Synthesis and characterization of FeCoCrAlCu high-entropy alloy coating by laser surface alloying

• FeCoCrAlCu high-entropy alloy coating has been synthesized by laser alloying.
• The HEA coating is mainly composed of a single BCC solid solution phase.
• The microstructure of the coating is mainly composed of a dendritic structure.
• The microhardness of the coating is more than 8 GPa, which is 3 times that of the substrate.
• The high-entropy alloy coating shows a superior wear resistance.

FeCoCrAlCu high-entropy alloy coating was synthesized on Q235 steel with premixed high-purity Co, Cr, Al and Cu four-component powders on a Fe-base alloy by laser surface alloying. Constituent phases, microstructure and chemical composition of the coating were investigated using XRD, SEM, and EDS, respectively. Surface mechanical property and wear resistance were also studied. Results showed that the FeCoCrAlCu coating was ~ 800 μm in thickness, and a hard high-entropy alloy coating with good metallurgical bonding to the substrate was obtained. FeCoCrAlCu coating was composed of a single BCC solid solution. The microstructure of the coating exhibited a typical dendrite structure growing from the substrate. The microhardness of the FeCoCrAlCu coating was ~ 3 times that of the Fe-base alloy substrate. The wear resistance of the FeCoCrAlCu coating was also improved. Both the wear volume and specific wear rate of the coating are an order of magnitude lower than that of the Q235 substrate under a dry sliding condition, which might be attributed to the fact that the wear resistance is proportional to the alloy hardness according to Archard's law.