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.