Röntgendiffraktometrische Ermittlung tiefenabhängiger Eigenspannungsverteilungen in Dünnschichtsystemen mit komplexem Aufbau

A formalism is developed, which extends the depth resolved X-ray residual stress analysis (XSA) on thin films to the case of multilayer systems. The method is based on the replacement of the classic information depth, which loses its physical meaning in the case of alternating sublayers, by an equivalence thickness model describing the residual stress state in each of the diffracting layers in a parametric form. The proposed formalism is independent from both the diffraction geometry and diffraction mode chosen for data acquisition and hence, exhibits a universal character. The method is applied to residual stress analysis on CVD-coated cemented carbide cutting inserts. Both angle and energy dispersive diffraction using conventional low energy X-ray sources and high energy synchrotron radiation, respectively, were applied to achieve sufficient sensitivity in the near surface region of the investigated Al2O3/TiCN multilayers as well as in the interfacial substrate region. By examples of practical relevance it is demonstrated, that the proposed formalism is suited for detecting both ‚intralayer‘ residual stress gradients within particular sublayers and ‚interlayer‘ residual stress gradients which extend over several sublayers of a multilayer system. It is shown, that the white beam method can be used for simultaneous analysis of the film stress as well as the near interface substrate residual stress state to the same degree. Thus, from the technological point of view the interesting possibility arises to apply energy dispersive diffraction to large sample series being necessary in process control and optimisation. The second focus of the thesis is on the development of a MATHEMATICA® package, by means of which X-ray residual stress analysis for arbitrary measurement set-up and layer geometry can be simulated based on the kinematic theory of diffraction. Two different fields of application, which are related to the experimental results, are examined. Thus, the causal connection between the steep residual stress gradients and asymmetric diffraction line broadening could be proved quantitatively. Further it is demonstrated, that the simulation of XSA-experiments is a valuable tool to study the feasibility of complex measuring problems and to reveal optimal approaches for their solution.