Effect of SiO_2 amount on microstructures and tensile properties of alumina short fiber-reinforced composites by low-pressure infiltration method

摘要

The tensile properties of two types of alumina (Al_2O_3 and Al_2O_3-SiO_2) and short fiber-reinforced A366 alloy composite created by low-pressure infiltration have been studied. The applied pressure and temperature of molten alloy are 0.4 MPa and 1073 K, respectively. The composite containing 10 vol.% of fiber preform was sectioned and the microstructure was observed by scanning electron microscopy and energy dispersive X-ray spectroscopy. Tensile properties of Al_2O_3 fiberreinforced A366 alloy composites were investigated, in conjunction with investigation of effects of amounts of SiO_2 sol added as binder to fabricated preform and effects of changed chemical composition of Al_2O_3 fiber. The composite with SiO_2 sol of 8 mass% has higher relative density in comparison with composite with SiO_2 sol of 2 mass%. SiO_2 sol raised the relative density of composite by the reaction with aluminum. In addition, the ultimate tensile strength of composite which has Al_2O_3 fiber-reinforced A366 alloy composite containing SiO_2 sol of 8 mass% was approximately 20% higher than that of Al_2O_3-SiO_2 fiber-reinforced A366 alloy composite containing SiO_2 sol of 8 mass%.