The Stray Grains from Fragments in the Rejoined Platforms of Ni-Based Single-Crystal Superalloy

Nickel-based single crystal superalloy is the most important material for blade preparation. However, some solidification defects inevitably occur during process of preparing single-crystal blades through directional solidification. In this study, in order to study origin misorientation solidification, a model with rejoined platforms was designed according geometry guide vanes. Electron Back-Scattering Diffraction (EBSD) used quantify orientation deviation dendrites and identify platforms. The results showed that stray grain appeared their changed gradually, not abruptly. Combined simulation results, it proposed grains formed as result fragment, which induced by solute enrichment mushy zone Meanwhile, accompanied obvious dendritic deformation, caused shrinkage stress. This suggested fragmentation multiple factors, among which, concave interface shape provided favorable conditions enrichment, dynamic variability local thermal gradient fluctuations rate might play catalytic roles.