铁基复合材料中原位TiC增强颗粒生成机制

在合金熔体中采用不同时间取样，通过液淬的方法，将铁基复合材料的液态合金熔体迅速冷却到室温，固定熔融条件下的形态，观察金相组织，分析其变化情况．结果表明：根据热力学及动力学分析，合金熔体在富碳区TiC的形核率很高，形核驱动力足以在正常熔炼温度下形成众多的小晶核；熔体中TiC颗粒的形成可分为形核与长大阶段，首先活性Ti原子包围C，溶入合金中的Ti与C在碳表面形成一复杂反应中间层，随着反应进行，Ti和C颗粒不断减少，生成的TiC不断弥散分布于熔体中；其长大过程伴随着TiC颗粒的相互堆砌、聚集和形态规则化．

Study on Formation Mechanism of in Situ TiC Particle-reinforced in Iron Matrix Composites

Samples were selected at different time in liquid alloy. Then the liquid alloy of iron-matrix composites was cooled to room temperature at a rapid speed and fixed its shape at the situation of melting by the method of liquid quenching. We observed its micro-structure and analyzed its changes. The results show that the nucleation rate of TiC is high in rich carbon area of alloy melt according to thermodynamic and kinetics analysis. Nucleation driving force can form a lot of small nucleus at normal melting temperature. The formation of TiC grains can divide into two stages-nucleation and growth. Firstly, active Ti atoms surround carbon atom and form a complex reaction middle layer at the surface of carbon in alloy. With the process of reaction, Ti and carbon grains decrease constantly, acquired TiC distribute in alloy melt in manner of dispersion. The growth process is accompanied with mutual pile, aggregation and regularization of shape.