贫稀土钕铁硼合金与Nd_(67)Cu_(33)混粉热变形磁体组织演变过程及其对磁体矫顽力的影响  

Microstructure evolution process of die-upset magnets with mixed powder of lean rare earth-iron-boron alloy and Nd_(67)Cu_(33) and its effects on coercivity of the magents

作　　者：陈兵 蒋美琴[1] 肖恢芸 潘晶[1] 刘新才[1] CHEN Bing;JIANG Meiqin;XIAO Huiyun;PAN Jing;LIU Xincai(Faculty of Materials Science and Chemical Engineering, Ningbo University, Ningbo 315211,China)

机构地区：[1]宁波大学材料科学与化学工程学院,浙江宁波315211

出　　处：《功能材料》2018年第3期3097-3102,共6页Journal of Functional Materials

基　　金：国家自然科学基金资助项目(51274125;51174121);浙江省重点科技创新团队资助项目(2012R10016-08)

摘　　要：分别真空感应快淬贫稀土钕铁硼合金Nd_(11.5)Fe_(81.8)B_(6.0)Nb_(0.7)与Nd_(67)Cu_(33)薄带,然后制备Nd_(67)Cu_(33)含量0,3%,6%,9%,12%(质量分数)的混粉热变形磁体,分析讨论了贫稀土钕铁硼合金与Nd_(67)Cu_(33)混粉变形磁体中组织演变过程及其对磁体矫顽力的影响。研究结果表明,在热变形过程中当变形量由0增到30%时,混粉热变形磁体中Nd-Cu的扩散导致与之相邻区域的α-Fe晶粒尺寸减小、局部出现富稀土相、2∶14∶1相中稀土含量部分补偿性增加,整个磁体中α-Fe相体积分数减少、2∶14∶1相与软磁相α-Fe交换耦合作用增强,混粉热变形磁体的矫顽力随变形量的增加而增大;当变形量进一步增加,在双相磁体中富稀土相消失,2∶14∶1相和α-Fe相晶粒尺寸增大,一旦α-Fe晶粒尺寸超过交换耦合的临界尺寸将导致双相交换耦合作用恶化,2∶14∶1相晶粒尺寸增大导致其对磁体矫顽力的贡献降低,整个混粉热变形磁体的矫顽力随变形量的增加而大幅度下降;当变形量达到70%时,混粉热压热变形磁体随Nd_(67)Cu_(33)添加量的增加尽管2∶14∶1等效平均晶粒尺寸增大但磁体的矫顽力不断提高,原因在于随Nd_(67)Cu_(33)的增加磁体分别出现α-Fe消失、富稀土晶界相出现、且富稀土晶界相体积分数增大,富稀土晶界相的去磁耦合作用增强。The flakes of both Nd11.5Fe81.8B6.0Nb0.7and Nd67Cu33were prepared respectively at argon atmosphere within vacuum induction furnace.The mixed powder with0,3%,6%,9%and12%Nd67Cu33were hot-pressed and then die-upset.The microstructure evolution process of the die-upset magnets during the deformation and its effect on their coercivity have been discussed.The results show that when the deformation is increased from zero to30%,the grain size ofα-Fe with neighbouring Nd-Cu particles decreases,the rich-rare earth phase appears locally,and the rare-earth content of2∶14∶1partly compensates.The volume fraction ofα-Fe in the magnets is reduced.And the exchange-spring effect is strengthened.So the coercive forces of the magnets are raised as the deformation increases.If it further does,the local rich-rare-earth phase disappears in the magnets with both2∶14∶1andα-Fe phase at last,and their grain sizes will enlarge.As soon as theα-Fe grain size is above the critical exchange-spring one,its effect of the whole die-upset magnets will deteriorate.And the contribution of2∶14∶1with the larger grain size to the coercivity will fall.So the coercivity of the whole magnets will sharply cut down as the deformation further increases.At the deformation70%,although the equivalent-average grain size is increased as the content of Nd67Cu33increasing,the coercivity of the die-upset magnets is still gone up.For the phenomena occur successively,α-Fe disappears,the rich-rare-earth gain boundary phase appears and its volume fraction increases,which enhances the magnetically decoupling.

关 键 词：贫稀土钕铁硼 混粉热变形 α-Fe相体积分数 2∶14∶1相等效平均晶粒尺寸 组织与矫顽力的演变 交换耦合 

分 类 号：TG113.225[金属学及工艺—物理冶金]