• Indium addition promotes reverse plating and creates passivation film defects, enhancing the sacrificial anode performance of the coating.
• High indium content induces segregated In as cathode phase, activating τ6 phase and improving resistance to non-uniform corrosion.
• The optimal indium content of 0.1% shifts Ecorr to −0.932 V and lowers Jcorr to 4.699 μA/cm², providing best sacrificial anode effect.
• In-containing corrosion products at phase boundaries block Cl− diffusion, contributing to improved electrochemical stability.