Synthesis and mechanism of ternary carbide Ti₃AlC₂ by in situ hot pressing process in TiC–Ti–Al system

Abstract

Ti₃AlC₂ is successfully synthesised by in situ hot pressing process from 2TiC/xAl/Ti (x = 1, 1·2) raw powders. The phases and microstructure of the samples are identified by X-ray diffraction and scanning electron microscopy. It is found that aluminium content influences on the generating content of Ti₃AlC₂ significantly. High purity Ti₃AlC₂ can be obtained from a compacted cylinder composed of TiC–Ti–1·2Al at 1350°C for 2 h, and the purity of Ti₃AlC₂ is nearly 96·9 wt-%. The corresponding density and compressive strength are 3·93 g·cm⁻³ and 377·34 MPa respectively. Ti₃AlC₂ grain exhibits typical plate-like structure. When aluminium melts, a mass of Al atoms diffuse to Ti grain rapidly, and Ti–Al intermetallic compounds generate. Then, Ti–Al intermetallic compounds react with TiC to form Ti₃AlC₂ directly. Using TiC powders as the raw materials provides Ti₆C octahedra directly. At elevated temperature, a part of aluminium will evaporate and lose. This will result in that every two layers of Ti₆C octahedra are linked by aluminium planes directly and Ti₃AlC₂ can be formed.

Keywords:

• Ti₃AlC₂
• Layered carbide
• Synthesis
• Microstructure
• Strength

This work was supported by the National Natural Science Foundation of China (grant no. 51201094), the Natural Science Foundation of Shaanxi Province, China (grant no. 2012JM6018) and the Scientific Research Program of Shaanxi Provincial Education Department, China (grant no. 12JK0444).