Surface characteristics, nano-indentation and corrosion behavior of Nb implanted NiTi alloy

The Electrochemical Behavior of the NiTi Alloy in Different Simulated Body Fluids

“…In both studies, the developed surface treatment improved the corrosion resistance of the NiTi. Even though the Nb alloy treatments developed lower current densities, it is important to notice that the corrosion densities found by Zhao et al 17 were also lower than the values obtained by Qiu et al 14 24 , studied the effects of different electrolytes (Ringer's, PBS and Hank's solution) on anticorrosion biometallic materials (SUS316L stainless steel, Co-Cr alloy and Ti-6Al-4V). The results indicate that the corrosion caused by the Ringer's solution is the strongest, followed by the PBS and Hank's solutions.…”

“…The authors state that E br is an indication to evaluate the susceptibility to pitting corrosion, thus, higher E br values means higher resistance to pitting corrosion 17 . They also found that the i corr values of the Nb-NiTi samples (5.89 × 10 -10 A/cm 2 ) were much lower than that of the untreated NiTi (1.07 × 10 -8 A/cm 2 ), suggesting a much slower eroding rate.…”

“…Despite the reports of some authors 3,4 of the lack of cytotoxicity of alloys, a study conducted by Fili 5 found that Ni-rich precipitates in NiTi osseous implants chemically passivized with HF, HNO 3 and H 2 O 300 days after implantation. A number of methodologies were proposed with the objective of creating a barrier that would block the release of nickel, resulting in an increased biocompatibility of the alloy and corrosion resistance: anodization 6,7 , heat treatments for superficial oxidation 8,9 , sputtering 10,11 , plasma electrolytic oxidation 12 , plasma immersion ion implantation 13 , hydroxiapatite/zirconia composite coating 14 , TiN coating 15 , sol-gel technology 16 metal vapor vaccum arc plasma source 17 . The correlation of the results from these studies in regards to the corrosion resistance is complex due to the different simulated body fluids that were used as electrolytes.…”

“…They also found that the breakdown potential (E br ) of the bare NiTi sample appeared at nearly 600 mV, while coated samples did not break at studied potentials 14 . Zhao et al 17 , on the other hand, used a commercial NiTi polished alloy samples, as well as samples polished by metal vapor vaccum arc plasma (MEVVA 100) with different parameters. The electrochemical tests were conducted in Hank's solution.…”

Crystal size induced reduction in thermal hysteresis of Ni-Ti-Nb shape memory thin films

“…[1][2][3][4][5][6] NiTibased shape memory films have been considered as one of the most promising candidates due to their high power output per volume, large actuation strain and high damping capacity. 7 For many micro-actuators, a narrow hysteresis is essential to improve the efficiency of actuation, whereas for energy storage devices a wide hysteresis is required.…”