Laser directed energy deposition processing of exchange-biased bulk nanocomposite permanent magnets using tailored ferromagnetic-matrix powder

The National Science Foundation (NSF) Directorate for Engineering (CFDA 47.041) awarded a $575,292 Project Grant to Virginia Commonwealth University (VCU) to conduct fundamental research on creating bulk nanocomposite permanent magnets without the use of rare-earth metals. The overarching goal is to design, fabricate, and investigate structure-property relationships in additively manufactured nanocomposite permanent magnets that can achieve energy products around 15 mega-gauss-oersted. To accomplish this, the project will synergistically combine computational material design with novel metal additive manufacturing and experimental analysis to examine the relationships between processing, composition, microstructure, and magnetic properties of these new magnet materials. The research has potential to enhance the economic and energy security of the nation by enabling renewable energy technologies that rely on permanent magnets. The project also includes educational and workforce development components through collaborations with a regional manufacturing center and K-12 STEM outreach programs.

Abstract

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.