TY - JOUR
T1 - Nanoanalysis of Ceramic Composite Interfaces
AU - Carpenter, Ray
N1 - Funding Information:
The ceramic matrix composites described were provided by Drs. W. Braue and B. Saruhan, DLR, Cologne, Germany. The metal/SiC specimens were synthesized at North Carolina State University, by Prof. R. F. Davis and his students. The microscopy and microstructural analysis research is mainly from the doctoral dissertation research of Drs. K. Das Chowdhury and J. S. Bow in the Science and Engineering of Materials Program at ASU, and was supported by the United States Department of Energy under Grant DE-FG03-94ER45510 at Arizona State University.
PY - 1998
Y1 - 1998
N2 - Instrumentation requirements, particularly for small probes, for high resolution analytical electron microscopy are described. Analysis of structure and chemistry of interfaces in conventionally processed Si3N4/SiC(w) ceramic matrix composites (CMCs) and metal/(0001) 6H-SiC single crystal substrates are presented. All of these interfaces are characterized by a chemical and a structural width. In the CMCs, which were processed at high temperatures, the chemical widths formed by diffusion of sintering aids into the bulk microstructure and were always much larger than the corresponding structural widths. The metals on SiC were deposited near room temperature, where diffusion is slow. Significant chemical widths did not form, and microstructure was determined by crystallographic factors. Upon annealing, reaction zones with appreciable chemical widths did form, with interesting morphologies that separated naturally into two groups. For metals that formed stable suicides and carbides, e.g. Ti, all interfaces in the reaction zones remained nearly atomically flat over large distances. For metals that formed only stable suicides interfaces in the reaction zones were often curved, and sometimes formed closed surfaces, for relatively low annealing temperatures, suggesting that interface melting had occurred even at temperatures less than expected for Si-metal eutectics.
AB - Instrumentation requirements, particularly for small probes, for high resolution analytical electron microscopy are described. Analysis of structure and chemistry of interfaces in conventionally processed Si3N4/SiC(w) ceramic matrix composites (CMCs) and metal/(0001) 6H-SiC single crystal substrates are presented. All of these interfaces are characterized by a chemical and a structural width. In the CMCs, which were processed at high temperatures, the chemical widths formed by diffusion of sintering aids into the bulk microstructure and were always much larger than the corresponding structural widths. The metals on SiC were deposited near room temperature, where diffusion is slow. Significant chemical widths did not form, and microstructure was determined by crystallographic factors. Upon annealing, reaction zones with appreciable chemical widths did form, with interesting morphologies that separated naturally into two groups. For metals that formed stable suicides and carbides, e.g. Ti, all interfaces in the reaction zones remained nearly atomically flat over large distances. For metals that formed only stable suicides interfaces in the reaction zones were often curved, and sometimes formed closed surfaces, for relatively low annealing temperatures, suggesting that interface melting had occurred even at temperatures less than expected for Si-metal eutectics.
KW - Ceramic interfaces
KW - Chemical interface width
KW - High resolution electron microscopy
KW - Metal/silicon carbide interfaces
UR - http://www.scopus.com/inward/record.url?scp=0032155626&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0032155626&partnerID=8YFLogxK
U2 - 10.1023/A:1022607428479
DO - 10.1023/A:1022607428479
M3 - Article
AN - SCOPUS:0032155626
VL - 6
SP - 345
EP - 358
JO - Journal of Materials Synthesis and Processing
JF - Journal of Materials Synthesis and Processing
SN - 1064-7562
IS - 5
ER -