Temperature increases caused by shear banding in as-cast and relaxed Zr-based bulk metallic glasses under compression

Using an infrared camera, the temperature evolution of as-cast and relaxed bulk metallic glasses during compression was measured. Substantial variations in the temperatures of both glasses during plastic deformation were observed, which are conjectured to result at least partially from shear-banding phenomena. The relaxed glass has a larger temperature rise than the as-cast glass, which can be attributed to a reduction in the free volume. The larger temperature increase in the relaxed glass may be responsible for the observed work softening. The relaxed glass also has a higher maximum temperature than the as-cast, which can be attributed to a stronger strain-rate dependence of the temperature rise rate, and a shorter dissipation time scale for the heat due to conduction. The experimental data follow the well-known model behavior, and suggest the possibility of a statistical correlation between the fluctuations of strain rates and the rates of the temperature variation.