Cyclic deformation of a bicrystal with a perpendicular grain boundary was performed at room temperature, using a constant plastic strain amplitude of 1.5 x 10−3. The dislocation structure evolution in a typical deformation band, as opposed to persistent slip bands, was observed after various cycles by means of electron channelling contrast in a scanning electron microscope. It was found that a micro-crack nucleated preferentially at the interface between the matrix and the second type of deformation band; the habit plane of which was close to the conventional kink plane, {101}, in the vicinity of the grain boundary. It then propagated along the second type of deformation band. The dislocation structures of the transgranular and intergranular crack tips were also observed. The main dislocation structure near to the crack tip was the cell structure.

Dislocation Structure Evolution of Deformation Band and Crack Formation in a Copper Bicrystal with a Perpendicular Grain Boundary. Y.Li, S.X.Li, G.Y.Li: Materials Science and Engineering A, 2004, 372[1-2], 221-8