Abstract
The microstructural stability of SCS-6 SiC monofilaments was determined by measuring the average grain size, tensile strength and critical length of the fibres as a function of various annealings in vacuum (≈0.1 Pa) at different temperatures (1400–1600 °C). The average grain size, calculated from X-ray diffraction line broadening, increased from 23 nm for the as-received fibres to 46 nm for fibres annealed for 2 h at 1600 °C. The corresponding tensile strength measured at room temperature dropped from 3.6 GPa for the as-received fibres to ≈2 GPa for the treated fibres. Simultaneously, the average critical lengths, measured using the glass-slide technique decreased from 0.37 mm for the as-received fibres to an average of 0.23 mm for the heat-treated fibres. The degradation of the mechanical properties was attributed to a combination of coarsening of the β-SiC grains as well as interactions with the annealing environment, namely the vacuum hot-press chamber.
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Elkind, A., Barsoum, M.W. Grain growth and strength degradation of SiC monofilaments at high temperatures. JOURNAL OF MATERIALS SCIENCE 31, 6119–6123 (1996). https://doi.org/10.1007/BF00354427
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DOI: https://doi.org/10.1007/BF00354427