Effect of minor B addition on microstructure and properties of AlCoCrFeNi multi-compenent alloy

The influences of slight amount of B element on the microstructure and properties of AlCoCrFeNiBx high entropy alloys (x = 0, 0.01,…, 0.09 and 0.1, mole fraction) were investigated. The AlCoCrFeNi high entropy alloy exhibits equiaxed grain structures with obvious composition segregation. However, with the addition of B element, the alloys exhibit dendrite structures. Inside the dendrites, spinodal decomposition structure can be clearly observed. With the addition of B element, the crystal structures change from (B2 + BCC) to (B2 + BCC + FCC) structures, and the hardness firstly increases from HV 486.7 to HV 502.4, then declines to HV 460.7 (x ≥ 0.02). The compressive fracture strength firstly shows a trend of increasing, and then declining (x ≥ 0.08). The coercive forces and the specific saturation magnetizations of the alloys decrease as B addition contents increase, the decreasing coercive forces show a better soft magnetic behavior.