Interactions of a screw dislocation with a {1 0 1¯ 1}–{1 0 1¯ 2} double twin in Mg

The interactions of basal screw partials with the {1 0 1¯ 1}–{1 0 1¯ 2} double twin under external shear strains in Mg were investigated by molecular dynamics simulations. Once the trailing partial was absorbed into the {1 0 1¯ 1} twin boundary (TB), the leading and trailing partials recombined on the TB and the resulting recombined dislocation was split into two twinning dislocations. These twinning dislocations then piled up near the triple junction of the {1 0 1¯ 1} and {1 0 1¯ 2} TBs. Complicated interactions occurred between the twinning dislocations and the triple junction, i.e., the cross-slip of the twinning dislocations to the twin region, the relocation of the triple junction along the {3 0 1¯ 4} boundary and the emission of a partial from the triple junction. These interactions were driven for accommodation of the stress concentration around the triple junction. Many defects were generated around the triple junction, resulting from the pile-ups of dislocations.