Superplastic Extrusion of Al2O3-YTZ Nanocomposite and Its Deformation Mechanism
Using Al2O3-YTZ(3mol% yttria stabilized tetragonal zirconia) nanocomposite, superplastic extrusion under different conditions was adopted to form blade models. The results demonstrate that desired microstructure is achieved through the addition of 20mol% YTZ which acts as a second-phase pinning agent. At temperature range of 1650°C to 1700°C the material shows good deformability. At this elevated temperature the maximum extrusion pressure is lower than 25MPa, and the maximum punch speed is about 0.35mm·min-1. In superplastic extrusion the dominating deformation mechanism is grain sliding and rotation, the accommodating mechanism is intergranular zirconia coordinated deformation. Meanwhile static and dynamic grain growth also plays an important role in deformation.
Z.Y. Zhong, H. Saka, T.H. Kim, E.A. Holm, Y.F. Han and X.S. Xie
G. Q. Chen and K. F. Zhang, "Superplastic Extrusion of Al2O3-YTZ Nanocomposite and Its Deformation Mechanism", Materials Science Forum, Vols. 475-479, pp. 2973-2976, 2005