Influence of intermetallics evolution on the electrochemical behavior of NiTiCe ternary alloy through aging

Nickel-Titanium (NiTi) alloys have garnered significant attention in biomedical applications due to their exceptional corrosion resistance, excellent biocompatibility, and superior mechanical properties. However, limited research has been conducted on NiTi ternary alloys, particularly those incorporating rare earth elements, which hold potential for enhancing their performance. This study investigates the electrochemical behavior and properties of NiTiCe ternary alloys, aiming to assess the impact of heat treatment on the microstructure, corrosion resistance, and mechanical properties of the NiTiCe alloy. Various characterization techniques, including electrochemical testing and hardness measurements, were employed to evaluate the material's performance. The results demonstrate a notable improvement in corrosion resistance, with the formation of NiCe intermetallics reducing the depletion of Nickel. Specifically, the corrosion rate decreased by 95%, from 1.71 mpy (sintered-only material) to 0.09 mpy (3-hr aged material). Furthermore, hardness increased by 57.9%, from 38.1 HRC to 60.1 HRC, due to the formation of NiTi intermetallics in the austenitic matrix after aging at 500 °C. The formation of Ni 4 Ti 3 was also observed to hinder the martensitic transformation, further contributing to the increased hardness. These findings suggest that the incorporation of Ce and heat treatment can significantly enhance the mechanical and electrochemical properties of NiTi alloys, offering potential for broader biomedical applications.