X-ray texture tomography of near-surface areas

The author’s aim was to develop a research tool for non-destructive investigation of space arrangement of crystallites in the near-surface areas of structural elements and materials of gradient or laminar structure. Such composites are as a rule structurally inhomogeneous and are numbered among modern class so called functionally graded materials. Their physical properties depend to a great extent on crystallographic texture, the effective analysis of which can be carried out only in a way not disturbing the subtle arrangement of the layers, formed most often deliberately in a technologically advanced process.The X-ray texture tomography, described in the study and verified experimentally, represents a non-invasive method of investigating the texture of the near-surface areas on X-ray penetration depth, usually up to 100 μm. It allows to localise the texture changes occurring under the sample surface to a certain definite depth.X-ray texture tomography consists in the registration of the diffraction effects according to a definite method and their transformation according to the developed procedure utilising the available calculation methods. As a result an information set is obtained helpful at the interpretation of various structural effects, quality control of deposited coatings and in designing the production technology of new materials of specific properties. Using texture tomography it is possible to investigate such problems as; anisotropy of physical properties, inhomogeneity and heredity of texture, distribution of residual stresses, fatigue wear of surface.In spite of some limitations, the described method adds the missing element to make the set of the research tools of the microstructure and supplements the electron microscopy wherever the scale of the examined phenomenon is beyond the nano-metric area. An essential of this research procedure is the possibility of its automatisation which facilitates its application not only in scientific laboratories but also in industry.Introduced classification of texture inhomogeneity made on the basis of the authoritative components, the methods of its evaluation and a precise measure of this effect, defined as the degree of inhomogeneity, makes complete the developed method of texture tomography.Experience gained by the author in the course of elaborating and practical application of the described method at the research laboratory of the Aleksander Krupkowski Institute of Metallurgy and Materials Science of the Polish Academy of Sciences (IMMS PAS) in Krakow has made him believe that texture inhomogeneity and its heredity are still not adequately studied areas of structure analysis considering their importance for the present-day materials engineering. It is expected that X-ray texture tomography will contribute to the knowledge in this field.