Rare events and disorder control the brittle yielding of well-annealed amorphous solids

TL;DR

This study uses atomistic simulations to understand the microscopic origins of brittle failure in well-annealed amorphous solids, highlighting the influence of rare soft regions and quenched disorder in triggering shear band propagation.

Contribution

It provides a microscopic description linking rare soft regions and disorder to brittle yielding, extending understanding of failure mechanisms in amorphous materials.

Findings

Brittle yielding originates at rare soft regions.

Localized plastic events trigger macroscopic failure.

Finite size effects influence brittle failure behavior.

Abstract

We use atomistic computer simulations to provide a microscopic description of the brittle failure of amorphous materials, and we assess the role of rare events and quenched disorder. We argue that brittle yielding originates at rare soft regions, similarly to Griffiths effects in disordered systems. We numerically demonstrate how localized plastic events in such soft regions trigger macroscopic failure via the propagation of a shear band. This physical picture, which no longer holds in poorly annealed ductile materials, allows us to discuss the role of finite size effects in brittle yielding and reinforces the similarities between yielding and other disorder-controlled nonequilibrium phase transitions.