原位合成TiC/Ti复合材料的微结构和力学性能

Microstructure and Mechanical Properties of In Situ Synthesized TiC/Ti Composites

利用钛与碳之间的反应 ,经非自耗电弧熔炼工艺 ,简洁、低成本地制备了 Ti C增强的钛基复合材料 .借助光学金相显微镜和透射电镜分析了复合材料的微结构 ,测定了原位合成钛基复合材料的力学性能和硬度值 .结果表明 ,原位合成增强体 Ti C均匀地分布在基体钛合金中 ,增强体主要呈树枝晶状和等轴、近似等轴状 .由于增强体 Ti C与基体合金的热膨胀系数存在较大的差异 ,在基体钛合金中形成高密度的位错 .增强体与基体界面洁净 ,没有任何界面反应 .复合材料的力学性能和硬度与基体钛合金比较有了明显的提高 .铝元素的加入 ,不仅固溶强化了基体钛合金 ,同时使增强体更为细小 。

TiC reinforced titanium matrix composites were simply produced at low cost by non-consumable arc-melting technology utilizing the reaction between titanium and graphite. Microstructure observations of the composites were performed by means of optical microscopy and transmission electron microscopy (TEM). The mechanical properties and hardness values of in situ synthesized titanium matrix composites were determined by material mechanics test and hardness test. The results show that the reinforcements are distributed uniformly in the titanium matrix alloy. The reinforcements show dendritic shape and equiaxed or near-equiaxed shape. There are high-density dislocations in the titanium matrix alloy due to a large difference in the coefficients of thermal expansion between TiC and titanium matrix alloy. The interface between reinforcements and the matrix alloy is very clean and there is not any interfacial reaction. The mechanical properties and hardness of titanium matrix composites are improved obviously due to the incorporation of in situ synthesized reinforcements. The strengthening mechanisms are attributed to the following factors: undertaking load of reinforcement, refinement of titanium matrix alloy's grain size and high-density dislocations in titanium matrix alloy. The addition of aluminum not only strengthens the titanium matrix alloy by solid solution strengthening, but also improves the mechanical properties by refining reinforcements.