Chemical and structural widths of interfaces and grain boundaries in silicon nitride-silicon carbide whisker composites
- Arizona State Univ., Tempe, AZ (United States)
The extent of chemical distributions into crystals bounding whisker/matrix interfaces and matrix grain boundaries and the lateral continuity of the distributions was investigated by analytical electron microscopy methods and compared to their structural widths determined by high-resolution TEM. The extent of the distributions into the bounding crystals, defined as chemical widths, was 10 to 120 times the structural widths; this ratio was larger for grain boundaries than for he interfaces. Further, the chemical distributions were laterally discontinuous at interfaces but continuous at grain boundaries. The elements from the sintering aids, Y{sub 2}O{sub 3} and Al{sub 2}O{sub 3}, were the primary chemical distribution constituents. The distributions were examined by the new position-resolved electron energy loss spectroscopy and Z-contrast scanning TEM methods. Microstructural observations indicated that chemical widths resulted from solid-state diffusion into the bounding crystals and that lateral discontinuities in the distributions resulted from preferential Gibbs-Thompson solution effects of the whisker surfaces at interfaces. These nonequilibrium distributions are process-dependent, and are expected to affect composite properties.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FG03-94ER45510
- OSTI ID:
- 131525
- Journal Information:
- Journal of the American Ceramic Society, Vol. 78, Issue 10; Other Information: PBD: Oct 1995
- Country of Publication:
- United States
- Language:
- English
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