3D atomic-scale growth characteristics of 10-12 twin in magnesium
X Wan and J Zhang and XY Mo and FS Pan, JOURNAL OF MAGNESIUM AND ALLOYS, 7, 474-486 (2019).
In this work, we carried out three-dimensional (3D) atomic-scale study on the growth characteristics of 10-12 twin in magnesium (Mg). The study was performed by MD simulations on Mg single crystals with an initial twin nucleus structures. A detailed atomistic analysis reveals that a stabilized 3D 10-12 twin nucleus is bounded by basal/prismatic (BP) interfaces, prismatic/basal (PB) interfaces, and 10-11 interfaces. Later, a 10-12 twin boundary (TB) occurs at the junction of the BP and PB interface with the growth of the twin nucleus. In this process, two twinning mechanisms are involved: a pure-shuffle mechanism in which 10-11 interface migration along the 11-20 direction is mediated by atomic shuffle, and a glide-shuffle mechanism in which BP/PB and 10-12 TB movements are realized by the migration of disconnections along the relevant interfaces. In addition, we systematically investigate the stress state associated with the activation of twinning, aiming to discover the intrinsic relationship of the elastic stress field to twin growth on an atomic scale. The results suggest that the elastic stress in the matrix is an important driving force for twin growth, much similar to what stress does for a crack. In addition, it is rather remarkable that the 10-11 interface has a greater ability to migrate than other interfaces, and this is thought to be a main factor for the rapid growth of a 10-12 twin. (C) 2019 Published by Elsevier B.V. on behalf of Chongqing University.
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