Interplay between magnetism and short-range order in medium- and high-entropy alloys: CrCoNi, CrFeCoNi, and CrMnFeCoNi

The impact of magnetism on predicted atomic short-range order in three medium-and high-entropy alloys is studied using a first-principles all-electron Landau-type linear-response theory, coupled with lattice-based atomistic modeling. We perform two sets of linear-response calculations: One in which the paramagnetic state is modeled within the disordered local moment picture, and one in which systems are modeled in a magnetically ordered state, which is ferrimagnetic for the alloys considered in this paper. We show that the treatment of magnetism can have a significant impact both on the predicted temperature of atomic ordering and the nature of atomic order itself. In CrCoNi, we find that the nature of atomic order changes from being L1(2)-like when modeled in the paramagnetic state to MoPt2-like when modeled assuming the system has magnetically ordered. In CrFeCoNi, atomic correlations between Fe and other elements present are dramatically strengthened when we switch from treating the system as magnetically disordered to magnetically ordered. Our results show it is necessary to consider the magnetic state when modeling multicomponent alloys containing mid-to late-3d elements. Furthermore, we suggest that there may be high-entropy alloy compositions containing 3d transition metals that will exhibit specific atomic short-range order when thermally treated in an applied magnetic field. This has the potential to provide a route for tuning physical and mechanical properties in this class of materials.