A delayed yielding transition in mechanically annealed binary glasses at finite temperature

Abstract

The influence of strain amplitude, glass stability and thermal fluctuations on shear band formation and yielding transition is studied using molecular dynamics simulations. The model binary mixture is first gradually cooled below the glass transition temperature and then periodically deformed to access a broad range of potential energy states. We find that the critical strain amplitude becomes larger for highly annealed glasses within about one thousand shear cycles. Moreover, upon continued loading at a fixed strain amplitude, the yielding transition is delayed in glasses mechanically annealed to lower energy states. It is also demonstrated that nucleation of a small cluster of atoms with large nonaffine displacements precedes a sharp energy change associated with the yielding transition. These results are important for thermal and mechanical processing of amorphous alloys with tunable mechanical and physical properties.