NdFeB magnets; intergranular addition; magnetic

作者:莫文剑;张澜庭;刘琼珍;单爱党;吴建生;Komuro Matahiro;沈丽萍;
关键词:NdFeB magnets; intergranular addition; magnetic

properties; corrosion resistance; microstructure; rare earths
单位:School of Materials Science and Engineering  Shanghai Jiao

Tong University,School of Materials Science and Engineering

Shanghai Jiao Tong University,School Block neodymium magnet of Materials Science and

Engineering Shanghai Jiao Tong University,School of Materials

Science and Engineering Shanghai Jiao Tong University,School of

Materials Science and Engineering Shanghai Jiao Tong

University,Advanced Research Laboratory Hitachi Ltd. Hitachi-shi

Ibaraki-ken 319-1292 Japan,http://www.chinamagnets.biz/Neodymium/Block-neodymium-magnet.php Hitachi (China) Research & Development

Corporation Shanghai Branch,,Shanghai 200240 China,Shanghai

200240 China,Shanghai 200240 China,Shanghai 200240 China,Shanghai

200240 China,Shanghai 200020 China
摘要:Microstructure and corrosion resistance of sintered

Nd15Dy1.2Fe77Al0.8B6 and Nd22Fe71B7 magnets modified by

intergranular addi- tion of MgO and ZnO were investigated. Both

the remanence and sintering density of the magnets increased

slightly with intergranular addi- tions of MgO and ZnO. There was

a remarkable increase in coercivity of Nd22Fe71B7 after addition.

Besides, the effects on magnetic proper- ties and an improved

corrosion resistance were observed. Compared with the native

magnets without addition, corrosion potential of the magnets with

MgO and ZnO additives was more positive and the current density

in the anodic branch of the polarization curve was reduced.

Corrosion resistance resulting from autoclave testing (2×105 Pa

of steam pressure, 120 °C) showed that the corrosion rate of

NdFeB magnets reduced with the increase of additive amount.

Microstructure observation revealed that MgO and ZnO additives

were incorporated into the intergranular phases in the magnets.

With the introduction of MgO and ZnO, more intergranular phase

with high oxygen content was formed while keeping the volume

fraction of all the intergranular phases almost unchanged, which

may contribute to improved corrosion resistance. Furthermore,

addition of MgO and ZnO refined the grain size of Nd22Fe71B7.