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.

非技术摘要大多数金属都是晶体，原子在三维空间中排列成周期性阵列，并且它们的结构-性能关系已经建立，这使得它们能够作为许多现代技术中不可或缺的结构材料得到广泛应用。相比之下，金属玻璃是非晶态的，其中原子不排列成周期性阵列。尽管金属玻璃具有许多优异的性能，例如高强度和弹性，但对其变形机制缺乏基本了解阻碍了它们在许多技术领域的潜在应用。该项目旨在增进我们对金属玻璃中成分如何影响结构，特别是纳米尺度的结构异质性以及这种结构异质性如何影响其变形行为的基本理解。 假设是不同类型的中程有序的存在，即纳米尺度的局部有序原子排列，以及它们在机械加载过程中的运动导致了金属玻璃的不同变形行为。该项目结合先进的电子显微镜和多尺度计算机模拟，研究了不同金属玻璃中存在的中程有序原子结构，并建立了中程有序结构与变形行为之间的关系。在教育推广方面，该项目整合了（i）为具有不同背景的当地社区大学生提供的实习计划，为他们提供研究经验并促进他们过渡到四年制大学，以及（ii）在线研讨会，以传播金属玻璃和其他非晶材料的实验和计算方法。技术摘要该项目通过以下方式表征金属玻璃（MG）的结构异质性： 定量分析使用 4 维扫描透射电子显微镜 (4D-STEM) 获得的纳米衍射图案，提供构成 MG 结构异质性的局部中程有序 (MRO) 信息。利用实验结构数据和原子间势，基于遗传算法的StructOpt优化提供了在MRO结构与实验数据完全一致的约束下最小化势能的原子结构。由此产生的 MRO 原子构型用于后续势能景观分析，以定量了解 MRO 如何影响剪切转变区 (STZ)，包括有关独特剪切模式、活化能垒、活化体积、软化行为和局部弹性模量的关键信息。这些量化基本塑性事件的关键 STZ 参数，以及直接来自 4D-STEM 的与结构异质性相关的微观结构信息，被纳入非均匀随机 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。模拟结果探索了实验表征所揭示的各种 MRO 类型及其分布，并进行了分析，以了解在两种主要 MG 系统（即 Zr 基和 La 基 MG）中观察到的延展性和 β 弛豫显着变化的结构起源。这些发现可以显着促进对 MG 结构与性能关系的基本理解，并影响非晶材料的设计和开发。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

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