Yttria stabilized zirconia (Y-CSZ) single crystals show plastic deformation at high temperatures byactivating dislocations. The effect of strain rate on the plastic behavior of this crystal was studied. As increasingstrain rate from ε=1.04×10-5sec-1 to 2.08×10-5sec-1 the yield drop was suppressed and resulted in higherYoung's modulus and yield stress. Dislocation structures of the strained crystals were analyzed using atransmission electron microscope to elucidate the plastic behavior of these crystals. In the early stage of plasticdeformation, dislocation dipoles and prismatic dislocation loops were formed in both samples. However,dislocation density was increased by increasing strain rate. Strong sessile dislocations were observed in thesample with higher strain rate, which may cause the higher work hardening.

Yttria stabilized zirconia single crystals show plastic deformation at high temperatures by activating dislocations. The plastic deformation is highly dependent on crystallographic orientation. When the samples were deformed at different orientations, stress-strain curves changed by operating different slip systems. The strength of samples was also highly dependent on crystallographic orientation, i.e., samples without yield drop showed higher strength than that of samples exhibiting yield drop. The slip systems in the sample deformed along<112>,<111> and<001> agreed with the theoretical values of the plastic deformation, following Schmid's Law. Dislocations play a major role in the plastic deformation of this crystal. At the early stages of plastic deformation, all samples exhibited dislocation dipoles and, in the later stages, dislocation interactions occurred by forming nodes, tangles and networks. In this study, three different orientations, [11-2], [111] and [001] were employed to explain the plastic deformation behavior. A microstructural analysis was performed to elucidate the mechanism of the plastic behavior of this crystal.