Inhibition mechanism of interaction effect between charged character of inhibitor and rare earth elements for Mg-Gd-Y alloy

The inhibition mechanism of four inhibitors with different charge on Mg-Gd-Y alloy was investigated experimentally and theoretically. The different charge of inhibitor evoked the preferential adsorption behavior, changing the susceptibility of Mg-Gd-Y alloy to micro-galvanic corrosion. Moreover, the adsorption of inhibitor changed the surface energy of embryos of corrosion product, and strongly suppressed the nucleation rate of corrosion product, leading to poor protective performance. Thus, the inhibitor with anion, exhibiting satisfactory inhibition efficiency for AZ/AM series alloys, showed worse inhibition for the Mg-Gd-Y alloy. Finally, the strategy to select and/or synthesize inhibitors for Mg-RE alloys was presented.