Corrosion and passive film characteristics of 3D‐printed NiTi shape memory alloys in artificial saliva

Abstract Electrochemical tests and surface analysis were applied to study the corrosion behavior and passive film characteristics of three‐dimensional‐printed NiTi shape memory alloys fabricated by laser‐powder bed fusion (L‐PBF) in artificial saliva at 37 °C. The passivity of L‐PBF NiTi shows to be influenced by the process parameters and resulting morphological and physicochemical surface properties. The results show that the defects at the surface of L‐PBF NiTi can promote the passivation rate in the early stages of exposure but a slowly formed passive film shows the best corrosion protection. The thickness of the passive film is positively correlated with its corrosion protective performance. The L‐PBF NiTi alloy prepared at a linear energy density of 0.2 J·m −1 and volumetric energy density of 56 J·mm −3 shows the least defects and best corrosion protection. An outer Ti‐rich and inner Ni‐rich dense passive film could be also obtained showing higher corrosion resistance.