Formation of grains and dislocation structure of geometrically necessary boundaries

TL;DR

This paper proposes a continuum dislocation model explaining the formation of grain structures with finite-thickness boundaries, showing lamellar structures are energetically favorable in simple shear deformation.

Contribution

It introduces a novel continuum dislocation model for grain boundary formation with finite thickness, analyzing energy and thickness dependence on misorientation angle.

Findings

Lamellar grain structures are energetically preferable in simple shear.

Boundary thickness and energy depend on misorientation angle.

Model predicts finite boundary thickness in grain formation.

Abstract

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 turns out to be energetically preferable. The thickness and the energy of this type of grain boundary are computed as functions of the misorientation angle.