Surface properties and mechanism of corrosion resistance enhancement in a high temperature nitrogen ion implanted medical grade Ti

The surface characteristics and mechanism of corrosion resistance enhancement in a high temperature nitrogen ion implanted medical grade titanium (Ti) were investigated. Implantations were conducted at constant energy (80 keV) and a dose of 2.1 × 10+18 Ion cm−2 at room temperature (~300 K) and at elevated temperatures (473 K, 673 K, and 873 K). The nitride phase formation on the implanted samples was characterized using grazing incidence X-ray diffraction (GI-XRD), and electrochemical polarization tests were carried out in Ringer's solution as a simulated body fluid. A significantly enhanced corrosion resistance was achieved for the titanium sample implanted at 473 K, attributed to the improved protective performance of the nitride layer due to the formation of a uniform and dense nitride phase. Analyzed via field emission scanning electron microscopy (FE-SEM), the corroded surface of the room temperature implanted sample exhibited delaminations, while the 473 K sample remained relatively intact. The decreased corrosion resistance of the 673 K and 873 K samples was linked to surface non-uniformity and phase transition from α to β-Ti. The enhanced corrosion resistance mechanism for the 473 K implanted sample was further explored using Multi-Beam Focused Ion Beam-Scanning Electron Microscope (FIB-SEM) and EDS mapping.