Effect of neodymium on microstructure and corrosion resistance of AZ91 magnesium alloy

The corrosion behavior of a new Mg–9Al– 1Zn (AZ91) magnesium alloy containing neodymium (Nd) is investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), immersion tests and electrochemical experiments. The results indicate that Nd decreases the size and volume fraction of the b (Mg17Al12) phase and forms Al2Nd in the alloy. In addition, during corrosion, Nd is incorporated into corrosion film in the form of Nd2O3. AZ91 alloy containing 1.0 wt.% Nd possesses an outstanding passivation property and excellent corrosion resistance. The corrosion resistance enhancement is attributed to the reduction in the size and volume fraction of the b phase and the incorporation of Nd2O3 in the corrosion film.