Shear bands in metallic glasses: Size effects on thermal profiles

The characteristic dimensions of the hot, liquid zone behind a moving shear-band front in a metallic glass are analyzed. In addition to the expected dependence on material constants, the thickness of the zone is proportional to the shear offset, while its width is proportional to the square of the offset. Considering the bending of a plate, the size and shape of the hot zone are found to be strongly dependent on plate thickness. For shear offsets ≪1μm, typical of plate thickness ≪100μm, local temperature rises are insignificant. For larger dimensions, local temperature rises give a liquid zone centered on the shear plane with width comparable to the sample dimensions. The scaling of characteristic lengths and times with plate thickness facilitates the interpretation of the transitions observed in mechanical behavior, and the variation in behavior from glass to glass.