Journal of the American Ceramic Sociery-Morscher and Martines-Fernandes Vol. 82. No (b) 0.5mm Matrix Cracks Fig. 5. SEM micrographs of the fracture surfaces of the Hi-Nicalon/PBN/CVI-SiC m incOmposite( (a)matrix crack 300 um away from the fracture urface and(b) matrix crack 1200 um away from the fracture surface) 868428K Fig. 6. SEM micrographs of the fracture surfaces of the Sylramic/PBN/SiC minicomposite((a) matrix crack is <100 um from the fracture surface Figs. 6(b)and (c)show that fiber pullout occurs throughout the minicomposite)Fig. 5. SEM micrographs of the fracture surfaces of the Hi-Nicalon/PBN/CVI-SiC minicomposite ((a) matrix crack 300 mm away from the fracture surface and (b) matrix crack 1200 mm away from the fracture surface). Fig. 6. SEM micrographs of the fracture surfaces of the Sylramic/PBN/SiC minicomposite ((a) matrix crack is <100 mm from the fracture surface; Figs. 6(b) and (c) show that fiber pullout occurs throughout the minicomposite). 148 Journal of the American Ceramic Society—Morscher and Martinez-Fernandez Vol. 82, No. 1