Effect of Environment on the Scale Formed on ODS FeCrAl at 1050 C and 1100 C
- ORNL
The surface scale formed on specimens of a commercial oxide dispersion strengthened (ODS) FeCrAl alloy (PM2000{trademark}) exposed for 1 and 500 h at 1050 C in dry O{sub 2}, Air + 10%H{sub 2}O and Ar + 10%H{sub 2}O consisted of a two-layer {alpha}-Al{sub 2}O{sub 3} structure with a columnar grain inner layer and a finer grain outer layer. The alumina scales formed in Air + 10%H{sub 2}O and Ar + 10%H{sub 2}O were slightly more than half of the thickness of the scale formed in dry O{sub 2}. The same two-layer structure was also observed after exposure for 500 h at 1100 C in dry O{sub 2} and 50%CO{sub 2} + 50%H{sub 2}O. The alumina scales formed in both atmospheres were similar in thickness. Oxides rich in Y and Ti at the gas - scale interface grew in size and number with time in each case. Using analytical transmission electron microscopy, alumina grain boundary segregation of both Y and Ti was evident near the gas interface but only Y segregation was detected near the metal interface. This difference was attributed to Ti depletion in the adjacent metal and the rapid outward flux of the smaller Ti ion through the scale.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Shared Research Equipment Collaborative Research Center
- Sponsoring Organization:
- FE USDOE - Office of Fossil Energy (FE)
- DOE Contract Number:
- DE-AC05-00OR22725
- OSTI ID:
- 1048715
- Resource Relation:
- Conference: Microscopy of Oxidation 8, Liverpool, United Kingdom, 20110411, 20110413
- Country of Publication:
- United States
- Language:
- English
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