The Role of CO2 in the Oxidation-Protection of Mg-Containing Aluminum Alloys

Abstract TEM EDS–EELS and XPS have been performed on disc samples of Al alloys 5182 (AlMg4.5Mn0.4) and 6016 (AlSi1.2Mg0.4) heat treated in an oxidizing atmosphere of 76 pct synthetic air, 20 pct Ar, and 4 pct CO 2 . For both alloys, an amorphous C–C bonded layer on top of a nanocrystalline MgO layer was observed, which is believed to inhibit further oxidation of Mg for the 5182 alloy and breakaway oxidation for the 6016 alloy.