Properties of α-sialon ceramics

α-Sialon ceramics in the system of Si3N4-AlN-Y2O3 were fabricated by pressureless sintering. The solid solubility range, microstructure and mechanical properties such as fracture strength, hardness, fracture toughness were measured. In the Y-α-Sialon ceramics, there existed a composition range containing a small amount of additive named “partially stabilized α-Sialon” in which α-Sialon and β-Si3N4 coexist. α-Sialon ceramics with excellent mechanical properties can be obtained in this composition range by controlling composition and microtexture.