Papers by Author: Klaus J. Martinschitz

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Authors: Klaus J. Martinschitz, Ernst Eiper, Jozef Keckes
Abstract: A new method is presented which allows the determination of experimental stress factors in anisotropic thin films on the basis of static diffraction measurement. The method is based on the simultaneous characterization of macroscopic stress and elastic strain in thin film using substrate curvature and sin2ψ methods, respectively. The curvature of monocrystalline substrate with known mechanical properties is determined using rocking curve measurements on substrate symmetrical reflections. The experimental stress and strain values are used to calculate stress factors for the specific film as a function sample tilt angle and reflection measured. The approach represents a relatively simple recipe to determine residual stress magnitude in thin films on the absolute scale. The procedure is demonstrated on polycrystalline Cu thin film deposited on Si(100).
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Authors: Klaus J. Martinschitz, C. Kirchlechner, R. Daniel, G. Maier, C. Mitterer, Jozef Keckes
Abstract: A temperature behaviour of residual stresses in shot-peened steel coated with 3m CrN is characterized using in-situ energy dispersive synchrotron X-ray diffraction performed in the temperature range of 25-800°C. The samples are thermally cycled and the development of volumeaveraged residual stresses in the coating and residual stress depth gradients in the steel is characterized. The results reveal complex changes of stresses in CrN and in the substrate. The annealing results in the removal of stress gradients in the steel which starts at the temperature of about 600°C. After cooling down, there are no stresses detected in the steel. The temperature dependence of stresses in CrN is very complex and indicates the presence of phenomena like an annealing of intrinsic stresses about the deposition temperature of 350°C, a formation and a closing of micro-cracks in the tensile region and finally a stress relaxation of approximately 500 MPa after the cooling down. The presented approach allows a complex characterization of thermo-mechanical processes in coating-substrate composites and opens the possibility to understand phenomena related to the thermal fatigue of coated tools.
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