DMREF/Collaborative Research: Designing and Synthesizing Nano-Metallic Materials with Superior Properties

通常，限制车辆、发电机、土木工程结构和许多其他产品性能的主要因素是制造它们的金属的耐久性。因此，优质金属是推进美国竞争力和安全核心技术（交通、能源和基础设施）的关键。纳米金属材料包括一类有望满足这一需求的金属：它们具有极高的强度，抗反复载荷的损伤，以及许多独特的性能，如抗辐射损伤。这个研究项目解决了纳米金属材料迄今为止限制其实际应用的一个缺点。也就是说，当它们拉伸时，它们并不是均匀地拉长，而是在孤立的位置夹断。这个项目将创造出均匀拉伸的纳米金属材料，因此不容易突然失效。因此，它将消除纳米金属材料广泛技术使用的一个主要障碍，并加速其向市场的部署。该项目还将向高中教师和学生、妇女、代表性不足的少数民族的个人以及更广泛的科学界开展外联活动。尽管许多纳米金属材料本质上是延展性的，但它们似乎以脆性的方式失效，因为它们的塑性变形局限在狭窄的区域，随后断裂。该项目的目标是通过集成理论、建模和实验的迭代设计过程，设计纳米金属材料的结构、界面/表面和成分，从而创造出抵抗流动本地化的纳米金属材料。该项目将遵循一个迭代的设计-综合-测试周期，快速扫描设计空间，并通过更新连接设计参数和性能指标的理论模型，整合每次迭代中获得的见解。由于纳米金属材料具有纳米尺度的微观结构，传统的基于位错的避免流动局部化的机制并不适用。因此，本项目将探索和实施非位错机制，该机制依赖于孪晶、表面和界面应力、相干应力、界面滑移障碍、受限层滑移以及流动局部化和均匀变形成分的复合材料。

Often, the main factor limiting the performance of vehicles, power generators, civil engineering structures, and many other products is the durability of the metals they are made of. Better metals are therefore key to advancing technologies at the core of US competitiveness and security: transportation, energy, and infrastructure. Nano-metallic materials comprise a class of metals that promise to fill this need: they possess extreme strength, resistance to damage from repeated loading, and numerous unique properties such as resistance to radiation damage. This research project addresses a drawback of nano-metallic materials that has so far limited their practical use. Namely: when they stretch, they do not elongate uniformly throughout, but rather pinch off in isolated locations. This project will create nano-metallic materials that stretch uniformly and are therefore not prone to sudden failures. It will thereby remove a major impediment to the widespread technical use of nano-metallic materials and accelerate their deployment to the marketplace. This project will also undertake outreach activities to high school teachers and students, women, individuals from underrepresented minorities, and the broader scientific community. Even though many nano-metallic materials are intrinsically ductile, they appear to fail in a brittle-like manner because plastic deformation in them localizes into narrow zones that subsequently fracture. The goal of this project is to create nano-metallic materials that resist flow localization by engineering their architectures, interfaces/surfaces, and compositions via an iterative design process that integrates theory, modeling, and experiments. The project will follow an iterative design-synthesize-test cycle that scans the design space rapidly and integrates insights gained in each iteration by updating theoretical models connecting design parameters to performance metrics. Due to the nanometer-scale microstructure dimensions in nano-metallic materials, conventional dislocation-based mechanisms for averting flow localization are not applicable. Therefore, this project will explore and implement non-dislocation mechanisms that rely on twinning, surface and interface stresses, coherency stresses, interface barriers to slip, confined layer slip, and composites of flow-localizing and uniformly deforming constituents.