|About this Abstract
||2021 TMS Annual Meeting & Exhibition
||Characterization of Minerals, Metals and Materials 2021
||Crystal Mosaicity and Local Alloy Chemistry of Low Angle Grain Boundaries in Ni-based Superalloys
||Felicitas Scholz, Junyang He, Oliver Martin Horst, Pascal Thome, Gunther Eggeler, Baptiste Gault, Jan Frenzel
|On-Site Speaker (Planned)
We report on the formation of crystal mosaicity during seeded single crystal Bridgman solidification and heat treatments of Ni-based superalloys, and its impact on the local alloy composition. In general, single crystals contain low angle misorientation defects referred to as crystal mosaicity. These small sub-grains with misorientations up to a few degrees are inherited from the dendritic growth process. We combine a new tomographic serial sectioning method, cross-correlation based electron back scatter diffraction and atom probe tomography to provide microstructure and local alloy composition analysis. We show that the presence of low angle grain boundaries (LAGBs) between slightly misoriented dendrites is associated with segregation phenomena. For the first time, rhenium segregation is reported for the as-cast and heat-treated states. Rhenium segregate to the dislocation networks building up LAGBs. We discuss our results in light of the present understanding of how rhenium partitions during processing and how it interacts with dislocations.