Correlation between Neutron Diffraction Measurements and Thermal Stresses in a Silicon Carbide/Alumina Composite

• Published in: Journal of the American Ceramic Society 1990-11, Vol.73 (11), p.3428-3432
• Main Authors: Tomé, Carlos N., Bertinetti, María A., MacEwan, Stuart R.
• Format: Article
• Language: English
• Subjects: Applied sciences; Building materials. Ceramics. Glasses; Ceramic industries; Chemical industry and chemicals; composites; diffraction; Exact sciences and technology; modeling; neutrons; stress; Structural ceramics; Technical ceramics
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/j.1151-2916.1990.tb06471.x

Sintering of Al2O3 powder and SiC fibers at high temperatures leads to a state of high internal stresses in the composite material at room temperature because of the difference in thermal contraction between both materials. These stresses are calcualted in this work using the scheme of the elastic elliposidal inclusion of Eshelby and regarding the fibers as prolate ellipsoids. The predicted strain in the fibers is used to calculate variations in the spacing of crystallographic planes and the results are compared against experimental measurements obtained with neutron diffraction by other authors. We show that in order to correlate the measurements with the actual stress state, it is necessary to account for the elastic anisotropy and the proper crystallographic structure of the fibers. We demonstrate that the interpretation also depends on the distribution of fiber orientations inside the matrix and that results can be substantially changed depending on the assumptions employed.