Nickel–titanium shape memory alloys (NiTi) are relatively special group of metallic biomaterials. Extraordinary properties of NiTi shape memory alloys are widely employed in medical applications (orthopedics, orthodontics, urology, etc.) owing to their desirable properties, such as superelasticity, relatively low modulus and good corrosion resistance. Furthermore, toxicity and carcinogenesis of Ni ions released from NiTi alloy are very interesting topics. Therefore, it is necessary to produce a surface barrier to impede the out-diffusion of Ni ions from the materials. Inductively coupled radio frequency plasma (ICRFP) was proposed to modify the surface properties. All nitride samples surfaces exhibit outstanding corrosion and Ni out-diffusion resistance. The microstructure of produced layer was analysed by X-ray diffraction. The enhancement of corrosion resistance proved that TiN layers as well as the intermediate Ti2N phase effectively protect surface of the NiTi alloys against nickel ion release.

Keywords: Inductively coupled radio frequency plasma (ICRFP), biocompatibility, corrosion resistance- Nickel–titanium (NiTi), shape memory alloys.