Journal of Materials Engineering and Performance

, Volume 28, Issue 1, pp 273–277 | Cite as

Performance of Nd-Fe-B Magnets Fabricated by Hot Isostatic Pressing and Low-Temperature Sintering

  • Fang YangEmail author
  • Haiying Wang
  • Li You
  • Alex A. Volinsky
  • Ce Zhang
  • Zhimeng Guo
  • Yanli Sui


Magnetic properties and microstructure of Nd-Fe-B sintered magnets fabricated by hot isostatic pressing (HIP) were studied. For comparison, magnets were also fabricated by vacuum sintering. The density reached 7.58 g/cm3 for the magnets HIP-sintered at 1123 K. The density of the magnets vacuum-sintered at 1123 K was much lower, which is of about 6.92 g/cm3. While the density of magnets vacuum-sintered at 1318 K was the same as the HIP-sintered magnets, the sintering temperature was significantly decreased to 1123 K. In addition, the average grain size decreased from 9 to 6 μm, which has enhanced coercivity. Therefore, the coercivity increased from 1067.7 to 1238.5 kA/m, which is 16% higher than the vacuum-sintered magnets. HIP is a promising method to obtain high density and high coercivity Nd-Fe-B sintered magnets.


coercivity grain refinement hot isostatic pressing Nd-Fe-B sintered magnets 



This work was supported by the State Key Laboratory of Advanced Metals and Materials (No. 2018-Z06).


  1. 1.
    K. Hono and H. Sepehri-Amin, Strategy for High-Coercivity Nd-Fe-B Magnets, Scripta Mater., 2012, 67, p 530–535CrossRefGoogle Scholar
  2. 2.
    K. Loewe, C. Brombacher, M. Katter, and O. Guttfleisch, Temperature-Dependent Dy Diffusion Processes in Nd-Fe-B Permanent Magnets, Acta Mater., 2015, 83, p 248–255CrossRefGoogle Scholar
  3. 3.
    K.C. Lu, X.Q. Bao, M.H. Tang, G.X. Chen, X. Mu, J.H. Li, and X.X. Gao, Boundary Optimization and Coercivity Enhancement of High (BH)max Nd-Fe-B Magnet by Diffusing Pr-Tb-Cu-Al Alloys, Scripta Mater., 2017, 138, p 83–87CrossRefGoogle Scholar
  4. 4.
    T.G. Woodcock and O. Gutfleisch, Multi-phase EBSD Mapping and Local Texture Analysis in NdFeB Sintered Magnets, Acta Mater., 2011, 59, p 1026–1036CrossRefGoogle Scholar
  5. 5.
    W.F. Li, H. Sepehri-Amin, T. Ohkubo, N. Hase, and K. Hono, Distribution of Dy in High-Coercivity (Nd, Dy)-Fe-B Sintered Magnet, Acta Mater., 2011, 59, p 3061–3069CrossRefGoogle Scholar
  6. 6.
    T.H. Kim, S.R. Lee, H.J. Kim, M.W. Lee, and T.S. Jang, Simultaneous Application of Dy-X (X = F or H) Powder Doping and Dip-Coating Processes to Nd-Fe-B Sintered Magnets, Acta Mater., 2015, 93, p 95–104CrossRefGoogle Scholar
  7. 7.
    J. Liu, H. Sepehri-Amin, T. Ohkubo, K. Hioki, A. Hattori, T. Schrefl, and K. Hono, Grain Size Dependence of Coercivity of Hot-Deformed Nd-Fe-B Anisotropic Magnets, Acta Mater., 2015, 82, p 336–343CrossRefGoogle Scholar
  8. 8.
    W.F. Li, A.M. Gabay, M. Marinescu-Jasinski, J.F. Liu, C. Ni, and G.C. Hadjipanayis, Microstructure of Sintered ND-Fe-Ga-B Magnets with Mo and MoS2 Addition, J. Magn. Magn. Mater., 2012, 324, p 1391–1396CrossRefGoogle Scholar
  9. 9.
    K. Uestuener, M. Katter, and W. Rodewald, Dependence of the Mean Grain Size and Coercivity of Sintered Nd-Fe-B Magnets on the Initial Powder Particle Size, IEEE Trans. Magn., 2006, 42(10), p 2897–2899CrossRefGoogle Scholar
  10. 10.
    W.F. Li, T. Ohkubo, K. Hono, and M. Sagawa, The Origin of Coercivity Decrease in Fine Grained Nd-Fe-B Sintered Magnets, J. Magn. Magn. Mater., 2009, 321, p 1100–1105CrossRefGoogle Scholar
  11. 11.
    H. Sepehri-Amin, T. Ohkubo, K. Hono, K. Guth, and O. Gutfleisch, Mechanism of the Texture Development in Hydrogen-Disproportionation-Desorption-Recombination (HDDR) Processed Nd-Fe-B Powders, Acta Mater., 2015, 85, p 42–52CrossRefGoogle Scholar
  12. 12.
    F. Bittner, T.G. Woodcock, L. Schultz, C. Schwobel, O. Gutfleisch, G.A. Zickler, J. Fidler, K. Ustuner, and M. Katter, Normal and Abnormal Grain Growth in Fine-Grained Nd-Fe-B Sintered Magnets Prepared from He Jet Milled Powders, J. Magn. Magn. Mater., 2017, 426, p 698–707CrossRefGoogle Scholar
  13. 13.
    J.W. Kin, W.S. Lee, J.M. Byun, S.H. Kim, and Y.D. Kim, Grain Refinement in Heavy Rare Earth Element-Free Sintered Nd-Fe-B Magnets by Addition of a Small Amount of Molybdenum, J. Appl. Phys., 2015, 117, p 17B523CrossRefGoogle Scholar
  14. 14.
    W.H. Cheng, W. Li, C.J. Li, and X.M. Li, The Role of Nb Addition in Nd-Fe-B Sintered Magnets with High Performance, J. Alloys Compd., 2001, 319, p 280–282CrossRefGoogle Scholar
  15. 15.
    T.Y. Chu, T.S. Chin, C.H. Lin, and J.M. Yao, Evidence of Domain-Wall Pinning in W-Doped (NdDy)(FeCo)B Sintered Magnets, J. Appl. Phys., 1994, 76, p 6834–6836CrossRefGoogle Scholar
  16. 16.
    K. Essa, P. Jamshidi, J. Zou, M.M. Attallah, and H. Hassanin, Porosity Control in 316L Stainless Steel Using Cold and Hot Isostatic Pressing, Mater. Des., 2018, 138, p 21–29CrossRefGoogle Scholar
  17. 17.
    T. Yildiz, N. Kati, and A.K. Gur, The Effect of Sintering Temperature on Microstructure and Mechanical Properties of Alloys Produced by Using Hot Isostatic Pressing Method, J. Alloys Compd., 2018, 737, p 8–13CrossRefGoogle Scholar
  18. 18.
    H.V. Atkinson and S. Davies, Fundamental Aspects of Hot Isostatic Pressing: An Overview, Metall. Mater. Trans. A, 2000, 31A, p 2981–3000CrossRefGoogle Scholar
  19. 19.
    S. Irukuvarghula, H. Hassanin, C. Cayron, M.M. Attallah, D. Stewart, and M. Preuss, Evolution of Grain Boundary Network Topology in 326L Austenitic Stainless Steel During Powder Hot Isostatic Pressing, Acta Mater., 2017, 133, p 269–281CrossRefGoogle Scholar
  20. 20.
    J.L. Sulley, B.K. Bull, and A.C. Wood, Hot Isostatic Pressing of Large Bore, Stainless Steel Pipework for a Safety Critical Application, Adv. Mater. Res., 2012, 378, p 752–758Google Scholar
  21. 21.
    W.J. Mo, L.T. Zhang, A.D. Shan, L.J. Cao, J.S. Wu, and M. Komuro, Microstructure and Magnetic Properties of NdFeB Magnet Prepared by Spark Plasma Sintering, Intermetallics, 2007, 15, p 1483–1488CrossRefGoogle Scholar

Copyright information

© ASM International 2018

Authors and Affiliations

  1. 1.Institute of Advanced Materials and TechnologyUniversity of Science and Technology BeijingBeijingChina
  2. 2.State Key Laboratory for Advanced Metals and MaterialsUniversity of Science and Technology BeijingBeijingChina
  3. 3.Department of Mechanical EngineeringUniversity of South FloridaTampaUSA

Personalised recommendations