Abstract
Effect of 5-30 mol% alumina addition on the tetragonal(T)-to-monoclinic(M) (Martensitic) phase transformation in zirconia-2 and 3 mol% yttria ceramics was investigated. Powders were compressed at 100MPa, and sintered at 1923 K for 54ks. The sintered specimens were aged at 573 K. Mean grain sizes were increased by alumina addition. The amount of expansion and contraction during heating and cooling accompanied with transformation were increased by the addition of alumina. The amount of transformation increased with aging time as a sigmoidal curve and the curve sifted to shorter aging time by the addition of alumina. In higher alumina, long time was required for saturation in transformation, although the transformation started occurred earlier. Aged 2Y specimen has a texture of (111)M, while in the alumina added specimen such tendency became to be weak. AFM observations show that, after aging in 3Y-5A specimen, the transformation accompanied by aging time developed in the various directions with many branch compared with those in 3Y.
