EFFECT OF ANNEALING ENVIRONMENT ON THE CRACK HEALING AND MECHANICAL-BEHAVIOR OF SILICON CARBIDE-REINFORCED ALUMINA NANOCOMPOSITES

The crack healing and strength behavior of an alumina-silicon carbide (Al2O3-SiC) nanocomposite (Al2O3 + 5 vol% 0.2 mu m SIC particles) has been studied, as a function of the crack size and the annealing enviro nment. Results show that annealing treatments can significantly increa se the indentation strength. The annealing atmosphere has a profound i nfluence on the extent of crack healing and the degree of strength rec overy. Annealing in argon results in a strength increase of 50%, where as annealing in air yields a three-fold improvement in the indentation strength Scanning electron microscopic observation has shown that hea ling of indentation cracks occurs in both environments, with the great er degree of healing occurring during annealing in air. Implications o f the findings to the strengthening mechanism in Al2O3 (SiC) nanocompo sites will be discussed.