Abstract
In the integration of oxy-fuel combustion to turbine power generation system, turbine alloys are exposed to high temperature and an atmosphere comprised of steam, CO2 and O2. While surface and internal oxidation of the alloy takes place, the microstructure in the subsurface region also changes due to oxidation. In this study, bare metal coupons of Ni-base superalloys were exposed in oxy-fuel combustion environment for up to 1000h and the oxidation-related microstructures were examined. Phase transformation occurred in the subsurface region in Ni-based superalloy and led to twinning. The transformation product phases were analyzed through thermodynamic equilibrium calculations and various electron microscopy techniques, including scanning electron microscopy (SEM), orientation imaging microscopy (OIM) and transmission electron microscopy (TEM). The mechanism by which the phase transformation and the formation of the microstructure occurred was also discussed. The possible effects of the product phases on the performance of the alloy in service were discussed.
Original language | English (US) |
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Pages (from-to) | 243-253 |
Number of pages | 11 |
Journal | Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing |
Volume | 550 |
DOIs | |
State | Published - Jul 30 2012 |
Externally published | Yes |
Keywords
- High temperature oxidation
- Oxy-fuel combustion
- Phase transformation
- Superalloy
ASJC Scopus subject areas
- General Materials Science
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering