高熵合金增强金属基复合材料的界面调控及强韧化效应

Metal matrix composites (MMCs) can be widely used in such areas as aerospace, automobile, electronics, etc. The ceramic reinforcements display low wettability with the metal matrix and the fragmentation of the ceramic reinforcements occurs sometimes during the cooling process due to the large difference of the thermal expansion coefficient between ceramics and metal matrix. The metallic glass reinforcements have also some drawbacks, such as low thermal stability and plasticity. In this project, MMCs reinforced with high-entropy alloy is presented firstly. The main scientific problems include: 1) Technological parameters of high-entropy alloy by mechanical alloying and MMCs reinforced with high-entropy by powder metallurgy are optimized. 2) The interfacial property of MMCs reinforced with high-entropy is improved by using the crystal structure sensitivity of high-entropy alloy to alloy composition. Moreover, based on the understanding of diffusion and phase transition in the interface between metal matrix and high-entropy alloy reinforcement, the thermodynamic equation of diffusion is built and the modulation of interface properties is realized. 3) According to mechanical properties, interfacial characteristics and microstructure of MMCs, the effect of interface on properties of MMCs is analyzed. The results in this project not only can provide the theoretical basis of MMCs with high-performances but also better explore the strengthening and toughening mechanisms of MMCs. Therefore, this project has theoretical significance in science and practical value in engineering.

金属基复合材料可以广泛用于航空航天、汽车、电子等领域。陶瓷增强相与金属基体热膨胀系数差异大，界面润湿性差；非晶增强相热稳定性和塑性差。本项申请在已有研究基础上，首次提出了用强度硬度高、韧性和热稳定性好的高熵合金来增强金属基复合材料的新思路。其研究内容包括：1）系统研究高熵合金机械合金化的工艺，优化高熵合金增强金属基复合材料的粉末冶金工艺。2）充分利用高熵合金的晶体结构成分敏感性，来改善复合材料的界面；明确增强相高熵合金与基体间的扩散和相变过程，建立合金元素扩散的热力学方程，有效调控复合材料的界面性能。3）根据复合材料力学性能、界面性能以及微观组织等分析测试结果，深入分析界面性能对复合材料力学性能的影响规律。其研究结果不仅为制备高性能金属基复合材料奠定坚实的理论基础，还能进一步揭示金属基复合材料的强韧化机制。因此，本项申请具有重要的科学理论意义和工程实用价值。

项目按照预定方案和路线开展研究，完成了预定了研究任务和研究目标。首先采用机械合金化法制备出了性能优异的高熵合金粉末，再利用等离子烧结技术制备出了铝基和铜基的粉末冶金制备高熵合金增强金属基复合材料。最后利用高强度、高硬度以及韧性和热稳定性好的高熵合金增强金属基复合材料，同时充分发挥高熵合金晶体结构对成分的敏感性来改善了复合材料的界面。在明确了增强相高熵合金与基体金属之间的扩散和相变过程的基础上，有效的调控了调控高熵合金增强金属基复合材料的界面性能和厚度，根据复合材料和界面的力学性能测试的结果以及微观组织分析的结果，揭示了金属基高熵合金复合材料的强韧化机制。