Effects on synthesis of Ti_2AlC/Ti_3AlC_2 doped with Si from elemental powders by hot pressing and theoretical analysis

Ti2AlC/Ti3AlC2 bulk material were synthesized by hot pressing using elemental powder mixture of Ti,Al,Si and active carbon whose molar ratios were 2.0Ti/1.1Al/1.0C,0.1mol Al replaced by Si and 0.2mol Al replaced by Si.Through calculating according to models of Ti2AlC,Ti3AlC2 and Si-doped,even net charge of the atoms and even covalent bond orders were calculated respectively.Results show that Ti2AlC material with little Ti3AlC2 could be synthesized by hot pressing elemental powder mixture of 2.0Ti/1.1Al/1.0C at 1450℃ for 60min.On the other hand,the effect of Si was very obvious when 0.2mol Al replaced by Si and it did not improve the synthesis of Ti2AlC but Ti3AlC2 at the same temperature.Moreover,experimental results were explained by the effect of Si doped on net charge of the atoms and covalent bond orders.