In the context of this work, chemically introduced zirconia (AP ng -Zm) tends to remain in the monoclinic phase (FIGURE ), while in the literature, for isotropic zirconia toughened alumina prepared from spherical alumina powders, chemically introduced zirconia can remain in the tetragonal phase at room temperature after sintering, even without stabilizer, in particular because the zirconia particles can be kept below the critical size for stabilization . Using XRD (FIGURE ), the AP-Zm sample shows no peak related to the tetragonal phase, while the AP ng -Zm sample shows only a small tetragonal peak. On the other hand, the Zt samples clearly show much more developed tetragonal peaks: AP-Zt shows a tetragonal peak that is much larger than the monoclinic peak and the AP ng -Zt and AP-Zt-HP samples show only tetragonal peaks and no monoclinic peaks. It appears that a stabilizer, here Y2O3, is required to keep the zirconia in the tetragonal phase at room temperature. It also shows that the presence of glass phase and alumina nanoparticles results in less monoclinic phase than the homologous sample without these additives. The same trend is observed for the sample sintered at 80 MPa instead of 40 MPa. It therefore appears that when sintering is more advanced it can help to stabilize the zirconia in the tetragonal phase. This difference with literature may possibly be related to the size and shape of the alumina grains, which are relatively large but also elongated (platelets) in the present work. This geometry of alumina platelets leads proportionally to less interface between grains on which zirconia can disperse after sintering, which logically leads to larger zirconia clusters at the triple grain boundaries.