TY  - JOUR
AU  - Jalowicka, A.
AU  - Naumenko, D.
AU  - Ernsberger, M.
AU  - Herzog, R.
AU  - Quadakkers, W. J.
TI  - Alumina Formation and Microstructural Changes of Aluminized CoNiCrAlY Coating During High Temperature Exposure in the Temperature Range 925–1075°C
JO  - Materials at high temperatures
VL  - 35
IS  - 1-3
SN  - 1878-6413
CY  - Amsterdam [u.a.]
PB  - Elsevier Science
M1  - FZJ-2018-07269
SP  - 66 - 77
PY  - 2018
AB  - 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.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000435483900009
DO  - DOI:10.1080/09603409.2017.1392114
UR  - https://juser.fz-juelich.de/record/858383
ER  -