Synthesis and mechanism of ternary carbide Ti ₃ AlC ₂ by in situ hot pressing process in TiC–Ti–Al system

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.