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High-Temperature Phase Transformation in Cr Added TiAl Base Alloy

Published online by Cambridge University Press:  10 February 2011

E. Abe ,
K. Niinobe ,
M. Nobuki ,
M. Nakamura  and
T. Tsujimoto
E. Abe
Affiliation:
National Research Institute for Metals, Tsukuba, JAPAN,
K. Niinobe
Affiliation:
Ibaraki University, Faculty of Engineering, Hitachi, JAPAN.
M. Nobuki
Affiliation:
National Research Institute for Metals, Tsukuba, JAPAN,
M. Nakamura
Affiliation:
National Research Institute for Metals, Tsukuba, JAPAN,
T. Tsujimoto
Affiliation:
Ibaraki University, Faculty of Engineering, Hitachi, JAPAN.
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Abstract

We have investigated a microstructure evolution of a Ti-48Al-3.5Cr (in at.%) alloy at high-temperatures (>1473K). In the alloy annealed at 1673K for 1.8ks, followed by air-cooling, a characteristic microstructure with a feathery fashion was uniformly formed. From a cooling-rate-controlling study, it was found that formation of the feathery structure is accomplished during continuous cooling from 1673K to 1573K, within the α+γ two-phase region. Transmission electron microscopy revealed that the feathery structure is composed of lamellar colonies (5–10µm) which are crystallographicaly tilted slightly (a few degree) with their neighbors. A surprising fact is that lamellae in each colony are mostly the γphase with few α2 phase less than 5% in volume. This suggests that the feathery structure is a metastable product and has not resulted from the α → α+γ transformation above 1573K. Instead, the feathery structure formation should be attributed to the non-equilibrium α → γtransformation which occurs at high-temperatures with a small degree of supercooling. We discuss this interesting phase transformation in terms of the α→γ massive transformation, based on the continuous-coolingtransformation (CCT) diagram constructed for the present alloy.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 552: Symposium KK – High-Temperature Ordered Intermetallic Alloys VIII , 1998 , KK2.10.1
Copyright
Copyright © Materials Research Society 1999

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References

REFERENCES

1. Wang, P., Viswanathan, G.B. and Vasudevan, V.K., Metall. Trans. A, 23A, 690 (1992).Google Scholar
2. Jones, S. A. and Kaufman, M.J., Acta metall. mater., 41, 387 (1993).CrossRefGoogle Scholar
3. Takeyama, M., Kumagai, T., Nakamura, M. and Kikuchi, M., in Structural Intermetallics, edited by Darolia, R. et al. ( TMS Proc., Warrendale, PA, 1993 ) pp. 167–176.Google Scholar
4. Wang, P. and Vasudevan, V. K., Scripta Metall. Mater., 27, 89 (1992).CrossRefGoogle Scholar
5. Mahon, G.J. and Howe, J.M., Metall. Trans. A, 21A, 1655 (1990).CrossRefGoogle Scholar
6. Abe, E., Kumagai, T. and Nakamura, M., in Structural Intermetallics-II, edited by Nathal, M. V. et al. (TMS Proc., Warrendale, PA, 1997) pp. 167–176.Google Scholar
7. Miura, T., Takeyama, M., Suzuki, T., Nakamura, M., Kumagai, T. and Hashimoto, K., in Abstracts of the JIM Spring Meeting, p334 (1993).Google Scholar
8. Abe, E., Niinobe, K., Nobuki, M., Nakamura, M. and Tsujimoto, T., to be submitted.Google Scholar
9. Kim, Y.-W., Acta metall. mater., 40, 1121 (1992).Google Scholar
10. Abe, E., Kajiwara, S., Kumagai, T. and Nakamura, M., Phil. Mag. A, 75, 975 (1997).CrossRefGoogle Scholar