Laser Directed Energy Deposition Processing of Exchange-Biased Bulk Nanocomposite Permanent Magnets Using Tailored Ferromagnetic-Matrix Powder

永磁体在实现清洁能源技术方面发挥着不可或缺的作用，包括风力涡轮机、水力发电机和电动汽车等。然而，用于清洁能源技术的磁体需要大量的关键稀土元素（如钕），这些元素与供应链的复杂性、对环境有害的开采和能源密集型生产有关。因此，迫切需要新的材料设计范例和节能加工方案来制造永磁体。该奖项支持基础研究，以探索不使用稀土金属的大块纳米复合永磁体的材料和制造创新。该团队将协同结合计算材料设计与新型金属增材制造和实验分析工作，以研究新型纳米复合永磁体中增材加工，材料成分和微观结构以及功能响应之间的关系。该项目有潜力通过可再生能源技术的发展大大提高国家的经济和能源安全。与联邦先进制造中心的研究合作将进一步扩大项目影响，促进先进制造领域的劳动力发展。此外，该团队将与里士满数学和科学中心合作，将与项目相关的材料纳入正在进行的教学研讨会，以进行K-12外展。本研究的总体目标是设计、制造和研究增材制造的块状纳米复合永磁体的结构-性能关系，这些永磁体具有各向异性微观结构，最大能量积在大约15兆高斯的范围内。为了实现这一目标，将使用计算微磁模拟工具来指导合金设计，并对选定的合金成分进行磁性材料制造和磁性能实验验证。其基本策略是生成“相分离”的块状纳米复合磁性合金，该合金由亚微米尺度的针状反铁磁沉淀组成，分散在具有定向排列晶粒的铁磁（FM）基体中。通过这种方式，假设可以利用导致高矫顽力的磁各向异性的替代来源（例如，交换偏置各向异性）来取代强磁晶各向异性场-稀土永磁体的特征。该团队将探索激光吹粉定向能沉积（DED）增材制造，以加工纳米复合永磁体，这是一个探索最少的路线。这台特殊的DED机器在磁场的辅助下，将使用从计算设计中计算出成分的粉末原料，包括FM矩阵，以产生新的定向排列的颗粒，亚稳沉淀和晶体结构，这些将在微观结构和磁性能方面进行分析。该项目不仅将深入了解增材制造纳米复合永磁材料的工艺-结构-性能关系，还将为制造复杂的多组分/多相磁性合金（如高熵磁热合金和磁性形状记忆合金）提供磁场辅助DED技术的基本理解。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。

Permanent magnets play an indispensable role in enabling clean energy technologies, including wind turbines, hydroelectric power generators, and electric vehicle, etc. However, the magnets used in clean energy technologies require a large amount of critical rare-earth elements (e.g., neodymium) associated with supply chain complexities, environmentally hazardous extraction, and energy-intensive production. New materials design paradigms and energy-efficient processing schemes for creating permanent magnets are thus urgently needed. This award supports fundamental research to explore material and manufacturing innovations in making bulk nanocomposite permanent magnets without using rare-earth metals. The team will synergistically combine computational material designs with novel metal additive manufacturing and experimental analysis efforts to examine the relationships between additive processing, material compositions and microstructures, and functional response in new nanocomposite permanent magnets. The project has the potential to drastically enhance the economic and energy security of the Nation via the development of renewable energy technologies. Research collaboration with the Commonwealth Center for Advanced Manufacturing will further broaden project impacts and promote workforce development in the field of advanced manufacturing. In addition, the team will incorporate project-related materials into ongoing teaching workshops partnered with the Richmond Math and Science Centers for K-12 outreach.The overarching goal of this research is to design, fabricate, and investigate structure-property relations in additively manufactured bulk nanocomposite permanent magnets that demonstrate anisotropic microstructure with the maximum energy products in the range of around 15 mega-gauss-oersted. To achieve this, computational micromagnetic simulation tools will be employed to guide alloy designs, with the magnetic material fabrications and experimental validation of magnetic properties performed for down-selected alloy compositions. The fundamental strategy is to generate "phase-separated" bulk nanocomposite magnetic alloys consisting of submicron-scale antiferromagnetic precipitates with acicular geometry dispersed in a ferromagnetic (FM) matrix with directionally-aligned grains. In this manner, it is hypothesized that alternate sources of magnetic anisotropy (e.g., exchange-biased anisotropy) that lead to high coercivity may be harnessed to replace strong magnetocrystalline anisotropy fields – a characteristic feature of rare-earth permanent magnets. The team will explore laser blown-powder directed energy deposition (DED) additive manufacturing for processing nanocomposite permanent magnets, which is a least explored route. The special DED machine, assisted with a magnetic field, will use powder feedstock with compositions calculated from computational designs that include an FM matrix to produce novel directionally-aligned grains, metastable precipitates, and crystallographic textures, which will be analyzed in microstructures and magnetic properties. The project will not only achieve insight regarding the process-structure-property relationships of additively-manufactured nanocomposite permanent magnet materials, it will also provide a fundamental understanding of the magnetic-field-assisted DED technology for the fabrication of complex multicomponent/multiphase magnetic alloys such as high-entropy magneto-caloric alloys and magnetic shape memory alloys.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.