1. Effect of environment on the scale formed on oxide dispersion strengthened FeCrAl at 1050°C and 1100°C
- Author
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Sebastien N. Dryepondt, Kinga A. Unocic, Bruce A. Pint, and E. Essuman
- Subjects
Materials science ,Mechanical Engineering ,Metallurgy ,Alloy ,Metals and Alloys ,Analytical chemistry ,Oxide ,engineering.material ,Condensed Matter Physics ,Metal ,chemistry.chemical_compound ,Flux (metallurgy) ,chemistry ,Mechanics of Materials ,Transmission electron microscopy ,visual_art ,Materials Chemistry ,Ceramics and Composites ,visual_art.visual_art_medium ,engineering ,Grain boundary ,Dispersion (chemistry) ,Layer (electronics) - Abstract
The surface scale formed on specimens of a commercial oxide dispersion strengthened (ODS) FeCrAl alloy (PM2000) exposed for 1 and 500 h at 1050°C in dry O2, Air+10%H2O and Ar+10%H2O consisted of a two-layer α-Al2O3 structure with a columnar grain inner layer and a finer grain outer layer. The alumina scales formed in Air+10%H2O and Ar+10%H2O were slightly more than half of the thickness of the scale formed in dry O2. The same two-layer structure was also observed after exposure for 500 h at 1100°C in dry O2 and 50%CO2+50%H2O. 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 sma...
- Published
- 2012
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