In order to improve our understanding of the link between the cyclic deformation of single crystals and of polycrystalline materials, a study was performed on copper bicrystals. Testing under strain control within the high cycle regime was performed in isoaxial [1̄49] (90° and 180°) twist boundaries and [1̄49]/ bicrystals, all with boundaries perpendicular to the tensile axis. A Grain Boundary Affected Zone (GBAZ), where multiple slip dominated, appeared when the boundaries developed compatibility stresses. Experiments showed that the behavior of macroscopically compatible bicrystals, 180° boundaries, is approximately similar to that of a monocrystal, whereas the fatigue responses of the other misorientations show a grain boundary effect, which increases the cyclic stress. The strain in each grain of the [1̄49]/ sample was measured separately. The plastic deformation in the adjacent crystals oscillated during initial hardening; finally, the soft grain carried approximately five times the plastic strain of the other grain.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Polymers and Plastics
- Metals and Alloys