Cu In Alloy Research Articles

Effect of Hot Rolling on Grain Refining Performance of Al–5Ti–1B Master Alloy on Hot Tearing on Al–7Si–3Cu Alloy

It has been known experimentally that TiAl3 acts as a powerful nucleant for the solidification of aluminum from the melt; however, a full microscopic understanding is still lacking. To improve microscopic understanding, hot rolling technique has been performed to the Al–5Ti–1B alloy and the effect of shape and size of the particles on grain refinement has been studied. The effect of hot rolling of Al–5Ti–1B master alloy on its grain refining performance and hot tearing have been studied by OM, XRD, and SEM. Hot rolling improves the grain refining performance of this master alloy, which is required to reduce hot tearing in Al–7Si–3Cu alloy. The improvement in grain refining performance of Al–5Ti–1B master alloy on rolling is due to the fracture of larger TiAl3 particles into fine particles during rolling. The presented results illustrate that the morphology of TiAl3 particles alter from the plate-like structure in the as-cast condition Al–5Ti–1B master alloy to the blocky type after rolling due to the fragmentation of plate-like structures. The grain refining response and effect on hot tearing of Al–7Si–3Cu alloy have been studied with as-cast and rolled Al–5Ti–1B master alloys. The results display hot-rolled master alloys revealing enhanced grain refining performance and minimizing hot tear tendency of the alloy at much lower addition level as compared to as-cast master alloys.

Effect of the addition of Sb and rare-earth elements La and Nd on the properties of Cu/6061Al with Zn–10Al–5Cu filler metals

The wetting ability, mechanical properties and microstructure distribution of a new solder based on a Zn–10Al–5Cu alloy with different amounts of Sb and rare earths added were studied. The results indicate that the spreading area of solder alloy decreases first and then increases and the shear strength of the Copper–aluminum joint increases with the increase of Sb element. The microstructure of the brazed weld matrix was refined. The Zn–10Al–5Cu–1.5Sb solder obtained by the test had better properties. Then, the rare earth (La and Nd) was added in Zn–10Al–5Cu–1.5Sb filler metal. It makes the wettability further improved. The wetting property of solder was the best with the 0.15 wt% RE addition. The large black eutectoid microstructure in the matrix become smaller and the number of IMC near the copper side increases with the addition of rare earth elements. The shear strength of brazed seam reaches the maximum when the content of rare earth element is 0.15%. Therefore, the optimum addition amount of the rare earth in Zn–10Al–5Cu–1.5Sb is about 0.15%.

Influences of Mg content on the microstructures and mechanical properties of cast Al–2Li–2Cu–0.2Zr alloy

This work was undertaken to investigate the influences of Mg content on the microstructure and mechanical properties of cast Al–2Li–2Cu–0.2Zr alloy. The addition of increasing amounts of Mg led to continuous grain refinement of as-cast base alloy accompanied by the increased volume fraction of secondary phases distributed along grain boundaries or interdendritic regions. The tensile test results showed that Mg addition could greatly enhance the mechanical properties of the base alloy after subjected to the solution treatments and artificial ageing. The precipitation behavior and microstructural evolution were also investigated. The addition of Mg would facilitate the nucleation of δ′ (Al3Li) phases after quenching. The presence of Mg was observed to lower the growth rate of δ′ and δ′-precipitation-free zones (δ′-PFZs) of the base alloy. Precipitation of θ′ (Al2Cu) phase would be almost suppressed, and S′ (Al2CuMg) phase was consequently introduced due to Mg additions. The precipitation of S′ phases was encouraged at the expense of T1 (Al2CuLi) phases as the Mg content increased. The increased amount of S′ phases tended to coalesce to form coarse laths distributed in uneven manner for alloys with relatively high Mg content (≥ 1 wt%). No improvements in mechanical properties were observed in alloys with heterogeneous distribution of coarse S′ laths. The optimal Mg addition in cast Al–2Li–2Cu alloy was 0.5 wt%.

Evolution of the As‐Cast Grain Microstructure of an Ultrasonically Treated Al–2Cu Alloy

The evolution of the grain structure of an Al–2Cu alloy is investigated numerically during its solidification while being subjected to ultrasonic treatment. A CAFE (Cellular Automation Finite Element) model coupling fluid flow, heat transfer, nucleation, and grain growth is developed and validated by comparing the results of both numerical simulations and physical experiments. The model successfully describes hydrodynamic fields generated by ultrasonic treatment and their influence on microstructural evolution. This validated model is then used to study the influence of the duration of ultrasonic treatment on temperature distribution and grain structure. A predominantly equiaxed grain structure developed due to the low temperature gradient throughout the melt is a result of the enhanced convection. These results highlight the critical role played by the convection induced by acoustic streaming during casting, that is, facilitating nucleation and grain growth.

Al–7Si–5Cu/Al2O3–ZrO2 Laminated Composites with Excellent and Anisotropic Wear Resistance

The authors prepare nacre‐mimetic Al−7Si−5Cu/Al2O3−ZrO2 composites with alternately arranged soft‐hard phases and different ceramic compositions using freeze casting and gas‐pressure infiltration techniques and investigate their dry abrasive wear resistance. These composites exhibit excellent and anisotropic wear resistance when worn along different directions. The wear rates of the composite with Al2O3:ZrO2 = 1:9 against 400‐grit, 240‐grit, and 100‐grit SiC sandpapers are approx. 1/78, 1/37, and 1/27 of those of the Al−7Si−5Cu alloy. The underlying mechanisms for the excellent wear resistance of these nacre‐mimetic composites are ascribed to the “self‐sharpen” effect in the early running‐in period and the formation of friction films in the later wear period. Moreover, the anisotropic wear resistance is interpreted by the different stress states that the interface is subjected to.

Influence of Sr addition on microstructure of the hypereutectic Zn\u2013Al\u2013Cu alloy

The purpose of the presented work is to answer the questions: how does the addition of strontium to the Zn–8Al–1Cu alloy crystallisation kinetics influence? What will the significance of the low temperature of heat treatment, characteristic for eutectic Zn–Al alloys, have for the formation of intermetallic phases? To describe the phenomena that occur in the metal during solidification under various conditions caused by the variable cooling rate, and as a result of the application of modifiers that provide the basis for heterogeneous nucleation, it was decided to use thermal-derivative analysis method. The mentioned method allows to accurately describe and interpret the kinetics of crystallisation of the tested materials. The effectiveness of the modification was assessed based on a degree of fragmentation of the structural components and changes in the properties of the material being modified, as well as by analysis of the cooling curves of the tested alloys. The thermal events occurring during solidification process, i.e. liquidus (TL) and solidus (TSol) temperatures and the beginning of phases and eutectic nucleation, were determined with the thermal-derivative analysis and calculation of total heat of crystallisation of the analysed material.

Studies on Dissimilar Friction Stir Welded Al–4Cu–TiB<sub>2 </sub> <i>In Situ </i>Composites with Base Alloy

Friction stir welding was performed on Al–4Cu alloy and Al–4Cu in situ composites reinforced with TiB2 with various reinforcement contents (3wt% and 6wt%), which were fabricated using a stir-casting route. The fully annealed and solutionized alloy and the in situ composites were friction stir welded using an M6 threaded pin tool operated at a constant rotational speed (1400 r/min) and traverse speed (40 mm/min); the welding was performed with the composites to base alloy on both the advancing and retreating sides of the welding tool in different experiments. Mechanical properties such as hardness and tensile behavior were evaluated for samples in both the as-welded and post-weld-aged conditions. An increase in the amount of reinforcement material in the Al-based composites caused the retreating side to exhibit better mechanical properties than the advancing side. The hardness values of the first mode and second mode in the weld nugget varied with respect to the reinforcement content of the composite and with respect to whether the composite in the retreating side or the advancing side in the weldments. The fractography details are also presented.

Aqueous Phase Synthesis Method of Fe Metal Nanoparticles and Its Application for Commercial Materials

It is well known that the melting point of metal element drastically change with decreasing the diameter of its particle into nano level, by obeying to the equation as follows, Tnano = Tbulk (1-2σ/(ΔH*R)) Here, Tnano is melting point of nanoparticles. Tbulk is melting point of bulk material, σ is surface energy, ΔH is enthalpy change of melting, and R is radius. Thus, the development of effective and green synthesis method of Fe nanoparticles means the development of new bonding method of Irons at low temperature, since Fe is most basic materials in resent world. Fe nanoparticles were synthesized only in acidic solution by using strong reducing reagent, while it cannot be achieved in basic solution since iron hydroxide, which is easily formed in this condition, cannot be reduced into metals. However, former is not suitable for commercial synthesis method because of its intense reducing process. Thus, the reducing rout of Fe species under basic condition should be developed. Here, until now, we tried to synthesized various metal/alloy nanoparticles, such as Pd20Te7 nanoparticles and uniform Cu-In (CI) alloy nanoparticles, by utilizing the restrict metallic complexes controlling method in an aqueous solution under room temperature. In this method, reduction potential of the metal species can be controlled under the room temperature, consequently metal/alloy nanomaterials with uniform and well crystallized structure can be successfully synthesized. Therefore, in this study, aqueous phase synthesis method of Fe metal nanoparticles were developed. To achieve the homogeneous reaction condition, metal complex species in the aqueous phase were restricted into single species by using calculation. Reduction potential of homogenized metal complex were analyzed by using cyclic voltammetry. Fe nanoparticles were synthesized by using chemical reduction method under ambient conditions using metal chlorides as metal sources and sodium borohydride as a reducing agent. Calculation results indicated that Fe complex can be restricted into one species as the function of pH, complexing reagent species and/also concentration. For example, Fe complex can be restricted into Fe(NTA)2 only, in the case of 8<pH<11. By using these homogeneous condition, metal Fe nanoparticles were successfully synthesized. Other results, such as melting and/or bonding condition of synthesized materials, will present in our presentation. [1] H. Takahashi et.,al, Applied Catalysis A: General 392 (2011) 80–85

Aqueous Phase Synthesis of CuIn Alloy Nanoparticles and Their Application for a CIS (CuInSe₂)-Based Printable Solar Battery.

To apply CuInSe2 (CIS)-based printable solar batteries; an aqueous phase synthesis method of Cu-In (CI) alloy nanoparticles is studied. Metal complexes in the original solution are restricted to homogenized species by utilizing calculations. For example; [(Cu2+)(ASP2−)2] [ASP: the “body (C4H5O4N)” of aspartic acid (C4H7O4N)] is predominant in the pH 6–13 region (CASP/CCu > 6); while In complexes can be restricted to [(In3+)(OH−)(EDTA4−)] (pH 10–12; CEDTA/CIn = 2) and/or [(In3+)(ASP2−)2] (pH 7–9; CASP/CIn = 5). These results indicate that the added amount of complex reagents should be determined by calculations and not the stoichiometric ratio. The reduction potential of homogenized metal complex is measured by cyclic voltammetry (CV) measurements and evaluated by Nernst’s equation using the overall stability constants. CuIn alloy nanoparticles with a small amount of byproduct (In nanoparticles) are successfully synthesized. The CI precursor films are spin-coated onto the substrate using a 2-propanol dispersion. Then the films are converted into CIS solar cells; which show a maximum conversion efficiency of 2.30%. The relationship between the open circuit potential; short circuit current density; and fill factor indicate that smoothing of the CIS films and improving the crystallinity and thickness increase the solar cell conversion efficiency.

Lead-Free Alternatives for Interconnects in High-Temperature Electronics

Predominant high melting point solders for high-temperature and harsh environment electronics (operating temperatures from 200 to 250 °C) are Pb-based systems, which are being subjected to RoHS regulations because of their toxic nature. In this study, high bismuth (Bi) alloy compositions with Bi-XSb-10Cu (X from 10 wt % to 20 wt %) were designed and developed to evaluate their potential as high-temperature, Pb-free replacements. Reflow processes were developed to make die-attach samples made from the cast Bi alloys. Die-attach joints made from Bi-15Sb-10Cu alloy exhibited an average shear strength of 24 MPa, which is comparable to that of commercially available high Pb solders. These alloy compositions also retained original shear strength even after thermal shock (TS) between −55 °C and +200 °C and high-temperature storage (HTS) at 200 °C. Brittle interfacial fracture sometimes occurred along the interfacial NiSb layer formed between Bi(Sb) matrix and Ni metallized surface. In addition, heat dissipation capabilities, using flash diffusivity, were measured on the die-attach assembly and were compared to the corresponding bulk alloys. The thermal conductivity of all the Bi–Sb alloys was higher than that of pure Bi. By creating high volume fraction of precipitates in a die-attach joint microstructure, it was feasible to further increase thermal conductivity of this joint to 24 W/m·K, which is three times higher than that of pure Bi (8 W/m·K). Bi–15Sb–10Cu alloy has so far shown the most promising performance as a die-attach material for high-temperature applications (operated over 200 °C). Hence, this alloy was further studied to evaluate its potential for plastic deformation. Bi–15Sb–10Cu alloy has shown limited plastic deformation in room temperature tensile testing in which premature fracture occurred via the cracks propagated on the (111) cleavage planes of rhombohedral crystal structure of the Bi(Sb) matrix. The same alloy has, however, shown up to 7% plastic strain under tension when tested at 175 °C. The cleavage planes, which became oriented at smaller angles to the tensile stress, contributed to improved plasticity in the high-temperature test.

Effect of copper content on the corrosion behaviors and antibacterial properties of binary Mg–Cu alloys

Biodegradable Mg–Cu alloys have attracted many researchers attention due to their characteristics of osteogenesis, angiogenesis, and long-lasting antibacterial effects. In this paper, the effect of copper content on the corrosion behaviors and antibacterial properties of binary Mg–Cu alloys was studied. Microstructure characterization, immersion test, electrochemical test and antibacterial test were carried out. The results show that with the increase of Cu content, the corrosion rate of Mg–Cu alloys was increased greatly due to the galvanic corrosion between Mg matrix and Mg2Cu intermetallic phase. The corrosion rate of Mg–0·3Cu alloy was almost 10 times as fast as Mg–0·1Cu alloy in 0·9 wt-% NaCl solution. Antibacterial test showed that Mg–Cu alloys could efficiently reduce the viability of Candida albicans with the addition of Cu above 0·1 wt-%. Mg–0·1Cu has good potential to be used as antibacterial implants due to its good corrosion resistance and antibacterial property.

One-dimensional CuIn alloy nanowires as a robust and efficient electrocatalyst for selective CO2-to-CO conversion

Electrical anodization of Cu foil produces one-dimensional Cu nanowires of high surface areas, which turns to CuIn alloy nanowires by indium electrodeposition replacing edge site Cu atoms. An electrochemical pre-activation forms a highly conformal amorphous In(OH)3 overlayer with oxygen vacancy on the CuIn alloy that facilitates CO2 adsorption to promote selective CO formation suppressing competing H2 adsorption. Thus the activated CuIn alloy nanowires catalyse electrochemical CO2 conversion to CO with high CO selectivity (>68.2%) and high current density (ca. −3.9 mAcm−2) at −0.6 VRHE, which represents the higher partial CO current density (ca. −2.66 mAcm−2) than that of previously reported CuIn alloy powders without nanostructuring. The performance remains stable for more than 15 h without significant degradation.

Reduction of CO2 to Ethanol on Cu-In/CuInS2 Composite Thin Film Photocathode

The challenge of photoelectrochemical reduction of CO2 is to design highly selective, highly efficient and non-precious metal catalysts. In this study, Cu-In alloy nanoparticles-modified CuInS2 (Cu-In/CuInS2) composite thin film electrodes are fabricated by electrodeposition of Cu-In alloy nanoparticles on the CuInS2 thin films. At Cu-In electrodeposition time of 10 s, the relative content of indium in Cu-In/CuInS2 composite thin film electrodes is the highest; and the resulted electrode exhibits the highest catalytic activity of ethanol. The electrochemical impedance spectroscopy results show that the rate of CO2 reduction is determined by both the charge transfer resistance and mass transport limitation. The modification of the Cu-In alloy significantly improves the surface coverage of the adsorbed CO and inhibits hydrogen evolution reaction, thus promotes the C-C coupling. Therefore the selectivity for the formation of ethanol is improved pronouncedly.

Structure and photoelectrochemistry of silver-copper-indium-diselenide ((AgCu)InSe2) thin film

In this work, silver (Ag) precursors with different thicknesses were sputtered on the surfaces of CuIn alloys, and (AgCu)InSe2 (ACIS) films were formed after selenization at 550 °C under nitrogen condition using a rapid thermal process furnace. The structure and electrical properties of the ACIS films were investigated. The result showed that the distribution of Ag+ ion was more uniform with increasing the thickness of Ag precursor, and the surface of the thin-film became more homogeneous and denser. When Ag/Cu ratio ≥0.249, the small grain particles disappeared. The band gap can be rationally controlled by adjusting Ag content. When (Ag + Cu)/In ratio ≥ 1.15, the surface of the ACIS thin-film mainly exhibited n-type semiconductor. Through the photoelectrochemistry measurement, it was observed that the incorporation of Ag+ ions could improve photocurrent by adjusting the band gap. With the Ag precursor thickness increased, the dark current decreased at the more negative potential.

Effects of Cu content on the wettability of SiC with Al-Ti-Si-xCu alloy and bending strength of resulting SiC matrix composite

The effects of the addition of Cu in an Al-Ti-Si alloy on the wettability of the ceramic SiC with respect to the resulting Al-Ti-Si-xCu alloy as well as the bending strength of the resulting composite were investigated. The melting point of the Al-Ti-Si-xCu alloy decreased with an increase in the Cu content, which facilitated the diffusion of the alloying elements. The first and second stages of the wetting process were promoted. The contact angles of 0Cu, 5Cu, and 10Cu after heating at 900°C for 10min were 102°, 90° and 89°, respectively. However, after 210min, they were similar at approximately 40°, as no new phases were formed at the interface. In addition, the three-point bending strength of the infiltrated SiC ceramic samples was almost twice that of the original one. As the Cu content was increased from 0 to 10wt%, the relative volume fraction of Ti3Si(Al)C2 increased. However, for a Cu content of 10wt%, the bonding rate between Al and SiC decreased. Therefore, the three-point bending strength of the infiltrated composite was the highest at 433MPa in the case of the sample infiltrated with the 5Cu alloy at 900°C for 6h.

The heat treatment response of semisolid formed Al–5Fe–4Cu alloy

The effect of heat treatment on both microstructures and performances of semisolid Al–5Fe–4Cu alloy was investigated with scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) and tensile test. The results showed that the semi-solid Al–5Fe–4Cu alloy’s response to the solution heat treatment (SHT) is abnormal compared with the conventional semi-solid Al alloys, i.e. the tensile properties of the semi-solid Al–5Fe–4Cu alloy decreased significantly after SHT. Nevertheless, the semi-solid Al–5Fe–4Cu alloy subject to direct ageing without SHT could exhibit conspicuous improvement of the tensile properties. And, the reason of the abnormal results has been analysed and discussed in detail.

ТЕРМОДИНАМИЧЕСКИЕ СВОЙСТВА ТВЕРДЫХ РАСТВОРОВ В СИСТЕМЕ Cu8GeS6 - Ag8GeS6

Измерением ЭДС концентрационных цепей с твердым электролитом Cu4RbCl3I2 в интервале температур 300÷380 К изучена система Cu8GeS6-Ag8GeS6. Показано образование широких областей твердых растворов на основе исходных соединений. Из данных измерений ЭДС вычислены парциальные молярные функции меди в сплавах.

Evaluation of hardening and softening behaviors in Zn–21Al–2Cu alloy processed by equal channel angular pressing

The microstructural evolution of as-cast and homogenized Zn–21Al–2Cu samples after two and six passes in an equal channel angular pressing (ECAP) at room temperature was reported. A homogenization treatment for 24h at 350°C was applied to the as-cast samples followed by deformation. An annealing heat treatment was performed on all samples after the ECAP process. Our results showed that the homogenized and deformed samples displayed a uniform fine-grained microstructure after annealing, while as-cast samples without homogenization treatment presented only some regions of fine-grained microstructure. The level of microsegregation was higher in the as-cast samples as compared to the homogenized ones even after annealing. Vickers microhardness measurement on samples after deformation is smaller than the original material indicating a softening. However, after the annealing treatment, the microhardness increased, indicating that there was a slight hardening of the material.

Influence of low-frequency vibrations on the structure of amorphous Ti40.7Hf9.5Ni44.8Cu5 alloy

The amorphous Ti40.7Hf9.5Ni44.8Cu5 melt-span ribbon samples were subjected to low-frequency vibrations (20Hz) with an amplitude of 1 or 4μm at room temperature to study the influence of the vibrations on the structural relaxation and the crystallization of amorphous alloy. The results obtained showed that the samples retained the amorphous structure after low-frequency vibrations but the resistivity decreased due to some structural relaxation. It was found that the low-frequency vibrations with an amplitude of 4μm led to the formation of nanoclusters with ordered atomic position in the amorphous structure, but it hardly affected the crystallization temperatures.

Fabrication and characterization of porous Ti–10Cu alloy for biomedical application

Porous titanium alloy has been a kind of biocompatible and attractive biomaterial used for orthopedic prosthesis. Porous Ti–10Cu (wt.%) alloys have been fabricated using powder metallurgy approach from TiH2 and Cu powders in this paper. XRD results indicate that the phase constituents of the sintered porous alloy are independent of addition of space holder agent NH4HCO3 granules. Pore characteristics like pore morphology and porosity of porous Ti–10Cu alloys depend strongly on the contents of added space-holder. The low porosity alloy consists of isolated and closed macro-pores as well as interconnected micro-pores. The high porosity alloy is composed of interconnected open macro-pores and micro-pores. The tailored elastic modulus and compressive strength of the alloy decrease with the increase of porosity. Electrochemical measurements show that the corrosion resistance of the porous alloy degrades with the increase of porosity. The pore size, elastic modulus and compressive strength of porous Ti–10Cu alloy with porosity of 53% meet the preliminary requirements of cancellous bones.