纳米复合永磁材料的有效各向异性与矫顽力

Effective anisotropy and coercivity in nanocomposite permanent materials

研究了纳米Nd2 Fe1 4B α Fe复合永磁材料中晶粒交换耦合相互作用对有效各向异性的影响和变化规律 .结果表明 :晶粒之间的交换耦合作用使材料的有效各向异性Keff随晶粒尺寸的减小而下降、随软磁性相成分的增加而降低 .当晶粒尺寸减小到 4nm时 ,Keff值减小为其各自通常各向异性常数值的 1 3— 1 4 .有效各向异性的变化特点与矫顽力的变化规律基本相同 .

The effects of exchange-coupling inter-actions between grains on the effective anisotropy and the variation in Nd2Fe14B/alpha-Fe nanocomposite permanent materials were investigated. The calculatied results showed that due to the exchange-coupling interactions, the effective anisotropy K(eff)of the nanocomposite decreases with the decrease of grain size and the increase of magnetically soft phase component. When the average grain size decreases to 4nm, K-eff decreases to about 1/3-1/4 of the value of the ordinary anisotropy constant. This variation character is basically similar to that of the coercivity. The decrease of coercivity for the nanocomposite permanent materials is mainly due to the decrease of the effective anisotropy.