Three Al2O3/SiC composite ceramics were prepared, which included 1, 3 or 5 wt.% Y2O3, and their high-temperature bending strengths and in-situ crack-healing behaviors examined. A surface elliptical-crack of about 100 01 in diameter was introduced in the specimens using a Vickers hardness indenter. From in-situ observations, the Al2O3/SiC composite ceramic with 3 wt.% Y2O3 showed superior crack-healing ability than the 1 and 5 wt.% Y2O3 ceramics. The as-cracked specimen with 3 wt.% Y2O3 showed strength recovery on heating for one hour at 1473 K in air, which may have been due to the lower crack-healing temperature on the addition of 3 wt.% Y2O3. The heat-resistance limit temperatures of the crack-healed Al2O3/SiC composite ceramics were 1073, 1373 and 873 K for 1, 3 and 5 wt.% Y2O3, respectively.

Keywords: Crack-healing; Al2O3/SiC Composites; Strength recovery; Additive powder Y2O3; In-situ crack-healing behavior; elevating temperature