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

Abstract

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.

Nanocrystals in Metallic Glasses

“…Proposed mechanisms for deformation-induced crystallization either follow the argument of adiabatic heating in shear bands as source for crystallization or they follow the argument of enhanced kinetics in shear bands due to the dilatation of the metallic glass in shear bands. Several studies focused on estimates or experimental analyses of the transient temperatures that develop during the shear band formation and propagation (Lewandowski and Greer, 2006;Hongwen et al, 2007;Battezzati and Baldissin, 2008;Jiang et al, 2008). The shear strains within shear bands are estimated to be on the order of 100 % (Jiang et al, 2007).…”