Numerical Simulation of the Effects of Temperature and Porosity on Corrosion Behaviors of β-Li Phase in Mg-8Li Alloy

In this study, the effects of temperature and corrosion product porosity on the micro-galvanic corrosion behavior of the β-Li phase in Mg-8Li alloy are systematically investigated using COMSOL Multiphysics numerical simulations. A two-dimensional micro-galvanic corrosion model incorporating mass transport, electrochemical reactions, and level set-based interface tracking is established to simulate the corrosion evolution over 72 h under varying temperature and porosity levels. The results indicate that temperature can significantly accelerate the corrosion process and the exchange current density increases exponentially. As the temperature increases from 35°C to 55°C, the electrolyte potential shifts negatively, and the maximum electrode thickness change rises from 8.2 to 34.0 mm, indicating that the localized corrosion approximately doubles when the temperature increases by 10°C, and the peak local current density increases from 250 to 1100 A/m². When the corrosion product porosity increases from 3% to 4.5%, the corrosion current density increases from 60.2 to 162 A/m², and the thickness of the corrosion product layer increases from 0.5 to 2.0 mm. Simultaneously, under high porosity conditions, the current distribution becomes more uniform, and corrosion products form a more evenly distributed deposition layer, mitigating excessive localized corrosion. The combined effects of temperature and porosity significantly alter the interfacial ion transport and current density distribution, thereby governing the corrosion evolution path and interface morphology of the β-Li phase.