Electrochemical Investigation of Corrosion Behavior Heat Treated Al-6Si-0.5Mg-xCu (x = 0, 0.5, 1, 2, and 4 wt%) Alloys

The corrosion behaviour of heat treated Al-6Si-0.5Mg-xCu ( x = 0.5 , 1, 2, and 4 wt%) alloys in 0.1 M NaCl solution was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The potentiodynamic polarization curves reveal that 2 wt% Cu (Alloy-4) and 4 wt% Cu (Alloy-5) content alloys are more prone to corrosion than the other alloys investigated. But the EIS test results showed that charge transfer resistance ( R c t ) increases with increasing Cu content into Al-6Si-0.5Mg. Maximum charge transfer resistance ( R c t ) is reported with the addition of 2 wt% Cu and minimum R c t value is for 4 wt% Cu content Al-6Si-0.5Mg alloy. Due to additions of Cu into Al-6Si-0.5Mg alloy, the magnitudes of open circuit potential (OCP), corrosion potential ( E c o r r ), and pitting corrosion potential ( E p i t ) in NaCl solution were shifted to the more noble direction.