Microstructure evolution and properties of CrCuFexNiTi high-entropy alloy coating by plasma cladding on Q235

Equimolar ratio CrCuFexNiTi high-entropy alloy (HEA) coating was prepared by plasma cladding on Q235 steel substrate. The microstructure of the HEA coating was analyzed by SEM and XRD, and its microhardness distribution was tested by a microhardness tester. Results showed that the HEA coating of CrCuFexNiTi without cracks and holes can be obtained through plasma cladding of elemental powders, namely, Cr, Cu, Fe, Ni, and Ti, on the Q235 steel substrate, with the coating thickness at approximately 2.5 mm. The microstructure of the coating showed a gradient distribution due to the dilution of the steel substrate and the large temperature gradient; moreover, it consisted of dendrite body-centered cubic structure and interdendrite face-centered cubic with some nano-precipitates in the middle of the coating, as well as Fe2Ti and γ-Fe-based solid solution with planar crystals at the interface between the coating and steel substrate. Furthermore, the entropy of the coating decreased from the surface to the interface. The microhardness of the coating was approximately 650-730 HV0.2, which was higher than that of the substrate at 130-200 HV0.2.