Corrosion resistance of weight reduced AlxCrFeMoV high entropy alloys

Abstract

High entropy alloys with superior hardness and corrosion resistance have proved themselves excellent coating materials. In this study, a pitting corrosion resistance analysis of AlxCrFeMoV alloys (with x = 0, 0.2, 0.6, 1), with outstanding mechanical features, has been conducted. The study was motivated by their exceedingly high pitting resistant equivalent number (PREN) values, in the range of 80-100. Powder metallurgy techniques, including mechanical alloying and spark plasma sintering, were applied to fabricate the designed alloys. To examine the pitting behavior of the alloys, the potentiodynamic and cyclic polarization analysis were performed in 3.5 wt% NaCl solution at 25 degrees C. The electrochemical impedance spectroscopy has been used to study variations in the surface characteristics of specimens in a saline environment. Also, the comparative chemistry of the passive layers formed in the primary and secondary passivation regions was evaluated by conducing X-ray photoelectron spectroscopy. The examined systems exhibited an exceptionally high pitting resistance, which was attributed to being predominantly caused by the high concentration of PREN elements in the alloys. Contrary to previously reported aluminum (Al) containing high entropy alloys, the addition of Al did not have an adverse effect on the pitting behavior of the current systems. This was due to the absence of Al-rich phases.