基于透射/扫描电镜原位实验的高熵合金跨尺度断裂破坏研究

High-entropy alloy attracts a lot of research attention recently due to its super property of high strength, high toughness and high-temperature resistance. In-situ experiments provide a new approach to observe the deformation and nucleation and evolution of microstructures in the fracture process of high-entropy alloy. This project employs in-situ experiments to observe the nucleation and propagation of twins and voids, the movement of dislocations and material damage during the fracture process of high-entropy alloys and understands the underlying mechanisms. Based on in-situ experiments, a multiscale model will be proposed to solve the boundary value problems of the fracture coupling both the macroscopic and microscopic scale, which needs to be improved through the comparison with in-situ experimental measurements on microstructure evolution and force-displacement. Based on the multiscale model, a macroscopic model will be proposed, which will be used to model the fracture process of three-bending and compact tension specimens. This project sets up a foundation for the microstructure design and engineering application of high entropy alloy.

高熵合金因其良好的强度、韧性、耐高温等综合优异性能，目前是备受关注的先进材料。但此类材料宏微观断裂力学机制尚不十分明确。本项目将应用透射/扫描电镜下的原位实验来清晰观测高熵合金断裂过程中的形变和内部多层次微纳观结构如位错、纳米孪晶和亚微米空洞等的萌生和演化。在此基础上，建立从微纳观到宏观的跨尺度力学模型，通过求解宏微观耦合边值问题，模拟试样断裂过程，与原位实验观测的微尺度位错、孪晶及空洞演化及力位移曲线全面对比，改进跨尺度力学模型，实现对断裂过程的定量表征，透彻理解高熵合金断裂力学机制。进而凝练能描述空洞、孪晶、位错行为的宏观损伤力学模型，预测高熵合金实验室结构件断裂破坏过程。项目研究成果不仅可以推进微纳米力学研究的前沿进展，而且可为高熵合金这一具有广阔应用前景的先进材料研发提供技术支撑。

高熵合金因其良好的强度、韧性、耐高温等综合优异性能，目前是备受关注的先进材料。但此类材料宏微观断裂力学机制尚不十分明确。本项目将应用透射/扫描电镜下的原位实验来清晰观测高熵合金断裂过程中的形变和内部多层次微纳观结构如位错、纳米孪晶和亚微米空洞等的萌生和演化。在此基础上，建立从微纳观到宏观的跨尺度力学模型，通过求解宏微观耦合边值问题，模拟试样断裂过程，与原位实验观测的微尺度位错、孪晶及空洞演化及力位移曲线全面对比，改进跨尺度力学模型，实现对断裂过程的定量表征，透彻理解高熵合金断裂力学机制。进而凝练能描述空洞、孪晶、位错行为的宏观损伤力学模型，预测高熵合金实验室结构件断裂破坏过程。项目研究成果不仅可以推进微纳米力学研究的前沿进展，而且可为高熵合金这一具有广阔应用前景的先进材料研发提供技术支撑。