Linking the pressure dependence of the structure and thermal stability to {\alpha}- and \b{eta}-relaxations in metallic glasses

TL;DR

This study investigates how high pressure affects relaxation processes in metallic glasses, revealing distinct mechanisms for {eta}- and extalpha}-relaxations and their impact on structural stability and thermal properties.

Contribution

It provides the first detailed experimental analysis of pressure-dependent relaxation spectra in metallic glasses, linking relaxation mechanisms to structural stability under extreme conditions.

Findings

High pressure reduces atomic mobility in {eta}-relaxation without density change.

extalpha}-relaxation under pressure enhances structural ordering and stability.

Transition between relaxation regimes occurs at a constant T/Tg,P ratio, regardless of pressure.

Abstract

Glasses derive their functional properties from complex relaxation dynamics that remain enigmatic under extreme conditions. While the temperature dependence of these relaxation processes is well-established, their behavior under high-pressure conditions remains poorly understood due to significant experimental difficulties. In this study, we employ cutting-edge experimental techniques to probe the pressure evolution of the relaxation spectrum in a Zr46.8Ti8.2Cu7.5Ni10Be27.5 metallic glass across gigapascal pressure ranges. Our findings reveal two distinct relaxation mechanisms under high pressure: In the \b{eta}-relaxation regime, compression drives the system with reduced atomic mobility and enhanced structural disorder, without significant density changes. Conversely, {\alpha}-relaxation under pressure promotes density-driven structural ordering that improves thermal stability. Notably, the transition between these regimes occurs at a constant T/Tg,P ratio, independent of applied pressure. These results provide crucial insights for decoupling the competing structural and relaxation contributions to glass stability, establishing a systematic framework for tailoring glass properties through controlled thermo-mechanical processing.