Influence of alumina particle size on fracture toughness of (Y,Nb)-TZP/Al2O3 composites

ZrO2/Al2O3 composites were prepared by mixing a tetragonal ZrO2, stabilized with 5.31 mol% Y2O3 and 4.45 mol% Nb2O5, and Al2O3 having different particle size (0.2 μm and 2.8 μm) to investigate the influence of the Al2O3 particle size on flaw tolerance of the composites. The composites exhibited rising R-curve behavior and plateau fracture toughness of 7.9 and 8.8 MPa√m for the additions of 20 vol.% of 0.2 and 2.8 μm Al2O3 particles, respectively. The difference in the fracture resistance was attributed mainly to the grain size of tetragonal phase in the composites, which scaled with the Al2O3 particle diameter, and partially to the dispersion toughening.