Numerical investigation of corrosion phenomena in heat-treated Mg-1Er-1Yb alloy via multiphysics modeling

Abstract This study examines the galvanic corrosion behaviour of a Mg-1Er-1Yb alloy when coupled with 316L stainless steel, with particular emphasis on the influence of artificial aging. The alloy was solution-treated and aged at 200 °C for 5 h (HT5), 10 h (HT10) and 15 h (HT15), and compared with the base metal. Electrochemical characterization was performed in 3.5 wt.% NaCl using a three-electrode cell, with potentiodynamic scans conducted from −250 mV to +250 mV versus OCP at a scan rate of 1 mV s⁻¹. The Tafel parameters (βₐ, β c ), corrosion potential (E corr ), and corrosion current density (i corr ) were extracted for both the Mg alloy (anode) and 316L stainless steel (cathode), enabling a quantitative assessment of galvanic interaction. Among all conditions, HT10 exhibited the most favourable performance, with a significantly reduced i corr (1.22 × 10⁻⁵ A cm⁻²) and the lowest corrosion rate (12.9 mm year⁻¹), compared to 22.8 mm year⁻¹ for the base metal. These experimental findings were incorporated into a COMSOL Multi- physics model using the Arbitrary Lagrangian Eulerian (ALE) method to dynamically track corrosion front movement under galvanic coupling. The simulated electrolyte potential fields, local current density profiles, pit morphology and thickness loss showed strong agreement with immersion and polarization results, with deviations below 7%. The study demonstrates that controlled aging at 200 °C for 10 h leads to a refined microstructure and improved galvanic compatibility with 316L stainless steel. The integrated experimental numerical approach provides a reliable framework for designing rare-earth--based Mg alloys for sacrificial anode applications.