Atomistic investigation of modulating structural heterogeneities to achieve strength-ductility synergy in metallic glasses

Abstract

Structural heterogeneities, i.e., spatial fluctuations of free volume, are of vital importance to the plasticity of irradiation-rejuvenated metallic glasses (MGs), but the mechanisms on how they affect the irreversible deformation and strength remain poorly understood. To address this issue, with the help of atomistic simulations, we systematically investigate the effect of structural heterogeneities on the mechanical behavior of tailored heterogenous MGs with uniformly distributed rejuvenated phases from several critical aspects such as pattern distribution, volume fraction and size effect. The results revealed that the periodically arranged soft rejuvenated phases with low diagonal orientation, high volume fraction and fine phase size alleviate the propensity of strain localization during the tensile deformation, hence promote the homogenous-like plastic flow mediated by the mass of homogenous shear transformation zones (STZ) operations. More importantly, the strength-ductility synergy of MGs was achieved at the given volume fraction of the rejuvenated phases via properly designing the arrangements of the heterogenous phases. The present study sheds light on the atomistic understanding of the relationship between the structural heterogeneity of rejuvenated amorphous structures and mechanical properties in MGs, which can provide useful insights for designing or processing MGs with a strength-ductility synergy.