Al2O3 reinforced by SiC whiskers (Al2O3/SiC‐W) was hot‐pressed to investigate the crack‐healing behavior. Semielliptical surface cracks of 100 μm in surface length were introduced using a Vickers indenter. The specimens containing precracks were crack‐healed at temperatures between 1000° and 1300°C for 1 h in air, and their strengths were measured by three‐point bending tests at room temperature and elevated temperatures between 400° and 1300°C. The results show that Al2O3/SiC‐W possesses considerable crack‐healing ability. The surface cracks with length of 2 c= 100 μm could be healed by crack‐healing at 1200° or 1300°C for 1 h in air. Fracture toughness of the material was also determined. As expected, the SiC whiskers made their Al2O3 tougher.

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Crack-healing behavior of silicon carbide ceramics sintered with AlN and Sc 2 O 3 has been studied as a function of heat-treatment temperature and applied stress. Results showed that heat treatment in air could significantly increase the indentation strength whether a stress is applied or not. After heat treatment with no applied stress at 13001C for 1 h in air, the indentation strength of the specimen with an indentation crack of B100 lm (%2c) recovered its strength fully at room temperature. In addition, a simple heat treatment at 12001C for 5 h under an applied stress of 200 MPa in air resulted in a complete recovery of the unindented strength at the healing temperature. However, higher applied stress led to fracture of the specimens during heat treatment. The static fatigue limit of the specimens crack healed at 12001C for 5 h under 200 MPa was B450 MPa at the healing temperature. The ratio of the static fatigue limit of the crackhealed specimen to the unindented strength wasB80%. J ournal