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The design and production of active, durable, and nonprecious electrocatalysts toward alkaline hydrogen oxidation and evolution reactions (HOR/HER) are extremely appealing for the implementation of hydrogen economy, but remain challenging. Here, we report a facile electric shock synthesis of an efficient, stable, and inexpensive NiCoCuMoW multi‐element alloy on Ni foam (NiCoCuMoW) as a bifunctional electrocatalyst for both HOR and HER. For the HOR, the current density of NiCoCuMoW could reach ∼11.2 mA cm–2 when the overpotential is 100 mV, higher than that for commercial Pt/C (∼7.2 mA cm–2) and control alloy samples with less elements, along with superior CO tolerance. Moreover, for the HER, the overpotential at 10 mA cm−2 for NiCoCuMoW is only 21 mV, along with a Tafel slope of low to 63.7 mV dec−1, rivaling the commercial Pt/C as well (35 mV and 109.7 mV dec−1). Density functional theory calculations indicate that alloying Ni, Co, Cu, Mo, and W can tune the electronic structure of individual metals and provide multiple active sites to optimize the hydrogen and hydroxyl intermediates adsorption, collaboratively resulting in enhanced electrocatalytic activity. A facile electric shock method is used to synthesize an efficient, stable, and inexpensive NiCoCuMoW bifunctional alloy electrocatalyst for both hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER). Combined experiments and theory calculations reveal that the multi‐component synergy of different elements and plentiful active sites render the NiCoCuMoW superior HOR/HER performance, rivaling the Pt/C benchmark and most reported nonprecious catalysts.

Energetic structural materials (ESMs) are a new type of structural materials with bearing and damage characteristics. In this work the microstructure, mechanical properties and energy release characteristics of multi-element Ti–Zr–Ta alloys with good casting performance were studied. The microstructure of the TixZrTa alloys gradually change from BCC + HCP to single BCC structure with the increase of Ti. While the Ti2ZryTa alloys was still uniform and single BCC structure with the increase of Zr. The evolution of microstructure and composition then greatly affect the mechanical properties and energy-release characteristics of Ti–Zr–Ta alloys. The synergistic effect of dual phase structure increases the fracture strain of TixZrTa (x = 0.2, 0.5) with the Ti content decreases, while the fracture strain of TixZrTa (x = 2.0, 3.0, 4.0) gradually increase with the Ti content increases caused by the annihilation of the obstacles for dislocation movement. And as Zr content increases, the fracture strain of Ti2ZryTa alloys decrease, then the oxidation reaction rate and fragmentation degree gradually increase. The higher oxidation rate and the lager exposed oxidation area jointly leads the higher releasing energy efficiency of TixZrTa alloys with low Ti content and Ti2ZryTa alloys with high Zr content.

High-entropy alloys (HEAs) are advanced materials characterized by their unique and complex compositions. Characterized by a mixture of five or more elements in roughly equal atomic ratios, these alloys diverge from traditional alloy formulations that typically focus on one or two principal elements. This innovation has paved the way for subsequent studies that have expanded our understanding of HEAs, highlighting the role of high mixing entropy in stabilizing fewer phases than expected by traditional phase prediction methods like Gibbs’s rule. In this review article, we trace the evolution of HEAs, discussing their synthesis, stability, and the influence of crystallographic structures on their properties. Additionally, we highlight the strength–ductility trade-off in HEAs and explore strategies to overcome this challenge. Moreover, we examine the diverse applications of HEAs in extreme conditions and their promise for future advancements in materials science.

Multi-element alloy doped diamond-like carbon (DLC) films were coated using sputtering with a (AlCrNbSiTiV) target. TEM and XRD results indicated DLC film had an amorphous compound feature incorporating polycrystalline phases around the face-centered cubic structure, which were embedded into the amorphous carbon matrix. The Raman spectra and mechanical characteristics of the DLC film sample were associated with concentration changes in the carbon and the multi-element alloy doped in the DLC films, which depended on the DC power. This investigation indicated that improved mechanical properties, including hardness and the elastic recovery rate, can be obtained from the multi-element alloy doped DLC film coated with proper DC sputtering power. These results demonstrated a proper DC power modifies the structure of multi-element alloy doped DLC film and improves its mechanical performance. This study should pave the way for the development of DLC film and elevate its application in various industries.

The promising potential of porous metallic materials for railway applications (e.g., conductive materials, materials for braking systems) is due to their unique combination of low density, high specific surface area, and high energy absorption capabilities. Porous multi-phase silicide coatings (FeSi, Si2CN4) provide a synergistic effect, doubling surface hardness and establishing a stable diffusion barrier. The article proposes a comprehensive approach to replacing materials for critical railway transport components, involving the development of a base material and a barrier coating. The use of widely available induction-melting components to produce a base material with superior mechanical properties is demonstrated. The material exhibits high static strength and hardness while maintaining acceptable impact toughness and ductility. To enhance wear, corrosion, and scale resistance, technology for forming a barrier layer via silicide coatings is proposed. The coating formation technology enables the regulation of porosity through the formation of nitrogen-containing phases. It is shown that pores can serve as “containers” for fillers that impart functional properties to the coatings (e.g., adjusting the friction coefficient or electrical conductivity). The new base material–barrier coating system can serve as a foundation for the sustainable production of critical rolling stock parts and other devices for railway transportation systems.

In this study, to meet the development and application requirements for high-strength and high-toughness energetic structural materials, a representative volume element of a TA15 matrix embedded with a TaZrNb sphere was designed and fabricated via diffusion bonding. The mechanisms of the microstructural evolution of the TaZrNb/TA15 interface were investigated via SEM, EBSD, EDS, and XRD. Interface mechanical property tests and in-situ tensile tests were conducted on the sphere-containing structure, and an equivalent tensile-strength model was established for the structure. The results revealed that the TA15 titanium alloy and joint had high density and no pores or cracks. The thickness of the planar joint was approximately 50–60 μm. The average tensile and shear strengths were 767 MPa and 608 MPa, respectively. The thickness of the spherical joint was approximately 60 μm. The Zr and Nb elements in the joint diffused uniformly and formed strong bonds with Ti without forming intermetallic compounds. The interface exhibited submicron grain refinement and a concave–convex interlocking structure. The tensile fracture surface primarily exhibited intergranular fracture combined with some transgranular fracture, which constituted a quasi-brittle fracture mode. The shear fracture surface exhibited brittle fracture with regular arrangements of furrows. Internal fracture occurred along the spherical interface, as revealed by advanced in-situ X-ray microcomputed tomography. The experimental results agreed well with the theoretical predictions, indicating that the high-strength interface contributes to the overall strength and toughness of the sphere-containing structure. [Display omitted] •High-strength mechanical properties of the interface of the TA15/TaZrNb MEA composite fabricated via diffusion bonding.•Investigation on the fracture mechanisms of the RVE embedded with a sphere by in-situ μCT tensile tests.•A tensile-strength equivalent model for the RVE embedded with a sphere is established.•The concave–convex interlocking structure at the interface plays a crucial role in resisting failure.

Improving the toughness of diamond composites has become an industrial demand. In this work, Co50Ni40Fe10 multi-element alloy was designed as binder for diamond-based composites prepared by high temperature and high pressure (HTHP). Two methods of mixing-sintering and infiltration-sintering were used to prepare diamond-based composites with different diamond contents. The phase diagrams of Co-C and Co50Ni40Fe10-C at 6 GPa were calculated by Thermo-Calc. The results show that Co50Ni40Fe10 multi-element alloy promotes the sintering of diamond powder than element Co. The transverse rupture strength (TRS) of sintered diamond with Co50Ni40Fe10 (Co50Ni40Fe10-75 vol% diamond) is higher than that of Co-Comp (Co-75 vol% diamond). The TRS of polycrystalline diamond (PCD) with Co50Ni40Fe10 alloy binder is up to 1360.3 MPa, which is 19.2% higher than Co-PCD. Compared with Co, using Co50Ni40Fe10 as binder results in a less metal residue in PCD, while the metal cluster area is smaller and the metal distribution is more uniform.

The mechanical behavior and microstructural evolution of a BCC‐phase NbTaTiV refractory multi‐principal element alloy (RMPEA) is studied over a wide range of strain rates (10−3 to 103 s−1) and temperatures (room temperature to 850 °C). The mechanical property of present RMPEA shows less strain‐rate dependence and strong resistance to softening at high temperatures. Under high strain‐rate loading, the formation of thin type‐I twins is observed, which could lead to an increase in strain‐hardening rates. However, this hardening mechanism competes with adiabatic heating effects, resulting in the deterrence of strain‐hardening behaviors. In contrast, substantial strain‐hardening occurs at cryogenic temperatures due to the formation of twins, which act as stronger barriers to dislocation motion and interact with each other. To further understand the different strain‐hardening behaviors, density functional theory (DFT) calculations predict relatively low stacking fault energies and high twinning stress for the NbTaTiV RMPEA. Exceptional mechanical stability of refractory multi‐principal element alloy (RMPEA) across various strain‐rates and temperature is studied through multiscale experiments coupled with theoretical calculations. This stability originates from competition between twinning and adiabatic heating during dynamic deformation, contributed from severe lattice distortion and edge dislocation strengthening. However, cryogenic testing still shows pronounced strain hardening from abundant twins.

Multi-elements alloy with good thermal stability is expected to serve as the superheater tube material of ultra-supercritical boiler and may suffer from hot corrosion under the coal-fired atmosphere. In this study, the corrosion resistance behavior of multi-elements alloy CoCrFeNiTi0.5 coated with alkali metal sulfates at 750°C is investigated systematically. The results showed the corrosion kinetics curves of the alloy followed a parabolic growth rate. The corrosion products, which consisted of volatile Na (CrO4) (SO4), (Fe,Ni) xSy, Cr/Ti oxide as well as compound oxides with spinel structure AB2O4, were found in the oxide scale and internal attack zone of the alloy. The oxide layer had good adhesion with the matrix at the beginning of corrosion. Prolonging corrosion time, the oxide layer in thickness increased and became loose as well as porous. The micro-pores generated in the interface between the oxide scale and matrix with the occurrence of the internal oxidation and internal sulfidation. In a word, the corrosion resistance behavior of multi-elements alloy CoCrFeNiTi0.5 at 750°C can be attributed to the formation of the protective oxide layers and to the basic fluxing in molten Na4SO4 induced by low melting point eutectic.

The emergence of multi‐principal element alloys (MPEAs) heralds a transformative shift in the design of high‐performance alloys. Their ingrained chemical complexities endow them with exceptional mechanical and functional properties, along with unparalleled microscopic plastic mechanisms, sparking widespread research interest within and beyond the metallurgy community. In this overview, a unique yet prevalent mechanistic process in the renowned FeMnCoCrNi‐based MPEAs is focused on: the dynamic bidirectional phase transformation involving the forward transformation from a face‐centered‐cubic (FCC) matrix into a hexagonal‐close‐packed (HCP) phase and the reverse HCP‐to‐FCC transformation. The light is shed on the fundamental physical mechanisms and atomistic pathways of this intriguing dual‐phase transformation. The paramount material parameter of intrinsic negative stacking fault energy in MPEAs and the crucial external factors c, furnishing thermodynamic, and kinetic impetus to trigger bidirectional transformation‐induced plasticity (B‐TRIP) mechanisms， are thorougly devled into. Furthermore, the profound significance of the distinct B‐TRIP behavior in shaping mechanical properties and creating specialized microstructures c to harness superior material characteristics is underscored. Additionally, critical insights are offered into key challenges and future striving directions for comprehensively advancing the B‐TRIP mechanism and the mechanistic design of next‐generation high‐performing MPEAs. The emergence of multi‐principal element alloys (MPEAs) signifies a transformative breakthrough in high‐performance alloy design. This review explores the unique bidirectional phase transformation in MPEAs, shedding light on fundamental mechanisms, intrinsic and external factors driving this mechanistic process. It underscores its profound significance in shaping mechanical properties and microstructures, offering critical insights into challenges and future directions for advancing MPEAs.