Transmission electron microscopic observations of the dislocation sub-structure in fine-grained polycrystals, fatigued at room temperature, were carried out in order to investigate correlations between the surface morphology and the underlying dislocation sub-structure. The results indicated that samples which were fatigued under a constant plastic strain amplitude, well into the saturation region, developed a small-scale surface roughness. The volume fraction of persistent slip-band type structures was extremely low. Persistent slip-band structures which were formed by the predominant slip system were observed only within narrow twin grains, and were associated with an extrusion-like surface profile. The results were explained in terms of a size effect, that permitted one predominant slip system to operate in the plane parallel to a coherent twin boundary.

Dislocation Microstructures and Surface Morphology in Fatigued Fine-Grained Copper Polycrystals. H.Kawazoe, M.Niewczas: Philosophical Magazine, 2004, 84[3], 381-99