Corrosion resistance of WE43 Mg alloy in sodium chloride solution

Abstract

Mg-based alloys are promising light materials for structural applications such as spare parts and assembles in aerospace manufacturing, but most of them are prone to corrode. In this work, the corrosion behavior of the WE43 Mg alloy in 0.6 M NaCl solution was appraised and compared to that of commercially pure Mg. Immersion tests allowed to assess the corrosion rate and the products formed on the exposed surfaces for up to 168 h. It was found that the corrosion rate of the WE43 was about 10- to 100-fold lower compared to commercially pure Mg. The onset of the corrosion resistance of the WE43 was ascribed to the nature of the corrosion product layer and its integrity on the surface, related to the low kinetics of the cathodic reaction of hydrogen gas evolution. The electrochemical impedance spectroscopy, potentiodynamic polarization, and kelvin probe force microscopy data reinforced the effect of the alloying elements on i) the formation of Y- and Nd-rich oxides, ii) the reduction of the intensity of the hydrogen gas evolution at the underneath surface, and iii) the formation of micro-anode second phases that did not compromise the corrosion resistance. Thus, this study contributes to the prospect of using alloys such as WE43 for applications where strong and light alloys with attractive corrosion resistance in a chloride-rich environment are requested.