Slow relaxation dynamics in binary glasses during stress-controlled, tension-compression cyclic loading

TL;DR

This study uses molecular dynamics simulations to explore how cyclic tension-compression affects the relaxation, densification, and mechanical properties of metallic glasses, revealing progressive energy minimization and microstructural changes.

Contribution

It demonstrates how cyclic loading induces densification and alters mechanical properties in metallic glasses, providing insights for thermomechanical processing.

Findings

Potential energy decreases with cyclic loading, indicating densification.

Elastic modulus decreases as density increases.

Cluster size of nonaffine displacements shrinks over cycles.

Abstract

The effect of cyclic loading on relaxation dynamics and mechanical properties of metallic glasses is studied using molecular dynamics simulations. We consider the Kob-Andersen three-dimensional binary mixture rapidly cooled across the glass transition and subjected to thousands of tension-compression cycles in the elastic range. It was found that during cyclic loading at constant pressure, the system is relocated to progressively lower levels of the potential energy, thus promoting greater densification and higher strength. Furthermore, with increasing stress amplitude, the average glass density increases and the minimum of the potential energy becomes deeper, while the elastic modulus is reduced. The typical size of clusters of atoms with large nonaffine displacements becomes smaller over consecutive cycles, which correlates with the gradual decrease in the potential energy. These results are important for thermomechanical processing of metallic glasses with improved mechanical properties.