Papers by Author: Klaus Dieter Liss

Abstract: In response to the development of new materials and the application of materials and components in new technologies the direct measurement, calculation and evaluation of textures and residual stresses has gained worldwide significance in recent years. Non-destructive analysis for phase specific residual stresses and textures is only possible by means of diffraction methods. The determination of global texture and the local variation of texture for example by inhomogeneous deformation are very important due to the coherence between the texture and the physical and mechanical properties of materials.

Abstract: High-energy synchrotron X-ray diffraction is a novel and powerful tool for bulk studies of materials. In this study, it is applied for the investigation of an intermetallic γ-TiAl based alloy. Not only the diffraction angles, but also the morphology of reflections on the Debye-Scherrer rings are evaluated in order to approach lattice parameters and grain sizes as well as crystallographic relationships. An in-situ heating cycle from room temperature to 1362 °C has been conducted starting from massively transformed γ-TiAl which exhibits high internal stresses. With increasing temperature the occurrence of strain relaxation, chemical and phase separation, domain orientations, phase transitions, recrystallization processes, and subsequent grain growth can be observed. The data obtained by high-energy synchrotron X-ray diffraction, extremely rich in information, are interpreted step by step.

Abstract: A new method to investigate thin wires has been tested, which is based on a special sample holder and on a high energy X-rays. Due to the high penetration power of high energy Xrays quantitative texture data will be obtained without any additional corrections such as constant volume correction and absorption correction. The measurements have been carried out at the high energy beam line BW5 at HASYLAB – DESY (Hamburg). In order to overcome grain statistics problems on the investigated Cu-wire of 122µm thickness a special scanning routine together with the sample preparation allows to average over a wire length between 1mm and up to 240 mm.