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The Study of Defects in Metals Using High Resolution Transmission Electron Microscopy and Atomistic Calculations

Published online by Cambridge University Press:  21 February 2011

M. J. Mills  and
M. S. Daw
M. J. Mills
Affiliation:
Sandia National Laboratories, Livermore, CA 94551-0969
M. S. Daw
Affiliation:
Sandia National Laboratories, Livermore, CA 94551-0969
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Abstract

The coupling of HRTEM with atomistic calculations is described for the study of grain boundaries and dislocations in aluminum. HRTEM images of the Σ9 (221) [110] grain boundary are compared with molecular statics calculations using both the Embedded Atom Method (EAM) and two pair potentials. Comparison between observed and simulated images are shown to serve as a stringent test of the theoretical methods. Atomistic calculations can in turn provide threedimensional information about the defect structure. Using the EAM, it is also possible to account for the effects of thin foil geometries on the minimim energy configuration of defects. While these effects are found to be minimal for grain boundary structures, the influence of the thin-foil geometries on the core structure of the 60° dislocation in aluminum is discussed. These comparisons indicate that the EAM function provides a good description of grain boundary structures, but fails to reproduce the observed dislocation core structure due to a low predicted value of the intrinsic stacking fault energy (SFE) on the (111). In contrast, the pair potentials used in this study provide reasonable SFE values, but appear to be less accurate for the prediction of the Σ9 (221) [110] grain boundary structures.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 183: Symposium E – High Resolution Electron Microscopy of Defects in Materials , 1990 , 15
Copyright
Copyright © Materials Research Society 1990

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