In Situ Processing and High‐Temperature Properties of Ti ₃ Si(Al)C ₂ /SiC Composites

Ti ₃ SiC ₂ has many salient properties including low density, high strength and modulus, damage tolerance at room temperature, good machinablity, and being resistant to thermal shock and oxidation below 1100°C. However, the low hardness and poor oxidation resistance above 1100°C limit the application of this material. The poor oxidation resistance at temperatures above 1100°C was because of the absence of protective layer in the scale and the presence of TiC impurity phase. TiC impurity could be eliminated by adding a small amount of Al to form Ti ₃ Si(Al)C ₂ solid solutions. Although the high‐temperature oxidation resistance was significantly improved for the Ti ₃ Si(Al)C ₂ solid solutions, the strength at high temperatures was lost. One important way to enhance the high‐temperature strength is to incorporate hard ceramic particles like SiC. In this article, we describe the in situ synthesis and simultaneous densification of Ti ₃ Si(Al)C ₂ /SiC composites using Ti, Si, Al, and graphite powders as the initial materials. The effect of SiC content on high‐temperature mechanical properties and oxidation resistance were investigated. The mechanisms for the improved high‐temperature properties are discussed.