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Topological materials are receiving significant attention for their distinctive properties and practical applications. Topological states featuring multi-fold band degeneracy are not restricted to electronic systems but also extend to phonon systems. In this investigation, we delved into the higher-order symmetry-constrained topological attributes of Nb 3 Bi, an intermetallic compound with a A15 crystal structure. Through the first-principles computations and symmetry evaluation, we tried to describe the topological phonon modes safeguarded by nonsymmorphic symmetries. Our scrutiny revealed that Nb 3 Bi possesses notable degeneracy in the phonon dispersion relation, particularly highlighted by a sixfold degenerate point situated at the R point of the Brillouin zone. In addition, we also identified cubic contact Dirac points and quadratic contact triple points at the R and Γ points, respectively. The computed phonon surface states considering two distinct terminations on the (001) and (1 1 ¯ 0) planes reveal a distinct twofold rotational symmetry arrangement. The present results offer valuable insights into the distinctive phonon attributes and surface characteristics of Nb 3 Bi, emphasizing its importance in the field of phonon topology. [ABSTRACT FROM AUTHOR]

In gas gun experiments, a graded density impactor (GDI) is used to achieve quasi-isentropic loading. However, inconsistency between the designed and experimental loading profiles, mainly caused by by-products during preparation, limits the application of GDI for a long time. In this work, a kind of W/Ti GDI with advantages of a wide density range of 4.5–19.3 g/cm3 and high structural designability was designed and synthesized. Each of mid-layers of the W/Ti GDI was composed of W and Ti without the formation of an intermetallic compound, and had good parallelism and flatness. This provides a prerequisite for good agreement between the designed and experimental loading profiles. Due to the high designability of the GDI, quasi-isentropic loading with different stress-paths was achieved by controlling the structure of the GDI. Then, independently controlling peak stress and strain rates of loading was successfully achieved by changing the flyer velocity and the type of the W/Ti GDI. The W/Ti GDI has enormous application potential in studying the dynamic response of materials under quasi-isentropic loading with stress and strain rate controlled. [ABSTRACT FROM AUTHOR]

The recent development of accurate and efficient semilocal density functionals on the third rung of Jacob's ladder of density functional theory, such as the revised regularized strongly constrained and appropriately normed (r2SCAN) density functional, could enable rapid and highly reliable prediction of the elasticity and temperature dependence of thermophysical parameters of refractory elements and their intermetallic compounds using the quasi-harmonic approximation (QHA). Here, we present a comparative evaluation of equilibrium cell volumes, cohesive energy, mechanical moduli, and thermophysical properties (Debye temperature and thermal expansion coefficient) for 22 transition metals using semilocal density functionals, including the local density approximation (LDA), Perdew–Burke–Ernzerhof (PBE) and PBEsol generalized gradient approximations (GGAs), and the r2SCAN meta-GGA. PBEsol and r2SCAN deliver the same level of accuracies for structural, mechanical, and thermophysical properties. PBE and r2SCAN perform better than LDA and PBEsol for calculating cohesive energies of transition metals. Among the tested density functionals, r2SCAN provides an overall well-balanced performance for reliably computing cell volumes, cohesive energies, mechanical properties, and thermophysical properties of various 3d, 4d, and 5d transition metals using QHA. Therefore, we recommend that r2SCAN could be employed as a workhorse method to evaluate thermophysical properties of transition metal compounds and alloys in high throughput workflows. [ABSTRACT FROM AUTHOR]

A nanoporous Cu 2 TiSn Heusler alloy is prepared by dealloying-induced phase transformation for electrocatalytic nitrate reduction in neutral conditions and to achieve value-added ammonium phosphomolybdate. [Display omitted] Heusler alloys are a series of well-established intermetallic compounds with abundant structure and elemental substitutions, which are considered as potentially valuable catalysts for integrating multiple reactions owing to the features of ordered atomic arrangement and optimized electronic structure. Herein, a nanoporous copper titanium tin (np-Cu 2 TiSn) Heusler alloy is successfully prepared by the (electro)chemical dealloying transformation method, which exhibits high nitrate (NO 3 –) reduction performance with an NH 3 Faradaic efficiency of 77.14 %, an NH 3 yield rate of 11.90 mg h−1 mg−1 cat , and a stability for 100 h under neutral condition. Significantly, we also convert NO 3 − to high-purity ammonium phosphomolybdate with NH 4 + collection efficiency of 83.8 %, which suggests a practical approach to convert wastewater nitrate into value-added ammonia products. Experiments and theoretical calculations reveal that the electronic structure of Cu sites is modulated by the ligand effect of surrounding Ti and Sn atoms, which can simultaneously enhance the activation of NO 3 −, facilitate the desorption of NH 3 , and reduce the energy barriers, thereby boosting the electrochemical nitrate reduction reaction. [ABSTRACT FROM AUTHOR]

Gallium (Ga) with a low melting point can serve as a unique metallic solvent in the synthesis of intermetallic compounds (IMCs). The negative formation enthalpy of transition metal‐Ga IMCs endows them with high catalytic stability. Meanwhile, their tunable crystal structures offer the possibility to tailor the configurations of active sites to meet the requirements for specific catalytic applications. Herein, we present a general method for preparing a range of transition metal‐Ga IMCs, including Co−Ga, Ni−Ga, Pt−Ga, Pd−Ga, and Rh−Ga IMCs. The structurally ordered CoGa IMCs with body‐centered cubic (bcc) structure are uniformly dispersed on the nitrogen‐doped reduced graphene oxide substrate (O‐CoGa/NG) and deliver outstanding nitrate reduction reaction (NO3RR) performance, making them excellent catalysts to construct highly efficient rechargeable Zn‐NO3− battery. Operando studies and theoretical simulations demonstrate that the electron‐rich environments around the Co atoms enhance the adsorption strength of *NO3 intermediate and simultaneously suppress the formation of hydrogen, thus improving the NO3RR activity and selectivity. [ABSTRACT FROM AUTHOR]

Due to the wide variety of porous materials, studying their properties can be laborious. This paper proposes a porous structure generation algorithm for molecular dynamics simulation, which simplifies and accelerates the study of porous material properties. The algorithm can generate a porous system with a specified porosity, pore size, and solid matrix distribution in the material. The algorithm successfully generates morphology similar to that of experimental samples. This is demonstrated through the example of NiTi intermetallic compound. [ABSTRACT FROM AUTHOR]

Ternary intermetallic rare-earth-based magnetocaloric compounds (RE 2 TM 2 Y, where RE = Gd, Tb, Dy, Ho, Er, Tm, TM= Ni, Cu, Co and Y = Sn, In, Cd, Ga, Al) have attracted attention lately as magnetic refrigerants in addressing major concerns of the conventional system of refrigeration. Assessment of the amount of heat transferred between cold and hot reservoirs at varying applied magnetic fields through relative cooling power (RCP) determination is costly and experimentally intensive which calls for predictive computational techniques with characteristic precision. In this contribution, intelligent-based predictive models are developed through sine activation function-based extreme learning machine (SELM) and genetically optimized support vector regression (GSVR) with Gaussian (GU) and polynomial (PY) kernel functions for data mapping and transformation using applied magnetic field and ionic radii of the constituent elements as descriptors. The GU-GSVR model exhibits superior performance compared to both the PY-GSVR and SELM models when validated using a testing set of ternary intermetallic rare-earth-based magnetocaloric compounds with improvement of 10.55% and 2.28%, respectively using correlation coefficient (CC) as assessment parameter. During model validation, the developed GU-GSVR also showcases enhanced performance across additional performance metrics, including root mean square error (RMSE) and mean absolute error (MAE). The impact of externally applied magnetic field on the RCP of different ternary intermetallic rare-earth-based magnetocaloric compounds was examined by utilizing the developed GU-GSVR model. The characteristic precision and accuracy of the developed computational intelligent models would enable adequate as well as comprehensive investigation of ternary intermetallic rare-earth-based magnetocaloric compounds for a clean system of refrigeration. [ABSTRACT FROM AUTHOR]

We review topological approaches to the analysis of crystal structures of intermetallic compounds and to searching for structural relations between them as the relations between their underlying atomic nets. We introduce the concept of skeletal net to find the simplest system of interatomic contacts in intermetallic compounds, which supports the three-periodic crystal architecture. Using the observed approaches, we have revealed topological relations between crystal structures of binary MeX compounds (Me = Re, Ti or Rh; X = B, C, N, or Si) and found a key role of the body-centered cubic net in their topological hierarchy. We have explored the configuration space of the corresponding crystalline systems by generating all possible 'subnet-supernet' topological transformations, optimized the resulting topological motifs with DFT methods and found a new phase of RhB to be stable above 22 GPa. We discuss the role of topological representations in the prediction of new crystalline chemical substances. [ABSTRACT FROM AUTHOR]

Wire bonding is the most widely used method for encapsulation, connecting chips and external contact points by metal wires. Copper is the most common material for wire bonding. However, the poor oxidation and corrosion resistance necessitates modification such as micro-alloying and coating with precious metals. Research indicates that doping within 1 wt.% of micro-alloy can improve the tensile properties, fatigue life, oxidation resistance, and corrosion resistance of wires without affecting resistance. However, coated wires have issues such as coating peeling or element solid solution during electrification. Excessive doping will reduce thermal conductivity and increase resistance. During chlorination, coated wires suffer from galvanic corrosion and pitting, leading to severe degradation of tensile properties. In contrast, micro-alloyed wires maintain high strength and elongation. In terms of bonding, replacing aluminum substrates with copper substrates can reduce resistance by 1.130 Ω and prevent the embrittlement of joint points caused by intermetallic compound (IMC) layers. In conclusion, PAP (platinum, gold, palladium) micro-alloyed copper wire with copper substrate is a feasible alternative to traditional copper-coated wires and aluminum substrates. [ABSTRACT FROM AUTHOR]

The laser welding of Cu–Al alloys for battery applications in the automotive industry presents significant challenges due to the high reflectivity of copper. Inadequate bonding and low mechanical strength may occur when the laser radiation is directed toward the copper side in an overlap configuration welding. To tackle these challenges, a laser surface treatment technique is implemented to enhance the absorption characteristics and overcome the reflective nature of the copper material. However, elevating the surface roughness and heat-energy input over threshold values leads to heightened temperature and extreme weld. This phenomenon escalates the formation of detrimental intermetallic compounds (IMC), creating defects like cracks and porosity. Metallurgical analysis, which is time-consuming and expensive, is usually used in studies to detect these phases and defects. However, to comprehensively evaluate the weld quality and discern the impact of surface structure, adopting a more innovative approach that replaces conventional cross-sectional metallography is essential. This article proposes a model based on the image feature extraction of the welds to study the effect of the laser-based structure and the other laser parameters. It can detect defects and identify the weld quality by weld classification. However, due to the complexity of the photo features, the system requires image processing and a convolutional neural network (CNN). Results show that the predictive model based on trained data can detect different weld categories and recognize unstable welds. The project aims to use a monitoring model to guarantee optimized and high-quality weld series production. To achieve this, a deeper study of the parameters and the microstructure of the weld is utilized, and the CNN model analyzes the features of 1310 pieces of weld photos with different weld parameters. [ABSTRACT FROM AUTHOR]

This study examines the diffusion bonding of 316 L stainless steel and H13 hot work tool steel, aiming to optimize process parameters and assess the resulting microstructural and mechanical properties. Both materials were bonded at varying temperatures (700, 750, and 850 °C) and times (15, 30, and 60 min). The joints are analyzed using scanning electron microscopy (SEM), energy‐dispersive spectroscopy, and X‐ray diffraction (XRD) to evaluate interfacial morphology, chemical composition, and phase formation. Microhardness measurements indicate an increase in hardness from the 316 L side to the H13 side, suggesting intermetallic phase formation. Shear strength tests show the highest strength at 850 °C for 30 min, with longer times leading to strength reduction due to brittle intermetallic compounds. SEM analysis reveals improved bonding interfaces with fewer voids at higher temperatures and longer times, but the Kirkendall effect causes void formation, negatively impacting mechanical properties. XRD confirms α‐Fe and γ‐Ni phases, with Fe3C forming at 850 °C for 60 min. This study underscores the importance of process parameters in optimizing joint properties and minimizing brittle phase formation, providing insights for industrial applications requiring robust and corrosion‐resistant joints. [ABSTRACT FROM AUTHOR]

This study investigated the impact of incorporating a CrFeNiTiZn High Entropy Alloy (HEA) into the A356 aluminum matrix through the friction stir processing (FSP) technique. The CrFeNiTiZn HEA, renowned for its compositional complexity and high-performance potential, was incorporated into the A356 alloy with different weight percent combinations to enhance its mechanical and tribological characteristics. The results revealed a refined microstructure characterized by solid solution phases and potential intermetallic compound formation due to the HEA addition for A356/2 %Cr2 %Fe2 %Ni2 %Ti2 %Zn composition. Strong interfacial bond strength was also observed among the matrix and reinforcement particles for the A356/2 %Cr2 %Fe2 %Ni2 %Ti2 %Zn composition. The number of grains was found to be about 1820.34 (average grain size is 686 µm) for A356/2 %Cr2 %Fe2 %Ni2 %Ti2 %Zn processed composite with FSP per square inch at 500 magnifications. The A356/2 %Cr2 %Fe2 %Ni2 %Ti2 %Zn composite exhibited improved tensile strength (35.70 %) and hardness (63.33 %) after the addition of 2 %Cr2 %Fe2 %Ni2 %Ti2 %Zn into A356 alloy, attributed to the strengthening effect of HEA particles. Furthermore, wear resistance is notably enhanced, likely due to the synergistic effects of the HEA’s inherent hardness and the modified microstructure. [ABSTRACT FROM AUTHOR]

In this study, fiber laser butt welding was performed on a 6 mm thick Ti-6Al-3Nb-2Zr-1Mo alloy and 10CrNi3MoV steel using two interlayer configurations, with the innovative introduction of an external alternating magnetic field. The microstructure, element distribution, and mechanical properties of the welded joint were investigated through various methods including scanning electron microscopy, energy-dispersive X-ray spectrometer, and X-ray diffraction. Results showed that joints with two interlayer configurations were present in an interfacial layer with non-uniform thickness and poor mechanical properties, due to the heterogeneous heat distribution in the thickness direction and the mixing of elements during the laser welding process. Applying an alternating magnetic field facilitated convection of the molten pool from center to sides, which accelerated forced convection in both vertical and horizontal directions leading to more uniform heat distribution as well as element distribution resulting in a significant reduction or disappearance of unmelted Cu for different interlayers, while also reducing the thickness of the interfacial layer at the upper part of the joint and significantly improving tensile strength by 5.9% and 8.3%, respectively. [ABSTRACT FROM AUTHOR]

The advancement of renewable energy is intricately relied on the development of diverse sustainable electrochemical devices. Persuing exceptionally efficient multifunctional electrocatalysts is imperative, as it promises to significantly streamline the electrode fabrication process, thereby enhancing the overall effectiveness of these devices. Herein, a trifunctional electrocatalysts of N‐doped carbon (NC) supported intermetallic PtZn catalyst (PtZn‐IMC@NC) are reported, which performs highly attractively toward the electrocatalysis of glycerol oxidation reactions (GOR), oxygen reduction reactions (ORR), and hydrogen evolution reactions (HER). Its effectiveness are demonstrated as electrocatalysts for both the anode and cathode in a hybrid acid/alkali direct glycerol fuel cell (AA‐DGFC) and a hybrid acid/alkali glycerol‐hydrogen electrolyzer (AA‐GHEC). The AA‐DGFC can release an impressive peak power density of 286.8 mW cm−2, while the AA‐GHEC achieves a noteworthy current density of 100 mA cm−2 at a significantly low applied voltage of 0.47 V. Such intermetallic PtZn‐based trifunctional electrocatalyst empowers them to establish a self‐powered integrated electrochemical device with the AA‐DGFC driving the AA‐GHEC. This setup exemplifies efficient valorization of glycerol into formate in both cells and hydrogen production in electrolyzer device. This study sparks innovation across diverse applications of multifunctional electrocatalysts and infuses renewed momentum into the realm of advanced energy devices. [ABSTRACT FROM AUTHOR]

Two different types of lead‐free solder joints Cu/(Sn3.0Ag0.5Cu)/Cu and Cu/Sn/(Sn3.0Ag0.5Cu)/Sn/Cu have been investigated. Joints are produced following the transient liquid phase like soldering process. The microstructure of different intermetallic compounds (IMCs) present at the joint interfaces, as well as their indentation hardness and elastic modulus, have been investigated and analyzed using scanning electron microscopy (SEM), X‐ray diffraction (XRD) spectroscopy, and nanoindentation. The exact position of different microcracks inside the interfaces has been identified by analyzing the elastic–plastic properties and interfacial toughness of these solder joints. The modulus and hardness of the Sn multilayer‐assisted solder joint interface are found to be 60.08%, and 90.18% higher than those of its non‐layered counterpart, respectively. The finite element analysis (FEA) has been done to estimate and compute stress distributions over the interfacial region. The dislocation mechanics involved in strengthening the joint strength are related to the nature of stress flow; as observed in FEA. It is reconfirmed that the high susceptibility to brittle failure of the non‐layered Cu‐SAC305 solder joints could be avoided by using a Sn interlayer in between the Cu substrates and the SAC305 solder paste. [ABSTRACT FROM AUTHOR]

Transition metal carbide shows excellent performance in selective hydrogenation of acetylene, however, the carburization of Pd-based intermetallic compounds remains infeasible. Here we report the successful synthesis of an unprecedented Pd3ZnCx intermetallic carbide, via co-infiltration of zinc and carbon in one-step carburization by syngas. Utilizing state-of-the-art in situ characterizations and theoretical calculation, we unveil the dynamic evolution of Pd3ZnCx during carburization, forming a Pd3Zn like cubic phase carbide structure. A unique transitional state (Pdt) with low content of Zn/C co-infiltration is clearly identified facilitating phase transition and sustain incorporation of carbon and zinc at elevated temperatures. The Pd3ZnCx carbide shows by far the best catalytic performance in the selective hydrogenation of acetylene with a high selectivity (>90%) even at a high H2/C2H2 ratio. Our results therefore provide a co-infiltration strategy and dynamic insights for the one-step synthesis of Pd based intermetallic carbides, towards high-performance intermetallic compound for selective hydrogenation of acetylene. Transition metal carbides exhibit outstanding performance in the selective hydrogenation of acetylene, but carburizing Pd-based intermetallic compounds has been challenging. Here, the authors present a successful synthesis of Pd3ZnCx intermetallic carbide for selective hydrogenation of acetylene through a one-step co-infiltration of zinc and carbon using syngas. [ABSTRACT FROM AUTHOR]

With the continuous pursuing on the improvement of catalytic activity, a catalyst performed exceeding catalytic volcano plots is desired, while it is impeded by the adsorption‐energy scaling relations of reaction intermediates. Numerous efforts have been focused on optimizing the initial and final intermediates to circumvent the scaling relations for an improved performance. For a step forward, simultaneously optimizing all intermediates is essential to explore the theoretical maximum of catalytic activity. Herein, we proposed a dynamic adsorption mechanism (DAM) to independently regulate the adsorption configurations of all intermediates of electrochemical nitrogen reduction reaction (NRR). To demonstrate the DAM, a multi‐site NbNi3 intermetallic is developed, which enables suitable adsorption energies of different intermediates via modulating orbital coupling mechanisms. As a result, NbNi3 achieves an ultra‐low limiting potential of NRR of −0.11 V vs. reversible hydrogen electrode (RHE). Strikingly, the theoretical result is confirmed by a proof‐of‐concept experiment, wherein the nanoporous NbNi3 electrode exhibits a remarkable NH3 yield rate of 25.89 μg h−1 cm−2 with the Faradaic efficiency of 33.15 % at −0.25 V vs. RHE. Overall, this work brings out a new strategy to avoid the scaling relations, and opens up a promising avenue toward high‐efficiency NRR catalysts. [ABSTRACT FROM AUTHOR]

NiAl bi‐ and trilayers are prepared by alternating evaporation of aluminum and nickel on float glass substrates under high vacuum, with individual layer thicknesses between 20 and 100 nm. The samples are subjected to an annealing procedure to temperatures of up to 300 °C in vacuum, and the structural changes induced by the heat treatments are followed by in situ grazing incidence X‐ray absorption spectroscopy experiments at the Ni K‐edge. The results show that the elemental metallic deposits are stable up to 180 °C, while a slow formation of the intermetallic NiAl compound occurs at temperatures above 200 °C. No additional reaction intermediates are detected. Linear combination fits employing spectra of face‐centered metallic Ni and body‐centered NiAl as references allow to quantify the contributions of the respective phases as a function of the temperature and the depth in the multilayer. In general, an increase of the phase fraction of the intermetallic NiAl phase is detected. While the deposited elemental metals cannot completely be transformed into this intermetallic compound for the Al–Ni bilayer system even after prolonged annealing at 240 °C, the analysis of the spectra of the Al–Ni–Al trilayer suggests almost complete conversion to NiAl with body‐centered‐cubic structure. [ABSTRACT FROM AUTHOR]

This study used electroless nickel‐immersion gold surface finish. The lead free solder used are tin‐silver‐copper 305 and tin‐silver‐copper 307 solder alloys. The difference in copper composition will affect the intermetallic compound′s microstructure after the laser soldering process. The intermetallic compound formation analysis reveals that only (Cu, Ni)6Sn5 was observed at the solder joint interface for both solders after laser soldering. The grain microstructure of tin‐silver‐copper 305 formed is rounded‐shaped and bar‐shaped, while tin‐silver‐copper 307 shapes are oval‐shaped and flake‐like. However, for cross‐sectioned analysis, the intermetallic compound grain microstructure formed at the solder joint formation was (Ni, Cu)3Sn4 and (Cu, Ni)6Sn5 presented in dendrite‐like and scale‐like shapes. This result shows that copper content in solder composition is directly affected the intermetallic compound grain microstructure. When exposed to the ageing process, the intermetallic compound thickness will increase directly with ageing time. The intermetallic compound thickness for tin‐silver‐copper 305 was increased from 0.98 μm to 8.34 μm while tin‐silver‐copper 307 was increased from 1.54 μm to 8.76 μm. The result also shows that nano‐sized of Ag3Sn grain particle was formed on the intermetallic compound surface after an ageing process for both samples, tin‐silver‐copper 305 and tin‐silver‐copper 307. [ABSTRACT FROM AUTHOR]

As the scaling down of semiconductor devices reaches its physical limits, 3D stacking packaging technology is emerging as a new miniaturization solution. Among the various 3D packaging technologies, Cu direct bonding is widely adopted due to copper's excellent electrical conductivity and the absence of intermetallic compounds for solder bumps. Since copper readily undergoes oxidation, technologies that prevent Cu surface oxidation during Cu direct bonding are essential. However, current research suggests that the methods require additional pretreatment processes, which demand high costs. In this study, a Cu direct bonding method utilizing glycerol vapor is developed to effectively streamline the pretreatment steps. The potential of glycerol as a reducing agent and antioxidant for Cu is demonstrated using a silicon die sample with a size of 10  ×  10 mm2, verified through the X‐ray photoelectron spectroscopy. The Cu direct bonding for 3D semiconductor packaging is successfully performed under glycerol vapor atmosphere, without any plasma pretreatment. The cross‐section of the bonded specimens is examined by scanning electron microscopy, and mechanical reliability is assessed by die shear testing. [ABSTRACT FROM AUTHOR]

In this article, dissimilar magnesium and aluminum alloys were welded with a Zn interlayer and TiC nanoparticles by friction stir welding. Optimal joining conditions were achieved by a combination of three traverse speeds (30, 45, and 60 mm/min) and constant rotational speeds (1050 rpm). The best microstructure evolution and mechanical properties were achieved for specimens joined at rotational and traverse speeds of 1050 rpm and 45 mm/min, respectively. The grain size decreases as the traverse speed increases from 30 to 45 mm/min due to a reduction in heat input, an improvement in reinforcing distribution, and high intermixing of materials, then increases from 45 to 60 mm/min due to inadequate heat input for recrystallization process. It was shown that the TiC particles play a prominent role in the microstructure modification and enhance mechanical properties of weld samples while the Zn foil interlayer plays a vital in avoiding the formation of Al-Mg IMC phases. The obtained result under optimal welding parameters indicates that MgZn2, Mg-Al-Zn compounds, Mg and Al solid solution, were the main detected common phases in the stir zone instead of the brittle and hard Al-Mg IMCs formation. The average hardness values of 232 Hv were achieved, while the strength of the weld specimen experiences the 189 MPa value. In addition, a combination of brittle and ductile modes was observed based on the fracture surface of the weld sample after the tensile test. [ABSTRACT FROM AUTHOR]

The introduction of Zn improves the wettability and surface lithiophilicity of Cu foam toward Li metal, and a sublevel scaffold of Li x Zn alloy is constructed in the pores of Cu foam, regulating uniform Li deposition in the modified 3D skeleton. [Display omitted] Lithium (Li) metal anode (LMA) is one of the most promising anodes for high energy density batteries. However, its practical application is impeded by notorious dendrite growth and huge volume expansion. Although the three-dimensional (3D) host can enhance the cycling stability of LMA, further improvements are still necessary to address the key factors limiting Li plating/stripping behavior. Herein, porous copper (Cu) foam (CF) is thermally infiltrated with molten Li-rich Li-zinc (Li-Zn) binary alloy (CFLZ) with variable Li/Zn atomic ratio. In this process, the LiZn intermetallic compound phase self-assembles into a network of mixed electron/ion conductors that are distributed within the metallic Li phase matrix and this network acts as a sublevel skeleton architecture in the pores of CF, providing a more efficient and structured framework for the material. The as-prepared CFLZ composite anodes are systematically investigated to emphasize the roles of the tunable lithiophilicity and hierarchical structure of the frameworks. Meanwhile, a thin layer of Cu-Zn alloy with strong lithiophilicity covers the CF scaffold itself. The CFLZ with high Zn content facilitates uniform Li nucleation and deposition, thereby effectively suppressing Li dendrite growth and volume fluctuation. Consequently, the hierarchical and lithiophilic framework shows low Li nucleation overpotential and highly stable Coulombic efficiency (CE) for 200 cycles in conventional carbonate based electrolyte. The full cell coupled with LiFePO 4 (LFP) cathode demonstrates high cycle stability and rate performance. This work provides valuable insights into the design of advanced dendrite-free 3D LMA toward practical application. [ABSTRACT FROM AUTHOR]

Brittle intermetallic compounds (IMCs) at the interface of dissimilar materials can seriously affect the mechanical properties of the dissimilar components. Introducing external assisted fields in the fabrication of dissimilar components is a potential solution to this problem. In this study, an alternating magnetic field (AMF) was introduced for the first time in the additive manufacturing of Ti6Al4V/AA2024 dissimilar alloy components by laser-directed energy deposition (L-DED). The effect of the AMF on the interfacial IMCs' distribution was studied. The results indicate that the contents of the IMCs were different for different magnetic flux densities and frequencies, and the lowest content was obtained with a magnetic flux density of 10 mT at a frequency of 40 Hz. When an appropriate AMF was applied, the IMC layer was no longer continuous at the interface, and the thickness was notably decreased. In addition, the influence of the AMF on the temperature distribution and fluid flow in the melt pool was analyzed through numerical simulation. The simulation results indicate that the effect of the AMF on the temperature of the melt pool was not significant, but it changed the flow pattern inside the melt pool. The two vortices inside the cross-section that formed when the AMF was applied caused different orientations of club-shaped IMCs inside the deposition layer. A sudden change in the streamline direction at the bottom of the longitudinal cross-section of the melt pool can affect the formation of the IMC layer at the interface of dissimilar materials, resulting in inconsistent thickness and even gaps. This work provides a useful guidance for regulating IMCs at dissimilar material interfaces. [ABSTRACT FROM AUTHOR]

Considering energy conservation and emission reductions, lightweight automobiles have become a research focus in the automotive industry. Steel/aluminum joining is regarded as an ideal lightweight structure, which can not only reduce the energy consumption but also ensure safety and is already attracting extensive attention. In this study, aluminum alloy 6061 and B410LA steel sheets were successfully joined by refill friction stir spot welding. The tensile properties, microhardness distribution and interfacial microstructure characteristics of the steel/Al welded joints were investigated. The maximum tensile load of the steel/Al joint was 4.3 kN. The mechanical properties of the steel/Al refill friction stir spot welded joint were largely determined by the bonding quality of the sleeve-plunging zone. With the stirring of the sleeve and the pin during the refill friction stir spot welding, work hardening occurred in the stir zone (SZ). The microhardness of the SZ was significantly higher than that of the steel base metal (BM) and could be detected on the steel side. The Fe-Al intermetallic compound (IMC) layer was continuously distributed at the interface of the sleeve-plunging zone, revealing good uniformity in the thickness. In particular, a hook-and-vortex-like structure formed during the refill friction stir spot welding process in the sleeve-plunging zone, producing a mechanical interlock effect at the interface. The ideal mechanical properties of the welded joint could be attributed to the good quality of the metallurgical and mechanical bonding at the interface, especially the mechanical interlock effect, thereby depending on the hook-and-vortex-like structure. [ABSTRACT FROM AUTHOR]

Solder joint, crucial component in electronic systems, face significant challenges when exposed to extreme conditions during applications. The solder joint reliability involving microstructure and mechanical properties will be affected by extreme conditions. Understanding the behaviour of solder joints under extreme conditions is vital to determine the durability and reliability of solder joint. This review paper aims to comprehensively explore the underlying failure mechanism affecting solder joint reliability under extreme conditions. This study covers an in-depth analysis of effect extreme temperature, mechanical stress, and radiation conditions towards solder joint. Impact of each condition to the microstructure including solder matrix and intermetallic compound layer, and mechanical properties such as fatigue, shear strength, creep, and hardness was thoroughly discussed. The failure mechanisms were illustrated in graphical diagrams to ensure clarity and understanding. Furthermore, the paper highlighted mitigation strategies that enhancing solder joint reliability under challenging operating conditions. The findings offer valuable guidance for researchers, engineers, and practitioners involved in electronics, engineering, and related fields, fostering advancements in solder joint reliability and performance. [ABSTRACT FROM AUTHOR]

In this study, the effect of intermetallic compounds (ICMs) on the tribocorrosion behavior of the 7075 aluminum alloy was investigated. ICMs play important roles in the tribocorrosion resistance and mechanism of the sample. In the as-received sample, micron-sized Mg2Si, Al23Fe4Cu, and nanosized MgZn2 induced pitting corrosion and acted as abrasive materials. Accompanying the re-dissolution of Mg2Si and the growth of MgZn2, the pitting resistance worsened and adhesive wear took place. Subsequently, MgZn2 precipitated along the grain boundaries, which resulted in intergranular corrosion and aggravation of adhesive wear. [ABSTRACT FROM AUTHOR]

We examined the hydrogen diffusion behavior in the Al–Si-coating layer which underwent the press-hardening simulation. The microstructure evolution, in particular, the type of intermetallic compounds, was revealed to have a remarkable influence on the hydrogen absorption. It was found that the formation of AlFe in the coating layer was advantageous regarding to the suppression of hydrogen penetration across the coating layer, which was originating from the lower hydrogen diffusivity compared to the Al5Fe2. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is the formation and growth of nanoscale intermetallic compounds (IMCs) when laser is used as a heat source to form solder joints. Design/methodology/approach: This study investigates the Sn/Cu and Sn-0.1AlN/Cu structure using laser soldering under different laser power: (200, 225 and 250 W) and heating time: (2, 3 and 4 s). Findings: The results show clearly that the formation of nano-Cu6Sn5 films is feasible in the laser heating (200 W and 2 s) with Sn/Cu and Sn-0.1AlN/Cu system. The nano-Cu6Sn5 films with thickness of 500 nm and grains with 700 nm are generally parallel to the Cu surface with Sn-0.1AlN. Both IMC films thickness of Sn/Cu and Sn-0.1AlN/Cu solder joints gradually increased from 524.2 to 2025.8 nm as the laser heating time and the laser power extended. Nevertheless, doping AlN nanoparticles can slow down the growth rate of Cu6Sn5 films in Sn solder joints due to its adsorption. Originality/value: The formation of nano-Cu6Sn5 films using laser heating can provide a new method for nanofilm development to realize the metallurgical interconnection in electronic packaging. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to investigate the effect of incorporating cobalt (Co) into Sn-58Bi alloy on its phase composition, tensile properties, hardness and thermal aging performances. The fracture morphologies of tensile-tested solders are also investigated to correlate the microstructural changes with tensile properties of the solder alloys. Then, the thermal aging performances of the solder alloys are investigated in terms of their intermetallic compound (IMC) layer morphology and thickness. Design/methodology/approach: The Sn-58Bi and Sn-58Bi-xCo, where x = 1.0, 1.5 and 2.0 Wt.%, were prepared using the flux doping technique. X-ray diffraction (XRD) is used to study the phase composition of the solder alloys, whereas scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) are used to investigate the microstructure, fractography and compositions of the solders. Tensile properties such as ultimate tensile strength (UTS), Young's modulus and elongation are tested using the tensile test, whereas the microhardness value is gained from the micro-Vickers hardness test. The morphology and thickness of the IMC layer at the solder's joints are investigated by varying the thermally aging duration up to 56 days at 80°C. Findings: XRD analysis shows the presence of Co3Sn2 phase and confirms that Co was successfully incorporated via the flux doping technique. The microstructure of all Sn-58Bi-xCo solders did not differ significantly from Sn-58Bi solders. Sn-58Bi-2.0Co solder exhibited optimum properties among all compositions, with the highest UTS (87.89 ± 2.55 MPa) at 0.01 s−1 strain rate and the lowest IMC layer thickness at the interface after being thermally aged for 56 days (3.84 ± 0.67 µm). Originality/value: The originality and value of this research lie in its novel exploration of the flux doping technique to introduce minor alloying of Co into Sn-58Bi solder alloys, providing new insights into enhancing the properties and performance of these solders. This new Sn-Bi-Co alloy has the potential to replace lead-containing solder alloy in low-temperature soldering. [ABSTRACT FROM AUTHOR]

The magnetic properties of Ho6MnBi2 and Ho6FeBi2 crystals are investigated by means of density functional theory. These materials are currently an active subject of research in the context of magnetic refrigeration applications since they exhibit a remarkable magnetocaloric effect. In this work, the equation of state, density of states and magnetic moments are calculated and compared with previous experimental results for these materials. Also, the Curie temperatures for the paramagnetic to ferromagnetic phase transition observed in these systems are calculated from first principles. All the calculated quantities are in reasonable agreement with experimental data, which suggests that density functional theory could provide a reliable framework to theoretically investigate the magnetic properties of intermetallic ternary compounds. [ABSTRACT FROM AUTHOR]

The aims of this study were to explore the nitriding mechanism of Ti‐6Al‐4 V alloy in Al2O3‐based refractories. Al2O3‐based composite refractories were fabricated using Ti‐6Al‐4 V and sintered alumina as main materials, followed by nitriding at different temperatures in a nitrogen atmosphere. Phase and microstructure evolution of the products was analyzed by X‐ray diffraction and field‐emission scanning electron microscopy equipped with energy‐dispersive X‐ray spectroscopy. The results reveal a multi‐stage nitridation process of Ti‐6Al‐4 V at different temperatures. At 900°C, nitridation of the Ti‐6Al‐4 V surface results in the formation of a (Ti,V)N solid solution, while Al and V migrate inward, forming intermetallic compounds Ti3Al and a‐Ti (Ti1‐x‐yVxAly) with rich Al and V. At 1100°C, nitridation of Ti3Al produces intermediate products like Ti2AlN or Ti3AlN, with continued inward migration of Al or V to form the intermetallic α2 phase of (Ti1‐xVx)3yAly in the center of the alloy particles. At 1300°C, decomposition of Ti2AlN or Ti3AlN results in the outward migration of Al atoms and the presence of AlN on the outer layer of Ti‐6Al‐4 V particles, thus forming a hollow structure. Finally, at 1500°C, the (Ti,V)N solid solution grains grow as a result of further diffusion and dissolution of nitrogen. [ABSTRACT FROM AUTHOR]

With its high energy density, lithium metal battery technology encounters empirical challenges such as pulverization and dendrite growth. These can hinder the achievement of long lifespans. To address these challenges, it is important to optimize the lithium charge behavior. Here, the determination of the appropriate structural conditions and processes to prevent the accumulation of lithium ions on the lithium surface is discussed. Employing a hierarchical structure of polymeric macro/mesopores at the lithium interface, the favorable behavior of lithium ions and the reaction process is monitored. And the way of alloying process is proposed, revealing lithium ion accepted alloyable metals make to lithium‐metal intermetallic compounds. The well‐distributed alloyable metals in the unidimensional polymeric interface have sufficient capacity to accommodate and transport lithium ions. This emphasizes the need for innovative strategies to address irregular lithium nucleation and enhance lithium metal battery technology. [ABSTRACT FROM AUTHOR]

Due to their distinct characteristics and prospective uses in several disciplines, half-Heusler (HH) materials are a family of intermetallic compounds that have garnered a lot of attention. HH compounds have a cubic crystal structure and exhibit a wide range of electronic, optical, mechanical and thermoelectric characteristics. Direct bandgap acquired by the WC-GGA (TB + mBJ) approach is 1.07 eV (2.26 eV), 0.61 eV (1.71 eV), 0.76 eV (1.68 eV), and 0 eV (0.78 eV) for KMgP, KMgAs, KMgSb, and KMgBi, respectively. Threshold power ε 2 (ω) of KMgX (X = P , As, Sb, and Bi), starts from 2.218, 1.701, 1.674, and 0.776 eV, so they exhibit the distinct peaks at 4.014, 3.742, 3.388, and 3.197 eV, correspondingly. Among these materials, the maximum value of Seebeck coefficient (S) has been attained at 300 K. Specifically, KMgP achieves the highest value of S at 3.134 mV/K, followed by KMgAs at 2.947 mV/K, KMgSb at 2.893 mV/K, and KMgBi at 1.431 mV/K, all in their respective p-type configurations. In order to determine the compound's stability, we will explore the elastic and thermodynamic properties. We will also discuss their possible applications in photovoltaic and thermoelectric devices. [ABSTRACT FROM AUTHOR]

Gradient hierarchically porous structures are effective for enhancing catalytic reactions due to their capability of enabling fast mass transfer from solutions to inner active sites. However, facile and rational designing of the construction with uniform spatial gradients and high stability remains challenging. Here, a self‐supporting high‐entropy alloy (HEA) catalyst with a unique triple‐scale gradient porosity based on physical metallurgy is reported. The hierarchically porous structure of the catalyst can be effectively manipulated by tailoring the multi‐length scale phases of a negative mixing enthalpy FeCoNiCr‐Zr eutectic HEA. As an oxygen‐evolving catalyst, the hierarchically porous HEA demonstrates low overpotentials of 215 and 370 mV at 10 mA cm−2 and 1A cm−2, respectively. This is primarily attributed to the gradient mesoporosity providing abundant accessible reactive sites and exceptional intrinsic reactivity resulting from the synergistic electronic effects of multi‐component alloying. Furthermore, benefiting from the integrative gradient porosity that can suppress drastic gas bubble impact and the chemically stable configuration of inherent high‐entropy intermetallic compounds, the catalyst exhibits extraordinary durability for over 1000 h at 2 A cm−2. This work provides a new paradigm for developing high‐efficiency and low‐cost catalysts with robust gradient hierarchically porous structures for practical applications in various energy conversion technologies. [ABSTRACT FROM AUTHOR]

This paper studies how isothermal aging affects the micromechanical and structural properties of mixed solder joints made of 60Sn-40Pb (SnPb) with Sn-3.0Ag-0.5Cu (SAC305) and SnPb with Sn-0.7Cu (SnCu). The nanoindentation test was done to measure the micromechanical properties of SnPb/SAC305 and SnPb/SnCu mixed solder joints. These properties are hardness, reduced modulus, and stress exponent. Scanning electron microscopy (SEM) was used to look at the microstructure of a cross-section of mixed solder joints. The micrographs that were taken were then examined with open-source image processing software called ImageJ. It was found that the rate and distribution of intermetallic compound (IMC) formation and the reduction of Sn-rich phase grain size affect how the hardness and stress exponent values of mixed solder joints change after 1000 h of high temperature storage (HTS). ImageJ analysis shows that the Pb-rich phase particle count and distribution can be used to figure out how mixed solder joints respond to indentation creep and how that relates to isothermal aging. Using ImageJ, it's clear that the indentation creep behavior of the GBS mechanism of an as soldered SnPb/SnCu mixed solder joint is caused by the highest number and size of Pb-rich phase particles that are not well distributed across the dendritic area of Sn-rich phase grain boundaries. [ABSTRACT FROM AUTHOR]

Aluminum‒magnesium alloys are widely used in the shipbuilding and railcar industries because of their high specific strength and corrosion resistance. However, the welding of aluminum–magnesium alloys to steel poses a number of significant issues, mainly due to the formation of brittle intermetallic compounds (IMCs) and adiabatic shear bands (ASBs). The effects of IMCs on the mechanical properties of joints have been well researched, but there is a limited understanding of how ASBs and magnesium affect these properties. In this work, the effects of ASBs and Mg2Al3 on the mechanical properties of explosive-welded bimetals are studied. Optical microscopy, electron microscopy, confocal laser scanning microscopy, and electron backscatter diffraction (EBSD) were performed. Additionally, Vickers hardness tests, tear strength tests, and bending tests were carried out to determine the mechanical properties of the specimens. The results of the study revealed that at the weld interface after explosive welding, a zone of fine dark-etching Mg2Al3 phase accumulation up to 10 µm thick and an ASB zone up to 400 µm thick formed. The thickness and included volume of both zones increase from 3 to 20 vol.% with increasing detonation velocity. The tear strength also increases (from 80 to 230 MPa). After heat treatment at 200 °C for 1 h, the specimens survived at twice the bending angle, indicating good plastic properties. Thus, the results help elucidate the influence of Mg2Al3 and ASBs on the properties of bimetals with AlMg6 alloys obtained via explosive welding. [ABSTRACT FROM AUTHOR]

Ensuring a consistently high-strength connection in superalloy components of space shuttles from 25 to 1200 °C is essential yet challenging. To achieve the objective, we developed an adhesive using silicon-boron modified phenolic resin (Si-BPF) as the matrix and inorganic fillers as additives. The continuous Si– O –Si– O –B– O –B skeleton endowed the Si-BPF with excellent thermal stability. In addition, the inorganic fillers inhibited the thermal decomposition of Si-BPF. The generation of low-melting-point glass phases compensated for the defects in the adhesive. Therefore, within the "300–600 °C weak strength interval", the synergistic effect of Si-BPF and inorganic additives increased the adhesive strength to 17.26 MPa. The formation of intermetallic compounds and the ceramization of the adhesive resulted in a gradual increase in the bonding strength of the composite adhesive with increasing temperature, reaching 34.23 MPa after 1200 °C. The adhesive enabled high-strength bonding for superalloys throughout the wide temperature range, enhancing the application of superalloy components in space shuttles. [ABSTRACT FROM AUTHOR]

This study investigated the corrosion behaviour of dissimilar steel-to-aluminium laser-welded conduction, and keyhole mode (partial- and full-penetration) lap joints through electrochemical techniques and advanced microstructural characterisation. The corrosion resistance of the weld was found to be higher than the base materials, primarily due to the presence of cathodic FexAly (η-Fe2Al5, θ-Fe4Al13, β-FeAl) intermetallic compounds (IMCs) with high corrosion potential. The different micro and macro-galvanic corrosion mechanisms were found at various interfaces around the weld, resulting in localised pitting corrosion. The keyhole mode welding showed improved corrosion resistance, primarily attributed to the type, size, and distribution of IMCs. [ABSTRACT FROM AUTHOR]

Advancing the design of cathode catalysts to significantly maximize platinum utilization and augment the longevity has emerged as a formidable challenge in the field of fuel cells. Herein, we rationally design a high entropy intermetallic compound (HEIC, Pt(FeCoNiCu)3) for catalyzing oxygen reduction reaction (ORR) by an efficient machine learning stategy, where crystal graph convolutional neural networks are employed to expedite the multicomponent design. Based on a dataset generated from first‐principles calculations, the model can achieve a high prediction accuracy with mean absolute errors of 0.003 for surface strain and 0.011 eV atom−1 for formation energy. In addition, we identify two chemical features (atomic size difference and mixing enthalpy) as new descriptors to explore advanced ORR catalysts. The carbon supported Pt(FeCoNiCu)3 catalyst with small particle size is successfully synthesized by a freeze‐drying‐annealing technology, and exhibits ultrahigh mass activity (4.09 A mgPt−1) and specific activity (7.92 mA cm−2). Meanwhile, The catalyst also shows significantly enhanced electrochemical stability which can be ascribed to the sluggish diffussion effect in the HEIC structure. Beyond offering a promising low‐Pt electrocatalysts for fuel cell cathode, this work offers a new paradigm to rationally design advanced catalysts for energy storage and conversion devices. [ABSTRACT FROM AUTHOR]

The increasing anthropogenic carbon dioxide emissions (CO2) have a huge environmental impact, and CO2 emission reduction is already a common view in our society. Recently, selective hydrogenation of CO2 to methanol has attracted much attention because the process can effectively mitigate CO2 emissions and simultaneously produce high‐value‐added chemicals and fuels. The catalysts play a very important role in achieving high efficiency of CO2 to methanol. As one promising alternative, the alloy catalysts have demonstrated high performance in CO2 hydrogenation to methanol due to their unique geometry and electronic properties. Herein, we review the recent advances in alloy catalysts, including solid solution alloys and intermetallic compounds (mainly Cu‐based, In‐based, Ga‐based, and other alloy catalysts) for heterogeneous catalysis of CO2 hydrogenation to methanol. Moreover, the research ideas and development prospects of alloy catalysts for CO2 hydrogenation to methanol are overviewed to provide the ideas and references for the subsequent research on alloy catalysts for CO2 hydrogenation. [ABSTRACT FROM AUTHOR]

Pt‐based intermetallic compounds have been considered promising electrocatalysts in the practical applications of fuel cells; however, the development of Pt‐based catalysts that meet performance targets of high activity, maximized stability, and low cost remains a huge challenge. Herein, an atomically ordered and low‐Pt intermetallic nitride (PtMn3N) catalyst are synthesized consisting of a strained Pt shell and PtMn3N core on carbon support via the KCl‐matrix protection strategy. The PtMn3N catalyst represents a high mass activity of 0.70 A mgPt−1 at 0.9 V and a specific activity degradation of 4.2% after 5000 potential cycles for the oxygen reduction reaction (ORR) in rotating disk electrode (RDE) testing, which substantially outperformed commercial Pt/C (0.25 A mgPt−1 and 17.4%). Density functional theory calculations reveal that the introduction of Mn elements to the Pt lattice is beneficial to produce appropriate compressive strain to weaken the binding energy of oxygen species and the introduction of N elements to promote the strong metal‐N interactions is conducive to alleviating the dissolution of metal atoms, allowing for displaying the prominent durability. This work provides an effective strategy of N‐doped Pt‐based intermetallic compounds to enhance the corrosion resistance of 3d transition metals and to enhance the ORR performance. [ABSTRACT FROM AUTHOR]

This article studies the process of laser alloying of aluminum and alloy AL25 with metals: nickel, chromium, niobium, in a melting regime. Choice of metals for the study is made according to the criterion of efficiency of melt zone filling under laser treatment. Theoretical analysis of possible intermetallic phases within Al–Ni, Al–Cr, Al–Nb systems is performed, including physical parameters and crystallographic characteristics. Experimental studies by methods of metallography and X-ray diffraction analysis allows establishment of the spectrum of phases formed during alloying of aluminum from powders of these elements. They include both aluminum-rich intermetallics, and chemical compounds enriched with alloying metal. Alloying with niobium disilicide is also investigated to reveal differences in mechanisms of introducing chemical compounds into a laser-affected zone. On alloying with NbSi2 particles get into the melt zone directly from the powder (a mechanism of particle "flight"), and when alloying with pure metal intermetallic formation of occurs in situ during crystallization. On the basis of calculating the change in lattice spacing of aluminum the concentration of alloying metals within supersaturated solid solution is estimated. The increase in microhardness of alloying zones due to solid solution hardening and dispersion strengthening by intermetallic particles is established. [ABSTRACT FROM AUTHOR]

The reliability of solder joints in electronic packaging was investigated by finite element analysis (= FEA), focusing on the effects of intermetallic compound (= IMC) layers and voids. The results showed that changes in the elastic modulus of the IMC layer of around 20 % did not significantly affect solder joint life. This means that when the modulus of elasticity changes, it is not only the change in modulus that is considered, but also the change in creep properties. In addition, the FEA evaluation of voids underscores the importance of considering equivalent creep strain and cautions against relying solely on the FEA results when void locations do not coincide with maximum equivalent creep strain values. Currently, it is difficult to predict the tendency of voids to affect solder creep life based on FEA analysis results alone. A limitation is that if voids are present in the solder not at the IMC interface, the solder creep life may be underestimated. This study contributes to a better understanding of the complex thermal-fatigue life that solder joint reliability in electronic packaging. [ABSTRACT FROM AUTHOR]

Electron backscattered diffraction (EBSD) characterization was conducted on the typical regions in friction-stir-welded dissimilar Al/Mg joints of 2 mm thick sheets with/without ultrasonic assistance. The effects of ultrasonic vibration (UV) on the grain size, recrystallization mechanisms, and degree of recrystallization on both sides of the Al-Mg bonding interface and the intermetallic compounds (IMCs) were investigated. It was found that on the Mg side of the weld nugget zone (WNZ), the primary dynamic recrystallization (DRX) mechanisms were discontinuous dynamic recrystallization (DDRX) and continuous dynamic recrystallization (CDRX), with geometric dynamic recrystallization (GDRX) playing a secondary role. On the Al side of the WNZ, CDRX was identified as the primary mechanism, with GDRX as a secondary contributor. While UV did not significantly alter the DRX mechanisms in either alloy within the WNZ, it promoted the aggregation and rearrangement of dislocations. This led to an increase in high-angle grain boundaries (HAGBs) and an enhanced degree of recrystallization in the welds. The average grain size in both the Al and Mg alloys of the WNZ followed a pattern of initially increasing and then decreasing along the thickness direction, reaching a maximum in the upper-middle part and a minimum at the bottom. The influence of UV on the average grain size in the WNZ was minimal, with only slight grain refinement observed, and the minimum refinement degree was only 0.9%. The Schmid factor (SF) on the WNZ and thermo-mechanically affected zone (TMAZ) boundary regions of the advancing side (AS) indicates that the application of UV increased the likelihood of basal slip and extension twinning in the crystal structure. In addition, UV reduced the thickness of IMCs and improved the strength of the Al-Mg bonding interface. These results suggest a higher probability of fracture along the TMAZ and WNZ boundary on the AS when UV was applied. [ABSTRACT FROM AUTHOR]

Herein, we fabricated a low-melting-point Zr-16Ti-6Cu-8Ni-6Co eutectic filler based on a Zr-Ti-Cu-Ni filler to achieve effective joining of a Ti6Al4V (TC4) titanium alloy. The temperature at which the brittle intermetallic compound (IMC) layer in the seam completely disappeared was reduced from 920 °C to 900 °C, which broadened the temperature range of the Zr-based filler, brazing the TC4 without a brittle IMC layer. The shear strength of the Zr-16Ti-6Cu-8Ni-6Co brazed joint increased by 113% more than that of the Zr-16Ti-9Cu-11Ni brazed joint at 900 °C. The proportion of β-Ti in the seam of the Zr-16Ti-6Cu-8Ni-6Co brazed joint increased by 21.31% compared with that of the Zr-16Ti-9Cu-11Ni brazed joint. The nano-indentation results show that the elastic modulus of the β-Ti (143 GPa) in the interface is lower than that of the α-Ti (169 GPa) and (Ti,Zr)2(Ni,Cu,Co) (203 GPa). As a result, the β-Ti is subjected to a greater strain under the same stress state compared with the α-Ti and (Ti,Zr)2(Ni,Cu,Co), and the Zr-16Ti-6Cu-8Ni-6Co brazed joint can maintain a higher strength than the Zr-16Ti-9Cu-11Ni brazed joint under a middle–low erosion area of the TC4 base metal. This provides valuable insights into the use of high-strength, fatigue-resistant TC4 brazed joints in engineering applications. [ABSTRACT FROM AUTHOR]

The aim of this work is to obtain Cu-13.5Al-4Ni alloy for use as shape memory alloy by Spark Plasma Sintering (SPS) of mechanically alloyed powder. The study investigates the structural and microstructural changes in terms of crystal parameters, crystallite sizes, and phases evolution during mechanical alloying and spark plasma sintering of Cu-13.5Al-4Ni powders. We obtained alloyed powders with a structure composed of α(Cu), AlNi intermetallic compound and small amounts of elemental Al through the mechanical alloying technique. After spark plasma sintering at 900 °C, the microstructure consists of an AlNi compound distributed at the edge of α(Cu) grains. The crystallite sizes of both, α(Cu) and AlNi are in nanoscale order after 16 h of milling (9 and 6.5 nm respectively). After sintering at 900 °C (in Ar atmosphere, without holding time), the crystallite sizes increase to 46 nm for α(Cu) and to 40 nm for AlNi compound. Also, the Cu-13.5Al-4Ni compacts achieve a final density after sintering at 900 °C of around 80% from the theoretical density. [ABSTRACT FROM AUTHOR]

Pt-based intermetallic compound (IMC) nanoparticles have been considered the most promising catalysts for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFC). Herein, we propose a strategy for producing ordered Pt3(CoNi) ternary IMC nanoparticles supported on N-doped carbon materials. Particularly, the Co and Ni are originally embedded into ZIF-derived carbon, which diffuse into Pt nanocrystals to form Pt3(CoNi) nanoparticles. Moreover, a thin layer of carbon develops outside of Pt3(CoNi) nanoparticles during the cooling process, which contributes to stabilizing the Pt3(CoNi) on carbon supports. The optimal Pt3(CoNi) nanoparticle catalyst has achieved significantly enhanced activity and stability, exhibiting a half-wave potential of 0.885 V vs reversible hydrogen electrode (RHE) and losing only 16 mV after 10,000 potential cycles between 0.6 and 1.0 V. Unlike the direct-use commercial carbon (VXC-72) for depositing Pt, we utilized ZIF-derived carbon containing dispersed Co and Ni nanocluster or nanoparticles to prepare ordered Pt3(CoNi) intermetallic catalysts. [ABSTRACT FROM AUTHOR]

Bioresorbable magnesium-metal vascular stents are gaining popularity due to their biodegradable nature and good biological and mechanical properties. They are also suitable candidate materials for biodegradable stents. Due to the rapid degradation rate of Mg metal vascular scaffolds, a Mg/Zn bilayer composite was formed by a number of means, such as magnetron sputtering and physical vapor deposition, thus delaying the degradation time of the Mg metal vascular scaffolds while providing good radial support for the stenotic vessels. However, the interlaminar compounds at the metal interface have an essential impact on the mechanical properties of the bi-material interface, especially the cracking and delamination of the Mg matrix Zn coating vascular stent in the radially expanded process layer. Intermetallic compounds (IMCs) are commonly found in dual-layer composites, such as Mg/Zn composites and multi-layer structures. They are frequently overlooked in simulations aiming to predict mechanical properties. This paper analyses the interfacial failure processes and evolutionary mechanisms of interfacial fracture mechanics of a Mg/Zn interface with an intermetallic compound layer between coated Zn and Mg matrix metallic vascular stents. The simulation results show that the fracture mode in the Mg/Zn interface with an intermetallic compound involves typical ductile fracture under static tensile conditions. The dislocation line defects mainly occur on the side of the Mg, which induces the Mg/Zn interfacial crack to expand along the interface into the pure Mg. The stress intensity factor and the critical strain energy release rate decrease as the intermetallic compound layer's thickness gradually increases, indicating that the intensity of stress and the force of the crack extending and expanding along the crack tip are weakened. The presence of intermetallic compounds at the interface can significantly strengthen the mechanical properties of the material interface and alleviate the crack propagation between the interfaces. [ABSTRACT FROM AUTHOR]