以Nd2Fe14B为例, 研究了单相纳米晶硬磁材料中有效各向异性和矫顽力随晶粒尺寸及其分布的变化关系。计算结果表明：材料的有效各向异性和矫顽力随晶粒尺寸减小而降低, 当平均晶粒尺寸小于20 nm时, 其减小更为迅速；晶粒尺寸的非理想分布没有改变有效各向异性和矫顽力随晶粒尺寸的总体变化规律, 但使材料有效各向异性和矫顽力进一步下降. 当微结构因子pc取值为0.7时, 计算结果与Manaf等人关于矫顽力的实验结果非常接近。纳米晶硬磁材料的矫顽力随晶粒尺寸下降主要是有效各向异性常数或各向异性场的减小引起的。
Taking nanocrystalline Nd2Fe14B as a typical sample, the effects of grain-size distribution on the anisotropy and coercivity in nanocrystalline hard magnetic materials have been investigated. The calculating results reveal that the effective anisotropy and coercivity of material decrease with the reduction of grain size, and rapidly decrease while the grain size is less than 20nm. The non-ideal distribution of grain size does not change the variation trendency of the effective anisotropy and coercivity with reducing grain size, however, promotes the decrease rate of effective anisotropy and coercivity. When the microstructure factor, pc, is 0.7, our calculated results agree basically with the experimental results. The decrement of coercivity is mainly due to the reduction of effective anisotropy for nanocrystalline Nd2Fe14B permanent magnetic material. nanocrystalline Nd2Fe14B hard magnet; effective anisotropy ; coercivity ; grain-size distribution
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