枝晶增韧ZrTi基非晶复合材料的低温拉伸变形机理

Dendrite-reinforced metallic glass matrix composites (MGMCs) have attracted a flood of interests, owing to their high strength and excellent tensile plasticity. However, deformation mechanism of this advanced materials at cryogenic temperatures still remains unclear until now. This project will select a ZrTi-based MGMC with high plasticity as model materials. The in-situ tensile deformation behaviors of this composite at cryogenic temperatures will be studied. The stress/strain states of the glassy matrix and dendritic phase will be explored in real time using complementary focused ion beam and high resolution scanning electron microscope, in order to make clear the evolution rule of stress/strain fields of the individual phases, and then investigate their effects on the global deformation behaviors of this composite. Electron back-scattered diffraction combined with synchrotron X-ray diffraction will be used to study in-depth the atomic-scale structure evolution of the glassy phase and the phase transformation of the dendritic phase, and then establish the underlying correlation between them and the formation mechanism of shear bands. The full dynamic process of the shear band nucleation and propagation, and their evolution into cracks will be understood. This project will provide a better understanding of the macro/micro-scopic deformation mechanism of MGMCs. It will be expected that this study will lay the solid foundation for the exploration of MGMCs with high plastic deformation capacity and thus extend their applications in extreme conditions.

枝晶增韧非晶复合材料因其兼具高强度和高拉伸塑性而引起材料界的广泛关注，然而其在低温下力学变形的物理机理尚不明晰。本项目拟以具有优异拉伸塑性的ZrTi基非晶复合材料为研究对象，原位观察其在低温下的拉伸变形行为，采用聚焦离子束并结合高分辨扫描电子显微镜，实时获取枝晶相及非晶相在拉伸过程中各自的应力/应变状态，借此探明两相各自的应力/应变场演变规律及二者对于非晶复合材料的整体变形行为的协同作用，基于背散射电子衍射技术并结合同步辐射技术，原位研究其在低温拉伸变形过程中非晶相的原子尺度结构演变规律及枝晶相的相变行为，并研究应力/应变场演变及相变行为与剪切带的形成之间的关系，进而构建非晶复合材料在拉伸变形过程中剪切带形核、扩展乃至最后形成裂纹的整个动态过程，从而深入认识非晶复合材料在低温下的宏/微观变形行为，为开发具有大塑性变形能力的非晶复合材料并拓展其在极端环境（如太空）下的应用提供理论指导。

非晶复合材料因其兼具高强度和高拉伸塑性而引起材料界的广泛关注，然而其在低温下力学变形的物理机理尚不明晰。本项目主要以具有优异拉伸塑性的CuZr基非晶复合材料为研究对象，探究了晶体相体积分数与剪切带演变规律之间的关系，阐明晶体相体积分数对非晶合金复合材料塑性变形产生影响的本质机理，明晰了非晶合金复合材料在室温及低温条件下变形的温度相关性，并利用纳米压痕技术研究了样品制备过程中冷却速率对非晶基体结构特征及其力学性能的影响规律。研究结果对于调控非晶复合材料的微观结构进而改善其力学性能中起到指导作用，也对于开发和合成新型具有优异力学性能的非晶复合材料具有重要意义。项目在研期间，在International Journal of Plasticity, Journal of Materials Science & Technology及Scripta Materialia等国际重要学术期刊上发表SCI论文32篇；申请国家发明专利10项，授权6项，2020年获黑龙江省高校科学技术奖二等奖1项。