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

TL;DR

This study investigates how magnetism influences atomic short-range order in medium- and high-entropy alloys using first-principles calculations, revealing that magnetic treatment significantly affects predicted atomic arrangements and their properties.

Contribution

It demonstrates the importance of considering magnetic states in modeling multicomponent alloys, showing how magnetism alters atomic order predictions and suggesting potential for property tuning via magnetic fields.

Findings

Magnetic treatment changes atomic order from L1_2 to MoPt2 in CrCoNi.

Atomic correlations are strengthened in magnetically ordered states.

Magnetic effects are crucial for accurate modeling of multicomponent alloys.

Abstract

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 modelling. We perform two sets of linear-response calculations: one in which the paramagnetic state is modelled within the disordered local moment picture, and one in which systems are modelled in a magnetically ordered state, which is ferrimagnetic for the alloys considered in this work. We show that the treatment of magnetism can have significant impact both on the predicted temperature of atomic ordering and also the nature of atomic order itself. In CrCoNi, we find that the nature of atomic order changes from being $\mathrm{L}1_2$-like when modelled in the paramagnetic state to MoPt$_2$-like when modelled assuming the system has magnetically ordered. In CrFeCoNi, atomic correlations between Fe and the 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 modelling multicomponent alloys containing mid- to late-$3d$ elements. Further, 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.