Formation of <0001>-rotation-type kink boundary in Mg–Zn–Y alloy with long-period stacking ordered structure

Highlights: • Kink deformation with lattice rotation around the axis occurs in Mg-Zn-Y alloys at a temperature higher than 673 K. • The -rotation-type kink boundary comprises prismatic a> edge dislocations with the same Burgers vector. • The geometrical softening effect is significant despite the kink band formation stimulated by the prismatic slip system. The dislocation configuration around the -rotation-type kink bands/boundaries formed in extruded Mg₈₉Zn₄Y₇ alloys with a long-period stacking ordered structure was investigated by an intragranular misorientation axis analysis and a g• b study. The g• b analysis suggests that the -rotation-type kink boundary with small tilt angles comprises prismatic a> edge dislocations. The tendency of kinking with lattice rotation around the axis to activate at temperatures higher than 673 K can be explained by the temperature dependence of the critical resolved shear stress of prismatic a> slips. The kink bands arising from the activation of the prismatic a> slip system are numerically reproduced by a crystal plasticity finite element analysis. Geometrical softening should be significant despite kink-band formation stimulated by the prismatic slip system.