Correlating structural heterogeneity to deformation in metallic glasses

将金属玻璃的结构异质性与变形相关联

• 批准号: 1709290
• 负责人: Jinwoo Hwang
• 金额: $ 45万
• 依托单位: Ohio State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-07-01 至 2021-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1709290&HistoricalAwards=false
• 关键词: Correlating; structural; heterogeneity; deformation; metallic

Non-Technical SummaryThis award supports an integrated experimental and computational study of structure-property relationship of metallic glasses (MGs). Glasses are ubiquitous in nature, and many of them have superior properties (much better than crystals) that can be utilized for important applications. For example, metallic glasses (MGs) are multi-component metallic alloys with glassy (disordered) atomic structure, and their excellent properties, including high strength and elastic energy, have shown great promises for novel structural applications. However, such applications are currently limited by the poor ductility of MGs. To understand the deformation behavior of MGs, it is required to understand their atomic structure and how structural heterogeneities at different length scales influence the way they plastically deform. Using a unique combination of advanced electron microscopy and mesoscale computer simulation, the PIs will investigate how the local atomic ordering that is inherited from processing of the MGs affects their important mechanical properties, and seek opportunities to improve MG ductility by engineering structural heterogeneities at the nanoscale through adjusting alloy composition and heat treatment. The PIs will use electron microscopy techniques for the educational component of this award to introduce science and engineering of MGs to K12 students and teachers, including students with disabilities, and to motivate them to choose science and engineering as their college major and to pursue their careers in these fields.Technical SummaryThis award supports an integrated experimental and computational study of the correlation between nanoscale structural heterogeneities and deformation behavior of metallic glasses (MGs). In particular, the PIs will use nanodiffraction combined with two advanced analysis methods (fluctuation microscopy and angular correlation function) to reveal the details of medium range (nanoscale) atomic orders (MROs) in MGs, including their type, size, volume fraction, and distribution, at an unprecedented quantitative level. These structural details will be characterized as function of composition and thermal history of the MGs and correlated to their deformation behavior. The PIs will then incorporate the experimentally determined MRO information into mesoscale computer simulations based on a heterogeneously randomized shear transformation zone (STZ) model to establish new understanding on how the MROs affect shear banding and overall deformation. The possible connection between MRO and STZs will be investigated by first assuming a set of deformation rules in the simulations according to the detailed MRO structures revealed by the nanodiffraction, and then matching the simulation results (including overall ductility and shear banding patterns) to the experimental observations. Such a fully integrated experimental and computational study will provide important insights into how the nanoscale structural heterogeneity affects STZ activation and the overall deformation. Through this award the PIs will probe nanoscale structural heterogeneities in MGs beyond the limits of the conventional characterization methods, and reveal important connections among composition, thermal history, MRO, and mechanical properties. Simulations incorporating the experimentally determined structural heterogeneity will offer new insights into how structural heterogeneities at the nanoscale in MGs affect their overall deformation behavior beyond the spatial and temporal limits of previous simulations. This award will also provide insights into how the nanoscale structural heterogeneity is related to the previously suggested plasticity carriers and structural defects in MGs, such as STZ, free volume distribution, and the recently suggested geometrically unfavored motifs. The new structure-property relationship established will provide new possibilities in designing MGs with enhanced mechanical properties (in particular, ductility) by tuning the nanoscale structural heterogeneities.

非技术摘要这一奖项支持金属眼镜（MGS）结构质体关系的综合实验和计算研究。眼镜本质上是普遍存在的，其中许多具有优越的特性（比晶体好得多），可用于重要的应用。例如，金属玻璃（MGS）是具有玻璃（无序）原子结构的多组分金属合金，其优秀特性（包括高强度和弹性能）对新型结构应用表现出了巨大的希望。但是，此类应用目前受到MGS延展性不佳的限制。要了解MGS的变形行为，需要了解其原子结构以及在不同长度尺度下的结构异质性如何影响它们塑性变形的方式。使用高级电子显微镜和中尺度计算机模拟的独特组合，PI将研究如何通过处理MGS处理而遗传的局部原子订购会影响其重要的机械性能，并寻求机会通过调整Alloy组成和热处理和热处理来改善纳米级的工程结构异质性来改善MG延展性。 PI将使用电子显微镜技术作为该奖项的教育组成部分，以向K12学生和老师（包括残疾学生）介绍MGS的科学和工程学，并激励他们选择科学和工程学作为他们的大学专业，并在这些领域中从事自己的职业，并在这些领域中追求他们的职业。金属眼镜（MGS）。特别是，PI将使用纳米式曲线以及两种先进的分析方法（波动显微镜和角相关函数）来揭示MGS中中等范围（Nansoscale）原子订单（MROS）的细节，包括它们的类型，大小，体积分数和分布，在空前的定量级别上。这些结构细节将以MGS的组成和热历史的函数为特征，并与它们的变形行为相关。然后，PI将基于异质随机剪切转化区（STZ）模型将实验确定的MRO信息纳入中尺度计算机模拟中，以建立对MRO如何影响剪切谱带和整体变形的新理解。首先根据模拟中的一组变形规则来研究MRO和STZ之间的可能连接，根据纳米式Fraction揭示的详细MRO结构，然后将模拟结果（包括整体延展性和剪切束带模式）与实验观测值相匹配。这样的完全集成的实验和计算研究将为纳米级结构异质性如何影响STZ激活和整体变形提供重要见解。通过该奖项，PI将在MGS中探测纳米级的结构异质性，超出了传统表征方法的限制，并揭示了组成，热历史，MRO和机械性能之间的重要连接。结合实验确定的结构异质性的模拟将为MGS中纳米级的结构异质性如何影响其整体变形行为，而不是先前模拟的空间和时间限制。该奖项还将提供有关纳米级结构异质性如何与先前建议的可塑性载体和MGS中的结构缺陷有关的见解，例如STZ，自由体积分布以及最近建议的几何不利主题。建立的新结构 - 陶艺关系将通过调整纳米级结构异质性来设计具有增强机械性能（尤其是延性）的MGS的新可能性。

项目成果

Direct determination of structural heterogeneity in metallic glasses using four-dimensional scanning transmission electron microscopy

• DOI: 10.1016/j.ultramic.2018.09.005
• 发表时间: 2018-12-01
• 期刊: ULTRAMICROSCOPY
• 影响因子: 2.2
• 作者: Im, Soohyun;Chen, Zhen;Hwang, Jinwoo
• 通讯作者: Hwang, Jinwoo

Connecting Structural Heterogeneity to Properties of Disordered Materials

将结构异质性与无序材料的特性联系起来

• DOI: 10.1017/s1431927620015615
• 发表时间: 2020
• 期刊: Microscopy and Microanalysis
• 影响因子: 2.8
• 作者: Im, Soohyun;Ortiz, Gabriel Calderon;Gharacheh, Mehrdad Abbasi;Williams, Robert;Hwang, Jinwoo
• 通讯作者: Hwang, Jinwoo

Influence of nanoscale structural heterogeneity on shear banding in metallic glasses

• DOI: 10.1016/j.actamat.2017.05.057
• 发表时间: 2017-08
• 期刊: Acta Materialia
• 影响因子: 9.4
• 作者: P. Zhao;Ju Li;Jinwoo Hwang;Yunzhi Wang

Probing Nanoscale Structural Heterogeneity in Metallic Glasses Using 4-D STEM

使用 4-D STEM 探测金属玻璃中的纳米级结构异质性

• DOI: 10.1017/s1431927618001502
• 发表时间: 2018
• 期刊: Microscopy and Microanalysis
• 影响因子: 2.8
• 作者: Im, Soohyun;Chen, Zhen;Johnson, Jared M.;Zhao, Pengyang;Yoo, Geun Hee;Park, Eun Soo;Wang, Yunzhi;Muller, David A.;Hwang, Jinwoo
• 通讯作者: Hwang, Jinwoo

New Insights into Deformation of Metallic Glasses by Combining Mesoscale Simulation and Fluctuation Electron Microscopy

• DOI: 10.1017/s1431927616008023
• 发表时间: 2016-07
• 期刊: Microscopy and Microanalysis
• 影响因子: 2.8
• 作者: P. Zhao;Soohyun Im;Jinwoo Hwang;Yunzhi Wang