Microstructure and tribological properties of in-situ carbide/CoCrFeNiMn high entropy alloy composites synthesized by flake powder metallurgy

CoCrFeNiMn high entropy alloy (HEA) owns prominent strain hardening capacity and high tensile elongation but poor wear resistance. In present work, in-situ carbide/CoCrFeNiMn composites with excellent anti-wear properties were fabricated by a flake powder metallurgy route using graphene oxide (GO) and CoCrFeNiMn as original powders. As a result, the hard carbide phase, Cr7C3, is formed in the soft matrix via in-situ reaction at the GO/HEA interface, which leads to a dense distribution of small-sized Cr7C3 and strong interfacial bonding of the composites. With the addition of 5 wt% GO, the microhardness is improved by 66.7% and the macroscopic wear rate is decreased by 78.3% as compared with CoCrFeNiMn HEA. Increased nano-scratch resistance indicates that the dense distribution of hard Cr7C3 carbide and the strong Cr7C3-CoCrFeNiMn interfacial bonding play key roles to resist the plastic flow of the HEA matrix during friction and wear. This study may provide a pathway to improve the wear resistance of HEA for engineering applications.