Compression Creep Characteristics of 8-mol%-Yttria-Stabilized Cubic-Zirconia

Constant stress compression creep tests were conducted on 8-mol%-yttria-stabilized cubic-zirconia (8YCZ) over stress (?), temperature, and grain-size ranges from ～20 to 300 MPa, 1673 to 1773 K, and 4 to 8 μm, respectively. Creep data were analyzed in terms of the relationship epsivdot] ∝? ⁿ , where epsivdot] is the strain rate and n the stress exponent. Although the experimental data yielded a stress exponent of n & 2, analysis of the results with compensation of significant concurrent grain growth revealed that the true stress exponent was n ～ 1. The results were consistent with deformation by the Coble creep mechanism. Experiments at stresses greater than ～100 MPa revealed a transition from grain-size-dependent Coble diffusion creep to grain-size-independent intragranular dislocation creep.