Enabling L10 Ordering in Bulk FeNi Alloys and an Alternative for Nd2Fe14B- Based Permanent Magnets

实现散装 FeNi 合金的 L10 订购以及基于 Nd2Fe14B 的永磁体的替代品

• 批准号: 2400480
• 负责人: Sivaraman Guruswamy
• 金额: $ 52.77万
• 依托单位: University of Utah
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-05-01 至 2027-04-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2400480&HistoricalAwards=false
• 关键词: Enabling; L10; Ordering; Bulk; FeNi

NON-TECHNICAL SUMMARYNdFeB based magnets are in increased demand for use in wind mills, DC motors in electric vehicles and numerous other key technologies. The high cost of rare-earth (RE) elements and heavy reliance on imports of Nd and other rare-earth elements make the replacement of NdFeB magnets with low-cost magnets made of more abundant elements an urgent economic and national security need. A specific type of ordered arrangement of Ni and Fe atoms in a specific FeNi alloy provides powerful magnetic properties comparable to that of NdFeB magnets. While an FeNi alloy with such an ordered arrangement of Fe and Ni atoms has been observed in meteorites, efforts to make such an alloy on the earth has so far been unsuccessful. This is because such an arrangement is stable only below 300 degree Centigrade, but at these temperatures, the atomic jumps needed to achieve the ordered crystals will require millions of years. This project investigates (i) introduction of extensive amount of crystal defects in FeNi single crystals using a unique approach and (ii) how they can be used to increase the atomic jump rates and obtain the desired structure in a practical time frame. This work also sheds light on the operating mechanism in meteorites to form this ordered arrangement in the FeNi alloy. Strategic need to minimize the current reliance on RE imports underscores the impact of the proposed research. The project trains several graduate and undergraduate students, enhances course content in several courses, and improves research facilities. Outreach efforts are made to high school students, female and under-represented student groups, and the broader community.TECHNICAL SUMMARYThere is an increasing demand for NdFeB based magnets for use in wind mills, DC motors in electric vehicles and numerous other key technologies. The high cost of rare-earth elements and heavy reliance on the imports of Nd and other rare-earth elements make the replacement of NdFeB magnets with low-cost magnets made of more abundant elements an urgent economic and national security need. Equiatomic FeNi alloy phase with L10 ordered crystal structure provides powerful permanent magnet properties comparable to NdFeB magnets. While this phase has been observed in neutron irradiated FeNi single crystals and asteroids, it has defied terrestrial synthesis in bulk form due to its low critical ordering temperature of around 320 degree centigrade and consequently low diffusion kinetics. This project overcomes the barrier for L10 long-range ordering in FeNi alloy by enhancing diffusion kinetics at temperatures below the critical ordering temperature. This is achieved by increasing the dislocation density and nonequilibrium vacancy concentration through extreme deformation and by alloying additions that enhance diffusion kinetics. FeNi single crystals are grown using the vertical Bridgman crystal growth technique. Dislocation and other defect densities are characterized using x-ray diffraction and scanning transmission electron microscopy. Short- and long-range order are examined using diffuse scattering peaks and superlattice peaks in the x-ray diffraction patterns. Ordering and local atomic environments are also examined using extended x-ray fine spectrum (EXAFS). Vibrating sample magnetometry is used to assess the magnetic properties. The work also elucidates the operating mechanism in meteorites to form this ordered phase in the FeNi alloy. Strategic need to minimize the current reliance on rare-earth element or rare-earth magnet imports underscores the impact of the proposed research. The project trains several graduate and undergraduate students, enhances course content in several courses, and improves university research facilities. Outreach efforts are made to high school students, female and under-represented student groups, and to the broader community.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.

非技术摘要 风车、电动汽车直流电机以及众多其他关键技术中对钕铁硼磁体的需求不断增加。稀土（RE）元素的高昂成本以及对钕等稀土元素进口的严重依赖，使得用更丰富的元素制成的低成本磁体替代钕铁硼磁体成为迫切的经济和国家安全需求。 特定 FeNi 合金中 Ni 和 Fe 原子的特定有序排列提供了与 NdFeB 磁体相当的强大磁性。 虽然在陨石中观察到具有如此有序排列的 Fe 和 Ni 原子的 FeNi 合金，但迄今为止在地球上制造这种合金的努力尚未成功。这是因为这种排列仅在 300 摄氏度以下稳定，但在这些温度下，实现有序晶体所需的原子跳跃将需要数百万年。该项目研究 (i) 使用独特的方法在 FeNi 单晶中引入大量晶体缺陷，以及 (ii) 如何利用它们来提高原子跳跃率并在实际时间范围内获得所需的结构。这项工作还揭示了陨石在 FeNi 合金中形成这种有序排列的运行机制。最大限度地减少当前对可再生能源进口依赖的战略需要强调了拟议研究的影响。该项目培养了多名研究生和本科生，增强了多门课程的课程内容，并改善了研究设施。推广工作针对高中生、女性和代表性不足的学生群体以及更广泛的社区。技术摘要用于风车、电动汽车直流电机和许多其他关键技术的钕铁硼磁体的需求不断增长。稀土元素成本高昂，加上钕等稀土元素严重依赖进口，使得用元素更为丰富的低成本磁体替代钕铁硼磁体成为经济和国家安全的迫切需求。具有 L10 有序晶体结构的等原子 FeNi 合金相提供了与 NdFeB 磁体相媲美的强大永磁性能。虽然这一相已在中子辐照的 FeNi 单晶和小行星中观察到，但由于其临界有序温度约为 320 摄氏度，因此扩散动力学较低，因此无法在陆地上以块体形式合成。该项目通过增强低于临界有序温度的扩散动力学，克服了 FeNi 合金中 L10 长程有序的障碍。这是通过极端变形增加位错密度和非平衡空位浓度以及增强扩散动力学的合金添加来实现的。 FeNi 单晶采用垂直布里奇曼晶体生长技术生长。使用 X 射线衍射和扫描透射电子显微镜来表征位错和其他缺陷密度。使用 X 射线衍射图中的漫散射峰和超晶格峰检查短程和长程有序。还使用扩展 X 射线精细光谱 (EXAFS) 检查有序和局部原子环境。振动样品磁力测量用于评估磁性。这项工作还阐明了陨石中形成 FeNi 合金有序相的操作机制。最大限度地减少当前对稀土元素或稀土磁体进口的依赖的战略需要强调了拟议研究的影响。该项目培养了多名研究生和本科生，增强了多门课程的课程内容，并改善了大学的研究设施。外展工作面向高中生、女性和代表性不足的学生群体以及更广泛的社区。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优点和更广泛的影响审查标准进行评估，被认为值得支持。