The deformation mechanism of graphene nanosheets embedded in high-entropy alloy upon sliding

Serving as an outstanding solid lubricant, the graphene can effectively reduce friction and improve wear-resistance of composites, which are pursued by CoCrFeMnNi high entropy alloy (HEA) with excellent strain hardening capacity and tensile ductility but poor wear resistance. However, the research on the lubrication effects of graphene so far has been mostly restricted to the idealized infinite flat models, missing the effects of morphology evolution and graphene-dislocation interactions, which are highly influencing the friction induced deformation. In this paper, molecular dynamics simulations were performed to investigate the nanoscratching response of HEA/graphene composites with finite graphene nanosheet that are more conformed to the real experiments. Upon sliding, the subsurface damage was diminished by the introduction of graphene nanosheet regardless of sheet size and embedding depth, leading to enhanced wear resistance. The mechanism transition from dislocation-graphene interactions to graphene morphology dominated was revealed with decreasing the embedding depth of graphene nanosheet. These findings may contribute to the design of HEA/graphene composites toward better mechanical and tribological properties.