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

We performed calorimetric and torsion stress relaxation measurements upon linear heating of six conventional and high-entropy metallic glasses with the mixing entropy ΔS_mix ranging from 0.86R to 1.79R (R is the universal gas constant). It is shown that high-entropy metallic glasses (ΔS_mix>1.5R) 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 Δ_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 ΔS_mix but increases with Δ_S. Possible reasons for this relationship are discussed.