Fig. 6: Sketches illustrating a possible mechanism of atomic-scale plastic flow consistent with the experimental findings of this paper.
From: Atomic-scale homogeneous plastic flow beyond near-theoretical yield stress in a metallic glass
a A diamond tip with very small radius (some nm) is indenting a sample of bulk metallic glass below the material’s yield point. In this case, deformation can be well described by the Hertz model, and much <1000 atoms are exposed to significant stress levels. b Near the onset of yielding, the volume where atoms are subjected to a stress sufficient to induce positional changes approaches ≈15 nm2, comprising ~1000 atoms. At this stage in the process, the atomic-level heterogeneity intrinsic to any glass due to its structural disorder allows small STZs consisting out of only few atoms to nucleate via small displacements in atomic locations. c Once enough STZ have formed, they move without leading to significant degrees of shear localization. Note, in particular, that these STZs are expected to be transient in its temporal nature, which additionally prevents appreciative degrees of shear localization.
