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

TL;DR

This study uses molecular dynamics simulations to explore how strain amplitude, thermal fluctuations, and glass stability influence shear band formation and delayed yielding in binary glasses at finite temperature.

Contribution

It reveals that more stable, highly annealed glasses exhibit larger critical strain amplitudes and delayed yielding, with nucleation of atomic clusters preceding the transition.

Findings

Critical strain amplitude increases with glass stability.

Yielding transition is delayed in more annealed glasses.

Nucleation of atomic clusters precedes energy change during yielding.

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.