Papers by Author: Karen Pantleon

Abstract: Transformation Induced Plasticity (TRIP) steels have not yet been successfully joined by any welding technique. It is desirable to search for a suitable welding technique that opens up for full usability of TRIP steels. In this study, the potential of joining TRIP steel with Friction Stir Spot Welding (FSSW) is investigated. The aim of the study is to investigate whether acceptable welds can be produced, and additionally, to obtain an understanding of the microstructural changes during welding. The microstructure was investigated with a combination of microscopical techniques with the aim of identifying the transformations occurring during welding. Reflected light microscopy, scanning electron microscopy, and electron backscatter diffraction were among the methods applied for detailed investigations. The microstructure adjacent to the welds can generally be subdivided in two thermo-mechanically affected zones (TMAZ), and two heat-affected zones (HAZ). The dual behavior of the microstructure in the zones is related to the two transition temperatures in steel: A₁ and A₃. In parts of the TMAZ the microstructure contains ultra fine-grained ferrite. This finding parallels the observation in thermo-mechanically processed steels, where severe deformation at elevated temperatures is used to produce ultra fine-grained microstructures. Several possible transformation mechanisms could in principle explain the development of ultra fine-grained ferrite, e.g. dynamic recrystallization, strain-induced ferrite transformation and dynamic recovery.

Abstract: Free-standing line patterns of Cu and Ni were manufactured by electrochemical deposition into lithographically prepared patterns. Electrodeposition was carried out on top of a highly <111> oriented Au-layer physically vapor deposited on glass. Quantitative texture analysis carried out by means of X-ray diffraction for both the substrate layer and the electrodeposits yielded experimental evidence for epitaxy between Cu and Au. An orientation relation between film and substrate was discussed with respect to various concepts of epitaxy. While the conventional mode of epitaxy fails for the Cu-Au-system, it is shown that the experimentally observed orientation relation can be conceived as a 30º rotation of Cu (111) grown on Au (111) (rotational epitaxy).

Abstract: Copper layers were deposited from acidic electrolytes containing different amounts of organic additives, designed for the formation of Cu-interconnect structures. Amorphous Ni-P substrates allow to study the unbiased growth of the electrodeposits. The crystallographic texture was investigated by the determination of X-ray diffraction (XRD) pole figures and the calculation of the orientation distribution functions. XRD results are discussed in relation to the morphologies of the electrodeposits as investigated with light optical microscopy and correlated with the process parameters during electrodeposition.