This project seeks to understand the impact of Scandium (Sc) additions on oxide formation and ignition of molten magnesium. The introduction of lightweight Magnesium (Mg) alloys in the interior of aircraft has the potential to decrease the weight by 20-30%. However, the lower ignition temperature of conventional magnesium alloys restricts their use in aerospace applications. This project aims to develop a new generation of magnesium alloys having ignition points satisfying the FAA’s criteria, which would allow for their use in the aircraft interior. This will be achieved by the creation of complex multi-layered oxide structures that form alongside MgO via the addition of various suitable elements.

The three primary parameters that determine the effectiveness of an element in forming a protective oxide layer are Pilling-Bedworth ratio, Gibbs free energy and solubility. One element which shows significant promise as an effective ignition inhibitor in Mg and satisfies the above criteria is Scandium (Sc). Preliminary investigations have shown that Sc has a Pilling-Bedworth ratio of 1.18 which puts it in the category of a highly protective oxide layer. Furthermore, Sc oxide has a Gibbs free energy (-1210 kJ/mol) that is lower than that of MgO (-1125 kJ/mol) which means it will form preferentially on the surface of the alloy in the event of oxidation. Finally, Sc has excellent solid solubility of approximately 10 wt% in Mg, preventing the formation of any low melting phases that can significantly reduce the alloy ignition temperature. However, there is extremely limited work that has been conducted on Sc additions in Mg. Some basic studies have shown promising results of Sc additions on increasing the strength of Mg. However, there is a severe lack of detailed characterization and a poor understanding of the specific impact of Sc on the ignition and flammability characteristics.

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