Analysis On Microstructure Of Superplastic Deformation Of Al₂O₃-ZrO₂ Nanocomposite Ceramics

Alumina-zirconia series ceramics are the more sophisticated zirconia dispersion ceramics, and be also the emphasis of composite research. Tetragonal zirconia particle dispersing on alumina matrix can increase obviously toughness and strength of alumina ceramics through phase change toughening. Fine-grained alumina-20%zirconia without impurity can be deformed with high strain in compression tests at 1400-1600℃. Alumina-zirconia nanocomposite was studied under the route of"powders synthesis-composite sintering-superplastic forming-microstructure anylisis". The microstructures and texture of Alumina-zirconia nanocomposite have been systematically investigated.The homogeneity and mixed powders of Nano Alumina-zirconia were maken by planet globe mill. Nanocomposite ceramics block with intergranular and intragranular nano-particles which were made by using hot-press sintering. Nanocomposite ceramics block was compressed well to 82% at 1550℃. XRD patterns of Alumina-zirconia nanocomposite before and after compression which indicate diffraction intensity changes obviously. Determination through F parametric characterizing orientation degree of texture of materials, alumina crystal grains had preferred oritentation in {110},{113} and {300} crystal plane, and oritentation of zirconia crystal grains were not obvious. By pole figure, texture of alumina of perpendicular plane in {110} and {300} crystal plane was apparent and that in {113} crystal plane was weaker than former, and texture of alumina crystal grains of compression plane was diffuse. Microstructure was analysed by TEM and SEM, SEM analysis demonstrate that Alumina crystal grains aligned directionally and texture appeared, and zirconia crystal grains aligned randomly after superplastic compressive deformation. Microstructure was compact, crystal grains grew and fibrous tissue appeared after deformation. TEM analysis demonstrate that there were dislocation behavior and dynamic recovery and dynamic recrystallization during superplastic compressive deformation.