Cooperative regulation of mechanical properties and magnetoresistance effect in high-entropy alloys by spinodal decomposition

Abstract

Adjusting the phase composition of high-entropy alloys is an effective approach to change its mechanical and magnetic properties. In this study, FeCoNiCr high-entropy alloys with Al addition (AlxFeCoNiCr; x = 0.0, 0.25, 0.5, 0.75, 1.0, 1.25, 1.75) were prepared by argon arc melting to obtain a special spinodal decomposition structure. There precipitated body-centered cubic (BCC) phase in the face-centered cubic (FCC) phase matrix for the samples with Al (x = 0.25, 0.5, 0.75) addition. Furthermore, the increase in the Al content (x = 1.0, 1.25, 1.75) transformed the alloy into a BCC phase, and resulted in a spinodal decomposition in the alloy. This spinodal decomposition created a low-misfit coherent nanostructure combining the enriching AlNiCo ordered B2 matrix with enriching Fe–Cr BCC disordered nanoprecipitates. The difference in the distribution of chemical elements of the two phases leads to different magnetic properties and induces the magnetoresistance (MR) effect. This provides a pathway for the design of advanced functional high-entropy alloys.