Effect of harmonic structure on the electrochemical behavior of high entropy Cantor alloy in NaCl solution

The present work discusses the effect of harmonic structure on the corrosion behavior of high entropy Cantor alloy (Fe20Cr20Mn20Ni20Co20) in freely aerated 3.5 wt% NaCl solution. A harmonic structure featuring a continuous shell region with an average grain diameter of ∼3 μm and discreet core regions with an average grain diameter of ∼25 μm is developed in the Cantor alloy. The X-ray diffraction patterns, transmission electron microscopy and selected area electron diffraction patterns confirm the presence of face-centered cubic phase indicating that no second phase formation occurs in the shell or core regions. Its electrochemical behavior has been studied and compared with a conventional Cantor alloy, harmonic-structured 304L stainless steel, and maraging steel. The studies conclude that the harmonic-structured Cantor alloy shows the highest corrosion resistance among the tested materials. A novel mechanism for the corrosion of the harmonic-structured Cantor alloy suggests that the excellent corrosion-resistive properties are attributed to the early passivation by enrichment of Cr in the oxide layer in its shell region and reversal of polarity due to the early passivation during corrosion. •Harmonic structure develops by mechanical milling of powder followed by spark plasma sintering.•Harmonic structure in Cantor alloy induces enhanced corrosion resistance.•Early passivation in Cr enriched fine-grained shell region in harmonic Cantor alloy leads to better corrosion resistance.•Harmonic structured SUS304L shows inferior corrosion and pitting resistance than harmonic structured Cantor alloy.