3D simulation of the dislocation dynamics in polycrystalline metal thin films

The plastic deformation of polycrystalline fcc metal thin films with thick-ness of 1 µm and less is investigated by simulating the dynamics of discrete dislocations in a representative columnar grain. The simulations are based on the assumption that dislocation sources or multiplication sites are rare and that sources have to operate several times to generate appreciable plastic deformation. This model is thoroughly tested by calculating the response of randomly distributed dislocation sources to an applied stress and comparing the results with experimental data. Stress-strain curves, the influence of boundary conditions, dislocation densities, work hardening rates and their dependence on the film thickness as well as the dependence on grain orientation are studied. The agreement between simulation and experiment is good and many aspects of thin film plasticity can be understood with the assumption that small-scale plastic deformation is source controlled rather than mobility controlled