摘要：
The flakes of both Nd11.5Fe81.8B6.0Nb0.7and Nd67Cu33were prepared respectively at argon atmosphere within vacuum induction furnace.The mixed powder with 0,3%,6%,9% and 1 2% 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 to 30%,the grain size ofα-Fe with neighbouring Nd-Cu particles decreases,the rich-rare earth phase ap-pears locally,and the rare-earth content of 2:14:1 partly compensates.The volume fraction of α-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 both 2:14:1 andα-Fe phase at last,and their grain sizes will enlarge.As soon as theα-Fe grain size is a-bove the critical exchange-spring one,its effect of the whole die-upset magnets will deteriorate.And the contri-bution of 2:14:1 with 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 deformation 70%,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.%分别真空感应快淬贫稀土钕铁硼合金Nd11.5Fe81.8B6.0Nb0.7与Nd67Cu33薄带,然后制备 Nd67Cu33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 Nd67Cu33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Nd67Cu33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Nd67Cu33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.
