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Thermally Activated Processes and Dislocation Mobilities in Two-Phase γ-Titanium Aluminides

Published online by Cambridge University Press:  22 February 2011

Fritz Appel ,
Ulf Sparka  and
Richard Wagner
Fritz Appel
Affiliation:
Institute for Materials Research, GKSS Research Center, Max-Planck-Str., D-21502 Geesthacht, Germany.
Ulf Sparka
Affiliation:
Institute for Materials Research, GKSS Research Center, Max-Planck-Str., D-21502 Geesthacht, Germany.
Richard Wagner
Affiliation:
Institute for Materials Research, GKSS Research Center, Max-Planck-Str., D-21502 Geesthacht, Germany.
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Abstract

The processes controlling the dislocation mobility in two-phase γ-titanium aluminides have been investigated over a wide temperature range by determining the activation volumes and activation energies of thermally activated dislocation glide processes. The deformation tests are supplemented by electron microscope observations. Accordingly, at room temperature the mobility of ordinary dislocations is determined by a combination of localized pinning and lattice friction. Additional glide resistance arises from dislocation dipoles and debris defects, which are trailed and terminated at jogs in 1/2 <110] screw dislocations. Dislocation climb processes start above 900 K and seem to initiate the transition from brittle to ductile material behaviour.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 364: Symposium L – High-Temperature Ordered Intermetallic Alloys–VI , 1994 , 623
Copyright
Copyright © Materials Research Society 1995

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