Influence of alloyed magnesium on the microstructure and long-term corrosion behavior of hot-dip Al-Zn-Si coating in NaCl solution

The effects of alloyed magnesium on the corrosion behavior of hot-dip Al-Zn-Si-xMg (x=0, 1.25, 3 and 4wt.%) coatings were investigated by analysis of the phase composition, long-term immersion test and electrochemical measurements. Mg2Si phase appeared in the Al-Zn-Si-1.25Mg and Al-Zn-Si-3 Mg coatings but only MgZn2 phase existed on the surface of Al-Zn-Si-4Mg coating. The alloyed magnesium improves the corrosion resistance of the Mg-containing coatings and the Al-Zn-Si-3Mg coating shows the highest protective properties in the investigation. (C) 2015 Elsevier Ltd. All rights reserved.