Abstract: Improved alumina-zirconia composite sintered materials with sufficient high mechanical strength and thermal shock resistance as well as excellent hardwearing resistance are made by mixing, heating and melting zirconia and alumina, then the produced melt was quenched, and the resulting solid was ground and milled while adding thereto at least one compound of ceria and/or titania, to an average grain size of from about 0.5 to about 1.5 .mu.m, and subjected the resulting powder to molding and sintering at a temperature of from 1450.degree. to about 1600.degree. C., said zirconia, ceria and titania being employed in the amount of about 10-20%, about 3-7%, and about 15-25% by weight, respectively, plus the balance of alumina. Said sintered materials are useful for employment in structural materials, refractorial materials, erosion resistance materials, cutting tool materials, grinding and polishing materials, etc.

Abstract: Alumina-zirconia composite sintered materials having sufficient high-temperature strength and thermal shock resistance as well as excellent mechanical strength are made by mixing Bayer alumina and/or bauxite as an alumina and baddeleyite and/or zircon sand as a zirconia material in amounts of 50 to 95% by weight of alumina, the balance being zirconia, respectively, subjecting the mixture to heating, melting and quenching, grinding the resulting solid to an average grain size of 10 .mu.m or smaller, and subjecting the resulting powder to molding and sintering.