Al-Si基复合材料作为一种轻质封装材料，以其较低的成本和良好的热学性能，广泛应用于电子封装领域。然而，传统的Al-Si材料中Si呈粗糙的、有棱角的孤立相，这种结构会降低材料的热学性能。同时，Al和Si固有的物性参数也限制了其在一些领域应用。因此，为了提高Al-Si基复合材料的热学性能，通过仿生结构设计和原位合成技术，制备出的新型半连续仿生结构材料无疑是具有较强竞争力的电子封装材料之一。本文采用粉末冶金结合原位合成技术分别制备了Al-Si复合材料和Al-AIN-Si复合材料，分析了材料结构对热学性能的影响规律，阐明了鹿角仿生结构对Al-Si材料热学性能和磨损性能的作用机理。同时基于实验结果，建立了材料的三维数值模型，对Al-(AIN)-Si材料(Al-AIN-Si复合材料和Al-Si复合材料)的微观动力学演变过程进行了深入分析，并揭示了材料组织结构演变机制。本文主要研究结果如下： (1)高能球磨工艺可以在细化晶粒尺寸同时提高混合粉末的均匀程度，制备出的Al-Si材料组织分布均匀，致密性较好。在一定范围内随着Si的含量增加，合金的组织结构由Al相相互贯通转变为Si相相互连接，相互贯通Al相可提高材料的热导率，而相互连接Si相则可降低材料的热膨胀系数。综合分析表明，由高能球磨制备的Al-50Si材料具有更好的热学性能。 (2)制备出的新型鹿角仿生结构Al-Si材料，具有特殊的孔状骨架-颗粒增强结构。这种结构比普通的离散结构具有更好的抗磨损性能和热学性能。结构中：半连续区，可有效限制和降低基体的热膨胀；孔状区，可减缓摩擦系数的增加；颗粒增强区，可进一步提高抗磨损性能和降低热膨胀系数。 (3)Si含量可以有效控制Al-AIN-Si材料气相扩散反应体系中N₂的浓度二次梯度。Si含量的增加，可导致复杂的扩散通道形成，具有高Si含量的Al-AIN-Si材料促进了N₂与Al的流动反应，使得材料的内部形成连续的AIN-Si复合结构。 (4)前驱体粉末的形貌和尺寸可用于控制Al-AIN-Si材料气相扩散反应体系中反应物的化学势梯度。高能球磨的粉末具有许多高表面能的缺陷，形成的高化学势梯度促进了界面扩散反应，材料形成半连续结构。而混合粉末具有相对稳定的界面且Al和Si润湿性较差，导致AIN和Si在基体中形成相对孤立的结构。 (5)高能球磨的Al-Si复合粉末可原位合成出具有半连续AIN-Si结构的Al-AIN-50Si〓(由球磨粉末制备)材料。与Al-AIN-50Si〓(由混合粉末制备)材料相比， Al-AIN-50Si〓材料表现出更好更稳定的热学性能。Al-AIN-50Si〓材料的热膨胀系数和热扩散系数在100℃时分别为5.9×10⁻⁶／K和64.4×10⁻⁶㎡／s，表明Al-AIN-50Si〓材料具有很好的应用前景。 (6)Al-AIN-Si材料的组织演变过程中，半连续Si结构会导致大流动偏转角的形成。具有更多各向异性的半连续结构可产生较强的湍流，其流动路径呈逐渐减弱的波动趋势。而孤立Si结构表现出温和的湍流，其流动路径呈线性关系。AIN的原位合成强烈的受微观结构和流动路径交互作用影响。 关键词：铝基复合材料；电子封装材料；热学性能；仿生结构；动力学微观组织演变 论文类型：应用基础

 Al-Si based materials, one of the lightweight packaging materials have a wide range of electronic packaging industries owning to their low cost and good thermal properties. However, the conventional Al-Si materials always show a coarse, angular and isolated silicon phase which degrades thermal properties. Moreover, the physical property of Al and Si which confines Al-Si materials applications in many fields. To improve the thermal properties of Al-Si materials, the semi-continuous structure prepared by the biomimetic design and the in-situ synthesis, which can be considered as a promising candidate. In this paper, the Al-Si materials and Al-AIN-Si materials were prepared by high energy ball milled/mixed powders following nitrogen atmosphere sintering. The thermal properties of the different structures were analyzed in Al-(A1N)-Si materials. Specifically, the effects of biomimetic antler-like structure and the normal discrete-like structure on the fatigue wear and the thermal properties of Al-Si materials, which were evaluated in detail. In parallel, the 3D scale models of Al-(A1N)-Si materials were constructed based on the experimental results. The dynamic micro structural evolution of materials was investigated using the computational fluid dynamics (CFD) method.The main conclusion of this paper were list as follow, 1.The high-energy ball milling can reduce powder particle size and can improve the uniformity of particle size. The Al-Si materials showed the uniform micro structure and well compactness. With the increase of Si content, the micro structure of Al-Si were changed from the interpenetrating Al to the semi-continuous Si. The interpenetrating Al structure can improve the thermal conductivity, while the semi-continuous Si can improve the thermal expansion of Al-Si materials. The high-energy ball milled Al-50Si composite powders which show good thermal properties. 2.The biomimetic antler-like structure which shows a novel fenestrated network-particle reinforced Al-Si composite. The fenestrated network-particle reinforced structure exhibits better anti-wear property and thermal properties than that of normal discrete-like structure. These characteristics include an S-N region that can provide a strong support on the surface of wear and can effectively restrict and retard the thermal expansion of matrix; a fenestrated region that leads to the friction coefficient increased slowly, and provides better expansion match with matrix; and a particle-reinforcement region that can further reinforce the anti-wear and thermal expansion properties. 3.For the Al-AIN-Si materials, the Si content can be used to regulate the concentration quadratic-gradient of N₂ in gas-diffusion-reaction system, due to the high Si content which can lead to the formation of complex diffusion channels in the matrix. The high Si content of Al-AIN-Si materials which promotes the flow-reaction of N₂ with Al, and the continuous AIN-Si composite structure is formed in the inner part of the materials. 4.The particle morphology and size can be used to regulate the chemical potential gradient in gas-diffusion-reaction system of Al-AlN-Si materials. The high-energy ball milled powders have many defects of high activation energy which can form high chemical potential gradient, and stimulate the diffusion-reaction of interface and the formation of semi-continuous structure. However, the mixed powders have stable interfaces with poor wettability which cause the formation of relatively isolated islands of AlN and Si in the matrix. 5.The high-energy ball milled Al-Si composite powders can be used to prepare a semi-continuous AIN-Si structure of Al-AlN-50Si〓 materials. The Al-AlN-50Si〓 materials show better thermal properties compared with that of Al-AlN-50Si〓 materials. The CTE and TD of the Al-AlN-50Si〓 materials are 5.9×10⁻⁶/K and 64.4×10⁻⁶㎡/s at 100℃, respectively, thus it is desirable for the application in thermal management materials. 6.In the evolution process of Al-AlN-Si materials, the semi-continuous Si can lead to the formation of the large flow deflection angles. The semi-continuous with more anisotropic structure which can create the strong turbulence with gradually weakened fluctuation in the flow-path. However, the isolated Si structure shows the mild turbulence with linear relationship in the flow-path. The in-situ synthesis of AlN is strongly affected by the interaction of structure and flow-path. KEY WORDS: Aluminum matrix composites; Electronic packaging materials; Thermal properties; Biomimetic structure; Dynamic microstructural evolution TYPE OF DISSERTATION: Application Fundamentals