快速凝固高硅铝电子封装材料的稀土元素微合金化及强韧化机理研究

Aluminum-high silicon electronic packaging materials are light-weight electronic packaging materials and widely used in aviation, aerospace and other fields. Their service performance is co-determined by the microstructure of Si phase and the properties of Al matrix. Because of the relatively low strength, rapid solidification coupling with rare earth elements micro-alloying is proposed to modify Si phase as well as strengthen matrix. It is expected to improve the mechanical properties while maintaining the excellent thermal conductivity. The research contents are as follows: (1) The size and morphology of Si phase before and after micro-alloying of rapidly solidified alloys are characterized and compared. The modification effect of rare earth elements is clarified in combination with the distribution of rare earth elements. (2) The precipitation of supersaturated solid solution atoms and the growth of Si phase in rapidly solidified alloys during heating are analyzed. Additionally, the parameters of Si phase growth kinetics are calculated. Then, the influence of rare earth elements addition on the growth of Si phase is clarified. (3) The characteristics of Si phase, rare earth compounds and interface of aluminum-high silicon alloys are characterized carefully. In combination with the results of mechanical testing, the synergistic strengthening-toughening mechanism of Si phase modification and Al matrix modification is revealed. At last, a relationship among the alloy composition, microstructure and properties is established. This research will provide the scientific basis for the design of composition and microstructure of aluminum-high silicon electronic packaging materials.

高硅铝合金作为轻质电子封装材料广泛应用于航空、航天等领域，其服役表现受到Si相结构与Al基体性能的综合影响。本项目针对高硅铝电子封装材料强度较低的问题，提出快速凝固耦合稀土元素微合金化的方法，以调控Si相并强化基体，达到保持良好导热性能并改善力学性能的目的。具体开展以下研究：(1)表征对比微合金化前后快速凝固合金的Si相尺寸和形貌变化，结合稀土元素分布与存在形式考察，明确稀土元素的变质作用；(2)分析快速凝固组织在加热过程中的过饱和固溶原子析出及粗化行为，对比Si相生长动力学参数，探明稀土元素对Si相长大过程的影响；(3)详细表征高硅铝合金的Si相、稀土化合物及界面结构等微观组织，综合力学性能测试结果，揭示Si相调控与Al基体改性的协同强韧化机理，建立合金成分-微观组织-宏观性能之间的关联，为高硅铝电子封装材料的成分与结构设计提供科学依据。

高硅铝合金具有轻质、比强度高、热膨胀系数匹配和激光焊接性能好等特点，是一种重要的电子封装材料，广泛应用于航空、航天、舰船等领域微波发射/接收（T/R）组件的封装壳体。项目基于电子封装铝硅合金的组织特点与应用需求，针对Al-50Si合金强度不足的问题，主要研究内容为：观察气雾化Al-50Si-xSc/Zr合金粉末的主要特征，表征对比微合金化对合金中Si相尺寸和形貌的影响；分析加热保温过程中Si相生长行为以及微合金化的作用；对比分析热压Al-50Si-xSc/Zr合金的微观组织、力学性能和热物理性能；对比Al-50Si-xSc/Zr合金的热循环稳定性，明确其失效机制。重要进展包括：通过对比铸造和不同粒度气雾化Al-50Si-xSc/Zr合金粉末的微观组织，明确了快速凝固协同微合金化对Si相尺寸的抑制作用；通过不同加热温度和保温时间后的微观组织观察和定量分析，明确了Si相的生长行为以及微合金化的影响；对比添加不同微合金化元素对合金微观组织、力学性能和热物理性能的影响，阐明了Si相调控和Al基体改性的强化机理，建立了微观组织与宏观性能的关系，获得强度显著提高且保持良好导热性能的高硅铝合金；进一步地，以综合性能较优的Al-50Si-xSc合金为研究对象，对比分析Sc微合金化对合金热循环稳定性的影响。本项目成果为高强度高硅铝合金的开发和应用提供了理论依据和关键技术，扩展了高硅铝合金微观组织和性能调控的途径。