Atomic-level structural identification for prediction of localized shear deformation in metallic glasses

Unlike obviously topological defects in crystals, defect identification in metallic glasses (MGs) is still controversial and under investigation. Based on molecular simulations and analysis of MG samples, a structural parameter related to the Laplacian of local equivalent stiffness is proposed for prediction of localized shear deformation in MGs. It is found that local regions with the parameter of positive and relatively large value represent several particular modes of stiffness valleys in initial configuration which will strengthen local shear deformation and lead to the formation of shear transformation zones (STZs). More than 80% of the locations where STZs are formed in six types of MG samples under athermal quasi-static shear deformation match well with the regions predicted by the parameter calculated from initial configuration of the samples. The parameter not only reveals the relationship among local heterogeneity, nonaffine displacement, and shear localization, but also provides an efficient way for predicting the activation of STZs in MGs. (C) 2020 Elsevier Ltd. All rights reserved.