Microstructure, Tribological Behavior, and Strengthening Mechanisms of the Friction Interface Layer with Nanocrystalline Structure of Ni3Al Matrix Self-lubricating Composites

This work investigated the microstructure, tribological behavior and strengthening mechanisms of friction interface layer with nanocrystalline structure of graphene-reinforced Ni3Al matrix composites (GNMCs) synthesized using laser melting deposition. A dislocation density-based model was selected to analyze the mechanisms of the improvement in the wear resistance of the friction interface layer from initial wear stage to stable wear stage. Results show that GNMCs exhibit excellent antifriction and wear resistance in the stable wear stage due to the formation of friction interface layer with nanocrystalline structure. Grain boundary strengthening is the predominant strengthening mechanism of friction interface layer of GNMCs. Dislocations are blocked at grain boundaries to form complex dislocation barriers, further contributing to the high strength and wear resistance. The dislocation density-based model can be successfully used to predict the mechanical response of the friction interface layer subjected to the grain refinement during sliding friction process.