Surface modification of TiNi alloy through tantalum immersion ion implantation

TiNi alloy samples were implanted with tantalum at a dose of 3.1 × 10¹⁷ N/cm² by means of Plasma immersion ion implantation (PIII) method. The surface morphology, chemical composition was characterized by Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The corrosion resistance, were determined by electrochemical methods in 0.9% NaCl solution at 37 °C. The results show that PIII treatment can increase the open-circuit corrosion potential (E_corr) and decrease the corrosion current density (I_corr). The pitting potential (E_br) for the tantalum implanted TiNi alloy is approximately 810 mV, more than 200 mV higher than that of the unimplanted one. The corrosion hystersis loop of the unimplanted TiNi alloy is larger than that of the implanted material, indicating improvement of the repassivating ability and pitting resistance of the TiNi alloys.