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Effect of Cooling Rate on Decomposition of the α Phase in Ti-(43-50) At.% Al ALLOYS:

Published online by Cambridge University Press:  01 January 1992

Ping Wang  and
Vijay K. Vasudevan
Ping Wang
Affiliation:
Dept. of Materials Science and Engineering, University of Cincinnati, Cincinnati, OH 45221
Vijay K. Vasudevan
Affiliation:
Dept. of Materials Science and Engineering, University of Cincinnati, Cincinnati, OH 45221
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Abstract

The effect of cooling rate on transformations of the disordered, hcp α phase in TiAl alloys containing 43 to 50 at.% Al is reported. Cast and homogenized samples of the alloys were solutionized in the completely α region and cooled at various rates, and the microstructures examined by various microscopical techniques. The results indicate a very strong effect of cooling rate on transformations, and depending on it the γ forms from the α in three morphologies. At low cooling rates, a lamellar morphology is observed, at intermediate rates both Widmanstatten and feathery morphologies appear, and at very high rates a massive transformation dominates. The crystallography of the various forms of γ, together with orientation relationships, compositions, and nature of the parent/product interfaces have been examined. Controlled heat treatments were also performed to further elucidate the cooling rate dependence of the lamellar and Widmanstatten structures. These various results are presented and the temperature and composition dependence of transformations are discussed in light of phase diagram considerations.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 288: Symposium L – High-Temperature Ordered Intermetallic Alloys V , 1992 , 229
Copyright
Copyright © Materials Research Society 1995

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References

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