Magnetic properties of the FCC and BCC phases of (MnFeCoNi)80Cu 20 − x Z x ( Z : Al, Ga) high-entropy alloys

In this work, the FCC-BCC phase transition in (MnFeCoNi)80Cu20−xZx (Z: Al, Ga) high entropy alloys were investigated on the basis of structural, magnetic, hardness and thermal expansion properties. It is found that the equiatomic MnFeCoNiCu alloy is FCC and exhibits mixed ferromagnetic/anti-ferromagnetic interactions with a Curie temperature, Tc, close to room temperature. However, the BCC structure emerges with increasing amount of Al (10 at%) and Ga (15 at%) with additional ferromagnetic interactions and associated Tcs. It is evidenced that in terms of the valence electron concentration and the average magnetic moment values, the investigated HEAs obey the Slater-Pauling rule in a region close to the Heusler alloys. Additionally, they may exhibit similar physical properties like Invar property with low thermal expansion coefficient with the 3d-transition metal-alloys having same valence electron concentration.