Unveiling the Re segregation at γ/γ′ interface in Ni-based Superalloy

The distribution of Rhenium (Re) in a Ni-based single crystal superalloy is characterized and specified by atom probe tomography (APT) after different heat treatment (including long-term aging). At high temperatures (950-1100°C), the actual effective diffusion providing γ΄ coarsening is becoming much bigger than Re diffusion in γ matrix, consequently Re atoms are insufficient to diffuse away and keep accumulating, leading to forming segregation at γ/γ′ interface. While at low temperatures (800-900°C), the Re diffusion is capable to balance the effective diffusion for γ΄ coarsening. After introducing more alloys with different Re content and different aging temperatures, Re segregation is irrelevant to the Re content but highly temperature-dependent. These results provide a novel perspective on the comprehension of the Re effect on the γ΄ coarsening in Ni-based superalloy and will be valuable to both improving the γ/γ′ microstructure stability and designing high-performance superalloys.