Dislocation ↔ twin transmutations during interaction between prismatic slip and [formula omitted] twin in magnesium

Abstract

Very unusual and interesting interaction between matrix prismatic dislocations and {101¯1} twin boundaries (TBs) in Magnesium (Mg) was observed in atomistic simulations. When the first prismatic dislocation impinged on the TB, the incoming dislocation was transmuted into a thin layer of {112¯1} twin inside the {101¯1} twin. When successive prismatic dislocations on the same slip plane impinged on the same location at the {101¯1} TB, the {112¯1} twin kept growing toward the opposite {101¯1} TB. Eventually, the {112¯1} twin reached the opposite TB and was then transmuted back to prismatic dislocations that exited the {101¯1} twin and glided into the matrix. Hence, the matrix prismatic dislocations temporarily lose their dislocation identity during twin-slip interaction and then resume their dislocation identity after the interaction is complete. The net effect of these interactions is that the matrix prismatic dislocations transmit across the {101¯1} twin. Lattice correspondence analysis for {101¯1} twinning was performed to understand the mechanism of the interactions. The results show that, the prismatic slip plane is exactly the corresponding plane of {112¯1} twinning. Such a correspondence is consistent with the crystallographic calculations based on classical twinning theory.