Collaborative Research: Towards Rare-Earth-Free Advanced Permanent Magnets - High-Anisotropy L10 Materials

该项目旨在阐明控制等原子化合物FeNi的热力学和动力学稳定性的材料因素，该化合物具有化学有序的四方L10结构，具有非常高的无稀土先进永磁体应用潜力。在Fe-Ni相图的近等原子组成区域，磁性合金的基础探索性研究将在有或没有添加Ti、V和Al三元合金的材料中进行。这些材料将以块状和厚膜形式合成，并从焦点合金的薄膜类似物中获得见解，用于指导块状合金的合理设计。化学有序与磁性之间的关系，如磁化强度、各向异性和居里温度将被确定和量化，以促进趋势预测。天文学家已经在选定的陨石中发现了L10 FeNi相，并将其存在归因于异常缓慢的冷却速度，这种冷却速度在46亿年的时间里促进了长期的化学秩序。Fe-Ni体系中L10结构的确认是非常重要的，因为在这种结构中伴随着化学有序的四方畸变引起了明显的各向异性。开发不含稀土的永磁材料对于抵消供应限制和确保美国的竞争力至关重要。获得具有极高磁晶各向异性的无稀土磁性材料将产生巨大的影响，从基础科学领域一直到具有重大社会意义的高级应用。获资助的学生将在三所地理位置不同、实力雄厚的理工科院校进行教育交流，获得跨学科的研究经验。

This project seeks to elucidate materials factors that control the thermodynamic and kinetic stability of the equiatomic compound FeNi with the chemically-ordered tetragonal L10 structure that holds very high potential for rare-earth-free advanced permanent magnet applications. Fundamental exploratory research on magnetic alloys in the near-equiatomic compositional region of the Fe-Ni phase diagram will take place in materials with and without the ternary alloying additions of Ti, V, and Al. These materials will be synthesized in both bulk and thick-film form, with insight gained from film analogs of the focus alloys used to guide rational design of bulk alloys. Correlations between chemical ordering and magnetic properties such as magnetization, anisotropy and Curie temperature will be determined and quantified to facilitate trend prediction.Astronomers have identified the L10 FeNi phase in selected meteorites and attributed its presence to an extraordinarily slow cooling rate that fosters long-range chemical ordering over a period of 4.6 billion years. Confirmation of the L10 structure in the Fe-Ni system is extremely significant because the tetragonal distortion that accompanies the chemical ordering in this structure gives rise to appreciable anisotropy. The development of rare-earth-free permanent magnet materials is essential to offset supply limitations and ensure U.S. competitiveness. Attainment of a rare-earth-free magnetic material with very high magnetocrystalline anisotropy would carry tremendous impact that ranges from the basic science realm all the way to advanced applications of great societal importance. Students supported by this grant will obtain an interdisciplinary research experience via educational exchange at three geographically diverse, strong science and engineering schools.