Electron beam induced oxidation of Al–Mg alloy surfaces

Electron beam currents of a few nanoamperes, currently used in nanometer scale scanning Auger/electron microscopy, induces severe oxidation of Al–Mg alloy surfaces at room temperature. Auger peak-to-peak oxygen curves for Al–Mg surfaces support the hypothesis that the electron beam creates additional nucleation sites for oxidation. However, the oxygen curves are described with a more complex functional form than that of single element oxidation investigated in the past. The e-beam oxidizes mainly the Al on areas where Mg is in solid solution, while on areas where the Al3Mg2 phase is present a complex oxidation process takes place. In this case, besides Al oxidation also Mg oxidizes on the surface accompanied by Mg segregation through the surface oxide layer.