Figure 6

Semi-quantitative illustration of deformation mechanism map of Sn.

For displacive deformation, Hall-Petch strengthening predicts “smaller is stronger” trend (red curve). Surface diffusional deformation is governed by Coble creep. At a fixed strain rate, stress follows σ ∝ D³, which shows “smaller is weaker” (black curve). These two curves crossed and distinguished the two deformation mechanism, i.e. displacive plasticity and diffusive plasticity.