Effect of Ti on the corrosion resistance of Al-Cr-Fe-Mn-Mo-Ni single and multi-phase CCAs

• Published in: Corrosion science 2024-08, Vol.236, p.112262, Article 112262
• Main Authors: Inman, S.B., Han, J., Hoyos, D.I., Poon, S.J., Ogle, K.M., Scully, J.R.
• Format: Article
• Language: English
• Subjects: Chemical Sciences; Compositionally Concentrated Alloys (CCAs); High Entropy Alloys (HEAs); Microstructure; Passivity; Titanium; X-ray photoelectron spectroscopy
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2024.112262

Five Al0.3Cr0.5Fe2Mn0.25Mo0.15Ni1.5Tix compositionally concentrated alloys were synthesized, forming alloys with an FCC matrix. At Ti concentrations of 5 at% and above, an L21 phase enriched in Al, Ti and Ni was present within the FCC matrix. At Ti concentrations of 9.6 at% Ti and above, a three-phase microstructure containing FCC+L21+Laves phases was formed, with the Laves third phases enriched in Cr and Mo. Ti(IV) was a prominent constituent in the passive film. Resistance to localized corrosion improved with Ti concentration before reaching an optimal concentration and beginning to decrease, likely due to the formation of new phases. •The passivation and corrosion behavior of a Ti-containing, multi-phase complex concentrated alloy series is characterized.•At increased Ti concentrations, an L21 phase enriched in Al, Ni, and Ti and/or a Laves phase enriched in Cr and Mo form.•Pitting and repassivation potentials increase with Ti content up to 6 at% but decrease at higher Ti concentrations.•Elemental fates are tracked with X-ray Photoelectron Spectroscopy and Atomic Emission Spectroelectrochemistry.•Ti(IV) species are prevalent in the passive film despite Ti depletion in the FCC matrix.