In situ TEM mechanical molding of intermetallic nanowires

金属间化合物纳米线的原位 TEM 机械成型

• 批准号: 2240956
• 负责人: Judy Cha
• 金额: $ 54.12万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2240956&HistoricalAwards=false
• 关键词: situ; TEM; mechanical; molding; intermetallic

Non-technical SummaryLarge-scale manufacturing of nanostructures with controlled shapes and high sample quality will be transformative for many applications, such as sensing, catalysis, plasmonic and electronic applications, yet still challenging to achieve. Recently, thermomechanical molding, in which bulk feedstocks are pressed onto a mold with nano-sized pores, has shown the ability to fabricate large arrays of single-crystalline nanowires with well-controlled diameters and lengths, thus having broad implications for the many applications listed above. However, how these nanowires are formed during thermomechanical molding is not well understood, severely limiting the broad applicability of this technique. This project aims to fundamentally understand the molding process at the atomic scale by the use of in situ transmission electron microscopy (TEM) to directly observe in real-time the formation of nanowires of metallic systems during thermomechanical molding. Such new knowledge will help to improve the thermomechanical molding technique by providing the underlying science during processing in order to better select the processing conditions needed to control the dimensions and aspect ratios of these manufactured nanowires and be applicable to a broader class of materials that can be thermomechanically molded, and allow for more facile production of large quantities of nanoscale materials. Additionally, the project will provide research opportunities to undergraduate students to perform research in nanoscale metallic systems, thus preparing them for career opportunities in advanced nanomanufacturing. The in situ TEM movies will be shared with K-12 students and the general public in order to educate and engage the public in nano- science and manufacturing.Technical SummaryNanoscale thermomechanical molding, in which bulk feedstocks are pressed onto a mold with nanoscale channels at a fraction of the melting temperature, has recently demonstrated the capability to produce large arrays of single-crystalline nanowires of ordered phases. This project aims to understand the diffusion process of the thermomechanical molding by atomic scale structure characterization using transmission electron microscopy (TEM), both ex situ and in situ, with various intermetallic and solid-solution systems. The process of recrystallization, the mechanism in which a single-crystalline nanowire is extruded out from a polycrystalline bulk feedstock, will be examined in detail to explain diffusion dynamics that are tightly regulated by lowering of the Gibbs free energy, which depends quite sensitively to the stoichiometry of the intermetallics or solid solution. In situ TEM provides real-time information on the diffusion mechanism that could also demonstrate the exclusion of common dislocation slips and grain boundary movements. In summary, the project will provide atomic scale information on nanoscale solid diffusion processes of intermetallics and solid solutions, which is currently largely unexplored. Such direct visualization of solid diffusion in confined channels will also help to establish a better understanding of creep behaviors at the nanoscale. This new knowledge will help develop thermomechanically molding as a more facile and tailored production method of nanoscale materials for a broad range of technical applications. For outreach, the in situ TEM movies obtained under the project will be used as visual tools to educate K-12 students and general public about the fundamental aspects of atomic motions and their relevance to nanomanufacturing.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.

具有控制形状和高样本质量的纳米结构的非技术总结规模制造对于许多应用，例如感应，催化，等离子体和电子应用将是有影响力的，但仍然具有挑战性。 最近，将散装原料按在带有纳米大小的毛孔的模具上的热机械成型表明能够制造大量的单晶纳米线，并具有良好的控制直径和长度，从而对上面列出的许多应用具有广泛的影响。 但是，在热机械成型过程中如何形成这些纳米线尚未得到充分了解，从而严重限制了该技术的广泛适用性。该项目的目的是通过使用原位传输电子显微镜（TEM）从根本上理解原子尺度的成型过程，以实时观察热力学成型过程中金属系统的纳米线的形成。 这样的新知识将通过在处理过程中提供基础科学来帮助改善热机械成型技术，以便更好地选择控制这些制造的纳米线的尺寸和宽高比所需的处理条件，并适用于可以热机械塑造的更广泛的材料，并可以更多地生产大量纳米级材料的大量生产。 此外，该项目将为本科生提供研究机会，以在纳米级金属系统中进行研究，从而为他们做好准备在高级纳米制造方面的职业机会。 原地电影将与K-12学生和公众共享，以教育和吸引公众参与纳米科学和制造业。技术摘要摘要热力学模制，其中将散装原料压接到纳米级频道上的模具上，以融化的温度占据融化的能力，可以订购大型nan nan anan nan-carlays and and and。该项目旨在了解使用透射电子显微镜（TEM）的原子尺度结构表征的热机械成型的扩散过程，包括异地和原位，具有各种金属间和实心系统。将详细检查重结晶的过程，即从多晶体散装原料中挤出单晶纳米线的机制，以解释通过降低吉布斯自由能的降低，这很敏感地取决于固定剂或固体固体固定剂或固体固件的稳态。原位TEM提供了有关扩散机制的实时信息，该信息还可以证明排除常见位错滑和晶界运动的排除。 总而言之，该项目将提供有关金属间和实心解决方案的纳米级固体扩散过程的原子量表信息，目前尚未探索。 这种直接可视化在密闭通道中的固体扩散也将有助于更好地理解纳米级的蠕变行为。这些新知识将有助于开发热机械成型，作为一种更容易量身定制的纳米级材料生产方法，用于广泛的技术应用。对于宣传，该项目下获得的原位电影将被用作视觉工具，以教育K-12学生和公众有关原子动作的基本方面及其与纳米制造的相关性。这项奖项反映了NSF的法定任务，并通过评估该基金会的知识点功能和广泛的影响来评估NSF的法定任务。

项目成果

Nanomolding of metastable Mo4P3

• DOI: 10.1016/j.matt.2023.03.023
• 发表时间: 2023-04
• 期刊: Matter
• 影响因子: 18.9
• 作者: M. Kiani;Quynh P Sam;Gangtae Jin;B. Pamuk;H. Han;J. Hart;J.R. Stauff;J. Cha