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High-Resolution Electron Microscopy of Dislocation Cores in NiAl

Published online by Cambridge University Press:  10 February 2011

D. Stöckle ,
W. Sigle  and
A. Seeger
D. Stöckle
Affiliation:
Max-Planck-Institut für Metallforschung, Heisenbergstraße 1, 70569 Stuttgart, Germany
W. Sigle
Affiliation:
Max-Planck-Institut für Metallforschung, Seestraße 92, 70174 Stuttgart, Germany
A. Seeger
Affiliation:
Max-Planck-Institut für Metallforschung, Heisenbergstraße 1, 70569 Stuttgart, Germany
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Abstract

The atomic structure of dislocation cores in NiAl is studied by high-resolution transmission electron microscopy (HRTEM) and molecular dynamics (MD) calculations. Results are presented on dislocations with Burgers vectors b=a<100> and a<111>. A comparison with HRTEM image simulations indicates that the core of a 45° a <100> dislocation consists of Al atoms. The Burgers vector distribution shows a width of 2.2b. This corresponds very closely to MD results and is consistent with the relatively low Peierls stress of this dislocation. By detailed image analysis the angular dependence of the shear stress components of the dislocation are made visible. MD results obtained from 45° dislocations with opposite screw components suggest, that the helicity of the screw component might be discernible from high-resolution electron micrographs. A a<111> dislocation with <110> line direction is shown which exhibits a rather wide dissociation, probably into two a/2<111> partials.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 552: Symposium KK – High-Temperature Ordered Intermetallic Alloys VIII , 1998 , KK9.8.1
Copyright
Copyright © Materials Research Society 1999

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References

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