Electrochemical characteristic of TiNi shape memory alloy in artificial body fluids

In this work, the electrochemical characteristic of TiNi shape memory alloy (SMA) in Hank's solution was studied. The results indicated that low potential active dissolution of TiNi SMA occurred at a potential range of 150-250 mV during anodic polarizing. Its corrosion resistance was not affected by temperature, but was deeply affected by pH and Cl- ion concentration. Decreasing pH and improving Cl- ion concentration made the pitting broken potential (Eb) move toward negative and increased the sensitivity to pitting corrosion. Electro-probe microanalyzer and scanning electron microscope analysis showed that low potential active dissolution resulted in forming Ti2Ni precipitation phase in the hole, which enriched Ti and deficient Ni, became the sensitive position to pitting corrosion.