In situ X-ray diffraction peak profile analysis during plastic deformation in  oriented copper single crystals was carried out using synchrotron radiation. Characteristic changes of the hardening coefficient indicate that a transition occurs from stage III to stage IV which has been observed for the first time in a single crystal under low temperature deformation conditions. The long-range internal stresses, the dislocation arrangement parameters and the fluctuations of the dislocation density show non-monotonous changes at this transition suggesting that the dislocation structure, especially within the cell-wall regions, reveals a second-order phase transition. A microscopic dislocation model is introduced which not only illustrates the break of symmetry, but also describes well the development of new grains ("fragmentation") during plastic deformation.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Polymers and Plastics
- Metals and Alloys