Phase Stabilities of High Entropy Alloys

Abstract

High entropy alloys exhibit a composition design route that different from conventional alloys. However, whether the high configurational entropy is the key factor that stabilizes the room temperature single phase solid solution is still under debate. Here we use a perturbation model to evaluate their phase stabilities. According to the calculation results of 7085 alloys, it clearly indicates that a stable single phase is rare when constituent elements increase. The effect of increased entropy cannot balance the fast-increased driving force for the formation of intermetallics. Although it is not favored by thermodynamics, the frequently observed room temperature single-phase solid solutions can still form due to dynamic effect, which from the other side, provides a method to tune the microstructure and therefore the mechanical properties.