Intermediate phases in synthesis of Ti3SiC2 and Ti3Si(Al)C2 solid solutions from elemental powders

In this paper, we investigated the reaction path to synthesize Ti3SiC2 by the in situ hot pressing/solid–liquid reaction method. The effect of different content of Al addition on this process was also examined. Ti3SiC2 mainly formed from the reaction between Ti5Si3Cx, TiCx, TiSi2 and graphite at 1400–1500 °C. As an inescapable impurity in Ti3SiC2, TiCx was removed by addition of small amounts of Al. This was owing to the fact that the addition of a minor quantity of Al increased the amount of “effective TiCx” and relatively decreased that of “invalid TiCx”. Further increasing Al content, however, resulted in the presence of TiCx again in the final product. This was due to the fact when significant amounts of Al was added, the stoichiometric ratio of silicon and graphite has been deviated from that for Ti3SiC2. More Si and less graphite were needed to prepare a monolithic Ti3Si(Al)C2 solid solution with high Al content.