Accelerated rejuvenation in metallic glasses subjected to elastostatic compression along alternating directions

TL;DR

This study uses molecular dynamics simulations to show that alternating elastostatic compression can rejuvenate metallic glasses, reducing their elastic modulus and stress overshoot, with implications for improving their mechanical properties.

Contribution

It demonstrates that alternating static stress directions enhance rejuvenation effects and mechanical property modifications in metallic glasses, a novel approach in their processing.

Findings

Rejuvenation occurs via collective atomic rearrangements at high static stress.

Alternating stress orientations amplify rejuvenation and increase nonaffine displacement clusters.

Prolonged loading reduces elastic modulus and stress overshoot in metallic glasses.

Abstract

The influence of static stress and alternating loading direction on the potential energy and mechanical properties of amorphous alloys is investigated using molecular dynamics simulations. The model glass is represented via a binary mixture which is first slowly annealed well below the glass transition temperature and then subjected to elastostatic loading either along a single direction or along two and three alternating directions. We find that at sufficiently large values of the static stress, the binary glass becomes rejuvenated via collective, irreversible rearrangements of atoms. Upon including additional orientation of the static stress in the loading protocol, the rejuvenation effect is amplified and the typical size of clusters of atoms with large nonaffine displacements increases. As a result of prolonged mechanical loading, the elastic modulus and the peak value of the stress overshoot during startup continuous compression become significantly reduced, especially for loading protocols with alternating stress orientation. These findings are important for the design of novel processing methods to improve mechanical properties of metallic glasses.