An investigation of fabrication technology on eutectic composites consisting of Al2O3 phases and YAG (Y3Al5O12) phases was carried out by applying the unidirectional solidification process. Unidirectionally solidified eutectic composites consisting of [110] sapphire phases and [420] single crystal YAG phases could be fabricated successfully by lowering a Mo crucible at a speed of 5 mm h(-1) under a pressure of 10(-5) mmHg of argon. These eutectic composites have excellent high-temperature properties up to 1973 K. For example, the flexural strength is 360-500 MPa independent of testing temperature from room temperature to 1973 K. Oxidation resistance at 1973 K in an air atmosphere is superior to SiC and Si3N4 and the microstructure of these eutectic composites is stable even after heat treatment at 1773 K for 50 h in an air atmosphere.