两种方法制备纳米晶复相Nd_2Fe_(14)B/α-Fe永磁体实验研究

Research on Preparing Permanent Magnets of Nanocomposite Nd_2Fe_(14)B/α-Fe by Two Methods

将机械球磨后制备的Nd2Fe14B非晶粉末和α-Fe纳米晶粉末分别采用2种方法制备纳米复相Nd2Fe14B/α-Fe永磁体。第1种方法是直接将其冷压制坯、真空包套和热挤压制备永磁体。第2种方法是先将Nd2Fe14B晶化,然后冷压制坯、真空包套和热挤压制备永磁体。利用TEM、VSM等分析手段对比研究了2种方法制备永磁体的相对密度、微观组织以及磁性能。结果表明:在相同的工艺参数下,第1种方法制备永磁体不仅可以减少工序,而且其制备的永磁体综合性能均优于第2种方法,其制备永磁体的相对密度为98.24%;Nd2Fe14B和α-Fe的晶粒尺寸分别为60和80nm;磁性能达到:Br=0.98T,Hci=305.6kA/m,和(BH)m=89.8kJ/m3。

Amorphous Nd2Fe14B and nanocrystalline α-Fe obtianed by mechanical balll milling were prepared into nanocomposite Nd2Fe14B/α-Fe permanent-magnets by two methods. In the first method, permanent magnet was prepared by hot extrusion of vacuum canned cold-pressed compacts of amorphous Nd2Fe14B and nanocrystalline α-Fe. In the second method, permanent magnet was prepared by hot extrusion of vacuum canned cold-pressed compacts of crystallized Nd2Fe14B and nanocrystalline α-Fe. By means of TEM and VSM, relative density, microstructure and magnetic properties of nanocomposite Nd2Fe14B/α-Fe permanent-magnets were invstigated. The results show that under the same technological parameters, comparing to the second method, procedure can be reduced in the first method and magnetic properties of the prepared permanent-magnet are also higher. Relative density of 98.24%, 60 nm Nd2Fe14B and 80 nm α-Fe, higher magnetic properties such as Br=0.98T, Hci=305.6 kA/m, and (BH) m=89.8 kJ/m 3 can be obtained in the permanent-magnet prepared by the first method.