Pyramidal slip in magnesium: Dislocations and stacking fault on the {101̄1} plane

Molecular dynamics (MD) simulations are presented to illustrate the pyramidal slip processes on the {101̄1} plane (also a twinning plane) in magnesium. The simulations eveal 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 {101̄1} plane, each having both 〈c〉 and 〈a〉 components. The first dislocation glides with an effective Burgers vector1/2.1/2 [011̄2] (1/2[011̄2] is also the twinning vector 1), and the second dislocation with an effective Burgers vector 1/2.1/2 [011̄2]+1/2.1/3[21̄1̄0]. When operating separately, the first incomplete dislocation leads to a wide stacking fault on the {101̄1} 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.