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

Abstract

The corrosion behavior of Al0.8CrFeCoNiCu0.5Six (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 Al0.8CrFeCoNiCu0.5Six 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 Al0.8CrFeCoNiCu0.5 coating underwent selective corrosion, with some pitting corrosion distribution showing no apparent regularity. The Al0.8CrFeCoNiCu0.5Si0.2 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 Al0.8CrFeCoNiCu0.5Si0.2 coating. The Al0.8CrFeCoNiCu0.5Si0.3 coating presented corrosion pits, although their distribution did not display apparent regularity. The Al0.8CrFeCoNiCu0.5Six high-entropy alloy coating demonstrates superior corrosion resistance in solution compared to 5083 aluminum alloy.

Keywords

• High entropy alloy
• Laser cladding
• Corrosion resistance
• Corrosion behavior