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The Use of Moiré Patterns in TEM Images to Measure Precipitate Composition in Al-Si-Ge Alloys

Published online by Cambridge University Press:  02 July 2020

V. Radmilovic
Affiliation:
Department of Materials Science and Mineral Engineering, University of California, Berkeley, CA, USA
D. Mitlin
Affiliation:
National Center for Electron Microscopy, Lawrence Berkeley Laboratory, University of California, Berkeley, CA, USA.
S. Hinderberger
Affiliation:
National Center for Electron Microscopy, Lawrence Berkeley Laboratory, University of California, Berkeley, CA, USA.
U. Dahmen
Affiliation:
National Center for Electron Microscopy, Lawrence Berkeley Laboratory, University of California, Berkeley, CA, USA.
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Abstract

Moiré patterns are commonly formed in multiphase system when diffracting planes of similar spacing and orientation lead to interference effects. They can be used experimentally to evaluate the stress distribution in materials [1], to analyze orientation relationships and latttice strain in diffraction contrast microscopy, or, combined with the related geometrical phase technique, to analyze displacements in high resolution lattice images [2,3]. The interpretation of moiré fringes is often not straightforward due to the elastic interaction between the crystals at the interface and the dynamical nature of electron diffraction [4]. However, if the two lattices are fully relaxed, or if a small precipitate crystal is embedded in a large matrix, moiré patterns can give a simple and direct measure of orientation and lattice constants. in the present work, the moiré technique has been applied to the quantitative analysis of lath-shaped Ge or Ge-Si precipitates in Al with the aim to determine the composition (the Si:Ge ratio) from the lattice parameter indicated by the moiré fringes.

Type
Quantitative Transmission Electron Microscopy of Interfaces (Organized by M. Rüehle, Y. Zhu and U. Dahmen)
Copyright
Copyright © Microscopy Society of America 2001

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References

References:

1.Post, D., Han, B. and Ifju, P., "High intensity Moire: experimental analysis for mechanics and materials", Springer Verlag, New York, 1996.Google Scholar
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6.This work was supported by the Director, Office of Basic Energy Sciences, Materials Science and Engineering Division, US Department of Energy, under contract DE-AC3-76SF00098.Google Scholar