Effect of valence electron concentration on stability of fcc or bcc phase in high entropy alloys

TLDR

Phase stability in high‑entropy alloys is poorly understood, yet predicting it from elemental properties would greatly aid alloy design. The study systematically investigates how the physicochemical and thermodynamic properties of alloying elements influence phase stability in HEAs. The authors analyzed the relationship between phase stability and the physicochemical/thermodynamic properties of alloying components in HEAs. Mixing enthalpy determines whether solid solutions or compounds form, while valence electron concentration clearly distinguishes fcc from bcc solid solutions, making VEC a crucial parameter for alloy design and mechanical behavior control.

Abstract

Phase stability is an important topic for high entropy alloys (HEAs), but the understanding to it is very limited. The capability to predict phase stability from fundamental properties of constituent elements would benefit the alloy design greatly. The relationship between phase stability and physicochemical/thermodynamic properties of alloying components in HEAs was studied systematically. The mixing enthalpy is found to be the key factor controlling the formation of solid solutions or compounds. The stability of fcc and bcc solid solutions is well delineated by the valance electron concentration (VEC). The revealing of the effect of the VEC on the phase stability is vitally important for alloy design and for controlling the mechanical behavior of HEAs.