Corrosion Behavior of AZ31B Magnesium Alloy in High‐Temperature Deionized Water

ABSTRACT Mg alloy corrosion is mainly related to water in ethylene glycol coolant. Meanwhile, engine works, the temperature of coolant reaches 80°C–110°C. Thus the corrosion behavior of AZ31B Mg alloy in high‐temperature deionized water was investigated using weight loss tests, optical microscope, scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X‐ray diffraction (XRD), and X‐ray photoelectron spectroscopy (XPS), and the results revealed that its corrosion rate at 90°C was higher than that at 30°C due to the intense hydrogen evolution and its serious destruction to corrosion product film. At 90°C, with raising soaking period, its corrosion rate significantly decreased because of the generation of a more complete corrosion product film. High temperature could cause inner layer MgO to convert into Mg(OH) 2 , and corrosion products were composed of inner layer MgO and outer layer Mg(OH) 2 and Al(OH) 3 .