Search Results (2,229)

In a solid-state hydrogen storage tank, the storage medium is most often in the form of an intermetallic alloy powder. With each cycle of hydrogen absorption/desorption, the particles swell, move, fragment, and segregate. Understanding and modeling these phenomena are essential in order to guide engineers during the tank design process. However, there are little data in the literature on the mechanical behavior of powders for storage applications. This study focuses on the flowability and compression behavior of an intermetallic powder, with the aim of analyzing particle mobility in a confined environment as well as the transmission of forces to the tank walls. In order to represent the evolution of particle size through fragmentation during cycles, five ${\mathrm{T}\mathrm{i}\mathrm{F}\mathrm{e}}_{\left(1-\mathrm{x}\right)}{\mathrm{M}\mathrm{n}}_{\mathrm{x}}\left(\mathrm{x}\approx 0.1\right)$ powders, differing in their average particle size and polydispersity, are studied. Flowability tests on Granutools^® (Awans, Belgium) instruments show that behaviors differ. Fine-grained samples exhibit rheo-thickening behavior, while coarser samples are quasi-Newtonian. These tests highlight variations in cohesion and internal friction, particularly for polydisperse samples. Stepwise cyclic compression tests (in stages 0-10-20-30 kN) were performed to study the elastic response of the powder under confinement and its ability to transfer stresses to the walls. This work highlights the impact of particle size and polydispersity on stress transfer in a confined space. This work therefore presents the mechanical effects of changes in particle size and polydispersity during absorption/desorption cycles on the overall behavior of the powder storage bed, in terms of flowability, cohesion, and stress transmission, in order to better understand, in the long term, its impact on tank deformation. Full article

Functional materials based on LaCoSi and LaCuSi intermetallic compounds (IMC) were fabricated and tested in the electrocatalytic process of reducing nitrates to ammonia (NO₃RR). The method of arc melting in an argon atmosphere was used to synthesize the alloys. The synthesis process is described and analyzed in detail, and the difficulties and advantages are shown. It has been established that when using an LaCuSi-based IMC–alloy as an electrocatalyst, the reduction of nitrates is the predominant reaction. On the contrary, for the LaCoSi (IMC)–alloy electrocatalyst, NO₃RR and the hydrogen evolution reaction (HER) occur simultaneously. Full article

The study investigates the microstructure evolution in the stir zone produced by the friction stir processing (FSP) of a heat-treated microalloyed Al-Mn-Cu alloy in the area subjected to the highest temperature, strain, and strain rate. The samples were studied using electron microscopy and atom probe tomography (APT) to obtain structural and chemical information from the macro to the nano scale. FSP refines the dendritic Al-rich solid solution grains through dynamic recrystallisation in the range of a few micrometres. The primary intermetallic phases were dispersed to the particles in the 0.5–3 µm range and transformed mainly into a more stable τ₁-Al₂₉Mn₆Cu₄ phase. The fraction of dispersed particles after FSP increased due to the precipitation from the solid solution during cooling. The nanoscale quasicrystalline precipitates in the matrix, formed upon heat treatment, dissolved entirely during FSP, while the strong coarsening of the L1₂ precipitates occurred due to high temperatures in the stir zone. After FSP, the hardness of the stir zone was nearly identical for specimens in the as-cast and heat-treated conditions. Full article

Particle-reinforced aluminum matrix composite (AMC)/steel hybrid structures present considerable benefits for lightweight design and enhanced product performance. This article provides a systematic overview of research advances from 2003 to 2024 on laser welding of particle-reinforced AMCs to steel, with particular emphasis on the influence of laser welding parameters, shielding gas, and reinforcing particles on the mechanical properties of the welded joints. The mechanisms by which intermetallic compounds (IMCs) impair joint strength are thoroughly analyzed. Moreover, the effects of rare earth element additions on both mechanical properties and corrosion resistance of the joints are critically assessed, along with the coupling mechanism between rare earth elements and the reinforcement phase. Key insights from the literature reveal that regulating heat input can effectively suppress harmful interfacial reactions. Meanwhile, the synergistic incorporation of rare earth elements not only refines the grain structure and boosts mechanical strength, but also improves corrosion resistance through the formation of dense surface oxide films and grain boundary strengthening. This review underscores the innovative integration of interfacial reaction control with rare earth microalloying to achieve high-performance AMC/steel laser-welded joints—a distinct departure from prior studies that typically investigated these strategies separately. Full article

The brittleness of 18-karat purple gold originates from the AuAl₂ intermetallic compound. This study investigates the microstructural modification of the AuAl₂ intermetallic compound by adding silicon (Si) and cobalt (Co) and by rapid solidification in copper molds. The samples with alloy additions from a traditional investment casting were compared with copper mold casting for grain boundary characteristics using SEM, EBSD, and TEM. SEM micrographs showed a reduction in grain size of copper mold casting from approximately within 150–200 μm to within 12–20 μm. EBSD showed a narrow grain size distribution in the Si–Co-modified alloy than in the Si-modified alloy, using the copper mold casting technique. TEM observations show that grain boundaries were closely packed, with ~80 nm-sized voids. XRD confirmed that all alloys retained the AuAl₂ intermetallic phase, with peak broadening in the modified and fast-cooling samples indicating crystallographic refinement. These results confirm that Si-Co additions with a fast cooling rate effectively refine the microstructure of the AuAl₂ intermetallic compound, making the alloy less brittle while preserving the purple gold color. Full article

The persistent discharge of refractory toxic organic pollutants poses a severe threat to aquatic environmental safety, driving the urgent demand for high-efficiency water treatment technologies in environmental engineering. Fenton and Fenton-like oxidation processes have garnered extensive attention due to their robust oxidizing capacity and environmental benignity; however, traditional Fenton systems are constrained by inherent limitations, including a narrow applicable pH range, potential secondary pollution, and cumbersome catalyst recovery. To address these challenges, Fenton-like catalysts have evolved progressively from single-metal systems to multi-metal alloy configurations. This review systematically elaborates on the fundamental principles and technical bottlenecks of classical Fenton and Fenton-like reactions, while comprehensively summarizing the research progress of multi-metal alloy catalysts—encompassing binary alloys, multi-component alloys, and high-entropy alloys. Special emphasis is placed on dissecting the core mechanisms through which multi-metal alloys optimize redox cycles and enhance structural stability, leveraging intermetallic synergistic effects, unique electronic structures, and lattice distortion. Furthermore, this work synthesizes key performance enhancement strategies for such catalysts, including co-catalyst synergy, external field assistance, and supported composite modification. Ultimately, this review aims to provide a scientific foundation and technical reference for the rational design, development, and engineering application of high-performance Fenton-like catalysts in sustainable wastewater remediation. Full article

The present study investigates the dry sliding wear behaviour of pure Zn, Zn–3Mg, and Zn–3Mg–0.5Y biodegradable alloys using mass loss measurements, friction torque monitoring on an Amsler tribometer, and optical profilometry of wear tracks. The microstructure of the Zn–Mg–Y alloy exhibited an α-Zn matrix comprising Zn–Mg intermetallic constituents and dispersed Y-rich phases. Tribological testing at 20 N and 30 N revealed a marked enhancement in wear resistance for Zn–3Mg in comparison to pure Zn, attributable to matrix strengthening by intermetallic phases. Despite the stabilising effect of Y on the friction response, there was no consistent reduction in wear volume under higher loads. Surface investigations have revealed a multifaceted wear mechanism, characterised by a combination of abrasion, oxide tribolayer formation, and localised adhesion. The measured wear rates were found to fall within the range documented in the available literature concerning biodegradable Zn-based alloys, thereby confirming the experimental validity of the findings. In summary, Zn–3Mg exhibited the optimal equilibrium between friction stability and wear resistance under the examined dry sliding conditions. However, further research in physiological environments is necessary to evaluate its biomedical applicability. Full article

Liquid metal cathodes, particularly liquid cadmium (Cd), are widely used in molten salt electrorefining and pyrochemical reprocessing of spent nuclear fuel due to their high electrical conductivity, strong affinity for actinides, and favorable alloying characteristics. During electrorefining, reduced metal species enter the liquid Cd phase and may exist as dissolved atoms, liquid alloys, or intermetallic compounds, all of which significantly influence deposition behavior, separation selectivity, and cathode performance. Although numerous experimental and theoretical studies have investigated metal solubility, alloy formation, and diffusion in liquid Cd systems, the current understanding remains fragmented. Thermodynamic phase behavior and mass transport kinetics are often discussed separately, and reported diffusion data show considerable discrepancies owing to variations in experimental techniques and interpretations. In addition, the relationship between phase stability, diffusion mechanisms, and electrochemical conditions in practical electrorefining environments has not yet been systematically clarified. This review aims to present an integrated thermodynamic–kinetic perspective on the behavior of metals in liquid Cd cathodes. Recent progress in dissolution behavior, alloy phase formation, and diffusion-controlled transport processes is critically summarized. The differences in solubility and precipitation behavior of actinides, rare-earth elements, and selected transition metals are analyzed in relation to binary phase diagrams and thermodynamic stability. Furthermore, experimental methods for determining diffusion coefficients, including capillary techniques and electrochemical approaches, are comparatively evaluated. By correlating thermodynamic phase stability with diffusion-driven mass transport, this work provides a coherent framework for understanding metal behavior in liquid Cd cathodes and offers insights for optimizing molten salt electrorefining and advanced nuclear fuel cycle technologies. Full article

The application of microalloying technology has significantly improved the mechanical properties, oxidation resistance, and corrosion resistance of the Sn-9Zn-xAl-series solder. The effects of Al addition on microstructural evolution and service-related performance of the solders were systematically investigated using a combination of characterization techniques, including scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX), differential scanning calorimetry (DSC), tensile testing, spreading testing, thermogravimetry (TG), and potentiodynamic polarization measurements. Microstructural characterization reveals that an optimal content of Al reacts with the Sn-Zn matrix to form AlZnSn intermetallic compounds (IMCs), which effectively refines the Zn-rich precipitates and eutectic lamellar structure. Concomitantly, the formation of second-phase strengthening contributes to a significant enhancement in the tensile strength of the solder alloys. Specifically, the Sn-9Zn-0.8Al solder exhibits a tensile strength of 87 MPa, corresponding to a 37% increment compared to the base Sn-9Zn alloy, whereas the elongation is reduced to 14.1%. Moreover, the in situ-formed Al₂O₃ passive film provides effective protection for the solder matrix, inhibiting oxidation induced by oxygen atoms and corrosion caused by chlorine ions, thereby remarkably improving the oxidation and corrosion resistance of the alloy. Collectively, these findings demonstrate that Al microalloying can substantially enhance the strength, oxidation resistance, and corrosion resistance of Sn-9Zn solder; however, a trade-off between wettability and ductility needs to be carefully considered for practical applications. Full article

Friction stir-welding (FSW) is widely recognized as a modern solid-state technology used to join dissimilar materials by solid-state mechanical mixing. Such mechanical mixing can be exploited to fabricate in situ composite structures through solid-state deformation mechanisms. The present investigation highlights the microstructural evolution and mechanical properties of an in situ composite structure fabricated by FSW of aluminum (Al) to titanium (Ti) incorporating a thin Nickel (Ni) interlayer. A 0.1 mm thick Ni foil was placed across the full butt interface between 4 mm thick Al and Ti plates before friction stir-welding. Properties of the composite were investigated in detail, and the results revealed that fragmented Ti and Ni particles of different sizes were consolidated in the weld nugget. Al, on the other hand, exhibited substantial microstructural refinement and developed an equiaxed microstructure with random grain orientation, mixed grain boundaries and low micro-strain accumulation in the weld nugget. At the processing temperature, Al reacted with both Ti and Ni to form multiple intermetallic compounds. Tensile testing indicated that the tensile properties of the weld were close to those of the base aluminum. This retention of mechanical properties in spite of recrystallization is attributed to the following mechanisms: (1) Ti and Ni undergo severe deformation, forming fine particles with varying sizes and shapes; (2) at particle interfaces, diffusion and chemical reactions produce interlayers and intermetallic compounds; (3) these particles are consolidated within dynamically recrystallized Al, imparting composite characteristics to the weld nugget; and (4) the particles containing intermetallic compounds act as dispersoids in the Al matrix. Quantitatively, the weld retained 98% (104.2 ± 3.3 MPa) UTS and 90% (17.1 ± 1.2) ductility of base aluminum, demonstrating the effectiveness of the Ni interlayer approach in controlling brittle intermetallic formation. Full article

TC4/Al₃Ti metal–intermetallic laminated (MIL) composites were fabricated by the vacuum hot-pressing process at 650 °C. The microstructure characteristics, i.e., grain boundary distribution, crystallographic orientation and Kernel Average Misorientation (KAM) map, were analyzed using EBSD. Meanwhile, the distribution of local strain and the fracture behavior of TC4/Al₃Ti MIL composites during tensile process were determined by Digital Image Correlation (DIC) and in situ tensile experiments, respectively. Results show that the TC4/Al₃Ti interfaces are well bonded and exhibit a distinct wavy morphology. The obvious Kirkendall pores and centerline are observed within the central region of the Al₃Ti layer. The texture components of (10-10) <0001> and (11-20) <10-10> are predominant in the TC4 layers; (100) <001> and (110) <001> are observed in the Al₃Ti layer. Additionally, the average geometrically necessary dislocation (GNDs) density is 2.53 × 10¹⁴ m⁻² in the TC4 layer, whereas it is 1.74 × 10¹⁴ m⁻² in the Al₃Ti layer. In the tensile test, the fracture resistance of TC4/Al₃Ti MIL composites is significantly improved by the plastic deformation of the TC4 layers and the suppression of crack-tip instability. It is found that the extrinsic toughening mechanisms contain crack deflection, crack blunting, crack bridging, multiple cracking modes, and the plastic deformation of ductile TC4 layers in TC4/Al₃Ti MIL composites. The real-time observation technique may provide more complete insights into the relationship between fracture behavior and enhanced toughness. Full article

Four compositions of rapidly quenched ribbon brazing alloys based on Ag–Cu–Ti (Ag–26.5Cu–1.5Ti, Ag–25Cu–5Ti) and Ag–Cu–Zr (Ag–26.5Cu–1.5Zr, Ag–25Cu–5Zr) systems were produced. Initial ingots were synthesized by arc melting. Rapidly solidified ribbons, 50–100 μm thick, were then fabricated from homogenized ingots using a “Crystall-702” facility. A comparative analysis of the microstructure and phase composition of both the ingots and ribbons was conducted using scanning electron microscopy and X-ray diffraction. The analysis revealed the presence of Cu₄Ti and CuTi intermetallic compounds in the Ag–Cu–Ti alloys, and AgCu₄Zr and Zr₂Cu in the Ag–Cu–Zr alloys. Rapid quenching was found to produce metastable structures and significantly refine the intermetallic phases. Microhardness measurements of the ingot and ribbon states demonstrated a substantial influence of the processing route on the mechanical properties. The tensile strength of the ingots was also evaluated. The wetting angles of the rapidly quenched alloy melts on 99% Al₂O₃ (alumina) ceramic substrates under vacuum were determined. All produced ribbons, except for the Ag–26.5Cu–1.5Zr composition, demonstrated adequate wettability. Thus, these materials are considered promising for further research into heat-resistant metal–ceramic joints. Full article

Welding copper (Cu) and aluminum (Al) is highly demanded for lightweight and cost-effective manufacturing. However, it faces significant challenges. First, substantial differences in physical properties may lead to high residual stresses and distortion. Second, brittle intermetallic compounds (IMCs) readily form at the interface, severely compromising the joint’s mechanical properties and electrical conductivity. Third, the native oxide film on Al impedes effective wetting and bonding. Therefore, effective control over the interfacial microstructure of the welded joint is essential. This review provides a critical analysis and comparison of several typical welding techniques, including laser welding (LW), friction stir welding (FSW), ultrasonic welding (UW), brazing and soldering, and welding–brazing. These analyses focus on their process characteristics, joint microstructures, and corresponding formation mechanisms. Furthermore, this review synthesizes key strategies for enhancing joint quality, including process parameter optimization, introduction of functional interlayers, and external assistance, aimed at optimizing joint microstructure and minimizing defects. Based on the analysis, this work provides comparative insights into process selection and microstructure control, and highlights future directions: advancing novel methods such as magnetic pulse welding and transient liquid phase bonding; developing intelligent real-time process control to suppress brittle IMCs and associated defects; promoting sustainable practices and establishing standardized performance evaluation; and systematically investigating long-term reliability to support the industrial application of robust Cu/Al joints. Full article

This study investigates the influence of highly thermally conductive coatings on the combustion thresholds of a TC4 titanium alloy, aiming to address the flame-retardant protection requirements for titanium alloys. The findings reveal that, in terms of combustion thermodynamics, as the thickness of the copper coating increases from 100 μm to 300 μm, the critical ignition power rises by 125–170 W compared to the substrate (235 W). Additionally, the critical oxygen pressure increases by 0.21–0.51 MPa relative to the substrate (0.03 MPa), and the ignition temperature is elevated by 119–184 K above that of the substrate (848.80 K). This phenomenon is primarily due to the high thermal diffusivity of copper. Increased coating thickness further enhances heat dissipation, significantly suppressing the local heat accumulation rate and thereby improving the coating’s combustion resistance. In terms of combustion kinetics, under fixed experimental conditions, the copper coating extends the ignition delay time by 0.670 s and reduces the combustion propagation rate by approximately 21% compared to the substrate (26.772 mm/s). The post-combustion microstructural analysis indicates that during the reaction process, the copper coating forms a TiCu₂Al-type intermetallic compound (Ti_0.5Al_0.5)Cu. This structure exerts an “anchoring” effect on the substrate material, decreases the Ti/O reaction efficiency, and consequently achieves effective flame retardancy. These findings inform the subsequent design and optimization of copper-based abradable coatings with enhanced combustion resistance. Full article

This work investigates the structural evolution and electrocatalytic activity of the amorphous metal alloy Al₈₇Y₄Gd₁Ni₄Fe₄ during short-term annealing and its effect on the kinetics of the hydrogen evolution reaction (HER) in 1 M KOH. It is shown that a 5 min heat treatment at 647 ± 2 K initiates controlled nanocrystallisation with the formation of AlFe₂Ni, GdFe₂ and Al(X) (X = Gd, Ni, Y, Fe) phases, which are uniformly dispersed in the amorphous matrix. According to XRD, DSC and HRTEM data, it was established that the formation of intermetallic nanodomains leads to a decrease in charge transfer energy barriers and the appearance of additional active centres of H* adsorption. Electrochemical studies have shown an increase in cathode current density, an increase in i₀ by 2–3 orders of magnitude, and a decrease in R_ct after annealing, confirming the improvement in HER kinetics. Potentiostatic tests showed an increase in the volumetric hydrogen evolution rate from 35.1 to 106.0 mL/(g·min) during the first immersion and up to 217.9 mL/(g·min) during reuse. SEM/EDS analysis revealed surface reconstruction and Ni enrichment after HER, which contributes to the acceleration of the H* recombination stage. The synergy of the amorphous matrix and nanophases ensures high electrocatalytic activity and stability of the system, making annealed AMA a promising low-cost catalyst for alkaline hydrogen evolution. Full article