X-ray determination of dislocation density and arrangement in plastically deformed copper

Using the kinematical theory of X-ray scattering by crystals with dislocati ons as developed by Krivoglaz et al. and Wilkens, the dislocation content o f compressed copper single and polycrystals was investigated by means of pr ofile analysis of selected diffraction peaks. Measurements of radial intens ity distributions I(2 theta) were performed with a double-crystal spectrome ter in the case of the single crystals and with conventional polycrystal di ffractometers in the case of the polycrystals. Additionally, the misorienta tions Theta occurring within the dislocation cell structure because of the accumulation of excess dislocations of one sign were investigated by means of rocking curves of the single-crystal reflections and by evaluation of el ectron backscattering patterns (EBSPs). Within a wide deformation range, th e mean total dislocation density rho(d) can be related well to the flow str ess via the Taylor relationship. Assuming a random distribution of the miso rientations Theta between adjacent dislocation cells, the evaluation of the rocking curves gives mean values [\Theta\] much smaller than those determi ned by EBSP analysis. For this reason, a model of a dislocation cell struct ure with restrictedly correlated misorientations, which leads to better agr eement of the X-ray and the EBSP data, is proposed.