The Impact Induced Demagnetization Mechanism in NdFeB Permanent Magnets
LI Yan-Feng1,3, ZHU Ming-Gang1**, LI Wei1, ZHOU Dong1, LU Feng2, CHEN Lang2, WU Jun-Ying2, QI Yan3, DU An3
1Division of Functional Materials, Central Iron and Steel Research Institute, Beijing 100081 2State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081 3College of Science, Northeastern University, Shenyang 110819
Abstract：Compression of unmagnetized Nd2Fe14B permanent magnets is executed by using shock waves with different pressures in a one-stage light gas gun system. The microstructure, crystal structure, and magnetic properties of the magnets are examined with scanning electronic microscopy, x-ray diffraction, hysteresis loop instruments, and a vibrating sample magnetometer, respectively. The NdFeB magnets display a demagnetization phenomenon after shock wave compression. The coercivity dropped from about 21.4 kOe to 3.2 kOe. The critical pressure of irreversible demagnetization of NdFeB magnets should be less than 4.92 GPa. The coercivity of the NdFeB magnets compressed by shock waves could be recovered after annealing at 900°C and 520°C for 2 h, sequentially. The chaotic orientation of Nd2Fe14B grains in the compressed magnets is the source of demagnetization.
[1] Bancroft D, Peterson E L, Minshall S et al 1956 J. Appl. Phys.27 291 [2] Neilson F W and Anderson G W 1957 Bull. Am. Phys. Soc. Ser. II2 302 [3] Kulterman R W, Neilson F W and Benedick W B 1958 J. Appl. Phys.29 500 [4] Royce E B 1966 J. Appl. Phys.37 4066 [5] Graham R A 1968 J. Appl. Phys.39 437 [6] Gust W H and Royce E B 1970 J. Appl. Phys.41 2443 [7] Wang R J, Li F Y, Wang J F and Luo Y 1988 Chin. Phys. Lett.5 85 [8] Prishchepenko A and Tretyakov D 1999 12th IEEE International Pulsed Power Conference (Monterey California 27–30 June 1999) 2 856 [9] Shkuratov S I, Talantsev E F, Dickens J C and Kristiansen M 2002 IEEE Trans. Plasma Sci.30 1681 [10] Shkuratov S I, Talantsev E F, Baird J, Altgilbers L L and Stults A H 2007 12th IEEE International Pulsed Power Conference (Albuquerque, New Mexico 17–22 June 2007) 2 1347 [11] Chernyshev V K, Selemir V D and Plyashkevich L N 1997 Megagauss and Megaampere Pulse Technology and Applications (Russia, Sarov: VNIIEF Press) [12] Altgilbers L L, Brown M D J, Grishnaev I, Novac B M, Smith I R, Tkach I and Tkach Y 2000 Magnetocumulative Generators (New York: Springer-Verlag) [13] Talantsev E F, Shkuratov S I, Dickens J C and Kristiansen M 2002 Mod. Phys. Lett. B 16 545 [14] Shkuratov S I, Talantsev E F, Dickens J C and Kristiansen M 2002 Rev. Sci. Instrum.73 2738 [15] Shkuratov S I, Talantsev E F, Dickens J C and Kristiansen M 2002 J. Appl. Phys.92 159 [16] Shkuratov S I, Talantsev E F, Dickens J C and Kristiansen M 2003 J. Appl. Phys.93 4529 [17] Shkuratov S I, Talantsev E F, Dickens J C, Kristiansen M and Baird J 2003 Appl. Phys. Lett.82 1248 [18] Talantsev E F, Shkuratov S I, Dickens J C and Kristiansen M 2003 Rev. Sci. Instrum.74 225 [19] Shkuratov S I, Talantsev E F, Baird J, Altgilbers L L and Stults A H 2006 Rev. Sci. Instrum.77 066107 [20] Shkuratov S I, Talantsev E F, Baird J and Altgilbers L L 2010 IEEE Trans. Plasma Sci.38 1784 [21] Ramesh R, Chen J K and Thomas G 1987 J. Appl. Phys.61 2993 [22] Mo W J, Zhang L T, Liu Q Z, Shan A D, Wu J S and Komuro M 2008 Scr. Mater.59 179 [23] Liu J F, Ken M, Kottcamp E D, Walmer M, Bauser S, Higgins A and Liu S 2004 18th International Workshop on High Performance Magnets and Their Applications (Annecy France 29 August–2 September 2004) p 616 [24] Faria R N, Takiishi H and Lima L F C P 2001 J. Magn. Magn. Mater.234 43 [25] Schneider G, Henig E T, Stadelmaier H H and Petzow G 1981 5th International Workshop on Rare-Earth Magnets and Their Applications (Roanoke Virginia 7–10 June 1981) p 347
2013, Vol. 30 
