Solute segregation at the stacking faults in the γ phase of Ni-based single crystal superalloys

Creep deformation at intermediate temperatures and high-stress conditions in a second-generation Ni-based superalloys occurs by continuous shearing of γ and γ' phases that lead to the formation of a high number density of stacking faults (SFs). Solute segregations to these faults highlight that their diffusivities play a critical role as creep rate limiting solutes. Although most of the earlier works focus on solute segregations to SFs inside γ', in this work, we show evidence of Re and W segregation at the SFs in the γ matrix phase by atomic-scale analysis using atom probe tomography. Based on the observations, we derive possible solute diffusion mechanisms along the SFs that contribute to a new understanding of creep deformation and their dependence on the specific solutes, especially Re and W in the alloy.