Why are 10(1)over-bar2 twins profuse in magnesium?

H El Kadiri and CD Barrett and J Wang and CN Tome, ACTA MATERIALIA, 85, 354-361 (2015).

DOI: 10.1016/j.actamat.2014.11.033

We show that 10 (1) over bar2 twinning in magnesium acts as an effective sink of basal dislocations without loss of mobility. The lattice dislocation decomposes into the b(0/0)(BP) dislocation recently identified by the present authors, and a residual dislocation. The b(0/0)(BP) dislocation in turn spontaneously decomposes into a Burgers vector content of the basal-prismatic facet related disclination dipole, f(0)(BP), plus an associated number of twinning disconnections. The residual dislocation lies on the basal-prismatic facet and thus remains glissile should the twin boundary move forward or recede back. Importantly, the basal-prismatic facet absorbs any twinning disconnection gliding on one side of the twin boundary and releases another one to other side, thereby enabling the twin boundary to progress through a forest of basal dislocations with no apparent decrease in mobility or loss of coherency. This mechanism explains why 10 (1) over bar2 twinning is profuse in hexagonal close-packed metals as slip induces the interfacial atomic structure to change favorably for twin propagation. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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