Enhancing Pitting Corrosion Resistance Of Al_xcrfe_(1.5)mnni_(0.5) High-entropyalloys By Anodic Treatment In Sulfuric Acid

摘要

High-entropy alloys are a newly developed family of multi-component alloys that comprise various major alloying elements. Each element in the alloy system is present in between 5 and 35 at.%. The crystal structures and physical properties of high-entropy alloys differ completely from those of conventional alloys. The electrochemical impedance spectra (EIS) of the Al_xCrFe_(1.5)MnNi_(0.5) (x=0, 0.3, 0.5) alloys, obtained in 0.1 M HCl solution, clearly revealed that the corrosion resistance values were determined to increase from 21 to 34 Ωcm~2 as the aluminum content increased from 0 to 0.5 mol, and were markedly lower than that of 304 stainless steel (243 Ωcm~2). At passive potential, the corresponding current declined with the anodizing time accounting, causing passivity by the growth of the multi-component anodized film in H_2SO_4 solution. X-ray photoelectron spectroscopy (XPS) analyses revealed that the surface of anodized Al_(0.3)CrFe_(1.5)MnNi_(0.5) alloy formed aluminum and chromium oxide film which was the main passivating compound on the alloy. This anodic treatment increased the corrosion resistance in the EIS measurements of the CrFe_(1.5)MnNi_(0.5) and Al_(0.3)CrFe_(1.5)MnNi_(0.5) alloys by two orders of magnitude. Accordingly, the anodic treatment of the Al_xCrFe_(1.5)MnNi_(0.5) alloys optimized their surface structures and minimized their susceptibility to pitting corrosion.