High resolution energy loss research: Si compounds and ceramics

Technical Report · Sun Jan 01 00:00:00 EST 1989

DOI:https://doi.org/10.2172/5917397· OSTI ID:5917397

Carpenter, R W

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; USDOE, Washington, DC (United States)
• DOE Contract Number: FG02-87ER45305
• OSTI ID: 5917397
• Report Number(s): DOE/ER/45305-2; ON: DE92007118
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CERAMICS
ENERGY-LOSS SPECTROSCOPY
MICROSTRUCTURE
SILICON COMPOUNDS
COMPOSITE MATERIALS
ELECTRON MICROSCOPY
GRAIN BOUNDARIES
INTERFACES
PROGRESS REPORT
SILICON CARBIDES
SILICON NITRIDES
CARBIDES
CARBON COMPOUNDS
CRYSTAL STRUCTURE
DOCUMENT TYPES
ELECTRON SPECTROSCOPY
MATERIALS
MICROSCOPY
NITRIDES
NITROGEN COMPOUNDS
PNICTIDES
SPECTROSCOPY
360202* - Ceramics
Cermets
& Refractories- Structure & Phase Studies