Effect of Ta2O5, Nb2O5, and HfO2 Alloying on the Transformability of Y2O3-Stabilized Tetragonal ZrO2


  • Dae-Joon Kim

    1. Department of Materials Science and Engineering, The University of Michigan, Ann Arbor, Michigan 48109
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      Member, the American Ceramic Society.

    • Now at Oak Ridge National Laboratory, Oak Ridge, TN.

  • Presented in part at the 89th Annual Meeting of the American Ceramic Society, Pittsburgh, PA, April 28, 1987 (Basic Science Division, Paper No. 126-B-87).


The addition of Ta2O5, Nb2O5, and HfO2 enhanced the transformability of Y2O3-stabilized tetragonal ZrO2 polycrystal (Y-TZP), which was indicated by an increase in phase transformation temperatures and fracture toughness of Y-TZP. Comparison of the alloying effects of these oxides on the transformability and crystal structure of Y-TZP suggested that an alloying oxide which increases the c/a axial ratio (tetragonality) of TZP also increases the transformability. Empirical equations to predict the tetragonality are proposed. Calculated tetragonalities showed good agreement with measured values in the systems ZrO2-Y2O3-Ta2O5, -Nb2O5, and -HfO2.