Synthesis of nano-laminated Ti3SiC2 from Ti–Ti5Si3 and CNTs

Nano-laminated Ti3SiC2 powders were prepared by heating mixture of Ti, Ti5Si3, carbon nanotube powders in argon at 1330 °C, the eutectic temperature of Ti and Ti5Si3. The nano-laminated morphology of Ti3SiC2 was revealed by the SEM and TEM observations. The high-resolution TEM image of cross-sectioned Ti3SiC2 sample shows a layer–interface–layer structure, where layer and interface contained pure Ti3SiC2 and TiC, respectively. Highly oriented Ti3SiC2 rods were also observed. A reaction mechanism was proposed containing three key stages: formation of Ti–Ti5Si3 eutectic liquid, emergence of TiC/CNT from reaction between carbon nanotube and eutectic liquid, and formation of Ti3SiC2 from TiC/CNT and eutectic liquid. As-synthesized Ti3SiC2 powders were pressure-less sintered to produce a compact with 93.3% of theroretical density and the nanolayers were preserved in the sintered sample. The measured Vickers hardness of sintered Ti3SiC2 sample was in the range of 3.1–4.5 GPa. After indentation, nano-scale deformations such as buckling, kink band, delamination, and cleavage fracture were observed. The nano-laminated morphology is believed to increase the damage tolerance and machinability.