Scanning Acoustic Microscopy of Indentation Damage in Y 2 O 3 ‐Stabilized Tetragonal Zirconia

Scanning acoustic microscopy (SAM) has been applied to investigate Vickers indentation‐induced damage in Y 2 O 3 ‐stabilized tetragonal zirconia polycrystal (Y‐TZP). The leaky Rayleigh wave velocity, v R , around the indentation is determined from the V( Z ) curve technique. A considerable anisotropy in v R is observed within the elastic/plastic zone which results from the indentation‐induced residual stresses. In contreast, an isotropic reduction in v R is found within the indentation core, implying the presence of microcracks. Furthermore, the SAM observations reveal that the elasic/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‐sphericalcavity model.