Early oxidation behaviors of Mg-Y alloys at high temperatures

The early oxidation behaviors of Mg-Y alloys (Y=0.82, 1.09, 4.31 and 25.00 wt.%) oxidized in pure 02 have been investigated at high temperatures. The results showed that the oxidation behaviors of the Mg-Y alloys (Y=4.31 and 25.00 wt.%) obeyed a parabolic law, while that of the Mg-Y (Y = 0.82 and 1.09 wt.%) exhibited both parabolic and linear kinetics depending on the oxidation temperature. Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses indicated that an oxide film with a single structure composed of MgO and Y2O3 had formed. Moreover, the higher the oxidation temperature was, the thicker the oxide film was. Finally, the corresponding oxidation mechanism has been discussed, and the improved oxidation resistance of the Mg-Y alloys can be due to the formation of a continuous Mg-dissolving Y2O3 protective film. (C) 2007 Elsevier B.V. All rights reserved.