Characterization and modeling of dynamic relaxation of a Zr-based bulk metallic glass

Dynamic mechanical properties of the Zr40Ti25Cu8Be27 bulk metallic glass with large supercooled liquid region were investigated in both temperature and frequency domains. In the framework of the spectrum of loss modulus G″, master curves were established by using the time-temperature superposition principle. We found that temperature dependence of the shift factor follows the Arrhenius relationship around the glass transition temperature Tg. The activation energy for the low temperature relaxation and viscous flow were 1.2 eV and 4.47 eV, respectively. In addition, the fragility index was evaluated by considering temperature effect to the shift factor. The main relaxation was investigated by using different theoretical models. Due to the non-symmetrical characteristic of the main (α) relaxation, the main relaxation can not be well described with a single relaxation time. The advantages and disadvantages of various models are discussed. The physical significance of different parameters is qualitatively and quantitatively evaluated, which could help to understand the mechanical relaxation mechanism in bulk metallic glasses.