含铌钕铁硼永磁体的纳米晶粒微观结构与矫顽力机制模型  

Nanometer Grain Microcosmic Structure And Coercivity Mechanism Model of NdFeB Magnet With Nb

作　　者：潘树明[1] 平爵云[2] 刘金芳 马如璋[2] 

机构地区：[1]北京有色金属研究总院 [2]北京科技大学材料物理系,北京100080

出　　处：《中国稀土学报》2003年第z1期125-129,共5页Journal of the Chinese Society of Rare Earths

摘　　要：运用1000kV超高压电子量微镜和Mossbauer谱仪结合磁测量,研究了含Nb钕铁硼永磁体的纳米微观结构与矫顽力机制模型。加入Nb,Ga等元素的NdFeB合金(3种化学元素以上组成Nd Fe B合金)的矫顽力变化机制用现有的成核硬化模型、界面局域钉扎、均匀钉札都不能解释,必须有一种新的矫顽力机制模型,这种新的模型提出的基础是畴壁受激活能作用而移动,当激活能足够大时,畴壁可克服阻力而脱出,从研究热涨落场和矫顽力关系引出研究三元以上NdFeB合金的理论,即"动态交叉,组合补益",要使这种动态交叉能补益必须去寻找Nb,Ga等元素加入量,文内提出以2%为宜。作者提出"晶粒细化局域钉札"模型可解释三元以上NdFeB的矫顽力变化机制。文内观察到的加Nb后出的Fe2Nb相(a=0.382nm,c=0.787nm)存在于Nd2Fe14B主相内,属Laves相。通过Mossbauer变研究得出:Nb进入e,c晶位,减少面各向异性,提高单轴各向异性,Nb主要在晶界,这是提高矫顽力原因之一。Nb和Ga以适量的添加即复合添加,可提高矫顽力,从而改善合金的热稳定性。This paper uses 1000 kV super high voltage electronic microscope and Mossbauer spectrometer as well as magnetic measurement to study the nanometer grain microcosmic structure and coercivity mechanism model of NdFeB magnets with Nb. The coercivity change mechanism of NdFeB alloy added with Nb, Ga (NdFeB alloy with more than 3 elelments) can not be explained by current nucleation hardening model, boundary local pinning or uniform pinning. So there should be a new coercivity mechanism model, the base of this model is that the domain wall can be moved by activation energy. When activation energy is big enough, the domain wall will break block out. A theory 'Dynamic Cross and Complementary Combination' on NdFeB alloy with more than 3 elelments is introduced from the relation of thermal fluctuation field and coercivity. To make the dynamic cross complement, it should find out the addition amount of Nd, Ga, this paper suggests a proper amount of 2%. The 'grain finery local pinning' model given out by the author explains the coercivity change mechanism of NdFeB alloy with more than 3 elelments. FeNb_2 phase (a=0.382 nm, c=0.787 nm) appeared after addition of Nb is located in the main phase Nd_2Fe_(14)B and belongs to Laves phase. By Mossbauer, this paper gives out the effect of added Nb: Nb enters into e, c grain positions, decreasing face anisotropy and increasing single axis anisotropy. Nb is primarily located at grain boundary, which is one of the reason for increasing coercivity. The proper composite addition of Nb and Ga can increase coercivity and improves the thermal stability of alloy.

关 键 词：永磁合金 钕铁硼 纳米晶 微观结构 矫顽力 模型 

分 类 号：TM273[一般工业技术—材料科学与工程]