Lightweight high entropy alloys (LWHEAs), characterized by their low density, exceptional mechanical properties, and superior corrosion resistance, have gained significant attention in materials science. These alloys exhibit promising potential for applications in cutting-edge fields such as aerospace, automotive manufacturing, and energy storage. This paper provides a comprehensive review of recent advancements in LWHEAs research, with a focus on density-based classification methods, distinctive crystal structures, mechanical performance at ambient and elevated temperatures, complex deformation mechanisms, and excellent oxidation resistance. Additionally, the paper explores the diverse applications of LWHEAs in structural, functional, and energy-related materials. Key challenges in current research are highlighted, particularly concerning composition design and performance stability. Finally, the paper outlines future research directions, emphasizing the integration of theoretical modeling, experimental studies, and practical applications to drive technological innovation and facilitate the widespread engineering applications of LWHEAs.

The uniformity of the flow structure of the extruded copper bars has a significant impact on the mechanical and electrical conductivity properties of the material. A finite element simulation was conducted on the continuous equal-channel angular extrusion (C-ECAP)—extended extrusion process of pure copper. The material rheology during the deformation process was studied through experiments, and the variation laws of strain hardening and mechanical anisotropy were analyzed. The results show that the ultra-fine grain structure formed by C-ECAP can effectively suppress the turbulence of the material in the expansion zone and form a polycrystalline structure in the retarding zone. The texture type in the expansion zone is mainly {110}<112> brass texture and {110}<110> Goss texture; annealing twins and {001}<100> cubic weaves appear in the central region; and {110}<100> Goss texture and {110}<111> texture appear in the extrusion region. After deformation, the grain size of the copper bars gradually increases from the center to the periphery, the hardness of the copper busbar decreases first and then slowly increases along the extrusion direction, and the electrical conductivity continues to increase. The texture features, strain state, and expansion chamber structure are the main reasons for the non-uniform flow and anisotropy of the material.

In solid-state metal additive manufacturing, oxide removal is crucial for high-quality bonding, yet its impact remains unclear. In the article, the influence of oxides on the bonding interface by using cold spray additive manufacturing and leveraging diverse deformation mechanisms of high-entropy alloys is revealed. Advanced microstructure characterization shows that oxide fragmentation drives grain refinement via lattice rotation and substructure formation. As grain refinement progresses, oxide fragmentation increases metal-to-metal contact, promoting metallurgical bonding. These findings offer deep insights into the role of native oxides at the bonding interface and provide guidance for optimizing bond quality in solid-state additive manufacturing.

Electrochemical carbon dioxide reduction reaction (CO2RR) represents an electrochemical process that efficiently converts CO2 into value-added products, which hold significant environmental and social importance. Bismuth-based catalysts have emerged as the primary focus in electrocatalytic research for CO2 conversion into formic acid, owing to their exceptional catalytic performance and selectivity. By strategically doping heterogeneous atoms, the catalytic activity and stability of bismuth-based catalysts can be significantly improved. However, research in this field is still in its infancy, with relatively few comprehensive review articles available. Herein, we present a comprehensive review of the progress in heteroatom-doped bismuth-based catalysts for CO2RR toward formic acid production. Initially, this review outlines the market application prospects of bismuth-based catalysts, the reduction reaction mechanisms, and various modification methods. Furthermore, it systematically summarizes the latest advancements in heteroatom-doped bismuth-based catalysts, including non-metal atom-doped bismuth (such as S, F, and Te) and metal atom-doped bismuth (such as Cu, Co, and Sn). Finally, the review explores the future prospects and challenges associated with the development of heterogeneous atom-doped Bi-based catalysts. This review provides deeper insights into accelerating the technologies of CO2RR to value-added formic acid formation using Bi-based catalysts.