Plastic deformation of thin metal films was investigated with the help of a discrete dislocation dynamics simulation. In particular, the operation of a Frank-Read source was studied in the confined geometry of a thin polycrystalline film. The results led to a new model for the dependence of flow stress on film thickness and grain size. It was based on the assumption that the number of dislocation sources per grain was small and multiple activation was required. The model predicts a flow stress that scales with the inverse film thickness or grain size (whichever was smaller) and that was roughly 4 times higher than predicted by previous models, thereby giving better agreement with experimental data.

Dislocation Sources and the Flow Stress of Polycrystalline Thin Metal Films. B.von Blanckenhagen, P.Gumbsch, E.Arzt: Philosophical Magazine Letters, 2003, 83[1], 1-8