{alpha} {r_arrow} {beta} reverse phase transformation in silicon carbide in silicon nitride-particulate-reinforced-silicon carbide composites

Journal Article · Fri Nov 01 04:00:00 EST 1996 · Journal of the American Ceramic Society

DOI:https://doi.org/10.1111/j.1151-2916.1996.tb08723.x· OSTI ID:417774

Turan, S; Knowles, K M ^[1]

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1. Univ. of Cambridge (United Kingdom). Dept. of Materials Science and Metallurgy

The {alpha} {r_arrow} {beta} reverse transformation in SiC is observed in Si{sub 3}N{sub 4}-particulate-reinforced-SiC composites made from as-received {alpha}-SiC and {alpha}-Si{sub 3}N{sub 4} powders. However, the transformation does not occur to any great extent in composites made from deoxidized Si{sub 3}N{sub 4}-SiC powder compacts. Detailed transmission electron microscopy shows that most interfaces are covered with an {approximately}10 {angstrom} thick amorphous intergranular film in the composites made from as-received powders, whereas most interfaces are free of such films in the composites made from deoxidized powder compacts. These observations indicate that the {alpha} {r_arrow} {beta} reverse transformation in SiC is encouraged by a nitrogen-containing liquid phase that occurs at high temperature in the composites made from the as-received powders. A mechanism is proposed to account for the experimental observations.

• Sponsoring Organization: USDOE
• OSTI ID: 417774
• Journal Information: Journal of the American Ceramic Society, Journal Name: Journal of the American Ceramic Society Journal Issue: 11 Vol. 79; ISSN 0002-7820; ISSN JACTAW
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
42 ENGINEERING
COMPOSITE MATERIALS
CRYSTAL-PHASE TRANSFORMATIONS
ELECTRONIC EQUIPMENT
EXPERIMENTAL DATA
HOT PRESSING
POWDERS
SILICON CARBIDES
SILICON NITRIDES
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION