Processing and mechanical properties of Al2O3/Ni3Al composites with interpenetrating network microstructure

Composites with microstructures of interpenetrating networks were manufactu red by gas pressure infiltration of Ni3Al into porous preforms of aluminum oxide. Composites with Ni-3,Al contents of between 15% and 30% by volume we re made and evaluated mechanically at temperatures between room temperature and 1000 degreesC. The fracture strength, the fracture toughness, Young's modulus, and the thermal expansion coefficient were measured for each compo site and test condition and were correlated with the microstructures of the composites. Composites with low Ni3Al contents had strengths below 400 Wa, presumably due to microcracking along the interface between the Ni3Al and the Al2O3. The composite with the highest content of Ni3Al, 30 vol%, had a mean fracture strength of 675 +/- 16 MPa, a Weibull modulus of 23.9, and a room-temperature toughness of 9.2 +/- 0.5 MPa(.)m(1/2).