Corrosion behavior of AZ91 magnesium alloy in dilute NaCl solutions

The corrosion behavior of AZ91 magnesium alloy in dilute NaCl solutions was studied using electrochemical measurements, whereby a corrosion map in terms of electrode potential and chloride concentration [Cl−] was obtained. AZ91 alloy exhibited the corrosion and passivation zones in dilute NaCl solutions. The passivation zone became narrow with increasing [Cl−]. The values of open-circuit potential were in the passivation zone when the [Cl−] was less than 0.5 mol/L. XRD patterns showed the presence of the Mg(OH)2, Mg5(CO3)4(OH)2·8H2O and MgO phases in the corrosion product, whereas the latter two phases found in the passive film.