Insights into the corrosion behavior of Mg-1Sc alloy in varied corrosive environments: Comparative analysis of three distinct application media

This study investigates the corrosion behavior of Mg-1Sc alloy in three chemically distinct media including 3.5 wt.% NaCl, 0.1 M Na₂SO₄ and 30 vol% ethylene glycol which represent typical marine, industrial and automotive environments respectively. Mg-1Sc was selected due to the high solubility of Sc in Mg and the favorable characteristics of its corrosion products. Microstructural analysis revealed a small amount of Mg₃Sc second-phase particles with a more positive potential than the α-Mg matrix which may accelerate galvanic corrosion. Hydrogen evolution and electrochemical tests showed that the corrosion resistance of Mg-1Sc decreased in the order of EG, Na₂SO₄ and NaCl. Severe localized corrosion occurred in NaCl solution due to the penetration of Cl⁻ through porous Mg(OH)₂ films. In Na₂SO₄ solution the formation of compact MgSO₄ helped reduce the corrosion rate. In EG the low ionic activity and molecular adsorption contributed to uniform and mild corrosion. Molecular dynamics simulations confirmed the highest adsorption energy in EG and the lowest in NaCl which matched the experimental corrosion trends. These findings clarify the relationship between interfacial adsorption behavior and corrosion performance and provide insight for designing Mg alloys suited to specific service environments.