Microstructure of Y2O3 doped Al2O3–ZrO2 eutectics grown by the laser floating zone method

Al2O3–ZrO2 eutectics containing 9 mol% Y2O3 (with respect to zirconia) were produced by directional solidification using the laser floating zone (LFZ) method. The eutectic microstructures were investigated as a function of the growth variables. Using a solidification-axis thermal gradient of 600 °C/mm a homogeneous, colony-free, interpenetrating lamellar microstructure was obtained for growth rates less than 50 mm/h. Higher growth rates produce cellular structures. Colonies grew with the [0001] alumina and the [110] zirconia axis parallel to the growth direction. The uniform lamellar microstructure obtained at low growth rates is stable during thermal treatment at 1500 °C.