Development of novel microstructures in zirconia-toughened alumina using rapid solidification and shock compaction

Abstract

A rapidly solidified alumina-zirconia eutectic material containing nanocrystalline t-ZrO2 has been synthesized. When heated, the microstructure contained a mixture of t-ZrO2 and m-ZrO2, each of which can facilitate toughening of the composite. Dynamic shock compaction was used to accelerate densification of the material, producing crack-free specimens with high green densities. After sintering to densities measuring ∼95% of theoretical, the shock-compacted specimens fabricated with unstabilized alumina-zirconia were extensively microcracked due to an overabundance of the m-ZrO2 phase. Experiments employing Y2O3 as a chemical stabilizer have shown that the extent of the phase transformation can be controlled, and the microstructure that developed in the stabilized material contained an acceptable level of the microcrack generating m-ZrO2 phase.