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Accession Number N20120012883
Title TEM Observation of the Ti Interlayer Between SiC Substrates During Diffusion Bonding.
Publication Date May 2012
Media Count 9p
Personal Author H. Tsuda M. Singh M. C. Halbig S. Mori
Abstract Diffusion bonding was carried out to join SiC to SiC substrates using titanium interlayers. In this study, 10 m and 20 m thick physical vapor deposited (PVD) Ti surface coatings, and 10 and 20 m thick Ti foils were used. Diffusion bonding was performed at 1250 C for PVD Ti coatings and 1200 C for Ti foil. This study investigates the microstructures of the phases formed during diffusion bonding through TEM and selected-area diffraction analysis of a sample prepared with an FIB, which allows samples to be taken from the reacted area. In all samples, Ti3SiC2, Ti5Si3Cx and TiSi2 phases were identified. In addition, TiC and unknown phases also appeared in the samples in which Ti foils were used as interlayers. Furthermore, Ti3SiC2 phases show high concentration and Ti5Si3Cx formed less when samples were processed at a higher temperature and thinner interlayer samples were used. It appears that the formation of microcracks is caused by the presence of intermediate phase Ti5Si3Cx, which has anisotropic thermal expansion, and by the presence of an unidentified Ti-Si-C ternary phase with relatively low Si content.
Keywords Anisotropy
Diffusion welding
Interlayers
Ion beams
Microcracks
Microstructure
Scanning electron microscopy
Silicon carbides
Substrates
Thermal expansion
Titanium
Transmission electron microscopy
Vapor deposition


 
Source Agency National Aeronautics and Space Administration
NTIS Subject Category 71F - Composite Materials
Corporate Author National Aeronautics and Space Administration, Cleveland, OH. NASA John H. Glenn Research Center at Lewis Field.
Document Type Conference proceedings
Title Note N/A
NTIS Issue Number 1303
Contract Number N/A

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