Inter-phase selective corrosion of γ-TiAl alloy in molten salt environment at high temperature

Hot corrosion behavior of Ti-48Al-2Cr-2Nb alloy in molten salt environment of 75% Na2SO4 and 25% NaCl (mass fraction) at 800 °C was studied using oxidation kinetics analysis, scanning electron microscopy, X-ray energy dispersive and X-ray diffraction analyses. The inter-phase selective corrosion, which caused the corrosion pits initiated from lamellar interfaces and the preferential corrosion of α2 phases, was observed during the hot corrosion of the alloy. The common controls of thermodynamic and kinetics in corrosion reactions with fluxing and active oxidation process were considered the essential hot corrosion mechanisms of the alloy. Moreover, lamellar refinement was proved to be an effective way to mitigate the inter-phase selective corrosion of the alloy in molten salts.