Abstract
Cast NiAl alloyed with Cr, Pt, Pd, Ir and Ru was tested in 1-h cycles at 950 °C under hot corrosion conditions and at 1150 °C in oxygen. For comparison, Hf-doped NiAl variants and a cast NiPtAl alloy resembling the composition of commercial aluminide coatings were included. Cr was the only element that reduced hot corrosion attack of NiAl significantly. However, at higher temperatures, addition of Cr to Hf-doped NiAl accelerated the alumina scale growth rate and promoted spallation of the oxide scale. The results from initial detailed characterization indicate that rejection of chromium at the metal-oxide interface gives rise to the formation of chromium-rich precipitates in the alloy, which apparently modify its oxidation behavior. This suggests that for NiAl-based substrates, hot corrosion resistance and exceptional scale spallation resistance may be mutually incompatible goals.
| Original language | English |
|---|---|
| Pages (from-to) | 15-22 |
| Number of pages | 8 |
| Journal | Surface and Coatings Technology |
| Volume | 133-134 |
| DOIs | |
| State | Published - Nov 2000 |
Funding
The research was sponsored by the German Aerospace Center and the US Department of Energy, Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Industrial Technologies, as part of the Advanced Turbine Systems Program under contract DE-AC05-96OR22464 with Lockheed Martin Energy Research Corporation. M. Peters at DLR and J.A. Haynes, D.F. Wilson and J.R. DiStefano at ORNL provided comments on the manuscript which are gratefully acknowledged.
| Funders | Funder number |
|---|---|
| Lockheed Martin Energy Research Corporation | |
| Office of Industrial Technologies | DE-AC05-96OR22464 |
| U.S. Department of Energy | |
| Office of Energy Efficiency and Renewable Energy | |
| Deutsches Zentrum für Luft- und Raumfahrt |