Simulation of X-ray diffraction-line broadening due to dislocations in a model composite material

X-ray diffraction-tine profiles of two-dimensional, plastically deformed model composite materials are calculated and analysed in detail. The composite consists of elastic reinforcements in a crystalline solid and is subjected to macroscopic shear. Slip occurs in the matrix only due to the collective motion of discrete dislocations on a single set of parallel slip planes. The results of dislocation dynamics computations are used as input for the calculation of the line profiles. The line profiles are computed directly using the kinematics approach, without making a priori assumptions on the dislocation distributions. Two steps are required. First, the fall intensity distribution of a single crystal of composite material is calculated. Then, assuming a perfectly random orientation distribution of such single crystals, powder diffraction-line profiles are determined. Results will be presented for several orders of reflection and in different crystallographic directions. The broadening of the line profiles is shown to be not only determined by the density of dislocations, but also by their spatial distribution. (C) 2001 Elsevier Science B.V. All rights reserved.