Effect of the particulate size on mechanical properties of alumina–zirconia composites

The effect of particulate size of alumina addition on mechanical properties of zirconia containing 3mol% Y2O3 (3Y-TZP) was investigated. Composites containing 15vol.% Al2O3 either as broken or as unbroken platelets ranging from 1 to 11μm were fabricated by hot isostatic pressing. Additions of Al2O3 to YSZ resulted in enhanced fracture toughness with a trend to lower values of KIc with increasing platelet size. Observations of cracks produced by Vickers indentation and in-situ crack propagation studies lead to assume that the addition of Al2O3 enlarged the process zone size. The formation of elastic bridges was observed and is believed to be a contribution to the R-curve properties. ► Addition of Al2O3 broken platelets to YSZ results in increasing fracture toughness. ► An enhanced process zone size was formed. ► Crack deflection and elastic bridges were detected. ► Platelet size can be modified to optimize strength and toughness.