Isothermal oxidation of Ti–6Al–7Nb alloy

• The oxidation behaviours of Ti–6Al–7Nb alloy has been described.
• The predominant phase of the scale was TiO2 in the form of rutile.
• The continuity of the scale it increased with temperature.

The properties of Ti–6Al–7Nb alloy oxidation in the temperature range from 500 to 800 °C, in various time periods between 20 min and 72 h, were examined. The rate of oxidation at temperatures of 600, 700 and 800 °C, determined on the basis of the weight gain, was described by a parabolic equation. The obtained oxidation activation energy value was 170 kJ/mol. In addition to oxidation kinetics, the phase composition and the surface morphology of the formed scale were determined. The phase composition of the oxide layers was complex and it changed with the oxidation temperature. At a higher temperature titanium oxide TiO2 in the form of rutile was the predominant phase. The continuity of the scale and the size of forming it oxide particles were increasing with temperature.