Stabilization of Zr-base metallic glass studied by isochronal and isothermal annealing experiments

The internal friction Q−1 and the oscillation frequency f of a Zr–Ti–Cu–Ni–Be metallic glass specimen were measured using an inverted torsion pendulum with the free decay method. A single-roller melt-spinning apparatus was used for preparing the specimens. Two kinds of experiments have been performed. In the isochronal annealing experiment, temperature dependences of Q−1 and f were measured from the room temperature up to the crystallization temperature Tx. The glass was found to become stabilized state by a long-time annealing near and below the glass transition temperature Tg. In the isothermal annealing experiment, time dependences of Q−1 and f were measured at various annealing temperatures Ta, and the relaxation time τ for the annealing process was determined. The dependence of τ on Ta showed that the stabilization near Tg could be due to the viscoelastic relaxation occurring in the glassy material.