Corrosion resistance and interfacial morphologies of a high Nb-containing TiAl alloy with and without thermal barrier coatings in molten salts

Abstract

In this work, corrosion behaviors of the high Nb-containing TiAl alloy with and without thermal barrier coatings are compared to illustrate the factors and corresponding mechanism determining stability of TiAl alloy in molten salts. The high Nb-containing TiAl alloy with coatings suffers a mass change of −7.50 mg/cm2 in the mixture salts of 75 wt.%Na2SO4+25 wt.%NaCl at 800°C for 50 h. The mass change of TiAl alloy with coatings is only 0.20 mg/cm2 and the thickness of corrosion region is 10 ± 1 μm. Dense ceramic coating retards molten salts diffusing to TiAl substrate and corrosion products suppress self-sustaining reaction of TiAl alloy.