High strength, high hardening rates, and strong Bauschinger-like effects in thin films were attributed to constraints on dislocation motion and dislocation interactions. To understand these phenomena, dislocation interactions in (111) and (001) oriented single crystal face-centered cubic films were studied using dislocation dynamics simulations. Interactions on intersecting glide planes resulted in junction formation, annihilation, or attractive non-junction-forming configurations, while dislocations on parallel glide planes formed dipoles. The configurations adopted by interacting dislocations, and thus the strengths of the interactions, were found to be sensitive to the applied strain, film thickness, crystallographic orientation, and boundary conditions. Different interactions thus dominate film behavior in different ranges of film thickness and applied strain. Interactions were stronger on unloading than on loading. Interactions involving three or more dislocations were found to be different from pairwise interactions. The results suggested that simple analytical calculations were unlikely to describe film phenomena but that full 3-D simulations could be used to understand many features of thin film mechanical behavior.

Dislocation Interactions in Thin FCC Metal Films. P.Pant, K.W.Schwarz, S.P.Baker: Acta Materialia, 2003, 51[11], 3243-58