Crack‐Tip Transformation Zones in Toughened Zirconia

Transformation zones surrounding cracks in several toughened magnesia‐partially‐stabilized zirconia ceramics are characterized by optical interference measurements of surface uplift and by Raman microprobe spectroscopy. The measurements demonstrate that the volume fraction of transformation is nonuniform within the zone and that the extent of the frontal zone is approximately the same as that of the wake. Results are used to evaluate the crack‐tip shielding stress intensity factor and to compare with the measured fracture toughness.