Microstructure and Properties of Fe-Based Amorphous Alloy Coatings

Fe-based amorphous alloy coatings were successfully prepared by high velocity oxy-fuel (HVOF) thermal spraying process on the surface of Cr18Ni9Ti stainless steel. The microstructure, thermal stability and corrosion resistance of the coatings were investigated. The results showed that the coatings present high amorphous content, typical layered morphologies and homogenous and compact microstructures. It was observed that the splat predominantly consist of amorphous matrix containing a fraction of <em<α</em<-Fe solid solution phase dispersed 50~500nm in size with both agglomerate and dentritic crystal structures. The coatings revealed high thermal stability with crystallization temperature up to 879K. The coatings exhibited visible passive phenomena and superior corrosion resistance in 3.5% NaCl aqueous solution due to high values of passive region width and critical potential.