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Creep Mechanisms in Equiaxed and Lamellar Ti-48Al

Published online by Cambridge University Press:  21 March 2011

G. B. Viswanathan ,
S. Karthikeyan ,
V. K. Vasudevan  and
M. J. Mills
G. B. Viswanathan
Affiliation:
Department of Materials Science and Engineering, The Ohio State University, Columbus, OH 43210
S. Karthikeyan
Affiliation:
Department of Materials Science and Engineering, The Ohio State University, Columbus, OH 43210
V. K. Vasudevan
Affiliation:
Department of Materials Science and Engineering, University Of Cincinnati, Cincinnati, OH 45221
M. J. Mills
Affiliation:
Department of Materials Science and Engineering, The Ohio State University, Columbus, OH 43210
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Abstract

Minimum creep rates as a function of stress have been obtained for Ti-48Al binary alloy with a near gamma and a fully lamellar microstructure. TEM investigation reveals that deformation structures in both microstructures are dominated by jogged screw 1/2[110] dislocations in γ phase. A modif ied jogged screw model is adopted to predict minimum creep rates where the rate controlling step is assumed to be the non-conservative motion of 1/2[110] unit dislocations. In the case of equiaxed microstructure where the deformation was mostly uniform, the creep rates predicted by this model were in agreement with experimental values. Conversely, deformation in lamellar microstructures were highly inhomogeneous where the density of jogged 1/2[110] unit dislocations were seen in varying proportions depending on the width of the γ laths. The creep rates and stress exponents in these microstructures is explained in terms of active volume fractions of γ laths participating in deformation for a given applied stress.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 646 , 2000 , N1.6.1
Copyright
Copyright © Materials Research Society 2001

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References

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