| About this Abstract |
| Meeting |
MS&T24: Materials Science & Technology
|
| Symposium
|
Advances in High-Temperature Oxidation and Degradation of Materials for Harsh Environments: A SMD and FMD Symposium Honoring Brian Gleeson
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| Presentation Title |
On the Formation of Adherent Alumina Scales |
| Author(s) |
Bruce A. Pint, Yi-Feng Su, Michael J Lance |
| On-Site Speaker (Planned) |
Bruce A. Pint |
| Abstract Scope |
One can consider many factors that affect alumina scale adhesion. Some of the most popular are “reactive” element (RE) additions and the effect of interstitial impurities/additions like C and O that might affect RE activity and mobility. However, the most significant factor is the coefficient of thermal expansion (CTE) mismatch between the alumina scale and the substrate, which may include alloy phase transformations. To illustrate that point, various Ni- and Fe-based alumina-forming alloys with optimized RE additions of Y and/or Hf were thermally cycled in air at 1200°C using 1-h cycles and the residual stress was tracked using photo-stimulated luminescence spectroscopy. After 100 cycles, the highest stress was observed for NiCrAl+YHf but higher CTE alloys like Fe3Al+YHf, FeAl+Hf and Ni-35at.%Al+Hf showed no residual stress because of spallation. Alloys that retained high residual stress (FeCrAl+YHf and NiAl+Hf) had the lowest CTE. Research sponsored by the U. S. Department of Energy. |