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以Ti、Al和TiO2混合粉的原位反应制备Al2O3颗粒增强TiAl基复合材料。利用热力学机理分析了制备该种材料的可行性;用扫描电镜观察了合成产物的组织形态;借助差热变化曲线,对Ti-Al-TiO2体系的反应过程进行了初步研究。结果表明,Ti-Al-TiO2体系的反应能够原位生成Al2O3颗粒增强的TiAl基复合材料;Al2O3颗粒分布在基体晶界处,随其含量增大,基体晶粒逐渐细化;铝熔化后首先开始了TiAl3的生成反应,由于TiO2的稀释作用,使它的放热峰与Ti-Al体系的主放热峰相比有所滞后,紧接着发生了Al-TiO2的还原反应,由于其激活能低而速度较快,因此较早完成;若Al-TiO2的还原反应未进行彻底,部分TiAl3将分解以提供铝液;最后发生了TiAl3向TiAl和Ti3Al相转变的过程。
In - situ Synthesis of Al2O3 Particle Reinforced TiAl Matrix Composites with In situ Mixed Ti, Al and TiO2 Powders. The feasibility of preparing the material was analyzed by thermodynamic mechanism. The morphology of the synthesized product was observed by SEM. The reaction process of Ti-Al-TiO2 system was preliminarily studied by means of the curve of differential thermal. The results show that the reaction of Ti-Al-TiO2 system can generate Al2O3-TiAl matrix composites in situ. Al2O3 particles distribute at the grain boundaries of the matrix. With the increase of the content, the matrix grains gradually refine. The TiAl3 formation reaction started. Due to the dilution effect of TiO2, the exothermic peak of TiAl3 lags behind the main exothermic peak of Ti-Al system, followed by the reduction reaction of Al-TiO2. Due to its activation energy Low and fast, and therefore completed earlier; if the reduction reaction of Al-TiO2 is not complete, part of TiAl3 will be decomposed to provide molten aluminum; and finally TiAl3 to TiAl and Ti3Al phase transformation process.