Effect of copper on the localized corrosion resistance of Ni–Ti shape memory alloy

An electrochemical study aiming at the evaluation of corrosion parameters using potentiodynamic and potentiostatic techniques (“scratch” and modified ASTM F746) was conducted in 0.9% NaCl on wires from equiatomic Ni–Ti and ternary Ni44Ti51Cu5 superelastic alloys with Ti90Mo10 as a reference material. The results obtained using potentiostatic tests, that simulate better the behavior of material in service conditions than potentiodynamic ones, indicate that both Ni–Ti and Ni–Ti–Cu wires exhibit low corrosion potentials (≈50–150 mV versus SCE) inferior to that of Ti–Mo alloy. The latter proved to be immune to localized corrosion attacks up to 800 mV.