases).

  18. Boric/sulfuric acid anodizing of aluminum alloys 2024 and 7075: Film growth and corrosion resistance

    SciTech Connect

    Thompson, G.E.; Zhang, L.; Smith, C.J.E.; Skeldon, P.

    1999-11-01

    The influence of boric acid (H{sub 3}BO{sub 3}) additions to sulfuric acid (H{sub 2}SO{sub 4}) were examined for the anodizing of Al 2024-T3 (UNS A92024) and Al 7075-T6 (UNS A97075) alloys at constant voltage. Alloys were pretreated by electropolishing, by sodium dichromate (Na{sub 2}Cr{sub 2}O{sub 7})/H{sub 2}SO{sub 4} (CSA) etching, or by alkaline etching. Current-time responses revealed insignificant dependence on the concentration of H{sub 3}BO{sub 3} to 50 g/L. Pretreatments affected the initial film development prior to the establishment of the steady-state morphology of the porous film, which was related to the different compositions and morphologies of pretreated surfaces. More detailed studies of the Al 7075-T6 alloy indicated negligible effects of H{sub 3}BO{sub 3} on the coating weight, morphology of the anodic film, and thickening rate of the film, or corrosion resistance provided by the film. In salt spray tests, unsealed films formed in H{sub 2}SO{sub 4} or mixed acid yielded similar poor corrosion resistances, which were inferior to that provided by anodizing in chromic acid (H{sub 2}CrO{sub 4}). Sealing of films in deionized water, or preferably in chromate solution, improved corrosion resistance, although not matching the far superior performance provided by H{sub 2}CrO{sub 4} anodizing and sealing.

  19. Study of anodic dissolution of Fe-Ru alloy with the aid of mossbauer spectroscopy

    SciTech Connect

    Khlystov, A.S.; Fasman, A.B.; Kil'dibekova, G.A.

    1986-01-10

    This paper uses Fe 57 Mossbauer spectroscopy, whereby iron compounds may be identified quantitatively and their composition and structure can be determined, for the study of the relationships of slime formation from Fe-Ru binary alloys. Both the products of dissolution and the composition and state of intermediate phases formed at various stages of anodic dissolution were studied simultaneously. It was found that the slimes formed both during chemical and during electrochemical destruction of ruthenium-iron alloys are finely dispersed systems of complex composition, analogous to those formed in the course of electrochemical dissolution of Ni-Ru alloys, which were found to contain oxide phases of ruthenium (by x-ray spectroscopy and ESCA) and of nickel (by x-ray phase analysis). The difference between the slime compositions is determined mainly by kinetic factors.

  20. Corrosion behavior of Au and Ag modified Cu-Ni-Mn alloys.

    PubMed

    Wright, S R; Cocks, F H; Gettleman, L

    1980-04-01

    The linear electrochemical polarization method was used to provide quantitative in vitro measurements of corrosion rates as a function of exposure time for Cu-Ni-Mn, Cu-Ni-Mn-Au, Cu-Ni-Mn-Ag, and Cu-Ni-Mn-Au-Ag alloys in artificial saliva. Both Au and Ag additives to dental-cast Cu-Ni-Mn alloys lowered the corrosion rate significantly.

  1. Mechanical properties and microstructures of dental cast Ti-6Nb-4Cu, Ti-18Nb-2Cu, and Ti-24Nb-1Cu alloys.

    PubMed

    Takahashi, Masatoshi; Kikuchi, Masafumi; Takada, Yukyo

    2016-01-01

    The mechanical properties -tensile strength, yield strength, elongation after fracture, and Vickers hardness- and alloy phases of the dental cast alloys Ti-6%Nb-4%Cu, Ti-18%Nb-2%Cu, and Ti-24%Nb-1%Cu were investigated. Ti-6%Nb-4%Cu consisted of a single α-phase, while Ti-18%Nb-2%Cu and Ti-24%Nb-1%Cu consisted of α- and β-phases. The tensile strengths, yield strengths, and hardnesses of these alloys were higher than those of Ti-5%Cu and Ti-30%Nb; however, their breaking elongations were smaller. These differences in the mechanical properties are attributable to solid-solution strengthening or to precipitation strengthening by the dual-phase (α+β) structure. Thus, Ti-Nb-Cu alloys are suitable for use in high-strength dental prostheses, such as implantretained superstructures and narrow-diameter implants.

  2. Anodic Behavior of Alloy 22 in Calcium Chloride and in Calcium Chloride Plus Calcium Nitrate Brines

    SciTech Connect

    Evans, K J; Day, S D; Ilevbare, G O; Whalen, M T; King, K J; Hust, G A; Wong, L L; Estill, J C; Rebak, R B

    2003-05-13

    Alloy 22 (UNS N60622) is a nickel-based alloy, which is extensively used in aggressive industrial applications, especially due to its resistance to localized corrosion and stress corrosion cracking in high chloride environments. The purpose of this work was to characterize the anodic behavior of Alloy 22 in concentrated calcium chloride (CaCl{sub 2}) brines and to evaluate the inhibitive effect of nitrate, especially to localized corrosion. Standard electrochemical tests such as polarization resistance and cyclic polarization were used. Results show that the corrosion potential of Alloy 22 was approximately -360 mV in the silver-silver chloride (SSC) scale and independent of the tested temperature. Cyclic polarization tests showed that Alloy 22 was mainly susceptible to localized attack in 5 M CaCl{sub 2} at 75 C and higher temperatures. The addition of nitrate in a molar ratio of chloride to nitrate equal to 10 increased the onset of localized corrosion to approximately 105 C. The addition of nitrate to the solution also decreased the uniform corrosion rate and the passive current of the alloy.

  3. A Practical Anodic and Cathodic Curve Intersection Model to Understand Multiple Corrosion Potentials of Fe-Based Glassy Alloys in OH- Contained Solutions.

    PubMed

    Li, Y J; Wang, Y G; An, B; Xu, H; Liu, Y; Zhang, L C; Ma, H Y; Wang, W M

    2016-01-01

    A practical anodic and cathodic curve intersection model, which consisted of an apparent anodic curve and an imaginary cathodic line, was proposed to explain multiple corrosion potentials occurred in potentiodynamic polarization curves of Fe-based glassy alloys in alkaline solution. The apparent anodic curve was selected from the measured anodic curves. The imaginary cathodic line was obtained by linearly fitting the differences of anodic curves and can be moved evenly or rotated to predict the number and value of corrosion potentials.

  4. Surface alloying of Pb on Cu(111): a TEAS study

    NASA Astrophysics Data System (ADS)

    de Beauvais, Ch.; Girard, Y.; Pérard, C.; Croset, B.; Mutaftschiev, B.

    1996-11-01

    Thermal energy atom scattering on vacuum deposited Pb submonolayers on Cu(111) in close to equilibrium conditions, at substrate temperatures between 303 K and 413 K, gives evidence for: (a) decoration by Pb atoms of monatomic steps on the Cu surface at degree of coverage 0 < θ < 0.004; (b) formation of disordered surface alloy in the first lattice plane of the copper substrate in the coverage range 0.004 < θ < 0.21; (c) formation of non-alloyed Pb layer with a p(4 × 4) structure above this coverage, up to the monolayer ( θ ≈ 0.56). The latter transition is shown to be of first order. The role of the deposition kinetics in far from equilibrium conditions is pointed out.

  5. Facile synthesis of complex shaped Pt-Cu alloy architectures

    NASA Astrophysics Data System (ADS)

    Nosheen, Farhat; Ni, Bing; Xu, Xiaobin; Yang, Haozhou; Zhang, Zhicheng; Wang, Xun

    2016-07-01

    Several intricate Pt-Cu alloy architectures have been synthesized including hexapod backbones with stretchers and caved octahedron like hexapods, as well as some other intermediates with complex structures. The mechanistic study indicates that the shape is realized via a competitive effect between etching and growth induced by different chemicals.Several intricate Pt-Cu alloy architectures have been synthesized including hexapod backbones with stretchers and caved octahedron like hexapods, as well as some other intermediates with complex structures. The mechanistic study indicates that the shape is realized via a competitive effect between etching and growth induced by different chemicals. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr03511f

  6. Solidification behavior and structure of Al-Cu alloy welds

    SciTech Connect

    Brooks, J.A.; Li, M.; Yang, N.C.Y.

    1997-09-01

    The microsegregation behavior of electron beam (EB) and gas tungsten arc (GTA) welds of Al-Cu alloys covering a range from 0.19 to 7.74 wt% Cu were characterized for dendrite core concentrations and fraction eutectic solidification. Although a single weld speed of 12.7 mm/sec was used, some differences were observed in the segregation behavior of the two weld types. The microsegregation behavior was also modeled using a finite differences technique considering dendrite tip and eutectic undercooling and solid state diffusion. Fairly good agreement was observed between measured and calculated segregation behavior although differences between the two weld types could not be completely accounted for. The concept of dendrite tip undercooling was used to explain the formation of a single through thickness centerline grain in the higher alloy content GTA welds.

  7. Anode performance of lithium-silicon alloy prepared by mechanical alloying for use in all-solid-state lithium secondary batteries

    NASA Astrophysics Data System (ADS)

    Park, Hye Won; Song, Jung-Hoon; Choi, Heekyu; Jin, Joo Sung; Lim, Hyung-Tae

    2014-08-01

    Li22Si5 alloy powder was synthesized by mechanical alloying and its electrochemical performance was investigated for use in solid-state battery anodes. Two types of anode powder were prepared: 1) Li-Si alloy powder after mechanical alloying with Li-granules and Si-powder, and 2) Li-Si alloy powder from the first process followed by additional ball milling for reduction of particle size. Using these anode materials, all-solid-state lithium batteries were assembled with Li4Ti5O12 (LTO) as cathode and Li2S-P2S5 as electrolyte. Impedance spectra of the two types of cells were measured, and the results showed that the non-ohmic resistance was less in the case of the cell with the secondary ball-milled, fine anode powder. Galvanostatic charge/discharge tests were also performed, and capacity was increased about two times by the additional powder milling process; which is consistent with the impedance results. Thus, the results from the present work indicate that using the secondary milling process to refine the electrode powder is an effective way to increase the kinetics of alloying and de-alloying with improvement in interfacial properties in all-solid-state lithium secondary batteries.

  8. The Incorporation of Lithium Alloying Metals into Carbon Matrices for Lithium Ion Battery Anodes

    NASA Astrophysics Data System (ADS)

    Hays, Kevin A.

    An increased interest in renewable energies and alternative fuels has led to recognition of the necessity of wide scale adoption of the electric vehicle. Automotive manufacturers have striven to produce an electric vehicle that can match the range of their petroleum-fueled counterparts. However, the state-of-the-art lithium ion batteries used to power the current offerings still do not come close to the necessary energy density. The energy and power densities of the lithium ion batteries must be increased significantly if they are going to make electric vehicles a viable option. The chemistry of the lithium ion battery, based on lithium cobalt oxide cathodes and graphite anodes, is limited by the amount of lithium the cathode can provide and the anode will accept. While these materials have proven themselves in portable electronics over the past two decades, plausible higher energy alternatives do exist. The focus is of this study is on anode materials that could achieve a capacity of more than 3 times greater than that of graphite anodes. The lithium alloying anode materials investigated and reported herein include tin, arsenic, and gallium arsenide. These metals were synthesized with nanoscale dimensions, improving their electrochemical and mechanical properties. Each exhibits their own benefits and challenges, but all display opportunities for incorporation in lithium ion batteries. Tin is incorporated in multilayer graphene nanoshells by introducing small amounts of metal in the core and, separately, on the outside of these spheres. Electrolyte decomposition on the anode limits cycle life of the tin cores, however, tin vii oxides introduced outside of the multilayer graphene nanoshells have greatly improved long term battery performance. Arsenic is a lithium alloying metal that has largely been ignored by the research community to date. One of the first long term battery performance tests of arsenic is reported in this thesis. Anodes were made from nanoscale

  9. Microadditions to alloys of the system Cu-Sn-Ti

    SciTech Connect

    Kizikov, E.D.; Kebko, V.P.

    1987-07-01

    The authors assess the microstructure and some mechanical properties of a Cu-20% Sn-10% Ti alloy, used extensively as binders for diamond drill bits, under the influence of a series of dopants including lanthanum, yttrium, vanadium, molybdenum, rhenium, boron, lanthanum hexaboride, silicon nitride, titanium nitride, and titanium carbide. Doping procedures are outlined. Microadditions of all dopants were found to promote ductility, yield strength, and structural transformations.

  10. A three-dimensional Macroporous Cu/SnO2 composite anode sheet prepared via a novel method

    SciTech Connect

    Xu, Wu; Canfield, Nathan L.; Wang, Deyu; Xiao, Jie; Nie, Zimin; Zhang, Jiguang

    2010-11-01

    Macroporous Cu/SnO2 composite anode sheets were prepared by a novel method which is based on slurry blending, tape casting, sintering, and reducing of metal oxides. Such composite Cu/SnO2 anode sheets have no conducting carbons and binders, and show improved discharge capacity and cycle life than the SnO2 electrode from conventional tape-casting method on Cu foil. This methodology produces limited wastes and is also adaptable to many other materials. It is easy for industrial scale production. With the optimization of particle size of the metal oxide, pore size, pore volume and other factors, this kind of macroporous Cu/SnO2 composite anode sheets could give significantly improved capacity and cycle life.

  11. Silicon purification using a Cu-Si alloy source

    NASA Technical Reports Server (NTRS)

    Powell, R. C.; Tejedor, P.; Olson, J. M.

    1986-01-01

    Production of 99.9999% pure silicon from 98% pure metallurgical grade (MG) silicon by a vapor transport filtration process (VTP) is described. The VTF process is a cold wall version of an HCl chemical vapor transport technique using a Si:Cu3Si alloy as the silicon source. The concentration, origin, and behavior of the various impurities involved in the process were determined by chemically analyzing alloys of different purity, the slag formed during the alloying process, and the purified silicon. Atomic absorption, emission spectrometry, inductively coupled plasma, spark source mass spectrometry, and secondary ion mass spectroscopy were used for these analyses. The influence of the Cl/H ratio and the deposition temperature on the transport rate was also investigated.

  12. Morphology and mechanical properties of nanocrystalline Cu/Ag alloy

    NASA Astrophysics Data System (ADS)

    Li, Ao; Szlufarska, Izabela

    2017-04-01

    Hybrid Monte Carlo (MC)/molecular dynamics (MD) simulations are conducted to study the microstructures of nanocrystalline (nc) Cu/Ag alloys with various Ag concentrations. When the Ag concentration is below 50 Ag atoms/nm!, an increase in Ag concentration leads to a gradual growth of monolayer grain boundary (GB) complexions into nanolayer complexions. Above the concentration of 50 Ag atoms/nm!, wetting layers with a bulk crystalline phase are observed. The effects of Ag on mechanical properties and deformation mechanisms of nc Cu/Ag alloys are investigated in MD simulations of uniaxial tension. GB sliding resistance is found to first increase and then decrease with an increase in Ag concentration. Surprisingly, we also find that the dislocation density decreases monotonically with an increase in Ag concentration, which suggests that the grain interiors are softened by the introduction of Ag dopants at GBs. In addition, there is a critical Ag concentration that maximizes flow stress of nc Cu/Ag alloys. The flow stress, GB sliding resistance, and the intragranular dislocation densities become less sensitive to Ag dopants when the grain diameter increases from 5nm to 40nm.

  13. Metal-organic framework derived porous CuO/Cu2O composite hollow octahedrons as high performance anode materials for sodium ion batteries.

    PubMed

    Zhang, Xiaojie; Qin, Wei; Li, Dongsheng; Yan, Dong; Hu, Bingwen; Sun, Zhuo; Pan, Likun

    2015-11-25

    Porous CuO/Cu2O composite hollow octahedrons were synthesized simply by annealing Cu-based metal-organic framework templates. When evaluated as anode materials for sodium ion batteries, they exhibit a high maximum reversible capacity of 415 mA h g(-1) after 50 cycles at 50 mA g(-1) with excellent cycling stability and good rate capability.

  14. Fabrication of nanoporous silver by de-alloying Cu-Zr-Ag amorphous alloys

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Xiao, Shang-gang; Zhang, Tao

    2016-07-01

    Nanoporous silver (NPS) with a ligament size ranging from 15 to 40 nm was fabricated by de-alloying (Cu50Zr50)100- x Ag x ( x = 10at%, 20at%, 30at%, and 40at%) amorphous ribbons in a mixed aqueous solution of hydrofluoric (HF) acid and nitric acid under free corrosion conditions. Nanoporous silver ligaments and pore sizes were able to be fine-tuned through tailoring the chemical composition, corrosion conditions, and de-alloying time. The ligament size increases with an increase in Ag content and de-alloying time, but decreases with an increase in HF concentration. This phenomenon may be attributed to the dissolution of Zr/Cu and the diffusion, aggregation, nucleation, and recrystallization of Ag, leading to an oriented attachment of adjacent nanocrystals as revealed by TEM analysis.

  15. Increasing strength and conductivity of Cu alloy through abnormal plastic deformation of an intermetallic compound

    PubMed Central

    Han, Seung Zeon; Lim, Sung Hwan; Kim, Sangshik; Lee, Jehyun; Goto, Masahiro; Kim, Hyung Giun; Han, Byungchan; Kim, Kwang Ho

    2016-01-01

    The precipitation strengthening of Cu alloys inevitably accompanies lowering of their electric conductivity and ductility. We produced bulk Cu alloys arrayed with nanofibers of stiff intermetallic compound through a precipitation mechanism using conventional casting and heat treatment processes. We then successfully elongated these arrays of nanofibers in the bulk Cu alloys to 400% of original length without breakage at room temperature using conventional rolling process. By inducing such an one-directional array of nanofibers of intermetallic compound from the uniform distribution of fine precipitates in the bulk Cu alloys, the trade-off between strength and conductivity and between strength and ductility could be significantly reduced. We observed a simultaneous increase in electrical conductivity by 1.3 times and also tensile strength by 1.3 times in this Cu alloy bulk compared to the conventional Cu alloys. PMID:27488621

  16. Increasing strength and conductivity of Cu alloy through abnormal plastic deformation of an intermetallic compound.

    PubMed

    Han, Seung Zeon; Lim, Sung Hwan; Kim, Sangshik; Lee, Jehyun; Goto, Masahiro; Kim, Hyung Giun; Han, Byungchan; Kim, Kwang Ho

    2016-08-04

    The precipitation strengthening of Cu alloys inevitably accompanies lowering of their electric conductivity and ductility. We produced bulk Cu alloys arrayed with nanofibers of stiff intermetallic compound through a precipitation mechanism using conventional casting and heat treatment processes. We then successfully elongated these arrays of nanofibers in the bulk Cu alloys to 400% of original length without breakage at room temperature using conventional rolling process. By inducing such an one-directional array of nanofibers of intermetallic compound from the uniform distribution of fine precipitates in the bulk Cu alloys, the trade-off between strength and conductivity and between strength and ductility could be significantly reduced. We observed a simultaneous increase in electrical conductivity by 1.3 times and also tensile strength by 1.3 times in this Cu alloy bulk compared to the conventional Cu alloys.

  17. Increasing strength and conductivity of Cu alloy through abnormal plastic deformation of an intermetallic compound

    NASA Astrophysics Data System (ADS)

    Han, Seung Zeon; Lim, Sung Hwan; Kim, Sangshik; Lee, Jehyun; Goto, Masahiro; Kim, Hyung Giun; Han, Byungchan; Kim, Kwang Ho

    2016-08-01

    The precipitation strengthening of Cu alloys inevitably accompanies lowering of their electric conductivity and ductility. We produced bulk Cu alloys arrayed with nanofibers of stiff intermetallic compound through a precipitation mechanism using conventional casting and heat treatment processes. We then successfully elongated these arrays of nanofibers in the bulk Cu alloys to 400% of original length without breakage at room temperature using conventional rolling process. By inducing such an one-directional array of nanofibers of intermetallic compound from the uniform distribution of fine precipitates in the bulk Cu alloys, the trade-off between strength and conductivity and between strength and ductility could be significantly reduced. We observed a simultaneous increase in electrical conductivity by 1.3 times and also tensile strength by 1.3 times in this Cu alloy bulk compared to the conventional Cu alloys.

  18. Electrochemical behavior of anodized AA6063-T6 alloys affected by matrix structures

    NASA Astrophysics Data System (ADS)

    Huang, Yung-Sen; Shih, Teng-Shih; Wu, Chen-En

    2013-01-01

    AA 6063 alloys were cold-rolled (CR) either before or after solution treatment (S) and then different samples were artificially aged (T6) to obtain different samples (CRST6 and SCRT6). The highest dislocation density was observed in the SCRT6 sample which also showed the lowest particle count among the three samples; ST6, CRST6 and SCRT6. Subsequently, all samples were anodized in a 15 wt% sulfuric acid solution for different time spans to obtain anodic aluminum oxide (AAO) films. The anodized samples were further analyzed with X-ray Photoelectron Spectroscopy (XPS) analysis. We determined that the constituent phases in the AAO film were composed of hydrated amorphous alumina, hydrated oxide (Al(OH)3) and oxyhydroxide (AlOOH) phases together with some silicon-containing particles trapped in the films on all samples. In the electrochemical test, the silicon-containing particles and hydrated Al(OH)3 oxide that existed at the electrolyte/film (e/f) interface were found to inversely influence the corrosion resistance of the anodized samples.

  19. Effect of protein adsorption on the corrosion behavior of 70Cu-30Ni alloy in artificial seawater.

    PubMed

    Torres Bautista, Blanca E; Carvalho, Maria L; Seyeux, Antoine; Zanna, Sandrine; Cristiani, Pierangela; Tribollet, Bernard; Marcus, Philippe; Frateur, Isabelle

    2014-06-01

    Copper alloys often used in cooling circuits of industrial plants can be affected by biocorrosion induced by biofilm formation. The objective of this work was to study the influence of protein adsorption, which is the first step in biofilm formation, on the electrochemical behavior of 70Cu-30Ni (wt.%) alloy in static artificial seawater and on the chemical composition of oxide layers. For that purpose, electrochemical measurements performed after 1h of immersion were combined to surface analyses. A model is proposed to analyze impedance data. In the presence of bovine serum albumin (BSA, model protein), the anodic charge transfer resistance deduced from EIS data at Ecorr is slightly higher, corresponding to lower corrosion current. Without BSA, two oxidized layers are shown by XPS and ToF-SIMS: an outer layer mainly composed of copper oxide (Cu2O redeposited layer) and an inner layer mainly composed of oxidized nickel, with a global thickness of ~30nm. The presence of BSA leads to a mixed oxide layer (CuO, Cu2O, Ni(OH)2) with a lower thickness (~10nm). Thus, the protein induces a decrease of the dissolution rate at Ecorr and hence a decrease of the amount of redeposited Cu2O and of the oxide layer thickness. © 2013.

  20. Mechanical and Thermal Properties of Two Cu-Cr-Nb Alloys and NARloy-Z

    NASA Technical Reports Server (NTRS)

    Ellis, David L.; Michal, Gary M.

    1996-01-01

    A series of creep tests were conducted on Cu-8 Cr-4 Nb (Cu-8 at.% Cr-4 at.% Nb), Cu-4 Cr-2 Nb (Cu-4 at.% Cr-2 at% Nb), and NARloy-Z (Cu-3 wt.% Ag-0.5 wt.% Zr) samples to determine their creep properties. In addition, a limited number of low cycle fatigue and thermal conductivity tests were conducted. The Cu-Cr-Nb alloys showed a clear advantage in creep life and sustainable load over the currently used NARloy-Z. Increases in life at a given stress were between 100% and 250% greater for the Cu-Cr-Nb alloys depending on the stress and temperature. For a given life, the Cu-Cr-Nb alloys could support a stress between 60% and 160% greater than NARloy-Z. Low cycle fatigue lives of the Cu-8 Cr-4 Nb alloy were equivalent to NARloy-Z at room temperature. At elevated temperatures (538 C and 650 C), the fatigue lives were 50% to 200% longer than NARloy-Z samples tested at 538 C. The thermal conductivities of the Cu-Cr-Nb alloys remained high, but were lower than NARloy-Z and pure Cu. The Cu-Cr-Nb thermal conductivities were between 72% and 96% that of pure Cu with the Cu-4 Cr-2 Nb alloy having a significant advantage in thermal conductivity over Cu-8 Cr4 Nb. In comparison, stainless steels with equivalent strengths would have thermal conductivities less than 25% the thermal conductivity of pure Cu. The combined results indicate that the Cu-Cr-Nb alloys offer an attractive alternative to current high temperature Cu-based alloys such as NARloy-Z.

  1. Alloying effect via comparative studies of ethanol dehydrogenation on Cu(1 1 1), Cu3Pd(1 1 1), and Cu3Pt(1 1 1)

    NASA Astrophysics Data System (ADS)

    Wu, Ruitao; Wang, Lichang

    2017-06-01

    Ethanol dehydrogenations on Cu(1 1 1), Cu3Pd(1 1 1), and Cu3Pt(1 1 1) were studied using density functional theory with a PBE functional. The α-C-H and β-C-H scissions are endothermic on all surfaces while the O-H scission is exothermic on Cu(1 1 1) and Cu3Pt(1 1 1) but endothermic on Cu3Pd(1 1 1). The ethanol dehydrogenation occurs on Cu(1 1 1) through both α-C-H and O-H scissions but on Cu3Pd(1 1 1) and Cu3Pt(1 1 1) through only α-C-H scission. Furthermore, alloying Pt or Pd with Cu shows an increase in reaction rate at 493 K by more than 3 orders of magnitude, thus illustrating the promise of alloying Pt or Pd in Cu catalysts for ethanol dehydrogenation.

  2. Structural, electronic and mechanical properties of alloyed Au-Cu monolayer

    NASA Astrophysics Data System (ADS)

    Kapoor, Pooja; Sharma, Munish; Kumar, A.; Chandel, S. K.; Ahluwalia, P. K.

    2017-05-01

    We present a DFT based comparative study of structural, electronic and mechanical properties of Au-Cu alloyed monolayer with its pristine counterparts (Au, Cu monolayer). The value of lattice constant, binding energy and bond length of Au-Cu alloyed monolayer lies in between the values for pristine Au and Cu monolayer. An indirect band gap of 0.46 eV has been found for Au-Cu alloyed monolayer while its pristine counterparts are metallic. The band gap in alloyed Au-Cu monolayer can be further tuned with biaxial compression strain. These tunable properties of Au-Cu alloyed monolayer could have applications in nanoelectronics, sensors and nano-electromechanical systems (NEMS).

  3. Preparation of Copper (Cu)-Nickel (Ni) Alloy Thin Films for Bilayer Graphene Growth

    DTIC Science & Technology

    2016-02-01

    Laboratory Preparation of Copper (Cu)-Nickel (Ni) Alloy Thin Films for Bilayer Graphene Growth by Andrew Chen and Eugene Zakar Sensors and Electron...COVERED (From - To) June–August 2015 4. TITLE AND SUBTITLE Preparation of Copper (Cu)-Nickel (Ni) Alloy Thin Films for Bilayer Graphene Growth 5a...distribution is unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT Co-sputtered copper (Cu)-nickel (Ni) alloys with layered thin-film ratios of 6

  4. Biologically activated noble metal alloys at the nanoscale: for lithium ion battery anodes.

    PubMed

    Lee, Yun Jung; Lee, Youjin; Oh, Dahyun; Chen, Tiffany; Ceder, Gerbrand; Belcher, Angela M

    2010-07-14

    We report the synthesis and electrochemical activity of gold and silver noble metals and their alloy nanowires using multiple virus clones as anode materials for lithium ion batteries. Using two clones, one for specificity (p8#9 virus) and one versatility (E4 virus), noble metal nanowires of high-aspect ratio with diameters below 50 nm were successfully synthesized with control over particle sizes, morphologies, and compositions. The biologically derived noble metal alloy nanowires showed electrochemical activities toward lithium even when the electrodes were prepared from bulk powder forms. The improvement in capacity retention was accomplished by alloy formation and surface stabilization. Although the cost of noble metals renders them a less ideal choice for lithium ion batteries, these noble metal/alloy nanowires serve as great model systems to study electrochemically induced transformation at the nanoscale. Given the demonstration of the electrochemical activity of noble metal alloy nanowires with various compositions, the M13 biological toolkit extended its utility for the study on the basic electrochemical property of materials.

  5. Solution-dispersed CuO nanoparticles anode buffer layer: Effect of ultrasonic agitation duration on photovoltaic performance

    NASA Astrophysics Data System (ADS)

    Sabri, Nasehah Syamin; Yap, Chi Chin; Yahaya, Muhammad; Salleh, Muhamad Mat; Jumali, Mohammad Hafizuddin Haji

    2016-11-01

    The performance of inverted type hybrid organic solar cell based on poly(3-hexyltheopene):[6,6]-phenyl C61-butyric acid methyl ester (P3HT:PCBM) can be improved by adding an anode buffer layer of copper oxide (CuO). CuO that serves as an electron blocking layer which could effectively reduce the charge recombination at the photoactive layer (P3HT:PCBM)/silver (Ag) interfaces. At the same time, Cuo anode buffer layer could accelerate the holes collection from the photoactive layer to the top electrode. In this study we investigated the effects of ultrasonic agitation duration in preparation of solution-dispersed CuO anode buffer layer on the performance of the devices with a configuration of fluorine tin oxide (FTO)/zinc oxide (ZnO) nanorod arrays/P3HT:PCBM/ CuO/Ag. Different durations of ultrasonic agitation (0, 5, 15 and 25 min) were used for CuO nanoparticles solution dispersion to obtain the optimum particle size distribution of CuO. It was found that the smallest average particle size of CuO was obtained by applying the ultrasonic agitation for longest duration of 25 min. The highest power conversion efficiency of 1.22% was recorded from the device incorporating with CuO anode buffer layer with the smallest average particle size. It is believed that CuO anode buffer layer with the smallest average particle size had the least agglomerates, thus leading to better film formation and contact surface area.

  6. Ti-based glassy alloys in Ti-Cu-Zr-Sn system

    NASA Astrophysics Data System (ADS)

    Wang, ZengRui; Dong, DanDan; Qiang, JianBing; Wang, Qing; Wang, YingMin; Dong, Chuang

    2013-07-01

    Bulk amorphous formation in Ti-Cu-based multicomponent alloys, free of Ni, Pd and Be elements, were studied using the cluster-plus-glue-atom model. The basic cluster formula was revealed as [Ti9Cu6]Cu3 to explain the best binary glass forming composition Ti50Cu50=Ti9Cu9, where the CN14 rhombi-dodecahedron Ti9Cu6 was the principal cluster in the devitrification phase CuTi. This basic cluster formula was further alloyed with Zr and Sn and a critical glass forming ability was reached at (Ti7.2Zr1.8)(Cu8.72Sn0.28) and (Ti7.2Zr1.8)(Cu8.45Sn0.55) up to 5 mm in diameter by suction casting, which was the largest in Ti-Cu-based and Ni-, Pd- and Be-free alloys.

  7. Monte Carlo simulations of copper clustering in Fe-Cu alloys under irradiation

    NASA Astrophysics Data System (ADS)

    Kwon, J.; Kwon, S. C.; Hong, J. H.

    2004-10-01

    We present the computational approach for studying the microstructures of Cu clusters in Fe-Cu alloys by combining the molecular dynamics (MD) simulation and Monte Carlo methods. The MD simulation is used to characterize the primary damage resulting from the displacement cascade in Fe. Then, using the Metropolis Monte Carlo methods, the microstructure of the Cu clusters is predicted under the assumption that the system will evolve towards the equilibrium state. The formation of the Cu clusters is apparent for Fe-Cu alloys of a higher Cu content (1.0 w/o), whereas the degree of Cu clustering is not significant for the lower Cu content (0.1 w/o) alloys. The atomic configuration of the Cu-vacancy complex under irradiation, produced by this simulation, is in a fair agreement with the experiments. The simulation is expected to provide important information on the Cu-cluster morphology, which is useful for experimental data analysis.

  8. Anodic vacuum arc developed nanocrystalline Cu-Ni and Fe-Ni thin film thermocouples

    SciTech Connect

    Mukherjee, S. K.; Sinha, M. K.; Pathak, B.; Rout, S. K.; Barhai, P. K.

    2009-12-01

    This paper deals with the development of nanocrystalline Cu-Ni and Fe-Ni thin film thermocouples (TFTCs) by using ion-assisted anodic vacuum arc deposition technique. The crystallographic structure and surface morphology of individual layer films have been studied by x-ray diffraction and scanning electron microscopy, respectively. The resistivity, temperature coefficient of resistance, and thermoelectric power of as deposited and annealed films have been measured. The observed departure of these transport parameters from their respective bulk values can be understood in terms of intrinsic scattering due to enhanced crystallite boundaries. From the measured values of thermoelectric power and the corresponding temperature coefficient of resistance of annealed Cu, Ni, and Fe films, the calculated values of log derivative of the mean free path of conduction electrons at the Fermi surface with respect to energy (U) are found to be -0.51, 3.22, and -8.39, respectively. The thermoelectric response of annealed Cu-Ni and Fe-Ni TFTCs has been studied up to a maximum temperature difference of 300 deg. C. Reproducibility of TFTCs has been examined in terms of the standard deviation in thermoelectric response of 16 test samples for each pair. Cu-Ni and Fe-Ni TFTCs agree well with their wire thermocouple equivalents. The thermoelectric power values of Cu-Ni and Fe-Ni TFTCs at 300 deg. C are found to be 0.0178 and 0.0279 mV/ deg. C, respectively.

  9. Anodic vacuum arc developed nanocrystalline Cu-Ni and Fe-Ni thin film thermocouples

    NASA Astrophysics Data System (ADS)

    Mukherjee, S. K.; Sinha, M. K.; Pathak, B.; Rout, S. K.; Barhai, P. K.

    2009-12-01

    This paper deals with the development of nanocrystalline Cu-Ni and Fe-Ni thin film thermocouples (TFTCs) by using ion-assisted anodic vacuum arc deposition technique. The crystallographic structure and surface morphology of individual layer films have been studied by x-ray diffraction and scanning electron microscopy, respectively. The resistivity, temperature coefficient of resistance, and thermoelectric power of as deposited and annealed films have been measured. The observed departure of these transport parameters from their respective bulk values can be understood in terms of intrinsic scattering due to enhanced crystallite boundaries. From the measured values of thermoelectric power and the corresponding temperature coefficient of resistance of annealed Cu, Ni, and Fe films, the calculated values of log derivative of the mean free path of conduction electrons at the Fermi surface with respect to energy (U) are found to be -0.51, 3.22, and -8.39, respectively. The thermoelectric response of annealed Cu-Ni and Fe-Ni TFTCs has been studied up to a maximum temperature difference of 300°C. Reproducibility of TFTCs has been examined in terms of the standard deviation in thermoelectric response of 16 test samples for each pair. Cu-Ni and Fe-Ni TFTCs agree well with their wire thermocouple equivalents. The thermoelectric power values of Cu-Ni and Fe-Ni TFTCs at 300°C are found to be 0.0178 and 0.0279mV/°C, respectively.

  10. Elastocaloric effect in CuAlZn and CuAlMn shape memory alloys under compression.

    PubMed

    Qian, Suxin; Geng, Yunlong; Wang, Yi; Pillsbury, Thomas E; Hada, Yoshiharu; Yamaguchi, Yuki; Fujimoto, Kenjiro; Hwang, Yunho; Radermacher, Reinhard; Cui, Jun; Yuki, Yoji; Toyotake, Koutaro; Takeuchi, Ichiro

    2016-08-13

    This paper reports the elastocaloric effect of two Cu-based shape memory alloys: Cu68Al16Zn16 (CuAlZn) and Cu73Al15Mn12 (CuAlMn), under compression at ambient temperature. The compression tests were conducted at two different rates to approach isothermal and adiabatic conditions. Upon unloading at a strain rate of 0.1 s(-1) (adiabatic condition) from 4% strain, the highest adiabatic temperature changes (ΔTad) of 4.0 K for CuAlZn and 3.9 K for CuAlMn were obtained. The maximum stress and hysteresis at each strain were compared. The stress at the maximum recoverable strain of 4.0% for CuAlMn was 120 MPa, which is 70% smaller than that of CuAlZn. A smaller hysteresis for the CuAlMn alloy was also obtained, about 70% less compared with the CuAlZn alloy. The latent heat, determined by differential scanning calorimetry, was 4.3 J g(-1) for the CuAlZn alloy and 5.0 J g(-1) for the CuAlMn alloy. Potential coefficients of performance (COPmat) for these two alloys were calculated based on their physical properties of measured latent heat and hysteresis, and a COPmat of approximately 13.3 for CuAlMn was obtained.This article is part of the themed issue 'Taking the temperature of phase transitions in cool materials'. © 2016 The Author(s).

  11. Performance improvement of Sn-Co alloy film anodes for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Li, Peng; Chen, Yun; Zeng, Duoqing; Xiao, Qizhen; Li, Zhaohui; Lei, Gangtie

    2014-05-01

    Three sets of Sn-Co alloy films were electrochemically deposited onto nodule-type Cu foil in aqueous solution. The results of X-ray diffraction (XRD), atomic absorption spectroscopy (AAS) and scanning electron microscopy (SEM) proved that the electrochemical current density and the depositing time had influence on the structure and the morphology of the alloy films. The electrochemical properties of the Sn-Co alloy film electrodes for lithium-ion battery were investigated by galvanostatic charge-discharge test and cyclic voltammetry (CV). The Sn-Co alloy with the thickness of 0.8 μm created at the current density of 15 mA cm-2 presents excellent electrochemical performance with the discharge capacity of 949.3 mAh g-1 at the first cycle and 661.1 mAh g-1 after 70 cycles. The high coulombic efficiency of almost 100% can be observed at different current rate. The improved performance is attributed to the structure of Cu foil, the optimized Co content and thickness of the alloy film, which were beneficial to strengthen the adhesion of the active materials to the current collector, shorten diffusion length of lithium ions and reduce the electrical resistance.

  12. Structural and thermal properties of Cu-Hf-Ti bulk amorphous alloys

    NASA Astrophysics Data System (ADS)

    Rontó, V.; Nagy, E.; Svéda, M.; Roósz, A.; Tranta, F.

    2009-01-01

    Cu-Hf-Ti amorphous alloys are high strength and wear resistant materials. Master alloys of Cu57.5Hf27.5Ti15 and Cu57.5Hf25Ti17.5 ternary alloys have been prepared by arc melting, and wedge and rod shaped samples have been cast by centrifugal casting. Liquidus and solidus temperatures of the alloys were determined by DTA. The fully amorphous size was determined by X-ray diffraction. Thermodynamic properties of the amorphous alloys were studied by DSC measurements and Kissinger analyses were performed.

  13. Enhanced electrocatalytic performance of Pt monolayer on nanoporous PdCu alloy for oxygen reduction

    NASA Astrophysics Data System (ADS)

    Hou, Linxi; Qiu, Huajun

    2012-10-01

    By selectively dealloying Al from PdxCu20-xAl80 ternary alloys in 1.0 M NaOH solution, nanoporous PdCu (np-PdCu) alloys with different Pd:Cu ratios are obtained. By a mild electrochemical dealloying treatment, the np-PdCu alloys are facilely converted into np-PdCu near-surface alloys with a nearly pure-Pd surface and PdCu alloy core. The np-PdCu near-surface alloys are then used as substrates to fabricate core-shell catalysts with a Pt monolayer as shell and np-PdCu as core by a Cu-underpotential deposition-Pt displacement strategy. Electrochemical measurements demonstrate that the Pt monolayer on np-Pd1Cu1 (Pt/np-Pd1Cu1) exhibits the highest Pt surface-specific activity towards oxygen reduction, which is ˜5.8-fold that of state-of-the-art Pt/C catalyst. The Pt/np-Pd1Cu1 also shows much enhanced stability with ˜78% active surface retained after 10,000 cycles (0.6-1.2 V vs. RHE). Under the same condition, the active surface of Pt/C drops to ˜28%.

  14. Design and development of novel antibacterial Ti-Ni-Cu shape memory alloys for biomedical application

    NASA Astrophysics Data System (ADS)

    Li, H. F.; Qiu, K. J.; Zhou, F. Y.; Li, L.; Zheng, Y. F.

    2016-11-01

    In the case of medical implants, foreign materials are preferential sites for bacterial adhesion and microbial contamination, which can lead to the development of prosthetic infections. Commercially biomedical TiNi shape memory alloys are the most commonly used materials for permanent implants in contact with bone and dental, and the prevention of infections of TiNi biomedical shape memory alloys in clinical cases is therefore a crucial challenge for orthopaedic and dental surgeons. In the present study, copper has been chosen as the alloying element for design and development novel ternary biomedical Ti‒Ni‒Cu shape memory alloys with antibacterial properties. The effects of copper alloying element on the microstructure, mechanical properties, corrosion behaviors, cytocompatibility and antibacterial properties of biomedical Ti‒Ni‒Cu shape memory alloys have been systematically investigated. The results demonstrated that Ti‒Ni‒Cu alloys have good mechanical properties, and remain the excellent shape memory effects after adding copper alloying element. The corrosion behaviors of Ti‒Ni‒Cu alloys are better than the commercial biomedical Ti‒50.8Ni alloys. The Ti‒Ni‒Cu alloys exhibit excellent antibacterial properties while maintaining the good cytocompatibility, which would further guarantee the potential application of Ti‒Ni‒Cu alloys as future biomedical implants and devices without inducing bacterial infections.

  15. Design and development of novel antibacterial Ti-Ni-Cu shape memory alloys for biomedical application

    PubMed Central

    Li, H. F.; Qiu, K. J.; Zhou, F. Y.; Li, L.; Zheng, Y. F.

    2016-01-01

    In the case of medical implants, foreign materials are preferential sites for bacterial adhesion and microbial contamination, which can lead to the development of prosthetic infections. Commercially biomedical TiNi shape memory alloys are the most commonly used materials for permanent implants in contact with bone and dental, and the prevention of infections of TiNi biomedical shape memory alloys in clinical cases is therefore a crucial challenge for orthopaedic and dental surgeons. In the present study, copper has been chosen as the alloying element for design and development novel ternary biomedical Ti‒Ni‒Cu shape memory alloys with antibacterial properties. The effects of copper alloying element on the microstructure, mechanical properties, corrosion behaviors, cytocompatibility and antibacterial properties of biomedical Ti‒Ni‒Cu shape memory alloys have been systematically investigated. The results demonstrated that Ti‒Ni‒Cu alloys have good mechanical properties, and remain the excellent shape memory effects after adding copper alloying element. The corrosion behaviors of Ti‒Ni‒Cu alloys are better than the commercial biomedical Ti‒50.8Ni alloys. The Ti‒Ni‒Cu alloys exhibit excellent antibacterial properties while maintaining the good cytocompatibility, which would further guarantee the potential application of Ti‒Ni‒Cu alloys as future biomedical implants and devices without inducing bacterial infections. PMID:27897182

  16. Design and development of novel antibacterial Ti-Ni-Cu shape memory alloys for biomedical application.

    PubMed

    Li, H F; Qiu, K J; Zhou, F Y; Li, L; Zheng, Y F

    2016-11-29

    In the case of medical implants, foreign materials are preferential sites for bacterial adhesion and microbial contamination, which can lead to the development of prosthetic infections. Commercially biomedical TiNi shape memory alloys are the most commonly used materials for permanent implants in contact with bone and dental, and the prevention of infections of TiNi biomedical shape memory alloys in clinical cases is therefore a crucial challenge for orthopaedic and dental surgeons. In the present study, copper has been chosen as the alloying element for design and development novel ternary biomedical Ti‒Ni‒Cu shape memory alloys with antibacterial properties. The effects of copper alloying element on the microstructure, mechanical properties, corrosion behaviors, cytocompatibility and antibacterial properties of biomedical Ti‒Ni‒Cu shape memory alloys have been systematically investigated. The results demonstrated that Ti‒Ni‒Cu alloys have good mechanical properties, and remain the excellent shape memory effects after adding copper alloying element. The corrosion behaviors of Ti‒Ni‒Cu alloys are better than the commercial biomedical Ti‒50.8Ni alloys. The Ti‒Ni‒Cu alloys exhibit excellent antibacterial properties while maintaining the good cytocompatibility, which would further guarantee the potential application of Ti‒Ni‒Cu alloys as future biomedical implants and devices without inducing bacterial infections.

  17. Electrodeposition of PdCu alloy and its application in methanol electro-oxidation

    NASA Astrophysics Data System (ADS)

    Hsieh, Ming-Wei; Whang, Thou-Jen

    2013-04-01

    This study demonstrates a simple electrodeposition method to fabricate the palladium-copper alloy on an ITO coated glass (PdCu/ITO) and its application in methanol electro-oxidation. Our approaches involve the co-reduction of Pd and Cu using triethanolamine (TEA) as a complexing agent in the electroplating bath and a Pd redox replacement of Cu on the surface of the as-prepared PdCu alloy. The phase structures, alloy compositions and morphologies of catalysts are determined by X-ray diffraction, energy dispersive spectrometer and scanning electron microscopy, respectively. X-ray diffraction shows that the particle size of PdCu deposits shrink when the alloy is deposited in a TEA-contained solution. The electrocatalytic properties of PdCu alloys and Pd redox replacement modified PdCu alloys for methanol oxidation have been investigated by cyclic voltammetry. The PdCu alloy with atomic ratio of 20.5% Cu exhibits higher catalytic activity toward methanol oxidation compared with a pure Pd catalyst. PdCu alloys with smaller particle sizes associated with TEA agent and the surface confined Pd replacement are found to have enhanced catalytic performance in the electro-oxidation of methanol.

  18. Tribological performance of Cu-Ni alloy nanoparticles synthesized using a pulsed-wire evaporation method

    NASA Astrophysics Data System (ADS)

    Oh, Jeongseok; Rhee, Changkyu

    2008-08-01

    Cu-Ni alloy nanoparticles were produced using a pulsed-wire evaporation method in Ar gas. The synthesized Cu-Ni alloy nanoparticles had an average size of 150 nm, were spherical in shape and agglomerated. We investigated the tribological propeties of dispersion-stabilized Cu-Ni alloy nanoparticles when used as a solid lubricant in oil at ambient temperature. The sedimentation behavior of Cu-Ni alloy nanoparticles in oil was examined using Turbiscan LAb. The particles were clearly quantified using delta backscattering profiles and peak thickness kinetics as functions of time. The rubbing surfaces were characterized after a friction test using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). We found that dispersed Cu-Ni nanoparticles as a solid lubricant in oil had superior dispersion stability properties for over 48 h. Dispersed Cu nanoparticles in oil showed a low friction coefficient and good wear rate compared to oil only. Dispersed Cu-Ni alloy nanoparticles had superior friction reduction and antiwear properties compared to Cu nanoparticles, and these effects increased with the Ni content in the alloy. However, non-dispersed Cu-Ni alloy nanoparticles had poor antiwear properties. Dispersion-stabilized Cu-Ni alloy nanoparticles in oil enhanced the rolling effect of spherical nanoparticles between rubbing surfaces during friction processes.

  19. Metastable Demixing of Supercooled Cu-Co and Cu-Fe Alloys in an Oxide Flux

    NASA Technical Reports Server (NTRS)

    Li, D.; Robinson, M. B.; Rathz, T. J.; Williams, G.

    1998-01-01

    A systematic study on the liquid separation in supercooled Cu-Co and Cu-Fe alloys was performed using a melt fluxing which permits high supercooling to be achieved. Moreover, this method renders it possible to directly measure binodal temperatures and establish metastable liquid miscibility gap (LMG). All phase-separated samples at compositions ranging from 10 to 80 wt pct Co or to 83 wt pct Fe were found to exhibit droplet-shaped morphologies, in spite of various droplet distributions. Uniformly dispersed microstructures were obtained as the minority component was less than 20 vol.%; while beyond this percentage, serious coarsening was brought about. Calculations of the miscibility gap in the Cu-Co system and Stokes movement velocity of Co and Fe droplets in Cu matrix were made to analyze the experimental results.

  20. Metastable Demixing of Supercooled Cu-Co and Cu-Fe Alloys in an Oxide Flux

    NASA Technical Reports Server (NTRS)

    Li, D.; Robinson, M. B.; Rathz, T. J.; Williams, G.

    1998-01-01

    A systematic study on the liquid separation in supercooled Cu-Co and Cu-Fe alloys was performed using a melt fluxing which permits high supercooling to be achieved. Moreover, this method renders it possible to directly measure binodal temperatures and establish metastable liquid miscibility gap (LMG). All phase-separated samples at compositions ranging from 10 to 80 wt pct Co or to 83 wt pct Fe were found to exhibit droplet-shaped morphologies, in spite of various droplet distributions. Uniformly dispersed microstructures were obtained as the minority component was less than 20 vol.%; while beyond this percentage, serious coarsening was brought about. Calculations of the miscibility gap in the Cu-Co system and Stokes movement velocity of Co and Fe droplets in Cu matrix were made to analyze the experimental results.

  1. Microstructure and mechanical characteristics of gradient structured Cu and Cu alloys processed by surface mechanical attrition treatment

    NASA Astrophysics Data System (ADS)

    Hu, XZ; Cheng, LP; Chen, HL; Yin, Z.; Zhang, Z.; Shu, BP; Gong, YL; Zhu, XK

    2017-05-01

    Cu-Al-Zn alloys with different stacking fault energy (SFE) were processed by surface mechanical attrition treatment (SMAT) at cryogenic temperature (CT), mechanical properties of gradient structured Cu-Al-Zn alloys were investigated in this study. Al and Zn content in alloys, which result in the decrease of SFE, can contribute to the increase in strength. Cu-4.5wt%Al-14.3wt%Zn alloy with the lower SFE shows that the strength increased, the ductility did not decrease significantly with increasing processing time, and the strength can be improved by a thicker gradient structure (GS) layer. The better combination of strength and ductility was achieved in Cu-4.5wt%Al-14.3wt%Zn alloy with lower SFE.

  2. Anodic behaviour of a metallic U-Pu-Zr alloy during electrorefining process

    NASA Astrophysics Data System (ADS)

    Murakami, T.; Sakamura, Y.; Akiyama, N.; Kitawaki, S.; Nakayoshi, A.; Fukushima, M.

    2011-07-01

    Electrorefining tests of the non-irradiated U-Pu-Zr alloy were performed in LiCl-KCl-UCl 3-PuCl 3-ZrCl 4 melts at 773 K, aiming at reduced Zr dissolution. The tests were carried out both using potentiostatic electrolysis at -1.0 V (vs. Ag +/Ag), i.e. at a more negative potential than the Zr dissolution potential, and galvanostatic electrolysis with a limited amount of Zr dissolution. The ICP-AES analysis of the anode residues confirmed that a high dissolution yield of actinides (U: >99.6%, Pu: 99.9%) was successfully demonstrated for both electrolyses.

  3. Enriched alloy layer on an Al-Cu alloy studied by cyclic voltammetry

    NASA Astrophysics Data System (ADS)

    García Vergara, S. J.; Blanco Pinzon, C. E.; Skeldon, P.

    2017-01-01

    The behaviour of enriched Al-0.7at.%Cu alloy is investigated using cyclic voltammetry. Enriched alloy layers at the interface between the alloy/oxide film were developed by alkaline etching at 5mAcm-2 in 0.1M sodium hydroxide solution at 298K, with the time of etching determining the extent of enrichment. Cyclic voltammograms were recorded at a scan rate of 10mV s-1 in naturally aerated 0.1M ammonium pentaborate solution at 298K. The current overshoot of the enriched alloys was different from that for non-enriched alloy. The latter material revealed the usual single peaks, which are very similar. In contrast, the overshoot comprised two or more components for the enriched alloys. The behaviour is suggested to be associated with the atomic bonding of aluminium in copper-rich and aluminium-rich regions of the enriched alloy layer, with influence on the activation potentials for oxidation of aluminium.

  4. Irradiation-induced patterning in dilute Cu-Fe alloys

    NASA Astrophysics Data System (ADS)

    Stumphy, B.; Chee, S. W.; Vo, N. Q.; Averback, R. S.; Bellon, P.; Ghafari, M.

    2014-10-01

    Compositional patterning in dilute Cu1-xFex (x ≈ 12%) induced by 1.8 MeV Kr+ irradiation was studied as a function of temperature using atom probe tomography. Irradiation near room temperature led to homogenization of the sample, whereas irradiation at 300 °C and above led to precipitation and macroscopic coarsening. Between these two temperatures the irradiated alloys formed steady state patterns of composition where precipitates grew to a fixed size. The size in this regime increased somewhat with temperature. It was also observed that the steady state concentrations of Fe in Cu matrix and Cu in the Fe precipitates both greatly exceeded their equilibrium solubilities, with the degree of supersaturation in each phase decreasing with increasing temperature. In the macroscopic coarsening regime, the Fe-rich precipitates showed indications of a “cherry-pit” structure, with Cu precipitates forming within the Fe precipitates. In the patterning regime, interfaces between Fe-rich precipitates and the Cu-rich matrix were irregular and diffuse.

  5. Indentation creep of nanocrystalline Cu-TiC alloys prepared by mechanical alloying

    SciTech Connect

    Shen, B.L.; Itoi, T.; Yamasaki, T.; Ogino, Y.

    2000-04-01

    In recent years, nanocrystalline materials have attracted much attention in materials research because they behave differently from conventional materials. For example, the nanocrystalline materials exhibit enhanced mechanical properties, such as high strength and hardness. The present study was performed to investigate the indentation creep mechanism of nanocrystalline Cu-TiC alloys which were prepared by HIP (Hot Isostatic Press) processing of MA (Mechanical Alloying) powders and hot rolling afterwards. As these materials have high densities and high structural stability, the authors could investigate creep behavior at wide temperature ranges below 0.5Tm (Tm is the melting temperature of copper).

  6. Grindability of dental cast Ti-Ag and Ti-Cu alloys.

    PubMed

    Kikuchi, Masafumi; Takahashi, Masatoshi; Okabe, Toru; Okuno, Osamu

    2003-06-01

    Experimental Ti-Ag alloys (5, 10, and 20 mass% Ag) and Ti-Cu alloys (2, 5, and 10 mass% Cu) were cast into magnesia molds using a dental casting machine, and their grindability was investigated. At the lowest grinding speed (500 m min(-1)), there were no statistical differences among the grindability values of the titanium and titanium alloys. The grindability of the alloys increased as the grinding speed increased. At the highest grinding speed (1500 m x min(-1)), the grindability of the 20% Ag, 5% Cu, and 10% Cu alloys was significantly higher than that of titanium. It was found that alloying with silver or copper improved the grindability of titanium, particularly at a high speed. It appeared that the decrease in elongation caused by the precipitation of small amounts of intermetallic compounds primarily contributed to the favorable grindability of the experimental alloys.

  7. Optimization of conductivity and strength in Cu-Ni-Si alloys by suppressing discontinuous precipitation

    NASA Astrophysics Data System (ADS)

    Han, Seung Zeon; Lee, Jehyun; Lim, Sung Hwan; Ahn, Jee Hyuk; Kim, Kwangho; Kim, Sangshik

    2016-11-01

    Cu-Ni-Si alloys with and without Ti were solution treated at 980 °C for 1 h and cooled by air cooling and water quenching, after which the specimens were aged at 500 °C. The two alloys showed different aging characteristics with different cooling rates during the aging process. The conductivity of all alloys increased during aging; for alloys that were water quenched, hardness increased at the early stage of aging and then drastically decreased. The air-cooled Cu-Ni-Si alloy without Ti also experienced an increase in hardness, which then decreased during aging, but the air-cooled Cu-Ni-Si alloy with Ti did not show a drastic decrease in hardness during prolonged aging. A combination of yield strength and conductivity of 820 MPa and 42% IACS, respectively, was achieved in the air-cooled Cu-Ni-Si-Ti alloy after solution treatment.

  8. Self-sealing anodization approach to enhance micro-Vickers hardness and corrosion protection of a die cast Al alloy

    NASA Astrophysics Data System (ADS)

    Lee, Chulho; Oh, Kiseok; Lee, Dongeun; Kim, Yelim; Yoon, Hyungsop; Park, Dong-Wha; Gab Kim, Moon; Lee, Kiyoung; Choi, Jinsub

    2017-04-01

    Die cast, high-Si content ADC12 Al alloy samples were successfully anodized without surface cracks. This was accomplished with a 0.3 M sulfuric acid electrolyte with a high concentration of sodium aluminate. During anodization, the AlO2- anions were attracted to the positively-charged Al substrate and deposited in the cracks formed by un-oxidized Si islands within the ADC12. Anodic films prepared in electrolytes with a high concentration of AlO2- drastically enhanced surface morphology, thickness uniformity, Vickers hardness, and corrosion behavior in comparison with anodic film prepared without AlO2- concentration. The simultaneous sealing mechanism by AlO2- anions during anodization is reported in detail.

  9. Alloying effects in near-eutectic Sn-Ag-Cu solder alloys for improved microstructural stability

    NASA Astrophysics Data System (ADS)

    Anderson, I. E.; Foley, J. C.; Cook, B. A.; Harringa, J.; Terpstra, R. L.; Unal, O.

    2001-09-01

    This study included a comparison of the baseline Sn-3.5Ag eutectic to one near-eutectic ternary alloy, Sn-3.6 Ag-1.0Cu and two quaternary alloys, Sn-3.6Ag-1.0Cu-0.15Co and Sn-3.6Ag-1.0 Cu-0.45 Co, to increase understanding of the beneficial effects of Co on Sn-Ag-Cu solder joints cooled at 1 3 C/sec, typical of reflow practice. The results indicated that joint microstructure refinement is due to Co-enhanced nucleation of the Cu6Sn5 phase in the solder matrix, as suggested by Auger elemental mapping and calorimetric measurements. The Co also reduced intermetallic interface faceting and improved the ability of the solder joint samples to maintain their shear strength after aging for 72 hr at 150 C. The baseline Sn-3.5Ag joints exhibited significantly reduced strength and coarser microstructures.

  10. Theoretical means for searching bimetallic alloys as anode electrocatalysts for direct liquid-feed fuel cells

    NASA Astrophysics Data System (ADS)

    Demirci, Umit B.

    The present paper reviews the best anode electrocatalysts, mainly the alloys, which have been tested in direct liquid-feed fuel cells fed with methanol, ethanol or formic acid. It attempts to interpret the alloys catalytic behaviours by using the Nørskov and co-workers' theoretical work [A. Ruban, B. Hammer, P. Stoltze, H.L. Skriver, J.K. Nørskov, J. Mol. Catal. A 115 (1997) 421; B. Hammer, J.K. Nørskov, Adv. Catal. 45 (2000) 71; J. Greeley, J.K. Nørskov, M. Maurikakis, Annu. Rev. Phys. Chem. 53 (2002) 319], who proposed surface theories and databases about the metals d-band centre shift and the segregation. It also attempts to suggest new alloys combinations. For example, for the methanol oxidation, the best catalyst is Pt-Ru and the following features make this catalyst stand out: the d-band centre of Pt shifts down what supposes weaker molecules adsorption and Pt strongly segregates. From this analysis, it is suggested that the Pd-Ni alloy may be a potentially good catalyst. Similar interpretations are given for the three fuel cell systems regarded in the present paper.

  11. Cu2+1O coated polycrystalline Si nanoparticles as anode for lithium-ion battery

    NASA Astrophysics Data System (ADS)

    Zhang, Junying; Zhang, Chunqian; Wu, Shouming; Liu, Zhi; Zheng, Jun; Zuo, Yuhua; Xue, Chunlai; Li, Chuanbo; Cheng, Buwen

    2016-04-01

    Cu2+1O coated Si nanoparticles were prepared by simple hydrolysis and were investigated as an anode material for lithium-ion battery. The coating of Cu2+1O on the surface of Si particles remarkably improves the cycle performance of the battery than that made by the pristine Si. The battery exhibits an initial reversible capacity of 3063 mAh/g and an initial coulombic efficiency (CE) of 82.9 %. With a current density of 300 mA/g, its reversible capacity can remains 1060 mAh/g after 350 cycles, corresponding to a CE ≥ 99.8 %. It is believed that the Cu2+1O coating enhances the electrical conductivity, and the elasticity of Cu2+1O further helps buffer the volume changes during lithiation/delithiation processes. Experiment results indicate that the electrode maintained a highly integrated structure after 100 cycles and it is in favour of the formation of stable solid electrolyte interface (SEI) on the Si surface to keep the extremely high CE during long charge and discharge cycles.

  12. Cu2+1O coated polycrystalline Si nanoparticles as anode for lithium-ion battery.

    PubMed

    Zhang, Junying; Zhang, Chunqian; Wu, Shouming; Liu, Zhi; Zheng, Jun; Zuo, Yuhua; Xue, Chunlai; Li, Chuanbo; Cheng, Buwen

    2016-12-01

    Cu2+1O coated Si nanoparticles were prepared by simple hydrolysis and were investigated as an anode material for lithium-ion battery. The coating of Cu2+1O on the surface of Si particles remarkably improves the cycle performance of the battery than that made by the pristine Si. The battery exhibits an initial reversible capacity of 3063 mAh/g and an initial coulombic efficiency (CE) of 82.9 %. With a current density of 300 mA/g, its reversible capacity can remains 1060 mAh/g after 350 cycles, corresponding to a CE ≥ 99.8 %. It is believed that the Cu2+1O coating enhances the electrical conductivity, and the elasticity of Cu2+1O further helps buffer the volume changes during lithiation/delithiation processes. Experiment results indicate that the electrode maintained a highly integrated structure after 100 cycles and it is in favour of the formation of stable solid electrolyte interface (SEI) on the Si surface to keep the extremely high CE during long charge and discharge cycles.

  13. Solid-state ionics method fabricated centimeter level CuAu alloy nanowires: Application in SERS.

    PubMed

    Xu, Dapeng; Dong, Jing; Yang, Wei; Zhang, Song; Peng, Yuli; Chen, Jian

    2017-04-08

    CuAu alloy nanowires were prepared by a solid-state ionics method under a direct current electric field (DCEF) using fast ionic conductor Rb4Cu16Cl13I7 films. The surface morphology, chemical composition and crystal structures of the CuAu alloy nanowires were characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD), respectively. Raman enhancement performance of the CuAu alloy nanowires substrates was detected by Rhodamine 6G (R6G) aqueous solutions as probe molecules. Long-range disorder and short-range order CuAu alloy nanowires with the length of 1 cm were prepared by a solid-state ionics method. The nanowires were bamboo-shaped and the diameters of nanowires ranged from 40 to 100nm. The molar ratio of Cu to Au is 16:1. The crystal structure of the CuAu alloy nanowires is crystallized. A part of Cu and Au formed Au3Cu alloy structure. The limiting concentrations of R6G for the prepared CuAu alloy nanowires SERS substrates is 10(-15)mol/L.

  14. Metallic glass alloys of Zr, Ti, Cu and Ni

    DOEpatents

    Lin, Xianghong; Peker, Atakan; Johnson, William L.

    1997-01-01

    At least quaternary alloys form metallic glass upon cooling below the glass transition temperature at a rate less than 10.sup.3 K/s. Such alloys comprise titanium from 19 to 41 atomic percent, an early transition metal (ETM) from 4 to 21 atomic percent and copper plus a late transition metal (LTM) from 49 to 64 atomic percent. The ETM comprises zirconium and/or hafnium. The LTM comprises cobalt and/or nickel. The composition is further constrained such that the product of the copper plus LTM times the atomic proportion of LTM relative to the copper is from 2 to 14. The atomic percentage of ETM is less than 10 when the atomic percentage of titanium is as high as 41, and may be as large as 21 when the atomic percentage of titanium is as low as 24. Furthermore, when the total of copper and LTM are low, the amount of LTM present must be further limited. Another group of glass forming alloys has the formula (ETM.sub.1-x Ti.sub.x).sub.a Cu.sub.b (Ni.sub.1-y Co.sub.y).sub.c wherein x is from 0.1 to 0.3, y.cndot.c is from 0 to 18, a is from 47 to 67, b is from 8 to 42, and c is from 4 to 37. This definition of the alloys has additional constraints on the range of copper content, b.

  15. Local structure of disordered Au-Cu and Au-Ag alloys

    NASA Astrophysics Data System (ADS)

    Frenkel, A. I.; Machavariani, V. Sh.; Rubshtein, A.; Rosenberg, Yu.; Voronel, A.; Stern, E. A.

    2000-10-01

    X-ray-absorption fine structure (XAFS) and x-ray-diffraction (XRD) measurements of disordered alloys AuxCu1-x and Au0.5Ag0.5 prepared by melt spinning were performed. In the Au0.5Ag0.5 alloy, no significant local deviations of the atoms from the average fcc lattice were detected while in AuxCu1-x alloys, significant deviations of atoms from the average fcc lattice were found. Mean-square vibrations of the Cu-Cu distances revealed by the XAFS in AuxCu1-x alloys indicate the weakening of contact between Cu atoms in the dilute limit. Our computer simulation for AuxCu1-x clusters of 105 atoms reproduces the main features of both the XAFS and XRD data.

  16. Potential bioactivity of coatings formed on AZ91D magnesium alloy by plasma electrolytic anodizing.

    PubMed

    Vu, Thanh-Nam; Veys-Renaux, Delphine; Rocca, Emmanuel

    2012-10-01

    Magnesium is a potential candidate as biodegradable orthopedic implant thanks to its remarkable mechanical properties closed to those of natural bone. But its low corrosion resistance in the body fluid is a limiting factor. By using electrolytic plasma (or microarc) anodizing process, 10-20 μm protective coatings were formed on AZ91D magnesium alloys at a constant current density of 20 mA cm(-2). The effect of a small addition of CaO (1-3 g L(-1)) to a classical electrolytic bath (made of KOH 3 mol L(-1), KF 0.5 mol L(-1), and K(2)HPO(4) 1 mol L(-1)) was studied. The anodic films, investigated by X-ray diffraction and scanning electron microscope-energy dispersive spectroscopy, show a porous structure containing crystallized Mg(OH)(2), MgO, MgAl(2)O(4), as well as Ca and P elements. The 1 g L(-1) CaO-containing electrolyte leads to morphology and composition permitting optimum corrosion behavior evaluated by stationary electrochemical measurements and impedance spectroscopy. This improvement is associated with both the appearing of a "sealing" layer and the precipitation of an outermost Ca/P-containing layer (hydroxyapatite like) in simulated body fluid. The control of the corrosion behavior of coated magnesium alloys is therefore required to enhance their potential bioactivity.

  17. Conical surface textures formed by ion bombarding 2% Be Cu alloy

    SciTech Connect

    Panitz, J.K.G.

    1990-01-01

    A homogeneous, micrometer-sized conical surface texture forms on 2% Be-Cu alloy which is bombarded with an argon beam produced by a Kaufman ion source. The dimensions of the features that form strongly depend on: (1) argon energy (from 250 to 1500 eV), (2) fluence (10{sup 19} to 10{sup 20} ions/cm{sup 2}), and (3) flux (0.1 to 1 mA/cm{sup 2}). The texture morphology depends less strongly on the background ambient (Mo vs graphite), earlier alloy heat treatments and the temperature during bombardment (100{degree}C and 450{degree}C). As the texture matures with increasing fluence, the number of large features increases at the expense of the number of small features. The observed relationship between texture formation and ion flux suggests that the evolution of these features is not adequately described by theories predicting that the mature conical sidewall angle is related to the angle of the maximum sputtering yield. These textured surfaces can be coated with other metals for a variety of possible applications including: (1) pulsed power Li+ beam anodes, (2) cold cathode field emission devices, (3) optical absorbers and (4) catalysis supports. 18 refs., 5 figs.

  18. Asymmetric reversal in aged high concentration CuMn alloy.

    PubMed

    Barnsley, L C; MacA Gray, E; Webb, C J

    2013-02-27

    The magnetic hysteresis loops of an aged Cu(81.2)Mn(18.8) alloy sample exhibit significant asymmetric reversal at low temperatures, with high sensitivity to the cooling field. Much of the observed behaviour was explained by considering an ensemble of coherent, ferromagnetically aligned clusters interacting with a randomized spin glass component. A modified Stoner-Wohlfarth model was successfully applied to the data using Monte Carlo simulations, in order to gain insight into the dependence of the cluster shape anisotropy and exchange anisotropy on the cooling field. This model suggested that ferromagnetic clusters grow as the cooling field increases.

  19. Thermodynamic properties of metastable Ag-Cu alloys

    NASA Astrophysics Data System (ADS)

    Najafabadi, R.; Srolovitz, D. J.; Ma, E.; Atzmon, M.

    1993-09-01

    The enthalpies of formation of metastable fcc Ag-Cu solid solutions, produced by ball milling of elemental powders, were determined by differential scanning calorimetry. Experimental thermodynamic data for these metastable alloys and for the equilibrium phases are compared with both calculation of phase diagrams (CALPHAD) and atomistic simulation predictions. The atomistic simulations were performed using the free-energy minimization method (FEMM). The FEMM determination of the equilibrium Ag-Cu phase diagram and the enthalpy of formation and lattice parameters of the metastable solid solutions are in good agreement with the experimental measurements. CALPHAD calculations made in the same metastable regime, however, significantly overestimate the enthalpy of formation. Thus, the FEMM is a viable alternative approach for the calculation of thermodynamic properties of equilibrium and metastable phases, provided reliable interatomic potentials are available. The FEMM is also capable of determining such properties as the lattice parameter which are not available from CALPHAD calculations.

  20. Surface hardening by anodizing and heat treatments of Ti6Al4V alloys for articular prostheses.

    PubMed

    Gil, F J; Ginebra, M P; Planell, J A

    2002-01-01

    This paper presents a study of the surface hardening of Ti6Al4V alloy produced by electrochemical anodizing and by different heat treatments, in addition to studying the annealing of the martensitic structure. Results of the combination of both methods produce hardening over 1300 HV and an important improvement on the tribological behaviour. These values could improve wear resistance of this alloy in applications like articular prostheses.

  1. The effect of zinc additions on the environmental stability of Alloy 8090 (Al-Li-Cu-Mg-Zr)

    NASA Technical Reports Server (NTRS)

    Kilmer, Raymond J.; Stoner, G. E.

    1991-01-01

    Stress corrosion cracking (SCC) remains a problem in both Al-Li and conventional Al heat treatable alloys. It has recently been found that relatively small additions (less than or approximately 1 wt-percent) of Zn can dramatically improve the SCC performance of alloy 8090 (Al-Li-Cu-Mg-Zr). Constant load time to failure experiments using cylindrical tensile samples loaded between 30 and 85 percent of TYS indicate improvements of orders of magnitude over the baseline 8090 for the Zn-containing alloys under certain aging conditions. However, the toughnesses of the alloys were noticeably degraded due to the formation of second phase particles which primarily reside on grain and subgrain boundaries. EDS revealed that these intermetallic particles were Cu and Zn rich. The particles were present in the T3 condition and were not found to be the result of quench rate, though their size and distribution were. At 5 hours at 160 C, the alloys displayed the greatest susceptibility to SCC but by 20 hours at 160 C the alloys demonstrated markedly improved TTF lifetimes. Aging past this time did not provide separable TTF results, however, the alloy toughnesses continued to worsen. Initial examination of the alloys microstructures at 5 and 20 hours indicated some changes most notably the S' and delta' distributions. A possible model by which this may occur will be explored. Polarization experiments indicated a change in the trend of E(sub BR) and passive current density at peak aging as compared to the baseline 8090. Initial pitting experiments indicated that the primary pitting mechanism in chloride environments is one occurring at constituent (Al-Fe-Cu) particles and that the Cu and Zn rich boundary precipitates posses a breakaway potential similar to that of the matrix acting neither anodic or cathodic in the first set of aerated 3.5 w/o NaCl experiments. Future work will focus on the identification of the second phase particles, evaluation of K(sub 1SCC) and plateau da/dt via

  2. Hydrogen isotope trapping in Al-Cu binary alloys

    DOE PAGES

    Chao, Paul; Karnesky, Richard A.

    2016-01-01

    In this study, the trapping mechanisms for hydrogen isotopes in Al–X Cu (0.0 at. % < X < 3.5 at. %) alloys were investigated using thermal desorption spectroscopy (TDS), electrical conductivity, and differential scanning calorimetry. Constant heating rate TDS was used to determine microstructural trap energies and occupancies. In addition to the trapping states in pure Al reported in the literature (interstitial lattice sites, dislocations, and vacancies), a trap site due to Al–Cu intermetallic precipitates is observed. The binding energy of this precipitate trap is (18 ± 3) kJ•mol–1 (0.19 ± 0.03 eV). Typical occupancy of this trap is high;more » for Al–2.6 at. % Cu (a Cu composition comparable to that in AA2219) charged at 200 °C with 130 MPa D2 for 68 days, there is ca. there is 3.15×10–7 mol D bound to the precipitate trap per mol of Al, accounting for a third of the D in the charged sample.« less

  3. Hydrogen isotope trapping in Al-Cu binary alloys

    SciTech Connect

    Chao, Paul; Karnesky, Richard A.

    2016-01-01

    In this study, the trapping mechanisms for hydrogen isotopes in Al–X Cu (0.0 at. % < X < 3.5 at. %) alloys were investigated using thermal desorption spectroscopy (TDS), electrical conductivity, and differential scanning calorimetry. Constant heating rate TDS was used to determine microstructural trap energies and occupancies. In addition to the trapping states in pure Al reported in the literature (interstitial lattice sites, dislocations, and vacancies), a trap site due to Al–Cu intermetallic precipitates is observed. The binding energy of this precipitate trap is (18 ± 3) kJ•mol–1 (0.19 ± 0.03 eV). Typical occupancy of this trap is high; for Al–2.6 at. % Cu (a Cu composition comparable to that in AA2219) charged at 200 °C with 130 MPa D2 for 68 days, there is ca. there is 3.15×10–7 mol D bound to the precipitate trap per mol of Al, accounting for a third of the D in the charged sample.

  4. The shape memory capability and life of Cu-Al-Be-X alloys

    SciTech Connect

    Dong, Y.Y.; Dar, K.Z. ); Wang, T.M. ); Zin, S.J. )

    1994-09-01

    The shape memory capacity and the shape memory life of three alloys of the Cu-11.6Al-0.4Be-X type have been investigated using the strain angle restoration method and compared with the alloy Cu-25Zn-4Al. The alloys were subjected to various normalizing and normalizing plus aging treatments, and all were found to possess excellent shape memory properties. The alloy Cu-11.6Al-0.4Be-0.2Cr demonstrated the best shape memory capacity and life.

  5. Improved electrochemical performances of CuO nanotube array prepared via electrodeposition as anode for lithium ion battery

    SciTech Connect

    Xiao, Anguo Zhou, Shibiao; Zuo, Chenggang; Zhuan, Yongbing; Ding, Xiang

    2015-10-15

    Graphical abstract: CuO nanotube array electrodes prepared by electrodeposition method exhibit an excellent lithium ion storage ability as anode of Li-ion battery. - Highlights: • CuO nanotube arrays are synthesized by an electrodeposition method. • CuO nanotube shows a high-rate performance. • CuO nanotube shows an excellent cycling performance. - Abstract: We report a facile strategy to prepared CuO nanotube arrays directly grown on Cu plate through the electrodeposition method. The as-prepared CuO nanotubes show a quasi-cylinder nanostructure with internal diameters of ca. ∼100 nm, external diameters of ca. ∼120 nm, and average length of ∼3 μm. As an anode for lithium ion batteries, the electrochemical properties of the CuO nanotube arrays are investigated by cyclic voltammetry (CV) and galvanostatic charge/discharge tests. Due to the unique nanotube nanostructure, the as-prepared CuO electrodes exhibit good rate performance (550 mAh g{sup −1} at 0.1 C and 464 mAh g{sup −1} at 1 C) and cycling performance (581 mAh g{sup −1} at 0.1 C and 538 mAh g{sup −1} at 0.5 C)

  6. Thermodynamic properties and phase transitions of ternary Co-Cu-Si alloys with equiatomic Co/Cu ratio

    NASA Astrophysics Data System (ADS)

    Zhai, Wei; Hu, Liang; Zhou, Kai; Wei, Bingbo

    2016-04-01

    Different amounts of Si element were introduced into binary Co50Cu50 alloy to investigate the thermodynamic properties and phase transitions of ternary Co50-x/2Cu50-x/2Si x (x  =  10, 20, 30, 40 and 50 at%) alloys. Their liquidus and solidus temperatures versus Si content were determined by the differential scanning calorimetry (DSC) method. It was found that the addition of Si element depressed both the liquidus and solidus temperatures as compared with binary Co50Cu50 alloy. In particular, the additions of 10 and 20 at% Si remarkably reduced the critical undercooling for liquid demixing to only 3 and 1 K, whereas no liquid phase separation took place in other Co50-x/2Cu50-x/2Si x alloys. The relationship between the enthalpy of fusion and alloy composition was also established by a polynomial function on the basis of the measured data. The solidification microstructures of the DSC samples were investigated corresponding to the calorimetric signals, based on which the solidification pathway for each Co50-x/2Cu50-x/2Si x alloy was elucidated. The Si element displays stronger affinity with the Co element than the Cu element. As Si content rises, the pseudobinary eutectic (Co  +  Co2Si), (Co2Si  +  CoSi), (CoSi  +  CoSi2) and (Cu3Si  +  Si) structures were successively formed, and there were no ternary intermetallic compounds in these alloys. The thermal diffusivity of solid ternary Co50-x/2Cu50-x/2Si x alloys was determined by a laser flash method in a wide temperature range from 300 to 1180 K, which showed a decreasing tendency with the increase of Si content.

  7. Magnetic properties of Fe-Cu alloys prepared by pulsed electrodeposition

    NASA Astrophysics Data System (ADS)

    Noce, R. D.; Gomes, O. D. M.; de Magalhães, S. D.; Wolf, W.; Guimarães, R. B.; de Castro, A. C.; Pires, M. J. M.; Macedo, W. A. A.; Givord, D.; Barthem, V. M. T. S.

    2009-11-01

    FexCu100-x metastable alloys were prepared by pulsed electrodeposition for 5alloys crystallize in the bcc structure of α-Fe and the Fe-poor ones in the fcc structure of Cu. The magnetic properties of the ferromagnetic Fe-rich alloys (x>50) are reminiscent of those observed in Fe-Cu alloys prepared by other methods. The Curie temperature decreases regularly with decreasing x. In the Fe-poor alloys (x≤30), the observed properties indicate that Fe-rich clusters form within a Cu-rich matrix. In the x=10 alloy, the Fe clusters are found to be superparamagnetic at room temperature, but a superferromagnetic order develops below a critical temperature of about 120 K. It is suggested that the intercluster coupling is mediated by Ruderman-Kittel-Kasuya-Yosida interactions which are predominantly positive due to the very short intercluster distances.

  8. A Novel Multiphase Sn-Sb-Cu Alloy Electrodeposited on 3D Interconnected Microporous Cu Current Collector as Negative Electrode for Lithium Ion Battery

    NASA Astrophysics Data System (ADS)

    Sengupta, Srijan; Patra, Arghya; Deo, Yash; Das, Karabi; Majumder, Subhasish Basu; Das, Siddhartha

    2017-03-01

    We report a novel, active-active-inactive-type tin-antimony-copper alloy with dendritic morphology electrodeposited on 3D interconnected microporous copper foam ( 70 μm pore diameter) as a promising high specific capacity anode for Li-ion batteries. The multiphase composition, SnSb and Cu6Sn5 "reactant" intermetallics embedded in Sn "matrix," alleviates the volumetric stress generated during cycling by lithiating at different step potentials (0.84, 0.66, 0.57, 0.42, 0.39, and 0.38 to 0.33 V vs Li/Li+). Copper foam successfully acts as a stress buffer preventing both pulverization and delamination. This combination of properties in tin-antimony-copper anode on copper foam results in 2nd cycle discharge capacity of 723 mAh/g, superior rate capability, and stable cycle retention with a capacity loss of 16 pct in the last 70 cycles at a rate of 400 mA/g (0.5 C) while preserving its structural integrity in comparison to tin-antimony-copper anode deposited on a planar copper foil as a current collector.

  9. Effect of Cu Addition to Zn-12Al Alloy on Thermal Properties and Wettability on Cu and Al Substrates

    NASA Astrophysics Data System (ADS)

    Gancarz, Tomasz; Pstruś, Janusz; Mosińska, Sylwia; Pawlak, Sylwia

    2016-01-01

    The thermal properties, electrical resistivity, thermal linear expansion and tensile strength of a new high-temperature lead-free solder based on a eutectic Zn-Al alloy with 0.5, 1.0, or 1.5 at. pct Cu added were studied. Wettability studies on Cu substrate were performed with flux at 773 K (500 °C) for 60, 180, 240, 900, 1800, and 3600 seconds, and for 480 seconds at 733 K, 753 K, 773 K, 793 K, and 823 K (460 °C, 480 °C, 500 °C, 520 °C, and 550 °C, respectively). The experiment was designed to demonstrate the effect of the addition of Cu on the kinetics of the formation and growth of the CuZn, Cu5Zn8, CuZn4, and Al4Cu9 phases, which were identified by X-ray diffraction analysis. Wetting tests were also performed on the Al substrate, for 15 and 30 seconds at 773 K and 793 K (500 °C and 520 °C, respectively). Very low contact angles on Al pads were obtained. The electrical resistivity of Zn-Al-Cu alloys was slightly higher than that of the ZnAl eutectic alloy. The present results are discussed with respect to the available literature on Zn-Al and Zn-Al-Cu alloys.

  10. Evolution of insoluble eutectic Si particles in anodic oxidation films during adipic-sulfuric acid anodizing processes of ZL114A aluminum alloys

    NASA Astrophysics Data System (ADS)

    Hua, Lei; Liu, Jian-hua; Li, Song-mei; Yu, Mei; Wang, Lei; Cui, Yong-xin

    2015-03-01

    The effects of insoluble eutectic Si particles on the growth of anodic oxide films on ZL114A aluminum alloy substrates were investigated by optical microscopy (OM) and scanning electron microscopy (SEM). The anodic oxidation was performed at 25°C and a constant voltage of 15 V in a solution containing 50 g/L sulfuric acid and 10 g/L adipic acid. The thickness of the formed anodic oxidation film was approximately 7.13 μm. The interpore distance and the diameters of the major pores in the porous layer of the film were within the approximate ranges of 10-20 nm and 5-10 nm, respectively. Insoluble eutectic Si particles strongly influenced the morphology of the anodic oxidation films. The anodic oxidation films exhibited minimal defects and a uniform thickness on the ZL114A substrates; in contrast, when the front of the oxide oxidation films encountered eutectic Si particles, defects such as pits and non-uniform thickness were observed, and pits were observed in the films.

  11. Adhesive strength of medical polymer on anodic oxide nanostructures fabricated on biomedical β-type titanium alloy.

    PubMed

    Hieda, Junko; Niinomi, Mitsuo; Nakai, Masaaki; Cho, Ken; Mohri, Tomoyoshi; Hanawa, Takao

    2014-03-01

    Anodic oxide nanostructures (nanopores and nanotubes) were fabricated on a biomedical β-type titanium alloy, Ti-29Nb-13Ta-4.6Zr alloy (TNTZ), by anodization in order to improve the adhesive strength of a medical polymer, segmented polyurethane (SPU), to TNTZ. TNTZ was anodized in 1.0M H3PO4 solution with 0.5 mass% NaF using a direct-current power supply at a voltage of 20V. A nanoporous structure is formed on TNTZ in the first stage of anodization, and the formation of a nanotube structure occurs subsequently beneath the nanoporous structure. The nanostructures formed on TNTZ by anodization for less than 3,600s exhibit higher adhesive strengths than those formed at longer anodization times. The adhesive strength of the SPU coating on the nanoporous structure formed on top of TNTZ by anodization for 1,200s improves by 144% compared to that of the SPU coating on as-polished TNTZ with a mirror surface. The adhesive strength of the SPU coating on the nanotube structure formed on TNTZ by anodization for 3,600s increases by 50%. These improvements in the adhesive strength of SPU are the result of an anchor effect introduced by the nanostructures formed by anodization. Fracture occurs at the interface of the nanoporous structure and the SPU coating layer. In contrast, in the case that SPU coating has been performed on the nanotube structure, fracture occurs inside the nanotubes. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. Effect of microstructure on the nanotube growth by anodic oxidation on Ti-10Nb alloy

    NASA Astrophysics Data System (ADS)

    Luz, A. R.; Lepienski, C. M.; Henke, S. L.; Grandini, C. R.; Kuromoto, N. K.

    2017-07-01

    Several papers have reported the grown self-organized nanotube arrays on pure Ti and its alloys to improve the surface of these materials for biomedical applications. The growth of nanotubes can be influenced by microstructure of material; however, few papers concerning this topic have been published. The aim of this work was to investigate the morphology, the cross-section view and the oxides in nanotube arrays in relationship to the microstructure of the Ti-10Nb alloy. The growth of nanotubes on the Ti-10Nb alloy obtained by anodic oxidation (AO). The Ti-10Nb alloy is composed by alfa and beta phases that were investigated by metallographic analysis, patterns of x-ray diffraction and EDS analysis. SEM images and EDS analysis revealed the morphology was composed by self-organized nanotube arrays on the alpha phase and walls with transversal holes on beta phase. X-ray patterns show crystalline oxides formation. Raman spectrum confirms the presence of anatase and Nb2O5 oxides. A significant contribution of the Nb2O5 was observed by bi-dimensional (x, y) Raman mapping, which also showed that the all oxide film was homogeneous oxide distributed on Ti-10Nb alloy. The nanostructured films have higher thickness in the beta than in the alpha phase, and have a small different in structure and oxide composition; as observed by SEM and Raman mapping. The results indicate that the microstructure of the Ti-10Nb affects the nanotubes morphology and the cross-section view, but the oxide formation was similar for all regions analyzed.

  13. The coupled effect of grain size and solute on work hardening of Cu-Ni alloys

    NASA Astrophysics Data System (ADS)

    Shadkam, A.; Sinclair, C. W.

    2015-12-01

    A modified grain size-dependent model developed to capture the combined effects of solute and grain size on the work hardening behaviour of fine-grained Cu-Ni alloys is provided. This work builds on a recent model that attributes the grain size-dependent work hardening of fine-grained Cu to backstresses. In the case of Cu-Ni alloys, unlike commercially pure Cu, a grain size-dependent separation between the Kocks-Mecking curves develops, this being explained here based on an extra contribution from geometrically necessary dislocations in the solid solution alloy. This is corroborated by strain-rate sensitivity experiments.

  14. Effects of Li content on precipitation in Al-Cu-(Li)-Mg-Ag-Zr alloys

    SciTech Connect

    Huang, B.P.; Zheng, Z.Q.

    1998-01-06

    Although much attention has been paid to Al-Cu-Li-Mg-Ag-Zr alloys, there are sparse reports about the influence of Li on precipitation in these alloys. The aim of the present study is to determine the effects of Li on modifying precipitation in a baseline aluminum alloy 2195 and the accompanying variants with 0--1.6 wt.% Li.

  15. Resistance to Fracture, Fatigue and Stress-Corrosion of Al-Cu-Li-Zr Alloys

    DTIC Science & Technology

    2007-11-02

    Zr alloyý, 4 Heat treatment and hot rolling schedules fur 66 the Al-Cu-Li-Zr alloys 5 Laue transmission analysis of Al-Cu-Li-Zr alloys 67 6 X-ray...ratio, there appears to be an increase in amount of matrix 6 ’ as well as grain boundary precipitates ( 6 , T-phase) (? 4 ). As a result, there is a...containing 6 ’ precipitates that enhance slip planarity and certain titanium alloys (e.g. alloys with acicular astructure), will be expected to have a

  16. Microstructure development in Al-Cu-Ag-Mg quaternary alloy

    NASA Astrophysics Data System (ADS)

    Zhou, Bin; Froyen, L.

    2012-01-01

    The solidification behaviour of multi-component and multi-phase systems has been largely investigated in binary and ternary alloys. In the present study, a quaternary model system is proposed based on the well known Al-Cu-Ag and Al-Cu-Mg ternary eutectic alloys. The quaternary eutectic composition and temperature were determined by EDS (Energy Dispersive Spectrometry) and DSC (Differential Scanning Calorimetry) analysis, respectively. The microstructure was then characterised by SEM (Scanning Electron Microscope). In the DSC experiments, two types of quaternary eutectics were determined according to their phase composition. For each type of eutectic, various microstructures were observed, which result in different eutectic compositions. Only one of the determined eutectic compositions was further studied by the controlled growth technique in a vertical Bridgeman type furnace. In the initial part of the directionally solidified sample, competing growth between two-phase dendrites and three-phase eutectics was obtained, which was later transformed to competing growth between three-phase and four-phase eutectics. Moreover, silver enrichment was measured at the solidification front, which is possibly caused by Ag sedimentation due to gravity and Ag rejection from dendritic and three-phase eutectic growth, and its accumulation at the solidification front.

  17. Annealing behavior of Cu and dilute Cu-alloy films: Precipitation, grain growth, and resistivity

    NASA Astrophysics Data System (ADS)

    Barmak, K.; Gungor, A.; Cabral, C.; Harper, J. M. E.

    2003-08-01

    The impact of 11 alloying elements, namely, Mg, Ti, In, Sn, Al, Ag, Co, Nb, and B, at two nominal concentrations of 1 and 3 at. %, and Ir and W, at only a nominal concentration of 3 at. %, on the resistivity and grain structure of copper was investigated. The films were electron beam evaporated onto thermally oxidized Si wafers and had thicknesses in the range of 420-560 nm. Pure evaporated Cu films were used as controls. Isothermal anneals were carried out at 400 °C for 5 h; constant-heating rate treatments, with no hold at the temperature, were done at 3 °C to 650 and 950 °C. In all cases, annealing resulted in the lowering of resistivity compared with the as-deposited state. Furthermore, annealing to a higher temperature resulted in lower, postannealing, room-temperature resistivity, unless the film agglomerated or showed evidence of solute redissolution. Annealing also resulted in significant growth of grains, except for the Nb- and W-containing films. In addition, the grain sizes for the nominally 3 at. %, 400 °C-annealed films were smaller than those for the nominally 1.0 at. % films. The interesting exceptions in this case were the Co-containing films, which had a larger grain size than the pure Cu film, and which, in addition, exhibited a larger grain size for the film with the higher concentration of Co. After the 400 °C anneal, Cu(0.4B) and Cu(1.0Ag) had the lowest resistivities at 2.0 and 2.1 μΩ cm, respectively, and Cu(2.8Co) showed the largest average grain size at 1080 nm. The resistivity and grain size for the pure Cu film after the same anneal were 2.0 μΩ cm and 790 nm, respectively. Precipitation of a second phase was observed in 8 of 20 alloy films annealed at 400 °C. No alloy film simultaneously showed the combination of a low resistivity and a larger grain size than pure Cu.

  18. Ag-Pd-Cu alloy inserted transparent indium tin oxide electrodes for organic solar cells

    SciTech Connect

    Kim, Hyo-Joong; Seo, Ki-Won; Kim, Han-Ki; Noh, Yong-Jin; Na, Seok-In

    2014-09-01

    The authors report on the characteristics of Ag-Pd-Cu (APC) alloy-inserted indium tin oxide (ITO) films sputtered on a glass substrate at room temperature for application as transparent anodes in organic solar cells (OSCs). The effect of the APC interlayer thickness on the electrical, optical, structural, and morphological properties of the ITO/APC/ITO multilayer were investigated and compared to those of ITO/Ag/ITO multilayer electrodes. At the optimized APC thickness of 8 nm, the ITO/APC/ITO multilayer exhibited a resistivity of 8.55 × 10{sup −5} Ω cm, an optical transmittance of 82.63%, and a figure-of-merit value of 13.54 × 10{sup −3} Ω{sup −1}, comparable to those of the ITO/Ag/ITO multilayer. Unlike the ITO/Ag/ITO multilayer, agglomeration of the metal interlayer was effectively relieved with APC interlayer due to existence of Pd and Cu elements in the thin region of the APC interlayer. The OSCs fabricated on the ITO/APC/ITO multilayer showed higher power conversion efficiency than that of OSCs prepared on the ITO/Ag/ITO multilayer below 10 nm due to the flatness of the APC layer. The improved performance of the OSCs with ITO/APC/ITO multilayer electrodes indicates that the APC alloy interlayer prevents the agglomeration of the Ag-based metal interlayer and can decrease the thickness of the metal interlayer in the oxide-metal-oxide multilayer of high-performance OSCs.

  19. Performance of commercial aluminium alloys as anodes in gelled electrolyte aluminium-air batteries

    NASA Astrophysics Data System (ADS)

    Pino, M.; Chacón, J.; Fatás, E.; Ocón, P.

    2015-12-01

    The evaluation of commercial aluminium alloys, namely, Al2024, Al7475 and Al1085, for Al-air batteries is performed. Pure Al cladded Al2024 and Al7475 are also evaluated. Current rates from 0.8 mA cm-2 to 8.6 mA cm-2 are measured in a gel Al-air cell composed of the commercial alloy sample, a commercial air-cathode and an easily synthesizable gelled alkaline electrolyte. The influence of the alloying elements and the addition to the electrolyte of ZnO and ZnCl2, as corrosion inhibitors is studied and analysed via EDX/SEM. Specific capacities of up to 426 mAh/g are obtained with notably flat potential discharges of 1.3-1.4 V. The competition between self-corrosion and oxidation reactions is also discussed, as well as the influence of the current applied on that process. Al7475 is determined to have the best behaviour as anode in Al-air primary batteries, and cladding process is found to be an extra protection against corrosion at low current discharges. Conversely, Al1085 provided worse results because of an unfavourable metallic composition.

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

    NASA Technical Reports Server (NTRS)

    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.

  1. Time evolution of morphology in mechanically alloyed Fe-Cu.

    PubMed

    Wille, Catharina G; Al-Kassab, Tala'at; Kirchheim, Reiner

    2011-05-01

    Being widely accessible as well as already utilised in many applications, Fe-Cu acts as an ideal binary model alloy to elaborate the enforced nonequilibrium enhanced solubility in such a solution system that shows a limited regime of miscibility and characterised by a large positive heat of mixing. In addition to the detailed analysis of ball milled Fe-Cu powders by means of Atom Probe Tomography (APT), site specific structural analysis has been performed in this study using Transmission Electron Microscopy (TEM). In this contribution results on powders with low Cu concentrations (2.5-10 at%) are presented. Combining a ductile element (Cu, fcc) and a brittle one (Fe, bcc), striking differences in morphology were expected and found on all length-scales, depending on the mixing ratio of the two elements. However, not only could the atomic mixing of Fe and Cu be evaluated, but also the distribution of impurities, mostly stemming from the fabrication procedure. The combination of APT and TEM enables a correlation between the structural evolution and the chemical mixing during the milling process. For the first time, a clear distinction can be drawn between the morphological evolution at the surface and in the interior of the powder particles. This became possible owing to the site specific sample preparation of TEM lamellae by Focussed Ion Beam (FIB). Surprisingly, the texture arising from the ball milling process can directly be related to the classical rolling texture of cold rolled Fe. In addition, full homogeneity can be achieved even on the nano-scale for this material as shown by APT, resulting in an extended miscibility region in comparison to the equilibrium phase diagram. Grain sizes were determined by means of XRD and TEM. The strain corrected XRD results are in very good agreement with the values derived by TEM, both confirming a truly nanocrystalline structure.

  2. One-pot facile synthesis of CuS/graphene composite as anode materials for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Tao, Hua-Chao; Yang, Xue-Lin; Zhang, Lu-Lu; Ni, Shi-Bing

    2014-11-01

    CuS/graphene composite has been synthesized by the one-pot hydrothermal method using thiourea as the sulfur source and reducing agent. The formation of CuS nanoparticles and the reduction of graphene oxide occur simultaneously during the hydrothermal process, which enables a uniform dispersion of CuS nanoparticles on the graphene nanosheets. The electrochemical performance of CuS/graphene composite was studied as anode materials for lithium ion batteries. The obtained CuS/graphene composite exhibits a relative high reversible capacity and good cycling stability. The good electrochemical performance of CuS/graphene composite can be attributed to graphene, which improves the electronic conductivity of composite and enhances the interfacial stability of electrode and electrolyte.

  3. Displacement cascades in Fesbnd Nisbnd Mnsbnd Cu alloys: RVP model alloys

    NASA Astrophysics Data System (ADS)

    Terentyev, D.; Zinovev, A.; Bonny, G.

    2016-07-01

    Primary damage due to displacement cascades (10-100 keV) has been assessed in Fesbnd 1%Mnsbnd 1%Ni-0.5%Cu and its binary alloys by molecular dynamics (MD), using a recent interatomic potential, specially developed to address features of the Fesbnd Mnsbnd Nisbnd Cu system in the dilute limit. The latter system represents the model matrix for reactor pressure vessel steels. The applied potential reproduces major interaction features of the solutes with point defects in the binary, ternary and quaternary dilute alloys. As compared to pure Fe, the addition of one type of a solute or all solutes together does not change the major characteristics of primary damage. However, the chemical structure of the self-interstitial defects is strongly sensitive to the presence and distribution of Mn and Cu in the matrix. 20 keV cascades were also studied in the Fesbnd Nisbnd Mnsbnd Cu matrix containing <100> dislocation loops (with density of 1024 m-3 and size 2 nm). Two solute distributions were investigated, namely: a random one and one obtained by Metropolis Monte Carlo simulations from our previous work. The presence of the loops did not affect the defect production efficiency but slightly reduced the fraction of isolated self-interstitials and vacancies. The cascade event led to the transformation of the loops into ½<111> glissile configurations with a success rate of 10% in the matrix with random solute distribution, while all the pre-created loops remain stable if the alloy's distribution was applied using the Monte-Carlo method. This suggests that solute segregation to loops "stabilizes" the pre-existing loops against transformation or migration induced by collision cascades.

  4. Non-equilibrium phase map, optical and electrical properties of Cu-Zn-O alloys

    NASA Astrophysics Data System (ADS)

    Subramaniyan, Archana; Perkins, John; O'Hayre, Ryan; Ginley, David; Lany, Stephan; Zakutayev, Andriy

    2014-03-01

    Cuprous oxide (Cu2O) is a candidate p-type solar cell absorber material that has been spotlighted recently due to its low cost, earth abundant and non-toxic nature. The maximum reported efficiency of Cu2O based solar cells is rather low (5. 38%) and it can in part be attributed its forbidden direct band gap (2.1 eV) and higher absorption threshold (2.6 eV). Here, we alloy Cu2O with ZnO via combinatorial RF magnetron sputtering as a function of temperature (T) and composition at fixed 20 mTorr Ar pressure to modify the electronic band structure and reduce its absorption threshold, which can potentially enhance the solar cell performance. A non-equilibrium Cu-Zn-O phase map was generated in the T range 100 - 400 °C and Zn composition 0 - 37 at%. Highly crystalline Cu2O structured Cu-Zn-O alloys with Zn content of 0 to 17 at% were synthesized in the T range 200 - 270 °C. With increasing Zn at%, the preferential orientation in Cu-Zn-O alloy changes from (200) to (111) direction. At lower T (<200 °C), either amorphous or poor crystalline Cu2O structured alloys were observed, whereas at higher T (>270 ° C) and higher Zn composition (>25 at%), CuO or ZnO second phases were observed. The absorption coefficient of all Cu-Zn-O alloys was higher than that of phase pure Cu2O. The absorption threshold () was also reduced significantly, for example, at = 2*104 cm-1 the absorption threshold of Cu-Zn-O alloy with 10 at% Zn reduced from 2.4 eV to 2.1 eV. The electrical conductivity of all Cu-Zn-O alloys was measured to be within 2 - 5 mS/cm.

  5. Growth of Pt/Cu(100): An Atomistic Modeling Comparison with the Pd/Cu(100) Surface Alloy

    NASA Technical Reports Server (NTRS)

    Demarco, Gustavo; Garces, Jorge E.; Bozzolo, Guillermo

    2002-01-01

    The Bozzolo, Ferrante, and Smith (BFS) method for alloys is applied to the study of Pt deposition on Cu(100). The formation of a Cu-Pt surface alloy is discussed within the framework of previous results for Pd/Cu(100). In spite of the fact that both Pd and Pt share the same basic behavior when deposited on Cu, it is seen that subtle differences become responsible for the differences in growth observed at higher cover-ages. In agreement with experiment, all the main features of Pt/Cu(100) and Pd/Cu(100) are obtained by means of a simple modeling scheme, and explained in terms of a few basic ingredients that emerge from the BFS analysis.

  6. Abnormal magnetization behaviors in Sm-Ni-Fe-Cu alloys

    NASA Astrophysics Data System (ADS)

    Yang, W. Y.; Zhang, Y. F.; Zhao, H.; Chen, G. F.; Zhang, Y.; Du, H. L.; Liu, S. Q.; Wang, C. S.; Han, J. Z.; Yang, Y. C.; Yang, J. B.

    2016-06-01

    The magnetization behaviors in Sm-Ni-Fe-Cu alloys at low temperatures have been investigated. It was found that the hysteresis loops show wasp-waisted character at low temperatures, which has been proved to be related to the existence of multi-phases, the Fe/Ni soft magnetic phases and the CaCu5-type hard magnetic phase. A smooth-jump behavior of the magnetization is observed at T>5 K, whereas a step-like magnetization process appears at T<5 K. The CaCu5-type phase is responsible for such abnormal magnetization behavior. The magnetic moment reversal model with thermal activation is used to explain the relation of the critical magnetic field (Hcm) to the temperature (T>5 K). The reversal of the moment direction has to cross over an energy barrier of about 6.6×10-15 erg. The step-like jumps of the magnetization below 5 K is proposed to be resulted from a sharp increase of the sample temperature under the heat released by the irreversible domain wall motion.

  7. Microstructure and Mechanical Properties of Cu-Ag-Zr Alloy

    NASA Astrophysics Data System (ADS)

    Krishna, S. Chenna; Tharian, K. Thomas; Pant, Bhanu; Kottada, Ravi S.

    2013-12-01

    The Cu-3Ag-0.5Zr alloy was produced by vacuum induction melting and subsequently processed through hot forging and rolling. Detailed microstructural characterization of solution-treated (ST) specimen shows three types of phases: Cu matrix, zirconium-rich phase, and Cu-Ag-Zr intermetallic phase. Transmission electron microscopy studies together with energy-dispersive x-ray spectroscopy analysis established the presence of Zr-rich large particles in the ST condition. Aging at 450 °C for 4.5 h after solution treatment resulted in the formation of uniformly distributed fine spherical silver precipitates with an average diameter of 9.0 ± 2.0 nm. Consequently, room temperature yield strength (YS) and ultimate tensile strength (UTS) of the aged specimen increased by 110% and 15%, respectively, compared to those of 120 and 290 MPa of the ST specimen. At elevated temperature, the YS decreased to 146 and 100 MPa at 540 and 640 °C, respectively, for the aged sample. On the contrary, the YS increased to 140 MPa at 540 °C, and thereafter a decrease was observed with a value of 105 MPa at 640 °C for the ST sample. This decrease in YS at higher temperatures is attributed to coarsening of precipitates and dissolution of the precipitates, whereas an increase in YS is attributed to in-situ aging of the samples.

  8. [Mechanical properties of wiredrawn Ag-Pd-Cu alloys].

    PubMed

    Hasegawa, T; Miyagawa, Y; Nakamura, K

    1989-01-01

    Nine experimental Ag-Pd-Cu ternary alloys, containing 20-30 wt% Pd and 10-20 wt% Cu, were cast into rods 4.5 mm in diameter using an original vacuum/argon-pressure oxide-free casting technique. Test samples 2.0 mm in diameter were made from the rods by wire-drawing. After softening and hardening heat treatments, mechanical properties (modulus of elasticity, elastic limit, proof stress, tensile strength, elongation, and Vickers hardness) of the samples were measured to analyze the effects of composition and fifteen sets of correlations between the mechanical properties on the condition that few internal casting defects existed. After softening heat treatment, values of hardness and strength increased with increasing Cu and Pd contents, while they increased approximately with increasing Pd content after hardening heat treatment. After softening and hardening heat treatments, tensile strength ranged from 44.4 to 60.7 and from 68.1 to 89.1 kgf/mm2, respectively. Values of elongation were more than 10% even after hardening heat treatment. Fourteen out of fifteen correlation coefficients (r) were statistically significant (p less than 0.01). One of the regression lines derived was as follows. Tensile strength (kgf/mm2) = 9.1 +/- 0.305 Hv (r = 0.990) Moreover, the mechanical properties observed in this investigation were compared with those of ordinarily cast samples with the same compositions.

  9. Texture in CuZnAl shape memory alloys

    NASA Astrophysics Data System (ADS)

    Park, No-Jin

    1996-06-01

    The pseudoelastic elongation and the Young's modulus were estimated using lexture and orientation dependent properties in the 95.5% hot-rolled Cu-14.0 wt% Zn-8.0 wt% Al, in the 96.7% extruded Cu -17.7 wt% Zn-7.0 wt% Al-0.5 wt%Ti and in the 95% cold drawn Cu-27.1 wt% Zn-4.6 wt% Al shape-memory-alloys. The textures were measured in martensitic phases, and the austenitic textures were calculated using texture transformation, which gave rise to the maximum possible shape change for a particular application. The maximum value of the pseudoelastic elongation (6.55%) was found at the normal direction in the sheet and a minimum value of 2.23% at 35° from the normal direction to the rolling direction. In the rod and wire the maximum value 4.80% and 5.28% were found at 45 and 90° from the axis direction. The anisotropic constant 1.5, 1.2 and 1.3 of the Young's modulus were found in the sheet, rod and wire, respectively. These values enabled us to estimate the optimum texture for a technological application.

  10. Metallic glass alloys of Zr, Ti, Cu and Ni

    DOEpatents

    Lin, X.; Peker, A.; Johnson, W.L.

    1997-04-08

    At least quaternary alloys form metallic glass upon cooling below the glass transition temperature at a rate less than 10{sup 3} K/s. Such alloys comprise titanium from 19 to 41 atomic percent, an early transition metal (ETM) from 4 to 21 atomic percent and copper plus a late transition metal (LTM) from 49 to 64 atomic percent. The ETM comprises zirconium and/or hafnium. The LTM comprises cobalt and/or nickel. The composition is further constrained such that the product of the copper plus LTM times the atomic proportion of LTM relative to the copper is from 2 to 14. The atomic percentage of ETM is less than 10 when the atomic percentage of titanium is as high as 41, and may be as large as 21 when the atomic percentage of titanium is as low as 24. Furthermore, when the total of copper and LTM are low, the amount of LTM present must be further limited. Another group of glass forming alloys has the formula (ETM{sub 1{minus}x}Ti{sub x}){sub a} Cu{sub b} (Ni{sub 1{minus}y}Co{sub y}){sub c} wherein x is from 0.1 to 0.3, y{center_dot}c is from 0 to 18, a is from 47 to 67, b is from 8 to 42, and c is from 4 to 37. This definition of the alloys has additional constraints on the range of copper content, b. 2 figs.

  11. Further studies of the anodic dissolution in sodium chloride electrolyte of aluminium alloys containing tin and gallium

    NASA Astrophysics Data System (ADS)

    Nestoridi, Maria; Pletcher, Derek; Wharton, Julian A.; Wood, Robert J. K.

    As part of a programme to develop a high power density, Al/air battery with a NaCl brine electrolyte, the high rate dissolution of an aluminium alloy containing tin and gallium was investigated in a small volume cell. The objective was to define the factors that limit aluminium dissolution in condition that mimic a high power density battery. In a cell with a large ratio of aluminium alloy to electrolyte, over a range of current densities the extent of dissolution was limited to ∼1000 C cm -2 of anode surface by a thick layer of loosely bound, crystalline deposit on the Al alloy anode formed by precipitation from solution. This leads to a large increase in impedance and acts as a barrier to transport of ions.

  12. Phase-dependent corrosion of titanium-to-stainless steel joints brazed by Ag-Cu eutectic alloy filler and Ag interlayer

    NASA Astrophysics Data System (ADS)

    Lee, M. K.; Park, J. J.; Lee, J. G.; Rhee, C. K.

    2013-08-01

    The electrochemical corrosion properties of Ti-STS dissimilar joints brazed by a 72Ag-28Cu alloy filler and an Ag interlayer were studied in a 3.5% NaCl solution using potentiodynamic polarization and ac impedance spectroscopy. For a joint with a layered structure of Ti(base)/TiAg/Ag solid solution/Ag-Cu eutectic/STS(base), galvanic corrosion mostly occurred in the TiAg phase with a severe material loss, indicating that the TiAg layer acted as an anode in the galvanic couple in the layered joint. The Ag-rich solid solution layer was also corroded to a certain extent, but the corrosion in this layer was dominated by the selective pitting corrosion of the eutectic Cu-rich phase. With an increase in the brazing temperature, the Cu-rich phases disappeared owing to the enhanced isothermal solidification effect, leading to an improvement of the corrosion resistance.

  13. Core-shell Si/Cu nanocomposites synthesized by self-limiting surface reaction as anodes for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Xu, Kaiqi; Zhang, Zhizhen; Su, Wei; Huang, Xuejie

    Core-shell Si/Cu nanocomposites were synthesized via a flexible self-limiting surface reaction without extra reductant for the first time. The nano Si was uniformly coated with Cu nanoparticles with a diameter of 5-10nm, which can enhance the electronic conductivity of the nanocomposites and buffer the huge volume change during charge/discharge owing to its high ductility. Benefited from the unique structure, the Si/Cu nanocomposites exhibited a good electrochemical performance as anodes for lithium ion batteries, which exhibited a capacity retention of 656mAh/g after 50 cycles and a coulombic efficiency of more than 99%.

  14. Mechanical and histologic examination of titanium alloy material treated by sandblasting and anodic oxidization.

    PubMed

    Yamagami, Akiyoshi; Yoshihara, Yusuke; Suwa, Fumihiko

    2005-01-01

    To evaluate the biocompatibility and the bone-bonding strength of new titanium alloy materials treated by sandblasting and anodic oxidization, 3 cylindric test pieces having different surface roughnesses were manufactured and implanted into the diaphyses of the femurs of New Zealand white rabbits. Six weeks later, shear loading tests and histologic examination were carried out. Strong interfacial bonding strength and active new bone formation were confirmed in the peripheral area of the test pieces having a surface roughness (Ra = 2.7 microm and Ra = 4.7 microm). Judging from stable fixation to shear loading in bone tissue, it was concluded that group C (Ra = 2.7 microm) had the best surface condition of the 2 groups. Further detailed examination is required to demonstrate that the surface treatment used for group C (a micro rough surface on a macro rough surface structure) can enhance active bone formation and stable fixation in bone tissue.

  15. Anodic Behavior of Alloy 22 in High Nitrate Brines at Temperatures Higher than 100(degree)C

    SciTech Connect

    Ilevbare, G O; Etien, R A; Estill, J C; Hust, G A; Yilmaz, A; Stuart, M L; Rebak, R B

    2006-03-28

    Alloy 22 (N06022) may be susceptible to crevice corrosion in chloride solutions. Nitrate acts as an inhibitor to crevice corrosion. Several papers have been published regarding the effect of nitrate on the corrosion resistance of Alloy 22 at temperatures 100 C and lower. However, very little is known about the behavior of this alloy in highly concentrated brines at temperatures above 100 C. In the current work, electrochemical tests have been carried out to explore the anodic behavior of Alloy 22 in high chloride high nitrate electrolytes at temperatures as high as 160 C at ambient atmospheres. Even though Alloy 22 may adopt corrosion potentials in the order of +0.5 V (in the saturated silver chloride scale), it does not suffer crevice corrosion if there is high nitrate in the solution. That is, the inhibitive effect of nitrate on crevice corrosion is active for temperatures higher than 100 C.

  16. Anodic behavior of carbon supported Cu@Ag core-shell nanocatalysts in direct borohydride fuel cells

    NASA Astrophysics Data System (ADS)

    Duan, Donghong; Liu, Huihong; You, Xiu; Wei, Huikai; Liu, Shibin

    2015-10-01

    Carbon-supported Cu@Ag core-shell nanoparticles are prepared by a successive reduction method in an aqueous solution and are used as an anode electrocatalyst for the direct borohydride-hydrogen peroxide fuel cell (DBHFC). The physical and electrochemical properties of the as-prepared electrocatalysts are investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), cyclic voltammetry (CV), chronopotentiometry (CP), and fuel cell tests. In situ Fourier transform infrared (FTIR) spectroscopy is employed in 2 M NaOH/0.1 M NaBH4 to understand the borohydride oxidation reaction (BOR) mechanism by studying the intermediate reactions occurring on the Cu@Ag/C electrode. The TEM images show that the average size of the Cu1@Ag1/C particles is approximately 18 nm. Among the as-prepared catalysts, the Cu2@Ag1/C catalyst presents the highest catalytic activity. As shown by in situ FTIR, the oxidation reaction mechanism of BH4- is similar to that of Ag/C: BHn(OH)4-n- + 2OH- → BHn-1(OH)5-n- +H2 O + 2e . At 25 °C, the DBHFC with Cu2@Ag1/C as the anode electrocatalyst and Pt mesh (1 cm2) as the cathode electrode exhibits a maximum anodic power density of 17.27 mW mg-1 at a discharge current density of 27.8 mA mg-1.

  17. Glassy Metal Alloy Nanofiber Anodes Employing Graphene Wrapping Layer: Toward Ultralong-Cycle-Life Lithium-Ion Batteries.

    PubMed

    Jung, Ji-Won; Ryu, Won-Hee; Shin, Jungwoo; Park, Kyusung; Kim, Il-Doo

    2015-07-28

    Amorphous silicon (a-Si) has been intensively explored as one of the most attractive candidates for high-capacity and long-cycle-life anode in Li-ion batteries (LIBs) primarily because of its reduced volume expansion characteristic (∼280%) compared to crystalline Si anodes (∼400%) after full Li(+) insertion. Here, we report one-dimensional (1-D) electrospun Si-based metallic glass alloy nanofibers (NFs) with an optimized composition of Si60Sn12Ce18Fe5Al3Ti2. On the basis of careful compositional tailoring of Si alloy NFs, we found that Ce plays the most important role as a glass former in the formation of the metallic glass alloy. Moreover, Si-based metallic glass alloy NFs were wrapped by reduced graphene oxide sheets (specifically Si60Sn12Ce18Fe5Al3Ti2 NFs@rGO), which can prevent the direct exposure of a-Si alloy NFs to the liquid electrolyte and stabilize the solid-electrolyte interphase (SEI) layers on the surfaces of rGO sheets while facilitating electron transport. The metallic glass nanofibers exhibited superior electrochemical cell performance as an anode: (i) Si60Sn12Ce18Fe5Al3Ti2 NFs show a high specific capacity of 1017 mAh g(-1) up to 400 cycles at 0.05C with negligible capacity loss as well as superior cycling performance (nearly 99.9% capacity retention even after 2000 cycles at 0.5C); (ii) Si60Sn12Ce18Fe5Al3Ti2 NFs@rGO reveals outstanding rate behavior (569.77 mAh g(-1) after 2000 cycles at 0.5C and a reversible capacity of around 370 mAh g(-1) at 4C). We demonstrate the potential suitability of multicomponent a-Si alloy NFs as a long-cycling anode material.

  18. The mineralogical characterization of tellurium in copper anodes

    NASA Astrophysics Data System (ADS)

    Chen, T. T.; Dutrizac, J. E.

    1993-12-01

    A mineralogical study of a «normal» commercial copper anode and six tellurium-rich copper anodes from the CCR Refinery of the Noranda Copper Smelting and Refining Company was carried out to identify the tellurium carriers and their relative abundances. In all the anodes, the major tellurium carrier is the Cu2Se-Cu2Te phase which occurs as a constituent of complex inclusions at the copper grain boundaries. In tellurium-rich anodes, the molar tellurium content of the Cu2Se-Cu2Te phase can exceed that of selenium. Although >85 pct of the tellurium occurs as the Cu2Se-Cu2Te phase, minor amounts are present in Cu-Pb-As-Bi-Sb oxide, Cu-Bi-As oxide, and Cu-Te-As oxide phases which form part of the grain-boundary inclusions. About 1 pct of the tellurium content of silver-rich anodes occurs in various silver alloys, but gold tellurides were never detected. Surprising is the fact that 2 to 8 pct of the total tellurium content of the anodes occurs in solid solution in the copper-metal matrix, and presumably, this form of tellurium dissolves at the anode interface during electrorefining.

  19. One-step electrolytic preparation of Si-Fe alloys as anodes for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Wang, Hailong; Sun, Diankun; Song, Qiqi; Xie, Wenqi; Jiang, Xu; Zhang, Bo

    2016-06-01

    One-step electrolytic formation of uniform crystalline Si-Fe alloy particles was successfully demonstrated in direct electro-reduction of solid mixed oxides of SiO2 and Fe2O3 in molten CaCl2 at 900∘C. Upon constant voltage electrolysis of solid mixed oxides at 2.8V between solid oxide cathode and graphite anode for 5h, electrolytic Si-Fe with the same Si/Fe stoichimetry of the precursory oxides was generated. The firstly generated Fe could function as depolarizers to enhance reduction rate of SiO2, resulting in the enhanced reduction kinetics to the electrolysis of individual SiO2. When evaluated as anode for lithium ion batteries, the prepared SiFe electrode showed a reversible lithium storage capacity as high as 470mAh g-1 after 100 cycles at 200mA g-1, promising application in high-performance lithium ion batteries.

  20. Precipitation Hardening and Statistical Modeling of the Aging Parameters and Alloy Compositions in Al-Cu-Mg-Ag Alloys

    NASA Astrophysics Data System (ADS)

    Al-Obaisi, A. M.; El-Danaf, E. A.; Ragab, A. E.; Soliman, M. S.

    2016-06-01

    The addition of Ag to Al-Cu-Mg systems has been proposed to replace the existing high-strength 2xxx and 7xxx Al alloys. The aged Al-Cu-Mg-Ag alloys exhibited promising properties, due to special type of precipitates named Ω, which cooperate with other precipitates to enhance the mechanical properties significantly. In the present investigation, the effect of changing percentages of alloying elements, aging time, and aging temperature on the hardness values was studied based on a factorial design. According to this design of experiments (DOE)—23 factorial design, eight alloys were cast and hot rolled, where (Cu, Mg, and Ag) were added to aluminum with two different levels for each alloying element. These alloys were aged at different temperatures (160, 190, and 220 °C) over a wide range of time intervals from 10 min. to 64 h. The resulting hardness data were used as an input for Minitab software to model and relate the process variables with hardness through a regression analysis. Modifying the alloying elements' weight percentages to the high level enhanced the hardness of the alloy with about 40% as compared to the alloy containing the low level of all alloying elements. Through analysis of variance (ANOVA), it was figured out that altering the fraction of Cu had the greatest effect on the hardness values with a contribution of about 49%. Also, second-level interaction terms had about 21% of impact on the hardness values. Aging time, quadratic terms, and third-level interaction terms had almost the same level of influence on hardness values (about 10% contribution). Furthermore, the results have shown that small addition of Mg and Ag was enough to improve the mechanical properties of the alloy significantly. The statistical model formulated interpreted about 80% of the variation in hardness values.

  1. Influence of Nanowire Diameter on Structural and Optical Properties of cu Nanowire Synthesized in Anodic Aluminium Oxide Film

    NASA Astrophysics Data System (ADS)

    Cetinel, A.; Özcelik, Z.

    2016-11-01

    Copper (Cu) nanowire arrays embedded in anodic aluminium oxide films (AAO) on aluminium substrate have been synthesized by alternating current electrochemical deposition. Two-step anodization process has been performed to get the through-hole AAO with ordered nanochannels in 0.3M oxalic acids at DC voltages 30, 40, 50 and 60V, respectively. Structural characterization of the Cu nanowires has been analyzed by scanning electron microscopy (SEM) and X-ray diffraction (or) X-ray diffractometer (XRD). Our SEM analysis has revealed that the diameters of vertically oriented Cu nanowires are 15, 25, 45 and 60nm and the length of Cu nanowires having high packing density is about 15μm. XRD measurement has indicated that polycrystalline Cu nanowires prefer growth orientation along the (111) direction. Optical measurements show that reflection of the Cu nanowires/AAO on aluminium reduces with decreasing diameter of the Cu nanowires. This effect can be associated with increased light scattering from metal nanoparticles near their localized plasmon resonance frequency depending on the size and shape of the nanoparticles.

  2. Oxidation resistance of graphene-coated Cu and Cu/Ni alloy.

    PubMed

    Chen, Shanshan; Brown, Lola; Levendorf, Mark; Cai, Weiwei; Ju, Sang-Yong; Edgeworth, Jonathan; Li, Xuesong; Magnuson, Carl W; Velamakanni, Aruna; Piner, Richard D; Kang, Junyong; Park, Jiwoong; Ruoff, Rodney S

    2011-02-22

    The ability to protect refined metals from reactive environments is vital to many industrial and academic applications. Current solutions, however, typically introduce several negative effects, including increased thickness and changes in the metal physical properties. In this paper, we demonstrate for the first time the ability of graphene films grown by chemical vapor deposition to protect the surface of the metallic growth substrates of Cu and Cu/Ni alloy from air oxidation. In particular, graphene prevents the formation of any oxide on the protected metal surfaces, thus allowing pure metal surfaces only one atom away from reactive environments. SEM, Raman spectroscopy, and XPS studies show that the metal surface is well protected from oxidation even after heating at 200 °C in air for up to 4 h. Our work further shows that graphene provides effective resistance against hydrogen peroxide. This protection method offers significant advantages and can be used on any metal that catalyzes graphene growth.

  3. Improving the Mechanical Properties of Cu-15Ni-8Sn Alloys by Addition of Titanium.

    PubMed

    Zhao, Chao; Zhang, Weiwen; Wang, Zhi; Li, Daoxi; Luo, Zongqiang; Yang, Chao; Zhang, Datong

    2017-09-06

    The effect of Ti addition on the microstructure and mechanical properties of Cu-15Ni-8Sn alloys was investigated. Optical microscopy (OM), scanning electronic microscopy (SEM), and transmission electron microscopy (TEM) were used to determine grain size and distribution of the second phases in the alloys. The results indicate that the tensile properties of Cu-15Ni-8Sn alloys are improved significantly with Ti addition. Tensile elongation increased from 2.7% for the alloy without Ti to 17.9% for the alloy with 0.3% Ti, while tensile strength was maintained and even increased from 935 MPa to 1024 MPa. The improvement of the mechanical properties of Cu-15Ni-8Sn alloys by the addition of Ti is attributed to the grain refinement and suppression of discontinuous precipitation during heat treatment.

  4. A new Cu-8 Cr-4 Nb alloy for high temperature applications

    SciTech Connect

    Ellis, D.L.; Michal, G.M.; Dreshfield, R.L.

    1995-06-01

    Various applications exist where a high conductivity alloy with good strength and creep resistance are required. NASA LeRC has developed a Cu-8 at. percent Cr-4 at. percent Nb (Cu-8 Cr-4 Nb) alloy for these applications. The alloy is designed for use up to 700 C and shows exceptional strength, low cycle fatigue (LCF) resistance, and creep resistance. Cu-8 Cr-4 Nb also has a thermal conductivity of at least 72 percent that of pure Cu. Furthermore, the microstructure and mechanical properties of the alloy are very stable. In addition to the original application in combustion chambers, Cu-8 Cr-4 Nb shows promise for welding electrodes, brazing fixtures, and other applications requiring high conductivity and strength at elevated temperatures.

  5. A new Cu-8 Cr-4 Nb alloy for high temperature applications

    NASA Technical Reports Server (NTRS)

    Ellis, D. L.; Michal, G. M.; Dreshfield, R. L.

    1995-01-01

    Various applications exist where a high conductivity alloy with good strength and creep resistance are required. NASA LeRC has developed a Cu-8 at. percent Cr-4 at. percent Nb (Cu-8 Cr-4 Nb) alloy for these applications. The alloy is designed for use up to 700 C and shows exceptional strength, low cycle fatigue (LCF) resistance, and creep resistance. Cu-8 Cr-4 Nb also has a thermal conductivity of at least 72 percent that of pure Cu. Furthermore, the microstructure and mechanical properties of the alloy are very stable. In addition to the original application in combustion chambers, Cu-8 Cr-4 Nb shows promise for welding electrodes, brazing fixtures, and other applications requiring high conductivity and strength at elevated temperatures.

  6. Mechanical properties of Al-Cu alloy-SiC composites

    SciTech Connect

    Anggara, B. S.; Handoko, E.; Soegijono, B.

    2014-09-25

    The synthesis of aluminum (Al) alloys, Al-Cu, from mixture 96.2 % Al and 3.8 % Cu has been prepared by melting process at a temperature of 1200°C. The adding 12.5 wt% up to 20 wt% of SiC on Al-Cu alloys samples has been investigated. The structure analyses were examined by X-Ray Diffractometer (XRD) and scanning electron microscope (SEM). Moreover, the morphology of Al-Cu alloys has been seen as structure in micrometer range. The hardness was measured by hardness Vickers method. According to the results, it can be assumed that the 15 wt% of SiC content is prefer content to get better quality of back to back hardness Vickers of Al-Cu alloys.

  7. Effects of niobium on thermal stability and corrosion behavior of glassy Cu Zr Al Nb alloys

    NASA Astrophysics Data System (ADS)

    Tam, M. K.; Pang, S. J.; Shek, C. H.

    2006-04-01

    The corrosion behavior of Cu95-xZrxAl5 (x=40, 42.5 and 45 at.%) in 1 N HCl, 3 mass% NaCl and 1 N H2SO4 solutions was studied. As Zr content increases, the corrosion resistance is slightly enhanced. In order to improve the corrosion resistance of the Cu Zr Al glassy alloy, Nb was selected to substitute Cu. Although the supercooled liquid region ΔTx of the Cu Zr Al glassy alloys decreases with increasing Nb content, the alloys still retain high glass-forming ability and bulk glassy samples with 1.5 mm diameter can be obtained when up to 5 at.% Nb was added. It is found that the addition of Nb results in improvement of the corrosion resistance of the glassy Cu Zr Al alloys.

  8. Formation and Stability of Equiatomic and Nonequiatomic Nanocrystalline CuNiCoZnAlTi High-Entropy Alloys by Mechanical Alloying

    NASA Astrophysics Data System (ADS)

    Varalakshmi, S.; Kamaraj, M.; Murty, B. S.

    2010-10-01

    Nanocrystalline equiatomic high-entropy alloys (HEAs) have been synthesized by mechanical alloying in the Cu-Ni-Co-Zn-Al-Ti system from the binary CuNi alloy to the hexanary CuNiCoZnAlTi alloy. An attempt also has been made to find the influence of nonequiatomic compositions on the HEA formation by varying the Cu content up to 50 at. pct (Cu x NiCoZnAlTi; x = 0, 8.33, 33.33, 49.98 at. pct). The phase formation and stability of mechanically alloyed powder at an elevated temperature (1073 K [800 °C] for 1 hour) were studied. The nanocrystalline equiatomic Cu-Ni-Co-Zn-Al-Ti alloys have a face-centered cubic (fcc) structure up to quinary compositions and have a body-centered cubic (bcc) structure in a hexanary alloy. In nonequiatomic alloys, bcc is the dominating phase in the alloys containing 0 and 8.33 at. pct of Cu, and the fcc phase was observed in alloys with 33.33 and 49.98 at. pct of Cu. The Vicker’s bulk hardness and compressive strength of the equiatomic nanocrystalline hexanary CuNiCoZnAlTi HEA after hot isostatic pressing is 8.79 GPa, and the compressive strength is 2.76 GPa. The hardness of these HEAs is higher than most commercial hard facing alloys ( e.g., Stellite, which is 4.94 GPa).

  9. A Practical Anodic and Cathodic Curve Intersection Model to Understand Multiple Corrosion Potentials of Fe-Based Glassy Alloys in OH- Contained Solutions

    PubMed Central

    Li, Y. J.; Wang, Y. G.; An, B.; Xu, H.; Liu, Y.; Zhang, L. C.; Ma, H. Y.; Wang, W. M.

    2016-01-01

    A practical anodic and cathodic curve intersection model, which consisted of an apparent anodic curve and an imaginary cathodic line, was proposed to explain multiple corrosion potentials occurred in potentiodynamic polarization curves of Fe-based glassy alloys in alkaline solution. The apparent anodic curve was selected from the measured anodic curves. The imaginary cathodic line was obtained by linearly fitting the differences of anodic curves and can be moved evenly or rotated to predict the number and value of corrosion potentials. PMID:26771194

  10. First-principles study of phase equilibria in Cu-Pt-Rh disordered alloys.

    PubMed

    Yuge, Koretaka

    2009-10-14

    Phase stability of Cu-Pt-Rh ternary disordered alloys is examined by a combination of cluster expansion techniques and Monte Carlo statistical simulation based on first-principles calculation. The sign of pseudo-binary ECIs indicates that neighboring Cu and Pt strongly prefer unlike-atom pairs, Pt and Rh weakly prefer unlike-atom pairs, and Cu and Rh atoms prefer like-atom pairs, indicating that the ternary alloy retains the ordering tendency of the constituent binary alloys. The formation energy of a random alloy at T = 1200 K exhibits a negative sign for a wide range of Pt-rich compositions, while at Pt-poor compositions of x≤0.25, the formation energy has a positive value. Calculated affinities for the random alloy show the variety of energetically favored bonds for the alloy: Cu-Pt bonds in both first-and second-nearest neighbor (1-NN and 2-NN) are energetically preferred for all the composition range, the Pt-Rh bond in 1-NN is preferred at Pt-rich compositions, the Pt-Rh in 2-NN and Rh-Cu in 1-NN bonds are unfavored for all compositions, and the Rh-Cu bond in 2-NN is unfavored for Pt-poor compositions. We elucidate that the ordering tendency of 1-NN and 2-NN Cu-Pt, 2-NN Pt-Rh and 1-NN Cu-Rh atoms in constituent binary alloys is retained for the whole composition range of Cu-Pt-Rh ternary alloys, while that of 1-NN Pt-Rh and 2-NN Cu-Rh atoms significantly depends on composition.

  11. Fracture toughness of an Al-Li-Cu-In alloy

    NASA Technical Reports Server (NTRS)

    Wagner, John A.; Gangloff, Richard P.

    1992-01-01

    The crack initiation and growth fracture toughness of select AL-Li-Cu alloy variants are characterized and elucidated. Conventionally processed plates form large DC cast ingots are investigated to eliminate the variation in microstructure associated with laboratory scale and SPF-processed material. Fracture resistance is characterized using the J-integral method to establish crack initiation and growth behavior at 25 and -185 C. It is shown that state-of-the-art 2090-T81 has superior toughness compared to 2090 + In-T6 at both test temperatures, with the low toughness of 2090 + In-T6 associated with intersubgranular fracture attributed to a high density of subboundary precipitates.

  12. Fracture toughness of an Al-Li-Cu-In alloy

    NASA Technical Reports Server (NTRS)

    Wagner, John A.; Gangloff, Richard P.

    1992-01-01

    The crack initiation and growth fracture toughness of select AL-Li-Cu alloy variants are characterized and elucidated. Conventionally processed plates form large DC cast ingots are investigated to eliminate the variation in microstructure associated with laboratory scale and SPF-processed material. Fracture resistance is characterized using the J-integral method to establish crack initiation and growth behavior at 25 and -185 C. It is shown that state-of-the-art 2090-T81 has superior toughness compared to 2090 + In-T6 at both test temperatures, with the low toughness of 2090 + In-T6 associated with intersubgranular fracture attributed to a high density of subboundary precipitates.

  13. The Influence of Composition on the Clustering and Precipitation Behavior of Al-Mg-Si-Cu Alloys

    NASA Astrophysics Data System (ADS)

    Jia, Zhihong; Ding, Lipeng; Cao, Lingfei; Sanders, Robert; Li, Shichen; Liu, Qing

    2017-01-01

    The natural aging (NA) and artificial aging (AA) behavior of Al-Mg-Si-Cu alloys with different Mg/Si ratios and Cu additions were systematically investigated by means of hardness test, atom probe tomography, transmission electron microscopy, and Monte Carlo simulation. The Si-rich low-Cu alloys displayed higher hardness compared to the Mg-rich equivalents because Si atoms play a dominant role in clustering of solute atoms during both natural and artificial aging. In the high-Cu alloys, Cu did not obviously change the cluster distribution during NA, but significantly refines the clusters and precipitates due to the strong interaction of Cu atoms with Mg atoms during AA. In contrast to the low-Cu alloys, the Mg-rich high-Cu alloys exhibit higher hardness in the early and over-aged stages of artificial aging, with similar or slightly higher hardness in the peak aging condition compared to their Si-rich counterparts. Three types of precipitates ( β″, Q', and L) are favored in the high-Cu alloys. The Mg-rich high-Cu alloy has more L phase, while the Si-rich variant is abundant in Q' phase. The negative effect of NA on subsequent AA behavior is less dependent on Mg/Si ratio in the high-Cu alloys due to a synergistic action of the residual Si and Cu atoms, but is closely related to Mg/Si ratio in low-Cu alloys.

  14. Sacrificial anode stability and polarization potential variation in a ternary Al-xZn-xMg alloy in a seawater-marine environment

    NASA Astrophysics Data System (ADS)

    Muazu, Abubakar; Aliyu, Yaro Shehu; Abdulwahab, Malik; Idowu Popoola, Abimbola Patricia

    2016-06-01

    In this paper, the effects of zinc (Zn) and magnesium (Mg) addition on the performance of an aluminum-based sacrificial anode in seawater were investigated using a potential measurement method. Anodic efficiency, protection efficiency, and polarized potential were the parameters used. The percentages of Zn and Mg in the anodes were varied from 2% to 8% Zn and 1% to 4% Mg. The alloys produced were tested as sacrificial anodes for the protection of mild steel in seawater at room temperature. Current efficiency as high as 88.36% was obtained in alloys containing 6% Zn and 1% Mg. The polarized potentials obtained for the coupled (steel/Al-based alloys) are as given in the Pourbaix diagrams, with steel lying within the immunity region/cathodic region and the sacrificial anodes within the anodic region. The protection offered by the sacrificial anodes to the steel after the 7th and 8th week was measured and protection efficiency values as high as 99.66% and 99.47% were achieved for the Al-6%Zn-1%Mg cast anode. The microstructures of the cast anodes comprise of intermetallic structures of hexagonal Mg3Zn2 and body-centered cubic Al2Mg3Zn3. These are probably responsible for the breakdown of the passive alumina film, thus enhancing the anode efficiency.

  15. Alloy Catalyst in a Reactive Environment: The Example of Ag-Cu Particles for Ethylene Epoxidation

    SciTech Connect

    Piccinin, Simone; Zafeiratos, Spiros; Stampfl, Catherine; Hansen, Thomas W.; Haevecker, Michael; Teschner, Detre; Girgsdies, Frank; Knop-Gericke, Axel; Schloegl, Robert; Scheffler, Matthias; Bukhtiyarov, Valerii I.

    2010-01-22

    Combining first-principles calculations and in situ photoelectron spectroscopy, we show how the composition and structure of the surface of an alloy catalyst is affected by the temperature and pressure of the reagents. The Ag-Cu alloy, recently proposed as an improved catalyst for ethylene epoxidation, forms a thin Cu-O surface oxide, while a Ag-Cu surface alloy is found not to be stable. Several possible surface structures are identified, among which the catalyst surface is likely to dynamically evolve under reaction conditions.

  16. Microstructure and magnetic behavior of Cu-Co-Si ternary alloy synthesized by mechanical alloying and isothermal annealing

    NASA Astrophysics Data System (ADS)

    Chabri, Sumit; Bera, S.; Mondal, B. N.; Basumallick, A.; Chattopadhyay, P. P.

    2017-03-01

    Microstructure and magnetic behavior of nanocrystalline 50Cu-40Co-10Si (at%) alloy prepared by mechanical alloying and subsequent isothermal annealing in the temperature range of 450-650 °C have been studied. Phase evolution during mechanical alloying and isothermal annealing is characterized by X-ray diffraction (XRD), differential thermal analyzer (DTA), high resolution transmission electron microscopy (HRTEM) and magnetic measurement. Addition of Si has been found to facilitate the metastable alloying of Co in Cu resulting into the formation of single phase solid solution having average grain size of 9 nm after ball milling for 50 h duration. Annealing of the ball milled alloy improves the magnetic properties significantly and best combination of magnetic properties has been obtained after annealing at 550 °C for 1 h duration.

  17. Biodegradable Mg-Cu alloys with enhanced osteogenesis, angiogenesis, and long-lasting antibacterial effects

    PubMed Central

    Liu, Chen; Fu, Xuekun; Pan, Haobo; Wan, Peng; Wang, Lei; Tan, Lili; Wang, Kehong; Zhao, Ying; Yang, Ke; Chu, Paul K.

    2016-01-01

    A series of biodegradable Mg-Cu alloys is designed to induce osteogenesis, stimulate angiogenesis, and provide long-lasting antibacterial performance at the same time. The Mg-Cu alloys with precipitated Mg2Cu intermetallic phases exhibit accelerated degradation in the physiological environment due to galvanic corrosion and the alkaline environment combined with Cu release endows the Mg-Cu alloys with prolonged antibacterial effects. In addition to no cytotoxicity towards HUVECs and MC3T3-E1 cells, the Mg-Cu alloys, particularly Mg-0.03Cu, enhance the cell viability, alkaline phosphatase activity, matrix mineralization, collagen secretion, osteogenesis-related gene and protein expressions of MC3T3-E1 cells, cell proliferation, migration, endothelial tubule forming, angiogenesis-related gene, and protein expressions of HUVECs compared to pure Mg. The favorable osteogenesis and angiogenesis are believed to arise from the release of bioactive Mg and Cu ions into the biological environment and the biodegradable Mg-Cu alloys with osteogenesis, angiogenesis, and long-term antibacterial ability are very promising in orthopedic applications. PMID:27271057

  18. Ex Situ Investigation of Anisotropic Interconnection in Silicon-Titanium-Nickel Alloy Anode Material

    DOE PAGES

    Cho, Jong -Soo; Alaboina, Pankaj Kumar; Kang, Chan -Soon; ...

    2017-03-10

    Herein we investigate the nanostructural evolution of Silicon-Titanium-Nickel (Si-Ti-Ni) ternary alloy material synthesized by melt spinning process for advanced lithium-ion battery anode. The synthesized material was found to have nano-Silicon particles dispersed in the Ti4Ni4Si7 (STN) alloy buffering matrix and was characterized by X-ray diffraction (XRD), High resolution- transmission electron microscope (HR-TEM), Scanning transmission electron microscopes - energy dispersive X-ray spectrometer (STEM-EDS), and electrochemical performance test. The role of STN matrix is to accommodate the volume expansion stresses of the dispersed Si nanoparticles. However, an interesting behavior was observed during cycling. The Si nanoparticles were observed to form interconnection channelsmore » growing through the weak STN matrix cracks and evolving to a network isolating the STN matrix into small puddles. In conclusion, this unique nanostructural evolution of Si particles and isolation of the STN matrix failing to offer significant buffering effect to the grown Si network eventually accelerates more volume expansions during cycling due to less mechanical confinement and leads to performance degradation and poor cycle stability.« less

  19. Mechanical properties and microstructures of dental cast Ti-Ag and Ti-Cu alloys.

    PubMed

    Takahashi, Masatoshi; Kikuchi, Masafumi; Takada, Yukyo; Okuno, Osamu

    2002-09-01

    In this study, experimental Ti-Ag alloys (5, 10, and 20 mass% Ag) and Ti-Cu alloys (2, 5, and 10 mass% Cu) were made in an argon-arc melting furnace. The alloys were cast into magnesia molds using an argon gas-pressure dental casting machine, and the mechanical properties and microstructures of the castings were investigated. As the concentration of silver or copper in the alloys increased, the tensile strength, yield strength, and hardness of the alloys became higher than those of CP Ti, and the elongation of the alloys became lower than that of CP Ti. Changes in the mechanical properties by alloying were considered to be caused by solid-solution strengthening of the a-phases and by precipitation of intermetallic compounds.

  20. Controlling Bulk Cu6Sn5 Nucleation in Sn0.7Cu/Cu Joints with Al Micro-alloying

    NASA Astrophysics Data System (ADS)

    Xian, J. W.; Belyakov, S. A.; Gourlay, C. M.

    2016-01-01

    We show that dilute Al additions can control the size of primary Cu6Sn5 rods in Sn-0.7Cu/Cu ball grid array joints. In Sn-0.7Cu-0.05Al/Cu joints, the number of primary Cu6Sn5 per mm2 is ˜7 times higher and the mean three-dimensional length of rods is ˜4 times smaller than in Al-free Sn-0.7Cu/Cu joints, while the area fraction of primary Cu6Sn5 is similar. It is shown that epitaxial nucleation of primary Cu6Sn5 occurs on δ-Cu33Al17 or γ 1-Cu9Al4 particles, which are stable in the Sn-0.7Cu-0.05Al melt during holding at 250°C. The observed facet relationships agree well with previously determined orientation relationships between δ-Cu33Al17 and Cu6Sn5 in hypereutectic Sn-Cu-Al alloys and result in a good lattice match with <˜2.5% lattice mismatch on two different interfacial planes.

  1. Elevated Temperature Creep Properties of Conventional 50Au-50Cu and 47Au 50Cu-3Ni Braze Alloys

    SciTech Connect

    STEPHENS JR.,JOHN J.; SCHMALE,DAVID T.

    2000-12-18

    The elevated temperature creep properties of the 50Au-50Cu wt% and 47Au-50Cu-3Ni braze alloys have been evaluated over the temperature range 250-850 C. At elevated temperatures, i.e., 450-850 C, both alloys were tested in the annealed condition (2 hrs. 750 C/water quenched). The minimum strain rate properties over this temperature range are well fit by the Garofalo sinh equation. At lower temperatures (250 and 350 C), power law equations were found to characterize the data for both alloys. For samples held long periods of time at 375 C (96 hrs.) and slowly cooled to room temperature, an ordering reaction was observed. For the case of the 50Au-50Cu braze alloy, the stress necessary to reach the same, strain rate increased by about 15% above the baseline data. The limited data for ordered 47Au-50Cu-3Ni alloy reflected a,smaller strength increase. However, the sluggishness of this ordering reaction in both alloys does not appear to pose a problem for braze joints cooled at reasonable rates following brazing.

  2. Estimation of thermodynamic properties of Cu-La binary alloy with modified Miedema's theory

    NASA Astrophysics Data System (ADS)

    Li, Hai-hong; Zhang, Shi-hong; Chen, Yan; Cheng, Ming; Song, Hong-wu; Liu, Jin-song

    2016-01-01

    According to modified Miedema's theory, mixing enthalpies (Δ H), excess entropies ( S E), excess Gibbs free energy ( G E), and component activities ( a) of Cu-La binary alloy were estimated using the basic thermodynamic principles and some simple physical parameters of Cu and La, such as electronegativity, atomic volume and electron density. Based on the Cu-La binary alloy phase diagram, the Gibbs free energy of the phase precipitation reactions of Cu6La and Cu5La was deduced. The results showed that the values of Δ H, S E, and G E of Cu-La binary alloy were all negative. Compared to the ideal solution, the activities of the components presented a large negative deviation from Raoult's law, which indicated that there was a strong interaction between Cu and La. The calculated data are well consistent with the experimental data. The Gibbs free energies of the phase precipitation reactions of Cu6La are lower than those for Cu5La, which means that Cu6La is thermodynamically more stable than Cu5La. Furthermore, the experimental results show that rareearth rich Cu6La phase particles in copper matrix are formed after La microalloying.

  3. Phase transformations and age-hardening behaviors related to Au3Cu in Au-Cu-Pd alloys.

    PubMed

    Winn, H; Udoh, K; Tanaka, Y; Hernandez, R I; Takuma, Y; Hisatsune, K

    1999-09-01

    Phase transformation behaviors in Au-Cu-Pd alloys were investigated by means of electrical resistivity measurements, hardness tests, X-ray diffraction and transmission electron microscopy. Anisothermal and isothermal annealing were performed. Two types of phase transformations were found, namely related to the single phase of Au3Cu and the coexistent phase of Au3Cu and AuCu I. The latter produced more remarkable hardening than the former. Hardening was brought about by the antiphase domain size effect of Au3Cu ordered phase in the single phase and by the formation of AuCu I ordered phase in the Au3Cu ordered matrix. There are three modes of phase transformation in the coexistent region depending on the composition. Each sequence is discussed.

  4. Microstructure and Corrosion Behavior of the Cu-Pd-X Ternary Alloys for Hydrogen Separation Membranes

    SciTech Connect

    O.N. Dogan; M.C. Gao; B.H. Howard

    2012-02-26

    CuPd alloys are among the most promising candidate materials for hydrogen separation membranes and membrane reactor applications due to their high hydrogen permeability and better sulfur resistance. In order to reduce the Pd content and, therefore, the cost of the membrane materials, efforts have been initiated to develop CuPdM ternary alloys having a bcc structure. The advantages of having Pd as a hydrogen separation membrane are: (1) high hydrogen selectivity; and (2) high hydrogen permeability. The disadvantages are: (1) high cost; (2) hydrogen embrittlement ({alpha} {yields} {beta} Pd hydride); and (3) sulfur poisoning. Experiments (XRD, SEM/EDS) verified that Mg, Al, La, Y and Ti are promising alloying elements to expand the B2 phase region in Cu-Pd binary system. HT-XRD showed that the B2 to FCC transition temperatures for Cu-Pd-X (X = Mg, Al, La, Y and Ti) are higher than that of Cu-Pd binary alloys. While the Cu-50Pd alloy had the highest corrosion resistance to the H2S containing syngas, the Cu-Pd-Mg alloy had a comparable resistance.

  5. Pd-Cu-M (M = Y, Ti, Zr, V, Nb, and Ni) Alloys for the Hydrogen Separation Membrane.

    PubMed

    Nayebossadri, Shahrouz; Speight, John D; Book, David

    2017-01-25

    Self-supported fcc Pd-Cu-M (M = Y, Ti, Zr, V, Nb, and Ni) alloys were studied as potential hydrogen purification membranes. The effects of small additions (1-2.6 at. %) of these elements on the structure, hydrogen solubility, diffusivity, and permeability were examined. Structural analyses by X-ray diffraction (XRD) showed the fcc phase for all alloys with induced textures from cold rolling. Heat treatment at 650 °C for 96 h led to the reorientation in all alloys except the Pd-Cu-Zr alloy, exhibiting the possibility to enhance the structural stability by Zr addition. Hydrogen solubility was almost doubled in the ternary alloys containing Y and Zr compared to Pd65.1Cu34.9 alloy at 300 °C. It was noted that hydrogen diffusivity is decreased upon additions of these elements compared to the Pd65.1Cu34.9 alloy, with the Pd-Cu-Zr alloy showing the lowest hydrogen diffusivity. However, the comparable hydrogen permeability of the Pd-Cu-Zr alloy with the corresponding binary alloy, as well as its highest hydrogen permeability among the studied ternary alloys at temperatures higher than 300 °C, suggested that hydrogen permeation of these alloys within the fcc phase is mainly dominated by hydrogen solubility. Hydrogen flux variations of all ternary alloys were studied and compared with the Pd65.1Cu34.9 alloy under 1000 ppm of H2S + H2 feed gas. Pd-Cu-Zr alloy showed superior resistance to the sulfur poisoning probably due to the less favorable H2S-surface interaction and more importantly slower rate of bulk sulfidation as a result of improved structural stability upon Zr addition. Therefore, Pd-Cu-Zr alloys may offer new potential hydrogen purification membranes with improved chemical stability and hydrogen permeation compared to the binary fcc Pd-Cu alloys.

  6. Mechanism of abnormally slow crystal growth of CuZr alloy

    SciTech Connect

    Yan, X. Q.; Lü, Y. J.

    2015-10-28

    Crystal growth of the glass-forming CuZr alloy is shown to be abnormally slow, which suggests a new method to identify the good glass-forming alloys. The crystal growth of elemental Cu, Pd and binary NiAl, CuZr alloys is systematically studied with the aid of molecular dynamics simulations. The temperature dependence of the growth velocity indicates the different growth mechanisms between the elemental and the alloy systems. The high-speed growth featuring the elemental metals is dominated by the non-activated collision between liquid-like atoms and interface, and the low-speed growth for NiAl and CuZr is determined by the diffusion across the interface. We find that, in contrast to Cu, Pd, and NiAl, a strong stress layering arisen from the density and the local order layering forms in front of the liquid-crystal interface of CuZr alloy, which causes a slow diffusion zone. The formation of the slow diffusion zone suppresses the interface moving, resulting in much small growth velocity of CuZr alloy. We provide a direct evidence of this explanation by applying the compressive stress normal to the interface. The compression is shown to boost the stress layering in CuZr significantly, correspondingly enhancing the slow diffusion zone, and eventually slowing down the crystal growth of CuZr alloy immediately. In contrast, the growth of Cu, Pd, and NiAl is increased by the compression because the low diffusion zones in them are never well developed.

  7. Evaluation of the microstructure of Al-Cu-Li-Ag-Mg Weldalite (tm) alloys, part 4

    NASA Technical Reports Server (NTRS)

    Pickens, Joseph R.; Kumar, K. S.; Brown, S. A.; Gayle, Frank W.

    1991-01-01

    Weldalite (trademark) 049 is an Al-Cu-Li-Ag-Mg alloy designed to have ultrahigh strength and to serve in aerospace applications. The alloy displays significantly higher strength than competitive alloys in both naturally aged and artificially aged tempers. The strengthening phases in such tempers have been identified to, in part, explain the mechanical properties attained. In general, the alloy is strengthened by delta prime Al3Li and Guinier-Preston (GP) zones in the naturally aged tempers. In artificially aged tempers in slightly underaged conditions, strengthening is provided by several phases including GP zones, theta prime Al2Cu, S prime Al2CuMg, T(sub 1) Al2CuLi, and possibly a new phase. In the peak strength artificially aged tempers, T(sub 1) is the predominant strengthening phase.

  8. Effects of a micro pattern on Cu alloy electrodeposition and its application as an oil detector

    NASA Astrophysics Data System (ADS)

    Lee, Jae Min; Ko, Jong Soo

    2016-12-01

    In this study, the effects of open area ratio (OAR) variations by micro-patterns on Cu alloy electrodeposition were analyzed experimentally. To change the OAR of the samples, a strip-type micro-pattern was formed on a substrate through a photolithography process. Moreover, the OAR was controlled by adjusting the distance of the stripe pattern to a width of 20 μm. When electrodeposition was applied on a non-patterned substrate with an OAR of 100%, a pillar-type Cu alloy structure was produced. In addition, when the OAR was decreased to 40%, the height of the Cu alloy structures was increased. However, when the OAR was decreased to 20%, no electrodeposited structures were formed. To confirm the industrial effectiveness of the electrodeposited structures on a micro-pattern, the Cu alloy electrodeposited structures were applied to the formation of an oil detector.

  9. Identification of strengthening phases in Al-Cu-Li alloy Weldalite (tm) 049

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Microstructure property relationships were determined for a family of ultrahigh strength weldable Al-Cu-Li based alloys referred to as Weldalite (tm) alloys. The highest strength variant of this family, Weldalite 049, has a high Cu/Li wt pct. ratio with a nominal composition of Al-6.3Cu-1.3Li-0.4Ag-0.4Mg-0.14Zr. Increasing the alloy's lithium content above 1.3 wt pct. resulted in a decrease in both yield and ultimate tensile strength. Strength was shown to be strongly dependent on lithium content, with a maximum in strength occurring in the range of about 1.1 to 1.4 wt pct. lithium. The strengthening phases present in Weldalite 049 (1.3Li) and an Al-6.3Cu-1.9Li-0.4Mg-0.14Zr alloy were identified using transmission electron microscopy (TEM).

  10. Corrosion resistance evaluation of Pd-free Ag-Au-Pt-Cu dental alloys.

    PubMed

    Fujita, Takeshi; Shiraishi, Takanobu; Takuma, Yasuko; Hisatsune, Kunihiro

    2011-01-01

    The corrosion resistance of nine experimental Pd-free Ag-Au-Pt-Cu dental alloys in a 0.9% NaCl solution was investigated using cyclic voltammetry (CV), optical microscopy, and scanning electron microscopy (SEM). CV measurements revealed that the breakdown potential (E(bd)) and zero current potential (E(zc)) increased with increasing Au/(Au+Ag) atomic ratio. Thus, the Au/(Au+Ag) atomic ratio, but not the Cu content, influenced the corrosion resistance of Ag-Au-Pt-Cu alloys. After the forward scan of CV, both optical and scanning electron microscope images showed that in all the experimental alloys, the matrix phase was corroded but not the second phase. From corrosion resistance viewpoint, the Ag-Au-Pt-Cu alloys seemed to be suitable for clinical application.

  11. A new Cu(GeNx) alloy film for industrial applications

    NASA Astrophysics Data System (ADS)

    Lin, Chon-Hsin

    2014-11-01

    In this study, a copper alloy [Cu(GeNx)] film is developed for industrial applications by cosputtering Cu and Ge targets on a barrierless Si substrate within a vacuum chamber sparsely filled with N2 gas. Through extensive tests conducted in this study, the alloy film shows good thermal stability and adhesion to the substrate with no noticeable interactions between the film and the substrate after annealing at 720 °C for 1 h. The new Cu(GeNx) alloy film also renders adequate wetting for solders, shows good solderability, and has a dissolution rate lower than pure Cu by at least one order of magnitude, in addition to having a comparable consumption rate to Ni. The alloy film seems suitable for industrial applications in, e.g., barrierless Si metallization, interconnect manufacture and, the replacement of the wetting and diffusion layers for flip-chip solder joints in conventional metallurgy.

  12. On the origin of bulk glass forming ability in Cu-Hf, Zr alloys

    NASA Astrophysics Data System (ADS)

    Ristić, Ramir; Zadro, Krešo; Pajić, Damir; Figueroa, Ignacio A.; Babić, Emil

    2016-04-01

    Understanding the formation of bulk metallic glasses (BMG) in metallic systems and finding a reliable criterion for selection of BMG compositions are among the most important issues in condensed-matter physics and material science. Using the results of magnetic susceptibility measurements performed on both amorphous and crystallized Cu-Hf alloys (30-70 at% Cu) we find a correlation between the difference in magnetic susceptibilities of corresponding glassy and crystalline alloys and the variation in the glass forming ability (GFA) in these alloys. Since the same correlation can be inferred from data for the properties associated with the electronic structure of Cu-Zr alloys, it seems quite general and may apply to other glassy alloys based on early and late transition metals. This correlation is plausible from the free-energy considerations and provides a simple way to select the compositions with high GFA.

  13. Effect of alloying on the photoluminescence of the CuInS2 nanocrystals

    NASA Astrophysics Data System (ADS)

    Kim, Young-Kuk; Choi, Chul-Jin

    2011-10-01

    We have developed a novel route to highly luminescent Cd-free core-shell nanocrystals. By simply refluxing assynthesized CuInS2 nanocrystals with zinc acetate and palmitic acid, highly luminescent CuInS2/ZnS nanocrystals were synthesized. We modified the photoluminescence of the grown nanocrystal by alloying foreign atoms. Nanocrystals with alloyed cores were synthesized by adding selenium and nanocrystals with alloyed shell layers were synthesized by refluxing the as-synthesized CuInS2 nanocrystals with mixture of cadmium acetate, zinc acetate and palmitic acid. It was found that the emission wavelength of the nanocrystals was shifted to longer wavelength side by alloying. The photoluminescence spectra showed clear red-shift without significant minimization of emission intensity. A Detailed study on the emission process of nanocrystals implies that the formation of shell layers with small lattice mismatch minimized mismatch strain generated from the shell layers in contrast to core alloyed nanocrystals.

  14. Effect of delayed aging on mechanical properties of an Al-Cu-Mg alloy

    SciTech Connect

    Ravindranathan, S.P.; Kashyap, K.T.; Kumar, S.R.; Ramachandra, C.; Chatterji, B.

    2000-02-01

    The effect of delayed aging on mechanical properties is characteristically found in Al-Mg-Si alloys. Delayed aging refers to the time elapsed between solutionizing and artificial aging. Delayed aging leads to inferior properties. This effect was investigated in an Al-Cu-Mg alloy (AU2GN) of nominal composition Al-2Cu-1.5Mg-1Fe-1Ni as a function of delay. This alloy also showed a drop in mechanical properties with delay. The results are explained on the basis of Pashley's kinetic model to qualitatively explain the evolution of a coarse precipitate structure with delay. It is found that all the results of delayed aging in the Al-Cu-Mg alloys are similar to those found in Al-Mg-Si alloys.

  15. Synthesis of Cu3Sn alloy nanocrystals through sequential reduction induced by gradual increase of the reaction temperature.

    PubMed

    Cho, Sanghun; Shin, Dong-Hun; Yin, Zhenxing; Lee, Chaedong; Park, Si Yun; Yoo, Jeeyoung; Piao, Yuanzhe; Kim, Youn Sang

    2015-04-27

    Cu3Sn alloy nanocrystals are synthesized by sequential reduction of Cu and Sn precursors through a gradual increase of the reaction temperature. By transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), UV/Vis spectroscopy, and X-ray diffraction (XRD) analyses, the alloy formation mechanism of Cu3Sn nanocrystals has been studied. The incremental increase of the reaction temperature sequentially induces the reduction of Sn, the diffusion of Sn into the preformed Cu nanocrystals, resulting in the intermediate phase of Cu-Sn alloy nanocrystals, and then the formation of Cu3Sn alloy nanocrystals. We anticipate that the synthesis of Cu3Sn alloy nanocrystals encourages studies toward the synthesis of various alloy nanomaterials.

  16. Elastic moduli of cast Ti-Au, Ti-Ag, and Ti-Cu alloys.

    PubMed

    Kikuchi, Masafumi; Takahashi, Masatoshi; Okuno, Osamu

    2006-07-01

    This study investigated the effect of alloying titanium with gold, silver, or copper on the elastic properties of the alloys. A series of binary titanium alloys was made with four concentrations of gold, silver, or copper (5, 10, 20, and 30 mass%) in an argon-arc melting furnace. The Young's moduli and Poisson's ratios of the alloy castings were determined with an ultrasonic-pulse method. The density of each alloy was previously measured by the Archimedes' principle. Results were analyzed using one-way ANOVA and the Scheffé's test. The densities of Ti-Au, Ti-Ag, and Ti-Cu alloys monotonically increased as the concentration of alloying elements increased. As the concentration of gold or silver increased to 20%, the Young's modulus significantly decreased, followed by a subsequent increase in value. As the concentration of copper increased, the Young's modulus monotonically increased. The Young's moduli of all the Ti-Cu alloys were significantly higher than that of the titanium. The density of all the experimental alloys was virtually independent of the alloy phases, while the Young's moduli and Poisson's ratios of the alloys were dependent. The addition of gold or silver slightly reduced the Young's modulus of the titanium when the alloy phase was single alpha. The increase in the Young's modulus of the Ti-Cu alloys is probably due to the precipitation of intermetallic compound Ti2Cu. Copper turned out to be a moderate stiffener that gains a Young's modulus of titanium up to 20% at the copper concentration of 30 mass%.

  17. Effect of Thermomechanical Processing on the Microstructure and Properties of a Cu-Fe-P Alloy

    NASA Astrophysics Data System (ADS)

    Dong, Qiyi; Shen, Leinuo; Cao, Feng; Jia, Yanlin; Liao, Kaiju; Wang, Mingpu

    2015-04-01

    A Cu-0.7Fe-0.15P (wt.%) alloy was designed, and its comprehensive properties, especially electrical conductivity and temper-softening resistance of the designed alloy, were higher than those of traditional Cu-Fe-P alloys. The microstructure of this alloy was investigated with optical microscopy, scanning electron microscopy, and transmission electron microscopy. The particle of secondary phase was confirmed to be Fe2P with x-ray spectroscopy and digital diffractogram. By virtue of precipitation hardening and work hardening, the tensile strength and electrical conductivity of Cu-0.7Fe-0.15P alloy were 498 MPa and 62% IACS, respectively. The electrical conductivity of this alloy can be up to 92% IACS due to the complete precipitation of Fe2P. After repeating the cold rolling and aging process for three times, the tensile strength, elongation, and conductivity of this alloy were 467 MPa, 22%, and 78% IACS, respectively. Due to the low driving force of recrystallization and the pinning effect of fine dispersed Fe2P, the alloy with low deformation rate showed excellent softening resistance. The designed alloy can be used as a high-strength, high-electrical-conductivity lead-frame alloy.

  18. Modified embedded-atom method interatomic potential for the Fe-Cu alloy system and cascade simulations on pure Fe and Fe-Cu alloys

    NASA Astrophysics Data System (ADS)

    Lee, Byeong-Joo; Wirth, Brian D.; Shim, Jae-Hyeok; Kwon, Junhyun; Kwon, Sang Chul; Hong, Jun-Hwa

    2005-05-01

    A modified embedded-atom method (MEAM) interatomic potential for the Fe-Cu binary system has been developed using previously developed MEAM potentials of Fe and Cu. The Fe-Cu potential was determined by fitting to data on the mixing enthalpy and the composition dependencies of the lattice parameters in terminal solid solutions. The potential gives a value of 0.65eV for the dilute heat of solution and reproduces the increase of lattice parameter of Fe with addition of Cu in good agreement with experiments. The potential was used to investigate the primary irradiation defect formation in pure Fe and Fe-0.5at.%Cu alloy by a molecular dynamics cascade simulation study with a PKA energy of 2keV at 573K . A tendency for self-interstitial atom-Cu binding, the formation of mixed (Fe-Cu) dumbbells and even Cu-Cu dumbbells was observed. Given a positive binding energy between Cu atoms and self-interstitials, Cu transport by an interstitial diffusion mechanism could be proposed to contribute to the formation of Cu-rich precipitates and irradiation-induced embrittlement in nuclear structural steels.

  19. Corrosion behavior of Cu and the Cu-Zn-Al shape memory alloy in simulated uterine fluid.

    PubMed

    Chen, Bangyi; Liang, Chenghao; Fu, Daojun; Ren, Deming

    2005-09-01

    Chemical immersion tests, electrochemical methods and atomic absorption spectrometry were employed to investigate the corrosion behavior of Cu and the Cu-Zn-Al shape memory alloy (SMA) in simulated uterine fluid. The effect of pH on corrosion rate and corrosion potential was also investigated. The results indicated that in the static state in simulated uterine fluid, dealuminumification of the Cu-Zn-Al alloy occurred with Cl- combining with aluminum ions to form hydroxyl aluminum chloride. The hydroxyl aluminum chloride hydrolyzed readily and facilitated further dealuminumification corrosion. The corrosion process of Cu and Cu-Zn-Al SMA in simulated uterine fluid was controlled by cathodic reduction of oxygen. Because the tendency for surface ionization is greater for aluminum than for zinc, a compact protective aluminum layer was formed, which inhibited the cathodic reduction of oxygen. Hence, the corrosion rate of Cu-Zn-Al SMA was smaller than that of Cu in simulated uterine fluid. With increasing pH, the corrosion rate of Cu and Cu-Zn-Al SMA in simulated uterine fluid decreased and the open-circuit potential moved in a positive direction.

  20. Effect of Cu content on exfoliation corrosion and electrochemical corrosion of A7N01 aluminum alloy in EXCO solution

    NASA Astrophysics Data System (ADS)

    He, Yaling; Wang, Xiaomin; Hu, Jie; Zhou, Qiang; Chen, Hui

    2017-07-01

    The exfoliation corrosion (EXCO) sensitivities and electrochemical corrosions of A7N01 aluminum (Al) alloys with 0.074% and 0.136% Cu contents were investigated in EXCO solution. The exfoliation corrosion developed more rapidly for the alloy with 0.136% Cu by expressing higher exfoliation rate and deeper corrosion pits as observed by SEM and laser confocal scanning microscopy (LCSM). In EXCO solution, the alloy with 0.136% Cu content showed lower open-circuit potential (OCP) than the alloy with 0.074% Cu content. The alloy with 0.136% Cu content had bigger “hysteresis loop” in cyclic polarization curve which meant lower self-passivation ability. In electrochemical impedance spectroscopy plot, its curvature radius and capacitance index were lower. The electrochemical test results revealed that the alloy with 0.136% Cu content showed more severe electrochemical corrosion than the alloy with 0.074% Cu content, consistent with the exfoliation corrosion results. The microstructures of two alloys were observed through optical microscopy (OM) and transmission electron microscopy (TEM). The continuous distribution of the equilibrium precipitate η-MgZn2 on grain boundaries, the decreasing of the width of precipitate-free zone (PFZ) and the coarse Cu-Fe-Si-rich phase were responsible for the higher corrosion sensitivity of the Al alloy with 0.136% Cu than that of Al alloy with 0.074% Cu content in EXCO solution.

  1. Performance of AA5052 alloy anode in alkaline ethylene glycol electrolyte with dicarboxylic acids additives for aluminium-air batteries

    NASA Astrophysics Data System (ADS)

    Wang, DaPeng; Zhang, DaQuan; Lee, KangYong; Gao, LiXin

    2015-11-01

    Dicarboxylic acid compounds, i.e. succinic acid (SUA), adipic acid (ADA) and sebacic acid (SEA), are used as electrolyte additives in the alkaline ethylene glycol solution for AA5052 aluminium-air batteries. It shows that the addition of dicarboxylic acids lowers the hydrogen gas evolution rate of commercial AA5052 aluminium alloy anode. AA5052 aluminium alloy has wide potential window for electrochemical activity and better discharge performance in alkaline ethylene glycol solution containing dicarboxylic acid additives. ADA has the best inhibition effect for the self-corrosion of AA5052 anode among the three dicarboxylic acid additives. Fourier transform infrared spectroscopy (FT-IR) reveals that dicarboxylic acids and aluminium ions can form coordination complexes. Quantum chemical calculations shows that ADA has a smaller energy gap (ΔE, the energy difference between the lowest unoccupied orbital and the highest occupied orbital), indicating that ADA has the strongest interaction with aluminium ions.

  2. The Effect of Silane on the Microstructure, Corrosion, and Abrasion Resistances of the Anodic Films on Ti Alloy

    NASA Astrophysics Data System (ADS)

    Wang, Jinwei; Chen, Jiali

    2016-04-01

    Anodic oxide films on Ti-6Al-4V alloy are prepared using sodium hydroxide as the base electrolyte containing aminopropyl trimethoxysilane (APS) as an additive. Some APS undergo hydrolysis, adsorption, and chemical reaction with the TiO x to form Ti-O-Si bond as confirmed by ATR-FTIR and XPS spectra, and in turn their surface appearance and roughness are greatly changed with the addition of APS as observed by their SEM images. These amino anodic films possess much higher corrosive resistances since the formation of Ti-O-Si complex enhances the compactness of the anodic films and the existence of aminopropyl groups inside the pores provides additional blocking effects. Besides, their improvement in anti-abrasive capability is attributed to the toughening effect of the chemically bonded silanes and the lubrication functions from both the chemically bonded and physically absorbed silanes between the touched interfaces.

  3. A 3D porous Ni-Cu alloy film for high-performance hydrazine electrooxidation

    NASA Astrophysics Data System (ADS)

    Sun, Ming; Lu, Zhiyi; Luo, Liang; Chang, Zheng; Sun, Xiaoming

    2016-01-01

    Structural design and catalyst screening are two most important factors for achieving exceptional electrocatalytic performance. Herein we demonstrate that constructing a three-dimensional (3D) porous Ni-Cu alloy film is greatly beneficial for improving the hydrazine oxidation reaction (HzOR) performance. A facile electrodeposition process is employed to synthesize a Ni-Cu alloy film with a 3D hierarchical porous structure. As an integrated electrode for HzOR, the Ni-Cu alloy film exhibits superior catalytic activity and stability to the Ni or Cu counterparts. The synthesis parameters are also systematically tuned for optimizing the HzOR performance. The excellent HzOR performance of the Ni-Cu alloy film is attributed to its high intrinsic activity, large electrochemical specific surface area, and 3D porous architecture which offers a ``superaerophobic'' surface to effectively remove the gas product in a small volume. It is believed that the Ni-Cu alloy film electrode has potential application in direct hydrazine fuel cells as well as other catalytic fields.Structural design and catalyst screening are two most important factors for achieving exceptional electrocatalytic performance. Herein we demonstrate that constructing a three-dimensional (3D) porous Ni-Cu alloy film is greatly beneficial for improving the hydrazine oxidation reaction (HzOR) performance. A facile electrodeposition process is employed to synthesize a Ni-Cu alloy film with a 3D hierarchical porous structure. As an integrated electrode for HzOR, the Ni-Cu alloy film exhibits superior catalytic activity and stability to the Ni or Cu counterparts. The synthesis parameters are also systematically tuned for optimizing the HzOR performance. The excellent HzOR performance of the Ni-Cu alloy film is attributed to its high intrinsic activity, large electrochemical specific surface area, and 3D porous architecture which offers a ``superaerophobic'' surface to effectively remove the gas product in a small

  4. The susceptibility of 90Cu-10Ni alloy to stress corrosion cracking in seawater polluted by sulfide ions

    NASA Astrophysics Data System (ADS)

    Domiaty, A. El; Alhajji, J. N.

    1997-08-01

    Electrochemical polarization measurements and slow strain rate tests (SSRT) of a 90Cu-10Ni alloy in highly sulfide polluted seawater were conducted to investigate stress-corrosion cracking (SCC) behavior. The severity of the SCC depends on the sulfide concentration in the seawater. The severity increases as the concentration increases. Because the major time in SCC is spent in the initiation process of the propagating crack, the fracture toughness has only a minor effect in the component life failed by SCC. The SCC behavior of CDA706 is strictly linked to sulfide concentration in the range of 100 to 1000 ppm. The general corrosion of Cu-Ni alloys in low (<100 ppm) and high (>100 ppm) sulfide polluted seawater increases due to the selective copper dissolution. Cyclic polarization measurements confirmed that the corrosion rate decreases slightly as the sulfide concentration increases. Pitting tendency was high in the low concentration range of sulfide and low in the high concentration range. The presence of stresses in SCC removes the protective layer as it increases during testing of the specimen or during the actual service of a component. The authors propose that film rupture occurred, and two proposed SCC mechanisms were operational, namely sulfide stress cracking associated with the anodic dissolution in the low sulfide concentration range and hydrogen embrittlement, which was dominant in the high sulfide concentration range. It was found that a synergism exists between sulfide and stress that enhances the effect of the latter.

  5. Crystallization Kinetics and Phase Transformation Mechanisms in Cu56Zr44 Glassy Alloy

    NASA Astrophysics Data System (ADS)

    Kalay, Ilkay; Kramer, Matthew J.; Napolitano, Ralph E.

    2015-08-01

    The kinetics and phase selection mechanisms involved in the crystallization of an amorphous Cu-Zr alloy of eutectic composition (Cu56Zr44) were investigated using in situ high-energy X-ray diffraction (HEXRD), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC) under isothermal and constant heating rate conditions. In situ HEXRD results for 10 K/min (10 °C/min) heating indicate that the amorphous alloy devitrifies into CuZr2 and mainly Cu10Zr7 at the crystallization temperature of 725 K (452 °C). The sequence continues with the precipitation of CuZr (B2) at 1004 K (731 °C), where these three phases coexist until the decomposition of CuZr2 is observed at 1030 K (757 °C). The two equilibrium phases Cu10Zr7 and CuZr (B2) remain present on further heating until melting at the eutectic temperature for the Cu56Zr44 alloy. TEM investigation of the isothermal [705 K (432 °C)] crystallization sequence reveals primary nucleation and growth of the Cu10Zr7 phase, where growth of the Cu10Zr7 crystals is initially planar with a transition to a cellular morphology, associated with partitioning of Zr at the growth front. Related cellular structures and composition profiles are quantified.

  6. Saturation magnetization in supersaturated solid solution of Co-Cu alloy

    NASA Astrophysics Data System (ADS)

    Yuasa, Motohiro; Kajikawa, Kota; Hakamada, Masataka; Mabuchi, Mamoru

    2009-10-01

    The magnetovolume effect has been investigated using a supersaturated solid solution of a Co-19 at. %Cu alloy processed by electrodeposition. The enhanced saturation magnetization of the Co-Cu alloy was attributed to both metastable fcc Co and lattice expansion. The density functional theory using the CASTEP code revealed that an enhanced magnetic moment due to the magnetovolume effect is obtained in fcc Co, but not in hcp Co.

  7. Morphology Evolution on the Fracture Surface and Fracture Mechanisms of Multiphase Nanostructured ZrCu-Base Alloys.

    PubMed

    Qiu, Feng; Zhu, Lin; Zou, Qian; Wang, Lei; Han, Xue; Li, Qiang; Jiang, Qi-Chuan

    2017-03-13

    A multiphase nanostructured ZrCu-base bulk alloy which showed a unique microstructure consisting of sub-micrometer scale Zr₂Cu solid solution, nano-sized twinned plate-like ZrCu martensite (ZrCu (M)), and retained ZrCu (B2) austenite was fabricated by copper mold casting. The observation of periodic morphology evolution on the fracture surface of the multiphase nanostructured ZrCu-base alloys has been reported, which suggested a fluctuant local stress intensity along the crack propagation. It is necessary to investigate the compressive deformation behavior and the fracture mechanism of the multiphase alloy and the relation to the unique microstructures. The results obtained in this study provide a better understanding of the deformation and fracture mechanisms of multiphase hybrid nanostructured ZrCu-based alloys and give guidance on how to improve the ductility/toughness of bulk ZrCu-based alloys.

  8. Stress/strain characteristics of Cu-alloy sheath MgB 2 superconducting wires

    NASA Astrophysics Data System (ADS)

    Katagiri, Kazumune; Kasaba, Koichi; Shoji, Yoshitaka; Yamakage, Daisuke; Obara, Takeshi; Shimura, Satoshi; Koshizuka, Naoki; Watanabe, Kazuo

    2007-04-01

    The mechanical properties of Cu and Cu-alloy (Cu-Zr, Cu-Be and Cu-Cr) sheath in situ PIT-processed MgB 2 superconducting wires were studied at room temperature (RT) and 4.2 K. The effects of stress/strain on the critical current ( Ic) of the wires have also been studied at 4.2 K and in magnetic fields up to 5 T. Alloying the Cu sheath significantly increased the yield stress of the wires. The 0.5% flow stresses of the Cu-alloy sheath wires were 147-237 MPa, whereas that of Cu was 55 MPa. At RT, the serration in the stress-strain curves corresponding to the multiple cracking was observed around a strain of 0.4% and the curve almost saturated beyond that point. The strain dependence of Ic prior to the critical strain ( ɛirr) was different depending on the magnetic field; being almost constant at 2 T and increased with strain at 5 T. The Ic decreased beyond ɛirr, which was much larger for Cu-alloy sheath wires as compared with Cu sheath wire. The magnitude of ɛirr is due to the difference in the thermal compressive strain in the MgB 2 core, which was relaxed by yielding in the sheath materials. The transverse compression tests revealed that the Ic of the Cu-alloy sheath wire did not degrade up to about 95 MPa, which is also higher than that of Cu sheath wire.

  9. CuCrZr alloy microstructure and mechanical properties after hot isostatic pressing bonding cycles

    NASA Astrophysics Data System (ADS)

    Frayssines, P.-E.; Gentzbittel, J.-M.; Guilloud, A.; Bucci, P.; Soreau, T.; Francois, N.; Primaux, F.; Heikkinen, S.; Zacchia, F.; Eaton, R.; Barabash, V.; Mitteau, R.

    2014-04-01

    ITER first wall (FW) panels are a layered structure made of the three following materials: 316L(N) austenitic stainless steel, CuCrZr alloy and beryllium. Two hot isostatic pressing (HIP) cycles are included in the reference fabrication route to bond these materials together for the normal heat flux design supplied by the European Union (EU). This reference fabrication route ensures sufficiently good mechanical properties for the materials and joints, which fulfil the ITER mechanical specifications, but often results in a coarse grain size for the CuCrZr alloy, which is not favourable, especially, for the thermal creep properties of the FW panels. To limit the abnormal grain growth of CuCrZr and make the ITER FW fabrication route more reliable, a study began in 2010 in the EU in the frame of an ITER task agreement. Two material fabrication approaches have been investigated. The first one was dedicated to the fabrication of solid CuCrZr alloy in close collaboration with an industrial copper alloys manufacturer. The second approach investigated was the manufacturing of CuCrZr alloy using the powder metallurgy (PM) route and HIP consolidation. This paper presents the main mechanical and microstructural results associated with the two CuCrZr approaches mentioned above. The mechanical properties of solid CuCrZr, PM CuCrZr and joints (solid CuCrZr/solid CuCrZr and solid CuCrZr/316L(N) and PM CuCrZr/316L(N)) are also presented.

  10. Research of Mechanical Property Gradient Distribution of Al-Cu Alloy in Centrifugal Casting

    NASA Astrophysics Data System (ADS)

    Sun, Zhi; Sui, Yanwei; Liu, Aihui; Li, Bangsheng; Guo, Jingjie

    Al-Cu alloy castings are obtained using centrifugal casting. The regularity of mechanical property gradient distribution of Al-Cu alloy castings with the same centrifugal radius at different positions is investigated. The result shows that the tensile strength, yield strength, elongation and microscope hardness exhibit the following gradient distribution characteristic — high on both sides and low on the center. The trend of mechanical property gradient distribution of Al-Cu alloy increases with the increase in the rotation speed. Moreover, the mechanical properties of casting centerline two sides have asymmetry. The reason is that the grain size of casting centerline two sides and Al2Cu phase and Cu content change correspondingly.

  11. 25th anniversary article: Understanding the lithiation of silicon and other alloying anodes for lithium-ion batteries.

    PubMed

    McDowell, Matthew T; Lee, Seok Woo; Nix, William D; Cui, Yi

    2013-09-25

    Alloying anodes such as silicon are promising electrode materials for next-generation high energy density lithium-ion batteries because of their ability to reversibly incorporate a high concentration of Li atoms. However, alloying anodes usually exhibit a short cycle life due to the extreme volumetric and structural changes that occur during lithium insertion/extraction; these transformations cause mechanical fracture and exacerbate side reactions. To solve these problems, there has recently been significant attention devoted to creating silicon nanostructures that can accommodate the lithiation-induced strain and thus exhibit high Coulombic efficiency and long cycle life. In parallel, many experiments and simulations have been conducted in an effort to understand the details of volumetric expansion, fracture, mechanical stress evolution, and structural changes in silicon nanostructures. The fundamental materials knowledge gained from these studies has provided guidance for designing optimized Si electrode structures and has also shed light on the factors that control large-volume change solid-state reactions. In this paper, we review various fundamental studies that have been conducted to understand structural and volumetric changes, stress evolution, mechanical properties, and fracture behavior of nanostructured Si anodes for lithium-ion batteries and compare the reaction process of Si to other novel anode materials.

  12. Superplastic formability of Al-Cu-Li alloy Weldalite (TM) 049

    NASA Technical Reports Server (NTRS)

    Ma, Bao-Tong; Pickens, Joseph R.

    1991-01-01

    Extensive research during the past decade shows that several aluminum lithium alloys can be processed to attain a microstructure that enables superplasticity. The high tensile stress of Al-Cu-Li alloy Weldalite (TM) 049 in the T4 and T6 tempers offers tremendous potential for attaining exceptional post-SPF (superplastic formability) properties. The used SPF material is Weldalite, which was shown to induce SPF behavior in other Al-Cu-Li alloys. The superplastic behavior and resulting post-SPF mechanical properties of this alloy, which was designed to be the next major structural alloy for space applications, were evaluated. The results indicate that Weldalite alloy does indeed exhibit excellent superplasticity over a wide range of temperatures and strain rates and excellent post-SPF tensile strength at various potential service temperatures.

  13. The effect of thin film morphology on the electrochemical performance of Cu-Sn anode for lithium rechargeable batteries.

    PubMed

    Polat, B D; Keleş, O

    2014-05-01

    We investigate the anode performance of non ordered and ordered nanostructured Cu-Sn thin films deposited via electron beam deposition technique. The ordered nanostructured Cu-Sn thin film having nano-porosities was fabricated using an oblique (co)deposition technique. Our results showed that the nano structured Cu-Sn thin film containing Cu-Sn nanorods had higher initial anodic capacity (790 mA h g(-)) than that of the non ordered thin film (330 mA h g(-)). But the capacity of the ordered nanostructured Cu-Sn thin film diminished after the first cycle and a steady state capacity value around 300 mA h g(-) is sustainable in following up to 80th cycle, which is attributed to the composition and morphology of the thin film. The presence of copper containing Sn nanorods leading to form nano-porosities as interstitial spaces among them, enhanced lithium ions movement within thin film and increased the thin film tolerance against the stress generated because of the drastic volume change occurred during lithiation-delithiation processes; hence, homogenously distributed porosities increased the cycle life of the thin film.

  14. Preparation of Advanced CuO Nanowires/Functionalized Graphene Composite Anode Material for Lithium Ion Batteries

    PubMed Central

    Zhang, Jin; Wang, Beibei; Zhou, Jiachen; Xia, Ruoyu; Chu, Yingli; Huang, Jia

    2017-01-01

    The copper oxide (CuO) nanowires/functionalized graphene (f-graphene) composite material was successfully composed by a one-pot synthesis method. The f-graphene synthesized through the Birch reduction chemistry method was modified with functional group “–(CH2)5COOH”, and the CuO nanowires (NWs) were well dispersed in the f-graphene sheets. When used as anode materials in lithium-ion batteries, the composite exhibited good cyclic stability and decent specific capacity of 677 mA·h·g−1 after 50 cycles. CuO NWs can enhance the lithium-ion storage of the composites while the f-graphene effectively resists the volume expansion of the CuO NWs during the galvanostatic charge/discharge cyclic process, and provide a conductive paths for charge transportation. The good electrochemical performance of the synthesized CuO/f-graphene composite suggests great potential of the composite materials for lithium-ion batteries anodes. PMID:28772432

  15. Corrosion and runoff rates of Cu and three Cu-alloys in marine environments with increasing chloride deposition rate.

    PubMed

    Odnevall Wallinder, Inger; Zhang, Xian; Goidanich, Sara; Le Bozec, Nathalie; Herting, Gunilla; Leygraf, Christofer

    2014-02-15

    Bare copper sheet and three commercial Cu-based alloys, Cu15Zn, Cu4Sn and Cu5Al5Zn, have been exposed to four test sites in Brest, France, with strongly varying chloride deposition rates. The corrosion rates of all four materials decrease continuously with distance from the coast, i.e. with decreasing chloride load, and in the following order: Cu4Sn>Cu sheet>Cu15Zn>Cu5Al5Zn. The patina on all materials was composed of two main layers, Cu2O as the inner layer and Cu2(OH)3Cl as the outer layer, and with a discontinuous presence of CuCl in between. Additional minor patina constituents are SnO2 (Cu4Sn), Zn5(OH)6(CO3)2 (Cu15Zn and Cu5Al5Zn) and Zn6Al2(OH)16CO3·4H2O/Zn2Al(OH)6Cl·2H2O/Zn5Cl2(OH)8·H2O and Al2O3 (Cu5Al5Zn). The observed Zn- and Zn/Al-containing corrosion products might be important factors for the lower sensitivity of Cu15Zn and Cu5Al5Zn against chloride-induced atmospheric corrosion compared with Cu sheet and Cu4Sn. Decreasing corrosion rates with exposure time were observed for all materials and chloride loads and attributed to an improved adherence with time of the outer patina to the underlying inner oxide. Flaking of the outer patina layer was mainly observed on Cu4Sn and Cu sheet and associated with the gradual transformation of CuCl to Cu2(OH)3Cl of larger volume. After three years only Cu5Al5Zn remains lustrous because of a patina compared with the other materials that appeared brownish-reddish. Significantly lower release rates of metals compared with corresponding corrosion rates were observed for all materials. Very similar release rates of copper from all four materials were observed during the fifth year of marine exposure due to an outer surface patina that with time revealed similar constituents and solubility properties.

  16. Optimization of square wave anodic stripping voltammetry (SWASV) for the simultaneous determination of Cd, Pb, and Cu in seawater and comparison with differential pulse anodic stripping voltammetry (DPASV).

    PubMed

    Truzzi, Cristina; Lambertucci, Luca; Gambini, Gloria; Scarponi, Giuseppe

    2002-03-01

    Square wave anodic stripping voltammetry (SWASV) was optimized for the simultaneous determination of Cd, Pb and Cu in coastal seawater samples. Background subtraction was adapted to improve peak detection and quantification. Optimum background voltammograms were obtained by applying a 7.5 s equilibration potential at -975 mV (vs. Ag/AgCl, 3M KCl) before starting the background scan. Voltammetric scan parameters were optimized to obtain maximum sensitivity while retaining good peak resolution and discrimination from background. Optimal parameters were: frequency 100 Hz, pulse amplitude 25 mV, current sampling delay time 2 ms, step height 8 mV. The sensitivity of optimized SWASV proved to be more than double that of differential pulse anodic stripping voltammetry (DPASV), and analysis time was halved. Samples containing around 13 (Cd), 30 (Pb), 200 (Cu) ng/l (typical averages of the coastal area of the Marche region) can be analyzed using a 5 min deposition time and the total analysis time using three standard additions is about 1 h and half, excluding the mercury film preparation and the outgassing of the sample, which can be made in parallel using a second cell cup.

  17. The effects of anodic interlayer on the morphology and mechanical performances of electroless Ni-P coating on Al alloy

    NASA Astrophysics Data System (ADS)

    Wang, Jinwei; Wu, Qiang

    2017-06-01

    We fabricate anodic film on Al alloy and deposit Ni-P coatings on the porous surface by electroless plating (EP) technique in comparison with those deposited directly on Al alloy. When Ni-P particles are directly deposited on the surface of Al alloy, a thicker film made by particles with bigger grain sizes is observed by SEM images, and the atom diffusions between their contacting interfaces may lead to the formation of loosely packed interlayer with thickness of around 4 μ as determined by EDS results. The porous anodic surface refines the size of Ni-P particles to form more compact Ni-P coating with smaller grain size and narrower size distributions; it also promotes particles embedding in the pores to form `interlock' transient layer with depth of around 1 μ. Thus, the rougher surface and the interlocking function provided by the porous anodic surface enhance the compactness and stability of the composite coating, which in turn result in the great improvements in its microhardness and adhesion performances.

  18. Study on the thermal storage properties of Al-Si-Cu-Mg alloy

    NASA Astrophysics Data System (ADS)

    XIE, Yi; WAN, Ke-yang; XIE, Guo-sheng; HU, Jia-rui; YIN, Fu-cheng; GONG, Jing

    2017-04-01

    Based on thermodynamic calculation technology, the thermodynamic data of six alloys (inc. Al-Si and Al-Si-Cu-Mg systems) was calculated. The microstructure, phase transformation temperature and latent heat of the Al-4%Cu-12%Mg-7%Si alloy and Al-13%Si alloy were also verified by X-ray diffraction(XRD), scanning electron microscopy/Energy-dispersive system (SEM/EDS) and Differential scanning calorimetry (DSC). The results show that The enthalpy change value of Al-Si-Cu-Mg alloy is larger than that of Al-Si alloy from 800 °C to 400 °C, while its phase transformation temperature is lower. In particular, the enthalpy value of Al-4%Cu-12%Mg-7%Si alloy is 85% higher than that of Al-13%Si near eutectic alloy, and its initial temperature of phase transformation is about 74 °C lower. The former has relatively low phase transformation temperature and over-dimensioned latent heat of phase transformation, displaying the excellent thermal storage property. Therefore, the alloy is a good potential solar energy thermal storage material. The results in the paper also indicated that thermodynamic calculation is of value in seeking new potential solar energy thermal storage materials for solar thermal power generation system.

  19. X-ray imaging and controlled solidification of Al-Cu alloys toward microstructures by design

    SciTech Connect

    Clarke, Amy J.; Tourret, Damien; Imhoff, Seth D.; Gibbs, Paul J.; Fezzaa, Kamel; Cooley, Jason C.; Lee, Wah -Keat; Deriy, Alex; Patterson, Brian M.; Papin, Pallas A.; Clarke, Kester D.; Field, Robert D.; Smith, James L.

    2015-01-30

    X-ray imaging, which permits the microscopic visualization of metal alloy solidification dynamics, can be coupled with controlled solidification to create microstructures by design. In this study, this x-ray image shows a process-derived composite microstructure being made from a eutectic Al-17.1 at.%Cu alloy by successive solidification and remelting steps.

  20. Effect of Boron and Cerium on Corrosion Resistance of Cu -Fe -P Alloy

    NASA Astrophysics Data System (ADS)

    Zou, Jin; Lu, Lei; Lu, De-ping; Liu, Ke-Ming; Chen, Zhi-bao; Zhai, Qi-jie

    2016-03-01

    The effects of B and Ce on the corrosion resistance of Cu-0.22Fe-0.06P alloy were investigated by salt spray and electrochemical tests. The corrosion morphology was studied by scanning electron microscopy. The corrosion products were characterized by energy-dispersive x-ray spectroscopy and x-ray diffraction analysis. The impurity content was determined by inductively coupled plasma mass spectrometry. The conductivity was measured using an eddy current conductivity meter. The grains of Cu-0.22Fe-0.06P alloy were refined by the addition of B and Ce. The electrochemical corrosion process of alloy is retarded due to purification effect of B and Ce. After the addition of a trace amount of B, the corrosion resistance of the alloy decreased. The corrosion resistance of Cu-0.22Fe-0.06P-0.025B-0.05Ce was better than that of Cu-0.22Fe-0.06P-0.025B due to the fact that the purification effect of Ce is better than that of B. The main corrosion products of the Cu-Fe-P alloys in a NaCl solution are Cu2Cl(OH)3 and Cu2O. The addition of trace amounts of B and Ce did not change the components of the corrosion product.

  1. Constitutive Behavior and Modeling of Al-Cu Alloy Systems

    DTIC Science & Technology

    2013-05-01

    annealing to refine the grain structure. All alloys were melted from high purity components by induction heating, and casted into a steel mold. Alloys...summary of the tested alloys with their individual strengthening mechanisms and their processing procedure...containing Mg element were melted in an argon atmosphere to minimize oxidation . Precipitation hardenable alloys additionally aged at a low

  2. Increasing Wear Resistance of Titanium Alloys by Anode Plasma Electrolytic Saturation with Interstitial Elements

    NASA Astrophysics Data System (ADS)

    Belkin, P. N.; Kusmanov, S. A.; Dyakov, I. G.; Silkin, S. A.; Smirnov, A. A.

    2017-05-01

    In our previous studies, we have shown that anode plasma electrolytic saturation of titanium alloys with nitrogen and carbon can improve their tribological properties. Obtained structure containing oxide layer and solid solution of diffused element in titanium promotes the enhancement of running-in ability and the decrease in the wear rate in some special cases. In this paper, further investigations are reported regarding the tribological properties of alpha- and beta-titanium alloys in wear test against hardened steel (50 HRC) disk using pin-on-disk geometry and balls of Al2O3 (6.25 mm in diameter) or bearing steel (9.6 mm in diameter) with ball-on-plate one and normal load from 5 to 209 N. Reproducible results were obtained under testing samples treated by means of the plasma electrolytic nitriding (PEN) with the mechanical removal of the oxide layer. Friction coefficient of nitrided samples is 0.5-0.9 which is somewhat higher than that for untreated one (0.48-0.75) during dry sliding against Al2O3 ball. An increase in the sliding speed results in the polishing of nitrided samples and reduction of their wear rate by 60 times. This result is obtained for 5 min at 850 °C using PEN in electrolyte containing 5 wt.% ammonia and 10 wt.% ammonium chloride followed by quenching in solution. Optical microscope was employed to assist in the evaluation of the wear behavior. Sizes of wear tracks were measured by profilometer TR200.

  3. Cascade collapse of heavy-ion irradiated Cu-Ni alloys

    SciTech Connect

    Smalinskas, K.S.

    1988-01-01

    To evaluate the role of material properties on the probability of a displacement cascade collapsing to a vacancy dislocation loop, the alloy content in Cu-Ni has been varied over the complete composition range. Cu-90wt%Ni, Cu-80wt%Ni, Cu-60wt%Ni, Cu-40wt%Ni, Cu-20wt%Ni, and Cu-10wt%Ni were used in this investigation. The probability of vacancy loop formation in Cu-Ni alloys has been shown to vary with the concentration of Ni. Initially, the inclusion of Ni increases the defect yield but on further addition, the yield decreases to a value lower than that of Cu. The yield starts to decrease when the Ni content exceeds 40%. The maximum and average dislocation loop size also decreases with increasing Ni content. Thus the number of vacancies retained in loops is significantly lower in the high nickel alloys than in pure Cu; a ratio of 13:1 was obtained. There is good agreement between the yields and size distributions in the current data with those reported by Stathopoulos et al. The diverse effects that the addition of impurities have on the probability of forming a dislocation loop from a displacement cascade and the lack of sufficient systematic studies makes it impossible to determine the precise effect. It is likely that more than one mechanism is operative. 31 refs., 14 figs., 3 tabs.

  4. Corrosion properties of Ag-Au-Cu-Pd system alloys containing indium.

    PubMed

    Hattori, Masayuki; Tokizaki, Teruhiko; Matsumoto, Michihiko; Oda, Yutaka

    2010-01-01

    In this study, the corrosion resistance of Ag-Au-Cu-Pd system alloys consisting of 5 or 10 mass% indium was evaluated. Levels of element release and tarnish were determined and electrochemical measurements performed. Results were compared with those for commercial silver-palladium-gold alloy. In terms of electrochemical behavior, the transpassive potential of these experimental alloys was 168-248mV. Experimental alloys with 25 mass% Au showed similar corrosion resistance to control gold-silver-palladium alloy. Amount of released elements was 14-130microg/cm(2) at 7 days, which is in the allowable range for dental alloys. Addition of indium to Ag-Au-Cu-10mass%Pd system alloys was effective in increasing resistance to tarnish and alloys containing 10 mass% of indium showed a minimal decrease in L(*) values after immersion. These findings indicate that 25Au-37.5Ag-15Cu-10Pd-2Zn-10In-0.5Ir alloy is applicable in dental practice.

  5. Cermet anode with continuously dispersed alloy phase and process for making

    DOEpatents

    Marschman, Steven C.; Davis, Norman C.

    1989-01-01

    Cermet electrode compositions and methods for making are disclosed which comprise NiO--NiFe.sub.2 O.sub.4 --Cu--Ni. Addition of an effective amount of a metallic catalyst/reactant to a composition of a nickel/iron/oxide, NiO, copper, and nickel produces a stable electrode having significantly increased electrical conductivity. The metallic catalyst functions to disperse the copper and nickel as an alloy continuously throughout the oxide phase of the cermet to render the electrode compositon more highly electrically conductive than were the third metal not present in the base composition. The third metal is preferably added to the base composition as elemental metal and includes aluminum, magnesium, sodium and gallium. The elemental metal is converted to a metal oxide during the sintering process.

  6. Thermal Spraying of CuAlFe Powder on Cu5Sn Alloy

    NASA Astrophysics Data System (ADS)

    Roata, I. C.; Pascu, A.; Croitoru, C.; Stanciu, E. M.; Pop, M. A.

    2017-06-01

    To improve the corrosion and wear resistance of copper and its alloys, flame spraying has been employed to obtain a relatively homogenous Cu/Al/Fe-based coating. To minimize the defects that usually occur by using this method, a post-coating annealing step has been employed, by using concentrated solar energy as means of thermal surface treatment. Scanning electron micrographs have indicated a reduction in the cracks/pores density and accelerated corrosion testing have indicated a higher performance of the solar-annealed sample, in comparison with the initial reference material. The coating approach mentioned in this paper could be successfully applied to restore several worn tools and instruments, and could also be of use in the renewable energy field (IR-absorbent coatings) or in advanced oxidation processes, such as photocatalysis.

  7. Biocompatibility of antibacterial Ti-Cu sintered alloy: in vivo bone response.

    PubMed

    Bai, Bing; Zhang, Erlin; Dong, Hui; Liu, Jie

    2015-12-01

    Ti-10Cu sintered alloy has shown very strong in vitro and in vivo antibacterial property and in vitro cell compatibility. In this paper, Ti-10Cu implant (Ti-Cu group) and commercial pure Ti implant (cp-Ti group) were implanted in rabbit femurs to investigate in vivo bone response to the Ti-10Cu alloy. X-ray photo, fluorescent microscopy, routine pathological examination and immunohistochemistry have been used to analyze bone growth, mineral apposition rate (MAR), bone implant contact (BIC), BMP-2 expression and TGF-β1 expression. In both Ti-Cu and cp-Ti groups, new bone tissue was found at bone/implant interfaces 4 weeks postimplantation and completely filled the interfaces gap bone 12 weeks postimplantation. A significant MOD value in BMP-2 expression was observed at week 1 and week 4 in the Ti-Cu group with lower values of week 2 and 3 in both groups, which indicated strong positive activity. MOD value in TGF-β1 expression decreased with the extension of implantation. However, no difference can be found in MAR, BIC and TGF-β1 expression between the two groups at all intervals. It was deduced that Ti-Cu alloy exhibited as good bone response as cp-Ti. The good bone compatibility suggests that Ti-10Cu alloy might have potential application in orthopedic surgery and dental implant.

  8. Oxygen-induced Y surface segregation in a CuPdY ternary alloy

    SciTech Connect

    Tafen, D N.; Miller, J B.; Dogan, O N.; Baltrus, J P.; Kondratyuk, P

    2013-01-01

    We present a comprehensive theoretical and experimental study of the segregation behavior of the ternary alloy CuPdY in vacuum (i.e., the clean surface) and in the presence of oxygen. Theoretical prediction shows that for clean surface, yttrium will substitute first for Cu and then for Pd at the subsurface lattice site before segregating to the surface where it substitutes for Cu. XRD characterization of the surface of CuPdY indicates the presence of two major phases, B2 CuPd and Pd{sub 3}Y. In the presence of adsorbed oxygen, theory predicts that Y preferentially occupies surface sites due to its stronger oxygen affinity compared to Cu and Pd. XPS experiments confirm the computational results in the adsorbed oxygen case, showing that surface segregation of yttrium is induced by the formation of Y-oxides at the top-surface of the alloy.

  9. Effect of Thermomagnetic Treatment on Structure and Properties of Cu-Al-Mn Alloy

    NASA Astrophysics Data System (ADS)

    Titenko, A. N.; Demchenko, L. D.; Perekos, A. O.; Gerasimov, O. Yu

    2017-04-01

    The paper studies the influence of magnetic field on magnetic and mechanical properties of Cu-Mn-Al alloy under annealing. The comparative analysis of the magnetic field orientation impact on solid solution decomposition processes in a fixed annealing procedure is held using the methods of low-field magnetic susceptibility, specific magnetization, and microhardness test. The paper highlights changes in the magnetic and mechanical properties of Cu-Al-Mn alloy as the result of change in a critical size of forming precipitated ferromagnetic phase and determines correlation in the behavior of magnetic and mechanical properties of the alloy, depending on a critical nucleus size of forming precipitated ferromagnetic phase.

  10. The Effect of Cold Work on Martensitic Transformations in CU-ZN-AL Shape Memory Alloys.

    DTIC Science & Technology

    1983-12-01

    has been reported to occur in many binary and ternary systems including: Ni-Ti ( Nitinol ), Fe-Pt, Mn-Cu, In-Tl, Cu-Zn, Cu-Zn-Sn, Cu-Ni-Al and Cu-Zn-Al...describe several different kinds of alloy behavior. To avoid confusion, a brief review of terminology follows [Refs. 12-14]. Shape memory (SM), also known...data follows: 1.) brief review and summary of the structural and " , .~substructural conditions prevailing in the as received and as homogenized

  11. Dynamics of domain walls in Ti-Ni-Cu alloy

    NASA Astrophysics Data System (ADS)

    Liang, X. L.; Zhang, Z. F.; Liu, Q.; Shen, H. M.; Wang, Y. N.; Shi, P.; Chen, F. X.; Yang, D. Z.

    1999-12-01

    The internal friction for Ti-Ni-Cu shape memory alloys (SMAs) was measured in the Hz and kHz range. The peak temperature in the Hz range is independent of the measuring frequencies. Only in the tens of kHz range does the peak temperature shift with the frequencies, showing a thermally activated progress with icons/Journals/Common/tau" ALT="tau" ALIGN="TOP"/> = icons/Journals/Common/tau" ALT="tau" ALIGN="TOP"/>0e-B/Tc - T, characteristic of viscous motion of domain walls, instead of the Arrhenius relation. Taking into account the change of the density of the domain walls during the phase transformation, we modified the Q-1-formula by using a model of viscous motion of domain walls, obtaining a good result in agreement with the experimental data. Additionally, corresponding parameters, which play a key role in the shape memory effect, such as the viscosity coefficient and the effective pinning force constant, were obtained.

  12. Research on a Zn-Cu alloy as a biodegradable material for potential vascular stents application.

    PubMed

    Niu, Jialin; Tang, Zibo; Huang, Hua; Pei, Jia; Zhang, Hua; Yuan, Guangyin; Ding, Wenjiang

    2016-12-01

    Zn-based alloys have been viewed as new potential materials for biodegradable implants, such as cardiovascular stents, mainly in consideration of their lower corrosion rate when compared with that of Mg alloys. In this study we developed a new Zinc-4wt.%Copper (Zn-4Cu) alloy as a biodegradable material. Hot extrusion was applied to Zn-4Cu to refine the microstructure and consequently improve its mechanical properties and corrosion resistance. After extrusion, dendritic CuZn5 phases were broken and distributed along the extrusion direction. The grains were refined obviously due to dynamical recrystallization. The yield strength (YS), ultimate tensile strength (UTS) and elongation of the as-extruded alloy are 250±10MPa, 270±10MPa and 51±2%, respectively. The corrosion rate of the as-extruded alloy in Hank's solution is about 9.41(±1.34)μmyear(-1). In vitro evaluation shows that Zn-4Cu presents acceptable toxicity to human endothelial cells, and could effectively inhibit bacteria adhesion and biofilm formation. The present study indicates that the as-extruded Zn-4Cu alloy exhibits excellent strength and ductility, uniform and slow degradation, good biocompatibility and significant antibacterial effect, which make it an excellent candidate material for biodegradable implants, especially for cardiovascular stents application.

  13. Biocorrosion properties of antibacterial Ti-10Cu sintered alloy in several simulated biological solutions.

    PubMed

    Liu, Cong; Zhang, Erlin

    2015-03-01

    Ti-10Cu sintered alloy has shown strong antibacterial properties against S. aureus and E. coli and good cell biocompatibility, which displays potential application in dental application. The corrosion behaviors of the alloy in five different simulated biological solutions have been investigated by electrochemical technology, surface observation, roughness measurement and immersion test. Five different simulated solutions were chosen to simulate oral condition, oral condition with F(-) ion, human body fluids with different pH values and blood system. It has been shown that Ti-10Cu alloy exhibits high corrosion rate in Saliva pH 3.5 solution and Saliva pH 6.8 + 0.2F solution but low corrosion rate in Hank's, Tyrode's and Saliva pH 6.8 solutions. The corrosion rate of Ti-10Cu alloy was in a order of Hank's, Tyrode's, Saliva pH 6.8, Saliva-pH 3.5 and Saliva pH 6.8 + 0.2F from slow to fast. All results indicated acid and F(-) containing conditions prompt the corrosion reaction of Ti-Cu alloy. It was suggested that the Cu ion release in the biological environments, especially in the acid and F(-) containing condition would lead to high antibacterial properties without any cell toxicity, displaying wide potential application of this alloy.

  14. Microstructural changes to AlCu6Ni1 alloy after prolonged annealing at elevated temperature.

    PubMed

    Wierzbińska, M; Sieniawski, J

    2010-03-01

    This work presents results of microstructure examination of AlCu(6)Ni(1) aluminium alloy. The commercial AlCu(4)Ni(2)Mg(2) (M-309) alloy is widely used for elements of aircraft and automotive engines. Modification its chemical composition was aimed at improving the stability of mechanical properties of the alloy subjected to long-term exposure to high temperature. The alloy after standard T6 heat treatment (solution heat treated at 818 K/10 h/water quenched followed by ageing at 498 K/8 h/air cooled) was annealed for 150 h at elevated temperature of 573 K corresponding to the maximum value at which structural elements of jet piston engines made of aluminium alloys operate. It was found that applied heat treatment caused an increasing in the particles of hardening phase (theta'-Al(2)Cu) size. The significant growth of the length of theta'-Al(2)Cu precipitations was observed in particularly. Nevertheless, it did not strongly result in change of its shape - the 'crystallites' and 'rods' were still characteristic of hardening phase morphology. The phenomena of the growth of theta'-Al(2)Cu precipitates caused decreasing the mechanical properties of the alloy, what is the subject of further investigations by the authors.

  15. Properties of amalgams made from lathe-cut, high Cu amalgam alloys.

    PubMed

    Espevik, S

    1980-01-01

    Two alloys for dental amalgams made from lathe-cut powder with high Cu content have been developed. The alloys have been characterized with respect to physical properties and microstructure. The strongest amalgam exhibited minimal dimensional changes during setting and had low flow and creep values. It had the highest Cu content of the two amalgams investigated and no gamma 2 phase. The epsilon and eta' phases may dispersion-strenthen the amalgam which in compressive strength was comparable to the strongest amalgams available. A new mechanism for gamma 2 disappearance is suggested where Cu replaces Hg directly in the gamma 2 phase thus forming the eta' phase.

  16. Structural and magnetic properties of mechanically alloyed Co 20Cu 80 solid solution

    NASA Astrophysics Data System (ADS)

    Yoo, Y. G.; Yang, D. S.; Yu, S. C.; Kim, W. T.; M. Lee, J.

    1999-08-01

    Microstructural change during the mechanical alloying of Co 20Cu 80 has been studied by X-ray diffractometry (XRD) and extended X-ray absorption fine structure (EXAFS) techniques. EXAFS analysis shows clearly the formation of supersaturated Co 20Cu 80 solid solution with FCC crystal structure during mechanical alloying, which is in good agreement with XRD analysis. Magnetic properties also have been studied by SQUID magnetometer from 4 to 290 K. The supersaturated Co 20Cu 80 solid solution shows wide distribution in Co cluster size due to the continuous blocking of Co cluster as a function of temperature.

  17. Solid-Solution Alloying of Immiscible Ru and Cu with Enhanced CO Oxidation Activity.

    PubMed

    Huang, Bo; Kobayashi, Hirokazu; Yamamoto, Tomokazu; Matsumura, Syo; Nishida, Yoshihide; Sato, Katsutoshi; Nagaoka, Katsutoshi; Kawaguchi, Shogo; Kubota, Yoshiki; Kitagawa, Hiroshi

    2017-03-24

    We report on novel solid-solution alloy nanoparticles (NPs) of Ru and Cu that are completely immiscible even above melting point in bulk phase. Powder X-ray diffraction, scanning transmission electron microscopy, and energy-dispersive X-ray measurements demonstrated that Ru and Cu atoms were homogeneously distributed in the alloy NPs. Ru0.5Cu0.5 NPs demonstrated higher CO oxidation activity than fcc-Ru NPs, which are known as one of the best monometallic CO oxidation catalysts.

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

    PubMed

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

    2016-12-01

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

  19. Microstructural, mechanical, and electrical characterization of directionally solidified Al-Cu-Mg eutectic alloy

    NASA Astrophysics Data System (ADS)

    Kaygısız, Yusuf; Maraşlı, Necmettin

    2017-04-01

    The composition of an Al-Cu-Mg ternary eutectic alloy was chosen to be Al-30 wt% Cu-6 wt % Mg to have the Al2Cu and Al2CuMg solid phases within an aluminum matrix (α-Al) after its solidification from the melt. The alloy Al-30 wt % Cu-6 wt % Mg was directionally solidified at a constant temperature gradient ( G = 8.55 K/mm) with different growth rates V, from 9.43 to 173.3 μm/s, by using a Bridgman-type furnace. The lamellar eutectic spacings (λE) were measured from transverse sections of the samples. The functional dependencies of lamellar spacings λE ({λ _{A{l_2}CuMg}} and {λ _{A{l_2}Cu}} in μm), microhardness H V (in kg/mm2), tensile strength σT (in MPa), and electrical resistivity ρ (in Ω m) on the growth rate V (in μm/s) were obtained as {λ _{A{l_2}CuMg}} = 3.05{V^{ - 0.31}}, {λ _{A{l_2}Cu}} = 6.35{V^{ - 0.35}}, {H_V} = 308.3{( V )^{ - 0.33}}; σT= 408.6( V)0.14, and ρ = 28.82 × 10-8( V)0.11, respectively for the Al-Cu-Mg eutectic alloy. The bulk growth rates were determined as λ _{A{l_2}CuMg}^2V = 93.2 and λ _{A{l_2}Cu}^2V = 195.76 by using the measured values of {λ _{A{l_2}CuMg}}, {λ _{A{l_2}Cu}} and V. A comparison of present results was also made with the previous similar experimental results.

  20. Utilizing various test methods to study the stress corrosion behavior of Al-Li-Cu alloys

    NASA Technical Reports Server (NTRS)

    Pizzo, P. P.; Galvin, R. P.; Nelson, H. G.

    1984-01-01

    Recently, much attention has been given to aluminum-lithium alloys because of rather substantial specific-strength and specific-stiffness advantages offered over commercial 2000and 7000-series aluminum alloys. An obstacle to Al-Li alloy development has been inherent limited ductility. In order to obtain a more refined microstructure, powder metallurgy (P/M) has been employed in alloy development programs. As stress corrosion (SC) of high-strength aluminum alloys has been a major problem in the aircraft industry, the possibility of an employment of Al-Li alloys has been considered, taking into account a use of Al-Li-Cu alloys. Attention is given to a research program concerned with the evaluation of the relative SC resistance of two P/M processed Al-Li-Cu alloys. The behavior of the alloys, with and without an addition of magnesium, was studied with the aid of three test methods. The susceptibility to SC was found to depend on the microstructure of the alloys.

  1. Utilizing various test methods to study the stress corrosion behavior of Al-Li-Cu alloys

    NASA Technical Reports Server (NTRS)

    Pizzo, P. P.; Galvin, R. P.; Nelson, H. G.

    1984-01-01

    Recently, much attention has been given to aluminum-lithium alloys because of rather substantial specific-strength and specific-stiffness advantages offered over commercial 2000and 7000-series aluminum alloys. An obstacle to Al-Li alloy development has been inherent limited ductility. In order to obtain a more refined microstructure, powder metallurgy (P/M) has been employed in alloy development programs. As stress corrosion (SC) of high-strength aluminum alloys has been a major problem in the aircraft industry, the possibility of an employment of Al-Li alloys has been considered, taking into account a use of Al-Li-Cu alloys. Attention is given to a research program concerned with the evaluation of the relative SC resistance of two P/M processed Al-Li-Cu alloys. The behavior of the alloys, with and without an addition of magnesium, was studied with the aid of three test methods. The susceptibility to SC was found to depend on the microstructure of the alloys.

  2. Recovery of Industrial and Recycled Al-Cu Alloys Subjected to Severe Plastic Deformation

    NASA Astrophysics Data System (ADS)

    Rekik, M. A.; Kassis, K.; Masmoudi, J.; Zghal, S.; Champion, Y.; Njah, N.

    2009-11-01

    Equal channel angular pressing (ECAP) is a well-known method to obtain high hardness levels through a strong refinement of grains. To obtain fine grains, a subsequent heating is performed after deformation. The main difficulty is to retain a sufficiently small grain size. Alloy purity is an important parameter in recristallization kinetics. In the present work, an industrial and a recycled Al-4%Cu alloys were subjected to ECAP. The evolution of the microstructure of the deformed and annealed alloys was investigated. The alloys exhibit different hardness values for a given equivalent deformation. In industrial alloy, no recovery was observed at low temperatures. On the other hand, enhanced precipitation in this alloy leads to an increase in hardness balancing then softening due to recovery. A substantial decrease in hardness is observed around 250 ∘C and seems to depend on alloy purity.

  3. New Fe-Co-Ni-Cu-Al-Ti Alloy for Single-Crystal Permanent Magnets

    NASA Astrophysics Data System (ADS)

    Belyaev, I. V.; Bazhenov, V. E.; Moiseev, A. V.; Kireev, A. V.

    2016-03-01

    A new alloy intended for single-crystal permanent magnets has been suggested. The new alloy has been designed based on the well-known Fe-Co-Ni-Cu-Al-Ti system and contains to 1 wt % Hf. The alloy demonstrates an enhanced potential ability for single-crystal forming in the course of unidirectional solidification of ingot. Single-crystal permanent magnets manufactured from this alloy are characterized by a high level of magnetic properties. When designing the new alloy, computer simulation of the phase composition and calculations of solidification parameters of complex metallic systems have been performed using the Thermo-Calc software and calculation and experimental procedures based on quantitative metallographic analysis of quenched structures. After the corresponding heat treatment, the content of high-magnetic phase in the alloy is 10% higher than that in available analogous alloys.

  4. Surface phenomena of hydroxyapatite film on the nanopore formed Ti-29Nb-xZr alloy by anodization for bioimplants.

    PubMed

    Kim, Eun-Ju; Jeong, Yong-Hoon; Choe, Han-Cheol

    2013-03-01

    In this study, surface phenomena of hydroxyapatite (HA) film on the nanopore formed Ti-29Nb-xZr alloy by anodization for bioimplants have been investigated by electron beam physical vapor deposition (EB-PVD), field emission scanning electron microscope (FE-SEM), X-ray diffractometer (XRD), potentiostat and contact angle. The microstructure of Ti-29Nb-xZr alloys exhibited equiaxed structure and alpha" phase decreased, whereas beta phase increased as Zr content increased. The increment of Zr contents in HA coated nanotubular Ti-29Nb-xZr alloys showed good corrosion potential in 0.9% NaCI solution. The wettability of HA coated nanotubular surface was higher than that of non-coated samples.

  5. Effects of Cryogenic Forging and Anodization on the Mechanical Properties of AA 7075-T73 Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Shih, Teng-Shih; Liao, Tien-Wei; Hsu, Wen-Nong

    2016-03-01

    In this study, high-strength AA7075 alloy samples were cryogenically forged after annealing and then subjected to solution and aging treatments. The cryogenically forged 7075-T73 alloy samples displayed equiaxed fine grains associated with abundant fine precipitates in their matrix. Compared with conventional 7075-T73 alloy samples, the cryogenically forged samples exhibited an 8-12% reduction in tensile strength and an increased fatigue strength and higher corrosion resistance. The fatigue strength measured at 107 cycles was 225 MPa in the bare samples; the strength was increased to 250 MPa in the cryogenically forged samples. The effect of anodization on the corrosion resistance of the bare samples was improved from (E corr) -0.80 to -0.61 V.

  6. Comparison of Pt-based binary and ternary alloy anode catalysts for polymer electrolyte direct methanol fuel cells

    SciTech Connect

    Liu, R.; Ley, K.L.; Pu, C.

    1996-12-31

    As an anode catalyst, Pt is highly active for the adsorption and dehydrogenation of methanol, however, the surface is poisoned by CO. To oxidize CO to CO{sub 2}, a second oxygen atom is required from an adjacent adsorbed water molecule. Bifunctional alloys composed of Pt and a second metal M, able to activate H{sub 2}O (forming -OH{sub ads}) at low potentials, are candidate materials for methanol electro-oxidation catalysts A proposed mechanism is: Figure 2 shows that metals which enhance methanol oxidation activity when alloyed with Pt have similar M-O bond strengths (see bold print), suggesting that the best binary alloy catalysts have second metals that are optimized with respect to the ability to oxidatively adsorb water. and the ability to dissociate M-O bonds to yield CO{sub 2}.

  7. Preparation of PdCu Alloy Nanocatalysts for Nitrate Hydrogenation and Carbon Monoxide Oxidation

    SciTech Connect

    Cai, Fan; Yang, Lefu; Shan, Shiyao; Mott, Derrick; Chen, Bing H.; Luo, Jin; Zhong, Chuan-Jian

    2016-06-30

    Alloying Pd with Cu is important for catalytic reactions such as denitrification reaction and CO oxidation reaction, but understanding of the catalyst preparation and its correlation with the catalyst’s activity and selectivity remains elusive. Herein, we report the results of investigations of the preparation of PdCu alloy nanocatalysts using different methods and the catalytic properties of the catalysts in catalytic denitrification reaction and CO oxidation reaction. PdCu alloy nanocatalysts were prepared by conventional dry impregnation method and ligand-capping based wet chemical synthesis method, and subsequent thermochemical activation as well. The alloying characteristics depend on the bimetallic composition. PdCu/Al2O3 with a Pd/Cu ratio of 50:50 was shown to exhibit an optimized hydrogenation activity for the catalytic denitrification reaction. The catalytic activity of the PdCu catalysts was shown to be highly dependent on the support, as evidenced by the observation of an enhanced catalytic activity for CO oxidation reaction using TiO2 and CeO2 supports with high oxygen storage capacity. Lastly, we discussed the implications of the results to the refinement of the preparation of the alloy nanocatalysts.

  8. Preparation of PdCu Alloy Nanocatalysts for Nitrate Hydrogenation and Carbon Monoxide Oxidation

    DOE PAGES

    Cai, Fan; Yang, Lefu; Shan, Shiyao; ...

    2016-06-30

    Alloying Pd with Cu is important for catalytic reactions such as denitrification reaction and CO oxidation reaction, but understanding of the catalyst preparation and its correlation with the catalyst’s activity and selectivity remains elusive. Herein, we report the results of investigations of the preparation of PdCu alloy nanocatalysts using different methods and the catalytic properties of the catalysts in catalytic denitrification reaction and CO oxidation reaction. PdCu alloy nanocatalysts were prepared by conventional dry impregnation method and ligand-capping based wet chemical synthesis method, and subsequent thermochemical activation as well. The alloying characteristics depend on the bimetallic composition. PdCu/Al2O3 with amore » Pd/Cu ratio of 50:50 was shown to exhibit an optimized hydrogenation activity for the catalytic denitrification reaction. The catalytic activity of the PdCu catalysts was shown to be highly dependent on the support, as evidenced by the observation of an enhanced catalytic activity for CO oxidation reaction using TiO2 and CeO2 supports with high oxygen storage capacity. Lastly, we discussed the implications of the results to the refinement of the preparation of the alloy nanocatalysts.« less

  9. Aging Strengthening Mechanism of the Cu-1.0Zr Alloy

    NASA Astrophysics Data System (ADS)

    Tian, Ka; Tian, Baohong; Zhang, Yi; Liu, Yong; Volinsky, Alex A.

    2017-08-01

    The effects of different aging processes on electrical conductivity and microhardness of a Cu-1.0Zr alloy were investigated. Microstructure and precipitates of the aged alloy were analyzed by transmission electron microscopy, and the aging strengthening mechanism of the Cu-1.0Zr alloy is discussed. Good comprehensive performance of the Cu-1.0Zr alloy can be obtained by aging at 773K (500 °C) for 1 hour, for which electrical conductivity reached 80.2 pct IACS, while microhardness reached 155.6 HV. Small amounts of a Zr-rich phase and annealing twins were present in the solid solution. A large amount of 3-18 nm Cu10Zr7 precipitates were present in the copper matrix. At the early stage of aging, the precipitates were small and their density was relatively low. As aging time progressed, the precipitates gradually increased in size. After overaging, the precipitated phase was dissolved, resulting in reduced microhardness. After aging at 723 K (450 °C) for 6 hours, the precipitates were Cu10Zr7. The peak Cu-1.0Zr alloy performance was achieved after aging at 773 K (500 °C) for 1 hour, and the main reason for the performance increase is coherent strain hardening.

  10. Annealing dependence of giant magnetoresistance in CuFeNi alloys

    NASA Astrophysics Data System (ADS)

    Martins, C. S.; Missell, F. P.

    2000-05-01

    Giant magnetoresistance (GMR) in granular CuFeNi alloys is comparable in magnitude to that observed in CuCo. Here we study magnetization M and GMR (0Cu80Fe20-xNix (x=0, 2.5, 5, 10, and 15) as a function of annealing temperature Tan<500 °C, using a superconducting quantum interference device (SQUID) magnetometer. A wide variety of granular structures characterized by different average values of the particle sizes is obtained for different Fe/Ni ratios and annealing conditions. For Cu80Fe10Ni10, neither M nor GMR exhibit static hysteresis for T>50 K. At this temperature, the largest GMR value (19%) was obtained for a sample annealed at 400 °C for 2 h. In Cu80Fe5Ni15, on the other hand, the microstructure and magnetic properties of the alloy are much more sensitive to annealing. The magnetoresistence is strongly dependent upon both the annealing and the measuring temperatures. For Fe-rich Cu80Fe20-xNix, the magnetic properties other alloys show a weak dependence upon annealing temperature. Magnetization curves for both as-cast and annealed alloys indicate many large particles which saturate at low magnetic fields. GMR versus alloy composition is presented for two annealing temperatures.

  11. AlCu alloy films prepared by the thermal diffusion technique

    SciTech Connect

    Oliva, A.I.; Corona, J.E.; Sosa, V.

    2010-07-15

    100-nm thick films of Al{sub 1-x}Cu{sub x} alloys were prepared on glass substrates by thermal diffusion technique. The Cu atomic concentration was varied from 10% to 90%. Alloys were prepared at different temperatures into a vacuum oven with Argon atmosphere. Two thermal processes were used: i) heating the film at 400 deg. C in a single step, and ii) heating the films in sequential steps at 100, 200, 300 and 400 deg. C. Morphology, electrical resistivity, and crystalline orientation of the alloys were studied. The electrical resistivity and surface roughness of the alloys were found to depend strongly on the atomic composition and the diffusion temperature. However, we did not find differences between samples prepared under the two thermal processes. Alloys prepared with x = 0.6 and x = 0.1-0.3 as Cu at concentration exhibited values on electrical resistivity and surface roughness lower than pure Al. Different phases of the Al{sub 1} {sub -} {sub x}Cu{sub x} films were observed as a function of Cu concentration showing a good agreement with the AlCu phase diagram.

  12. Stress oscillations and surface alloy formation during the growth of FeMn on Cu(001)

    NASA Astrophysics Data System (ADS)

    Pan, Wei; Sander, Dirk; Lin, Minn-Tsong; Kirschner, Jürgen

    2003-12-01

    In situ stress and medium-energy electron-diffraction (MEED) measurements have been performed simultaneously during the deposition of FeMn on Cu(001). For a thickness above 5 layers, stress and MEED exhibit coherent layer-by-layer oscillations with a period of one atomic layer, where the largest compressive stress corresponds to the filled layer. In this thickness regime, the average stress is -0.59±0.02 GPa. From this, we deduce the biaxial modulus of FeMn layers as 148 (±5) GPa, which agrees well with the respective bulk value. For a FeMn thickness below 1.5 layers, the resulting stress is qualitatively ascribed to the sum of the individual stress contributions from Fe on Cu(001) and Mn on Cu(001). A c(2×2) low-energy electron diffraction pattern in this thickness regime indicates the formation of a c(2×2) MnCu surface alloy in the initial growth of FeMn on Cu(001), which induces a compressive surface stress of -0.7 N/m for the initial deposition of the FeMn alloy. This surface alloy formation leads to a Fe-rich FeMn alloy near the Cu interface. This compositional change might modify the antiferromagnetic coupling of the 1:1 FeMn alloy.

  13. Specific heat capacity and dendritic growth kinetics of liquid peritectic Fe-Cu alloys

    NASA Astrophysics Data System (ADS)

    Xia, Z. C.; Wang, W. L.; Luo, S. B.; Wei, B.

    2016-08-01

    The specific heat and dendritic growth of highly undercooled peritectic Fe-Cu alloys were investigated by electromagnetic levitation technique. The specific heat values of liquid peritectic Fe92.8Cu7.2 and hyperperitectic Fe88.5Cu11.5 alloys were determined to be 40.4 and 39.58 J·mol-1·K-1 over wide temperature ranges. The measured growth velocities rose rapidly with increasing undercooling, which reached 69 and 68 m·s-1 at the maximum undercoolings of 401 K (0.23 TL) and 468 K (0.27 TL). The microstructures of peritectic Fe-Cu alloys were refined significantly with enhanced undercooling. Theoretical analyses showed that almost segregationless solidification was realized if undercooling was sufficiently large.

  14. Molecular Dynamics Simulation of the Phonon Conductivity in Cu-Ni Binary Alloy

    NASA Astrophysics Data System (ADS)

    Konishi, Yusuke; Fukushima, Tetsuya; Sato, Kazunori; Asai, Yoshihiro; Katayama-Yoshida, Hiroshi

    2014-03-01

    In 2010, a giant Peltier effect was observed in a Cu-Ni/Au junction. It is considered that this giant Peltier effect is caused by nano-scale phase separation formed in the sputtering process. The giant Peltier coefficient in the Cu-Ni/Au junction indicates the great Seebeck coefficient in Cu-Ni alloy. Although this alloy is a prospective thermoelectric material because of its great Seebeck coefficient, the low phonon thermal conductivity is also necessary for a large thermoelectric coefficient ZT. In order to find conditions for the low phonon conductivity, we calculate the thermal conductivity in Cu-Ni Alloy in various shapes with or without nanostructures by using nonequilibrium molecular dynamics simulation. In this simulation, we use a semi-empirical potential and the reverse nonequilibrium molecular dynamics method.

  15. Forge Welding of Magnesium Alloy to Aluminum Alloy Using a Cu, Ni, or Ti Interlayer

    NASA Astrophysics Data System (ADS)

    Yamagishi, Hideki; Sumioka, Junji; Kakiuchi, Shigeki; Tomida, Shogo; Takeda, Kouichi; Shimazaki, Kouichi

    2015-08-01

    The forge-welding process was examined to develop a high-strength bonding application of magnesium (Mg) alloy to aluminum (Al) alloy under high-productivity conditions. The effect of the insert material on the tensile strength of the joints, under various preheat temperatures and pressures, was investigated by analyzing the reaction layers of the bonded interface. The tensile strengths resulting from direct bonding, using pure copper (Cu), pure nickel (Ni), and pure titanium (Ti) inserts were 56, 100, 119, and 151 MPa, respectively. The maximum joint strength reached 93 pct with respect to the Mg cast billet. During high-pressure bonding, a microscopic plastic flow occurred that contributed to an anchor effect and the generation of a newly formed surface at the interface, particularly prominent with the Ti insert in the form of an oxide layer. The bonded interfaces of the maximum-strength inserts were investigated using scanning electron microscopy-energy-dispersive spectroscopy and electron probe microanalysis. The diffusion reaction layer at the bonded interface consisted of brittle Al-Mg intermetallics having a thickness of approximately 30 μm. In contrast, for the three inserts, the thicknesses of the diffusion reaction layer were infinitely thin. For the pure Ti insert, exhibiting the maximum tensile strength value among the inserts tested, focused ion beam-transmission electron microscopy-EDS analysis revealed a 60-nm-thick Al-Ti reaction layer, which had formed at the bonded interface on the Mg alloy side. Thus, a high-strength Al-Mg bonding method in air was demonstrated, suitable for mass production.

  16. Age hardening characteristics and mechanical behavior of Al-Cu-Li-Zr-In alloys

    NASA Technical Reports Server (NTRS)

    Wagner, John A.

    1989-01-01

    An investigation was conducted to determine the age-hardening response and cryogenic mechanical properties of superplastic Al-Cu-Li-Zr-In alloys. Two alloys with compositions Al-2.65Cu-2.17Li-O.13Zr (baseline) and Al-2.60Cu-2.34Li-0.16Zr-0.17In were scaled-up from 30 lb permanent mold ingots to 350 lb DC (direct chill) ingots and thermomechanically processed to 3.2 mm thick sheet. The microstructure of material which contained the indium addition was partially recrystallized compared to the baseline suggesting that indium may influence recrystallization behavior. The indium-modified alloy exhibited superior hardness and strength compared to the baseline alloy when solution-heat-treated at 555 C and aged at 160 C or 190 C. For each alloy, strength increased and toughness was unchanged or decreased when tested at - 185 C compared to ambient temperature. By using optimized heat treatments, the indium-modified alloy exhibited strength levels approaching those of the baseline alloy without deformation prior to aging. The increase in strength of these alloys in the T6 condition make them particularly attractive for superplastic forming applications where post-SPF parts cannot be cold deformed to increase strength.

  17. Magnetic Susceptibility of liquid Gd-NM (NM = Cu, Ga, Ge) alloys

    NASA Astrophysics Data System (ADS)

    Shimakura, Hironori; Tahara, Shuta; Okada, Tatsuya; Ohno, Satoru

    2017-08-01

    For rare earth alloys, the indirect interaction of RKKY is at work between rare-earth atoms. Therefore, the magnetism of them depends on the number of conduction electrons and the distance between rare-earth metals. In this work, to reveal the relationship between the number of conduction electrons and magnetic property of rare earth metal alloys, magnetic susceptibility measurements for liquid Gd-NM (NM = Cu, Ga, Ge) was performed by Faraday method. As the results, it was observed that the sign of paramagnetic Curie temperature of Cu-Gd alloys are positive at all composition, while Ga-Gd and Ge-Gd alloys show negative paramagnetic Curie temperature at certain composition. Moreover, it was indicated when the alloy at certain composition shows highest melting temperature, it has the lowest paramagnetic Curie temperature.

  18. Atomistic Modeling of Quaternary Alloys: Ti and Cu in NiAl

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Mosca, Hugo O.; Wilson, Allen W.; Noebe, Ronald D.; Garces, Jorge E.

    2002-01-01

    The change in site preference in NiAl(Ti,Cu) alloys with concentration is examined experimentally via ALCHEMI and theoretically using the Bozzolo-Ferrante-Smith (BFS) method for alloys. Results for the site occupancy of Ti and Cu additions as a function of concentration are determined experimentally for five alloys. These results are reproduced with large-scale BFS-based Monte Carlo atomistic simulations. The original set of five alloys is extended to 25 concentrations, which are modeled by means of the BFS method for alloys, showing in more detail the compositional range over which major changes in behavior occur. A simple but powerful approach based on the definition of atomic local environments also is introduced to describe energetically the interactions between the various elements and therefore to explain the observed behavior.

  19. In-situ carbon coated CuCo2S4 anode material for Li-ion battery applications

    NASA Astrophysics Data System (ADS)

    Verma, Rakesh; R, Kothandaraman; Varadaraju, U. V.

    2017-10-01

    In-situ carbon coated carrollite spinel CuCo2S4 nanoparticles were synthesized by a simple low temperature hydrothermal route and studied as anode for lithium battery applications. The electrochemical reaction with lithium involves initial insertion of 3Li/f.u into the lattice upto 1.5 V followed by conversion reaction upto 0.01 V. A reversible capacity of 180 mAh g-1 was obtained for CuCo2S4 after 30 cycles at C/5 rate (137 mA g-1). However, in-situ carbon coated CuCo2S4 shows significantly higher capacity of 375 mAh g-1 even after 30 cycles.

  20. Bonding of Cf/SiC composite to Invar alloy using an active cement, Ag-Cu eutectic and Cu interlayer

    NASA Astrophysics Data System (ADS)

    Lei, Zhao; Xiaohong, Li; Jinbao, Hou; Qiang, Sun; Fuli, Zhang

    2012-10-01

    The interfacial microstructures and mechanical properties of the joints formed by active cement added brazing in vacuum of Cf/SiC composite to Invar alloy, using Ag-Cu eutectic alloy and pure copper foil as braze alloy and interlayer respectively, were investigated. CuTi, Cu4Ti3, Fe2Ti and the reaction layer of TiC and Si were the predominant components at the joint interface. The maximum shear strength of the joint was 77 MPa for brazing at 850 °C for 15 min. The results show that active cement added brazing in vacuum using Ag-Cu eutectic alloy and Cu interlayer can be used successfully for joining Cf/SiC composites to Invar alloy.

  1. Diffusion properties of Cu(0 0 1)- c(2 × 2)-Pd surface alloys

    NASA Astrophysics Data System (ADS)

    Eremeev, S. V.; Rusina, G. G.; Chulkov, E. V.

    2007-09-01

    Structural and diffusion properties of a Cu(0 0 1)- c(2 × 2)-Pd surface and sub-surface ordered alloys are studied by using interaction potentials obtained from the embedded-atom method. The calculated diffusion energies are in agreement with observed kinetics of the surface alloy formation and confirm stability of the underlayer alloy. Activation energy of planar diffusion of palladium at the initial stage of the alloy formation as well as the activation energy of the overlayer-underlayer diffusion of the Pd atoms are in good agreement with those obtained by the scanning tunneling microscopy and low energy electron diffraction measurements, respectively.

  2. Electrodeposition of Zn and Cu-Zn alloy from ZnO/CuO precursors in deep eutectic solvent

    NASA Astrophysics Data System (ADS)

    Xie, Xueliang; Zou, Xingli; Lu, Xionggang; Lu, Changyuan; Cheng, Hongwei; Xu, Qian; Zhou, Zhongfu

    2016-11-01

    The electrodeposition of Zn and Cu-Zn alloy has been investigated in choline chloride (ChCl)/urea (1:2 molar ratio) based deep eutectic solvent (DES). Cyclic voltammetry study demonstrates that the reduction of Zn(II) to Zn is a diffusion-controlled quasi-reversible, one-step, two electrons transfer process. Chronoamperometric investigation indicates that the electrodeposition of Zn on a Cu electrode typically involves three-dimensional instantaneous nucleation with diffusion-controlled growth process. Micro/nanostructured Zn films can be obtained by controlling the electrodeposition potential and temperature. The electrodeposited Zn crystals preferentially orient parallel to the (101) plane. The Zn films electrodeposited under more positive potentials and low temperatures exhibit improved corrosion resistance in 3 wt% NaCl solution. In addition, Cu-Zn alloy films have also been electrodeposited directly from CuO-ZnO precursors in ChCl/urea-based DES. The XRD analysis indicates that the phase composition of the electrodeposited Cu-Zn alloy depends on the electrodeposition potential.

  3. Effect of the existing form of Cu element on the mechanical properties, bio-corrosion and antibacterial properties of Ti-Cu alloys for biomedical application.

    PubMed

    Zhang, Erlin; Wang, Xiaoyan; Chen, Mian; Hou, Bing

    2016-12-01

    Ti-Cu alloys have exhibited strong antibacterial ability, but Ti-Cu alloys prepared by different processes showed different antibacterial ability. In order to reveal the controlling mechanism, Ti-Cu alloys with different existing forms of Cu element were prepared in this paper. The effects of the Cu existing form on the microstructure, mechanical, corrosion and antibacterial properties of Ti-Cu alloys have been systematically investigated. Results have shown that the as-cast Ti-Cu alloys showed a higher hardness and mechanical strength as well as a higher antibacterial rate (51-64%) but a relatively lower corrosion resistance than pure titanium. Treatment at 900°C/2h (T4) significantly increased the hardness and the strength, improved the corrosion resistance but had little effect on the antibacterial property. Treatment at 900°C/2h+400°C/12h (T6) increased further the hardness and the mechanical strength, improved the corrosion resistance and but also enhanced the antibacterial rate (>90%) significantly. It was demonstrated that the Cu element in solid solution state showed high strengthening ability but low antibacterial property while Cu element in Ti2Cu phase exhibited strong strengthening ability and strong antibacterial property. Ti2Cu phase played a key role in the antibacterial mechanism. The antibacterial ability of Ti-Cu alloy was strongly proportional to the Cu content and the surface area of Ti2Cu phase. High Cu content and fine Ti2Cu phase would contribute to a high strength and a strong antibacterial ability.

  4. Fabrication of Ni-Ti-O nanotube arrays by anodization of NiTi alloy and their potential applications

    PubMed Central

    Hang, Ruiqiang; Liu, Yanlian; Zhao, Lingzhou; Gao, Ang; Bai, Long; Huang, Xiaobo; Zhang, Xiangyu; Tang, Bin; Chu, Paul K.

    2014-01-01

    Nickel-titanium-oxide (Ni-Ti-O) nanotube arrays (NTAs) prepared on nearly equiatomic NiTi alloy shall have broad application potential such as for energy storage and biomedicine, but their precise structure control is a great challenge because of the high content of alloying element of Ni, a non-valve metal that cannot form a compact electronic insulating passive layer when anodized. In the present work, we systemically investigated the influence of various anodization parameters on the formation and structure of Ni-Ti-O NTAs and their potential applications. Our results show that well controlled NTAs can be fabricated during relatively wide ranges of the anodization voltage (5–90 V), electrolyte temperature (10–50°C) and electrolyte NH4F content (0.025–0.8 wt%) but within a narrow window of the electrolyte H2O content (0.0–1.0 vol%). Through modulating these parameters, the Ni-Ti-O NTAs with different diameter (15–70 nm) and length (45–1320 nm) can be produced in a controlled manner. Regarding potential applications, the Ni-Ti-O NTAs may be used as electrodes for electrochemical energy storage and non-enzymic glucose detection, and may constitute nanoscaled biofunctional coating to improve the biological performance of NiTi based biomedical implants. PMID:25520180

  5. Fabrication of Ni-Ti-O nanotube arrays by anodization of NiTi alloy and their potential applications.

    PubMed

    Hang, Ruiqiang; Liu, Yanlian; Zhao, Lingzhou; Gao, Ang; Bai, Long; Huang, Xiaobo; Zhang, Xiangyu; Tang, Bin; Chu, Paul K

    2014-12-18

    Nickel-titanium-oxide (Ni-Ti-O) nanotube arrays (NTAs) prepared on nearly equiatomic NiTi alloy shall have broad application potential such as for energy storage and biomedicine, but their precise structure control is a great challenge because of the high content of alloying element of Ni, a non-valve metal that cannot form a compact electronic insulating passive layer when anodized. In the present work, we systemically investigated the influence of various anodization parameters on the formation and structure of Ni-Ti-O NTAs and their potential applications. Our results show that well controlled NTAs can be fabricated during relatively wide ranges of the anodization voltage (5-90 V), electrolyte temperature (10-50°C) and electrolyte NH4F content (0.025-0.8 wt%) but within a narrow window of the electrolyte H2O content (0.0-1.0 vol%). Through modulating these parameters, the Ni-Ti-O NTAs with different diameter (15-70 nm) and length (45-1320 nm) can be produced in a controlled manner. Regarding potential applications, the Ni-Ti-O NTAs may be used as electrodes for electrochemical energy storage and non-enzymic glucose detection, and may constitute nanoscaled biofunctional coating to improve the biological performance of NiTi based biomedical implants.

  6. Structural study of an amorphous CuTi alloy produced by mechanical alloying using XRD, EXAFS and RMC simulations

    NASA Astrophysics Data System (ADS)

    Machado, K. D.; Maciel, G. A.; Sanchez, D. F.; de Lima, J. C.; Jóvári, P.

    2010-09-01

    The structure of an amorphous Cu 64Ti 36 alloy produced by mechanical alloying was studied by X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) spectroscopy techniques and modeled through reverse Monte Carlo simulations using the total structure factor S(K) and the EXAFS χ(k) oscillations on Cu K edge as input data. From the simulations the partial pair distribution functions g(r) and the bond-angle distribution functions Θ(cosθ) were determined and, from these functions, average coordination numbers and average interatomic distances for the first neighbors were calculated. We also obtained information about the three-dimensional structures present in the alloy.

  7. Influence of Cu Addition on the Structure, Mechanical and Corrosion Properties of Cast Mg-2%Zn Alloy

    NASA Astrophysics Data System (ADS)

    Lotfpour, M.; Emamy, M.; Dehghanian, C.; Tavighi, K.

    2017-05-01

    Effects of different concentrations of Cu on the structure, mechanical and corrosion properties of Mg-2%Zn alloy were studied by the use of x-ray diffraction, optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, standard tensile testing, polarization and electrochemical impedance spectroscopy (EIS) measurements. The average grain size of the alloy decreased from above 1000 μm to about 200 μm with 5 wt.% Cu addition in as-cast condition. Microstructural studies revealed that Mg-2Zn- xCu alloys matrix typically consists of primary α-Mg and MgZnCu and Mg(Zn,Cu)2 intermetallics which are mainly found at the grain boundaries. The results obtained from mechanical testing ascertained that Cu addition increased the hardness values significantly. Although the addition of 0.5 wt.% Cu improved the ultimate tensile strength and elongation values, more Cu addition (i.e., 5 wt.%) weakened the tensile properties of the alloy by introducing semi-continuous network of brittle intermetallic phases. Based on polarization test results, it can be concluded that Cu eliminates a protective film on Mg-2%Zn alloy surface. Among Mg-2%Zn- x%Cu alloys, the one containing 0.1 wt.% Cu exhibited the best anti-corrosion property. However, further Cu addition increased the volume fraction of intermetallics culminating in corrosion rate enhancement due to the galvanic couple effect. EIS and microstructural analysis also confirmed the polarization results.

  8. A Study of Al-Zn-Sn Alloy Sacrificial Anode Cathodic Protection Requirements for Structure Used In Seawater

    SciTech Connect

    Kamarudin, Siti Radiah Mohd; Daud, Muhamad; Sattar, Shariff; Daud, Abd. Razak

    2010-01-05

    The corrosion of aluminium (Al) alloys in seawater was investigated using potentiodynamic technique, complemented by Scanning Electron Microscopy (SEM), EDAX and XRD. SEM was used out to characterize the corroded surface and to observe the extent of corrosion attack on the Al alloys tested in seawater. EDAX analysis was used to identify elements present on the specimen surface. Where else XRD was to identify phase appearance. The results indicate that zinc (Zn), stanum (Sn) and copper (Cu) as alloying elements enhance corrosion behaviour of the aluminium in seawater by shifting the potential to a more negative value. In the presence of those elements, the Al alloys becomes more active, having potential of more than -1.0 V{sub SCE} and showed active corrosion behaviour.

  9. Age hardening and creep resistance of cast Al–Cu alloy modified by praseodymium

    SciTech Connect

    Bai, Zhihao; Qiu, Feng; Wu, Xiaoxue; Liu, Yingying; Jiang, Qichuan

    2013-12-15

    The effects of praseodymium on age hardening behavior and creep resistance of cast Al–Cu alloy were investigated. The results indicated that praseodymium facilitated the formation of the θ′ precipitates during the age process and improved the hardness of the Al–Cu alloy. Besides, praseodymium resulted in the formation of the Al{sub 11}Pr{sub 3} phase in the grain boundaries and among the dendrites of the modified alloy. Because of the good thermal stability of Al{sub 11}Pr{sub 3} phase, it inhibits grain boundary migration and dislocation movement during the creep process, which contributes to the improvement in the creep resistance of the modified alloy at elevated temperatures. - Highlights: • Pr addition enhances the hardness and creep resistance of the Al–Cu alloy. • Pr addition facilitates the formation of the θ′ precipitates. • Pr addition results in the formation of the Al11Pr3 phase in the Al–Cu alloy.

  10. Magnetic properties of Fe-Cu alloys grown by molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Grigorov, I. L.; Freeland, J. W.; Walker, J. C.

    1996-03-01

    Magnetic properties of Fe_xCu_1-x alloys are difficult to study due to the low mutual solid solubility of the components. These alloys can be formed by co-sputtering onto a cold substrate, however, they retain fcc phase only for x < 0.6footnote[1]C.L. Chien et. al. Phys.Rev. B 33, 3247 (1986). In this work Fe_xCu_1-x alloys were grown epitaxially by co-deposition onto the Cu(100) substrate. Using this technique we can stabilize the alloy in fcc phase across the entire Fe concentration range. During growth, the substrate was maintained at 0^0C to prevent clustering. Crystal structure was monitored by in-situ RHEED and ex-situ X-ray diffraction. The correlation between structural and magnetic properties of the alloys as well as their dependence on the film thickness were studied by SQUID magnetometry and Mössbauer spectroscopy. Initial results showed a non-zero quadrupole splitting of the room temperature Mössbauer absorption line indicating the random distribution of iron in the Cu matrix. Both low temperature Mössbauer and SQUID measurements on the alloys with low iron concentration showed significant reduction of the average magnetic moment and T_c.

  11. Characterization of prior cold worked and age hardened Cu-3Ti-1Cd alloy

    SciTech Connect

    Markandeya, R. . E-mail: marksravvala@yahoo.co.in; Nagarjuna, S.; Sarma, D.S.

    2005-05-15

    The influence of cold deformation by 50%, 75% and 90% on the age-hardening behavior of a Cu-3Ti-1Cd alloy has been investigated by hardness, tensile tests and light optical as well as transmission electron microscopy. The hardness of Cu-3Ti-1Cd alloy increased from 111 Hv in the solution-treated condition to 355 Hv in 90% cold worked and peak aged condition. The yield and ultimate tensile strengths of Cu-3Ti-1Cd alloy reached maxima of 922 MPa and 1035 MPa, respectively, on 90% deformation and peak aging. The microstructure of the deformed alloy exhibited elongated grains and deformation bands. The maximum strength on peak aging was brought about by the precipitation of ordered, metastable, coherent {beta}' Cu{sub 4}Ti phase, in addition to high dislocation density and deformation twins. Both the hardness and the strength of the alloy decreased on overaging due to the development of the incoherent equilibrium phase {beta} Cu{sub 3}Ti in a cellular structure form. However, the morphology of the discontinuous precipitation was changed to globular form at high deformation levels.

  12. Core level shifts in Cu-Pd alloys as a function of bulk composition and structure

    NASA Astrophysics Data System (ADS)

    Boes, Jacob R.; Kondratyuk, Peter; Yin, Chunrong; Miller, James B.; Gellman, Andrew J.; Kitchin, John R.

    2015-10-01

    CuPd alloys are important materials in hydrogen purification, where they are used as dense Pd-based separation membranes. Cu is added to impart sulfur tolerance and improved mechanical properties. At intermediate compositions and T < 873 K, a BCC alloy (B2) phase occurs, which has superior separation characteristics to those of the FCC phases that form at high Cu and high Pd compositions. Identifying the composition and temperature window where the B2 phase forms is a critical need to enable the design of improved alloys. A composition spread alloy film of Cu and Pd was synthesized. The film was characterized by electron back scatter diffraction and X-ray photoelectron spectroscopy, providing the core level shifts as a function of bulk composition and bulk structure. An anomalous deviation in the Cu core level shift was observed in the composition range 0.33 < xPd < 0.55 over which the B2 phase occurs. Density functional theory calculations were used to simulate core level shifts in the FCC and B2 alloy structures. They suggest that the anomalous deviation in core level shift is due to formation of the ordered B2 phase in this composition range.

  13. Nanoporous Ag prepared from the melt-spun Cu-Ag alloys

    NASA Astrophysics Data System (ADS)

    Li, Guijing; Song, Xiaoping; Sun, Zhanbo; Yang, Shengchun; Ding, Bingjun; Yang, Sen; Yang, Zhimao; Wang, Fei

    2011-07-01

    Nanoporous Ag ribbons with different morphology and porosity were achieved by the electrochemical corrosion of the melt-spun Cu-Ag alloys. The Cu-rich phase in the alloys was removed, resulting in the formation of the nanopores distributed across the whole ribbon. It is found that the structures, morphology and porosity of the nanoporous Ag ribbons were dependent on the microstructures of the parent alloys. The most of ligaments presented a rod-like shape due to the formation of pseudoeutectic microstructure in the melt-spun Cu 55Ag 45 and Cu 70Ag 30 alloys. For nanoporous Ag prepared from Cu 85Ag 15 alloys, the ligaments were camber-like because of the appearance of the divorced microstructures. Especially, a novel bamboo-grove-like structure could be observed at the cross-section of the nanoporous Ag ribbons. The experiment reveals that nanoporous Ag ribbons exhibited excellent enhancement of surface-enhanced Raman scattering (SERS) effect, but a slight difference existed due to the discrepancy of their morphology.

  14. Spectro-photometric determinations of Mn, Fe and Cu in aluminum master alloys

    NASA Astrophysics Data System (ADS)

    Rehan; Naveed, A.; Shan, A.; Afzal, M.; Saleem, J.; Noshad, M. A.

    2016-08-01

    Highly reliable, fast and cost effective Spectro-photometric methods have been developed for the determination of Mn, Fe & Cu in aluminum master alloys, based on the development of calibration curves being prepared via laboratory standards. The calibration curves are designed so as to induce maximum sensitivity and minimum instrumental error (Mn 1mg/100ml-2mg/100ml, Fe 0.01mg/100ml-0.2mg/100ml and Cu 2mg/100ml-10mg/ 100ml). The developed Spectro-photometric methods produce accurate results while analyzing Mn, Fe and Cu in certified reference materials. Particularly, these methods are suitable for all types of Al-Mn, Al-Fe and Al-Cu master alloys (5%, 10%, 50% etc. master alloys).Moreover, the sampling practices suggested herein include a reasonable amount of analytical sample, which truly represent the whole lot of a particular master alloy. Successive dilution technique was utilized to meet the calibration curve range. Furthermore, the workout methods were also found suitable for the analysis of said elements in ordinary aluminum alloys. However, it was observed that Cush owed a considerable interference with Fe, the later one may not be accurately measured in the presence of Cu greater than 0.01 %.

  15. Effects of Heat Treatment on the Discharge Behavior of Mg-6wt.%Al-1wt.%Sn Alloy as Anode For Magnesium-Air Batteries

    NASA Astrophysics Data System (ADS)

    Xiong, Hanqing; Zhu, Hualong; Luo, Jie; Yu, Kun; Shi, Chunli; Fang, Hongjie; Zhang, Yu

    2017-05-01

    Mg-6wt.%Al-1wt.%Sn alloys under different conditions are prepared. Primary magnesium-air batteries are assembled using such experimental Mg-Al-Sn alloys as anodes. The discharge behaviors of different alloys are investigated in 3.5 wt.% NaCl solution. The results show that the solution treatment can facilitate the homogeneous distribution of alloy elements and reduce the accumulation of discharge products. The magnesium-air battery based on the solution-treated Mg-Al-Sn anode presents higher operating voltage and more stable discharge process than those on the as-cast and the aged ones. Although the solution treatment cannot effectively improve the capacity density and the anodic efficiency of the experimental Mg-Al-Sn alloy, it is an effective approach to increasing the power and the energy density during discharge process. Especially at the applied current density of 30 mA cm-2 for 5 h, the solution-treated anode supplies 1.212 V average operating voltage, the anode energy density reaches 1527.2 mWhg-1, while the cast one is 1481.3 mWhg-1 and the aged one is 1478.8 mWhg-1.

  16. Microscopic analysis of thermally-driven formation of Cu-Si alloy nanoparticles in a Cu/Si template

    NASA Astrophysics Data System (ADS)

    Lee, Wooyoung; Jue, Miyeon; Lee, Sanghwa; Kim, Chinkyo

    2013-12-01

    Selective thermal diffusion of Cu into a 100-nm-thick SiO2-patterned Si(001) substrate was investigated to elucidate the spontaneous formation of Cu-Si alloy nanoparticles. Transmission electron microscopy and energy dispersive X-ray spectroscopy provided the indirect evidence for the formation on the substrate's surface of nanoparticles that served as a catalyst to grow SiO2 nanowires selectively in window regions. The microstructural analysis revealed that thermal annealing caused selective diffusion of Cu into the Si matrix in window regions only and that the Cu-Si alloy nanoparticles were formed at 900 °C although the diffusion of Cu into Si was already significant at 700 °C. The nanoparticles that were sparsely distributed below the surface of the Si matrix did not serve as a catalyst for growing SiO2 nanowires, and the chemical composition analysis showed that the nanoparticles at the tip of SiO2 nanowires were Cu3Si.

  17. Environmental fatigue of an Al-Li-Cu alloy. Part 2: Microscopic hydrogen cracking processes

    NASA Technical Reports Server (NTRS)

    Piascik, Robert S.; Gangloff, Richard P.

    1992-01-01

    Based on a fractographic analysis of fatigue crack propagation (FCP) in Al-Li-Cu alloy 2090 stressed in a variety of inert and embrittling environments, microscopic crack paths are identified and correlated with intrinsic da/dN-delta K kinetics. FCP rates in 2090 are accelerated by hydrogen producing environments (pure water vapor, moist air, and aqueous NaCl), as defined in Part 1. For these cases, subgrain boundary fatigue cracking (SGC) dominates for delta K values where the crack tip process zone, a significant fraction of the cyclic plastic zone, is sufficiently large to envelop 5 micron subgrains in the unrecrystallized microstructure. SGC may be due to strong hydrogen trapping at T1 precipitates concentrated at sub-boundaries. At low delta K, the plastic zone diameter is smaller than the subgrain size and FCP progresses along (100) planes due to either local lattice decohesion or aluminum-lithium hydride cracking. For inert environments (vacuum, helium, and oxygen), or at high delta K where the hydrogen effect on da/dN is small, FCP is along (111) slip planes; this mode does not transition with increasing delta K and plastic zone size. The SGC and (100) crystallographic cracking modes, and the governing influence of the crack tip process zone volume (delta K), support hydrogen embrittlement rather than a surface film rupture and anodic dissolution mechanism for environmental FCP. Multi-sloped log da/dN-log delta K behavior is produced by changes in process zone hydrogen-microstructure interactions, and not by purely micromechanical-microstructure interactions, in contradiction to microstructural distance-based fatigue models.

  18. Hot Workability of CuZr-Based Shape Memory Alloys for Potential High-Temperature Applications

    NASA Astrophysics Data System (ADS)

    Biffi, Carlo Alberto; Tuissi, Ausonio

    2014-07-01

    The research on high-temperature shape memory alloys has been growing because of the interest of several potential industrial fields, such as automotive, aerospace, mechanical, and control systems. One suitable candidate is given by the CuZr system, because of its relative low price in comparison with others, like the NiTi-based one. In this context, the goal of this work is the study of hot workability of some CuZr-based shape memory alloys. In particular, this study addresses on the effect of hot rolling process on the metallurgical and calorimetric properties of the CuZr system. The addition of some alloying elements (Cr, Co, Ni, and Ti) is taken into account and their effect is also put in comparison with each other. The alloys were produced by means of an arc melting furnace in inert atmosphere under the shape of cigars. Due to the high reactivity of these alloys at high temperature, the cigars were sealed in a stainless steel can before the processing and two different procedures of hot rolling were tested. The characterization of the rolled alloys is performed using discrete scanning calorimetry in terms of evolution of the martensitic transformation and scanning electron microscopy for the microstructural investigations. Additionally, preliminary tests of laser interaction has been also proposed on the alloy more interesting for potential applications, characterized by high transformation temperatures and its good thermal stability.

  19. Microstructure evolution and tensile mechanical properties of thixoformed high performance Al-Zn-Mg-Cu alloy

    NASA Astrophysics Data System (ADS)

    Chen, Gang; Chen, Qiang; Wang, Bo; Du, Zhi-ming

    2015-09-01

    Al-Zn-Mg-Cu alloys are the strongest aluminum alloys which have been widely used for aerospace applications. They are usually machined from the wrought state usually with a high waste percentage. To reduce waste, it is important to thixoform these alloys in near net shape. In this work, the thixoformability of a commercial high performance Al-Zn-Mg-Cu alloy 7075 was studied. A novel multistep reheating regime was developed in recrystallization and partial melting (RAP) route to obtain spheroidal semi-solid microstructures. The as-extruded 7075 alloy was fully recrystallized for a short holding time using the multistep reheating regime. Semi-solid microstructures with fine and spherical solid grains with a grain size of 40-50 μm embedded in liquid matrix were obtained. The advantage of the multistep reheating regimes over those conventional routes was also discussed. Some wheel-shaped components were thixoformed from the as-received 7075 alloy. The ultimate tensile strength, yield strength and elongation to fracture of the thixoformed component based on multistep reheating regime, are 510 MPa, 446 MPa and 17.5% respectively. These values are superior to those of the products manufactured with the conventional RAP route. As the results indicated, thixoforming could be conducted based on commercial extruded Al-Zn-Mg-Cu alloys, which has important practical significance.

  20. Monolithic Cu-Cr-Nb Alloys for High Temperature, High Heat Flux Applications

    NASA Technical Reports Server (NTRS)

    Ellis, David L.; Locci, Ivan E.; Michal, Gary M.; Humphrey, Derek M.

    1999-01-01

    Work during the prior four years of this grant has resulted in significant advances in the development of Cu-8 Cr4 Nb and related Cu-Cr-Nb alloys. The alloys are nearing commercial use in the Reusable Launch Vehicle (RLV) where they are candidate materials for the thrust cell liners of the aerospike engines being developed by Rocketdyne. During the fifth and final year of the grant, it is proposed to complete development of the design level database of mechanical and thermophysical properties and transfer it to NASA Glenn Research Center and Rocketdyne. The database development work will be divided into three main areas: Thermophysical Database Augmentation, Mechanical Testing and Metallography and Fractography. In addition to the database development, work will continue that is focussed on the production of alternatives to the powder metallurgy alloys currently used. Exploration of alternative alloys will be aimed at both the development of lower cost materials and higher performance materials. A key element of this effort will be the use of Thermo-Calc software to survey the solubility behavior of a wide range of alloying elements in a copper matrix. The ultimate goals would be to define suitable alloy compositions and processing routes to produce thin sheets of the material at either a lower cost, or, with improved mechanical and thermal properties compared to the current Cu-Cr-Nb powder metallurgy alloys.

  1. Investigation of vacuum properties of CuCrZr alloy for high-heat-load absorber

    NASA Astrophysics Data System (ADS)

    Shueh, C.; Chan, C. K.; Chang, C. C.; Sheng, I. C.

    2017-01-01

    The Taiwan Photon Source (TPS) uses high-heat-load (HHL) absorbers to protect downstream ultrahigh-vacuum chambers from overheating. In this work, we propose to use the CuCrZr alloy (ASTM C18150) for the HHL absorber body and the ConFlat flanges. We use the throughput method to measure the thermal outgassing rate and a helium leak detector to verify the vacuum seal between the CuCrZr alloy and stainless-steel flanges. The measured outgassing rate of the CuCrZr alloy was 5.8×10-10 Pa m/s after 72 h of pumping and decreased to 2.0 × 10-10 Pa m/s after 100 h of pumping. The leak rate through the vacuum seal between a CuCrZr flange and a stainless-steel flange was less than 1 × 10-10 Pa m3/s even after mounting and unmounting the flanges ten times and baking them at 250 °C. These results indicate that CuCrZr alloy is suitable for integrating HHL components with ConFlat CuCrZr flanges for the absorption of the synchrotron radiation generated by the TPS.

  2. Apatite Formation and Biocompatibility of a Low Young's Modulus Ti-Nb-Sn Alloy Treated with Anodic Oxidation and Hot Water.

    PubMed

    Tanaka, Hidetatsu; Mori, Yu; Noro, Atsushi; Kogure, Atsushi; Kamimura, Masayuki; Yamada, Norikazu; Hanada, Shuji; Masahashi, Naoya; Itoi, Eiji

    2016-01-01

    Ti-6Al-4V alloy is widely prevalent as a material for orthopaedic implants because of its good corrosion resistance and biocompatibility. However, the discrepancy in Young's modulus between metal prosthesis and human cortical bone sometimes induces clinical problems, thigh pain and bone atrophy due to stress shielding. We designed a Ti-Nb-Sn alloy with a low Young's modulus to address problems of stress disproportion. In this study, we assessed effects of anodic oxidation with or without hot water treatment on the bone-bonding characteristics of a Ti-Nb-Sn alloy. We examined surface analyses and apatite formation by SEM micrographs, XPS and XRD analyses. We also evaluated biocompatibility in experimental animal models by measuring failure loads with a pull-out test and by quantitative histomorphometric analyses. By SEM, abundant apatite formation was observed on the surface of Ti-Nb-Sn alloy discs treated with anodic oxidation and hot water after incubation in Hank's solution. A strong peak of apatite formation was detected on the surface using XRD analyses. XPS analysis revealed an increase of the H2O fraction in O 1s XPS. Results of the pull-out test showed that the failure loads of Ti-Nb-Sn alloy rods treated with anodic oxidation and hot water was greater than those of untreated rods. Quantitative histomorphometric analyses indicated that anodic oxidation and hot water treatment induced higher new bone formation around the rods. Our findings indicate that Ti-Nb-Sn alloy treated with anodic oxidation and hot water showed greater capacity for apatite formation, stronger bone bonding and higher biocompatibility for osteosynthesis. Ti-Nb-Sn alloy treated with anodic oxidation and hot water treatment is a promising material for orthopaedic implants enabling higher osteosynthesis and lower stress disproportion.

  3. Apatite Formation and Biocompatibility of a Low Young’s Modulus Ti-Nb-Sn Alloy Treated with Anodic Oxidation and Hot Water

    PubMed Central

    Tanaka, Hidetatsu; Mori, Yu; Noro, Atsushi; Kogure, Atsushi; Kamimura, Masayuki; Yamada, Norikazu; Hanada, Shuji; Masahashi, Naoya; Itoi, Eiji

    2016-01-01

    Ti-6Al-4V alloy is widely prevalent as a material for orthopaedic implants because of its good corrosion resistance and biocompatibility. However, the discrepancy in Young’s modulus between metal prosthesis and human cortical bone sometimes induces clinical problems, thigh pain and bone atrophy due to stress shielding. We designed a Ti-Nb-Sn alloy with a low Young’s modulus to address problems of stress disproportion. In this study, we assessed effects of anodic oxidation with or without hot water treatment on the bone-bonding characteristics of a Ti-Nb-Sn alloy. We examined surface analyses and apatite formation by SEM micrographs, XPS and XRD analyses. We also evaluated biocompatibility in experimental animal models by measuring failure loads with a pull-out test and by quantitative histomorphometric analyses. By SEM, abundant apatite formation was observed on the surface of Ti-Nb-Sn alloy discs treated with anodic oxidation and hot water after incubation in Hank’s solution. A strong peak of apatite formation was detected on the surface using XRD analyses. XPS analysis revealed an increase of the H2O fraction in O 1s XPS. Results of the pull-out test showed that the failure loads of Ti-Nb-Sn alloy rods treated with anodic oxidation and hot water was greater than those of untreated rods. Quantitative histomorphometric analyses indicated that anodic oxidation and hot water treatment induced higher new bone formation around the rods. Our findings indicate that Ti-Nb-Sn alloy treated with anodic oxidation and hot water showed greater capacity for apatite formation, stronger bone bonding and higher biocompatibility for osteosynthesis. Ti-Nb-Sn alloy treated with anodic oxidation and hot water treatment is a promising material for orthopaedic implants enabling higher osteosynthesis and lower stress disproportion. PMID:26914329

  4. Prediction of novel, Earth abundant Cu2O based alloys for PV applications

    NASA Astrophysics Data System (ADS)

    Stevanovic, Vladan; Lany, Stephan

    2014-03-01

    Tuning the opto-electronic properties of semiconductors through alloying is essential for semiconductor industry. Currently, mostly isovalent and isostructural alloys are used (e.g. Si/Ge, GaN/InN or CdTe/ZnTe), but a vast and unexplored space of novel functional materials is conceivable when considering more complex alloys by mixing aliovalent and heterostructural constituents. The real challenge lies in the quantitative property prediction for such complex alloys to guide their experimental exploration. In our work we demonstrate how an Earth abundant p-type oxide Cu2O, can be engineered through alloying into a technologically useful absorber material. We use non-local external potentials (NLEP) fitted to GW calculations for correcting the DFT electronic structure and compute absorption coefficient of different alloy compositions and configurations. Work supported by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Next Generation Photovoltaics II (SunShot initiative).

  5. Electrochemical Extraction of Nd from NaCl-KCl Melt by Formation of Cu-Nd Alloys

    NASA Astrophysics Data System (ADS)

    Zhang, Zhong-Lin; Zhou, Lin-Zong; Ji, De-Bin; Yan, Yong-De; Hong, Wei; Liu, Yu-Hui; Wang, Pu; Yin, Tai-Qi; Zheng, Jia-Ning; Xue, Yun; Ye, Yuan-Feng

    2017-10-01

    Electrochemical behavior of Nd was studied in NaCl-KCl melt on W and Cu electrodes via cyclic voltammetry and chronopotentiometry. Generally, the reduction of Nd3+ takes place in two consecutive steps in molten chlorides, such as LiCl-CaCl2, LiCl-BaCl2, CaCl2-NaCl, LiCl-KCl melts. However, the reduction of Nd3+ ions was found to be through a one-step process: Nd3+ + 3e- → Nd. The co-reduction behavior of Nd3+ and Cu2+ ions and the mechanisms of alloy formation were investigated in NaCl-KCl melt on W electrodes at 988 K (715 °C). Four potential plateaus corresponding to four different kinds of Cu-Nd intermetallic compounds were detected. Cu-Nd alloys were prepared on Cu electrodes at 988 K (715 °C) and 1143 K (870 °C). At 988 K (715 °C), Cu5Nd phase was identified by X-ray diffraction. The morphology and micro-zone chemical analysis of the alloys were characterized by scanning electron microscopy equipped with energy-dispersive spectrometry. The alloy film was observed on the Cu electrodes. Moreover, at 1143 K (870 °C), a globate bulk Cu-Nd alloy with Cu5Nd, Cu4Nd, Cu2Nd, CuNd, and Cu phases, as liquid in the melt, was obtained at the bottom of the crucible.

  6. Electrochemical Extraction of Nd from NaCl-KCl Melt by Formation of Cu-Nd Alloys

    NASA Astrophysics Data System (ADS)

    Zhang, Zhong-Lin; Zhou, Lin-Zong; Ji, De-Bin; Yan, Yong-De; Hong, Wei; Liu, Yu-Hui; Wang, Pu; Yin, Tai-Qi; Zheng, Jia-Ning; Xue, Yun; Ye, Yuan-Feng

    2017-07-01

    Electrochemical behavior of Nd was studied in NaCl-KCl melt on W and Cu electrodes via cyclic voltammetry and chronopotentiometry. Generally, the reduction of Nd3+ takes place in two consecutive steps in molten chlorides, such as LiCl-CaCl2, LiCl-BaCl2, CaCl2-NaCl, LiCl-KCl melts. However, the reduction of Nd3+ ions was found to be through a one-step process: Nd3+ + 3e- → Nd. The co-reduction behavior of Nd3+ and Cu2+ ions and the mechanisms of alloy formation were investigated in NaCl-KCl melt on W electrodes at 988 K (715 °C). Four potential plateaus corresponding to four different kinds of Cu-Nd intermetallic compounds were detected. Cu-Nd alloys were prepared on Cu electrodes at 988 K (715 °C) and 1143 K (870 °C). At 988 K (715 °C), Cu5Nd phase was identified by X-ray diffraction. The morphology and micro-zone chemical analysis of the alloys were characterized by scanning electron microscopy equipped with energy-dispersive spectrometry. The alloy film was observed on the Cu electrodes. Moreover, at 1143 K (870 °C), a globate bulk Cu-Nd alloy with Cu5Nd, Cu4Nd, Cu2Nd, CuNd, and Cu phases, as liquid in the melt, was obtained at the bottom of the crucible.

  7. Hardening behavior after high-temperature solution treatment of Ag-20Pd-12Au-xCu alloys with different Cu contents for dental prosthetic restorations.

    PubMed

    Kim, Yonghwan; Niinomi, Mitsuo; Hieda, Junko; Nakai, Masaaki; Cho, Ken; Fukui, Hisao

    2014-07-01

    Ag-Pd-Au-Cu alloys have been used widely for dental prosthetic applications. Significant enhancement of the mechanical properties of the Ag-20Pd-12Au-14.5Cu alloy as a result of the precipitation of the β' phase through high-temperature solution treatment (ST), which is different from conventional aging treatment in these alloys, has been reported. The relationship between the unique hardening behavior and precipitation of the β' phase in Ag-20Pd-12Au-xCu alloys (x=6.5, 13, 14.5, 17, and 20mass%) subjected to the high-temperature ST at 1123K for 3.6ks was investigated in this study. Unique hardening behavior after the high-temperature ST also occurs in Ag-20Pd-12Au-xCu alloys (x=13, 17, and 20) with precipitation of the β' phase. However, hardening is not observed and the β' phase does not precipitate in the Ag-20Pd-12Au-6.5Cu alloy after the same ST. The tensile strength and 0.2% proof stress also increase in Ag-20Pd-12Au-xCu alloys (x=13, 14.5, 17, and 20) after the high-temperature ST. In addition, these values after the high-temperature ST increase with increasing Cu content in Ag-20Pd-12Au-xCu alloys (x=14.5, 17, and 20). The formation process of the β' phase can be explained in terms of diffusion of Ag and Cu atoms and precipitation of the β' phase. Clarification of the relationship between hardening and precipitation of the β' phase via high-temperature ST is expected to help the development of more effective heat treatments for hardening in Ag-20Pd-12Au-xCu alloys. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Comparison of GRCop-84 to Other Cu Alloys with High Thermal Conductivities

    NASA Technical Reports Server (NTRS)

    deGroh, Henry C., III; Ellis, David L.; Loewenthal, William S.

    2007-01-01

    The mechanical properties of six highly conductive copper alloys, GRCop-84, AMZIRC, GlidCop Al-15, Cu-1Cr-0.1Zr, Cu-0.9Cr, and NARloy-Z were compared. Tests were done on as-received hard drawn material, and after a heat treatment designed to simulate a brazing operation at 935 C. In the as-received condition AMZIRC, GlidCop Al-15, Cu- 1Cr-0.1Zr and Cu-0.9Cr had excellent strengths at temperatures below 500 C. However, the brazing heat treatment substantially decreased the mechanical properties of AMZIRC, Cu-1Cr-0.1Zr, Cu-0.9Cr, and NARloy-Z. The properties of GlidCop Al-15 and GRCop-84 were not significantly affected by the heat treatment. Thus there appear to be advantages to GRCop-84 over AMZIRC, Cu-1Cr-0.1Zr, Cu-0.9Cr, and NARloy-Z if use or processing temperatures greater than 500 C are expected. Ductility was lowest in GlidCop Al-15 and Cu-0.9Cr; reduction in area was particularly low in GlidCop Al-15 above 500 C, and as- received Cu-0.9Cr was brittle between 500 and 650 C. Tensile creep tests were done at 500 and 650 C; the creep properties of GRCop-84 were superior to those of brazed AMZIRC, Cu-1Cr- 0.1Zr, Cu-0.9Cr, and NARloy-Z. In the brazed condition, GRCop-84 was superior to the other alloys due to its greater strength and creep resistance (compared to AMZIRC, Cu-1Cr-0.1Zr, Cu-0.9Cr, and NARloy-Z) and ductility (compared to GlidCop Al-15).

  9. Comparison of GRCop-84 to Other Cu Alloys with High Thermal Conductivities

    NASA Astrophysics Data System (ADS)

    de Groh, Henry C.; Ellis, David L.; Loewenthal, William S.

    2008-08-01

    The mechanical properties of six highly conductive copper alloys, GRCop-84, AMZIRC, GlidCop Al-15, Cu-1Cr-0.1Zr, Cu-0.9Cr, and NARloy-Z were compared. Tests were done on as-received hard drawn material, and after a heat treatment designed to simulate a brazing operation at 935 °C. In the as-received condition AMZIRC, GlidCop Al-15, Cu-1Cr-0.1Zr, and Cu-0.9Cr had excellent strengths at temperatures below 500 °C. However, the brazing heat treatment substantially decreased the mechanical properties of AMZIRC, Cu-1Cr-0.1Zr, Cu-0.9Cr, and NARloy-Z. The properties of GlidCop Al-15 and GRCop-84 were not significantly affected by the heat treatment. Thus there appear to be advantages to GRCop-84 over AMZIRC, Cu-1Cr-0.1Zr, Cu-0.9Cr, and NARloy-Z if use or processing temperatures greater than 500 °C are expected. Ductility was the lowest in GlidCop Al-15 and Cu-0.9Cr; reduction in area was particularly low in GlidCop Al-15 above 500 °C, and as-received Cu-0.9Cr was brittle between 500 and 650 °C. Tensile creep tests were done at 500 and 650 °C; the creep properties of GRCop-84 were superior to those of brazed AMZIRC, Cu-1Cr-0.1Zr, Cu-0.9Cr, and NARloy-Z. In the brazed condition, GRCop-84 was superior to the other alloys due to its greater strength and creep resistance (compared to AMZIRC, Cu-1Cr-0.1Zr, Cu-0.9Cr, and NARloy-Z) and ductility (compared to GlidCop Al-15).

  10. Relationships involving process, microstructure, and properties of weldments of Al-Cu and Al-Cu-Li alloys

    SciTech Connect

    Martukanitz, R.P.; Howell, P.R.

    1996-12-31

    The evolution of microstructure within the heat affected zone for Al-Cu and Al-Cu-Li alloys is qualitatively described in terms of diffusion controlled modifications that result in the minimization of chemical free energy. Coarsening of strengthening precipitate is anticipated at relatively low peak temperatures; whereas, dissolution is expected to dominate the microstructural modifications within the heat affected zone for these alloys. Transmission electron microscopy of alloy 2195-T8 was performed to validate the analysis. Dissolution of {theta}{prime} (Al{sub 2}Cu) was seen to occur within the heat affected zone at temperatures below 220 C. The primary strengthening phase, T{sub 1} (Al{sub 2}CuLi), exhibited partial dissolution at peak temperatures of 320 C. Peak temperatures up to 500 C resulted in partial dissolution of T{sub 1} during heating and growth upon cooling. Positions near the fusion zone interface resulted in complete dissolution of strengthening precipitate and re-precipitation of copper-rich zones upon cooling. The effect of microstructural modifications within the heat affected zone on mechanical properties is discussed in terms of strengthening mechanisms.

  11. Crystallization kinetics of rapidly quenched Cu50Zr50 and Cu46Zr46Al8 glass-forming alloys

    NASA Astrophysics Data System (ADS)

    Kulikova, T. V.; Ryltseva, A. A.; Bykov, V. A.; Estemirova, S. Kh; Shuhyaev, K. Yu

    2017-01-01

    We studied the crystallization processes, the structure and thermal properties of amorphous alloys Cu50Zr50 and Cu46Zr46Al8 in a wide temperature range. Comparative study of the crystallization kinetics of these amorphous alloys was carried out for the first time using multivariate non-linear regression. It was found that mechanisms of the crystallization of studied metallic glasses are substantially different. The binary alloy is crystallized by branched reaction complex in four steps. For the ternary system was proposed two-step kinetic model of the crystallization process with consecutive reactions. The values of the total energy of activation for each crystallization stage reach to Cu50Zr50: E1 (345.2 kJ/mol); E2 (307.9 kJ/mol), E3 (281.1 kJ/mol), E4 (259.51 kJ/mol) and Cu46Zr46Al8: E1 (350.7 kJ/mol); E2 (150.4 kJ/mol).

  12. Investigation of thermal, mechanical and magnetic behaviors of the Cu-11%Al alloy with Ag and Mn additions

    SciTech Connect

    Silva, R.A.G.; Paganotti, A.; Gama, S.; Adorno, A.T.; Carvalho, T.M.; Santos, C.M.A.

    2013-01-15

    The investigation of thermal, mechanical and magnetic behaviors of the Cu-11%Al, Cu-11%Al-3%Ag, Cu-11%Al-10%Mn and Cu-11%Al-10%Mn-3%Ag alloys was made using microhardness measurements, differential scanning calorimetry, X-ray diffractometry, scanning electron microscopy, energy dispersion X-ray spectroscopy and magnetic moment change with applied field measurement. The results indicated that the Mn addition changes the phase stability range, the microhardness values and makes undetectable the eutectoid reaction in annealed Cu-11%Al and Cu-11%Al-3%Ag alloys while the presence of Ag does not modify the phase transformation sequence neither microhardness values of the annealed Cu-11%Al and Cu-11%Al-10%Mn alloys, but it increases the magnetic moment of this latter at about 2.7 times and decreases the rates of eutectoid and peritectoid reactions of the former. - Highlights: Black-Right-Pointing-Pointer The microstructure of Cu-Al alloy is modified in the Ag presence. Black-Right-Pointing-Pointer ({alpha} + {gamma}) phase is stabilized down to room temperature when Ag is added to Cu-Al alloy. Black-Right-Pointing-Pointer Ag-rich phase modifies the magnetic characteristics of Cu-Al-Mn alloy.

  13. Aging Characteristics of Sn-Ag Eutectic Solder Alloy with the Addition of Cu, In, and Mn

    NASA Astrophysics Data System (ADS)

    Ghosh, M.; Kar, Abhijit; Das, S. K.; Ray, A. K.

    2009-10-01

    In the present investigation, three types of solder alloy, i.e., Sn-Ag-Cu, Sn-Ag-In, and Sn-Ag-Cu-Mn, have been prepared and joined with Cu substrate. In the reflowed condition, the joint interface is decorated with Cu6Sn5 intermetallic in all cases. During aging at 100 °C for 50 to 200 hours, Cu3Sn formation took place in the diffusion zone of the Sn-Ag-Cu and Sn-Ag-In vs Cu assembly, which was not observed for the Sn-Ag-Cu-Mn vs Cu joint. Aging also leads to enhancement in the width of reaction layers; however, the growth is sluggish (~134 KJ/mol) for the Sn-Ag-Cu-Mn vs Cu transition joint. In the reflowed condition, the highest shear strength is obtained for the Sn-Ag-Cu-Mn vs Cu joint. Increment in aging time results in decrement in shear strength of the assemblies; yet small reduction is observed for the Sn-Ag-Cu-Mn vs Cu joint. The presence of Mn in the solder alloy is responsible for the difference in microstructure of the Sn-Ag-Cu-Mn solder alloy vs Cu assembly in the reflowed condition, which in turn influences the microstructure of the same after aging with respect to others.

  14. One-pot synthesis of CeO₂-supported Pd-Cu-alloy nanocubes with high catalytic activity.

    PubMed

    Park, Kyu-Hwan; Lee, Young Wook; Kim, Yena; Kang, Shin Wook; Han, Sang Woo

    2013-06-17

    Cerium and nanocubes: CeO₂-supported Pd-Cu-alloy nanocubes (Pd-Cu NCs/CeO₂) with high content and good dispersion of the Pd-Cu NCs were prepared in high yields by heating a solution containing Pd, Cu, and Ce precursors. The prepared Pd-Cu NCs/CeO₂ have excellent catalytic activity and stability toward formic acid electro-oxidation due to the synergism between the Pd-Cu-alloy catalysts and the CeO₂ support. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Optimization of mechanical properties, biocorrosion properties and antibacterial properties of as-cast Ti-Cu alloys.

    PubMed

    Zhang, Erlin; Ren, Jing; Li, Shengyi; Yang, Lei; Qin, Gaowu

    2016-10-21

    Ti-Cu sintered alloys have shown good antibacterial abilities. However, the sintered method (powder metallurgy) is not convenient to produce devices with a complex structure. In this paper, Ti-Cu alloys with 2.0, 3.0 and 4.0 wt.% Cu were prepared in an arc melting furnace and subjected to different heat treatments: solid solution and ageing, to explore the possibility of preparing an antibacterial Ti-Cu alloy by a casting method and to examine the effect of Cu content. Phase identification was conducted on an XRD diffraction meter, and the microstructure was observed by a metallographic microscope, a scanning electron microscope (SEM) with energy disperse spectroscopy (EDS) and transmission electron microscopy (TEM). Microhardness and the compressive property of Ti-Cu alloys were tested, and the corrosion resistance and antibacterial activity were assessed in order to investigate the effect of the Cu content. Results showed that the as-cast Ti-Cu alloys exhibited a very low antibacterial rate against Staphylococcus aureus (S. aureus). Heat treatment improved the antibacterial rate significantly, especially after a solid and ageing treatment (T6). Antibacterial rates as high as 90.33% and 92.57% were observed on Ti-3Cu alloy and Ti-4Cu alloy, respectively. The hardness, the compressive yield strength, the anticorrosion resistance and the antibacterial rate of Ti-Cu alloys increased with an increase of Cu content in all conditions. It was demonstrated that homogeneous distribution and a fine Ti2Cu phase played a very important role in the mechanical property, anticorrosion and antibacterial properties. Furthermore, it should be pointed out that the Cu content should be at least 3 wt.% to obtain good antibacterial properties (>90% antibacterial rate) as well as satisfactory mechanical properties.

  16. Fabrication of single phase p-CuInSe{sub 2} nanowire arrays by electrodeposited into anodic alumina templates

    SciTech Connect

    Cheng, Yu-Song; Lang, Hao-Jan; Houng, Mau-Phon

    2015-10-19

    Single-phase CuInSe{sub 2} nanowire (NW) arrays were prepared at various pH values in a heated electrolyte by using pulse electrodeposition techniques and an anodized aluminum oxide template. X-ray diffraction showed that the CuInSe{sub 2} NW nucleation mechanism received H{sup +} constraints when the NWs were deposited at pH 1.7 with a (112) orientation and annealed at 550 °C. The CuInSe{sub 2} NW band gap was determined to be approximately 1 eV through optical measurements. Transmission electron microscopy showed that at the pH value of 1.7, small particles of the single-phase CuInSe{sub 2} NWs aligned along the crystallographic direction are nucleated to form large particles. Scanning electron microscopy revealed that the NW diameter and the length were 80 nm and 2.3 μm, respectively. From Mott–Schottky and Ohmic contact plots, the CuInSe{sub 2} NWs were found to be p-type semiconductors, and their work function was estimated to be approximately 4.69 eV.

  17. Fabrication of single phase p-CuInSe2 nanowire arrays by electrodeposited into anodic alumina templates

    NASA Astrophysics Data System (ADS)

    Cheng, Yu-Song; Lang, Hao-Jan; Houng, Mau-Phon

    2015-10-01

    Single-phase CuInSe2 nanowire (NW) arrays were prepared at various pH values in a heated electrolyte by using pulse electrodeposition techniques and an anodized aluminum oxide template. X-ray diffraction showed that the CuInSe2 NW nucleation mechanism received H+ constraints when the NWs were deposited at pH 1.7 with a (112) orientation and annealed at 550 °C. The CuInSe2 NW band gap was determined to be approximately 1 eV through optical measurements. Transmission electron microscopy showed that at the pH value of 1.7, small particles of the single-phase CuInSe2 NWs aligned along the crystallographic direction are nucleated to form large particles. Scanning electron microscopy revealed that the NW diameter and the length were 80 nm and 2.3 μm, respectively. From Mott-Schottky and Ohmic contact plots, the CuInSe2 NWs were found to be p-type semiconductors, and their work function was estimated to be approximately 4.69 eV.

  18. Length scale of the dendritic microstructure affecting tensile properties of Al-(Ag)-(Cu) alloys

    NASA Astrophysics Data System (ADS)

    Duarte, Roberto N.; Faria, Jonas D.; Brito, Crystopher; Veríssimo, Nathalia C.; Cheung, Noé; Garcia, Amauri

    2016-12-01

    The dependence of tensile properties on the length scale of the dendritic morphology of Al-Cu, Al-Ag and Al-Ag-Cu alloys is experimentally investigated. These alloys were directionally solidified (DS) under a wide range of cooling rates (Ṫ), permitting extensive microstructural scales to be examined. Experimental growth laws are proposed relating the primary dendritic arm spacing, λ1 to Ṫ and tensile properties to λ1. It is shown that the most significant effect of the scale of λ1 on the tensile properties is that of the ternary alloy, which is attributed to the more homogeneous distribution of the eutectic mixture for smaller λ1 and by the combined reinforcement roles of the intermetallics present in the ternary eutectic: Al2Cu and nonequilibrium Ag3Al.

  19. Cu-Ni nano-alloy: mixed, core-shell or Janus nano-particle?

    PubMed

    Guisbiers, Grégory; Khanal, Subarna; Ruiz-Zepeda, Francisco; Roque de la Puente, Jorge; José-Yacaman, Miguel

    2014-12-21

    Bimetallic nanoparticles like Cu-Ni are particularly attractive due to their magnetic and catalytic properties; however, their properties depend strongly on the structure of the alloy i.e. mixed, core-shell or Janus. To predict the alloy structure, this paper investigates the size and shape effects as well as the surface segregation effect on the Cu-Ni phase diagram. Phase maps have been plotted to determine the mixing/demixing behavior of this alloy according the particle shape. Cu-Ni nanoalloy can form a mixed particle or a Janus one depending on the synthesis temperature. Surface segregation is also considered and reveals a nickel surface-enrichment. Finally, this paper provides a useful roadmap for experimentalists.

  20. Studies on polishing of Ti and Ag-Pd-Cu-Au alloy with five dental abrasives.

    PubMed

    Hirata, T; Nakamura, T; Takashima, F; Maruyama, T; Taira, M; Takahashi, J

    2001-08-01

    Titanium (Ti) and Ag-Pd-Cu-Au alloy were examined for their polishing behaviour by conducting manually controlled polishing tests using five dental abrasives [carborundum point (CR) and silicone points (R1 and R2)] driven by a high torque micromotor with rotational speeds ranging from 2000 to 15 000 r.p.m. Polishing of Ti resulted in less volume of removal upon polishing, a rougher surface and larger loss of abrasives, compared with polishing of Ag-Pd-Cu-Au alloy. Polishing of Ti with a rotational speed of 15 000 r.p.m. led to the largest volume of removal upon polishing, whilst that of 10 000 r.p.m. produced the optimal volume for Ag-Pd-Cu-Au alloy. It was concluded that Ti was much more difficult to polish, requiring special care (e.g. frequent exchange of abrasives). Development of new abrasives for polishing Ti is required.

  1. Ferromagnetic behavior of nanocrystalline Cu-Mn alloy prepared by ball milling

    NASA Astrophysics Data System (ADS)

    Mondal, B. N.; Sardar, G.; Nath, D. N.; Chattopadhyay, P. P.

    2014-12-01

    50Cu-50Mn (wt%) alloy was produced by ball milling. The milling was continued up to 30 h followed by isothermal annealing over a four interval of temperature from 350 to 650 °C held for 1 h. Crystallite size, lattice strain, lattice parameter were determined by Rietveld refinement structure analysis of X-ray diffraction data. The amount of dissolved/precipitated Mn (wt%) after ball milling/milling followed by annealing was calculated by quantative phase analysis (QPA). The increase of coercivity could be attributed to the introduction of lattice strain and reduction of crystallite size as a function of milling time. Electron paramagnetic resonance and superconducting quantum interface device analysis indicate that soft ferromagnetic behavior has been achieved by ball milled and annealed Cu-Mn alloy. The maximum coercivity value of Cu-Mn alloy obtained after annealing at 350 °C for 1 h is 277 Oe.

  2. Structure and Phase Separation in Ultrathin Ag/Cu Amorphous Alloy System

    NASA Astrophysics Data System (ADS)

    Chen, Hao

    2005-03-01

    The structure of disordered metallic alloys is an important but unsolved problem. Previous studies on Ag-Cu system showed that relatively homogeneous solid solutions formed at liquid nitrogen temperature decompose into separate phases or evolve into crystalline structure at a higher temperature. In this research project, we prepared ultra-thin Ag-Cu films on amorphous carbon support by HV magnetron sputtering with both targets. With high energy Ag and Cu atoms bombarding on the carbon substrate, they are forced to form amorphous alloy or nano-crystalline thin film at room temperature. We have investigated the structure of ultra-thin Ag-Cu films by examining their pair distribution function (PDF) using electron diffraction and observed phase separation process directly in STEM images. In the STEM Z-contrast images, since the contrast is directly related to the atomic number (Z) of the components, we can see clearly the phase separation process. Experimental results show that the sample morphology evolutions are different in samples with different thickness, and the phase separation depends on various Ag/Cu atomic ratios. In Ag50Cu50 sample, early stage phase separation is associated with increasing Cu crystallite size, indicates that Cu diffuse out of Ag-Cu solid solution phase.

  3. Recrystallization Behavior of CoCrCuFeNi High-Entropy Alloy

    NASA Astrophysics Data System (ADS)

    Park, Nokeun; Watanabe, Ikuto; Terada, Daisuke; Yokoyama, Yoshihiko; Liaw, Peter K.; Tsuji, Nobuhiro

    2015-04-01

    We investigated the recrystallization behavior of a cold-rolled CoCrCuFeNi high-entropy alloy (HEA). Two different face-centered cubic phases having different chemical compositions and lattice constants in the as-cast specimen have different chemical compositions: One phase was the Cu-lean matrix and the other was the Cu-rich second phase. The second phase remained even after a heat treatment at 1373 K (1100 °C) and Cu enriched more in the Cu-rich second phase. The calculated mixing enthalpies of both Cu-lean and Cu-rich phases in the as-cast and heat-treated specimens explained that Cu partitioning during the heat treatment decreased the mixing enthalpy in both phases. In the specimens 90 pct cold rolled and annealed at 923 K, 973 K, and 1073 K (650 °C, 700 °C, and 800 °C), recrystallization proceeded with increasing the annealing temperature, and ultrafine recrystallized grains with grain sizes around 1 μm could be obtained. The microhardness tended to decrease with increasing the fraction recrystallized, but it was found that the microhardness values of partially recrystallized specimens were much higher than those expected by a simple rule of mixture between the initial and cold-rolled specimens. The reason for the higher hardness was discussed based on the ultrafine grain size, sluggish diffusion expected in HEAs, and two-phase structure in the CoCrCuFeNi alloy.

  4. The combination of precipitation and dispersion hardening in powder metallurgy produced Cu-Ti-Si alloy

    SciTech Connect

    Bozic, D.; Dimcic, O.; Dimcic, B. Cvijovic, I.; Rajkovic, V.

    2008-08-15

    Microstructure and microhardness properties of precipitation hardened Cu-Ti and precipitation/dispersion hardened Cu-Ti-Si alloys have been analyzed. Cu-1.2Ti and Cu-1.2Ti-3TiSi{sub 2} (wt.%) atomized powders were characterized before and after consolidation by HIP (Hot Isostatic Pressing). Rapidly solidified powders and HIP-ed compacts were subsequently subjected to thermal treatment in hydrogen at temperatures between 300 and 600 deg. C. Compared to Cu-Ti powder particles and compacts, obtained by the same procedure, the strengthening effect in Cu-1.2Ti-3TiSi{sub 2} powder particles and compacts was much greater. The binary and ternary powders both reveal properties superior to those of Cu-1.2Ti and Cu-1.2Ti-3TiSi{sub 2} compacts. Microhardness analysis as a function of the aging temperature of Cu-1.2Ti-3TiSi{sub 2} alloy shows an interaction between precipitation and dispersion hardening which offers possibilities for an application at elevated temperatures.

  5. Effect of homogenization process on the hardness of Zn-Al-Cu alloys

    NASA Astrophysics Data System (ADS)

    Villegas-Cardenas, Jose D.; Saucedo-Muñoz, Maribel L.; Lopez-Hirata, Victor M.; De Ita-De la Torre, Antonio; Avila-Davila, Erika O.; Gonzalez-Velazquez, Jorge Luis

    2015-10-01

    The effect of a homogenizing treatment on the hardness of as-cast Zn-Al-Cu alloys was investigated. Eight alloy compositions were prepared and homogenized at 350 °C for 180 h, and their Rockwell "B" hardness was subsequently measured. All the specimens were analyzed by X-ray diffraction and metallographically prepared for observation by optical microscopy and scanning electron microscopy. The results of the present work indicated that the hardness of both alloys (as-cast and homogenized) increased with increasing Al and Cu contents; this increased hardness is likely related to the presence of the θ and τ' phases. A regression equation was obtained to determine the hardness of the homogenized alloys as a function of their chemical composition and processing parameters, such as homogenization time and temperature, used in their preparation.

  6. Aqueous sodium chloride induced intergranular corrosion of Al-Li-Cu alloys

    NASA Technical Reports Server (NTRS)

    Pizzo, P. P.; Daeschner, D. L.

    1986-01-01

    Two methods have been explored to assess the susceptibility of Al-Li-Cu alloys to intergranular corrosion in aqueous sodium chloride solution. They are: (1) constant extension rate testing with and without alternate-immersion preexposure and (2) metallographic examination after exposure to a NaCl-H2O2 corrosive solution per Mil-H-6088F. Intergranular corrosion was found to occur in both powder and ingot metallurgy alloys of similar composition, using both methods. Underaging rendered the alloys most susceptible. The results correlate to stress-corrosion data generated in conventional time-to-failure and crack growth-rate tests. Alternate-immersion preexposure may be a reliable means to assess stress corrosion susceptibility of Al-Li-Cu alloys.

  7. Study of CoTa alloy as barrier layer for Cu/low-k interconnects

    NASA Astrophysics Data System (ADS)

    Wang, Xu; Liu, Lin-Tao; He, Peng; Qu, Xin-Ping; Zhang, Jing; Wei, Shuhua; Mankelevich, Yuri A.; Baklanov, Mikhail R.

    2017-10-01

    CoTa alloy films as diffusion barriers for Cu/low-k interconnects are studied. Crystalline structure, thermal stability, barrier and sealing properties on low-k dielectric of CoTa alloys with different atomic ratios between Co and Ta are studied using different techniques. It is demonstrated that CoTa alloys with proper content and thickness can be considered as candidates to act as a barrier layer for Cu/low-k interconnects with acceptable thermal stability and resistivity. However, ultralow-k organosilicate based dielectrics with k  =  2.25 and pore size about 2 nm can be sealed by this barrier against penetration of neutral molecules only when the CoTa alloy thickness is larger than 3 nm. Correlation of the barrier performance with low-k pore size is demonstrated.

  8. Creep Testing of High-Temperature Cu-8 Cr-4 Nb Alloy Completed

    NASA Technical Reports Server (NTRS)

    1995-01-01

    A Cu-8 at.% Cr-4 at.% Nb (Cu-8 Cr-4 Nb) alloy is under development for high-temperature, high heatflux applications, such as actively cooled, hypersonic vehicle heat exchangers and rocket engine combustion chambers. Cu-8 Cr-4 Nb offers a superior combination of strength and conductivity. It has also shown exceptional low-cycle fatigue properties. Following preliminary testing to determine the best processing route, a more detailed testing program was initiated to determine the creep lives and creep rates of Cu-8 Cr-4 Nb alloy specimens produced by extrusion. Testing was conducted at the NASA Lewis Research Center with constant-load vacuum creep units. Considering expected operating temperatures and mission lives, we developed a test matrix to accurately determine the creep properties of Cu-8 Cr-4 Nb between 500 and 800 C. Six bars of Cu-8 Cr-4 Nb were extruded. From these bars, 54 creep samples were machined and tested. The figure on the left shows the steady-state, or second-stage, creep rates for the samples. Comparison data for NARloy-Z (Cu-3 wt % Ag-0.5 wt % Zr), the alloy currently used in combustion chamber liners, were not unavailable. Therefore the steady-state creep rates for Cu at similar temperatures are presented. As expected, in comparison to pure Cu, the creep rates for Cu-8 Cr-4 Nb are much lower. The lives of the samples are presented in the figure on the right. As shown, Cu-8 Cr-4 Nb at 800 C is comparable to NARloy-Z at 648 C. At equivalent temperatures, Cu-8 Cr-4 Nb enjoys a 20 to 50 percent advantage in stress for a given life and 1 to 3 orders of magnitude greater life at a given stress. The improved properties allow for design tradeoffs and improvements in new and existing heat exchangers such as the next generation of combustion chamber liners. Average creep rates for Cu-8 Cr-4 Nb and pure Cu are shown. Average creep lives for Cu-8 Cr- 4 Nb and NARloy-Z are also shown. Currently, two companies are interested in the commercial usage of the Cu

  9. Relationship between microstructure, cytotoxicity and corrosion properties of a Cu-Al-Ni shape memory alloy.

    PubMed

    Colić, Miodrag; Rudolf, Rebeka; Stamenković, Dragoslav; Anzel, Ivan; Vucević, Dragana; Jenko, Monika; Lazić, Vojkan; Lojen, Gorazd

    2010-01-01

    Cu-Al-Ni shape memory alloys (SMAs) have been investigated as materials for medical devices, but their biomedical application is still limited. The aim of this work was to compare the microstructure, corrosion and cytotoxicity in vitro of a Cu-Al-Ni SMA. Rapidly solidified (RS) thin ribbons, manufactured via melt spinning, were used for the tests. The control alloy was a permanent mould casting of the same composition, but without shape memory effect. The results show that RS ribbons are significantly more resistant to corrosion compared with the control alloy, as judged by the lesser release of Cu and Ni into the conditioning medium. These results correlate with the finding that RS ribbons were not cytotoxic to L929 mouse fibroblasts and rat thymocytes. In addition, the RS ribbon conditioning medium inhibited cellular proliferation and IL-2 production by activated rat splenocytes to a much lesser extent. The inhibitory effects were almost completely abolished by conditioning the RS ribbons in culture medium for 4 weeks. Microstructural analysis showed that RS ribbons are martensitic, with boron particles as a minor phase. In contrast, the control Cu-Al-Ni alloy had a complex multiphase microstructure. Examination of the alloy surfaces after conditioning by energy dispersive X-ray and Auger electron spectroscopy showed the formation of Cu and Al oxide layers and confirmed that the metals in RS ribbons are less susceptible to oxidation and corrosion compared with the control alloy. In conclusion, these results suggest that rapid solidification significantly improves the corrosion stability and biocompatibility in vitro of Cu-Al-Ni SMA ribbons.

  10. Tensile strength of thermomechanically processed Cu-9Ni-6Sn alloys

    SciTech Connect

    Rhu, J.C.; Kim, S.S.; Jung, Y.C.; Han, S.Z.; Kim, C.J.

    1999-10-01

    The tensile properties of Cu-9Ni-6Sn alloys with different swaging amounts of 64, 77, and 95 pct, either solutionized and aged (S/A), were examined as a function of aging time. It was found that the aging response of Cu-9Ni-6Sn alloys varied greatly depending on the prior solution heat treatment before aging and/or different swaging amounts. The swaged S/A Cu-9Ni-6Sn alloys showed a multistage increase in tensile strength with respect to aging time, probably due to the sequential occurrence of spinodal decomposition, formation of metastable {gamma}{center{underscore}dot} precipitates, and recrystallization. The effect of different swaging amounts, ranging from 64 to 95 pct, was minimal on the aging response of S/A specimens. The prior cold working, however, appeared to favor the spinodal strengthening, comparing unswaged and swaged S/A Cu-9Ni-6Sn alloys. In 95 pct swaged D/A Cu-9Ni-6Sn alloys, the level of hardening was much less sensitive to aging time. A complex interaction between the reduction in dislocation density, the formation of equilibrium precipitates, and the reduction of Sn content in the Sn-rich segregates during an aging process is believed to be responsible for such a lean sensitivity. The increases in tensile strength of 64 and 77 pct swaged D/A Cu-9Ni-6Sn alloys were found to be much steeper than that in the 95 pct counterparts in the early and intermediate stages of aging, which is believed to be related to the relative contribution from work hardening and precipitation hardening to the strength level of D/A specimens.

  11. Processing and Consolidation of Nanocrystalline Cu-Zn-Ti-Fe-Cr High-Entropy Alloys via Mechanical Alloying

    NASA Astrophysics Data System (ADS)

    Mridha, Sanghita; Samal, Sumanta; Khan, P. Yousaf; Biswas, Krishanu; Govind

    2013-10-01

    In the current investigation, nanocrystalline multicomponent high-entropy alloys (HEAs) have been synthesized in the Cu x Zn y Ti20Fe20Cr20 system ( x/ y = 1/0, 3/1, 1; and x + y = 40) by mechanical alloying and subsequently consolidated using spark plasma sintering (SPS) in argon atmosphere at a pressure of 50 MPa. A detailed X-ray diffraction and transmission electron microscopy study reveals the presence of both FCC copper solid-solution, (Cu)ss and BCC chromium solid-solution, (Cr)ss phases in both the mechanically alloyed powders as well as the sintered compacts. The phase formation and stability of the sintered multicomponent Cu x Zn y Ti20Fe20Cr20 with x/ y = 3/1 and x + y = 40 pellet have been studied at different sintering temperatures, i.e., 873 K, 973 K, 1073 K, and 1173 K (600 °C, 700 °C, 800 °C, and 900 °C). The important findings include that high Vickers bulk hardness of around 6 GPa and relative density of around 95 pct reported in the Cu x Zn y Ti20Fe20Cr20 with x/ y = 3/1 and x + y = 40 HEAs, SPSed at 1173 K (900 °C). The formation, consolidation, and microstructural details are analyzed critically and discussed.

  12. High resolution electron microscopy study of a high Cu variant of Weldalite (tm) 049 and a high strength Al-Cu-Ag-Mg-Zr alloy

    NASA Technical Reports Server (NTRS)

    Herring, R. A.; Gayle, Frank W.; Pickens, Joseph R.

    1991-01-01

    Weldalite (trademark) 049 is an Al-Cu-Li-Ag-Mg alloy that is strengthened in artificially aged tempers primarily by very thin plate-like precipitates lying on the set of (111) matrix planes. This precipitate might be expected to be the T(sub 1) phase, Al2CuLi, which has been observed in Al-Cu-Li alloys. However, in several ways this precipitate is similar to the omega phase which also appears as the set of (111) planes plates and is found in Al-Cu-Ag-Mg alloys. The study was undertaken to identify the set of (111) planes precipitate or precipitates in Weldalite (trademark) 049 in the T8 (stretched and artificially aged) temper, and to determine whether T(sub 1), omega, or some other phase is primarily responsible for the high strength (i.e., 700 MPa tensile strength) in this Al-Cu-Li-Ag-Mg alloy.

  13. Investigation of the martensitic transformation of (Cu-Zn-Ni) shape memory alloys

    NASA Astrophysics Data System (ADS)

    Naat, N. A.; Mohammed, M. A.

    2017-02-01

    (Cu-Zn-Ni) shape memory alloy with different percent have been prepared by using high frequency induction furnace under argon atmosphere. All of the specimens obtained from this alloys were heated in furnace for (15 minutes at 865°C) for homogenization and quenched in iced-water. Comparisons has been made with data obtained via differential scanning calorimetry (DSC) and energy-dispersive X-ray spectroscopy (EDS). The metallographic analyses were carried out by using optical microscopy (OM).

  14. LACBED characterization of dislocations in Cu-Al-Ni shape memory alloys processed by powder metallurgy

    NASA Astrophysics Data System (ADS)

    Rodriguez, P. P.; Ibarra, A.; San Jean, J.; Morniro, J. P.; No, M. L.

    2003-10-01

    Powder metallurgy Cu-AI-Ni shape memory alloys show excellent thermomechanical properties, being the fracture behavior close to the one observed in single crystals. However, the microstructural mechanisms responsible of such behavior are still under study. In this paper we present the characterization of the dislocations present in these alloys by Large Angle Convergent Beam Electron Diffraction (LACBED) in two different stages of the elaboration process: after HIP compaction and after hot rolling.

  15. Diffusion of boron in copper and a AuCu alloy

    SciTech Connect

    Hasaka, Masayuki; Morimura, Takao; Uchiyama, Yasuo; Kondo, Shinichiro . Dept. of Materials Science and Engineering); Hisatsune, Kunihiro . Dept. of Dental Materials Science)

    1993-10-01

    Dental gold alloys exhibit age hardening characteristics. This kinetic phenomenon is sometimes due to ordering of the L1[sub 0] type, which is related to diffusion. By using secondary ion mass spectroscopy, the present paper elucidates the diffusion behavior of boron in the pure copper and the AuCu alloy which changes from the disordered state to the L1[sub 0] ordered state at 683K.

  16. Thermal storage/discharge performances of Cu-Si alloy for solar thermochemical process

    NASA Astrophysics Data System (ADS)

    Gokon, Nobuyuki; Yamaguchi, Tomoya; Cho, Hyun-seok; Bellan, Selvan; Hatamachi, Tsuyoshi; Kodama, Tatsuya

    2017-06-01

    The present authors (Niigata University, Japan) have developed a tubular reactor system using novel "double-walled" reactor/receiver tubes with carbonate molten-salt thermal storage as a phase change material (PCM) for solar reforming of natural gas and with Al-Si alloy thermal storage as a PCM for solar air receiver to produce high-temperature air. For both of the cases, the high heat capacity and large latent heat (heat of solidification) of the PCM phase circumvents the rapid temperature change of the reactor/receiver tubes at high temperatures under variable and uncontinuous characteristics of solar radiation. In this study, we examined cyclic properties of thermal storage/discharge for Cu-Si alloy in air stream in order to evaluate a potentiality of Cu-Si alloy as a PCM thermal storage material. Temperature-increasing performances of Cu-Si alloy are measured during thermal storage (or heat-charge) mode and during cooling (or heat-discharge) mode. A oxidation state of the Cu-Si alloy after the cyclic reaction was evaluated by using electron probe micro analyzer (EPMA).

  17. Effects of Pulse Electromagnetic Field on Corrosion Resistance of Al-5 % Cu Alloy

    NASA Astrophysics Data System (ADS)

    Wang, B.; Tang, L. D.; Qi, J. G.; Wang, J. Z.

    2013-03-01

    It was investigated that corrosion resistance of Al-5 % Cu alloy was influenced by pulse electromagnetic field (PEMF). The morphologies were observed by scanning election microscopy (SEM). The corrosion behaviors were investigated by potentiodynamic polarization tests and immersion tests. The results indicated that corrosion resistance of samples could be increased by using pulse electromagnetic field, moreover, the optimum parameter of pulse electromagnetic field in this experiment was showed as follows: 500 V, 3 Hz, 30 s. Decreasing the quantity of eutectic in grain boundaries and refining the grains were main causations for increasing corrosion resistance of Al-5 % Cu alloy with pulse electromagnetic field.

  18. H2 and CO oxidation process at the three-phase boundary of Cu-ceria cermet anode for solid oxide fuel cell

    NASA Astrophysics Data System (ADS)

    Zheng, Minghao; Wang, Shuang; Li, Mei; Xia, Changrong

    2017-03-01

    Cu-ceria cermets have been widely investigated as the anode materials for solid oxide fuel cells (SOFCs) that operated with hydrocarbon fuels. However, the anode reaction processes are not clear yet, especially those at the ceria-Cu-gas three phase boundary (3 PB). This work investigates samaria-doped ceria (SDC)-Cu-gas 3 PB reaction kinetics for the oxidation of H2 and CO, the products from hydrocarbons via external and internal reforming. Electrochemical conductivity relaxation measurement demonstrates that Cu is a synergistic catalyst that can significantly increase the reaction rate. The reaction at 3 PB contributes 81.3/66.8% of H2/CO oxidation when 5.4% SDC surface is covered with Cu particles. Combining with AC impedance analysis, elementary steps are proposed for the reaction at 3 PB. Water vapor combining to oxygen vacancy and carbon monoxide transforming to carbonate are the rate-determining steps for the oxidation of H2 and CO, respectively. Cu-SDC has shown much higher catalytic activity, i.e. about fivefold reaction rate, for the oxidation of CO than H2. In addition, Cu-SDC electrodes exhibit lower interfacial polarization resistance and lower activation energy for the electrochemical oxidation of CO than H2. Consequently, CO is easier to be oxidized than H2 when the Cu-ceria anode is fueled with syngas, the reforming product from hydrocarbons.

  19. A Review of TiNiPdCu Alloy System for High Temperature Shape Memory Applications

    NASA Astrophysics Data System (ADS)

    Khan, M. Imran; Kim, Hee Young; Miyazaki, Shuichi

    2015-06-01

    High temperature shape memory alloys (HTSMAs) are important smart materials and possess a significant potential to improve many engineering systems. Many TiNi-based high temperature ternary alloy systems have been reported in literature including TiNiPd, TiNiPt, TiNiZr, TiNiAu, TiNiHf, etc. Some quaternary additions of certain elements in the above systems have been successful to further improve many important shape memory and mechanical properties. The success criteria for an HTSMA become strict in terms of its cyclic stability, maximum recoverable strain, creep resistance, and corrosion resistance at high temperatures. TiNiPdCu alloy system has been recently proposed as a promising HTSMA. Unique nanoscaled precipitates formed in TiNiPdCu-based HTSMAs are found to be stable at temperatures above 773 K, while keeping the benefits of ease of fabrication. It is expected that this alloy system possesses significant potential especially for the high temperature shape memory applications. Till now many research reports have been published on this alloy system. In the present work, a comprehensive review of the TiNiPdCu system is presented in terms of thermomechanical behavior, nanoscale precipitation mechanism, microstructural features, high temperature shape memory and mechanical properties, and the important parameters to control the high temperature performance of these alloys.

  20. Solubility and magnetic properties enhancement in bi-phase nanostructure Cu-Fe-Mn alloy

    NASA Astrophysics Data System (ADS)

    Mondal, B. N.; Basumallick, A.; Nath, D. N.; Chattopadhyay, P. P.

    2013-09-01

    In order to improve solubility and magnetic properties, the ball milling technology was used for the production of 50Cu-40Fe-10Mn (wt%) alloy. The effect of Mn content on the microstructure and magnetic properties of Cu-Fe alloy was also investigated in detail. Microstructure and magnetic properties of the alloy were analyzed by X-ray diffraction, differential scanning calorimetry, high resolution transmission electron microscopy and superconducting quantum interface device magnetometry. The results showed that a complete solid solution of the alloy was produced after 30 h of milling. Quantitative phase analysis of X-ray diffraction data revealed that the milled alloy obtained after isothermal annealing at 550 °C for 1 h consisted of Cu (54.52 wt%), α-Fe (36.49 wt%) and MnO (8.99 wt%). The milled alloy obtained after annealing at 450 °C for 1 h leads to the maximum values of magnetic properties such as coercivity=438 Oe, remanent magnetization=14.3 emu/g, and saturation magnetization=51 emu/g.

  1. The effects of Bi alloying in Cu delafossites: A density functional theory study

    NASA Astrophysics Data System (ADS)

    Huda, Muhammad N.; Yan, Yanfa; Al-Jassim, Mowafak M.

    2011-06-01

    Recently, Cu delafossites, CuMO2, have received much attention as photo-catalysts for hydrogen production by water splitting due to their unique properties such as stability in most aqueous solutions and p-type conductivity with excellent hole mobility. However, due to their large optical bandgaps, they can absorb sun light only in the ultraviolet region. Hence, it is necessary to tailor their optical properties to enhance their optical absorption in the visible light regions. In this paper, we report on the effects of Bi alloying on the electronic and optical properties of Cu delafossites by density functional theory. We find that Bi alloying can lead to improved optical absorption as compared to the pristine Cu delafossites. We further find that the lone pair Bi-6s electrons create occupied delocalized anti-bonding states on the top of the valence band, leading to further improved hole mobility.

  2. Direct observation of atomic-scale origins of local dissolution in Al-Cu-Mg alloys

    NASA Astrophysics Data System (ADS)

    Zhang, B.; Wang, J.; Wu, B.; Oguzie, E. E.; Luo, K.; Ma, X. L.

    2016-12-01

    Atomistic chemical inhomogeneities are anticipated to induce dissimilarities in surface potentials, which control corrosion initiation of alloys at the atomic scale. Precise understanding of corrosion is therefore hampered by lack of definite information describing how atomistic heterogeneities regulate the process. Here, using high-angle annular dark-field (HAADF) scanning transmission electron microscope (STEM) and electron energy loss spectroscopy (EELS) techniques, we systematically analyzed the Al20Cu2Mn3 second phase of 2024Al and successfully observed that atomic-scale segregation of Cu at defect sites induced preferential dissolution of the adjacent zones. We define an “atomic-scale galvanic cell”, composed of zones rich in Cu and its surrounding matrix. Our findings provide vital information linking atomic-scale microstructure and pitting mechanism, particularly for Al-Cu-Mg alloys. The resolution achieved also enables understanding of dealloying mechanisms and further streamlines our comprehension of the concept of general corrosion.

  3. Vibrational properties of Cu(100)-c(2×2)-Pd surface and subsurface alloys

    NASA Astrophysics Data System (ADS)

    Sklyadneva, I. Yu.; Rusina, G. G.; Chulkov, E. V.

    2003-07-01

    Using interaction potentials from the embedded-atom method we investigated the structural and vibrational properties of a Cu(100)-c(2×2)-Pd surface alloy and an underlayer c(2×2) alloy with a mixed CuPd second layer. The calculated surface phonon frequencies are in agreement with the experimental values obtained by electron energy-loss spectroscopy. From the calculated local phonon densities of states we find that surface effects are most pronounced in the first two layers for both systems studied. The results also indicate a very strong Pd-Cu bonding accompanied by a weaker bonding of the Cu surface atoms to their nearest neighbors. This has considerable influence on the surface phonon frequencies.

  4. Direct observation of atomic-scale origins of local dissolution in Al-Cu-Mg alloys

    PubMed Central

    Zhang, B.; Wang, J.; Wu, B.; Oguzie, E. E.; Luo, K.; Ma, X. L.

    2016-01-01

    Atomistic chemical inhomogeneities are anticipated to induce dissimilarities in surface potentials, which control corrosion initiation of alloys at the atomic scale. Precise understanding of corrosion is therefore hampered by lack of definite information describing how atomistic heterogeneities regulate the process. Here, using high-angle annular dark-field (HAADF) scanning transmission electron microscope (STEM) and electron energy loss spectroscopy (EELS) techniques, we systematically analyzed the Al20Cu2Mn3 second phase of 2024Al and successfully observed that atomic-scale segregation of Cu at defect sites induced preferential dissolution of the adjacent zones. We define an “atomic-scale galvanic cell”, composed of zones rich in Cu and its surrounding matrix. Our findings provide vital information linking atomic-scale microstructure and pitting mechanism, particularly for Al-Cu-Mg alloys. The resolution achieved also enables understanding of dealloying mechanisms and further streamlines our comprehension of the concept of general corrosion. PMID:28000750

  5. Direct observation of atomic-scale origins of local dissolution in Al-Cu-Mg alloys.

    PubMed

    Zhang, B; Wang, J; Wu, B; Oguzie, E E; Luo, K; Ma, X L

    2016-12-21

    Atomistic chemical inhomogeneities are anticipated to induce dissimilarities in surface potentials, which control corrosion initiation of alloys at the atomic scale. Precise understanding of corrosion is therefore hampered by lack of definite information describing how atomistic heterogeneities regulate the process. Here, using high-angle annular dark-field (HAADF) scanning transmission electron microscope (STEM) and electron energy loss spectroscopy (EELS) techniques, we systematically analyzed the Al20Cu2Mn3 second phase of 2024Al and successfully observed that atomic-scale segregation of Cu at defect sites induced preferential dissolution of the adjacent zones. We define an "atomic-scale galvanic cell", composed of zones rich in Cu and its surrounding matrix. Our findings provide vital information linking atomic-scale microstructure and pitting mechanism, particularly for Al-Cu-Mg alloys. The resolution achieved also enables understanding of dealloying mechanisms and further streamlines our comprehension of the concept of general corrosion.

  6. Preparation and optical properties of silica Ag-Cu alloy core-shell composite colloids

    SciTech Connect

    Zhang Jianhui Liu Huaiyong; Wang Zhenlin; Ming Naiben

    2007-04-15

    The silica Ag-Cu alloy core-shell composite colloids have been successfully synthesized by an electroless plating approach to explore the possibility of modifying the plasmon resonance at the nanoshell surface by varying the metal nanoshell composition for the first time. The surface plasmon resonance of the composite colloids increases in intensity and shifts towards longer, then shorter wavelengths as the Cu/Ag ratio in the alloy shell is increased. The variations in intensity of the surface plasmon resonance with the Cu/Ag ratio obviously affect the Raman bands of the silica colloid core. The report here may supply a new technique to effectively modify the surface plasmon resonance. - Graphical abstract: The silica Ag-Cu alloy core-shell colloids have been successfully synthesized to explore the possibility of modifying the surface plasmon resonance (SPR) by varying the metal nanoshell composition for the first time. Varying the Cu/Ag ratio of the alloy nanoshell has obvious influences on the SPR of the composite colloids and the Raman bands of the amorphous silica core.

  7. Kinetic limitations in surface alloy formation: PtCu/Ru(0001)

    NASA Astrophysics Data System (ADS)

    Engstfeld, A. K.; Jung, C. K.; Behm, R. J.

    2016-01-01

    We have systematically investigated the structure and structure formation of two-dimensional PtCu monolayer surface alloys on Ru(0001) as model systems for bimetallic PtCu catalysts and surfaces by scanning tunneling microscopy (STM). The surface alloys were prepared by deposition of Pt and Cu on Ru(0001) and thermal intermixing; different procedures were developed and tested to produce bimetallic surfaces with homogeneous structure, including also a homogeneous distribution of the different surface species, while at the same time intermixing with the Ru(0001) substrate should be inhibited. STM imaging revealed that for Pt concentrations below 65% surface alloys with homogeneous distribution could be formed, while at higher concentrations in the mixed phase, up to 82%, pure Pt or Pt-rich surface areas were formed as well. At Pt contents of 0.20 < xPt < 0.65, the PtxCu1 -x/Ru(0001) surface alloys were pseudomorphic, while lower Pt contents resulted in triangular dislocation line patterns. Also at xPt > 0.65 line structures were observed, but of different nature. The distribution of surface atoms in the mixed phase was evaluated from STM images with chemical contrast, the related short-range order parameters were determined. The resulting structures and their energetics, the influence of different deposition and annealing procedures and the suitability of these surfaces as model systems for studies of the surface chemistry of bimetallic PtCu surfaces are discussed.

  8. Pressure- and Temperature-Dependent Study of Heusler Alloys Cu2MGa (M = Cr and V)

    NASA Astrophysics Data System (ADS)

    Gupta, Dinesh C.; Ghosh, Sukriti

    2017-04-01

    Full-potential computation of the electronic, magnetic, elastic and thermodynamic properties of Cu2MGa (M = Cr and V) alloys has been performed in the most stable Fm-3 m phase. The equilibrium lattice parameter is 5.9660 Å for Cu2CrGa and 5.9629 Å for Cu2VGa in the stable state. The application of mBJ potential has also found no energy gap in these alloys in either of the spin channels, hence they are metallic. The total and partial density of states, second-order elastic constants and their combinations are computed to show the electronic, magnetic, stability and brittle or ductile nature of these alloys, which are reported for the first time. Cauchy's pressure and Pugh's index predict Cu2CrGa to be brittle and Cu2VGa to be ductile. Both the materials are stiff enough to break. We have found that both the compounds are anisotropic, ferromagnetic and metallic in nature. We have used quasi-harmonic approximations to study the pressure and temperature variation of the thermodynamic properties of these alloys.

  9. Calculation and measurement of helium generation and solid transmutations in Cu-Zn-Ni alloys

    SciTech Connect

    Greenwood, L.R.; Oliver, B.M.; Garner, F.A.; Muroga, T.

    1998-03-01

    A method was recently proposed by Garner and Greenwood that would allow the separation of the effects of solid and gaseous transmutation for Cu-Zn-Ni alloys. Pure copper produces zinc and nickel during neutron irradiation. {sup 63}Cu transmutes to {sup 64}Ni and {sup 64}Zn, in about a 2-to-1 ratio, and {sup 65}Cu transmutes to {sup 66}Zn. The {sup 64}Zn further transmutes to {sup 65}Zn which has been shown to have a high thermal neutron (n,{alpha}) cross-section. Since a three-step reaction sequence is required for natural copper, the amount of helium produced is much smaller than would be produced for the two-step, well-known {sup 58}Ni (n,{gamma}) {sup 59}Ni (n,{alpha}) reaction sequence. The addition of natural Zn and Ni to copper leads to greatly increased helium production in neutron spectra with a significant thermal component. Using a suitable Cu-Zn-Ni alloy matrix and comparative irradiation of thermal neutron-shielded and unshielded specimens, it should be possible to distinguish the separate influences of the solid and gaseous transmutants. Whereas helium generation rates have been previously measured for natural nickel and copper, they have not been measured for natural Zn or Cu-Ni-Zn alloys. The (N,{alpha}) cross section for {sup 65}Zn was inferred from helium measurements made with natural copper. By comparing helium production in Cu and Cu-Zn alloys, this cross section can be determined more accurately. In the current study, both the solid and helium transmutants were measured for Cu, Cu-5Ni, Cu-3.5Zn and Cu-5Ni-2Zn, irradiated in each of two positions in the HFIR JP-23 test. Highly accurate helium measurements were performed on these materials by isotope dilution mass spectrometry using a facility that was recently moved from Rockwell International to PNNL. It is shown that both the helium and solid transmutants for Cu-zn-Ni alloys can be calculated with reasonable certainty, allowing the development of a transmutation experiment as proposed by

  10. Characterization of the Corrosion Behavior of High Damping Alloys in Seawater.

    DTIC Science & Technology

    1987-06-01

    the potential is increased, current increases, due to anodic dissolution . However, in some cases, as the specimen is scanned anodically, an oxide...34baseline" alloys were examined during this research. The nominal compositions of the high damping alloys are as follows: Delta Alloy C - 73.0% Cu, 21.0... ferritic stainless steel composition) are 72 ..... ..... presented in Figures 44 and 45, surfaces in Figures 46 to 51. Using the PDP and LPM plots (k

  11. Vacuum Brazing TC4 Titanium Alloy to 304 Stainless Steel with Cu-Ti-Ni-Zr-V Amorphous Alloy Foil

    NASA Astrophysics Data System (ADS)

    Dong, Honggang; Yang, Zhonglin; Wang, Zengrui; Deng, Dewei; Dong, Chuang

    2014-10-01

    Dissimilar metal vacuum brazing between TC4 titanium alloy and 304 stainless steel was conducted with newly designed Cu-Ti-Ni-Zr-V amorphous alloy foils as filler metals. Solid joints were obtained due to excellent compatibility between the filler metal and stainless steel substrate. Partial dissolution of stainless steel substrate occurred during brazing. The shear strength of the joint brazed with Cu43.75Ti37.5Ni6.25Zr6.25V6.25 foil was 105 MPa and that with Cu37.5Ti25Ni12.5Zr12.5V12.5 was 116 MPa. All the joints fractured through the gray layer in the brazed seam, revealing brittle fracture features. Cr4Ti, Cu0.8FeTi, Fe8TiZr3 and Al2NiTi3C compounds were found in the fractured joint brazed with Cu43.75Ti37.5Ni6.25Zr6.25V6.25 foil, and Fe2Ti, TiCu, Fe8TiZr3 and NiTi0.8Zr0.3 compounds were detected in the joint brazed with Cu37.5Ti25Ni12.5Zr12.5V12.5 foil. The existence of Cr-Ti, Fe-Ti, Cu-Fe-Ti, and Fe-Ti-V intermetallic compounds in the brazed seam caused fracture of the resultant joints.

  12. Determination of sulfuric acid concentration for anti-cavitation characteristics of Al alloy by two step anodizing process to forming nano porous.

    PubMed

    Lee, Seung-Jun; Kim, Seong-Kweon; Jeong, Jae-Yong; Kim, Seong-Jong

    2014-12-01

    Al alloy is a highly active metal but forms a protective oxide film having high corrosion resistance in atmosphere environment. However, the oxide film is not suitable for practical use, since the thickness of the film is not uniform and it is severly altered with formation conditions. This study focused on developing an aluminum anodizing layer having hardness, corrosion resistance and abrasion resistance equivalent to a commercial grade protective layer. Aluminum anodizing layer was produced by two-step aluminum anodizing oxide (AAO) process with different sulfuric acid concentrations, and the cavitation characteristics of the anodized coating layer was investigated. In hardness measurement, the anodized coating layer produced with 15 vol.% of sulfuric acid condition had the highest value of hardness but exhibited poor cavitation resistance due to being more brittle than those with other conditions. The 10 vol.% of sulfuric acid condition was thus considered to be the optimum condition as it had the lowest weight loss and damage depth.

  13. Wetting of TiC by Al-Cu alloys and interfacial characterization.

    PubMed

    Contreras, A

    2007-07-01

    The wetting behavior and the interfacial reactions that occurred between molten Al-Cu alloys (1, 4, 8, 20, 33, and 100 wt% Cu) and solid TiC substrates were studied by the sessile drop technique in the temperature range of 800-1130 degrees C. The effect of wetting behavior on the interfacial reaction layer was studied. All the Al-Cu alloys react with TiC at the interface forming an extensive reaction layer. The interface thickness varied with the samples, and depends on the temperature, chemical composition of the alloy and the time of the test. Wetting increases with increasing concentration of copper in the Al-Cu alloy at 800 and 900 degrees C. In contrast, at higher temperature such as 1000 degrees C wetting decreases with increasing copper content. The spreading kinetics and the work of adhesion were evaluated. The high values of activation energies indicated that spreading is not a simple viscosity controlled phenomenon but is a chemical reaction process. The spreading of the aluminum drop is observed to occur according to the formation of Al4C3, CuAl2O4, CuAl2, TiCux mainly, leading to a decreases in the contact angle. As the contact angle decreases the work of adhesion increases with increasing temperature. Al-Cu/TiC assemblies showed cohesive fracture corresponding to a strong interface. However, using pure Cu the adhesion work is poor, and the percentage of cohesion work is also too low (27-34%).

  14. Three-dimensional SnO2/carbon on Cu foam for high-performance lithium ion battery anodes

    NASA Astrophysics Data System (ADS)

    Chen, Weimin; Maloney, Scott; Wang, Wenyong

    2016-10-01

    SnO2 is an attractive anode material for lithium-ion batteries (LIBs) due to its high theoretical specific capacity (1491 mAh g-1), low cost, and environmental benignity. The main challenges for SnO2 anodes are their low intrinsic conductivity and poor cycling stability associated with their large volume changes during the charge and discharge process. Here, we present a simple chemical vapor deposition method to fabricate three-dimensional SnO2/carbon on Cu foam electrodes for LIBs. Such a three-dimensional electrode combines multiple advantages, including a continuous electrically conductive network, short pathways for electron transport and ion diffusion, and porous space to allow for the volume expansion of SnO2 nanoparticles. With this anode, superior electrochemical performance is achieved with a high reversible specific capacity of 1171 mAh g-1 at a current density of 100 mA g-1. A stable cycling performance as well as an excellent rate capability is also achieved. These outstanding lithium-storage properties suggest the strategy is a reliable approach for fabricating high-performance LIB electrodes.

  15. Effect of prior aging and flat rooling on the structure and magnetic properties of alloys of the Fe-Cr-Co-Cu system

    NASA Astrophysics Data System (ADS)

    Samarin, B. A.; Kolchin, A. E.; Kal'ner, Yu. V.

    1986-09-01

    In alloys based on Fe-33% Cr-12% Co-2% Cu alloyed with 1% Al (alloy 2) or 1.5% Nb (alloy 3) the temperature for quenching to α-solid solution is reduced from 1050 (alloy 1) to 1000 (alloy 2) or 950°C (alloy 3). The temperature for the start of α-solid solution decomposition for the alloys is 935-640°C.

  16. Antibacterial effect of copper-bearing titanium alloy (Ti-Cu) against Streptococcus mutans and Porphyromonas gingivalis

    NASA Astrophysics Data System (ADS)

    Liu, Rui; Memarzadeh, Kaveh; Chang, Bei; Zhang, Yumei; Ma, Zheng; Allaker, Robert P.; Ren, Ling; Yang, Ke

    2016-07-01

    Formation of bacterial biofilms on dental implant material surfaces (titanium) may lead to the development of peri-implant diseases influencing the long term success of dental implants. In this study, a novel Cu-bearing titanium alloy (Ti-Cu) was designed and fabricated in order to efficiently kill bacteria and discourage formation of biofilms, and then inhibit bacterial infection and prevent implant failure, in comparison with pure Ti. Results from biofilm based gene expression studies, biofilm growth observation, bacterial viability measurements and morphological examination of bacteria, revealed antimicrobial/antibiofilm activities of Ti-Cu alloy against the oral specific bacterial species, Streptococcus mutans and Porphyromonas gingivalis. Proliferation and adhesion assays with mesenchymal stem cells, and measurement of the mean daily amount of Cu ion release demonstrated Ti-Cu alloy to be biocompatible. In conclusion, Ti-Cu alloy is a promising dental implant material with antimicrobial/antibiofilm activities and acceptable biocompatibility.

  17. Nucleation and growth of oxide islands during the initial-stage oxidation of (100)Cu-Pt alloys

    SciTech Connect

    Luo, Langli; Zhou, Guangwen; Kang, Yihong; Yang, Judith C.

    2015-02-14

    The initial-stage oxidation of (100) Cu-Pt alloys has been examined by in situ environmental transmission electron microscopy and ex situ atomic force microscopy (AFM). It is shown that the oxidation proceeds via the nucleation and growth of Cu{sub 2}O islands that show dependence on the alloy composition and oxidation temperature. The kinetic measurements on the oxide nucleation reveal that both the nucleation density and surface coverage of Cu{sub 2}O islands can be promoted by alloying more Pt in the Cu-Pt alloys. Increasing the oxidation temperature above 700 °C results in the growth of large Cu{sub 2}O islands that transits to a dendritic growth morphology. The ex situ AFM studies reveal that the nucleation of oxide islands can occur on surface terraces and the subsequent oxide growth depletes local terrace Cu atoms that results in the formation of surface pits.

  18. Antibacterial effect of copper-bearing titanium alloy (Ti-Cu) against Streptococcus mutans and Porphyromonas gingivalis

    PubMed Central

    Liu, Rui; Memarzadeh, Kaveh; Chang, Bei; Zhang, Yumei; Ma, Zheng; Allaker, Robert P.; Ren, Ling; Yang, Ke

    2016-01-01

    Formation of bacterial biofilms on dental implant material surfaces (titanium) may lead to the development of peri-implant diseases influencing the long term success of dental implants. In this study, a novel Cu-bearing titanium alloy (Ti-Cu) was designed and fabricated in order to efficiently kill bacteria and discourage formation of biofilms, and then inhibit bacterial infection and prevent implant failure, in comparison with pure Ti. Results from biofilm based gene expression studies, biofilm growth observation, bacterial viability measurements and morphological examination of bacteria, revealed antimicrobial/antibiofilm activities of Ti-Cu alloy against the oral specific bacterial species, Streptococcus mutans and Porphyromonas gingivalis. Proliferation and adhesion assays with mesenchymal stem cells, and measurement of the mean daily amount of Cu ion release demonstrated Ti-Cu alloy to be biocompatible. In conclusion, Ti-Cu alloy is a promising dental implant material with antimicrobial/antibiofilm activities and acceptable biocompatibility. PMID:27457788

  19. A surface analytical examination of Stringer particles in Al-Li-Cu alloys

    NASA Technical Reports Server (NTRS)

    Larson, L. A.; Avalos-Borja, M.; Pizzo, P. P.

    1983-01-01

    A surface analytical examination of powder metallurgy processed Al-Li-Cu alloys was conducted. The oxide stringer particles often found in these alloys was characterized. Particle characterization is important to more fully understand their impact on the stress corrosion and fracture properties of the alloy. The techniques used were SIMS (Secondary Ion Mass Spectroscopy) and SAM (Scanning Auger Microscopy). The results indicate that the oxide stringer particles contain both Al and Li with relatively high Li content and the Li compounds may be associated with the stringer particles, thereby locally depleting the adjacent matrix of Li solute.

  20. Cu(2+)-assisted synthesis of hexoctahedral Au-Pd alloy nanocrystals with high-index facets.

    PubMed

    Zhang, Lei; Zhang, Jiawei; Kuang, Qin; Xie, Shuifen; Jiang, Zhiyuan; Xie, Zhaoxiong; Zheng, Lansun

    2011-11-02

    Controlled syntheses of multicomponent metal nanocrystals (NCs) and high-index surfaces have attracted increasing attention due to the specific physical and chemical properties of such NCs. Taking advantage of copper underpotential deposition as a bridge, hexoctahedral Au-Pd alloy NCs with {hkl} facets exposed were successfully synthesized, while phase separation occurred in the absence of Cu(2+) ions. The as-prepared hexoctahedral Au-Pd alloy NCs exhibited very excellent performance in terms of both formic acid electro-oxidation and methanol tolerance due to synergism between the high-index facets and the alloy.

  1. Transmission electron microscopy characterization of microstructural features of Al-Li-Cu alloys

    NASA Technical Reports Server (NTRS)

    Avalos-Borja, M.; Pizzo, P. P.; Larson, L. A.

    1983-01-01

    A transmission electron microscopy (TEM) examination of aluminum-lithium-copper alloys was conducted. The principal purpose is to characterize the nature, size, and distribution of stringer particles which result from the powder metallurgy (P/M) processing of these alloys. Microstructural features associated with the stringer particles are reported that help explain the stress corrosion susceptibility of the powder metallurgy-processed Al-Li-Cu alloys. In addition, matrix precipitation events are documented for a variety of heat treatments and process variations. Hot rolling is observed to significant alter the nature of matrix precipitation, and the observations are correlated with concomitant mechanical property variations.

  2. Fabrication of thin film TiO2 nanotube arrays on Co-28Cr-6Mo alloy by anodization.

    PubMed

    Ni, Jiahua; Frandsen, Christine J; Noh, Kunbae; Johnston, Gary W; He, Guo; Tang, Tingting; Jin, Sungho

    2013-04-01

    Titanium oxide (TiO2) nanotube arrays were prepared by anodization of Ti/Au/Ti trilayer thin film DC sputtered onto forged and cast Co-28Cr-6Mo alloy substrate at 400 °C. Two different types of deposited film structures (Ti/Au/Ti trilayer and Ti monolayer), and two deposition temperatures (room temperature and 400 °C) were compared in this work. The concentrations of ammonium fluoride (NH4F) and H2O in glycerol electrolyte were varied to study their effect on the formation of TiO2 nanotube arrays on a forged and cast Co-28Cr-6Mo alloy. The results show that Ti/Au/Ti trilayer thin film and elevated temperature sputtered films are favorable for the formation of well-ordered nanotube arrays. The optimized electrolyte concentration for the growth of TiO2 nanotube arrays on forged and cast Co-28Cr-6Mo alloy was obtained. This work contains meaningful results for the application of a TiO2 nanotube coating to a CoCr alloy implant for potential next-generation orthopedic implant surface coatings with improved osseointegrative capabilities.

  3. Fabrication of thin film TiO2 nanotube arrays on Co-28Cr-6Mo alloy by anodization

    PubMed Central

    Ni, Jiahua; Frandsen, Christine J.; Noh, Kunbae; Johnston, Gary W.; He, Guo; Tang, Tingting; Jin, Sungho

    2014-01-01

    Titanium oxide (TiO2) nanotube arrays were prepared by anodization of Ti/Au/Ti trilayer thin film DC sputtered onto forged and cast Co-28Cr-6Mo alloy substrate at 400 °C. Two different types of deposited film structures (Ti/Au/Ti trilayer and Ti monolayer), and two deposition temperatures (room temperature and 400 °C) were compared in this work. The concentrations of ammonium fluoride (NH4F) and H2O in glycerol electrolyte were varied to study their effect on the formation of TiO2 nanotube arrays on a forged and cast Co-28Cr-6Mo alloy. The results show that Ti/Au/Ti trilayer thin film and elevated temperature sputtered films are favorable for the formation of well-ordered nanotube arrays. The optimized electrolyte concentration for the growth of TiO2 nanotube arrays on forged and cast Co-28Cr-6Mo alloy was obtained. This work contains meaningful results for the application of a TiO2 nanotube coating to a CoCr alloy implant for potential next-generation orthopedic implant surface coatings with improved osseointegrative capabilities. PMID:23827596

  4. Observation of the segregation and the dissolution of the Co and the Cu in CoCu metastable alloys.

    PubMed

    Fdez-Gubieda, M L; García Prieto, A; García Arribas, A; Meneghini, C; Mobilio, S

    2001-03-01

    Metastable Co(x)Cu100-x(x=5, 10, 15, 20) alloys have been annealed at increasing temperatures in order to study the evolution of the Co cluster and its relation with the magnetotransport properties. The structure was investigated by X-ray Absorption Spectroscopy on the Co K-edge as a function of composition and annealing temperature. An anomalous trend in the structural evolution has been evidenced and related to the preculiar features observed in the magnetotransport properties.

  5. Characterization of Al-Cu-Mg-Ag Alloy RX226-T8 Plate

    NASA Technical Reports Server (NTRS)

    Lach, Cynthia L.; Domack, Marcia S.

    2003-01-01

    Aluminum-copper-magnesium-silver (Al-Cu-Mg-Ag) alloys that were developed for thermal stability also offer attractive ambient temperature strength-toughness combinations, and therefore, can be considered for a broad range of airframe structural applications. The current study evaluated Al-Cu-Mg-Ag alloy RX226-T8 in plate gages and compared performance with sheet gage alloys of similar composition. Uniaxial tensile properties, plane strain initiation fracture toughness, and plane stress tearing resistance of RX226-T8 were examined at ambient temperature as a function of orientation and thickness location in the plate. Properties were measured near the surface and at the mid-plane of the plate. Tensile strengths were essentially isotropic, with variations in yield and ultimate tensile strengths of less than 2% as a function of orientation and through-thickness location. However, ductility varied by more than 15% with orientation. Fracture toughness was generally higher at the mid-plane and greater for the L-T orientation, although the differences were small near the surface of the plate. Metallurgical analysis indicated that the microstructure was primarily recrystallized with weak texture and was uniform through the plate with the exception of a fine-grained layer near the surface of the plate. Scanning electron microscope analysis revealed Al-Cu-Mg second phase particles which varied in composition and were primarily located on grain boundaries parallel to the rolling direction. Fractography of toughness specimens for both plate locations and orientations revealed that fracture occurred predominantly by transgranular microvoid coalescence. Introduction High-strength, low-density Al-Cu-Mg-Ag alloys were initially developed to replace conventional 2000 (Al-Cu-Mg) and 7000 (Al-Zn-Cu-Mg) series aluminum alloys for aircraft structural applications [1]. During the High Speed Civil Transport (HSCT) program, improvements in thermal stability were demonstrated for candidate

  6. Large extrinsic spin Hall effect in Au-Cu alloys by extensive atomic disorder scattering

    NASA Astrophysics Data System (ADS)

    Zou, L. K.; Wang, S. H.; Zhang, Y.; Sun, J. R.; Cai, J. W.; Kang, S. S.

    2016-01-01

    Spin Hall angle, which denotes the conversion efficiency between spin and charge current, is a key parameter in the pure spin current phenomenon. The search for materials with large spin Hall angle is indeed important for scientific interest and potential application in spintronics. Here the large enhanced spin Hall effect (SHE) of Au-Cu alloy is reported by investigating the spin Seebeck effect, spin Hall anomalous Hall effect, and spin Hall magnetoresistance of the Y3F e5O12 (YIG)/A uxC u1 -x hybrid structure over the full composition. At the near equiatomic Au-Cu composition with maximum atomic disorder scattering, the spin Hall angle of the Au-Cu alloy increases by two to three times together with a moderate spin diffusion length in comparison with Au. The longitudinal spin Seebeck voltage and the spin Hall magnetoresistance ratio also increase by two to three times. More importantly, no evidence of anomalous Hall effect is observed in all YIG/Au-Cu samples, in contrast to the cases of other giant SHE materials Pt(Pd), Ta, and W. This behavior makes Au-Cu free from any suspicion of the magnetic proximity effect involved in the hybrid structure, and thus the Au-Cu alloy can be an ideal material for pure spin current study.

  7. Interfacial Free Energy Controlling Glass-Forming Ability of Cu-Zr Alloys

    PubMed Central

    Kang, Dong-Hee; Zhang, Hao; Yoo, Hanbyeol; Lee, Hyun Hwi; Lee, Sooheyong; Lee, Geun Woo; Lou, Hongbo; Wang, Xiaodong; Cao, Qingping; Zhang, Dongxian; Jiang, Jianzhong

    2014-01-01

    Glass is a freezing phase of a deeply supercooled liquid. Despite its simple definition, the origin of glass forming ability (GFA) is still ambiguous, even for binary Cu-Zr alloys. Here, we directly study the stability of the supercooled Cu-Zr liquids where we find that Cu64Zr36 at a supercooled temperature shows deeper undercoolability and longer persistence than other neighbouring compositions with an equivalent driving Gibbs free energy. This observation implies that the GFA of the Cu-Zr alloys is significantly affected by crystal-liquid interfacial free energy. In particular, the crystal-liquid interfacial free energy of Cu64Zr36 in our measurement was higher than that of other neighbouring liquids and, coincidently a molecular dynamics simulation reveals a larger glass-glass interfacial energy value at this composition, which reflects more distinct configuration difference between liquid and crystal phase. The present results demonstrate that the higher crystal-liquid interfacial free energy is a prerequisite of good GFA of the Cu-Zr alloys. PMID:24893772

  8. Interfacial free energy controlling glass-forming ability of Cu-Zr alloys.

    PubMed

    Kang, Dong-Hee; Zhang, Hao; Yoo, Hanbyeol; Lee, Hyun Hwi; Lee, Sooheyong; Lee, Geun Woo; Lou, Hongbo; Wang, Xiaodong; Cao, Qingping; Zhang, Dongxian; Jiang, Jianzhong

    2014-06-04

    Glass is a freezing phase of a deeply supercooled liquid. Despite its simple definition, the origin of glass forming ability (GFA) is still ambiguous, even for binary Cu-Zr alloys. Here, we directly study the stability of the supercooled Cu-Zr liquids where we find that Cu64Zr36 at a supercooled temperature shows deeper undercoolability and longer persistence than other neighbouring compositions with an equivalent driving Gibbs free energy. This observation implies that the GFA of the Cu-Zr alloys is significantly affected by crystal-liquid interfacial free energy. In particular, the crystal-liquid interfacial free energy of Cu64Zr36 in our measurement was higher than that of other neighbouring liquids and, coincidently a molecular dynamics simulation reveals a larger glass-glass interfacial energy value at this composition, which reflects more distinct configuration difference between liquid and crystal phase. The present results demonstrate that the higher crystal-liquid interfacial free energy is a prerequisite of good GFA of the Cu-Zr alloys.

  9. The Maximum Fluidity Length of Solidifying Sn-Cu-Ag-Ni Solder Alloys

    NASA Astrophysics Data System (ADS)

    Gourlay, C. M.; Read, J.; Nogita, K.; Dahle, A. K.

    2008-01-01

    During wave soldering, it is important that a solder is able to flow easily to fill joints and to drain away to leave tidy fillets. The maximum fluidity length ( L f) is a simple measure of the flow behavior of solidifying alloys, defined as the distance a cooling and solidifying alloy can flow in a constant cross-section before the developing microstructure arrests flow. This paper explores the influence of alloy composition on L f in Sn-rich Sn-Cu-Ag-Ni alloys with compositions relevant to wave soldering. Significant differences in L f are measured among candidate lead-free solder alloys, which are discussed with respect to the phase diagrams and the mode of solidification.

  10. Composition and anisotropy in Al-Cu-Li-Ag-Mg-Zr alloys

    SciTech Connect

    Gayle, F.W. . Metallurgy Div.); Tack, W.T.; Swanson, G. ); Heubaum, F.H.; Pickens, J.R. )

    1994-03-15

    Aluminum-lithium alloys that have been hot worked generally suffer from an anisotropy of mechanical properties, both through thickness (surface to centerline) and in plane (from longitudinal to 45[degree] to transverse). Although such anisotropy is present in all tempers, it is more pronounced in the commercially-important, high strength, artificially aged conditions. Yield strength differences between the longitudinal and long transverse orientations ([Delta]YS) of up to 240 MPa for Al-Cu-Li alloy 2090 have been reported. Since minimum properties in all orientations must be considered in applications design, mechanical property anisotropy can limit the use of an alloy. To investigate the role composition plays in the development of mechanical property anisotropy, the authors have examined a range of compositions in the Weldalite[reg sign] 049 alloy family as well as certain model alloys. This novel approach is in contrast to most attempts to reduce anisotropy which have been based on established alloys of relatively narrow composition ranges. In the present study, a baseline aluminum alloy 2195 (4.0 Cu-0.95 Li-0.4 Ag-0.4 Mg-0.14 Zr, in wt.%) with accompanying experimental variants containing 0 to 1.4% Li and 0.4 and 1.2% Mg, were evaluated for tensile property anisotropy, fracture toughness, and microstructure.

  11. Tensile Properties of Al-Cu 206 Cast Alloys with Various Iron Contents

    NASA Astrophysics Data System (ADS)

    Liu, K.; Cao, X.; Chen, X.-G.

    2014-05-01

    The Al-Cu 206 cast alloys with varying alloy compositions ( i.e., different levels of Fe, Mn, and Si) were investigated to evaluate the effect of the iron-rich intermetallics on the tensile properties. It is found that the tensile strength decreases with increasing iron content, but its overall loss is less than 10 pct over the range of 0.15 to 0.5 pct Fe at 0.3 pct Mn and 0.3 pct Si. At similar iron contents, the tensile properties of the alloys with dominant Chinese script iron-rich intermetallics are generally higher than those with the dominant platelet phase. In the solution and artificial overaging condition (T7), the tensile strength of the 206 cast alloys with more than 0.15 pct Fe is satisfactory, but the elongation does not sufficiently meet the minimum requirement of ductility (>7 pct) for critical automotive applications. However, it was found that both the required ductility and tensile strength can be reached at high Fe levels of 0.3 to 0.5 pct for the alloys with well-controlled alloy chemistry and microstructure in the solution and natural aging condition (T4), reinforcing the motivation for developing recyclable high-iron Al-Cu 206 cast alloys.

  12. Atmospheric corrosion of Cu, Zn, and Cu-Zn alloys protected by self-assembled monolayers of alkanethiols

    NASA Astrophysics Data System (ADS)

    Hosseinpour, Saman; Forslund, Mattias; Johnson, C. Magnus; Pan, Jinshan; Leygraf, Christofer

    2016-06-01

    In this article results from earlier studies have been compiled in order to compare the protection efficiency of self-assembled monolayers (SAM) of alkanethiols for copper, zinc, and copper-zinc alloys exposed to accelerated indoor atmospheric corrosion conditions. The results are based on a combination of surface spectroscopy and microscopy techniques. The protection efficiency of investigated SAMs increases with chain length which is attributed to transport hindrance of the corrosion stimulators in the atmospheric environment, water, oxygen and formic acid, towards the copper surface. The transport hindrance is selective and results in different corrosion products on bare and on protected copper. Initially the molecular structure of SAMs on copper is well ordered, but the ordering is reduced with exposure time. Octadecanethiol (ODT), the longest alkanethiol investigated, protects copper significantly better than zinc, which may be attributed to the higher bond strength of Cu-S than of Zn-S. Despite these differences, the corrosion protection efficiency of ODT for the single phase Cu20Zn brass alloy is equally efficient as for copper, but significantly less for the heterogeneous double phase Cu40Zn brass alloy.

  13. A novel coping metal material CoCrCu alloy fabricated by selective laser melting with antimicrobial and antibiofilm properties.

    PubMed

    Ren, Ling; Memarzadeh, Kaveh; Zhang, Shuyuan; Sun, Ziqing; Yang, Chunguang; Ren, Guogang; Allaker, Robert P; Yang, Ke

    2016-10-01

    The aim of this study was to fabricate a novel coping metal CoCrCu alloy using a selective laser melting (SLM) technique with antimicrobial and antibiofilm activities and to investigate its microstructure, mechanical properties, corrosion resistance and biocompatibility. Novel CoCrCu alloy was fabricated using SLM from a mixture of commercial CoCr based alloy and elemental Cu powders. SLM CoCr without Cu served as control. Antibacterial activity was analyzed using standard antimicrobial tests, and antibiofilm properties were investigated using confocal laser scanning microscope. Cu distribution and microstructure were determined using scanning electron microscope, optical microscopy and X-ray diffraction. Corrosion resistance was evaluated by potential dynamic polarization and biocompatibility measured using an MTT assay. SLM CoCrCu alloys were found to be bactericidal and able to inhibit biofilm formation. Other factors such as microstructure, mechanical properties, corrosion resistance and biocompatibility were similar to those of SLM CoCr alloys. The addition of appropriate amounts of Cu not only maintains normal beneficial properties of CoCr based alloys, but also provides SLM CoCrCu alloys with excellent antibacterial and antibiofilm capabilities. This material has the potential to be used as a coping metal for dental applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Analysis of the Influence of Starting Materials and Processing Conditions on the Properties of W/Cu Alloys

    PubMed Central

    Montealegre-Meléndez, Isabel; Arévalo, Cristina; Perez-Soriano, Eva M.; Neubauer, Erich; Rubio-Escudero, Cristina; Kitzmantel, Michael

    2017-01-01

    In this work, a study of the influence of the starting materials and the processing time used to develop W/Cu alloys is carried out. Regarding powder metallurgy as a promising fabrication route, the difficulties in producing W/Cu alloys motivated us to investigate the influential factors on the final properties of the most industrially demanding alloys: 85-W/15-Cu, 80-W/20-Cu, and 75-W/25-Cu alloys. Two different tungsten powders with large variation among their particle size—fine (Wf) and coarse (Wc) powders—were used for the preparation of W/Cu alloys. Three weight ratios of fine and coarse (Wf:Wc) tungsten particles were analyzed. These powders were labelled as “tungsten bimodal powders”. The powder blends were consolidated by rapid sinter pressing (RSP) at 900 °C and 150 MPa, and were thus sintered and compacted simultaneously. The elemental powders and W/Cu alloys were studied by optical microscopy (OM) and scanning electron microscopy (SEM). Thermal conductivity, hardness, and densification were measured. Results showed that the synthesis of W/Cu using bimodal tungsten powders significantly affects the final alloy properties. The higher the tungsten content, the more noticeable the effect of the bimodal powder. The best bimodal W powder was the blend with 10 wt % of fine tungsten particles (10-Wf:90-Wc). These specimens present good values of densification and hardness, and higher values of thermal conductivity than other bimodal mixtures. PMID:28772502

  15. A novel Nickel-Aluminum alloy with Titanium for improved anode performance and properties in Molten Carbonate Fuel Cells

    NASA Astrophysics Data System (ADS)

    Frattini, Domenico; Accardo, Grazia; Moreno, Angelo; Yoon, Sung Pil; Han, Jong Hee; Nam, Suk Woo

    2017-06-01

    The anode materials of MCFC require more investigations in order to boost performances at long term. In literature, many NiAl modified alloys have been proposed but not always enhanced cell performance and improved mechanical properties are achieved together. In this work, differently from previous literature, the use of Ti in a NiAl/Ti system is proposed as an effective strategy to enhance both mechanical and electrochemical properties. Results show that bending strength and stiffness increase whereas creep deformation under high pressure-temperature is lower, i.e. around 5-6%, compared to 7.5% of the standard benchmark. The preliminary cell tests carried out show also how the performance, in terms of current and voltage output, is better for anodes with Ti addition with a maximum power density of 165 mW cm-2 at 300 mA cm-2 for Ti 5% compared to 149 mW cm-2 of Ni5Al at the same current density. Finally, the best electrochemical behavior is found for the Ti 5% sample as it achieved the lowest internal and charge transfer resistance at the end of tests. These results suggest that NiAl/Ti systems can be eligible anode materials and are worthy to be investigated more in order to attract a renewed interest for development of MCFCs.

  16. Thin Anodic Oxide Films on Aluminum Alloys and Their Role in the Durability of Adhesive Bonds.

    DTIC Science & Technology

    1980-02-01

    REFERENCES 20 Si ! V K.. LIST OF ILLUSTRATIONS FIGURE PG 1 Thermogram of Boehmite, Bayerite , and Anodic IOxide on Aluminum. 7 2 Porous Oxide and Barrier Layer...and bayerite . The data shown in the thermogram in Figure 1 does not show any direct relationship of anodic aluminum oxide to either compound. Since...y boehmite |0 S anodic film (I). C3 DC Foo.0 200.0 300.0 400.0 500.0 600.0 706.0 TEMPERATURE DEGREE CELCIUS Figure 1. Thermogram of Boehmite, Bayerite

  17. Effect of Surplus Phase on the Microstructure and Mechanical Properties in Al-Cu-Mg-Ag Alloys with High Cu/Mg Ratio

    NASA Astrophysics Data System (ADS)

    Xu, Xiaofeng; Zhao, Yuguang; Wang, Xudong; Zhang, Ming; Ning, Yuheng

    2015-11-01

    In order to examine the effect of surplus phase on the microstructure and mechanical properties, different compositions with high Cu/Mg ratio of the T6-temper extruded Al-Cu-Mg-Ag alloys were studied in this investigation. The results show that the Al-5.6Cu-0.56Mg-0.4Ag alloy obtains superior mechanical properties at room temperature, while the yield strength of Al-6.3Cu-0.48Mg-0.4Ag alloy is 378 MPa at 200 °C, which is 200 MPa higher than that of Al-5.6Cu-0.56Mg-0.4Ag alloy. Although the excessive Cu content causes the slight strength loss and elongation decrease in the Al-6.3Cu-0.48Mg-0.4Ag alloy at room temperature, the surplus phases and recrystallized microstructure will play an effective role in strengthening the alloy at elevated temperature.

  18. High conductivity Be-Cu alloys for fusion reactors

    SciTech Connect

    Lilley, E.A.; Adachi, Takao; Ishibashi, Yoshiki

    1995-09-01

    The optimum material has not yet been identified. This will result in heat from plasma to the first wall and divertor. That is, because of cracks and melting by thermal power and shock. Today, it is considered to be some kinds of copper, alloys, however, for using, it must have high conductivity. And it is also needed another property, for example, high strength and so on. We have developed some new beryllium copper alloys with high conductivity, high strength, and high endurance. Therefore, we are introducing these new alloys as suitable materials for the heat sink in fusion reactors.

  19. Dissolution of Cu/Mg Bearing Intermetallics in Al-Si Foundry Alloys

    NASA Astrophysics Data System (ADS)

    Javidani, Mousa; Larouche, Daniel; Grant Chen, X.

    2016-10-01

    Evolutions of the Cu/Mg bearing intermetallics were thoroughly investigated in four Al-Si hypoeutectic alloys containing various Cu (1 and 1.6 wt pct) and Mg (0.4 and 0.8 wt pct) contents. The area fractions of Cu/Mg bearing phases before and after solution heat treatment (SHT) were quantified to evaluate the solubility/stability of the phases. Two Mg-bearing intermetallics (Q-Al5Cu2Mg8Si6, π-Al8FeMg3Si6) which appear as gray color under optical microscope were discriminated by the developed etchant. Moreover, the concentrations of the elements (Cu, Mg, and Si) in α-Al were analyzed. The results illustrated that in the alloys containing ~0.4 pct Mg, Q-Al5Cu2Mg8Si6 phase was dissolved after 6 hours of SHT at 778 K (505 °C); but containing in the alloys ~0.8 pct Mg, it was insoluble/ partially soluble. Furthermore, after SHT at 778 K (505 °C), Mg2Si was partially substituted by Q-phase. Applying a two-step SHT [6 hours@778 K (505 °C) + 8 hours@798 K (525 °C)] in the alloys containing ~0.4 pct Mg helped to further dissolve the remaining Mg bearing intermetallics and further modified the microstructure, but in the alloys containing ~0.8 pct Mg, it caused partial melting of Q-phase. Thermodynamic calculations were carried out to assess the phase formation in equilibrium and in non-equilibrium conditions. There was an excellent agreement between the experimental results and the predicted results.

  20. Cu3Si@Si core-shell nanoparticles synthesized using a solid-state reaction and their performance as anode materials for lithium ion batteries.

    PubMed

    Zhou, Jianbin; Lin, Ning; Han, Ying; Zhou, Jie; Zhu, Yongchun; Du, Jin; Qian, Yitai

    2015-10-07

    Cu3Si@Si core-shell nanoparticles with a Si shell coated over the Cu3Si core are synthesized by a solid-state reaction between CuCl and Si. The evaluation process of the core-shell structure shows a mechanism analogous to the Kirkendall effect. As anode materials for lithium ion batteries, Cu3Si@Si core-shell nanoparticles retained a capacity of 903.6 mA h g(-1) at the current density of 2 A g(-1) over 400 cycles.

  1. Comparison of GRCop-84 to Other High Thermal Conductive Cu Alloys

    NASA Technical Reports Server (NTRS)

    deGroh, Henry C., III; Ellis, David L.; Loewenthal, William S.

    2007-01-01

    The mechanical properties of five copper alloys (GRCop-84, AMZIRC, GlidCop Al-15, Cu-1Cr-0.1Zr, Cu-0.9Cr) competing in high temperature, high heat flux applications such as rocket nozzles, were compared. Tensile, creep, thermal expansion, and compression tests are presented. Tests were done on as-received material, and on material which received a simulated brazing heat treatment at 935 C. The 935 C heat treatment weakened AMZIRC, Cu-1Cr-0.1Zr, and Cu-0.9Cr, and the strength of as-received AMZIRC dropped precipitously as test temperatures exceeded 500 C. The properties of GlidCop Al-15 and GRCop-84 were not significantly affected by the 935 C heat treatment. Thus GRCop-84 is better than AMZIRC, Cu-1Cr-0.1Zr, and Cu-0.9Cr at temperatures greater than 500 C. Ductility was lowest in GlidCop Al-15 and Cu-0.9Cr. The creep properties of GRCop-84 were superior to those of brazed AMZIRC, Cu-1Cr-0.1Zr, and Cu-0.9Cr. At equivalent rupture life and stress, GRCop-84 had a 150 C temperature advantage over brazed AMZIRC; for equivalent rupture life and temperature GRCop-84 was two times stronger. The advantages of GRCop-84 over GlidCop Al-15 associated with ease of processing were confirmed by GlidCop s marginal ductility. In the post brazed condition, GRCop-84 was found to be superior to the other alloys due to its greater strength and creep resistance (compared to AMZIRC, Cu-1Cr-0.1Zr, and Cu-0.9Cr) and ductility (compared to GlidCop Al-15)

  2. Tailoring the Electronic Structure by Alloying: AgnCu34-n Nanoparticle Family

    NASA Astrophysics Data System (ADS)

    Yildirim, Handan; Kara, Abdelkader; Rahman, Talat S.

    2010-03-01

    We report results of first principles calculations of the electronic structure of the AgnCu34-n bi-metallic nanoparticle family where n=0, 1, , 34. We find that alloying of the pure Ag cluster with a few Cu atoms displays substantial changes in the electronic structure but the reverse is not the case when few Ag atoms are substituted in pure Cu clusters. We find that local environment control the length and the strength of the Cu-Ag bonds. The Cu atoms, which form the core display shortened bond length and present above 1 eV shift in their d-band center. The HOMO-LUMO gap for the set of nanoalloys falls in three regions: 0.19 eV to 0.31 eV, 0.40 eV to 0.57 eV, and 0.73 eV to 0.88 eV. For several nanoparticles slight change in composition may thus lead to a change of about 600 meV in the gap. The highest gap is found for the most symmetric nanoparticle (Ag17Cu17), while the lowest is for Ag29Cu5. We present a systematic analysis of the changes in Cu-Ag, Ag-Ag and Cu-Cu bond lengths and hybridization with composition to understand their effect on the HOMO-LUMO gap and other characteristics of the nanoparticles.

  3. Understanding the Cu-Zn brass alloys using a short-range-order cluster model: significance of specific compositions of industrial alloys

    PubMed Central

    Hong, H. L.; Wang, Q.; Dong, C.; Liaw, Peter K.

    2014-01-01

    Metallic alloys show complex chemistries that are not yet understood so far. It has been widely accepted that behind the composition selection lies a short-range-order mechanism for solid solutions. The present paper addresses this fundamental question by examining the face-centered-cubic Cu-Zn α-brasses. A new structural approach, the cluster-plus-glue-atom model, is introduced, which suits specifically for the description of short-range-order structures in disordered systems. Two types of formulas are pointed out, [Zn-Cu12]Zn1~6 and [Zn-Cu12](Zn,Cu)6, which explain the α-brasses listed in the American Society for Testing and Materials (ASTM) specifications. In these formulas, the bracketed parts represent the 1st-neighbor cluster, and each cluster is matched with one to six 2nd-neighbor Zn atoms or with six mixed (Zn,Cu) atoms. Such a cluster-based formulism describes the 1st- and 2nd-neighbor local atomic units where the solute and solvent interactions are ideally satisfied. The Cu-Ni industrial alloys are also explained, thus proving the universality of the cluster-formula approach in understanding the alloy selections. The revelation of the composition formulas for the Cu-(Zn,Ni) industrial alloys points to the common existence of simple composition rules behind seemingly complex chemistries of industrial alloys, thus offering a fundamental and practical method towards composition interpretations of all kinds of alloys. PMID:25399835

  4. Understanding the Cu-Zn brass alloys using a short-range-order cluster model: significance of specific compositions of industrial alloys

    NASA Astrophysics Data System (ADS)

    Hong, H. L.; Wang, Q.; Dong, C.; Liaw, Peter K.

    2014-11-01

    Metallic alloys show complex chemistries that are not yet understood so far. It has been widely accepted that behind the composition selection lies a short-range-order mechanism for solid solutions. The present paper addresses this fundamental question by examining the face-centered-cubic Cu-Zn α-brasses. A new structural approach, the cluster-plus-glue-atom model, is introduced, which suits specifically for the description of short-range-order structures in disordered systems. Two types of formulas are pointed out, [Zn-Cu12]Zn1~6 and [Zn-Cu12](Zn,Cu)6, which explain the α-brasses listed in the American Society for Testing and Materials (ASTM) specifications. In these formulas, the bracketed parts represent the 1st-neighbor cluster, and each cluster is matched with one to six 2nd-neighbor Zn atoms or with six mixed (Zn,Cu) atoms. Such a cluster-based formulism describes the 1st- and 2nd-neighbor local atomic units where the solute and solvent interactions are ideally satisfied. The Cu-Ni industrial alloys are also explained, thus proving the universality of the cluster-formula approach in understanding the alloy selections. The revelation of the composition formulas for the Cu-(Zn,Ni) industrial alloys points to the common existence of simple composition rules behind seemingly complex chemistries of industrial alloys, thus offering a fundamental and practical method towards composition interpretations of all kinds of alloys.

  5. Effects of Cu content and preaging on precipitation characteristics in aluminum alloy 6022

    SciTech Connect

    Miao, W.F.; Laughlin, D.E.

    2000-02-01

    Effects of Cu content and preaging treatments on precipitation sequence and artificial aging response in aluminum alloy 6022 were investigated using transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and hardness tests. It was found that Cu induces the formation of Q and its precursor metastable phases and has a beneficial effect on the kinetics of artificial aging. For the alloy with 0.07 wt pct Cu, the precipitation sequence is GP zones {r{underscore}arrow} needlelike {beta}{double{underscore}prime} {r{underscore}arrow} rodlike {beta}{prime} + lathlike Q{prime} {yields} (beta) + Si. On the other hand, the precipitation sequence in the alloy with 0.91 wt pct lathlike Q{prime} {yields} {beta} + Si. On the other hand, the precipitation sequence in the alloy with 0.91 wt pct Cu is GP zones {r{underscore}arrow} needlelike {beta}{double{underscore}prime} {r{underscore}arrow} lathlike Q{prime} {yields} Q + Si. For the artificial aging condition of 20 minutes at 175 C, which is the typical automotive paint bake condition, suitable preaging treatments were found to significantly reduce the detrimental effect of the natural aging on artificial aging response.

  6. Physical simulation study of the dynamic recrystallization kinetics of an Ni-Cu-Al alloy

    NASA Astrophysics Data System (ADS)

    Rudskoi, A. I.; Kodzhaspirov, G. E.; Kamelin, E. I.

    2015-10-01

    The influence of temperature and deformation on the dynamic recrystallization kinetics of an Ni-30Cu-3Al heat-resistant alloy has been studied on the basis of experiments using a torsion plastometer. The process is simulated and mathematical model is proposed for estimating the dynamically recrystallized grain sizes. Good agreement between the calculated and experimental data is achieved.

  7. The response of macrophages to a Cu-Al-Ni shape memory alloy.

    PubMed

    Colić, Miodrag; Tomić, Sergej; Rudolf, Rebeka; Anzel, Ivan; Lojen, Gorazd

    2010-09-01

    Cu-Al-Ni shape memory alloys (SMAs) have been investigated as materials for medical devices, but little is known about their biocompatibility. The aim of this work was to study the response of rat peritoneal macrophages (PMØ) to a Cu-Al-Ni SMA in vitro, by measuring the functional activity of mitochondria, necrosis, apoptosis, and production of proinflammatory cytokines. Rapidly solidified (RS) thin ribbons were used for the tests. The control alloy was a permanent mold casting of the same composition, but without the shape memory effect. Our results showed that the control alloy was severely cytotoxic, whereas RS ribbons induced neither necrosis nor apoptosis of PMØ. These findings correlated with the data that RS ribbons are significantly more resistant to corrosion compared to the control alloy, as judged by the lesser release of Cu and Ni in the conditioning medium. However, the ribbons generated intracellular reactive oxygen species and upregulated the production of IL-6 by PMØ. These effects were almost completely abolished by conditioning the RS ribbons for 5 weeks. In conclusion, RS significantly improves the corrosion stability and biocompatibility of Cu-Al-Ni SMA. The biocompatibility of this functional material could be additionally enhanced by conditioning the ribbons in cell culture medium.

  8. New Cu(AuTiNx) copper alloy film and its features

    NASA Astrophysics Data System (ADS)

    Lin, Chon-Hsin

    2016-01-01

    In this study, a new copper alloy [Cu(AuTiNx)] film is developed for industrial applications, by cosputtering Cu and titanium gold (AuTi) targets on a barrierless Si substrate within a vacuum chamber sparsely filled with N2 gas. Through extensive tests conducted in this study, the new alloy film, after annealing at 720 °C for 1 h, shows good thermal stability and high adhesion strength to the substrate, without appreciable interactions between the film and the substrate. The new Cu(AuTiNx) alloy film also has adequate wetting for solder, shows good solderability, and has a dissolution rate lower than that of pure Cu by at least 1 order of magnitude, in addition to having a comparable consumption rate to that of Ni. The alloy film seems to be suitable for many industrial applications, e.g., barrierless Si metallization, interconnect manufacture, and as new wetting and diffusion layers for flip-chip solder joints in conventional metallurgy.

  9. Investigation of the ternary phase diagram of mechanically alloyed FeCuAg

    NASA Astrophysics Data System (ADS)

    Cohen, N. S.; Ahlswede, E.; Wicks, J. D.; Pankhurst, Q. A.

    1997-04-01

    The structural and magnetic properties of mechanically alloyed Fe - Cu - Ag at room temperature have been investigated using 0953-8984/9/15/016/img1 Mössbauer spectroscopy, x-ray diffraction and differential scanning calorimetry. The elements are naturally immiscible, but through prolonged and energetic ball milling (70 hours at 600 rpm) one can make metastable alloys, the structure of which depends on the elemental composition. In the binary Cu - Ag and Fe - Cu systems, crystalline single-phase solid solutions result, whereas in Fe - Ag the alloying is limited, with the product a mixture of elemental particles. In the ternary system it is possible to produce copper- and silver-rich single-phase fcc alloys, but not the equivalent bcc iron-based structure. As the proportions of the three elements become more equal, the resulting structure becomes highly disordered or amorphous. The composition range of this amorphous phase is different to that observed in sputtered Fe - Cu - Ag systems.

  10. Protection of Advanced Copper Alloys With Lean Cu-Cr Coatings

    NASA Technical Reports Server (NTRS)

    Greenbauer-Seng, L. (Technical Monitor); Thomas-Ogbuji, L.

    2003-01-01

    Advanced copper alloys are used as liners of rocket thrusters and nozzle ramps to ensure dissipation of the high thermal load generated during launch, and Cr-lean coatings are preferred for the protection of these liners from the aggressive ambient environment. It is shown that adequate protection can be achieved with thin Cu-Cr coatings containing as little as 17 percent Cr.

  11. Microstructural evolution during aging of an Al-Cu-Li-Ag-Mg-Zr alloy

    NASA Technical Reports Server (NTRS)

    Kumar, K. S.; Brown, S. A.; Pickens, Joseph R.

    1991-01-01

    Alloys in the Al-Cu-Li Ag-Mg subsystem were developed that exhibit desirable combinations of strength and ductility. These Weldalite (trademark) alloys, are unique for Al-Cu-Li alloys in that with or without a prior cold stretching operation, they obtain excellent strength-ductility combinations upon natural and artificial aging. This is significant because it enables complex, near-net shape products such as forgings and super plastically formed parts to be heat treated to ultra-high strengths. On the other hand, commercial extrusions, rolled plates and sheets of other Al-Cu-Li alloys are typically subjected to a cold stretching operation before artificial aging to the highest strength tempers to introduce dislocations that provide low-energy nucleation sites for strengthening precipitates such as the T(sub 1) phase. The variation in yield strength (YS) with Li content in the near-peak aged condition for these Weldalite (trademark) alloys and the associated microstructures were examined, and the results are discussed.

  12. Application of Al-Nb alloy film to metal capping layer on Cu

    NASA Astrophysics Data System (ADS)

    Takeyama, Mayumi B.; Noya, Atsushi

    2016-02-01

    An Al-Nb alloy film with the Al72Nb28 composition is applied as a candidate metal capping layer on Cu interconnects. In the Al72Nb28/Cu/SiO2/Si model system, the preferential oxidation of Al forming a thin surface Al2O3 layer occurs owing to oxidation in air for 1 h at temperatures up to ˜300 °C, resulting in the protection of the layers underneath from further oxidation, although a slight Cu intermixing into Al-Nb occurs. With increasing oxidation temperature up to 500 °C, the surface Al2O3 layer still grows by the preferential oxidation of Al and rejects Cu atoms from the surface oxidized layer. Although Nb atoms are left behind in the surface oxidized layer, they are in a metallic state owing to the high solubility of oxygen before forming an oxide. The extremely low solubility of Nb in Cu also protects Cu without excess intermixing. A good passivation characteristic of the Al72Nb28 alloy film on Cu is demonstrated.

  13. Precipitates in a quasicrystal-strengthened Al–Mn–Be–Cu alloy

    SciTech Connect

    Zupanič, Franc; Wang, Di; Gspan, Cristian; Bončina, Tonica

    2015-08-15

    In this work, an Al–Mn–Be–Cu alloy was studied containing a primary and eutectic icosahedral quasicrystalline phase in the as-cast microstructure. Special attention was given to a transmission electron microscopy investigation of precipitates formed within the aluminium solid solution (Al{sub ss}) at different temperatures. At 200 °C, only binary Al–Cu precipitates (θ′) were formed. At 300 °C, icosahedral quasicrystalline (IQC) precipitates prevailed with a crystallographic orientation relationship with the Al{sub ss.} The rods of the T-phase (Al{sub 20}Mn{sub 3}Cu{sub 2}) which were precipitated above 400 °C, also had a specific orientation relationship with the Al{sub ss}. The primary and eutectic IQC microstructural constituent started to transform rapidly to the T-phase and Be{sub 4}Al(Mn,Cu) at 500 °C. - Highlights: • In a quasicrystal-strengthened Al-alloy several types of precipitates can form. • At 200 °C, only binary Al–Cu precipitates formed (Al{sub 2}Cu-θ′). • The icosahedral quasicrystalline (IQC) precipitates prevailed at 300 °C. • T-phase (Al{sub 20}Mn{sub 3}Cu{sub 2}) precipitated at temperatures above 400 °C. • The precipitation of different phases did not have a strong effect on hardness.

  14. Machining characteristics and fracture morphologies in a copper-beryllium (Cu-2Be) alloy

    NASA Astrophysics Data System (ADS)

    Sudhakar, K. V.; Cisneros, J. C.; Cervantes, Hector; Pineda, Cosme Gomez

    2006-02-01

    The technology of materials removal is improved greatly by the introduction of advanced cutting tools like cubic boron nitride, ceramics, polycrystalline diamond and the more recent whisker-reinforced materials. In this paper, the influence of cutting temperature on machinability, mechanical properties, microstructure, and fracture morphology of Cu-2Be alloy using a polycrystalline diamond cutter is investigated. The information on machining, microstructure, and fracture morphology of Cu-2Be alloy are very useful to understand their fabrication characteristics and the basic mechanisms of its deformation and fracture. The machinability (in terms of surface finish) of Cu-2Be alloy is evaluated as a function of cutting temperature, resulting from wet and dry cutting. Machining is carried out on a Hardinge Cobra 42 CNC machine (Hardinge Inc., Elmira, NY), and the machining parameters used—cutting speed, depth of cut, and feed rate—are kept constant during both wet and dry cutting. The machined surface finish on Cu-2Be alloy is measured using a surface finish analyzer (Surftest 401, series 178) technique. The machined specimens are examined for their strength and hardness properties using a standard Universal Testing Machine and Rockwell hardness tester, respectively. Wet cutting (using coolants) produced a smooth surface finish when compared with dry cutting of the Cu-2Be alloy. The machined specimens are examined for their microstructural features using a Nikon optical microscope. The specimens are etched using a suitable etchant solution for revealing such microstructure constituents as grain size, phase proportions, and the possible overheated areas (especially in dry cutting). The fractured surfaces from the tensile and impact toughness tests are investigated for their fracture morphologies (dry and wet cutting) using a microprocessor-controlled scanning electron microscope (Jeol Model JSM 5910 LV). A detailed analysis is also made to understand and interpret

  15. Synthesis and anti-bacterial activity of Cu, Ag and Cu-Ag alloy nanoparticles: A green approach

    SciTech Connect

    Valodkar, Mayur; Modi, Shefaly; Pal, Angshuman; Thakore, Sonal

    2011-03-15

    Research highlights: {yields} Synthesis of novel nanosized copper-silver alloys of different compositions. {yields} Completely green approach for synthesis of water soluble bimetallic nanoparticle. {yields} Interesting anti-bacterial activity of as synthesized metal and alloy nanoparticle. -- Abstract: Metallic and bimetallic nanoparticles of copper and silver in various proportions were prepared by microwave assisted chemical reduction in aqueous medium using the biopolymer, starch as a stabilizing agent. Ascorbic acid was used as the reducing agent. The silver and copper nanoparticles exhibited surface plasmon absorption resonance maxima (SPR) at 416 and 584 nm, respectively; while SPR for the Cu-Ag alloys appeared in between depending on the alloy composition. The SPR maxima for bimetallic nanoparticles changes linearly with increasing copper content in the alloy. Transmission electron micrograph (TEM) showed monodispersed particles in the range of 20 {+-} 5 nm size. Both silver and copper nanoparticles exhibited emission band at 485 and 645 nm, respectively. The starch-stabilized nanoparticles exhibited interesting antibacterial activity with both gram positive and gram negative bacteria at micromolar concentrations.

  16. Crystallization and nanoindentation behavior of a bulk Zr-Al-Ti-Cu-Ni amorphous alloy

    SciTech Connect

    Wang, J. G.; Choi, B. W.; Nieh, T. G.; Liu, C. T.

    2000-03-01

    The crystallization and nanoindentation behavior of a Zr-10Al-5Ti-17.9Cu-14.6Ni (at.%) bulk amorphous alloy (BAA) were studied. Resulting from the kinetic nature of phase transformation in multicomponent alloys, the crystallization path is complex. Despite the complexity of different crystallization paths, the main final crystallized product in the Zr-based BAA is Zr{sub 2}Cu. Young's modulus and hardness of the BAA were found to increase with an increase in annealing temperature. The observed mechanical properties were correlated with the microstructure of the material. Also, in the present paper, both the observed crystallization and nanoindentation behavior are compared with existing data. Zr-based BAAs exhibit a ratio of hardness to Young's modulus (H/E ratio) of about 1/10, suggesting the interatomic bonding in the alloys is close to being covalent. (c) 2000 Materials Research Society.

  17. Size and alloying induced shift in core and valence bands of Pd-Ag and Pd-Cu nanoparticles

    SciTech Connect

    Sengar, Saurabh K.; Mehta, B. R.; Govind

    2014-03-28

    In this report, X-ray photoelectron spectroscopy studies have been carried out on Pd, Ag, Cu, Pd-Ag, and Pd-Cu nanoparticles having identical sizes corresponding to mobility equivalent diameters of 60, 40, and 20 nm. The nanoparticles were prepared by the gas phase synthesis method. The effect of size on valence and core levels in metal and alloy nanoparticles has been studied by comparing the values to those with the 60 nm nanoparticles. The effect of alloying has been investigated by comparing the valence and core level binding energies of Pd-Cu and Pd-Ag alloy nanoparticles with the corresponding values for Pd, Ag, and Cu nanoparticles of identical sizes. These effects have been explained in terms of size induced lattice contractions, alloying induced charge transfer, and hybridization effects. The observation of alloying and size induced binding energy shifts in bimetallic nanoparticles is important from the point of view of hydrogen reactivity.

  18. Size and alloying induced shift in core and valence bands of Pd-Ag and Pd-Cu nanoparticles

    NASA Astrophysics Data System (ADS)

    Sengar, Saurabh K.; Mehta, B. R.; Govind

    2014-03-01

    In this report, X-ray photoelectron spectroscopy studies have been carried out on Pd, Ag, Cu, Pd-Ag, and Pd-Cu nanoparticles having identical sizes corresponding to mobility equivalent diameters of 60, 40, and 20 nm. The nanoparticles were prepared by the gas phase synthesis method. The effect of size on valence and core levels in metal and alloy nanoparticles has been studied by comparing the values to those with the 60 nm nanoparticles. The effect of alloying has been investigated by comparing the valence and core level binding energies of Pd-Cu and Pd-Ag alloy nanoparticles with the corresponding values for Pd, Ag, and Cu nanoparticles of identical sizes. These effects have been explained in terms of size induced lattice contractions, alloying induced charge transfer, and hybridization effects. The observation of alloying and size induced binding energy shifts in bimetallic nanoparticles is important from the point of view of hydrogen reactivity.

  19. Physical preparation and optical properties of CuSbS2 nanocrystals by mechanical alloying process

    NASA Astrophysics Data System (ADS)

    Zhang, Huihui; Xu, Qishu; Tan, Guolong

    2016-09-01

    CuSbS2 nanocrystals have been synthesized through mechanical alloying Cu, Sb and S elemental powders for 40 hs. The optical spectrum of as-milled CuSbS2 nano-powders demonstrates a direct gap of 1.35 eV and an indirect gap of 0.36 eV, which are similar to that of silicon and reveals the evidence for the indirect semiconductor characterization of CuSbS2. Afterwards, CuSbS2 nanocrystals were capped with trioctylphosphine oxide/trioctylphosphine/pyridine (TOPO/TOP). There appear four sharp absorption peaks within the region of 315 to 355 nm for the dispersion solution containing the capped nanocrystals. The multiple peaks are proposed to be originating from the energy level splitting of 1S electronic state into four discrete sub-levels, where electrons were excited into the conduction band and thus four exciton absorption peaks were produced.

  20. Aberration-Corrected STEM Study of Precipitates in an Al-Mg-Si-Ge-Cu Alloy

    NASA Astrophysics Data System (ADS)

    Bjørge, Ruben; Andersen, Sigmund J.; Marioara, Calin D.; Etheridge, Joanne; Holmestad, Randi

    Precipitation in a Mg-rich Al-Mg-Si-Ge-Cu alloy was investigated using aberration-corrected high-angle annular dark-field scanning transmission electron microscopy. The precipitates were needle or lath shaped with the longest dimension parallel to <001>Al. The precipitates had no repeating unit cell when viewed along this direction. However, the precipitate structure in projection consisted of a hexagonal network of mixed Si and Ge columns, with Mg, Al, and Cu columns occupying specific sites in between the network columns. The Cu columns appeared with the same local arrangement of atomic columns as in Al-Mg-Si-Cu precipitates, and the Cu-free regions consisted of structural units with Mg and Al at specific sites. The proposed atomic model is supported by image simulations.

  1. Electrochemical performance of 2D polyaniline anchored CuS/Graphene nano-active composite as anode material for lithium-ion battery.

    PubMed

    Iqbal, Shahid; Bahadur, Ali; Saeed, Aamer; Zhou, Kebin; Shoaib, Muhammad; Waqas, Muhammad

    2017-09-15

    Lithium-ion battery (LIB) is a revolutionary step in the electric energy storage technology for making green environment. In the present communication, a LIB anode material was constructed by using graphene/polyaniline/CuS nanocomposite (GR/PANI/CuS NC) as a high-performance electrode. Initially, pure covellite CuS nanoplates (NPs) of the hexagonal structure were synthesized by hydrothermal route and then GR/PANI/CuS NC was fabricated by in-situ polymerization of aniline in the presence of CuS NPs and graphene nanosheets (GR NSs) as host matrix. GR/PANI/CuS NC-based LIB has shown the superior reversible current capacity of 1255mAhg(-1), a high cycling stability with more than 99% coulombic efficiency over 250 cycles even at a high current density of 5Ag(-1), low volume expansion, and excellent power capabilities. Galvanostatic charge/discharge tests and cyclic voltammetry analysis were used to investigate electrochemical properties. The electrochemical test proves that GR/PANI/CuS NC is promising anode material for LIB. The crystal phases and purity of the GR/PANI/CuS NC were confirmed by X-ray diffraction (XRD). Scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS) were employed to examine the morphology, size, chemical composition, and phase structure of the synthesized GR/PANI/CuS NC. Copyright © 2017. Published by Elsevier Inc.

  2. Low temperature growth of graphene on Cu-Ni alloy nanofibers for stable, flexible electrodes

    NASA Astrophysics Data System (ADS)

    Liu, Zheng-Dong; Yin, Zong-You; Du, Ze-Hui; Yang, Yang; Zhu, Min-Min; Xie, Ling-Hai; Huang, Wei

    2014-04-01

    Here, we report a facile approach to grow graphene on Cu-Ni alloy NFs at a temperature as low as 450-500 °C, in which solid polystyrene (PS) carbon source and two-temperature-zone furnace were used to prepare graphene. The graphene coated Cu-Ni (designated as G-coated Cu-Ni) NFs were fully characterized by Raman spectra, XPS, FESEM and TEM. The G-coated Cu-Ni NFs exhibited excellent anti-oxidation, anti-corrosion and flexibility properties. The anti-corrosion of G-coated Cu-Ni NFs was examined through cyclic voltammetry measurements by using sea water as the electrolyte solution. Finally, using crossed arrays of G-coated Cu-Ni NF composite electrode thin films (sheet resistance is ~10 Ω sq-1) as the flexible electrode, an alternating current (AC) electroluminescent (EL) device with a configuration of G-coated Cu-Ni/active layer (ZnS : Cu phosphor)/dielectric layer (BaTiO3)/front electrode (CNT) has been fabricated. Under an AC voltage of 200 V and frequency of 1300 Hz, the ACEL device emitted blue light at 496 nm with a brightness of 103 cd m-2.Here, we report a facile approach to grow graphene on Cu-Ni alloy NFs at a temperature as low as 450-500 °C, in which solid polystyrene (PS) carbon source and two-temperature-zone furnace were used to prepare graphene. The graphene coated Cu-Ni (designated as G-coated Cu-Ni) NFs were fully characterized by Raman spectra, XPS, FESEM and TEM. The G-coated Cu-Ni NFs exhibited excellent anti-oxidation, anti-corrosion and flexibility properties. The anti-corrosion of G-coated Cu-Ni NFs was examined through cyclic voltammetry measurements by using sea water as the electrolyte solution. Finally, using crossed arrays of G-coated Cu-Ni NF composite electrode thin films (sheet resistance is ~10 Ω sq-1) as the flexible electrode, an alternating current (AC) electroluminescent (EL) device with a configuration of G-coated Cu-Ni/active layer (ZnS : Cu phosphor)/dielectric layer (BaTiO3)/front electrode (CNT) has been fabricated. Under

  3. High resolution electron microscopy of metastable precipitates in a Cu-7. 8 at% Be alloy

    SciTech Connect

    Yamamoto, A.; Tsubakino, H. . Dept. of Materials Science and Engineering)

    1994-09-15

    It is known that three metastable phases, the G.P. zone, the [gamma][double prime] and the [gamma][prime] phase precipitate in Cu-rich, Cu-Be alloys prior to the precipitation of the stable [gamma] (CuBe) phase. In addition, a precursor to the G.P. zone was reported in the as-quenched state by Rioja and Laughlin, Koo et al. and Koo and Cohen, which is described as equiaxed'' or ellipsoidal'' Be clusters. There is little known about the phases ability to dissolve to form the following next phase or to continuously transform to the next, except for the formation of the [gamma][double prime] by a stacking of the G.P. zones. The authors of this study have recently suggested, based on the results of a calorimetric study of Cu-Be alloys, that the structure of the G.P. zones and the [gamma][double prime] gradually change with aging toward that of [gamma][double prime] and the [gamma][prime], respectively. The high resolution electron microscopy (HREM) is considered to be a suitable method for examining the structural changes in these precipitates. Therefore, in the present study, the precipitates formed in the Cu-Be alloy are observed in detail by HREM to clarify the relationship between their structures.

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

    PubMed

    Liu, Aihua; Geng, Haoran; Xu, Caixia; Qiu, Huajun

    2011-10-10

    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(2)PdCl(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 ~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(2)O(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). Copyright © 2011 Elsevier B.V. All rights reserved.

  5. Microstructures and Mechanical Properties of NiTiFeAlCu High-Entropy Alloys with Exceptional Nano-precipitates

    NASA Astrophysics Data System (ADS)

    Zhang, Yanqiu; Wang, Sibing; Jiang, Shuyong; Zhu, Xiaoming; Sun, Dong

    2017-01-01

    Three novel NiTiFeAlCu high-entropy alloys, which consist of nano-precipitates with face-centered cubic structure and matrix with body-centered cubic structure, were fabricated to investigate microstructures and mechanical properties. With the increase in Ni and Ti contents, the strength of NiTiFeAlCu alloy is enhanced, while the plasticity of NiTiFeAlCu alloy is lowered. Plenty of dislocations can be observed in the Ni32Ti32Fe12Al12Cu12 high-entropy alloy. The size of nano-precipitates decreases with the increase in Ni and Ti contents, while lattice distortion becomes more and more severe with the increase in Ni and Ti contents. The existence of nano-precipitates, dislocations and lattice distortion is responsible for the increase in the strength of NiTiFeAlCu alloy, but it has an adverse influence on the plasticity of NiTiFeAlCu alloy. Ni20Ti20Fe20Al20Cu20 alloy exhibits the substantial ability of plastic deformation and a characteristic of steady flow at 850 and 1000 °C. This phenomenon is attributed to a competition between the increase in the dislocation density induced by plastic strain and the decrease in the dislocation density due to the dynamic recrystallization.

  6. Microstructures and Mechanical Properties of NiTiFeAlCu High-Entropy Alloys with Exceptional Nano-precipitates

    NASA Astrophysics Data System (ADS)

    Zhang, Yanqiu; Wang, Sibing; Jiang, Shuyong; Zhu, Xiaoming; Sun, Dong

    2016-10-01

    Three novel NiTiFeAlCu high-entropy alloys, which consist of nano-precipitates with face-centered cubic structure and matrix with body-centered cubic structure, were fabricated to investigate microstructures and mechanical properties. With the increase in Ni and Ti contents, the strength of NiTiFeAlCu alloy is enhanced, while the plasticity of NiTiFeAlCu alloy is lowered. Plenty of dislocations can be observed in the Ni32Ti32Fe12Al12Cu12 high-entropy alloy. The size of nano-precipitates decreases with the increase in Ni and Ti contents, while lattice distortion becomes more and more severe with the increase in Ni and Ti contents. The existence of nano-precipitates, dislocations and lattice distortion is responsible for the increase in the strength of NiTiFeAlCu alloy, but it has an adverse influence on the plasticity of NiTiFeAlCu alloy. Ni20Ti20Fe20Al20Cu20 alloy exhibits the substantial ability of plastic deformation and a characteristic of steady flow at 850 and 1000 °C. This phenomenon is attributed to a competition between the increase in the dislocation density induced by plastic strain and the decrease in the dislocation density due to the dynamic recrystallization.

  7. Ab initio prediction of vacancy properties in concentrated alloys: The case of fcc Cu-Ni

    NASA Astrophysics Data System (ADS)

    Zhang, Xi; Sluiter, Marcel H. F.

    2015-05-01

    Vacancy properties in concentrated alloys continue to be of great interest because nowadays ab initio supercell simulations reach a scale where even defect properties in disordered alloys appear to be within reach. We show that vacancy properties cannot generally be extracted from supercell total energies in a consistent manner without a statistical model. Essential features of such a model are knowledge of the chemical potential and imposition of invariants. In the present work, we derive the simplest model that satisfies these requirements and we compare it with models in the literature. As illustration we compute ab initio vacancy properties of fcc Cu-Ni alloys as a function of composition and temperature. Ab initio density functional calculations were performed for SQS supercells at various compositions with and without vacancies. Various methods of extracting alloy vacancy properties were examined. A ternary cluster expansion yielded effective cluster interactions (ECIs) for the Cu-Ni-Vac system. Composition and temperature dependent alloy vacancy concentrations were obtained using statistical thermodynamic models with the ab initio ECIs. An Arrhenius analysis showed that the heat of vacancy formation was well represented by a linear function of temperature. The positive slope of the temperature dependence implies a negative configurational entropy contribution to the vacancy formation free energy in the alloy. These findings can be understood by considering local coordination effects.

  8. Factors Affecting the Hydrogen Environment Assisted Cracking Resistance of an AL-Zn-Mg-(Cu) Alloy

    SciTech Connect

    Young, G A; Scully, J R

    2002-04-09

    Precipitation hardenable Al-Zn-Mg alloys are susceptible to hydrogen environment assisted cracking (HEAC) when exposed to aqueous environments. In Al-Zn-Mg-Cu alloys, overaged tempers are used to increase HEAC resistance at the expense of strength but overaging has little benefit in low copper alloys. However, the mechanism or mechanisms by which overaging imparts HEAC resistance is poorly understood. The present research investigated hydrogen uptake, diffusion, and crack growth rate in 90% relative humidity (RH) air for both a commercial copper bearing Al-Zn-Mg-Cu alloy (AA 7050) and a low copper variant of this alloy in order to better understand the factors which affect HEAC resistance. Experimental methods used to evaluate hydrogen concentrations local to a surface and near a crack tip include nuclear reaction analysis (NRA), focused ion beam, secondary ion mass spectroscopy (FIB/SIMS) and thermal desorption spectroscopy (TDS). Results show that overaging the copper bearing alloys both inhibits hydrogen ingress from oxide covered surfaces and decreases the apparent hydrogen diffusion rates in the metal.

  9. Microstructure properties and microhardness of rapidly solidified Al64Cu20Fe12Si4 quasicrystal alloy

    NASA Astrophysics Data System (ADS)

    Karaköse, Ercan; Keskin, Mustafa

    2012-04-01

    This paper presents differences in the microstructure and microhardness properties of conventional casting (ingot) and rapidly solidified Al64Cu20Fe12Si4 quasicrystal (QC) alloys. The phases present in the Al64Cu20Fe12Si4 ingot alloy were determined to be icosahedral quasicrystalline (IQC) Ψ-Al65Cu20Fe15, cubic β-AlFe, tetragonal θ-Al2Cu, and monoclinic λ-A13Fe4 phases, whereas only IQC Ψ-Al65Cu20Fe15 and cubic β-AlFe phases were identified in the rapidly solidified alloy. The microhardness value of the melt spun alloy was measured to be approximately 790 kg/mm2. Microhardness increases with increasing solidification rates.

  10. Vacuum Plasma Spray of CuCrNb Alloy for Advanced Liquid - Fuel Combustion Chambers

    NASA Technical Reports Server (NTRS)

    Zimmerman, Frank

    2000-01-01

    The copper-8 atomic percent chromium-4 atomic percent niobium (CuCrNb) alloy was developed by Glenn Research Center (formally Lewis Research Center) as an improved alloy for combustion chamber liners. In comparison to NARloy-Z, the baseline (as in Space Shuttle Main Engine) alloy for such liners, CuCrNb demonstrates mechanical and thermophysical properties equivalent to NARloy-Z, but at temperatures 100 C to 150 C (180 F to 270 F) higher. Anticipated materials related benefits include decreasing the thrust cell liner weight 5% to 20%, increasing the service life at least two fold over current combustion chamber design, and increasing the safety margins available to designers. By adding an oxidation and thermal barrier coating to the liner, the combustion chamber can operate at even higher temperatures. For all these benefits, however, this alloy cannot be formed using conventional casting and forging methods because of the levels of chromium and niobium, which exceed their solubility limit in copper. Until recently, the only forming process that maintains the required microstructure of CrNb intermetallics is powder metallurgy formation of a billet from powder stock, followed by extrusion. This severely limits its usefulness in structural applications, particularly the complex shapes required for combustion chamber liners. Vacuum plasma spray (VPS) has been demonstrated as a method to form structural articles including small combustion chambers from the CuCrNb alloy. In addition, an oxidation and thermal barrier layer can be formed integrally on the hot wall of the liner that improve performance and extend service life. This paper discusses the metallurgy and thermomechanical properties of VPS formed CuCrNb versus the baseline powder metallurgy process, and the manufacturing of small combustion chamber liners at Marshall Space Flight Center using the VPS process. The benefits to advanced propulsion initiatives of using VPS to fabricate combustion chamber liners

  11. Vacuum Plasma Spray of CuCrNb Alloy for Advanced Liquid - Fuel Combustion Chambers

    NASA Technical Reports Server (NTRS)

    Zimmerman, Frank

    2000-01-01

    The copper-8 atomic percent chromium-4 atomic percent niobium (CuCrNb) alloy was developed by Glenn Research Center (formally Lewis Research Center) as an improved alloy for combustion chamber liners. In comparison to NARloy-Z, the baseline (as in Space Shuttle Main Engine) alloy for such liners, CuCrNb demonstrates mechanical and thermophysical properties equivalent to NARloy-Z, but at temperatures 100 C to 150 C (180 F to 270 F) higher. Anticipated materials related benefits include decreasing the thrust cell liner weight 5% to 20%, increasing the service life at least two fold over current combustion chamber design, and increasing the safety margins available to designers. By adding an oxidation and thermal barrier coating to the liner, the combustion chamber can operate at even higher temperatures. For all these benefits, however, this alloy cannot be formed using conventional casting and forging methods because of the levels of chromium and niobium, which exceed their solubility limit in copper. Until recently, the only forming process that maintains the required microstructure of CrNb intermetallics is powder metallurgy formation of a billet from powder stock, followed by extrusion. This severely limits its usefulness in structural applications, particularly the complex shapes required for combustion chamber liners. Vacuum plasma spray (VPS) has been demonstrated as a method to form structural articles including small combustion chambers from the CuCrNb alloy. In addition, an oxidation and thermal barrier layer can be formed integrally on the hot wall of the liner that improve performance and extend service life. This paper discusses the metallurgy and thermomechanical properties of VPS formed CuCrNb versus the baseline powder metallurgy process, and the manufacturing of small combustion chamber liners at Marshall Space Flight Center using the VPS process. The benefits to advanced propulsion initiatives of using VPS to fabricate combustion chamber liners

  12. Superconducting properties of Nb-Cu nano-composites and nano-alloys

    NASA Astrophysics Data System (ADS)

    Parab, Pradnya; Kumar, Sanjeev; Bhui, Prabhjyot; Bagwe, Vivas; Bose, Sangita

    2016-05-01

    The evolution of the superconducting transition temperature (Tc) in nano-composite and nano-alloys of Nb-Cu, grown by DC magnetron co-sputtering are investigated. Microstructure of these films depends less strongly on the ratio of Nb:Cu but more on the growth temperature. At higher growth temperature, phase separated granular films of Nb and Cu were formed which showed superconducting transition temperatures (Tc) of ~ 7.2±0.5K, irrespective of the composition. Our results show that this is primarily influenced by the microstructure of the films determined during growth which rules out the superconducting proximity effect expected in these systems. At room temperature growth, films with nano-scale alloying were obtained at the optimal compositional range of 45-70 atomic% (At%) of Nb. These were also superconducting with a Tc of 3.2K.

  13. Superconducting properties of Nb-Cu nano-composites and nano-alloys

    SciTech Connect

    Parab, Pradnya Kumar, Sanjeev; Bhui, Prabhjyot; Bose, Sangita; Bagwe, Vivas

    2016-05-23

    The evolution of the superconducting transition temperature (T{sub c}) in nano-composite and nano-alloys of Nb-Cu, grown by DC magnetron co-sputtering are investigated. Microstructure of these films depends less strongly on the ratio of Nb:Cu but more on the growth temperature. At higher growth temperature, phase separated granular films of Nb and Cu were formed which showed superconducting transition temperatures (T{sub c}) of ~ 7.2±0.5 K, irrespective of the composition. Our results show that this is primarily influenced by the microstructure of the films determined during growth which rules out the superconducting proximity effect expected in these systems. At room temperature growth, films with nano-scale alloying were obtained at the optimal compositional range of 45-70 atomic% (At%) of Nb. These were also superconducting with a T{sub c} of 3.2 K.

  14. Electron Transport Properties of Aluminium Substituted CuTi Amorphous Alloys

    NASA Astrophysics Data System (ADS)

    Bhatnagar, A. K.; Fritsch, G.; Naugle, D. G.; Haberkern, R.; Kandlbinder, M.; Lindqvist, P.

    Room temperature electrical resistivity (ρ), temperature coefficient of resistivity (α) and Hall coefficient (RH) of (Cu1-yTiy)1-xAlx amorphous alloys, where y=0.36, 0.50 and 0.64 and x=0, 0.05 and 0.10 are presented. The low temperature dependence of resistivity and magnetoresistivity of a-(Cu0.36Ti0.64)1-xAlx are also presented and discussed qualitatively in terms of quantum corrections. It is found that the addition of Al in a-Cu0.36Ti0.64 alloy decreases the spin-orbit scattering time τso.

  15. Electron transport properties of aluminium substituted CuTi amorphous alloys

    SciTech Connect

    Bhatnagar, A.K.; Fritsch, G.; Haberkern, R.; Kandlbinder, M.; Lindqvist, P.; Naugle, D.G.

    1997-01-30

    Room temperature electrical resistivity ({rho}) temperature coefficient of resistivity ({alpha}) and Hall coefficient (R{sub H}) of (Cu{sub 1{minus}y}Ti{sub y}){sub 1{minus}x}Al{sub x} amorphous alloys, where y = 0.36, 0.50 and 0.64 and x = 0, 0.05 and 0.10 are presented. The low temperature dependence of resistivity and magnetoresistivity of a-(Cu{sub 0.36}Ti{sub 0.64}){sub 1{minus}x}Al{sub x} are also presented and discussed qualitatively in terms of quantum corrections. It is found that the addition of Al in a Cu{sub 0.36}Ti{sub 0.64} alloy decreases the spin-orbit scattering time {tau}{sub so}.

  16. Optical analysis of lens-like Cu2CdSnS4 quaternary alloy nanostructures

    NASA Astrophysics Data System (ADS)

    Odeh, Ali Abu; Al-Douri, Y.; Ayub, R. M.; Ameri, M.; Bouhemadou, A.; Prakash, Deo; Verma, K. D.

    2016-10-01

    Cu2CdSnS4 quaternary alloy nanostructures with different copper concentrations (0.2, 0.4, 0.6, 0.8 and 1.0 M) were successfully synthesized on n-type silicon substrates using spin coating technique with annealing temperature at 300 °C. Optical properties were analyzed through UV-Vis and Photoluminescence spectroscopies, and thus, there is a change in energy band gap with increasing Cu concentration from 0.2 to 1.0 M. The structural properties of Cu2CdSnS4 quaternary alloy nanostructures were investigated by X-ray diffraction. The particles size and shape have a direct relationship with copper concentration. Morphological and topographical studies were carried out by using scanning electron microscopy and atomic force microscopy. The obtained results are investigated to be available in the literature for future studies.

  17. Enhanced spin Hall effect by electron correlations in CuBi alloys

    SciTech Connect

    Gu, Bo Xu, Zhuo; Mori, Michiyasu; Maekawa, Sadamichi; Ziman, Timothy

    2015-05-07

    A recent experiment in CuBi alloys obtained a large spin Hall angle (SHA) of −0.24 (Niimi et al., Phys. Rev. Lett. 109, 156602 (2012)). We find that the SHA can be dramatically enhanced by Bi impurities close to the Cu surface. The mechanisms of this enhancement are two-fold. One is that the localized impurity state on surface has a decreased hybridization and combined with Coulomb correlation effect. The other comes from the low-dimensional state of conduction electrons on surface, which results in a further enhancement of skew scattering by impurities. Furthermore, we note that a discrepancy in sign of SHA between the experiment and previous theories is simply caused by different definitions of SHA. This re-establishes skew scattering as the essential mechanism underlying the spin Hall effect in CuBi alloys.

  18. Thermal Stability and Tensile Properties of Electrodeposited Cu-Bi Alloy

    NASA Astrophysics Data System (ADS)

    Chen, Xianhua; Mao, Jianjun

    2011-04-01

    By means of pulse electrodeposition technique, a nanocrystalline Cu-0.42at.%Bi alloy with a grain size down to ~10 nm was synthesized. The thermal stability of Cu-Bi electrodeposit was investigated using differential scanning calorimetry (DSC), x-ray diffraction (XRD), transmission electron microscopy (TEM), and hardness measurements. The temperature at which this material tends to become unstable was found to be 160 °C. DSC revealed an exothermal peak between 190 and 300 °C, caused by grain growth. It was observed that segregation of Bi at grain boundary has a considerable effect on the thermal stability of the Cu-Bi alloy. Tensile test showed the sample interestingly possesses a high strength of 760 MPa, while no plastic strain is detected.

  19. Interconnection between microstructure and microhardness of directionally solidified binary Al-6wt.%Cu and multicomponent Al-6wt.%Cu-8wt.%Si alloys.

    PubMed

    Vasconcelos, Angela J; Kikuchi, Rafael H; Barros, André S; Costa, Thiago A; Dias, Marcelino; Moreira, Antonio L; Silva, Adrina P; Rocha, Otávio L

    2016-05-31

    An experimental study has been carried out to evaluate the microstructural and microhardness evolution on the directionally solidified binary Al-Cu and multicomponent Al-Cu-Si alloys and the influence of Si alloying. For this purpose specimens of Al-6wt.%Cu and Al-6wt.%Cu-8wt.%Si alloys were prepared and directionally solidified under transient conditions of heat extraction. A water-cooled horizontal directional solidification device was applied. A comprehensive characterization is performed including experimental dendrite tip growth rates (VL) and cooling rates (TR) by measuring Vickers microhardness (HV), optical microscopy and scanning electron microscopy with microanalysis performed by energy dispersive spectrometry (SEM-EDS). The results show, for both studied alloys, the increasing of TR and VL reduced the primary dendrite arm spacing (l1) increasing the microhardness. Furthermore, the incorporation of Si in Al-6wt.%Cu alloy to form the Al-6wt.%Cu-8wt.%Si alloy influenced significantly the microstructure and consequently the microhardness but did not affect the primary dendritic growth law. An analysis on the formation of the columnar to equiaxed transition (CET) is also performed and the results show that the occurrence of CET is not sharp, i.e., the CET in both cases occurs in a zone rather than in a parallel plane to the chill wall, where both columnar and equiaxed grains are be able to exist.

  20. Evaluation of the amalgamation reaction of experimental Ag-Sn-Cu alloys containing Pd using a mercury plating technique.

    PubMed

    Koike, Marie; Ferracane, Jack L; Fujii, Hiroyuki; Okabe, Toru

    2003-09-01

    A mercury plating technique was used to determine the phases forming on experimental Ag-Sn-Cu alloy powders (with and without Pd) exposed to electrolytically deposited mercury. Four series of alloy powders were made: a) 1.5% Pd with 10-14% Cu (CU series); b) 1.0% Pd with 10-14% Cu (1PD series); c) 1.5% Pd with different ratios of Ag3Sn (gamma) to Ag4Sn (beta) with 12% Cu (AGSN series); and d) 9-13% Cu with no Pd (NOPD series). Each powder was pressed on a freshly prepared amalgam specimen made from the same powder and metallographically polished until cross sections appeared; mercury was electroplated on the alloy particles. Alloy powders, amalgams and electroplated specimens were examined using XRD and SEM/EDS. XRD confirmed the presence of gamma2 in amalgams made from alloys with Cu < 13% or with Ag3Sn/Ag4Sn > 0.8. Specimens with moderately plated Hg showed gamma1 (Ag2Hg3) polyhedra and eta' Cu6Sn5, but not gamma2. This method effectively identifies alloys prone to forming gamma2.

  1. On the evolution of Cu-Ni-rich bridges of Alnico alloys with tempering

    NASA Astrophysics Data System (ADS)

    Fan, M.; Liu, Y.; Jha, Rajesh; Dulikravich, George S.; Schwartz, J.; Koch, C. C.

    2016-12-01

    Tempering is a critical step in Alnico alloy processing, yet the effects of tempering on microstructure have not been well studied. Here we report these effects, and in particular the effects on the Cu-Ni bridges. Energy-dispersive X-ray spectroscopy (EDS) maps and line scans show that tempering changes the elemental distribution in the Cu-Ni bridges, but not the morphology and distribution of Cu-bridges. The Cu concentration in the Cu-Ni bridges increases after tempering while other element concentrations decrease, especially Ni and Al. Furthermore, tempering sharpens the Cu bridge boundaries. These effects are primarily related to the large 2C44/(C11-C12) ratio for Cu, largest of all elements in Alnico. In addition, the Ni-Cu loops around the α1 phases become inconspicuous with tempering. The diffusion of Fe and Co to the α1 phase during tempering, which increases the difference of saturation magnetization between the α1 and α2 phases, is observed by EDS. In summary, α1, α2 and Cu-bridges are concentrated with their major elements during tempering which improves the magnetic properties. The formation of these features formed through elemental diffusion is discussed via energy theories.

  2. Facile synthesis of novel tunable highly porous CuO nanorods for high rate lithium battery anodes with realized long cycle life and high reversible capacity.

    PubMed

    Wang, Linlin; Gong, Huaxu; Wang, Caihua; Wang, Dake; Tang, Kaibin; Qian, Yitai

    2012-11-07

    Various CuO nanostructures have been well studied as anode materials for lithium ion batteries (LIBs); however, there are few reports on the synthesis of porous CuO nanostructures used for anode materials, especially one-dimensional (1D) porous CuO. In this work, novel 1D highly porous CuO nanorods with tunable porous size were synthesized in large-quantities by a new, friendly, but very simple approach. We found that the pore size could be controlled by adjusting the sintering temperature in the calcination process. With the rising of calcination temperature, the pore size of CuO has been tuned in the range of ∼0.4 nm to 22 nm. The porous CuO materials have been applied as anode materials in LIBs and the effects of porous size on the electrochemical properties were observed. The highly porous CuO nanorods with porous size in the range of ∼6 nm to 22 nm yielded excellent high specific capacity, good cycling stability, and high rate performance, superior to that of most reported CuO nanocomposites. The CuO material delivers a high reversible capacity of 654 mA h g(-1) and 93% capacity retention over 200 cycles at a rate of 0.5 C. It also exhibits excellent high rate capacity of 410 mA h g(-1) even at 6 C. These results suggest that the facile synthetic method of producing a tunable highly porous CuO nanostructure can realize a long cycle life with high reversible capacity, which is suitable for next-generation high-performance LIBs.

  3. Compositionally graded SiCu thin film anode by magnetron sputtering for lithium ion battery

    SciTech Connect

    Polat, B. D.; Eryilmaz, O. L.; Keles, O; Erdemir, A; Amine, Khalil

    2015-10-22

    Compositionally graded and non-graded composite SiCu thin films were deposited by magnetron sputtering technique on Cu disks for investigation of their potentials in lithium ion battery applications. The compositionally graded thin film electrodes with 30 at.% Cu delivered a 1400 mAh g-1 capacity with 80% Coulombic efficiency in the first cycle and still retained its capacity at around 600 mAh g-1 (with 99.9% Coulombic efficiency) even after 100 cycles. On the other hand, the non-graded thin film electrodes with 30 at.% Cu exhibited 1100 mAh g-1 as the first discharge capacity with 78% Coulombic efficiency but the cycle life of this film degraded very quickly, delivering only 250 mAh g-1 capacity after 100th cycles. Not only the Cu content but also the graded film thickness were believed to be the main contributors to the much superior performance of the compositionally graded SiCu films. We also believe that the Cu-rich region of the graded film helped reduce internal stress build-up and thus prevented film delamination during cycling. In particular, the decrease of Cu content from interface region to the top of the coating reduced the possibility of stress build-up across the film during cycling, thus leading to a high electrochemical performance.

  4. Vacancy trapping by solute atoms during quenching in Cu-based dilute alloys studied by positron annihilation spectroscopy

    NASA Astrophysics Data System (ADS)

    Yabuuchi, A.; Yamamoto, Y.; Ohira, J.; Sugita, K.; Mizuno, M.; Araki, H.; Shirai, Y.

    2009-11-01

    Frozen-in vacancies and the recovery have been investigated in some Cu-based dilute alloys by using positron annihilation lifetime spectroscopy. Cu-0.5at%Sb, Cu-0.5at%Sn and Cu-0.5at%In dilute bulk alloys were quenched to ice water from 1223 K. A pure-Cu specimen was also quenched from the same temperature. As a result, no frozen-in vacancies have been detected in as-quenched pure-Cu specimen. On the other hand, as-quenched Cu-0.5at%Sb alloy contained frozen-in thermal equilibrium vacancies with concentration of 3 × 10-5. Furthermore, these frozen-in vacancies in Cu-0.5at%Sb alloy were stable until 473 K, and began to migrate at 523 K. Finally, the Cu-Sb alloy were recovered to the fully annealed state at 823 K. This thermal stability clearly implies some interaction exists between a vacancy and Sb atom and due to the interaction, thermal equilibrium vacancies are trapped by Sb atoms during quenching.

  5. Effect of cooling rate on the microstructure and microhardness of the CuZrAgAl alloy

    SciTech Connect

    Liu, Y.; Blandin, J.J.; Suery, M.; Kapelski, G.

    2012-08-15

    The effect of cooling rate on the microstructure and microhardness of the Cu{sub 40}Zr{sub 44}Ag{sub 8}Al{sub 8} (at.%) alloy has been studied. The crystalline phases were characterized by X-ray diffraction, optical microscopy and scanning electron microscopy with energy dispersive X-ray spectroscopy, and identified as AlCu{sub 2}Zr, Cu{sub 10}Zr{sub 7} and CuZr{sub 2}. The solidification sequence was established as following: the Cu{sub 10}Zr{sub 7} phase forms first in the periphery of the rod, then following with AlCu{sub 2}Zr phase in the rod center and finally CuZr{sub 2} crystals in Cu-depleted areas. The effect of crystals on the mechanical properties of the Cu{sub 40}Zr{sub 44}Ag{sub 8}Al{sub 8} alloy was also estimated through the microhardness. According to the value of microhardness, inhomogeneous structure of the amorphous matrix is more easily formed for the alloy in the low cooling rate (i.e., 9 mm) as compared with the alloy with fully amorphous state in the large cooling rate (i.e., 3 mm). This inhomogeneous structure was attributed to the composition change of amorphous matrix arising from the forming of crystalline phases due to the low cooling rate. - Highlights: Black-Right-Pointing-Pointer The crystalline phases in the Cu{sub 40}Zr{sub 44}Ag{sub 8}Al{sub 8} alloy were identified. Black-Right-Pointing-Pointer The solidification sequence of Cu{sub 40}Zr{sub 44}Ag{sub 8}Al{sub 8} alloy was verified. Black-Right-Pointing-Pointer The softening and hardening of alloy could be observed due to the crystallization.

  6. Metallographic preparation of Zn-21Al-2Cu alloy for analysis by electron backscatter diffraction (EBSD).

    PubMed

    Rodríguez-Hernández, M G; Martínez-Flores, E E; Torres-Villaseñor, G; Escalera, M Dolores

    2014-08-01

    Samples of Zn-21Al-2Cu alloy (Zinalco) that will be heavily deformed were prepared using five different manual mechanical metallographic methods. Samples were analyzed before tensile testing using the orientation imaging microscopy-electron backscatter diffraction (OIM-EBSD) technique. The effect of type and particle size during the final polishing stages for this material were studied in order to identify a method that produces a flat, damage free surface with a roughness of about 50 nm and clean from oxide layers, thereby producing diffraction patterns with high image quality (IQ) and adequate confidence indexes (CI). Our results show that final polishing with alumina and silica, as was previously suggested by other research groups for alloys that are difficult to prepare or alloys with low melting point, are not suitable for manual metallographic preparation of this alloy. Indexes of IQ and CI can be used to evaluate methods of metallographic preparation of samples studied using the OIM-EBSD technique.

  7. Microstructure-property relationships in Al-Cu-Li-Ag-Mg Weldalite (tm) alloys, part 2

    NASA Technical Reports Server (NTRS)

    Langan, T. J.; Pickens, J. R.

    1991-01-01

    The microstructure and mechanical properties of the ultrahigh strength Al-Cu-Li-Ag-Mg alloy, Weldalite (tm) 049, were studied. Specifically, the microstructural features along with tensile strength, weldability, Young's modulus and fracture toughness were studied for Weldalite (tm) 049 type alloys with Li contents ranging from 1.3 to 1.9 wt. pct. The tensile properties of Weldalite 049 and Weldalite 049 reinforced with TiB2 particles fabricated using the XD (tm) process were also evaluated at cryogenic, room, and elevated temperatures. In addition, an experimental alloy, similar in composition to Weldalite 049 but without the Ag+Mg, was fabricated. The microstructure of this alloy was compared with that of Weldalite 049 in the T6 condition to assess the effect of Ag+Mg on nucleation of strengthening phases in the absence of cold work.

  8. Electrodeposition of high corrosion resistance Cu/Ni-P coating on AZ91D magnesium alloy

    NASA Astrophysics Data System (ADS)

    Zhang, Shan; Cao, Fahe; Chang, Linrong; Zheng, JunJun; Zhang, Zhao; Zhang, Jianqing; Cao, Chunan

    2011-08-01

    High corrosion resistance Cu/Ni-P coatings were electrodeposited on AZ91D magnesium alloy via suitable pretreatments, such as one-step acid pickling-activation, once zinc immersion and environment-friendly electroplated copper as the protective under-layer, which made Ni-P deposit on AZ91D Mg alloy in acid plating baths successfully. The pH value and current density for Ni-P electrodeposition were optimized to obtain high corrosion resistance. With increasing the phosphorous content of the Ni-P coatings, the deposits were found to gradually transform to amorphous structure and the corrosion resistance increased synchronously. The anticorrosion ability of AZ91D Mg alloy was greatly improved by the amorphous Ni-P deposits, which was investigated by potentiodynamic polarization curve and electrochemical impedance spectroscopy (EIS). The corrosion current density ( Icorr) of the coated Mg alloy substrate is about two orders of magnitude less than that of the uncoated.

  9. Novel high-strength NiCuCoTiTa alloy with plasticity

    NASA Astrophysics Data System (ADS)

    Samal, Sumanta; Biswas, Krishanu

    2013-07-01

    The present investigation reports a novel Ni-Ti-based Ni48Cu10Co2Ti38Ta2 alloy, obtained by arc melting cum suction casting route under ultrahigh-purity Ar atmosphere. X-ray diffractometer, scanning electron microscopy, and transmission electron microscopy (TEM) investigations reveal a microstructure consisting of nanostructured eutectic between cubic NiTi and hexagonal Ni3Ti with micron-scale NiTi and cubic Ti2Ni dendrites. Detailed TEM investigation indicates substantial reduction in the interlamellar spacing as the alloy chemistry changes from binary to quinary. The alloy shows a high compressive strength, 2 GPa, with high plasticity 13 %. Fractography surface of this new alloy reveals mixed mode of fracture. The results are discussed in light of the available literature on deformation of nanostructured eutectic with micron-sized dendrites in the microstructures.

  10. Electrolytic production of metals using a resistant anode

    DOEpatents

    Tarcy, Gary P.; Gavasto, Thomas M.; Ray, Siba P.

    1986-01-01

    An electrolytic process comprising evolving oxygen on an anode in a molten salt, the anode comprising an alloy comprising a first metal and a second metal, both metals forming oxides, the oxide of the first metal being more resistant than the second metal to attack by the molten salt, the oxide of the second metal being more resistant than the first metal to the diffusion of oxygen. The electrode may also be formed of CuAlO.sub.2 and/or Cu.sub.2 O.

  11. Electrolytic production of metals using a resistant anode

    DOEpatents

    Tarcy, G.P.; Gavasto, T.M.; Ray, S.P.

    1986-11-04

    An electrolytic process is described comprising evolving oxygen on an anode in a molten salt, the anode comprising an alloy comprising a first metal and a second metal, both metals forming oxides, the oxide of the first metal being more resistant than the second metal to attack by the molten salt, the oxide of the second metal being more resistant than the first metal to the diffusion of oxygen. The electrode may also be formed of CuAlO[sub 2] and/or Cu[sub 2]O. 2 figs.

  12. Kinetics and Equilibrium of Age-Induced Precipitation in Cu-4 At. Pct Ti Binary Alloy

    NASA Astrophysics Data System (ADS)

    Semboshi, Satoshi; Amano, Shintaro; Fu, Jie; Iwase, Akihiro; Takasugi, Takayuki

    2017-03-01

    Transformation kinetics and phase equilibrium of metastable and stable precipitates in age-hardenable Cu-4 at. pct Ti binary alloy have been investigated by monitoring the microstructural evolution during isothermal aging at temperatures between 693 K (420 °C) and 973 K (700 °C). The microstructure of the supersaturated solid solution evolves in four stages: compositional modulation due to spinodal decomposition, continuous precipitation of the needle-shaped metastable β'-Cu4Ti with a tetragonal structure, discontinuous precipitation of cellular components containing stable β-Cu4Ti lamellae with an orthorhombic structure, and eventually precipitation saturation at equilibrium. In specimens aged below 923 K (650 °C), the stable β-Cu4Ti phase is produced only due to the cellular reaction, whereas it can be also directly obtained from the intergranular needle-shaped β'-Cu4Ti precipitates in specimens aged at 973 K (700 °C). The precipitation kinetics and phase equilibrium observed for the specimens aged between 693 K (420 °C) and 973 K (700 °C) were characterized in accordance with a time-temperature-transformation (TTT) diagram and a Cu-Ti partial phase diagram, which were utilized to determine the alloy microstructure, strength, and electrical conductivity.

  13. Kinetics and Equilibrium of Age-Induced Precipitation in Cu-4 At. Pct Ti Binary Alloy

    NASA Astrophysics Data System (ADS)

    Semboshi, Satoshi; Amano, Shintaro; Fu, Jie; Iwase, Akihiro; Takasugi, Takayuki

    2017-01-01

    Transformation kinetics and phase equilibrium of metastable and stable precipitates in age-hardenable Cu-4 at. pct Ti binary alloy have been investigated by monitoring the microstructural evolution during isothermal aging at temperatures between 693 K (420 °C) and 973 K (700 °C). The microstructure of the supersaturated solid solution evolves in four stages: compositional modulation due to spinodal decomposition, continuous precipitation of the needle-shaped metastable β'-Cu4Ti with a tetragonal structure, discontinuous precipitation of cellular components containing stable β-Cu4Ti lamellae with an orthorhombic structure, and eventually precipitation saturation at equilibrium. In specimens aged below 923 K (650 °C), the stable β-Cu4Ti phase is produced only due to the cellular reaction, whereas it can be also directly obtained from the intergranular needle-shaped β'-Cu4Ti precipitates in specimens aged at 973 K (700 °C). The precipitation kinetics and phase equilibrium observed for the specimens aged between 693 K (420 °C) and 973 K (700 °C) were characterized in accordance with a time-temperature-transformation (TTT) diagram and a Cu-Ti partial phase diagram, which were utilized to determine the alloy microstructure, strength, and electrical conductivity.

  14. Intermetallic Formation and Fluidity in Sn-Rich Sn-Cu-Ni Alloys

    NASA Astrophysics Data System (ADS)

    Gourlay, C. M.; Nogita, K.; Read, J.; Dahle, A. K.

    2010-01-01

    This paper investigates the phase equilibria and solidification behavior of Sn-Cu-Ni alloys with compositions in the range of 0 wt.% to 1.5 wt.% Cu and 0 wt.% to 0.3 wt.% Ni. The isothermal section at 268°C in the Sn-rich corner was determined. No evidence for a ternary phase was found, and the section is in good agreement with past experimental studies that report wide solubility ranges for (Cu,Ni)6Sn5 and (Ni,Cu)3Sn4. The vacuum fluidity test was applied to compositions that are liquid at 268°C to map the variation in microstructure and flow behavior with composition in this system. Significant variations in fluidity length were measured among the Sn-Cu-Ni alloys, and the variations correlate with the microstructure that develops during solidification. The generated fluidity map enables the selection of Sn-Cu-Ni solder compositions that exhibit good fluidity behavior during solidification and form near-eutectic microstructures.

  15. Cu3Si@Si core-shell nanoparticles synthesized using a solid-state reaction and their performance as anode materials for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Zhou, Jianbin; Lin, Ning; Han, Ying; Zhou, Jie; Zhu, Yongchun; Du, Jin; Qian, Yitai

    2015-09-01

    Cu3Si@Si core-shell nanoparticles with a Si shell coated over the Cu3Si core are synthesized by a solid-state reaction between CuCl and Si. The evaluation process of the core-shell structure shows a mechanism analogous to the Kirkendall effect. As anode materials for lithium ion batteries, Cu3Si@Si core-shell nanoparticles retained a capacity of 903.6 mA h g-1 at the current density of 2 A g-1 over 400 cycles.Cu3Si@Si core-shell nanoparticles with a Si shell coated over the Cu3Si core are synthesized by a solid-state reaction between CuCl and Si. The evaluation process of the core-shell structure shows a mechanism analogous to the Kirkendall effect. As anode materials for lithium ion batteries, Cu3Si@Si core-shell nanoparticles retained a capacity of 903.6 mA h g-1 at the current density of 2 A g-1 over 400 cycles. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr04456a

  16. Effect of Sn4+ Additives on the Microstructure and Corrosion Resistance of Anodic Coating Formed on AZ31 Magnesium Alloy in Alkaline Solution

    NASA Astrophysics Data System (ADS)

    Salman, S. A.; Kuroda, K.; Saito, N.; Okido, M.

    Magnesium is the lightest structural metal with high specific strength and good mechanical properties. However, poor corrosion resistance limits its widespread use in many applications. Magnesium is usually treated with Chromate conversion coatings. However, due to changing environmental regulations and pollution prevention requirements, a significant push exists to find new, alternative for poisonous Cr6+. Therefore, we aim to improve corrosion resistance of anodic coatings on AZ31 alloys using low cost non-chromate electrolyte. Anodizing was carried out in alkaline solutions with tin additives. The effect of tin additives on the coating film was characterized by SEM and XRD. The corrosion resistance was evaluated using anodic and cathodic polarizations and electrochemical impedance spectroscopy (EIS). Corrosion resistance property was improved with tin additives and the best anti-corrosion property was obtained with addition of 0.03 M Na2SnO3.3H2O to anodizing solution.

  17. A new type of Cu-Al-Ta shape memory alloy with high martensitic transformation temperature

    NASA Astrophysics Data System (ADS)

    Wang, C. P.; Su, Y.; Y Yang, S.; Shi, Z.; Liu, X. J.

    2014-02-01

    In this study, a new type of Cu-Al-Ta (Cu86Al12Ta2 wt%) shape memory alloy with high martensitic transformation temperature is explored. The microstructure, reversible martensitic transformation and shape memory properties are investigated by means of optical microscopy, back-scattered electron, electron probe microanalysis, x-ray diffraction, differential scanning calorimetry and tensile tests. It is proposed that Cu86Al12Ta2 alloy consists of a mixture of primarily {\\beta }_{1}^{\\prime} martensite and a little {\\gamma }_{1}^{\\prime} martensite and some different precipitates. The tiny thin-striped Ta2(Al,Cu)3 precipitate is predominant in the as-quenched condition, whereas the particle-shaped Cu(Al, Ta) precipitate is dominant after hot-rolling. Additionally, the dendritic-shaped γ1(Cu9Al4) phase begins to appear after hot-rolling, but it disappears when the sample is re-quenched. All studied samples have reversible martensitic transformation temperatures higher than 450 ° C. The results show that two-step martensitic transformation behavior is observed for Cu86Al12Ta2 alloy in all three different conditions due to the transformations between ({\\beta }_{1}^{\\prime}+{\\gamma }_{1}^{\\prime}) martensites and the austenite parent phase. The results further show that the recovery ratios are almost 100% when the pre-strains are ≤2.5%, then they gradually decrease with further increase of the pre-strains. The shape memory effects clearly increase as a result of increase of the pre-strains, up to a maximum value of 3.2%.

  18. Strain relaxation in nm-thick Cu and Cu-alloy films bonded to a rigid substrate

    NASA Astrophysics Data System (ADS)

    Herrmann, Ashley Ann Elizabeth

    In the wide scope of modern technology, nm-thick metallic films are increasingly used as lubrication layers, optical coatings, plating seeds, diffusion barriers, adhesion layers, metal contacts, reaction catalyzers, etc. A prominent example is the use of nm-thick Cu films as electroplating seed layers in the manufacturing of integrated circuits (ICs). These high density circuits are linked by on-chip copper interconnects, which are manufactured by filling Cu into narrow trenches by electroplating. The Cu fill by electroplating requires a thin Cu seed deposited onto high-aspect-ratio trenches. In modern ICs, these trenches are approaching 10 nm or less in width, and the seed layers less than 1 nm in thickness. Since nm-thick Cu seed layers are prone to agglomeration or delamination, achieving uniform, stable and highly-conductive ultra-thin seeds has become a major manufacturing challenge. A fundamental understanding of the strain behavior and thermal stability of nm-thick metal films adhered to a rigid substrate is thus critically needed. In this study, we focus on understanding the deformation modes of nm-thick Cu and Cu-alloy films bonded to a rigid Si substrate and under compressive stress. The strengthening of Cu films through alloying is also studied. In-situ transport measurements are used to monitor the deformation of such films as they are heated from room temperature to 400 °C. Ex-situ AFM is then used to help characterize the mode of strain relaxation. The relaxation modes are known to be sensitive to the wetting and adhesive properties of the film-substrate interface. We use four different liners (Ta, Ru, Mo and Co), interposed between the film and substrate to provide a wide range of interfacial properties to study their effect on the film's thermal stability. Our measurements indicate that when the film/liner interfacial energy is low, grain growth is the dominant relaxation mechanism. As the interface energy increases, grain growth is suppressed, and

  19. Grain Refinement and Mechanical Properties of Cu-Cr-Zr Alloys with Different Nano-Sized TiCp Addition.

    PubMed

    Zhang, Dongdong; Bai, Fang; Wang, Yong; Wang, Jinguo; Wang, Wenquan

    2017-08-08

    The TiCp/Cu master alloy was prepared via thermal explosion reaction. Afterwards, the nano-sized TiCp/Cu master alloy was dispersed by electromagnetic stirring casting into the melting Cu-Cr-Zr alloys to fabricate the nano-sized TiCp-reinforced Cu-Cr-Zr composites. Results show that nano-sized TiCp can effectively refine the grain size of Cu-Cr-Zr alloys. The morphologies of grain in Cu-Cr-Zr composites changed from dendritic grain to equiaxed crystal because of the addition and dispersion of nano-sized TiCp. The grain size decreased from 82 to 28 μm with the nano-sized TiCp content. Compared with Cu-Cr-Zr alloys, the ultimate compressive strength (σUCS) and yield strength (σ0.2) of 4 wt% TiCp-reinforced Cu-Cr-Zr composites increased by 6.7% and 9.4%, respectively. The wear resistance of the nano-sized TiCp-reinforced Cu-Cr-Zr composites increased with the increasing nano-sized TiCp content. The wear loss of the nano-sized TiCp-reinforced Cu-Cr-Zr composites decreased with the increasing TiCp content under abrasive particles. The eletrical conductivity of Cu-Cr-Zr alloys, 2% and 4% nano-sized TiCp-reinforced Cu-Cr-Zr composites are 64.71% IACS, 56.77% IACS and 52.93% IACS, respectively.

  20. On the mechanisms of cation injection in conducting bridge memories: The case of HfO{sub 2} in contact with noble metal anodes (Au, Cu, Ag)

    SciTech Connect

    Saadi, M.; Gonon, P. Vallée, C.; Mannequin, C.; Bsiesy, A.; Grampeix, H.; Jalaguier, E.; Jomni, F.

    2016-03-21

    Resistance switching is studied in HfO{sub 2} as a function of the anode metal (Au, Cu, and Ag) in view of its application to resistive memories (resistive random access memories, RRAM). Current-voltage (I-V) and current-time (I-t) characteristics are presented. For Au anodes, resistance transition is controlled by oxygen vacancies (oxygen-based resistive random access memory, OxRRAM). For Ag anodes, resistance switching is governed by cation injection (Conducting Bridge random access memory, CBRAM). Cu anodes lead to an intermediate case. I-t experiments are shown to be a valuable tool to distinguish between OxRRAM and CBRAM behaviors. A model is proposed to explain the high-to-low resistance transition in CBRAMs. The model is based on the theory of low-temperature oxidation of metals (Cabrera-Mott theory). Upon electron injection, oxygen vacancies and oxygen ions are generated in the oxide. Oxygen ions are drifted to the anode, and an interfacial oxide is formed at the HfO{sub 2}/anode interface. If oxygen ion mobility is low in the interfacial oxide, a negative space charge builds-up at the HfO{sub 2}/oxide interface. This negative space charge is the source of a strong electric field across the interfacial oxide thickness, which pulls out cations from the anode (CBRAM case). Inversely, if oxygen ions migration through the interfacial oxide is important (or if the anode does not oxidize such as Au), bulk oxygen vacancies govern resistance transition (OxRRAM case).