A cost-effective as-cast Ni-Fe-Cr-Al-Cu eutectic high-entropy alloy with excellent strength and corrosion resistance for marine applications

Developing Cu-containing alloys that combine high strength with excellent corrosion resistance remains a key challenge in marine engineering. Although Cu-containing eutectic high-entropy alloys (EHEAs) exhibit attractive overall performance, they have so far been limited to the Ni-Fe-Co-Cr-Al-Cu system, in which the mandatory use of expensive Co undermines engineering viability, despite the indispensable role of Cu in potentially mitigating biofouling-induced degradation. Here, a cost-effective Co-free Ni-Fe-Cr-Al-Cu EHEA is designed by exploiting the differences in interelement mixing enthalpies to tailor the eutectic composition. This composition-driven strategy stabilizes an ultrafine lamellar architecture containing coherent nanoprecipitates, which simultaneously delivers high strength and superior corrosion resistance. Without any post-processing, the as-cast alloy achieves a yield strength of 732 ± 9 MPa, an ultimate tensile strength of 1061 ± 17 MPa, and an elongation to failure of 8.5 ± 1.6%. Electrochemical measurements in 3.5 wt% NaCl solution further reveal a low corrosion current density of 0.85 ± 0.09 μA cm −2 , outperforming conventional Cu-based counterparts. This eutectic-engineering strategy alleviates the long-standing trade-off between cost and performance in EHEAs and offers a scalable route toward next-generation marine structural materials.