Hostname: page-component-78c5997874-94fs2 Total loading time: 0 Render date: 2024-11-09T02:36:29.584Z Has data issue: false hasContentIssue false
  • English
  • Français

The Importance of Microstructural Instability in Determining the Mechanical Behaviour of Cubic Titanium Trialuminides

Published online by Cambridge University Press:  01 January 1992

D.G. Morris ,
S. Gunther  and
R. Lerf
D.G. Morris
Affiliation:
Institute of Structural Metallurgy, Avenue de Bellevaux 51, University of Neuchâtel, NEUCHATEL 2000, SWITZERLAND.
S. Gunther
Affiliation:
Institute of Structural Metallurgy, Avenue de Bellevaux 51, University of Neuchâtel, NEUCHATEL 2000, SWITZERLAND.
R. Lerf
Affiliation:
Institute of Structural Metallurgy, Avenue de Bellevaux 51, University of Neuchâtel, NEUCHATEL 2000, SWITZERLAND.
Get access

Abstract

Cubic trialuminides deform by the movement of <110> dislocations which are clearly dissociated as APB superdislocations at high temperatures, with debate about whether these are dissociated as APB or SISF superdislocations at low temperatures. These materials are characterized by the following mechanical behaviour: (i) strength variable with ternary element addition or titanium content; (ii) mild strength anomaly at high temperature, sometimes; (iii) serrations in stress-strain curve at intermediate temperatures; (iv) low tensile ductility (≈0) at room temperature, increasing at higher temperatures, with an intermediate temperature minimum.

These properties are explained by the fine microstructure and its variation locally and with temperature: (a) a tetragonal component of order in ternary alloys in addition to the basic L12 order, varying with ternary element and content; (b) precipitation (sometimes on dislocations) during high temperature testing - accounting for the strength anomaly; (c) extra-ordinarily rapid solute collection at dislocations and APB's - accounting for strain aging and minimum ductility phenomena; (d) strain relaxation at crack tips restricted to single slip planes by the structural modification produced by shear - making a major contribution to brittleness.

All these processes are particularly acute in the titanium trialuminides because of the structural instabilities involved, and the fast kinetics of atom rearrangement; thus low temperatures during testing or during cooling after prior heat treatment play a major role. Similar effects may be of importance in other intermetallics such as FeAl, TiAl.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 288: Symposium L – High-Temperature Ordered Intermetallic Alloys V , 1992 , 177
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. Kumar, K.S. and Pickens, J.R., Scripta Metall. 22, 1015 (1988).Google Scholar
2. Kumar, K.S. and Brown, S.A., Acta Metall. Mater. 40, 1923 (1992).Google Scholar
3. Zhang, S., Nic, J.P., Milligan, W.W. and Mikkola, D.E., Scripta Metall. Mater. 24, 1441 (1990).Google Scholar
4. Wu, Z.L., Pope, D.P. and Vitek, V., Scripta Metall. Mater. 24, 2187 (1990).Google Scholar
5. Lerf, R. and Morris, D.G., Acta Metall. Mater. 39, 2419 (1991).Google Scholar
6. Nic, J.P., Zhang, S. and Mikkola, D.E., Scripta Metall. 24, 1099 (1990).Google Scholar
7. Tichy, G., Vitek, V. and Pope, D.P., Phil. Mag. A53, 467 (1986).Google Scholar
8. Tichy, G., Vitek, V. and Pope, D.P., Phil. Mag. A53, 485 (1986).Google Scholar
9. Takasugi, T., Hirakawa, S., Izumi, O., Ono, S. and Watanabe, S., Acta Metall. 35, 2015 (1987).Google Scholar
10. Winnicka, M.B. and Varin, R.A., Scripta Metall. Mater. 25, 2297 (1991).Google Scholar
11. Morris, D.G., Lerf, R. and Hollrigl, G., EUROMAT 91, Proc. 2nd European Conf. on Advanced Structural Materials, Vol. 2, The Institute of Metals, London, p. 398 (1992).Google Scholar
12. Zhang, S., Nic, J.P. and Mikkola, D.E., Scripta Metall. Mater. 24, 57 (1990).Google Scholar
13. George, E.P., Horton, J.A., Porter, W.D. and Schneibel, J.H., J. Mater. Res. 5, 1639 (1990).Google Scholar
14. Morris, D.G., J. Mater. Res. 7, 303 (1992).Google Scholar
15. Gengxiang, H., Shipu, C., Xiaohua, W. and Xiaofu, C., J. Mater. Res. 6, 957 (1991).Google Scholar
16. Inui, H., Luzzi, D.E., Porter, W.D., Pope, D.P., Vitek, V. and Yamaguchi, M., Phil. Mag. A65, 245 (1992).Google Scholar
17. Veyssiere, P. and Morris, D.G., Phil. Mag., in press.Google Scholar
18. Morris, D.G. and Gunther, S., Acta Metall. et Mater., 40, 3065 (1992).Google Scholar
19. Potez, L., Lapasset, G. and Kubin, L.P., Scripta Metall. Mater. 26, 841 (1992).Google Scholar
20. Yamaguchi, M., Umakoshi, Y. and Yamane, T., Mater. Res. Soc. Symp. proc., Vol. 81, Materials Research Society, Pittsburgh, p. 275 (1987).Google Scholar
21. Morris, D.G., Scripta Metall. Mater. 25, 713 (1991).Google Scholar
22. Morris, D.G., Phil. Mag. A65, 389 (1992).Google Scholar
23. Korner, A. and Schoeck, G., Phil. Mag. A61, 909 (1991).Google Scholar
24. Morris, D.G., Scripta Metall. Mater. 26, 733 (1992).Google Scholar
25. Brown, N., Phil. Mag. 4, 693 (1959).Google Scholar
26. Popov, L.E., Kozlov, E.V. and Golosov, N.S., Phys. Stat. Sol. 13, 569 (1966).Google Scholar
27. Golosov, N.S., Pudan, L. Ya. and Popov, L.E., Phys. Stat. Sol. 11, 123 (1972).Google Scholar