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The two-way shape memory effect with reversible compressive strain up to 5.1% and high cyclic stability is obtained for Ni44Fe19Ga27Co10 (at.%) single crystals by stress-induced martensite aging at 398 K for 1–3 h, under 650 MPa. 100 cycles of thermal treatment at temperatures not exceeding aging temperature, do not affect the temperature of the martensite formation, and reversible strain reduces merely by 0.4%. Thermal cycling with aging overheating significantly decreases reversible strain down to 1% due to the austenite stabilization. [ABSTRACT FROM AUTHOR]

γ-TiAlNb intermetallic compound is a highly promising material for aircraft structural components. A 46Ti-46Al-8Nb intermetallic compound was prepared and subjected to three different heat treatments. The changes in phase composition, microstructure, and hardness of the as-cast samples and heat-treated samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and Rockwell hardness. Subsequently, the material was designed for milling of thin-wall structures, with a focus on side milling. The milling process was investigated under different axial and radial cutting depths, and the variations in multi-directional cutting forces were analyzed, taking into consideration the surface quality of the machined parts. The results indicate that the γ-TiAlNb intermetallic compound possesses high hardness and brittleness. With increasing heat treatment temperature, the content of TiAl phase significantly decreases, while the content of AlTi3 phase increases notably. The β-Ti phase containing Nb remains nearly unchanged and is mainly located at grain boundaries. Heat treatment can enhance the machinability of the TiAlNb intermetallic compound. A heat treatment process involving a 1-hour hold at 1200 °C followed by furnace cooling results in reduced Rockwell hardness, lower milling forces in three directions and improved surface quality. [ABSTRACT FROM AUTHOR]

Intermetallic compounds (IMCs) have attracted significant attention in recent years due to their unique properties and potential applications in various fields, particularly in catalysis. This review aims to provide an in-depth understanding of IMCs, including their synthesis methods, structural characteristics, and diverse catalytic applications. The review begins with an introduction to IMCs, highlighting their distinct features and advantages over traditional catalyst materials. It then delves into the synthesis techniques employed to prepare IMCs and explores their structural properties. Subsequently, catalytic applications of the IMCs are introduced, focusing on the key reactions and highlighting their superior catalytic performance compared to conventional catalysts. Future perspectives for, and challenges to, the catalysis of IMCs are then proposed. [ABSTRACT FROM AUTHOR]

In this study, we investigated the brittle fracture behavior of Sn-3.0Ag-0.5Cu (SAC305) solder joints with a Direct Electroless Gold (DEG) surface finish, formed using laser-assisted bonding (LAB) and mass reflow (MR) techniques. Commercial SAC305 solder balls were used to ensure consistency. LAB increases void fractions and coarsens the primary β-Sn phase with higher laser power, resulting in a larger eutectic network area fraction. In contrast, MR produces solder joints with minimal voids and a thicker intermetallic compound (IMC) layer. LAB-formed joints exhibit higher high-speed shear strength and lower brittle fracture rates compared to MR. The key factor in the reduced brittle fracture in LAB joints is the thinner IMC layer at the joint interface. This study highlights the potential of LAB in enhancing the mechanical reliability of solder joints in advanced electronic packaging applications. [ABSTRACT FROM AUTHOR]

TiAl-based alloys represent a novel class of lightweight, high-temperature structural materials that exhibit exceptional properties, including low densities, high specific strength, and remarkable thermal resistance. These properties make them exceedingly promising for supplanting nickel-based superalloy in the production of pivotal components for aerospace, marine, and automotive engines. Regrettably, like most intermetallic compounds, TiAl-based alloys are subject to certain shortcomings, such as room-temperature brittleness, deformation difficulties, and susceptibility to cracking, which present challenges for shaping these materials into intricate forms using traditional processing methods. In this regard, additive manufacturing (AM), with its high processing freedom and energy, has emerged as a revolutionary technology for the fabrication of complex structural components of TiAl-based alloys. However, AM TiAl-based alloys are still plagued by issues such as cracking, porosity, and uneven microstructure. Therefore, various post-processing techniques were employed to tune the microstructure, and thus enhance the performance of AM TiAl-based alloys. This paper reviews the research progress of AM TiAl-based alloys, summarizing the effects of process parameters, alloying, heat treatment, and surface treatment on the microstructure and mechanical properties of these alloys. Additionally, it discusses the challenges and prospects for the future development of AM TiAl-based alloys. [ABSTRACT FROM AUTHOR]

The electronic packaging industry is gradually moving away from lead solder to lead-free solder, which is more environmentally friendly. However, there is still work to be done to ensure that lead-free solder meets the demands and requirements of the latest technology. The present study demonstrates the analysis of the microstructure formation of Cu6Sn5 and Cu3Sn intermetallic compound layers in Sn-10Cu/Cu solder joints. Therefore, the key objective of this research is to determine the growth rate and activation energy of the Cu6Sn5 and Cu3Sn intermetallic compound layer of the Sn-10Cu/Cu solder joint. The investigation on the bulk solder microstructure which consists of Cu6Sn5 and Cu3Sn intermetallic compound layer was carried out using Optical Microscope (OM), Scanning Electron Microscope (SEM) with EDX and ImageJ software. The IMC layer undergoes rapid growth with increasing aging temperature and duration and the two main IMC layers (Cu6Sn5 and Cu3Sn) grew thicker. The growth kinetic solder joints for Sn-10Cu and Sn-0.7Cu are 22.44 kJ/mol and 31.20 kJ/mol, respectively. Hence, the findings from this study may offer useful information for the development of high-reliability solder joints in future applications. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to investigate the thermal fracture mechanism of moisture-preconditioned SAC305 ball grid array (BGA) solder joints subjected to multiple reflow and thermal cycling. Design/methodology/approach: The BGA package samples are subjected to JEDEC Level 1 accelerated moisture treatment (85 °C/85%RH/168 h) with five times reflow at 270 °C. This is followed by multiple thermal cycling from 0 °C to 100 °C for 40 min per cycle, per IPC-7351B standards. For fracture investigation, the cross-sections of the samples are examined and analysed using the dye-and-pry technique and backscattered scanning electron microscopy. The packages' microstructures are characterized using an energy-dispersive X-ray spectroscopy approach. Also, the package assembly is investigated using the Darveaux numerical simulation method. Findings: The study found that critical strain density is exhibited at the component pad/solder interface of the solder joint located at the most distant point from the axes of symmetry of the package assembly. The fracture mechanism is a crack fracture formed at the solder's exterior edges and grows across the joint's transverse section. It was established that Au content in the formed intermetallic compound greatly impacts fracture growth in the solder joint interface, with a composition above 5 Wt.% Au regarded as an unsafe level for reliability. The elongation of the crack is aided by the brittle nature of the Au-Sn interface through which the crack propagates. It is inferred that refining the solder matrix elemental compound can strengthen and improve the reliability of solder joints. Practical implications: Inspection lead time and additional manufacturing expenses spent on investigating reliability issues in BGA solder joints can be reduced using the study's findings on understanding the solder joint fracture mechanism. Originality/value: Limited studies exist on the thermal fracture mechanism of moisture-preconditioned BGA solder joints exposed to both multiple reflow and thermal cycling. This study applied both numerical and experimental techniques to examine the reliability issue. [ABSTRACT FROM AUTHOR]

The alloys of the Ti-Zr-Mn system based on the C14-type Laves phase are considered as ones of the most promising materials for safe storage and transportation of hydrogen. These alloys have appropriate parameters for activating the processes of absorption and release of hydrogen, a low cost, and a fairly high cyclic stability. In this work, the microstructure and phase composition of the starting alloys and the crystal structure of the hydrides synthesized from them are studied. Possible ways to reduce the cost of the final products are shown. The fact that changing the method of the alloy fabrication does not significantly affect its hydrogen absorption properties is shown. On the example of the considered alloys, it is shown that, as expected, alloying with an element with a larger atomic radius that forms a stable chemical compound with hydrogen results in an increase in the hydrogen capacity. This is explained by both the increased radius of the tetrahedral interstitial sites, where hydrogen atoms are located after dissolution, and the higher total amount of the element interacting with hydrogen. [ABSTRACT FROM AUTHOR]

In the present investigation, an effort has been made to join commercial pure titanium and stainless steel 304L by plasma-assisted heating techniques. The diffusion bonding is conducted at 750 °C with varying heating rates viz. 100, 150, 200, 250 °C/min with holding for 5 minutes with varying pressure condition (44 MPa). The bonding strength of the interfacial region is evaluated by the tensile test. The result shows that the diffusion of Fe in Ti leads to the formation and stabilization of Fe2Ti in the interfacial zone. To understand the effect of varying holding time and heating rate, the bond width is studied using optical and scanning electron microscopes. It is observed that the thickness of the joint is reduced by increasing the heating rate. This leads to maximum bonding strength 418 MPa for the bond made at 150 °C/min withholding the pressure to room temperature whereas the bonding strength falls to 340 MPa at 200 °C/min due to the formation of a thick brittle intermetallic compound. [ABSTRACT FROM AUTHOR]

Anode‐free potassium (K) metal batteries are promising candidates in high‐energy‐density batteries. Nevertheless, the notorious potassium dendrite growth and poor K plating/stripping efficiency originating from the potassiophobicity of conventional Cu current collectors impede their practical applications. Herein, by means of systematically multi‐scale theoretical simulations, the correlations among K deposition morphology, nucleation sites, and potassiophilicity of mediation layers are well illuminated from thermodynamics and dynamics perspectives. As a proof of concept, a potassiophilic alloy Cu6Sn5 layer is constructed on commercial Cu foils via a facile electroless plating approach. The designed Cu6Sn5@Cu can guide the homogeneous distribution of K+ flux and regulate the electronic field, promoting uniform K+ plating and stripping. Meanwhile, a KF‐rich solid electrolyte interphase (SEI) layer with high mechanical strength is electrochemically induced and formed, facilitating the transport of K+ through SEI and enhancing the stability of SEI. Consequently, Cu6Sn5@Cu delivers great performance with durable stability of up to 600 h (1 mA cm−2 and 1 mAh cm−2) in no‐reservoir half‐cells. Benefiting from the unique mediation layer design, a novel anode‐free K‐metal full‐cell prototype demonstrates ameliorative cyclic stability. This work advances a fundamental understanding and establishes the bridge between the potassium deposition morphology and mediation layer properties for anode‐free potassium‐metal batteries. [ABSTRACT FROM AUTHOR]

Reductions in automobile weight and carbon dioxide emission are critical for the further development of the automobile industry. Aluminum is a lightweight material that can replace copper in automobile electronic equipment; therefore, laser welding of aluminum and copper is a subject of extensive research. This study investigates the influence of the laser strategy on the laser welding of aluminum and copper while preventing the formation of brittle Al–Cu intermetallic compounds. Aluminum and copper plates with a length of 20 mm and thickness of 0.3 and 1 mm, respectively, are used for the experiment. A continuous-wave laser with a power of 500 W and a spot beam radius of 150 μm is employed to irradiate the aluminum surface at different scan speeds. An electroless-plated nickel layer is used as a buffer between aluminum and copper, and the experimental results show that it can prevent copper surface damage and the formation of Al–Cu compounds during laser welding. In addition, the simulation and experimental results reveal that the residual thermal stress after laser welding can be reduced by heat treatment at different temperatures prior to laser irradiation. [Display omitted] • Al–Cu compound can be avoided during the laser welding process by the electroless nickel layer. • Residual thermal stress can be decreased by controlling the pre-heat treatment temperature for the metal before the laser weld. • Tension strength of welded joint will be decided by the laser scan speed in the welding process. • The contact area of the Al–Cu interface will affect the residual thermal stress after laser welding. [ABSTRACT FROM AUTHOR]

The phase diagram of the Fe-Zn binary system was evaluated based on the CALPHAD method with reference to the latest experimental data. The solubility ranges of the intermetallic compound phases, Γ-Fe4Zn9, Γ1-Fe11Zn40, δ1k-FeZn7, δ1p- Fe13Zn126, and ζ-FeZn13 were modeled considering their structures consisting of Zn12 icosahedra with Fe at the center (Fe1Zn12 clusters) as well as glue-like Fe and Zn atoms, and the miscibility gap between the δ1k and δ1p phases was also taken into account in the present calculations. The solubility of Fe in the liquid and (ηZn) phases that was confirmed as dozens of times larger than the values reported in the earlier literature could be calculated by introducing Fe1Zn12 associates to these solution phases. Consequently, all phase equilibria were adequately reproduced by the thermodynamic models and parameters revised in the present study. [ABSTRACT FROM AUTHOR]

Using our new program code, we have calculated the temperature dependence of the Seebeck coefficient ( S - T ) in the linearized Boltzmann transport equation with a constant relaxation time (LBT-CRT) for Fe2VAl (cF16) and its quaternary compounds for the range from − 263 °C (10 K) to 727 °C (1000 K). We revealed that Fe2VAl compound free from any defects exhibited the Seebeck coefficient with a negative sign at odds with experimental data with a positive sign. However, this dilemma could be removed after the introduction of Al/V near neighbor inversion defects into the perfect Fe2VAl. A key point in developing a reliable temperature-dependent Seebeck coefficient software lies in how precisely we calculate the density of states times square of the group velocity v x 2 along the direction x of thermal gradient. The present method is contrasted to the Fourier Transform Interpolation method in BoltzTraP developed by Madsen and Singh (2006). Nevertheless, both could reproduce the experimental data of Fe2VAl once the inversion effect was taken into account. Our new software allows us to seek the origin of characteristic behaviors in the S - T curve by decomposing the electronic parameter above into sub-bands and analyzing the sub-band dependence of the energy spectrum A ε in the LBT-CRT equation. [ABSTRACT FROM AUTHOR]

This work provides an efficient method to synthesize Ge nanorods through the reaction between intermetallic compound CaGe and ZnCl 2. By controlling the reaction temperature, Ge nanorods with different morphologies and crystallinity can be obtained. Particularly, the nanorods exhibit remarkable cycling stability and capacity retention even at −20 °C. These findings open up avenues for utilizing Ge nanomaterials in high-performance LIBs. [Display omitted] Germanium (Ge) nanomaterials have emerged as promising anode materials for lithium-ion batteries (LIBs) due to their higher capacity compared to commercial graphite. However, their practical application has been limited by the high cost associated with harsh preparation conditions and the poor electrode cycling stability in charging and diacharging. In this study, we successfully synthesized crystalline Ge nanorods through the reaction of intermetallic compound CaGe and ZnCl 2. Ge nanorods with different morphologies and crystallinity can be obtained through precisely controlling the reaction temperature. When employed as electrodes for LIBs, the Ge nanorods demonstrate exceptional long-term cyclic stability. Even after 1000 cycles at a high rate of 2C (1C = 1600 mA g−1), it exhibits a remarkable reversible capacity of around 1000 mAh/g. Furthermore, such Ge electrode displays excellent cycling performance across a wide temperature range. And it could achieve reversible capacities of 1267, 832, and 690 mAh/g, with the rate of 1C, at temperatures of 20, 0, and −20 °C, respectively. Above all, our study offers a cost-effective approach for the synthesis of crystalline Ge nanorods, addressing the concerns associated with high production costs. And the application of Ge nanorods as anode materials in LIBs over a wide temperature range opens up new possibilities for the development of advanced energy storage systems. [ABSTRACT FROM AUTHOR]

The findings of this study provide valuable insights into the electrochemical characteristics of high-chromium white cast irons (HCCIs) and their suitability as impellers in flue-gas desulfurizer (FGD) slurry pumps of coal-fired power plants. By evaluating the corrosion and wear resistance of HCCI specimens with varying Cr contents, it was confirmed that the corrosion mechanism of HCCI involves micro-galvanic corrosion between the matrix and iron–chromium and carbon intermetallic compounds. Furthermore, the study revealed that HCCI with 32 wt% Cr content exhibited superior corrosion resistance, owing to the full-ferrite matrix with complete Cr dissolution that facilitated the enrichment of Cr(OH)3 and Cr2O3 on the HCCI surface. The results demonstrate that the addition of 32 wt% Cr to HCCI enhances its passivation ability and improves its ability to resist both micro-galvanic corrosion and erosion–cavitation. Finally, the performance of the impeller fabricated with HCCI containing 32 wt% Cr was validated in a real environment for 16 months with a FGD slurry pump, and it was found to be in excellent condition, further highlighting the effectiveness of HCCI for use as impellers in FGD slurry pumps. [ABSTRACT FROM AUTHOR]

Effects of Si and Mg as main elements on interface reaction between tool steel and molten Al alloy at 700°C were investigated. Pure aluminum and Al-10mass%Mg alloy showed relatively simple interfacial layers, whereas thicker, multi-layered reaction bonds were found in the diffusion couple of A380 alloy. The diffusion of a large amount of Fe into Al matrix throughout the interfacial layer led to the formation of Al-Fe based intermetallic particles in the Al base metals. The diffusion couple of Al-10mass%Mg alloy showed a similar intermetallic layer as that of pure Al, indicating that 10mass%Mg in the Al melt rarely affected the formation of Al-Fe intermetallic layers. However, A380 alloy showed much expanded soldering area and increased thickness of intermetallic layers. Based on the phase diagram calculated, the solubility of Fe in liquid Al increased significantly with increasing Si content up to apploximately 5mass%, while, in the case of 10mass%Mg addition, the Fe solubility gradually decreased with increasing Mg content. Al-10mass%Mg alloy also showed the same tendency as that of pure Al in the formation and distribution of intermetallic compounds. However, in the Al-12mass%Si alloy, two types of Al-Fe-Si ternary compounds are present on the Al-rich side. [ABSTRACT FROM AUTHOR]

The mechanical properties of electronic devices in packaging technology are significantly affected by intermetallic compounds (IMCs). This study investigates the interfacial reaction between Ni under bump metallization and In solder at aging temperatures of 125°C, 135°C, and 145°C for different periods. Based on the energy dispersive x-ray spectrometry analysis, the growth of the IMCs is mainly Ni3In7. In addition, the square thickness of the IMCs is proportional to the aging time, which is consistent with volume diffusion control. The activation energy of the Ni3In7 IMC is calculated as 165.9 kJ/mol. [ABSTRACT FROM AUTHOR]

Zinc-included intermetallic compound catalysts of RhZn, PtZn, and PdZn with a molar ration of Zn/metal = 1/1, which are generally prepared using a hydrogen reduction approach, are known to show excellent catalytic performance in some selective hydrogenations of organic compounds. In this study, in order to reduce the incorporated mounts of the expensive noble metals, we attempted to prepare zinc-rich intermetallic compounds via a CaH2-assisted molten salt synthesis method with a stronger reduction capacity than the common hydrogen reduction method. X-ray diffraction results indicated the formation of RhZn13 and Pt3Zn10 in the samples prepared by the reduction of ZnO-supported metal precursors. In a hydrogenation reaction of p-nitrophenol to p-aminophenol, the ZnO-supported RhZn13 and Pt3Zn10 catalysts showed a higher selectivity than the RhZn/ZnO and PtZn/ZnO catalysts with the almost similar conversions. Thus, it was demonstrated that the zinc-rich intermetallic compounds of RhZn13 and Pt3Zn10 could be superior selective hydrogenation catalysts compared to the conventional intermetallic compound catalysts of RhZn and PtZn. [ABSTRACT FROM AUTHOR]

It is difficult to confirm the existence of intermetallic compounds (IMCs) between SnIn and Cu, as their atomic numbers are very close, making it challenging to differentiate them through experimental tests. In order to determine IMCs and understand their growth mechanism, this study employed phase identification, morphology observation, and growth kinetics analyses on IMCs formed between In-48Sn solder and polycrystalline Cu substrate during liquid soldering. The experiments were conducted within a temperature range of 160~250 °C for up to 90 min. The obtained results indicated that IMCs formed at the interface depended strongly on the soldering temperature. During long-time soldering below 200 °C, one main IMC species, Cu2(In,Sn), was found at the In-48Sn solder/Cu interface, which showed two different morphologies: a coarse-grained layer at the solder side and a fine-grained layer within the Cu component. When the soldering temperature was increased to 200 °C, Cu6(In,Sn)5 was the only intermetallic compound (IMC) that formed at the point where the In-48Sn/Cu eutectic interface existed. At 250 °C, with an increase in the soldering time, there was a formation of Cu9(In,Sn)4 between Cu and Cu6(In,Sn)5. The growth kinetics analyses indicated that the fast grain boundary/molten-channel diffusion of Cu into solder and their reaction with solder controlled the growth of the interfacial IMCs, with the activation energy of 24.56 kJ/mol when the sample was liquid-state-aged above 200 °C. [ABSTRACT FROM AUTHOR]

The paper studies the double-layer coating consisting of the Y–Al–C sublayer and external Y–Al–O ceramic layer obtained by vacuum-arc deposition for the protection of the VTI-4 (Ti49–11Al–40Nb) intermetallic alloy from oxidation at 750°C. The coating degradation mechanism and its chemical composition are studied after thermal cyclic tests. Test results show the stability of the double-layer coating during both their heating in a furnace and thermal cyclic tests. [ABSTRACT FROM AUTHOR]

The paper studies intermetallic coatings based on the Ti–Al system obtained by plasma-assisted vacuum-arc deposition. The coatings are deposited by three different techniques to gain the different elemental and phase compositions. The study of the oxidation kinetics shows that the coating with the gradient aluminum distribution possesses the best oxidation resistance. It is found that after 500 hours of oxidation, its structure and weight remain unchanged. [ABSTRACT FROM AUTHOR]

The intermetallic compound and hot tearing sensitivity of Al–4.4Cu–xMg–0.15Zr (x = 1.0–2.5 wt%) alloys with different Cu/Mg ratios are studied by using the multi-channel "cross" hot tearing test device. Based on microstructure evolution, thermal analysis, and shrinkage force curves analyzed by SEM, TEM, EPMA, and JMatPro, the hot tearing mechanism of the alloys is explored. The results show that the type of intermetallic compound and viscosity change with the decrease of Cu/Mg ratio, and the hot tearing tendency can be controlled by regulating the type and quantity of intermetallic compound. The greater the number of Al2CuMg phases between grains of the alloys, the smaller the viscosity, the stronger the feeding ability of liquid phase in the late solidification period, and so the lower the hot tearing tendency of the alloys. Significantly, when the Cu/Mg ratio is 2.6, the amount of Al2CuMg phase is the largest, and the viscosity of the alloy is low, thus improving the tear feeding efficiency in the late solidification stage. Moreover, the cracking susceptibility coefficient value of the alloy is the minimum value, and the hot tearing tendency is the lowest. [ABSTRACT FROM AUTHOR]

The electronic structure of a gold film deposited on W was studied during the adsorption of sodium atoms. An analysis of the photoemission spectra from the valence band and core levels of Au 4f and Na 2p upon synchrotron excitation in the photon energy range of 80–600 eV showed that Na adsorption leads to the formation of NaxAuy intermetallic compounds of various stoichiometry under the Na monolayer. [ABSTRACT FROM AUTHOR]

The hydrogenation of a mechanical 200-μm mixture of commercial magnesium in the presence of 10–40 wt % Ti2Ni intermetallic compound as a catalytic additive under a high-purity hydrogen pressure of 30 atm and at temperatures of 350–390°C without the use of preliminary high-energy treatment of the reactant mixture has been studied in order to optimize conditions for the hydrogenation of magnesium. It has been found that in a mixture of Mg + 20 wt % Ti2Ni, magnesium is hydrogenated by 95–96% at 370–380°C with a total hydrogen content of 6.2 wt % in the resulting mixture of hydrides. This mixture, as a working substance in reusable high-temperature metal hydride hydrogen batteries at 250–450°C, released high-purity hydrogen (99.999 wt %) for practical use in small-scale and laboratory works. [ABSTRACT FROM AUTHOR]

In this study, it was verified that the synthesis of Ti‐Al‐C MAX phases has advantages when using intermetallic compounds rather than using only elemental powders. The formation behavior of the MAX phases was presented through diffusion experiments. In the case of using elemental powder, Ti2AlC is produced at 1300°C, and Ti3AlC2 is produced at 1400°C. When intermetallic compounds are used, Ti2AlC is produced at 1000°C, and Ti3AlC2 is produced at 1300°C. In the case of the elemental powder, it is verified that Ti3AlC2 content is decreased and Ti2AlC is increased when heat treatment is performed at 1400°C for 3 h. Rather Ti3AlC2 content is increased when intermetallic compounds are used. When an intermetallic compound is used, synthesis occurs more actively at high temperatures, and the tendency to be thermally decomposed can be prevented. When TiAl and TiC are heat treated, Al of the intermetallic compound is diffused into TiC, and C of TiC is diffused into the intermetallic compound. Furthermore, there are many two‐dimensional defects in TiAl, which act as a C diffusion channel. C diffuses into TiAl to produce TiCX, and the MAX phases is generated by the short‐range diffusion of Al. At the region of TiC, TiC transforms into TiCX after C diffuses into TiAl, which consequently structure of TiC changes from cubic to hexagonal. This is the same crystal structure as the MAX phases, and it is confirmed that the (110) surface is maintained. A Ti‐C layer structure of the (110) surface is maintained, and it was determined that Al is diffused during this time to generate the MAX phases. [ABSTRACT FROM AUTHOR]

Al/Cu dissimilar welding is a key technology for weight reduction in fabricating high-functional products, however, conventional tungsten inert gas (TIG) welding is difficult to be applied due to a large fusion area. The constricted nozzle equipped inside the conventional TIG torch has been developed and can improve the position accuracy of tungsten electrode and arc plasma characteristics, moreover increase the heat input density. In this study, 0.5 mm-thick Al and Cu dissimilar sheets were butt welded using pulsed TIG welding with the constricted nozzle under two welding speed-current combinations of 50 mm/s-85 A and 100 mm/s-105 A. The 50 mm/s-85 A joint exhibited that Al and Cu mixed each other in the entire weld metal, containing two intermetallic compounds (IMC) of Al2Cu and Al4Cu9 mainly in the Al side. In contrast, both elements hardly mixed each other in the 100 mm/s-105 A weld metal and the interface exhibited hook-like shape at a nearly constant pitch, depending on the welding speed and pulse frequency. Consequently, the formation of IMC layers was limited. Based on the three-dimensional images reconstructed using a serial sectioning technique, the hook-shaped Al/Cu interface was also formed inside the weld metal. The mixed-zone volume per unit weld length of the 100 mm/s-105 A joint was estimated to be about 0.12 mm3/mm, and is much smaller than that of the 50 mm/s-85 A joint (0.97 mm3/mm). The average tensile strength of the 100 mm/s-105 A joint were higher than those of the 50 mm/s-85 A joint, suggesting that the hook-shaped Al/Cu interface together with the reduced mixed zone seems to increase the joint strength. [ABSTRACT FROM AUTHOR]

Despite the large number of studies on the development of multilayered composites using accumulative roll bonding method (ARB), there are not enough available details concerning the effect of the temperature variation on the constituent layer microstructure and the nature and kinetics of the developed intermetallic compounds. The present work aims to process an Al/IF steel multilayered composite using ARB and to understand the effect of non-isothermal heating on its structural evolution. The elaborated material is characterized by using thermal Differential Dilatometry (DD), Scanning Electronic Microscopy (SEM) and x-ray Diffraction (XRD). The progress of the ARB leads to the dispersion of the Fe layers between the Al layers and does not lead to the formation of diffusion layer. The continuous heating leads, for temperature lower than 330 °C, to the occurrence of the recovery reaction in the Al layers, which produces a big contraction and causes a partial softening of the material. The formation of the intermetallic compound Al5Fe2 seems to occur at higher temperatures and leads to a significant expansion of the material. This effect is explained by the increase in the atomic specific volume. [ABSTRACT FROM AUTHOR]

Thermal ionization of methenamine (C6H12N4) on the surface of the NaAux intermetallic compound has been studied. It has been established that the processes of decomposition, desorption and ionization of adsorbed compounds, thermally stimulated on the surface, proceed due to the accumulation of energy at the degrees of freedom of the adsorption complex, including the adsorbed compound and a solid, by the mechanism of monomolecular decomposition reactions. In this case, the decomposition of the adsorption complex is accompanied by the desorption of ions that are not in thermal equilibrium with the solid. The uniformity of the temperature dependences of the ion current and their distribution over two groups allowed us to conclude that ions are desorbed from the surface, which correspond to the decays of individual adsorbed molecules, as well as the decays of dimers formed on the surface. The decay of methenamine molecules during thermal ionization occurs in the same way as their decay in vacuum during electron ionization, which indicates the preservation of the bulk structure of methenamine molecules during adsorption and a significant lifetime of the excited state of compounds on NaAux. [ABSTRACT FROM AUTHOR]

This study investigates the impact of an additional pass on microstructure evolution, mechanical properties, and intermetallic compound formation during friction stir welding of aluminum and titanium. The microstructure analysis showed a complex mechanical mixing in the weld nugget that contained particles of varying sizes and the formation of intermetallic compounds. The formation of intermetallic compounds, such as Al3Ti and AlTi, was detected through chemical analyses and X-ray diffraction techniques. The microstructure of aluminum in the weld nugget comprised equi-axed grains with different grain boundaries and low orientation deviation. Such features in the evolution of the microstructure are attributed to continuous dynamic recrystallization due to its high stacking fault energy and favorable welding temperature and strain-induced dislocation activities. The presence of particles in aluminum and their homogeneous distribution after the second pass promote the state-IV hardening rate. A model for inhomogeneous materials was introduced to explain the variation in tensile properties with the number of passes, and the model correlated well with the cross-sectional microstructure analysis, which showed five distinct zones across the weld nugget. The study concludes that the improvement in mechanical properties after the second pass can be attributed to the development of interlayers, a defect-free interface, mechanical mixing, and continuous dynamic recrystallization of aluminum in the weld nugget. [ABSTRACT FROM AUTHOR]

Heusler alloys (X2YZ) can be a candidate for new catalysts as well as other intermetallic compounds. We previously found good catalytic properties of Co2FeGe for selective hydrogenation of alkynes and developed nanoparticles of Co2FeGe supported on SiO2. However, the average diameter of the nanoparticles was 23 nm, which is not small enough compared to those of state‐of‐the‐art nanoparticle catalysts. In this study, we developed SiO2‐supported Co2FeGe nanoparticles of <10 nm in diameter. A catalytic test for selective hydrogenation of propyne indicated a partial formation of sites with low selectivity including excess Co atoms. For ammonia decomposition, enhancement of turnover frequency was achieved by reducing the particle size. [ABSTRACT FROM AUTHOR]

In the present study, an attempt is made to perform a comparative assessment between the conventional friction stir welding (C-FSW) and two auxiliary energy-assisted FSW (AE-FSW) techniques, namely plasma arc-assisted FSW (P-FSW) & induction-assisted FSW (I-FSW) of high strength DH36 steel to 6061-T6 aluminum alloy. The study is carried out with an intention to realize the advancement of AE-FSW techniques by preheating the harder material, i.e., DH36 steel. For the reliable evaluation & comparison, two different preheating conditions based on the peak temperature were chosen for both AE-FSW techniques: low peak temperature at around 400 °C, and high peak temperature at about 600 °C. It is observed that the induction preheating improved the joint efficiency, grain refinement, and hardness magnitudes due to its superior heat generation capabilities than the corresponding plasma preheating. A significant decrease in tool degradation is observed in I-FSW at high peak temperature compared to C-FSW and P-FSW, along with reductions of 27.8% in axial force and 21.7% in tool torque. The lamellar intercalated features exhibited the highest hardness due to the substantial formation of different intermetallic compounds (IMCs), namely Fe 3 Al + FeAl 3 in P-FSW and I-FSW at low peak temperature, and FeAl + Fe 3 Al + FeAl 3 at high peak temperature. By maintaining the superior corrosion resistance, I-FSW at high peak temperature produced the highest joint efficiency of 77.2% with the binary-phased (i.e., Fe 2 Al 5 + FeAl 3) IMC layer thickness of 4.21 ± 0.4 µm and the 4.13% area fraction of FeAl 3 in the stir zone. [ABSTRACT FROM AUTHOR]

Thermal ionization of methenamine (C6H12N4) on the surface of the NaAux intermetallic compound has been studied. It has been established that the processes of decomposition, desorption and ionization of adsorbed compounds, thermally stimulated on the surface, proceed due to the accumulation of energy at the degrees of freedom of the adsorption complex, including the adsorbed compound and a solid, by the mechanism of monomolecular decomposition reactions. In this case, the decomposition of the adsorption complex is accompanied by the desorption of ions that are not in thermal equilibrium with the solid. The uniformity of the temperature dependences of the ion current and their distribution over two groups allowed us to conclude that ions are desorbed from the surface, which correspond to the decays of individual adsorbed molecules, as well as the decays of dimers formed on the surface. The decay of methenamine molecules during thermal ionization occurs in the same way as their decay in vacuum during electron ionization, which indicates the preservation of the bulk structure of methenamine molecules during adsorption and a significant lifetime of the excited state of compounds on NaAux. [ABSTRACT FROM AUTHOR]

This research introduces low-temperature soldering of Ga with practical metallization structures, namely, Cu/Ni/Pd and Cu/Ni/Au, applied to contemporary microelectronic packages. Through these multilayer configurations, the study investigates the stability of the Ni diffusion barrier by examining changes in the interfacial microstructure as Ni is consumed. The interfacial reactions are conducted across a temperature spectrum of 160, 200, 240, and 280 °C, with reaction durations ranging from 30 to 270 min. Valuable insights for low-temperature soldering with Ga are extracted from the data. At lower reaction temperatures, the presence of Ga-rich intermetallic compounds (IMCs), specifically GaxNi (x = 89 to 95 at%), on the Ga7Ni3 layer is notably confirmed. As the reaction temperature and duration increase, the gradual consumption of the Ni layer occurs. This gives rise to the formation of Ga-Cu IMCs, specifically CuGa2 and γ3-Cu9Ga4, beneath the Ga-Ni IMC layer. Concurrently, the gap between the Ga-Ni and Ga-Cu IMC layers widens, allowing molten Ga to infiltrate. The rate of Ga7Ni3 growth follows a time exponent ranging approximately from 1.1 to 1.7. This highlights the significant influence of interface reaction-controlled kinetics on Ga7Ni3 IMC growth. The activation energy for Ga7Ni3 growth is determined to be 61.5 kJ/mol. The growth of Ga7Ni3 is believed to be primarily driven by the diffusion of Ga atoms along grain boundaries, with the porous microstructure inherent in the Ga7Ni3 layer providing additional diffusion pathways. [ABSTRACT FROM AUTHOR]

Developing efficient catalysts for formic acid decomposition has been studied extensively. Herein, the Au 3 Pd 1 intermetallic compound is designed as a single atom catalyst for the dehydrogenation of formic acid. By using density functional theory calculations, the thermodynamic stability, electronic structure, and reaction mechanism for the Au 3 Pd 1 catalyst are systematically investigated, and the surface charge polarization and atom-ordered arrangement were confirmed to play an important role in the efficient formic acid dehydrogenation. The special positively charged Pd single atom on the Au 3 Pd 1 surface becomes the adsorption site of HCOO− and the reaction site for formic acid decomposition. The nearby Au sites suppress the C–O bond cleavage due to their weak interaction with CO∗ and OH∗. As a result, the HCOO− dehydrogenation pathway is predominant on the Pd single atomic sites and the CO formation is well inhibited. This intermetallic-based catalyst can be extended to other systems and provided general guidance for efficient catalyst design. [Display omitted] • Stability and reaction mechanism using Au 3 Pd 1 intermetallic as a model catalyst. • Breaking scaling relations by constructing surface charge polarized Pd single atom. • Extendable and guiding principle for intermetallic-based catalyst design. [ABSTRACT FROM AUTHOR]

A new ternary intermetallic compound Al3GaCu9 was synthesized experimentally. A high-quality powder diffraction pattern of the compound was collected by an X-ray diffractometer, and its crystal structure was determined using the Rietveld refinement method. Results show that the compound has a cubic cell with the Al4Cu9 structure type (space group $P\bar{4}3m$ and Pearson symbol cP 52). The lattice parameter a = 8.7132(3) Å, unit-cell volume V = 661.52 Å3, calculated density D calc = 7.26 g/cm3, and Z = 4. The residual factors converge to R p = 2.96%, R wp = 4.06%, and R exp = 2.57%. The experimentally obtained reference intensity ratio value is 7.04. [ABSTRACT FROM AUTHOR]

Wire-bonding technology is the most commonly used chip interconnection technology in microelectronic packaging. Metal bonding wire is the key material for wire bonding and plays an important role in the reliability of electronic devices. In recent years, palladium-plated copper (PdCu) bonding wire has been widely used because of its low cost, good electrical and thermal conductivity, the fact that it is not easy to oxidize, and its high reliability. Therefore, it is necessary to review its research progress. In this paper, the preparation and application of palladium-plated copper bonding wire are reviewed. Firstly, the preparation methods of electroplating, electroless plating, and direct plating are introduced. Secondly, the factors affecting the distribution of Pd in free air balls and bonding interfaces, the effect of Pd on the formation and growth of intermetallic compounds in PdCu wire, stitch bond, and reliability of PdCu wire are summarized and analyzed in the application process. Finally, its development prospect is prospected. Hopefully, this review can help readers to have a comprehensive understanding of the preparation and application of palladium-plated copper bonding wires, and can accelerate the promotion of its application in more fields in the future. [ABSTRACT FROM AUTHOR]

T2 copper was joined to 1060 pure aluminum by a novel welding method, that is, an ultrasonic-assisted plasma arc Welding–Brazing process. The impacts of ultrasonication on the interfacial microstructure and weld formation were studied. Optical microscopy and scanning electron microscopy were used to observe weld formation and the resulting microstructure. The elemental distributions and phase formation of the alloy were identified by energy dispersive spectrometry and x-ray diffraction. A tensile test machine was used to determine the shear strength of the weld lap joint. The results showed that ultrasonic vibration significantly improved the wetting and spreading ability of Al on the Cu substrate and changed the morphology of the intermetallic compound (IMC) layer. Ultrasound assistance can also significantly break the continuous IMC layer, and some bulk-shaped IMC phases were found in the weld. In studies of the mechanical performance of the weld joint, the shear strength did not increase linearly with ultrasonic power. When the ultrasonic power was 1400 W, the maximum shear strength of the welded joint reached 86.31 MPa, and the shear strength was 67.2% higher than that of the ultrasonic joint made without increasing the power. [ABSTRACT FROM AUTHOR]

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The objective of present research work is to improve the joint strength of dissimilar FSW of Al and Mg alloy. The method used for joining Al and Mg alloys is the application of Zn interlayer in different orientations in FSW process. The horizontal orientation of Zn interlayer has been used first time and compared for material mixing and strength with that of without interlayer and vertical Zn interlayer. The result shows that the maximum tensile strength of 126 MPa has been achieved for horizontal Zn interlayer as compared to the 85 MPa in the case of vertical Zn interlayer. It has been observed that cracking occurs when no interlayer was used due to formation of hard and brittle intermetallic compound (IMC) Al12Mg17. The two different types of eutectic structures and one eutectoid structure have been observed in FSW while using vertical Zn interlayer, whereas only one eutectic structure has been observed in case of horizontal Zn interlayer. New major phases identified in these FSW welds are Al5Mg11Zn4, Mg32(Al,Zn)49, MgZn, and MgZn2 in place of Al3Mg2 and Al12Mg17 phases. It has been concluded that orientation of Zn interlayer in the horizontal position has improved material flow and better mixing, which provided less hard intermetallic compounds and resulted in improved tensile strength. [ABSTRACT FROM AUTHOR]

The ternary Tb2–xNdxZn17–yNiy (x = 0.5, y = 4.83) disordered phase belongs to the structural family based on the rhombohedral Th2Zn17 structure type. The structure is maximally disordered since all the sites are occupied by statistical mixtures of atoms. The Tb/Nd mixture of atoms occupies the 6c site (site symmetry 3m). The statistical mixtures Ni/Zn consisting of more Ni atoms are located in the 6c and 9d (symmetry.2/m) sites. In the following 18f (site symmetry.2) and 18h (site symmetry.m) sites are located Zn/Ni statistical mixtures which consist of more Zn atoms. Zn/Ni atoms form three‐dimensional networks with hexagonal channels that fill statistical mixtures of Tb/Nd and Ni/Zn. The Tb2–xNdxZn17–yNiy compound belongs to the family of intermetallic phases capable of absorbing hydrogen. In the structure, there are three types of voids, namely, 9e (site symmetry.2/m), 3b (site symmetry m) and 36i (site symmetry 1), in which hydrogen can be inserted, and the maximum total absorption capacity can reach 1.21 wt% H2. Electrochemical hydrogenation shows that the phase absorbs 1.03% of H2, which indicates partial filling of the voids with H atoms. [ABSTRACT FROM AUTHOR]

In this paper, in order to achieve the development of a novel biodegradable dual-phase alloy in a Ca–Mg–Zn system, the establishment of the control strategy of degradation behavior of alloys composed of two phases was attempted by the control of alloy composition, constituent phases, and microstructure. By combining two phases with different dissolution behavior, biodegradable alloys are expected to exhibit multiple functions. For example, combining a suitable slow dissolving phase with a faster dissolving second phase may allow for dynamical concavities formation during immersion on the surface of the alloy, assisting the invasion and establishment of bone cells. Without the careful control of the microstructure, however, there is a risk that such dual-phase alloy rapidly collapses before the healing of the affected area. In this study, ten two-phase alloys consisting of various different phases were prepared and their degradation behaviors were examined. Consequently, it was found that by combining the IM3 and IM1 intermetallic phases with the compositions of Ca2Mg5Zn13 and Ca3Mg4.6Zn10.4, the expected degradation behavior can be obtained. [ABSTRACT FROM AUTHOR]

The melting behavior and microstructure of bulk Sn-xIn (x = 6, 12 and 24, wt.%) solders and the thermomigration, elemental distribution and intermetallic compound (IMC) growth in Cu/Sn-xIn/Cu micro solder joints during soldering and aging under temperature gradient (TG) were investigated. The results indicate that In addition effectively decreased the melting temperature of the bulk solders. Only the InSn4 phase was detected when In addition was increased to 24 wt.%. During soldering under TG, the growth rate of the interfacial IMC layer at the cold end interfaces gradually decreased as the In content increased. The mechanism of microstructure evolution and elemental distribution in the micro solder joints was revealed based on the TG-induced atomic thermomigration (TM). The chemical potential gradient of atoms was enhanced by TM, and the rapid diffusion of atoms in the liquids resulted in a uniform distribution of In element in both solders and the IMC phase during soldering. While during aging under TG, there was a smaller chemical potential gradient due to the slow atomic diffusion rate. At this time, TG dominated the atomic migration, which resulted in a nonuniform distribution of the In element in the whole joints. This study provides further insight into the application of In-containing solders in electronic packaging. [ABSTRACT FROM AUTHOR]

Diffusion in Ni-V solid-solution of A1 structure and Ni3V of D022 structure has been studied by interdiffusion experiments using single-phase (A1/A1 and D022/D022) and two-phase (A1/D022) diffusion couples. Concentration profiles in diffusion-annealed couples were measured by electron-probe microanalysis, and the chemical diffusion coefficient has been evaluated by Boltzmann-Matano analysis. The diffusion coefficient in the A1 phase agrees well with the data in the literature over the ranges of temperature from 900 to 1300 °C and composition from 0 to 25 mol.% V. The diffusion coefficient at 25 mol.% V in the ordered D022 phase, which exists below 1045 °C, is found to be smaller than the extrapolation from the A1 phase toward this temperature range. The much faster diffusion in the D022 phase reported by Khlomov et al. (Phys Met Metall 46(1): 173-175, 1978; Phys Met Metall 46(3):188-191, 1978) could have been caused by transient microstructural evolution - formation of new phases and grains - in their reaction diffusion experiments. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to study the impact of intermetallic compound on microstructure, mechanical characteristics and thermal behavior of the melt-spun Bi-Ag high-temperature lead-free solder. Design/methodology/approach: In this paper, a new group of lead-free high-temperature Pb-free solder bearing alloys with five weight percentages of different silver additions, Bi-Agx (x = 3.0, 3.5, 4.0, 4.5 and 5.0 Wt.%) have been developed by rapidly solidification processing (RSP) using melt-spun technique as a promising candidate for the replacement of conventional Sn-37Pb common solder. The effect of the addition of a small amount of Ag on the structure, microstructure, thermal and properties of Bi-Ag solder was analyzed by means of X-ray diffractometer, scanning electron microscopy, differential scanning calorimetry and Vickers hardness technique. Applying the RSP commonly results in departures from conventional microstructures, giving an improvement of grain refinement. Furthermore, the grain size of rhombohedral hexagonal phase Bi solid solution and cubic IMC Bi0.97Ag0.03 phase is refined by Ag addition. Microstructure analysis of the as soldered revealed that relatively uniform distribution, equiaxed refined grains of secondary IMC Bi0.97Ag0.03 particles about 10 µm for Bi-Ag4.5 dispersed in a Bi matrix. The addition of trace Ag led to a decrease in the solidus and liquidus temperatures of solder, meanwhile, the mushy zone is about 11.4°C and the melting of Sn-Ag4.5 solder was found to be 261.42°C which is lower compared with the Sn-Ag3 solder 263.60°C. This means that the silver additions into Bi enhance the melting point. The results indicate that an obvious change in electrical resistivity (?) at room temperature was noticed by the Ag addition. It was also observed that the Vickers microhardness (Hv) was increased with Ag increasing from 118 to 152 MPa. This study recommended the use of the Bi-Ag lead-free solder alloys for higher temperature applications. Findings: Silver content is very important for the soldering process and solder joint reliability. Based on the present investigations described in this study, several conclusions were found regarding an evaluation of microstructural and mechanical deformation behavior of various Bi-Ag solders. The effect of Ag and rapid solidification on the melting characteristics, and microstructure of Bi-Ag alloys were studied. In addition, the mechanical properties of Bi with different low silver were investigated. From the present experimental study, the following conclusions can be drawn. The addition of Ag had a marked effect on the melting temperature of the lead-free solder alloys, it decreases the melting temperature of the alloy from 263.6 to 261.42°C. Bi-Ag solders are comprised of rhombohedral Hex. Bi solid solution and cubic Ag0.97Bi0.03 IMC is formed in the Bi matrix. The alloying of Ag could refine the primary Bi phase and the Bi0.97Ag0.03 IMC. With increasing Ag content, the microstructure of the Bi-Ag gradually changes from large dimples into tiny dimple-like structures. The refinement of IMC grains was restrained after silver particles were added into the matrix. The inhibition effect on the growth of IMC grains was most conspicuous when solder was doped with Ag particles. As a result, the Vickers microhardness of the Bi-Ag lead-free solder alloys was enhanced by more than 100% ranging from 118.34 to 252.95 MPa. Bi-Ag high-temperature lead-free solders are a potential candidate for replacing the tin-lead solder (Sn-37Pb) materials which are toxic to human and the environment and has already been banned. Originality/value: This study recommended the use of the Bi-Ag lead-free solder alloys for high-temperature applications. [ABSTRACT FROM AUTHOR]

Regularities of cold uniaxial deformation of powder materials consisting of Ti–B and Ti–Al–Nb–Mo–B layers are established based on a rheological approach. The composition TiB–Ti (30 wt.%) (TiB) was chosen for the Ti–B layer; 51.85Ti–43Al–4Nb–1Mo–0.15B (at%) (TNM), for the intermetallic layer. Five types of charge blanks with diameters 12 and 25 mm were investigated [contents (vol.%) 100 TiB, 100 TNM, 70 TiB/30 TNM, 50 TiB/50 TNM, and 30 TiB/70 TNM]. Experimental stress(strain rheological dependences were plotted for each type of powder blank. Three areas of compaction were distinguished on the obtained dependences. The effect of the blank diameter on the degree of deformation and the stresses arising in the powder blanks was shown. An irregular compaction mode was found at stresses above 100 MPa for a blank containing only intermetallic compounds. [ABSTRACT FROM AUTHOR]

A rotating magnetic field was applied during the solidification of AlSiFe alloys (Si = 5 mass% or 10 mass% and Fe = 0.5 mass% or 1 mass%) and the effect of electromagnetic stirring on the area and shape of the intermetallic compounds was studied. The phases formed during solidification of the alloys were not influenced by electromagnetic stirring. The alloys consisted of α-Al, Si and intermetallic β-Al9Fe2Si2. At coil current frequencies above 10 Hz, electromagnetic stirring induced fragmentation of dendritic α-Al, giving rise to coarsening of the β-Al9Fe2Si2 present between the fragmented α-Al grains. The application of electromagnetic stirring at coil current frequencies above 80 Hz decreased the aspect ratio of β-Al9Fe2Si2 in Al10 mass%Si1 mass%Fe, while no such decrease was identified in Al5 mass%Si0.5 mass%Fe, Al5 mass%Si1 mass%Fe or Al10 mass%Si0.5 mass%Fe. It was found that the shape of the β-Al9Fe2Si2 phase formed under forced flow of the melt depended significantly on the stirring intensity and the solid fraction of the melt at which intermetallic compounds were formed. [ABSTRACT FROM AUTHOR]

In order to enhance the high-temperature mechanical performance to meet service requirements, the microstructures and tensile properties of heat-treated Al-8.4Cu-2.3Ce-1.0Mn-0.2Zr-xNi (x = 0, 0.5, 1.0, 2.0, 4.0 wt.%) were investigated. The metallographic analysis techniques have been used to examine the microstructural changes with different Ni contents. Results show that after adding 0.5% Ni to the Al-8.4Cu-2.3Ce-1.0Mn-0.2Zr alloy, the spheroidized Al7Cu4Ni phase is formed. With Ni content further increasing, the Al8CeCu4 and Al24MnCu8Ce3 phases disappear, and the nano-sized Al20Cu2Mn3 and Al2Cu phases decrease gradually. When Ni content reaches 4.0%, the Al3CuNi phase appears. It turns out that the addition of 0.5% Ni has significantly improved the tensile properties at 400 °C. The ultimate tensile strength, yield strength, and elongation of Al-8.4Cu-2.3Ce-1.0Mn-0.2Zr-0.5Ni alloy at 400 °C reach 103 MPa, 93 Mpa, and 18.0%, respectively, which makes the alloy possible to be employed at 400 °C. The intermetallic micro-skeleton, composed of thermostable Al8CeCu4, Al24MnCu8Ce3, Al16Cu4Mn2Ce, and Al7Cu4Ni phases at the grain boundaries as well as nano-sized Al20Cu2Mn3 and Al2Cu precipitates in the grains, contributes to the good elevated-temperature tensile strength. The fracture mechanism is changed from quasi-cleavage at ambient temperature to coexistence of quasi-cleavage and dimple at 400 °C. [ABSTRACT FROM AUTHOR]

Copyright of Electroplating & Finishing is the property of Electroplating & Finishing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Heat sink assemblies consisting of an A6061-T6 aluminum alloy fin and a C1100 copper base are prepared by T-joint welding using a near continuous-wave fiber laser system. The effects of the welding parameters on the tensile strength and heating rate of the heat sink assembly are investigated and compared. It is shown that the maximum tensile strength and heating rate are obtained using a laser power of 220 W, a pulse width of 8 ms, a welding speed of 2 mm/s, and an incident angle of 60°. The thermal conductivity of the heat sink prepared using the optimal welding parameters is shown to be in good agreement with the ANSYS Fluent simulation results obtained under the assumption of an ideal, defect-free joint between the copper base and aluminum fin. The tensile strength and heating rate using the optimal welding parameters are 24.31 MPa and 41.2 °C/102 S, respectively. The optical microscopy (OM) images show that the thickness of the intermetallic compound (IMC) layer formed at the interface between the aluminum fin and the copper base varies with the welding parameters and has a value of approximately 6 µm under the optimal welding conditions. The energy dispersive spectrometry (EDS) results and X-ray diffraction (XRD) analysis results reveal that the welding bead consists mainly of Cu, Al, and Al2Cu phases. [ABSTRACT FROM AUTHOR]