Effect of nickel addition on microstructure, tensile and corrosion properties of cold rolled silicon bronze

In this study, silicon bronze (Cu-Si) with nickel addition was fabricated using double stir casting technique. The influence of nickel addition and cold deformation on the microstructure, hardness, tensile and corrosion properties of the fabricated alloys were investigated. The microstructure of the alloy was evaluated using an optical microscope. Microhardness tester was used to determine the hardness while the tensile property was obtained from the hardness data. Potentiodynamic polarization measurement was used to study corrosion behaviour in 0.5 M H₂SO₄. The result show that the Ni modified Cu-Si alloys revealed the presence of Cu rich α-phase and δ-Ni₂Si precipitates along the a grain boundaries. The δ-Ni₂Si precipitates increased with increase in Ni content. The addition of Ni reduces the grain sizes and refine the microstructure. The hardness and tensile strength of the Ni modified Cu-Si increased with an increase in Ni addition from 0.2 to 0.8 wt%. The silicon bronze showed excellent corrosion resistance in a sulfuric acid environment with Ni addition. This is evident from the reduction in corrosion current density (I_corr) with an increase in Ni content.