Corrosion and high-temperature oxidation of AM60 magnesium alloy

The corrosion and high-temperature oxidation characteristics of AM60 Mg alloy in different environments were investigated by immersion test, electrochemical polarizing analysis and differential thermal analysis （DTA）/thermo gravimetric （TG） experiments. The influence of aging heat treatment on the corrosion resistance of AM60 Mg alloy was studied. AM60 Mg alloy shows better corrosion resistance in sea water than in 3.5%（mass fraction） NaCI solution. The corrosion resistance after aging for 24 h is better than that of both as-cast and aging for 48 h. Corrosion resistance of Mg alloy is controlled by microstructure, composition of a-matrix. Precipitation offl phase along the grain boundaries acts as a barrier that decreases corrosion rate, whereas the decrease of aluminum content of a phase causes an increase in the corrosion rate. The DTA and TG curves of heating process in air are characterized with combustion after 590℃. When heated in helium, the curves show two endothermic peaks and a remarkable evaporation of magnesium. As for isothermal DTA and TG experiments, mass increment caused by oxidation does not happen till 520 ℃.