Synthesis Fe-Ni protective coating on 45 steel by laser remelting nickel pre-coating dopped with Fe-based amorphous powders

Abstract Fe-based amorphous powders were added to a nickel coating on 45 steel as a precoating during the electroplating process, and then this precoating underwent laser remelting. The Fe-Ni amorphous/nanocrystalline composite coating was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nanoindentation, dry sliding tests and electrochemical techniques. Results showed that the amorphous phase and γ(Fe,Ni) phase were formed during the laser cladding process. The coating was metallurgically bonded to the substrate and could be divided into three zones: the bottom dendrite-phase zone, the upper amorphous-phase zone, and the crystalline zone. In addition, it was further confirmed by TEM that the coating contained amorphous phase and γ(Fe,Ni) nanocrystalline phase. The maximum hardness of the coating was 12.59 GPa, which is four times more than that of the substrate. The maximum elastic modulus of the coating was 233.47 GPa, which is 34.07 GPa higher than that of the substrate. The coating presented good wear resistance with a friction coefficient of 0.09 and a wear mass loss of 0.79 mg. Moreover, the coating exhibited excellent corrosion resistance in NaCl solution with an Ecorr of −171.8 mV, Icorr of 0.1366 μA·cm−2 and polarization resistance of 75,688.12 Ω·cm2, which is much better than that of the substrate.