Effect of Zinc Content on the Structure and Mechanical Properties of Silicon Bronze

Abstract

This research investigated the effect of zinc content on the structure and mechanical properties of silicon bronze (Cu-3%wt.Si). The dopant was added in concentrations of 0.1, 0.3, 0.5, 0.8, 1 and 1.5wt%. The samples were developed using permanent die casting technique and machined to the required dimensions for the structural analysis and mechanical tests. Mechanical properties such as percentage elongation, ultimate tensile strength and Brinell hardness of the developed alloys were investigated using a 100KN JPL tensile strength tester (Model: 130812) and portable dynamic hardness testing machine (Model: DHT-6) respectively. The structural analysis was conducted using an optical metallurgical microscope (Model: L2003A) and scanning electron microscopy (SEM). Results of the structural analysis revealed that the control specimen consisted of dendrite of primary silicon and coarse intermetallic phase (Cu3Si). The samples doped with zinc consisted of refined and modified dendritic primary silicon and intermetallic compound respectively. Mechanical tests results indicated that addition of zinc to silicon bronze improved the percentage elongation, ultimate tensile strength and hardness of the alloy significantly. The percentage elongation increased with increase in zinc content up to 1wt%. Further increase in zinc content resulted to decrease in percentage elongation with corresponding increase in hardness. It was noted that the ultimate tensile strength increased with increase in zinc content. This trend in mechanical properties was concluded to be as a result of the precipitation of ?-phase from the ?-phase as the zinc content increased to 1.5wt%.