Corrosion Behavior of As-Cladding Al0.8CrFeCoNiCu0.5Six High Entropy Alloys in 3.5% NaCl Solution

Abstract

The corrosion behavior of Al 0.8 CrFeCoNiCu 0.5 Si x (x=0, 0.2, 0.3) high-entropy alloy laser cladding coatings in a 3.5% NaCl solution was investigated using polarization tests, impedance spectroscopy, scanning electron microscopy, and energy dispersive spectroscopy. As the Si content increased, the over-passivation potential and the width of the passivation zone for the Al 0.8 CrFeCoNiCu 0.5 Six coating expanded, while the corrosion current density tended to decrease, enhancing the stability of the passivation film and the corrosion resistance of the coating. The Al 0.8 CrFeCoNiCu 0.5 coating underwent selective corrosion, with some pitting corrosion distribution showing no apparent regularity. The Al 0.8 CrFeCoNiCu 0.5 Si 0.2 coating exhibited a distinct grain profile with a tendency towards intergranular corrosion. The aggregation of Cu-rich and Al-Ni intergranular phases in the eutectic structure led to preferential erosion at the grain boundaries by corrosion ions in the Al 0.8 CrFeCoNiCu 0.5 Si 0.2 coating. The Al 0.8 CrFeCoNiCu 0.5 Si 0.3 coating presented corrosion pits, although their distribution did not display apparent regularity. The Al 0.8 CrFeCoNiCu 0.5 Si x high-entropy alloy coating demonstrates superior corrosion resistance in solution compared to 5083 aluminum alloy.

Microstructure, Hardness, Wear Resistance, and Corrosion Resistance of As-Cast and Laser-Deposited FeCoNiCrAl0.8Cu0.5Si0.5 High Entropy Alloy

“…The effective capacitance value is in- As demonstrated in the impedance spectra in Figure 6b, the capacitive reactance arc radius of the laser-deposited alloy is larger. The capacitive reactance arc radius is related to the resistance of the corrosion process; a larger radius signifies greater resistance to the reaction and, consequently, a lower corrosion rate [37]. An equivalent circuit with two-time constants is used to extract quantitative information from the EIS, as shown in Table 3.…”