Formation of {1 1 2¯ 1} twins in polycrystalline cobalt during dynamic plastic deformation

The formation mechanism of the {112¯1} deformation twins in polycrystalline cobalt during dynamic plastic deformation has been proposed in this paper. It is found that the dislocation reactions play important roles in the nucleation and growth of {112¯1} deformation twins. The basal dislocations dissociate into sessile partials pinned at the intersection of two {112¯1} planes and glissile partials glided to nucleate twins on the (0 0 0 2) planes during the deformation. With the help of the applied stress, the dislocation reactions can be repeated, resulting in the formation of {112¯1} deformation twins.

► We have proposed the formation mechanism of the {1 1 2¯ 1} twins in polycrystalline Co.
► Dislocation reaction plays important role in the nucleation and growth of {1 1 2¯ 1} twins.
► The basal dislocations dissociate into sessile partials and glissile partials.
► Sessile partials pin at intersection of the two {1 1 2¯ 1} planes.
► Glissile partials glide to nucleate twins on the (0 0 0 2) planes.