Corrosion Behavior of TiNi Alloy Fabricated by Selective Laser Melting in Simulated Saliva

In this work, TiNi samples were prepared by Selective Laser Melting (SLM) technology, and the influence of microstructure, fluoride ion, and pH value on corrosion behavior in a saline environment was investigated and compared with TiNi alloy fabricated by traditional forging technology. The results indicated that the corrosion resistance of the SLM sample was slightly superior to that of the wrought sample in a saline environment due to the uniform and dense oxide film formed on the SLM sample surface. However, in acidic Artificial Saliva Solution (ASS) containing fluoride ions, the corrosion current density of the SLM sample increased from 9.85 × 10−2 to 13.9 μA/cm2 because of the presence of F−. Fluorine ions disrupted the passive film on the surface, and the Ti-F compound formed in the film, which deteriorated the corrosion resistance of the SLM sample. The increase in fluoride concentration and the decrease in pH value could accelerate the corrosion of the SLM sample.