Simulating the effect of aluminizing on a CoNiCrAlY-coated Ni-base superalloy

Journal Article · 23 April 2019 · Calphad

DOI: https://doi.org/10.1016/j.calphad.2019.04.004 · OSTI ID:1531218

Pillai, R. ^[1]; Jalowicka, A. ^[2]; Galiullin, T. ^[2]; Naumenko, D. ^[2]; Ernsberger, M. ^[3]; Herzog, R. ^[3]; Quadakkers, W. J. ^[2]

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1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2. Forschungszentrum Juelich GmbH (Germany)
3. MAN Energy Solutions SE, Oberhausen (Germany)

MCrAlY (M = Ni, Co) coatings are commonly used on gas-turbine components as oxidation resistant overlay coatings and bondcoats for thermal barrier systems. Here, we focus on the effect of the aluminizing process on the CoNiCrAlY coating microstructure. In the as-received condition the outer part of the coating consisted mostly of β-(Ni,Co)Al with interspersed precipitates of Cr-rich carbide and Cr-rich boride precipitates. Formation of σ-CoCr was observed at the interface between the β-layer and the inner initial CoNiCrAlY microstructure. Scanning electron microscopy (SEM) combined with energy and wavelength-dispersive X-ray spectroscopy (EDX/WDX) was employed to characterize the aluminized CoNiCrAlY coating. Phases were then identified by electron backscatter diffraction (EBSD). Detailed microstructural studies of the coating were corroborated with the help of coupled thermodynamic-kinetic calculations to model the aluminizing process. The calculations were performed with the in-house developed code employing the commercially available thermodynamic and kinetic databases (ThermoCalc). The mechanisms of the observed microstructural changes were elucidated with the help of the modelling donclusions.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 1531218
• Journal Information: Calphad, Vol. 65, Issue C; ISSN 0364-5916
• Publisher: ElsevierCopyright Statement
• Country of Publication: United States
• Language: English