Non-isothermal stress relaxation in conventional and high-entropy metallic glasses and its relationship to themixing and excess entropy

TL;DR

This study investigates how mixing entropy influences stress relaxation in metallic glasses, revealing that higher entropy glasses resist relaxation more and that excess entropy correlates with relaxation behavior.

Contribution

The paper introduces an entropy-based parameter {}S to quantify the relationship between entropy, structural disorder, and stress relaxation in metallic glasses.

Findings

High-entropy metallic glasses show greater resistance to stress relaxation.

The excess entropy correlates with the depth of stress relaxation.

The entropy parameter {}S effectively characterizes relaxation behavior.

Abstract

We performed calorimetric and torsion stress relaxation measurements upon linear heating of six conventional and high-entropy metallic glasses with the mixing entropy {\Delta}Smix ranging from 0.86R to 1.79R (R is the universal gas constant). It is shown that high-entropy metallic glasses ({\Delta}Smix > 1.5 R) exhibit significantly greater resistance to stress relaxation. Based on calorimetric data, we calculated the excess entropy of glass relative to the counterpart crystalline state and introduced an entropy-based dimensionless parameter {\Delta}S, which characterizes the rise of the entropy and structural disordering of glass in the supercooled liquid region. It is shown that the depth of stress relaxation at a given temperature decreases with {\Delta}Smix but increases with {\Delta}S. Possible reasons for this relationship are discussed.