Microstructure and mechanical properties of Ni-Cr-Si-B-Fe composite coating fabricated through laser additive manufacturing

In this study, Ni-Cr-Si-B-Fe amorphous ribbon was coated on a mild steel substrate by laser additive manufacturing. The microstructure, phase composition, tribological behavior, and mechanical properties of the coating were systematically investigated. The results of X-ray diffraction showed that amorphous and crystalline phases coexisted in the coating and the fraction of the amorphous phase reaches up to 41%. According to SEM and TEM analyses, middle and surface regions of the coating were mainly consisted of eutectic structures. Columnar crystals existed in the bottom region of the coating near the coating-substrate interface. The matrix of the coating was mainly consisted of amorphous phase and the γ(Fe,Ni) solid solution phase. The composite coating exhibits excellent wear resistance and the hardness of the coating is about 2.4 times larger than that of the substrate, which is due to the existence of amorphous phase in the coating.