To improve implant integration with body tissues and accelerate healing, plasma immersion ion implantation (PIII) is attractive because it can improve the corrosion resistance, hardness, and biocompatibility of materials surface while preserving the favorable characteristics of the bulk materials[1-3]. The technique is especially suitable for biomedical implants with a complex geometry because of its intrinsic non-line-of-sight characteristic [1-3]. NiTi alloys have good biocompatibility [2-4] but the poor corrosion resistance may lead to increased cytotoxicity since Ni may be released from the substratecausing toxic reactions in humans [3-4]. In this work, carbon plasma immersion ion implantation (C-PIII) is used to modify the surface of NiTi alloys to improve the corrosion behavior and electrochemical impedance spectroscopy (EIS) is employed to investigate the corrosion behavior and the underlying corrosion resistance mechanism.
