Rejuvenation of metallic glasses under high pressure

TL;DR

This paper demonstrates that high pressure annealing can effectively rejuvenate metallic glasses by inducing microstructural changes, leading to higher energy states, which contrasts with traditional ambient pressure annealing methods.

Contribution

It introduces high pressure annealing as a controllable technique to rejuvenate metallic glasses, revealing microstructural origins involving negative flow units.

Findings

Rejuvenation in enthalpy is achieved and preserved by high pressure annealing.

Rejuvenation increases with higher annealing temperature and pressure.

Microstructural analysis shows involvement of negative flow units with higher atomic packing density.

Abstract

Modulating energy states of metallic glasses (MGs) is significant in understanding the nature of glasses and control their properties. In this study, we show that rejuvenation in enthalpy can be achieved and preserved in bulk MGs by using high pressure (HP) annealing, which is a controllable method to continuously alter the energy states of MGs. Contrary to the decrease in enthalpy by conventional annealing at ambient pressure, such rejuvenation can occur and be enhanced by increasing both of annealing temperature and pressure. By using double aberration corrected scanning transmission electron microscopy, it is revealed that the rejuvenation, which is attributed to coupling effect of high pressure and high temperature, originates from the microstructural change that involves "negative flow units" with a higher atomic packing density compared to that of the elastic matrix of MGs. The results demonstrate that HP annealing is an effective way to rejuvenate MGs into higher energy states, and it may assist in understanding the microstructural origin of the rejuvenation in MGs.