In this study, NiTi intermetallic coatings were deposited on 316L stainless steel and 1045 steel using high velocity oxy-fuel (HVOF) and air plasma spraying (APS) processes. In this regard, amorphous/nanocrystalline Ni–Ti powders produced by low energy mechanical alloying were used as feedstock. According to characterization results, the phase composition of both optimum HVOF and APS coatings consisted of NiTi, Ni 4 Ti 3 , Ni and NiTiO 3 . On the other hand, TiO phase were found only in optimum APS coating. The microstructural evaluations showed that HVOF NiTi coating was less-oxidized than APS one. In addition, no visible microcracks were detected in HVOF coating, while the microcracks were evidently observed in APS one. The result showed that corrosion resistance of HVOF coating on 1045 steel is better than that of APS one. Here, the corrosion performance of HVOF coating improved at long times while delamination of APS coating was observed. It was indicated that the passive behavior and corrosion performance of the HVOF coating on 316L stainless steel were far better than those of the APS coating. The study also showed that the solution had penetrated through the coating defects and caused interior corrosion of APS coating, while the HVOF coating was immune from interior corrosion attack and consequently exhibited a good passive behavior during long-term immersion. Keywords: Atmospheric plasma spraying, High velocity oxy-fuel spraying, 316L stainless steel, Ni-Ti alloys, Intermetallic coatings, Electrochemical impedance spectroscopy
