Synthesis and mechanism of ternary carbide Ti3AlC2 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 degrees 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.