Recovery of Crack-Tip Transformation Zones in Zirconia After High-Temperature Annealing


  • D. R. Clarke—contributing editor

  • Present address: 17 Rue de Bizy, 27200 Vernon, France.

  • Supported at Rockwell by the U.S. Air Force Office of Scientific Research under Contract No. F49620–89-C-0031 and at CWRU by the National Science Foundation under Grant No. DMR90–19383.


Annealing at temperatures between 500° and 1000°C reverses the stress-induced tetragonal-to-monoclinic phase transformation in precipitates within crack-tip zones in MgO-partially-stabilized ZrO2 (Mg-PSZ). The stability of such reverse-transformed tetragonal precipitates during subsequent room-temperature aging has been examined using Raman spectroscopy, surface displacement measurements, and crack-opening measurements. Partial spontaneous retransformation of material within the original zone from tetragonal-to-monoclinic symmetry occurred over periods of several months.