ELECTRON-MICROSCOPIC OBSERVATION OF RAPIDLY COOLED ZRO2-3 MOL-PERCENT SM2O3 FROM THE MELT

Electron microscopic observation was made on ZrO2-3 mol % Sm2O3 specimens prepared from the melt using two different cooling rates, namely rapid quenching using a hammer-anvil apparatus and free cooling-on a water-cooled copper hearth. The observed microscopic features, such as fully tetragonal grains with parallel twins or herringbone structure, anti-phase boundary contrast in a dark-field image, tweed structure, etc., were found to be quite similar to those observed in similarly prepared ZrO2-3 mol % Y2O3 specimens. It was specifically noted that the tweed structure, which requires atomic diffusion, was not suppressed by the rapid quenching, indicating a very fast growth rate. Trace analysis was also conducted on the tweed structure observed in freely cooled specimens.