合金元素参与下CNTs/Al复合材料界面行为及其热物理性能研究

Aluminum matrix composites reinforced with Carbon nanotubes (CNTs) are hopeful to become one kind of perfect electronic package material in future due to the CNTs have some excellent properties, such as high thermal conductivity, low coefficient of expansion et. al. However, the thermo-physical properties of the CNTs/Al composites are far unreached to theory value. The main reason is the poor wettability and unstable interface structure between CNTs and Al matrix. . In this project, in order to improve the wettability and control the interface reaction and microstructures between CNTs and Al matrix, the first kind of alloying elements (Ti/Zr/Nb), which can generate the second phase by in-situ reaction with CNTs and the second kind of alloying elements (Mg/Zn/Cu), which can exist in the form of solid solution in Al matrix are both introduced in the CNTs-Al composite. The physics and chemistry behavior and its kinetic law between CNTs and Al during the process of interface formation will be deeply studied with the participation of the above mentioned two kinds of alloying elements. Then, the action mechanism of the effect of the interface structures and thermo-stability on the thermo-physical properties of the CNTs/Al composites will be revealed. Low thermal conductivity and unmatched thermal expansion coefficient with chip and interface thermo-stability of CNTs/Al composites used as electronic package material will be resolved by optimizing the interface structure. The success of this work will make a significant contribution for fabricating the CNTs/Al composites with high thermal conductivity, controllable thermal expansion coefficient and high thermal stability and provide basic theory and guideline in actual application.

CNTs高导热、低膨胀系数及优异的综合性能使得CNTs增强铝基复合材料有望成为理想的电子封装材料，但CNTs与Al润湿性差、界面结合不稳定，其热物理性能远未达理想值。.鉴于此，本项目在CNTs-Al体系中引入能与CNTs原位反应生成第二增强相的合金元素(Ti/Zr/Nb)和在Al基体中以固溶形式存在的合金元素(Mg/Zn/Cu)，分别研究在两类合金元素及其交互作用下复合材料界面形成过程中的物理化学行为及动力学规律，改善增强相与基体间的润湿性、调控界面反应及微结构，提高界面结合的有效性。进而，研究复合材料界面微结构及界面热稳定性对热物理性能的影响机制，通过界面结构优化解决CNTs/Al复合材料热导率低、热膨胀系数与芯片不匹配及其作为封装材料应用时的界面热稳定性问题，获得高导热、热膨胀系数可控、热稳定性高的CNTs/Al复合材料，为其从实验研究到封装应用奠定理论和技术基础。

本项目运行期间，研究了CNTs/Al复合材料及其在少量合金元素Ti参与下组织与性能演变行为及强化机制，揭示了纳米碳管添加量和烧结温度对CNTs/Al复合材料的微观组织和性能的影响规律，揭示了Ti参与下CNTs/Al复合材料的物相演变行为。首次通过调整CNTs/Ti比实现了Al-CNTs-Ti反应路线、物相组成、界面结合的主动控制，揭示了CNTs/Ti比诱发界面反应物对Al-CNTs-Ti体系反应路径、物相组成、陶瓷形貌、力学与热物理性能的影响规律，通过对界面反应润湿的精准控制实现了Al-CNTs-Ti体系复合材料常/高温力学性能和热物理性能大幅度提高。研究了生成第二增强相的合金元素(Mo/Ta/Nb/Zr)对Al-CNTs-Ti体系复合材料物相、组织演变、常/高温力学性能及热物理性能的影响规律，基于仿生设计思想提出了金属间化合物与陶瓷颗粒协同增强金属基体，实现了Al-CNTs-Ti体系复合材料强韧性的大幅度提高。研究了在Al中以固溶形式存在的合金元素(Cu/Mg/Mn/Zn/Si)对Al-CNTs-Ti体系反应行为的影响，揭示了Al-CNTs-Ti-Me体系的反应机制，揭示了合金元素诱导的纳米TiC颗粒的生长行为和形貌控制机制，提出了原位内生纳米TiC外露晶面的调控方法，实现了原位内生纳米TiC的可控制备。首次提出通过调整反应体系来设计和控制界面结合，揭示了Al-Ti-C、Al-Ti-B4C体系复合材料的界面形成机制、界面缺陷形成原因和性能强化机制，通过界面缺陷的抑制及界面结合强度的提高实现了高陶瓷含量的铝基复合材料压缩、磨损、热物理性能的全面提高。