渗Dy烧结Nd-Fe-B磁体矫顽力温度稳定性

Temperature stablity of coercivity of Dy-diffused Nd-Fe-B sintered magnet

将3 mm厚的N40SH牌号烧结Nd-Fe-B磁体进行热蒸发渗Dy处理,研究了渗Dy磁体的微观结构及温度稳定性。结果表明,渗Dy磁体中Dy分布存在两方面的不均匀性,一是磁体表层晶粒上形成"核-壳"结构,"壳"中富集Dy并形成(Pr,Nd,Dy)_2Fe_(14)B相。二是从磁体表层向内部Dy含量降低。渗Dy处理后,常温下磁体矫顽力增加6.26 k Oe。温度系数和磁通老化损失分析表明,渗Dy磁体的温度稳定性优于基体磁体,而比同等矫顽力的常规磁体略差。

3-mm thick N40SH grade sintered Nd-Fe-B magnets were Dy-diffused by thermal evaporation method,and their micrsostructure and temperature stablity were investigated.The results show that the distribution of Dy is inhomogenous in Dy-diffused magents.One part of inhomogenty refers to that the core-shell structure of grains colse to the sureface of magnet.The shell contain Dy-rich(Pr,Nd,Dy)2Fe14B phase.The other part of inhomogenty indicates the Dy concentration decreases from the surface to the interior of the magent.After Dy-diffusion the coercivity of the magnet is increased by6.26kOe at room temperature.The results of teperature cofficients and magnetic flux loss indicate that the temperature stablity of Dy-diffused magnet is better than that of original magnet,but is little worse than that of the conventional magnet with the the same coercivity.