Nucleation of a (1¯012) twin in hexagonal close-packed crystals

We have studied the atomic structures of the nucleus of a [ 1 0 1 ¯ 1 ] ( 1 ¯ 0 1 2 ) twin in Mg by atomistic simulations using density function theory and an empirical potential. The twinning mechanism for ( 1 ¯ 0 1 2 ) twins is described. The results show that the nucleus consists of one partial dislocation with a Burgers vector of - 50 / 107 [ 1 0 1 ¯ 1 ] together with multiple twinning dislocations (TDs) with a Burgers vector of 1 / 15 [ 1 0 1 ¯ 1 ] . The minimum, stable nucleus involves eight TDs and one partial dislocation, corresponding to a thickness of 17 crystallographic planes.

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