Physical metallurgy is a branch of materials science, which focuses on the relationship between composition, processing, crystal structure and microstructure, and physical and mechanical properties. The progress of physical metallurgy is over 100 years and the underlying principles are thought to become mature. However, the progress is based on the observations on conventional alloys. As compositions of HEAs are entirely different from that of conventional alloys, physical metallurgy principles might need modification for HEAs.
In this presentation, four core effects of HEAs, i.e. high entropy, sluggish diffusion, severe lattice distortion, and cocktail effects, are reviewed. Their influences on different aspects of physical metallurgy are emphasized with examples. Most importantly, this presentation points out that lots of future works are required to build suitable mechanisms and theories correlating composition, microstructure and properties for HEAs. Only these understandings make it possible to complete the physical metallurgy of the alloys world.