Synthesis of a Bulk TiSiC MAX Phase by Reduction of TiO with SiC.

The bulk MAX phase TiSiC was first synthesized with a yield of 86% by a long-time thermal treatment of TiO and SiC powder mixture with a molar ratio of 2:3 at 1600 °C under vacuum conditions. It was found that the appearance of TiSiC was preceded by the formation of TiC and TiSiC as a result of the following reactions: (1) combined carbothermic and silicothermic reduction of TiO to TiC accompanied by evolution of SiO and CO gases; (2) silicidation of TiC with gaseous SiO, leading to the growth of TiSiC. It was suggested that, apart from TiC and TiSiC solids, sublimed gaseous species such as Ti, Si, SiC, SiC, etc., could take part in the TiSiC formation that occurred in the next stage. The crystal structure of synthesized TiSiC was refined by X-ray diffraction Rietveld analysis and confirmed by high-resolution scanning transmission electron microscopy. The measured structural characteristics of bulk TiSiC are in good agreement with those predicted by ab initio calculations reported in the literature.