Microbeam X-ray diffraction studies of structural properties of polycrystalline metals by means of synchrotron radiation

A 100 μm×4 mm fine beam was applied at the 9.1 high resolution powder diffraction (HRPD) station of the CLRC Daresbury Laboratory to scan an individual grain from grain-boundary to grain-boundary in a tensile deformed coarse grain copper specimen. Diffraction profiles (θ–2θ) and rocking curves enabled a comprehensive analysis to be made of the intensity distribution around a fundamental Bragg reflection as a function of position in the specimen. The dislocation densities were found to be larger near the grain-boundary region than in the central parts of the grain. The dislocation-arrangement parameter M was found to be smaller in the grain-boundary region than in the centre of the grain, indicating an increased dipole character in the grain-boundary region. The rocking curves were wider near the grain boundaries than in the central region indicating larger misorientations between subgrains in this region at the strain level investigated here.