The effects of grain orientation and plastic strain amplitude upon the saturated dislocation structure were studied, in individual grains of cyclically deformed polycrystals, by means of scanning electron microscopy; using electron back-scattering pattern techniques and the channelling contrast of back-scattered electrons. The main features of the dislocation configuration in a grain were found to be determined mainly by the crystallographic axial orientation of the grain. A labyrinth-like dislocation pattern was typical of grains with axial orientations near to [001]. A patch pattern existed in grains with a loading axis near to [011] and fragmented dislocation walls predominated in grains with a loading axis near to [¯111]. Grains with axial orientations in the central part of the stereographic standard triangle contained a bundle arrangement of dislocation structures. All 4 types of dislocation structure (but mainly bundle type) could occur; together with the ladder structure of persistent slip bands. Cell patterns were found to be a result of a modification of the bundle and patch configuration at high deformation amplitudes.

Dislocation Structures in Cyclically Deformed Nickel Polycrystals. C.Buque, J.Bretschneider, A.Schwab, C.Holste: Materials Science and Engineering A, 2001, 300[1-2], 254-62