MORPHOLOGY OF TETRAGONAL PRECIPITATES IN Y2O3-STABILIZED ZRO2 CRYSTALS

Yttria-stabilized zirconia single crystals are annealed to contain precipitates of the tetragonal phase of medium size. The morphology of these precipitates is investigated by high voltage electron microscopy. The particles are built of platelets of only two t variants of approximately equal thickness. They extend in directions differing from the usually discussed low-index directions. These growth directions result from a shift of the individual platelets parallel to the twin plane. The shift and the corresponding facetting of the precipitate/matrix interfaces may play a role in the growth mechanism.