Correlating dynamic relaxation and viscoelasticity in metallic glasses

Relaxation dynamics, essential for the structural evolution of non-equilibrium systems like glassy materials, remain enigmatic. Here, we explore relaxation dynamics and viscoelastic properties in three types of metallic glasses with distinct β relaxation behavior. In systems with significant β relaxation, stress relaxation and creep experiments reveal a transition from two-step to one-step relaxation with rising temperature. However, such a phenomenon is absent in systems with weaker β relaxation. We model the two-step relaxation process using a double Kohlrausch-Williams-Watts equation, and the obtained relaxation times elegantly adhere to the Arrhenius relationship. By combining fitted activation energies with theoretical analysis, we conclusively attribute these relaxation processes to β relaxation and α relaxation, respectively. Finally, we analyze the relaxation time spectra of two processes and establish a comprehensive picture linking dynamic relaxation with viscoelasticity. Our study provides new strategies for probing the complex relaxation behaviors of glasses from the perspective of viscoelasticity. © Science China Press 2024.