Microstructures in L12 Titanium Trialuminides Containing Iron

Abstract

The microstructures of the L12 titanium trialuminides at low temperatures were studied using a number of single crystals with various Al-Ti-Fe compositions, all of which lie in the nominal single phase L12 field at 1200°C. Five different second phases were found to be in equilibrium with the L12 matrix, namely, (Al,Ti)3Fe, Al3Ti, Al2FeTi, Ti2NAl and Al2Ti+Fe. Small volume fractions of the first two phases are often seen in compounds containing relatively low Ti contents. The Al2FeTi, a so-called T phase, was observed at relatively high Fe contents. The Ti2NAl does not seems to be sensitive to the Al-Ti-Fe composition, it exists to some extent in all the alloys used in this study. Ti2NAl and the interface with the L12 matrix are found to be brittle and provide the sites for crack initiation. The Al2Ti+Fe phase has been observed in many compounds containing high Ti contents (>25 at.%), and has a large hardening effect. Like binary Al2Ti, the phase possesses a tetragonal structure of the Ga2Hf-type, and forms plates on the cube planes of the L12 matrix. The crystallographic relation between the Al2Ti and the L12 matrix was determined to be (100)p//(100)m.and (010)p//(010)m. Porosity is also commonly seen in these alloys, and has a very destructive impact on ductility.

This is a preview of subscription content, access via your institution.

References

  1. 1.

    S. Mazdiyasni, D.B. Miracle, D.M. Dimiduk, M.G. Mendiratta, and P.R. Subramanian, Scrip. Metall., 223, 327, 1989.

    Article  Google Scholar 

  2. 2.

    V. Ya. Markiv, V. V. Burnashova, and V. P. Ryabov, Akad. Nauk Ukr. SSR, Metallofizika, 4, 103, 1973.

    Google Scholar 

  3. 3.

    A. Raman, and K. Schubert, Z. Metallkd., 56, 99, 1965.

    CAS  Google Scholar 

  4. 4.

    H. Mabuchi, K. Hirukawa, and Y. Makayama, Scrip. Metall., 23, 1761, 1989.

    CAS  Article  Google Scholar 

  5. 5.

    S. Zhang, J.P. Nic, W.W. Milligan, and D.E. Mikkola, Scrip. Metall., 24, 57, 1990.

    CAS  Article  Google Scholar 

  6. 6.

    Z.L. Wu, D.P. Pope, and V. Vitek, submitted to this symposium.

  7. 7.

    C.D. Turner, W.O. Power, and J.A. West, Acta Metall., 37, 2635, 1989.

    CAS  Article  Google Scholar 

  8. 8.

    Z.L. Wu, D.P. Pope, and V. Vitek, High Temperature Ordered Intermetallic Alloys, IV, (ed. by Johnson, L., Pope, D.P. and Stiegler, J.O.), MRS Symp., 213, MRS Pittsburgh, 487, 1991.

    CAS  Google Scholar 

  9. 9.

    Z.L. Wu, D.P. Pope, and V. Vitek, Scrip. Metall., 24, 2187, 1990.

    CAS  Article  Google Scholar 

  10. 10.

    Z.L. Wu, Ph.D thesis, University of Pennsylvania, 1992.

    Google Scholar 

  11. 11.

    E.P. George, J.A. Horton, W.D.Porter and J.H. Schneibel, J. Mater. Res., 5, 1639, 1990.

    CAS  Article  Google Scholar 

  12. 12.

    D.D. Mysko, J.B. Lumsden, W.O. Powers and J.A. Wert, Scrip. Metall., 23, 1827, 1989.

    CAS  Article  Google Scholar 

Download references

Acknowledgement

The work was supported by the AFOSR under Grant AFOSR-89-0062. Research facilities were provided by the LRSM supported by the NSF MRL program under Grant DMR88-19885. The authors would like to thank K.S. Kumar for valuable discussions, and W.J. Romanow and R. Hsiao for technical assistance.

Author information

Affiliations

Authors

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Wu, Z.L., Pope, D.P. & Vitek, V. Microstructures in L12 Titanium Trialuminides Containing Iron. MRS Online Proceedings Library 288, 367–372 (1992). https://doi.org/10.1557/PROC-288-367

Download citation