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Sample records for cu alloy anode

  1. 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.

  2. 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.

  3. 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. PMID:26802262

  4. Rechargeable sodium alloy anode

    SciTech Connect

    Jow, T.R.

    1988-06-28

    A secondary battery is described comprising: (a) an anode which comprises an alloy of sodium and one or metals selected from the group consisting of tin, lead antimony, bismuth, selenium and tellerium, (b) an electrolyte comprising one or more organic solvents and one or more sodium salts dissolved therein forming dissolved sodium cations in solution; and (c) a cathode; the sodium cations from the electrolyte alloying with the one or more metals of the alloy in the anode during the charging of the battery and sodium in the alloy disoloving in the electrolyte during the discharging of the battery.

  5. Microstructure and anodic polarization behavior of experimental Ag-18Cu-15Pd-12Au alloy in aqueous sulfide solution.

    PubMed

    Endo, Kazuhiko; Ohno, Hiroki; Asakura, Shukuji

    2003-05-01

    The anodic corrosion behavior of an experimental Ag-15Pd-18Cu-12Au alloy in 0.1% Na(2)S solution in relation to its microstructure was investigated using potentiodynamic and potentiostatic polarization techniques with analyses of corrosion products by X-ray diffractometry, Auger electron spectroscopy, and X-ray photoelectron spectroscopy. The role of Pd in improvement of the corrosion resistance was also investigated. In the potential/current density curve, three distinct current peaks, at -520 mV (peak I), -425 mV (peak II) and -175 mV (peak III), were observed. The Ag-rich alpha(2) matrix with coarse Cu and Pd-rich lamellae was the most corrosion-susceptible region, and this region was preferentially corroded at peak I with the formation of granular deposits of Ag(2)S. A small amount of Ag-Cu mixed sulfide deposited on the Cu and Pd-rich coarse particles and dissolution of Ag as AgO(-) might have occurred in parallel with Ag(2)S formation at peak II. Enrichment of Pd on the alloy surface occurred at peak III due to preferential dissolution of Ag and Cu. A high level of corrosion resistance was attained with the formation of a thin Pd-rich sulfide film, which enhanced the passivity of the alloy in an alkaline sulfide solution. It was found that passivity is an important phenomenon not only for base metal alloys but also for noble metal alloys to maintain high levels of resistance to corrosion and tarnishing in sulfide environments. PMID:15348446

  6. 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.

  7. Core-Shell Sn-Ni-Cu-Alloy@Carbon Nanorods to Array as Three-Dimensional Anode by Nanoelectrodeposition for High-Performance Lithium Ion Batteries.

    PubMed

    Peng, Hao; Li, Rui; Hu, Jiangtao; Deng, Wenjun; Pan, Feng

    2016-05-18

    We report the synthesis of a novel three-dimensional anode based on the core-shell Sn-Ni-Cu-alloy@carbon nanorods which was fabricated by pulse nanoelectrodeposition. Li ion batteries equipped with the three-dimensional anode demonstrated almost 100% capacity retention over 400 cycles at 450 mA g(-1) and excellent rate performance even up to 9000 mA g(-1) for advanced Li-ion battery. Insight of the high performance can be attributed to three key factors, Li-Sn alloys for Li-ion storage, Ni-Cu matrix for the electronic conductive and nanorods structure, and the carbon shell for the electronic/Li-ion conductive and holding stable solid electrolyte interphase (SEI), because these shells always kept stable volumes after extension of initial charge-discharge cycles. PMID:27113033

  8. Copper-nickel superalloys as inert alloy anodes for aluminum electrolysis

    NASA Astrophysics Data System (ADS)

    Shi, Zhongning; Xu, Junli; Qiu, Zhuxian; Wang, Zhaowen; Gao, Bingliang

    2003-11-01

    The superalloys Cu-Ni-Al, Cu-Ni-Fe, and Cu-Ni-Cr were studied as anodes for aluminum electrolysis. The alloys were tested for corrosion in acidic electrolyte molten salt and for oxidation in both air and oxygen. The results showed that the Cu-Ni-Al anodes possess excellent resistance to oxidation and corrosion, and the oxidation rates of Cu-Ni-Fe and Cu-Ni-Al anodes were slower than those of pure copper or nickel. During electrolysis, the cell voltage of the Cu-Ni-Al anode was affected most by the concentration of alumina in cryolite molten salt. The Cu-Ni-Fe anode exhibited corrosion resistance in electrolyte molten salt. Comparatively, the Cu-Ni-Cr anode showed poor resistance to oxidation and corrosion. The testing found that further study is warranted on the use of Cu-Ni-Al and Cu-Ni-Fe as inert alloy anodes.

  9. 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.

  10. 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.

  11. Nano-scale Cu 6Sn 5 anodes

    NASA Astrophysics Data System (ADS)

    Wolfenstine, J.; Campos, S.; Foster, D.; Read, J.; Behl, W. K.

    Nano-scale (<100 nm) Cu 5Sn 6 powders were prepared by a chemical method that used a NaBH 4 solution to reduce the metal ions. A significant improvement in capacity retention was obtained in the nano-scale Cu 6Sn 5 alloy, compared to the alloy having micron-sized particles. The volumetric capacity of the nano-scale Cu 6Sn 5 alloy at 100 cycles was almost twice the theoretical capacity of graphite.

  12. 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.

  13. Catalytic activity of bimetallic nickel alloys for solid-oxide fuel cell anode reactions from density-functional theory

    NASA Astrophysics Data System (ADS)

    An, Wei; Gatewood, Daniel; Dunlap, Brett; Turner, C. Heath

    2011-05-01

    We present density-functional theory calculations of the chemisorption of atomic species O, S, C, H and reaction intermediates OH, SH, and CHn (n = 1, 2, and 3) on M/Ni alloy model catalysts (M = Bi, Mo, Fe, Co, and Cu). The activity of the Ni alloy catalysts for solid-oxide fuel cell (SOFC) anode oxidation reactions is predicted, based on a simple descriptor, i.e., the binding energy of oxygen. First, we find that the binding of undesirable intermediates, such as C and S, can be inhibited and the catalytic activity of planar Ni-based anodes can be tuned towards oxidation by selectively forming a bimetallic surface alloy. In particular, Cu/Ni, Fe/Ni, and Co/Ni anode catalysts are found to be most active towards anode oxidation. On the other hand, the Mo/Ni alloy surface is predicted to be the most effective catalyst in terms of inhibiting the deposition of C and S (while still preserving relatively high catalytic activity). The formation of a surface alloy, which has the alloy element enriched on the topmost surface, was found to be critical to the activity of the Ni alloy catalysts.

  14. 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.

  15. 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.

  16. Solid solution lithium alloy cermet anodes

    DOEpatents

    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.

  17. 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. PMID:17945243

  18. Beyond theoretical capacity in Cu-based integrated anode: Insight into the structural evolution of CuO

    NASA Astrophysics Data System (ADS)

    Chen, Kunfeng; Xue, Dongfeng; Komarneni, Sridhar

    2015-02-01

    An excellent CuO/Cu integrated anode with CuO nanoparticle-aggregated microsheets on Cu current collector showed higher capacity beyond the theoretical capacity of CuO. The reoxidation of Cu including converted Cu nanoparticles and Cu current collector into CuO guaranteed the highly reversible conversion reaction and high capacity. The combined current ex-situ methods of XRD, SEM and TEM were used to find the origin of the additional capacity by examining the structural evolution and phase transformation of CuO/Cu integrated anode during electrochemical cycling. After 110 cycles, the discharge capacity of CuO/Cu integrated anode retained a large value of 706 mAh g-1, which is beyond the theoretical capacity of CuO materials (674 mAh g-1). The specific electrode configuration and the release of Cu from integrated Cu current collector made these CuO/Cu electrodes maintain high capacity and cycling stability. The present research demonstrates a protocol for the design of high-performance anode structure: in situ chemical and electrochemical activating integrated electrode system.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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. PMID:21919435

  4. 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.

  5. 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. PMID:21104193

  6. Sb/Cu2Sb-TiC-C Composite Anode for High-Performance Sodium-Ion Batteries.

    PubMed

    Chae, Seung Chul; Hur, Jaehyun; Kim, Il Tae

    2016-02-01

    A novel nanostructure consisting of copper-antimony alloy (Cu2Sb) particles dispersed in a conductive hybrid matrix of titanium carbide (TiC) and carbon (C) has been developed by high energy mechanical milling (HEMM) and explored for use as an anode in sodium-ion batteries. By controlling the molar ratio of Cu and Sb, Cu2Sb and Sb are able to co-exist in a matrix. The (Sb)/Cu2Sb-TiC-C samples have been characterized by X-ray diffraction and by high-resolution transmission electron microscopy. Specifically, the Cu2Sb-TiC-C composite anode demonstrates better cyclic performance as well as better rate-capability compared to Sb/Cu2Sb-TiC-C. Addition- ally, the introduction of the fluoroethylene carbonate (FEC) additive into the electrolyte leads to improved electrochemical performance even at high-rate current densities, when compared to the electrodes without the FEC additive, owing to the formation of a stable and thin SEI layer. PMID:27433694

  7. 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.

  8. 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.

  9. Effect of Cu content on the defect evolution in Fe-Cu alloys investigated by PALS

    NASA Astrophysics Data System (ADS)

    Cao, X. Z.; Lai, X.; Cheng, G. D.; Jin, S. X.; Zhang, X.; Zhang, P.; Wang, B. Y.

    2016-01-01

    The effect of Cu content on the evolution of defects in Fe-x%Cu alloys (x= 0.15, 0.3, and 0.6) were investigated using Positron Annihilation Lifetime Spectroscopy (PALS). The vacancy-type and Cu-vacancy complexes defects were respectively produced by quenching from 1173 K and cold-rolled deformation followed by isochronal annealing. The PALS results with isochronal annealing showed that the temperature of defects recovery increased in deformed Fe-Cu alloys with Cu content. The increment of Cu content also restrained the migration of vacancies in as-quenched Fe-Cu alloys.

  10. 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. PMID:15744719

  11. On reversion phenomena in Cu-Zr-Cr alloys

    NASA Technical Reports Server (NTRS)

    Suzuki, H.; Kitano, H.; Kanno, M.

    1985-01-01

    Reversion phenomena in aged Cu-0.12% Zr-0.28% Cr alloy were investigated by means of resistivity measurement and transmission electron microscopy and compared with those of Cu-0.30% Zr and Cu-0.26% Cr alloys. Specimens in the form of a 0.5 mm sheet were solution-treated at 950 F for 1 hr water-quenched, aged, and finally reversed. The reversion phenomena were confirmed to exist in Cu-Zr and Cu-Zr-Cr alloys as well as Cu-Cr alloys, at aging temperatures of 300 to 500 F. The critical aging temperature for the reversion was not observed in all the alloys. Split aging increased the amount of reversion, particularly in Cu-Zr and Cu-Zr-Cr alloys, compared with that by conventional aging. The amount of reversion in Cu-Zr-Cr alloy was greatly affected by the resolution of Cr precipitate formed by preaging. Structural changes in Cu-Zr-Cr alloy due to the reversion were hardly observed by transmission electron microscopy.

  12. Effect of alloying elements on electrochemical properties of magnesium-based sacrificial anodes

    SciTech Connect

    Kim, J.G.; Koo, S.J.

    2000-04-01

    Effects of alloying elements on electrochemical properties of magnesium-based sacrificial anodes were evaluated. Potentiodynamic, galvanostatic, scanning electron microscopy (SEM), and x-ray diffraction (XRD) analyses were used to investigate the corrosion rate, efficiency, and surface characteristics of anodes. Polarization data indicated that alloying with manganese, aluminum, and zinc reduced the corrosion rates of magnesium anodes. All anodes did not undergo passivation but demonstrated only active behavior. Corrosion morphology was changed from localized to uniform attach by the alloying. Addition of manganese to magnesium anodes yielded increased driving potential and efficiency. The efficiency of Mg-Al anodes was improved up to {approximately}6% Al addition. The addition of zinc increased the efficiency of Mg-Al-Zn anodes compared to the efficiency of Mg-Al anodes, but the reversal of this behavior happened as the zinc content exceeded {approximately}3%. The increase in the efficiency of Mg-Al and Mg-Al-Zn anodes was accompanied by a decrease in the driving potential. The decrease of driving potential might have resulted form a somewhat resistive film on the surface, which hindered the transport of ions. The increased corrosion resistance generally improved anode efficiency.

  13. 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. PMID:23436766

  14. Evaluation of Ti-Cr-Cu alloys for dental applications

    NASA Astrophysics Data System (ADS)

    Koike, Marie; Okabe, Toru; Itoh, Masayuki; Okuno, Osamu; Kimura, Kohei; Takeda, Osamu; Okabe, Toru H.

    2005-12-01

    This study examined the characteristics of as-cast Ti-Cr(7 19%)-Cu(3 7%) (all percentages in this article are mass%) alloys to evaluate their suitability for dental applications; studies on the alloy structures and mechanical properties, grindability, and corrosion behavior were included in the investigation. The alloys were centrifugally cast and bench-cooled in investment molds. The x-ray diffractometry of the as-cast alloys bench-cooled in the molds indicated the following phases: α+β+ω in the 7% Cr and 7% Cr+3% Cu; β+ω in the 13%Cr; and β in the 13%Cr+3% Cu through the 19%Cr+3% Cu alloys. The strengths of the binary β Ti-Cr and ternary β Ti-Cr-Cu alloys with 13 and 19% Cr were approximately two times higher than those of CP Ti. The alloy ductility was dependent on the chemical composition and thus, the microstructure. The 7% Cr alloys were extremely brittle and hard due to the ω phase, but the ductility was restored in the 13 and 19% Cr alloys. The hardness (HV) of the cast 13 and 19% Cr alloys was approximately 300 350 compared with a value of 200 for CP Ti. The grindability of the cast alloys was examined using a rotating SiC wheel at speeds (circumferential) of 500 and 1250 m/min. At the higher speed, the grindability of the 13 and 19% Cr alloys increased with the Cu content. The grindability of the 13% Cr alloy with 7% Cu was similar to that of CP Ti. Evaluation of the corrosion behavior in an artificial saliva revealed that the alloys are like many other titanium alloys within the normal intraoral oxidation potential. The wear resistance testing of these alloys also showed favorable results.

  15. Dendritic solidification of undercooled Cu-20%Pb hypomonotectic alloy

    SciTech Connect

    Dong, C.; Wei, B.

    1996-05-15

    The Cu-Pb monotectic system is the basis of an important category of wear-resistant materials especially bearing alloys. Its industrially interesting composition ranges from 10 to 50%Pb. In order to produce aligned composites or homogeneous dispersions, extensive research has been performed to investigate the solidification mechanism of Cu-Pb monotectic alloys under directional solidification or microgravity conditions. The preliminary nature of the current space experiments on Cu-Pb monotectic solidification excludes the possibility to draw any really definite conclusions about the influences of microgravity. In contrast, so far still little has been known about the undercooling behavior and rapid solidification kinetics of Cu-Pb monotectic alloys. The objective of the present work is to undercool bulk samples of Cu-Pb alloys to a significant extent and investigate their subsequent rapid solidification process. and this paper reports the related results obtained for Cu-20%Pb hypomonotectic alloy.

  16. Surface integrity after pickling and anodization of Ti-6Al-4V titanium alloy

    NASA Astrophysics Data System (ADS)

    Vermesse, Eric; Mabru, Catherine; Arurault, Laurent

    2013-11-01

    The surface integrity of Ti-6Al-4V titanium alloy was studied at different stages of surface treatments, especially pickling and compact anodization, through surface characteristics potentially worsening fatigue resistance.

  17. 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.

  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. 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.

  20. 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.

  1. Electrochemical properties of rapidly solidified Si-Ti-Ni(-Cu) base anode for Li-ion rechargeable batteries

    NASA Astrophysics Data System (ADS)

    Kwon, Hye Jin; Sohn, Keun Yong; Park, Won-Wook

    2013-11-01

    In this study, rapidly solidified Si-Ti-Ni-Cu alloys have been investigated as high capacity anodes for Li-ion secondary batteries. To obtain nano-sized Si particles dispersed in the inactive matrix, the alloy ribbons were fabricated using the melt spinning process. The thin ribbons were pulverized using ball-milling to make a fine powder of ˜ 4 µm average size. Coin-cell assembly was carried out under an argon gas in a glove box, in which pure lithium was used as a counter-electrode. The cells were cycled using the galvanostatic method in the potential range of 0.01 V and 1.5 V vs. Li/Li+. The microstructure and morphology were examined using an x-ray diffractometer, Field-Emission Scanning Electron Microscopy and High Resolution Transmission Electron Microscopy. Among the anode alloys, the Si70Ti15Ni15 electrodes had the highest discharge capacity (974.1 mAh/g) after the 50th cycle, and the Si60Ti16Ni16Cu8 electrode showed the best coulombic efficiency of ˜95.9% in cyclic behavior. It was revealed that the Si7Ni4Ti4 crystal phase coexisting with an amorphous phase, could more efficiently act as a buffer layer than the fully crystallized Si7Ni4Ti4 phase. Consequently, the electrochemical properties of the anode materials pronouncedly improved when the nano-sized primary Si particle was dispersed in the inactive Si7Ni4Ti4-based matrix mixed with an amorphous structure.

  2. Effect of intermetallic phases on the anodic oxidation and corrosion of 5A06 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Li, Song-mei; Li, Ying-dong; Zhang, You; Liu, Jian-hua; Yu, Mei

    2015-02-01

    Intermetallic phases were found to influence the anodic oxidation and corrosion behavior of 5A06 aluminum alloy. Scattered intermetallic particles were examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) after pretreatment. The anodic film was investigated by transmission electron microscopy (TEM), and its corrosion resistance was analyzed by electrochemical impedance spectroscopy (EIS) and Tafel polarization in NaCl solution. The results show that the size of Al-Fe-Mg-Mn particles gradually decreases with the iron content. During anodizing, these intermetallic particles are gradually dissolved, leading to the complex porosity in the anodic film beneath the particles. After anodizing, the residual particles are mainly silicon-containing phases, which are embedded in the anodic film. Electrochemical measurements indicate that the porous anodic film layer is easily penetrated, and the barrier plays a dominant role in the overall protection. Meanwhile, self-healing behavior is observed during the long immersion time.

  3. 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.

  4. Highly active nanoporous Pt-based alloy as anode and cathode catalyst for direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Chen, Xiaoting; Jiang, Yingying; Sun, Junzhe; Jin, Chuanhong; Zhang, Zhonghua

    2014-12-01

    In this paper, we explore nanoporous PtPdAlCu (np-PtPdAlCu) quaternary alloy through ball-milling with the subsequent two-step dealloying strategy. The microstructure and catalytic performance of the np-PtPdAlCu catalyst have been characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electrochemical measurements. The np-PtPdAlCu catalyst exhibits an open bi-continuous interpenetrating ligament/channel structure with a length scale of 2.3 ± 0.5 nm. The np-PtPdAlCu catalyst shows 2 and 3.5 times enhancement in the mass activity and area specific activity towards methanol oxidation at anode respectively, compared to the Johnson Matthey (JM) Pt/C (40 wt.%) catalyst. Moreover, the CO stripping peak of np-PtPdAlCu is 0.49 V (vs. SCE), indicating a 180 mV negative shift in comparison with the Pt/C catalyst (0.67 V vs. SCE). In addition, the np-PtPdAlCu catalyst also shows an enhanced oxygen reduction reaction (ORR) activity at cathode compared to Pt/C. The present study provides a facile and effective route to design high-performance catalysts for direct methanol fuel cells (DMFCs).

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Mechanical Properties of Cu-Cr-Nb Alloys

    NASA Technical Reports Server (NTRS)

    Ellis, David L.

    1997-01-01

    The chemical compositions of the alloys are listed. The alloying levels were near the values for stochiometric Cr2Nb. A slight excess of Cr was chosen for increased hydrogen embrittlement resistance. The microstructures of all Cu-Cr-Nb alloys were very similar. Two typical transmission electron microscope (TEM) micrographs are presented. The images show the presence of large mount of Cr2Nb precipitates in a nearly pure Cu matrix. The interactions between dislocations and precipitates are currently under investigations, but as the images demonstrates, the extremely fine (less then 15 nm) Cr2Nb are the primary strengtheners for the alloy.

  12. High areal capacity, micrometer-scale amorphous Si film anode based on nanostructured Cu foil for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Si, Wenping; Sun, Xiaolei; Liu, Xianghong; Xi, Lixia; Jia, Yandong; Yan, Chenglin; Schmidt, Oliver G.

    2014-12-01

    We report a feasible design to fabricate micrometer-scale Si films deposited on nanostructured Cu foil as high areal capacity anodes for Li-ion batteries with excellent cycling performance. Nanostructured copper oxides are prepared by anodic oxidation of Cu foil in alkaline solution. The resultant copper oxide nanofibers function as matrix for thick Si films (1-2 μm) loading. Metallic Cu nanofibers are obtained by in-situ electrochemical reduction at low potentials, which work as electrical highways for fast electron transport and a reliable mechanical matrix to accommodate volume changes during lithium-silicon alloy/dealloy processes. The engineered thick Si film anode exhibit both high areal capacity (0.48 mAh cm-2 for 1 μm Si film and 0.6 mAh cm-2 for 2 μm Si film after 200 cycles at 0.225 mA cm-2) and excellent rate capability (0.52 mAh cm-2 at 1.05 mA cm-2 for 2 μm Si film). The 2 μm silicon film electrode is able to recover to the initial value of 1 mAh cm-2 when the current rate is set back to 0.15 mA cm-2 even after cycling at high current rates. The reported concept can be a general method for high-loading-film electrodes, which is industrial scalable and compatible with current battery manufacturing processes.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Cracking associated with micrometeoroid impact craters in anodized aluminum alloy clamps on LDEF

    NASA Technical Reports Server (NTRS)

    Murr, Lawrence E.; Niou, Chorng S.; Quinones, Stella; Murr, Kyle S.

    1992-01-01

    The Long Duration Exposure Facility (LDEF) is a reusable hollow-cylindrical satellite sustaining a total of 57 different experiments. The 130 sq m of spacecraft surface area included anodized 6061-T6 Al alloy bay frames and clamps for holding experiment trays in the bay areas. Attention is presently given to the micrometeoroid impact crater features observed on two tray clamps recovered from the LDEF leading-edge locations. It is found that even very subtle surface modifications in structural alloy anodizing can influence micrometeoroid impact crater cracking, notable radial cracking due to the ejecta-rim of the impact craters.

  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. Production and processing of Cu-Cr-Nb alloys

    NASA Technical Reports Server (NTRS)

    Ellis, David L.; Michal, Gary M.; Orth, Norman W.

    1990-01-01

    A new Cu-based alloy possessing high strength, high conductivity, and good stability at elevated temperatures was recently produced. This paper details the melting of the master alloys, production of rapidly solidified ribbon, and processing of the ribbon to sheet by hot pressing and hot rolling.

  2. 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. PMID:21757793

  3. 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.

  4. A nanoglass alloying immiscible Fe and Cu at the nanoscale.

    PubMed

    Chen, Na; Wang, Di; Feng, Tao; Kruk, Robert; Yao, Ke-Fu; Louzguine-Luzgin, Dmitri V; Hahn, Horst; Gleiter, Herbert

    2015-04-21

    Synthesized from ultrafine particles with a bottom-up approach, nanoglasses are of particular importance in pursuing unique properties. Here, we design a metallic nanoglass alloy from two components of ∼Cu64Sc36 and ∼Fe90Sc10 nanoglasses. With nanoalloying mutually immiscible Fe and Cu, the properties of the nanoglass alloys can be tuned by varying the proportions of the ∼Fe90Sc10 component. This offers opportunity to create novel metallic glass nanocomposites and sheds light on building a structure-property correlation for the nanoglass alloys. PMID:25792519

  5. 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.

  6. High capacity group-15 alloy anodes for Na-ion batteries: Electrochemical and mechanical insights

    NASA Astrophysics Data System (ADS)

    Mortazavi, Majid; Ye, Qiongjie; Birbilis, Nick; Medhekar, Nikhil V.

    2015-07-01

    Group-15 elements phosphorus, arsenic, antimony and bismuth offer the prospect of serving as functional alloying elements for developing high-capacity alloy anodes for sodium-ion batteries (NIBs). Here we obtain concentration-dependent electrochemical properties of sodium (Na) alloys with group-15 elements using first principles calculations. Since Na intercalation in these alloys is accompanied by a substantial volume expansion that can lead to mechanical failure and loss of capacity, we have also obtained a full set of concentration-dependent elastic properties for a single crystal as well as a polycrystalline microstructure. We find that sodiation of these alloys results in their significant elastic softening by as large as 60%. In contrast to the group-14 alloys that are also being explored as anodes of NIBs, the elastic softening in group-15 alloys varies in a non-monotonic manner with Na concentration, and more importantly, the maximum degradation of elastic properties does not necessarily occur at full sodiation. Our results provide crucial insights into the electrochemical and mechanical response of these alloys to Na intercalation, thus contributing to the design of failure-resistant architectures of high capacity NIBs.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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. PMID:27200436

  12. 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.

  13. 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

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

    PubMed

    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

  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. 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. PMID:23755692

  17. 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.

  18. In vivo and in vitro response to electrochemically anodized Ti-6Al-4V alloy.

    PubMed

    Lee, Yu Mi; Lee, Eun Jung; Yee, Sung Tae; Kim, Byung Il; Choe, Eun Sang; Cho, Hyun Wook

    2008-05-01

    Tissues' reactions to metals depend on a variety of properties of the metal, most notably surface structure. Anodizing has been shown to alter the surface properties of metal, thus eliciting a change in the biocompatibility of the metal. In order to evaluate the biocompatibility of unoxidized titanium alloy (Ti-6Al-4V) and anodized titanium alloy samples, the samples were implanted in murine abdominal subcutaneous tissues, and maintained for 2 and 4 weeks. The reaction of the abdominal subcutaneous connective tissues to the samples was then assessed. Fibrous connective tissue capsules were observed around the vicinity of the sample, and these capsules were shown to harbor fibroblasts, fibrocytes, and other cells, including neutrophils, macrophages, and giant multinucleated cells. The average thickness of the fibrous capsules observed around the anodized alloy samples was less than that of the capsules seen around samples of the unoxidized titanium alloy. Blood was obtained from the tails of the experimental mice, and blood cell analyses were conducted in order to assess the levels of leukocytes, red blood cells, and thrombocytes. The blood analysis results of the unoxidized control group and treatment group were all within normal ranges. In addition, the biocompatibility of the titanium alloy samples was evaluated using cell culture techniques. The numbers of MG-63 cells cultured on oxidized samples tended to be greater than those in the controls; however, these increases were not statistically significant. The alkaline phosphatase activity of the sample oxidized at 310 V evidenced significantly higher activity than was observed in the control group. These results indicate that the anodized Ti-6Al-4V alloy will be of considerable utility in biomedical applications. PMID:17914611

  19. Wetting and Interfacial Chemistry of SnZnCu Alloys with Cu and Al Substrates

    NASA Astrophysics Data System (ADS)

    Fima, Przemysław; Pstruś, Janusz; Gancarz, Tomasz

    2014-05-01

    Wetting of Cu and Al pads by Sn-Zn eutectic-based alloys with 0.5, 1, and 1.5 wt.% of Cu was studied at 250 °C, in the presence of ALU33® flux, with wetting times of 15, 30, 60, and 180 s, respectively. With increasing wetting time the wetting angle decreases only slightly and the angles on Cu pads are higher than those on Al pads. Selected, solidified solder-pad couples were cross-sectioned and subjected to SEM-EDS study of the interfacial microstructure. The results revealed that the microstructure of the SnZnCu/Cu interface is much different from SnZnCu/Al interface. In the first case continuous interlayers are observed while in the latter case there is no interlayer but the alloy dissolves the substrate along grain boundaries.

  20. 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.

  1. Effect of temperature on the anodizing process of aluminum alloy AA 5052

    NASA Astrophysics Data System (ADS)

    Theohari, S.; Kontogeorgou, Ch.

    2013-11-01

    The effect of temperature (10-40 °C) during the anodizing process of AA 5052 for 40 min in 175 g/L sulfuric acid solution at constant voltage (15 V) was studied in comparison with pure aluminum. The incorporated magnesium species in the barrier layer result in the further increase of the minimum current density passed during anodizing, as the temperature increases, by about 42% up to 30 °C and then by 12% up to 40 °C. Then during the anodizing process for 40 min a blocking effect on oxide film growth was gradually observed as the temperature increased until 30 °C. The results of EDAX analysis on thick films reveal that the mean amount of the magnesium species inside the film is about 50-70% less than that in the bulk alloy, while it is higher at certain locations adjacent to the film surface at 30 °C. The increase of anodizing temperature does not influence the porosity of thin films (formed for short times) on pure aluminum, while it reduces it on the alloy. At 40 °C the above mentioned blocking effects disappear. It means that the presence of magnesium species causes an impediment to the effect of temperature on iss, on the film thickness and on the porosity of thin films, only under conditions where film growth takes place without significant loss of the anodizing charge to side reactions.

  2. Band gap structure modification of amorphous anodic Al oxide film by Ti-alloying

    SciTech Connect

    Canulescu, S. Schou, J.; Rechendorff, K.; Pleth Nielsen, L.; Borca, C. N.; Jones, N. C.; Hoffmann, S. V.; Bordo, K.; Ambat, R.

    2014-03-24

    The band structure of pure and Ti-alloyed anodic aluminum oxide has been examined as a function of Ti concentration varying from 2 to 20 at. %. The band gap energy of Ti-alloyed anodic Al oxide decreases with increasing Ti concentration. X-ray absorption spectroscopy reveals that Ti atoms are not located in a TiO{sub 2} unit in the oxide layer, but rather in a mixed Ti-Al oxide layer. The optical band gap energy of the anodic oxide layers was determined by vacuum ultraviolet spectroscopy in the energy range from 4.1 to 9.2 eV (300–135 nm). The results indicate that amorphous anodic Al{sub 2}O{sub 3} has a direct band gap of 7.3 eV, which is about ∼1.4 eV lower than its crystalline counterpart (single-crystal Al{sub 2}O{sub 3}). Upon Ti-alloying, extra bands appear within the band gap of amorphous Al{sub 2}O{sub 3}, mainly caused by Ti 3d orbitals localized at the Ti site.

  3. Dendrite coherency of Al-Si-Cu alloys

    NASA Astrophysics Data System (ADS)

    Veldman, Natalia L. M.; Dahle, Arne K.; Stjohn, David H.; Arnberg, Lars

    2001-01-01

    The dendrite coherency point of Al-Si-Cu alloys was determined by thermal analysis and rheological measurement methods by performing parallel measurements at two cooling rates for aluminum alloys across a wide range of silicon and copper contents. Contrary to previous findings, the two methods yield significantly different values for the fraction solid at the dendrite coherency point. This disparity is greatest for alloys of low solute concentration. The results from this study also contradict previously reported trends in the effect of cooling rate on the dendritic coherency point. Consideration of the results shows that thermal analysis is not a valid technique for the measurement of coherency. Analysis of the results from rheological testing indicates that silicon concentration has a dominant effect on grain size and dendritic morphology, independent of cooling rate and copper content, and thus is the factor that determines the fraction solid at dendrite coherency for Al-Si-Cu alloys.

  4. Direct electrodeposition of Cu2Sb for lithium-ion battery anodes.

    PubMed

    Mosby, James M; Prieto, Amy L

    2008-08-13

    We describe the direct single potential electrodeposition of crystalline Cu2Sb, a promising anode material for lithium-ion batteries, from aqueous solutions at room temperature. The use of citric acid as a complexing agent increases the solubility of antimony salts and shifts the reduction potentials of copper and antimony toward each other, enabling the direct deposition of the intermetallic compound at pH 6. Electrodeposition of Cu2Sb directly onto conducting substrates represents a facile synthetic method for the synthesis of high quality samples with excellent electrical contact to a substrate, which is critical for further battery testing. PMID:18627144

  5. Fe-30Ni-5NiO alloy as inert anode for low-temperature aluminum electrolysis

    NASA Astrophysics Data System (ADS)

    Zhu, Yuping; He, Yedong; Wang, Deren

    2011-05-01

    Fe-30Ni-5NiO alloy anodes were prepared by a spark plasma sintering process for aluminum electrolysis. NiO nano-particles with the size of ˜20 nm were dispersed in the anodes. The oxidation behaviors of the anodes were investigated at 800°C and 850°C, respectively. The electrolysis corrosion behaviors were tested in a cryolite-alumina electrolyte at a low temperature of 800°C with anodic current densities of ˜0.5 A/cm2. The results indicated that the oxidation kinetic of the anodes followed a parabolic law. A continuous Fe2O3 film selectively formed on the surface of the anode during the electrolysis process. A semi-continuous Al2O3 layer was observed at oxide film/alloy interface, probably caused by an in-situ chemical dissolution process.

  6. Synthesis of porous Cu from Al-Cu-Co decagonal quasicrystalline alloys

    NASA Astrophysics Data System (ADS)

    Kalai Vani, V.; Kwon, O. J.; Hong, S. M.; Fleury, E.

    2011-07-01

    The formation of a porous Cu structure from cast Al-Cu-Co decagonal quasicrystalline alloys has been studied using a selective corrosion technique. Two alkaline solutions were selected based on the electrochemical properties of the constituent elements. Selective corrosion of Al and Co was achieved by chemical immersion of the cast Al-Cu-Co alloy in both 5 M NaOH and 0.5 M Na2CO3 solutions; values for BET surface-to-weight ratio of up to 30 m2/g could be reached. Microstructural analyses indicated that the architecture of the resulting porous structures was composed of a needle-type phase, remaining from the decagonal phase, in addition to Cu and Cu-Co phases.

  7. 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.

  8. Dissolution of amorphous Ti-Zr-Si alloy during anodic oxidation with formation of barrier films

    SciTech Connect

    Isaev, N.I.; Yakovlev, V.B.; Iovdal'skii, A.A.; Gorshkov, T.P.

    1988-07-01

    Radiometric analysis of a solution has been used to study kinetic mechanisms for dissolution of amorphous alloy components in acid aqueous solutions with anodic oxidation in different regimes. In a galvanostatic regime for alloy and crystalline Ti, Zr, and Ta two sections are detected: an initial section of accelerated dissolution and a steady section. An increase in dissolution of zirconium from the alloy has been revealed compared with pure crystalline zirconium. Potentiostatic oxidation is accompanied by a slowdown in dissolution similar to a change in current. Current yield has been analyzed for dissolution of the main elements and nonrectifying impurities of the alloy (for example copper). Gamma spectroscopy using the gamma radiation from neutron-activated isotopes of the components and impurities was performed.

  9. Magnetic properties of pulse-reverse electrodeposited nanocrystalline NiFe/Cu composite wires in relation to the anodic current

    NASA Astrophysics Data System (ADS)

    Seet, H. L.; Li, X. P.; Lee, K. S.; Chia, H. Y.; Zheng, H. M.; Ng, W. C.

    2007-12-01

    Ni80Fe20/Cu composite wires were developed using the pulse-reverse electrodeposition technique with the cathodic (positive) current Ic fixed at 1 mA and the anodic (negative) current IA varied from 10 to 90% of Ic. The relationship between the magnetic properties of pulse reverse electrodeposited nanocrystalline NiFe/Cu composite wires and the anodic current was investigated. The results showed that the smaller the magnitude of the anodic current, the smaller was the average nanocrystalline grain size of the deposited material and the better was the uniformity of the surface, and consequently, the better the magnetic properties.

  10. 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.

  11. Precipitations in a dental Ag-Pd-Cu-Au alloy.

    PubMed

    Herø, H; Jørgensen, R; Sørbrøden, E; Suoninen, E

    1982-05-01

    The structure of a dental Ag-PD-Cu-Au alloy has been studied after centrifugal casting and various heat treatments. By transmission electron microscopy, a high density of small fct particles, assumed to be PdCu, was observed, but, in addition, finely-spaced rods of approximately equal to 0.05 micrometer (500 A) diameter with an fcc structure precipitated on the [100] planes of the matrix were found. On the basis of their structure and the pertaining lattice parameter, these rods are assumed to be Cu-rich. They could also be observed by scanning electron microscopy, but not at annealing temperatures lower than 425 degrees C. PMID:6953095

  12. Investigation of carbon supported Pd-Cu nanoparticles as anode catalysts for direct borohydride fuel cell

    NASA Astrophysics Data System (ADS)

    Behmenyar, Gamze; Akın, Ayşe Nilgün

    2014-03-01

    Carbon supported Pd and bimetallic Pd-Cu nanoparticles with different compositions are prepared by a modified polyol method and used as anode catalysts for direct borohydride fuel cell (DBFC). The physical and electrochemical properties of the as-prepared electrocatalysts are investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), ICP-AES, cyclic voltammetry (CV), chronoamperometry (CA), and fuel cell experiments. The results show that the carbon supported Pd-Cu bimetallic catalysts have much higher catalytic activity for the direct oxidation of BH4- than the carbon supported pure nanosized Pd catalyst, especially the Pd50Cu50/C catalyst presents the highest catalytic activity among all as-prepared catalysts, and the DBFC using Pd50Cu50/C as anode catalyst and Pt/C as cathode catalyst gives the best performance, and the maximum power density is 98 mW cm-2 at a current density of 223 mA cm-2 at 60 °C.

  13. 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. PMID:24411393

  14. A potentiostatic study of the corrosion behavior of anodized and nonanodized aluminum alloy.

    PubMed

    White, K C; Svare, C W; Taylor, T D

    1985-06-01

    The clinical implication of this study is that some improvement in the corrosion resistance of denture bases made with aluminum alloy D-214 may be obtained by anodization. However, since this study does not exactly duplicate an oral environment or take into consideration the variation in oral environments, it cannot be assumed that the additional corrosion resistance would be discernible in a particular patient. PMID:3859652

  15. 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

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    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.

  17. Thermal fatigue damage of Cu-Cr-Zr alloys

    NASA Astrophysics Data System (ADS)

    Chatterjee, Arya; Mitra, R.; Chakraborty, A. K.; Rotti, C.; Ray, K. K.

    2013-11-01

    The primary aim of this investigation is to examine thermal fatigue damage (TFD) in Cu-Cr-Zr alloys used in High Heat Flux components of Tokamak and its subsystems. Thermal fatigue experiments have been carried out between 290 °C and 30 °C, which is analogous to the condition of service application on two Cu-Cr-Zr alloys having different aging treatments. The extents of TFD have been examined by standard measurements of electrical conductivity, lattice strain, residual stress and dynamic elastic modulus, supplemented by characterizations of microstructure and determination of hardness and tensile properties. The results lead to infer that the relative amounts of damage are different in the two alloys which are further dependent on their aging conditions; the reasons for the observed difference have been explained. The operative mechanisms of TFD are revealed to be as formation and subsequent coalescence of microvoids, and/or initiation and growth of microcracks.

  18. Thermophysical and electrical properties of equiatomic CuZr alloy

    NASA Astrophysics Data System (ADS)

    Bykov, V. A.; Kulikova, T. V.; Yagodin, D. A.; Filippov, V. V.; Shunyaev, K. Yu.

    2015-11-01

    Differential scanning calorimetry, laser flash technique, dilatometry, and a method based on a rotating magnetic field were used to study for the first time thermophysical and electrical properties of the Cu50Zr50 equiatomic alloy in the quenched state and after annealing at temperatures ranging from room temperature to 1100 K. The thermal conductivity coefficient was calculated using the results of heat capacity, thermal diffusivity, and density measurements. The sequence and temperatures of structural transformations in the quenched Cu50Zr50 alloy were determined during alloy heating. The electron component of thermal conductivity was estimated using the Wiedemann-Franz-Lorentz law. This law was found to be satisfied well for the quenched sample at temperatures above 600 K and for the annealed sample at temperatures beginning from 900 K. As the temperature decreases, the lattice contribution increases. This fact indicates the marked effect of strong chemical interaction between copper and zirconium on the heat- and electrotransport processes.

  19. Performance Enhancement of Silicon Alloy-Based Anodes Using Thermally Treated Poly(amide imide) as a Polymer Binder for High Performance Lithium-Ion Batteries.

    PubMed

    Yang, Hwi Soo; Kim, Sang-Hyung; Kannan, Aravindaraj G; Kim, Seon Kyung; Park, Cheolho; Kim, Dong-Won

    2016-04-01

    The development of silicon-based anodes with high capacity and good cycling stability for next-generation lithium-ion batteries is a very challenging task due to the large volume changes in the electrodes during repeated cycling, which results in capacity fading. In this work, we synthesized silicon alloy as an active anode material, which was composed of silicon nanoparticles embedded in Cu-Al-Fe matrix phases. Poly(amide imide)s, (PAI)s, with different thermal treatments were used as polymer binders in the silicon alloy-based electrodes. A systematic study demonstrated that the thermal treatment of the silicon alloy electrodes at high temperature made the electrodes mechanically strong and remarkably enhanced the cycling stability compared to electrodes without thermal treatment. The silicon alloy electrode thermally treated at 400 °C initially delivered a discharge capacity of 1084 mAh g(-1) with good capacity retention and high Coulombic efficiency. This superior cycling performance was attributed to the strong adhesion of the PAI binder resulting from enhanced secondary interactions, which maintained good electrical contacts between the active materials, electronic conductors, and current collector during cycling. These findings are supported by results from X-ray photoelectron spectroscopy, scanning electron microscopy, and a surface and interfacial cutting analysis system. PMID:27008091

  20. Morphology-dependent performance of CuO anodes via facile and controllable synthesis for lithium-ion batteries.

    PubMed

    Wang, Chen; Li, Qing; Wang, Fangfang; Xia, Guofeng; Liu, Ruiqing; Li, Deyu; Li, Ning; Spendelow, Jacob S; Wu, Gang

    2014-01-22

    Nanostructured CuO anode materials with controllable morphologies have been successfully synthesized via a facile and environmentally friendly approach in the absence of any toxic surfactants or templates. In particular, leaf-like CuO, oatmeal-like CuO, and hollow-spherical CuO were obtained by changing the ligand agents. The structures and electrochemical performance of these as-prepared CuO were fully characterized by various techniques, and the properties were found to be strongly dependent on morphology. As anode materials for lithium-ion batteries, the leaf-like CuO and oatmeal-like CuO electrodes exhibit relatively high reversible capacities, whereas hollow-spherical CuO shows enhanced reversible capacity after initial degradation. Furthermore, an excellent high rate capability was obtained for the leaf-like CuO and hollow-spherical CuO electrodes. These results may provide valuable insights for the development of nanostructured anodes for next-generation high-performance lithium-ion batteries. PMID:24377276

  1. 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.

  2. 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.

  3. 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. PMID:26412211

  4. 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.

  5. 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. PMID:24433910

  6. 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

  7. 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.

  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. 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. PMID:27477221

  10. Mechanical Properties of a Partially Solidified Cu-Zn Alloy

    NASA Astrophysics Data System (ADS)

    Kasuya, Naoki; Nakazawa, Tomoaki; Matsushita, Akira; Okane, Toshimitsu; Yoshida, Makoto

    2016-04-01

    For predicting solidification cracking by thermal stress analysis, the mechanical properties in the partially solidified state based on the experimental results are the best hope. However, the Young's modulus has never been investigated for copper alloys. In this study, stress-strain curves of a Cu-Zn alloy in the partially solidified state for various solid fractions were obtained using a specially developed horizontal tensile test device. Furthermore, by removing the load during the tensile test, the spring-back (elastic behavior) was observed and the Young's modulus was obtained.

  11. 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).

  12. Nanoporous alumina formed by self-organized two-step anodization of Ni3Al intermetallic alloy in citric acid

    NASA Astrophysics Data System (ADS)

    Stępniowski, Wojciech J.; Cieślak, Grzegorz; Norek, Małgorzata; Karczewski, Krzysztof; Michalska-Domańska, Marta; Zasada, Dariusz; Polkowski, Wojciech; Jóźwik, Paweł; Bojar, Zbigniew

    2013-01-01

    Formation of the nanoporous alumina on the surface of Ni3Al intermetallic alloy has been studied in details and compared with anodization of aluminum. Successful self-organized anodization of this alloy was performed in 0.3 M citric acid at voltages ranging from 2.0 to 12.0 V using a typical two-electrode cell. Current density records revealed different mechanism of the porous oxide growth when compared to the mechanism pertinent for the anodization of aluminum. Electrochemical impedance spectroscopy experiments confirmed the differences in anodic oxide growth. Surface and cross-sections of the Ni3Al intermetallic alloy with anodic oxide were observed with field-emission scanning electron microscope and characterized with appropriate software. Nanoporous oxide growth rate was estimated from cross-sectional FE-SEM images. The lowest growth rate of 0.14 μm/h was found for the anodization at 0 °C and 2.0 V. The highest one - 2.29 μm/h - was noticed for 10.0 V and 30 °C. Pore diameter was ranging from 18.9 nm (2.0 V, 0 °C) to 32.0 nm (12.0 V, 0 °C). Interpore distance of the nanoporous alumina was ranging from 56.6 nm (2.0 V, 0 °C) to 177.9 nm (12.0 V, 30 °C). Pore density (number of pore occupying given area) was decreasing with anodizing voltage increase from 394.5 pores/μm2 (2.0 V, 0 °C) to 94.9 pores/μm2 (12.0 V, 0 °C). All the geometrical features of the anodic alumina formed by two-step self-organized anodization of Ni3Al intermetallic alloy are depending on the operating conditions.

  13. 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.

  14. Viscosities of aluminum-rich Al-Cu liquid alloys

    NASA Astrophysics Data System (ADS)

    Ganesan, S.; Speiser, R.; Poirier, D. R.

    1987-06-01

    Viscosity data for Al-Cu liquid alloys in the ranges of 0≤ C L≤33.1 wt pct Cu and 1173≤ T ≤973 K are reviewed. It was found that Andrade's equation can be used to represent the variation of viscosity with temperature for a given composition, but that each of the two parameters in Andrade's equation shows no systematic variation with composition of the liquid-alloys. Consequently, arithmetic averages of the parameters were used and assumed to apply to all compositions in the range 0≤ C L ≤33.1 wt pct Cu. Such a procedure implies that the viscosity happens to vary with composition solely because the specific volume varies with composition. In order to establish the predictability of extrapolating such simple behavior, a more complex model was considered. The latter model was recently presented by Kucharski and relates viscosity to the structure and thermodynamics of liquid alloys. Viscosities obtained by interpolating Andrade's equation and Kucharski's model compare closely; furthermore, values obtained by extrapolations to lower temperatures also compare favorably. Finally the simpler model was used to calculate the viscosity of the interdendritic liquid during solidification.

  15. Positron lifetime studies of decomposition in 2024 (Al-Cu-Mg) and 7010 (Al-Zn-Cu-Mg) alloys

    SciTech Connect

    Dlubek, G. |; Lademann, P.; Krause, H.; Krause, S.; Unger, R.

    1998-09-04

    In the current paper, the decomposition behavior of the engineering alloys 2024 (Al-Cu-Mg) and 7010 (Al-Zn-Cu-Mg) is studied using positron lifetime measurements. Positrons probe open volume defects such as vacancies and dislocations. However, they may also be used to investigate coherent zones and incoherent precipitates. In order to understand the rather complicated precipitation sequences and the response of positrons to different type of precipitates occurring in 2024 and 7010 alloys, binary and ternary laboratory alloys were also investigated under the same experimental conditions as the engineering alloys. The interpretations of the results are based on experiences of the group from extensive positron studies of laboratory alloys such as Al-Zn, Al-Zn-Mg, Al-Cu, and further Al alloys (see also the review (4)). Their collected results are shown as lifetimes and curve-shape parameters S of the electron-positron momentum distribution curves characteristic for different precipitates in Al alloys.

  16. Effect of alloying on the resistance of Cu-10% Ni alloys to seawater impingement

    SciTech Connect

    Burleigh, T.D.; Waldeck, D.H.

    1999-08-01

    Cu-Ni castings and wrought pipes nominally contain 1% Fe to 2% Fe, which is added to improve the Cu-Ni alloy`s erosion-corrosion resistance. After fabrication, Cu-Ni products are solution heat-treated to dissolve the iron uniformly and form a single-phase alloy. During welding, however, iron can precipitate from solid solution onto grain boundaries in the heat-affected zones (HAZ). During seawater service, these iron-rich precipitates can dissolve preferentially (galvanically), leading to intergranular corrosion of the HAZ. The present report described 90-10 Cu-Ni alloys in which different soluble elements were substituted for iron. Jet-impingement testing in filtered natural seawater showed that 2% In also promoted improved erosion-corrosion resistance. Because indium is very soluble in copper, it should not precipitate in the HAZ during welding and cause intergranular corrosion of the HAZ during seawater service. The present study reviewed the literature on the mechanisms by which iron is believed to improve the erosion-corrosion resistance, and proposed a different model based on doping of the thin surface oxide film.

  17. 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. PMID:27102903

  18. 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.

  19. 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.

  20. 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. PMID:24177137

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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

    2016-01-01

    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

  7. Electrical Transport Properties of Liquid Al-Cu Alloys

    NASA Astrophysics Data System (ADS)

    Thakore, B. Y.; Khambholja, S. G.; Suthar, P. H.; Jani, A. R.

    2010-06-01

    Electrical transport properties viz. electrical resistivity, thermoelectric power and thermal conductivity of liquid Al-Cu alloys as a function of Cu concentration have been studied in the present paper. Ashcroft empty core model potential has been used to incorporate the ion-electron interaction. To incorporate the exchange and correlation effects, five different forms of local field correction functions viz. Hartree, Taylor, Ichimaru et al., Farid et al. and Sarkar et al. have been used. The transport properties of binary system have been studied using Faber-Ziman formulation combined with Ashcroft-Langreth (AL) partial structure factor. The computed values of electrical resistivity are compared with experimental data and for low Cu concentration, good agreement has been observed. Further, thermoelectric power and thermal conductivity have also been predicted.

  8. Undercooling, Liquid Separation and Solidification of Cu-Co Alloys

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

    Large undercooling can induce not only various solidification pathways, but also a precursor reaction, or liquid separation. This paper deals with the latter effect of undercooling using examples of the Cu-Co system which has a flattened liquidus. Bulk Cu-Co alloys (about 7mm diameter) at compositions ranging from 10 to 90 wt pct Co were highly undercooled using a fluxing technique. Except for Cu-90 wt pct Co, liquid separation was directly observed as undercooling exceeded a critical value depending on the composition. It was also confirmed by a microstructural transition from dendrites to droplets above the critical undercooling. Finally, theoretical calculations regarding the metastable miscibility boundary and maximum droplet radius were made to analyze the experimental results.

  9. Trace elements distribution in Cu-Si alloys

    NASA Astrophysics Data System (ADS)

    Mitrašinović, Aleksandar M.; Utigard, Torstein A.

    2011-10-01

    The trace elements distribution in Cu-Si alloys is analyzed after mixing Si with Cu. The mass balance and atomic distribution showed that the highest concentration of trace elements was at the phase boundaries between Si and Cu-Si intermetallic. The concentrations of 21 trace elements in the refined Si were below detection limit of the ICP technique where 11 elements were below 1ppm at and another 7 elements were below 2ppm at. The amount of other elements decreased several times in the refined Si, compared to that in initial metallurgical grade silicon. The level of trace elements in refined Si allows utilization of the Si photo-catalytic characteristics for solar energy generation.

  10. In Situ Transmission Electron Microscopy Observation of the Lithiation-Delithiation Conversion Behavior of CuO/Graphene Anode.

    PubMed

    Su, Qingmei; Yao, Libing; Zhang, Jun; Du, Gaohui; Xu, Bingshe

    2015-10-21

    The electrochemical conversion behavior of metal oxides as well as its influence on the lithium-storage performance remains unclear. In this paper, we studied the dynamic electrochemical conversion process of CuO/graphene as anode by in situ transmission electron microscopy. The microscopic conversion behavior of the electrode was further correlated with its macroscopic lithium-storage properties. During the first lithiation, the porous CuO nanoparticles transformed to numerous Cu nanograins (2-3 nm) embedded in Li2O matrix. The porous spaces were found to be favorable for accommodating the volume expansion during lithium insertion. Two types of irreversible processes were revealed during the lithiation-delithiation cycles. First, the nature of the charge-discharge process of CuO anode is a reversible phase conversion between Cu2O and Cu nanograins. The delithiation reaction cannot recover the electrode to its pristine structure (CuO), which is responsible for about ∼55% of the capacity fading in the first cycle. Second, there is a severe nanograin aggregation during the initial conversion cycles, which leads to low Coulombic efficiency. This finding could also account for the electrochemical behaviors of other transition metal oxide anodes that operate with similar electrochemical conversion mechanism. PMID:26437926

  11. 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.

  12. 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.

  13. Anode behaviors of aluminum antimony synthesized by mechanical alloying for lithium secondary battery

    SciTech Connect

    Honda, H.; Sakaguchi, H.; Fukuda, Y.; Esaka, T

    2003-03-24

    AlSb was synthesized as an anode active material for lithium secondary battery using mechanical alloying (MA). Electrochemical performance was examined on the electrodes of AlSb synthesized with different MA time. The first charge (lithium-insertion) capacity of the AlSb electrodes decreased with increasing the MA time. The discharge capacity on repeating charge-discharge cycle, however, did not show the same dependence. The electrode, consisting of the 20 h MA sample exhibited the longest charge-discharge life cycle, suggesting that there is the optimum degree of internal energy derived from the strain and/or the amorphization due to mechanical alloying. These results were evaluated using ex situ X-ray diffraction and differential scanning calorimetry.

  14. 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'. PMID:27402936

  15. Giant spin Hall effect in CuBi alloys

    NASA Astrophysics Data System (ADS)

    Otani, Yoshichika

    2013-03-01

    Spintronic devices manipulating pure spin currents, flows of spin angular momentum without net charge current, should play an important role in low energy consumption electronics for next generation. This explains the current interest for the spin Hall effect (SHE) which provides a purely electrical way to create spin currents without ferromagnets and magnetic fields. In this work, we have studied extrinsic SHEs in Cu-based alloys. Copper itself does not show any SHE, but by adding impurities with strong spin-orbit interactions such as Ir and Bi, the extrinsic SHEs can be generated and one can tune the SH angle which represents the maximum yield of conversion of charge to spin current density. The SH resistance was measured by means of spin absorption method using a lateral spin valve structure with an inserted wire of SHE material. We found that Cu99.5Bi0.5 exhibited a very large negative SH resistance whereas Pt and a Cu99Ir1 alloy had positive SH resistances. From nonlocal spin valve measurements with the SHE materials, we can obtain the spin absorption rates as well as the spin diffusion lengths of the SHE materials. The spin Hall angle was determined by fitting experimental data to two theoretical models, i.e., a purely 1D model and a 3D spin transport model based on an extension to 3D of the Valet-Fert formalism. For Pt and CuIr alloys, the spin diffusion lengths are smaller than their thickness (20 nm), and the SH angles obtained from the 1D and 3D analyses are similar to each other (about 2% for both Pt and CuIr). For CuBi alloys, however, the analysis in the 3D model gave much larger SH angle of about - 24% than the 1D of about -12%. More interestingly the fact that Bi impurities generated much larger SH angle than Pt and Ir, was consistent with a recent ab-initio theoretical calculation.

  16. 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.

  17. Micro-nanostructured CuO/C spheres as high-performance anode materials for Na-ion batteries

    NASA Astrophysics Data System (ADS)

    Lu, Yanying; Zhang, Ning; Zhao, Qing; Liang, Jing; Chen, Jun

    2015-01-01

    In this paper, we report on the synthesis of micro-nanostructured CuO/C spheres by aerosol spray pyrolysis and their application as high-performance anodes in sodium-ion batteries. Micro-nanostructured CuO/C spheres with different CuO contents were synthesized through aerosol spray pyrolysis by adjusting the ratio of reactants and heat-treated by an oxidation process. The as-prepared CuO/C spheres show uniformly spherical morphology, in which CuO nanoparticles (~10 nm) are homogeneously embedded in the carbon matrix (denoted as 10-CuO/C). The electrochemical performance of 10-CuO/C with a carbon weight of 44% was evaluated as the anode material for Na-ion batteries. It can deliver a capacity of 402 mA h g-1 after 600 cycles at a current density of 200 mA g-1. Furthermore, a capacity of 304 mA h g-1 was obtained at a high current density of 2000 mA g-1. The superior electrochemical performance of the micro-nanostructured CuO/C spheres leads to the enhancement of the electronic conductivity of the nanocomposite and the accommodation of the volume variation of CuO/C during charge/discharge cycling.In this paper, we report on the synthesis of micro-nanostructured CuO/C spheres by aerosol spray pyrolysis and their application as high-performance anodes in sodium-ion batteries. Micro-nanostructured CuO/C spheres with different CuO contents were synthesized through aerosol spray pyrolysis by adjusting the ratio of reactants and heat-treated by an oxidation process. The as-prepared CuO/C spheres show uniformly spherical morphology, in which CuO nanoparticles (~10 nm) are homogeneously embedded in the carbon matrix (denoted as 10-CuO/C). The electrochemical performance of 10-CuO/C with a carbon weight of 44% was evaluated as the anode material for Na-ion batteries. It can deliver a capacity of 402 mA h g-1 after 600 cycles at a current density of 200 mA g-1. Furthermore, a capacity of 304 mA h g-1 was obtained at a high current density of 2000 mA g-1. The superior

  18. 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%.

  19. Micro-nanostructured CuO/C spheres as high-performance anode materials for Na-ion batteries.

    PubMed

    Lu, Yanying; Zhang, Ning; Zhao, Qing; Liang, Jing; Chen, Jun

    2015-02-14

    In this paper, we report on the synthesis of micro-nanostructured CuO/C spheres by aerosol spray pyrolysis and their application as high-performance anodes in sodium-ion batteries. Micro-nanostructured CuO/C spheres with different CuO contents were synthesized through aerosol spray pyrolysis by adjusting the ratio of reactants and heat-treated by an oxidation process. The as-prepared CuO/C spheres show uniformly spherical morphology, in which CuO nanoparticles (∼10 nm) are homogeneously embedded in the carbon matrix (denoted as 10-CuO/C). The electrochemical performance of 10-CuO/C with a carbon weight of 44% was evaluated as the anode material for Na-ion batteries. It can deliver a capacity of 402 mA h g(-1) after 600 cycles at a current density of 200 mA g(-1). Furthermore, a capacity of 304 mA h g(-1) was obtained at a high current density of 2000 mA g(-1). The superior electrochemical performance of the micro-nanostructured CuO/C spheres leads to the enhancement of the electronic conductivity of the nanocomposite and the accommodation of the volume variation of CuO/C during charge/discharge cycling. PMID:25584745

  20. 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)

  1. 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.

  2. Superhydrophobic hierarchical surfaces fabricated by anodizing of oblique angle deposited Al-Nb alloy columnar films

    NASA Astrophysics Data System (ADS)

    Fujii, Takashi; Aoki, Yoshitaka; Habazaki, Hiroki

    2011-07-01

    A combined process of oblique angle magnetron sputtering and anodizing has been developed to tailor superhydrophobic surfaces with hierarchical morphology. Isolated submicron columns of single-phase Al-Nb alloys are deposited by magnetron sputtering at several oblique deposition angles on a scalloped substrate surface, with the gaps between columns increasing with an increase in the deposition angle from 70° to 110°. Then, the columnar films have been anodized in hot phosphate-glycerol electrolyte to form a nanoporous anodic oxide layer on each column. Such surfaces with submicron-/nano-porous structure have been coated with a fluoroalkyl phosphate layer to reduce the surface energy. The porous surface before coating is superhydrophilic with a contact angle for water is less than 10°, while after coating the contact angles are larger than 150°, being superhydrophobic. The beneficial effect of dual-scale porosity to enhance the water repellency is found from the comparison of the contact angles of the submicron columnar films with and without nanoporous oxide layers. The larger submicron gaps between columns are also preferable to increase the water repellency.

  3. 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.

  4. Nucleation and Growth of Cu-Al Intermetallics in Al-Modified Sn-Cu and Sn-Ag-Cu Lead-Free Solder Alloys

    NASA Astrophysics Data System (ADS)

    Reeve, Kathlene N.; Anderson, Iver E.; Handwerker, Carol A.

    2015-03-01

    Lead-free solder alloys Sn-Cu (SC) and Sn-Ag-Cu (SAC) are widely used by the microelectronics industry, but enhanced control of the microstructure is needed to improve solder performance. For such control, nucleation and stability of Cu-Al intermetallic compound (IMC) solidification catalysts were investigated by variation of the Cu (0.7-3.0 wt.%) and Al (0.0-0.4 wt.%) content of SC + Al and SAC + Al alloys, and of SAC + Al ball-grid array (BGA) solder joints. All of the Al-modified alloys produced Cu-Al IMC particles with different morphologies and phases (occasionally non-equilibrium phases). A trend of increasing Cu-Al IMC volume fraction with increasing Al content was established. Because of solidification of non-equilibrium phases in wire alloy structures, differential scanning calorimetry (DSC) experiments revealed delayed, non-equilibrium melting at high temperatures related to quenched-in Cu-Al phases; a final liquidus of 960-1200°C was recorded. During cooling from 1200°C, the DSC samples had the solidification behavior expected from thermodynamic equilibrium calculations. Solidification of the ternary alloys commenced with formation of ternary β and Cu-Al δ phases at 450-550°C; this was followed by β-Sn, and, finally, Cu6Sn5 and Cu-Al γ1. Because of the presence of the retained, high-temperature phases in the alloys, particle size and volume fraction of the room temperature Cu-Al IMC phases were observed to increase when the alloy casting temperature was reduced from 1200°C to 800°C, even though both temperatures are above the calculated liquidus temperature of the alloys. Preliminary electron backscatter diffraction results seemed to show Sn grain refinement in the SAC + Al BGA alloy.

  5. Microwave sintering of W-18Cu and W-7Ni-3Cu alloys.

    PubMed

    Mondal, Avijit; Upadhyaya, Anish; Agrawal, Dinesh

    2009-01-01

    Microwave processing is emerging as an innovative and highly effective material processing method offering many advantages over conventional methods, especially for sintering applications. It is recognized for its various advantages, such as: time and energy saving, rapid heating rates, considerably reduced processing cycle time and temperature, fine microstructures and improved mechanical properties which lead to better product performance. Major constraints in conventional sintering of refractory material such as tungsten and its alloys are high sintering temperatures and long soaking times which cause abnormal grain growth and lead to poor mechanical properties. They get further aggravated at smaller (submicron and nano) tungsten powder sizes. This study describes recent research findings; W-18Cu and W-7Ni-3Cu alloys have been successfully consolidated using microwave heating which resulted in an overall reduction of sintering time of up to 80%. The microwave sintered samples exhibited finer microstructure and superior mechanical properties when compared with the conventional samples. PMID:21384717

  6. Cold Spraying of Amorphous Cu50Zr50 Alloys

    NASA Astrophysics Data System (ADS)

    List, A.; Gärtner, F.; Mori, T.; Schulze, M.; Assadi, H.; Kuroda, S.; Klassen, T.

    2015-01-01

    A new range of applications in cold spraying is expected for bulk metallic glass (BMG) coatings. For retaining amorphous structures in cast multi-component BMG parts, typically high purity raw material must be used. The present investigation explores an alternative approach, where cold spraying is used to deposit a technical-grade binary amorphous alloy. This approach is shown to be potentially cost-effective and suitable for rapid manufacturing. For this purpose, amorphous Cu50Zr50 was chosen as a model alloy system, and cold spraying was performed using nitrogen as process gas. By a systematic variation of the spray parameter sets, the critical velocities for coating formation were determined experimentally. Based on the current models of bonding of amorphous Cu50Zr50 powder in cold spraying, a new, more comprehensive concept of bonding and rebound is presented, which also considers the presence of liquefied interfaces and quenching rates for resolidification. Results concerning impact morphologies and coating formation demonstrate that under suitable choice of spray conditions, well-adhering coatings with amorphous structure of the Cu50Zr50 powders can be obtained by cold spraying.

  7. 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.

  8. Advances in aluminum anodizing

    NASA Technical Reports Server (NTRS)

    Dale, K. H.

    1969-01-01

    White anodize is applied to aluminum alloy surfaces by specific surface preparation, anodizing, pigmentation, and sealing techniques. The development techniques resulted in alloys, which are used in space vehicles, with good reflectance values and excellent corrosive resistance.

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

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  10. Characteristics of Molten Alloys as Anodes in Solid Oxide Fuel Cells

    SciTech Connect

    Javadekar, Ashay; Jayakumar, Abhimanyu; Gorte, R. J.; Vohs, J. M.; Buttrey, D. J.

    2011-11-01

    Molten alloys with 50-mol% In-Sb, Sn-Sb, Sb-Bi, and Sb-Pb were examined as anodes for solid oxide fuel cells at 973 K. The cells were operated in the battery mode, without added fuel, in order to understand the oxidation characteristics of these alloys at electrolyte interfaces. Cells using 50-mol% In-Sb and Sn-Sb mixtures exhibited open-circuit voltages (OCV) of 1.0 and 0.93 V, values that are identical to that of cell with pure In and Sn respectively. Also similar to the pure In and Sn anodes, the impedances of these cells were initially low but increased dramatically after drawing a small amount of charge, implying formation of In₂O₃ and SnO₂ layers at the electrolyte interface. The 50-mol% Sb-Bi cell had an OCV of 0.73 V initially, close to the OCV observed with pure Sb. The OCV remained constant until a charge identical to that required for oxidation of all the Sb had been passed, after which the OCV dropped to 0.43 V, similar to the value for pure Bi. SEM analysis of the cell after conversion of the Sb showed two distinct phases, with metallic Bi at the bottom and Sb₂O₃ at the top. The electrochemical oxidation of 50-mol% Sb-Pb alloys exhibited an OCV that changed continuously with conversion, from 0.73 V initially to 0.67 V following the addition of charge corresponding to oxidation of 120% the Sb. The total cell impedance remained low for this entire period. EDS measurements on the sectioned Sb-Pb cell suggested that both Sb and Pb were oxidized simultaneously to form a mixed oxide of Pb and Sb.

  11. 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.

  12. 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.

  13. Component, Microstructure and Simulation Calculation Study of Bimetallic Pt-Cu Alloys Towards Catalyzing Methanol Oxidation Reaction

    NASA Astrophysics Data System (ADS)

    Wei, Shenying; Gao, Huaizhi; Li, Haibo; Li, Rui; Liu, Jifeng

    2014-12-01

    Three Pt-Cu alloys (Pt0.3Cu0.7, Pt0.5Cu0.5, and Pt0.7Cu0.3) with different Cu contents were synthesized by adjusting the Pt/Cu precursor ratio, and their electrocatalytic activities for methanol oxidation reaction (MOR) were systematically studied. Component and microstructure study revealed that the relationship between the lattice parameters and Cu content followed the Vegard's law. Electrochemistry measurement showed that the MOR catalytic activity for Pt-Cu alloys displayed a dependency on the Cu content, and it decreased following: Pt0.3Cu0.7 > Pt0.5Cu0.5 > Pt0.7Cu0.3. Among the three Pt-Cu alloys, the Pt0.3Cu0.7 alloy exhibited the highest oxidation current density and best CO tolerance activity. Density functional theory simulation calculation, taking into account the shrinking of Pt-Cu alloy's lattice after Cu incorporation, confirmed that the adsorption energy of CO also displayed a dependency on the Cu content in Pt-Cu alloys, and it increased following: Pt0.3Cu0.7 < Pt0.5Cu0.5 < Pt0.7Cu0.3 < Pt, which could rationally explain the best CO tolerance ability for the Pt0.3Cu0.7.

  14. Hydrogen isotope trapping in Al-Cu binary alloys

    DOE PAGESBeta

    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

  15. 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.

  16. Development and evaluation of anode alloys for aluminum/air batteries: Final report

    SciTech Connect

    Macdonald, D.; Real, S.; Urquidi-Macdonald, M.

    1987-02-01

    Experimental and theoretical studies are reported on the development of aluminum alloys for alkaline aluminumair batteries. This work begins by analyzing the thermodyanmics of aluminum in LiOH, NaOH, and KOH solutions as a function of concentration (0 to 7 molkg alkali) and temperature (25 to 100)degree)C). The thermodynamic data define the conditions under which precipitation of Al(OH)/sub 3/ may occur but, more importantly for this study, they yield equilibrium potentials for various charge transfer reactions, including aluminum dissolution, Al(OH)/sub 3/ and A100H formation, AlH/sub 3/ formation, oxygen reduction, and hydrogen evoltuion. These data are used in our mechanistic analyses of aluminum electrodissolution. The findings of this work form the basis of a working model for the activation of aluminum alloy fuels for alkaline aluminumair batteries, in which activation is attributed to the oxidative dissolution of a protective layer of metallic alloying elements (principally gallium) from the surface at a voltage of )approximately)1.5 V (HgHgO). This model is now being used to design and prepare new high energy density anodes for Alair batteris. 29 refs., 87 figs., 39 tabs

  17. 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.

  18. 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

  19. Corrosion of Cu-Ni alloys in sulfide-polluted seawater

    SciTech Connect

    Al-Hajji, J.N. . Mechanical Engineering Dept.); Reda, M.R. . Chemical Engineering Dept.)

    1993-10-01

    A study of the corrosion of copper-nickel (Cu-Ni) alloys showed hydrodynamic conditions increased the corrosion rate (I[sub corr]) significantly by reducing the sulfide concentration polarization. Pre-exposure to oxidation products of dissolved sulfide and elemental sulfur (S) increased I[sub corr] of the alloys in seawater significantly. Pre-exposure to nitrite and chromate decreased I[sub corr] by almost 2 orders of magnitude for alloys of 90% Cu-10% Ni and 70% Cu-30% Ni. However, cyclic polarization curves for both alloys pre-exposed to chromate and nitrite showed the passivators caused severe localized corrosion for the 70% Cu-30% Ni alloy only by transition from the active to passive state. The corrosion mechanism of the 90% Cu-10% Ni alloy differed from that of the 70% Cu-30% Ni alloy in quiescent sulfide-polluted seawater. A four-part corrosion mechanism was proposed. The rate of sulfide ion diffusion to the alloy-solution interface always was the rate determining step for corrosion of the alloy of higher Ni content, whereas different kinetics of the reaction determined I[sub corr] of the second alloy.

  20. 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.

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

    SciTech Connect

    Noce, R. D.; Barthem, V. M. T. S.; Magalhaes, S. D. de; Wolf, W.; Castro, A. C. de; Guimaraes, R. B.; Pires, M. J. M.; Macedo, W. A. A.; Givord, D.

    2009-11-01

    Fe{sub x}Cu{sub 100-x} metastable alloys were prepared by pulsed electrodeposition for 5alloys crystallize in the bcc structure of alpha-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.

  2. 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.

  3. Ductile Chromium in Heavily Cold-Drawn Cu75Cr25 Alloy

    NASA Astrophysics Data System (ADS)

    Chang, Yanli; Zhou, Zhiming; Guo, Ziqin; Wang, Yaping

    2016-01-01

    Microstructure evolution, gas content, and properties of the heavily cold-drawn Cu75Cr25 alloy were studied. Results showed that the oxygen and nitrogen contents of Cu75Cr25 alloy prepared by vacuum induction melting in calcia crucibles were low, about 320 and 20 ppm, respectively. The Cu75Cr25 material with low gas content can be cold drawn to lines with diameter less than 0.1 mm, in which Cr phase displays thin and curving morphology. The coherent interface, forming between Cu(111) and Cr(110) during the heavily cold-drawing process, constrained Cr phase and greatly improved its deformability as well as increased the strength of the Cu-Cr alloy. The breaking strength and electrical conductivity of the Cu75Cr25 alloy were about 577 MPa and 60 pct IACS, respectively.

  4. In situ TEM Studies of the Initial Oxidation stage of Cu and Cu Alloy Thin Films

    NASA Astrophysics Data System (ADS)

    Yang, Judith; Kang, Yihong; Luo, Langli; Ciston, James; Stach, Eric; Zhou, Guangwen

    2012-02-01

    The fundamental understanding of oxidation at the nanoscale is important for the environmental stability of coating materials as well as processing of oxide nanostructures. Our previous studies show the epitaxial growth of Cu2O islands during the initial stages of oxidation of Cu thin films, where surface diffusion and strain impact the oxide development and morphologies. The addition of secondary elements changes the oxidation mechanism. If the secondary element is non-oxidizing, such as Au, it will limit the Cu2O island growth due to the depletion of Cu near the oxide islands. When the secondary element is oxidizing, for example Ni, the alloy will show more complex behaviour, where duplex oxide islands were observed. Nucleation density and growth rate of oxide islands are observed under various temperatures and oxygen partial pressures (pO2) as a function of time by in situ ultra high vacuum (UHV)-transmission electron microscopy (TEM). Our initial results of Cu-Ni(001) oxidation is that the oxide epitaxy and morphologies change as function of Ni concentration. For higher spatial resolution, we are examining the atomic scale oxidation by aberration-corrected ETEM with 1å resolution.

  5. 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.

  6. CuO/Cu2O composite hollow polyhedrons fabricated from metal-organic framework templates for lithium-ion battery anodes with a long cycling life

    NASA Astrophysics Data System (ADS)

    Hu, Lin; Huang, Yimin; Zhang, Fapei; Chen, Qianwang

    2013-05-01

    Novel CuO/Cu2O hollow polyhedrons with porous shells were fabricated by thermal decomposition of coordination compound [Cu3(btc)2]n (btc = benzene-1,3,5-tricarboxylate) polyhedrons at 350 °C. When tested as anode materials for lithium-ion batteries, these hollow polyhedrons exhibited a reversible lithium storage capacity as high as 740 mA h g-1 at 100 mA g-1 after 250 cycles even if the charge-discharge process is stopped for one week during the test time.Novel CuO/Cu2O hollow polyhedrons with porous shells were fabricated by thermal decomposition of coordination compound [Cu3(btc)2]n (btc = benzene-1,3,5-tricarboxylate) polyhedrons at 350 °C. When tested as anode materials for lithium-ion batteries, these hollow polyhedrons exhibited a reversible lithium storage capacity as high as 740 mA h g-1 at 100 mA g-1 after 250 cycles even if the charge-discharge process is stopped for one week during the test time. Electronic supplementary information (ESI) available: Experimental details and characterization: Fig. S1-S8. See DOI: 10.1039/c3nr00623a

  7. 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.

  8. Quantification of Microsegregation in Cast Al-Si-Cu Alloys

    NASA Astrophysics Data System (ADS)

    Ganesan, M.; Thuinet, L.; Dye, D.; Lee, P. D.

    2007-08-01

    The random sampling approach offers an elegant yet accurate way of validating microsegregation models. However, both instrumental errors and interference from secondary phases complicate the treatment of randomly sampled microprobe data. This study demonstrates that the normal procedure of sorting the data for each element independently can lead to inaccurate estimation of segregation profiles within multicomponent, multiphase, aluminum alloys. A recently proposed alloy-independent approach is shown to more reliably isolate these interferences, allowing more accurate validation of microsegregation models. Application of this approach to examine solidification segregation of a 319-type alloy demonstrated that, for these slowly cooled castings, neither Sr or TiB2 additions significantly affected coring of Cu within the primary α-Al dendrites. Comparison against predictions of CALPHAD-type Gulliver-Scheil models was less satisfactory. Consideration of back-diffusion and morphology effects through a one-dimensional (1-D) numerical model do not improve the agreement. Possible reasons for the lack of agreement are hypothesized.

  9. 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. PMID:26028125

  10. 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.

  11. Preparation and some properties of Cu-Li alloys containing up to 20 at. % Li

    SciTech Connect

    Mendelsohn, M.; Krauss, A.R.; Gruen, D.M.

    1985-01-01

    Lithium strongly segregates to the surface of Cu-Li alloys, thus substantially lowering the Cu sputtering yield relative to pure Cu. Use of Cu-Li limiters or divertors in tokamaks can therefore be expected to be beneficial in limiting high-Z plasma impurity influx. A large scale (100-200g) method for the preparation of Cu-Li alloys is described. Analysis reveals that on solidification from the melt stratification occurs which leads to compositional inhomogeneity. The results are discussed in the light of the Cu-Li binary phase diagram and rationalized on the basis of large density differences between Cu and Cu-Li solid solutions. It is concluded that obtaining homogeneous Cu-Li solid solutions is a nontrivial task.

  12. Evaluation of AA5052 alloy anode in alkaline electrolyte with organic rare-earth complex additives for aluminium-air batteries

    NASA Astrophysics Data System (ADS)

    Wang, Dapeng; Li, Heshun; Liu, Jie; Zhang, Daquan; Gao, Lixin; Tong, Lin

    2015-10-01

    Behaviours of the AA5052 aluminium alloy anode of the alkaline aluminium-air battery are studied by the hydrogen evolution test, the electrochemical measurements and the surface analysis method. The combination of amino-acid and rare earth as electrolyte additives effectively retards the self-corrosion of AA5052 aluminium alloy in 4 M NaOH solution. It shows that the combination of L-cysteine and cerium nitrate has a synergistic effect owing to the formation of a complex film on AA5052 alloy surface. The organic rare-earth complex can decrease the anodic polarisation, suppress the hydrogen evolution and increase the anodic utilization rate.

  13. 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.

  14. 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.

  15. 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.

  16. Formation of Nanocrystalline Surface of Cu-Sn Alloy Foam Electrochemically Produced for Li-Ion Battery Electrode.

    PubMed

    Ye, Bora; Kim, Sunjung

    2015-10-01

    Cu-Sn alloy foam is a promising electrode material for Li-ion batteries. In this study, Cu-Sn alloy foam was produced by diffusion-limited electrodeposition in alkaline electrolyte using polyurethane (PU) foam template. Our major concern is to form Cu-Sn alloy foam with nanocrystalline surface morphology by adjusting electrodeposition conditions such as deposition potential and metal ion concentration. Cu-Sn alloy layers comprising of nanoclusters such as nanospheres, nanoellipsoids, and nanoflakes were created depending on electrodeposition conditions. Larger surface area of nanocluster-interconnected Cu-Sn alloy layer was created when both Sn concentration and negative deposition potential were higher. After decomposing PU template thermally, Cu-Sn alloy foam of Cu, Cu6Sn5, and Cu3Sn phases was finally produced. PMID:26726491

  17. 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.

  18. 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.

  19. 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. PMID:26771194

  20. 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

  1. Influence of alloying effect on X-ray fluorescence parameters of Co and Cu in CoCuAg alloy films

    NASA Astrophysics Data System (ADS)

    Aylikci, Nuray Kup; Tiraşoğlu, Engin; Apaydin, Gökhan; Cengiz, Erhan; Aylikci, Volkan; Bakkaloğlu, Ömer Faruk

    2009-06-01

    In this study, K β/K α X-ray intensity ratios, σ, σ production cross-sections and ωK fluorescence yields of Co and Cu and L β/L α X-ray intensity ratios, σ, σ production cross-sections and ϖ average fluorescence yields of Ag in pure metals and in different alloy compositions were measured. In this study, alloying effects on the σ production cross-sections of Co and Cu were investigated and changes interpreted according to the rearrangement of valance state electrons and the charge transfer process between the 3d elements (Co and Cu) and Ag.

  2. 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

    2016-04-01

    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.

  3. 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.

  4. Conduction mechanism of the anodic film on Fe-Cr alloys in sulfate solutions

    SciTech Connect

    Bojinov, M.; Fabricius, G.; Laitinen, T.; Maekelae, K.; Saario, T.; Sundholm, G.

    1999-09-01

    The passive state of Fe-12% Cr and Fe-25% Cr alloys in 1 M sulfate solutions of pH 0 and 5 was studied with a combination of electrochemical techniques: impedance spectroscopy, photoelectrochemistry, and dc resistance measurements by the contact electric resistance technique. The investigations were supported by studies on pure metal constituents (Fe, Cr) in the same solutions. As a result, the steady-state passive film on the alloys (and on pure Cr) can be described as a thin, essentially insulating layer. Polarization of the steady-state metal/anodic film/electrolyte system to negative and positive potentials away from the potential region corresponding to the highest electronic resistance was concluded to lead to the generation of lower or higher valency defects at the interfaces via solid-state electrochemical reactions. These reactions result in a substantial increase of the conductivity in the first layers adjacent to either the metal/film or the film/electrolyte interface. At very negative (or very positive) potentials the film is transformed into a conductor allowing active (or transpassive) dissolution to take place. A quantitative physical model of the conduction mechanism on the basis of the surface charge approach is proposed and compared with experimental data.

  5. 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. PMID:21275384

  6. Electrochemical performance and carbon deposition resistance of M-BaZr₀.₁Ce₀.₇Y₀.₁Yb₀.₁O₃₋δ (M = Pd, Cu, Ni or NiCu) anodes for solid oxide fuel cells.

    PubMed

    Li, Meng; Hua, Bin; Pu, Jian; Chi, Bo; Jian, Li

    2015-01-01

    Pd-, Cu-, Ni- and NiCu-BaZr₀.₁Ce₀.₇Y₀.₁Yb₀.₁O₃₋δ anodes, designated as M-BZCYYb, were prepared by impregnating M-containing solution into BZCYYb scaffold, and investigated in the aspects of electrocatalytic activity for the reactions of H₂ and CH₄ oxidation and the resistance to carbon deposition. Impregnation of Pd, Ni or NiCu significantly reduced both the ohmic (RΩ) and polarization (RP) losses of BZCYYb anode exposed to H₂ or CH₄, while Cu impregnation decreased only RΩ in H₂ and the both in CH4. Pd-, Ni- and NiCu-BZCYYb anodes were resistant to carbon deposition in wet (3 mol. % H₂O) CH₄ at 750°C. Deposited carbon fibers were observed in Pd- and Ni-BZCYYb anodes exposed to dry CH4 at 750°C for 12 h, and not observed in NiCu-BZCYYb exposed to dry CH₄ at 750°C for 24 h. The performance of a full cell with NiCu-BZCYYb anode, YSZ electrolyte and La₀.₆Sr₀.₄Co₀.₂Fe₀.₈O₃₋δ-Gd doped CeO₂ (LSCF-GDC) cathode was stable at 750°C in wet CH₄ for 130 h, indicating that NiCu-BZCYYb is a promising anode for direct CH₄ solid oxide fuel cells (SOFCs). PMID:25563843

  7. Microstructure and Properties of Sn-10Bi- xCu Solder Alloy/Joint

    NASA Astrophysics Data System (ADS)

    Lai, Zhongmin; Ye, Dan

    2016-07-01

    The effect of Cu on the microstructure and properties of Sn-10Bi solder alloy/joint were investigated. The results showed that the microstructure of Sn-10Bi-Cu solder alloy consisted of a Sn-rich phase, Bi-rich phase, and particles of Cu6Sn5 intermetallic compounds (IMCs). The pasty range of Sn-10Bi- xCu had an influence on the spreading property of Sn-10Bi- xCu. Cu improved the growth of the IMCs layer during the liquid reaction stage. Furthermore, the hardness of the solder alloy increased as the Cu concentration of increased. The strength of the solder joint was controlled by the solder alloy hardness and the interfacial IMCs layer thickness together. For the joints with low solder alloy hardness and a thin IMCs layer, the fracture was in the solder alloy. For the joints with high solder alloy hardness and a thick IMCs layer, the fracture was in the IMCs layer.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

    2016-04-01

    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.

  12. 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.

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

    SciTech Connect

    Wagner, J.A.; Gangloff, R.P. Virginia, University, Charlottesville )

    1992-06-01

    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. 21 refs.

  14. 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.

  15. 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

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

    PubMed

    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

  17. 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.

  18. 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.

  19. 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.

  20. Dependence of alloying and island composition on terrace width: Growth of Cu on Ag(100)

    NASA Astrophysics Data System (ADS)

    Beichert, Agnes; Zaum, Christopher; Morgenstern, Karina

    2015-07-01

    The growth of Cu on Ag(100) is investigated by low-temperature scanning tunneling microscopy. Exchange diffusion of Cu deposited onto Ag(100) leads to small pure Cu islands and larger islands consisting of a CuAg alloy in room temperature growth. The ratio of the different types of islands depends on terrace widths up to 100 nm. This surprisingly long-range dependence is correlated to the density of the surface alloy. We thus reveal that the exchange diffusion barrier is influenced by terrace widths far beyond quantum size confinement.

  1. 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.

  2. Low-temperature, facile fabrication of ultrafine Cu2O networks by anodization on TiO2 nanotube arrays

    NASA Astrophysics Data System (ADS)

    Luo, S. L.; Li, Y.; Yang, L. X.; Liu, C. B.; Su, F.; Chen, Y.

    2012-10-01

    A green and facile process was developed to fabricate ultrafine p-type Cu2O single crystal nanowires by anodizing copper (Cu0) particles preloaded on TiO2 nanotube arrays. The Cu2O nanowires with a diameter of less than 5 nm were assembled on the top surface of n-type TiO2 nanotube arrays, constructing a novel p-n junction heterostructure with larger specific surface area compared to the unmodified TiO2 nanotube arrays. X-ray diffractometer (XRD) and high-resolution transmission electron microscopy (HRTEM) were employed to demonstrate that the resulting Cu2O was single crystalline. The composite Cu2O/TiO2 nanotube arrays exhibited significantly enhanced response to the visible light, resulting from Cu2O with a narrow-band gap. Furthermore, under visible light irradiation, enhanced efficiency in separating photogenerated hole-electron pairs was achieved due to the potential difference generated on the p-n interface. A possible mechanism was proposed to explain the formation of crystal Cu2O nanowires.

  3. Hybrid CuO/SnO2 nanocomposites: Towards cost-effective and high performance binder free lithium ion batteries anode materials

    NASA Astrophysics Data System (ADS)

    Xing, G. Z.; Wang, Y.; Wong, J. I.; Shi, Y. M.; Huang, Z. X.; Li, S.; Yang, H. Y.

    2014-10-01

    Hybrid CuO/SnO2 nanocomposites are synthesized by a facile thermal annealing method on Cu foils. Compared to pristine CuO and SnO2 nanostructures, hybrid CuO/SnO2 nanocomposites exhibit the enhanced electrochemical performances as the anode material of lithium ion batteries (LIBs) with high specific capacity and excellent rate capability. The binder free CuO/SnO2 nanocomposites deliver a specific capacity of 718 mA h g-1 at a current density of 500 mA g-1 even after 200 cycles. The enhanced electrochemical performances are attributed to the synergistic effect between SnO2 nanoparticles and CuO nanoarchitectures. Such hybrid CuO/SnO2 nanocomposites could open up a new route for the development of next-generation high-performance and cost-effective binder free anode material of LIBs for mass production.

  4. 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.

  5. 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. PMID:16102560

  6. Surface Morphology Changes During Pb Deposition on Cu(100): Evidence for Surface Alloyed Cu(100)-c(2x2) Pb

    SciTech Connect

    PLASS,RICHARD A.; KELLOGG,GARY LEE

    2000-07-13

    Using Low Energy Electron Microscopy (LEEM), the authors have followed Cu(100) surface morphology changes during Pb deposition at different temperatures. Surface steps advance and 2-D islands nucleate and grow as deposited Pb first alloys, and then dealloys, on a 125 C Cu(100)surface. From LEEM images, they determine how much Cu is being displaced at each stage and find that the amount of material added to the top layer for a complete Pb/Cu(100) c(4x4) reconstruction (a surface alloy) is consistent with the expected c(4x4) Cu content of 0.5 monolayer. However, as the surface changes to the Pb/Cu(100) c(2x2) overlayer, they find that the displaced material from surface dealloying, 0.22ML, is more than a factor of two lower than expected based on a pure Pb c(2x2) overlayer. Further, they find that in the 70 to 130 C range the amount of Cu remaining in c(2x2) increases with increasing substrate temperature during the deposition, showing that surface Cu is alloyed with Pb in the c(2x2) structure at these temperatures. When holding the sample at 125 C, the transformation from the c(2x2) structure to the higher coverage c(5{radical}2 x{radical}2)R45{degree} overlayer structure displaces more Cu, confirming the c(2x2) surface alloy model. They also find the c(2x2) surface has characteristically square 2-D islands with step edges parallel to the (100) type crystallographic directions, whereas the c(5{radical}2 x{radical}2)R45{degree} structure has line-like features which run parallel to the dislocation double rows of this surface's atomic structure and which expand into 2-D islands upon coarsening.

  7. 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. PMID:24321319

  8. High glass-forming ability correlated with fragility of Mg-Cu(Ag)-Gd alloys

    NASA Astrophysics Data System (ADS)

    Zheng, Qiang; Xu, Jian; Ma, Evan

    2007-12-01

    We report bulk metallic glasses with critical diameter (Dc) in the 20-27mm range over a relatively wide composition range in the Mg-Cu-Ag-Gd quaternary system. Such an extraordinary glass-forming ability is correlated with the relatively strong liquid behavior of these alloys in terms of Angell's [Science 267, 1924 (1995)] fragility concept. The relaxation time of the ternary Mg61Cu28Gd11 and quaternary Mg59.5Cu22.9Ag6.6Gd11 alloys was measured. In terms of the fragility parameter D*, the Mg59.5Cu22.9Ag6.6Gd11 alloy with a critical diameter of 27mm under copper mold casting has a D* of 25, higher than all the bulk metallic glass-forming alloys reported so far. The implications of these findings are discussed.

  9. The Role of Lattice Dynamics on The Thermal Properties of Cu-Ni Alloys

    NASA Astrophysics Data System (ADS)

    Onat, Berk; Durukanoglu, Sondan

    2014-03-01

    We have investigated Cu-Ni alloys with both disorder and order phases in fcc structures to analyze the effect of temperature dependent vibrational thermodynamical properties. The interactions between the atoms in the model systems are defined using an EAM type potential, specifically developed for Cu-Ni alloys. Vibrational thermodynamic functions are determined within the harmonic approximation of lattice dynamics and the vibrational densities of states are calculated using real space Green's function technique. In addition, through ab-initio calculations we have estimated the electronic contributions to set the ground for a comparative discussion. Our results show that the overall characteristics of thermodynamic functions of Cu-Ni alloys of varying concentrations are governed by the lattice vibrations. We will present our results for free energy, heat capacity and entropy of ordered/disordered Cu-Ni alloys with the experimental findings and discuss the electronic, anharmonic and lattice dynamic contributions.

  10. New bulk glassy alloys in Cu-Zr-Ag ternary system prepared by casting and milling

    NASA Astrophysics Data System (ADS)

    Janovszky, D.; Tomolya, K.; Sveda, M.; Solyom, J.; Roosz, A.

    2009-01-01

    The thermal stability, crystallization behaviour and glass forming ability of Cu-Zr-Ag system have been investigated on the basis of a ternary phase diagram. We altered the concentration of the alloys from the Cu58Zr42 to the concentration of the deep eutectic point of the Cu-Zr-Ag ternary system and we calculated the glass forming ability parameters. This paper summerises the results of the procedure during which Cu-Zr-Ag amorphous alloys with different Ag content (0-25%) were prepared by casting and ball-milling. Wedge-shaped samples were prepared from the ingots by centrifugal casting into copper mold. The supercooled liquid region (ΔTx) exceeded 75K. Following the characterization of the cast alloys, master alloys of identical composition were milled in a Fritsch Pulverisette 2 ball-mill. The powders, milled for various periods of time were analysed by XRD in order to define the amorphous fraction.

  11. 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.

  12. Effect of Solute Clusters on Stress Relaxation Behavior in Cu-Ni-P Alloys

    NASA Astrophysics Data System (ADS)

    Aruga, Yasuhiro; Saxey, David W.; Marquis, Emmanuelle A.; Shishido, Hisao; Sumino, Yuya; Cerezo, Alfred; Smith, George D. W.

    2009-12-01

    In this study, the ultrafine structures in Cu-P and Cu-Ni-P alloys have been characterized using a three-dimensional atom probe (3DAP) and transmission electron microscopy (TEM), and the stress relaxation behavior of these alloys has been explored. The results show that low-temperature annealing greatly improved the stress relaxation performance, especially in the Cu-Ni-P alloys. The presence of Ni-P clusters in the Cu-Ni-P alloys has been revealed. The overall improvement in properties has been analyzed in terms of variations in the dislocation density and solute atom cluster density within these materials. It is shown that clusters with small average spacing give rise to significant improvements in the stress relaxation performance, without requiring significant change in the dislocation density.

  13. 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.

  14. 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.

  15. 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.

  16. Enthalpy of mixing of liquid Ni-Zr and Cu-Ni-Zr alloys

    SciTech Connect

    Witusiewicz, V.T.; Sommer, F.

    2000-04-01

    Since the Al-Cu-Ni-Zr system is a basis for the production of bulk amorphous materials by rapid solidification techniques from the liquid state, it is of great scientific interest to determine the partial and the integral thermodynamic functions of liquid and undercooled liquid alloys. Such data, as was pointed out previously, are important in order to understand their extremely good glass-forming ability in multicomponent metallic systems as well as for processing improvements. In order to measure the thermodynamic properties of the Al-Cu-Ni-Zr quaternary, it is necessary to have reliable thermochemical data for its constituent canaries and ternaries first. In a series of articles, the authors have reported in detail the thermodynamic properties of liquid Al-Cu, Al-Ni, Cu-Ni, Cu-Zr, Al-Zr, Al-Cu-Ni, and Al-Cu-Zr alloys. This article deals with the direct calorimetric measurements of the partial and the integral enthalpies of mixing of liquid Ni-Zr and Cu-Ni-Zr alloys and the heat capacity of liquid Ni{sub 26}Zr{sub 74}. In a subsequent article, the authors will present similar data for the liquid ternary Al-Ni-Zr and for the liquid quaternary Al-Cu-Ni-Zr alloys.

  17. 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

  18. 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.

  19. Thermal evolution of short-range order in Cu-Hf-based amorphous alloys

    NASA Astrophysics Data System (ADS)

    Damonte, L. C.; Pasquevich, A. F.; Mendoza-Zélis, L.

    2010-04-01

    A Perturbed Angular Correlation study on melt-spun Cu60Hf20Ti20 and Cu60Hf40 is presented. The influence of Ti addition on thermal stability and crystallization mechanism is followed by differential scanning calorimetry. The evolution of quadrupole parameters with measurement temperature is analyzed in both alloys in order to get insight into the crystallization process. Although an intricate crystallization mechanism is observed for the Ti containing alloy, the final stage is similar, irrespective of minority atom.

  20. 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.

  1. 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.

  2. On the discontinuous precipitation reaction and solute redistribution in a Cu-15%Ni-8%Sn alloy

    SciTech Connect

    Alili, B.; Bradai, D.; Zieba, P.

    2008-10-15

    Optical and transmission electron microscopy studies have been undertaken in order to clarify some morphological aspects of the discontinuous precipitation (DP) reaction in a Cu-15Ni-8Sn (wt.%) alloy in the temperature range 800-950 K. The DP reaction proceeds in the ternary Cu-Ni-Sn system relatively fast (in binary Cu-Ni alloy is not present) with typical morphological features like change of growth direction, appearance and disappearance of solute-rich {gamma} lamellae. A fine continuous precipitation of single Ni and Sn-rich phase was also evidenced within the solute-depleted {alpha} lamellae. An energy-dispersive X-ray analysis showed the level of partitioning of the alloying elements. Most of the Ni and Sn is located in the {gamma} lamellae. However, the formula of the {gamma} lamellae is still close to (Cu{sub 3}Sn), which indicates that some Cu atoms are replaced by Ni.

  3. Growth and characterization of Cu2ZnSnS4 nanostructures using anodized aluminum as the growth mask

    NASA Astrophysics Data System (ADS)

    Chan, C. P.; Chen, Z.; Lam, H.; Surya, C.

    2009-08-01

    In this paper we report the growth and characterization of Cu2ZnSnS4 (CZTS) nanostructures by co-electrodeposition technique using CuCl2, SnCl2 and ZnCl2 as sources and choline-based ionic liquid (IL) as the electrolyte. X-ray diffraction analysis of CZTS thin films grown by this technique indicated that the films have a kesterite structure with preferred grain orientation along (112). It is found that the energy bandgap of the material is about 1.49eV and the optical absorption coefficient is in the order of 104cm-1. Anodized aluminum oxide (AAO) was used as the growth mask for the growth of the nanostructures. Anodization of the aluminum foil was carried out in phosphoric acid solution at 1°C and a potential of 40 to 100V was applied. Sulfurization of the rods was performed in elemental sulfur vapor at 450°C for four hours using N2 as the ambient gas. Experimental results show that nanotubes were formed using the technique and the diameter can be well controlled by varying the applied potential in the anodization process. Electron diffraction experiments show that a mixture of single- and poly-crystalline nanostructures was found.

  4. In vitro study on an antibacterial Ti-5Cu alloy for medical application.

    PubMed

    Ma, Zheng; Li, Mei; Liu, Rui; Ren, Ling; Zhang, Yu; Pan, Haobo; Zhao, Ying; Yang, Ke

    2016-05-01

    Health of human beings is subjected to severe threats from the spread of harmful bacteria and the implant-associated infection remains a serious problem in clinic. In this study, a copper-bearing antibacterial titanium alloy, Ti-5Cu, has been developed for dental and orthopedic implant applications. The microstructure, mechanical property, electrochemical corrosion behavior, in vitro antibacterial performance, cytocompatibility and hemocompatibility of the alloy are systematically investigated. The results reveal that the Ti-5Cu alloy which consists of α-phase matrix and intermetallic compound Ti2Cu not only possesses strong antibacterial activity against both E. coli and S. aureus, but also exhibits better mechanical properties than the commercial pure titanium. It is confirmed that the release of trace amount of Cu ions from the alloy plays an important role in killing bacteria. In spite of the ion release, Ti-5Cu alloy still reveals excellent corrosion resistance. Moreover, good cytocompatibility and superior hemocompatibility make Ti-5Cu alloy to be a potential solution that could prevent the peri-implant infection in dental and orthopaedic applications. PMID:26975748

  5. Effect of Silicon on the Thixoformability of Al-Si-Cu Alloys

    NASA Astrophysics Data System (ADS)

    Benati, Davi Munhoz; Zoqui, Eugênio José

    2014-09-01

    The thixoformability of new Al-Si-Cu alloys was evaluated and characterized by their microstructural and rheological behavior. Alloys Al1Si2.6Cu, Al2Si2.6Cu, Al4Si2.6Cu, and Al7Si2.6Cu were produced with the addition of Al5Ti1B grain refiner alloy. The materials were heat treated under two controlled conditions: holding times of 0, 30, 90, and 210 s and solid fraction of 45 and 60%. The evaluation of the microstructure and semisolid behavior was characterized by globule size, shape factor (SF), minimum stress to flow, maximum stress, and apparent viscosity. The heat treatment times promoted the globularization of solid phase particles to achieve better apparent viscosity results for the alloys treated for 210 s. Both 45 and 60% solid fraction showed no significant differences in terms of SF, but the alloys containing lower solid fraction showed better performance for apparent viscosity. Better working ranges for these new Al-Si-Cu alloys were determined reaching average strain of 0.5 MPa and apparent viscosity of 105 Pa s.

  6. 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.

  7. 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.

  8. X-ray imaging and controlled solidification of Al-Cu alloys toward microstructures by design

    DOE PAGESBeta

    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.; et al

    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. 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.

  9. 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}.

  10. Mechanical properties of Li-Sn alloys for Li-ion battery anodes: A first-principles perspective

    NASA Astrophysics Data System (ADS)

    Zhang, Panpan; Ma, Zengsheng; Jiang, Wenjuan; Wang, Yan; Pan, Yong; Lu, Chunsheng

    2016-01-01

    Fracture and pulverization induced by large stress during charging and discharging may lead to the loss of electrical contact and capacity fading in Sn anode materials. A good understanding of mechanical properties is necessary for their optimal design under different lithiation states. On the basis of first-principles calculations, we investigate the stress-strain relationships of Li-Sn alloys under tension. The results show that the ideal tensile strengths of Li-Sn alloys vary as a function of Li concentration, and with the increase of Li+ concentration, the lowest tensile strength decreases from 4.51 GPa (Sn) to 1.27 GPa (Li7Sn2). This implies that lithiation weakens the fracture resistance of Li-Sn alloys.

  11. 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.

  12. CuZn dendritic alloys: their template-free electrochemical preparation and morphology-dependent wettability.

    PubMed

    Qiao, Ru; Yin, Qiaoqiao; Qiu, Ri; Zhu, Lanlan; Fu, Jianong; Zhang, Xiao Li

    2013-06-01

    In this paper, we report a preparation of CuZn dendritic microstructures through a tunable template-free electrochemical approach. By simply tunning the applied depositing current, the morphology of the product can be well controlled. The growth mechanism of CuZn dendritic alloys was also verified. The experimental results suggest that the growth of the grass-like structures obtained at 5 mA is driven by diffusion limited aggregation, while the driving force of the formation of CuZn dendrites obtained at 10 mA and 15 mA is gas bubbling worked as the dynamic template. The contact angle test shows the modified CuZn dendritic products possess superhydrophobic property. Additionally, through annealing of CuZn alloys in argon as the protective gas, derivative Cu/ZnO composite materials can be produced. PMID:23862481

  13. 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.

  14. Sandwich-Stacked SnO2/Cu Hybrid Nanosheets as Multichannel Anodes for Lithium Ion Batteries.

    PubMed

    Deng, Junwen; Yan, Chenglin; Yang, Lichun; Baunack, Stefan; Oswald, Steffen; Wendrock, Horst; Mei, Yongfeng; Schmidt, Oliver G

    2013-08-27

    We have introduced a facile strategy to fabricate sandwich-stacked SnO2/Cu hybrid nanosheets as multichannel anodes for lithium-ion batteries applying rolled-up nanotechnology with the use of carbon black as intersheet spacer. By employing a direct self-rolling and compressing approach, a much higher effective volume efficiency is achieved as compared to rolled-up hollow tubes. Benefiting from the nanogaps formed between each neighboring sheet, electron transport and ion diffusion are facilitated and SnO2/Cu nanosheet overlapping is prevented. As a result, the sandwich-stacked SnO2/Cu hybrid nanosheets exhibit a high reversible capacity of 764 mAh g(-1) at 100 mA g(-1) and a stable cycling performance of ~75% capacity retention at 200 mA g(-1) after 150 cycles, as well as a superior rate capability of ~470 mAh g(-1) at 1 A g(-1). This synthesis approach presents a promising route to design multichannel anodes for high performance Li-ion batteries. PMID:23879640

  15. Composition effects on the early-stage oxidation kinetics of (001) Cu-Au alloys

    NASA Astrophysics Data System (ADS)

    Zhou, G.-W.; Eastman, J. A.; Birtcher, R. C.; Baldo, P. M.; Pearson, J. E.; Thompson, L. J.; Wang, L.; Yang, J. C.

    2007-02-01

    An in situ environmental transmission electron microscopy study of the nucleation and growth of oxide islands during the early-stage oxidation of (001) Cu1-xAux alloys (x⩽38at.%) was undertaken in order to investigate the effects of alloying on oxide island nucleation behavior and growth kinetics. The kinetic data reveal that Au enhances the nucleation density of oxide islands and suppresses their growth rate. Our results provide insight into reasons for the decreased passivation properties of Cu when alloyed with Au.

  16. Magnetic viscosity in Ni/Cu compositionally-modulated alloys

    SciTech Connect

    Bennett, L.H.; Swartzendruber, L.J.; Ettedgui, H.; Atzmony, U.; Lashmore, D.S; Watson, R.E.; Brookhaven National Lab., Upton, NY )

    1989-01-01

    The existence of a magnetic aftereffect ( magnetic viscosity'') in Ni/Cu multilayered alloys was established using a vibrating sample magnetometer at room temperature and at 86 K. It was shown that the effect is strongly dependent on the step field, H{sub 2} (i.e., the value the field is reduced to after the magnetic moment has been aligned in high field) and exhibits a maximum relaxation rate for values of H{sub 2} around the reverse coercive field, {minus}H{sub c}. Aftereffect behavior of this type has been observed in other materials, though most often for systems composed of superparamagnetic particles, where the relaxation freezes out at low temperatures. In contrast, the relaxation in the CMA was shown to be enhanced at 86 K over its value at room temperature. New measurements over a wider temperature range show that the enhancement in this sample reaches a maximum near 120 K, but below that temperature the relaxation does freeze out. The temperature of maximum enhancement varies from sample to sample. 6 refs.

  17. Preparation and optical properties of silica@Ag Cu alloy core-shell composite colloids

    NASA Astrophysics Data System (ADS)

    Zhang, Jianhui; Liu, Huaiyong; Wang, Zhenlin; Ming, Naiben

    2007-04-01

    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.

  18. 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

    2014-01-01

    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

  19. 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

  20. Controllable Synthesis of Bandgap-Tunable CuSx Se(1-x) Nanoplate Alloys.

    PubMed

    Xu, Jun; Yang, Xia; Yang, Qing-Dan; Huang, Xing; Tang, Yongbing; Zhang, Wenjun; Lee, Chun-Sing

    2015-07-01

    Composition engineering is an important approach for modulating the physical properties of alloyed semiconductors. In this work, ternary CuS(x)Se(1-x) nanoplates over the entire composition range of 0≤x≤1 have been controllably synthesized by means of a simple aqueous solution method at low temperature (90 °C). Reaction of Cu(2+) cations with polysulfide/-selenide ((S(n)Se(m))(2-)) anions rather than independent S(n)(2-) and Se(m)(2-) anions is responsible for the low-temperature and rapid synthesis of CuS(x)Se(1-x) alloys, and leads to higher S/Se ratios in the alloys than that in reactants owing to different dissociation energies of the Se-Se and the S-S bonds. The lattice parameters 'a' and 'c' of the hexagonal CuS(x)Se(1-x) alloys decrease linearly, whereas the direct bandgaps increase quadratically along with the S content. Direct bandgaps of the alloys can be tuned over a wide range from 1.64 to 2.19 eV. Raman peaks of the S-Se stretching mode are observed, thus further confirming formation of the alloyed CuS(x)Se(1-x) phase. PMID:25864726

  1. 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. PMID:27612729

  2. 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.

  3. 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. PMID:27612770

  4. Characterization of Cu-Zn Alloy Nanocrystalline Powders Prepared by Wire Electrical Explosion

    NASA Astrophysics Data System (ADS)

    Qun, Wang; Hai-Bin, Yang; Wei-Li, Guo; Guang-Tian, Zou

    2000-02-01

    Nanocrystalline powders of Cu-Zn alloy in size ranging from 10 to 140 nm was prepared from α-Cu-Zn alloy wire containing 39.8 at.% Zn by an electrical explosion method. The particles are identified from x-ray diffraction as a mixture of the α, β, γ, and ɛ phases of Cu-Zn alloy. Most of the particles are hexagonal in shape, with only a small part being spherical and cubic. The composition of Zn in the explosion products varied from 6.9 to 45.2 at.% in different particles as determined by energy dispersive x-ray spectrometer. A possible mechanism for the formation of the alloy nanocrystalline powders is proposed, in which a redistribution process occurred caused by strong collision and diffusion between the two kinds of atoms during the powder formation.

  5. Crystal nucleation in amorphous (Au/100-y/Cu/y/)77Si9Ge14 alloys

    NASA Technical Reports Server (NTRS)

    Thompson, C. V.; Greer, A. L.; Spaepen, F.

    1983-01-01

    Because, unlike most metallic glasses, melt-spun alloys of the series (Au/100-y/Cu/y/)77Si9Ge14 exhibit well separated glass transition and kinetic crystallization temperatures, crystallization can be studied in the fully relaxed amorphous phase. An isothermal calorimetric analysis of the devitrification kinetics of the amorphous alloy indicates sporadic nucleation and a constant growth rate. It is found for the cases of alloys with y values lower than 25 that the classical theory of homogeneous nucleation is consistent with observations, including transient effects. An analysis of the crystallization kinetics shows that slow crystal growth rates play an important role in glass formation in these alloys. Although the reduced glass transition temperature increases with Cu content, glass formation is more difficult at high Cu contents, perhaps because of a difference in nucleus composition.

  6. 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.

  7. Copper Removal from Hypereutectic Cu-Si Alloys by Heavy Liquid Media Separation

    NASA Astrophysics Data System (ADS)

    Mitrašinović, Aleksandar M.; Utigard, Torstein A.

    2012-04-01

    A high-capacity method for silicon refining is investigated. The biggest obstacle in Si refining using the alloying technique is the amount of solute element. In the current work, Cu is removed from two Cu-Si hypereutectic alloys by the heavy liquid media separation technique. The results indicated 86.0 pct silicon recovered, which is close to the theoretical limit. The chemical analysis showed a Cu concentration of 0.68 wt pct in the 50 Cu-Si alloy for a 75- μm average particle size after heavy liquid media separation. The optimal particle size was found in the range of 75 to 125 μm. Heavy liquid media separation is an efficient technique in the process of liberating Si dendrites that can be used as feedstock in solar cell applications.

  8. 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.

  9. 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.

  10. 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. PMID:27612819

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  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. Influence of sodium borate concentration on properties of anodic coatings obtained by micro arc oxidation on magnesium alloys

    NASA Astrophysics Data System (ADS)

    Zhang, R. F.; Zhang, S. F.; Shen, Y. L.; Zhang, L. H.; Liu, T. Z.; Zhang, Y. Q.; Guo, S. B.

    2012-06-01

    The influence of sodium borate concentration on the formation and properties of anodic coatings obtained by micro arc oxidation (MAO) on magnesium alloys was systematically studied in an alkaline solution with addition of 0-40 g/L sodium borate. It is shown that sodium borate can decrease the solution conductivity, take part in the coating formation and increase the coating thickness. With the increase of sodium borate concentration, the boron content in the coatings increases in the range of 10-20 g/L but decreases within the range of 20-40 g/L. Sodium borate cannot further improve the corrosion resistance attributed to the development of porous or rough anodic coatings.

  17. Solidification Paths and Phase Components at High Temperatures of High-Zn Al-Zn-Mg-Cu Alloys with Different Mg and Cu Contents

    NASA Astrophysics Data System (ADS)

    Shu, W. X.; Hou, L. G.; Liu, J. C.; Zhang, C.; Zhang, F.; Liu, J. T.; Zhuang, L. Z.; Zhang, J. S.

    2015-11-01

    Studies were carried out systematically on a series of Al-8.5 wt pct Zn- xMg- yCu alloys ( x is about 1.5, 2.0, and 2.5 wt pct, and y is about 1.5, 2.0, 2.5, and 2.9 wt pct). The effects of alloying elements Mg and Cu on the microstructures of as-cast and homogenized alloys were investigated using the computational/experimental approach. It shows that Mg(Zn,Al,Cu)2 ( σ) phase can exist in all the as-cast alloys without any observable Mg32(Al,Zn)49/Al2Mg3Zn3 ( T) or Al2CuMg ( S) phase, whereas Al2Cu ( θ) phase is prone to exist in the alloys with low Mg and high Cu contents. Thermodynamic calculation shows that the real solidification paths of the designed alloys fall in between the Scheil and the equilibrium conditions, and close to the former. After the long-time homogenization [733 K (460 °C)/168 hours] and the two-step homogenization [733 K (460 °C)/24 hours + 748 K (475 °C)/24 hours], the phase components of the designed alloys are generally consistent with the calculated phase diagrams. At 733 K (460 °C), the phase components in the thermodynamic equilibrium state are greatly influenced by Mg content, and the alloys with low Mg content are more likely to be in single-Al phase field even if the alloys contain high Cu content. At 748 K (475 °C), the dissolution of the second phases is more effective, and the phase components in the thermodynamic equilibrium state are dominated primarily by (Mg + Cu) content, except the alloys with (Mg + Cu) ≳ 4.35 wt pct, all designed alloys are in single-Al phase field.

  18. Effects of alloying 30 at. % Ni using a Cu catalyst on the growth of bilayer graphene

    NASA Astrophysics Data System (ADS)

    Lee, Wan-Gyu; Kim, Eunho; Jung, Jongwan

    2012-12-01

    A small percentage graphene bilayer where the first layer was fully covered with a graphene sheet was grown on alloy foils via an inductively coupled plasma-chemical vapor deposition chamber. Compared with Cu foils, the alloy foils led to faster growth of the graphene film, while maintaining the same quality, homogeneity, and thickness uniformity over the whole area synthesized as the growth characteristics of a monolayer graphene grown on Cu. Moreover, the combined catalyst had a graphene film simultaneously grown with a metallic compound of magnesium silicate in some regions and of 200 nm Cu2.4S in other regions. Nevertheless, graphene was grown continuously and highly homogenously over the entire large area synthesized without boundaries between regions. Thus the resulting graphene growth is affected primarily by the Cu catalyst and partly by the Ni and that the quality of the graphene is dependent on the Cu catalyst.

  19. Ion beam mixing in binary amorphous metallic alloys. [Cu-Er; Ni-Ti

    SciTech Connect

    Hahn, H.; Averback, R.S.; Diaz de la Rubia, T.; Okamoto, P.R.

    1985-12-01

    Ion beam mixing (IM) was measured in homogeneous amorphous metallic alloys of Cu-Er and Ni-Ti as a function of temperature using tracer impurities, i.e., the so-called ''marker geometry''. In Cu-Er, a strong temperature dependence in IM was observed between 80 and 373K, indicating that radiation-enhanced diffusion mechanisms are operative in this metallic glass. Phase separation of the Cu-Er alloy was also observed under irradiation as Er segregated to the vacuum and SiO2 interfaces of the specimen. At low-temperatures, the amount of mixing in amorphous Ni-Ti is similar to that in pure Ni or Ti, but it is much greater in Cu-Er than in either Cu or Er.

  20. 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

  1. 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. PMID:26914329

  2. The Surface Dynamics of the Initial Oxidation Behavior of CuNi Alloys

    NASA Astrophysics Data System (ADS)

    Ziemack, Steve; Sun, Li; Yang, Judith; Eastman, Jeff; Zhou, Guangwen

    2009-03-01

    As an extension of our previous work on the initial oxidation stages of pure Cu and CuAu alloy, we are currently visualizing the oxidation of CuNi alloys by in-situ ultra high vacuum transmission electron microscope (UHV-TEM) and X-ray diffraction. We investigated systematically a range of CuNi (001) compositions, including 2,8,15 and 24 at%Ni at P (O2) =5x10-4 torr and T=500-700^oC. The initial oxidation behavior is similar to that of Cu (001) AND CuAu (001), where oxide islands rapidly nucleate, grow and coalesce. However, remarkable differences exist: 1) a second rapid nucleation of compact and dense oxide islands occurred and 2) polycrystalline oxides formed, where only cube-on-cube epitaxial Cu2O islands nucleated on Cu (001) and CuAu (001) for all temperature and pressures studied. The surface segregation behavior of Cu and Ni may explain these surprising results.

  3. Three-dimensional SnO2/carbon on Cu foam for high-performance lithium ion battery anodes.

    PubMed

    Chen, Weimin; Maloney, Scott; Wang, Wenyong

    2016-10-14

    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. PMID:27587237

  4. 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.

  5. Crystallization behavior and magnetic properties in High Fe content FeBCSiCu alloy system

    NASA Astrophysics Data System (ADS)

    Fan, X. D.; Shen, B. L.

    2015-07-01

    High Fe content FeBCSiCu nanocrystalline alloys are prepared by annealing melt-spun amorphous ribbons with aim at increasing saturation magnetic flux density. Microstructures identified by XRD and TEM reveal that Cu addition inhibits the surface crystallization of Fe86B7C7 alloy and improve its glass-forming ability. Activation energy of crystallization calculated by Kissinger's equation indicates that both Cu and Si addition promotes the precipitation of α-Fe phase and improves the thermal stability. VSM and DC B-H loop tracer measurements show that the Fe85.5B7C6Si1Cu0.5 nanocrystalline alloy exhibits high saturation magnetic flux density of 1.8 T and low coercivity of 10 A/m, respectively. AC properties measured by AC B-H analyzer show this alloy exhibits low core loss of 0.35 W/kg at 1 T at 50 Hz. Low material cost and convenient productivity make the Fe85.5B7C6Si1Cu0.5 nanocrystalline alloy an economical application in industry.

  6. 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.

  7. 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.

  8. Electroslag surfacing of steel shafting with Ni alloy 625 and 70Cu-30Ni strip

    SciTech Connect

    Devletian, J.H.; Gao, Y.P.; Wood, W.E.

    1996-12-31

    A comprehensive study of electroslag surfacing (ESS) of steel with Ni Alloy 625 and 70Cu-30Ni strip electrodes was conducted to establish the feasibility of replacing forged bearing sleeves on propulsion shafting with integral weld surfacing. The base material was MIL-S-23284, Class 1 steel in the form of 41--66 cm (16--26 in.) diameter shafting and 76 mm (3 in.) thick flat plate. All ESS was carried out at a heat input level of approximately 5.9kJ/mm (150 kJ/in.) using 30 x 0.5 mm (1.2 x 0.02 in.) strip electrodes. Assessments of mechanical properties and microstructure of Ni Alloy 625 surfacing and 70Cu-30Ni surfacing were conducted to establish the structure-property relationships in these complex alloy systems. In addition, a solidification cracking test was developed to determine the relative cracking susceptibilities of these strip surfacing alloys. Although the Ni Alloy 625 surfacing contained small islands of interdendritic MC type carbides and Laves phase, the mechanical properties of this surfacing were satisfactory. The 70Cu-30Ni surfacing required a buttering layer of 30Cu-70Ni or pure Ni to prevent solidification cracking. The inherent ductility-dip sensitivity of 70Cu-30Ni surfacing was overcome by the development of a suitable ESS procedure.

  9. Effect of Cr and Cu addition on corrosion behavior of Ni-Ti alloys.

    PubMed

    Iijima, M; Endo, K; Ohno, H; Mizoguchi, I

    1998-03-01

    The corrosion behavior of three Ni-Ti alloys with compositions as commercial super-elastic orthodontic wires was investigated using polished plate specimens. Corrosion resistance was estimated by potentiodynamic polarization measurement in 0.9% NaCl and 1% lactic acid solutions and analysis of released metals by atomic absorption spectrophotometry. The influence of Cr and Cu addition on the structure of the surface oxide film was examined by X-ray photoelectron spectroscopy (XPS). Addition of 0.19 at% Cr had little effect on the structure of the oxide films and the corrosion resistance of the Ni-Ti alloys. For Ni-Ti-5Cu-0.3Cr alloy, the metallic Cu was enriched at the alloy/oxide film interface, resulting in increased susceptibility to pitting corrosion above +1000 mV. However, the passive current density and the amount of released Ni were not significantly increased by the addition of Cu. The study showed that small amounts of Cr and Cu added to change the super-elastic characteristics do not change the corrosion resistance of the Ni-Ti alloy freely immersed in simulated physiological environments. PMID:9663060

  10. CONSTITUTIVE BEHAVIOR OF AS-QUENCHED Al-Cu-Mn ALLOY

    NASA Astrophysics Data System (ADS)

    Yang, Xia-Wei; Zhu, Jing-Chuan; Nong, Zhi-Sheng; Ye, Mao; Lai, Zhong-Hong; Liu, Yong

    2013-07-01

    The hot flow stress of as-quenched Al-Cu-Mn alloy was modeled using the constitutive equations. The as-quenched Al-Cu-Mn alloy were treated with isothermal hot compression tests in the temperature range of 350-500°C, the strain rate range of 0.001-1 s-1. The hyperbolic sine equation was found to be appropriate for flow stress modeling and prediction. Based on the hyperbolic sine equation, a constitutive equation is a relation between 0.2 pct yield stress and deformation conditions (strain rate and deformation temperature) was established. The corresponding hot deformation activation energy (Q) for as-quenched Al-Cu-Mn alloy was determined to be 251.314 kJ/mol. Parameters of constitutive equation of as-quenched Al-Cu-Mn alloy were calculated at different small strains (≤ 0.01). The calculated flow stresses from the constitutive equation are in good agreement with the experimental results. Therefore, this constitutive equation can be used as an accurate temperature-stress model to solve the problems of quench distortion of Al-Cu-Mn alloy parts.

  11. 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.

  12. Cu3 V2 O8 Nanoparticles as Intercalation-Type Anode Material for Lithium-Ion Batteries.

    PubMed

    Li, Malin; Gao, Yu; Chen, Nan; Meng, Xing; Wang, Chunzhong; Zhang, Yaoqing; Zhang, Dong; Wei, Yingjin; Du, Fei; Chen, Gang

    2016-08-01

    Cu3 V2 O8 nanoparticles with particle sizes of 40-50 nm have been prepared by the co-precipitation method. The Cu3 V2 O8 electrode delivers a discharge capacity of 462 mA h g(-1) for the first 10 cycles and then the specific capacity, surprisingly, increases to 773 mA h g(-1) after 50 cycles, possibly as a result of extra lithium interfacial storage through the reversible formation/decomposition of a solid electrolyte interface (SEI) film. In addition, the electrode shows good rate capability with discharge capacities of 218 mA h g(-1) under current densities of 1000 mA g(-1) . Moreover, the lithium storage mechanism for Cu3 V2 O8 nanoparticles is explained on the basis of ex situ X-ray diffraction data and high-resolution transmission electron microscopy analyses at different charge/discharge depths. It was evidenced that Cu3 V2 O8 decomposes into copper metal and Li3 VO4 on being initially discharged to 0.01 V, and the Li3 VO4 is then likely to act as the host for lithium ions in subsequent cycles by means of the intercalation mechanism. Such an "in situ" compositing phenomenon during the electrochemical processes is novel and provides a very useful insight into the design of new anode materials for application in lithium-ion batteries. PMID:27356500

  13. Anodic behavior of alloys in the systems aluminum-scandium(yttrium, praseodymium, neodymium) in a neutral medium

    SciTech Connect

    Ganiev, I.N.; Yunusov, I.; Krasnoyarskii, V.V.

    1988-03-10

    The authors investigated the influence of scandium, yttrium, praseodymium, and neodymium on the anodic behavior of aluminum in a 3% sodium chloride solution by a potentiodynamic method which provided information over a time interval during which the state of the electrode surface and the composition of the solution remained essentially unchanged. Data were derived for electrochemical and pitting corrosion for different alloy contents and compositions. Results were analyzed for aluminum-scandium, aluminum-yttrium, aluminum-praseodymium, and aluminum-neodymium binary systems.

  14. 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.

  15. 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).

  16. Dissolution of Precipitates During Solution Treatment of Al-Mg-Si-Cu Alloys

    NASA Astrophysics Data System (ADS)

    Zhang, Xukai; Guo, Mingxing; Zhang, Jishan; Zhuang, Linzhong

    2016-02-01

    A model combining classical diffusion-controlled dissolution equation for a single spherical particle and Johnson-Mehl-Avrami-like equation is used to deal with dissolution process for different kinds of precipitations (Si, Mg2Si, Q(Al1.9Mg4.1Si3.3Cu)) in Al-Mg-Si-Cu alloys. The results reveal that the dissolution time of precipitates increases with increasing their sizes and solute concentrations in the alloy matrix; for the same size and concentration, their dissolution times follow Si > Q(Al1.9Mg4.1Si3.3Cu) > Mg2Si. Two precipitates (Mg2Si and Al1.9Mg4.1Si3.3Cu) with a size of about 700 nm were obtained in a cold rolled Al-Mg-Si-Cu-Zn alloy, and the complete dissolution time is about 15 seconds, which is basically the same as the calculated time by the developed model. The theoretical prediction of dissolution time can be greatly used to design solution treatment and thermomechanical processing parameters of Al-Mg-Si-Cu alloys.

  17. Novel PdAgCu ternary alloy: Hydrogen permeation and surface properties

    NASA Astrophysics Data System (ADS)

    Tarditi, Ana M.; Braun, Fernando; Cornaglia, Laura M.

    2011-05-01

    Dense PdAgCu ternary alloy composite membranes were synthesized by the sequential electroless plating of Pd, Ag and Cu on top of both disk and tubular porous stainless steel substrates. X-ray diffraction and scanning electron microscopy were employed to study the structure and morphology of the tested samples. The hydrogen permeation performance of these membranes was investigated over a 350-450 °C temperature range and a trans-membrane pressure up to 100 kPa. After annealing at 500 °C in hydrogen stream followed by permeation experiments, the alloy layer presented a FCC crystalline phase with a bulk concentration of 68% Pd, 7% Ag and 25% Cu as revealed by EDS. The PdAgCu tubular membrane was found to be stable during more than 300 h on hydrogen stream. The permeabilities of the PdAgCu ternary alloy samples were higher than the permeabilities of the PdCu alloy membranes with a FCC phase. The co-segregation of silver and copper to the membrane surface was observed after hydrogen permeation experiments at high temperature as determined by XPS.

  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. 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.

  20. 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.

  1. 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.

  2. Effects of half-wave and full-wave power source on the anodic oxidation process on AZ91D magnesium alloy

    NASA Astrophysics Data System (ADS)

    Wang, Ximei; Zhu, Liqun; Li, Weiping; Liu, Huicong; Li, Yihong

    2009-03-01

    Anodic films have been prepared on the AZ91D magnesium alloys in 1 mol/L Na 2SiO 3 with 10 vol.% silica sol addition under the constant voltage of 60 V at room temperature by half-wave and full-wave power sources. The weight of the anodic films has been scaled by analytical balance, and the thickness has been measured by eddy current instrument. The surface morphologies, chemical composition and structure of the anodic films have been characterized by scanning electron microscopy (SEM), energy dispersion spectrometry (EDS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the thickness and weight of the anodic films formed by the two power sources both increase with the anodizing time, and the films anodized by full-wave power source grow faster than that by half-wave one. Furthermore, we have fitted polynomial to the scattered data of the weight and thickness in a least-squares sense with MATLAB, which could express the growth process of the anodic films sufficiently. The full-wave power source is inclined to accelerate the growth of the anodic films, and the half-wave one is mainly contributed to the uniformity and fineness of the films. The anodic film consists of crystalline Mg 2SiO 4 and amorphous SiO 2.

  3. 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.

  4. 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.

  5. Laser Controllable Growth of Graphene via Ni-Cu Alloy Composition Modulation

    NASA Astrophysics Data System (ADS)

    Ye, Xiaohui; Lin, Zhe; Zhang, Hongjun; Zhu, Hongwei; Zhong, Minlin

    2015-12-01

    Graphene has many unique properties, most of them strongly depend on the number of layers. It is significant to develop a facile approach to realize the controllable growth of graphene with specific number of layers. We ever reported an efficient approach to grow graphene rapidly and locally by laser irradiation. In this work, we offers yet another important feature, to control the number of layers of graphene. Ni-Cu alloy has been reported to be used successfully as the catalyst for graphene growth with controllable number of layers. In that case, the Ni-Cu alloys with different compositions were normally formed by thermal evaporation. Here we provide an efficient way to fabricate the Ni-Cu alloy catalysts by laser cladding. Then the high power laser was employed to melt the Ni and Cu mixed powders. Different Ni-Cu alloy catalysts were formed in a high rate of 720 mm2/min with a thickness of 1.2 mm. Then the graphene with controllable layers was rapidly and locally grown on the Ni-Cu catalysts by laser irradiation at a high rate (18 cm2/min) at room temperature. We found that the Ni-Cu catalyst with 15 % Cu could be helpful to grow single layer graphene, which occupied 92.4 % of the entire film. Higher Cu content didn't promote the growth due to the oxygen involved during the growth process. The controllable growth mechanism of graphene by laser processing was discussed. Combining the rapid catalyst fabrication and graphene synthesis make it a cost- and time-efficient method to produce the controllable graphene films.

  6. 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. PMID:25971100

  7. Bulk glassy Cu-based alloys with a large supercooled liquid region of 110 K

    NASA Astrophysics Data System (ADS)

    Inoue, Akihisa; Zhang, Wei

    2003-09-01

    The replacement of Cu by 5%Ag for Cu50Hf45Al5 glassy alloy was found to increase significantly the stability of supercooled liquid against crystallization. The supercooled liquid region reached as large as 110 K for Cu45Hf45Al5Ag5. The extension of the supercooled liquid region is due to an increase in the crystallization temperature, accompanying the change in the primary crystalline phases. The effectiveness of Ag addition was interpreted to result from the retardation of long-range atomic rearrangements for the progress of crystallization reaction. The selection of the quaternary composition enabled us to form bulk glassy alloys with diameters up to 3 mm. The Young's modulus and compressive fracture strength of the 5%Ag-containing alloy are 119 GPa and 2220 MPa, respectively.

  8. Brazeability of a 3003 Aluminum alloy with Al-Si-Cu-based filler metals

    NASA Astrophysics Data System (ADS)

    Tsao, L. C.; Weng, W. P.; Cheng, M. D.; Tsao, C. W.; Chuang, T. H.

    2002-08-01

    Al-Si-Cu-based filler metals have been used successfully for brazing 6061 aluminum alloy as reported in the authors’ previous studies. For application in heat exchangers during manufacturing, the brazeability of 3003 aluminum alloy with these filler metals is herein further evaluated. Experimental results show that even at such a low temperature as 550 °C, the 3003 alloys can be brazed with the Al-Si-Cu fillers and display bonding strengths that are higher than 77 MPa as well. An optimized 3003 joint is attained in the brazements with the innovative Al-7Si-20Cu-2Sn-1Mg filler metal at 575 °C for 30 min, which reveals a bonding strength capping the 3003 Al matrix.

  9. 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

  10. 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.

  11. SDAS, Si and Cu Content, and the Size of Intermetallics in Al-Si-Cu-Mg-Fe Alloys

    NASA Astrophysics Data System (ADS)

    Sivarupan, Tharmalingam; Taylor, John Andrew; Cáceres, Carlos Horacio

    2015-05-01

    Plates of Al-(a)Si-(b)Cu-Mg-(c)Fe alloys with varying content of (mass pct) Si ( a = 3, 4.5, 7.5, 9, 10, or 11), Cu ( b = 0, 1, or 4), and Fe ( c = 0.2, 0.5 or 0.8) were cast in sand molds with a heavy chill at one end to ensure quasi-directional solidification over a wide range of Secondary Dendrite Arm Spacing (SDAS). Statistical analysis on the size of the β-Al5FeSi, α-Al8Fe2Si, or Al2Cu intermetallics on Backscattered Electron images showed that a high Si content reduced the size of the β platelets in alloys with up to 0.5 Fe content regardless of the SDAS, whereas at small SDAS the refining effect extended up to 0.8 Fe, and involved α-phase intermetallics which replaced the beta platelets at those concentrations. At low Si contents, a high Cu level appeared to have similar refining effects as increased Si, through the formation of α-phase particles in the post-eutectic stage which agglomerated with the Al2Cu intermetallics. A high content of Si appears to make the overall refining process less critical in terms of SDAS/cooling rate.

  12. Correlation between the wear resistance of Cu-Ni alloy and its electron work function

    NASA Astrophysics Data System (ADS)

    Huang, X. C.; Lu, H.; He, H. B.; Yan, X. G.; Li, D. Y.

    2015-12-01

    This article reports our studies on the performance of isomorphous Cu-Ni alloy during sliding and erosive wear processes with attempt to correlate its wear behaviour with the electron work function (EWF). EWF, mechanical behaviour and wear resistance of the Cu-Ni alloy with respect to the concentration of Ni were measured using ultraviolet photoelectron spectroscopy, micro-indenter, pin-on-disc and air-jet testers, respectively. It was demonstrated that EWF, hardness and Young's modulus of the alloy increased as the concentration of Ni increased. During solid-particle erosion tests, the wear resistance of the alloy was enhanced with an increase in the Ni concentration, corresponding to an increase in EWF. However, an opposite trend was observed during sliding wear tests, which was ascribed to the formation of oxide scale that affected the sliding wear resistance.

  13. Superelastic Deformation in Polycrystalline Fe-Ni-Co-Ti-Cu Alloys

    NASA Astrophysics Data System (ADS)

    Titenko, Anatoliy N.; Demchenko, Lesya D.

    2012-12-01

    This article presents the deformation behavior of aged ferromagnetic alloys of Fe-Ni-Co-Ti-Cu system caused by phase transitions. The basic characteristic temperatures of martensitic transformation (MT) of the alloys were determined from temperature dependences of low-field magnetic susceptibility. The coefficients of thermal expansion of high- and low-temperature phases, as well as values of volume effect were obtained from dilatometric data. Peculiarities of deformation behavior were studied from the analysis of stress-strain curves, registered at uniaxial tension. It was found that investigated alloys have a substantial superelastic deformation and a low value of the temperature hysteresis of MT with the volume effect of 2%, which is typical for thermoelastic alloys of Fe-Ni-Co-Ti-Cu system.

  14. 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.

  15. 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.

  16. Cu-Ni nano-alloy: mixed, core-shell or Janus nano-particle?

    NASA Astrophysics Data System (ADS)

    Guisbiers, Grégory; Khanal, Subarna; Ruiz-Zepeda, Francisco; Roque de La Puente, Jorge; José-Yacaman, Miguel

    2014-11-01

    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.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. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr05739b

  17. Grain growth behavior of Pb-Cu-Te cable sheathing alloys

    SciTech Connect

    Sahay, S.S.; Guruswamy, S.; Goodwin, F.

    1995-04-01

    Lead alloys are extensively used as sheathing material for power and telecommunication cables. Excellent extrusion properties, high ductility, extremely low recrystallization temperature, good fatigue and creep resistance, make these alloys ideal for cable sheathing application. Though the thickness of the lead sheath is only a few hundred {mu}m, it is a critical component of the cable. The lead layer in the cable is often the limiting factor both during the cable production and during its service phase. Up to several hundred miles of long single piece cables may be required for underground and underwater cables. Cracking in the lead sheath during the cable sheathing extrusion limits the production of such long cables while cracking of the lead sheath due to repeated vibration, creep and recrystallization limits the service life of these cables. The purpose of the present research is to increase the duration of cable extrusion time without compromising sheath integrity by minimizing deleterious precipitate formation and growth. Concentrations of Cu and Te in the commercial alloy are too small to contribute to precipitation strengthening. Therefore their positive influence on mechanical strength should mainly result from the influence of Cu and Te in solution on interdiffusivity and grain boundary mobility. The formation of large precipitates observed in Pb-Cu-Te alloys can be minimized and extrusion times increased without negatively affecting mechanical properties if the solute content is reduced to near solid solubility levels. In order to examine the effect of lowering solute content on microstructural stability and mechanical properties, compressive stress-strain behavior of a Pb-50 wt ppm Cu-100 wt ppm Te alloy with solute contents close to the solubility limits and a Pb-400 wt ppm Cu-400 wt ppm Te alloy was examined at room temperature. The grain growth kinetics in these alloys were studied in a temperature range of 100 to 225 C.

  18. Intergranular fracture in an Al-Li-Cu-Mg-Zr alloy

    SciTech Connect

    Wert, J.A.; Lumsden, J.B.

    1985-02-01

    The intergranular fracture characteristics of the Al-Li-Cu-Mg-Zr alloy is studied for underaged (170 C/4 hr) and overaged (230 C/4 hr) conditions. In addition, extensive intergranular fracture parallel to the tensile axis (delamination) in longitudinal tensile specimens is found together with equal concentration of K on all intergranular fracture surfaces independent of aging treatment. K is believed to promote intergranular fracture in Al-Li alloys similarly to a Na presence. 7 references.

  19. 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.

  20. 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

  1. Influence of carbon nanotube on the structure evolution of Ni-Cu alloy nanorod

    NASA Astrophysics Data System (ADS)

    Guo, J.-Y.; Xu, C.-X.; Yang, C.; Dai, J.; Li, Z.-H.

    2011-02-01

    A Monte Carlo method has been performed to simulate the structure evolution of Ni-Cu alloy nanorods encapsulated in the carbon nanotube and removed from the carbon nanotube. The Sutton-Chen many-body potential and Lennard-Jones potential are used to describe the metal-metal and metal-carbon interactions, respectively. The studies show that all Ni-Cu atoms in carbon nanotube are arranged in a series of concentric cylindrical layers even they have different fractions, and Cu atoms are apt to stay at the surface layers. If the carbon nanotube was removed, Ni-Cu alloy nanorod would turn into a cluster with nickel core and copper shell. The physical origin for such structure formation and evolution toward core-shell motifs are discussed. The bond pair analysis shows that the nanorods and clusters are amorphous structures dominated by the rhombohedral structure and mixed up with some local short-range order.

  2. 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.

  3. Self-Formed Barrier with Cu-Mn alloy Metallization and its Effects on Reliability

    SciTech Connect

    Koike, J.; Wada, M.; Usui, T.; Nasu, H.; Takahashi, S.; Shimizu, N.; Yoshimaru, M.; Shibata, H.

    2006-02-07

    Advancement of semiconductor devices requires the realization of an ultra-thin (less than 5 nm thick) diffusion barrier layer between Cu interconnect and insulating layers. Self-forming barrier layers have been considered as an alternative barrier structure to the conventional Ta/TaN barrier layers. The present work investigated the possibility of the self-forming barrier layer using Cu-Mn alloy thin films deposited directly on SiO2. After annealing at 450 deg. C for 30 min, an amorphous oxide layer of 3-4 nm in thickness was formed uniformly at the interface. The oxide formation was accompanied by complete expulsion of Mn atoms from the Cu-Mn alloy, leading to a drastic decrease in resistivity of the film. No interdiffusion was observed between Cu and SiO2, indicating an excellent diffusion-barrier property of the interface oxide.

  4. Unidirectional solidification of Zn-rich Zn-Cu peritectic alloys -- 2. Microstructural length scales

    SciTech Connect

    Ma, D.; Li, Y.; Ng, S.C.; Jones, H.

    2000-05-11

    Experimental results are presented of solidification microstructure length scale including {eta}-phase cell spacing, primary {epsilon} secondary dendrite arm spacing, size of nonaligned dendrite of primary {epsilon}, and volume fraction of primary {epsilon}, as functions of alloy concentration (containing up to 7.37 wt% Cu) and growth velocity (ranging from 0.02 to 4.82 mm/s) in the unidirectional solidification of Zn-rich Zn-Cu peritectic alloys. Intercellular spacing ({lambda}) of two-phase cellular structure decreases with increasing growth velocity (V) such that {lambda}V{sup 1/2} is constant at a fixed alloy concentration in parametric agreement with the KGT and Hunt-Lu models. The value of {lambda}V{sup 1/2} varies from 216 {+-} 10 to 316 {+-} 55 {micro}m{sup 3/2}/s{sup 1/2} with decrease in alloy concentration from 4.94 to 2.17 wt% Cu. These values are much greater than for normal eutectic systems but comparable with monotectic alloys. Dendritic secondary arm spacing ({lambda}{sub 2}) of primary {epsilon} decreases with increasing V such that {lambda}{sub 2}V{sup 1/3} is constant ranging 14.9 {+-} 0.9 to 75.6 {+-} 8.1 {micro}m{sup 4/3}/s{sup 1/3} with increase in alloy concentration (C{sub 0}) from 2.17 to 7.37 wt% Cu, which is in parametric agreement with predictions of arm-coarsening theory. The volume fraction (f{sub e}) of primary {epsilon} increases with increasing V for Zn-rich Zn-3.37, 4.94 and 7.37 wt% Cu hyperperitectic alloys. Predictions of the Scheil and Sarreal-Abbaschian models show good agreement with the observed f{sub {epsilon}} for Zn-4.94 wt% Cu at moderate V from 0.19 to 2.64 mm/s, but fail at low V of less than 0.16 mm/s and at high V of greater than 3.54 mm/s. The measured average size, {Lambda}V{sup 1/2} is constant for a given alloy, increasing from (0.98 {+-} 0.04) x 10{sup 3} to (7.2 {+-} 0.7) x 10{sup 3} {micro}m{sup 3/2}/s{sup 1/2} with increase in alloy concentration from 2.17 to 4.94 wt% Cu.

  5. 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.

  6. 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.

  7. The structure of a commercial dental Ag-Pd-Cu-Au casting alloy.

    PubMed

    Niemi, L; Herø, H

    1984-02-01

    The structure of a commercial dental Ag-Pd-Cu-Au casting alloy has been studied by microprobe and X-ray diffraction analyses after various heat treatments. The composition of phases in equilibrium was established. After being annealed at 400 degrees C, 500 degrees C, and 600 degrees C for seven wk, the alloy consisted of three phases: a Cu- and Pd-rich fee phase (alpha 1) with alpha = 0.372nm, a Ag-rich matrix (alpha 2) with alpha = 0.399nm, and an ordered CsCl-type bcc PdCu phase with alpha = 0.296nm. The PdCu phase was not observed above 600 degrees C, and the proportion of the alpha 1 phase decreased sharply above 700 degrees C. After being annealed at 900 degrees C, the alloy matrix was partly decomposed at the Cu-enriched grain boundaries. The decomposed areas grew into the grain interior during subsequent precipitation hardening. No segregation of Au was detected after casting, and the element was evenly distributed throughout the alloy structure after all heat treatments. PMID:6582096

  8. Local Structures of Mechanically Alloyed Al70Cu20Fe10 Nanocomposites Studied by XRD and XAFS

    SciTech Connect

    Yin Shilong; Qian Liying; He Bo; Zou Shaobo; Wei Shiqiang; Bian Qing

    2007-02-02

    Ternary Al70Cu20Fe10 alloy nano-composites prepared by mechanical alloying are characterized by X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS). The results indicate that after milled for 10 hours, the coordination environment around Cu atoms is changed largely and becomes disordered, but the local structure of Fe atoms still remains as that of {alpha}-Fe. This indicates the forming of inter-metallic compound Al2Cu with body center cubic structure. Even if the milling time is extended to 40 hours, only small amount of {alpha}-Fe can be alloyed to produce Al-Fe-Cu alloy. However, the annealing treatment at 700 deg. C can drive the {alpha}-Fe to incorporate into the Al2Cu compound to form an icosahedral alloy phase.

  9. Effect of trace organic compounds on the corrosion of Cu/Ni alloys in sulfide polluted seawater

    SciTech Connect

    Reda, M.R.; Al-Hajji, J.N. )

    1993-05-01

    Trace organic complexing agents were investigated to check their ability to reduce the relatively high corrosion rates of Cu/Ni alloys in sulfide polluted seawater. It is found that an organic complexing agent such as fuchsin in the concentration range of 5 ppm is an excellent inhibitor against uniform and localized attack for 70/30 Cu/Ni alloy in 2 ppm sulfide polluted seawater. Another metal complexing agent, SSA (5-sulfosalicylic acid), was found to be effective for the 90/10 Cu/Ni alloy against enhanced attack by sulfide polluted seawater while it was ineffective for 70/30 Cu/Ni alloy. EDTA (ethylene diaminetetraacetic acid disodium salt) was found to be ineffective for both Cu/Ni alloys when used by itself in the concentration range of 5 ppm. A mechanism is proposed to explain the effectiveness of the various selected trace organic complexing agents on the corrosiveness of sulfide polluted seawater.

  10. Effect of gold composition on the orientations of oxide nuclei during the early stage oxidation of Cu-Au alloys

    SciTech Connect

    Luo Langli; Zhou Guangwen; Kang Yihong; Yang, Judith C.

    2012-04-15

    In situ environmental transmission electron microscopy is employed to study the effect of Au composition in Cu-Au alloys on the orientations of oxide islands during the initial-stage oxidation of Cu-Au(100) alloys. An orientation transition from nucleating epitaxial Cu{sub 2}O islands to randomly oriented oxide islands is observed upon increasing the oxygen gas pressure. By increasing the Au composition in the Cu-Au alloys, both the oxide nucleation time and saturation density of oxide islands increase, but the critical oxygen pressure leading to nucleating randomly oriented Cu{sub 2}O islands decreases. It is shown by a kinetic model that such a dependence of the critical oxygen pressure on the alloy composition is related to its effect on two competing processes, the oxide-alloy structure match and the effective collision of oxygen atoms, in determining the overall nucleation rate of oxide islands during the oxidation.

  11. Effect of the third element on the structure of liquid Mg65Cu25Y10 alloy

    NASA Astrophysics Data System (ADS)

    Liu, Dan; Zhu, Xun Ming; Qin, Jing Yu; Duan, Jun Peng; Wang, Ai Min; Gu, Ting Kun

    2016-08-01

    The liquid structures of Mg65Cu25Y10 and its three homologous binary liquid alloys are investigated via ab initio molecular dynamics in the present work. The chemical and topological environments in all four liquid alloys are analyzed using pair distribution function, coordination number, and the Voronoi polyhedron. It shows that the Cu atoms play significant role in deciding the chemical and topological short-range orders of the Mg65Cu25Y10 liquid alloy. The Voronoi polyhedra in the ternary liquid alloy illustrate less varieties and longer lifetime. Moreover, the diffusion coefficients are decreased significantly in the ternary liquid alloys according to the mean square displacements. All above offer a deeper insight into how the three species work in the Mg65Cu25Y10 liquid alloy.

  12. 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.

  13. Experimental and computational simulation studies on creep deformation mechanisms of a novel nanostructured Cu and Cu-10%Sn Alloy

    NASA Astrophysics Data System (ADS)

    Abo-Elsoud, Mohamed A.

    2015-04-01

    This work presents experimental and computational simulation studies on creep deformation mechanisms of a novel nanostructured Cu and Cu-10%Sn alloy that prepared by mechanical alloying (MA) copper with elemental Tin. Mechanical Newtonian creep model is employed for computational simulation of creep deformation mechanism under low stress-high temperature and to justify the experimental findings. The observed behaviors are discussed and compared with the predications of the Nabarro-Herring (N-H) theory of directional diffusion. A simple theory based on the climb controlled generation of dislocations from a fixed density of sources is developed to explain the observed behavior. TEM and SEM investigations are convenient and powerful techniques for characterization of phases and a novel nano-grain structured of the resulting materials. The reduction of grain size to the nanometer scale improves their mechanical properties.

  14. Bulk metallic glass formation in Zr-Cu-Fe-Al alloys

    SciTech Connect

    Jin Kaifeng; Loeffler, Joerg F.

    2005-06-13

    We have discovered a series of bulk metallic glass-forming alloys of composition (Zr{sub x}Cu{sub 100-x}){sub 80}(Fe{sub 40}Al{sub 60}){sub 20} with x=68-77 and have investigated them by x-ray diffraction, small-angle neutron scattering, and differential scanning calorimetry. All of these alloys exhibit a calorimetric glass transition temperature of 670 Kalloy Zr{sub 58}Cu{sub 22}Fe{sub 8}Al{sub 12}. In rod shape this alloy has a critical casting thickness of 13 mm, as verified by detailed casting experiments, while alloys with x=68 and 77 can still be cast to a thickness of 5 mm. Furthermore, the region where glassy samples with a thickness of 0.5 mm can be prepared extends from x=62-81. The best glass-former, Zr{sub 58}Cu{sub 22}Fe{sub 8}Al{sub 12}, has a tensile yield strength of 1.71 GPa and shows an elastic limit of 2.25%. This new class of Ni-free Zr-based alloys is potentially very interesting for biomedical applications.

  15. 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%). PMID:17359993

  16. Phase composition and structure of aluminum Al-Cu-Si-Sn-Pb alloys

    NASA Astrophysics Data System (ADS)

    Belov, N. A.; Stolyarova, O. O.; Murav'eva, T. I.; Zagorskii, D. L.

    2016-06-01

    The structure and phase composition of cast and heat treated Al-Cu-Si-Sn-Pb alloys containing 6 wt % Sn, 2 wt % Pb, 0-4 wt % Cu, 0-10 wt % Si have been studied using calculations and experimental methods. Polythermal and isothermal sections are reported, which indicate the existence of two liquid phases. It was found that the low-melting phase is inhomogeneous and consists of individual leadand tin-based particles.

  17. 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.

  18. Nano-Nucleation Characteristic of Cu-Ag Alloy Directly Electrodeposited on W Diffusion Barrier for Microelectronic Device Interconnect.

    PubMed

    Kim, Kang O; Kim, Sunjung

    2016-05-01

    Cu-Ag alloy interconnect is promising for ultra-large-scale integration (ULSI) microelectronic system of which device dimension keeps shrinking. In this study, seedless electrodeposition of Cu-Ag alloy directly on W diffusion barrier as interconnect technology is presented in respect of nano-nucleation control. Chemical equilibrium state of electrolyte was fundamentally investigated according to the pH of electrolyte because direct nano-nucleation of Cu-Ag alloy on W surface is challenging. Chelation behavior of Cu2+ and Ag+ ions with citrate (Cit) and ammonia ligands was dependent on the pH of electrolyte. The amount and kind of Cu- and Ag-based complexes determine the deposition rate, size, elemental composition, and surface morphology of Cu-Ag alloy nano-nuclei formed on W surface. PMID:27483895

  19. 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.

  20. 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

  1. Antibacterial effect of copper-bearing titanium alloy (Ti-Cu) against Streptococcus mutans and Porphyromonas gingivalis.

    PubMed

    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

  2. Charge transfer, lattice distortion, and quantum confinement effects in Pd, Cu, and Pd-Cu nanoparticles; size and alloying induced modifications in binding energy

    SciTech Connect

    Sengar, Saurabh K.; Mehta, B. R.; Gupta, Govind

    2011-05-09

    In this letter, effect of size and alloying on the core and valence band shifts of Pd, Cu, and Pd-Cu alloy nanoparticles has been studied. It has been shown that the sign and magnitude of the binding energy shifts is determined by the contributions of different effects; with quantum confinement and lattice distortion effects overlapping for size induced shifts in case of core levels and lattice distortion and charge transfer effects overlapping for alloying induced shifts at smaller sizes. These results are important for understanding gas molecule-solid surface interaction in metal and alloy nanoparticles in terms of valance band positions.

  3. Effects of Oxygen Impurities on Glass-Formation Ability in Zr2Cu Alloy.

    PubMed

    Wang, Zhanyu; Huang, Li; Yue, G Q; Shen, B; Dong, F; Zhang, R J; Zheng, Y X; Wang, S Y; Wang, C Z; Kramer, M J; Ho, K M; Chen, L Y

    2016-09-01

    Using ab initio molecular dynamics simulations, we show that oxygen (O) impurities have a noticeable influence on the glass-formation ability (GFA) in Zr2Cu alloy. Cu-centered icosahedral clusters and Zr-centered Kasper polyhedra are the dominate short-range orders in undercooled Zr2Cu liquid which are most likely to be responsible for the glass formation in Zr2Cu systems. When O is introduced, a Zr octahedron is formed around the O impurity. Most of the Zr atoms in the octahedron also serve as the bridging atoms for cross-linked Kasper polyhedral network, resulting in an O-centered medium range order (MRO) structure. Meanwhile, Cu atoms are moved away from the first shell of O-centered octahedral clusters. With 1 at. % O impurities, the fractions of Zr-centered clusters are less affected, while the increase of ideal icosahedral order and decrease of distorted icosahedral order lead to a more stable atomic structure. This result suggests that a low concentration of O impurities would improve the GFA in Zr2Cu alloy. However, when ∼5 at. % O impurities are included, the ideal icosahedral clusters and Zr-centered Kasper polyhedra are seriously suppressed by the formation of O-centered MRO, which can lead to deterioration of GFA. Our analyses provide useful insight into glass formation behavior in O-doped metallic alloy systems. PMID:27509394

  4. 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

  5. Interfacial Free Energy Controlling Glass-Forming Ability of Cu-Zr Alloys

    NASA Astrophysics Data System (ADS)

    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

    2014-06-01

    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.

  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. Study of local structure in hyper-eutectic Zr-Cu-Al bulk glassy alloys by positron annihilation techniques

    NASA Astrophysics Data System (ADS)

    Ishiyama, T.; Ishii, K.; Yokoyama, Y.; Konno, T. J.; Iwase, A.; Hori, F.

    2016-01-01

    The Zr-Cu-Al bulk glassy (BG) alloy, which has amorphous structure, possesses various properties such as high strength and toughness with compositional dependence. In the present study, density, positron annihilation lifetime and coincidence Doppler Broadening measurement have been performed for various compositional hyper-eutectic Zr-Cu-Al BG alloys. The density of hyper-eutectic Zr-Cu-Al BG alloys increases with decreasing of Zr fraction. In contrast, positron lifetime for all compositional alloys is almost constant about 165 psec. In addition, the CDB ratio profile is almost the same for hyper-eutectic alloys. This unchanging trend of CDB ratio profile is quite different from that of hypo-eutectic BG alloys. These results reveal that different internal structure exists in hyper and hypo-eutectic BG alloys.

  8. 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

  9. Amorphous alloy catalysis: VII. Activation and surface characterization of an amorphous Cu-Ti alloy catalyst precursor in the dehydrogenation of 2-propanol and comparison with Cu-Zr

    SciTech Connect

    Katona, T.; Molnar, A.

    1995-05-01

    The activation and catalytic properties of Cu-Ti and Cu-Zr metallic glass precursors in the dehydrogenation of 2-propanol differ substantially. In contrast with Cu-Zr, Cu-Ti can only be activated with HF solution. The pretreatment of Cu-Ti results in catalysts with BET and copper surface areas one order of magnitude smaller than those of Cu-Zr under the same conditions. Cu-Ti exhibits decreasing catalytic activity, while Cu-Zr displays stable activity in the course of the reaction. Crystallization of the metallic glasses prior to HF treatment results in a weaker reactivity toward hydrogen fluoride for both alloys. Scanning electron micrographs of the alloys reveal that HF etching results in surfaces with deep grooves, and copper-rich flakes, a Raney-Cu-like catalyst. Auger electron spectroscopic studies show copper enrichment in the surface region on both alloys after HF treatment. On the surface of Cu-Ti, mostly Cu(II) is detected, whereas Cu(O) and Cu(II) coexist on Cu-Zr. 54 refs., 11 figs., 2 tabs.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Al-Cu-Li and Al-Mg-Li alloys: Phase composition, texture, and anisotropy of mechanical properties (Review)

    NASA Astrophysics Data System (ADS)

    Betsofen, S. Ya.; Antipov, V. V.; Knyazev, M. I.

    2016-04-01

    The results of studying the phase transformations, the texture formation, and the anisotropy of the mechanical properties in Al-Cu-Li and Al-Mg-Li alloys are generalized. A technique and equations are developed to calculate the amounts of the S1 (Al2MgLi), T1 (Al2CuLi), and δ' (Al3Li) phases. The fraction of the δ' phase in Al-Cu-Li alloys is shown to be significantly higher than in Al-Mg-Li alloys. Therefore, the role of the T1 phase in the hardening of Al-Cu-Li alloys is thought to be overestimated, especially in alloys with more than 1.5% Li. A new model is proposed to describe the hardening of Al-Cu-Li alloys upon aging, and the results obtained with this model agree well with the experimental data. A texture, which is analogous to that in aluminum alloys, is shown to form in sheets semiproducts made of Al-Cu-Li and Al-Mg-Li alloys. The more pronounced anisotropy of the properties of lithium-containing aluminum alloys is caused by a significant fraction of the ordered coherent δ' phase, the deformation mechanism in which differs radically from that in the solid solution.

  15. 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.

  16. 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.

  17. Dissolution of Cu/Mg Bearing Intermetallics in Al-Si Foundry Alloys

    NASA Astrophysics Data System (ADS)

    Javidani, Mousa; Larouche, Daniel; Grant Chen, X.

    2016-08-01

    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.

  18. 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)

  19. Structural evolution and the kinetics of Cu clustering in the amorphous phase of Fe-Cu-Nb-Si-B alloy

    NASA Astrophysics Data System (ADS)

    Gupta, P.; Gupta, A.; Shukla, A.; Ganguli, Tapas; Sinha, A. K.; Principi, G.; Maddalena, A.

    2011-08-01

    An attempt has been made to investigate the evolution of the structure of the amorphous phase of Fe73.9 Cu0.9 Nb3.1 Si13.2 B8.9 (finemet) alloy by a combination of wide-angle x-ray scattering, small angle x-ray scattering (SAXS), Mössbauer spectroscopy and X-ray absorption near edge spectroscopy on the supposition that they would provide complementary information. Before the onset of nanocrystallization, the amorphous phase undergoes a structural relaxation resulting in small increase in the hyperfine field and a decrease in the width of the first diffraction maxima. There is an increase in the topological ordering in the system, though chemical inhomogeneity sets-in due to the clustering of Cu atoms in the pure amorphous state of this alloy. Annealing at 400 °C (well below the crystallization temperature) for different time durations results in occurrence of Cu clusters having fcc structure. Kinetics of Cu clustering is studied using SAXS. The incubation time for the clustering at 400 °C is ˜120 min. With further annealing, the average cluster size gradually increases from the initial value of ˜0.4 nm, reaching a value of ˜0.6 nm after annealing for 720 min. Cluster size exhibits a t1/2 dependence, suggesting a diffusion controlled growth.

  20. 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.

  1. On the mechanisms of cation injection in conducting bridge memories: The case of HfO2 in contact with noble metal anodes (Au, Cu, Ag)

    NASA Astrophysics Data System (ADS)

    Saadi, M.; Gonon, P.; Vallée, C.; Mannequin, C.; Grampeix, H.; Jalaguier, E.; Jomni, F.; Bsiesy, A.

    2016-03-01

    Resistance switching is studied in HfO2 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 HfO2/anode interface. If oxygen ion mobility is low in the interfacial oxide, a negative space charge builds-up at the HfO2/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).

  2. Fim study on the relaxation and crystallization processes of a Cu-Zr amorphous alloy

    NASA Astrophysics Data System (ADS)

    H, Lu; Lu, Hua; D, S. Tang; Tang, Disheng; Y, Y. Xiong; Xiong, Yanyun

    1987-09-01

    The relaxation of the Cu-50at.%Zr amorphous alloy was revealed by FIM as a process of formation of clusters consisting of 2, 3, or 4 atoms, which afterwards migrate towards some definite centers, predominantly the quenched-in "embryos", to construct ordered structure. This dynamic picture, so far as we know, is observed for the first time. Crystallized regions were determined by atom-probe analysis as Cu10Zr7 phase, and the coexisting phase CuZr2 was not revealed simultaneously.

  3. Surface segregation phenomena in extended and nanoparticle surfaces of Cu-Au alloys

    NASA Astrophysics Data System (ADS)

    Li, Jonathan; Wang, Guofeng; Zhou, Guangwen

    2016-07-01

    Using density functional theory (DFT) and Monte Carlo (MC) simulations, we studied the surface segregation phenomena of Au atoms in the extended and nanoparticle surfaces of Cu-Au alloys. Our MC simulations predicted significant Au enrichment in the outermost layer of (111) and (100) extended surfaces, and Au enrichment in the two outermost layers of (110) extended surfaces. The equilibrium Cu-Au nanoparticles were predicted to develop into an Au-enriched shell structure, where Au atoms preferably segregate to the (100) facets while Cu atoms are mainly located on the (111) facet of the nanoparticles. Our simulation predictions agree with experimental measurements.

  4. Lattice Changes in Shape Memory CuZnAl Alloys on Aging at Room Temperature

    NASA Astrophysics Data System (ADS)

    Çakmak, Seyfettýn; Artunç, Ekrem; Kayali, Nejdet; Adigüzel, Osman

    2001-09-01

    The aging behavior of CuZnAl martensites (Cu-21.62 wt.% Zn-5.68 wt.% Al and Cu-24.98 wt.% Zn-4.43 wt.% Al) at about 297 K was studied by analyzing diffraction line profiles obtained by X-ray diffractometry. For the alloys, the change of the lattice parameters and the tetragonality associated with the aging time at room temperature were investigated. The habit planes versus the aging time at room temperature were calculated using the De Vos-Aernoundt-Delaey model, based on the crystallographic theory of Wechsler-Lieberman-Read(WLR), and from the DO3→ 18R martensite transformation theory.

  5. High performance Au-Cu alloy for enhanced visible-light water splitting driven by coinage metals.

    PubMed

    Liu, Mingyang; Zhou, Wei; Wang, Ting; Wang, Defa; Liu, Lequan; Ye, Jinhua

    2016-03-17

    A Au-Cu alloy strategy is, for the first time, demonstrated to be effective in enhancing visible-light photocatalytic H2 evolution via promoting metal interband transitions. Au3Cu/SrTiO3, in which oxidation of Cu was successfully restrained, showed the highest visible-light H2 evolution activity. PMID:26952932

  6. 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.

  7. Electrolytic production of metals using a resistant anode

    SciTech Connect

    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.

  8. Isothermal Solid-State Transformation Kinetics Applied to Pd/Cu Alloy Membrane Fabrication

    SciTech Connect

    Pomerantz, Natalie L; Payzant, E Andrew; Ma, Yi Hua

    2010-01-01

    In this work, time-resolved, in situ high-temperature X-ray diffraction (HT-XRD) was used to study the solid-state transformation kinetics of the formation of the fcc Pd/Cu alloy from Pd/Cu bi-layers for the purpose of fabricating sulfur tolerant Pd/Cu membranes for H2 separation. Thin layers of Pd and Cu (total ~15 wt% Cu) were deposited on porous stainless steel (PSS) with the electroless deposition method and annealed in H2 at 500, 550 and 600 C. The kinetics of the annealing process were successfully described by the Avrami nucleation and growth model showing that the annealing process was diffusion controlled and one dimensional. The activation energy for the solid-state transformation was 175 kJ/mol, which was similar to the activation energy of Pd-Cu bulk interdiffusion. Furthermore, the Avrami model was able to successfully describe the changes in permeance and activation energy observed in Pd/Cu alloy membranes during characterization as they were annealed at high temperatures.

  9. 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.

  10. 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.

  11. Understanding the Cu-Zn brass alloys using a short-range-order cluster model: significance of specific compositions of industrial alloys.

    PubMed

    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]Zn(1~6) 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 1(st)-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

  12. 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

  13. Study on structure and properties of CuZn40Pb alloy

    NASA Astrophysics Data System (ADS)

    Achiţei, D. C.; Minciună, M. G.; Vizureanu, P.; Sandu, A. V.; Cimpoeşu, R.; Istrate, B.

    2016-06-01

    The paper shows aspects about the behavior of Cu-Zn-Pb alloys a subjected to the temperatures variation and corrosion resistance in saline medium (sea water). The chemical composition was determined by spectral analysis on optical spectrometer, type Foundry Masters. The experiments are completed by a microstructure analysis made on scanning electronic microscope.

  14. 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.

  15. Sulfuration resistance of five experimental Ag-Pd-Au-Cu alloys with low Pd content of 10 or 12%.

    PubMed

    Saitoh, Setsuo; Araki, Yoshima; Taira, Masayuki

    2006-06-01

    Commercial Ag-based alloy (46Ag-20Pd-12Au-20Cu alloy) is widely used in Japan as a casting alloy. As opposed to the commercial composition, we prepared five experimental Ag-based alloys with reduced Pd content of 10 or 12%, increased Au content of 20 to 30%, and reduced Cu content of 12 to 20%. We then evaluated their sulfuration resistance by analyzing cast specimen surfaces dipped in 0.1% Na2S solution with SEM/EPMA, TF-XRD, and XPS. It became evident that all alloys were susceptible to sulfuration in the segregated Ag-rich Pd-poor phases. The degree and speed of sulfuration, however, differed among the six alloys examined. In particular, one experimental alloy (46Ag-10Pd-30Au-12Cu) possessed a sulfuration resistance equal or superior to that of commercial Ag-based alloy, while the other four experimental alloys were inferior in sulfuration resistance. Based on the results of this study, we concluded that our newly developed 46Ag-10Pd-30Au-12Cu alloy could be employed as a new sulfuration-resistant Ag-based casting alloy--which is especially useful if the price of Pd is skyrocketing again. PMID:16916236

  16. 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.

  17. Characterization of Localized Corrosion in an Al-Cu-Li Alloy

    NASA Astrophysics Data System (ADS)

    Luo, Chen; Zhang, Xinxin; Zhou, Xiaorong; Sun, Zhihua; Zhang, Xiaoyun; Tang, Zhihui; Lu, Feng; Thompson, George E.

    2016-05-01

    Corrosion behaviors of recently developed 2A97-T6 aluminum-copper-lithium alloy in sodium chloride solution are investigated using scanning electron and transmission electron microscopies in conjunction with electron backscatter diffraction. It has been found that corrosion product rings were established on the alloy surface as early as 5 min during immersion in sodium chloride solution. Meanwhile, hydrogen continuously evolved from within the rings. Pitting corrosion is evident with crystallographic dependant corrosion channel facets mainly parallel to {100} planes. Non-uniform distribution of misorientation in the 2A97 aluminum alloy results in a portion of grains of relatively high stored energy. Such grains were preferentially attacked, serving as local anodes, during the development of crystallographic pitting.

  18. Thermal and structural characterization of Cu-Al-Mn-X (Ti, Ni) shape memory alloys

    NASA Astrophysics Data System (ADS)

    Canbay, C. Aksu; Genc, Z. Karagoz; Sekerci, M.

    2014-05-01

    In this study, the Cu-Al-Mn-X (X = Ni, Ti) shape memory alloys at the range of 10-12 at.% of aluminum and 4-5 at.% manganese were produced by arc melting. We have investigated the effects of the alloying elements on the transformation temperatures, and the structural and the magnetic properties of the quaternary Cu-Al-Mn-X (X = Ni, Ti) shape memory alloys. The evolution of the transformation temperatures was studied by differential scanning calorimetry with different heating and cooling rates. The characteristic transformation temperatures and the thermodynamic parameters were highly sensitive to variations in the aluminum and manganese content, and it was observed that the nickel addition into the Cu-Al-Mn system decreased the transformation temperature although Ti addition caused an increase in the transformation temperatures. The effect of the nickel and the titanium on the thermodynamic parameters such as enthalpy and entropy values was investigated. The structural changes of the samples were studied by X-ray diffraction measurements and by optical microscope observations at room temperature. It is evaluated that the element Ni has been completely soluble in the matrix, and the main phase of the Cu-Al-Mn-Ni sample is martensite, and due to the low solubility of the Ti, the Cu-Al-Mn-Ti sample has precipitates, and a martensite phase at room temperature. The magnetic properties of the Cu-Al-Mn, Cu-Al-Mn-Ni and Cu-Al-Mn-Ti samples were investigated, and the effect of the nickel and the titanium on the magnetic properties was studied.

  19. 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.

  20. Hybrid CuO/SnO{sub 2} nanocomposites: Towards cost-effective and high performance binder free lithium ion batteries anode materials

    SciTech Connect

    Xing, G. Z.; Wang, Y.; Wong, J. I.; Shi, Y. M.; Huang, Z. X.; Yang, H. Y.; Li, S.

    2014-10-06

    Hybrid CuO/SnO{sub 2} nanocomposites are synthesized by a facile thermal annealing method on Cu foils. Compared to pristine CuO and SnO{sub 2} nanostructures, hybrid CuO/SnO{sub 2} nanocomposites exhibit the enhanced electrochemical performances as the anode material of lithium ion batteries (LIBs) with high specific capacity and excellent rate capability. The binder free CuO/SnO{sub 2} nanocomposites deliver a specific capacity of 718 mA h g{sup −1} at a current density of 500 mA g{sup −1} even after 200 cycles. The enhanced electrochemical performances are attributed to the synergistic effect between SnO{sub 2} nanoparticles and CuO nanoarchitectures. Such hybrid CuO/SnO{sub 2} nanocomposites could open up a new route for the development of next-generation high-performance and cost-effective binder free anode material of LIBs for mass production.

  1. Effect of solidified structure on hot tear in Al-Cu alloy

    NASA Astrophysics Data System (ADS)

    Yoshida, Y.; Esaka, H.; Shinozuka, K.

    2015-06-01

    Hot tear is the one of the biggest problems of cast products of aluminum alloy. The effect of solidified structure on the hot tear has not been clear. Therefore, this study has been carried out to correlate solidified structure and hot tear. Al-2.0 wt% Cu alloy was cast at 750 °C in a moldcavity, which could intentionally form hot tear. To change solidified structure, some amount of refiner was added to the molten alloy. Length of hot tear decreased with increasing the amount of refiner. Further, the area of fine eutectic Al2Cu increased as amount of refiner increased. These may indicate that probability of healing increased in case of equiaxed structure. Therefore, the length of hot tear decreased with increasing the amount of refiner. great care should be taken in constructing both.

  2. Microstructural evolution in Al-Zn-Mg-Cu-Sc-Zr alloys during short-time homogenization

    NASA Astrophysics Data System (ADS)

    Liu, Tao; He, Chun-nian; Li, Gen; Meng, Xin; Shi, Chun-sheng; Zhao, Nai-qin

    2015-05-01

    Microstructural evolution in a new kind of aluminum (Al) alloy with the chemical composition of Al-8.82Zn-2.08Mg-0.80Cu-0.31Sc-0.3Zr was investigated. It is found that the secondary phase MgZn2 is completely dissolved into the matrix during a short homogenization treatment (470°C, 1 h), while the primary phase Al3(Sc,Zr) remains stable. This is due to Sc and Zr additions into the Al alloy, high Zn/Mg mass ratio, and low Cu content. The experimental findings fit well with the results calculated by the homogenization diffusion kinetics equation. The alloy shows an excellent mechanical performance after the short homogenization process followed by hot-extrusion and T6 treatment. Consequently, a good combination of low energy consumption and favorable mechanical properties is obtained.

  3. Voids in fast-neutron-irradiated Cu, Ni and Cu-Ni concentrated alloys studied by TEM and positron annihilation methods

    NASA Astrophysics Data System (ADS)

    Fukushima, H.; Ochiai, K.; Shimomura, Y.

    The effect of concentrated Ni and Cu solute atoms in the Cu-Ni system on the formation of voids has been examined using Cu, Cu-8 at.% Ni, Ni-8 at.% Cu and Ni irradiated with fast-neutrons in the FFTF-MOTA. Both solute atoms introduced smaller voids in the grains of the concentrated alloys than voids in the normal grains of pure-Cu and pure-Ni. Slight increase of irradiation temperature and the higher dose of fast-neutrons induced coalescence of voids in the grains of Ni-8 at.% Cu, but it resulted in the abrupt decrease of the concentration of small voids in the grains and the formation of heterogeneously distributed larger voids near grain boundaries in Cu-8 at.% Ni. Heterogeneous distribution of larger voids was also observed in other materials. Annealing at higher temperatures induced segregation of impurity atoms at a void surface in Ni-8 at.% Cu.

  4. Room-Temperature Indentation Creep and the Mechanical Properties of Rapidly Solidified Sn-Sb-Pb-Cu Alloys

    NASA Astrophysics Data System (ADS)

    Kamal, Mustafa; El-Bediwi, A.; Lashin, A. R.; El-Zarka, A. H.

    2016-05-01

    In this paper, we study the room-temperature indentation creep and the mechanical properties of Sn-Sb-Pb-Cu alloys. Rapid solidification from melt using the melt-spinning technique is applied to prepare all the alloys. The experimental results show that the magnitude of the creep displacement increases with the increase in both time and applied load, and the stress exponent increases with the increase in the copper content in the alloys which happens primarily due to the existence of the intermetallic compounds SbSn and Cu6Sn5. The calculated values of the stress exponent are in the range of 2.82 to 5.16, which are in good agreement with the values reported for the Sn-Sb-Pb-Cu alloys. We have also studied and analyzed the structure, elastic modulus, and internal friction of the Sn-Sb-Pb-Cu alloys.

  5. 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.

  6. Mechanism by which porous structure is formed on the surface of gold alloy containing only Cu as base metal.

    PubMed

    Ohno, Hiroki; Endo, Kazuhiko; Haneda, Katsumi; Tamura, Makoto; Hikita, Kazuhiro

    2005-12-01

    Gold alloys with Cu contents of 10 mass%, 20%, and 30% were used for morphological observation of porous surface structures after heating at 800 degrees C in air followed by pickling with acid solution. With increasing Cu content in the gold alloy, the internal oxidation zone became well-developed in the alloy matrix. The mechanism by which a porous structure was formed on the surface of a gold alloy containing only Cu as a base metal was thought to be as follows: Cu2O which formed along the grain boundaries acted as a diffusion path, permitting the penetration of O2- into the inner alloy matrix, and thereby resulting in internal oxidation occurring predominantly along the grain boundaries. PMID:16445010

  7. Chemical Dealloying Derived 3D Porous Current Collector for Li Metal Anodes.

    PubMed

    Yun, Qinbai; He, Yan-Bing; Lv, Wei; Zhao, Yan; Li, Baohua; Kang, Feiyu; Yang, Quan-Hong

    2016-08-01

    A 3D porous Cu current collector is fabricated through chemical dealloying from a commerial Cu-Zn alloy tape. The interlinked porous framework naturally integrated can accommodate Li deposition, suppressing dendrite growth and alleviating the huge volume change during cycling. The Li metal anode combined with such a porous Cu collector demonstrates excellent performance and commerial potentials in Li-based secondary batteries. PMID:27219349

  8. 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. PMID:27254454

  9. Enhanced spin Hall effect by electron correlations in CuBi alloys

    NASA Astrophysics Data System (ADS)

    Gu, Bo; Xu, Zhuo; Mori, Michiyasu; Ziman, Timothy; Maekawa, Sadamichi

    2015-05-01

    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.

  10. 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.

  11. Magnetic States in Ensemble of Ferromagnetic Nanoparticles in Cu-Mn-Al Alloy.

    PubMed

    Konoplyuk, S M; Kozlova, L E; Kokorin, V V; Perekos, A O; Kolomiets, O V

    2016-12-01

    Two Cu-Mn-Al samples of different compositions were studied: one exhibiting martensitic transformation, another without structural transition. X-ray diffraction and magnetic measurements demonstrate that different magnetic behaviors of alloys originate from different concentrations and sizes of ferromagnetic nanoparticles, which appear after solid solution decomposition.Estimation of magnetic moments of ferromagnetic nanoparticles from magnetization curves was performed using Langevin function and compared to those obtained from X-ray examination. Granular systems are known to show giant magnetoresistance. Therefore, magnetoresistance of Cu-Mn-Al melt-spun ribbons after different aging times was measured. The study has shown that increase in the concentration of Mn atoms and time of aging in Cu-Mn-Al alloy leads to an increase in the amount of precipitated phase appearing as ferromagnetic nanoparticles. PMID:26762264

  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. 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

  14. Intrinsic fatigue crack growth rates for Al-Li-Cu-Mg alloys in vacuum

    SciTech Connect

    Slavik, D.C.; Gangloff, R.P.; Starke, E.A. Jr ); Blankenship, C.P. Jr )

    1993-08-01

    The influences of microstructure and deformation mode on inert environment intrinsic fatigue crack propagation were investigated for Al-Li-Cu-Mg alloys AA2090, AA8090, and X2095 compared to AA2024. The amount of coherent shearable [delta][prime] (Al[sub 3]Li) precipitates and extent of localized planar slip deformation were reduced by composition (increased Cu/Li in X2095) and heat treatment (double aging of AA8090). Intrinsic growth rates, obtained at high constant K[sub max] to minimize crack closure and in vacuum to eliminate any environmental effect, were alloy dependent; da/dN varied up to tenfold based on applied [Delta]K or [Delta]K/E. When compared based on a crack tip cyclic strain or opening displacement parameter ([Delta]K/([sigma][sub ys]E)[sup 1/2]), growth rates were equivalent for alloys except X2095-T8 which exhibited unique fatigue crack growth resistance. Tortuous fatigue crack profiles and large fracture surface facets were observed for each Al-Li alloy independent of the precipitates present, particularly [sigma][prime], and the localized slip deformation structure. Reduced fatigue crack propagation rates for X2095 in vacuum are not explained by either residual crack closure or slip reversibility arguments; the origin of apparent slip band facets in a homogeneous slip alloy is unclear. Better understanding of crack tip damage accumulation and fracture surface facet crystallography is required for Al-Li alloys with varying slip localization.

  15. Characterization of a CuAlBe Alloy with Different Cr Contents

    NASA Astrophysics Data System (ADS)

    da M. Candido, Gemierson Valois; de A. Melo, Tadeu Antônio; De Albuquerque, Victor Hugo C.; Gomes, Rodinei Medeiros; de Lima, Severino Jackson G.; Tavares, João Manuel R. S.

    2012-11-01

    In this article, the use of chromium (Cr) as a grain refiner for a CuAlBe shape memory alloy is discussed. Alloys with 0.1, 0.2, 0.3, and 0.5 wt.% Cr were characterized by optical microscopy, scanning electron microscope, and x-ray diffraction. Also, the influence of the different percentages of Cr on the grain size and on the mechanical properties was analyzed through macro- and microscopic evaluations and by tensile and hardness tests, respectively. Finally, the phase transformation temperatures of the alloys were determined by thermal analysis using differential scanning calorimetry. The results showed that the higher the Cr content, the greater the grain refinement effect and lower the hardness. In addition, at room temperature the alloys with 0.1 and 0.2 wt.% Cr were austenitic, while the rest were martensitic. The tensile tests showed that the alloy with 0.2 wt.% Cr provided the best strain-stress performance. The conclusion was that the use of 0.2 wt.% Cr as a grain refiner improved the mechanical properties of the CuAlBe alloy; however, the same was not observed for the other Cr contents.

  16. 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.

  17. Electric field control of magnetization in Cu2O/porous anodic alumina hybrid structures at room temperature

    NASA Astrophysics Data System (ADS)

    Qi, L. Q.; Liu, H. Y.; Sun, H. Y.; Liu, L. H.; Han, R. S.

    2016-04-01

    Cu2O nanoporous films are deposited on porous anodic alumina (PAA) substrates by DC-reactive magnetron sputtering. This paper focuses on voltage driven magnetization switching in Cu2O/PAA (CP) composite films prepared by DC-reactive magnetron sputtering. By applying a dc electric field, the magnetization of the CP composite films can be controlled in a reversible and reproducible way and shows an analogous on-off behavior. The magnitude of the change in the magnetization was about 75 emu/cm3 as the electric field was switched on and off. Resistive switching behavior was also observed in as-prepared CP composite films. Further analysis indicated that the formation/rupture of conducting filaments composed of oxygen vacancies is likely responsible for the changes in the magnetization as well as in the resistivity. Such reversible change of magnetization controlled by an electric field at room temperature may have applications in spintronics and power efficient data storage technologies.

  18. Electrically conductive anodized aluminum coatings

    NASA Technical Reports Server (NTRS)

    Alwitt, Robert S. (Inventor); Liu, Yanming (Inventor)

    2001-01-01

    A process for producing anodized aluminum with enhanced electrical conductivity, comprising anodic oxidation of aluminum alloy substrate, electrolytic deposition of a small amount of metal into the pores of the anodized aluminum, and electrolytic anodic deposition of an electrically conductive oxide, including manganese dioxide, into the pores containing the metal deposit; and the product produced by the process.

  19. Discharge properties of Mg-Al-Mn-Ca and Mg-Al-Mn alloys as anode materials for primary magnesium-air batteries

    NASA Astrophysics Data System (ADS)

    Yuasa, Motohiro; Huang, Xinsheng; Suzuki, Kazutaka; Mabuchi, Mamoru; Chino, Yasumasa

    2015-11-01

    The discharge behaviors of rolled Mg-6 mass%Al-0.3 mass%Mn-2 mass%Ca (AMX602) and Mg-6 mass%Al-0.3 mass%Mn (AM60) alloys used as anodes for Magnesium-air batteries were investigated. The AMX602 alloy exhibited superior discharge properties compared to the AM60 alloy, especially at low current density. The discharge products of the AMX602 alloy were dense and thin, and many cracks were observed at all current densities. In addition, the discharge products were detached at some sites. These sites often corresponded to the positions of Al2Ca particles. The comparison of the discharge and corrosion tests indicated that the dense and thin discharge products of AMX602 were easily cracked by dissolution of the Mg matrix around Al2Ca particles, and the cracks promoted the penetration of the electrolyte into the discharge products, retaining the discharge activity. In contrast, concerning the AM60 alloy, thick discharge products were formed on the surface during discharge, and cracking of the discharge products hardly occurred, degrading the discharge properties. Localized and deeply corroded pits that could result from the detachment of metal pieces from the anode during discharge were partly observed in the AM60 alloy. It is suggested that these detached metal pieces are another reason for the low discharge properties of the AM60 alloy.

  20. 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.

  1. 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

  2. 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%.

  3. Enhancing the response of microbial fuel cell based toxicity sensors to Cu(II) with the applying of flow-through electrodes and controlled anode potentials.

    PubMed

    Jiang, Yong; Liang, Peng; Zhang, Changyong; Bian, Yanhong; Yang, Xufei; Huang, Xia; Girguis, Peter R

    2015-08-01

    The application of microbial fuel cell (MFC)-based toxicity sensors to real-world water monitoring is partly impeded by the limited sensitivity. To address this limitation, this study optimized the flow configurations and the control modes. Results revealed that the sensitivity increased by ∼15-41times with the applying of a flow-through anode, compared to those with a flow-by anode. The sensors operated in the controlled anode potential (CP) mode delivered better sensitivity than those operated in the constant external resistance (ER) mode over a broad range of anode potentials from -0.41V to +0.1V. Electrodeposition of Cu(II) was found to bias the toxicity measurement at low anode potentials. The optimal anode potential was approximately -0.15V, at which the sensor achieved an unbiased measurement of toxicity and the highest sensitivity. This value was greater than those required for electrodeposition while smaller than those for power overshoot. PMID:25965954

  4. Probing the mechanism of sodium ion insertion into copper antimony Cu2Sb anodes

    DOE PAGESBeta

    Baggetto, Loic; Carroll, Kyler J.; Hah, Hien -Yoong; Johnson, Charles E.; Mullins, David R.; Unocic, Raymond R.; Johnson, Jacqueline A.; Meng, Ying Shirley; Veith, Gabriel M.

    2014-03-25

    Cycling Cu2Sb films with fluoroethylene carbonate additive drastically improves the capacity retention of the electrode compared to cycling in pure PC with about 250 mAh g-1 retained capacity for about two hundred cycles. TEM photographs reveal that the pristine films are formed of nanoparticles of 5-20 nm diameters. XRD results highlight that during the first discharge the reaction leads to the formation of Na3Sb via an intermediate amorphous phase. During charge, Na3Sb crystallites convert into an amorphous phase, which eventually crystallizes into Cu2Sb at full charge, indicating a high degree of structural reversibility. The subsequent discharge is marked by amore » new plateau around 0.5 V at low Na/Sb content which does not correspond to the formation of a crystalline phase. XAS data show that the fully discharged electrode material has interatomic distances matching those expected for the coexistence of Cu and Na3Sb nanodomains. At 1 V charge, the structure somewhat differs from that of Cu2Sb whereas at 2 V charge, when all Na is removed, the structure is significantly closer to that of the starting material. 121Sb Mössbauer spectroscopy isomer shifts of Cu2Sb powder (-9.67 mm s-1) and thin films (-9.65 mm s-1) are reported for the first time, and agree with the value predicted theoretically. At full discharge, an isomer shift (-8.10 mm s-1) rather close to that of a Na3Sb reference powder (-8.00 mm s-1) is measured, in agreement with the formation of Na3Sb domains evidenced by XRD and XAS data. As a result, the isomer shift at 1 V charge (-9.29 mm s-1) is close to that of the pristine material and the higher value is in agreement with the lack of full desodiation at 1 V.« less

  5. 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.

  6. 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.

  7. Interdiffusion in. beta. phase Cu--Al alloys

    SciTech Connect

    Romig, A.D. Jr.

    1983-06-01

    The diffusion behavior of ..beta.. phase Cu--Al has been studied at 800, 850, and 950 /sup 0/C using the experimental approach and analysis scheme of Kirkendall and Darken. Diffusion couples were made using the window frame technique and concentration profiles were determined by electron probe microanalysis. The chemical diffusion coefficient, D was found to be D = 0.65 exp(-42200/RT) cm/sup 2//s. The diffusivity was observed to be independent of composition over the range 11--13 wt. % Al. The self-diffusion coefficients D/sub Cu/ and D/sub Al/ were determined to be D/sub Al/ = 0.13 exp(-38900/RT) cm/sup 2//s and D/sub Cu/ = 2.2 exp(-43400/RT) cm/sup 2//s. All activation energies are in calories/mole.

  8. Grain Refinement of an Al-2 wt%Cu Alloy by Al3Ti1B Master Alloy and Ultrasonic Treatment

    NASA Astrophysics Data System (ADS)

    Wang, E. Q.; Wang, G.; Dargusch, M. S.; Qian, M.; Eskin, D. G.; StJohn, D. H.

    2016-03-01

    Both inoculation by AlTiB master alloys and Ultrasonic Treatment (UT) are effective methods of refining the grain size of aluminium alloys. The present study investigates the influence of UT on the grain refinement of an Al-2 wt% Cu alloy with a range of Al3TilB master alloy additions. When the alloy contains the smallest amount of added master alloy, UT caused significant additional grain refinement compared with that provided by the master alloy only. However, the influence of UT on grain size reduces with increasing addition of the master alloy. Plotting the grain size data versus the inverse of the growth restriction factor (Q) reveals that the application of UT causes both an increase in the number of potentially active nuclei and a decrease in the size of the nucleation free zone due to a reduction in the temperature gradient throughout the melt. Both these factors promote the formation of a fine equiaxed grain structure.

  9. Assessment of Post-eutectic Reactions in Multicomponent Al-Si Foundry Alloys Containing Cu, Mg, and Fe

    NASA Astrophysics Data System (ADS)

    Javidani, Mousa; Larouche, Daniel; Grant Chen, X.

    2015-07-01

    Post-eutectic reactions occurring in Al-Si hypoeutectic alloys containing different proportions of Cu, Mg, and Fe were thoroughly investigated in the current study. As-cast microstructures were initially studied by optical and electron microscopy to investigate the microconstituents of each alloy. Differential scanning calorimetry (DSC) was then used to examine the phase transformations occurring during the heating and cooling processes. Thermodynamic calculations were carried out to assess the phase formation under equilibrium and in nonequilibrium conditions. The Q-Al5Cu2Mg8Si6 phase was predicted to precipitate from the liquid phase, either at the same temperature or earlier than the θ-Al2Cu phase depending on the Cu content of the alloy. The AlCuFe-intermetallic, which was hardly observed in the as-cast microstructure, significantly increased after the solution heat treatment in the alloys containing high Cu and Fe contents following a solid-state transformation of the β-Al5FeSi phase. After the solution heat treatment, the AlCuFe-intermetallics were mostly identified with the stoichiometry of the Al7Cu2Fe phase. Thermodynamic calculations and microstructure analysis helped in determining the DSC peak corresponding to the melting temperature of the N-Al7Cu2Fe phase. The effect of Cu content on the formation temperature of π-Al8Mg3FeSi6 is also discussed.

  10. Tin-germanium alloys as anode materials for sodium-ion batteries.

    PubMed

    Abel, Paul R; Fields, Meredith G; Heller, Adam; Mullins, C Buddie

    2014-09-24

    The sodium electrochemistry of evaporatively deposited tin, germanium, and alloys of the two elements is reported. Limiting the sodium stripping voltage window to 0.75 V versus Na/Na+ improves the stability of the tin and tin-rich compositions on repeated sodiation/desodiation cycles, whereas the germanium and germanium-rich alloys were stable up to 1.5 V. The stability of the electrodes could be correlated to the surface mobility of the alloy species during deposition suggesting that tin must be effectively immobilized in order to be successfully utilized as a stable electrode. While the stability of the alloys is greatly increased by the presence of germanium, the specific Coulombic capacity of the alloy decreases with increasing germanium content due to the lower Coulombic capacity of germanium. Additionally, the presence of germanium in the alloy suppresses the formation of intermediate phases present in the electrochemical sodiation of tin. Four-point probe resistivity measurements of the different compositions show that electrical resistivity increases with germanium content. Pure germanium is the most resistive yet exhibited the best electrochemical performance at high current densities which indicates that electrical resistivity is not rate limiting for any of the tested compositions. PMID:25158125

  11. NiTiCu Shape Memory Alloy Characterization Through Microhardness Tests

    NASA Astrophysics Data System (ADS)

    Fabregat-Sanjuan, Albert; Ferrando, Francesc; De la Flor, Silvia

    2014-07-01

    NiTiCu alloys are one of the most investigated shape memory alloys (SMAs) because of their better performance as SMA actuators in a variety of industrial and engineering applications. However, NiTiCu alloys are strongly influenced by thermomechanical cycling (TMC), which causes degradation depending on the stress and strain level applied. Since heat treatment (HT) and TMC are essential for NiTiCu alloys, understanding how hardness evolves at different levels of TMC and different HT temperatures is a useful tool for characterizing the material. The aim of this paper is to investigate the relationship between hardness and different HT temperatures and different TMCs. All the microhardness tests were done below martensite finish temperature (Mf) because the apparent material hardness measured below Mf fairly reflects the relative strengthening of SMAs without involving martensitic transformation artifacts. Resistivity and break tensile tests were carried out as a first step in order to understand the effect of different HT temperatures. Microstructure was also examined to provide a basis for a mechanistic understanding of the effect of different HT temperatures. Next, the degradation of mechanical properties (functional fatigue) at different levels of TMC was evaluated to assess their relationship to the evolution of hardness. Finally, an attempt was made to establish a link between the increase in hardness and different HT temperatures with different levels of TMC.

  12. Microstructure and Precipitate's Characterization of the Cu-Ni-Si-P Alloy

    NASA Astrophysics Data System (ADS)

    Zhang, Yi; Tian, Baohong; Volinsky, Alex A.; Sun, Huili; Chai, Zhe; Liu, Ping; Chen, Xiaohong; Liu, Yong

    2016-04-01

    Microstructure of the Cu-Ni-Si-P alloy was investigated by transmission electron microscopy (TEM). The alloy had 551 MPa tensile strength, 226 HV hardness, and 36% IACS electrical conductivity after 80% cold rolling and aging at 450 °C for 2 h. Under the same aging conditions, but without the cold rolling, the strength, hardness, and electrical conductivity were 379 MPa, 216 HV, and 32% IACS, respectively. The precipitates identified by TEM characterization were δ-Ni2Si. Some semi-coherent spherical precipitates with a typical coffee bean contrast were found after aging for 48 h at 450 °C. The average diameter of the observed semi-coherent precipitates is about 5 nm. The morphology of the fracture surface was observed by scanning electron microscopy. All samples showed typical ductile fracture. The addition of P refined the grain size and increased the nucleation rate of the precipitates. The precipitated phase coarsening was inhibited by the small additions of P. After aging, the Cu-Ni-Si-P alloy can gain excellent mechanical properties with 804 MPa strength and 49% IACS conductivity. This study aimed to optimize processing conditions of the Cu-Ni-Si-P alloys.

  13. Effects of anodic oxidation and hydrothermal treatment on surface characteristics and biocompatibility of Ti-30Nb-1Fe-1Hf alloy

    NASA Astrophysics Data System (ADS)

    Ou, Shih-Fu; Chou, Hsin-Hua; Lin, Chao-Sung; Shih, Ching-Jui; Wang, Kuang-Kuo; Pan, Yung-Ning

    2012-06-01

    Anodic oxidation followed by hydrothermal treatment has been widely applied for surface modification of titanium alloys to precipitate a crystalline hydroxyapatite (HA) layer in order to achieve improved osteoconduction. A majority of the studies in the literature imposed relatively high powers to enhance Ca and P in the anodic oxide film (AOF). However, high powers have been found to cause deterioration of the adhesive strength in one of the author's previous study. In this study, a new electrolyte comprising calcium acetate monohydrate (CA), β-glycerophosphate disodium pentahydrate (β-GP) and HA powder was developed, and the Ti-30Nb-1Fe-1Hf alloy was anodized in this HA-containing electrolyte to a relatively low voltage. Results show that the AOF anodized in the HA-containing electrolyte exhibits a better HA forming ability during hydrothermal treatment, attributing to the presence of HA powder in the electrolyte that effectively enhances both the Ca content and Ca/P ratio in the AOF. On the other hand, the adhesive strength was little affected due to the decrease in size of the craters residing in the AOF. With respect to the biological responses, not much difference in biocompatibility of the treated and untreated Ti-Nb surfaces was obtained. However, the anodized and hydrothermally treated surface promotes the attachment of cells.

  14. Origin of nondetectable x-ray diffraction peaks in nanocomposite CuTiZr alloys

    NASA Astrophysics Data System (ADS)

    Jiang, J. Z.; Kato, H.; Ohsuna, T.; Saida, J.; Inoue, A.; Saksl, K.; Franz, H.; Stâhl, K.

    2003-10-01

    Microscopic structures of Cu60Ti10+xZr30-x (x=0 and 10) alloys have been investigated by transmission electron microscopy, x-ray diffraction (XRD) and differential scanning calorimeter (DSC). In the Cu60Ti10Zr30 samples annealed at 708 K for times ranging from 0 to 130 min, where the enthalpy of the first exothermic peak decreases by 80%, the corresponding XRD patterns still look similar to that for the as-prepared sample. However, the simulated XRD patterns for the pure Cu51Zr14 phase, which is the crystalline phase formed during the first exothermic reaction, with small grain sizes and defects clearly show a broadened amorphous-like feature. This might be the reason that no diffraction peaks from the nanocrystalline component were detected in the XRD patterns recorded for the as-cast or as-spun Cu60Ti10+xZr30-x (x=0 and 10) alloys and for the alloys annealed at lower temperatures, in which the enthalpy of the first exothermic peak has a significant reduction. The second exothermic peak found in DSC curves is due to the formation of another hexagonal phase, spacing group P63/mmc (194) and lattice parameters a=5.105 Å and c=8.231 Å.

  15. Preparation and characterisation of SOFC anodic materials based on Ce-Cu

    NASA Astrophysics Data System (ADS)

    Fuerte, A.; Valenzuela, R. X.; Daza, L.

    Ce-Cu mixed oxide precursors with varing Ce:Cu atomic ratio have been prepared by freeze-drying and microemulsion coprecipitation methods. Nanostructured particles having different properties have been obtained. Physicochemical properties have been studied with X-ray diffraction, UV-vis spectroscopy, nitrogen adsorption-desorption, mercury intrusion porosimetry, ICP-AES, conductivity measurement and thermal expansion coefficient. All samples show fluorite structure with slight copper surface enrichment for samples having high copper content. Microemulsion method allows the introduction of a large quantity of copper into the cerium oxide structure, obtaining a nanostructured mixed oxide of high surface area. On the other hand, freeze-drying samples does not show evidence of copper incorporation to the lattice of cerium oxide. All materials have a thermal expansion coefficient similar to other components of SOFC.

  16. Comparison of the Crystallization Behavior of Fe-Si-B-Cu and Fe-Si-B-Cu-Nb-Based Amorphous Soft Magnetic Alloys

    NASA Astrophysics Data System (ADS)

    Smith, Casey; Katakam, Shravana; Nag, Soumya; Zhang, Y. R.; Law, J. Y.; Ramanujan, Raju V.; Dahotre, Narendra B.; Banerjee, Rajarshi

    2014-06-01

    The role of the solute elements, copper, and niobium, on the different stages of de-vitrification or crystallization of two amorphous soft magnetic alloys, Fe73.5Si13.5B9Nb3Cu1, also referred to as FINEMET, and a Fe76.5Si13.5B9Cu1 alloy, a model composition without Nb, has been investigated in detail by coupling atom probe tomography and transmission electron microscopy. The effects of copper clustering and niobium pile-up at the propagating interface between the α-Fe3Si nanocrystals and the amorphous matrix, on the nucleation and growth kinetics have been addressed. The results demonstrate that while Cu clustering takes place in both alloys in the early stages, the added presence of Nb in FINEMET severely restricts the diffusivity of solute elements such as Cu, Si, and B. Therefore, the kinetics of solute partitioning and mobility of the nanocrystal/amorphous matrix interface is substantially slower in FINEMET as compared to the Fe76.5Si13.5B9Cu1 alloy. Consequently, the presence of Nb limits the growth rate of the α-Fe3Si nanocrystals in FINEMET and results in the activation of a larger no. of nucleation sites, leading to a substantially more refined microstructure as compared to the Fe76.5Si13.5B9Cu1 alloy.

  17. Evaluation of cerium oxide coated Cu cermets as inert anodes for aluminum electrowinning

    SciTech Connect

    Not Available

    1992-08-01

    Cu/NiFe{sub 2}O{sub 4} cermets were evaluated, with and without an in-situ deposited CEROX (TM; cerium oxide) coating, in 100 h laboratory A1 electrowinning tests. Bath ratio and current density were varied between tests and corrosion was determined by contamination of the aluminum and cryolite by cermet components (Cu, Fe, and Ni). Higher bath ratios of 1.5 to 1.6 led to less corrosion and thicker CEROX coatings. Lower current densities led to slightly less corrosion but much less oxidation of the Cu cermet substrate. At identical test conditions, the corrosion of the CEROX coated cermets was 1/7 that of an uncoated cermet. Corrosion was increased in CEROX coated cermets tested under unsaturated alumina conditions. The electrical conductivity of the CEROX coating was measured to be {approximately}0.2 ohm{sup {minus}1}cm{sup {minus}1}, resulting in a slight voltage penalty, depending on the thickness of the coating.

  18. Influence of Tin Additions on the Phase-Transformation Characteristics of Mechanical Alloyed Cu-Al-Ni Shape-Memory Alloy

    NASA Astrophysics Data System (ADS)

    Saud, Safaa N.; Hamzah, E.; Abubakar, T.; Bakhsheshi-Rad, H. R.; Mohammed, M. N.

    2016-07-01

    The influence of the addition of Sn to Cu-Al-Ni alloy as a fourth element with different percentages of 0.5, 1.0, and 1.5 wt pct on the microstructure, phase-transformation temperatures, mechanical properties, and corrosion behaviors was investigated. The modified and unmodified alloys were fabricated by mechanical alloying followed by microwave sintering. The sintered and homogenized alloys of Cu-Al-Ni-xSn shape-memory alloys had a refined particle structure with an average particle size of 40 to 50 µm associated with an improvement in the mechanical properties and corrosion resistance. With the addition of Sn, the porosity density tends to decrease, which can also lead to improvements in the properties of the modified alloys. The minimum porosity percentage was observed in the Cu-Al-Ni-1.0 wt pct Sn alloy, which resulted in enhancing the ductility, strain recovery, and corrosion resistance. Further increasing the Sn addition to 1.5 wt pct, the strength of the alloy increased because the highest volume fraction of precipitates was formed. Regarding the corrosion behavior, addition of Sn up to 1 wt pct increased the corrosion resistance of the base SMA from 2.97 to 19.20 kΩ cm2 because of formation of a protective film that contains hydrated tin oxyhydroxide, aluminum dihydroxychloride, and copper chloride on the alloy. However, further addition of Sn reduced the corrosion resistance.

  19. Novel Amorphous Fe-Zr-Si(Cu) Boron-free Alloys

    SciTech Connect

    Kopcewicz, M.; Grabias, A.; Latuch, J.; Kowalczyk, M.

    2010-07-13

    Novel amorphous Fe{sub 80}(Zr{sub x}Si{sub 20-x-y})Cu{sub y} boron-free alloys, in which boron was completely replaced by silicon as a glass forming element, have been prepared in the form of ribbons by a melt quenching technique. The X-ray diffraction and Moessbauer spectroscopy measurements revealed that the as-quenched ribbons with the composition of x = 6-10 at. % and y = 0, 1 at. % are predominantly amorphous. DSC measurements allowed the estimation of the crystallization temperatures of the amorphous alloys. The soft magnetic properties have been studied by the specialized rf-Moessbauer technique in which the spectra were recorded during an exposure of the samples to the rf field of 0 to 20 Oe at 61.8 MHz. Since the rf-collapse effect observed is very sensitive to the local anisotropy fields it was possible to evaluate the soft magnetic properties of amorphous alloys studied. The rf-Moessbauer studies were accompanied by the conventional measurements of the quasi-static hysteresis loops from which the magnetization and coercive fields were estimated. It was found that amorphous Fe-Zr-Si(Cu) alloys are magnetically very soft, comparable with those of the conventional amorphous B-containing Fe-based alloys.

  20. STM studies of the growth of the Si/Cu(110) surface alloy

    NASA Astrophysics Data System (ADS)

    Polop, C.; Sacedón, J. L.; Martín-Gago, J. A.

    1998-05-01

    The stages of the growth of the surface alloy c(2×2)-Si/Cu(110) have been analysed on the basis of scanning tunneling microscopy images and low electron energy diffraction (LEED) patterns. The formation of this interface goes through several stages as the Si coverage is increased. For a Si coverage ca 0.1 monolayer (ML), structured islands are observed on the surface. They are aligned along the < 1¯12> surface direction which corresponds to the Si-Si bonding direction in the atomic model. These islands grow and coalesce upon Si coverage, forming extended alloy areas. Defects, consisting of grouped atomic vacancies, along the < 1¯10> surface direction are observed at this stage of growth which are reflected on the corresponding LEED pattern as diffuse c(2×2) spots enlarged along the <001> surface direction. Complete and free of defects alloy terraces are observed for a Si coverage ca 0.5 ML, that is, when the completion of the overlayer alloy is attained. Atomic resolution STM images show a c(2×2) atomic arrangement which can be explained as a near coplanar substitution of Cu by Si atoms. Throughout the text the relationship between the growth stages and the perfection of the alloy layer is discussed.

  1. Hot Deformation Characteristics and Processing Maps of the Cu-Cr-Zr-Ag Alloy

    NASA Astrophysics Data System (ADS)

    Zhang, Yi; Chai, Zhe; Volinsky, Alex A.; Sun, Huili; Tian, Baohong; Liu, Ping; Liu, Yong

    2016-03-01

    The hot deformation behavior of the Cu-Cr-Zr-Ag alloy has been investigated by hot compressive tests in the 650-950 °C temperature and 0.001-10 s-1 strain rate ranges using Gleeble-1500D thermo-mechanical simulator. The microstructure evolution of the alloy during deformation was characterized using optical and transmission electron microscopy. The flow stress decreases with the deformation temperature and increases with the strain rate. The apparent activation energy for hot deformation of the alloy was 343.23 kJ/mol. The constitutive equation of the alloy based on the hyperbolic-sine equation was established to characterize the flow stress as a function of the strain rate and the deformation temperature. The processing maps were established based on the dynamic material model. The optimal processing parameters for hot deformation of the Cu-Cr-Zr-Ag alloy are 900-950 °C and 0.001-0.1 s-1 strain rate. The evolution of DRX microstructure strongly depends on the deformation temperature and the strain rate.

  2. Intrinsic fatigue crack growth rates for Al-Li-Cu-Mg alloys in vacuum

    NASA Technical Reports Server (NTRS)

    Slavik, D. C.; Blankenship, C. P., Jr.; Starke, E. A., Jr.; Gangloff, R. P.

    1993-01-01

    The influences of microstructure and deformation mode on inert environment intrinsic fatigue crack propagation were investigated for Al-Li-Cu-Mg alloys AA2090, AA8090, and X2095 compared to AA2024. The amount of coherent shearable delta-prime (Al3Li) precipitates and extent of localized planar slip deformation were reduced by composition (increased Cu/Li in X2095) and heat treatment (double aging of AA8090). Intrinsic growth rates, obtained at high constant K(max) to minimize crack closure and in vacuum to eliminate any environmental effect, were alloy dependent; da/dN varied up to tenfold based on applied Delta-K or Delta-K/E. When compared based on a crack tip cyclic strain or opening displacement parameter, growth rates were equivalent for all alloys except X2095-T8, which exhibited unique fatigue crack growth resistance. Tortuous fatigue crack profiles and large fracture surface facets were observed for each Al-Li alloy independent of the precipitates present, particularly delta-prime, and the localized slip deformation structure. Reduced fatigue crack propagation rates for X2095 in vacuum are not explained by either residual crack closure or slip reversibility arguments; the origin of apparent slip band facets in a homogeneous slip alloy is unclear.

  3. Accumulative Roll Bonding and Post-Deformation Annealing of Cu-Al-Mn Shape Memory Alloy

    NASA Astrophysics Data System (ADS)

    Moghaddam, Ahmad Ostovari; Ketabchi, Mostafa; Afrasiabi, Yaser

    2014-09-01

    Accumulative roll bonding is a severe plastic deformation process used for Cu-Al-Mn shape memory alloy. The main purpose of this study is to investigate the possibility of grain refinement of Cu-9.5Al-8.2Mn (in wt.%) shape memory alloy using accumulative roll bonding and post-deformation annealing. The alloy was successfully subjected to 5 passes of accumulative roll bonding at 600 °C. The microstructure, properties as well as post-deformation annealing of this alloy were investigated by optical microscopy, scanning electron microscopy, x-ray diffraction, differential scanning calorimeter, and bend and tensile testing. The results showed that after 5 passes of ARB at 600 °C, specimens possessed α + β microstructure with the refined grains, but martensite phases and consequently shape memory effect completely disappeared. Post-deformation annealing was carried out at 700 °C, and the martensite phase with the smallest grain size (less than 40 μm) was obtained after 150 s of annealing at 700 °C. It was found that after 5 passes of ARB and post-deformation annealing, the stability of SME during thermal cycling improved. Also, tensile properties of alloys significantly improved after post-deformation annealing.

  4. Accumulative Roll Bonding and Post-Deformation Annealing of Cu-Al-Mn Shape Memory Alloy

    NASA Astrophysics Data System (ADS)

    Moghaddam, Ahmad Ostovari; Ketabchi, Mostafa; Afrasiabi, Yaser

    2014-12-01

    Accumulative roll bonding is a severe plastic deformation process used for Cu-Al-Mn shape memory alloy. The main purpose of this study is to investigate the possibility of grain refinement of Cu-9.5Al-8.2Mn (in wt.%) shape memory alloy using accumulative roll bonding and post-deformation annealing. The alloy was successfully subjected to 5 passes of accumulative roll bonding at 600 °C. The microstructure, properties as well as post-deformation annealing of this alloy were investigated by optical microscopy, scanning electron microscopy, x-ray diffraction, differential scanning calorimeter, and bend and tensile testing. The results showed that after 5 passes of ARB at 600 °C, specimens possessed α + β microstructure with the refined grains, but martensite phases and consequently shape memory effect completely disappeared. Post-deformation annealing was carried out at 700 °C, and the martensite phase with the smallest grain size (less than 40 μm) was obtained after 150 s of annealing at 700 °C. It was found that after 5 passes of ARB and post-deformation annealing, the stability of SME during thermal cycling improved. Also, tensile properties of alloys significantly improved after post-deformation annealing.

  5. Influence of thermomechanical processing on the microstructure and properties of a Cu-Cr-P Alloy

    NASA Astrophysics Data System (ADS)

    Gao, N.; Tiainen, T.; Huttunen-Saarivirta, E.; Ji, Y.

    2002-08-01

    The microstructure and properties of a Cu-0.55 wt. % Cr-0.07 wt. % P alloy were studied by using optical microscopy, transmission electron microscopy, and the measurements of Vickers hardness and electrical conductivity after it was subjected to conventional aging and two thermomechanical treatments. The hardness increment resulting from the thermomechanical treatments was 50% higher than the increment produced by conventional aging. The thermomechanical procedure, including two aging steps (double aging), produced a 5% International Annealed Copper Standard (IACS) higher increase in conductivity than the procedure including a single aging step. However, the former procedure did not lead to more efficient hardening in the studied alloy than the latter procedure because during the second aging step extensive recovery or even the onset of recrystallization tended to suppress precipitation hardening to some extent. After being subjected to a thermomechanical treatment that included three cold-drawing steps and one aging step, the studied alloy showed a tensile strength of 550 MPa with a conductivity of 74% IACS. Based on the obtained results as well as on the comparison with other Cu-Cr type alloys, some suggestions were given for improving the thermomechanical processing route of the studied alloy.

  6. Electrochemical Corrosion Behavior of TiN-Coated Biomedical Ti-Cu Alloy Foam in Fluoride Containing Artificial Saliva

    NASA Astrophysics Data System (ADS)

    Mutlu, Ilven

    2014-07-01

    Highly porous Ti-Cu alloy foams were produced by powder metallurgy method for implant applications. Ti-Cu alloys were prepared with 3, 5, 7, and 10 wt pct Cu contents in order to determine optimum Cu addition. Cu addition enhances sinterability, and the Ti-Cu compacts were sintered at lower temperatures and times than pure Ti. Specimens were coated with a TiN film to enhance wear and corrosion resistance. Sintered specimens were precipitation hardened (aged) in order to increase mechanical properties. Corrosion properties of foams were examined by electrochemical techniques, such as potentiodynamic polarization, cyclic polarization, Tafel extrapolation, linear polarization resistance, and open-circuit potential measurement. Effect of Cu content, TiN coating, pH, and fluoride content of artificial saliva on electrochemical corrosion behavior of specimens was investigated.

  7. Environmental fatigue of an Al-Li-Cu alloy. I - Intrinsic crack propagation kinetics in hydrogenous environments

    NASA Technical Reports Server (NTRS)

    Piascik, Robert S.; Gangloff, Richard P.

    1991-01-01

    Deleterious environmental effects on steady-state, intrinsic fatigue crack propagation (FCP) rates (da/dN) in peak aged Al-Li-Cu alloy 2090 are established by electrical potential monitoring of short cracks with programmed constant delta K and K(sub max) loading. The da/dN are equally unaffected by vacuum, purified helium, and oxygen but are accelerated in order of decreasing effectiveness of aqueous 1 percent NaCl with anodic polarization, pure water vapor, moist air, and NaCl with cathodic polarization. While da/dN depends on delta K(sup 4.0) for the inert gases, water vapor and chloride induced multiple power-laws, and a transition growth rate 'plateau'. Environmental effects are strongest at low delta K. Crack tip damage is ascribed to hydrogen embrittlement because of the following: (1) accelerated da/dN due to part-per-million levels of H2O without condensation; (2) impeded molecular flow model predictions of the measured water vapor pressure dependence of da/dN as affected by mean crack opening; (3) the lack of an effect of film-forming O2; (4) the likelihood for crack tip hydrogen production in NaCl; and (5) the environmental and delta K-process zone volume dependencies of the microscopic cracking modes. For NaCl, growth rates decrease with decreasing loading frequency, with the addition of passivating Li2CO3, and upon cathodic polarization. These variables increase crack surface film stability to reduce hydrogen entry efficiency. The hydrogen environmental FCP resistance of 2090 is similar to other 2000 series alloys and is better than 7075.

  8. Environmental fatigue of an Al-Li-Cu alloy. Part 1: Intrinsic crack propagation kinetics in hydrogenous environments

    NASA Technical Reports Server (NTRS)

    Piascik, Robert S.; Gangloff, Richard P.

    1991-01-01

    Deleterious environmental effects on steady-state, intrinsic fatigue crack propagation (FCP) rates (da/dN) in peak aged Al-Li-Cu alloy 2090 are established by electrical potential monitoring of short cracks with programmed constant delta K and K(sub max) loading. The da/dN are equally unaffected by vacuum, purified helium, and oxygen but are accelerated in order of decreasing effectiveness by aqueous 1 percent NaCl with anodic polarization, pure water vapor, moist air, and NaCl with cathodic polarization. While da/dN depends on delta K(sup 4.0) for the inert gases, water vapor and chloride induced multiple power-laws, and a transition growth rate 'plateau'. Environmental effects are strongest at low delta K. Crack tip damage is ascribed to hydrogen embrittlement because of the following: (1) accelerated da/dN due to part-per-million levels of H2O without condensation; (2) impeded molecular flow model predictions of the measured water vapor pressure dependence of da/dN as affected by mean crack opening; (3) the lack of an effect of film-forming O2; (4) the likelihood for crack tip hydrogen production in NaCl, and (5) the environmental and delta K-process zone volume dependencies of the microscopic cracking modes. For NaCl, growth rates decrease with decreasing loading frequency, with the addition of passivating Li2CO3, and upon cathodic polarization. These variables increase crack surface film stability to reduce hydrogen entry efficiency. The hydrogen environmental FCP resistance of 2090 is similar to other 2000 series alloys and is better than 7075.

  9. Coating TiVCr hydrogen storage alloy on the anode gas diffusion layer of proton exchange membrane fuel cells to improve performance

    NASA Astrophysics Data System (ADS)

    Fang, Sheng-Yu; Huang, Rong-Hsin; Teoh, Lay Gaik; Hsueh, Kan-Lin; Chao, Wen-Kai; Tsai, Du-Cheng; Yang, Tse-Ning; Shieu, Fuh-Sheng

    2014-12-01

    In this study, a TiVCr hydrogen storage alloy was coated onto the anode gas diffusion layer (GDL) of proton exchange membrane fuel cells (PEMFCs) by direct-current sputtering to improve cell performance and durability. Scanning electron microscopy analysis indicated that the GDLs are well coated and that the TiVCr coating shows pyramidal protrusions. The single-cell performance of PEMFCs, in which the GDLs were coated with TiVCr hydrogen storage alloy as the anode, was investigated at cell temperatures of 25 and 65 °C (non-humidification and full-humidification conditions, respectively). The membrane-electrode assembly (MEA) with TiVCr hydrogen storage alloy-coated GDL (10 min sputtering time) exhibited optimal performance at 25 and 65 °C, with power densities 18.49% and 43.67%, respectively, higher than that without TiVCr hydrogen storage alloy coating. The MEA with the TiVCr-coated GDL obtained by 60 min of sputtering exhibited 90.6% greater durability under no-hydrogen flow conditions than the MEA without the TiVCr hydrogen storage alloy coating. These results demonstrate for the first time that GDLs coated with a hydrogen storage alloy such as TiVCr may be applied in PEMFCs to improve their performance and durability.

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  11. Nanostructured Cu-Cr alloy with high strength and electrical conductivity

    SciTech Connect

    Islamgaliev, R. K. Nesterov, K. M.; Bourgon, J.; Champion, Y.; Valiev, R. Z.

    2014-05-21

    The influence of nanostructuring by high pressure torsion (HPT) on strength and electrical conductivity in the Cu-Cr alloy has been investigated. Microstructure of HPT samples was studied by transmission electron microscopy with special attention on precipitation of small chromium particles after various treatments. Effect of dynamic precipitation leading to enhancement of strength and electrical conductivity was observed. It is shown that nanostructuring leads to combination of high ultimate tensile strength of 790–840 MPa, enhanced electrical conductivity of 81%–85% IACS and thermal stability up to 500 °C. The contributions of grain refinement and precipitation to enhanced properties of nanostructured alloy are discussed.

  12. Deep-cryogenic-treatment-induced phase transformation in the Al-Zn-Mg-Cu alloy

    NASA Astrophysics Data System (ADS)

    Li, Chun-mei; Cheng, Nan-pu; Chen, Zhi-qian; Guo, Ning; Zeng, Su-min

    2015-01-01

    An aluminum alloy (Al-Zn-Mg-Cu) subjected to deep cryogenic treatment (DCT) was systematically investigated. The results show that a DCT-induced phase transformation varies the microstructures and affects the mechanical properties of the Al alloy. Both Guinier-Preston (GP) zones and a metastable η' phase were observed by high-resolution transmission electron microscopy. The phenomenon of the second precipitation of the GP zones in samples subjected to DCT after being aged was observed. The viability of this phase transformation was also demonstrated by first-principles calculations.

  13. Optical properties of random alloys: application to CuAu and NiPt

    NASA Astrophysics Data System (ADS)

    Krishna Saha, Kamal; Mookerjee, Abhijit

    2005-07-01

    In an earlier paper we presented a formulation for the calculation of the configuration-averaged optical conductivity in random alloys. Our formulation is based on the augmented-space theorem introduced by one of us (Mookerjee 1973 J. Phys. C: Solid State Phys. 6 1340). In this communication we shall combine the augmented space methodology with the tight-binding linear muffin-tin orbital technique (TB-LMTO) to study the optical conductivities of two alloys, CuAu and NiPt.

  14. Interfacial Heat Transfer during Die Casting of an Al-Si-Cu Alloy

    NASA Astrophysics Data System (ADS)

    Hamasaiid, A.; Wang, G.; Davidson, C.; Dour, G.; Dargusch, M. S.

    2009-12-01

    The relationship between in-cavity pressure, heat flux, and heat-transfer coefficient during high-pressure die casting of an Al-9 pct Si-3 pct Cu alloy was investigated. Detailed measurements were performed using infrared probes and thermocouple arrays that accurately determine both casting and die surface temperatures during the pressure die casting of an aluminum A380 alloy. Concurrent in-cavity pressure measurements were also performed. These measurements enabled the correlation between in-cavity pressure and accurate heat-transfer coefficients in high-pressure die-casting operations.

  15. Kinetically controlled synthesis of Pt-Cu alloy concave nanocubes with high-index facets for methanol electro-oxidation.

    PubMed

    Qi, Yue; Bian, Ting; Choi, Sang-Il; Jiang, Yingying; Jin, Chuanhong; Fu, Maoshen; Zhang, Hui; Yang, Deren

    2014-01-18

    Pt-Cu alloy concave nanocubes enclosed by high-index {511} facets were synthesized in high yields and exhibited substantially enhanced electrocatalytic properties for methanol oxidation relative to commercial Pt/C. PMID:24271020

  16. New Cu(TiBN x ) copper alloy films for industrial applications

    NASA Astrophysics Data System (ADS)

    Lin, Chon-Hsin

    2016-06-01

    In this study, I explore a new type of copper alloy, Cu(TiBN x ), films by cosputtering Cu and TiB within an Ar/N2 gas atmosphere on Si substrates. The films are then annealed for 1 h in a vacuum environment at temperatures up to 700 °C. The annealed films exhibit not only excellent thermal stability and low resistivity but also little leakage current and strong adhesion to the substrates while no Cu/Si interfacial interactions are apparent. Within a Sn/Cu(TiBN x )/Si structure at 200 °C, the new alloy exhibits a minute dissolution rate, which is lower than that of pure Cu by at least one order of magnitude. Furthermore, the new alloy’s consumption rate is comparable to that of Ni commonly used in solder joints. The new films appear suitable for some industrial applications, such as barrierless Si metallization and new wetting and diffusion barrier layers required in flip-chip solder joints.

  17. Structural and magnetic properties of Cu-alloyed FePd films

    NASA Astrophysics Data System (ADS)

    Polit, A.; Makarov, D.; Brombacher, C.; Krupinski, M.; Perzanowski, M.; Zabila, Y.; Albrecht, M.; Marszałek, M.

    2015-05-01

    Multilayer films [Cu(d Å)/Fe(9 Å)/Pd(11 Å)]5 were deposited at room temperature on Si(001)/SiO2(400 nm) substrates. In order to induce chemical L10 ordering, the as-deposited samples were post-annealed by rapid thermal annealing (RTA) at 600 °C for 90 s followed additionally by heating in ultra-high vacuum (UHV) at 700 °C up to several hours. In this study the impact of post-annealing on the structural and magnetic properties of FePdCu alloy films in dependence on the Cu content was investigated. It was found that the addition of Cu to the FePd alloy has a strong influence on the chemical ordering process and the (001) texture formation. After the RTA treatment only an isotropic distribution of the easy axis of magnetization with coercive fields in the range of a few hundred mT was observed. In contrast, samples which were additionally heated for 1 h at 700 °C revealed an out-of-plane easy axis of magnetization with an effective magnetic anisotropy of about 2×105 J/m3 for the sample containing 10 at% of Cu.

  18. Solid Effect Between Quadrupolar Transitions in Dilute Cu-Pd Alloys

    NASA Astrophysics Data System (ADS)

    Konzelmann, K.; Majer, G.; Seeger, A.

    1996-06-01

    The paper investigates the Dynamic Solid Effect (DSE) in Nuclear Quadrupole Double Reso-nance (NQDOR) on a system (dilute alloys of CuPd with 8, 42, 210, or 1000 at.ppm Pd) chosen for its simplicity and the possibility to test the theoretical concepts on which the experimental tech-niques (in particular the so-called Berthier-Minier technique for exhibiting the DSE) are based. NQDOR allows to observe the transitions between the Cu nuclear energy levels split by the quadrupolar interaction with the electric field gradients generated by nearby Pd atoms even in dilute alloys, in which the fraction of Cu nuclei experiencing a given field gradient is very small. The DSE permits transitions at frequencies corresponding to the sums or differences of quadrupolar level splittings at neighbouring nuclei and thus gives access to information on the spatial correlation of nuclei accessible to NQDOR studies. The DSE information is shown to be in full accord with the conclusions drawn earlier, on the basis of line-intensity arguments, on the assignment of quadrupo-lar transitions to the first four shells of Cu nuclei surrounding isolated Pd atoms but, in addition, allows to identify the low-frequency NQDOR lines associated with Cu nuclei in the fifth and sixth shells.

  19. Oxidation of Fe-W Alloy Electrodeposits for Application to Anodes as Lithium Ion Batteries

    NASA Astrophysics Data System (ADS)

    Su, Changwei; Ye, Mengchao; Zhon, Linxing; Hou, Jianping; Li, Junmin; Guo, Junming

    2016-12-01

    A citrate-ammonia bath was selected to electrodeposit Fe-W alloys, which exhibit a crystalline structure even if the content of W in the Fe-W alloy is up to 37.8wt%. Those alloys could be oxidized partly at 700∘C. Resultant oxides were composed of Fe2O3, Fe3O4 and amorphous products. The composite oxides presented better electrochemical properties than those of the Fe2O3 and Fe3O4 composite formed by oxidation of Fe deposits. For instance, such an electrode demonstrates the reversible capacity of up to 2438.3mAhg-1 (in terms of incremental oxygen) after 100 charge-discharge cycles, while the electrodes of Fe2O3 and Fe3O4 composites formed by oxidation of Fe deposits were of only 667.5mAhg-1.

  20. Highly-enhanced reflow characteristics of sputter deposited Cu alloy thin films for large scale integrated interconnections

    SciTech Connect

    Onishi, Takashi; Mizuno, Masao; Yoshikawa, Tetsuya; Munemasa, Jun; Mizuno, Masataka; Kihara, Teruo; Araki, Hideki; Shirai, Yasuharu

    2011-08-01

    An attempt to improve the reflow characteristics of sputtered Cu films was made by alloying the Cu with various elements. We selected Y, Sb, Nd, Sm, Gd, Dy, In, Sn, Mg, and P for the alloys, and ''the elasto-plastic deformation behavior at high temperature'' and ''the filling level of Cu into via holes'' were estimated for Cu films containing each of these elements. From the results, it was found that adding a small amount of Sb or Dy to the sputtered Cu was remarkably effective in improve the reflow characteristics. The microstructure and imperfections in the Cu films before and after high-temperature high-pressure annealing were investigated by secondary ion micrographs and positron annihilation spectroscopy. The results imply that the embedding or deformation mechanism is different for the Cu-Sb alloy films compared to the Cu-Dy alloy films. We consider that the former is embedded by softening or deformation of the Cu matrix, which has a polycrystalline structure, and the latter is embedded by grain boundary sliding.

  1. Direct Determination of the Metastable Liquid Miscibility Gap in Undercooled Cu-Co Alloys

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

    Bulk Cu-Co alloys at compositions ranging from 10 to 80 wt pct Co were highly undercooled using a melt fluxing technique. The metastable liquid separation boundary has been directly determined from the measured temperature-time profiles. It was found that the critical point of the miscibility gap is slightly shifted towards the Co side and about 90 K below the liquidus. A droplet-shaped microstructure was observed for all solidified specimens (Cu- 10 to 80 wt pct Co), when the melts were undercooled into the metastable miscibility boundary.

  2. Magnetic properties of nanocrystalline FeCuNb(Sb/W)SiB alloys

    SciTech Connect

    Degro, J.; Vojtanik, P.; Konc, M.; Zentko, A.; Csach, K.; Ocelik, V.

    1994-03-01

    The magnetic relaxation {Delta}r/r, the perminvar critical field H{sub CR}, the initial susceptibility {chi}{sub 10}, the coercive field H{sub c} as a function of annealing temperature in Fe{sub 73.5}Cu{sub 1}Nb{sub 2.95}Sb{sub 0.05}Si{sub 13.5}B{sub 9} and Fe{sub 73.5}Cu{sub 1}W{sub 3}Si{sub 13.5}B{sub 9} alloys were investigated. DSC measurements and thermomagnetic analyses were also done. The results using random anisotropy model can be explained.

  3. Preparation and investigation of the quaternary alloy CuTaInSe{sub 3}

    SciTech Connect

    Grima-Gallardo, P. Munoz, M.; Duran, S.; Delgado, G.E.; Quintero, M.; Ruiz, J.

    2007-12-04

    Polycrystalline samples of the quaternary alloy CuTaInSe{sub 3} were prepared by the usual melt and anneal technique. The analysis of the diffraction pattern indicates a single phase which indexes as a tetragonal chalcopyrite-like structure with lattice parameters a = 5.7837 {+-} 0.0002 A; c = 11.6208 {+-} 0.0007 A and V = 389 {+-} 1 A{sup 3}. Differential thermal analysis shows that the melting transition of CuTaInSe{sub 3} is incongruent with large liquid + solids regions.

  4. Thermodynamics calculation of reactions between phosphorus and main elements in Al-Si-Cu alloys

    NASA Astrophysics Data System (ADS)

    Li, Wangxing; Zhang, Ying; Yi, Danqing; Kong, Fanxiao; Chen, Xingyu

    2011-05-01

    The Gibbs free energy was calculated between phosphorus and the main elements in Al-Si-Cu alloys sampled as A390 to study the reaction process and give theoretical directions for the adding of phosphorus in industry. The results show that the elements such as aluminum, silicon, and copper have the capabilities to react with phosphorus according to the preference of Al, Cu, Si. As temperature increases, the reactions between phosphorus and the elements become more difficult. If aluminum is in existence, the phosphides of other elements will transform to aluminum phosphide.

  5. Effect of thermally stable Cu- and Mg-rich aluminides on the high temperature strength of an AlSi12CuMgNi alloy

    SciTech Connect

    Asghar, Z.

    2014-02-15

    The internal architecture of an AlSi12CuMgNi piston alloy, revealed by synchrotron tomography, consists of three dimensional interconnected hybrid networks of Cu-rich aluminides, Mg-rich aluminides and eutectic/primary Si embedded in an α-Al matrix. The strength at room temperature and at 300°C is studied as a function of solution treatment time at 490°C and compared with results previously reported for an AlSi12Ni alloy. The addition of 1 wt% Cu and 1 wt% Mg to AlSi12CuMgNi increases the room temperature strength by precipitation hardening while the strength at 300°C is similar for both alloys in as-cast condition. The strength of AlSi12CuMgNi decreases with solution treatment time and stabilizes at 4 h solution treatment. The effect of solution treatment time on the strength of the AlSi12CuMgNi alloy is less pronounced than for the AlSi12Ni alloy both at room temperature and at 300°C. - Highlights: • The 3D microstructure of AlSi12CuMgNi is revealed by synchrotron tomography. • An imaging analysis procedure to segment phases with similar contrasts is presented. • 1 wt% Cu and Mg results in the formation of 3D networks of rigid phases. • AlSi12CuMgNi is stronger than AlSi12Ni owing to the stability of the 3D networks.

  6. Factors Affecting the Hydrogen Environment Assisted Cracking Resistance of an Al-Zn-Mg-(Cu) Alloy

    SciTech Connect

    G.A. Young; J.R. Scully

    2001-09-12

    It is well established that Al-Zn-Mg-(Cu) aluminum alloys are susceptible to hydrogen environment assisted cracking (HEAC) when exposed to aqueous environments. In Al-Zn-Mg-Cu alloys, overaged tempers are commonly used to increase HEAC resistance at the expense of strength. 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). When freshly bared coupons of AA 7050 are exposed to 90 C, 90% RH air, hydrogen ingress follows inverse-logarithmic-type kinetics and is equivalent for underaged (HEAC susceptible) and overaged (HEAC resistant) tempers. However, when the native oxide is allowed to form (24 hrs in 25 C, 40% RH lab air) prior to exposure to 90 C, 90% RH air, underaged alloy shows significantly greater hydrogen ingress than the overaged alloy. Humid air is a very aggressive environment producing local ({approx}1{micro}m) hydrogen concentrations in excess of 10,000 wt. ppm at 90 C. In the copper bearing alloy, overaging also effects the apparent diffusivity of hydrogen. As AA 7050 is aged from underaged {yields} peak aged {yields} overaged, the activation energy for hydrogen diffusion increases and the apparent diffusivity for hydrogen decreases, In the low copper alloy, overaging has little effect on hydrogen diffusion. Comparison of the apparent activation energies for hydrogen diffusion and for K independent (stage II) crack growth

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

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  8. Rapid synthesis of three-dimensional network structure CuO as binder-free anode for high-rate sodium ion battery

    NASA Astrophysics Data System (ADS)

    Chen, Chengcheng; Dong, Yanying; Li, Songyue; Jiang, Zhuohan; Wang, Yijing; Jiao, Lifang; Yuan, Huatang

    2016-07-01

    We report on the preparation of the three dimensional (3D) network structure CuO by rapid and facile engraving method and their application as high rate anode for sodium ion battery. The CuO is rapidly synthesized by in-situ etched and oxidated the specified Cu foils within 15 min. It shows the 3D network architecture with flower-like nanosheets connected by nanowires, which provides the porous structure, short ion diffusion pathway and collaborative electronic transmission. Furthermore, the etched CuO can be directly used as anode for sodium ion battery without polymer additions or conductive agents. The electrodes exhibit excellent electrochemical performance with a high capacity of 680 mAh·g-1 at 50 mA g-1 and a reversible capacity of 280 mAh·g-1 at 1000 mA g-1. In addition, the electrochemical reaction and detail charge/discharge process are carefully explored to discover the conversion reaction routes and the recession reason. Thus, the 3D network structure CuO might open an insight for transition-metal oxides as energy storage materials.

  9. Zn ion post-implantation-driven synthesis of CuZn alloy nanoparticles in Cu-preimplanted silica and their thermal evolution.

    PubMed

    Jia, Guangyi; Xu, Rong; Mu, Xiaoyu; Liu, Changlong

    2013-12-26

    Cu nanoparticles (NPs) were fabricated in silica by 45 keV Cu ion implantation at a fluence of 1.0 × 10(17) cm(-2) and were then subjected to implantation of 50 keV Zn ions at fluences of 1.0 × 10(16), 5.0 × 10(16), and 10.0 × 10(16) cm(-2), respectively. Our results clearly show that post Zn ion implantation could significantly modify structures and components of the preformed Cu NPs and thus the corresponding surface plasmon resonance (SPR) absorption can be modulated in a wide range. In particular, CuZn alloy NPs with unique SPR absorption were synthesized in Cu-implanted silica followed by Zn ion implantation at a fluence of 5.0 × 10(16) cm(-2). During subsequent annealing, two distinguished processes concerning CuZn alloy NPs (i.e., realloying and dealloying) were found that directly result from thermally driven diffusion of Zn atoms. Moreover, owing to Zn diffusion, lots of core-shell nanostructures consisting of Zn-related compound shells around Cu cores were observed after annealing at 500 °C and higher. The underlying mechanism concerning the formation and decomposition of CuZn alloy NPs is discussed and presented. PMID:24283510

  10. Precisely Controlled Synthesis of High Quality Kesterite Cu2ZnSnS4 Thin Film via Co-Electrodeposited CuZnSn Alloy Film.

    PubMed

    Hreid, Tubshin; Tiong, Vincent Tiing; Cai, Molang; Wang, Hongxia; Will, Geoffrey

    2016-06-01

    In this work, a facile co-electrodeposition method was used to fabricate CuZnSn alloy films where the content of copper, zinc and tin could be precisely controlled through manipulating the mass transfer process in the electrochemical deposition. By finely tuning the concentration of the cations of Cu2+, Zn2+ and Sn2+ in the electrochemical bath solution, uniform CuZnSn film with desired composition of copper poor and zinc rich was made. Sulphurisation of the CuZnSn alloy film led to the formation of compact and large grains Cu2ZnSnS4 thin film absorber with an optimum composition of Cu/(Zn+Sn) ≈ 0.8, Zn/Sn ≈ 1.2. Both SEM morphology and EDS mapping results confirmed the uniformity of the CuZnSn and Cu2ZnSnS4 films and the homogeneous distribution of Cu, Zn, Sn and S elements in the bulk films. The XRD and Raman measurements indicated that the synthesized Cu2ZnSnS4 film was kesterite phase without impurities detected. Photoelectrochemical tests were carried out to evaluate the CZTS film's photocurrent response under illumination of green light. PMID:27427618

  11. Ab Initio Analysis of Guinier–Preston–Bagaryatsky Zone Nucleation in Al-Cu-Mg Alloys

    SciTech Connect

    Kovarik, Libor; Mills, M. J.

    2012-05-01

    Due to the inherit difficulties associated with microstructure characterization in the early stages of aging, the origin of rapid hardening in Al-Cu-Mg alloys remains a poorly understood and controversial issue. This works addresses the precipitation processes in the early stages by ab-initiomodeling of GPB zone nucleation. We derive the structural nature of GPB zone nuclei and establish that the nucleation starts with 1D-GPB1 crystals, which represent thermodynamically stable configurations at the size scale previously associated only with solute clusters. It is also established that the 1D-GPB1 can form very rapidly due a simple structural transition from FCC based configurations (clusters). The formation of GPB zones in the early stages of aging is validated by comparison with previous experimental measurements. Based on previous experimental evidence, it is postulated that GPB zones rather than solute clusters may be able to rationalize the rapid hardening in the Al-Cu-Mg alloys.

  12. Localized depth distribution in the bombarded surface of AgCu alloy

    NASA Astrophysics Data System (ADS)

    Wang, Wenmin; Wang, Zhenxia; Lu, Rongrong; Zhu, Fuying; Wu, Xiankang; Guo, Yingmei; Zhu, Jieqing

    1995-09-01

    Combined with electron microbeam techniques such as scanning electron microscopy and electron-induced X-ray emission, a helium microbeam is used to study the effect of Ar + ion bombardment on the surface of a binary alloy Ag 37Cu 63 by particle-induced X-ray emission and Rutherford backscattering. A pronounced change of the surface concentration and depth profile has been found at both Cu-enriched solid solution micro-region and Ag-enriched eutectic mixture micro-region on the alloy surface due to ion bombardment. The preferential sputtering of Ag and bombardment-induced surface segregation is suggested to be attributed to the composition change in the near-surface regions. A superposition of depth distributions determined from different micro-phase-regions is experimentally confirmed.

  13. Calculation of Phonon Conductivity and Seebeck Coefficient in Cu-Ni Alloy

    NASA Astrophysics Data System (ADS)

    Konishi, Yusuke; Asai, Yoshihiro

    2015-03-01

    In recent years, thermoelectric materials have been attracting a lot of attention because they are expected to be applied for utilization of waste heat. Many kinds of materials are studied for this purpose; semiconductors, alloys, organic materials, etc. 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. Although this material is a great candidate for a thermoelectric material, we need to find the condition for a large thermoelectric coefficient that requires a large Seebeck coefficient, large electric conductivity, and small phonon conductivity. We calculated phonon conductivity in Cu-Ni alloy by using nonequilibrium molecular dynamics simulation and calculated Seebeck coefficients via ab-initio methods.

  14. Characterization of ultrafine grained Cu-Ni-Si alloys by electron backscatter diffraction

    NASA Astrophysics Data System (ADS)

    Altenberger, I.; Kuhn, H. A.; Gholami, M.; Mhaede, M.; Wagner, L.

    2014-08-01

    A combination of rotary swaging and optimized precipitation hardening was applied to generate ultra fine grained (UFG) microstructures in low alloyed high performance Cu-based alloy CuNi3Si1Mg. As a result, ultrafine grained (UFG) microstructures with nanoscopically small Ni2Si-precipitates exhibiting high strength, ductility and electrical conductivity can be obtained. Grain boundary pinning by nano-precipitates enhances the thermal stability. Electron channeling contrast imaging (ECCI) and especially electron backscattering diffraction (EBSD) are predestined to characterize the evolving microstructures due to excellent resolution and vast crystallographic information. The following study summarizes the microstructure after different processing steps and points out the consequences for the most important mechanical and physical properties such as strength, ductility and conductivity.

  15. Preparation, Characterization and Mechanical Properties of Cu-Sn Alloy/Graphite Composites

    NASA Astrophysics Data System (ADS)

    Dong, Ruifeng; Cui, Zhenduo; Zhu, Shengli; Xu, Xu; Yang, Xianjin

    2014-10-01

    Ni-B coating was prepared on the surface of graphite particles using the electroless plating method. The Ni-B coating was composed of spherical grains with average diameter of 80 nm. The phases of Ni-B coating were indexed as nanosized crystal Ni phase and amorphous Ni-B phase. Cu-Sn alloy/graphite composites with 0.5, 1.0, 1.5, and 2.0 wt pct graphite contents were synthesized by the powder metallurgy method. Ni-B coating improved the wettability and bonding strength between the Cu-Sn alloy and graphite. The composite with Ni-B coated graphite exhibited higher density, hardness, and compression strength compared with the composites with bare graphite. The crack propagation mechanism of the composites was also analyzed.

  16. The electrical conductivity of CuCrZr alloy after SPD processing

    NASA Astrophysics Data System (ADS)

    Lipińska, M.; Bazarnik, P.; Lewandowska, M.

    2014-08-01

    CuCrZr alloys exhibit very good relation between mechanical properties and electrical conductivity. However, for its use in some advanced applications improvement of mechanical strength while preserving high electrical conducting is required. Therefore, in this work a CuCrZr alloy was subjected to a series of thermo-mechanical treatments, including solution annealing and water quenching, SPD processing (using hydrostatic extrusion and ECAP) as well as aging in order to improve mechanical strength. The influence of these processing procedures on microstructure features and mechanical properties was determined by TEM observation and microhardness measurements, respectively. Electrical conductivity of the samples was measured by four-points method. The results have shown that it is possible to improve mechanical strength while preserving good electrical conductivity by a proper combination of SPD processing and heat treatment.

  17. Improvement of lithium storage performance of Sn-alloy anode materials by a polypyrrole protective layer

    NASA Astrophysics Data System (ADS)

    Peng, Peng; Wen, Zhaoyin; Liu, Yu; Jin, Jun

    2015-01-01

    The SnO2-based anode with improved reversible capacity and cyclability was achieved by employing a protective layer composed of crosslinked polypyrrole nanowires. Scanning electron microscopy measurement was performed to characterize the surface and cross section morphology of electrodes before and after cycling. The crosslinked polypyrrole nanowire protective layer with good elasticity adhered to the SnO2 surface could form a network, leading to buffer the volumetric swelling of active materials during the lithiation/delithiation process. A good cycling stability and an excellent rate capability of the modified electrode were achieved.

  18. The effect of milling time on the synthesis of Cu54Mg22Ti18Ni6 alloy

    NASA Astrophysics Data System (ADS)

    Kursun, C.; Gogebakan, M.

    2016-03-01

    In the present work, nanocrystalline Cu54Mg22Ti18Ni6 alloy was produced by mechanical alloying from mixtures of pure crystalline Cu, Mg, Ti and Ni powders using a Fritsch planetary ball mill with a ball to powder ratio of 10:1. Morphological changes, microstructural evolution and thermal behaviour of the Cu-Mg-Ti-Ni powders at different stages of milling were characterised by X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray detection (SEM/EDX) and differential thermal analysis (DTA). This alloy resulted in formation of single phase solid solution with FCC structure α-Cu (Mg, Ti, Ni) after 80 h of milling. In the initial stage of milling different sized and shaped elemental powders became uniform during mechanical alloying. The homogeneity of the Cu54Mg22Ti18Ni6 alloy increased with increasing milling time. The EDX result also confirmed the compositional homogeneity of the powder alloy. The crystallite size of alloy was calculated below 10 nm from XRD data.

  19. Microstructural evolution of Cu-1at% Ti alloy aged in a hydrogen atmosphere and its relation with the electrical conductivity.

    PubMed

    Semboshi, Satoshi; Al-Kassab, Talaat; Gemma, Ryota; Kirchheim, Reiner

    2009-04-01

    Copper alloys with titanium additions between 1 and 6at% Ti emerge currently as attractive conductive materials for electrical and electronic commercial products, since they exhibit superior mechanical and electrical properties. However, their electrical conductivity is reduced owing to the residual amount of Ti solutes in the Cu solid solution (Cu(ss)) phase. Since Cu shows only poor reactivity with hydrogen (H), while Ti exhibits high affinity to it, we were inspired by the idea that hydrogenation of Cu-Ti alloys would influence their microstructure, resulting in a significant change of their properties. In this contribution, the influence of aging under a deuterium (D(2)) atmosphere of Cu-1at% Ti alloys on their microstructure is investigated to explore the effects on the electrical conductivity. The specimens were investigated by means of transmission electron microscopy (TEM), field ion microscopy (FIM), computer-aided field ion image tomography (cFIIT), and atom probe tomography (APT). At an early aging stage at 623K in a D(2) atmosphere of 0.08MPa, ellipsoidal alpha-Cu(4)Ti precipitates are formed in the alloy, and during subsequent aging, delta-TiD(2) is competitively nucleated instead of growth of alpha-Cu(4)Ti particles. The co-precipitation of alpha-Cu(4)Ti and delta-TiD(2) efficiently reduces the Ti concentration of Cu(ss) matrix, particularly in the later aging stages in comparison to the aging in vacuum conditions. The electrical conductivity of the alloy aged in the D(2) atmosphere increases steeply up to 48% International Annealed Copper Standard (IACS) after 1030h, while it saturates to approximately 20% IACS in the alloy aged in vacuum. The outstanding increase of electrical conductivity during aging in D(2) atmosphere can be basically explained by the reduction of Ti solute concentration in Cu(ss) matrix. PMID:19243888

  20. In situ corrosion analysis of Al-Zn-In-Mg-Ti-Ce sacrificial anode alloy

    SciTech Connect

    Ma Jingling Wen Jiuba; Zhai Wenxia; Li Quanan

    2012-03-15

    The corrosion behaviour of Al-5Zn-0.02In-1Mg-0.05Ti-0.5Ce (wt.%) alloy has been investigated by immersion test, scanning electron microscopy, energy dispersive X-ray detector, electrochemical impedance spectroscopy and electrochemical noise. The results show that there exist different corrosion types of the alloy in 3.5% NaCl solution with the immersion time. At the initial stage of immersion, pitting due to the precipitates predominates the corrosion with a typical inductive loop at low frequencies in electrochemical impedance spectroscopy. The major precipitates of the alloy are MgZn{sub 2} and Al{sub 2}CeZn{sub 2} particles. The corrosion potentials of the bulk MgZn{sub 2} and Al{sub 2}CeZn{sub 2} alloys are negative with respect to that of {alpha}-Al, so the MgZn{sub 2} and Al{sub 2}CeZn{sub 2} precipitates can act as activation centre and cause the pitting. In the late corrosion, a relative uniform corrosion predominates the corrosion process controlled by the dissolution/precipitation of the In ions and characterized by a capacitive loop at medium-high frequencies in electrochemical impedance spectroscopy. The potential noise of the pitting shows larger amplitude fluctuation and lower frequency, but the potential noise of the uniform corrosion occurs with smaller amplitude fluctuation and higher frequency.

  1. Relaxation process of Fe(CuNb)SiB amorphous alloys investigated by dynamical calorimetry

    SciTech Connect

    Zhu, J.; Clavaguera-Mora, M.T.; Clavaguera, N.

    1997-03-01

    Differential scanning calorimetry and dynamic differential scanning calorimetry were used to analyze the relaxation process of Fe(CuNb)SiB amorphous alloys. The Curie temperature (T{sub C}) evolution of the amorphous phase during relaxation as a function of heating rate, time and pre-annealing temperature were measured. Two distinct relaxation processes are observed, consequent with topological and chemical short range order changes. {copyright} {ital 1997 American Institute of Physics.}

  2. Low Temperature Anomalies in the Plasticity of Cu-Ti Alloys

    NASA Astrophysics Data System (ADS)

    Moriya, Takeshi; Murata, Yasuo; Murase, Shinichi; Yoshimura, Osamu

    1991-12-01

    Low temperature anomalies in the flow stress were found for the super saturated alloys of Cu-5 at.%Ti below about 40 K. Similar anomalies were also found for the specimens decomposed spinodally. These are consistent with our previous model. The shoulders at higher temperatures on the stress-temperature curves were interpreted as corresponding to the onset of short ranged unzippings generally accompanied by the transition from over to under damping mode of dislocation oscillations.

  3. High permeance sulfur tolerant Pd/Cu alloy membranes

    SciTech Connect

    Ma, Yi Hua; Pomerantz, Natalie

    2014-02-18

    A method of making a membrane permeable to hydrogen gas (H.sub.2.uparw.) is disclosed. The membrane is made by forming a palladium layer, depositing a layer of copper on the palladium layer, and galvanically displacing a portion of the copper with palladium. The membrane has improved resistance to poisoning by H.sub.2S compared to a palladium membrane. The membrane also has increased permeance of hydrogen gas compared to palladium-copper alloys. The membrane can be annealed at a lower temperature for a shorter amount of time.

  4. Evaluation of high strength, high conductivity CuNiBe alloys for fusion energy applications

    SciTech Connect

    Zinkle, Steven J

    2014-06-01

    The unirradiated tensile properties for several different heats and thermomechanical treatment conditions of precipitation strengthened Hycon 3HPTM CuNiBe (Cu-2%Ni-0.35%Be in wt.%) have been measured over the temperature range of 20-500 C for longitudinal and long transverse orientations. The room temperature electrical conductivity has also been measured for several heats, and the precipitate microstructure was characterized using transmission electron microscopy. The CuNiBe alloys exhibit very good combination of strength and conductivity at room temperature, with yield strengths of 630-725 MPa and electrical conductivities of 65-72% International Annealed Copper Standard (IACS). The strength remained relatively high at all test temperatures, with yield strengths of 420-520 MPa at 500 C. However, low levels of ductility (<5% uniform elongation) were observed at test temperatures above 200-250 C, due to flow localization near grain boundaries (exacerbated by having only 10-20 grains across the gage thickness of the miniaturized sheet tensile specimens). Scanning electron microscopy observation of the fracture surfaces found a transition from ductile transgranular to ductile intergranular fracture with increasing test temperature. Fission neutron irradiation to a dose of ~0.7 displacements per atom (dpa) at temperatures between 100 and 240 C produced a slight increase in strength and a significant decrease in ductility. The measured tensile elongation increased with increasing irradiation temperature, with a uniform elongation of ~3.3% observed at 240 C. The electrical conductivity decreased slightly following irradiation, due to the presence of defect clusters and Ni, Zn, Co transmutation products. Considering also previously published fracture toughness data, this indicates that CuNiBe alloys have irradiated tensile and electrical properties comparable or superior to CuCrZr and oxide dispersion strengthened copper at temperatures <250 C, and may be an attractive

  5. Evaluation of high strength, high conductivity CuNiBe alloys for fusion energy applications

    NASA Astrophysics Data System (ADS)

    Zinkle, S. J.

    2014-06-01

    The unirradiated tensile properties for several different heats and thermomechanical treatment conditions of precipitation strengthened Hycon 3HP™ CuNiBe (Cu-2%Ni-0.35%Be in wt.%) have been measured over the temperature range of 20-500 °C for longitudinal and long transverse orientations. The room temperature electrical conductivity has also been measured for several heats, and the precipitate microstructure was characterized using transmission electron microscopy. The CuNiBe alloys exhibit very good combination of strength and conductivity at room temperature, with yield strengths of 630-725 MPa and electrical conductivities of 65-72% International Annealed Copper Standard (IACS). The strength remained relatively high at all test temperatures, with yield strengths of 420-520 MPa at 500 °C. However, low levels of ductility (<5% uniform elongation) were observed at test temperatures above 200-250 °C, due to flow localization near grain boundaries (exacerbated by having only 10-20 grains across the gage thickness of the miniaturized sheet tensile specimens). Scanning electron microscopy observation of the fracture surfaces found a transition from ductile transgranular to ductile intergranular fracture with increasing test temperature. Fission neutron irradiation to a dose of ∼0.7 displacements per atom (dpa) at temperatures between 100 and 240 °C produced a slight increase in strength and a significant decrease in ductility. The measured tensile elongation after irradiation increased with increasing irradiation temperature, with a uniform elongation of ∼3.3% observed at 240 °C. The electrical conductivity decreased slightly following irradiation, due to the presence of defect clusters and Ni, Zn, Co transmutation products. Considering also previously published fracture toughness data, this indicates that CuNiBe alloys have irradiated tensile and electrical properties comparable or superior to CuCrZr and oxide dispersion strengthened copper at temperatures

  6. Critical cooling rate and thermal stability of Zr--Ti--Cu--Ni--Be alloys

    SciTech Connect

    Waniuk, Theodore A.; Schroers, Jan; Johnson, William L.

    2001-02-26

    The critical cooling rate as well as the thermal stability are measured for a series of alloys in the Zr--Ti--Cu--Ni--Be system. Upon cooling from the molten state with different rates, alloys with compositions ranging along a tie line from (Zr{sub 70}Ti{sub 30}){sub 55}(Ni{sub 39}Cu{sub 61}){sub 25}Be{sub 20} to (Zr{sub 85}Ti{sub 15}){sub 55}(Ni{sub 57}Cu{sub 43}){sub 22.5}Be{sub 27.5} show a continuous increase in the critical cooling rate to suppress crystallization. In contrast, thermal analysis of the same alloys shows that the undercooled liquid region, the temperature difference between the glass transition temperature and the crystallization temperature, is largest for some compositions midway between the two endpoints, revealing that glass forming ability does not correlate with thermal stability. The relationship between the composition-dependent glass forming ability and thermal stability is discussed with reference to a chemical decomposition process.

  7. Industrialization of nanocrystalline Fe-Si-B-P-Cu alloys for high magnetic flux density cores

    NASA Astrophysics Data System (ADS)

    Takenaka, Kana; Setyawan, Albertus D.; Sharma, Parmanand; Nishiyama, Nobuyuki; Makino, Akihiro

    2016-03-01

    Nanocrystalline Fe-Si-B-P-Cu alloys exhibit high saturation magnetic flux density (Bs) and extremely low magnetic core loss (W), simultaneously. Low amorphous-forming ability of these alloys hinders their application potential in power transformers and motors. Here we report a solution to this problem. Minor addition of C is found to be effective in increasing the amorphous-forming ability of Fe-Si-B-P-Cu alloys. It allows fabrication of 120 mm wide ribbons (which was limited to less than 40 mm) without noticeable degradation in magnetic properties. The nanocrystalline (Fe85.7Si0.5B9.5P3.5Cu0.8)99C1 ribbons exhibit low coercivity (Hc)~4.5 A/m, high Bs~1.83 T and low W~0.27 W/kg (@ 1.5 T and 50 Hz). Success in fabrication of long (60-100 m) and wide (~120 mm) ribbons, which are made up of low cost elements is promising for mass production of energy efficient high power transformers and motors

  8. Stress corrosion cracking and hydrogen embrittlement of an Al-Zn-Mg-Cu alloy

    SciTech Connect

    Song, R.G.; Dietzel, W.; Zhang, B.J.; Liu, W.J.; Tseng, M.K.; Atrens, A

    2004-09-20

    The age hardening, stress corrosion cracking (SCC) and hydrogen embrittlement (HE) of an Al-Zn-Mg-Cu 7175 alloy were investigated experimentally. There were two peak-aged states during ageing. For ageing at 413 K, the strength of the second peak-aged state was slightly higher than that of the first one, whereas the SCC susceptibility was lower, indicating that it is possible to heat treat 7175 to high strength and simultaneously to have high SCC resistance. The SCC susceptibility increased with increasing Mg segregation at the grain boundaries. Hydrogen embrittlement (HE) increased with increased hydrogen charging and decreased with increasing ageing time for the same hydrogen charging conditions. Computer simulations were carried out of (a) the Mg grain boundary segregation using the embedded atom method and (b) the effect of Mg and H segregation on the grain boundary strength using a quasi-chemical approach. The simulations showed that (a) Mg grain boundary segregation in Al-Zn-Mg-Cu alloys is spontaneous, (b) Mg segregation decreases the grain boundary strength, and (c) H embrittles the grain boundary more seriously than does Mg. Therefore, the SCC mechanism of Al-Zn-Mg-Cu alloys is attributed to the combination of HE and Mg segregation induced grain boundary embrittlement.

  9. Artificial intelligence applied to atomistic kinetic Monte Carlo simulations in Fe Cu alloys

    NASA Astrophysics Data System (ADS)

    Djurabekova, F. G.; Domingos, R.; Cerchiara, G.; Castin, N.; Vincent, E.; Malerba, L.

    2007-02-01

    Vacancy migration energies as functions of the local atomic configuration (LAC) in Fe-Cu alloys have been systematically tabulated using an appropriate interatomic potential for the alloy of interest. Subsets of these tabulations have been used to train an artificial neural network (ANN) to predict all vacancy migration energies depending on the LAC. The error in the prediction of the ANN has been evaluated by a fuzzy logic system (FLS), allowing a feedback to be introduced for further training, to improve the ANN prediction. This artificial intelligence (AI) system is used to develop a novel approach to atomistic kinetic Monte Carlo (AKMC) simulations, aimed at providing a better description of the kinetic path followed by the system through diffusion of solute atoms in the alloy via vacancy mechanism. Fe-Cu has been chosen because of the importance of Cu precipitation in Fe in connection with the embrittlement of reactor pressure vessels of existing nuclear power plants. In this paper the method is described in some detail and the first results of its application are presented and briefly discussed.

  10. Ductility of a dental Ag-Pd-Cu-Au alloy.

    PubMed

    Syverud, M; Herø, H

    1984-02-01

    A silver-palladium type of dental alloy for fixed restorations has been investigated with regard to the ability of the material to be plastically deformed in uniaxial tensile testing after two different age-hardening treatments. A certain degree of ductility is required for the burnishing of the margins. Aged to peak hardness at 350 degrees C after solid-solution annealing at 900 degrees C, the material was found to be brittle owing to a reaction zone along the grain boundaries, promoting an intergranular fracture. When the age-hardening temperature was lowered to 275 degrees C, a less pronounced reaction zone along the grain boundaries could be observed. The accompanying mechanical properties after precipitation hardening at 275 degrees C are probably an acceptable compromise between mechanical strength and ductility. Small particles along grain boundaries and brittleness were also found after solid-solution annealing at 900 degrees C and quenching. It is suggested that the improved ductility after subsequent aging at 275 degrees C is due to a coarsening of these small particles. In the as-cast condition the alloy was softer and more ductile than in the age-hardened state. PMID:6585123

  11. Time Temperature-Precipitation Behavior in An Al-Cu-Li Alloy 2195

    NASA Technical Reports Server (NTRS)

    Chen, P. S.; Bhat, B. N.

    1999-01-01

    Al-Cu-Li alloy 2195, with its combination of good cryogenic properties, low density, and high modulus, has been selected by NASA to be the main structural alloy of the Super Light Weight Tank (SLWT) for the Space Shuttle. Alloy 2195 is strengthened by an aging treatment that precipitates a particular precipitate, labeled as T1(Al2CuLi). Other phases, such as GP zone, (theta)', (theta)", theta, (delta)', S' are also present in this alloy when artificially aged. Cryogenic strength and fracture toughness are critical to the -SLWT application, since the SLWT will house liquid oxygen and hydrogen. Motivation for the Time-Temperature-Precipitation (TTP) study at lower temperature (lower than 350 F) comes in part from a recent study by Chen, The study found that the cryogenic fracture toughness of alloy 2195 is greatly influenced by the phases present in the matrix and subgrain boundaries. Therefore, the understanding of TTP behavior can help develop a guideline to select appropriate heat treatment conditions for the desirable applications. The study of TTP behavior at higher temperature (400 to 1000 F) was prompted by the fact that the SLWT requires a welded construction. Heat conduction from the weld pool affects the microstructure in the heat-affected zone (HAZ), which leads to changes in the mechanical properties. Furthermore, the SLWT may need repair welding for more than one time and any additional thermal cycles will increase precipitate instability and promote phase transformation. As a result considerable changes in HAZ microstructure and mechanical properties are expected during the construction of the SLWT. Therefore, the TTP diagrams can serve to understand the thermal history of the alloy by analyzing the welded microstructure. In the case welding, the effects of thermal cycles on the microstructure and mechanical properties can be predicted with the aid of the TTP diagrams. The 2195 alloy (nominally Al + 4 pct Cu + 1 pct Li + 0.3 pct Ag + 0.3 pct Mg + 0

  12. Barrier anodic coatings formed on 6061-T6 aluminum alloy in electrolytes containing different ethanol to water ratios

    SciTech Connect

    Panitz, J.K.G.; Sharp, D.J.; Martinez, F.E.; Merrill, R.M.; Ward, K.J.

    1988-12-01

    We have studied barrier anodic film formation on 6061-T6 aluminum alloy substrates as a function of electrolyte composition for five mixtures of ammonium tartrate dissolved in water and diluted with different amounts of ethanol. The effects of electrolyte temperatures within the range of 18/degree/C to 38/degree/C were explored. The results of this study indicate that the best dielectric coatings and the shortest processing times occur for the 100% water-ammonium tartrate electrolyte. The second best coatings and processing times occur in conjunction with the use of 98% ethanol, 2% water plus ammonium tartrate electrolyte. In general, visibly flawed coatings, scintillation events at cell voltages in excess of approximately 750-800 volts and/or abnormally long processing times occur in conjunction with the use of electrolyte mixtures containing 20%, 60%, and 90% water. We analysed samples of electrolyte as a function of usage, and evaluated the composition of the coatings using Fourier Transform Infrared Analysis to better understand the mechanisms which contribute to anodic coating growth that result in the observed variations in the dielectric properties. All of the coatings exhibited similar compositions except with regard to the amount of CO2 that was physisorbed in the coatings. The dielectrically inferior coatings that were typically produced by the electrolytes containing ethanol contain substantially more CO2 than the coatings grown in the 100% water-based electrolyte. These results strongly suggest that the ethanol in the electrolyte oxidizes and forms CO2 which is incorporated in the coatings and results in inferior dielectric properties. 8 refs., 7 figs.

  13. Experimental examination of strain field within GP zone in an Al-Zn-Mg-Cu alloy

    NASA Astrophysics Data System (ADS)

    Bai, P. C.; Liu, F.; Hou, X. H.; Zhao, C. W.; Xing, Y. M.

    2012-11-01

    The strain field of GP zone plays a very important role in strengthening of the precipitation-hardened aluminum alloys by prohibiting movement of dislocations; however, quantitative analysis about the strain field of the GP zone in the aluminum alloys has been seldom reported elsewhere. In this paper, the microstructure of GP zone in an Al-Zn-Mg-Cu alloy was explored by using high-resolution transmission electron microscopy (HRTEM), and the displacement field of lattice planes within the GP zone was experimentally measured by geometric phase analysis (GPA) technique; then, the quantitative results about strains of the distorted lattice planes within the GP zone were also obtained. It is found that the GP zone core is convergence region of the strains, and the maximum value of the compressive strains within the GP zone is about 7.6%.

  14. CuZrAl amorphous alloys prepared by casting and milling

    NASA Astrophysics Data System (ADS)

    Tomolya, K.; Janovszky, D.; Sveda, M.; Hegman, N.; Solyom, J.; Roosz, A.

    2009-01-01

    Several preparation methods are available for the production of amorphous alloys. During the experiment described in this paper (Cu58Zr42)100-xAlx (x = 0-14,8; in at%) amorphous alloys were prepared by casting and ball-milling. The ingots were produced by arc melting. Wedge-shaped samples were prepared from the ingots by centrifugal casting into copper mould. The microstructures of these samples were defined by SEM. The amorphous samples were analysed by DSC and the activation energy of the crystallization processes was calculated from the measured temperatures. The master alloys of identical composition were milled by ball-mill for different periods of time. The powders were analysed by XRD in order to define the amorphous fractions.

  15. Fracture resistance and fatigue crack growth characteristics of two Al-Cu-Mg-Zr alloys

    NASA Technical Reports Server (NTRS)

    Sarkar, Bhaskar; Lisagor, W. B.

    1992-01-01

    The dependence of strength, fracture resistance, and fatigue crack growth rate on the aging conditions of two alloy compositions based on Al-3.7Cu-1.85Mg-0.2Mn is investigated. Mechanical properties were evaluated in two heat treatment conditions and in two orientations (longitudinal and transverse). Compact tension specimens were used to determine fatigue crack growth characteristics and fracture resistance. The aging response was monitored on coupons using hardness measurements determined with a standard Rockwell hardness tester. Fracture resistance is found to increase with increasing yield strength during artificial aging of age-hardenable 2124-Zr alloys processed by powder metallurgy techniques. Fatigue crack growth rate increases with increasing strength. It is argued that these changes are related to deformation modes of the alloys; a homogeneous deformation mode tends to increase fracture resistance and to decrease the resistance to the fatigue crack propagation rate.

  16. Surface Segregation in a PdCu Alloy Hydrogen Separation Membrane

    SciTech Connect

    Miller, J.B.; Matranga, C.S.; Gellman, A.J.

    2007-06-01

    Separation of hydrogen from mixed gas streams is an important step for hydrogen generation technologies, including hydrocarbon reforming and coal/biomass gasification. Dense palladium-based membranes have received significant attention for this application because of palladium’s ability to dissociatively adsorb molecular hydrogen at its surface for subsequent transport of hydrogen atoms through its bulk. Alloying palladium with minor components, like copper, has been shown to improve both the membrane’s structural characteristics and resistance to poisoning of its catalytic surface [1]. Surface segregation—a composition difference between the bulk material and its surface—is common in alloys and can affect important surface processes. Rational design of alloy membranes requires that surface segregation be understood, and possibly controlled. In this work, we examine surface segregation in a polycrystalline Pd70Cu30 hydrogen separation membrane as a function of thermal treatment and adsorption of hydrogen sulfide.

  17. Oxidation of CuSn alloy nanotree and application for gas sensors

    NASA Astrophysics Data System (ADS)

    Kaneko, Naoto; Shimizu, Tomohiro; Tada, Yoshihiro; Shingubara, Shoso

    2016-06-01

    The CuSn alloy nanotree formed by DC electroplating is a true three-dimensional (3D) structure with many branches that separate the trunk perpendicularly. We carried out the oxidation of CuSn nanotrees in atmosphere in order to study the possibility of such nanotrees for application to sensors. It was confirmed that the oxygen concentration in the CuSn nanotree oxide increased with temperature and reached 40 at. % at 350 °C. The optical reflectance spectra of the CuSn nanotree oxide formed at 250 °C showed a 3–4% reflectance in the wavelength range between 400 and 900 nm, and its behavior differed from those of Cu and Sn oxides formed at 250 °C. The temperature dependence of electrical resistivity for the CuSn nanotree oxide showed a typical semiconductor behavior. By the introduction of H2, O2, N2, and CO gases into the chamber, the resistance of the CuSn nanotree oxide responded against H2 most sensitively, as well as against O2 and CO gases. From the resistance change tendency, it is strongly suggested that the CuSn nanotree oxide is a p-type semiconductor, because it shows an increase in conductivity caused by the adsorption of a negative charge such as O‑. However, the conductivity decreases with the adsorption of a positive charge such as H+. The present study suggests the high potential of the CuSn nanotree oxide as a gas sensor, since it has a very high surface-to-volume ratio.

  18. Microstructural characterization and mechanical property of active soldering anodized 6061 Al alloy using Sn-3.5Ag-xTi active solders

    SciTech Connect

    Wang, Wei-Lin Tsai, Yi-Chia

    2012-06-15

    Active solders Sn-3.5Ag-xTi varied from x = 0 to 6 wt.% Ti addition were prepared by vacuum arc re-melting and the resultant phase formation and variation of microstructure with titanium concentration were analyzed using X-ray diffraction, optical microscopy and scanning electron microscopy. The Sn-3.5Ag-xTi active solders are used as metallic filler to join with anodized 6061 Al alloy for potential applications of providing a higher heat conduction path. Their joints and mechanical properties were characterized and evaluated in terms of titanium content. The mechanical property of joints was measured by shear testing. The joint strength was very dependent on the titanium content. Solder with a 0.5 wt.% Ti addition can successfully wet and bond to the anodized aluminum oxide layers of Al alloy and posses a shear strength of 16.28 {+-} 0.64 MPa. The maximum bonding strength reached 22.24 {+-} 0.70 MPa at a 3 wt.% Ti addition. Interfacial reaction phase and chemical composition were identified by a transmission electron microscope with energy dispersive spectrometer. Results showed that the Ti element reacts with anodized aluminum oxide to form Al{sub 3}Ti-rich and Al{sub 3}Ti phases at the joint interfaces. - Highlights: Black-Right-Pointing-Pointer Active solder joining of anodized Al alloy needs 0.5 wt.% Ti addition for Sn-3.5Ag. Black-Right-Pointing-Pointer The maximum bonding strength occurs at 3 wt.% Ti addition. Black-Right-Pointing-Pointer The Ti reacts with anodized Al oxide to form Al{sub 3}Ti-rich and Al{sub 3}Ti at joint interface.

  19. The stress-corrosion behavior of Al-Li-Cu alloys: A comparison of test methods

    NASA Technical Reports Server (NTRS)

    Rizzo, P. P.; Galvin, R. P.; Nelson, H. G.

    1982-01-01

    Two powder metallurgy processed (Al-Li-Cu) alloys with and without Mg addition were studied in aqueous 3.5% NaCl solution during the alternate immersion testing of tuning fork specimens, slow crack growth tests using fracture mechanics specimens, and the slow strain rate testing of straining electrode specimens. Scanning electron microscopy and optical metallography were used to demonstrate the character of the interaction between the Al-Li-Cu alloys and the selected environment. Both alloys are susceptible to SC in an aqueous 3.5% NaCl solution under the right electrochemical and microstructural conditions. Each test method yields important information on the character of the SC behavior. Under all conditions investigated, second phase particles strung out in rows along the extrusion direction in the alloys were rapidly attacked, and played principal role in the SC process. With time, larger pits developed from these rows of smaller pits and under certain electrochemical conditions surface cracks initiated from the larger pits and contributed directly to the fracture process. Evidence to support slow crack growth was observed in both the slow strain rate tests and the sustained immersion tests of precracked fracture mechanics specimens. The possible role of H2 in the stress corrosion cracking process is suggested.

  20. Structural and magnetic properties CuAl1-xCrxS2 alloys

    NASA Astrophysics Data System (ADS)

    Ortega López, C.; Casiano Jiménez, G.; Espitia, M. J.

    2016-02-01

    In this paper computational calculations were performed based on the density functional theory DFT, to investigate the structural, electronic and magnetic properties of CuAl1-xCrxS2 (x=0.0, 0.50 and 1.00) alloys. Pseudopotential method was used, as is implemented in the Quantum-Espresso code. We found that the alloys crystallize in a tetragonal structure belonging to space group 122 (I-42d) with lattice constants a=5.290Å, c=10.378Å for x=0.5 and a=5.283Å, c=10.366Å for x=1.00. These values are in good agreement with experimental results. Additionally, we found that the alloys possess an antiferromagnetic behaviour with magnetic moments 4,20μβ/cell and 4,05μβ/cell, respectively. From the analysis of the density of states, it is clear that the alloys have a half-metallic behaviour due to the Cr-d and Cu-d states crossing the Fermi level. This compounds can be used in spintronic.

  1. Microstructure analysis of Al-Si-Cu alloys prepared by gradient solidification technique

    NASA Astrophysics Data System (ADS)

    Borkar, Hemant; Seifeddine, Salem; Jarfors, Anders E. W.

    2015-03-01

    Al-Si-Cu alloys were cast with the unique gradient solidification technique to produce alloys with two cooling rates corresponding to secondary dendrite arm spacing (SDAS) of 9 and 27 μm covering the microstructural fineness of common die cast components. The microstructure was studied with optical microscopy and scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS) and electron backscattered diffraction (EBSD). The alloy with higher cooling rate, lower SDAS, has a more homogeneous microstructure with well distributed network of eutectic and intermetallic phases. The results indicate the presence of Al-Fe-Si phases, Al-Cu phases and eutectic Si particles but their type, distribution and amount varies in the two alloys with different SDAS. EBSD analysis was also performed to study the crystallographic orientation relationships in the microstructure. One of the major highlights of this study is the understanding of the eutectic formation mechanism achieved by studying the orientation relationships of the aluminum in the eutectic to the surrounding primary aluminum dendrites.

  2. Effect of hydrogen exposure on a Cu-8 Cr-4 Nb alloy

    NASA Technical Reports Server (NTRS)

    Ellis, David L.; Misra, Ajay K.; Dreshfield, Robert L.

    1993-01-01

    The advanced regeneratively cooled rocket thrust chamber may require new materials to achieve long life and improved performance. Current materials such as NARloy-Z (Cu-3 wt. percent Ag-0.5 wt. percent Zr), while highly conductive, do not have sufficient high temperature strength and creep resistance to meet the projected needs of advanced rocket motors. A Cu-8 at. percent Cr-4 at. percent Nb (Cu-8 Cr-4 Nb) alloy has been identified as a promising material for this application. However, hydrogen embrittlement is a concern given the presence of high pressure, high temperature hydrogen in regeneratively cooled rocket motors. Thermodynamic analysis of the reaction between Cr-rich Cr2Nb and H2 showed that there is a possibility of reaction at temperatures up to 323 K in a 35 MPa H2 environment. Above 323 K the pressure necessary to achieve reaction rapidly increased beyond the range experienced in rocket motors. Tensile specimens exposed in 34.5 MPa H2 at room temperatures and during cycling to 705 C did not show any degradation of properties. No evidence of reaction was observed for Cr2Nb precipitate observed on the fracture surfaces. Based on these results the Cu-8 Cr-4 Nb alloy was judged to be sufficiently stable for use in rocket motors.

  3. Determination of the location of hydrogen in the CuTi amorphous alloys by neutron diffraction

    NASA Astrophysics Data System (ADS)

    Rodmacq, B.; Billard, L.; Chamberod, A.; Mangin, Ph.

    1986-02-01

    Neutron diffraction experiments have been performed on hydrogenated and deuterated Cu xTi 1- x amorphous alloys ( x = 0.67, 0.50, 0.35). The evolution of the interference functions as a function of hydrogen and deuterium concentration has shown that the hydrogen atoms have no copper atoms as first neighbours but are surrounded only by titanium atoms. The metal-hydrogen first distances compare well to those found in the corresponding crystalline hydrides. A model for the Cu 50Ti 50 amorphous alloy has been built up. The introduction of hydrogen or deuterium atoms in Ti 4 tetrahedra leads to calculated pair correlation functions very close to the experimental ones. Finally, the thermal evolution of CuTiH and CuTiD samples as been studied. Increasing the temperature leads to the precipitation of TiH 2 particles in the amorphous matrix. This is followed by the crystallization of the matrix and by the desorption of hydrogen at still higher temperature.

  4. Development of Cu-Nb alloy microcomposite conductors for high field pulsed magnets. Final report

    SciTech Connect

    Pantsyrnyi, V.I.; Shikov, A.K.; Nikulin, A.D.; Belyiakov, N.M.; Potapenko, I.I.; Vorob`ova, A.E.; Silaev, A.G.; Kozlenkova, N.I.; Zinov`ev, V.G.; Drobyshev, V.A.

    1995-12-31

    Primary goal is to develop high strength-high conductivity composite wires with enhanced cross section. The following research areas were started: melting, deformation, TEM, SEM, and mechanical/electrical characterization of in-situ Cu-Nb microcomposites. Consumable arc melting using initial composite electrodes produced by cold deformation was chosen for preparing initial ingots of Cu-(16- 18)wt%Nb alloy. The deformation process including extrusion, drawing with intermediate heat treatments, and rolling was analyzed. Structure of Cu-Nb composite was investigated at all stages of its fabrication. Rebundling was successfully used to manufacture conductors with enhanced cross sections. Wire with 3x7mm{sup 2} cross section and 50m length was produced with UTS (20 C) = 1000 MPa and electroconductivity 70% IACS.

  5. Explosive bonding of 316L to C18150 CuCrZr alloy for ITER applications.

    SciTech Connect

    Puskar, Joseph David; Butler, Don J.; Goods, Steven Howard; Brasher, Dave G.

    2010-10-01

    Recent developments in the ITER experimental fusion reactor require that a 316L stainless steel substructure be bonded to a precipitation strengthened CuCrZr heat sink alloy, C18150. This bond defines the cooling water pressure boundary. Given the importance of this interface, a variety of experiments with fusion welding and solid-state joining techniques have been performed. Analysis of the joints includes mechanical measurements of bond strength and microstructural analysis using optical and electron microscopy techniques. A particular emphasis was placed on the mechanical properties of the CuCrZr, since it undergoes additional thermal processing and cannot be solutionized and aged hardened per standard heat treatments. It was determined that the explosion bonding, of all the techniques examined, maximized the residual mechanical strength of the CuCrZr. The bonding parameters were optimized to minimize the amount of mixing and porosity at the interface. The details of these results and the optimization will be discussed.

  6. The effects of thermal procedure on transformation temperature, crystal structure and microstructure of Cu-Al-Co shape memory alloy

    NASA Astrophysics Data System (ADS)

    Aydoğdu, Y.; Kök, M.; Dağdelen, F.; Aydoğdu, A.; Turabi, A. S.; Karaca, H. E.

    2016-01-01

    The purpose of this study is to investigate the effects of different thermal procedures of the Cu-Al-Co shape memory alloy on its crystal structure, transformation temperature and microstructure. The alloys were subjected to a heat treatment and then cooling was applied at four different conditions. After the thermal process, XRD, DSC, optical microscopy and micro-hardness measurements were carried out. The experimental studies showed that crystal structure, microstructure and transformation temperature of Cu-Al-Co alloy were changed from the cooling conditions.

  7. Understanding the Cu-Zn brass alloys using a short-range-order cluster model: Significance of specific compositions of industrial alloys

    DOE PAGESBeta

    Hong, H. L.; Wang, Q.; Dong, C.; Liaw, Peter K.

    2014-11-17

    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 a-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 a-brasses listed in the American Society for Testing and Materials (ASTM) specifications. In these formulas, the bracketed parts represent the 1st-neighbor cluster, and eachmore » 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, therefore offering a fundamental and practical method towards composition interpretations of all kinds of alloys.« less

  8. Understanding the Cu-Zn brass alloys using a short-range-order cluster model: Significance of specific compositions of industrial alloys

    SciTech Connect

    Hong, H. L.; Wang, Q.; Dong, C.; Liaw, Peter K.

    2014-11-17

    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 a-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 a-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, therefore offering a fundamental and practical method towards composition interpretations of all kinds of alloys.

  9. Effect of Test Parameters on the Friction Behaviour of Anodized Aluminium Alloy

    PubMed Central

    Khalladi, A.; Elleuch, K.; De-Petris Wery, M.; Ayedi, H. F.

    2014-01-01

    The tribological behaviour of anodic oxide layer formed on Al5754, used in automotive applications, was investigated against test parameters. The friction coefficient under different normal loads, sliding speeds, and oxide thicknesses was studied using a pin on disc tribometer. Results show that the increase of load and sliding speed increase the friction coefficient. The rise of contact pressure and temperature seems to cause changes in wear mechanism. Glow-discharge optical emission spectroscopy (GDOES) was used to investigate the chemical composition of the oxide layer. Morphology and composition of the wear tracks were analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). On the basis of these characterization techniques, a wear mechanism was proposed. The observed mechanical properties can be related to the morphology and the chemical composition of the layer. PMID:27437452

  10. Highly branched PtCu bimetallic alloy nanodendrites with superior electrocatalytic activities for oxygen reduction reactions

    NASA Astrophysics Data System (ADS)

    Fu, Shaofang; Zhu, Chengzhou; Shi, Qiurong; Xia, Haibing; Du, Dan; Lin, Yuehe

    2016-02-01

    Morphology control is a promising strategy to improve the catalytic performance of Pt-based catalysts. In this work, we reported a facile synthesis of PtCu bimetallic alloy nanodendrites using Brij 58 as a template. The highly branched structures and porous features offer relatively large surface areas, which is beneficial to the enhancement of the catalytic activity for oxygen reduction reactions in fuel cells. In addition, the elimination of carbon supports showed an important effect on the stability of the catalysts. By tuning the ratio of Pt and Cu precursors, PtCu nanodendrites were almost four times more active on the basis of an equivalent Pt mass for oxygen reduction reactions than the commercial Pt/C catalyst.Morphology control is a promising strategy to improve the catalytic performance of Pt-based catalysts. In this work, we reported a facile synthesis of PtCu bimetallic alloy nanodendrites using Brij 58 as a template. The highly branched structures and porous features offer relatively large surface areas, which is beneficial to the enhancement of the catalytic activity for oxygen reduction reactions in fuel cells. In addition, the elimination of carbon supports showed an important effect on the stability of the catalysts. By tuning the ratio of Pt and Cu precursors, PtCu nanodendrites were almost four times more active on the basis of an equivalent Pt mass for oxygen reduction reactions than the commercial Pt/C catalyst. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07682j

  11. Microstructure and microhardness evolution of melt-spun Al-Si-Cu alloy

    NASA Astrophysics Data System (ADS)

    Ahmed, Emad M.; Ebrahim, M. R.

    2014-04-01

    Al-11 wt.% Si-11 wt.% Cu (11.29 at.% Si-5.1 at.% Cu) melt was rapidly solidified into ribbons and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and microhardness technique. The Rietveld X-ray diffraction analysis was applied successfully to analyze the microstructure and phase precipitations. The high cooling rate obtained in rapid solidification has a significant influence on the microstructure and microhardness of this alloy. On the basis of the Al peaks shift measured in the XRD scans, a solid solubility extension value of 3.95 at.% Si and 3.54 at.% Cu in α-Al were determined. No XRD peaks of the Si phase have been detected. XRD peaks of the intermetallic Al2Cu phase have been observed clearly with estimated content of 12.6 wt.%. During prolonged annealing process at 350°C/25 h, XRD peaks of the Si phase clearly appeared with estimated content of 8.6 wt.% and, moreover, the Al2Cu phase content increased to 16 wt.%. The estimated crystallite size and micro-strain % of α-Al are 30 nm and 0.056, respectively. The melt-spun wheel side ribbon represents ultra-fine microstructure with particles size less than 1μm and exhibits enhancement of hardness to 241 HV. Hardness has further increased to 291 HV during heat treatment (150°C/12 h). Rapid solidification exhibited a great influence on microstructure and microhardness of the Al-Si-Cu alloy.

  12. Effect of Cu addition on the martensitic transformation of powder metallurgy processed Ti–Ni alloys

    SciTech Connect

    Kim, Yeon-wook; Choi, Eunsoo

    2014-10-15

    Highlights: • M{sub s} of Ti{sub 50}Ni{sub 50} powders is 22 °C, while M{sub s} of SPS-sintered porous bulk increases up to 50 °C. • M{sub s} of Ti{sub 50}Ni{sub 40}Cu{sub 20} porous bulk is only 2 °C higher than that of the powders. • Recovered stain of porous TiNi and TiNiCu alloy is more than 1.5%. - Abstract: Ti{sub 50}Ni{sub 50} and Ti{sub 50}Ni{sub 30}Cu{sub 20} powders were prepared by gas atomization and their transformation behaviors were examined by means of differential scanning calorimetry and X-ray diffraction. One-step B2–B19’ transformation occurred in Ti{sub 50}Ni{sub 50} powders, while Ti{sub 50}Ni{sub 30}Cu{sub 20} powders showed B2–B19 transformation behavior. Porous bulks with 24% porosity were fabricated by spark plasma sintering. The martensitic transformation start temperature (50 °C) of Ti{sub 50}Ni{sub 50} porous bulk is much higher than that (22 °C) of the as-solidified powders. However, the martensitic transformation start temperature (35 °C) of Ti{sub 50}Ni{sub 30}Cu{sub 20} porous bulk is almost the same as that (33 °C) of the powders. When the specimens were compressed to the strain of 8% and then unloaded, the residual strains of Ti{sub 50}Ni{sub 50} and Ti{sub 50}Ni{sub 30}Cu{sub 20} alloy bulks were 3.95 and 3.7%, respectively. However, these residual strains were recovered up to 1.7% after heating by the shape memory phenomenon.

  13. Microstructure and Shape Memory Characteristics of Powder-Metallurgical-Processed Ti-Ni-Cu Alloys

    NASA Astrophysics Data System (ADS)

    Kim, Yeon-Wook; Chung, Young-Soo; Choi, Eunsoo; Nam, Tae-Hyun

    2012-08-01

    Even though Ti-Ni-Cu alloys have attracted a lot of attention because of their high performance in shape memory effect and decrease in thermal and stress hysteresis compared with Ti-Ni binary alloys, their poor workability restrains the practical applications of Ti-Ni-Cu shape memory alloys. Consolidation of Ti-Ni-Cu alloy powders is useful for the fabrication of bulk near-net-shape shape memory alloy. Ti50Ni30Cu20 shape memory alloy powders were prepared by gas atomization, and the sieved powders with the specific size range of 25 to 150 μm were chosen for this study. The evaluation of powder microstructures was based on a scanning electron microscope (SEM) examination of the surface and the polished and etched powder cross sections. The typical images showed cellular/dendrite morphology and high population of small shrinkage cavities at intercellular regions. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis showed that a B2-B19 one-step martensitic transformation occurred in the as-atomized powders. The martensitic transformation start temperature (Ms) of powders ranging between 25 and 50 μm was 304.5 K (31.5 °C). The Ms increased with increasing powder size. However, the difference of Ms in the as-atomized powders ranging between 25 and 150 μm was only 274 K (1 °C). A dense cylindrical specimen of 10 mm diameter and 15 mm length were fabricated by spark plasma sintering (SPS) at 1073 K (800 °C) and 10 MPa for 20 minutes. Then, this bulk specimen was heat treated for 60 minutes at 1123 K (850 °C) and quenched in ice water. The Ms of the SPS specimen was 310.5 K (37.5 °C) whereas the Ms of conventionally cast ingot is found to be as high as 352.7 K (79.7 °C). It is considered that the depression of the Ms in rapidly solidified powders is ascribed to the density of dislocations and the stored energy produced by rapid solidification.

  14. A branching NiCuPt alloy counter electrode for high-efficiency dye-sensitized solar cell

    NASA Astrophysics Data System (ADS)

    Yang, Peizhi; Tang, Qunwei

    2016-01-01

    A rising objective for high-efficiency dye-sensitized solar cells (DSSCs) is to create extraordinary and cost-effective counter electrode (CE) electrocatalysts. We present here a branching NiCuPt alloy CE synthesized by electrodepositing Ni on ZnO microrod templates and subsequently growing branched Cu as well as suffering from a galvanic displacement for Pt uptake. The resultant NiCuPt alloy CE displays a promising electrocatalytic activity toward redox electrolyte having I-/I3- couples. An impressive power conversion efficiency of 9.66% is yielded for the liquid-junction DSSC platform.

  15. Rapid solidification and dendrite growth of ternary Fe-Sn-Ge and Cu-Pb-Ge monotectic alloys

    NASA Astrophysics Data System (ADS)

    Zhang, Xuehua; Ruan, Ying; Wang, Weili; Wei, Bingbo

    2007-08-01

    The phase separation and dendrite growth characteristics of ternary Fe-43.9%Sn-10%Ge and Cu-35.5%Pb-5%Ge monotectic alloys were studied systematically by the glass fluxing method under substantial undercooling conditions. The maximum undercoolings obtained in this work are 245 and 257 K, respectively, for these two alloys. All of the solidified samples exhibit serious macrosegregation, indicating that the homogenous alloy melt is separated into two liquid phases prior to rapid solidification. The solidification structures consist of four phases including α-Fe, (Sn), FeSn and FeSn2 in Fe-43.9%Sn-10%Ge ternary alloy, whereas only (Cu) and (Pb) solid solution phases in Cu-35.5%Pb-5%Ge alloy under different undercoolings. In the process of rapid monotectic solidification, α-Fe and (Cu) phases grow in a dendritic mode, and the transition “dendrite→monotectic cell” happens when alloy undercoolings become sufficiently large. The dendrite growth velocities of α-Fe and (Cu) phases are found to increase with undercooling according to an exponential relation.

  16. Correlation between S' precipitation and the PortevinLe Chatelier effect in an Al-Li-Cu-Mg-Zr alloy

    SciTech Connect

    Wert, J.A.; Wycliffe, P.A.

    1985-04-01

    Serrated yielding, also known as the Portevin-le Chatelier effect, occurs in a variety of aluminum alloys when solutes such as Mg or Cu are present in solid solution. Despite frequent observations of serrated yielding in Al-Li alloys, the phenomenon has not been extensively investigated in these alloys. Tamura, Mori and Nakamura reported finding serrated yielding in Al-3 wt.% Li single crystals deformed at room temperature at a strain rate near 10/sup -3/ 5/sup -1/. However, similar polycrystalline samples did not exhibit serrated yielding, a observation which Tamura et al ascribed to interference of the primary slip system by grain boundaries or by operation of multiple slip systems. Although the cause of serrated yielding in Al-Li single crystals was not discussed, an interaction between dislocations and Li atoms in solid solution is consistent with results reported by Tamura et al. The goal of the present investigation was to show that occurrence of serrated yielding of an Al-Li-Cu-Mg-Zr alloy coincides with absence of S' precipitates (precursor to Al/sub 2/CuMg) in the microstructure. Evidence is presented to show that when Cu and Mg remain in solid solution (S' absent), serrated yielding is observed. However, aging treatments that lead to copious precipitation of S' inhibit serrated yielding in this alloy. Thus, links are established between aging treatment, microstructure and the Portevin-le Chatelier effect in an Al-Li-Cu-Mg-Zr alloy.

  17. Electrodeposition mechanism and characterization of Ni-Cu alloy coatings from a eutectic-based ionic liquid

    NASA Astrophysics Data System (ADS)

    Wang, Shaohua; Guo, Xingwu; Yang, Haiyan; Dai, JiChun; Zhu, Rongyu; Gong, Jia; Peng, Liming; Ding, Wenjiang

    2014-01-01

    The electrodeposition mechanism, microstructures and corrosion resistances of Ni-Cu alloy coatings on Cu substrate were investigated in a choline chloride-urea (1:2 molar ratio) eutectic-based ionic liquid (1:2 ChCl-urea IL) containing nickel and copper chlorides. Cyclic voltammetry showed that the onset reduction potentials for Cu (˜-0.32 V) and for Ni (˜-0.47 V) were close to each other, indicating that Ni-Cu co-deposition could be easily achieved in the absence of complexing agent which was indispensable in aqueous plating electrolyte. Chronoamperometric investigations revealed that Ni-Cu deposits followed the three-dimensional instantaneous nucleation/growth mechanism, thus producing a solid solution. The compositions, microstructures and corrosion resistances of Ni-Cu alloy coatings were significantly dependent on the deposition current densities. Ni-Cu alloy coatings were α-Ni(Cu) solid solutions, and the coating containing ˜17.6 at.% Cu exhibited the best corrosion resistance because of its dense and crack-free structure.

  18. The effect of quaternary element on the thermodynamic parameters and structure of CuAlMn shape memory alloys

    NASA Astrophysics Data System (ADS)

    Aksu Canbay, C.; Karagoz, Z.

    2013-10-01

    In this study, the Cu-based shape memory alloys were produced by arc melting. We have investigated the effects of the alloying elements on the characteristic transformation temperatures, enthalpy, entropy values, and the structure of Cu-Al-Mn ternary system. The evolution of the transformation temperatures was studied by the differential scanning calorimetry. The characteristic transformation temperatures can be controlled by the variations in the aluminum and manganese content. Additionally, the effect of magnesium and iron on the transformation temperatures and thermodynamic parameters was investigated in the Cu-Al-Mn ternary system. The addition of the magnesium decreases the characteristic transformation temperatures of the Cu-Al-Mn system, but that of the iron increases. The structural changes of the samples were studied by X-ray diffraction measurements and optical microscope observations. Due to the low solubility of the magnesium, the magnesium addition into the Cu-Al-Mn system forms precipitates in the matrix. It is evaluated that the transformation parameters of the CuAlMn shape memory alloys can be controlled by the change of the alloying elements and the weight percentages of alloying elements.

  19. Mechanical properties of Cu sbnd Cr sbnd Zr alloy and SS316 joints fabricated by friction welding method

    NASA Astrophysics Data System (ADS)

    Tsuchiya, Kunihiko; Kawamura, Hiroshi

    1996-10-01

    Copper alloys with high-strength and high-conductivity are being considered for several magnetic fusion energy applications such as the first wall in high power-density devices, resistive magnetic coils, and high-heat flux components. For example, the stainless steel is a structural material while Cu-alloy acts as a heat sink material for the surface heat flux in the first wall. Therefore, development of reliable joints between Cu-alloys and stainless steel (SS316) is required. In the present work, joining tests on Cu—1%Cr—1%Zr/SS316 by friction welding were performed, and optimum fabricating conditions of the Cu-alloy/SS316 joint were determined. Additionally, the characteristics of tensile strength, hardness, metallographical observation and SEM/EPMA analyses on Cu—1%Cr—1%Zr/SS316 fabricated by friction welding were evaluated.

  20. Effect of a prior stretch on the aging response 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

    Recently, a family of Al-Cu-Li alloys containing minor amounts of Ag, Mg, and Zr and having desirable combinations of strength and toughness were developed. The Weldalite (trademark) alloys exhibit a unique characteristic in that with or without a prior stretch, they obtain significant strength-ductility combinations upon natural and artificial aging. The ultra-high strength (approximately 690 MPa yield strength) in the peak-aged tempers (T6 and T8) were primarily attributed to the extremely fine T(sub 1) (Al2CuLi) or T(sub 1)-type precipitates that occur in these alloys during artificial aging, whereas the significant natural aging response observed is attributed to strengthening from delta prime (Al3Li) and GP zones. In recent work, the aging behavior of an Al-Cu-Li-Ag-Mg alloy without a prior stretch was followed microstructurally from the T4 to the T6 condition. Commercial extrusions, rolled plates, and sheets of Al-Cu-Li alloys are typically subjected to a stretching operation before artificial aging to straighten the extrusions and, more importantly, introduce dislocations to simulate precipitation of strengthening phases such as T(sub 1) by providing relatively low-energy nucleation sites. The goals of this study are to examine the microstructure that evolves during aging of an alloy that was stretch after solution treatment and to compare the observations with those for the unstretched alloy.

  1. Spark plasma sintering of a nanocrystalline Al-Cu-Mg-Fe-Ni-Sc alloy

    NASA Astrophysics Data System (ADS)

    Zúñiga, Alejandro; Ajdelsztajn, Leonardo; Lavernia, Enrique J.

    2006-04-01

    The microstructure and aging behavior of a nanocrystalline Al-Cu-Mg-Fe-Ni-Sc alloy was studied. The nanocrystalline powders were produced by milling at liquid nitrogen temperature and then consolidated using spark plasma sintering (SPS). The microstructure after SPS consisted of a bimodal aluminum grain structure (coarse-grained and fine-grained regions), along with Al9FeNi and Al2CuMg particles dispersed throughout. The microstructure observed in the as-consolidated sample is rationalized on the basis of high current densities that are generated during sintering. Solution treatment and aging of the SPS Al-Cu-Mg-Fe-Ni-Sc sample resulted in softening instead of hardening. This observation can be explained by the reduced amount of Cu, Mg, and Si in solid solution available to form S' Al2CuMg due to the precipitation of Al7FeCu2 and Si-rich particles, and by the fact that rodlike S' Al2CuMg particles could only precipitate out in the coarse-grained regions, greatly decreasing their influence on the hardness. This lack of precipitation in the fine-grained region is argued to represent a new physical observation and is rationalized on the basis of physical and thermodynamic effects. The nanocrystalline SPS Al-Cu-Mg-Fe-Ni-Sc sample was also extremely thermally stable, retaining a fine-grained structure even after solution treatment at 530°C for 5 h. The observed thermal stability is rationalized on the basis of solute drag and Zener pinning caused by the impurities introduced during the cryomilling process.

  2. Construction of modified embedded atom method potentials for Cu, Pt and Cu-Pt and modelling surface segregation in Cu 3Pt alloys

    NASA Astrophysics Data System (ADS)

    Luyten, Jan; Schurmans, Maarten; Creemers, Claude; Bunnik, Bouke S.; Kramer, Gert Jan

    2007-07-01

    In this work, surface segregation to Cu 3Pt surfaces is studied with the modified embedded atom method (MEAM). This work is triggered by the catalytic importance of Cu-Pt alloys, together with the contradictory experimental results for the surface segregation in Cu 3Pt(1 1 1) alloys based on low energy ion scattering (LEIS) [Y.G. Shen, D.J. O'Connor, K. Wandelt, R.J. MacDonald, Surf. Sci. 328 (1995) 21] and low energy electron diffraction (LEED) [Y. Gauthier, A. Senhaji, B. Legrand, G. Tréglia, C. Becker, K. Wandelt, Surf. Sci. 527 (2003) 71]. In order to accurately describe the segregation behaviour in the Cu 3Pt system, a reliable potential, that is also applicable to surface phenomena, is indispensable. Therefore, first, new MEAM parameters are derived, consistently based on ab initio density functional theory (DFT) calculations, according to a method that is a modification of previous work [P. van Beurden, G.J. Kramer, Phys. Rev. B 63 (2001) 165106]. Upon testing, these parameters prove to reproduce very well various surface properties of this system. Next, Monte Carlo (MC) simulations combined with the newly derived MEAM potentials are set up to investigate surface segregation to low index single crystal surfaces. For the Cu 3Pt(1 1 1) surface, our MC/MEAM simulations agree completely with the available LEIS evidence and contradict the unusual depth profile based on LEED. However, the slight Pt enrichment observed in the LEED experiments can be reproduced by assuming a slight Pt excess in the bulk of the sample. The simulated composition depth profile, on the other hand, does not agree with the LEED evidence. Also, for the Cu 3Pt(1 0 0) surface, the MC/MEAM results agree completely with LEIS experiments. For the Cu 3Pt(1 1 0) surface, finally, the MC/MEAM simulations show a somewhat deviating behaviour with respect to the experimental LEIS evidence. The possibility of a missing-row reconstruction is evaluated, but cannot explain the discrepancy for the Cu 3Pt

  3. Precipitation in dilute Cu-Cr alloys; The effects of phosphorus impurities and aging procedure

    SciTech Connect

    Luo, C.P.; Dahmen, U.; Witcomb, M.J.; Westmacott, K.H. )

    1992-02-15

    This paper reports that precipitation in dilute Cu-Cr alloys has been studied extensively in part because this alloy can be used as a model system for the investigation of the crystallography and interfaces in FCC-BCC phase transformations. Hall et al. first reported needle- or lath-shaped Cr-rich precipitates with a {l brace}335{r brace}{sub f} habit plane and a variable orientation relationship ranging from Nishiyama-Wasserman (N-W) to Kurdjumov-Sachs (K-S). Hall and Aaronson later confirmed their early findings. Weatherly et al. however, found a constant K-S orientation relationship for this alloy system and a preferred growth direction of {l angle}651{r angle}{sub f} for the needle-shaped precipitates. The variation of the orientation relationship and its potential effect on the precipitate morphology and interface structure have become key points in studying the precipitate crystallography of this alloy system. Dahmen et al. attributed the variation of the orientation relationship to the different quenching and aging conditions applied to the alloy; a direct quench from the solutionizing to the aging temperature employed by Hall et al. would result in a heterogeneous nucleation and hence a variation in the precipitation behavior, while the water quench and aging procedure utilized by Weatherly et al, would facilitate homogeneous nucleation and produce a constant crysallography.

  4. Single-Step Production of Nanostructured Copper-Nickel (CuNi) and Copper-Nickel-Indium (CuNiIn) Alloy Particles

    NASA Astrophysics Data System (ADS)

    Apaydın, Ramazan Oğuzhan; Ebin, Burçak; Gürmen, Sebahattin

    2016-04-01

    Nanostructured copper-nickel (CuNi) and copper-nickel-indium (CuNiIn) alloy particles were produced from aqueous solutions of copper, nickel nitrates and indium sulfate by hydrogen reduction-assisted ultrasonic spray pyrolysis. The effects of reduction temperatures, at 973 K, 1073 K, and 1173 K (700 °C, 800 °C, and 900 °C), on the morphology and crystalline structure of the alloy particles were investigated under the conditions of 0.1 M total precursor concentration and 0.5 L/min H2 volumetric flow rate. X-ray diffraction studies were performed to investigate the crystalline structure. Particle size and morphology were investigated by scanning electron microscope and energy-dispersive spectroscopy was applied to determine the chemical composition of the particles. Spherical nanocrystalline binary CuNi alloy particles were prepared in the particle size range from 74 to 455 nm, while ternary CuNiIn alloy particles were obtained in the particle size range from 80 to 570 nm at different precursor solution concentrations and reduction temperatures. Theoretical and experimental chemical compositions of all the particles are nearly the same. Results reveal that the precursor solution and reduction temperature strongly influence the particle size of the produced alloy particles.

  5. Single-Step Production of Nanostructured Copper-Nickel (CuNi) and Copper-Nickel-Indium (CuNiIn) Alloy Particles

    NASA Astrophysics Data System (ADS)

    Apaydın, Ramazan Oğuzhan; Ebin, Burçak; Gürmen, Sebahattin

    2016-07-01

    Nanostructured copper-nickel (CuNi) and copper-nickel-indium (CuNiIn) alloy particles were produced from aqueous solutions of copper, nickel nitrates and indium sulfate by hydrogen reduction-assisted ultrasonic spray pyrolysis. The effects of reduction temperatures, at 973 K, 1073 K, and 1173 K (700 °C, 800 °C, and 900 °C), on the morphology and crystalline structure of the alloy particles were investigated under the conditions of 0.1 M total precursor concentration and 0.5 L/min H2 volumetric flow rate. X-ray diffraction studies were performed to investigate the crystalline structure. Particle size and morphology were investigated by scanning electron microscope and energy-dispersive spectroscopy was applied to determine the chemical composition of the particles. Spherical nanocrystalline binary CuNi alloy particles were prepared in the particle size range from 74 to 455 nm, while ternary CuNiIn alloy particles were obtained in the particle size range from 80 to 570 nm at different precursor solution concentrations and reduction temperatures. Theoretical and experimental chemical compositions of all the particles are nearly the same. Results reveal that the precursor solution and reduction temperature strongly influence the particle size of the produced alloy particles.

  6. In Vitro Degradation Behavior of Ternary Mg-Zn-Se and Mg-Zn-Cu Alloys as Biomaterials

    PubMed Central

    Persaud-Sharma, Dharam; Budiansky, Noah

    2013-01-01

    In this study, the corrosion behavior of Mg-Zn-Se and Mg-Zn-Cu alloys was investigated to evaluate their corrosion behavior related to use as implantable biomaterials. The corrosion behavior of these alloys and a commercially available Mg-Zn alloy were examined using static solution electrochemical testing, dynamic solution gravimetric testing, ion leaching testing, and microscopic evaluation. Fluctuations in the pH of the Dulbecco’s Modified Eagles Medium (DMEM) used for the gravimetric and ion leaching immersion testing were also recorded over the 30-day duration to assess whether the media conditions induced by the alloy degradation would permit for cellular survival. Weight loss experimentation and electrochemical tests revealed the Mg-Zn-Cu alloy to have the greatest corrosion rate. PMID:24465245

  7. Effects of Zr and Si on the Glass Forming Ability and Compressive Properties of Ti-Cu-Co-Sn Alloys

    NASA Astrophysics Data System (ADS)

    Wang, Tan; Wu, Yidong; Si, Jiajia; Hui, Xidong

    2015-06-01

    To succeed in finding novel Ti-based bulk metallic glasses, which are free from Be, Ni, and noble metallic elements, a comprehensive study was performed on the effects of Zr and Si on the microstructural evolution, glass-forming ability (GFA), and mechanical properties of Ti46Cu44- x Zr x Co7Sn3 ( x = 0, 5, 10, 12.5, and 16 at. pct) and Ti46Cu31.5Zr12.5- x Co7Sn3Si x ( x = 0.5, 1, and 1.5 at. pct) alloys. It is shown that with the increase of Zr, the sequence of phase formation is β-Ti + α-Ti + (Ti, Zr)3Cu4 ⇒ β-Ti + α-Ti + TiCu ⇒ β-Ti + Ti2Cu + glass ⇒ glass ⇒ β-Ti + Ti2Cu + TiCuSn. The quinary Ti-Zr-Cu-Co-Sn alloy with 12.5 pct Zr exhibits the best GFA. The addition of 1 pct Si results in the improvement of the critical size of glassy rods up to 3 mm in diameter. The yield stress and Young's modulus of Z-series alloys increases, and the plastic strain decreases with the addition of Zr. The yield stress and ultimate compression stress of Ti46Zr11.5Cu31.5Co7Sn3Si1 glassy alloy reach 2477.9 and 2623.3 MPa, respectively. It was found that the addition of Si promotes the generation and multiplication of shear bands, resulting in certain plasticity in these kinds of glassy alloys.

  8. Structural and optical characterization of 1 µm of ternary alloy ZnCuSe thin films

    NASA Astrophysics Data System (ADS)

    Shaaban, E. R.; Hassan, H. Shokry; Aly, S. A.; Elshaikh, H. A.; Mahasen, M. M.

    2016-08-01

    Different compositions of Cu-doped ZnSe in ternary alloy Zn1- x Cu x Se thin films (with x = 0, 0.025, 0.05, 0.075 and 0.10) were evaporated (thickness 1 µm) onto glass substrate using electron beam evaporation method. The X-ray diffraction analysis for both powder and films indicated their polycrystalline nature with zinc blende (cubic) structure. The crystallite size was found to increase, while the lattice microstrain was decreased with increasing Cu dopant. The optical characterization of films was carried out using the transmittance spectra, where the refractive indices have been evaluated in transparent and medium transmittance regions using the envelope method, suggested by Swanepoel. The refractive index has been found to increase with increasing Cu content. The dispersion of refractive index has been analyzed in terms of the Wemple-DiDomenico single-oscillator model. The oscillator parameters, the single-oscillator energy E o, the dispersion energy E d and the static refractive index n 0, were estimated. The optical band gap was determined in strong absorption region of transmittance spectra and was found to increase from 2.702 to 2.821 eV with increasing the Cu content. This increase in the band gap was well explained by the Burstein-Moss effect.

  9. NiCu Alloy Nanoparticle-Loaded Carbon Nanofibers for Phenolic Biosensor Applications

    PubMed Central

    Li, Dawei; Lv, Pengfei; Zhu, Jiadeng; Lu, Yao; Chen, Chen; Zhang, Xiangwu; Wei, Qufu

    2015-01-01

    NiCu alloy nanoparticle-loaded carbon nanofibers (NiCuCNFs) were fabricated by a combination of electrospinning and carbonization methods. A series of characterizations, including SEM, TEM and XRD, were employed to study the NiCuCNFs. The as-prepared NiCuCNFs were then mixed with laccase (Lac) and Nafion to form a novel biosensor. NiCuCNFs successfully achieved the direct electron transfer of Lac. Cyclic voltammetry and linear sweep voltammetry were used to study the electrochemical properties of the biosensor. The finally prepared biosensor showed favorable electrocatalytic effects toward hydroquinone. The detection limit was 90 nM (S/N = 3), the sensitivity was 1.5 µA µM−1, the detection linear range was 4 × 10−7–2.37 × 10−6 M. In addition, this biosensor exhibited satisfactory repeatability, reproducibility, anti-interference properties and stability. Besides, the sensor achieved the detection of hydroquinone in lake water. PMID:26610505

  10. A Cu/Pt Near-Surface Alloy for Water-Gas Shift Catalysis.

    SciTech Connect

    Knudsen, Jan; Nilekar, Anand U.; Vang, Ronnie T.; Schnadt, Joachim; Kunkes, Edward L.; Dumesic, James A.; Mavrikakis, Manos; Besenbacher, Fleming

    2007-05-01

    The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. The primary route to hydrogen production from fossil fuels involves the water-gas shift (WGS) reaction, and an improvement in the efficiency of WGS catalysts could therefore lead to a major leap forward in the realization of hydrogen economy. On the basis of a combination of high-resolution scanning tunneling microscopy, X-ray photoelectron spectroscopy, and density functional theory (DFT) calculations, we suggest the existence of a new thermodynamically stable Cu/Pt near-surface alloy (NSA). Temperature-programmed desorption and DFT reveal that this Cu/Pt NSA binds CO significantly more weakly than does Pt alone, thereby implying a considerable reduction in the potential for CO poisoning of the Cu/Pt NSA surface as compared to that of pure Pt. In addition, DFT calculations show that this Cu/Pt NSA is able to activate H2O easily, which is the rate-determining step for the WGS on several metal surfaces, and, at the same time, to bind the products of that reaction and formate intermediates rather weakly, thus avoiding possible poisoning of the catalyst surface. The Cu/Pt NSA is thus a promising candidate for an improved WGS catalyst.

  11. Physical preparation and optical properties of CuSbS2 nanocrystals by mechanical alloying process

    NASA Astrophysics Data System (ADS)

    Zhang, Huihui; Xu, Qishu; Tan, Guolong

    2016-08-01

    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. [Figure not available: see fulltext.

  12. Nanocrystalline CuNi alloys: improvement of mechanical properties and thermal stability

    NASA Astrophysics Data System (ADS)

    Nogues, Josep; Varea, A.; Pellicer, E.; Sivaraman, K. M.; Pane, S.; Nelson, B. J.; Surinach, S.; Baro, M. D.; Sort, J.

    2014-03-01

    Nanocrystalline metallic films are known to benefit from novel and enhanced physical and chemical properties. In spite of these outstanding properties, nanocrystalline metals typically show relatively poor thermal stability which leads to deterioration of the properties due to grain coarsening. We have studied nanocrystalline Cu1-xNix (0.56 < x < 1) thin films (3 μm-thick) electrodeposited galvanostatically onto Cu/Ti/Si (100) substrates. CuNi thin films exhibit large values of hardness (6.15 < H < 7.21 GPa), which can be tailored by varying the composition. However, pure Ni films (x = 1) suffer deterioration of their mechanical and magnetic properties after annealing during 3 h at relatively low temperatures (TANN > 475 K) due to significant grain growth. Interestingly, alloying Ni with Cu clearly improves the thermal stability of the material because grain coarsening is delayed due to segregation of a Cu-rich phase at grain boundaries, thus preserving both the mechanical and magnetic properties up to higher TANN.

  13. Transverse-Weld Tensile Properties of a New Al-4Cu-2Si Alloy as Filler Metal

    NASA Astrophysics Data System (ADS)

    Sampath, K.

    2009-12-01

    AA2195, an Al-Cu-Li alloy in the T8P4 age-hardened condition, is a candidate aluminum armor for future combat vehicles, as this material offers higher static strength and ballistic protection than current aluminum armor alloys. However, certification of AA2195 alloy for armor applications requires initial qualification based on the ballistic performance of welded panels in the as-welded condition. Currently, combat vehicle manufacturers primarily use gas metal arc welding (GMAW) process to meet their fabrication needs. Unfortunately, a matching GMAW consumable electrode is currently not commercially available to allow effective joining of AA2195 alloy. This initial effort focused on an innovative, low-cost, low-risk approach to identify an alloy composition suitable for effective joining of AA2195 alloy, and evaluated transverse-weld tensile properties of groove butt joints produced using the identified alloy. Selected commercial off-the-shelf (COTS) aluminum alloy filler wires were twisted to form candidate twisted filler rods. Representative test weldments were produced using AA2195 alloy, candidate twisted filler rods and gas tungsten arc welding (GTAW) process. Selected GTA weldments produced using Al-4wt.%Cu-2wt.%Si alloy as filler metal consistently provided transverse-weld tensile properties in excess of 275 MPa (40 ksi) UTS and 8% El (over 25 mm gage length), thereby showing potential for acceptable ballistic performance of as-welded panels. Further developmental work is required to evaluate in detail GMAW consumable wire electrodes based on the Al-Cu-Si system containing 4.2-5.0 wt.% Cu and 1.6-2.0 wt.% Si.

  14. A Yolk-Shell Design for Stabilized and Scalable Li-Ion Battery Alloy Anodes

    SciTech Connect

    Liu, Nian; Wu, Hui; McDowell, Matthew T.; Yao, Yan; Wang, Chongmin; Cui, Yi

    2012-05-02

    Silicon is regarded as one of the most promising anode materials for next generation lithium-ion batteries. For use in practical applications, a Si electrode must have high capacity, long cycle life, high efficiency, and the fabrication must be industrially scalable. Here, we design and fabricate a yolk-shell structure to meet all these needs. The fabrication is carried out without special equipment and mostly at room temperature. Commercially available Si nanoparticles are completely sealed inside conformal, thin, self-supporting carbon shells, with rationally designed void space in between the particles and the shell. Finally, the well-defined void space allows the Si particles to expand freely without breaking the outer carbon shell, therefore stabilizing the solid-electrolyte interphase on the shell surface. High capacity (~2800 mAh/g at C/10), long cycle life (1000 cycles with 74% capacity retention), and high Coulombic efficiency (99.84%) have been realized in this yolk-shell structured Si electrode.

  15. Sputtering deposition of aluminium molybdenum alloy thin film anodes for thin film microbatteries

    NASA Astrophysics Data System (ADS)

    Thirumoolam, Mani Chandran; Sivaramakrishnan, Balaji; Devarajan, Mutharasu

    2015-05-01

    Al5Mo thin film anodes for Li-ion batteries were prepared using DC sputtering under different conditions, the latter being specified as deposition at room temperature (S0), deposition at 300°C (S1), and deposition at room temperature followed by thermal annealing at 300°C (S2). The thin films were deposited using an aluminum target tiled with molybdenum discs at a ratio calculated based on the theoretical sputtering yields. The structural and compositional analyses performed with x-ray diffraction (XRD) and energy-dispersive x-ray spectroscopy (EDX) confirmed the Al5Mo compound formation and the Al/Mo elemental ratio, respectively. The compound formation was observed to be evident only for the thin films subjected to heat treatment during or after deposition. Scanning electron micrographs reveal a higher porosity of approximately 23% for sample S0 and a lower porosity of around 18% for sample S1. The chronopotentiometry results show a higher volumetric specific capacity of approximately 197 mAh/cm3 for sample S1. Capacity increments have been observed for all samples upon charge-discharge cycles, whose values after 25 cycles for samples S0, S1, and S2 were 41.2%, 20.4%, and 21.1%, respectively. [Figure not available: see fulltext.

  16. A yolk-shell design for stabilized and scalable li-ion battery alloy anodes.

    PubMed

    Liu, Nian; Wu, Hui; McDowell, Matthew T; Yao, Yan; Wang, Chongmin; Cui, Yi

    2012-06-13

    Silicon is regarded as one of the most promising anode materials for next generation lithium-ion batteries. For use in practical applications, a Si electrode must have high capacity, long cycle life, high efficiency, and the fabrication must be industrially scalable. Here, we design and fabricate a yolk-shell structure to meet all these needs. The fabrication is carried out without special equipment and mostly at room temperature. Commercially available Si nanoparticles are completely sealed inside conformal, thin, self-supporting carbon shells, with rationally designed void space in between the particles and the shell. The well-defined void space allows the Si particles to expand freely without breaking the outer carbon shell, therefore stabilizing the solid-electrolyte interphase on the shell surface. High capacity (∼2800 mAh/g at C/10), long cycle life (1000 cycles with 74% capacity retention), and high Coulombic efficiency (99.84%) have been realized in this yolk-shell structured Si electrode. PMID:22551164

  17. Consolidation processing parameters and alternative processing methods for powder metallurgy Al-Cu-Mg-X-X alloys

    NASA Technical Reports Server (NTRS)

    Sankaran, K. K.

    1987-01-01

    The effects of varying the vacuum degassing parameters on the microstructure and properties of Al-4Cu-1Mg-X-X (X-X = 1.5Li-0.2Zr or 1.5Fe-0.75Ce) alloys processed from either prealloyed (PA) or mechanically alloyed (M) powder, and consolidated by either using sealed aluminum containers or containerless vacuum hot pressing were studied. The consolidated billets were hot extruded to evaluate microstructure and properties. The MA Li-containing alloy did not include Zr, and the MA Fe- and Ce-containing alloy was made from both elemental and partially prealloyed powder. The alloys were vacuum degassed both above and below the solution heat treatment temperature. While vacuum degassing lowered the hydrogen content of these alloys, the range over which the vacuum degassing parameters were varied was not large enough to cause significant changes in degassing efficiency, and the observed variations in the mechanical properties of the heat treated alloys were attributed to varying contributions to strengthening by the sub-structure and the dispersoids. Mechanical alloying increased the strength over that of alloys of similar composition made from PA powder. The inferior properties in the transverse orientation, especially in the Li-containing alloys, suggested deficiencies in degassing. Among all of the alloys processed for this study, the Fe- and Ce-containing alloys made from MA powder possessed better combinations of strength and toughness.

  18. An evaluation of the benefits of utilizing rapid solidification for development of 2XXX (Al-Cu-Mg) alloys

    NASA Technical Reports Server (NTRS)

    Paris, H. G.; Chellman, D. J.

    1986-01-01

    The advantages of rapid solidification processing over ingot metallurgy processing in the development of 2XXX aluminum alloy compositions were evaluated using a similarly processed ingot metallurgy (IM) control alloy. The powder metallurgy (PM) alloy extrusions showed a reduced age-hardening response in comparison with similar IM compositions, with higher tensile properties for naturally aged extrusions but lower properties for artificially aged ones. However, the tensile properties of naturally and artificially aged PM alloy extrusions based on a version of IM 2034 alloy, but containing 0.6 weight percent zirconium, were comparable to those of the IM control extrusions and had significantly superior combinations of strength and toughness. The tensile properties of this PM alloy showed even greater advantage in 6.4-mm (0.25-in.) and 1.8-mm (0.070-in.) plate and sheet, the yield strength being about 68 MPa (10 ksi) greater than reported values for the IM 2034 alloy sheet. An artificially aged PM alloy based on 2219 alloy also showed a strength and strength-toughness combination comparable to those of the PM Al-Cu-Mg-Zr alloy, substantially outperforming the IM 2219 alloy. These results show that rapid solidification offers the flexibility needed to modify conventional IM compositions to produce new alloy compositions with superior mechanical properties.

  19. Effect of the composition of Ti alloy on the photocatalytic activities of Ti-based oxide nanotube arrays prepared by anodic oxidation

    NASA Astrophysics Data System (ADS)

    Tang, Dingding; Wang, Yixin; Zhao, Yuwei; Yang, Yijia; Zhang, Lieyu; Mao, Xuhui

    2014-11-01

    Three types of Ti-based oxide nanotube arrays are prepared by anodic oxidation of pure Ti and Ti alloys (Ti-0.2Pd and Ti-6Al-4V) in the glycol-2 wt% H2O-0.3 wt% NH4F solution. The nanotube arrays are characterized by a series of techniques, including SEM, TEM, EIS, XRD, EDS, ICP, XPS and UV-vis DRS, to elucidate the effect of alloying elements on the properties of titania nanotube arrays. The results suggest that aluminium and vanadium elements greatly slow down the growth rate and therefore decrease the yield of nanotube arrays. Al and V deteriorate the photoreactivity of the resultant nanotube arrays. The palladium inside the Ti-0.2Pd alloy-derived nanotube arrays cannot be detected by EDS or XPS, but is quantitatively determined by ICP analysis. Incorporation of Pd significantly improves the photocatalytic activity of the resultant titania nanotube arrays powder. The presence of Pd element not only enhances the light absorption, but also facilitates the separation of photogenerated charge carriers. The uniform doping of Pd into the microstructure endows nanotube arrays with resistance to sulphur poison and preferable stability for organic degradation. This study suggests that anodization of Ti alloys, rather than pure Ti metal, allows to produce micron-sized high-performance photocatalysts for environmental and energy applications.

  20. Synthesis and electrochemical performances of LiNiCuZn oxides as anode and cathode catalyst for low temperature solid oxide fuel cell.

    PubMed

    Jing, Y; Qin, H; Liu, Q; Singh, M; Zhu, B

    2012-06-01

    Low temperature solid oxide fuel cell (LTSOFC, 300-600 degrees C) is developed with advantages compared to conventional SOFC (800-1000 degrees C). The electrodes with good catalytic activity, high electronic and ionic conductivity are required to achieve high power output. In this work, a LiNiCuZn oxides as anode and cathode catalyst is prepared by slurry method. The structure and morphology of the prepared LiNiCuZn oxides are characterized by X-ray diffraction and field emission scanning electron microscopy. The LiNiCuZn oxides prepared by slurry method are nano Li0.28Ni0.72O, ZnO and CuO compound. The nano-crystallites are congregated to form ball-shape particles with diameter of 800-1000 nm. The LiNiCuZn oxides electrodes exhibits high ion conductivity and low polarization resistance to hydrogen oxidation reaction and oxygen reduction reaction at low temperature. The LTSOFC using the LiNiCuZn oxides electrodes demonstrates good cell performance of 1000 mW cm(-2) when it operates at 470 degrees C. It is considered that nano-composite would be an effective way to develop catalyst for LTSOFC. PMID:22905585