The effects of a corrosion product film on the corrosion behavior of Mg-Al alloy with micro-alloying of yttrium in a chloride solution

Micro-alloying Mg alloys with rare earth elements is an economical and promising way to improve their corrosion resistance. It is of great importance to understand their corrosion behavior for designing corrosion-resistant Mg alloys. In this work, Mg-11Al-0.2Y alloy was prepared for exploring its corrosion behavior in 3.5 wt.% neutral NaCl solution. It exhibits a low corrosion current density of 2.3 μA/cm2 after immersion for 1 d due to the formation of a protective surface film containing Al2O3, MgO and Mg(OH)2. However, nano-scaled pores exhibit at the film/matrix interface, which undermines integrity and protectiveness of the surface film after long-term exposure to chloride solution.