Microstructure and wear resistance of the laser-cladded Al0.8CrFeCoNiCu0.5Bx high-entropy alloy coating on aluminum

Coatings with excellent mechanical properties are difficult to prepare on the aluminum alloy surfaces by laser surface engineering because of the low melting point and active chemical properties of aluminum (Al). Based on the unique entropy effect of a high-entropy alloy, we suppress the cracks in the cladding layer caused by the dilution ratio of the substrate, obtaining coatings exhibiting excellent wear resistance. The Al _0.8 CrFeCoNiCu _0.5 B _x coating exhibited a BCC1 + BCC2 + FCC phase when the x ≤ 0.1. When x ≥ 0.2, boride was formed in the Al _0.8 CrFeCoNiCu _0.5 B _x coatings, and it became the main phase of the Al _0.8 CrFeCoNiCu _0.5 B _0.3 and Al _0.8 CrFeCoNiCuB _0.4 coatings; however, no Al-rich intermetallic compound with a complex phase structure was formed. When 0 ≤ x ≤ 0.3, the bonding strengths of the Al _0.8 CrFeCoNiCu _0.5 B _x coatings were 70.6–176.2 MPa. An increase in the boron content increased the hardness of all the coatings, except the Al _0.8 CrFeCoNiCu _0.5 B _0.3 coating. The hardness was 479–705 HV (6–9 times that of the substrate). The wear rate of the coating ranged from 1.50 × 10 ^−7 to 1.19 × 10 ^−5 mm ^3 /Nm, which was only 0.01%–5.43% that of the substrate. The Al _0.8 CrFeCoNiCu _0.5 B _0.2 coating exhibited the highest resistance to wearing, and its wear mechanism was identified as abrasive wear.