Corrosion Behavior of AlMgSi Alloy in Aqueous Saline Solution

Abstract

The corrosion behavior of AlMgSi alloy in a solution of 3.5 % NaCl in H2O as a function of time of immersion has been studied and assessed by means of electrochemical techniques. These included potentiodynamic polarization curves, linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS) measurements and electrochemical noise measurements (EN). The corrosion rate expressed in terms of corrosion current density of AlMgSi alloy resulted higher than that of pure Aluminum. The precipitation of Mg2Si phase and the formation of the galvanic couple Al-Mg induced a shift of the current density towards higher values. According to electrochemical noise measurements, the Al-based alloy experienced a localized type of corrosion at virtually all the time of exposure. The hydroxide or oxide films formed over the surface of AlMgSi alloy were not totally protective. The electrochemical behavior of corrosion has been explained in terms of the stability of the corrosion