Simulations of Wear-Induced Microstructural Evolution in Nanocrystalline Aluminum

Abstract

Friction, wear resistance, and microstructural evolution of nanocrystalline (NC) aluminum during sliding were investigated using molecular dynamics (MD) simulations. The effect of Zr dopants and twinning has also been explored and it was found that doped NC Al sample and twinned NC Al sample exhibited better wear resistance and smaller friction force than pure NC Al sample. This trend was found to be correlated with higher hardness and higher strength of the doped NC Al sample and twinned NC Al sample. More grain growth in pure samples was found after wear, as compared with doped samples and twinned samples. We have determined the mechanisms of grain growth in NC Al and the main mechanism is grain boundary (GB) migration induced by emission of dislocations. Additional grain growth mechanisms found in the pure NC Al samples are disconnection-mediated GB migration and a so-called dissociation of low-angle GBs. Dislocation emission and GB migration were suppressed in both doped and twinned samples.