Increase in γ/α2 Lamellar Boundary Density and its Effect on Creep Resistance of TiAl Alloy

Abstract

Several lamellar microstructures of a Ti-48 % Al alloy were made by changing heating rate in the α+ dual phase field, and their creep properties were investigated at 1150 K. Average spacing and average length of α2 lamellae decrease with increasing heating rate. The decrease of α2 lamellar spacing is most effective at lower heating rate, and minimum creep rate decreases with increasing the heating rate, since a high density of γ/α2 boundaries stabilizes lamellar microstructure during creep. On the other hand creep rate increases at high heating rate, since α2 lamellar length becomes shorter with increasing heating rate. A reduction of creep rate by one order of magnitude is achieved at the optimum heating rate providing the best combination of narrow spacing and sufficiently long length of α2 lamellae.

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Acknowledgments

Financial supports from the Ministry of Education, Science, Sports and Culture, Japan (Grant no. 15360361) and from the 21st century COE program of Materials Research Center, Tohoku University are gratefully acknowledged.

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Correspondence to Kouichi Maruyama.

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Maruyama, K., Matsuda, J. & Zhu, H. Increase in γ/α2 Lamellar Boundary Density and its Effect on Creep Resistance of TiAl Alloy. MRS Online Proceedings Library 842, 465–470 (2004). https://doi.org/10.1557/PROC-842-S7.10

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