Electrochemical corrosion behaviour of stir cast and heat-treated EV31A magnesium alloy in different electrolytic mediums

The EV31A magnesium alloy has the potential for use in aerospace and automotive applications. To ensure the longevity of magnesium and its alloys in final applications, it is essential to know how quickly they corrode. An electrochemical approach (Tafel extrapolation and EIS) was used to evaluate the corrosion behaviour of EV31A alloy in various electrolytic mediums, including 0.6 M NaCl, 0.05 M H2SO4, 0.1 M HNO3, and 0.1 M HF. In each electrolytic solution, the stir-cast, T4, and T6 heat-treated samples corroded electrochemically. The as-cast EV31A alloy has superior corrosion resistance than T4 (solutionising) and T6 (solutionising cum age hardened). Because intermetallic precipitates have a large volume percentage in as-cast, it offers excellent corrosion resistance due to micro-galvanic or localised corrosion. In EV31A, chloride and fluoride ions have the same impact as compared with sulphate and nitrate ions. The as-cast EV31A shows a corrosion rate of 0.03 mm/year in solution containing 0.6 M NaCl and 0.1 M HF.

Automated summary

The EV31A magnesium alloy shows potential for use in aerospace and automotive applications. This study utilized an electrochemical approach to evaluate the corrosion behavior of the EV31A alloy in various electrolytic mediums, and found that the as-cast EV31A alloy exhibited superior corrosion resistance.