Hot corrosion behaviour of (γ + α2)-Ti-46Al-8Nb (at.%) and α-Ti-6Al-1Mn (at.%) alloys

- Fast degradation of Ti-46Al-8Nb and Ti-6Al-1Mn in hot salt environment.
- Large material loss, high thickness of scale, scale spallation.
- Corrosion resistance of Ti-46Al-8Nb better than of Ti-6Al-1Mn.
- NaCl as the most aggressive hot salt component.

Hot corrosion behaviour of (γ + α2) Ti-46Al-8Nb (at.%) and α-Ti-6Al-1 Mn (at.%) alloys was investigated in thermal cyclic conditions at 700, 800 and 900 °C. The samples were intentionally contaminated with Na2SO4 or NaCl or with a mixture of these. The corrosion rate was evaluated on the basis of mass change measurements. Degradation of materials was examined at the surface and on cross-sections by scanning electron microscopy (SEM). The chemical and phase composition of scale was determined with energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). It has been demonstrated that both (γ+α2)-Ti-46Al-8Nb (at.%) and α-Ti-6Al-1Mn (at.%) are not resistant to hot corrosion. Remarkable mass changes of samples accompanied by intensive scale spallation was observed especially with sodium chloride deposit.

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