Phase assemblage and wear resistance of laser-cladding Al0.8FeCoNiCrCu0.5Six high-entropy alloys on aluminum

Preparing a coating with excellent mechanical properties on aluminum substrates by laser cladding has always been challenging because of the low melting point and high chemical activity of Al. In this study, we designed Al 0.8 FeCoNiCrCu 0.5 Si x (x = 0, 0.2, 0.3, 0.4, and 0.5) high-entropy alloys (HEAs) as cladding materials. The proposed study aims to exploit the unique high-entropy effect of HEAs to restrict the the formation of hard and brittle intermetallic compounds via the reaction between Al in the substrate and added powders, thereby enhancing the quality of the formed coatings and ultimately improving the surface properties of the Al alloy. Results show that with an increase in the Si content, the structure of the Al 0.8 CrFeCoNiCu 0.5 Si x coating changes from FCC + BCC1 + BCC2 to BCC1 + BCC2. The hardness of the Al 0.8 FeCoNiCrCu 0.5 Si x coating first increases and then decreases with an increase in the Si content. The coatings with the highest and lowest hardness were those with compositions of Al 0.8 FeCoNiCrCu 0.5 Si 0.4 (592HV 0.2 ) and Al 0.8 FeCoNiCrCu 0.5 (412HV 0.2 ), respectively, which is approximately seven and five times greater than that of the substrate, respectively. The effect of Si content on the wear resistance of the coating is the same as its effect on the hardness. The wear rates of coatings with different Si contents range from 1.19 × 10 −6 mm 3 Nm −1 to 8.99 × 10 −7 mm 3 Nm −1 and are only 0.34% to 0.25% of the substrate. Obvious, the Al 0.8 FeCoNiCrCu 0.5 Si x HEAs can be used as coating materials to improve the mechanical properties of an Al alloy surface.