Formation of grains and dislocation structure of geometrically necessary boundaries

A continuum dislocation model of formation of grains whose boundaries have a non-vanishing thickness is proposed. For a single crystal deforming in simple shear the lamellar structure of grains with thin layers containing dislocations as the geometrically necessary boundaries turn out to be energetically preferable. The thickness and the energy of this type of grain boundary are computed as functions of the misorientation angle.