Cyclic deformation of a [¯4 15 20]-[18 ¯2 7] bicrystals, with a tilting Σ = 19b grain boundary, was investigated for axial plastic strains ranging from 1.5 x 10-4 to 2.13 x 10-3 at room temperature in air. The primary slip planes, (111), within the G1[¯4 15 20] and G2[18 ¯2 7] grains of the bicrystal were designed to be coplanar in order to reveal the interaction of slip bands with the grain boundaries. The results showed that the cyclic stress-strain curve of the bicrystal exhibited a plateau region at axial saturation stresses of 61.6 to 63.5MPa. This result was similar to that for single-slip oriented Cu single crystals; thus indicating that the grain boundary had little effect upon the saturation stress. It was found that only the primary slip system was activated in both grains. Secondly, the primary slip bands on the 4 surfaces of the 2 grains exhibited a good 1-to-1 relationship across the grain boundary; thus indicating that surface slip bands could transfer through it. Thirdly, secondary slip systems were not activated; even in the vicinity of the grain boundary. Dislocation patterns were observed by using the electron channelling contrast technique. A 2-phase structure of persistent slip bands and veins formed in both grains. Ladder-like persistent slip bands were observed to transfer through the grain boundary continuously on one surface of the bicrystals, but piled-up at the grain boundary on the other surface; thus leaving a discontinuous dislocation distribution next to the grain boundary. Several kinds of interaction between dislocations and the grain boundary were observed on the common slip plane.

Cyclic Deformation Behaviour of a Copper Bicrystal with Common Primary Slip Planes. Z.F.Zhang, Z.G.Wang: Philosophical Magazine A, 2001, 81[2], 399-415