Faceting of twin interfaces in rolled pure magnesium

Recent studies proved that the faceting of twin boundaries is a common feature in hcp materials. It was demonstrated that the asymmetrical facets in the most frequent {101¯2} and {101¯1} twin interfaces are the consequence of the twin boundary migration mechanism. We demonstrate that a similar mechanism is also applicable to less common {112¯6} twins, observed in pure magnesium rolled at room temperature. The migration of {112¯6} twin boundary is mediated by disconnections, which have Burgers vector b=0.030[112¯1¯] and step height equal to four {112¯6} interplanar distances. The mechanism of asymmetrical facets nucleation is also demonstrated by using atomistic simulations. The simulations are supported by transmission electron microscopy (TEM) of asymmetrical basal-pyramidal interfaces of {112¯6} twins.