TiC-Ti复合材料自蔓延高温合成中的组织转变

Microstructural Evolution during Self-Propagating High-Temperature Synthesis of TiC-Ti Composite

用燃烧波淬熄法研究了TiC-Ti金属陶瓷自蔓延高温合成(SHS法)中的组织转变和反应机理。淬熄试样中保留了未反应区、反应区及已反应区。用扫描电子显微镜观察了燃烧反应中的显微组织转变过程,用能谱仪分析了各微区的成分变化,测量了燃烧温度Tc,并用XRD分析了反应产物的相组成。实验结果表明:TiC-Ti复合材料的自蔓延高温合成机理可以用溶解-析出机制来描述;Ti首先部分熔化,C溶解在Ti液中,并和Ti发生反应生成TiCx,随着温度的升高,TiCx熔化,形成Ti-C熔体,在降温过程中,细小的TiC大量从Ti-C熔体中析出并聚集,最终形成TiC增强Ti基复合材料。

In this paper, a mechanism of self-propagating high-temperature synthesis of TiC-Ti composite was studied by means of a combustion wave front quenching method in which all information about a process of a phase transitions and a process of a microstructural evolution were remained in the quenched sample. The product was analyzed by X-ray diffraction （XRD）, and the process of a microstructural evolution was investigated using scanning electron microscope （SEM） and energy dispersive X-ray （EDX）. Based on these experimental results, the mechanism of self-propagating high-temperature synthesis of TiC-Ti cermets was discussed. The experimental results show that the mechanism of SHS of TiC-Ti can be described with a dissolution-precipitation mechanism. The Ti powders melt firstly, and the C particles dissolve in the Ti liquid. C atoms react with Ti and became TiCx. And with the temperature rising, the TiCx particles melt and form Ti-C liquid. As the temperature decreasing, the small TiC particles precipitate from the Ti-C liquid. In the end, a great amount of TiC precipitate from the Ti-C liquid and aggregate. The final products are composed of TiC particles and Ti matrix.