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Creep Properties of a High Niobium Containing γ-TiAl Alloy Sheet Material

Published online by Cambridge University Press:  11 February 2011

A. Bartels
Affiliation:
Technical University of Hamburg-Harburg, Dept. Materials Science and Technology, Eissendorfer Str. 42, D-21071 Hamburg, Germany
S. Bystrzanowski
Affiliation:
Technical University of Hamburg-Harburg, Dept. Materials Science and Technology, Eissendorfer Str. 42, D-21071 Hamburg, Germany
R. Gerling
Affiliation:
Institute for Materials Research, GKSS-Research Center, Max-Planck-Str., D-21502 Geesthacht, Germany
F.-P. Schimansky
Affiliation:
Institute for Materials Research, GKSS-Research Center, Max-Planck-Str., D-21502 Geesthacht, Germany
H. Kestler
Affiliation:
Plansee AG, Technology Center, A-6600 Reutte, Austria
M. Weller
Affiliation:
Max-Planck-Institut fuer Metallforschung, Heisenbergstr. 3, D-70569 Stuttgart, Germany
H. Clemens
Affiliation:
Institute for Materials Research, GKSS-Research Center, Max-Planck-Str., D-21502 Geesthacht, Germany
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Abstract

In this study Ti-46Al-9Nb (at%) sheet material processed by a powder metallurgical route was examined. Subsequent to hot rolling the sheets were subjected to a stress-relief treatment at 1273K for 3 hours. During this heat treatment a fine-grained near gamma microstructure has been formed. 100 hours tensile creep tests under constant load were carried out at 700°C in rolling direction, transverse direction as well as 45° direction. Using the method of load changes a stress exponent of 4.1 was determined. Furthermore, the apparent activation energy was determined in the temperature range of 715 – 775°C. Both stress exponent and activation energy suggest that diffusion assisted dislocation climb is the dominant creep mode. A comparison of these results with those of so-called conventional or so-called “2nd generation” γ-TiAl based alloys, e.g. Ti-46.5Al-4(Cr,Nb,Ta,B) (at%) and Ti-47Al-4(Cr,Mn,Nb,Si,B) (at%), indicates a significantly better creep resistance and a higher activation energy of the high Nb containing alloy. Additionally, internal friction experiments were conducted in order to analyze the deformation behavior under very small strains at elevated temperatures.

Type
Research Article
Copyright
Copyright © Materials Research Society 2003

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References

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