The results of investigation on the oxidation behavior of orthorhombic Ti2AlNb alloy with Al2O3 and AlCrN coating are presented. Oxidation was carried out in static air atmosphere at 700 and 800°C and in 9% O2+0.2% HCl+0.08% SO2+N2 atmosphere at a temperature of 700–750°C. Investigation of the material structure of the specimen and chemical composition of oxidation products was performed. The surfaces were characterized using SEM (scanning electron microscopy) techniques. It was determined that the alloy shows a sufficient high-temperature corrosion resistance only at 700°C. At both temperatures, the coated samples exhibited reduced mass gain compared to uncoated alloy. At 700°C rather insignificant differences were observed; however, at the temperature of 800°C, the deposited coatings strongly limit the mass gain of the test material.
Part of the book: High Temperature Corrosion