High‐Temperature Creep of Yttria‐Stabilized Zirconia Single Crystals

Creep of 9.4‐mol%‐Y 2 O 3 ‐stabilized cubic ZrO 2 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 Y 2 O 3 ‐stabilized ZrO 2 can be described by D = 10 −3 exp(‐5.0 eV/ kT ) m 2 ·s −1 .