Effects of W element on the microstructure, wear and cavitation erosion behavior of CoCrFeNiMnW high entropy alloy coatings by laser cladding

CoCrFeNiMnWx (x = 0, 0.5, 1, 1.5, 2) high entropy alloy (HEA) coatings were prepared on the surface of 304 stainless steel (304 SS) by laser cladding technology. The effects of W addition on the microstructure, microhardness, friction and wear properties, and cavitation erosion (CE) resistance of the coatings were thoroughly studied. The results show that the phase structure of the CoCrFeNiMnWx HEA coatings exhibits FCC structure, and the microstructure is typical dendrite (DR) and inter-dendrite (ID) morphology. With the increase of W content, the average grain size of CoCrFeNiMnWx HEA coatings gradually decreases. The microhardness of CoCrFeNiMnWx HEA coatings increases first and then decreases due to the brittle cracking caused by the excessive addition of W element. The wear resistance of CoCrFeNiMnW1 HEA coating is the highest, and its wear rate is much lower than that of CoCrFeNiMn HEA coating without W addition. The wear mechanism of CoCrFeNiMnWx HEA coatings is mainly adhesive wear, abrasive wear and oxidation wear, and the fatigue wear mechanism appears on CoCrFeNiMnW2 HEA coating. In addition, CoCrFeNiMnW1 HEA coating displays the highest CE resistance, and its mass loss after CE in 3.5 wt%Nacl solution is lower than that of CoCrFeNiMn HEA coating. The appropriate addition of W element can effectively improve the resistance to wear and CE of CoCrFeNiMnWx HEA coatings, showing a great potential in improving the service lifespan of overflow parts in marine environment.