A review on ignition mechanisms and characteristics of magnesium alloys

Magnesium alloys have become more attractive because of their low density and electromagnetic shielding effectiveness in the aerospace industry. However, some unpredictable situation may lead to the ignition of magnesium alloys. In this review, the thermodynamic conditions and transfer processes of magnesium alloys ignition are analyzed from the point of mechanisms. The criteria of ignition are emphasized. In addition, ignitability and flammability test systems are compared. And a more suitable method to assess the potential ignition and flammability risks of magnesium alloys in extreme environments is recommended. Furthermore, the ignition characteristics of magnesium alloys are discussed in detail. It was found that the ignition of magnesium alloys is a complex process determined by internal properties such as thermo-physical properties, oxide film properties, chemical compositions and geometrical parameters, as well as the external environment such as gas species, oxygen concentration and oxygen pressure. Ignition temperature is not physical constants of materials. It is not simply assumed that ignition may occur when the temperature of Mg alloys reaches a certain ignition point. Finally, the unsolved issues in the ignition of magnesium alloys are pointed out and the future investigation are suggested for improving the safety and reliability of magnesium alloys in the aerospace applications.