Characteristics and corrosion studies of vanadate conversion coating formed on Mg-14 wt%Li-1 wt%Al-0.1 wt%Ce alloy

Mg-14Li-1Al-0.1Ce alloy is immersed in NH4VO3 + K3(Fe(CN)6) solutions with different NH4VO3 and/or K3(Fe(CN)6) concentrations, and different immersion time. The surface morphology and composition of the vanadate coating are then characterized by scanning electron microscopy with energy dispersion spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS), and the corrosion behavior of the conversion coating is studied by polarization technique and electrochemical impedance spectroscopy (EIS). The experimental results indicate that the vanadate film with better corrosion resistance forms on Mg-Li-Al-Ce surface after the sample is immersed in 30 g L−1 NH4VO3 + 3.75 g L−1 K3(Fe(CN)6) solution at 80 °C for 10 min. The coating consists of V2O5, Li2O and Mg(OH)2.

► Vanadate film forms on the surface of Mg-Li-Al-Ce alloy. ► Vanadate coating improves the corrosion resistance. ► Vanadate coating is composed of Mg(OH)2, Li2O and V2O5.