ISSN: 1003-6326
CN: 43-1239/TG
CODEN: TNMCEW

Vol. 10    No. 4    August 2000

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Effects of Ti and(or) Cu on microstructures and
magnetic properties of sintered Nd-Fe-B magnets①
SONG Xiao-ping(宋晓平), YANG Sen(杨 森), WANG Xian-hui(王献辉), SUN Zhan-bo(孙占波)
(Department of Physical Materals, School of Science, Xi′an Jiaotong University, Xi′an 710049, P.R.China)
Abstract: The alloying elements Ti and(or) Cu were added into the intergranular regions of sintered Nd-Fe-B magnets and their effects on microstructures and magnetic properties of the magnets were investigated. The results showed that a small amount of Ti and(or) Cu additions can enhance the coercivity and have little effect on the remanence of Nd-Fe-B magnets. Compared with individual addition of pure Ti or Cu elements, Ti and Cu co-addition of intergranular region is more efficient to improve the coercivity of the magnets. The improvement of the coercivity can be attributed to the segregation of Cu element on the surface of the magnetic phase (Nd2Fe14B) and the occurrence of fine Nd-Fe-Ti particles near grain boundaries. The former can prevent the magnetic coupling of Nd2Fe14B grains to a certain degree and impede effectively the propagation of reversed domain walls through the magnetic phase grains. The latter can inhibit the growth of
magnetic phase grains during the sintering process, resulting in a finer grain size. Both are beneficial to the coercivity enhancement. With increasing Ti content above 0.8%, a strip Ti-rich phase appears in the intergranular region, resulting in the dramatic reduction of the remanence of Nd-Fe-B magnets.
Key words: NdFeB magnets; microstructure; coercivity
Superintended by The China Association for Science and Technology (CAST)
Sponsored by The Nonferrous Metals Society of China (NFSOC)
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