The effect of calcium addition to magnesium on the microstructure and compositional changes of oxide film formed at high temperature

Microstructural and compositional changes of oxide films were investigated in pure magnesium and Mg-1.51 mass%Ca alloy oxidized at high temperature. T he oxide films of pure magnesium formed at high temperature above 500 degre esC were porous, whereas those of Ca-containing alloy were compact, thin an d dense. II was found that the oxide films of Ca-containing alloy were basi cally in the amorphous state containing a high Volume fraction of CaO, whil e those of liquid oxidation were identified as a mixture of amorphous and m icrocrystalline structure. The retardation and suppression of solid and liq uid oxidation at high temperature in Ca-containing magnesium alloy was caus ed by the formation of compact amorphous oxide films.