Boundary structure of Y-ZrO sub 2 grains as derived from high-resolution electron microscopy

The grain boundary structure of an yttria doped tetragonal zirconia polycrystal (Y-ZrO sub 2 or Y-TZP), composed of small-sized grains, was examined by means of electron microscopy and energy dispersive X-ray spectroscopy (EDS). Two kinds of Y-TZP materials, the original sample and the sample decreased to 53% in length that of the original sample by compressive deformation at 1300 deg C, were investigated. The crystallographic structural difference between two samples could not be recognized. Each grain sticks together, and no amorphous phase was observed at the grain boundaries. Grains of Y-TZP usually form boundaries with low index planes such as {111}, {110}, {310} and {311}. It has been revealed that yttria added to zirconia has no measurable effect on the superplastic deformation of this material and the deformation takes place by grain boundary sliding.