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

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.
Authors:
ORCiD logo [1] ;  [1] ;  [2] ;  [3] ; ORCiD logo [4] ;  [4] ;  [5] ;  [5]
  1. Ames Lab. and Iowa State Univ., Ames, IA (United States)
  2. Ames Lab., Ames, IA (United States)
  3. Iowa State Univ., Ames, IA (United States)
  4. Univ. of Delaware, Newark, DE (United States)
  5. Univ. of Nebraska, Lincoln, NE (United States)
Publication Date:
Report Number(s):
IS-J-9589
Journal ID: ISSN 1359-6454; PII: S1359645418305858
Grant/Contract Number:
11/CJ000/09/03; EE0007794; FG02-04ER46152; NNCI: 1542182; AC02-07CH11358
Type:
Published Article
Journal Name:
Acta Materialia
Additional Journal Information:
Journal Volume: 158; Journal Issue: C; Journal ID: ISSN 1359-6454
Publisher:
Elsevier
Research Org:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Rare-earth-free; Permanent magnet; MnBi; MnAl; Alnico; L10FeNi; L10FeCo; Fe16N2; Co2C; Co3C; HfCo7; Zr2Co11
OSTI Identifier:
1462461
Alternate Identifier(s):
OSTI ID: 1464485

Cui, Jun, Kramer, Matthew, Zhou, Lin, Liu, Fei, Gabay, Alexander, Hadjipanayis, George, Balasubramanian, Balamurugan, and Sellmyer, David. Current progress and future challenges in rare-earth-free permanent magnets. United States: N. p., Web. doi:10.1016/j.actamat.2018.07.049.
Cui, Jun, Kramer, Matthew, Zhou, Lin, Liu, Fei, Gabay, Alexander, Hadjipanayis, George, Balasubramanian, Balamurugan, & Sellmyer, David. Current progress and future challenges in rare-earth-free permanent magnets. United States. doi:10.1016/j.actamat.2018.07.049.
Cui, Jun, Kramer, Matthew, Zhou, Lin, Liu, Fei, Gabay, Alexander, Hadjipanayis, George, Balasubramanian, Balamurugan, and Sellmyer, David. 2018. "Current progress and future challenges in rare-earth-free permanent magnets". United States. doi:10.1016/j.actamat.2018.07.049.
@article{osti_1462461,
title = {Current progress and future challenges in rare-earth-free permanent magnets},
author = {Cui, Jun and Kramer, Matthew and Zhou, Lin and Liu, Fei and Gabay, Alexander and Hadjipanayis, George and Balasubramanian, Balamurugan and Sellmyer, David},
abstractNote = {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.},
doi = {10.1016/j.actamat.2018.07.049},
journal = {Acta Materialia},
number = C,
volume = 158,
place = {United States},
year = {2018},
month = {7}
}