High-temperature oxidation behavior of TiB-reinforced IMI834 titanium matrix composites

This work compared the high-temperature oxidation behavior of an IMI834 titanium alloy (Basic) and a TiB-reinforced IMI834 titanium matrix composite (TMCs) at high-temperatures. The microstructures and oxidation products of these alloys were characterized by multi-scale characterization techniques after isothermal oxidation in air at 600, 700 and 800 °C for up to 200 h. The results show that the TiB reinforcement markedly refined the lamellar α microstructure, reducing the average α phase from 35.57 to 21.41 μm. Oxidation kinetics of both materials obey a parabolic rate law, while the composite exhibits consistently lower mass gains. The weight gain of IMI83 alloy after 200 h at 600, 700 and 800 °C were 0.222, 0.765 and 4.432 mg·cm⁻², compared with 0.192, 0.667 and 3.698 mg·cm⁻² for TMCs. At 600–700 °C, both alloys form dense, adherent scales, whereas at 800 °C severe spallation occurs on IMI834 but is much less pronounced on TMCs. TEM results reveal a continuous ∼2.27 μm duplex scale with Kirkendall pores but no through-thickness cracks on the composite. The improved oxidation resistance of TMCs is attributed to TiB promoting grain refinement, stress relaxation and enhanced scale adhesion, along with the outer SiO₂ layer., making TiB-reinforced IMI834 a promising candidate for elevated-temperature aerospace applications.