High-entropy alloy: challenges and prospects

TLDR

High‑entropy alloys, composed of multiple principal elements, are a growing research focus in materials science, but their complex compositions raise fundamental challenges to conventional alloy theories. The authors critically review recent studies addressing fundamental issues of phase formation in high‑entropy alloys. The review examines recent research on phase‑formation mechanisms in HEAs and discusses their novel properties such as high specific strength, superior high‑temperature performance, exceptional cryogenic ductility, superparamagnetism, and superconductivity. The authors conclude that HEAs’ structural and functional potential make them promising for new applications, warranting further investigation.

Abstract

High-entropy alloys (HEAs) are presently of great research interest in materials science and engineering. Unlike conventional alloys, which contain one and rarely two base elements, HEAs comprise multiple principal elements, with the possible number of HEA compositions extending considerably more than conventional alloys. With the advent of HEAs, fundamental issues that challenge the proposed theories, models, and methods for conventional alloys also emerge. Here, we provide a critical review of the recent studies aiming to address the fundamental issues related to phase formation in HEAs. In addition, novel properties of HEAs are also discussed, such as their excellent specific strength, superior mechanical performance at high temperatures, exceptional ductility and fracture toughness at cryogenic temperatures, superparamagnetism, and superconductivity. Due to their considerable structural and functional potential as well as richness of design, HEAs are promising candidates for new applications, which warrants further studies.