XPS Examination of the Oxide-Metal Interface of an Aluminum-Magnesium Alloy Containing Beryllium

Abstract

The addition of beryllium to high magnesium aluminum alloys has long been known to cause a significant decrease in the rate of alloy oxidation. A clear understanding of the fundamental mechanism behind this effect is still lacking. Previous work by the authors has shown that the first formed oxide layer and the oxide metal interface is of key importance. To understand the behavior of beryllium during oxidation, a detailed characterization of the metal/oxide interface was therefore carried out. XPS (X-Ray Photoelectron Spectroscopy) was used to study the oxide layer of an Al–5%Mg alloy containing an elevated beryllium content of 100 ppm, which had been oxidized in air at 550 and 700 °C. The higher concentration of beryllium than is used by industry was done to enhance its effects for easier characterization. For samples below the alloy melting point BeO–Al2O3 growths were found on the surface underneath an MgO layer. For liquid metal samples, the BeO–Al2O3 formed as a layer underneath an MgO layer.