Abstract
The cyclic deformation behaviour of a [5913]-[579] copper bicrystal with a grain boundary (GB) approximately perpendicular to the stress axis was investigated under constant-plastic-strain control at room temperature in air. In particular, the bicrystal contains two single-slip-oriented component crystals. The results showed that the cyclic stress-strain curve (CSSC) of the bicrystal exhibited two plateau regions in the axial plastic strain range of 1.8 ′ 10−4-1.35 ′ 10−3 and 2.05 ′ 10−3-2.56 ′ 10−3 respectively. The corresponding plateau axial saturation stresses were about 62–64 MPa and 70–71 MPa. During cyclic deformation, only the primary slip system B4 (111)[101] within the two component crystals was activated including the vicinity of the GB at all the applied strain amplitudes. Meanwhile, it is found that the plastic strains carried by the [5913] and [579] grains are obviously different owing to the difference in their orientations. By means of the electron channelling contrast technique in scanning electron microscopy, the surface dislocation patterns of the bicrystal were observed. The dislocation patterns in the two grains also showed an apparent difference. Based on the experimental results above, the effect of crystal orientation on the CSSC, surface slip patterns and saturation dislocation configurations within two grains was discussed.