Pyramidal slip in magnesium: Dislocations and stacking fault on the {10 1 1} plane

Molecular dynamics (MD) simulations are presented to illustrate the pyramidal slip processes on the 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 plane, each having both ⟨c⟩ and ⟨a⟩ components. The first dislocation glides with an effective Burgers vector ( is also the twinning vector η1), and the second dislocation with an effective Burgers vector . When operating separately, the first incomplete dislocation leads to a wide stacking fault on the 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.