Microstructure and superplastic behavior of TiO2-doped Al2O3–ZrO2 (3Y) composite ceramics

Compression deformation behavior and mechanism of as-sintered Al2O3–ZrO2 (3Y) composite ceramics doped with four different amounts of TiO2 (0, 1, 4, and 8 wt.%, designated as 0T, 1T, 4T, and 8T) were systematically investigated in this work. It was found out that the strain rate significantly increased by doping TiO2 addition. The stress-jump deformation data showed that the strain rate of 8T was about two orders of magnitude higher than that of the undoped ceramic under the same flow stress. Then, the microstructures were examined. After deformation, texture was developed but its intensity decreases with increasing TiO2 concentration. Moreover, liquid phases (about 50–100 nm) were observed along the edge facets and at the junction pockets in deformed 4T and 8T specimens. Based on the microstructural features and deformation behavior, it is suggested that for 0T and 1T, the deformation mechanism was texture-controlled grain boundary sliding accompanied by diffusion; for 4T and 8T, it was grain boundary sliding accompanied by the liquid phases.