Transmission electron microscopy was used to examine deformed microstructures in high-purity tetragonal polycrystals which contained 3mol%Y2O3. The transmission electron microscopic observations revealed that piled-up and tangled dislocations developed within grains at high stresses. Such sub-structures did not appear at lower stresses, apart from a small number of isolated dislocations. The stress-dependent deformed microstructures suggested that the dislocation sub-structures which were observed at high stresses were not due to any experimental artefacts. By applying an Eshelby model to the observed pile-up dislocations, it could be estimated that a stress concentration of the order of 14 to 25 was generated around multiple-grain junctions during deformation.

Deformed Substructures in Fine-Grained Tetragonal Zirconia. K.Morita, K.Hiraga: Philosophical Magazine Letters, 2001, 81[5], 311-9