Figure 1

(a) 3D view of the TB migration during the $\{10\overline{1}2\}⟨10\overline{1}\overline{1}⟩$ twinning in Mg. The atoms on the TB (marching upwards) are highlighted as big circles, whereas other atoms are plotted as little dots. A dashed line marks the initial trace of the TB on the front surface. The circle marks the preconstructed two-layer step which was found immobile. The whole moving TB is rather rough, with no well-defined homogeneous shear and slip plane, and atoms shuffle off plane at large magnitudes. Defining a TD becomes difficult and inadequate. This is contrasted with (b), which is a 3D view of the TB during $\{11\overline{2}2\}⟨11\overline{2}\overline{3}⟩$ twin growth in Ti. Here, only minor in-plane shuffles are involved, and the core, homogeneous shear and slip plane can all be well-defined for a TD.Reuse & Permissions