Incommensurate Structure in Al-rich TiAl Alloys


The microstructures of Ti-Al alloys in the range 56–62 at.% Al have been studied. These compounds consist of a basic L10 structure on which is superimposed an irrational modulation (Ti3Al5 related). This is incommensurate by occupation. It has two-dimensional modulations in which the wave vectors are q1 = α(a* + b*) and q2 = α(-a* + b*) where a* and b* are the L10 reciprocal basis and α is an irrational fraction. α decreases from 0.282 to 0.26 as the Al concentration increases to 60 at.% Al, i.e., the positions of the satellites change continuously with varying Al concentration. A third phase, TiAl2, appears at a composition of 62 at.% Al which means that no Ti3Al5 (62.5 at.% Al) of stoichiometric composition can ever exist.

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  1. 1.

    R. Miida, S. Hashimoto and D. Watanabe, Japanese J. Appl. Phy., 21, L59 (1982).

    CAS  Article  Google Scholar 

  2. 2.

    T. Nakano, K. Matsumoto, T. Seno, K. Oma and Y. Umakoshi, Phil. Mag. A, 74, 251 (1996).

    CAS  Article  Google Scholar 

  3. 3.

    T. Nakano, K. Hagihara, T. Seno, N. Sumida, M. Yamaoto and Y. Umakoshi, Phil. Mag. Lett., 78, 385 (1998).

    CAS  Article  Google Scholar 

  4. 4.

    A. Loiseau and A. Lasalmonie, Acta Cryst., B39, 580 (1983).

    CAS  Article  Google Scholar 

  5. 5.

    A. Loiseau, A. Lasalmonie, G. Van Tendeloo, J. Van Landuyt and S. Amelincks, Acta Cryst., B41, 411 (1985).

    CAS  Article  Google Scholar 

  6. 6.

    H. Inui, K. Chikugo, K. Kishida and M. Yamaguchi, ICEM 14, Cancun, Mexico, p 175 (1998).

    Google Scholar 

  7. 7.

    T. Janssen, A. Janner, A. Looijenga-Vos and P. M. de Wolff, International Table for Crystallography, Vol. C, Chaper 9.8. (1995).

  8. 8.

    H. Inui, M. Matsumuro, D. H. Wu and M. Yamaguchi, Phil. Mag. A, 75, 395 (1997).

    CAS  Article  Google Scholar 

  9. 9.

    M. Sauvage and E. Parthé, Acta Cryst., A28, 607 (1972).

    Article  Google Scholar 

  10. 10.

    P. M. De Wolff, Acta Cryst., A40, 34 (1984).

    Article  Google Scholar 

  11. 11.

    C. Y. Chung, W. H. Zou, X. D. Han, C. W. H. Lam, M. Gao, X. F. Duan and J. K. L. Lai, Acta Mater., 46, 5541 (1998).

    CAS  Article  Google Scholar 

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This work is supported by the Engineering and Physical Sciences Research Council (Contract number GR/L 79960/01)

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Correspondence to S. Wang.

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Wang, S., Fort, D., Jones, I.P. et al. Incommensurate Structure in Al-rich TiAl Alloys. MRS Online Proceedings Library 646, 413–418 (2000).

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