A pressure and entropy criterion for glass transition decoupling in high-entropy metallic glasses

Abstract

Decoupling between calorimetric and dynamical glass transitions has been observed in high-entropy metallic glasses (HEMGs) owing to their complex entropy effects. Pressure is another versatile thermodynamic variable that can be used to control the properties of metallic glasses (MGs) owing to the reduced interatomic distances. However, how can it affect such anomalous decoupling behavior in HEMGs remains unclear. Here, molecular dynamics simulations are performed to investigate the influence of pressure on the decoupling behavior in several prototypical MGs and HEMGs. We find that pressure can enhance the sluggish atomic diffusion and depress structural α-relaxation, thus promoting the decoupling in HEMGs, even with less atomic size mismatch. Finally, incorporating pressure and configurational and mismatch entropies, we propose a general criterion based on an explainable machine-learning method to quantitatively classify MG's decoupling or not. These findings refine our understanding of glass transitions and suggest an avenue for manipulating decoupling behaviors in HEMGs.