TiC-Ti复合材料自蔓延高温合成中的组织转变

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。

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

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.