Crystallographic orientation-dependent galvanic corrosion between α-Mg and Mg12Nd in Mg–Nd alloy

The Mg 12 Nd phase in Mg-Nd alloys exhibits complex electrochemical behavior beyond the conventional micro-galvanic model with fixed anode/cathode assignments. This work demonstrates that Mg 12 Nd undergoes preferential corrosion while simultaneously facilitating cathodic reactions, with relative Volta potential varying locally between Mg 12 Nd and α-Mg. First-principles calculations reveal that this potential reversal originates from crystallographic-dependent work functions (3.54–3.73 eV for α-Mg, 3.30–3.74 eV for Mg 12 Nd), where interfacial crystallography dictates electrochemical polarity rather than the phase type alone. Such anisotropy-mediated dual functionality accounts for the anodic and cathodic behavior of Mg 12 Nd during corrosion. This study shows that crystallographic and electronic properties need to be considered as factors in developing effective corrosion control strategies in Mg-based alloys.