Nucleation of a (over(1, ̄) 0 1 2) twin in hexagonal close-packed crystals

Abstract

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