The oxidation of dilute alloys of magnesium in aluminium

Abstract

The oxide layers developed during the oxidation of aluminium alloys containing 500 and 1000 PPM of magnesium at 850K were examined with the aid of electron spectroscopy for chemical analysis. The magnesium content of the oxide layers was relatively high because of the preferential depletion of the magnesium atoms from the base alloys. Near the outer surfaces of the oxide layers, spinel (MgAl2O4) was the predominant magnesium-bearing compound. At depth, MgO was more dominant. The preferential depletion of magnesium from the alloys injected vacancies into the material. This led to the formation of defect clusters. The presence of these defect clusters explains the experimental observations reported earlier by other researchers.