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Effects of the Variation in α-Phase Volume Fraction on the Thermal Stability of TiAl Alloys with Lamellar Microstructures

Published online by Cambridge University Press:  11 February 2011

S. W. Kim
Affiliation:
Department of Materials Science and Engineering, KAIST, Daejon 305–701, Korea Jointly Appointed at the Center for Advanced Aerospace Materials, POSTECH, Korea
H. N. Lee
Affiliation:
Department of Materials Science and Engineering, KAIST, Daejon 305–701, Korea Jointly Appointed at the Center for Advanced Aerospace Materials, POSTECH, Korea
M. H. Oh
Affiliation:
Department of Materials Science and Engineering, KIT, Gumi 730–701, Korea
M. Yamaguchi
Affiliation:
Department of Materials Science and Engineering, Kyoto Univ., Sakyo-ku, Kyoto 606–8501, Japan
D. M. Wee
Affiliation:
Department of Materials Science and Engineering, KAIST, Daejon 305–701, Korea Jointly Appointed at the Center for Advanced Aerospace Materials, POSTECH, Korea
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Abstract

The thermal stability of lamellar microstructure in Ti-Al-Mo PST crystals containing C or Si, was investigated. In addition, the variation of α-phase volume fraction in Ti-Al-Mo-(C,Si) systems was investigated at several temperatures. Ti-46Al-1.5Mo-0.2C and Ti-46Al-1.5Mo-1.0Si alloys were found to be very stable during heat treatments at various heating rates and temperatures. Moreover, the α-phase volume fractions of Ti-46Al-1.5Mo-0.2C and Ti-46Al-1.5Mo-1.0Si alloys, which were stable compositions, changed less than those of Ti-47Al and Ti-46–1.5Mo alloys, which were unstable compositions. From these results, it was determined that the instability of the latter alloys was caused by their relatively higher variation of α-phase volume fraction during heating. Therefore, it is suggested that the variation of α-phase volume fraction is an important factor in controlling the thermal stability of lamellar microstructure.

Type
Research Article
Copyright
Copyright © Materials Research Society 2003

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References

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