X-ray diffraction line broadening under elastic deformation of a polycrystalline sample: An elastic-anisotropy effect

A homogeneous stress field imposed on a polycrystalline sample containing elastically anisotropic13; crystallites produces an inhomogeneous strain field. The average strain causes a shift of the13; diffraction-line position, and the variance of the strain is a measure of line broadening. Though the13; shift of the line is commonly observed, earlier attempts to measure the broadening caused by elastic13; anisotropy were not conclusive. In the article, expressions have been derived for the average strain13; and variance of strain for a polycrystalline sample cubic system! subjected to uniaxial elastic stress.13; The 310! and 222! lines of beta brass under an uniaxial load have been recorded using Co K aand13; Cu K aradiations, respectively. The average strain and variance of strain derived from the measured13; diffraction line profiles are in good agreement with those predicted by the theory. The present13; measurements provide conclusive evidence for the diffraction line broadening caused purely by13; elastic anisotropy. xA9; 2001 American Institute of Physics