Denser glasses relax faster: a competition between rejuvenation and aging during in-situ high pressure compression at the atomic scale

TL;DR

This study reveals that metallic glasses exhibit faster relaxation under high pressure due to a competition between rejuvenation and aging at the atomic level, with distinct regimes observed during compression.

Contribution

It provides atomic-scale insights into how metallic glasses undergo structural and dynamic changes under high pressure, highlighting the interplay of rejuvenation and aging effects.

Findings

Atomic motion accelerates with compression

Reversible densification observed structurally

Hysteresis with rejuvenation and aging regimes

Abstract

A fascinating feature of metallic glasses is their ability to explore different configurations under mechanical deformations. This effect is usually observed through macroscopic observables, while little is known on the consequence of the deformation at atomic level. Using the new generation of synchrotrons, we probe the atomic motion and structure in a metallic glass under hydrostatic compression, from the onset of the perturbation up to a severely-compressed state. While the structure indicates reversible densification under compression, the dynamic is dramatically accelerated and exhibits a hysteresis with two regimes. At low pressures, the atomic motion is heterogeneous with avalanche-like rearrangements suggesting rejuvenation, while under further compression, aging leads to a super-diffusive dynamics triggered by internal stresses inherent to the glass. These results highlight the complexity of the atomic motion in non-ergodic systems and support a theory recently developed to describe the surprising rejuvenation and strain hardening of metallic glasses under compression.