Hidden dormant phase mediating the glass transition in disordered matter

TL;DR

This study visualizes a hidden dormant phase during the glass transition in metallic glasses, revealing nanoscale activity that drives the transition without macroscopic volume change, offering new insights into disordered matter phase behavior.

Contribution

It provides the first direct microscopic visualization of a dormant phase mediating the glass transition in disordered materials.

Findings

Identification of a hidden dormant phase during glass transition.

Nanoscale redistribution occurs without macroscopic volume change.

Nanoscale channels drive the transition process.

Abstract

Metallic glass is a frozen liquid with structural disorder that retains degenerate free energy without spontaneous symmetry breaking to become a solid. For over half a century, this puzzling structure has raised fundamental questions about how structural disorder impacts glass-liquid phase transition kinetics, which remain elusive without direct evidence. In this study, through single-pulse, time-resolved imaging using X-ray free-electron lasers, we visualized the glass-to-liquid transition, revealing a previously hidden dormant phase that does not involve any macroscopic volume change within the crossover regime between the two phases. Although macroscopically inactive, nanoscale redistribution occurs, forming channeld low-density bands within this dormant phase that drives the glass transition. By providing direct microscopic evidence, this work presents a new perspective on the phase transition process in disordered materials, which can be extended to various liquid and solid phases in other complex systems.