Effect on crack healing behavior of A1₂O₃/SiC nanocomposites under different annealing temperature

A1₂O₃/SiC nanocomposites with different relative density was used to investigate the crack healing behavior in annealing. Vicker's indentation method was used to induce the controlled cracks. The changing of four points bending strength of the sample with indentation was used to evaluate the healing effects indirectly. It is found that the healing effect increase strongly along with the increasing of annealing temperature above 850°C-After annealed at about 1150°C for one hour, the bending strength of all the different relative density sample with indentation crack almost recover to the original strength without crack. The crack healing mechanism is attributed to the relaxation of residual stress and the oxidation of SiC particle at the crack surface. However, the excess oxidation will reduce the healing effect.