Effect of Ca Additions on Ignition Temperature and Multi-Stage Oxidation Behavior of AZ80

AZ80, AZX801, and AZX802 alloys were prepared to investigate the ignition temperature and multi-stage oxidation behavior in air. Besides, the microstructures of alloys before and after oxidation were compared. The results reveal that AZX802 exhibits the characteristics of higher ignition temperature and best oxidation resistance compared to AZX801 and AZ80, which contributes to the increase of melting temperature of secondary phase in matrix due to the formation and increase of Al2Ca, with the addition of Ca in AZ80. In addition, the incubation periods before accelerated oxidation and the beginning of the accelerated oxidation temperatures of AZ80, AZX801, and AZX802 are different during multi-stage oxidation, which also contributes to the different onset melting temperature of the secondary phase. And the beginning of the accelerated oxidation of Mg alloys at high temperature is always accompanied by the onset melting of the low melting temperature of the secondary phase and the growth of oxide nodule on the surface.