High-Temperature Creep of Yttria-Stabilized Zirconia Single Crystals

Creep of 9.4-mol%-Y₂O₃-stabilized cubic ZrO₂ has been studied between 1300° and 1550°C. Conventional power-law creep (stress exponent n ～ 4.5) is found at the higher temperatures, with an activation energy (～6 eV) corresponding to cation diffusion. Transition to a different creep mechanism occurs at the lower temperatures, as indicated by higher values of the stress exponent ( n ～ 7) and an activation energy (～7.5 eV) higher than that for cation self-diffusion. The lower-temperature behavior is caused by a competition between cross-slip-controlled and recovery-controlled creep. Consideration of all the creep and diffusion data now available suggests that the rate-controlling high-temperature mass transport in Y₂O₃-stabilized ZrO₂ can be described by D = 10^?3 exp(-5.0 eV/ kT ) m²·s^?1.