Cu assisted improvement of wear and corrosion resistance in FeCoNiAl high-entropy intermetallic coating by laser cladding

Abstract

High-entropy intermetallic compounds (HEIs) with high strength and outstanding wear resistance are possibly the desirable coating materials. In this present work, A FeCoNiAl HEI composition originated from the multi-component substitution of A site in L12-Ni3Al was designed. Next, the HEI coating was achieved using laser cladding. The Cu atoms were incorporated into the HEI coatings to investigate their effects on the phase structure, cracking, and properties of HEI coatings. The results show that the FeCoNiAl HEI coating comprises a sole BCC phase. Adding Cu atoms less than 4.76 at.% does not alter the phase structures. Besides, the study found that as x exceeded 0.3, many tiny rod-like secondary precipitates are generated in the B2 matrix. The study also found that the FeCoNiAl HEI coating hardness at approximately 550 HV0.2 is twice that of Ni3Al coating. The secondary precipitates in the Cu-rich HEI coatings enhance the hardness to about 700 HV0.2. Accordingly, the wear resistance shows a similar tendency to the microhardness. Moreover, the Cu0.4 HEI coating exhibited the lowest friction coefficient (∼0.381) and the narrowest wear scar. In addition, the cracking behavior transforms from transgranular to intergranular cracking due to increased Cu content resulting in decreased cracking sensitivity. The study found that the corrosion resistance of Cux HEI coatings is more defective than those of Ni3Al coating. The Cu atoms effectively decrease the passivation current density of Cux HEI coatings. The above results provide a novel thought for the development of high-performance coatings.