Unlocking the secrets of stress within thin films, this paper presents a new development in determining residual stresses in thin surface layers and coatings. The procedure, based on the grazing-incidence X-ray diffraction geometry (referred to here as the `g-sin2 ψ' geometry), enables non-destructive measurement at a chosen depth below the sample surface.
The penetration depth of the X-ray radiation is well defined and does not change during the experiment. The g-sin2 ψ geometry was applied for measurements of the residual stresses in TiN coatings. Anisotropic diffraction elastic constants of textured material were used to determine the stress value from the measured lattice strains.
The method is particularly useful for analyzing non-uniform stresses in near-surface layers. A new method of data treatment enables reference-free measurements of residual stresses. This advance has implications for materials science and engineering, enabling better characterization and optimization of thin films and coatings.
This paper on X-ray diffraction techniques, published in the Journal of Applied Crystallography, fits squarely within the journal's scope of presenting research on crystallographic methods and their applications. The development of a new approach to stress analysis aligns with the journal's focus on advancing techniques for materials characterization.