Stabilization of metallic glass studied by internal friction measurement

The internal friction Q^?1 and the oscillation frequency f of Zr–Ti–Cu–Ni–Be metallic glass specimens were measured using an inverted torsion pendulum with the free decay method. A single-roller melt-spinning apparatus was used for preparing the specimens. Isothermal annealing near the glass transition temperature T_g was performed to investigate the stabilization of the specimens. Q^?1 decreased with annealing time t due to the stabilization. Q^?1-vs-t was measured at various annealing temperatures T_a, and the values of relaxation time τ for the stabilization process were determined. The dependence of τ on T_a showed that the hydrodynamic behavior represented by the Vogel–Tammann–Fulcher form and the hopping behavior represented by the Arrhenius form were observed in high- and low-temperature regions, respectively. The crossover of the two behaviors was seen at a temperature near and somewhat higher than T_g. The result was discussed on the basis of the viscoelastic relaxation in glassy materials.