Atomic-scale simulations of strain localization in three-dimensional model amorphous solids

Abstract

Molecular-dynamics simulations of the mechanical properties of three different three-dimensional metallic glass analogs reveal that each exhibits a transition from homogeneous flow to localized flow as the quench rate used to produce the glass is decreased. The solid samples are tested in uniaxial compression over more than an order of magnitude range of strain rates. Three different systems are studied including one single-component glass former and two binary alloys. The strain rate sensitivity of the localization changes sign at a critical cooling rate, implying a discontinuous transition in mechanical properties in the low loading rate limit. Analysis of the short-range order using a generalization of the Frank-Kasper criterion reveals that the short-range order is depleted in the shear band in two of the three systems. Moreover, the homogeneous to inhomogeneous deformation transition in the mechanical properties is found to coincide with the percolation of an identifiable aspect of the short-range order in those two systems. The third system studied, the Kob-Anderson glass, is hypothesized not to be amenable to the methods typically used to characterize short-range order due to its non-hard-sphere nature.