Synthesis of single-phase Ti3SiC2 from coarse elemental powders and the effects of excess Al

Abstract Single-phase Ti 3 SiC 2 was successfully prepared by using a new ratio of raw materials and coarse starting powder (~70 µm). To reveal the mechanism of aluminum acting as a sintering aid in the reaction synthesis of single-phase Ti 3 SiC 2 , mixtures of 3Ti/1.5Si/1.9C/ x Al ( x  = 0–0.6) were sintered to synthesize Ti 3 SiC 2 through pressureless sintering. The results showed that the molten Al reacted with oxygen to act as a deoxidizer and promoted the nucleation of Ti 3 SiC 2 during the sintering process. An optimal amount of Al can accelerate the reaction between the TiC and Ti 5 Si 3 intermediate phases, while excessive Al will hinder diffusion and reduce the purity of Ti 3 SiC 2 by forming Al 2 O 3 on the grain boundaries. The optimum experimental parameters for the synthesis of single-phase Ti 3 SiC 2 were determined as a Ti/Si/C/Al molar ratio of 3/1.5/1.9/0.5, holding at 1400 °C for 2 h.