Computer simulation of X-ray diffraction patterns of nanocrystalline materials

X-ray diffraction patterns of nanocrystalline copper have been obtained by computer simulation. The influence of grain size, thickness and structure of grain boundaries and crystal lattice distortions on the X-ray diffraction patterns was studied using the kinematical theory of X-ray scattering. Such specific features of the X-ray patterns of nanocrystalline materials as a decreased maximum peak intensity, a displacement of the position of the centre of gravity of the peaks, a change in the profile and an increase in the background have been analysed. It is shown that these specific features can be explained not only by the effect of such structural factors as crystallite size and grain-boundary thickness but also, and principally, by the presence of elastic atomic displacements in the bulk of the crystallites owing to long-range stress fields of extrinsic grain boundary dislocations. The role of the crystallographic texture in the formation of X-ray diffraction patterns of nanocrystalline copper has also been investigated.