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Microstructure and Microchemistry of Y-Doped a-Al203

Published online by Cambridge University Press:  02 July 2020

M. A. Giilgiin
Affiliation:
Max-Planck Institut fur Metallforschung, Seestr. 92, D-70174Stuttgart, Germany.
M. L. Mulvihill
Affiliation:
Max-Planck Institut fur Metallforschung, Seestr. 92, D-70174Stuttgart, Germany.
V. Putlayev
Affiliation:
Chemistry Dept., Moscow State University, Moscow, 119899, Russia.
M. Riihle
Affiliation:
Max-Planck Institut fur Metallforschung, Seestr. 92, D-70174Stuttgart, Germany.
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Extract

A thorough microstructural study of common ceramics requires analysis at various length scales. Yttrium doped, polycrystalline α-Al203 was studied using a broad selection of microscopy techniques over a scale range covering seven-orders of magnitude (i.e. from mm to Å).

Yttrium doped, (1000 (Y/Al) atomic ppm) polycrystalline alumina samples were prepared by hot pressing at 1450°C at 50 MPa. Some were subsequently crept in tension. Microstructure of these samples was studied by optical microscopy, scanning electron/orientation imaging microscopy (OIM™), conventional and high resolution transmission electron microscopy. Analytical electron microscopy was performed on a VG HB501 FEG-STEM equipped with an EDS and PEELS.

On a large scale, the microstructure often consisted of bimodal sized alumina grains and second phase YAG (Y3A15012) precipitates. YAG precipitates at grain boundaries (GB) and triple points caused clusters (50μm to 1mm) of small equi-axed alumina grains (0.5-2 μm) randomly distributed over 40 area% of the sample.

Type
Microscopy of Ceramics and Minerals
Copyright
Copyright © Microscopy Society of America

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References

(1) Cho, J. et al., J. Am. Ceram. Soc. 80, 10131017 (1997).CrossRefGoogle Scholar

(2) Authors gratefully acknowledge Harmer, M. P. for supplying the samples.Google Scholar

(3) Mulvihill, M.L. is supported by Humboldt, A. V. Research Fellowship.Google Scholar