Compression creep characteristics of 8-mol%-yttria-stabilized cubic-zirconia

Constant stress compression creep tests were conducted on 8-mol%-yttria-sta bilized cubic-zirconia (8YCZ) over stress (sigma), temperature, and grain-s ize ranges from similar to 20 to 300 MPa, 1673 to 1773 K, and 4 to 8 mum, r espectively. Creep data were analyzed in terms of the relationship (epsilon ) overdot proportional to sigma (n), where (epsilon) overdot is the strain rate and n the stress exponent. Although the experimental data yielded a st ress exponent of n approximate to 2, analysis of the results with compensat ion of significant concurrent grain growth revealed that the true stress ex ponent was n approximate to 1. The results were consistent with deformation by the Coble creep mechanism. Experiments at stresses greater than similar to 100 MPa revealed a transition from grain-size-dependent Coble diffusion creep to grain-size-independent intragranular dislocation creep.