Soft Magnetic and Mechanical Properties of FeNiCoSi<sub>0.25</sub>Al<sub>x</sub> (x = 0–1) High Entropy Alloys Prepared by Arc Melting

In this work, the effect of Al addition on the FeNiCoSi0.25Alx (x = 0, 0.25, 0.5, 0.75 and 1.0 mole) high entropy alloys prepared by arc melting route was investigated. The results show that the increase of Al content led to the change in phase structure of the high entropy alloys, from mainly FCC + minor Ni3Si to FCC+BCC and BCC phases, and resulted in various mechanical- and magnetic-properties of as-received alloys. The element mapping and SEM-EDS analysis results showed that the BCC phases contain two types of structure, BCC and B2 phase in which the B2 phase is rich in Ni and Al whilst BCC is enriched with Fe and Si. The Vickers hardness was enhanced with the increase of Al content. Maximum Vickers hardness was reached at 621.9 HV10 for FeNiCoSi0.25Al alloy containing the BCC and B2 phases. The obtained FeNiCoSi0.25Al0.5 high entropy alloys exhibit highest magnetic saturation of 114.1 Am2/kg and a low coercivity of 697 A/m, which, obviously indicate that these high entropy alloys need further investigations towards various applications, such as the soft magnetic materials.