NdFeB-CeFeB互扩散对其组织和磁性能的影响

Effect of mutual-diffusion between NdFeB and CeFeB on its microstructure and magnetic property

近年来由于Ce元素的价格优势和特殊性能,Ce掺杂NdFeB永磁体受到越来越广泛的关注。通过900℃均匀化处理、真空扩散焊接和900℃扩散处理制备了NdFeB-CeFeB扩散偶,探究了NdFeB和CeFeB互扩散对各自微观结构和磁性能的影响。扫描电子显微镜(SEM)和能谱分析(EDS)结果发现,随着900℃保温处理时间增长,组织中的第二相和孔洞逐渐消失。互扩散后Ce原子不能置换Nd2Fe14B中的Nd原子,而是主要被富Nd相捕获。而Nd原子扩散后置换Ce2Fe14B中的Ce原子,形成了(Nd0.615Ce0.385)2Fe14B和(Nd0.165Ce0.835)2Fe14B两相,证明(Nd1-xCex)2Fe14B化合物存在溶解间隙。两相区(Ce,Nd)FeB样品中Ce平均原子数约占总稀土原子数的69%,饱和磁化强度μ0MS约为1.46T,各向异性场μ0HA约为7.37T,其磁性能未因高Ce含量而大幅下降主要归功于两相组织的"核壳"结构和Nd对Ce价态的影响。

In recent years,Ce-doped NdFeB permanent magnets had attracted more and more attentions due to the price advantage and special properties of Ce element.In order to investigate the influence of mutual diffusion on its microstructure and magnetic properties,a NdFeB-CeFeB diffusion couple was firstly homogenized at 900℃and then treated with vacuum diffusion welding and diffusion process at 900℃.SEM and EDS analysis results show that secondary phases and cavities in the samples disappear gradually with increasing heat-treatment time.Instead of substituting the Nd atom in Nd2Fe14 B,the Ce atom is mainly captured by Nd-rich phase,while the Nd atom can substitute the Ce atom in Ce2Fe14 B,then a twophase structure composed of（Nd0.615 Ce0.385）2 Fe14 B and（Nd0.165 Ce0.835）2 Fe14 B forms,demonstrating the existence of miscibility gap in（Nd1-xCex）2 Fe14 B compound.The Ce content in the Ce（Nd）FeB samples is about 69 at.% of the total rare earth content while the saturated magnetizationμ0 MSand anisotropy fieldμ0 HAare about 1.46 Tand 7.37 T.The good magnetic properties of samples with high Ce content are attributed to the core-shell structure and the influence of Nd on valence state of Ce.