Localized superplastic deformation of nanocrystalline 3Y-TZP ceramics under cyclic tensile fatigue at ambient temperature

Cyclic tensile fatigue tests were performed on 100 +/- 20 nm, and 0.35 mu m 3Y-TZP ceramic specimens at room temperature. Localized superplastic defor mation of the grains in the 100 nm materia I at and near to the fracture su rfaces was fi rst identified by AFM imaging. Slip band-like microfeatures, similar to those reported on some metals, were also unexpectedly seen to de velop on the side faces. In contrast, the 0.35 mu m specimens retained thei r equiaxed grain morphology after undergoing similar testing conditions. Th e micromechanisms underlining these phenomena were discussed. Grain boundar y diffusion of the respective atomic species is reasoned to be the major go verning process in operation. And the contribution of a dislocation slip me chanism is considered to play a possible or parallel role. (C) 1998 Chapman & Hall.