Interdiffusion in SiC-AlN and AlN-Al{sub 2}OC systems

Journal Article · Thu Aug 01 04:00:00 EDT 1996 · Journal of the American Ceramic Society

DOI:https://doi.org/10.1111/j.1151-2916.1996.tb08952.x· OSTI ID:382466

Tian, Q; Virkar, A V ^[1]

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1. Univ. of Utah, Salt Lake City, UT (United States). Dept. of Materials Science and Engineering

AlN, Al{sub 2}OC, and the 2H form of SiC are isostructural. Both SiC-AlN and AlN-Al{sub 2}OC form homogeneous solid solutions above 2000 and 1950 C, respectively. The kinetics of phase separation in the two systems, however, are quite different. Interdiffusion in both SiC-AlN and AlN-Al{sub 2}OC systems was examined in the solid-solution regime in an attempt to elucidate differences in the kinetics of phase separation that occur in the two systems when annealed at lower temperatures. Diffusion couples of (SiC){sub 0.3}(AlN){sub 0.7}/(SiC){sub 0.7}(AlN){sub 0.3} and (AlN){sub 0.7}(Al{sub 2}OC){sub 0.3}/(AlN){sub 0.3}(Al{sub 2}OC){sub 0.7} were fabricated by hot pressing and were annealed at high temperatures by encapsulating them in sealed SiC crucibles to suppress loss due to evaporation. Interdiffusion coefficients in (SiC){sub 0.3}-(AlN){sub 0.7}/(SiC){sub 0.7}(AlN){sub 0.3} diffusion couples were measured at 2,373, 2473, and 2573 K, and the corresponding activation energy was determined to be 632 kJ/mol. (AlN){sub 0.7}(Al{sub 2}OC){sub 0.3}/(AlN){sub 0.3}(Al{sub 2}OC){sub 0.7} samples were annealed at 2273 K. The interdiffusion coefficient measured in the AlN-Al{sub 2}OC system was much larger than that in the SiC-AlN system.

• Sponsoring Organization: USDOE
• OSTI ID: 382466
• Journal Information: Journal of the American Ceramic Society, Journal Name: Journal of the American Ceramic Society Journal Issue: 8 Vol. 79; ISSN 0002-7820; ISSN JACTAW
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ACTIVATION ENERGY
ALUMINIUM COMPOUNDS
ALUMINIUM NITRIDES
ANNEALING
CHEMICAL COMPOSITION
HOT PRESSING
KINETICS
OXYCARBIDES
PHASE STUDIES
POWDERS
SAMPLE PREPARATION
SELF-DIFFUSION
SILICON CARBIDES
SOLID SOLUTIONS
TEMPERATURE DEPENDENCE