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Characterizing Defect Structures in Ordered Alloys Using Electron Microscopy and Computed Image Simulations

Published online by Cambridge University Press:  01 January 1992

K.J. Hemker
Affiliation:
Institut Genie Atomique, EPFL, CH-1015 Lausanne, Switzerland
B. Viguier
Affiliation:
Institut Genie Atomique, EPFL, CH-1015 Lausanne, Switzerland
R. Schäublin
Affiliation:
Institut Genie Atomique, EPFL, CH-1015 Lausanne, Switzerland
M.J. Mills
Affiliation:
Sandia National Laboratories, Livermore, CA, 94551-0969
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Abstract

The resolution offered by weak-beam transmission electron microscopy allows for the direct observation of partial dislocations in a large number of intermetallic alloys. In many instances, the comparison of these observations with computer simulated images leads to results that are much more quantitative and descriptive than are possible with ordinary analyses. Examples from several parallel studies are presented: i) comparisons of experimental and simulated images that have been used to characterize extrinsic stacking faults in TiAl are shown, ii) the need to correct the experimentally observed antiphase boundary dissociations (dAPB) in Ni3Al in order to account for the image shifts that occur during microscopy are highlighted, and iii) dissociation distances of less than 2 nm, which were observed with (2g-5g) diffraction conditions, were verified and quantified by comparisons with computer simulated images. Antiphase boundary energies (γAPB) and complex stacking fault energies (γCSF) were calculated from the corrected observations, and it was found that the APB energies did not depend on alloy content, but that the CSF energy of binary Ni3Al is less than it is for a boron containing alloy.

Type
Research Article
Copyright
Copyright © Materials Research Society 1995

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References

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