Effect of nanocrystallization on hot corrosion resistance of Ti-48Al-8Cr-2Ag alloy in molten salts

Magnetron-sputter deposition was used to produce Ti-48Al-8Cr-2Ag coating on a cast alloy substrate with the same composition. Hot corrosion was carried out in molten (Na,K)2SO4 and Na2SO4+NaCl at 900 °C. The sputtered nanocrystalline coating shows much better hot-corrosion resistance in molten (Na,K)2SO4 as a result of the formation of a continuous and compact Al2O3 scale. The nanocrystallization of TiAlCrAg alloy prolongs the incubation of breakaway corrosion and improves the hot-corrosion resistance of TiAlCrAg alloy in molten Na2SO4+NaCl. The relevant corrosion mechanism was discussed.