Creep deformation in metallic glasses: A global approach with strain as an indicator within transition state theory

Within the framework of transition state theory, the isothermal creep behavior of metallic glasses is elucidated through a unique global approach, where the topological state is exclusively linked to measured strain. Our methodology allows the computation of the average activation volume and activation energy of deformation units as a function of strain. Experimental data from four representative metallic glasses (La₃₀Ce₃₀Ni₁₀Al₁₀Co₂₀, La₆₅Ni₁₅Al₂₅, La_56.16Ce_14.04Ni_19.8Al₁₀, and Cu₄₆Zr₄₆Al₈) reveal two distinct characteristics. Below the glass transition temperature, the mechanical response is primarily influenced by secondary relaxation processes and excess configuration entropy, with activation volume increasing with strain. Upon reaching the glass transition temperature, the activation volume becomes notably larger and strain-independent. Additionally, the activation energy exhibits an increase with strain, and deformation units of varying sizes are progressively activated, from smaller to larger units. The decoupling and competition among relaxation events are correlated with the increase in the activation volume of deformation units. These findings provide valuable insights into the dynamic behavior of metallic glasses and their mechanical response across different states.