Exploring the Corrosion Performance of AZ31 Magnesium Alloy under Acidic and Alkaline Conditions

In the current work, the corrosion performances of Mg–3Al–1Zn (wt %) alloy were explored in 1 and 3.5% NaCl (wt %) solutions under acidic (pH 2) and alkaline (pH 11) conditions using electrochemical techniques. Analysis of corrosion products after immersion test was performed using optical microscopy, X‑ray diffraction and scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM-EDS). The experimental findings revealed that increasing the chloride ion concentration and decreasing the pH value enhanced the corrosion rate of the alloy. The corrosion mechanisms were substantially influenced by the pH of the solution rather than the concentration of chloride ions. In alkaline solution, a filiform-like morphology was found, but in acidic solution, a combination of filiform-like and pitting morphologies was observed on the corroded surface. Magnesium hydroxide (Mg(OH)2) was identified as the corrosion product.