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中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，清洁能源技术中使用的磁体需要大量的关键稀土元素（例如，钕）与供应链的复杂性、对环境有害的提取和能源密集型生产有关。因此，迫切需要用于制造永磁体的新材料设计范例和节能处理方案。该奖项支持基础研究，探索在不使用稀土金属的情况下制造块状纳米复合永磁体的材料和制造创新。该团队将协同联合收割机计算材料设计与新型金属增材制造和实验分析工作，以研究增材加工，材料成分和微观结构之间的关系，以及新型纳米复合永磁体的功能响应。该项目有可能通过开发可再生能源技术来大幅提高国家的经济和能源安全。与英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，该团队将把项目相关的材料纳入正在进行的教学研讨会与里士满数学和科学中心合作，为K-12 outreach.本研究的总体目标是设计，制造，并调查增材制造的块状纳米复合永磁体的结构-性能关系，展示各向异性的微观结构，最大能量产品在15兆高斯奥斯特左右的范围。为了实现这一目标，将采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实验验证。基本策略是产生“相分离”的大块纳米复合磁性合金，其由具有针状几何形状的亚微米级反铁磁沉淀物分散在具有定向排列晶粒的铁磁（FM）基体中组成。以这种方式，假设磁各向异性的替代源（例如，交换偏置的各向异性）可以用来代替强磁晶各向异性场-稀土永磁体的特征。该团队将探索激光吹制粉末定向能量沉积（DED）增材制造，用于加工纳米复合永磁体，这是一条探索最少的路线。特殊的DED机器，在磁场的辅助下，将使用粉末原料，其成分是从计算设计中计算出来的，包括FM矩阵，以产生新的定向排列的晶粒，亚稳沉淀物和晶体学纹理，这些将在微观结构和磁性能中进行分析。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，它还将提供磁场辅助DED技术的基本理解，用于制造复杂的多组分/多相磁性合金，如高熵磁致伸缩材料，该奖项反映了NSF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进行评估，被认为值得支持的搜索.

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.