Microstructure and Mechanical Properties of Equimolar CrFeCoNiMo High Entropy Alloy by MM/SPS Process

In this paper, microstructure and mechanical properties of equimolar CrFeCoNiMo high entropy alloy (HEA) prepared by mechanical milling (MM) and spark plasma sintering (SPS) process were investigated in detail. The initial and MM powders were sintered 1.8 ks at 1173 to 1373 K by using SPS apparatus. Microstructural observation of the powders and SPS compacts was achieved using scanning electron microscopy (SEM) / electron back scattered diffraction (EBSD). The SPS compact of the initial and MM powders consist of FCC, σ and μ phases. The grain size of the compacts of the MM powders is fine compared with that of the initial powders. The grain sizes of each phase increase with increasing the sintered temperature. The Vickers hardness of the MM powder compacts is higher than that of the initial powder compacts. The Vicker hardness of the compacts of initial and MM powders decreases with increasing the sintered temperature. It is revealed that the hardness of CrFeCoNiMo HEA is attributed to the grain size of each phase composed of the microstructure.