The nature and degree of completeness of phase transformations that occur at 1100 – 1750°C in ZrO2 – Nd2O3 (Y2O3) – Al2O3 (Cr2O3) compositions rich with ZrO2 are studied. It is shown that the zirconium-yttrium cubic solid solution has a maximum resistance to the action of Al2O3 and Cr2O3. The sinterability and other properties of parts from ZrO2 can be controlled within a quite wide range by adding Al2O3, Cr2O3, and NdCrO3 to ZrO2 stabilized by Nd2O3.