Synthesis of nano-laminated Ti 3SiC 2 from Ti–Ti 5Si 3 and CNTs

Abstract

Nano-laminated Ti 3SiC 2 powders were prepared by heating mixture of Ti, Ti 5Si 3, carbon nanotube powders in argon at 1330 °C, the eutectic temperature of Ti and Ti 5Si 3. The nano-laminated morphology of Ti 3SiC 2 was revealed by the SEM and TEM observations. The high-resolution TEM image of cross-sectioned Ti 3SiC 2 sample shows a layer–interface–layer structure, where layer and interface contained pure Ti 3SiC 2 and TiC, respectively. Highly oriented Ti 3SiC 2 rods were also observed. A reaction mechanism was proposed containing three key stages: formation of Ti–Ti 5Si 3 eutectic liquid, emergence of TiC/CNT from reaction between carbon nanotube and eutectic liquid, and formation of Ti 3SiC 2 from TiC/CNT and eutectic liquid. As-synthesized Ti 3SiC 2 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 Ti 3SiC 2 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.