Prediction of Face-Centered Cubic Single-Phase Formation for Non-Equiatomic Cr–Mn–Fe–Co–Ni High-Entropy Alloys Using Valence Electron Concentration and Mean-Square Atomic Displacement

We have investigated the face-centered cubic (FCC) single-phase formability of non-equiatomic Cr–Mn–Fe–Co–Ni HEAs as well as equiatomic derivative medium/high-entropy alloys (M/HEAs) considering their valence electron concentration (VEC) and mean-square atomic displacement (MSAD). While VEC remains the most decisive parameter to predict phase formation, MSAD can be a complementary parameter that modifies the VEC boundary. Multiplicity of constituent elements was beneficial to accommodate a larger MSAD, which resulted in a downward shift of the VEC boundary for the FCC single phase. This offers information about the correlations between the phase formation preference, VEC, and MSAD of M/HEAs with various compositions.