Effects of Hot Pressing and Deforming on the Microstructure and Properties of NdFeB Magnets

Abstract:

In this paper, the NdFeB magnets were prepared by hot pressing and deforming, the influence of pressing temperature, pressing strain, deforming temperature, deforming rate and amount on the density, hardness and magnetic properties of magnets were analyzed with the microstructure analysis. The results show that the density of the magnets and the hardness increase with the increase of the hot pressing temperature and pressure, but the hardness decreases when the pressing temperature reaches 800°C.After thermal deformation, the gap of the magnets reduced, the density is increased, the hardness becomes larger, and the grains are oriented in the direction of deformation, which leads to higher magnetic properties. However, when the deformation rate is too low, or the deformation temperature is too high, there is an abnormal phenomenon of grain growth, leading to the decrease of coercivity and harness of the material.

• Periodical: Materials Science Forum (Volume 852)
• Pages: 194-198
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.852.194
• Online since: April 2016
• Authors: Chun Hong Li*, Feng Li, Deng Ming Chen, Jiang Lin Zhao, Yi Long Ma, Qiang Zheng, Bing Bing Li
• Keywords: Density, Hardness, Hot Deforming, Hot Pressing, Magnetic Properties

References

[1] H.T. Kim S.H. Cho Y.B. Kim K.S. Ryu G.A. Kapustin H.S. Kim. NdFeB thin anisotropic magnets obtained by hot working process. Journal of Magnetism and Magnetic Materials 272-276(2004) e1925-e1927.

DOI: 10.1016/j.jmmm.2003.12.906

[2] PAN Minxiang, ZHANG Pengyue, LI Xianjun, GE Hongliang, WU Qiong, JIAO Zhiwei, LIU Tingting. Effect of Terbium addition on the coercivity of sintered NdFeB magnets. JOURNAl OF RARE EARTHS, 2012, 28: 399-402.

DOI: 10.1016/s1002-0721(10)60300-6

[3] DONG Xueliang, WANG Deren, ZENG Yangqing. Effect of mechanical attrition on microstructure and properties of electro-deposition coating on NdFeB. JOURNAl OF RARE EARTHS, 2014, 32(9): 867-873.

DOI: 10.1016/s1002-0721(14)60155-1

[4] YU Lianqing, HUANG Cuicui. Effect of Zr on High properties Consistency of NdFeB Magnets. RARE METAL MATERIALS AND ENGINEERING, 2009, 38(3): 465-467.

[5] Kirchnery A, Grünbergery W, Gutfleischz W, et al. Comparison of the magnetic properties and deformation behaviour of Nd-Fe-B magnets made from melt- spun, mechanically alloyed and HDDR powders [J]. Journal of Physics D: Applied Physcis, 1998, 31: 1660-1668.

DOI: 10.1088/0022-3727/31/14/008

[6] HUANG Youlin, HOU Yuhua, MA Shengcan, et al. Influences of Stain Rate on the Microstructure and Properties for Hot Deformed NdFeB Magnets. RARE METAL MATERIALS AND ENGINEERING, 2014, 43(11): 2748-2752.

[7] R.S. Sheridan, R. Sillitoe, M. Zakotnik, et al. Anisotropic powder from sintered NdFeB magnets by the HDDR processing route[J]. Journal of Magnetism and Magnetic Materials, 324(2012)63-67.

DOI: 10.1016/j.jmmm.2011.07.043

[8] LAI Bin, LI Yanfeng, WANG Huijie, et al. Model of temperature field for the preparation process of melt-spun NdFeB powders [J]. Journal of Rare Earths, 2014, 32(6): 514-520.

DOI: 10.1016/s1002-0721(14)60101-0

[9] Yu L Q ，Wen Y H ，Yan M． Effects of Dy and Nb on the mag-netic properties and corrosion resistance of sintered NdFeB［J］．Journal of Magnetism and Magnetic Materials，2004，283( 4) : 353.

DOI: 10.1016/j.jmmm.2004.06.006

[10] TU Shaojun, YAN Mi, CUI Xigui, NI Junjie, JIN Yibiao. Improvement of Corrosion Resistance of Sintered NdFeB Magnets by Intergranular Addition of AIN Nanopowders. RARE METAL MATERIALS AND ENGINEERING, 2010，39（10）：1777-1780.

[11] Tian Hao, Jin Dongzhe, Li Ying, et al. Microstructure and Magnetic properties of Anisotropic Nd-Fe-B Magnets Fabricated by Single-Stage Hot Deformation [J]. Journal of Rare Earths, 2006, 24: 318-320.

DOI: 10.1016/s1002-0721(07)60390-1

[12] Song Jie, Yue Ming, Zuo Jianhua, et al. Structure and magnetic properties of bulk nanocrystalline Nd-Fe-B permanent magnets prepared by hot pressing and hot deformation[J]. Journal of Rare Earths, 2013, 31(7): 674-678.

DOI: 10.1016/s1002-0721(12)60341-x

[13] LAI Bin, LIU Guojun, WANG Huijie, PAN Wei, ZHU Minggang. Effect of Hot-deformed Temperature on Magnetic Properties of Nanograin Nd-Fe-B Magnets. Metallic Functional Materials, 2011, 3(18): 1-4.