Plastic deformation and twin interfaces in hexagonal metals

The deformation twins are important with respect to limited number of dislocation modes in hexagonal crystals due to lower symmetry. Conjunction of experimental observations with theoretical models is beneficial for their study. We have demonstrated that the same physical reasons lead to appearance of secondary twins in metals (zinc and magnesium) with a qualitative difference of c/a ratio. c and a are the lattice parameters. In addition to symmetric twin boundaries, the matrix and twin are also separated by the interfaces between basal and prismatic planes. This interface can be described by a row of alternating dislocations with the Burgers vectors perpendicular to these two planes as shown in figure below.

Description

Junction of the symmetric twin boundary with the basal/prismatic interface. Dashed lines are parallel to the basal planes in the matrix and twin.