Microstructure Characteristics of Nucleation and Growth for the \(\left\{ {10\overline{1}1} \right\}\) Twin in Mg Polycrystal via an Atomistic Simulation

Using molecular dynamics (MD) simulations, microstructure evolution during nucleation and growth of the \(\left\{ {10\overline{1}1} \right\}\) twin in polycrystal Mg is studied. The results show that profuse basal stacking faults (BSFs) form inside the \(\left\{ {10\overline{1}1} \right\}\) twin embryo and disconnections with different step size are also characterized along the twinning boundary (TB) interface. The disconnections can be divided into two types according to their mobility, i.e., mobile steps with height of \(2h_{0}\) and \(4h_{0}\) and immobile steps with \(h_{0}\) and \(3h_{0}\). We find that the front line of mobile steps is divided into small segments due to the BSFs, and each segment will move as a unit at different velocity. When the mobile interfacial steps are consumed at grain boundaries, new steps are nucleated and glide on the TB interface. Such a process leads to twinning growth in the lateral and vertical directions. These insights contribute to the fundamental understanding of twinning mechanism in Mg.