Diffusion in a model metallic glass: heterogeneity and ageing

TL;DR

This study uses molecular dynamics simulations to explore how diffusion and dynamic heterogeneity evolve with temperature and aging in a model metallic glass, revealing their correlated behavior and underlying defect annealing processes.

Contribution

It demonstrates the relationship between diffusivity and heterogeneity during aging in metallic glasses, highlighting defect annealing as a key mechanism.

Findings

Diffusivity decreases with aging.

Heterogeneity increases with aging.

Both diffusivity and heterogeneity decay with the same constants.

Abstract

We report results of molecular dynamics simulations of a binary Lennard-Jones system at zero pressure in the undercooled liquid and glassy states. We first follow the evolution of diffusivity and dynamic heterogeneity with temperature and show their correlation. In a second step we follow the ageing of a quenched glass. As diffusivity decreases with ageing, heterogeneity increases. We conclude that the heterogeneity is a property of the inherent diffusion of the relaxed state. The variations with aging time can be explained by annealing of quenched defect structures. This annealing has the same decay constants for both diffusivity and heterogeneity of both components. \