Characterization of localized corrosion of heat treated Er- and Zr-containing A356 alloys in 3.5 wt% NaCl aqueous solution

The influences of Er and Zr additions on the corrosion behavior of A356 (Al-7Si-0.4Mg) alloy are investigated. Electrochemical tests (potentiodynamic polarization and electrochemical impedance spectroscopy), gravimetric analyses, and microstructural investigations demonstrate that 0.3 wt% Er nominal addition is beneficial for the corrosion resistance of A356 alloy, due to a modified eutectic morphology and a low volume fraction of intermetallic compounds. The further addition of about 0.5 wt% Zr, on the other hand, partially reduces the corrosion resistance of Er-containing A356 alloy, possibly due to a higher amount of intermetallic compounds which promote corrosion localization.