Oxidation exposures were carried out to assess the oxidation resistance of Ti-48Al-xAg (x=l and 3 at.%) coatings at 800°C in air with different H{sub}2O contents for 100 hours. The coatings containing 3.0 at.% Ag have been proved to be resistant against oxidation attacks in wet air. It has been found that both Ag content in the coating and H{sub}2O content in the atmosphere have substantial influence on the oxidation behavior. For coatings with 1.0 at.% Ag, TiO{sub}2 and mixed TiO{sub}2+Al{sub}2O{sub}3 were formed in 30.8 vol.%H{sub}20, while TiO{sub}2, the mixture of TiO{sub}2+Al{sub}2O{sub}3 and continuous A1{sub}2O{sub}3 layers were formed in 9.0 vol.%H{sub}2O. For the coatings containing 3.0 at.% Ag. higher H{sub}2O content (30.8 vol.%) resulted in the formation of duplex oxide scale with a mixture of TiO{sub}2+Al{sub}2O{sub}3 on top of continuous Al{sub}2O{sub}3, while continuous single A1{sub}2O{sub}3 layer was formed in lower H{sub}2O content (9.0 vol.%). The effect of H{sub}2O vapor on the oxidation behavior was explained by the interaction of H{sub}2O and TiO{sub}2, or the rapid and anisotropic diffusion of hydrogen in TiO{sub}2 during oxidation.
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