Elemental synergistic effect in CoxCrCuFeMnNi high-entropy alloys and its influence on phase and magnetic properties

CoxCrCuFeMnNi (x = 0, 0.5, 1.0, 1.5, 2.0 mol, named as Co0, Co0.5, Co1.0, Co1.5, and Co2.0, respectively) high-entropy alloys (HEAs) were prepared by powder metallurgy. The phase formation, elemental synergistic effect, and magnetic properties of HEAs were studied. The elemental synergistic effect on the magnetic properties was also discussed. Co0 alloy comprised the FCC1 main phase, FCC2 secondary phase, and minor ρ phase, whereas other alloys comprised the FCC2 main phase and FCC1 secondary phase. When Crequiv>1.22Coequiv+16.4 was satisfied, a BCC main phase + FCC secondary phase or BCC phase structure easily formed in the alloys. When Crequiv≤1.22Coequiv+16.4 was satisfied, an FCC main phase + BCC secondary phase or FCC phase structure easily formed. The saturation magnetization (Ms) and coercive force (Hc) of Co0 alloy were 0.8 emu/g and 9 Oe, respectively. With increased Co content, Ms increased and Hc changed irregularly. When the Co content reached 2.0 mol, Ms increased to 4.5 emu/g and Hc decreased to 7 Oe. The increase in Coequiv increased the Ms, but Crequiv had little influence on it. Only at 15%–20% Crequiv did Hc decrease with increased Coequiv. Conversely, in other cases, the alloy's Hc cannot be effectively reduced by adjusting Coequiv and Crequiv.