Atomic Level Simulation Of Deformation In Nanocrystalline Materials And Metallic Glasses

At the amorphous limit, bulk metallic glasses fail by intensely localized shear bands with very little macroscopic ductility, which limits structural service. It is understood through experiment and thermodynamics that a defect of volume from one to several vacancies plays a critical role in initiating and propagating shear, but not the structure of this defect or how it operates. Here we use atomistic modeling and electron density calculations to study defect distribution and migration in a metallic glass, and evolution under shear. We find a critical stress threshold to activate shear banding, and an enhancement of shear localization in the neighborhood of a dissolving void.