CAREER: Connecting interface structure to interface-defect interactions in metals

职业：将界面结构与金属中的界面缺陷相互作用联系起来

• 批准号: 1646954
• 负责人: Michael Demkowicz
• 金额: $ 10.25万
• 依托单位: Texas A&M Engineering Experiment Station
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1646954&HistoricalAwards=false
• 关键词: CAREER; Connecting; interface; structure; defect

TECHNICAL SUMMARYThis CAREER award supports mesoscale modeling of solid-state interfaces in metals, with a view to predicting interface structure and interface interactions with crystals defects: point defects, dislocations, and cracks. This effort will lead to quantitative structure-property relations for interfaces, which may then be used to design structural composite materials with interfaces tailored to yield desired functionalities, such as high strength or fracture toughness, radiation or wear resistance, reduced corrosion or creep, and others. Such materials would have a major impact on energy applications.The PI will pursue three specific scientific objectives. The first is to create mesoscale models that quantitatively describe and predict detailed interface structure. The second is to discover the mechanisms of interface-defect interactions, and create quantitative mesoscale models of these mechanisms. Finally, the third objective is to validate structure and defect interaction predictions through numerical uncertainty quantification and hypothesis-driven experiments. Initially, this project will be restricted to a subset of all possible interfaces, namely semicoherent interfaces formed between immiscible single-element metals. The structure of such interfaces may be described using misfit dislocations, which eases development of quantitative structure models and provides a basis for predicting interface-defect interactions. Heterophase interfaces between immiscible metals generally remain stable under a variety of conditions and do not migrate or intermix easily, easing experimental investigation.Work will focus on flat interfaces in their lowest energy state, but with differing crystallographic characters. Only pairs of metals whose crystal structures may be related to the face-centered-cubic structure by uniform deformations will be studied. Both heterophase interface and grain boundaries fall within this subset. The effect of temperature will be studied, but investigations of the effects of curvature, faceting, large pre-existing extrinsic defect concentrations, or non-equilibrium state will be postponed. This project will consider interface interactions with three types of defects: point defects, dislocations, and cracks. The interactions to be studied are defect trapping, emission, transmission, and motion near and within interfaces. Interactions with other types of defects - such as voids, inclusions, point defect clusters, or other interfaces - will not be studied as part of this project. There are no fundamental physical limitations that prevent broadening the scope of future work to interfaces, interactions, and defect types other than those listed above.The education component of this project will support the development of a new class on defect physics and the revision of an exiting class on mechanical behavior of materials. All materials as well as videotaped lectures for both classes will be made available worldwide through MIT's OpenCourseWare. This project will enhance the training of future scientists by providing undergraduate research opportunities in materials modeling and integrating their work with international collaborations through the MIT International Science and Technology Initiatives program. Postdoctoral experience is increasingly critical for scientists to gain proficiency in leading research projects that span across and integrate both modeling and experimental results from different fields of study. The PI will establish a postdoc office that will undertake to enhance the postdoc experience at MIT.NON-TECHNICAL SUMMARYThis CAREER project aims to increase our understanding of interfaces in metals through theory and computer modeling. Interfaces are locations where two different crystals meet and are ubiquitous in engineering alloys such as steel, aluminum, titanium, and many others. Although interfaces typically comprise less than 0.01% of the volume of such materials, they play a decisive role in determining their mechanical, electrical, thermal, and diffusion properties. Textbooks often portray them schematically as two-dimensional and abrupt. This simplification is convenient and often necessary, but fundamentally false: interface structure is inherently three dimensional, often complex, and occasionally quite beautiful. Thus, much remains to be understood about the structure and properties of interfaces.An improved understanding of interfaces may provide a path to making better engineering alloys. The performance envelope of materials limits much of what technology can accomplish, for example in energy applications: from steam generators and batteries to high-voltage power lines and nuclear reactors, better materials translate into cleaner, safer, and cheaper energy. Materials performance in these applications is often controlled by crystal defects, such as vacancies, dislocations, and cracks. Tailoring the interactions of interfaces with such defects is one path to expanding the performance envelope of materials.This project has three objectives. The first is to develop models that capture the full complexity of interface structure with enough precision to make quantitative predictions. The second is to discover how interfaces with different structures interact with defects that control materials performance and to develop the capability to predict these interface-defect interactions from interface structure. Finally, the third objective is to validate the interface structure and defect interaction models described above. All models make simplifying assumptions. A major goal of this work is to develop strategies for validating models of interface structure and defects interactions using both theory and experiments.Because there is an infinite number of possible interfaces, this project has to focus on a selected subset of them. The specific types of interfaces to be studied have therefore been downselected based on criteria that give the highest likelihood of making rapid progress towards achieving the goals of this project. Similarly, interactions of interfaces with only three types of defects will be considered: point defects, dislocations, and cracks. There are, however, no fundamental physical limitations that prevent broadening the scope of future work to interfaces, interactions, and defect types other than those initially downselected.The defect and interface physics involved in this project will be used to support the development of a new class and the revision of an existing class on mechanical behavior of materials at MIT. Thanks to MIT's commitment to share its educational resources through online programs such as OpenCourseWare, these classes will benefit a worldwide audience. This project will enhance the training of future scientists by providing undergraduate research opportunities both at MIT and internationally through the MIT International Science and Technology Initiatives program. Finally, this project will enhance the experience of scientists at MIT who recently received their PhDs and intend to continue building a career in research.

该职业奖支持金属固体界面的中尺度建模，以预测界面结构和界面与晶体缺陷的相互作用：点缺陷、位错和裂纹。这一努力将导致界面的定量结构-性能关系，然后可用于设计具有定制界面的结构复合材料，以获得所需的功能，例如高强度或断裂韧性，耐辐射或耐磨性，减少腐蚀或蠕变等。这类材料将对能源应用产生重大影响。PI将追求三个具体的科学目标。首先是建立中尺度模型，定量地描述和预测详细的界面结构。二是发现界面-缺陷相互作用的机制，并建立这些机制的定量中尺度模型。最后，第三个目标是通过数值不确定性量化和假设驱动实验来验证结构和缺陷相互作用预测。最初，该项目将局限于所有可能界面的子集，即不混相单元素金属之间形成的半相干界面。这种界面的结构可以用错配位错来描述，这简化了定量结构模型的开发，并为预测界面缺陷相互作用提供了基础。不混相金属之间的异相界面在各种条件下通常保持稳定，不易迁移或混合，便于实验研究。工作将集中在其最低能态的平面界面上，但具有不同的晶体学特征。只研究那些晶体结构可能与均匀变形的面心立方结构相关的金属对。异相界面和晶界都属于这个子集。温度的影响将被研究，但曲率、表面、大量预先存在的外部缺陷浓度或非平衡状态的影响的研究将被推迟。这个项目将考虑三种类型缺陷的界面相互作用：点缺陷、位错和裂纹。要研究的相互作用是缺陷捕获、发射、传输以及在界面附近和内部的运动。与其他类型缺陷的相互作用——如空洞、夹杂物、点缺陷簇或其他接口——将不作为本项目的一部分进行研究。没有基本的物理限制阻止将未来的工作范围扩展到接口、交互和缺陷类型，而不是上面列出的那些。这个项目的教育部分将支持开设一个关于缺陷物理学的新课程，并修订现有的关于材料力学行为的课程。这两门课的所有材料和视频讲座都将通过麻省理工学院的开放式课件在全球范围内提供。该项目将通过提供材料建模的本科生研究机会，并通过麻省理工学院国际科学与技术倡议计划将他们的工作与国际合作结合起来，从而加强对未来科学家的培训。博士后经历对于科学家熟练掌握跨越和整合不同研究领域的建模和实验结果的领先研究项目越来越重要。PI将建立一个博士后办公室，负责提高麻省理工学院博士后的经验。这个职业项目旨在通过理论和计算机建模来增加我们对金属界面的理解。界面是两种不同晶体相遇的地方，在工程合金如钢、铝、钛和许多其他合金中无处不在。虽然界面通常只占这类材料体积的0.01%，但它们在决定材料的机械、电学、热学和扩散性能方面起着决定性的作用。教科书经常把它们描绘成二维的、突兀的。这种简化是方便且必要的，但从根本上说是错误的：界面结构本质上是三维的，通常是复杂的，偶尔也很漂亮。因此，关于界面的结构和性质还有许多有待了解的地方。对界面的进一步了解可能为制造更好的工程合金提供一条途径。材料的性能限制了技术所能完成的许多事情，例如在能源应用方面：从蒸汽发生器和电池到高压电线和核反应堆，更好的材料转化为更清洁、更安全、更便宜的能源。在这些应用中，材料的性能通常受到晶体缺陷的控制，如空位、位错和裂纹。裁剪具有此类缺陷的界面的相互作用是扩展材料性能范围的途径之一。这个项目有三个目标。第一种是开发模型，以足够的精度捕捉界面结构的全部复杂性，从而进行定量预测。第二是发现具有不同结构的界面如何与控制材料性能的缺陷相互作用，并开发从界面结构预测这些界面-缺陷相互作用的能力。最后，第三个目标是验证上面描述的接口结构和缺陷交互模型。所有模型都简化了假设。这项工作的一个主要目标是利用理论和实验来开发验证界面结构和缺陷相互作用模型的策略。因为有无数可能的接口，所以本项目必须关注其中的一个选定子集。因此，要研究的特定类型的接口已经根据最有可能快速实现本项目目标的标准进行了选择。类似地，只有三种缺陷的界面的相互作用将被考虑：点缺陷，位错和裂纹。然而，没有基本的物理限制阻止将未来的工作范围扩展到接口、交互和缺陷类型，而不是最初选择的那些。本项目涉及的缺陷和界面物理将用于支持麻省理工学院材料力学行为新课程的开发和现有课程的修订。感谢麻省理工学院通过开放课程等在线项目分享其教育资源的承诺，这些课程将使全世界的观众受益。该项目将通过在麻省理工学院和国际上通过麻省理工学院国际科学与技术倡议计划提供本科生研究机会，从而加强对未来科学家的培训。最后，这个项目将增强麻省理工学院最近获得博士学位并打算继续在研究领域发展的科学家的经验。