Superior corrosion resistance-dependent laser energy density in (CoCrFeNi)95Nb5 high entropy alloy coating fabricated by laser cladding

(CoCrFeNi)(95)Nb-5 high entropy alloy (HEA) coatings were successfully fabricated on a substrate of Q235 steel by laser cladding technology. These (CoCrFeNi)(95)Nb-5 HEA coatings possess excellent properties, particularly corrosion resistance, which is clearly superior to that of some typical bulk HEA and common engineering alloys. In order to obtain appropriate laser cladding preparation process parameters, the effects of laser energy density on the microstructure, microhardness, and corrosion resistance of (CoCrFeNi)(95)Nb-5 HEA coating were closely studied. Results showed that as the laser energy density increases, precipitation of the Laves phase in (CoCrFeNi)(95)Nb-5 HEA coating gradually decreases, and diffusion of the Fe element in the substrate intensifies, affecting the integrity of the (CoCrFeNi)(95)Nb-5 HEA. This decreases the microhardness of (CoCrFeNi)(95)Nb-5 HEA coatings. Moreover, the relative content of Cr2O3, Cr(OH)(3), and Nb2O5 in the surface passive film of the coating decreases with increasing energy density, causing corrosion resistance to decrease. This study demonstrates the controllability of a high-performance HEA coating using laser cladding technology, which has significance for the laser cladding preparation of other CoCrFeNi-system HEA coatings.

Automated summary

By studying the effects of laser energy density on (CoCrFeNi)(95)Nb-5 high entropy alloy (HEA) coatings, it was found that increasing energy density leads to a decrease in Laves phase precipitation and intensification of Fe element diffusion in the substrate, resulting in reduced microhardness and corrosion resistance of the coating.