Processing-dependent microstructural factors affecting cavitation damage and tensile ductility in a superplastic alumina dispersed with zirconia

Superplastic tensile ductility in Al₂O₃-10 vol% ZrO₂ (3 mol% Y₂O₃) exhibits processing dependence when the grain size is reduced to 0.45 μm for a given relative density of ∼99.5%. The reduced grain size leads to largely enhanced ductility in a material prepared by colloidal processing, but does not in a material prepared by conventional dry processing. This result is explained from cavity-damage accumulation sensitive to a rather small variation in a few processing-dependent factors: the numerical densities of residual defects and ZrO₂ particles. The rate of damage accumulation is shown to depend mainly on the former and additionally on the latter.