Corrosion of Al xCoCrFeNi high-entropy alloys: Al-content and potential scan-rate dependent pitting behavior

• Published in: Corrosion science Vol. 119; pp. 33 - 45
• Main Authors: Shi, Yunzhu, Yang, Bin, Xie, Xie, Brechtl, Jamieson, Dahmen, Karin A., Liaw, Peter K.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.05.2017
• Subjects: A. Alloy; B. Polarization; C. Passive films; C. Pitting corrosion; C. Passive films; A. Alloy; C. Pitting corrosion; B. Polarization
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2017.02.019

•Al xCoCrFeNi high entropy alloys present superior corrosion-preventive ability.•Increased Al-content in Al xCoCrFeNi alloys degrades localized corrosion resistance.•Pitting behavior is influenced by passive film properties and migration of Cl− ions.•Mean field theory can predict the distribution of current fluctuations. The present work investigates the influence of Al-content and potential-scan-rate on stable/metastable pitting of Al xCoCrFeNi high-entropy alloys in a 3.5wt.% NaCl solution. The increased Al content causes the volume fraction of the Cr-depleted phase to increase, resulting in thicker/dispersive passive films that degrade the localized corrosion resistance. The varied stable/metastable pitting behavior under different potential scan rates indicates that pit generation is influenced by the properties of passive films and the interactions between chloride ions and the active sites. Furthermore, a mean-field theory is employed to predict the scan-rate dependent, power-law distribution of current fluctuations.