Unveiling the effect of Al–Mn intermetallic on the micro-galvanic corrosion of AM50 Mg alloy in NaCl solution

Abstract

The influence of Al–Mn intermetallic on corrosion resistance of AM50 alloy was investigated. TEM-SAED was utilized to identify microstructure and composition of the corrosion products on Al–Mn intermetallic. The electrochemistry results revealed that the corrosion rate of pure Mg was lower than AM50 due to thermodynamic driving force for micro-galvanic corrosion by Al–Mn with matrix. Although the Volta potential difference reduce because of accumulation of corrosion products, the cathodic activity of AM50 alloy increases with exposure time. The progress of corrosion could not be inhibited since the loose and porous corrosion products provided an area for containing and storing the corrosion medium.

Keywords

• Al–Mn
• Micro-galvanic corrosion
• Mg alloy
• Corrosion product
• SKPFM
• TEM