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

In this work, Ti3Al1-xSixC2 (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 degrees 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 Ti3Al1-xSixC2 is restrained. However, with excess Si content, the continuity of the resulting Al2O3 layer is destroyed, thus the oxidation rate rises again.