Al-Ti-C体系自蔓延高温合成TiC的形态演变

利用真空自蔓延加热-加压装置,采用X射线衍射(X-ray diffraction,XRD)、扫描电镜(scanning electron microscope,SEM)及能谱(energy dispersive spectrum,EDS)等分析测试手段,研究了Al含量、粉末粒度及C/Ti(原子比,下同)对Al-Ti-C体系自蔓延点燃温度、产物相组成及TiC形态的影响。结果表明,Al含量对TiC的尺寸影响最大,随着Al含量由20%(质量分数,下同)增加到50%时,TiC颗粒的尺寸由3～5μm减小到0.7～0.8μm。C粉粒度和C/Ti对TiC的形貌影响最大,当C粉粒度小于75μm或C/Ti≥1时,TiC的形貌为近球形;然而当C粉粒度不小于75μm或C/Ti1时,TiC的形貌为八面体。

Morphology evolution of TiC particulates formed by self-propagating high-temperature synthesis in Al-Ti-C system

The effect of Al content,size of powders and reactant C/Ti atomic ratios on ignition temperatures,phase constituents of the self-propagating high-temperature synthesis（SHS） products and morphology of TiC particulates formed by SHS in an Al-Ti-C system was investigated using the heat pressing vacuum apparatus by X-ray diffraction（XRD）,scanning electron microscope（SEM） and energy dispersive spectrum（EDS）.The results show that Al content plays an important role in determining the size of TiC particles.The size of TiC particles decreases from approximately 3～5 μm to 0.7～0.8 μm with increasing Al content from 20% to 50%（weight percent）.It is also observed that the size of carbon powders and the reactant C/Ti atomic ratios have a greater effect on morphology of TiC particularly.The TiC grains are in the close-to-sphere shape when the size of carbon powders is less than 75 μm or C/Ti≥1;while the morphology of TiC turns to octahedron when the size of carbon powders is more than 75 μm or C/Ti1.