摘要
对快淬磁粉进行热压/热流变处理已成为制备高性能各向异性NdFeB磁体的-种重要方法,快淬粉的成分和结构极大地影响了磁体的热流变能力和磁性能.研究了辊速和喷射压力,对快淬磁粉结构和最终热流变磁体磁性的影响.提高辊速可以细化晶粒和增加快淬磁粉中的非晶含量,但非晶含量较高会不利于磁体热流变过程的晶粒取向和织构形成;而辊速较低会使快淬磁粉的晶粒尺寸较为粗大,降低其热流变能力和织构形成能力,最终降低热流变磁体的剩磁和最大磁能积.适合进行热流变处理的快淬带晶粒尺寸为25～40nm.减小喷射压力也可以细化晶粒,但不影响快淬磁粉的非晶含量. 当喷射压力〈0.07 MPa时,快淬粉的XRD谱出现新的衍射峰,可能为亚稳相,其含量随喷射压力的减小而增加.新相的出现和含量的增加使得热流变磁体的剩磁、矫顽力和最大磁能积都降低.获得的最佳快淬工艺为辊速25m/s,喷射压力为0.07MPa,该条件下制备的热流变磁体磁性能为Br=1.29T,（BH ）m=298.5kJ/m3,Hcj=920.17kA/m.
High-performance anisotropic NdFeB magnets can be prepared by hot deformation of melt-spun mag-netic powders.Influence of wheel speed and pressure difference between the inside and outside of the quartz tube on melt-spun NdFeB powders and subsequent die-upset magnets was studied in this work.Increase of wheel speed can refine grain size of main phase （Nd2Fe14B）or increase the content of the amorphous phase,but the amorphous was harmful for the grain orientation in the hot deformation process and then texture formation. However,the lower wheel speed will result in the big size of grains and was also not helpful for the hot deform-ation and texture formation.Too high or too low wheel speed will reduce the romance Br and the maximum en-ergy product （BH）m of the final deformed NdFeB magnets.The appropriate grain size with appropriate wheel speed in the melt-spun powders was 25-40 nm.Reduce of pressure difference can also refine the grain size but not affect the content of the amorphous.When the pressure difference was lower than 0.07 MPa,a new diffrac-tion peak was found in the XRD spectrum and we think it may be a metastable phase.The content of the possi-ble metastable phase increase with reduced pressure difference.The possible metastable phase will deteriorate the romance Br,the coercivity H cj and the maximum energy product （BH）m of the deformed magnets.The best melt-spinning process conditions in the work were obtained as follows.The optimal wheel speed was 25 m/s and the optimal pressure difference was 0.07 MPa.The magnetic properties of deformed magnets from melt-spun powder in the preparation condition was：Br=1.29 T,（BH）m=298.5 kJ/m3 ,H cj=920.17 kA/m.
出处
《功能材料》
EI
CAS
CSCD
北大核心
2014年第3期83-87,共5页
Journal of Functional Materials
基金
国家自然科学基金资助项目(50931001
51241009)
国家高技术研究发展计划(863计划)资助项目(2011AA03A402)
关键词
辊速
喷射压力
热流变
亚稳相
wheel speed
pressure difference
hot deformation
metastable phase
