Morphology of phase separation in AlN-Al sub 2 OC and SiC-AlN ceramics

Journal Article · Sat Sep 01 04:00:00 EDT 1990 · Journal of the American Ceramic Society; (USA)

OSTI ID:5901006

Virkar, A V ^[1]; Kuo, S Y ^[2]

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1. Dept. of Materials Science and Engineering, Univ. of Utah, Salt Lake City, UT (US)
2. Diamond Technology Center, Norton, Co., Salt Lake City, UT (US)

Solid solutions in the AIN-Al{sub 2}OC and SiC-AlN systems were fabricated by hot-pressing powder mixtures in graphite dies. X-ray diffraction showed the samples to be single phases of 2H structure. The samples were annealed between 1600{degrees} and 1900{degrees}C for up to 1000 h. In the SiC-AlN system, optical microscopy and X-ray diffraction failed to reveal microstructural or phase changes. However, electron microscopy showed that samples had decomposed. Streaking of diffraction spots occurred along directions orthogonal to (012) planes ({approximately}43{degrees} off the c axis), which is approximately the direction along which the elastic energy function is a minimum. The orientation-dependent Young's modulus was also a minimum along this direction. In AlN-Al{sub 2}OC, optical microscopy and X-ray diffraction indicated the occurrence of decomposition. The precipitates were disk-shaped with (001) orthogonal to the disks. The occurrence of decomposition along the (001) direction suggests that it is the elastically soft direction.

• OSTI ID: 5901006
• Journal Information: Journal of the American Ceramic Society; (USA), Journal Name: Journal of the American Ceramic Society; (USA) Vol. 73:9; ISSN JACTA; ISSN 0002-7820
• Country of Publication: United States
• Language: English

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75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINIUM COMPOUNDS
ALUMINIUM NITRIDES
ALUMINIUM OXIDES
CARBIDES
CARBON
CARBON COMPOUNDS
CHALCOGENIDES
COHERENT SCATTERING
CRYSTALLOGRAPHY
DIFFRACTION
DISPERSIONS
ELECTRON MICROSCOPY
ELEMENTAL MINERALS
ELEMENTS
FABRICATION
GRAPHITE
HOT PRESSING
MATERIALS WORKING
MICROSCOPY
MINERALS
MIXTURES
MORPHOLOGY
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NITROGEN COMPOUNDS
NONMETALS
OPTICAL MICROSCOPY
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PNICTIDES
POWDERS
PRESSING
SCATTERING
SILICON CARBIDES
SILICON COMPOUNDS
SOLID SOLUTIONS
SOLUTIONS
X-RAY DIFFRACTION