SiC fiber strength after consolidation and heat-treatment in Ti-22Al-23Nb matrix composite

In any composite development effort it is important to demonstrate that modifications in constituents or in the fabrication process do not adversely affect the other constituents or the resulting composite properties. Previous work has demonstrated that the extracted fiber strength distribution in as-consolidated composites is different than typical virgin fiber strength distributions and that composite heat-treatments in an inert environment may further degrade fiber strength. The degree to which a composite can withstand elevated temperature exposure depends on the kinetics of the fiber-matrix interaction which is related to the matrix chemistry and microstructure. Smith et al. have characterized the reaction kinetics of several Ti-Al-Nb alloys with SiC fiber, but the effect of the reaction on fiber strength had not been measured. The goal of this work was to establish the effect of composite consolidation in a Ti-22Al-23 Nb (atomic percent) matrix on the fiber strength distribution. The consequences of post-consolidation heat treatments, as well as prolonged high temperature exposure, on fiber strength were also evaluated