Effect of self-doping of Be into Gd₂O₃ oxide film on incombustibility of Mg-Zn-Gd alloy

Non-flammable Mg-Zn-Gd alloys were developed by small addition of Be. The Mg97Zn1Gd2 (at%) alloy exhibits relatively low ignition temperature of similar to 1020 K due to the formation of non-uniform and less protective Gd2O3 surface films, whereas Be-containing Mg-Zn-Gd alloys show high ignition temperature of more than 1200 K. Soft X-ray emission spectroscopy (SXES) revealed that Be was concentrated as metallic and oxide states in the Gd2O3 surface film on the oxidized Mg96.9Zn1Gd2Be0.1 alloys. The segregation of Be along the Gd2O3 grain boundaries prevents the inward diffusion of oxygen resulting in forming a thin and uniform Gd2O3 film.