A new model for {10(1)over-bar2} twin growth in hcp metals

Computer simulation has been used to study the interaction of a perfect, basal dislocation with a {<10(1)over bar 2>} twin boundary in a hcp metal for the situation where the 1/3[<11(2)over bar 0>] Burgers vector is inclined at 60 degrees to the interface. It is found that slip is not transferred from one crystal to the other with a residual dislocation left at the interface. Instead, the matrix dislocation decomposes into interfacial defects. We show that as a result of this decomposition the matrix dislocation becomes a new source of twinning dislocations that produce twin growth when the appropriate stress is applied to the crystal. The mechanism described does not require twinning dislocations to multiply by a pole process.