高压凝固SiCp/Al-Si复合材料界面微区调控及其失效机理研究

It has very important application prospect to increase the strength and toughness of SiCp/Al-Si composites via high pressure solidification(GPa) introducing SiC-Si-Al interface. The strengthening and toughening methods need to a profound understanding of failure mechanism and control of pressure-induced SiC-Si-Al interfacial micro-zone. However，the related research is not thorough，and a lot of basic theoretical problem still remains unsolved. This project aims at solving the control of SiC-Si-Al interfacial micro-zone and the failure mechanism and other basic scientific problems. Pressure-induced SiC-Si-Al interface micro-zone after high pressure solidification is chosen as the research object. The system of high pressure solidification experiments, theoretical analysis and numerical simulation will be carried out to reveal the effect law of solidification pressure, interfacial strength, Si diffusion layer thickness, eutectic Si feature size on the stress distribution in the interface micro-zone, establish interface structure characterization of the physical model and obtain interface micro-zone stress regulation mechanism; to unveil the mechanisms of load transfer and deformation coordination in the SiC-Si-Al interface micro-zone; to indicate the interaction rules of pressure-induced twin in silicon phase with high density dislocation and the crack initiation mechanism in the interface micro-zone loading and disclose the evolution of interface cracks expansion in the interface micro-zone.

通过高压凝固(GPa级)引入SiC-Si-Al界面，增加SiCp/Al-Si复合材料强韧性具有重要的应用前景。这种增强增韧方法需要对SiC-Si-Al界面微区调控及其失效机理有深入的研究，但目前相关研究还很不深入，很多基本的理论问题尚待解决。本项目针对SiC-Si-Al界面微区调控及其失效机理等基本科学问题，以高压凝固后的SiC-Si-Al界面微区为研究对象，通过系统的高压凝固实验、理论分析和数值模拟来揭示凝固压力、界面结合强度、Si扩散层厚度、共晶Si特征尺寸等对界面微区应力分布的影响规律，建立界面结构物理模型，获得界面微区应力调控机理；揭示SiC-Si-Al界面微区载荷传递与变形协调机制；阐明界面微区内硅相压致孪晶与周围高密度位错加载时的相互作用规律及裂纹萌生机理，同时研究界面微区裂纹的扩展演化规律。

以SiCp/Al-Si复合材料为研究对象，在GPa级压力下熔化与凝固，通过高压凝固实验、理论分析和数值模拟研究了凝固压力、界面结合强度、Si扩散层厚度、共晶Si特征尺寸与含量对SiC-Si-Al界面微区结构与应力分布的影响，分析了SiC-Si-Al界面微区中Si相内的压致孪晶与周围的α-Al内高密度位错的相互作用规律。通过三维X射线显微镜与透射电镜的原位拉伸实验研究了外加力场作用下SiC-Si-Al界面微区载荷传递与变形协调机制，以及SiC-Si-Al界面微区裂纹的扩展演化规律，揭示了SiC-Si-Al界面微区力学性能与宏观力学行为的跨尺度耦合规律。通过研究与理论分析，获得了凝固压力、界面结合强度、Si扩散层厚度、共晶Si特征尺寸与含量对界面微区应力场的影响规律，凝固压力增大促进了共晶Si相细化，使共晶Si相中压致纳米孪晶数量增多，显著阻碍了位错运动；建立了高压凝固SiCp/Al-Si复合材料SiC-Si-Al界面结构物理模型，颗粒形貌、粒径与体积分数完全可控；建立了一种X射线衍射技术与EBSD技术相结合的表征颗粒增强金属基复合材料界面微区应力分布的检测方法；揭示了SiC-Si-Al界面载荷传递机制，凝固压力增大改善了SiCp与Al-Si合金的界面结合状态，SiCp阻碍了裂纹的扩展；阐明了载荷传递过程界面微区各相的应力与应变协调作用规律；获得了压致孪晶与高密度位错相互作用规律及裂纹萌生机理；获得了裂纹的扩展演化行为规律。通过高压凝固(GPa级)引入SiC-Si-Al界面，揭示了高压凝固制备SiCp/Al-Si复合材料的界面微区调控及其失效机理，为SiCp/Al-Si复合材料的强韧化提供理论和工艺基础。