Early high temperature oxidation behaviors of Mg-10Gd-3Y alloys

In the present study, the isothermal early oxidation behaviors of Mg-10Gd-3Y alloys were studied over the temperature range of 723-873 K in pure O-2 up to 90 min. In general, the oxidation kinetics of the Mg-10Gd-3Y alloys obeyed a parabolic rate law and the higher the oxidation temperature was, the greater the oxidation rate was. Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) were used to analyse the formed oxide film. The results indicated that an oxide film with a duplex structure had formed, which was composed of Gd2O3, Y2O3 and little MgO. The oxide scale morphologies were observed by scanning electron microscopy (FEI, SEM), which showed a dense and compact film. In contrast to pure Mg, the improved oxidation resistance of the Mg-10Gd-3Y alloys can be due to the formed dense oxide film. Finally, the corresponding oxidation mechanism, which represented a complex process during the isothermal oxidation, was also discussed. (C) 2008 Elsevier B.V. All rights reserved.