Surface analysis and oxidation behavior of Y-ion implanted AZ31 magnesium alloys

AZ31 samples were implanted with yttrium ions with fluences of 5 1016, 1 1017 and 5 1017 ions/cm2, using a metal vapor vacuum arc source at an extraction voltage of 45 kV. The surfaces of the implanted samples were then analyzed by Auger electron spectroscopy (AES) and Xray photoelectron spectroscopy (XPS). It was found that after treatment a pre-oxidation layer was formed, and the higher the fluence, the thicker the pre-oxidation layer was. The valence states showed that yttrium existed in the form of Y2O3. Isothermal oxidation tests have been conducted in pure oxygen at 773 K for 90 min to evaluate the oxidation behavior of the implanted samples. The results indicate that after implantation the oxidation resistance of the samples was significantly improved. Moreover, the greater the fluence, the better the oxidation resistance has been achieved. The characterization of the implanted layers after isothermal oxidation was examined by SEM, AES and XPS. From the results, it can be found that the thickness of the oxide scale formed on the implanted surfaces have been greatly decreased, and there is no obvious change for both the thickness of the pre-oxidation layer and the valence states of the elements after oxidation.