Analysis of stress gradients in physical vapour deposition multilayers by X-ray diffraction at fixed depth intervals

The objective of this article is to develop and apply a model for the design and evaluation of X-ray diffraction experiments to measure phase-specific residual stress profiles in multilayer systems. Using synchrotron radiation and angle-dispersive diffraction, the stress measurements are performed on the basis of the sin2ψ method. Instead of the traditional Ω or χ mode, the experiments are carried out by a simultaneous variation of the goniometer angles χ, Ω and φG to ensure that the penetration and information depth and the measuring direction φ remain unchanged when the polar angle ψ is varied. The applicability of this measuring and evaluation strategy is demonstrated by the example of a multilayer system consisting of Ti and TiAlN layers, alternately deposited on a steel substrate by means of physical vapour deposition.