Seminars and Events

Characterization of Ni- and Co-based superalloys using atom probe tomography

Date/Time: 16.09.2014. 2:00 p.m.
Place: Ruhr-Universität Bochum, Bochum, Germany

Pyuck-Pa Choi, Max-Planck-Institut für Eisenforschung, Düsseldorf

We use Atom Probe Tomography (APT) for studying elemental distributions and partitioning in Ni- and Co-based superalloys and for addressing two topics. The first topic is on the characterization of Co-Al-W-Ti-Ta superalloys. We detect partitioning of all solute elements (Al, W, Ti,Ta) to the γ'-phase. Local nanoindentation testing on γ'-precipitates and γ-channels show that there is a hardness increase of γ' upon alloying with Ti and/or Ta and that it can be ascribed to the substitution of Al and W atoms by these elements. The second topic deals with the effect of Ruon suppressing the formation of deleterious TCP phases in Ni-based superalloys. We comparatively study two different alloys, Astra 1-20 (Ru-free) and Astra 1-21 (1% Ru) upong long-term aging. We show that Ru partitions to the TCP and γ phase, while it does not alter partitioning of other alloying elements. No interfacial segregation is observed. Possible mechanisms of the “Ru effect” are discussed based on the APT data.

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