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Scandium is a potential alloying element for improving the high temperature properties (above 300°C) of magnesium alloys. Scandium (T_m=1541°C) increases the melting point of the magnesium solid solution, diffuses slowly in magnesium and has a lower density than other potential alloying additions (3 g cm⁻³). Based on thermodynamic equilibrium calculations the alloys MgSc6Mn1 and MgSc15Mn1 were prepared using the squeeze casting technique. The alloys showed a strong annealing response due to the formation of Mn₂Sc precipitates. The low diffusivity of the alloying elements retards the overageing process. The existence of the Mn₂Sc precipitates was confirmed by X-ray diffraction and energy dispersive X-ray microanalysis. The ultimate tensile strength of the new alloys was somewhat lower than the corresponding values for the high creep resistant conventional alloy WE43 (Mg–4.0wt.% Y–1.0wt …