Influence of β-Mg17Al12 and Al-Mn intermetallic compounds on the corrosion behaviour of cast and solution treated Mg-Al-Zn-Mn alloys

This study aims to investigate the correlation between the microstructure and corrosion behaviour of AZ series alloys, using analytical scanning electron microscopy, X-ray computed tomography, hydrogen evolution test, weight loss method, electrochemical measurement, and observation of corroded morphology. The results indicate that a 3D interconnected eutectic network is effective in preventing localized corrosion in chloride solution. It is also revealed that solution treated Al-Mn intermetallics lead to filiform corrosion, rather than pitting corrosion, as seen τ-AlMn and Al8Mn5 particles. This is due to the potential difference reduction between the complete Al11Mn4 shell and the α-Mg matrix.