Role of tantalum and nickel ion implantation on corrosion resistance properties of a Ti–Al–Zr alloy

Electrochemical behavior of Ti–Al–Zr implanted with nickel and tantalum ions and a co-implantation of them was investigated as a function of fluences. The polarization curves of the un-implanted and implanted Ti–Al–Zr were potentiodynamically measured in a hydrochloric acid solution. Electrochemical measurements revealed that nickel ion implantation significantly promoted the passivation of Ti–Al–Zr with an increase of fluence and the corrosion potentials resided in the passive region at fluences above 1 × 1016 ions/cm2. Tantalum ion implantation was effective in reducing the anodic current densities in the active and passive regions as fluences increased. On the other hand, the polarization curves of the co-implanted Ti–Al–Zr exhibited more stable passive behavior with low current densities. It was concluded that an excellent corrosion resistance of Ti–Al–Zr was achieved by complementary effects of nickel and tantalum ions co-implantation.