Faceting of {11(2)over-bar6} twin interfaces in rolled pure magnesium

摘要

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 {10 (1) over bar2} and {10 (1) over bar1} twin interfaces are the consequence of the twin boundary migration mechanism. We demonstrate that a similar mechanism is also applicable to less common {11 (2) over bar6} twins, observed in pure magnesium rolled at room temperature. The migration of {11 (2) over bar6} twin boundary is mediated by disconnections, which have Burgers vector b = 0.030[11 (2) over bar(1) over bar] and step height equal to four {11 (2) over bar6} 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 {11 (2) over bar6} twins.