Effect of TiO2 addition on the properties of Ti3Si(Al)C2 based ceramics fabricated by reactive melt infiltration

In this paper, Ti3Si(Al)C2 based ceramics were fabricated by reactive melt infiltration (RMI) of TiC/TiO2 preforms with liquid silicon. The microstructure, phase composition, and mechanical properties of the Ti3Si(Al)C2 based ceramics have been investigated to understand the effect of phase composition of the preforms on the formation mechanisms of Ti3Si(Al)C2. The preforms with different content of TiO2 infiltrated at 1500 °C with liquid silicon for 1 h were composed of Ti3Si(Al)C2, Al2O3, TiC, TiSixAly and residual Al. The prior generated Al2O3 phases inhibited the dispersion of Ti3Si(Al)C2 phases, resulting in the drastically grain growth of Ti3Si(Al)C2. Subsequently, the microstructure with gradually increasing Ti3Si(Al)C2 grain size resulted in the decrease of the bending strength and fracture toughness of samples. When the content of TiO2 reached 20 wt%, the bending strength reached the maximum, 326.6 MPa. The fracture toughness attained the maximum, 4.3 MPa m1/2, when the content of TiO2 was 10 wt%.