Investigation of pathways for nanoscale high temperature stability via nano-metallic multilayers

非技术描述：粒度小于100 nm的材料，更好地称为纳米材料，提供了许多特殊的性能。例如，具有纳米级微结构的材料的强度可以比较大晶粒的对应物高四到五倍。然而，为了充分利用其性能，必须保持具有纳米级微结构的材料的稳定性。如果晶粒在微观结构中长大，那么这些非凡的特性就会消失。该提案旨在开发一种制造纳米级微结构的新方法，以使最终材料在很宽的温度范围内非常稳定。重点是了解如何保持稳定性以及如何制造许多不同类型的金属合金系统。该研究适用于航空航天、桥梁、汽车等领域的纳米材料。此外，该项目通过教育在社区产生了更广泛的影响。具体而言，该项目推出“特洛伊熊猫计划”，为洛杉矶地区的低收入儿童带来动手实践的科学和工程项目。参与该项目的研究生领导这些会议，让K-6学生接触科学和工程概念，同时培养对STEM领域的兴趣。 技术规格：虽然纳米结构金属材料具有包括高强度在内的许多吸引人的性质，但它们通常表现出较差的热稳定性，这严重限制了它们的应用。合成金属纳米结构的复杂性加上复杂的动力学和热力学现象，使研究局限于少数可用的系统。为了真正利用纳米级特性，迫切需要合成和理解在纳米级控制热稳定性的机制。本研究提供了一种新的合成方法，以实现热稳定的纳米晶材料，通过探索从多层系统的微观结构演变为等轴纳米晶结构。通过利用纳米金属多层膜（nano-metallic multilayers），本研究允许从热力学模型中选择的广泛的组合物的合成，同时检查可以阐明在各种温度下的控制机制的中间微观结构步骤。在这项工作中接受教育的研究生将通过与德国波鸿鲁尔大学及其先进材料模拟跨学科中心（ICAMS）的合作获得国际经验。

NON-TECHNICAL DESCRIPTION: Materials with grain sizes below 100 nm, better known as nanomaterials, provide many exceptional properties. For example, the strength of a material with nanoscale microstructure can be four to five times higher than a larger grain counterpart. However, to fully exploit their performance, the stability of the materials with nanoscale microstructure must be maintained. If grains grow within the microstructure, the extraordinary properties will disappear. This proposal aims to develop a new method to fabricate nanoscale microstructures in such a way that the final material is very stable for a wide range of temperatures. The focus is on understanding how to maintain stability and how to fabricate many different types of metal alloy systems. This research is applicable to nanomaterials used in aerospace, bridges, automotive, and other fields. Additionally, the project has broader impact in the community through education. Specifically, this project launches the "Trojan Panda Program", which brings hands-on science and engineering projects to low-income children in the Los Angeles area. The graduate students involved in the project lead these sessions to expose K-6 students to science and engineering concepts while fostering an interest in STEM fields. TECHNICAL DETAILS: Though nanostructured metallic materials have many attractive properties including high strength, they generally exhibit poor thermal stability which severely limits their application. The complexity of synthesizing metallic nanostructures coupled with convoluted kinetic and thermodynamic phenomena have confined research to a few available systems. To truly exploit nanoscale properties there is a critical need to synthesize and understand the mechanisms that control thermal stability at the nanoscale. This research provides a novel synthesis approach to achieve thermally stable nanocrystalline materials by exploring the microstructural evolution from a multilayered system to an equiaxed nanocrystalline structure. By utilizing nano metallic multilayers (NMMs), this research allows for the synthesis of a wide range of compositions selected from thermodynamic models, while examining intermediate microstructural steps that can elucidate the controlling mechanisms at various temperatures. The graduate students educated in this effort will gain international experience through collaboration with faculty at Ruhr Universität, Bochum in Germany and their Interdisciplinary Center for Advanced Materials Simulations (ICAMS).