MORPHOLOGIES OF MONOCLINIC PHASE IN ZRO2 (2 MOL-PERCENT Y2O3) REVEALED BY TEM IN-SITU CONTINUOUS OBSERVATIONS

TEM in situ continuous observations were made of the tetragonal (t) to monoclinic (m) transformation of ZrO2(2Y) in pure ZrO2(2Y) and Al2O325 vol % ZrO2(2Y) ceramics. It was found that there were two morpholog ies of the m-phase after transformation of the t-grains: N-shaped plat e clusters and parallel laths. The parallel lath morphology is conside red to be the result of lateral growth of the m-plates. The lower the local Y2O3 content, the less will be the stability of the t-phase, and then the larger will be the possibility of the lateral growth of the m-plates. This, in turn, facilitates the transition from N-shaped to p arallel lath morphology and increases the completeness of the transfor mation.