High resolution energy loss research: Si compounds and ceramics. Progress report, January 1, 1988--January 1, 1989
Analytical and high resolution electron microscopes are used to investigate interfaces, grain boundaries and triple junctions in a number of materials. Interfaces between silicon carbide whiskers and either aluminum oxide or silicon nitride grains in two different ceramic matrix composites were found to be mostly crystalline, and did not contain a continuous amorphous phase. The amount of amorphous phase in these interfaces depended primarily on the amount of sintering aid used. Amorphous multiphase regions at triple grain junctions in several structural ceramics were shown to consists of fibrous graphite microcrystals in an oxygen containing amorphous matrix. We consider it likely that these regions act as fracture nuclei for structural ceramics and composites. Grain boundaries from a large silicon bicrystal with {Sigma}13 (32) structure were examined by atomic resolution and electron energy loss microscopy; this boundary is composed of theoretically perfect regions and regions to which oxygen had segregated during crystal growth. Detailed microstructural analysis of a liquid phase sintered body made from silicon dioxide, aluminum oxide and silicon nitride showed that silicon oxynitride is apparently nucleated at the liquid/silicon nitride interface; the structure of the silicon oxynitride/silicon nitride interface is strongly anisotropic. Instrumentation and theory are also discussed.
- Research Organization:
- Arizona State Univ., Tempe, AZ (United States). Center for Solid State Science
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG02-87ER45305
- OSTI ID:
- 10119657
- Report Number(s):
- DOE/ER/45305-2; ON: DE92007118
- Resource Relation:
- Other Information: PBD: [1989]
- Country of Publication:
- United States
- Language:
- English
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