Multi-scale characterization of stray grain in the platform of nickel-base single crystal turbine blade

Through comparatively characterizing the platforms with and without stray grain in multi-scale levels, it is determined that stray grain (SG) originates from heterogeneous nucleation with randomly distributed orientations with respect to the matrix grain. This independently nucleated deleterious grain constitutes distinct macro, dendritic and γ′ morphologies and forms a high angle boundary (HAB) in the conjunction area of SG and the matrix grain. Compositional distribution reveals that severe segregation could be identified in GB area due to compositional enrichment and deprivation during the last stage of solidification.