Surface coatings of super light magnesium–lithium alloys

The Mg–Li alloys with Li content of 5–11 mass- will exhibit a dual phase structure of α (hcp) and β (bcc) phases. These dual phase Mg–Li alloys have excellent formability, as well as extra low density. However, the Mg–Li alloys still have disadvantages of poor corrosion and wear resistance. In the present study, the AlN films deposited on Mg–Li alloy by radio frequency magnetron sputtering were investigated. The microstructure, surface morphology and corrosion resistance of the AlN films were examined by means of X-ray diffraction, SEM, TEM, and potentiodynamic polarisation. Experimental results show that deposited AlN films exhibit an amorphous structure, which can effectively improve the corrosion resistance of Mg–Li alloy. Meanwhile, the sputtering parameters, such as the radiofrequency power and working pressure, are found to have significant effects on the corrosion behaviour of deposited AlN films on Mg–Li alloy.