Effect of adding Y2O3 on structural and mechanical properties of Al2O3–ZrO2 ceramics

The effects of adding 1–8 wt% Y2O3 on phase formation and fracture toughness of Al2O3–xZrO2–Y2O3(AZY) ceramics were studied. Phase formations of the samples were characterized by the X-ray diffraction (XRD) technique. It was found that the major phase was rhombohedral-Al2O3, while the minor phase consisted of the monoclinic-ZrO2, tetragonal-ZrO2 and monoclinic-Y2O3. It was found that Y2O3 contents did not clearly influence grain shape of AZY ceramics. The results obtained from the microhardness test could be used to evaluate the fracture toughness. It was found that the smaller grains had high fracture toughness. The maximum fracture toughness of 4.827 MPa m1/2 was obtained from 4 wt% Y2O3. Refinement of lattice parameters using Rietveld analysis revealed the quantitative phases of AZY ceramics. This shows that under adding Y2O3 conditions the proportion of tetragonal-ZrO2 phase plays an important role for the mechanical properties of AZY ceramics.