原位自生增强相准连续网状分布铝基复合材料的制备及强韧化机理

In general,conventional Al matrix composites with reinforcements homogeneous distribution usually exibit some superior properties, such as high strength and stiffness.However,some disadvantages in terms of poor plasticity and fracture toughness can not be ignored. To solve the above problem , this project designs the novel composites reinforced by in-situ （Al3Zrp+Al2O3np）with three dimensional quasi-continuous network distribution according to microstructurally toughened mechanism. The composites consist of two parts: the Al matrix composites region reinforced by high volume fraction network reinforcements and the matrix region without reinforcements. The regions with network reinforcement distribution play an effective strenghening role as a "skeleton",while the large proportion matrix contributes to good plasticity and fracture toughness.Using Aluminum powder with large size and fine ZrO2 powder as raw materials, the novel in-situ （Al3Zrp+Al2O3np）/Al composites reinforced by reinforcements with three dimensional quasi-continuous network distribution are fabricated by low-energy milling and reactive hot pressing techniques. Ball milling and hot pressing sintering on the shape, size, distributions of reinforcements, interfaces and matrix microstructure are investigated in detaill to reaval the influences on microstructure and mechanical properties of composites. The relationship between microtructure and mechanical properties is established to achieve the controllability and predictability of microstructure and mechanical properties of quasi-continuous network Al matrix composites. Combined with the theoretical analysis and numerical simulation, strengthening and toughening mechanisms of quasi-continuous network Al matrix composites are clarified.

针对增强相均匀分布的传统铝基复合材料强度、刚度高，但塑性、韧性低的问题，本项目以"微结构韧化"为指导思想设计了增强相呈三维准连续网状分布新型铝基复合材料。该材料由两部分构成：网状增强相分布区和无增强相分布的基体区。网状增强相分布区作为"骨架"起到有效强化作用，而大比例的基体区则有利于获得良好塑性和韧性。以大尺寸Al粉和细小ZrO2粉为原料，采用低能球磨和真空热压技术，原位反应生成Al3Zr颗粒和纳米Al2O3颗粒，制备增强相准连续网状分布（Al3Zrp+Al2O3np）/Al复合材料。通过研究球磨和真空热压烧结工艺对增强相的形状、尺寸、空间分布、界面结构和基体组织的影响，揭示制备工艺对网状铝基复合材料微观组织与力学性能影响规律。建立网状铝基复合材料微观组织与宏观性能的关系，以实现网状铝基复合材料组织和性能的可控制及可预测。结合理论分析及数值模拟，阐明准连续网状铝基复合材料强化和韧化机理。

本项目以“微结构韧化”为指导思想设计并制备了增强相呈三维准连续网状分布新型铝基复合材料。探索并优化了低能球磨工艺和真空热压烧结工艺。研究了增强相种类、增强相分布、增强相体积分数、基体颗粒大小对复合材料力学性能的影响规律。同时研究了热挤压变形对复合材料显微组织和力学性能的影响。研究了网状铝基复合材料的裂纹萌生和扩展行为，结合理论分析和数值模拟阐述了网状结构铝基复合材料的强、韧化机理。.具体研究成果如下：.（1）获得了原位自生增强相网状结构分布高强、高韧铝基复合材料。烧结态网状结构10vol.%（Al3Zr+Al2O3）/6061铝基复合材料室温拉伸强度为200MPa,高于同体积分数增强相均匀分布复合材料的120MPa，挤压变形后网状结构复合材料拉伸强度达230MPa，延伸率为16%。均匀分布复合材料的断裂韧性为12.8MPa.m1/2，烧结态网状结构复合材料的断裂韧性为12.8MPa.m1/2，而挤压态复合材料的断裂韧性为33MPa.m1/2，与T4态6061铝合金断裂韧性接近，说明使得复合材料的塑性和韧性达到了6061铝合金的水平。.（2）阐明了制备工艺参数和网状结构参数对铝基复合材料微观组织及力学性能的影响规律，实现了网状结构铝基复合材料的可设计、可预测和可调控。.（3）揭示了网状结构铝基复合材料的强化机理和韧化机理，增强相网状分布区类似“骨架”对复合材料起到有效的强化作用，而网内大比例的基体区则有利于网状结构复合材料获得良好的塑性和韧性。.（4）国际著名杂志发表学术论文9篇，其中SCI检索7篇，EI检索8篇。.（5）撰写国家发明专利1项。.（6）协助培养博士后1名，博士生2名；培养硕士生4名，本科生3名。