Enhanced oxidation and overheating resistance of the extruded Mg–Zn–Al–Mn magnesium alloy by Calcium addition

Abstract

The effects of Ca addition on the microstructure and oxidation properties of a new Mg alloy were studied. The oxidation behavior of the alloys was analyzed by thermal analysis and material characterization of the alloys exposed in flame environment; and both electrical and induction furnaces. Moreover, the surface layers were characterized using field emission scanning electron microscopy, and X-ray diffraction technique. It was found that increasing the Ca addition reduces the grain size and increases the fraction of the secondary phases, and enhances the mechanical properties. Moreover, increasing the Ca contents resulted in the formation of a dense CaO/MgO layer on the surface prohibited the oxygen diffusion and assisted in protection of the substrate against further oxidation. Therefore, ignition temperature was increased from 680 °C to 890 °C after addition of the Ca element. The mechanical properties and ignition behavior of the current materials was compared with the literature which it showed an excellent combination of the properties in the developed alloys.

Keywords

• Mg alloys
• Oxidation properties
• Ca addition
• Microstructure
• Intermetallic phases