文章信息/Info

Title:

Effects of Cerium on Permanent Magnetic Properties of Sintered Nd-Fe-B Magnets

作者:

饒曉雷 鈕萼 胡伯平

中科三環(huán)研究院

Author(s):

RAO Xiaolei;  NIU E;  HU Boping

Zhong Ke San Huan Research

關鍵詞:

Ce混合價; CeFe2; 釹鐵硼; 燒結(jié); 快淬; 雙合金; 雙主相

Keywords:

Ce mixed valence;  CeFe2;  Nd-Fe-B;  sinter;  rapidly quench;  dual-alloy;  dual-main-phase

DOI:

10.7502/j.issn.1674-3962.2017.01.09

文獻標志碼:

A

摘要:

Ce在鑭系元素中是具有特殊性質(zhì)的一員，其根源在于它的混合價特性。在Ce2Fe14B化合物中，Ce表現(xiàn)出強烈的+4價傾向，不僅自身4f電子缺失無法貢獻稀土離子磁性，而且離子半徑過小導致Fe-Fe間距縮減，使Ce2Fe14B居里溫度和飽和磁極化強度都以較大幅度下降。另外，在Ce-Fe-B三元合金中，Ce傾向于生成Laves相CeFe2，而非富稀土低熔點晶界浸潤相，不能在燒結(jié)磁體中產(chǎn)生使主相晶粒退磁耦合的矯頑力機制，燒結(jié)Ce-Fe-B難以實現(xiàn)高矯頑力。盡管如此，Ce2Fe14B仍具有優(yōu)良的內(nèi)稟磁性，通過快淬方法可制備出性能適中的(Ce,Nd)-Fe-B各向同性磁粉，而通過貧Ce富Nd和貧Nd富Ce雙合金或雙主相燒結(jié)的方法，用富Nd相承擔分割主相晶粒提高矯頑力的功能，也實現(xiàn)了高性價比(Ce,Nd)-Fe-B燒結(jié)磁體的商品化。本文針對Ce影響釹鐵硼磁體內(nèi)稟磁性和矯頑力方面的研究工作進行了綜合闡述。

Abstract:

Cerium is a very special element in Lanthanide, originating from its mixed valence characteristics. Ce exists in Ce2Fe14B as Ce4+ ion. The lack of 4f electron leads Ce4+ to make no contribution to magnetism. Small ion radius shrinks the Fe-Fe distances and decreases the Curie temperature and saturation polarization of Ce2Fe14B. In addition, it is in favor of CeFe2 Laves phase instead of Ce-rich phase to magnetically decouple Ce2Fe14B grains. Sintered Ce-Fe-B magnet has very poor coercivity. Rapidly quenched isotropic (Ce,Nd)-Fe-B powder can realize reasonable HcJ for certain applications. By dual-alloy or dual-main-phase techniques, using Ce-rich/Nd-lean alloy and Nd-rich/Ce-lean alloy as starting materials, sintered (Ce,Nd)-Fe-B magnet is commercialized with high ratio of performance to cost. The key point is to let Nd-rich phase decouple (Ce,Nd)2Fe14B grains. This article reviews the effects of Cerium on the intrinsic and extrinsic magnetic peroperties of Nd-Fe-B permancent magnets.