Microstructures and properties of CoCrCuFeNiMox high-entropy alloys fabricated by mechanical alloying and spark plasma sintering

CoCrCuFeNiMox (x values in molar ratio, x= 0, 0.2, 0.4 and 0.8) high-entropy alloys were prepared by mechanical alloying and spark plasma sintering method. The effects of Mo addition on microstructure and mechanical properties were investigated. The X-ray diffraction (XRD) result showed that the addition of Mo into CoCrCuFeNi high-entropy alloy (HEA) changed the original phase constitution from FCC to FCC + sigma + mu and the peak intensity of (1 1 1) shifted to the left and decreased steadily. The field emission scanning electron microscope confirmed that the Cu-rich second FCC phase disappeared and the sigma phase with a tetragonal structure expanded as the Mo content was increased. Additionally, a high density of dimple-like features were seen in CoCrCuFeNi HEA while typical quasi-cleavage facets could be observed from the fracture surfaces of the HEAs with the addition of Mo. The Mo0.8 alloy showed a good wear resistant and appropriate strength with fracture strain 22.70%, fraction coefficient 0.65, hardness 530HV and compressive strength 1448MPa.