CAREER: Understanding novel characteristics of defects in concentrated solid solutions from first principles calculations

非技术摘要：金属合金的机械性能（例如强度和抗断裂性）受晶体缺陷（例如位错、晶界和溶质）的影响。设计具有增强性能的新金属合金需要详细了解这些缺陷的特性。该项目提供了对高熵合金的结构缺陷和塑性的新认识，高熵合金是一类具有理想和非常规性能的新型多组分合金。该研究计划促进了对以前从未考虑过的复杂多组分合金成分的研究，为发现新材料创造了巨大潜力，以满足二十一世纪不断增长的技术需求，例如能源和高效运输。此外，高熵合金的新颖特性鼓励人们以新的方式看待物理冶金学的基本方面，从而产生适用于各种金属合金的新见解。该综合研究和教育计划旨在“促进发现和理解，同时促进教学、培训和学习”，以培养下一代多元化和具有全球竞争力的研究科学家和工程师。教育部分借鉴研究主题，通过模拟增强困难材料科学概念的教学/学习。此外，外展活动在 PI 和哥伦布女子学校 (CSG) 之间建立了联系，哥伦布女子学校 (CSG) 是俄亥俄州哥伦布市一所当地的从幼儿园到 12 年级的女子学校，鼓励和指导年轻女性走向科学和工程领域的职业道路。技术摘要：该职业项目旨在了解高熵合金 (HEA) 卓越机械性能的基本变形机制，高熵合金是一类原子百分比（接近）相等的多组分金属合金，引人注目的是，结晶为单相固溶体。该提案的研究目标是检验这样的假设：单相浓多元素合金 (CMA)“其中单相 HEA 是一个有趣的子集”中的原子尺度变形机制与稀合金中的原子尺度变形机制根本不同。具体目标是：（1）利用密度泛函理论（DFT）计算CMA中的位错和堆垛层错结构和能量。 (2) 开发新的计算工具，利用 DFT 在 CMA 中进行位错建模。 (3) 生成适用于 CMA 的新固溶强化模型。该提案的成果并不局限于特定的 CMA，而且适用于广泛的浓缩固溶体类别，提供了思考物理冶金基本方面的新方法，并产生了适用于具有定制性能的新成分的各种金属合金的新见解。该提案的教育和推广目标是 (i) 通过基于模拟的可视化加强材料科学的教学/学习，以及 (ii) 增加女性和少数族裔在科学和工程职业中的代表性。这些目标是通过以下方式实现的：(1) 创建和传播有关原子尺度变形机制的短视频，作为各个级别的课程丰富模块；(2) 为哥伦布女子学校（当地一所从幼儿园到 12 年级的女子学校）的 K-12 学生提供指导、研究机会和实践活动。

Nontechnical Summary:Mechanical properties, such as strength and fracture resistance, of metal alloys are governed by crystal defects-e.g dislocations, grain boundaries, and solutes. Designing new metal alloys, with enhanced properties, requires detailed knowledge of the properties of these defects. This project provides a new understanding of the structural defects and plasticity in high entropy alloys, a new class of multicomponent alloys with desirable and nonconventional properties. The research program stimulates the study of complex multi-component alloy compositions that have never been considered before, creating a great potential for discovery of new materials to address the ever-increasing technological needs of the twenty-first century such as energy and efficient transportation. In addition, novel properties of high entropy alloys encourages new ways of viewing fundamental aspects of physical metallurgy, yielding new insights that are applicable to a wide range of metallic alloys. The integrated research and educational program seeks to "advance discovery and understanding while promoting teaching, training, and learning" to train the next generation of diverse and globally competitive research scientists and engineers. The educational component, drawing from the research theme, enhances teaching/learning of difficult materials science concepts using simulations. In addition, the outreach activities establishes a connection between the PI and Columbus School for Girls (CSG), a local all-girls K through 12 school in Columbus, Ohio, to encourage and mentor young women towards career paths in science and engineering fields.Technical Summary:This CAREER project aims to understand the fundamental deformation mechanisms responsible for the remarkable mechanical properties of high entropy alloys (HEAs), a class of multicomponent metallic alloys in (near) equal atomic percent that, strikingly, crystalize as single-phase solid solutions. The research goal of this proposal is to test the hypothesis that the atomic-scale deformation mechanisms in single-phase, concentrated multi-element alloys (CMAs) "of which the single phase HEAs are an interesting subset" are fundamentally different from those in dilute alloys. The specific objectives are: (1) Computing dislocation and stacking fault structures and energies in CMAs with density functional theory (DFT). (2) Developing new computational tools that enable dislocation modeling in CMAs with DFT. (3) Generating a new solid solution strengthening model applicable to CMAs. The outcomes of this proposal are not restricted to specific CMAs and are applicable to the broad category of concentrated solid solutions, providing new ways of thinking about fundamental aspects of physical metallurgy and yielding new insights that are applicable to a wide range of metallic alloys with new compositions for tailored properties.The education and outreach goals of this proposal are (i) to enhance teaching/learning of materials science via simulation-based visualizations and (ii) to increase the representation of women and minorities in science and engineering careers. These goals are achieved via (1) creating and disseminating short videos on atomic-scale deformation mechanisms, as course enrichment modules at various levels and (2) providing mentorship, research opportunities and hands-on activities for K-12 students in Columbus School for Girls-- a local all-girls K through 12 school.