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The effect of Al additions (5, 10, 15 and 20 at.%) on the corrosion behaviour of a 50 at.% Ti–50Ni alloy in Hank solution has been investigated by using potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS), electrochemical noise (EN) and linear polarization resistance (LPR) measurements. Microstructure evolution was observed from columnar grains to equiaxed grains in samples with low and high Al additions, respectively. All the different techniques indicated that with the addition of either 5 or 10 at.% Al not only decreases the uniform corrosion rate, but also the susceptibility to pitting corrosion. EIS technique has shown that the corrosion resistance of these alloys is due to a TiO2 layer with a duplex structure. Results have been explained in terms of the difference in microstructures for the different alloys. Keywords: TiNiAl alloy, Hank solution, Chloride corrosion