Scanning acoustic microscopy of indentation damage in Y2O3-stabilized tetragonal zirconia

Scanning acoustic microscopy (SAM) has been applied to investigate Vickers indentation-induced damage in Y2O3-stabilized tetragonal zirconia polycrystal (Y-TZP). The leaky Rayleigh wave velocity, vR, around the indentation is determined from the V(z) curve technique. A considerable anisotropy in vR is observed within the elastic/plastic zone which results from the indentation-induced residential stresses. In contrast, an isotropic reduction in vR is found within the indentation core, implying the presence of microcracks. Furthermore, the SAM observations reveal that the elastic/plastic boundary is axisymmetric with respect to the loading axis and that its radius is 1.2 times as large as the indentation half-diagonal. These results are discussed in terms of an analysis based on the pressurized-spherical-cavity model