Microstructure and Mechanical Properties of Fe-based Amorphous Composite Coatings Reinforced by Stainless Steel Powders

In this study, a few Fe-based amorphous matrix composite coatings reinforced with various portions (4, 8 and 16 vol.%) of 316L stainless steel powders have been successfully produced through high velocity oxy-fuel (HVOF) spraying. The microstructure of the composite coatings was systematically characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The main structure of composite coatings remained amorphous while 316L stainless steel splats were distributed homogeneously in the amorphous matrix and well connected with surrounding amorphous phase. Bonding strength of coatings to the substrate was determined by "pull-off" tensile tests. The results revealed that the 316L stainless steel phase effectively improved the bonding strength of amorphous coatings, which is mainly contributed by the strong metallurgical bonding between stainless steel and amorphous splats. The addition of 316L stainless steel also enhanced the ductility and fracture resistance of the coatings due to the ductile stainless steel phases, which can arrest crack propagation and increase energy dissipation.