Passivation and Localized Corrosion Resistance of Al0.3cr0.5fe2moxni1.5ti0.3 Compositionally Complex Alloys: Effect of Mo Content

Abstract

Al0.3Cr0.5Fe2MoxNi1.5Ti0.3 (x = 0, 0.05, 0.15) FCC+L21 compositionally complex alloys are investigated using electrochemical and surface science methods in 0.1 M Na2SO4 and 0.1 M NaCl at pH 4 and 10. Mo is mainly found in the FCC phase and amplifies elemental partitioning. The passive film is enriched in Cr(III), Ti(IV), Mo(VI), and (at pH 4) Al(III) with elemental fates tracked during film formation and dissolution. Mo presence suppresses Ni passivation in favor of more stable species such as TiO2. Pitting and repassivation potentials increase at higher Mo concentrations, suggesting improved resistance to localized corrosion often initiated at FCC-L21 interfaces.

Keywords: Passivation Compositionally complex alloys High entropy alloys MolybdenumAtomic emission spectroelectrochemistry X-ray photoelectron spectroscopy