High-Strain-Rate Superplasticity in 3mol-Y{sub}2O{sub}3-Stabilized Tetragonal ZrO{sub}2 Dispersed with 30vol MgAl{sub}2O{sub}4 Spinel

摘要

High-strain-rate superplasticity (HSRS) is attained in tetragonal ZrO{sub}2 dispersed with 30vol% MgAl{sub}2O{sub}4. The tensile ductility exceeds 250% at 1823 K and even at a strain rate of ≈0.7 s{sup}(-1). HSRS can be attained by the enhanced accommodation process of stress concentrations at multiple grain junctions exerted by grain boundary sliding. The present results indicate that the enhanced accommodation process occurs by the accelerated cation diffusion by the dissolution of Al and Mg ions from the MgAl{sub}2O{sub}4 phase into the ZrO{sub}2 matrix and by the accelerated stress relaxation through the plastic deformation of the MgAl{sub}2O{sub}4 grains.