Atom probe tomography of secondary γ′ precipitation in a single crystal Ni-based superalloy after isothermal aging at 1100 °C

•Bimodal size distribution of γ′ precipitates occurs after isothermal aging at 1100 °C.•Characterization of secondary γ′ by atom probe tomography.•It is proposed that the secondary γ′ occurs via a non-classical nucleation.•The coarsening of secondary γ′ precipitates well obeys the classical LSW theory.

Secondary γ′ precipitation in a commercial single crystal Ni-based superalloy after the 1100 °C isothermal aging has been investigated by atom probe tomography. After the isothermal aging for 300 s, 1800 s and 3600 s, a bimodal size distribution of larger primary γ′ precipitates and numerous smaller secondary γ′ precipitates was obtained. It is proposed that the secondary γ′ precipitated via a non-classical nucleation mode. The coarsening of secondary γ′ precipitates well obeys the classical LSW theory.

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