Maraging and reversion-driven passivation engineering of Fe68Ni10Mn10Co10Ti1.5Si0.5 medium entropy alloy

In this study, the relationship between the microstructural evolution, electrochemical behavior, and passivation capability in Fe68Ni10Mn10Co10Ti1.5Si0.5 medium entropy alloy (MEA) with different microstructure is investigated. The passive film formed on the selectively corroded dual -phase microstructure was characterized by an inner thin discontinuous Fe-, Mn-, Ni-, and Co -based oxides and hydroxides layer with a thinner pure Si -oxide layer partially grown on the TiO2/SiO2 layer. By contrast, a continuous oxide/hydroxide layer accompanied by a dense TiO2/SiO2 monolayer in the uniformly corroded austenitic microstructure exhibited the highest protective effect owning to the prevention of galvanic corrosion resulting in the best corrosion resistance.