Effect of Al_2O_3 and Fe_3Al on the phase formation and mechanical properties of β-sialon

摘要

The paper evaluated the mechanical properties of p-sialon composites prepared by hot-pressing sintering at 1600℃ in N_2 atmosphere using α-Si_3N_4, Al_2O_3, Y_2O_3 and Fe_3Al as raw materials. The influence of Al_2O_3 and Fe_3Al content on flexure strength, fracture toughness, hardness, and relative density was investigated. And phase formation and morphology of the composites were characterized by X-ray diffraction and electron microscopy. The experimental results indicate that the raw material Fe_3Al reacts with α-Si_3N_4 to form silicides at elevated temperature, and supplies more liquid phase to assist densification. Besides, the variation of flexure strength, fracture toughness and hardness is mainly consistent, and also in good agreement with the relative density measurements. The values all increase firstly, and then decrease when the Al_2O_3 content increases. Scanning electron microscopy illustrates that the metal particles act to inhibit the crack propagation.