Al2O3-metal composites were prepared by oxidation and reaction of molten Al alloy in two types of commercial Al2O3-SiO2 fibrous insulation board heat treated at 1000 degrees C and 1200 degrees C. The 4-point bending test specimens were heated up to test temperature and then quenched in a water bath of 20 degrees C, Fracture toughness, elastic modulus, Poisson ratio, and thermal expansion coefficient were determined, to obtain the specific fracture energies and the thermal shock resistance parameters. Commercially available, dense, sintered Al2O3 was tested for comparison. The fracture surface of specimens was investigated by scanning electron microscopy. Composites that are more resistant to thermal shock and are shrinkage free could be produced with inexpensive fibers through the;reactive oxidation and infiltration process.