The Cyclic Oxidation and Hardness Characteristics of Thermally Exposed Titanium Prepared by Inductive Sintering-Assisted Powder Metallurgy

Abstract

The oxidation and hardness of thermally exposed titanium (Ti) prepared using inductive sintering-assisted powder metallurgy was evaluated through cyclic tests in air at 700−900 °C for 100 h (5 cycles). In general, the oxidation kinetics of the Ti samples followed the parabolic law and their oxidation rates increased with increasing oxidation temperatures. The rutile form of titanium dioxide (TiO2) was detected by X-ray diffraction in the oxide scales after oxidation at 700 °C and 900 °C. Furthermore, the TiO2 grain size and thickness were significantly influenced by an increase in the oxidation temperature. Lastly, the formation of rutile as a single-phase on the surface of oxidized Ti enhanced the hardness of the oxide scales, whereas the substrate had lower hardness values than the oxide scales due to diffusion of Ti atoms at the surface to form the TiO2 oxide scales.

Keywords

• titanium
• oxidation
• x-ray diffraction
• microstructure
• hardness