Study On The Fabriction And Properties Of Ti₃Si_1.2-xAl_xC₂ Solid Solution Materials

In this thesis, the Ti₃Si_y-xAl_xC_z (x=0～1.2, y≥1,z≤2) solid solution powder and Ti₃Si_y-xAl_xC_z solid solution bulk material have been prepared by pressureless synthesis and in-situ hot-pressing method, respectively, based on the detailedly investigation of the development and present status of the ternary layered compound MAX materials including Ti3SiC2 and Ti3AlC2. The physical properties and high-temperature oxidation resistance of bulk Ti₃Si_y-xAl_xC_z solid solution have also been tested and analyzed.The results show that raw materials'mole ratio, synthesis temperature and soaking time are crucial factors to acquire single Ti₃Si_1.2-xAl_xC_1.8 solid solution. Though Ti3Si1.2-xAlxCy phase solid solution has a kind of"312"phase crystal structure theoretically, the formation of the impurity phase TiC and Ti5Si3 can be restrained when the mole number of Si and Al is larger than 1, and C is less than 2. The synthesis temperature is between 1400～1600℃when x=0～1.2. However, it depends on different value of x. The soaking time of 5 min is suitable, and impurity phase TiC and Ti5Si3 will appear if extending soaking time.Ti₃Si_1.2-xAl_xC₂ solid solutions have a layered and plate-like structure, similar to that of the Ti₃SiC₂ and Ti₃AlC₂. Solutionzing of Al (or Si) takes place at the Si (or Al) layer of Ti₃SiC₂ (or Ti₃AlC₂). The results show that the bulk Ti₃Si_1.2-xAl_xC₂(x=0.2,0.3,0.4) solid solution prepared by in-situ hot-pressing have an excellent oxidation resistance. The oxidation layer is composed of TiO₂,Al₂O₃ and Al₂TiO₅. The thickness of the oxidation layer thins and the oxidation area decreases with the increase of the x value. That is, the oxidation resistance of Ti₃Si_1.2-xAl_xC₂ becomes better with increase in the x value.