Measurement of X-ray diffraction-line broadening induced by elastic mechanical grain interaction

Abstract

Various grain-interaction models have been proposed in the literature to describe the stress and strain behavior of individual grains within a massive aggregate. Diffraction lines exhibit a response to the occurrence of a strain distribution in the diffracting crystallites, selected by the direction of the diffraction vector with respect to the specimen frame of reference, by correspondingly induced diffraction-line broadening. This work provides a report of synchrotron diffraction investigations dedicated to the measurement of the experimentally observable diffraction-line broadening induced by external elastic loading of various polycrystalline specimens. The experimentally obtained broadening data have been compared with those calculated adopting various grain-interaction models. Although such grain-interaction models have been proven to accurately predict the average (X-ray) diffraction measured lattice strain, as derived from the diffraction-peak position, the present results have demonstrated that the extent of the diffraction-line broadening due to grain interactions, as calculated by employing these grain-interaction models, is much smaller than the experimentally determined broadening. The obtained results have vast implications for diffraction-line broadening analysis and the understanding of the elastic behavior of massive polycrystals.