Enhanced hardness and magnetic properties of a CoCrCuFeNi high-entropy alloy under gradient magnetic fields

The mechanism of the influence of the gradient magnetic field on the dual FCC phase system was revealed using CoCrCuFeNi high-entropy alloy. Applying 75 T²/m GMF, the grain size of the alloy was refined from 58 μm to 39 μm, the proportion of Cu-lean FCC₁ phase increased from 77.2 % to 97.5 %, and a regular orientation was formed. Such microstructure and phase transform have divergent effects on mechanical and magnetic properties. The hardness of CoCrCuFeNi high-entropy alloy increased from 305 HV to 389 HV, the increase in saturation magnetization was attributed to the dominance of the regularly oriented phase structure and the high concentration of ferromagnetic elements, and the grain refinement led to an increase in grain boundary density, which slightly increased the coercivity. This work provides ideas for analyzing the mechanical and magnetic evolution of high-entropy alloys caused by complex changes in microstructure and multiphases.