ABNORMAL GRAIN-GROWTH IN ALUMINA-ZIRCONIA NANOCOMPOSITES

Abnormal grain growth in the alumina-zirconia system was investigated using a zirconia-20 weight% alumina nanocomposite. This composite was synthesized by the chloride sol-gel synthesis technique using zirconiu m tetrachloride, yttrium chloride and aluminum chloride as precursors. The powders were cold pressed using 40 MPa and sintered at 1773 K or 1873 K for 16 hr. The pellets heat treated at 1773 K showed uniform gr ain coarsening while the specimens heat treated at 1873 K showed signi ficant amounts of abnormal grain growth. This is attributed to the ina bility of the alumina dispersoids to pin the zirconia grains at higher temperatures.