Grain size, size-distribution and dislocation structure

Diffraction peak profile analysis (or Line Profile Analysis, LPA) has recently been developed to such an extent that it can be applied as a powerful method for the characterization of microstructures of crystalline materials in terms of crystallite size-distribution and dislocation structures. Physically based theoretical functions and their Fourier coefficients are available for both, the size and the strain diffraction profiles. Strain anisotropy is rationalized in terms of the contrast factors of dislocations. The Fourier coefficients of whole diffraction profiles are fitted by varying the following fundamental parameters characterizing the microstructure: (i) m and (ii) V, the median and the variance of the log-normal size distribution function, (iii) U and (iv) M, the density and the arrangement parameter of dislocations and (v) q or q1 and q2 for the average dislocation contrast factors in cubic or hexagonal materials, respectively. The method will be illustrated by showing results on ECA pressed copper and titanium.