Kinetics of oxidation of Fe-bearing powder metallurgy Ti alloys

The aim of this work is to study the kinetics of oxidation of new Fe-bearing titanium alloys produced by the innovative powder metallurgy route of induction sintering. The characterisation of the phases formed, surface topography, mass gain, microhardness and oxide layer thickness of the Fe-bearing titanium alloys oxidised at 700 °C in air reveals that a non-uniform oxidation layer composed of either TiO₂ particles or vertically-grown TiO₂ micro-pillars at short and long oxidation times, respectively, is formed. This results in a continuous increase of the total mass gain and microhardness with the oxidation time. It is found that the oxidation mechanism is controlled by the inwards diffusion of oxygen and the outwards diffusion of Ti and the presence of the alloying elements does not significantly affect the oxidation response. The study is complemented with the identification of a relationship useful to predict the degree of oxidation.