Tetragonal-to-monoclinic phase transformation in zirconia-yttria ceramics with and without alumina addition

It is well known that zirconia ceramics containing yttria and alumina have remarkable advantages in mechanical properties and these advantages are deeply related to tetragonal-to-monoclinic phase transformation. This study looked into the effect of alumina addition on the phase transformation in zirconia ceramics containing 0-3mol% yttria by DSC, Dilatometry and XRD. Alumina addition induces larger grain size in the tetragonal phase, lower saturation value of the isothermal phase transformation and different growth mode of the monoclinic laths. These results will be related to the change from an anisotropic to an isotropic behavior of monoclinic phase with the addition of alumina, resulted in improvement of mechanical properties.