Size Distribution of Grains or Subgrains, Dislocation Density and Dislocation Character by Using the Dislocation Model of Strain Anisotropy in X-Ray Line Profile Analysis

Abstract

Anisotropic strain broadening in X-ray line profile analysis means that the breadth or the Fourier coefficients of diffraction profiles are not a monotonous function of the diffraction angle. The lack of a physically sound model makes the interpretation of line broadening difficult or even impossible. Dislocations are anisotropic lattice imperfections with anisotropic contrast effects in diffraction. It has been suggested recently that anisotropic X-ray line broadening is caused by dislocations. The classical procedures of Williamson and Hall, and Warren and Averbach are suggested to be replaced by the modified Williamson-Hall plot and the modified Warren-Averbach method in which the modulus of the diffraction vector or its square, g or g ², are replaced by g ${\bar{C}^{{1/2}}}$ or g ² $\bar{C}$, respectively, where $\bar{C}$ are the average dislocation contrast factors. A straightforward procedure has been elaborated to separate size and strain broadening which enables to determine particle size and size distribution and the structure of dislocations in terms of dislocation densities and the character of dislocations in polycrystalline or submicron grain size materials.