High temperature oxidation of Mg2(Si-Sn)

• The breakaway oxidation behavior of Mg2Si1-xSnx at temperatures above 400 °C were studied.
• The ignition temperature for break-away oxidation is lower for higher Sn content.
• Below ignition temperature, a thin layer of MgO protects from further oxidation.
• Formation of liquid Sn below the MgO layer is the main factor causing ignition.

High temperature oxidation of Mg2Si1-xSnx alloys (x = 0.1 − 0.6) has been investigated. The oxidation rate was slow for temperatures below 430 °C. In the temperature range between 430–500 °C all the alloys exhibited breakaway oxidation. The onset temperature of the breakaway region in general decreased with increasing level of Sn in the alloy. The breakaway behavior is explained by a combination of the formation of a non-protective MgO layer and the formation of Sn-rich liquid at the interface between the oxide and Mg depleted Mg2Sn.