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Formation of Fine γ Grain Structure Through Fine α2 / γ Lamellar Structure in Ti-Rich TiAl Alloy

Published online by Cambridge University Press:  15 February 2011

T. Kumagai ,
E. Abe  and
M. Nakamura
T. Kumagai
Affiliation:
National Research Institute for Metals, Tsukuba-shi, Ibaraki 305, Japan
E. Abe
Affiliation:
National Research Institute for Metals, Tsukuba-shi, Ibaraki 305, Japan
M. Nakamura
Affiliation:
National Research Institute for Metals, Tsukuba-shi, Ibaraki 305, Japan
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Abstract

Microstructural development of an extremely fine α2-Ti3Al / γ-TiAl lamellar structure, which was formed by ice water quenching after solution-treatment in a high-temperature α-Ti phase field for a long period of time, was examined during isothermal aging treatment. In an as-quenched Ti-48at.%Al alloy, the massively transformed γ (γm) and untransformed (meaning massively untransformed) fine α2/γ lamellar regions were observed. Fine γ grains, which were similar to γm, were generated both within the fine α2/γ lamellae and at the boundary area between the γm and the fine α2/γ lamellar regions by aging at a low-temperature (1173K) for a short time (180s). Further aging (1.8ks) caused the coarsening of these newly generated fine γ grains. On the other hand, the coarsening of the γ grains occurred by a high-temperature (1323K) aging treatment even for 180s. Fine α2 plates and particles, which were aligned to a particular direction, were observed in the γ grain interiors, indicating that the newly generated γ grains grew at the expense of the fine α2/γ lamellae. It can be considered that the γ grain formation through the fine α2/γ lamellae is closely related to the α2→γ reaction of the α2 plates sandwiched by the γ plates, and needs the fast heating rate enough to overcome the α2/γ → γ/γ lamellae reaction.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 460: Symposium Z – High-Temperature Ordered Intermetallic Alloys VII , 1996 , 135
Copyright
Copyright © Materials Research Society 1997

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References

REFERENCES

1. Kim, Y-W., in Microstructure / Property Relationships m Titanium Aluminides and Alloys, edited by Kim, Y-W. and Boyer, R.R. (TMS Proc, Warrendale, PA, 1991) pp. 91–103.Google Scholar
2. Huang, S-C. and Shih, D.S., in Microstructure / Property Relationships in Titanium Aluminides and Alloys, edited by Kim, Y-W. and Boyer, R.R. (TMS Proc, Warrendale, PA, 1991) pp. 105–122.Google Scholar
3. Wang, P., Viswanathan, G.B. and Vasudevan, V.K., Metall. Trans. A., 23A, 690 (1992).Google Scholar
4. 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
5. Kumagai, T., Abe, E., Takeyama, M. and Nakamura, M., in High-Temperature Ordered Intermetallic Allovs VI. edited by Horton, J.A. et al. (MRS Proc 364, Pittsburgh, PA, 1995) pp. 181–186.Google Scholar
6. Mahon, G.J. and Howe, J.M., Metall. Trans. A., 21A, 1655 (1990).Google Scholar
7. Singh, S.R. and Howe, J.M., Phil. Mag. A, 66, 739 (1992).Google Scholar
8. Abe, E., Kumagai, T. and Nakamura, M., Phil. Mag. Lett., 72, 291 (1995).Google Scholar
9. Abe, E., Kumagai, T. and Nakamura, M., in Metastable Phases and Microstructures, edited by Bormann, R. et al. (MRS Proc 400, Pittsburgh, PA, 1996) pp. 281–286.Google Scholar
10. Hono, K., Abe, E., Kumagai, T. and Harada, H., Scripta Mater., 35, 495 (1996).Google Scholar