Onset of yielding and shear band nucleation in an Au-based bulk metallic glass

Nanoindentation tests were performed on an Au49Ag5.5Pd2.3Cu26.9Si16.3 metallic glass. The critical shear stress for the first pop-in, i.e. the onset of yielding, was measured at different temperatures. The volume and the activation free energy for the shear transformation zones were determined from the stress–temperature relationship. The strain-rate dependence of serrated flow in nanoindentation was also characterized. The sizes of shear band nucleus at different temperatures were found to be practically constant. The implication of a constant nucleus size is discussed.