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Static and Dynamic Strain Ageing in Two-Phase Gamma Titanium Aluminides

Published online by Cambridge University Press:  21 March 2011

U. Christoph
Affiliation:
GKSS Research Centre, Institute for Materials Research, D-21502 Geesthacht, Germany
F. Appel
Affiliation:
GKSS Research Centre, Institute for Materials Research, D-21502 Geesthacht, Germany
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Abstract

The deformation behaviour of two-phase titanium aluminides was investigated in the intermediate temperature interval 450–750 K where the Portevin-LeChatelier effect occurs. The effect has been studied by static strain ageing experiments. A wide range of alloy compositions was investigated to identify the relevant defect species. Accordingly, dislocation pinning occurs with fast kinetics and is characterized by a relatively small activation energy of 0.7 eV, which is not consistent with a conventional diffusion process. Furthermore, the strain ageing phenomena are most pronounced in Ti-rich alloys. This gives rise to the speculation that antisite defects are involved in the pinning process. The implications of the ageing processes on the deformation behaviour of two-phase titanium aluminide alloys will be discussed.

Type
Research Article
Copyright
Copyright © Materials Research Society 2001

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