Processing-Dependent Microstructural Factors Affecting Cavitation Damage and Tensile Ductility in a Superplastic Alumina Dispersed with Zirconia

摘要

Superplastic tensile ductility in Al_2O_3-10 vol% ZrO_2 (3 mol% Y_2O_3) exhibits processing dependence when the grain size is reduced to 0.45μm 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 ZrO_2 particles. The rate of damage accumulation is shown to depend mainly on the former and additionally on the latter.