This study aims to extrude Mg-xEr alloys with x = 0, 1, 2 and 3 Wt.% were studied to clarify how Er content regulates corrosion in a chloride-containing solution.
Microstructure and local potential heterogeneity were characterized by XRD, SEM, EBSD and Kelvin probe force microscopy. Corrosion behavior was evaluated by hydrogen evolution, polarization, electrochemical impedance spectroscopy and immersion tests, followed by surface and cross-sectional observations.
Corrosion severity increases from Mg-1Er to Mg-2Er and then decreases for Mg-3Er. Mg-2Er shows the most severe localized attack with extensive pitting, discontinuous product coverage and pronounced penetration after 12 h immersion, while Mg-3Er exhibits mitigated damage.
The trend is attributed to microgalvanic effects controlled by second-phase distribution and continuity, together with film stability changes at higher Er content. The results provide guidance for selecting an Er content window and optimizing second-phase distribution and corrosion product film stability to enhance the corrosion resistance of extruded Mg-Er alloys.
