Pyramidal slip in magnesium: Dislocations and stacking fault on the {1011} plane

Molecular dynamics (MD) simulations are presented to illustrate the pyramidal slip processes on the [image omitted] plane (also a twinning plane) in magnesium. The simulations reveal an interesting slip mode consisting of two separate partial dislocations that nucleate independently. These dislocations glide in a slightly corrugated fashion on the non-close-packed [image omitted] plane, each having both c and a components. The first dislocation glides with an effective Burgers vector [image omitted] ([image omitted] is also the twinning vector 1), and the second dislocation with an effective Burgers vector [image omitted]. When operating separately, the first incomplete dislocation leads to a wide stacking fault on the [image omitted] plane. When the second dislocation follows and combines with the first dislocation at the surface, the net end result is equivalent to a c + a dislocation. However, inside the crystal there is no unit c + a dislocation per se or its splitting.