Intermetallic phase prediction in cobalt-free high-entropy alloys

Cobalt-free high-entropy alloys (HEAs) are promising structural materials for nuclear reactor systems due to their excellent properties under high doses of radiation. The extremely high hardness and brittleness of the intermetallic (IM) phase in HEAs have a significant effect on their performance. Consequently, the importance of comprehending the stability of the IM phases is becoming increasingly evident. In this study, the formation rules of IM phases in Co-free HEAs were proposed based on calculations of widely used semi-empirical parameters. Both Co-free refractory HEAs (RHEAs) and regular HEAs that mainly contain 3d transition metals were considered. The semi-empirical parameters include electronegativity difference ( ΔX ), valence electron concentration ( VEC ), enthalpy of mixing ( ΔH mix ) and atomic size difference ( δ ). The proposed IM phase formation rules were verified by the novel V 10 Cr 25 Fe 25 Mn 5 Ni 35 alloy. The ΔH mix - δ map was found to be a critical criterion for predicting the IM phase stability in both RHEAs and regular HEAs. The findings offer a practical approach to efficiently design new Co-free HEA compositions using semi-empirical parameters to predict IM phase stability. The composition range that favors IM formation can be avoided, thus streamlining the development of Co-free HEAs with targeted properties. • Δ X , VEC , Δ H mix and δ were calculated to predict the IM phase stability in cobalt-free HEAs. • The Δ H mix - δ map was found to be a critical criterion for predicting the IM phase stability in both RHEAs and regular HEAs. • The VEC - Δ X map is only efficient for determining the IM phase stability in regular HEAs. • A new IM-free V 10 Cr 25 Fe 25 Mn 5 Ni 35 alloy was prepared using arc melting to verify the proposed rules.