基于实际三维细观结构研究原位镁基复合材料宏细观损伤机理

The mechanical and physical properties of particles reinforced magnesium matrix composites seriously depend on its mesostructures, characterizating of composite real mesostructure and exploring the relationship between the mesostructure and the macroscopic properties which demonstrates macro mesoscopic damage mechanismthe are the key foundation problem to design and development of magnesium matrix composites. Research on macro mesoscopic damage mechanism of in situ magnesium matrix composites based on real three-dimensional mesoscopic visualization by the theoretical analysis and experimental analysis. Emphasis was on the formation mechanism of in situ synthesis particles; preparation method of in situ magnesium matrix composites using response impregnation method and semi-solid stirring process combined with vacuum hot pressing technology, to explore the formation mechanism; the related model of three dimensional “mesostructure-visual presentation-mechanical properties” i.e. the forward materials prediction and the reverse materials design model, was built by combining serial section-based three dimensional reconstruction, molecular dynamics simulation and finite element analysis; the effects of the microstructures of in situ reinforcement particles, matrix and interface on the macro mesoscopic physical properties, mechanical properties and deformation failure mechanism of in situ magnesium matrix composites were researched and the quantitative relationship between the mesostructure and the macroscopic properties of in situ magnesium matrix composites were established. In the study, the inadequate microscopic information in the macro mesoscopic damage mechanismthe research of composites was overcome, and it also provided the important theoretical foundations for the structure optimization, failure analysis and preparation process of in situ magnesium matrix composites , and so on.

颗粒增强镁基复合材料内部细观结构严重影响其物理性能和力学性能，表征实际三维细观结构信息并探究宏观性能与细观结构之间内在关系进而揭示宏细观损伤机理是设计和开发原位镁基复合材料的关键基础问题。本项目拟通过理论分析和实验分析，基于实际三维细观结构研究原位镁基复合材料宏细观损伤机理。重点研究原位颗粒的形成机制；研究采用反应浸渗法和半固态搅拌工艺并结合真空热压技术制备复合材料，探索其形成的物理机制；研究连续切片三维重构、分子动力学和有限元分析相结合建立“三维细观结构-可视化演示-力学性能”相关联的正向材料预测与反向材料设计模型；研究原位合成颗粒、基体和界面等细观结构对镁基复合材料宏细观物理性能、力学性能、变形失效机理的影响规律，定量建立原位镁基复合材料细观结构与宏观性能之间关系。该研究克服了复合材料宏细观损伤机理研究中微观信息考虑不足，为原位镁基复合材料结构优化、失效分析、制备工艺等提供理论依据。

本项目实施期间，项目组按照国家基金管理规定及时提交项目进展报告，汇报项目研究进展情况。在工艺开发、数学建模与模拟、理论研究等方面取得预期成果，完成了项目计划任务书中的内容：依据热力学基本原理，研究了原位合成TiC的形成机制；搭建了制备原位TiC/AZ91D镁基复合材料实验平台，成功探索制备出了原位TiC/AZ91D镁基复合材料，定量建立了稀土合金复合改性与其组织和性能之间的关系；基于图像处理、识别技术和边缘提取技术，构建了TiC/AZ91D镁基复合材料真实微观结构的有限元模型，探明了拉伸过程中原位合成颗粒形状、体积分数和分布对其失效行为的影响机理，模拟与实际吻合；采用分子动力学模拟方法，从纳米尺度阐明了变形温度、空洞缺陷尺寸和应变速率影响镁孪晶界面塑性变形机制；基于密度泛函理论的第一性原理平面波超软赝势法，基于复合材料界面粘附功确定了界面的润湿性和结合强度，揭示了基体中掺杂合金元素对原位合成颗粒与基体界面稳定性的影响规律。