2D dislocation dynamics in thin metal layers

The paper deals with a discrete dislocation dynamics study of plastic deformation in a thin film caused by thermal mismatch with its substrate. A unit cell analysis is carried out, with dislocations in the film being represented by line singularities in an isotropic linear elastic medium. Their mutual interactions as well as the interactions with the interface and the free surface are accounted for by means of a coupled dislocation dynamics-finite element technique. The formulation includes a set of constitutive rules to model generation, glide, annihilation and pinning of dislocations at point obstacles. The simulation tracks the evolution of the dislocation structure as thermal stress builds up as well as during relaxation under constant temperature, leading to dense dislocation distributions near the interface and a dislocation-free zone along the stress-free surface of the film.