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Dislocation Core Structure and the Anomalous Yield Behavior of Li2 Ordered Alloys At Elevated Temperatures

Published online by Cambridge University Press:  21 February 2011

V. Vitek  and
D. P. Pope
V. Vitek
Affiliation:
Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104
D. P. Pope
Affiliation:
Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104
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Abstract

In many LI2 ordered alloys the flow stress increases with increasing temperature and is in this “anomalous” regime strongly dependent on orientation and sense of the applied stress. These dependences can be predicted from the nature of the dissociation and core structure of the 1/2<101> screw superpartials in these alloys. Computer modelling shows that two different configurations, a glissile one on {lll} planes and a sessile one on {010} planes, exist and both are described here in detail. The anomalous increase of the flow stress may then be explained by an increasing amount of core transformations from the glissile to sessile forms as the temperature increases. The theoretical model for the immobilization of screw dislocations by this mechanism is then discussed and its validity illustrated by comparison with experimental results on Ni3 (Al, Ta) single crystals.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 39: Symposium G – High-Temperature Ordered Intermetallic Alloys I , 1984 , 205
Copyright
Copyright © Materials Research Society 1985

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