CAREER: An Efficient First-Principles Method for Calculating Deformation Properties, Diffusivity, and Secondary Creep-Rate Behavior in BCC High-Entropy Alloys

职业生涯：一种计算 BCC 高熵合金变形特性、扩散率和二次蠕变速率行为的有效第一性原理方法

• 批准号: 2046670
• 负责人: Chelsey Hargather
• 金额: $ 51.96万
• 依托单位: New Mexico Institute of Mining and Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-01 至 2026-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2046670&HistoricalAwards=false
• 关键词: CAREER; Efficient; First; Principles; Method

This project is jointly funded by the Condensed-Matter-and-Materials-Theory program in the Division of Materials Research and by the Established Program to Stimulate Competitive Research (EPSCoR).NONTECHNICAL SUMMARYThis CAREER award supports computational research and educational activities with an aim to understand fundamental failure mechanisms in a new class of engineering alloys called high-entropy alloys (HEAs). HEAs are a relatively new class of engineering materials that show significant promise for replacing traditional engineering alloys, such as steel, in high temperature and load-bearing applications. HEAs are unique because they are typically composed of five elements in approximately equal proportions, whereas traditional engineering alloys, such as conventional steel, have one base alloying element (e.g. iron) which makes up at least 95% of the composition. Determining properties of HEAs using physics-based simulations, however, are challenging because of the large computational resources required to handle the multiple elements and atomic configurations of HEAs. The PI and her team will investigate an important mechanical property of HEAs, known as creep failure, which is the time-dependent and permanent deformation of a material under applied load or stress. A fundamental understanding of creep failure in these materials could potentially lead to the replacement of traditional engineering alloys with HEAs that could create faster, more fuel-efficient, and less costly machines. This award also supports an education plan which is aimed at (i) developing and delivering research-focused workshops to undergraduates, and (ii) facilitating faculty involvement in the current mentoring program. The PI and her team will create a series of workshops for first-year, first-semester students that will be added into the mentoring program at New Mexico Tech. These workshops will be delivered by faculty and will provide students with a toolbox of techniques useful in an undergraduate research setting. Participating students will be offered a small scholarship to use as consumable laboratory supplies in a faculty member's research laboratory. The undergraduate and graduate students engaged in the research and education components of this project will be trained as an educated workforce in research techniques and computational materials science. TECHNICAL SUMMARYThis CAREER award supports computational research and educational activities focused on the use of first-principles calculations based on density functional theory to predict factors that contribute to secondary creep rate properties of body-centered cubic high-entropy alloys (HEAs). HEAs are a relatively new class of engineering materials that show significant promise for replacing traditional, single-principal element engineering alloys in high temperature or structural engineering applications. However, HEAs pose several challenges when atomistic-level calculations are used to determine their properties, since (i) such calculations are more time consuming than those for ordered systems with an equivalent number of atoms, (ii) they require averaging of several atomic configuration permutations of a structure when a defect is present, and (iii) a model for predicting diffusivity in non-dilute random structures does not exist for body-centered cubic materials at the atomic level. Four research objectives will be completed to solve the challenges of applying atomistic-level calculations to HEAs. First, an efficient first-principles methodology validated with statistical inference will be developed for structures with point and planar defects. The inferential statistics method allows the user to select an appropriate error bar based on the sample set of a larger, global population. Second, a diffusion model for calculating atomic jump frequencies and diffusion coefficients in HEAs will be developed by combining Manning’s theory of diffusivity in random alloys with a novel frequency model for paired solutes in a body-centered cubic host lattice. When combined with inferential statistics, an efficient method for calculating the diffusion coefficients of each element in the HEA will be obtained. Third, stacking fault energy and elastic constants will be calculated by applying the inferential statistics method. The effect of impurity segregation on stacking fault energy in body-centered cubic HEAs will be explored. Finally, the calculated diffusion and deformation properties will be incorporated into a universal secondary creep law. Through a series of relationships in the universal creep law, contributions to creep behavior from deformation and diffusion properties will be investigated. This project will provide valuable data that is necessary to focus future experimental and computational research on HEA systems, while giving the materials science community a framework that can be used for efficient property determination in other engineering alloys.This award also supports an education plan which is aimed at (i) developing and delivering research-focused workshops to undergraduates, and (ii) facilitating faculty involvement in the current mentoring program. The PI and her team will create a series of workshops for first-year, first-semester students that will be added into the mentoring program at New Mexico Tech. These workshops will be delivered by faculty and will provide students with a toolbox of techniques useful in an undergraduate research setting. Participating students will be offered a small scholarship to use as consumable laboratory supplies in a faculty member's research laboratory. The undergraduate and graduate students engaged in the research and education components of this project will be trained as an educated workforce in research techniques and computational materials science.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

该项目由材料研究部的凝聚态物质与材料理论计划和刺激竞争性研究既定计划 (EPSCoR) 共同资助。非技术摘要该职业奖支持计算研究和教育活动，旨在了解称为高熵合金 (HEA) 的新型工程合金的基本失效机制，这是一种显示出相对重要前景的新型工程材料。用于在高温和承载应用中替代传统工程合金（例如钢）的 HEA 是独一无二的，因为它们通常由大约相等比例的五种元素组成，而传统工程合金（例如传统钢）只有一种基本合金元素。然而，由于处理 HEA 的多种元素和原子构型需要大量计算资源，因此使用基于物理的模拟确定 HEA 的特性具有挑战性。 PI 和她的团队将研究 HEA 的一个重要机械特性，即蠕变失效，这是材料在施加载荷或应力下随时间变化的永久变形，对这些材料的蠕变失效的基本了解可能会导致材料的蠕变失效。用 HEA 替代传统的工程合金，可以制造出更快、更省油且成本更低的机器。该奖项还支持一项教育计划，该计划旨在 (i) 为本科生开发和提供以研究为重点的研讨会，以及 (ii)促进教师参与当前的指导计划。 PI 和她的团队将为一年级第一学期的学生举办一系列研讨会，这些研讨会将添加到新墨西哥理工学院的指导计划中。这些研讨会将由教师讲授，并将为学生提供有用的技术工具箱。参与该项目的学生将获得一笔小额奖学金，用作教师研究实验室的消耗性实验室用品。参与该项目研究和教育部分的本科生和研究生将被培训为受过教育的研究人员。技术和计算材料科学。技术摘要该职业奖支持计算研究和教育活动，重点是使用基于密度泛函理论的第一性原理计算来预测影响体心立方高熵合金 (HEA) 二次蠕变速率特性的因素。一种相对较新的工程材料，在高温或结构工程应用中显示出替代传统单主要元素工程合金的巨大前景。然而，在使用原子级计算时，HEA 提出了一些挑战。为了确定它们的属性，因为（i）这种计算比具有相同原子数的有序系统的计算更耗时，（ii）当存在缺陷时，它们需要对结构的几个原子构型排列进行平均，并且（iii） ）在原子水平上不存在预测体心立方材料的扩散率的模型，以解决将原子水平计算应用于 HEA 的挑战。将为具有点和平面缺陷的结构开发经过统计推断验证的第一原理方法。推断统计方法允许用户根据更大的全球总体样本集选择合适的误差线。计算 HEA 中的原子跳跃频率和扩散系数将通过将随机合金中的曼宁扩散率理论与体心立方主晶格中成对溶质的新型频率模型相结合来开发。第三，应用推论统计方法计算杂质偏析对体中堆垛层错能的影响。最后，计算出的扩散和变形特性将被纳入通用二次蠕变定律中，通过通用蠕变定律中的一系列关系，将研究变形和扩散特性对蠕变行为的贡献。将提供有价值的数据对于未来重点关注 HEA 系统的实验和计算研究是必要的，同时为材料科学界提供了一个可用于有效确定其他工程合金性能的框架。该奖项还支持一项教育计划，该计划旨在（i ) 为本科生开发和提供以研究为重点的研讨会，以及 (ii) 促进教师参与当前的指导计划。 PI 和她的团队将为一年级、第一学期的学生举办一系列研讨会，并将其添加到课程中。新墨西哥理工学院的指导计划这些研讨会将由教师提供，将为学生提供在本科生研究环境中有用的技术工具箱，参与该研究的学生将获得小额奖学金，用作教师研究实验室的消耗性实验室用品。该项目的教育部分将被培训为研究技术和计算材料科学方面受过教育的劳动力。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。