High temperature mechanical behavior of polycrystalline alumina from mixed nanometer and micrometer powders

Sintered aluminum oxide materials were formed using commercial methods from mechanically mixed powders of nano- and micrometer alumina. The powders were consolidated at 1500 and 1600°C with 3.2 and 7.2 ksi applied stress in argon. The conventional micrometer sized powders failed to consolidate. While 100% nanometer-sized alumina and its mixture with the micrometer powders achieved >99% density. Preliminary high temperature creep behavior indicates no super-plastic strains. However high strains (>0.65%) were generated in the nanometer powder, due to cracks and linked voids initiated by cavitation.