Cavitation Failure in a Superplastic Alumina with Zirconia-Particle Dispersion

摘要

High temperature tensile failure in a fine-grainedalumina with zirconia particle dispersion is found to relateclosely to the separation distance among micrometer-sizedcavities growing from preexistent defects and from newlyformed ones during deformation. As the separation distance isdecreased to a certain level with an increase in both density andsize of such cavities, extensive cavity interlinkage starts to causemicrocracking, and the microcracking leads to the occurrence ofmacroscopic cracks propagating in a direction perpendicular tothe tensile axis toward the final failure. The dependence of theonset strain of microcracking on temperature and grain size isalso found to relate closely to the dependence of cavityformation and growth rates on these factors.