Hostname: page-component-7479d7b7d-pfhbr Total loading time: 0 Render date: 2024-07-13T20:56:44.621Z Has data issue: false hasContentIssue false
  • English
  • Français

Microstructures in Ll2 Titanium Trialuminides Containing Iron

Published online by Cambridge University Press:  01 January 1992

Z.L. Wu ,
D.P. Pope  and
V. Vitek
Z.L. Wu
Affiliation:
Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104-6202.
D.P. Pope
Affiliation:
Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104-6202.
V. Vitek
Affiliation:
Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104-6202.
Get access

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 LI2 matrix. The crystallographic relation between the Al2Ti and the Ll2 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.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 288: Symposium L – High-Temperature Ordered Intermetallic Alloys V , 1992 , 367
Copyright
Copyright © Materials Research Society 1995

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1. Mazdiyasni, S., Miracle, D.B., Dimiduk, D.M., Mendiratta, M.G., and Subramanian, P.R., Scrip. Metall., 223, 327, 1989.Google Scholar
2. Markiv, V. Ya., Burnashova, V. V., and Ryabov, V. P., Akad. Nauk Ukr. SSR, Metallofizika, 4, 103, 1973.Google Scholar
3. Raman, A., and Schubert, K., Z. Metallkd., 56, 99, 1965.Google Scholar
4. Mabuchi, H., Hirukawa, K., and Makayama, Y., Scrip. Metall., 23, 1761, 1989.Google Scholar
5. Zhang, S., Nic, J.P., Milligan, W.W., and Mikkola, D.E. Scrip. Metall., 24, 57, 1990.Google Scholar
6. Wu, Z.L., Pope, D.P., and Vitek, V., submitted to this symposium.Google Scholar
7. Turner, C.D., Power, W.O., and West, J.A., Acta Metall., 37, 2635, 1989.Google Scholar
8. Wu, Z.L., Pope, D.P., and Vitek, V., High Temperature Ordered Intermetallic Alloys, IV, (ed. by L., L., Pope, D.P., and Stiegler, J.O.), MRS Symp., 213, MRS Pittsburgh, 487, 1991.Google Scholar
9. Wu, Z.L., Pope, D.P., and Vitek, V., Scrip. Metall., 24, 2187, 1990.Google Scholar
10. Wu, Z.L., Ph.D thesis, University of Pennsylvania, 1992.Google Scholar
11. George, E.P., Horton, J.A., Porter, W.D. and Schneibel, J.H., J. Mater. Res., 5, 1639, 1990.Google Scholar
12. Mysko, D.D., Lumsden, J.B., Powers, W.O. and Wert, J.A., Scrip. Metall., 23, 1827, 1989.Google Scholar