Phenomenon of extinction in textured materials analysis as a source of both physical error and information on microstructure characteristics Original Research Article

The correction of pole density in the analysis of textured materials by means of an original X-ray diffraction technique is proposed. In the framework of the conventional model of mosaic crystals and the dynamic theory of X-ray diffraction, a method for the separation and determination of the primary and secondary extinction parameters is developed. From these parameters, microstructural features in textured materials, such as the average domain size, the domain misorientation angle and the dislocation density at the domain boundaries are evaluated. The essential influence of the extinction phenomenon on the directly calculated pole densities and the incorrect interpretation of the texture modifications is demonstrated for the case of aluminum samples after cold rolling and different stages of thermal annealing. Conventional determination of the pole densities for low-index reflections shows a decrease in their magnitudes after the first and second stages of recrystallization; on the contrary, second-order reflections indicate an increase in the pole densities. Extinction corrections remove this inconsistency.