原位(TiB_2-TiB)/Cu复合材料组织与性能研究

Research on the Microstructure and Properties of In Situ(TiB_2-TiB)/Cu Composites

采用机械合金化和热压烧结相结合的方法制备出原位TiB_2颗粒和TiB晶须混杂增强的铜基复合材料,利用XRD、OM、SEM、TEM研究了复合材料的微观组织,分析了热压烧结过程中的原位反应机理及微观组织对复合材料硬度、导电率及致密度的影响规律。结果表明:原位反应过程为Cu和Ti原始粉末在800℃开始反应生成Cu3Ti中间相,在850℃时达到Cu3Ti中间相的熔点并在基体中形成液相微区,然后B原子扩散至该液相微区,在继续加热过程中原位析出硼化钛增强相。TiB晶须含量相对较多的复合材料具有较高的硬度,Ti B2颗粒含量相对较多的复合材料具有较高的导电率,TiB晶须和TiB_2颗粒混杂增强的铜基复合材料则同时兼备了以上2种复合材料的性能优势,其综合性能得到优化。所得烧结态3%(TiB_2-TiB)/Cu混杂增强复合材料的硬度和导电率分别达到86.6 HB和70.4%IACS。

Copper matrix composites have attracted a lot of interest regarding their application as electrical materials.However,the development of copper matrix composites has suffered setbacks because of a trade-off between electrical conductivity and strength.In this work,TiB2 particles and TiB whiskers hybrid reinforced copper matrix composites were in situ fabricated by mechanical alloying and hot pressing.The microstructures of hot-pressed composites were characterized by XRD,OM,SEM and TEM.The mechanism of in situ reaction during hot pressing process and the influence of microstructures on physical properties of hot-pressed composites were analyzed.The Cu and Ti raw powders were firstly reacted at 800 ℃ by forming Cu3 Ti transient phase.Then,the Cu-Ti liquid micro-zone was formed at850 ℃,which is higher than the melting point of Cu3 Ti phase.With the increasing of temperature further,TiB2 particles and Ti B whiskers were formed in the liquid micro-zone by the diffusion of B atoms from copper matrix.When the reinforcing phase is consisted of mainly TiB whiskers,the hardness of composites is relatively high.But the composites reinforced mainly by TiB2 particles have a higher electrical conductivity.The combined properties of hybrid reinforced copper matrix composites were optimized due to the combination action of TiB2 particles and Ti B whisker.For the case of 3%(TiB2-TiB)/Cu composites,thehardness and the electrical conductivity are 86.6 HB and 70.4% IACS,respectively.