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.

基于feb的磁体在风力发电机，电动汽车直流电机和许多其他关键技术中的使用需求不断增加。稀土（RE）元素的高成本以及对Nd和其他稀土元素进口的严重依赖，使得用更丰富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要。在特定的FeNi合金中，一种特定类型的Ni和Fe原子的有序排列提供了与NdFeB磁铁相当的强大磁性。虽然已经在陨石中观察到一种铁和镍原子排列如此有序的FeNi合金，但在地球上制造这种合金的努力到目前为止还没有成功。这是因为这种排列只有在300摄氏度以下才稳定，但在这个温度下，原子跃迁需要达到有序的晶体需要数百万年的时间。该项目研究了(i)使用独特的方法引入FeNi单晶中大量的晶体缺陷，以及（ii）如何使用它们来增加原子跳变率并在实际时间框架内获得所需的结构。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作机制。减少目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。该项目培养了几名研究生和本科生，提高了几门课程的课程内容，并改善了研究设施。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开展推广工作。在风力发电机、电动汽车直流电机和许多其他关键技术中，对钕铁硼基磁体的需求不断增加。稀土元素的高成本和对钕等稀土元素进口的严重依赖，使得用更丰富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要。具有L10有序晶体结构的等原子FeNi合金相具有与NdFeB磁铁相当的强大永磁体性能。虽然这一相已经在中子辐照的FeNi单晶和小行星中观察到，但由于其临界有序温度较低，约为320摄氏度，因此扩散动力学较低，因此无法在陆地上以整体形式合成。该项目通过提高在低于临界有序温度下的扩散动力学，克服了FeNi合金中L10远程有序的障碍。这是通过极端变形增加位错密度和非平衡空位浓度以及通过添加合金来增强扩散动力学来实现的。采用垂直布里奇曼晶体生长技术生长FeNi单晶。位错和其他缺陷密度用x射线衍射和扫描透射电子显微镜表征。利用x射线衍射图中的漫射散射峰和超晶格峰来研究短阶和长阶。用扩展的x射线精细光谱（EXAFS）检测了有序和局部原子环境。振动样品磁强计用于评估磁性能。该工作还阐明了在陨石中形成FeNi合金中有序相的操作机制。减少目前对稀土元素或稀土磁铁进口依赖的战略需要凸显了拟议研究的影响。该项目培养了几名研究生和本科生，提高了几门课程的课程内容，改善了大学的研究设施。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开展推广工作。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。