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

Abstract

Constant stress compression creep tests were conducted on 8-mol%-yttria-stabilized cubic-zirconia (8YCZ) over stress (ς), 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] ∝ςⁿ, 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.