engleski

Microstructural Analysis of Ti-Ni Shape Memory Alloy after Corrosion Testing in 0.9 % NaCl Solution

In this work the corrosion behaviour of Ti-Ni (nitinol) shape memory alloy was studied using different electrochemical techniques including open circuit potential (EOC), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Samples made from nitinol alloy with diameter of 4 mm were used for microstructural and corrosion investigations. Testing solution was 0.9 % NaCl solution at pH=7.4, and temperature 37 °C. Microstructural analysis was performed by the optical and electron scanning electron microscopy (SEM) equipped with energy dispersive spectrometry (EDS). High values of the oxide film resistance (Rox) and the low value of corrosion current density (icorr) indicated high corrosion resistance of Ni-Ti alloy, but relatively low value of breakdown potential (Eb) indicates the possibility of development localised corrosion attack on the alloy surface. Size of pits was from 10 to 100 m and surface inclusions were initiation sites for the pitting corrosion.

nitinol; shape memory alloy; microstructure; corrosion

nije evidentirano