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.

技术摘要该职业奖支持金属中固态界面的介观建模，以预测界面结构以及与晶体缺陷（点缺陷、位错和裂纹）的界面相互作用。这项工作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，以产生所需的功能，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。此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。第一个是创建定量描述和预测详细界面结构的介观模型。第二是发现界面-缺陷相互作用的机制，并创建这些机制的定量介观模型。最后，第三个目标是通过数值不确定性量化和假设驱动的实验来验证结构和缺陷相互作用的预测。最初，该项目将仅限于所有可能界面的子集，即不混溶的单元素金属之间形成的半相干界面。此类界面的结构可以使用失配位错来描述，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。不混溶金属之间的异相界面通常在各种条件下保持稳定，并且不易迁移或混合，从而简化了实验研究。工作将集中在最低能量状态下的平坦界面，但具有不同的晶体学特征。仅研究其晶体结构可能通过均匀变形与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。将研究温度的影响，但对曲率、刻面、大量预先存在的外在缺陷浓度或非平衡态影响的研究将被推迟。该项目将考虑与三种类型缺陷的界面相互作用：点缺陷、位错和裂纹。要研究的相互作用包括界面附近和界面内的缺陷捕获、发射、传输和运动。与其他类型缺陷（例如空隙、夹杂物、点缺陷簇或其他界面）的相互作用将不会作为该项目的一部分进行研究。除了上面列出的之外，不存在任何基本的物理限制阻止未来工作范围扩大到界面、相互作用和缺陷类型。该项目的教育部分将支持缺陷物理新课程的开发以及材料机械行为现有课程的修订。这两门课程的所有材料和讲座录像都将通过麻省理工学院的开放课程在全球提供。该项目将通过提供材料建模方面的本科生研究机会，并通过麻省理工学院国际科学技术计划项目将他们的工作与国际合作相结合，加强对未来科学家的培训。博士后经验对于科学家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越来越重要。 PI 将建立一个博士后办公室，致力于增强麻省理工学院的博士后经验。非技术摘要该职业项目旨在通过理论和计算机建模增进我们对金属界面的理解。界面是两种不同晶体相遇的位置，在钢、铝、钛等工程合金中普遍存在。尽管界面通常占此类材料体积的不到 0.01%，但它们在确定其机械、电、热和扩散性能方面起着决定性作用。教科书经常将它们示意性地描述为二维且突然的。这种简化很方便，而且通常是必要的，但从根本上来说是错误的：界面结构本质上是三维的，通常很复杂，有时也很漂亮。因此，关于界面的结构和性能还有很多需要了解的地方。对界面的更好的理解可能为制造更好的工程合金提供一条途径。材料的性能范围限制了技术所能实现的大部分功能，例如在能源应用中：从蒸汽发生器和电池到高压输电线和核反应堆，更好的材料可以转化为更清洁、更安全和更便宜的能源。这些应用中的材料性能通常由晶体缺陷控制，例如空位、位错和裂纹。定制具有此类缺陷的界面的相互作用是扩展材料性能范围的一种途径。该项目有三个目标。首先是开发模型，以足够的精度捕获界面结构的全部复杂性，以进行定量预测。第二个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与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交互模型。所有模型都做出简化假设。这项工作的一个主要目标是开发利用理论和实验来验证界面结构和缺陷相互作用模型的策略。由于可能的界面有无数个，因此该项目必须重点关注其中选定的子集。因此，根据最有可能在实现该项目目标方面取得快速进展的标准，选择了要研究的具体接口类型。类似地，仅考虑三种类型缺陷的界面相互作用：点缺陷、位错和裂纹。然而，除了最初被拒绝的那些之外，没有任何基本的物理限制可以阻止未来工作范围扩大到界面、相互作用和缺陷类型。该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机械行为新课程的开发和现有课程的修订。由于麻省理工学院致力于通过 OpenCourseWare 等在线项目分享其教育资源，这些课程将使全世界的观众受益。该项目将通过麻省理工学院国际科学与技术计划计划在麻省理工学院和国际上提供本科生研究机会，从而加强对未来科学家的培训。最后，该项目将增强麻省理工学院最近获得博士学位并打算继续从事研究事业的科学家的经验。