Effect of non-ferromagnetic element content on magnetic properties of FeCoMnAlSi high entropy alloy

High-entropy alloys have attracted considerable attention due to their advantages such as versatility and customizable properties. The customizable properties in soft magnetic high-entropy alloys mainly come from non-ferromagnetic elements, but it is challenging to maintain good soft magnetic properties while increasing the proportion of non-ferromagnetic elements. In this study, the ratio of non-ferromagnetic elements is systematically adjusted in the FeCoMnAlSi high-entropy alloy to explore its influence on soft magnetic properties. The structure of the alloys transforms in a sequence of FCC + BCC → BCC → BCC + B2 as the proportion of non-ferromagnetic elements increases. The soft magnetic properties of the system are significantly influenced by non-ferromagnetic elements. The dependence of saturation magnetization (M_s) on the proportion of non-ferromagnetic elements exhibits an И-shaped pattern, while that of coercivity (H_c) follows a V-shaped trend. Notably, the alloy (Fe_4/5Co_1/5)₇₈(Mn_10/23Al_10/23Si_3/23)₂₂ exhibits an exceptionally high M_s of 189.12 emu·g⁻¹ and a low H_c of 1.9 Oe. Simulation calculations indicated that the enhancement in M_s results from a reduction in the antiferromagnetic coupling between Fe and Mn, coupled with an improved efficiency of the ferromagnetic transformation in Mn.