Al-TiO_2系XD合成铝基复合材料的反应机理

Reactive mechanism of composites synthesized by XD method in Al-TiO_2 system

分析了Al TiO2 系XD合成铝基复合材料的反应机理。研究表明: Al与TiO2 之间可自发进行强放热反应, 燃烧温度随增强相体积分数的增加而增加, 在增强相体积分数为 50%时, 燃烧温度已达 1 960K, 远高于Merzhanov的经验判据值 1 800K; 反应产物Al2O3 是由液态Al与固态TiO2 直接反应产生的, 呈细小颗粒状, 偏聚于基体颗粒的界面; Al3Ti是活性Ti原子扩散穿过反应层进入铝液与液态Al结合生成的, 呈短棒状, 分布相对均匀; 影响反应速率的主要因素有: TiO2 颗粒尺寸、燃烧温度、反应活化能、反应界面面积等。

The reactive mechanism of the composites synthesized by XD method in the Al-TiO_2 system was analyzed. The thermodynamic results indicate that the reactions between TiO_2 and Al carry through spontaneously with high quantity of exothermic heat. The combustion temperature increases with promoting the volume fraction and exceed Merzhanov experience criterion which is about 1800K when the reinforcement volume fraction is higher than 50%. The combusted products consist of particulate Al_2O_3 and stick Al_3Ti. The Al_2O_3 particulates are formed directly by the reaction between Al and TiO_2 and accumulated at grain interfaces of the matrix. The stick Al_3Ti is formed by the reaction between Al atoms and active titanium diffused from the reaction region of Al-TiO_2 and distributes uniformly in the matrix. The main factors influencing the reaction velocity of Al-TiO_2 system are the size of TiO_2 powders, combustion temperature, reaction activation energy, area of the reaction interface etc.