Behavior of magnesium dissolved in the surface of aluminum alloy powders

We have investigated the behavior of magnesium dissolved in aluminum alloy powders by X-ray photoelectron spectroscopy using synchrotron radiation (SR-XPS). The SR-XPS method allows free selection of X-ray energy to tune the kinetic energy of the photoelectrons for material surface analysis within 0.5 nm. Furthermore, due to the high intensity of the SR's X-ray source and the larger photoionization cross section, measurements can be completed within a few minutes. We applied the SR-XPS system to analyze the chemical reactions of aluminum alloy powder surfaces. In heating the powders to 823 K, magnesium dissolved in the powders was concentrated to the surface oxide below 670 K, and finally, over 670 K, the magnesium reduced the aluminum oxide of powder surfaces by chemical reaction, broke the surface oxide films, and metallic aluminum appeared on the topmost surface of the powder. The reduction was the initial reaction in a new aluminum nitridation method developed by one of the authors.