熔体反应法制备Al-Ti-C合金过程中组织演变机理及控制

The size and distribution of TiC particles play an essential role on the properties of Al-Ti-C alloys which have a strong industry application background. Presently the main producing method of Al-Ti-C alloys is aluminum melt reaction method. Plenty of researches have been carried out on the manufacturing process of Al-Ti-C alloy to control the formation and distribution of TiC particles effectively. It is demonstrated that the size and distribution of TiC particles depend on the size of carbon sources, the interfacial tension between carbon source and Al melt as well as the interfacial tension between TiC particle and Al melt. However, up to date the dynamics for the formation of TiC particles is unclear. Considering that the Nano-scale carbon sources can affect the formation of TiC particles, and micro surface active elements may reduce the interfacial tension between carbon source and Al melt as well as the interfacial tension between TiC particle and Al melt, this project will study the microstructure evolution during aluminum melt reaction process and the controlling methods of the size distribution of TiC particles in Al-Ti-C alloys. The detailed research contents include: Study the dynamics for the formation of TiC particles as well as the effects of Nano-scale carbon sources and micro surface active elements on the size and distribution of TiC particles experimentally; Develop the numerical models for the microstructure evolution during aluminum melt reaction process; Carry out computer simulations according to the experiments to investigate the formation mechanisms of TiC particles and influencing factors, and develop controlling methods of TiC size distribution in Al-Ti-C alloys. These researches will establish theoretical bases for manufacturing high quality Al-Ti-C alloys by using aluminum melt reaction method.

TiC颗粒的尺寸及分布对A1-Ti-C合金的性能具有决定性影响。目前主要用熔体反应法合成A1-Ti-C合金，人们对该制备过程开展了大量研究，以期寻求有效控制TiC颗粒形成及分布的方法。研究表明，C源尺寸及TiC/铝熔体和C/铝熔体的界面能是影响TiC颗粒尺寸及分布的关键因素。但迄今为止，对反应过程中TiC颗粒形成的动力学过程及TiC颗粒尺寸与分布的控制方法尚不清楚。考虑到纳米尺寸C源会深度改变TiC颗粒的形成过程，且微合金化元素会影响C/铝熔体和TiC/铝熔体相间界面能，本项目拟实验研究熔体反应法合成A1-Ti-C合金的动力学过程及碳源尺寸（尤其是纳米尺度碳源）和微合金化元素的影响；分析TiC粒子的形核、长大等特性，建立Al-Ti-C合金合成过程中组织演变模型；实验与模拟相结合，揭示Al-Ti-C合金组织形成机理、影响因素及控制方法，为高性能Al-Ti-C合金的工业设计与制备奠定理论基础。

A1-Ti-C合金是一种高效的铝及其合金的晶粒细化剂，该合金中TiC颗粒的尺寸及分布对其性能具有决定性影响。本项目针对目前人们对A1-Ti-C合金合成过程中TiC颗粒的形成过程及TiC颗粒尺寸与分布的控制方法认识尚不深入的现状开展研究。揭示了Al-Ti-C合金制备过程中的组织形成机理、影响因素及控制方法，全面完成了计划研究内容。具体研究工作及主要成果如下：.实验研究了碳源尺寸和微合金化元素对Al-Ti-C合金合成过程以及组织中TiC粒子数量密度、尺寸和分布的影响；分析了TiC粒子的形核、长大等特性，建立了描述Al-Ti-C合金合成过程中组织演变的模型；实验与模拟相结合，研究了Al-Ti-C合金合成过程的组织演变行为、影响因素及控制方法；在此基础上，优化了Al-Ti-C合金的制备工艺，研制出了TiC颗粒均匀弥散分布于基体之中的Al-Ti-C合金，并对铝合金和铜合金开展了细化实验。结果表明，1) 在反应及保温阶段，碳在铝合金熔体内的溶解度极低，通过溶质Ti与溶质C反应生成TiC相的驱动力远小于通过溶质Ti与固态C反应生成TiC相的驱动力，合金熔体内TiC相主要通过溶质Ti与固态C反应生成；2) 降低碳源尺寸能够显著增加Al-Ti-C合金中TiC粒子的体积分数和数量密度、减小TiC粒子的尺寸分布宽度和平均尺寸，促使TiC粒子更加均匀弥散地分布于基体之中；3) 适当微合金化元素的加入能减小Al-Ti-C合金中TiC粒子的平均尺寸，促使TiC粒子更加弥散地分布于基体中；4) 所研制的Al-Ti-C中间合金对铝/铜合金基体组织和第二相具有优异的细化能力。.就以上研究，发表期刊论文15篇(SCI收录12篇，EI收录12篇)；参加国内会议4次(其中2次为邀请报告)。申请国家发明专利9项，其中5项已授权。培养博士研究生2名（毕业2名）、硕士研究生1名（毕业1名）。