Effect of Si on the Oxidation Behaviors of Ti₃Al_1−xSi_xC₂ at 1000 °C

In this work, Ti₃Al_1−xSi_xC₂ (x=0, 0.2, 0.4, and 0.6) with Al/Si solid solution structure are synthesized, and the effects of Si on their oxidation behaviors at 1000 °C are evaluated. The addition of Si not only contributes to the formation of Ti₅Si₃ impurity but also affects the composition of the oxide scale. Particularly, the incorporation of Si in the TiO₂ lattice is demonstrated, which alters the formation energy of the (110) plane in TiO₂, thus leading to the preferential growth of Si-doped TiO₂ to dendritic congeries. Moreover, the Si addition is believed to affect mass transportation during the oxidation process, which accelerates the formation of a continuous Al₂O₃ layer in the oxide scale. With an optimized Si content, the oxidation of Ti₃Al_1−xSi_xC₂ is restrained. However, with excess Si content, the continuity of the resulting Al₂O₃ layer is destroyed, thus the oxidation rate rises again.