Superplastic Extrusion of Nano-structured Si2N20-Sialon

摘要

Nano-structured SiiN:0-Sialon composites were prepared by liquid phase sintering method with the amorphous nano-sized Si_3N_4 and nano-sized A1N powders. Nano-sized Al_2O_3 and Y_2O_3 powders synthesized by polyacrylamide gel method were introduced as additives. SEM examination shows the grain size of sintered body to be less than 80nm. Superplastic extrusion can be undertaken at 1550deg C with a high velocity of 0.5mm/min and a big extrusion ratio of 3.57. There are a lot ring-shaped structure just like "annual ring" of trees in radial fracture and clear flow trace in axial fracture, all which is very similar to deformed metal materials and approve good superplastic deformation capability of Si_2N_2O-Sialon composites.