三相烧结工艺对NdFeB磁体结构与性能的影响

Effect of Three Phases Sintering Technique on Properties and Microstructure of NdFeB Magnets

本文采用Nd2Fe14B、Nd55FeBCo和Nd86FeCu53相粉末共烧结的方法制得NdFeB磁体。研究发现通过3相烧结工艺制得NdFeB磁体的晶界相比常规工艺制得NdFeB磁体的晶界相更均匀。由于晶界存在大量的Nd-Cu4、NdCo3和NdCo2相,晶界相的平均电位大大升高,超过了主相Nd2Fe14B的电位。因而NdFeB磁体发生电化学腐蚀时,电流密度大大降低,耐腐蚀性能得到了显著的改善。磁体腐蚀失重从一般工艺的60.47 mg.cm-2下降至1.2 mg.cm-2,而磁体的磁性能基本保持不变。

NdFeB magnets are made by sintering with mixed powder of Nd2Fe14B,Nd55FeBCo and Nd86FeCu5.The results show that the phases in grain boundary sintered by three phases sintering technique are more uniform than that of common sintering technique.The average potential of the phases in grain boundary is greatly increased due to the existence of NdCu4,NdCo3 and NdCo2 phases.The potential of the phases in grain boundary sintered by three phases sintering technique is even higher than that of Nd2Fe14B,which results in the decrease of current density when electrochemical corrosion occurs.So,the corrosion resistance of NdFeB magnet is greatly improved.It is shown that through the three phases sintering technique,the loss weight of NdFeB magnet decreases from 60.47 mg·cm-2 to 1.2 mg·cm-2 while the magnetic properties of NdFeB magnet keep constant.