The role of Mg2Si on the corrosion behavior of wrought Mg–Zn–Mn alloy

Different quantities of silicon were added to Mg–6%Zn–0.5%Mn alloy and its effect on corrosion behavior investigated. AC and DC polarization and immersion tests were carried out on the extruded rods, which contain different quantities of silicon. A small quantity of Si (0.5 wt%) forms massive Chinese script Mg2Si intermetallics. Addition of 1 wt% or more Si was found to modify the Chinese script Mg2Si intermetallic into a fine polygonal shape. Improved corrosion behavior is noticed with the alloys containing more than 1 wt% Si addition, whereas addition of less than 1 wt% Si is found to reduce the corrosion resistance of Mg–6%Zn–0.5%Mn alloy. The polygonal shape Mg2Si intermetallics inhibit the corrosion more effectively compared to the Chinese script.