Fabrication of discontinuous ceramic fibers/FeAl composites by reactive sintering

The chemical compatibility of reinforcements, processing and fracture characteristics of delta-Al2O3 short fiber and beta-SiC whisker reinforced FeAl composites with the matrix composition of 40 similar to 50 at%Al were examined. The beta-SiC whisker does not react severely with FeAl in the temperature range below 1400 K. The FeAl matrix composites of full density are successfully fabricated by the reactive hot press sintering at 1273 similar to 1373 K. The proportional limit of Fe-40 at%Al matrix increases slightly by the addition of delta-Al2O3 short fibers due to the extremely weak bonding at the matrix/fiber interfaces. Although the beta-SiC whisker reinforced Fe-40 at%Al composites exhibits brittle fracture by the whisker addition beyond 15 vol%, the remarkable strengthening is achieved at volume fractions of 5 similar to 10 vol%. The brittle Fe-50 at%Al matrix is hardly strengthened at room temperature by the additions of delta-Al2O3 short fibers and of beta-SiC whiskers. The fracture toughness of the FeAl matrix composites reinforced with both the discontinuous fibers is reduced at higher volume fractions.