Novel Nanostructures for High-Energy Nanocomposite Permanent Magnets

技术：在纳米结构两相复合材料中，硬磁相和软磁相之间的磁相互作用导致永磁体材料具有显著增强的磁性能。随着软磁相含量的增加，材料的性能显著提高。然而，在颗粒状材料中，由于软磁颗粒/软磁颗粒近邻的发展，软磁相含量被限制在15%左右。然而，通过共晶相变开发的新型纳米结构提供了将软磁相的体积分数增加到20%-30%的可能性。本项目的目标是开发Sm-Co-T三元合金在Sm原子百分比为8的二元Sm-Co共晶附近的显微组织选择图。有了这些信息，可以设计出具有高Co含量的合金，其共晶组织可以避免形成初生Co。无论是常规处理的合金还是快速凝固后的合金，都将确定组织选择图。快速凝固处理有效地将软磁相的尺度细化到硬磁相和软磁相之间有效交换相互作用所必需的纳米结构水平。为了了解纳米复合永磁体作为温度函数的行为，将从作为温度函数的磁滞回线来确定纳米复合永磁体的磁性。直流退磁和等温剩磁测量将提供对磁行为的更多了解，特别是反转过程和相间磁相互作用。纳米复合材料的磁性行为将通过使用X射线衍射以及扫描和透射电子显微镜来表征结构，从而与纳米结构紧密相连。三维原子探针断层扫描和三维场离子显微镜也将用于表征纳米结构；这将与法国鲁昂大学的Frederic Danoix博士合作完成。非技术性：稀土永磁体是技术进步不可或缺的一部分。因此，通过提供先进的电子设备、新的医学成像功能以及无数其他应用，一些已知的和一些尚未想象的应用，改进的永久磁体的持续开发直接造福于社会。此外，这项研究还将对三元合金在共晶成分和近共晶成分下的凝固过程提供基本的了解。该项目还将教育和培训下一代科学家和行业领导者，主要是通过让本科生和研究生参与研究来实现教学和研究的一体化。计划与鲁昂大学的研究人员进行合作研究，研究生将参与鲁昂大学的短期访问，以进行研究实验。与国家实验室的研究人员合作以及使用国家用户设施也将扩大参与该项目的学生的经验。国际和平研究所还开发了一门纳米材料课程，该项目中的发现将被纳入其中。

TECHNICAL: Magnetic interactions between hard and soft magnetic phases in nanostructured two-phase composites result in permanent magnet materials with significantly enhanced magnetic properties. The properties dramatically increase with increasing soft magnetic phase fraction. However, in granular materials the soft magnetic phase fraction is limited to about 15 percent by the development of soft magnetic grain/soft magnetic grain neighbors. However, the development of novel nanostructures via eutectic phase transformations offers the potential to increase the volume fraction of the soft magnetic phase to 20-30 percent. The objective of this project is to develop microstructural selection maps for ternary Sm-Co-T alloys in the vicinity of the binary Sm-Co eutectic at 8 atomic percent Sm. With this information, alloys can be designed with high Co content with eutectic structures that avoid formation of primary Co. The microstructural selection maps will be determined for both conventionally processed alloys and after rapid solidification. Rapid solidification processing effectively refines the scale of the soft magnetic phase to the nanostructural level necessary for effective exchange interactions between the hard and soft magnetic phases. The magnetic properties of the nanocomposite permanent magnets will be determined from hysteresis loops as a function of temperature in order to understand the behavior of nanocomposite permanent magnets as a function of temperature. DC demagnetization and isothermal remanence magnetization measurements will provide additional insight into the magnetic behavior, especially the reversal processes and interphase magnetic interactions. The magnetic behavior of the nanocomposites will be closely tied to the nanostructures by characterizing structures using x-ray diffraction and scanning and transmission electron microscopy. Three-dimensional atom probe tomography and three-dimensional field ion microscopy will also be used to characterize the nanostructures; this will be accomplished in collaboration with Dr. Frederic Danoix of the University of Rouen in France. NON-TECHNICAL: Rare earth permanent magnets are integral to technological advancements. As a result, continued development of improved permanent magnets directly benefit society by providing advanced electronic devices, new medical imaging capabilities, and countless other applications, some known and some not yet imagined. Additionally, the research will provide fundamental understanding of solidification of ternary alloys at and near eutectic compositions. This project will also educate and train the next generation of scientists and industry leaders, primarily through the integration of teaching and research by involving undergraduate and graduate students in research. Collaborative research with researchers at the University of Rouen is planned, with graduate students involved with short-term visits to the University of Rouen to conduct the research experiments. Collaborations with researchers at National Laboratories and use of national user facilities will also expand the experiences of students involved in this project. The PI has also developed a course in nanomaterials, and discoveries made in this project will be incorporated into it.