Enhanced wear and corrosion resistances of AlCoCrFeNi high-entropy alloy coatings via high-speed laser cladding

In this study, an AlCoCrFeNi high-entropy alloy (HEA) coating was prepared on the surface of AISI 1045 steel by high-speed laser cladding (HLC). The microstructure, phase composition, element distribution, microhardness, wear resistance, and corrosion resistance of the coatings were analyzed, respectively. It was found that a metallurgical bond was formed, the main microstructure were the fine columnar and equiaxed dendrites, and the phase composition of the coating was a single-phase bulk cubic-centered structure (BCC/B2). Moreover, the elements of the HLC coating were evenly distributed without obvious segregation at the macro level. Compared to conventional laser cladding (CLC), the efficiencies of cladding and processing quality were improved. The scanning speed of CLC was 7 mm/s with some pores and overburning on the surface of the coating. However, the scanning speed of HLC increased by 40 times to 300 mm/s, and the surface roughness of the HLC coating was 39.83 % lower. The dilution ratio of the HLC coatings was 4.6 %, which was 3 times lower than that of 13.4 % by CLC. It also led to a significant decrease in the grain size, element transition zone, and heat affected zone. As a result, the hardness of the coating increased by 100 HV, the friction coefficient decreased by 0.15, the wear weight loss was reduced by 9.85 %, the self-corrosion potential increased by 84 mV, and the self-corrosion current density was one order of magnitude lower. Therefore, the potential application of HLC is to effectively improve the wear and corrosion resistances of HEA coatings.