Effect of laser remelting on the microstructure and corrosion property of the arc-sprayed AlFeNbNi coatings

A thick Al-Fe-Nb-Ni coating with 46% volume fraction of amorphous/nanocrystalline structure was prepared on the low carbon steel substrate through low-cost arc spraying and then post processed by the laser remelting. The evolution of the coating microstructure, micro-hardness and corrosion behavior was comprehensively studied. The porosity of the as-sprayed coatings was as low as 2%. However, the incorporation of Nb element could not sufficiently suppress the long-range migration of atoms to generate fully glassy coatings. After laser remelting, metallurgical bonding was formed along the interface between the substrate and the coating with little substrate material dissolving into the coating. The coating became completely densified, which was dominant in remarkably improving the micro-hardness and the corrosion resistance. In addition, a passive film with the characteristic of p-type semiconductor was formed on the laser-remelted coating.