Atomic Short-Range Order and Phase Stability of the Cantor-Wu Medium- and High-Entropy Alloys

Following on from the earlier chapters on refractory high-entropy alloys, in which magnetism played no role, we now move on to studying alloys containing magnetic elements. Namely, we study the prototypical family of face centred cubic high-entropy alloys, the Cantor alloy (CrMnFeCoNi) and its derivatives, collectively referred to as the Cantor-Wu alloys. We study an indicative series of the Cantor-Wu alloys: NiCo, NiCoCr, NiCoFeCr, and NiCoFeMnCr. We find that atom-atom effective pair interactions are not approximated well either as pseudobinary or restricted to nearest-neighbour distance. Our computed order-disorder transition temperatures are low, consistent with experimental observations.We find that atomic ordering is dominated by correlations between Ni, Co, and Cr, while Fe and Mn interact weakly. Our linear-response analysis suggests L1 \(_2\) orderings in CrCoNi, CrFeCoNi, and CrMnFeCoNi which are all driven primarily by Cr atoms moving to one sublattice. Further atomistic modelling suggests that there is no true single-phase low-temperature ground state for these multicomponent systems. Instead, the single-phase solid solution is kept stable to low temperatures by the large configurational entropy and the Fe, Mn dilution effects.