新型永磁材料的研究

本文综述了我们对强各向异性永磁材料的研究结果．通过对各向异性稀土．铁氮永磁材料的结构和磁性的关系研究，利用速凝等技术实现对反磁化形核场的控制，获得了单晶颗粒型稀土铁氮化物，进而实现了高矫顽力和高磁能积．开发的稀土铁氮磁粉最大磁能积达到40MGOe以上．发现了HDDRNd2Fel4B各向异性形成的关键机制在于歧化阶段形成的具有“耗散结构特征”的柱状歧化微结构，据此提出了可以稳定生产高性能各向异性Nd—Fe．B的HDDR工艺，成功制备了磁能积为27MGOe的三元Nd—Fe—B磁粉和41MGOe多元Nd—Fe．B磁粉．同时还发现可以通过调控其微观结构来实现提高HDDR磁粉的矫顽力．另外利用铁磁Mn基材料强磁各向异性的特点，在无稀土永磁材料方面开发了纳米结构且具有反常矫顽力温度系数的MnBi磁体．上述成果的取得为高性能各向异性稀土粘结磁体的产业化提供了可能．

Study of novel hard magnetic materials

In this work we systematically review our results about the permanent magnetic materials. We have investigated the structural and magnetic properties of the rare earth-iron based nitrides. Our investigations indicate that the hard magnetic properties of rare earth-iron nitrides are controlled by the domain nucleation. The high performance magnetic powders with maximum energy product of 43 MGOe can be obtained by creating single crystal particles, which could decrease the domain nucleation field. We also find the formation of the texture in HDDR NdFeB is related to the dissipative structure during the disproportional process. Highly textured HDDR magnetic powders can be achieved by controlling the HDDR process. The stability of the HDDR powders could be further improved through the microstructure modification. Finally, we also investigate Mn based hard magnetic materials, which show abnormal temperature coefficeient for coercivity. All these results may pave the road to produce bonded magnets with high performance.