EFFECTS OF OXIDATION OF CR3C2 PARTICULATE-REINFORCED ALUMINA COMPOSITES ON MICROSTRUCTURE AND MECHANICAL-PROPERTIES

Al2O3 can be strengthened and toughened by incorporating Cr3C2 particles through hot-pressing. For instance, an Al2O3-10 vol % Cr3C2 composite exhibits fracture strength and toughness of 600 MPa and 5.5 Mpa m0.5, respectively. An annealing treatment in air from 1000-1200-degrees-C may further substantially strengthen the same composite to give sigma(f) = 800 MPa and K(IC) = 9.5 MPa m0.5. Possible oxidation reactions and toughening mechanisms are discussed in terms of oxygen diffusion, the formation of micropores beneath the exposed surface, as well as the fracture mode.