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The Influence of Microstructure on Superplastic Behaviours of γ-TiAl Alloys

Published online by Cambridge University Press:  10 February 2011

J. Sun
Affiliation:
Open Laboratory for High-Temperature Materials and Tests, School of Materials Science & Engineering, Shanghai Jiao-Tong University, Shanghai 200030, P. R. China;
J. S. Wu
Affiliation:
Open Laboratory for High-Temperature Materials and Tests, School of Materials Science & Engineering, Shanghai Jiao-Tong University, Shanghai 200030, P. R. China;
G. X. Hu
Affiliation:
Open Laboratory for High-Temperature Materials and Tests, School of Materials Science & Engineering, Shanghai Jiao-Tong University, Shanghai 200030, P. R. China;
Y. H. He
Affiliation:
Central South University of Technology, Changsha 410083, P R. China.
B. Y. Huang
Affiliation:
Central South University of Technology, Changsha 410083, P R. China.
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Abstract

In this work, superplastic behaviours in Ti-33A1–3Cr-0.5Mo (wt%) γ-TiAl alloys with two different initial microstructures of near gamma (NG) and duplex (DM) structure were investigated with respect to the effect of testing temperatures and strain rates. At 1050°C and a strain rate of 8×10–5 S–1, a maximum elongation of 570% was observed for NG-TiAl and a maximum elongation of 467% for DM-TiAl. The relations of flow stress and strain rate sensitivity vs. strain rates at different temperatures were also determined by incremental strain rate tests. The results showed that the value of strain rate sensitivity is higher and the flow stress is lower for NG than those for DM at the same condition. The microstructural evolution during superplastic deformation was examined and correlated to the mechanical properties for these two alloys. The influence of microstructure on the superplastic behaviours of γ-TiAl alloys, and possible superplastic deformation mechanisms were finally discussed.

Type
Research Article
Copyright
Copyright © Materials Research Society 1999

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References

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