铝合金疲劳裂纹扩展行为的微结构作用机理

本项目以B93铝合金为研究对象，以微观组织因素为切入点，运用电子背散射衍射（EBSD）、透射电子显微镜和扫描电子显微镜原位观察等技术手段对疲劳裂纹扩展过程中晶粒、晶界及第二相粒子等微结构的作用机理进行了深入研究。详细阐释了晶粒结构、滑移系等效性、晶体学取向、相粒子与位错及位错与晶界间的交互作用等对疲劳裂纹扩展的影响规律，搭建起微结构与疲劳裂纹扩展之间的桥梁，确立循环加载条件下抗疲劳裂纹扩展的微结构适配模式。探讨疲劳裂纹扩展路径选择的优先条件及其必然性的内在机理，并依此构建疲劳裂纹扩展路径选择的统一模型。预期研究成果可为抑制疲劳裂纹扩展速度、延缓材料失效进程研究提供切实可行的基础支持和设计思路，并可推广应用于其它同类型合金，进一步发展完善疲劳裂纹扩展预测和控制理论。

Electron Backscattered Diffraction (EBSD), Transmission Electron Microscope(TEM) and in situ Scanning Electron Microscope(SEM) will be used to investigate influences of grains, boundaries, and second phase particles on the process of fatigue crack propagation and relative mechanisms. Influence discipline of grain structure, slip system equivalence, crystallographic orientation, interactions of particles, dislocation and grain boundaries on crack propagation will be interpreted. Thus relationship between microstructure and fatigue fracture will be verified and microstructure adaptation mode for resistance of fatigue crack propagation under cyclic loading will be established. Moreover, conditions for path choice in process of crack growth and the necessity and mechanisms of it will be discussed. From this, models for fatigue crack propagation could be built. Anticipated research findings of this project will provide foundation support and ideas to researches about inhibition of crack growth rate and fatigue failure retardation. In addition, these findings can also be utilize in similar alloys and improve fatigue crack growth prediction theory.