Superplasticity in Multi-Phase Alumina-Based Composites

摘要

High-temperature superplasticity in Al_2O_3-20vol%spinel (MgAl_2O_4) containing 5, 10, 20 and 30vol% of ZrO_2 was examined at temperatures between 1400 and 1500°C. The dispersion of ZrO_2 significantly reduces the flow stress during tensile tests in comparison with pure Al_2O_3-20vol%spinel. Flow stress around 10 MPa are obtained at 1450°C for 20vol% and 30vol%ZrO_2 materials and at a strain rate of 1.3×10~(-4)s~(-1). The flow stress reduction is explained by a decrease in grain growth due to ZrO_2 dispersion and by a high increase in diffusion through D_o parameter.