Behavior of Al-Mg alloys at high-temperature

The behaviour of a few Al—Mg alloys (up to 7.1 wt% Mg) has been studied on heating in air 500oC for 8h or more. The precipitation of a spinel phase, MgAl2O4, is found to take place in the surface and along the transverse section (depth) of the specimen. The alloys seem to resistant to internal oxidation below 4.5% Mg and thereafter prone to it. Beryllium modification does not suppress the progress of internal oxidation taking place in the Al-Mg alloys. The results have been interpreted on the basis of anodized photomicrographs and X-ray diffraction data