胶体系统可视化研究非晶金属形变断裂的微观结构起源及多时空尺度物理力学模型

The promising application of metallic glasses in machine, aerospace and biomedicine promotes their rapid development. However, the physical mechanisms for deformation and fracture of amorphous metals are not clear enough. It's still far away from effective prediction and optimization of mechanical properties of metallic glasses. The basic problem is the lack of knowledge of the complicated microstructures and trans-scale physical processes by using current available experimental methods. This key scientific issue puts forward a big challenge for fundamental research. Colloids are proved to be ideal model systems for simulating the microstructures and physical processes in atomic systems. In addition, the motion of single colloidal particles can be observed and tracked by microscopy. Colloids have become important systems to research the micromechanisms of phase transitions and a great deal of significant insights have been obtained. In this proposal, by using mono- or multiple model systems with colloidal particles of different shapes and inter-particle potentials, by connecting the macroscopic and micro-mechanical measurements and the in-situ microscopic observations, the microstructure evolution of local defects and orders and the spatial distribution of free volume, the behaviors of shear transformation zones (STZ) and shear bands will be more realistically simulated and more accurately characterized, as well as the interaction of microstructures and behaviors. The coupling relationship of physical and mechanical processes at multiple temporal-spatial scales will be detected. The dependence of physical-mechanical processes on loads and temperature will be systematically studied. Therefore, the microstructure origin of mechanical behaviors can be explored. The intrinsic relationships of different mechanisms and their operating conditions can be revealed. By verifying and clarifying theoretical hypothesis and predictions, the multiple temporal-spatial scale physical-mechanical models are tried to be abstracted finally. This research can better reveal the deformation and fracture mechanisms from a microscopic-structure level, which will be conducive to solving the practical problems such as configuration optimization of mechanical properties and the designs of smart materials. It also reflects the research trends in colloidal model systems.

非晶金属在机械、航天及生物医学等领域的应用前景使其迅速发展。然而其形变断裂机理仍不清晰，远未实现力学性能预测和优化，其根本原因是现有实验方法对复杂微观结构和跨尺度物理过程认识的不足，此关键科学问题对基础研究提出了挑战。胶体体系被证明可有效模拟原子体系微观结构和物理过程，且单粒子运动可直接观测，对相变机理研究已有大量重要成果。本项目拟利用不同形状和作用势的一元/多元胶体体系，结合宏观/局域力学测量与原位显微观测，更真实模拟和准确表征非晶金属形变过程中结构重排和自由体积再分布等微观结构演变以及STZ和剪切带等行为，探测物理-力学过程跨时空耦合关系及其对载荷和温度的依赖，探寻力学行为微观结构起源，揭示力学机制内在关联和作用条件，以验证理论假说，提炼多时空尺度物理力学模型。本项目从微观结构层面更好的揭示形变断裂机制，有助于力学构型优化和智能材料设计等实际问题的解决，是胶体模型化研究必然趋势。

非晶材料在机械、航天及生物医学等领域的应用前景使其迅速发展。然而玻璃态转变和形变等物理力学性质的机理仍不清晰，远未实现物态和性能的预测和优化，其根本原因是现有实验方法对复杂微观结构和跨尺度物理过程认识的不足，此关键科学问题对基础研究提出了挑战。胶体体系被证明可有效模拟原子体系微观结构和物理过程，且单粒子运动可直接观测，对相变机理研究已有大量重要成果。本项目拟利用不同形状和作用势的一元/多元胶体体系，结合宏观/局域力学测量与原位显微结构观测，更真实模拟和准确表征非晶形成和形变过程中微观结构重排和局域力学行为，探测物理-力学过程跨时空耦合关系及其对温度等外界条件和内在性质的依赖，探寻玻璃态形成和力学行为微观结构起源，揭示物理-力学行为机制内在关联和作用条件，以验证理论假说，提炼多时空尺度物理力学模型。本项目从微观结构层面更好的揭示玻璃态材料形成和形变机制，有助于结构力学优化和智能材料设计等实际问题的解决，是胶体模型化研究必然趋势。. 执行期内主要取得如下成果：（1）剪切流变显微观测实验系统搭建，（2）玻璃态转变起源的实验研究和玻璃态理论鉴别，（3）胶体椭球水动力相互作用的研究，（4）微流变在植物重力感应机制中应用。相关成果已发表4篇，分别发表于Nat. Commun., Plant Molecular, J. Experimental Botany, Microgravity Sci Tech 等期刊，已投稿文章2篇，后续三年内预计发表文章不少于4篇。