MICROBEAM X-RAY-DIFFRACTION STUDIES OF STRUCTURAL-PROPERTIES OF POLYCRYSTALLINE METALS BY MEANS OF SYNCHROTRON-RADIATION

A 100 mu m x 4 mm fine beam was applied at the 9.1 high resolution pow der diffraction (HRPD) station of the CLRC Daresbury Laboratory to sca n an individual grain from grain-boundary to grain-boundary in a tensi le deformed coarse grain copper specimen. Diffraction profiles (theta- 2 theta) and rocking curves enabled a comprehensive analysis to be mad e of the intensity distribution around a fundamental Bragg reflection as a function of position in the specimen. The dislocation densities w ere found to be larger near the grain-boundary region than in the cent ral parts of the grain. The dislocation-arrangement parameter M was fo und to be smaller in the grain-boundary region than in the centre of t he grain, indicating an increased dipole character in the grain-bounda ry region. The rocking curves were wider near the grain boundaries tha n in the central region indicating larger misorientations between subg rains in this region at the strain level investigated here. (C) 1998 E lsevier Science S.A. All rights reserved.