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, $1/3\left\{10\overline{1}1\right\}〈\overline{1}\overline{1}23〉$ and $1/3\left\{11\overline{2}2\right\}〈\overline{1}\overline{1}23〉$, are determined in pure magnesium using molecular dynamics simulation. In particular, simulations of $\left[11\overline{2}0\right]\text{-}$ and $\left[10\overline{1}0\right]\text{-textured}$ 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 $\left[11\overline{2}0\right]\text{-textured}$ Mg, the first-order pyramidal 〈c + a〉 slip occurs with $1/6〈\overline{2}023〉$ partials or $1/9\left[0\overline{1}13\right]+1/18\left[\overline{6}243\right]+1/6\left[0\overline{2}23\right]$ extended dislocations. Secondary pyramidal dislocations are created with edge type from grain boundaries in the $\left[10\overline{1}0\right]\text{-texture}$. The pyramidal 〈c + a〉 slip on the $\left\{11\overline{2}2\right\}$ plane can extend to the basal plane, on which it is terminated by a screw dislocation on the $\left\{10\overline{1}1\right\}$ plane.