Creep-Based Nanomanufacturing of Crystalline Metals and Alloys

金属材料的纳米结构对于满足催化、能量存储、传感器、过滤和药物输送方面日益增长的需求至关重要。 金属纳米结构的制造在很大程度上依赖于昂贵的光刻和薄膜沉积技术。 成型是一种高通量的纳米结构制造工艺，但金属中的大晶粒阻碍了它们在纳米级的流动。 该补助金支持晶体金属高温塑性变形的基础研究，以推进基于模塑的可扩展纳米制造。 该研究能够制造许多金属合金的高纵横比纳米结构，包括高表面积多孔金属纳米结构，这对于能量转换和存储以及生物医学应用是非常理想的。 金属纳米结构的制造研究通过推进能源，医疗保健和其他工业部门的技术，从而促进美国的竞争力和繁荣，使经济和社会受益。 该项目为各级学生提供教育和实践培训，并为他们在先进制造业中的发展做好准备。 该项目的外联活动旨在特别激励残疾学生从事科学和工程领域的职业。纳米结构通常通过软聚合物和其他玻璃质材料在其稳定的粘性状态下的模板成型来制造。 然而，类似的方法不直接适用于晶体金属，因为它们的高反应性液态和固态下的刚性微观结构特征。 本计画研究结晶金属及合金之蠕变塑性变形，以控制不同长度尺度之成型。 金属中的蠕变通常被认为对结构应用是有害的，但最近的研究表明其在可控纳米成形中的潜力。 在加工条件和原料材料的系统变化的成型实验，使不同的蠕变机制和它们的作用，在管理纳米级金属成型去耦。 该项目研究大小依赖机制，例如，位错介导的塑性，Nabarro-Herring蠕变，Coble蠕变，在金属和合金的热机械纳米成型和流动机制在模板填充作为模具尺寸，加工时间和气氛的函数。 从均质材料的成型中获得的知识应用于多相和多孔金属合金，包括高熵和共晶合金。 蠕变诱导流动的定量描述推进了对复杂合金和多孔结构中原子扩散的理解。 除了新的制造科学之外，该项目还具有在冶金学和机械学方面贡献新的基础知识的潜力。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Nanostructures of metallic materials are critical for meeting the growing demands in catalysis, energy storage, sensors, filtration, and drug-delivery. Manufacturing of metal nanostructures largely relies on expensive lithography and thin film deposition techniques. Molding is a high-throughput fabrication process for nanostructures, but the large crystal grains in metals hinder their flow at nanoscale. This grant supports fundamental research in high temperature plastic deformation of crystalline metals to advance molding-based scalable nanomanufacturing. The research enables fabrication of high aspect-ratio nanostructures of many metallic alloys including high surface-area porous metal nanostructures which are highly desirable for energy conversion and storage and biomedical applications. The manufacturing research in metal nanostructures benefits the economy and society by advancing technologies in energy, healthcare and other industrial sectors thus advancing US competitiveness and prosperity. The project provides education and hands-on training to students at all levels and prepares them for the growing industry in advanced manufacturing. The outreach activities in this project are designed to particularly inspire students with disabilities for careers in science and engineering fields. Nanostructures are routinely fabricated by templated molding of soft polymers and other glassy materials in their stable viscous state. A similar approach is however not directly applicable to crystalline metals due to their highly reactive liquid state and rigid microstructural features in the solid state. This project investigates creep-based plastic deformation of crystalline metals and alloys for controllable molding at different length scales. Creep in metals is generally considered detrimental for structural applications, but recent studies indicate its potential for controllable nanoforming. Molding experiments with systematic variation in processing conditions and feedstock material enable decoupling of different creep mechanisms and their role in governing nanoscale metal molding. The project studies size-dependent mechanisms, e.g., dislocation-mediated plasticity, Nabarro-Herring creep, and Coble creep, in thermomechanical nanomolding of metals and alloys and flow mechanisms in template filling as a function of mold size, processing time and atmosphere. The knowledge gained from molding of homogeneous materials is applied to multi-phase and porous metal alloys, including high-entropy and eutectic alloys. Quantitative descriptions of creep induced flow advances the understanding of atomic diffusion in complex alloys and porous structures. Besides novel manufacturing science, the project has the potential to contribute new fundamental knowledge in metallurgy and mechanics.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.