Atomistic investigation of aging and rejuvenation in CuZr metallic glass under cyclic loading

Abstract

The structural evolution and mechanical response of CuZr metallic glass (MG) under cyclic loading are investigated by molecular dynamics simulations. Either aging or rejuvenation was observed in the MG under cyclic loading with different cyclic strain amplitudes. Aging is more remarkable in the surface, while rejuvenation is correlated with the nucleation and development of shear transformation zone in the bulk of MG. The MG models with more structural heterogeneity were prepared by increasing the cooling rate during cooling process to exhibit larger degrees of structural evolution and aging during cyclic loading. While the fraction of ordered coordination polyhedron increases monotonically with increasing Cu content, the degree of aging during cyclic loading is not significantly impacted by Cu content. The glass-forming ability is the intrinsic character that governs the change in energy state and structural evolution of MG under cyclic loading. The critical cyclic strain amplitude for the transition from aging to rejuvenation is closely related to the initial structure of MG.