Chapter 18. Thermodynamic Stability of Titanium-Aluminum Alloys in Air

  1. John B. Wachtman Jr
  1. Wei-Heng Shih1,
  2. J. B. Boodey2,
  3. W. E. Frazier2 and
  4. S.-W. Wang2

Published Online: 26 MAR 2008

DOI: 10.1002/9780470314715.ch18

Proceedings of the 19th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures - A: Ceramic Engineering and Science Proceedings, Volume 16, Issue 4

Proceedings of the 19th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures - A: Ceramic Engineering and Science Proceedings, Volume 16, Issue 4

How to Cite

Shih, W.-H., Boodey, J. B., Frazier, W. E. and Wang, S.-W. (1995) Thermodynamic Stability of Titanium-Aluminum Alloys in Air, in Proceedings of the 19th Annual Conference on Composites, Advanced Ceramics, Materials, and Structures - A: Ceramic Engineering and Science Proceedings, Volume 16, Issue 4 (ed J. B. Wachtman), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470314715.ch18

Author Information

  1. 1

    Department of Materials Engineering, Drexel University, Philadelphia, PA

  2. 2

    Naval Air Warfare Center, Aircraft Division, Warminster, PA

Publication History

  1. Published Online: 26 MAR 2008
  2. Published Print: 1 JAN 1995

ISBN Information

Print ISBN: 9780470375372

Online ISBN: 9780470314715

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Keywords:

  • degradation;
  • thermodynamic;
  • titanium;
  • aluminides;
  • luthra

Summary

The environmentAl degradation of binary Ti-Al alloys in a nitrogen-oxygen atmosphere was examined. Using thermodynamic data, the phase diagram for Ti-Al-O-N system at 800°C was calculated. In particular, the adverse effect of N2 on the oxidation resistance of the Ti-Al alloy was analyzed. Based on the thermodynamic analysis it is proposed that nitrogen atmosphere helps the formation of titanium nitride which in turn oxidizes and forms titanium oxide. The formation of titanium oxide increases the concentration of oxygen in the alloy and promotes internAl oxidation and suppresses the formation of an outer protective Al2Q3 layer. Experimentally, oxidation experiments of TiAl in oxygen first and then in air were compared with those that were treated in air directly. The experimentAl results indicate that heat-treating the titanium aluminide in oxygen first helps the formation of alumina and reduces the formation of nitride phases.