Non-diffusional growth mechanism of I1 basal stacking-faults inside twins in hcp metals

Deformation twins in magnesium exhibit considerable densities of I-1 basal-plane stacking-faults. Since these faults generally transect their host twin, they presumably lengthen concommitantly with boundary migration during twin growth. We investigate this process using atomic-scale simulation for {10 (1) over bar2} and {10 (1) over bar1} twinning. It is demonstrated first that the intersection of a stacking-fault with a stationary twin boundary is delineated by a sessile imperfect disconnection. Subsequently, by applying a shear strain, we stimulate twin growth by the passage of twinning disconnections along twin boundaries, and show that these are able to propagate through such pre-existing imperfect disconnections in a conservative manner. (C) 2019 Acta Materialia Inc Published by Elsevier Ltd. All rights reserved.