Projekt

The addition of rhenium as a potent solid solution strengthener in nickel-base superalloys remarkably improved the mechanical properties of these alloys in the last ten years. Nevertheless, as rhenium additions affect not only solid solution hardening but also different other alloy properties like lattice mismatch and precipitate morphology, to mention just two examples, a complete understanding of rhenium effects in nickel-base superalloys has not been achieved yet. In this project, microstructural investigation methods with high lateral resolution like convergent beam electron diffraction (CBED) and energy dispersive spectroscopy in the transmission electron microscope at our institute are combined with atomic force microscopy (AFM) and nanoindentation measurements at the University of the Saarland in Saarbrücken in order to investigate a variety of alloy properties which are affected by rhenium additions. Examples are the local chemical composition, the local lattice parameters, the nanohardness and the local elastic moduli. Since the studies are performed on the same alloy and at identical specimen locations at our institute and the partner institute in Saarbrücken, the results can be correlated. Thus, a complete picture of the influence of rhenium on all the mentioned alloy properties can be achieved. While effects of rhenium as one of the most important alloying elements in modern nickel-base superalloys are of special interest, effects of other refractory elements like tantalum or ruthenium will also be investigated.