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

金属合金的机械性能，如强度和抗断裂性，是由晶体缺陷如位错、晶界和溶质决定的。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性能。该项目提供了对高熵合金的结构缺陷和塑性的新理解，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。该研究计划刺激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的潜力，以满足二十一世纪不断增长的技术需求，如能源和高效运输。此外，高熵合金的新特性鼓励人们以新的方式看待物理冶金的基本方面，产生适用于各种金属合金的新见解。综合研究和教育计划旨在“推进发现和理解，同时促进教学，培训和学习”，以培养下一代多样化和具有全球竞争力的研究科学家和工程师。教育部分，从研究主题，提高教学/学习困难的材料科学概念，使用模拟。此外，外联活动还在国际和平组织和哥伦布女子学校（CSG）之间建立了联系，CSG是俄亥俄州哥伦布的一所当地女子学校，从幼儿园到12岁，鼓励和指导年轻妇女走向科学和工程领域的职业道路。这个CAREER项目旨在了解高熵合金（HEAs）显着机械性能的基本变形机制，HEAs是一类（接近）等原子百分比的多组分金属合金，结晶为单相固溶体。该提案的研究目标是检验这样一种假设，即单相浓缩多元素合金（CMA）中的原子尺度变形机制“其中单相HEAs是一个有趣的子集”与稀合金中的原子尺度变形机制根本不同。具体目标是：（1）用密度泛函理论（DFT）计算CMA中位错和层错的结构和能量。(2)开发新的计算工具，使位错模型的CMA与DFT。(3)建立了一个新的适用于CMA的固溶强化模型。本提案的结果并不限于特定的CMA，而是适用于浓缩固体溶液的广泛类别，为物理冶金学的基本方面提供新的思维方式，并产生新的见解，适用于具有新成分的各种金属合金，以实现定制性能。本提案的教育和推广目标是：（i）加强教学/通过基于模拟的可视化学习材料科学，以及（ii）增加妇女和少数民族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）制作和传播关于原子尺度变形机制的短视频，作为各级课程的充实模块;（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-的学生提供辅导、研究机会和动手活动。

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.