X ray diffraction analysis of nonuniform residual stress fields sigma ii tau under difficult conditions

Thin hard coatings for wear protection usually do not consist of single layers but of stacks of alternating sublayers which have to meet different demands. With respect to X ray residual stress analysis XSA such multilayer systems pose a series of challenges. In addition to those problems which generally arise in thin film diffraction like small layer thickness or strong texture, neighbouring sublayers with similar chemical composition may superimpose each other, or sublay ers of identical structure and composition, which contribute to the same diffraction line, are sepa rated by other sublayers. Starting from a formalism that yields the X ray penetration depth tau in mul tilayer systems of arbitrary sublayer sequences we show, how a combination of measurements using conventional photon sources available in any X ray lab and synchrotron radiation allowing for wavelength tuning near the TiKbeta absorption edge, can be used to evaluate the residual stress state in the top sublayer stack of a hard coating multilayer system deposited by chemical vapour depositio