X-Ray Photon Correlation Spectroscopy Reveals Intermittent Aging Dynamics in a Metallic Glass

TL;DR

This study uses coherent X-ray techniques to reveal that aging in metallic glasses involves intermittent, heterogeneous atomic rearrangements driven by internal stress relaxation, challenging the view of steady slowing dynamics.

Contribution

It provides direct atomic-level evidence that aging in metallic glasses is characterized by intermittent and cooperative rearrangements, revealing complex energy landscape effects.

Findings

Aging dynamics are intermittent and heterogeneous at the atomic scale.

Structural relaxation involves cooperative atomic rearrangements.

Internal stress relaxation drives the aging process.

Abstract

We use coherent X-rays to probe the aging dynamics of a metallic glass directly on the atomic level. Contrary to the common assumption of a steady slowing down of the dynamics usually observed in macroscopic studies, we show that the structural relaxation processes underlying aging in this metallic glass are intermittent and highly heterogeneous at the atomic scale. Moreover, physical aging is triggered by cooperative atomic rearrangements, driven by the relaxation of internal stresses. The rich diversity of this behavior reflects a complex energy landscape, giving rise to a unique type of glassy-state dynamics.