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

非技术描述：颗粒尺寸在100纳米以下的材料，也就是众所周知的纳米材料，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颗粒的材料高四到五倍。然而，要充分利用它们的性能，必须保持纳米微结构材料的稳定性。如果晶粒在显微组织内长大，这种特殊的性能将消失。这项提议旨在开发一种新的方法来制造纳米级微结构，以使最终材料在广泛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。本研究适用于用于航空航天、桥梁、汽车等领域的纳米材料。此外，该项目还通过教育在社区中产生了更广泛的影响。具体地说，该项目推出了“特洛伊熊猫计划”，为洛杉矶地区的低收入儿童带来了亲身实践的科学和工程项目。参与该项目的研究生领导这些课程，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。技术细节：虽然纳米结构金属材料具有许多吸引人的特性，包括高强度，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，加上错综复杂的动力学和热力学现象，使研究局限于少数几个可用的系统。为了真正开发纳米尺度的特性，迫切需要合成和了解在纳米尺度上控制热稳定性的机制。本研究提供了一种新的合成方法，通过探索从多层体系到等轴纳米晶结构的微观结构演变来获得热稳定的纳米晶材料。通过利用纳米金属多层膜(NMM)，这项研究允许合成从热力学模型中选择的各种成分，同时检查中间微结构步骤，这些步骤可以阐明不同温度下的控制机制。在这方面接受教育的研究生将通过与德国波鸿鲁尔大学的教职员工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).