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Microstructural Changes During Long-Term Tension Creep of Two-Phase γ-Titanium Aluminide Alloys

Published online by Cambridge University Press:  15 February 2011

M. Oehring
Affiliation:
Institute for Materials Research, GKSS Research Centre Geesthacht, Max-Planck-Str., D-21502 Geesthacht, Germany
P. J. Ennis
Affiliation:
Jülich Research Centre, Institute for Materials in Energy Systems, PO Box 1913, D-52425, Jülich, Germany
F. Appel
Affiliation:
Institute for Materials Research, GKSS Research Centre Geesthacht, Max-Planck-Str., D-21502 Geesthacht, Germany
R. Wagner
Affiliation:
Institute for Materials Research, GKSS Research Centre Geesthacht, Max-Planck-Str., D-21502 Geesthacht, Germany
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Abstract

Long-term tension creep tests were performed on a Ti-48 at.% Al-2 at.% Cr alloy in order to assess the material behaviour under the intended service conditions for structural parts in turbine engines. Deformation processes and microstructural changes were investigated by TEM on a specimen loaded to 140 MPa for 5988 h at 700 °C. At lamellar boundaries the emission of interfacial dislocations was observed and is thought to contribute significantly to the high primary creep rate of the material. Under the creep conditions gliding dislocations apparently become locked by the heterogeneous formation of precipitates along their cores. Lamellar interfaces revealed ledges which indicates that they migrate during creep.

Type
Research Article
Copyright
Copyright © Materials Research Society 1997

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References

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