Accommodation and formation of {(1)over-bar012} twins in Mg-Y alloys

The {(1) over bar 012} tensile twins terminating inside the grains of a deformed Mg-Y alloy were investigated by transmission electron microscopy. The crystallographic features of terminating twins and associated slip structures were quantified and correlated. The local stresses developed at a terminating {(1) over bar 012} twin were computed using crystal plasticity simulations in order to interpret the observed slip patterns. Results indicate that both basal < a > and < c + a > matrix glide were involved in accommodating the plastic stresses developed in the vicinity of terminating twins. Along the twin boundary, the defect contrast consistent with that of lattice dislocations and twinning partials was observed. Based on these observations, a dislocation reaction is proposed that establishes an interrelationship between the observed matrix glide and {(1) over bar 012} twinning in Mg-Y alloys. (c) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

This study investigated {(1) over bar 012} tensile twins terminating inside the grains of a deformed Mg-Y alloy using transmission electron microscopy. Crystallographic features of the terminating twins and associated slip structures were quantified and analyzed, with local stresses computed using crystal plasticity simulations. Basal < a > and < c + a > matrix glide were found to accommodate the plastic stresses near the terminating twins, with defect contrast consistent with lattice dislocations and twinning partials observed along the twin boundary. A dislocation reaction was proposed to establish the interrelationship between matrix glide and {(1) over bar 012} twinning in Mg-Y alloys.