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: 1150862
• 负责人: Michael Demkowicz
• 金额: $ 50万
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-15 至 2016-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1150862&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.

技术摘要这一职业奖支持金属中固态界面的中尺度建模，以预测界面结构和与晶体缺陷的界面相互作用：点缺陷，错位和裂纹。这项工作将导致界面的定量结构 - 特性关系，然后可以使用该结构复合材料，其结构化材料的界面量身定制为产生所需的功能，例如高强度或断裂韧性​​，辐射或耐磨性，减少腐蚀或蠕变等。此类材料将对能源应用产生重大影响。PI将追求三个特定的科学目标。首先是创建中尺度模型，以定量描述和预测详细的界面结构。第二个是发现界面缺陷相互作用的机制，并创建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定量和假设驱动的实验来验证结构和缺陷相互作用预测。最初，该项目将仅限于所有可能的接口的子集，即在不混溶的单元素金属之间形成的半半晶体接口。可以使用不合适的脱位来描述此类接口的结构，从而简化定量结构模型的开发，并为预测接口缺陷相互作用提供了基础。在多种条件下，不混溶的金属之间的异物相界面通常保持稳定，并且不容易迁移或互化，可以放松实验研究。工作将集中在其最低能量状态的平坦接口，但具有不同的晶体学特征。只能研究一对晶体结构的金属，其晶体结构可能与均匀变形有关。异物相界面和晶界都属于该子集。将研究温度的作用，但是将对曲率，刻面，大型预先存在的外部缺陷浓度或非平衡状态的影响进行研究。该项目将考虑与三种缺陷类型的接口相互作用：点缺陷，错位和裂缝。要研究的相互作用是界面附近和内部的缺陷陷阱，发射，传输和运动。与其他类型的缺陷相互作用，例如空隙，夹杂物，点缺陷簇或其他接口 - 将不会作为该项目的一部分研究。没有基本的物理局限性可以阻止以外的界面，相互作用和缺陷类型的范围扩大未来工作的范围。该项目的教育部分将支持开发有关缺陷物理学的新班级，并修订了关于材料机械行为的退出类。所有材料以及两个课程的录像讲座都将通过MIT的OpenCourseware在全球范围内提供。该项目将通过在材料建模中提供本科研究机会来增强对未来科学家的培训，并通过MIT国际科学技术计划计划将其与国际合作融为一体。博士后经验对于科学家来说越来越重要，即熟练掌握跨越并整合不同研究领域的建模和实验结果的领先研究项目。 PI将建立一个博士后办公室，该办公室将在MIT.Non-Technical摘要职业项目中提高博士后经验，旨在通过理论和计算机建模来增强我们对金属界面的理解。界面是两个不同晶体相遇的位置，并且在工程合金中无处不在，例如钢，铝，钛等。尽管接口通常不到此类材料体积的0.01％，但它们在确定机械，电气，热和扩散性能方面起着决定性的作用。教科书经常以示意性地描绘它们为二维和突然。这种简化是方便的，通常是必要的，但从根本上是错误的：界面结构本质上是三维，通常很复杂，有时很漂亮。因此，关于界面的结构和特性还有很多待理解。对界面的改进理解可能为制造更好的工程合金提供了途径。材料的性能封装限制了技术可以完成的大部分，例如在能源应用中：从蒸汽发生器和电池到高压电源线和核反应堆，更好的材料转化为清洁，更安全，更便宜的能量。这些应用中的材料性能通常由晶体缺陷（例如空位，位错和裂缝）控制。根据这种缺陷来量身定制界面的相互作用是扩展材料的性能信封的一个途径。该项目具有三个目标。首先是开发模型，以足够的精确度捕获接口结构的完整复杂性，以进行定量预测。第二个是发现与不同结构的接口如何与控制材料性能的缺陷相互作用，并开发能够预测从界面结构中预测这些接口缺陷相互作用的能力。最后，第三个目标是验证上述界面结构和缺陷相互作用模型。所有模型都简化了假设。这项工作的一个主要目的是制定验证界面结构模型的策略，并使用理论和实验既有相互作用。由于存在无限数量的可能接口，因此该项目必须集中在其选定的子集上。因此，根据标准，将要研究的特定类型的界面类型被拒绝，这些标准使得在实现该项目的目标方面取得了快速进步的可能性最高。同样，将考虑与三种缺陷的接口相互作用：点缺陷，脱位和裂纹。但是，没有根本的物理限制可以防止将未来工作的范围扩大到最初被降低的界面，相互作用和缺陷类型的范围。该项目所涉及的缺陷和界面物理学将用于支持新班级的开发以及MIT机械机械性材料机械行为的现有类别的修订。由于麻省理工学院致力于通过OpenCourse软件等在线计划分享其教育资源，这些课程将使全球受众受益。该项目将通过MIT国际科学技术计划在MIT和国际上提供本科研究机会来增强未来科学家的培训。最后，该项目将增强麻省理工学院科学家的经验，后者最近获得了博士学位，并打算继续在研究领域建立职业。