High resolution interface nanochemistry and structure: Final project report, December 1, 1993--February 28, 1997

Work includes studies of interface and grain boundary chemistry and structure in silicon nitride matrix/silicon carbide whisker composites, and in monolithic silicon nitride and silicon carbide synthesized by several different methods. Off-stoichiometric, impurity, and sintering aid elemental distributions in these materials (and other ceramics) have been of great interest because of expected effects on properties but these distributions have proven very difficult to measure because the spatial resolution required is high. The authors made a number of these measurements for the first time, using techniques and instrumentation developed here. Interfaces between metals and SiC are the basis for important metal matrix composites and contacts for high temperature SiC-based solid state electronic devices. The authors have investigated ultrapure interfaces between Ti, Hf, Ti-Hf alloys, Pt, and Co and Si-terminated (0001) 6H SiC single crystals for the first time