Current progress and future challenges in rare-earth-free permanent magnets

Journal Article · Mon Oct 01 00:00:00 EDT 2018 · Acta Materialia

DOI:https://doi.org/10.1016/j.actamat.2018.07.049· OSTI ID:1462461

Cui, Jun ; Kramer, Matthew; Zhou, Lin; Liu, Fei; Gabay, Alexander ; Hadjipanayis, George; Balasubramanian, Balamurugan; Sellmyer, David

Here, permanent magnets (PM) are critical components for electric motors and power generators. Key properties of permanent magnets, especially coercivity and remanent magnetization, are strongly dependent on microstructure. Understanding metallurgical processing, phase stability and microstructural changes are essential for designing and improving permanent magnets. The widely used PM for the traction motor in electric vehicles and for the power generator in wind turbines contain rare earth elements Nd and Dy due to their high maximum energy product. Dy is used to sustain NdFeB's coercivity at higher temperature. Due to the high supply risk of rare earth elements (REE) such as Dy and Nd, these elements are listed as critical materials by the U.S. Department of Energy and other international institutes. Other than Dy, finer grain size is also found to have effect on sustaining coercivity at higher temperature. A proper control of phase stability and microstructures has direct impact on mitigating REE supply risk. Compared to rare earth PMs, non-rare earth (non-RE) PMs typically have lower maximum energy products, however, given their small supply risks and low cost, they are being intensively investigated for less-demanding applications.

• Research Organization: Ames Laboratory (AMES), Ames, IA (United States); Iowa State Univ., Ames, IA (United States)
• Sponsoring Organization: USDOE Advanced Research Projects Agency - Energy (ARPA-E); USDOE Office of Energy Efficiency and Renewable Energy (EERE); USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: 11/CJ000/09/03; EE0007794; AC02-07CH11358; FG02-04ER46152; NNCI: 1542182
• OSTI ID: 1462461
• Alternate ID(s): OSTI ID: 1464485; OSTI ID: 1864021
• Report Number(s): IS-J-9589; S1359645418305858; PII: S1359645418305858
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Vol. 158 Journal Issue: C; ISSN 1359-6454
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

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