Corrosion behavior of AZ91 magnesium alloy in dilute NaCl solutions

摘要

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, Mg_5(CO_3)_4(OH)_2· 8H_2O and MgO phases in the corrosion product, whereas the latter two phases found in the passive film.