Deformation twinning and detwinning in the lamella copper observed by in-situ TEM

Deformation twinning in metal is normally a permanent plastic deformation mechanism. In this study, deformation twining and detwinning were observed at a crack tip by in-situ transmission electron microscope and the post fracture surface characterization for the lamella copper. At deformation twinning process, the larger twins grew at expense of the smaller twins adjacent to them via the partial dislocations. The detwinning process is accomplished via the collective glide of multiple twinning dislocations that form an incoherent twin boundaries under the action of shear stress. This discovery of reversible twinning is the evidence that small scale deformation twinning is unstable.