Microstructures and corrosion resistance of Fe-based amorphous/nanocrystalline coating fabricated by laser cladding

Fe-based amorphous/nanocrystalline coatings were fabricated with industrial FeCoCrMoCBY alloy plate on the mild steel surface by laser cladding. The formation, microstructure were investigated with optical microscope (OM), transmission electron microscope (TEM) and X-ray diffraction (XRD). The results indicate that few pore and just only some cracks are formed in all of the coatings. With increase of heat input, some crystal phases of a-Fe, Fe3C and Fe23C6 are precipitated gradually in the coating layers, and the microhardness of the coating layers decreases gradually, while the maximum microhardness is up to 1300 Hv near to 5 times high than that of substrate. Though the passive currents of coating layers increase with increase of heat input, all of coating layers exhibit low corrosion current density, passive current density and wide passive region, which means all of coating layers present excellent corrosion resistance, even more superiors than that of 316L stainless steel in NaCl solution. (C) 2017 Elsevier B.V. All rights reserved.