Laser cladding Fe-based solid solution alloy coating with high corrosion resistance

Fe-based bulk metallic glasses are very attractive because of their excellent mechanical properties and corrosion resistance. Fe-Cr-Ni-Co-B amorphous alloy powders were cladded on a 304L stainless substrate by laser cladding technique. The microstructure and corrosion resistance properties were analyzed by XRD, OM, SEM and electrochemical measurement. The results show that the microstructure of the cladding coating is uniform and compact and there are no obvious cracks and stomata. In regions near the interface with the substrate, the microstructure exhibits planar crystalline and columnar crystalline solidification morphology. It is mainly strips-like dendritic crystalline in the coating, which exhibits various size and growth directions because of different composition and cooling rate in different region. The coatings mainly consist of Fe64Ni36 and (FeCrNi) solid solution phases. The coating microhardness shows a uniform distribution. The average hardness of the coating was 480HV0.2, which was about 2.5 times of the 304L stainless substrate. The coatings show excellent corrosion resistance with a higher Ecorr and lower icorr than the 304L stainless substrate.