摘要
用磁控溅射法在烧结Nd-Fe-B磁体表面沉积Tb金属薄膜并进行晶界扩散处理,对比经不同热扩散温度及时间处理后的磁体组织和磁性能变化。结果表明,925℃×10 h+500℃×2 h为最佳晶界扩散工艺,可将磁体矫顽力提高到1630.9 kA·m^(-1),较原始磁体提升50%,同时剩磁和磁能积无明显下降,磁体仍具有较高的退磁曲线方形度。晶界扩散处理后磁体取向度有所提高,主相晶粒表面形成了明显的富Tb壳层结构,其厚度随离开磁体表面距离的增加逐渐变薄,随热扩散温度升高和时间延长逐渐增厚。长时间热扩散处理使磁体内形成沿晶界分布的连续薄层富Nd相,将主相晶粒彼此分隔,有效降低磁性相颗粒间交换耦合作用。能谱(EDS)分析表明,适当的热扩散工艺可使Tb元素扩散至磁体芯部,渗透厚度4 mm的磁体。
Diffusing Tb element through the grain boundary diffusion process(GBDP)to improve the coercivity had gradually be-come the main production process of commercial high-performance sintered Nd-Fe-B.However,the optimum diffusion conditions andthe distribution of the Tb element in the Tb-deposited magnets prepared by the GBDP with the magnetron sputtering method still needfurther investigation.Understanding the relationship between thermal treatment processes and the magnetic properties of the GBDPmagnet will help us to optimize the GBDP and provide the reference basis for practical production.A commercial sintered Nd-Fe-B per-manent magnet without Dy or Tb was used as the diffusion substrate.The initial(annealed)magnet was cut into small pieces along theorientation of the magnet.The thin film of Tb metal was deposited on the surface by the magnetron sputtering technology.Subsequent-ly,Tb-deposited samples were exposed to heat treatment in a vacuum at 825~1025 ℃ for 2~10 h and then annealed at 500 ℃ for 2 h.The magnetic properties of the magnet were measured by high field hysteresis meter Hy MPulse(Metis Instruments).Back scatteredelectron(BSE)images were obtained by JSM-7800 F field emission scanning electron microscope(FE-SEM)equipped with energy dis-persive X-ray spectroscopy(EDX)detector for the constituent analysis.The microstructure and magnetic properties of the magnet treat-ed with different diffusion temperatures and time were compared.The higher the diffusion treatment temperature was,the deeper theTb element could enter into the magnet.So that the coercivity enhanced gradually as the concentration of Tb element diffused into themagnet increased.The shell structure was formed on the surface of main phase grains.Energy dispersive spectrometer(EDS)analysisindicated that Tb element apparently gathered at the shell.That revealed Tb did not diffuse into the interior,but formed the(Nd,Tb)2Fe14 Bshell in the outer regions of the main phase grain.The thickness of the Tb-rich shell gradually became thinner with t
作者
安仲鑫
李胜利
孙良成
张建园
An Zhongxin;Li Shengli;Sun Liangcheng;Zhang Jianyuan(Department of Material Science and Engineering,Shandong University,Jinan 250061,China;Baotou Re-search Institute of Rare Earth,Baotou 014030,China)
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2021年第1期34-40,共7页
Chinese Journal of Rare Metals
基金
白云鄂博稀土资源研究与综合利用国家重点实验室基金项目(2016B1948)资助。
关键词
烧结ND-FE-B
磁控溅射
TB
晶界扩散
磁性能
sintered Nd-Fe-B
magnetron sputtering
Tb
grain boundary diffusion
magnetic properties
