Corrosion behavior of single- and poly-crystalline dual-phase TiAl-Ti3Al alloy in NaCl solution

To clarify the correlation of single-crystalline structure with corrosion performance in high-strength TiAl alloys, electrochemical and surface characterization was performed by comparing Ti-45Al-8Nb dual-phase single crystals with their polycrystalline counterparts in NaCl solution. Polarization curves show a lower corrosion rate and a higher pitting potential of similar to 280 mV for the dual-phase single crystals. Electrochemical impedance spectroscopy and potentiostatic polarization plots revealed a higher impedance of the charge transfer through the compact passive film. Surface composition analysis indicated a compact film with more content of Nb, as twice as that in the film on the polycrystals. Our results reflect that the dual-phase Ti-45Al-8Nb single crystals possess a higher corrosion resistance in NaCl solution, compared with their polycrystalline counterpart, arising from a more homogeneous microstructure and composition distribution.

Automated summary

To investigate the correlation between single-crystalline structure and corrosion performance in high-strength TiAl alloys, the electrochemical and surface characterization of Ti-45Al-8Nb dual-phase single crystals and polycrystalline counterparts were compared in NaCl solution. The results showed that the dual-phase single crystals exhibited a lower corrosion rate, higher pitting potential, and a more compact passive film with a higher impedance of charge transfer compared to the polycrystals. This enhanced corrosion resistance can be attributed to the more homogeneous microstructure and composition distribution in the dual-phase single crystals.