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Control of Lamellar Orientation in γ-TiAl Based PST Crystal by Using Seed Crystals

Published online by Cambridge University Press:  21 March 2011

Y. Yamamoto ,
H. Morishima ,
K. Koike ,
M. Takeyama  and
T. Matsuo
Y. Yamamoto
Affiliation:
Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology, 2–12–1, Ookayama, Meguro-ku, Tokyo 152–8552, JAPAN
H. Morishima
Affiliation:
Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology, 2–12–1, Ookayama, Meguro-ku, Tokyo 152–8552, JAPAN
K. Koike
Affiliation:
Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology, 2–12–1, Ookayama, Meguro-ku, Tokyo 152–8552, JAPAN
M. Takeyama
Affiliation:
Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology, 2–12–1, Ookayama, Meguro-ku, Tokyo 152–8552, JAPAN
T. Matsuo
Affiliation:
Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology, 2–12–1, Ookayama, Meguro-ku, Tokyo 152–8552, JAPAN
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Abstract

Unidirectional solidification of Ti-48Al binary alloy using γ-TiAl single-phase seed crystals has been carried out by an optical floating zone method. The lamellar orientation of the grown PST crystal follows the orientation of the Ti-57Al seed crystal, while it fails to follow that in the case of the Ti-53Al seed. Microstructure analysis reveals that the seed crystal of Ti-57Al exhibits a flat liquid/solid interface in melting (γ→+L) even after making contact with 48Al to grow, whereas the seed of Ti-53Al shows a cellular interface due to the peritectic reaction in melting (γ→α+L). At the 57/48 interface, an abrupt change of Al concentration was detected from the seed to the grown crystal, indicating an occurrence of composition travel to skip the peritectic reaction, which is responsible for the control of lamellar orientation of the grown PST crystals. The same attempt has been made by using the 57Al single crystal seed with a different orientation, and the lamellar orientation of the grown PST crystal was confirmed to follow the orientation of the seed.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 646 , 2000 , N5.54.1
Copyright
Copyright © Materials Research Society 2001

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Footnotes

1

Graduate Student, Tokyo Institute of Technology, Tokyo, JAPAN

References

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