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, 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 T for the stabilization process were determined. The dependence of tau 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. (C) 2007 Elsevier B.V. All rights reserved.