Initial corrosion behavior of AZ91 magnesium alloy in simulating acid rain under wet-dry cyclic condition

Corrosion behavior of AZ91 magnesium alloy in simulating acid rain under wet-dry cyclic condition was investigated. The results show that corrosion potential shifts positively and the corrosion current density decreases at low wet-dry cyclic time. Further increase of the cyclic time results in the negative movement of corrosion potential and the increase of current density. SEM observation indicates that corrosion occurs only in α phase, β phase is inert in corrosive medium, and the corrosion of AZ91 magnesium appears in uniform characteristic. XPS analysis suggests that the corrosion product is mainly composed of oxide and hydroxide of magnesium and aluminum, and a small amount of sulfate is also contained in the film.