Quenching rate dependence of free volume in a Zr-Cu-Ni-Ti-Be glass as probed by positron annihilation lifetime spectroscopy

Many properties in metallic glasses like diffusivity or ductility are affected by the concentration of the free volume. Hence, the determination of the concentration and the dependencies on experimental parameters are of major interest. For Zr46.8Ti8.2Cu7.5Ni10Be27.5, a typical bulk amorphous alloy, different amounts of free volume have been quenched-in by variation of the cooling rate by more than three orders of magnitude. Positron annihilation lifetime spectroscopy has been used to probe the free volume quenched-in. The average lifetime increases with increase in cooling rate, reflecting higher free volume for higher cooling rates. This can be correlated to the increase in the caloric glass transiton temperature.