A possible mechanism on synthesis of Ti3AlC2

A ternary carbide phase, namely Ti3AlC2,, was successfully synthesized by hot pressing (HP) and spark plasma sintering (SPS), respectively from the starting materials of Ti, Al4C3 and activated carbon. The soaking temperature of HP process was 1400 degreesC and the soaking time varied from 5 to 120 min. The soaking temperature of SPS process was 1300 degreesC and the soaking time varied from 1 to 7 min. Based on the results of X-ray diffractometer (XRD) and scanning electron microscopy (SEM), a possible mechanism was presented: firstly, at a certain sintering temperature, plenty of Ti6C octahedra are formed. Thereafter, two different intermediate products are obtained from the Ti6C octahedra depending on different soaking temperatures. One intermediate product is Ti(2)lC obtained by linking every layer of Ti6C octahedra together by an aluminum plane. The other is TiC obtained by linking the Ti6C octahedra together directly, Finally, the intermediate products transform to Ti3AlC2, as the soaking time is extended. TiAIC loses half of its aluminum layer, and then transforms to Ti3AlC2. Ti6C octahedra in TiC crystals are separated by aluminum planes and then TiC transforms to Ti3AlC2. (C) 2003 Elsevier Science B.V. All rights reserved.