Exploring the influence of tensile load on the nature of passive film during stress corrosion cracking in a TRIP Fe39Mn20Co20Cr15Si5Al1 (at.%) high entropy alloy.

A passive film serves as a first defense of any material against the attack of a corrosive environment for any material. So, it is essential to understand the parameters affecting the characteristics of the passive film. The present work focused on investigating the effect of tensile load during stress corrosion cracking (SCC) condition on the characteristics of the passive film developed on a TRIP Fe 39 Mn 20 Co 20 Cr 15 Si 5 Al 1 high entropy alloy (HEA) in a 3.5 wt.% NaCl solution at room temperature. A constant load of ∼25% of the yield strength was applied to a flat dog-bone-shaped tensile specimen for 24 h in a 3.5 wt.% NaCl salt environment. For comparison purposes, a specimen with no-load was kept in a salt solution under similar conditions. Electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) techniques were used for passive film characterization. EIS results revealed that the passive film deposited on the no-load and load conditions exhibited a dense and stable structure. However, the passive film deposited on the no-load specimen showed relatively better resistance to corrosion ions. XPS results indicated that the passive film deposited on the no-load and load specimens consisted of Cr rich oxide and hydroxide, forming a monolayer type of passivation film. Nonetheless, the passive film on the no-load specimen exhibited higher concentrations of Cr than the passive film on the loaded specimen. XPS depth profile results showed that the film thickness was relatively greater for the no-load specimen than for the loaded specimen. This study underscores the critical influence of tensile load on the degradation of passive film properties of the HEA. [ABSTRACT FROM AUTHOR]