SiCnw/Al-Zn-Mg-Cu复合材料中高含量界面与基体组织交互作用及其强化行为研究

Currently, the interaction mechanism of the high content interface and the microstructure of the matrix，and its corresponding effect on the strengthening mechanism of the Al matrix nano-composites have been rarely reported. Our previous work indicates that the matrix defects and the precipitation behaviors of the Al alloys with low content alloying elements (pure Al and 6061Al) have been changed by the introduction of the high content interface. However, the effect and the corresponding mechanism of high content interface on the microstructure and mechanical strengthening behavior of the Al alloys with high content alloying elements have not been investigated yet. In the present work, highly-alloyed Al-Zn-Mg-Cu alloys with high strength would be used as the Al matrix. By modifying the content of the SiC nanowires and bamboo-like SiC nanowires and the amount of the precipitates contained alloying elements (Zn, Mg, and Cu), the effect of the high content interface on the matrix defects, precipitation, elements distribution and the microstructure of the near-interface-area would be deeply investigated. Moreover, interaction between high content interface and the microstructure of the Al alloys with high content alloying elements would be investigated, and its corresponding effect on the strengthening mechanism of the composites would be revealed. Combining with our previous investigation on the interaction between high content interface and the microstructure of the Al alloys with low content alloying elements, the effect of the high content interface on the microstructure and mechanical properties of the SiCnw/Al composites would be illuminated, which would provide experimental and theoretical support for the design of the composition, optimization of the microstructure and the modification of the performance of the Al matrix nano-composites.

目前高含量界面与基体组织交互作用及对纳米铝基复合材料强化机制的影响研究较少。申请人前期结果表明高含量界面的引入会改变低合金化铝合金(纯Al、6061Al)的基体缺陷形态和析出行为，但高含量界面与高合金化铝基体之间的交互作用及其对复合材料强化行为的影响机制尚不明确。本项目以高强度的高合金化Al-Zn-Mg-Cu铝合金为基体，通过调节SiC纳米线含量、竹节状SiC纳米线含量以及基体中时效析出相元素(Zn、Mg、Cu)的含量，研究高含量界面对复合材料基体缺陷、析出行为、元素分布和近界面显微组织的影响规律，揭示高含量界面与高合金化铝基体间的交互作用，阐明其对复合材料强化机制的影响规律。结合前期在高含量界面与低合金化铝合金交互作用的研究结果，系统阐明高含量界面对SiCnw/Al复合材料显微组织和性能影响机理，为纳米铝基复合材料的组成设计、组织优化及性能调控提供实验和理论依据。

目前高含量界面与基体组织交互作用及对纳米铝基复合材料强化机制的影响研究较少。本项目以SiCnw/Al-Zn-Mg-Cu复合材料为典型研究对象，研究高含量界面对复合材料显微组织和力学性能的影响规律，揭示高含量界面与高合金化铝基体间的交互作用及其对复合材料强化机制的影响，为SiCnw/Al复合材料的设计提供试验数据支持。.对铝基体中的常用合金元素(Zn、Mg、Cu、Si)对SiC-Al界面结合行为的影响进行了第一性原理计算，综合来看，向SiC界面偏聚的趋势为Si>Cu＞Mg＞Zn。对SiC纳米线进行了表征，发现SiC纳米线是由2H和3C结构的小片段复合而成的一种复合型结构。当体积分数为10%~25%时，SiCnw/Al复合材料的基体晶粒尺寸为微米级，基体的缺陷形式为位错。当体积分数达到30%时，SiCnw/Al复合材料的基体中存在大量的层错和孪晶。体积分数为10%~15%的SiC/Al合金的析出相未观察到明显的变化，但是30vol.%SiCnw/Al复合材料的时效组织为基于Si团簇而产生的层错四面体。.随着SiC纳米线含量的提高，SiCnw/Al复合材料的屈服强度及微屈服强度逐渐提升。从体积分数<25%时，屈服强度呈线性提高，当体积分数达到30%时，由于基体中生成层错和层错四面体，复合材料的屈服强度和微屈服强度都有偏离强度和体积分数线性关系的提高，层错和层错四面体对复合材料强度的贡献率约为70%。依据剪切滞后模型，对SiC纳米线增强铝基复合材料的屈服强度公式进行了修正，考虑了本文SiC纳米线长径比、SiC纳米线的尺寸效应以及SiC纳米线的排布方式最终得到了复合材料的屈服强度公式。.共发表学术论文22篇(封面图片论文1篇)；授权发明专利5项；参加了4次国内外会议；培养博士生4名、硕士4名、学士3名。基于本项目研究结果，实现了SiC/Al复合材料的成分设计，有力支撑了高尺寸稳定SiC/Al复合材料的微结构设计，研究成果应用于北斗卫星激光通讯系统、东方红五号电推系统、祝融号火星车双轴天线驱动机构等装备，解决了航天精密机构长期精度稳定、减重、天地一致性等技术难题，获国防科学技术进步一等奖1项(排序2)。