Microstructural evolution and high-temperature oxidation mechanisms of a Ti-Mo-Si composite

The objective of this study was to improve the safety working temperature of Ti alloy by developing a new Ti-Mo-Si composite. After SPS sintering, the Ti-Mo-Si composite in situ formed beta-Ti, alpha-Ti, Ti5Si3, and TiC phases. During oxidation, the composite followed parabolic oxidation kinetics. A dense multi-layered structured oxide layer that consists of TiO2(I)/mixed SiO2 and TiO2(II) was formed on the surface of the matrix with a grain size that gradually decreased after 120 h of oxidation. The amorphous SiO2 sealed the clearances between the TiO2 grains, which provided the oxide layer with a self-healing ability. This type of oxide layer caused an increase in the antioxidant temperature of the matrix to 900 degrees C for 120 h.