%0 Journal Article
%A Jalowicka, A.
%A Naumenko, D.
%A Ernsberger, M.
%A Herzog, R.
%A Quadakkers, W. J.
%T Alumina Formation and Microstructural Changes of Aluminized CoNiCrAlY Coating During High Temperature Exposure in the Temperature Range 925–1075°C
%J Materials at high temperatures
%V 35
%N 1-3
%@ 1878-6413
%C Amsterdam [u.a.]
%I Elsevier Science
%M FZJ-2018-07269
%P 66 - 77
%D 2018
%X MCrAlY (M = Ni, Co) coatings are commonly used on gas-turbine components as oxidation resistant overlay coatings and bondcoats for thermal barrier systems. In the present work the microstructural features and oxidation behavior of an aluminized Co-base MCrAlY-coating on a Ni-based superalloy have been investigated in the temperature range 925–1075 °C. Microstructural studies of the oxidized coatings by SEM/EBSD were complemented with numerical thermodynamic calculations using the software package ThermoCalc. In the as-received condition the outer part of the coating consisted mostly of β-(Ni,Co)Al. Formation of σ-CoCr was observed at the interface between the β-layer and the inner initial CoNiCrAlY. During high-temperature air exposure alumina based surface scales were formed but the oxidation induced Al depletion of the aluminized coating did not result in formation of the γ’-(Ni3Al) phase. Rather, the subscale formation of Co/Cr-rich phases was observed and a direct transformation of β- into γ-Ni phase after longer times. It is expected that these subscale microstructural changes thus affect the alumina formation and growth as well as the critical aluminum depletion in a different manner as in the case of corresponding β-NiAl coatings, although a direct comparison between various coating systems was not possible on the basis of the present results.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000435483900009
%R 10.1080/09603409.2017.1392114
%U https://juser.fz-juelich.de/record/858383