制备工艺对NaFeB磁体力学性能的影响

采用速凝法在铸带炉中制备NdFeB铸带，再经烧结制得NdFeB磁体。研究了制备工艺对磁体力学性能的影响。并将其结果与采用感应炉制得的铸锭经相同烧结工艺得到的磁体的力学性能进行了比较。实验结果得出：铸带速度2．6m/s时磁体的抗弯强度约为231MPa，当铸带速度增大到4．0m/s，抗弯强度显著提高了50％；当氢含量从0．15％减少到0．047％，抗弯强度提高了1倍，达到270MPa，冲击功也从2．78kJ／m^2增加到7．58kJ／m^2，这是因为在烧结过程中氢原子穿过晶粒和晶界扩散，其扩散通道导致的微裂纹强烈影响磁体的抗弯强度；磁粉粒度从4．0um减少到2．9um时，磁体晶粒减小，组织致密，抗弯强度从213MPa增大到331MPa。铸锭法制备的烧结磁体的综合力学性能均比铸带法磁体的性能差得较多。

Effect of Preparation Techniques on Mechanical Properties of NdFeB

The NdFeB magnet was prepared by rapid solidification followed by sintering process. The dependence of mechanical properties of sintered NdFeB magnets on preparation techniques was studied. It was found that bending strength of the magnets produced by 4.0 m/s in strip cast speed is 50% larger than that of magnets by 2.6 m/s in strip cast speed because of the finer grains of magnets. The hydrogen remained in HD powders dramatically affected grain and grain boundaries of magnet. When the hydrogen content decreased from 0.15% to 0.047, the bending strength and impact toughness has increased by a factor of twice, which respectively reached to 270 MPa and 7.58 kJ/m^2. This is due to hydrogen atom diffusion into grain and its boundary to result in microcrack in magnet. When the mean particle size of magnet powder decreased from 4.0 um to 2.9 um, the bending strength increased from 213 MPa to 331 MPa because of decreasing grain size in magnet and body densification. The comprehensive mechanical properties of sintered powder magnet is much lower than that of by rapid solidification.