Exploring Nano-Scale Scratching Induced Tribological Behavior of Graphene Engineered AlCoCrFeNi High-Entropy Alloy

Motivated by the recent discoveries concerning the exceptional surface engineering capabilities offered by high-entropy alloys (HEAs), this article investigates the tribological behavior of pristine and graphene nano-engineered Al_xCoCrFeNi HEA. The atomic-scale scratching is performed for different configurations of HEA in a molecular dynamics environment, wherein, at first, aluminum (Al) (x = 0.1, 0.3, and 0.5) concentration-dependent wear behavior of HEA configurations is compared. It is observed that with the increase in Al concentration, the normal and tangential forces, friction coefficients, and wear-rates were significantly reduced, due to the increased plastic deformation and phase transformation. Graphene-engineered HEA surfaces are perceived in two different ways, in the presented investigation: first, the graphene coating is applied directly over the HEA surface, and second, the graphene layers are embedded at a certain depth below the target surface. It is observed that graphene-engineered HEA surfaces exhibit exceptional performance against nano-scratching, wherein, the distribution and height of surface morphology (pile-ups) have seen significant improvement and elastic recovery, especially in the cases of graphene coating over the surface. The findings obtained from this study will be extremely helpful in bringing the bottom-up multi-scale design route for graphene-engineered HEA surfaces to reality. This will enable the development of a novel class of functionally engineered surfaces with enhanced wear and scratch resistance.