TY  - JOUR
AU  - Jalowicka, Aleksandra
AU  - Duan, Ran
AU  - Huczkowski, Pawel
AU  - Chyrkin, Anton
AU  - Grüner, Daniel
AU  - Pint, B. A.
AU  - Unocic, K. A.
AU  - Quadakkers, Willem J.
TI  - Effect of Specimen Thickness on Microstructural Changes During Oxidation of the NiCrW Alloy 230 at 950-1050°C
JO  - JOM
VL  - 67
IS  - 11
SN  - 0148-6608
CY  - New York, NY
PB  - Springer Science + Business Media
M1  - FZJ-2015-07478
SP  - 2573-2588
PY  - 2015
AB  - An accurate procedure for predicting oxidation-induced damage and lifetime limits is crucial for the reliable operation of high-temperature metallic components in practical applications. In order to develop a predictive oxidation lifetime model for Ni–Cr alloys, specimens of wrought NiCrW alloy 230 with different thicknesses were cyclically oxidized in air at 950–1050°C for up to 3000 h. After prolonged exposure, two types of carbides as well as a Cr-rich nitride (π-phase) precipitated in the γ-Ni matrix. The oxidation-induced loss of Cr from the alloy resulted in the formation of subscale zones, which were free of the Cr-rich carbide and nitride but also of the Ni-W rich M6C. The width of the M6C-free zone was smaller than that free of the Cr-rich precipitates. Thermodynamic and diffusion calculations of the observed time- and temperature-dependent Cr depletion processes identified that back diffusion of C occurred which resulted in an increased volume fraction of M23C6 in the specimen core. With increasing time and temperature, the amount of π-phase in the specimen core increased. The subscale depletion of the initially present Cr-nitrides and the formation of Cr-nitrides in the specimen center is believed to be related to a mechanism which is qualitatively similar to that described for the Cr carbide enrichment. However, with increasing time and decreasing specimen thickness, N uptake from the atmosphere becomes apparent. As a result, the precipitates present in the specimen center eventually consisted almost exclusively of nitrides
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000363936400012
DO  - DOI:10.1007/s11837-015-1645-8
UR  - https://juser.fz-juelich.de/record/279594
ER  -