The difference of synthesis mechanism between Ti_3SiC_2 and Ti_3AlC_2 prepared from Ti/M/C (M=A1 or Si) elemental powders by SHS technique

摘要

Ti_3MC_2 ternary compounds (M=A1 or Si) have been prepared by a self-propagating high-temperature synthesis (SHS). The difference of synthesis mechanism between Ti_3SiC_2 and Ti_3AlC_2 using Ti/M/C(M=A1 or Si) powder mixtures and some TiC or some intermetallic compounds as raw materials has been investigated. The phase composition and the relative content of Ti_3MC_2 materials in the final products were determined by X-ray diffraction (XRD). The results show that TiC and intermetallic compounds of TiAl have played an important role in synthesis of Ti_3AlC_2. The relative content of Ti_3AlC_2 in the products increases with increased addition of TiC or TiAl in the raw materials. In contrast, the relative content of Ti_3SiC_2 in the products changes less with increasing of TiSi_2 content, even decreases with increasing of TiC content in the raw materials. The difference of synthesis mechanism between them has been explained thcrmodynamically.