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Static and Dynamic Strain Aging in Two-Phase γ-Titanium Aluminides

Published online by Cambridge University Press:  15 February 2011

U. Christoph ,
F. Appel  and
R. Wagner
U. Christoph
Affiliation:
Institute for Materials Research, GKSS Research Center, Max-Planck-Str., D-21502 Geesthacht, Germany
F. Appel
Affiliation:
Institute for Materials Research, GKSS Research Center, Max-Planck-Str., D-21502 Geesthacht, Germany
R. Wagner
Affiliation:
Institute for Materials Research, GKSS Research Center, Max-Planck-Str., D-21502 Geesthacht, Germany
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Abstract

Deformation of two-phase titanium aluminides exhibits discontinuous yielding and a negative strain rate sensitivity over the temperature range 450–750 K. These phenomena are usually associated with the Portevin-LeChatelier effect which is due to the dynamic interaction of diffusing defects with the dislocations. The resulting glide resistance was investigated by static strain aging. The experiments involve the prestraining of samples followed by aging under a relaxing load for certain periods of time. Reloading of the samples resulted in distinct yield points. The investigations were performed on two-phase γ-titanium aluminides having different compositions and microstructures which are currently being considered for technical applications. Accordingly, dislocation locking occurs with fast kinetics which is characterized by a low activation energy. The experimental results will be discussed with respect to the nature of the diffusional mechanism and possible implication on the mechanical properties of the materials.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 460: Symposium Z – High-Temperature Ordered Intermetallic Alloys VII , 1996 , 207
Copyright
Copyright © Materials Research Society 1997

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References

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