Microsc. Microanal. Microstruct. 6, 587-599 (1995)
DOI: 10.1051/mmm:1995102

Local Chemistry at Interfaces and Boundaries: Ceramic and Electronic Composite Materials

R.W. Carpenter¹, J.S. Bow¹, M.J. Kim¹, K. Das Chowdhury¹ et W. Braue<sup>2

1</sup>  Center for Solid State Science and the Science and Engineering of Materials Program, Arizona State University, Tempe AZ 85287-1704, U.S.A.
²  German Aerospace Research Establishment (DLR), Materials Research Institute, 51147 Cologne, Germany

Abstract
The spatial extent of chemical solute distributions that formed in interfaces between platinum or silicon nitride and silicon carbide or in silicon nitride grain boundaries during high temperature processing of these composites has been investigated by position resolved nanospectroscopy, Z-contrast imaging and energy selected imaging. The solute distributions resulted from intentional sintering aid additions or interfacial reaction. The distribution widths normal to the nominal interface/boundary planes, called chemical interface/boundary widths, were much larger than the corresponding structural widths of the same boundaries and interfaces, determined by HREM imaging. Qualitative agreement between the three methods used to determine chemical widths was excellent. Differences in count rate resulting from beam current differences among the methods resulted is some predictable quantitative disagreements in absolute chemical widths. Energy selected imaging proved to be a very fast, efficient method for examination of chemical distributions over large specimen areas.

PACS
8265J - Heterogeneous catalysis at surfaces and other surface reactions.
6116D - Electron microscopy determinations of structures.

Key words
ceramics -- composite materials -- electron microscopy -- grain boundaries -- platinum -- silicon compounds -- sintering -- surface chemistry -- ceramics -- composite materials -- chemical solute distributions -- grain boundaries -- high temperature processing -- position resolved nanospectroscopy -- Z contrast imaging -- energy selected imaging -- sintering aid -- interfacial reaction -- boundary width -- HREM -- count rate -- beam current -- Pt SiC -- Si sub 3 N sub 4 SiC


© EDP Sciences 1995