| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1600779 | Intermetallics | 2011 | 8 Pages |
The corrosion behavior of Ni3Al-based intermetallic alloys in a 0.5 M NaOH solution was studied at 25 °C. The open circuit potential, cathodic and anodic potentiodynamic polarization, Tafel plots and linear polarization resistance measurements were used to characterize the corrosion behavior. For the Ni3Al(B, Zr) alloy, potentiodynamic polarization curves showed a wide passive region that can be found between about −0.220 VSCE and 0.520 VSCE. On the other hand, a narrow passive region, in the range of potentials from about −0.180 VSCE to 0.180 VSCE, was observed for the Ni3Al(B, Zr, Cr, Mo) alloy. Chromium, as an alloying element in the Ni3Al(B, Zr, Cr, Mo) alloy, contributes to transpassive dissolution of the passive film at much lower anodic potentials and remarkably reduces the passivation region. The experiments indicated also that damaged passive films on alloys repairs itself and pits do not initiate. The surface of both alloys and passive films possess extremely high corrosion resistance in a studied solution. However, Tafel and linear polarization tests revealed that freshly exposed surfaces of the Ni3Al(B, Zr) alloy exhibited better corrosion resistances than the Ni3Al(B, Zr, Cr, Mo) alloy. Both methods, used for the determination of corrosion rates gave very similar results. The calculated corrosion rates are about 2.8 ·10−3 and 6.0·10−3 mm year−1 for the Ni3Al(B, Zr) alloy and B, respectively.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Corrosion behavior of Ni3Al-based intermetallics in 0.5 M NaOH. ► Passive films formed in the studied solution are stable and compact. ► Corrosion rate of Ni3Al-based intermetallics is about 0.006 mm year−1. ► Corrosion resistance of the Ni3Al-based alloy is not enhanced by Mo and Cr presence.
