Tuning the microstructure for superb corrosion resistance in eutectic high entropy alloy

In this work, we demonstrate that the corrosion resistance of the FeCrNiCoNb_0.5 eutectic high entropy alloy (EHEA) can be tuned by controlling the size of its eutectic structure. Through microstructure refinement, the EHEA exhibits a superb corrosion resistance in 1  M NaCl in terms of a very low corrosion current density and an ultra-high transpassviation potential, which outperforms a variety of other HEAs and conventional metals and alloys. At the fundamental level, the microstructure refinement results in a rapid formation of a thick and compact passive film with less Cl⁻ adsorption on the EHEA, which results in significant enhancement in its corrosion resistance. The outcome of our research provides important insights into the design of corrosion resistant chemically complex alloys.