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Free keywords:
Heat treatment; High resolution transmission electron microscopy; Lattice mismatch; Scanning electron microscopy, Atom-probe tomography; Cast and wrought; Chemical characterization; Micro-structural characterization; Ni-based superalloys; Precipitate size; Scanning and transmission electron microscopy; Turbine engine components, Nickel alloys
Abstract:
Cast and wrought Ni-based superalloy Rene 65 was developed for turbine engine components applications. In the as-extruded condition the alloy presents trimodal distribution of gamma prime (γ′) precipitates. A detailed microstructural and chemical characterization of the precipitates is presented at a near atomic-scale before and after a softening sub-solvus heat treatment. Scanning and Transmission Electron Microscopy (SEM and TEM) as well as Atom Probe Tomography (APT) were employed to identify the differences in compositions. In the as received condition differences in Cr, Ti and Al content were found between the three precipitate sizes. After a softening sub-solvus heat treatment, the interface between secondary and grown tertiary γ′ with the matrix had become chemically homogenized. Lattice mismatch of secondary and tertiary γ′ were empirically calculated based on the APT compositions. © 2020 Elsevier Inc.
