It is found that the grain size of the powders milled by balls with different diameters is big, the hard phase is big too and not uniform, the hardness and bending strength are also lower.

结果表明：名义尺寸相同而实际尺寸相差较大的磨球所磨出的粉体粒度大且分布不均匀，烧结体硬质相颗粒粗大且等轴性差，抗弯强度和硬度均较低。

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Another is that the hard phase and the soft phase both have microstructure with crystal grain of fine and homogeneous, and the size of crystal grain had better within magnitude of nanometer.

二是硬磁相和软磁相均要求有晶粒细小且分布均匀的显微结构特别是软磁相晶粒尺寸尽可能达到纳米尺寸。

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