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Spatial Distribution of Crystallographic Orientational Variants in Yag-Al2O3 Directionally Solidified Eutectic Composite

Published online by Cambridge University Press:  02 July 2020

Colleen S. Frazer
Affiliation:
Dept. of Chemical and Materials Engineering, University of Kentucky, Lexington, KY40506
Elizabth C. Dickey
Affiliation:
Dept. of Chemical and Materials Engineering, University of Kentucky, Lexington, KY40506
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YAG-A12O3 directionally solidified eutectic composites show great promise in applications requiring high temperature strength and creep resistance.’ The orientation relationships between YAG and Al2O3 have been established within the composite by use of SEM Electron Backscatter Diffraction (EBSD) and x-ray diffraction (XRD). The orientation relationships of were determined. Two related variants of A12O3 were discovered in the sample. EBSD was employed to determine the spatial distribution of the variants within the sample.

The microstructure of the eutectic composite, shown in Figure 1, reflects a “chinese script” pattern, neither lamellar nor fibrous. The directionally solidified eutectic fibers, approximately 2.5 mm in diameter, were cut into disks normal to the fiber axis by a diamond saw and polished by with diamond-imbedded paper to reduce chances of phase-preferential wear. Samples used for EBSD were ion milled for 30 minutes at low power and incident angle to improve the patterns.

Type
Advances in the Instrumentation and Application of Electron Backscatter Diffraction in the SEM
Copyright
Copyright © Microscopy Society of America

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References

References:

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4. The aid of Dr.T.Watkins and Dr.C.Hubbard of the High Temperature Materials Laboratory at Oak Ridge National Laboratory is gratefully acknowledged.Google Scholar
5. This work was supported by the Department of Energy under grant#DE-FG-02-98ER-45710 and the AFSOR under grant #F49620-99-1-0266.Google Scholar