Combustion Synthesis of Fe-Cu-TiC Composites under Electric Field

摘要:

以配料比为15%(Ti+C)-65%Fe-20%Cu (质量分数)（Ti:C化学计量比为1:1）的Fe-Cu-Ti-C体系为研究对象，研究该体系在不同温度下的燃烧合成过程。Fe-Cu-TiC复合材料在759 ℃的点火温度下完成电场辅助燃烧合成，该电场辅助由Gleeble-3500D热模拟机提供。Fe-Cu-Ti-C体系燃烧合成的四步模型被提出，描述了Fe-Cu-TiC复合材料的在电场作用下的燃烧合成过程。它包括 (I) 预热阶段、(II)固相扩散阶段、(III) 燃烧合成阶段、(IV) 后续阶段。从阶段I到阶段II，反应物原子的固相扩散随着温度的增加而增加。从阶段II到阶段III，C原子扩散到Ti原子，直至紧密的与其接触。在III的初始阶段，Ti开始和C在界面处发生反应：Ti(s) + C(s) =TiC(s)，并且Ti粒子周围形成一层很薄的固相产物TiC层。在III的后续阶段，C原子穿过固相产物TiC层，扩散到Ti粒子中，继续发生化学反应，直到TiC粒子析出。在第IV阶段，TiC颗粒逐渐的形核和长大，在SEM中可以看出TiC是球形颗粒。

Abstract:

Fe-Cu-TiC composites were synthesized and consolidated simultaneously at an ignition temperature of 759 °C by electric field-assisted combustion synthesis (EFACS). This electric field was generated by a Gleeble thermal simulation instrument. The combustion synthesis process of 15(Ti+C)-65Fe-20Cu (wt%) system, where the molar ratio of Ti to C was 1:1, was studied according to quenching at different temperatures. A four-step model was proposed to describe the combustion synthesis process of Fe-Cu-TiC composites under an electric field. It is suggested that EFACS consists of preheating (I), solid diffusion (II), combustion (III), and post-combustion (IV) stages. The solid diffusion of reactant atoms increases with temperature increasing from the stage I to the stage II. From the stage II to the stage III, carbon atoms gradually diffuse towards titanium atoms until their close contact is performed. During the initial stage III, Ti starts to react with C, i.e. Ti(s) +C(s) =TiC(s) at their interfaces and TiC surrounds the raw Ti atom. Moreover, liquid Cu is formed at the same time. In the following stage III, C atoms diffuse further through the reactant TiC layer, and full reaction between C and Ti is accomplished. The nucleation and growth of TiC takes place in the stage IV. As can be seen from the SEM photographs, TiC exhibits spherical particle.