Effect of Element Cobalt on Microstructure and Properties of AlFeCuCrNi High Entropy Alloys

AlFeCuCrNiCox(x=0, 0.5, 1.0) high entropy alloys were prepared by vacuum arc furnace. The microstructure and phase structure change of AlFeCuCrNi alloys after addition of element cobalt were investigated by OM, SEM, EMP, XRD and TEM. And hardness, thermal stability and corrosion resistance of these alloys were also studied. The results show the microstructure of AlFeCuCrNiCox alloys was typically dendritic structure, the phases of these alloys consisted of simple face-centered cubic (FCC) and body-centered cubic (BCC), and adding of element cobalt reduced the lattice constants both of FCC and BCC. Compositions segregation existed in all alloys, and addition of element cobalt promoted segregation of element copper and homogenization of all the other elements. The hardness and corrosion resistance of the alloys were increased after addition of element cobalt and all alloys possessed good thermal stability.