点阵切变组元复合材料的载荷传递行为研究

The intrinsic relationship between load transfer and mechanical behavior of composite is always a key problem in the field of materials science and engineering. However, a large number of previous studies are concentrated in the conventional metal matrix composite where the matrix deformed by dislocation slip. Recently, the Science journal reported that the lattice shear component composite can exhibit more excellent mechanical properties than conventional metal matrix composites (e.g., with an order of magnitude higher for the elastic strain). However, up till now, little is known about the load transfer behavior in the composite where the matrix based on lattice shear. It is clear that the relevant issues will undoubtedly help to enrich and deepen the study of microscopic mechanics of metal matrix composites, and lay a theoretical foundation for the design of new high performance lattice shear composites. This project intends to investigate the lattice strain evolution of the component in our designed lattice shear composite by using in situ synchrotron X-ray diffraction technique, reveal the load transfer behavior of martensitic tranformation composite and martensite variant reorientation composite, clarify the microscopic mechanism of the load transfer in lattice shear composite, and illustrate the intrinsic link between the load transfer behavior and the mechanical behavior of the composite. It is expected to obtain high-quality academic achievement.

复合材料组元间的载荷传递与其力学行为之间的内在相关性一直是材料科学与工程领域的关键科学问题。然而，以往关于载荷传递的大量研究主要集中在传统金属基复合材料(基体为位错滑移组元)领域。直至最近，Science期刊报道点阵切变组元复合材料可呈现较传统金属基复合材料更加优异的力学性能（如弹性应变高出近一个数量级）。但迄今为止，此类复合材料的载荷传递行为却鲜有报道。显然，澄清与此相关的科学问题无疑将有助于丰富和深化金属基复合材料微观力学研究，为新型高性能点阵切变组元复合材料的设计奠定理论基础。本项目拟通过原位同步辐射技术研究点阵切变组元复合材料在变形过程中组元的晶格应变演化，揭示两种典型点阵切变（马氏体相变和马氏体变体取向）机制下复合材料的载荷传递行为与特征，澄清点阵切变组元复合材料载荷传递的微观机制，阐明其载荷传递与宏观力学行为之间的内在联系，可望获得高质量学术成果。

载荷传递在金属基复合材料的力学性能方面起到至关重要的作用。当金属基复合材料在外载作用下发生变形过程中，基体和增强相之间会发生载荷传递。在基体的不同变形阶段，载荷传递行为不一样。载荷传递通过影响增强组元的承载能力从而影响整体复合材料的力学性能。因此，一直以来，复合材料的载荷传递行为受到学者们的极大关注。. 尽管人们之前对复合材料的载荷传递行为做了大量的研究报道，但以往所研究的复合材料的基体塑性变形机制为位错滑移。最近, Science期刊报道点阵切变组元复合材料可呈现较传统金属基复合材料更加优异的力学性能（如弹性应变高出近一个数量级）。但迄今为止，此类复合材料的载荷传递行为却鲜有报道。因此，研究基体塑性变形机制为点阵切变的复合材料的载荷传递行为对于设计新型高性能复合材料具有重要意义。. 本研究采用同步辐射原位技术揭示基体变形机制分别为马氏体相变和马氏体变体取向时，复合材料的载荷传递特征；澄清了孪生基体复合材料载荷传递的微观机制，阐明了载荷传递行为与复合材料力学性能之间的内在联系，建立孪生基体复合材料载荷传递的基本理论。研究结果发现点阵切变组元由于其微观均匀变形机制能够和增强组元实现微观尺度点阵应变匹配。点阵应变匹配确保有效地载荷传递、避免应变局域化，从而实现增强组元的本征力学性能、确保复合材料的高性能。本项目的研究成果为新型高性能金属基复合材料的开发提供理论支持。