Comparative study of the oxidation with water vapor of pure titanium and of Ti--6Al--4V

The oxidation kinetics of pure titanium and of Ti-6Al-4V by water vapor were studied between 650 and 9500C and from 0.5 to 18 Torr. The results showed a marked similarity of the oxidation behavior for both the alloy and pure titanium. The rate curves had the same appearance. At low temperatures (below 7500C) they exhibited two stages. At high temperature the first of these stages was not observed. Scanning electron microscopy (SEM) and electron probe analyses of the scale showed that the structure of the scales was also similar over the temperature range 750 to 9000C; they consisted of two layers of rutile, and, in the case of the alloy, of a thin sublayer of alumina between the other two. Furthermore, SEM examination of the surface of oxidized specimens revealed the existence of whiskers