Collaborative Research: Experimentally Informed Modeling of Structural Heterogeneity and Deformation of Metallic Glasses

合作研究：金属玻璃结构异质性和变形的实验知情建模

• 批准号: 2104724
• 负责人: Jinwoo Hwang
• 金额: $ 49.93万
• 依托单位: Ohio State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2104724&HistoricalAwards=false
• 关键词: Collaborative; Research; Experimentally; Informed; Modeling

Non-Technical SummaryMost metals are crystalline where atoms arrange into periodical arrays in 3-dimensions and their structure-property relationships have been well-established, which have enabled their widespread applications as indispensable structural materials in numerous modern technologies. In contrast, metallic glasses are amorphous where atoms do not arrange into periodical arrays. Despite many exceptional properties found in metallic glasses such as high strength and elasticity, the lack of fundamental understanding of their deformation mechanisms has hindered their potential applications in many technical areas. This project seeks to advance our fundamental understanding on how composition affects the structure, in particular, structural heterogeneity at the nanoscale, in metallic glasses and how such structural heterogeneity affects their deformation behavior. The hypothesis is that the presence of different types of medium range ordering, i.e., locally ordered atomic arrangements at the nanometer scale, and their motion during mechanical loading are responsible for different deformation behaviors of metallic glasses. Using a combination of advanced electron microscopy and multiscale computer simulations, this project investigates the atomic structures of medium range ordering present in different metallic glasses and establish a relationship between medium range ordering structures and deformation behavior. For educational outreach, the project integrates (i) an internship program for local community college students with diverse backgrounds, which provides them with research experience and facilitate their transition to 4-year universities, and (ii) online workshops for dissemination of the experimental and computational approaches for metallic glasses and other amorphous materials.Technical SummaryThis project characterize structural heterogeneities in metallic glasses (MGs) at the nanometer scale by quantitatively analyzing nanodiffraction patterns acquired using 4-dimensional scanning transmission electron microscopy (4D-STEM), which provides the information on local medium-range ordering (MRO) that constitutes the MGs’ structural heterogeneities. Using the experimental structure data, together with interatomic potentials, the genetic-algorithm-based StructOpt optimization provides atomic structures that minimize the potential energy under the constraint of MRO structures being fully consistent with the experimental data. The resulting atomistic configurations of MROs are used for subsequent potential energy landscape analysis to gain quantitative understanding on how the MROs affect shear transformation zones (STZs), including the key information on distinctive shear modes, activation energy barrier, activation volume, softening behavior, and local elastic moduli. These crucial STZ parameters that quantify the elementary plastic events, along with the microstructural information related to the structural heterogeneity directly from 4D-STEM, are incorporated into a heterogeneously randomized STZ dynamic model to perform deformation simulations at the length and time scales relevant to real-world experiments. The results from the simulations, which explore various MRO types and their distribution revealed by the experimental characterization, are analyzed to gain understanding of the structural origins of the substantial variations in ductility and β-relaxation observed in two major MG systems, i.e., the Zr-based and La-based MGs. These findings could advance significantly the fundamental understanding of structure-property relationship in MGs and impact the design and development of amorphous materials.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.

非技术总结最多金属是结晶，其中原子排列在三维中的定期阵列及其结构 - 培训关系已建立了良好的建立，这使其在许多现代技术中都可以作为不可或缺的结构材料作为不可或缺的结构材料。相比之下，金属玻璃是无定形的，原子不排列在周期阵列中。尽管在高强度和弹性等金属眼镜中发现了许多非凡的特性，但对其变形机制的根本理解缺乏基本的理解阻碍了它们在许多技术领域的潜在应用。该项目旨在促进我们对组成如何影响结构的基本理解，尤其是纳米级的结构异质性，金属眼镜以及这种结构异质性如何影响其变形行为。假设是，存在不同类型的中范围排序的存在，即在纳米尺度上局部有序的原子排列，其在机械载荷期间的运动负责金属玻璃的不同变形行为。该项目结合了高级电子显微镜和多尺度计算机模拟，研究了存在于不同金属玻璃中的中范围排序的原子结构，并在中等范围排序结构和变形行为之间建立了关系。对于教育宣传，该项目将（i）针对具有潜水员背景的当地社区大学生的实习计划，为他们提供了研究经验并支持他们向4年大学的过渡，以及（ii）在线研讨会，用于传播金属玻璃和其他不惯性材料的实验和计算方法的实验和计算方法。分析使用4维扫描透射电子显微镜（4D-STEM）获得的纳米施法模式，该模式提供了构成MGS结构异质性的局部中范围订购（MRO）的信息。使用实验结构数据，以及原子间电位，基于遗传叠加的结构优化提供了原子结构，可将MRO结构约束下的势能最小化，完全与实验数据一致。 MRO的产生的原子构型用于随后的势能景观分析，以对MROS如何影响剪切转化区（STZ）获得定量理解，包括有关独特剪切模式，激活能量屏障，激活量，软化行为，软化行为和局部弹性Modulli的关键信息。将量化基本塑料事件的这些至关重要的STZ参数以及直接来自4D-STEM的结构异质性相关的微观结构信息被纳入一个异质随机的STZ动态模型中，以在与现实世界实验相关的长度和时间尺度上执行变形模拟。分析了探索各种MRO类型的模拟的结果，并通过实验表征揭示了它们的分布，以了解在两个主要的MG系统中观察到的延展性和β-浮肿的实质变化的结构起源，即基于ZR的基于ZR和LA的MG。这些发现可以显着提高对MGS结构性关系的基本理解，并影响非晶材料的设计和开发。该奖项反映了NSF的法定任务，并通过使用该基金会的知识分子和更广泛的影响来审查标准，被认为是通过评估来获得的支持。

项目成果

Deciphering the Structure of Amorphous Functional Materials using 4D-STEM

使用 4D-STEM 解读非晶功能材料的结构

• DOI: 10.1093/micmic/ozad067.144
• 发表时间: 2023
• 期刊: Microscopy and Microanalysis
• 影响因子: 2.8
• 作者: Ortiz, Gabriel Calderón;Im, Soohyun;Abbasi, Mehrdad;Islam, Minhazul;Hwang, Jinwoo
• 通讯作者: Hwang, Jinwoo

Medium-range ordering, structural heterogeneity, and their influence on properties of Zr-Cu-Co-Al metallic glasses

• DOI: 10.1103/physrevmaterials.5.115604
• 发表时间: 2021-11-15
• 期刊: PHYSICAL REVIEW MATERIALS
• 影响因子: 3.4
• 作者: Im, Soohyun;Wang, Yuchi;Hwang, Jinwoo
• 通讯作者: Hwang, Jinwoo