Light-weight refractory high-entropy alloys: A comprehensive review

In recent years, high-entropy alloys (HEAs) have become a research hotspot in materials community, and great progress has been made in exploring various high-performance HEAs. As a special class, the light-weight refractory high-entropy alloys (RHEAs) own both excellent high-temperature comprehensive properties and low density and have accordingly attracted more and more attention. In this paper, we presented a comprehensive review of the recent progress and status in light-weight RHEAs. Based on an exhausting search of the literature reports, one strategy in terms of phase numbers after preparation was first proposed to classify the light-weight RHEAs into three categories. Then, the status on the fundamental thermodynamic and thermophysical data/databases, computational approaches for alloy designing, and preparation/fabrication techniques of light-weight RHEAs was introduced one after another. After that, the progress on mechanical properties and oxidation/corrosion/wear behaviors of light-weight RHEAs at room and high temperatures was summarized. Finally, the conclusions of this review were drawn. By pointing out the shortcomings of the current research, the follow-up development directions in the field of light-weight RHEAs were also given.