Microstructure modulation improving the mechanical and electrochemical properties of Pb-Ag-Ca Alloy

The homogeneous microstructure within a lead alloy matrix plays a crucial role in enhancing its mechanical and electrochemical properties. This study investigates the changes in microstructure uniformity of as-cast and rolled Pb-0.3%Ag-0.07%Ca alloys produced at varying stirring speeds, and examines their impact on alloy properties. By altering the stirring speed during the melting and casting processes, the results demonstrate that an appropriate stirring speed significantly improves the overall homogeneity of the alloy. However, excessively high stirring speeds generate numerous second-phase impurities and defects within the lead matrix, negatively affecting both mechanical and electrochemical properties. The optimal uniform composition and homogeneous microstructure are achieved at a stirring speed of 100 r/min, leading to more consistent hardness. The Pb-0.3%Ag-0.07%Ca alloy exhibits maximum tensile strength and yield strength values of 40.73 MPa and 28.50 MPa, respectively. This uniformity is conducive to a reduction in oxygen evolution potential by 30 mV, a 22.77% decrease in charge transfer resistance, and a 1.49% increase in corrosion resistance. Additionally, it promotes the formation of a uniform and dense PbO ₂ protective layer.