F.F. Lange et al Materials Science and Engineering A195(1995)145-150 5 400500600 2cyde.1250°c 100um b Fig 4. Load-displacement behavior of (a Al,O3-Si3N and(b) Al2O3-mullite composites. 10 (Fig. 4(a))and the Al2O3-mullite(Fig. 4(b))com posites. Extensive inelastic deformation is evident. The failure.(b) Typical fracture surface of Al, O,-SiN, composite step-wise load drops, beyond the peak stress, are showing fiber bundles with attached matrix characteristic of the behavior of laminar composites with crack-deflecting interfaces [40 Fig. 5(a)illustrates the"wood"-like fracture path of the Al,O3-Si3N4 composite. Fig. 5(b) illustrates a crack-like voids within the matrix and thus optimizes typical fracture surface, showing that fiber bundles are its strength. The matrix itself can act as a crack bonded together with the powder matrix, and that deflecting phase such that an all-oxide CMc can be crack deflection occurs within the matrix fabricated 6. Concluding remarks Acknowledgments Damage-tolerant continuous fiber CMCs can be This research was sponsored by the Defense luced by a powder route that packs particles within Advance Research Projects Agency through the a fiber preform by pressure filtration and then strength- University Research Initiative of UCSB under ONR ening the powder matrix by a cyclic precursor infiltra- Contract N00014-92-J-1808. Portions of this review tion method. High particle packing densities can be that concerned interparticle tentials that control achieved within the fiber preform provided that the particle packing density and the rheology of the slurry particle-to-fiber diameter ratio is small. Filling the and consolidated body were supported by the Office of interstices with particles first limits the size of the Naval Research under No0014-90-J-1441F.F. Lange et al. / Materials Science and Engineering A195 (1995) 145-150 149 500 400 3OO 100 0 0 a I I I I 100 200 300 400 500 Displac~a~at (Ima) 300, b 2 yd,.IZ 0*C ] 20O !f/ a. • 150 a i 0 o ~oo 200 aoo 40o 50o soo Displacement (~m) Fig. 4. Load-displacement behavior of (a)AI203-Si3N 4 and (b) Al:O3-mullite composites. (Fig. 4(a)) and the A1203-mullite (Fig. 4(b)) com￾posites. Extensive inelastic deformation is evident. The step-wise load drops, beyond the peak stress, are characteristic of the behavior of laminar composites with crack-deflecting interfaces [40]. Fig. 5(a) illustrates the "wood"-like fracture path of the AIzO3-Si3N 4 composite. Fig. 5(b) illustrates a typical fracture surface, showing that fiber bundles are bonded together with the powder matrix, and that crack deflection occurs within the matrix. Fig. 5. (a) Fracture path of A1203-Si3N 4 composite in flexural failure. (b) Typical fracture surface of AI203-Si3N 4 composite showing fiber bundles with attached matrix. crack-like voids within the matrix and thus optimizes its strength. The matrix itself can act as a crack￾deflecting phase such that an all-oxide CMC can be fabricated. 6. Concluding remarks Damage-tolerant continuous fiber CMCs can be produced by a powder route that packs particles within a fiber preform by pressure filtration and then strength￾ening the powder matrix by a cyclic precursor infiltra￾tion method. High particle packing densities can be achieved within the fiber preform provided that the particle-to-fiber diameter ratio is small. Filling the interstices with particles first limits the size of the Acknowledgments This research was sponsored by the Defense Advance Research Projects Agency through the University Research Initiative of UCSB under ONR Contract N00014-92-J-1808. Portions of this review that concerned interparticle potentials that control particle packing density and the rheology of the slurry and consolidated body were supported by the Office of Naval Research under N00014-90-J-1441