An analysis of measurement of solute segregation in Ni-base superalloys using X-ray spectroscopy

The extent of solute segregation in a multi-component Ni-base superalloy, IN713LC, is analysed using X-ray spectroscopy techniques. It is demonstrated in this study that such an analysis is strongly influenced by the volume averaging of γ and γ′ phases sampled by the electron beam; the γ′ having precipitated from the γ phase below the γ′ solvus temperature in the solid-state. It is found that the size of the precipitate (γ′) in relation to the interaction volume is crucial; volume averaging is dominant when the precipitate size (γ′) is comparable to the interaction volume. Accurate interpretation of the measurements is essential when they are used to infer the micro-segregation and solute partitioning during solidification. Implications of this analysis in the assessment of segregation during solidification in Ni-base superalloys are addressed.