Atomistic simulations of twin facets associated with three-dimensional {1¯011} twins in magnesium

Abstract

Twinning is a deformation mechanism that creates three-dimensional (3D) twin domains through the migration of twin facets. This occurs via the nucleation and glide of twinning disconnections (TDs), which can pile up to create twin facets. A comprehensive understanding of twin facets associated with 3D twins, including their atomic structures and energies, is crucial for understanding deformation twinning. In this study, we propose a molecular statics/dynamics (MS/MD) approach to determine characteristic twin facets enclosing 3D non-equilibrium/equilibrium {$\overline{1}011$} twin domains, which has been much less studied than the counterpart {$\overline{1}012$} twin domains. The stability of different TD pile-up arrangement with varying line senses informs the morphology of 3D non-equilibrium twins, which are bounded by {$10\overline{1}0$}_T||{$\overline{1}013$}_M, {$10\overline{1}1$}_T||{0002}_M and {$10\overline{1}3$}_T||{$10\overline{1}3$}_M coherent facets associated with pile-up of edge TDs, and discrete non-edge TDs aligned along CTBs with their line senses parallel to <$4\overline{5}13$>, <$1\overline{1}01$>, <$5\overline{4}\overline{1}6$> <$2\overline{1}\overline{1}3$>or <$10\overline{1}2$> axes. Formation of semi-coherent facets of equilibrium twins is accompanied by rearrangement of TDs around misfit dislocations. 3D equilibrium {$\overline{1}011$} twins may comprise {$10\overline{1}1$}_T||{0002}_M, {$14\overline{5}7$}_T||{$3\overline{4}19$}_M, {$\overline{1}6\overline{5}7$}_T||{$5\overline{6}17$}_M, {$\overline{1}4\overline{3}3$}_T||{$3\overline{4}13$}_M, {$01\overline{1}0$}_T||{$01\overline{1}1$}_M and {$0\overline{2}21$}_T||{$0\overline{2}21$}_M semi-coherent facets in <$1\overline{2}10$>, <$4\overline{5}13$>, <$1\overline{1}01$>, <$5\overline{4}\overline{1}6$>, <$2\overline{1}\overline{1}3$> and <$10\overline{1}2$> axes, respectively.