Nanoscale tantalum dispersion suppresses marine corrosion of copper via cathodic blocking

Marine Cu-Ni alloys suffer sulfide and flow-induced corrosion, and fluctuating nickel prices drive the demand for nickel-free alternatives. Despite good mechanical properties, the seawater corrosion behaviour of nanocrystalline Cu–Ta alloys remains unclear. This work computationally explores 0–20 at% Ta Cu–Ta alloys and reveals a dual anti-corrosion mechanism. Ta 2 O 5 -coated nanoparticles significantly inhibit oxygen reduction via cathodic blocking. Compared with Cu 2 O films (0.41 V passivity margin), Ta 2 O 5 offers superior seawater stability with a 1.63 V margin. High-throughput screening determines the optimal composition (5–13 at% Ta) and microstructure (3–10 nm particles). The optimized Cu–Ta alloys exhibit a corrosion rate of 0.015–0.025 mm·y −1 , comparable to commercial Cu–10Ni alloys while avoiding nickel-related drawbacks. Grain boundary enrichment and oxygen reduction current density ratio dominate corrosion performance. The preliminarily identified cathodic feature of Cu–Ta galvanic coupling needs experimental validation. This method enables efficient corrosion screening for immiscible alloys.