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Fracture Behaviour of Two-Phase γ-Titanium Aluminides

Published online by Cambridge University Press:  22 February 2011

Fritz Appel ,
Uwe Lorenz ,
Tao Zhang  and
Richard Wagner
Fritz Appel
Affiliation:
Institute for Materials Research, GKSS Research Center, Max-Planck-Str., D-21502 Geesthacht, Germany
Uwe Lorenz
Affiliation:
Institute for Materials Research, GKSS Research Center, Max-Planck-Str., D-21502 Geesthacht, Germany
Tao Zhang
Affiliation:
Institute for Materials Research, GKSS Research Center, Max-Planck-Str., D-21502 Geesthacht, Germany
Richard Wagner
Affiliation:
Institute for Materials Research, GKSS Research Center, Max-Planck-Str., D-21502 Geesthacht, Germany
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Abstract

Titanium aluminides with a lamellar microstructure consisting of the intermetallic phases ֱ2 (Ti3Al) and γ(TiAl) suffer from brittleness at ambient temperatures but exhibit at the same time a relatively high fracture toughness. This discrepancy indicates particular processes stabilizing crack propagation in the lamellar microstructure. In this context, the toughening mechanisms were investigated in (α2 + γ) TiAl alloys which contained different volume fractions of lamellar colonies. The fracture toughness for crack propagation parallel or across the lamellar interfaces was estimated by using chevron-notched bending bars. Electron microscope studies were performed to characterize the related processes of crack tip plasticity. Special emphasis was paid to the crystallography of crack propagation and to the interaction of crack tips with lamellar interfaces. Accordingly, the lamellar morphology derives some of its toughness from interface-related processes which stabilize crack propagation by deflecting the crack tip and providing the necessary dislocation sources for crack tip shielding in the process zone ahead of the crack tip.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 364: Symposium L – High-Temperature Ordered Intermetallic Alloys–VI , 1994 , 493
Copyright
Copyright © Materials Research Society 1995

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References

1. Kim, Y.-W., JOM, 41, 24 (1989).Google Scholar
2. Hall, E.L. and Huang, S.C., J. Mater. Res. 4, 595 (1989).Google Scholar
3. Kim, Y.-W. and Dimiduk, D.M., JOM 43, 40 (1991).Google Scholar
4. Sastry, S.L.M. and Lipsitt, H.A., Metall. Trans. 8A, 299 (1977).Google Scholar
5. Inui, H., Nakamura, A., Oh, M.H., and Yamaguchi, M., Phil. Mag. A 66, 539, (1992).Google Scholar
6. Appel, F., Beaven, P.A. and Wagner, R., Acta metall. Mater. 41, 1721 (1993).Google Scholar
7. Chan, K.S. and Kim, Y.-W., Metall. Trans. 23A, 1663 (1992).Google Scholar
8. Kim, Y.-W. and Dimiduk, D.M., in High Temperature Deformation and Fracture. Proc. JIMIS-7, edited by Hosoi, Y., Yoshinaga, H., Oikawa, H., and Maruyama, K., JIM (Nagoya), 1993, p. 373.Google Scholar
9. Beaven, P. A., Appel, F., Dogan, B., and Wagner, R., in Ordered Intermetallics. edited by Liu, C.T., Cahn, R.W. and Sauthoff, G., NATO ASI Series E: Applied Sciences (Kluwer Academic Publishers, Dordrecht, 1991), Vol. 213, p. 213.Google Scholar
10. Newmann, C.W., in Chevron-Nochted Specimens: Testing and Stress Analysis, (ASTM STP 855, 1985), p. 5.Google Scholar
11. Munz, D., Bubsey, R.T. and Shannon, J. L. Jr., J. Am. Ceram, Soc. 63, 300 (1980).Google Scholar
12. Nakano, T., Kawanaka, T., Yasuda, H.Y., and Umakoshi, Y., Proc. 3rd Japan International SAMPE Symposium 1993, edited by: M. Yamaguchi and H. Fukutomi, p. 1334.Google Scholar
13. Yokoshima, S. and Yamaguchi, M., Proc. 3rd Japan International SAMPE Symposium 1993, edited by: M. Yamaguchi and H. Fukutomi, p. 1346.Google Scholar
14. Appel, F., Sparka, U. and Wagner, R., Thermally Activated Processes and Dislocation Mobilities in γ-Titanium Aluminides, these Proceedings.Google Scholar
15. Yoo, M.H., Fu, C.L. and Lee, J.K., J. Phys. III 1, 1065 (1991).Google Scholar
16. Appel, F., Christoph, U. and Wagner, R., submitted to Phil. Mag. A.Google Scholar