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 ¯   1 }   〈 1 ¯   1 ¯   2   3 〉 and 1 / 3 { 1   1   2 ¯   2 }   〈 1 ¯   1 ¯   2   3 〉 , are determined in pure magnesium using molecular dynamics simulation. In particular, simulations of [ 1   1   2 ¯   0 ] - and [ 1   0   1 ¯   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 ¯   0 ] -textured Mg, the first-order pyramidal 〈c + a〉 slip occurs with 1 / 6 〈 2 ¯   0   2   3 〉 partials or 1 / 9 [ 0   1 ¯   1   3 ] + 1 / 18 [ 6 ¯   2   4   3 ] + 1 / 6 [ 0   2 ¯   2   3 ] extended dislocations. Secondary pyramidal dislocations are created with edge type from grain boundaries in the [ 1   0   1 ¯   0 ] -texture . The pyramidal 〈c + a〉 slip on the { 1   1   2 ¯   2 } plane can extend to the basal plane, on which it is terminated by a screw dislocation on the { 1   0   1 ¯   1 } plane.