Preparation of high coercivity and high thermal stability sintered Nd-Fe-B magnet by optimizing boundary microstructure
;;Gao Xue-xu;;;
北京科技大学
Cite this article:
Gao Xue-xu. Preparation of high coercivity and high thermal stability sintered Nd-Fe-B magnet by optimizing boundary microstructure. Acta Metall Sin, 2008, 44(7): 871-875 .
Abstract Sintered Nd-Fe-B magnet with super-high coercivity and high thermal stability was achieved by blending 3wt%Dy2O3 powder and 3wt% (NdDyTb)25(FeCoNbTiGaAl)68B7 powder to near stoichiometric (NdDyTb)12.69(FeCoNb)84.01B6.00 main alloy powder. The intrinsic coercivity Hci with 3028kA/m, the maximum energy product (BH)max with 254 kJ/m3, the temperature coefficient (22-220℃) of remanence and intrinsic coercivity with -0.104%/ ℃ and -0.356%/ ℃, respectively, and irreversible flux loss at 260℃ near 4% were accomplished. Microstructure analyses indicated that that Nd2Fe14B grain boundaries were smooth and straight and the distribution of Nd-rich phase around Nd2Fe14B grain was continuous and uniform. Dy was rich in near the extension layer of Nd2Fe14B grains, indicating Dy element in Dy2O3 powder diffused and substituted Nd element in Nd-rich phase and the extension layer of Nd2Fe14B grains, which increased magnetic anisotropy of boundary of Nd2Fe14B grains only and depressed the nucleation formation and expansion of reverse magnetization domain. Furthermore, ideal microstructural model of Dy distribution in Nd-Fe-B sintered magnets with high intrinsic coercivity was presented.
[1]Kaneko Y,Kuniyoshi F,Ishigaki N.J Alloy Compd,2006; 408-412:1344 [2]Bao X Q,Li Q H,Zhu X X,Zhu J,Gao X X,Zhang M C, Zhou S Z.J Univ Sci Technol Beijing,2006;28:850 (包小倩，李青华，朱学新，朱洁，高学绪，张茂才，周寿增．北京科技大学学报，2006；28：850) [3]Bai G,Gao R W,Sun Y,Han G B,Wang B.J Magn Magn Mater,2007;308:20 [4]Zhou S Z,Tang W Z,Wang R.Acta Metall Sin,1990;26: 290 (周寿增，唐伟忠，王润．金属学报，1990；26：290) [5]Pandian S,Chandrasekaran V,Markandeyulu G,Iyer K J L,Rama Rao K V S.J Appl Phys,2002;92:6082 [6]Gabay A M,Zhang Y,Hadjipanayis G C.J Magn Magn Mater,2002;238:226 [7]Pandian S,Chandrasekaran V,Markandeyulu G,Iyer K J L,Rama Rao K V S.J Alloy Compd,2004;364:295 [8]Vial F,Jolly F,Nevalainen E,Sagawa M,Hiraga K,Park K T.J Magn Magn Mater,2002;242-245:1329 [9]Zhou S Y,Zhou L,Chen S K,Luo J J.Rare Met Mater Eng,2006;35:1006 (周圣银，周廉，陈绍楷，罗建军．稀有金属材料与工程，2006；35：1006) [10]Madaah Hosseini H R,Kianvash A,Seyyed Reihani M, Yoozbashi Zadeh H.J Alloy Compd,2000;298:319 [11]Cheng W H,Li W,Li C J,Li X M,Dong S Z.Acta Metall Sin,2001;37:1271 (成问好，李卫，李传建，李岫梅，董生智．金属学报，2001；37：1271) [12]Hu J F ,Liu Y L,Yin M L,Wang Y Z,Hu B P,Wang Z X.J Alloy Compd,1999;288:226 [13]de Groot C H,Buschow K H J,de Boer F R,de Kort K. J Appl Phys,1998;83:388 [14]Chen Z M,Yah A R,Wang X T,Hadjipanayis G C.J Appl Phys,1997;81:4456
