Creep and recovery behavior of metallic glasses in a global strain approach within transition state theory

A unique global strain approach based on the transition state theory was proposed to quantify the creep-recovery processes of metallic glasses, in which the structure of glasses is predominantly governed by the macroscopic strain. This methodology allows for the calculation of strain-dependent activation energy and activation volume for flow defects. The activation energy and volume of creep both increase linearly with the magnitude of strain. Upon the glass-to-liquid transition, they get large and strain-independent, which serves as a signature of the glass transition. During creep recovery, the cooperation of deformation units increases the activation volume but decreases activation energy due to the decrease in free volume. Notably, only a fraction of the anelasticity accumulated during creep persists in the recovery process; the rest is suppressed by structural relaxation. The results introduce physical insights into the deformation and relaxation of metastable solids that are not available in the usual rate-dependent theory developed for crystal plasticity.