Effects of Iron and Silicon Additions on the Microstructures and Mechanical Properties of Aluminium Bronze

The effects of Fe and Si additions on the microstructures and mechanical properties of aluminum bronze have been investigated. In a bar-type specimen cast in a die mold, the addition of Fe promoted the dendritic solidification of the α phase. The hardness values increased slightly in the Fe-added specimen with heat treatment, while these values was increased significantly in the specimens with Si or with combined additions of Fe and Si. When a centrifugal casting bush with combined addition of Fe and Si was heat treated, the FeSi compound within the matrix was finely dispersed, and was observed to be the origin of cup-cone type conical dimple failure in the tensile fracture surface. The mechanical properties of the heat treated centrifugal casting bushes, whose nom-inal alloy compositions were (Cu-7.0Al-0.8Fe-3.0Si)wt%, exhibited tensile strength of 703-781 N/mm 2 , elongation of 6.6-11.7% and hardness of Hv 222.6-249.2. These high values of strength and elongation were attributed to the strengthening of the matrix due to the combined addition of Fe and Si, and to precipitation of fine the FeSi compound.