Development of non-flammable high strength extruded Mg-Al-Ca-Mn alloys with high Ca/Al ratio

A series of non-flammable high strength Mg-Al-Ca-Mn alloys with high Ca/Al ratio were fabricated by water-cooled casting and hot extrusion. Microstructure and mechanical properties were investigated to study the effect of hot extrusion. The experimental results showed that hot extrusion significantly improved the mechanical properties by grain refinement and precipitates. Ignition temperature was measured by furnace test, and the highest temperature is up to approximately 1040 °C due to the composite oxide layer consisting of CaO and MgO. In addition, a laboratory-scale flame test was conducted to evaluate the flammability of smaller specimens. These alloys exhibited marvelous flame resistance attributed to the protective effect of dense and stable oxide film.