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Title: Achievement of high coercivity in sintered R-Fe-B magnets based on misch-metal by dual alloy method

The R-Fe-B (R, rare earth) sintered magnets prepared with different ratio of alloys of MM-Fe-B (MM, misch-metal) and Nd-Fe-B by dual alloy method were investigated. As expected, the high ratio of MM-Fe-B alloy degrades the hard magnetic properties heavily with intrinsic coercivity lower than 5 kOe. When the atomic ratio MM/R ≤ 21.5% the magnetic properties can reach a practical level of B{sub r} ≥ 12.1 kGs, H{sub cj} ≥ 10.7 kOe, and (BH){sub max} ≥ 34.0 MGOe. And the effect of H{sub cj} enhancement by the grain boundary diffusion process is obvious when MM/R ≤ 21.5%. It is revealed that the decrement of intrinsic magnetic properties of R{sub 2}Fe{sub 14}B matrix phase is not the main reason of the degradation of the magnets with high MM ratio. The change of deteriorated microstructure together with phase component plays fundamental roles in low H{sub cj}. In high MM ratio magnets, (a) after annealing, Ce atoms inside main phase are inclined to be segregated in the outer layer of the main phase grains; (b) there is no thin layer of Ce-rich phase as an analogue of Nd-rich phase to separate main phase grains; (c) excessive Ce tends to form CeFe{sub 2} grains.
Authors:
;  [1] ;  [2] ; ; ;  [3] ; ; ;  [3] ;  [4]
  1. State Key Laboratory for Magnetism, Institute of Physics, Chinese Academy of Sciences, P. O. Box 603, Beijing 100190 (China)
  2. (China)
  3. Beijing Zhong Ke San Huan Research, No.10 Chuangxin Road, Changping District, Beijing 102200 (China)
  4. (Beijing) Magnetics Co., Ltd., No.23 Chuangxin Road, Changping District, Beijing 102200 (China)
Publication Date:
OSTI Identifier:
22271187
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 11; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 36 MATERIALS SCIENCE; ANNEALING; COERCIVE FORCE; CONCENTRATION RATIO; DIFFUSION; GRAIN BOUNDARIES; IRON BORIDES; LAYERS; MAGNETIC MATERIALS; MAGNETIC PROPERTIES; MAGNETS; MATRIX MATERIALS; MISCH METAL; RARE EARTH COMPOUNDS; RARE EARTHS; THIN FILMS