Short-range order in the CoCrFeMnNi high-entropy alloy from cluster expansion

We investigate the short-range order (SRO) and phase stability of the equiatomic CoCrFeMnNi high-entropy alloy using cluster expansion supplemented by an eigen-decomposition analysis of the SRO parameters. Our results reveal that the primary ordering behavior is determined by strong Cr–Cr repulsive interactions, complemented by attractive heteroatomic Cr–X pairs in the first nearest-neighbor shell. This chemical affinity is consistent with the emergence of ordered local environments and appears to be a major contributor to the primary order–disorder transition. At lower temperatures, the spectral SRO analysis suggests two additional lower-temperature instabilities: a collective ordering instability and an Fe-rich local clustering instability.