Non-Dislocation Based Room Temperature Plastic Deformation Mechanism in Magnesium

Dislocation and deformation twinning are traditionally known to be plasticity carriers of crystalline materials at room temperature. By using in-situ TEM mechanical testing technique, here we report that the plasticity of a specially orientated single crystal magnesium can be mediated neither by dislocation nor by twinning, but through a non-dislocation based process, termed as unit-cell-reconstruction. After the reconstruction, a ~7% strain is produced. The newly formed grain and its parent grain are separated by a boundary that mainly consisted of basal-prismatic interfaces. Such boundary can migrate back and forth under a cyclic loading and therefore produce a reversible plastic deformation. The reported novel mechanism may have important implications for the alloy design of magnesium.