Skip to main content Accessibility help

Effect of Coherency Stresses on the Stability of Lamellar (α2+γ) Titanium Aluminides

  • F. Appel (a1), U. Christoph (a1), U. Lorenz (a1) and D R. Wagner (a1)


Two phase titanium aluminides with a lamellar microstructure of the intermetallic phases α2(Ti3Al) and γ (TiAl) are being developed for high temperature structural applications. Due to differences in lattice parameters and crystal structure, coherency stresses and mismatch structures occur at various types of semicoherent interfaces present in the material. The implications of these structural features on the stability of lamellar microstructures were studied by TEM in situ heating experiments. The investigations revealed that the lamellar interfaces serve as sources for perfect and twinning dislocations. The results will be discussed with respect to the observed degradation of the strength properties of the two phase alloys in the intended service temperature range of 900- 1000 K.



Hide All
1. Shechtman, D., Blackburn, M. J. and Lipsitt, H. A., Metall. Trans., 5, 1373 (1974).
2. Kim, Y.-W. and Dimiduk, D. M., J OM, 43, 40 (1991).
3. McCullough, C., Valencia, J. J., Levi, C. G., and Mehrabian, R., Acta metall. mater., 37, 1321 (1989).
4. Sastry, S. L. M. and Lipsitt, H. A., Metall. Trans. A, 8, 299 (1997).
5. Inui, H., Nakamura, A., Oh, M. H., and Yamaguchi, M., Ultramicroscopy, 39, 268 (1991).
6. Mahon, G. J. and Howe, J. M., Metall. Trans. A, 8, 299 (1990).
7. Zhao, L. and Tangri, K., Phil. Mag. A, 64, 361 (1991).
8. Singh, S. R. and Howe, J. M., Phil. Mag. Lett. 65, 233 (1992).
9. Kad, B. K. and Hazzledine, P. M., Phil. Mag. Lett. 66, 133 (1992).
10. Appel, F., Beaven, P. A. and Wagner, R., Acta metall. mater. 41, 1721 (1993).
11. Appel, F., Christoph, U. and Wagner, R., in Interface Control of Electrical, Chemical, and Mechanical Properties, edited by Muraka, S. P., Rose, K., Ohmi, T., and Seidel, T. (Mater. Res. Soc. Proc. 318, Pittsburgh, PA 1994), p. 691.
12. Appel, F. and Wagner, R., in Twinning in Advanced Materials, edited by Yoo, M. H. and Wuttig, M. (TMS, Warrendale, PA 1994) p. 317.
13. Appel, F., Sparka, U. and Wagner, R., in High-Temperature Ordered Intermetallic Alloys VI, edited by Horton, J., Baker, I., Hanada, S., Noebe, R. D., and Schwartz, D. S. (Mater. Res. Soc. proc. 364, Pittsburgh PA, 1995) p. 623.
14. Appel, F., Christoph, U. and Wagner, R., Phil. Mag. A, 72, 341 (1995).
15. Appel, F. and Wagner, R., to be published in Mater. Sci. Eng.


Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed