Abstract
The effect of microstructural refinement on the oxidation behavior of γ+ laves Ti-45Al-15Cr and γ+ σ Ti-40Al-27Nb was investigated. A fine, uniform γ+ laves microstructure in Ti-45Al-15Cr resulted in protective alumina scale formation over most of the sample surface at 800°C and 10000C in air. In contrast, the oxidation resistance of this same alloy was severely degraded by a coarse γ+ laves microstructure. The oxidation behavior of Ti-40Al-27Nb at 1200°C in air was poor. Refinement of the γ+ σ microstructure in this alloy was not effective in improving oxidation resistance. The mechanistic reasons for these effects, and the implications for improved oxidation resistance through microstructural refinement are discussed.
Original language | English |
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Pages (from-to) | 635-653 |
Number of pages | 19 |
Journal | Materials and Manufacturing Processes |
Volume | 11 |
Issue number | 4 |
DOIs | |
State | Published - 1996 |
Externally published | Yes |
Funding
The authors wish to thank S.P. Elder Randall, R.J. Hanrahan, Jr., J.C. Liu, and F. Ebrahimi for their helpful discussions of microstructure and oxidation in the Ti-Al-Nb system. The authors also wish to thank United Technologies ( h t tand Whitney) for supplying the arc-melted buttons of Ti-Al-Nb alloys. The Ti-Al-Nb work was performed at the University of Florida and supported by DARPA under grant # MDA 972-88-J-1006 and Ofice of Naval Research grant # NO00 1 4-88-J-1 100. The Ti-Al-Cr work was performed at NASA Lewis and supported under the HITEMP program. One author (MPB) wishes to acknowledge the support of a National Research Council PostDoctoral Fellowship. 9. Perkins, R. A,, K. T. Chiang, G. H. Meier, and R. A. Miller, "Effect of Alloying, Rapid Solidification, and Surface Kinetics on the High-temperature Environmental Resistance of Niobium" (Final Report Contract # F49620-86-C-0018 Air Force Office of Scientific Research, June 1989).