Preliminary electrochemical testing of some Zr-Ti alloys in 0.9% NaCl solution

The aim of this study is to investigate the corrosion behaviour of three ZrTi alloys (denoted with Zr5Ti, Zr25Ti, and Zr45Ti) in 0.9% NaCl solution. For comparison, cp-Ti was also investigated. In order to study the localized corrosion resistance and corrosion behavior at open circuit potential versus time, the open circuit potential (E-OC) was recorded, and the cyclic potentiodynamic polarization (CPP) and electrochemical impedance spectroscopy (EIS) were performed. Scanning electron microscopy (SEM) observations were made following the CPP tests. The Zr5Ti alloy was the most susceptible to localized corrosion. The Zr25Ti alloy presents a dangerous breakdown potential but have a sufficiently negative zero corrosion potential that the difference between them is sufficiently to provide a higher localized corrosion resistance in comparison with Zr5Ti. Among ZrTi alloys subjected to investigation, the Zr45Ti alloy had a much larger passive range in the polarization curve and was the most resistant to localized corrosion. For used test conditions, the localized corrosion was not found for the cp-Ti. The EIS tests show that both investigated ZrTi alloys and cp-Ti exhibit passivity after 168h immersion in 0.9% NaCl solution, at open circuit potential.