理论分析
(1. 武汉理工大学 理学院，武汉 430070;
2. 武汉理工大学 材料复合新技术国家重点实验室，武汉 430070)
摘 要: 以Ti粉、Al粉、活性炭和Si粉为原料，采用放电等离子工艺分别以摩尔比为2.0Ti/1.1Al/1.0C、2.0Ti/1.0Al/0.1Si/1.0C、2.0Ti/1.0Al/0.2Si/1.0C、2.0Ti/0.9Al/0.2Si/1.0C和2.0Ti/1.0Al/0.3Si/1.0C，在1 200 ℃合成了Ti2AlC/Ti3AlC2块体材料。通过合成试样的X射线衍射谱，确定了放电等离子合成试样的物相组成，并用扫描电镜结合能谱仪观察了合成试样的显微结构和微区成分。结果表明：以2.0Ti/1.1Al/1.0C为原料放电等离子合成了层状结构明显的Ti2AlC材料；掺Si后所有试样都由Ti2AlC、Ti3AlC2和Ti3SiC2 3种物相组成；当掺Si量逐渐增大，即Al与Si的量比减小时，试样中Ti3AlC2和Ti3SiC2的含量增加，而Ti2AlC的含量降低，同时颗粒得到细化。应用量子化学计算结果解释了掺Si后不利于Ti2AlC的生成，而有利于Ti3AlC2的生成机理，说明了掺Si后固溶体的产生过程。
关键字: 硅掺杂；放电等离子烧结；Ti2AlC/Ti3AlC2；理论分析
doping by spark plasmasintering and
theoretical analysis
（1. School of Science, Wuhan University of Technology,Wuhan 430070, China;
2. State Key Laboratory of Advanced Technology forMaterials Synthesis and Processing,Wuhan University of Technology,
Wuhan 430070, China）
Abstract:Ti2AlC/Ti3AlC2 bulk material was synthesized by spark plasma sintering (SPS) at 1 200 ℃ using elemental powder mixture of Ti, Al, active carbon and Si whose molar ratios were 2.0Ti/1.1Al/1.0C, 2.0Ti/1.0Al/0.1Si/1.0C, 2.0Ti/1.0Al/0.2Si/1.0C, 2.0Ti/0.9Al/0.2Si/1.0C and 2.0Ti/1.0Al/0.3Si/1.0C. X-ray diffractometry was used to determine the phase composition, and scanning electron microscopy with energy-dispersive spectroscopy was observed to investigate the microstructure of samples and components in selected area respectively. The results show that Ti2AlC bulk material which has obvious layered structure can be synthesized by SPS from 2.0Ti/1.1Al/1.0C at 1 200 ℃. On the other hand, the samples Si doping are made of Ti2AlC, Ti3AlC2 and Ti3SiC2. When the amount of Si doping increases and molar ratio of Al to Si decreases, the amount of Ti3AlC2 and Ti3SiC2 increases while Ti2AlC decreases. At the same time, the size of layered crystal grain becomes refined. The mechanism that Si doping is not helpful to form Ti2AlC is explained according to the results of quantum chemistry calculation. The formation of Si solid solution after Si doping is illuminated.
Key words: Si doping; spark plasma sintering; Ti2AlC/Ti3AlC2; theoretical analysis
