Atomistic study of nucleation and migration of the basal/prismatic interfaces in Mg single crystals

Q Zu and XZ Tang and SA Xu and YF Guo, ACTA MATERIALIA, 130, 310-318 (2017).

DOI: 10.1016/j.actamat.2017.03.035

The formation of the basal/prismatic (BP) interfaces during nucleation and growth of a reoriented crystal in Mg single crystals under c-axis tension is investigated by molecular dynamics simulations. The BP interfaces nucleate by a shuffling mechanism via local atomic rearrangement. Both two-layer disconnection and one-layer disconnection contribute to the migration of the BP interfaces. The three-dimensional analysis reveals that the two-layer disconnection forms at the junction between the partial pyramidal dislocation and BP interfate. The BP interfacial disconnections prefer to move towards the 1 (2) over bar 10 direction rather than the (1) over bar 010/0001 direction due to the accumulation of mismatches along the 1010/0001 direction. Moreover, the BP interface can transform to the 10 (1) over bar2 twin boundary and vice versa. The transformation from a BP interface to a twin boundary occurs through the diagonal pile-up of BP interface disconnections, and the reverse transformation involves an upright pile- up process. Both BP transformation and 10 (1) over bar2 twinning can effectively accommodate the applied tensile strain along the c-axis. The co-existing BP interfaces and 10 (1) over bar2 twin boundaries allow for large deviations of a twin interface from the 10 (1) over bar2 twin plane. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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