Nd_2Fe_(14)B/α-Fe纳米晶复合永磁材料的中子衍射结构分析及磁性研究

Neutron diffraction and magnetic properties of the nano-composite permanent Nd_2Fe_(14)B/α-Fe

用真空快淬法制备Nd12Fe84B6非晶态薄带,经700℃真空退火处理,获得Nd2Fe14B/α Fe双相纳米晶复合永磁材料。用中子衍射的方法对两种不同退火时间的样品进行室温相结构分析,并根据尺寸效应引起的衍射线展宽得到了晶粒的平均尺寸。研究结果表明:对退火时间为20min和90min的样品,Nd2Fe14B硬磁性相的平均晶粒大小分别为52.1nm和55.3nm,α Fe软磁性相的平均晶粒大小分别为61.5nm和66.2nm;软、硬磁性相的晶粒大小几乎没有变化。随着退火时间的增加,Nd2Fe14B硬磁性相的体积分数增加,而α Fe软磁性相的体积分数则减少。磁性测量及剩磁分析表明:90min的样品磁性能优于20min的样品,90min样品软、硬磁性相晶粒之间的交换耦合作用>20min的样品。

The amorphous Nd12Fe84B6 ribbons were prepared using the meltspinning method. The nanocomposite structure obtained by crystallizing the as-made amorphous meltspun ribbons was investigated by neutron diffraction. The results show that grain size of magnetically hard 2∶14∶1 was 52.1nm and 55.3nm for annealing at 700℃ for 20min and 90min respectively, and the grain size of soft αFe phases were 61.5nm and 66.2nm. The results of VSM (vibrating sample magnetometer) measurement show magnetic properties can be improved by the increase of annealing time at 700℃.