Grain-boundary activated pyramidal dislocations in nano-textured Mg by molecular dynamics simulation

The generation and structures of first- and second-order pyramidal (c + a) dislocations, 1/3{1 0 (1) over bar 1} ((1) over bar (1) over bar 2 3) and 1/3{1 1 (2) over bar 2} ((1) over bar (1) over bar 2 3), are determined in pure magnesium using molecular dynamics simulation. In particular, simulations of [1 1 (2) over bar 0]- and [1 0 (1) over bar 0]-textured polycrystalline Mg display pyramidal (c + a) slip nucleated at grain boundaries. Both the first- and second-order dislocations appear as a partial or extended edge type. In the [1 1 (2) over bar 0]-textured Mg, the first-order pyramidal (c + a) slip occurs with 1/6((2) over bar 0 2 3) partials or 1/9[0 (1) over bar 1 3] + 1/18[(6) over bar 2 4 3] + 1/6[0 (2) over bar 2 3] extended dislocations. Secondary pyramidal dislocations are created with edge type from grain boundaries in the [1 0 (1) over bar 0]-texture. The pyramidal (c + a) slip on the {1 1 (2) over bar 2} plane can extend to the basal plane, on which it is terminated by a screw dislocation on the {1 0 (1) over bar 1} plane. (C) 2011 Elsevier B.V. All rights reserved.