Mechanical memory and relaxation decoupling of metallic glasses in homogenous flow

Abstract

Due to the structural information submerged into the meta-stable disordered long-range structure, quantitative prediction of the time-dependent deformation of metallic glasses under mechanical stimuli is a challenging task. Specifically, the present understanding of relaxation behavior, particularly in relation to dynamic heterogeneity and the memory effect in metallic glasses during thermo-mechanical treatment, is yet to be totally understood. Here we study the correlation between the relaxation decoupling and mechanical memory effect in metallic glasses, manifested by non-monotonic variation of activation energy and dynamic heterogeneity during creep and stress relaxation. The strain evolution and energetic state show a memory effect in an aging (recovery)-and-creep procedure. The relaxation decoupling and mechanical memory effect originate from the competition between the formation of fast defects by stress and the transition towards slow defects and their annihilation. The strain evolution is dependent on total loading time and total recovery/aging time rather than their orders. Our results shed light on the deformation and history-dependent behaviors of metallic glasses.