Modification of Eutectic Al–Si Alloy With Trace Ti and Zr for Automotive Applications in Improved Electrochemical Corrosion Performance

Titanium and zirconium are crucial grain refiner elements that significantly influence the characteristics of the Al–Si automotive alloy. Here, three different alloys are prepared: the eutectic Al–Si alloy with traces of 0.1% Ti and 0.1% Zr. First, trace elements are introduced to study their effects on the alloy’s physical and mechanical characteristics, followed by electrochemical corrosion behavior in 0.1 M sulfuric acid solutions at ambient temperature. Through the utilization of the electrochemical impedance spectroscopy method in accordance with specific equivalent circuits and the recording of Tafel dependences, data are collected to assess the kinetic and corrosion parameters in the studied environment. The findings reveal that trace Ti addition effectively refines α‐Al grain and leads to the formation of thermally stable nano‐Al 3 Ti dispersoids, which prevents a drastic decline in the strength of thermally damaged alloy. The simultaneous inclusion of Ti and Zr in the alloy further facilitates the precipitation of Al 3 (Ti,Zr) dispersoids, enhancing its overall performance. Both the EIS data and Tafel plots indicate that the incorporation of Ti enhances the corrosion resistance of the Al–Si alloy in acidic environments. Additionally, Zr facilitates accelerating the resistance to corrosion properties by expanding the passivity range, as it helps in grain refinement and inhibits the charge transfer process within the alloy matrix. Observations from optical images post‐corrosion show prominent oxide layers on the surfaces, with the base alloy being most affected, followed by the Ti‐added and both Ti–Zr‐added alloy. The SEM images display lower internal damage on the surfaces of trace‐added alloys. Furthermore, the energy‐dispersive X‐ray spectrum supports the presence of thicker oxide coatings located on the Al–Si base alloy surface, correlating with the higher surface roughness observed compared to the trace‐added alloys.