Whole powder pattern decomposition - An application for the evaluation of residual stress states in consideration of steep stress gradients

•Calculation of residual stresses in thick coatings•Adaption of pattern refinement strategy on the depth resolved•Information content•Effect of distinctive stress gradients resolvable•Results confirmed by classical ω-stress, single peak analysis and pattern modelling

The whole powder pattern decomposition procedure is an established tool for the analysis of diffraction patterns with overlapping reflections. Its adapted application to data obtained in asymmetric diffraction geometry was shown to yield depth-resolved results of biaxial residual stress states, e.g. of thin film materials. Yet, with increasing coating thickness and in presence of pronounced stress gradients, this approach overestimates the magnitudes of the residual stresses present. The current work aims at overcoming this by including the variations in X-ray penetration depth encountered during the experiment into the applied refinement strategy. A proof of concept is obtained by measuring stress states in molybdenum thin films as a model material using the proposed approach in comparison to classical X-ray residual stress evaluation techniques.