Effects of laser re-melting and annealing on microstructure, mechanical property and corrosion resistance of Fe-based amorphous/crystalline composite coating

In order to develop a new coating to resist the corrosion of the carbon steel, a Fe-based amorphous/crystalline composite coatings were realized by an Nd: YAG pulse laser and then they were separately re-melted by the same laser and annealed for 2 h at 800 °C. The microstructure, mechanical and anticorrosion properties of the as-prepared coatings were studied by various testing and analyzing method. The crystalline structure, deformed crystalline structure and amorphous structure were found in the original coating and the re-melted coating, while the latter displayed a higher content of amorphous structure than the former. As a comparison, the annealed coating mainly showed crystalline structure. Moreover, three types of coatings owned the similar Vickers hardness, while pop-in events were observed at deformed crystalline structure and amorphous structure during nanoindentation tests. Additionally, the re-melted coating exhibited a higher corrosion resistance than the other two coatings and 316L stainless steel. The above research revealed that laser re-melting was beneficial to improve the microstructure and enhanced the properties of the Fe-based amorphous/crystalline composite coating.