The hot-deformed magnets processed from nanocrystalline/amorphous Nd–Fe–B powders were prepared under different hot-pressing temperatures (600–750 °C, at intervals of 25 °C) by the self-made hot-pressing equipment. The microstructure and magnetic properties of hot-deformed magnets prepared at different temperatures were also investigated. When the temperature is above 650 °C, the density of magnet reaches 7.5 g·cm−3. The optimum magnetic properties of magnetic induction intensity of Br = 1.3 T, optimum energy product of (BH)max = 282.5 kJ·m−3, intrinsic coercivity of Hcj = 1130.0 kA·m−1 of hot-deformed magnets are obtained at hot-pressing temperature of 650 °C. X-ray diffractometer pattern shows that the (00L) texture has been obtained. For the microstructural characteristic, on the one hand, the good magnetic performance is attributed to the fine platelet-like grains with an average length of 410–440 nm at the hot-pressing temperature range from 625 to 675 °C. On the other hand, the unaligned coarse grains are observed in all the samples. And the areal fraction of those is gradually increasing with the rise of the hot-pressing temperature, which tends to deteriorate the magnetic properties. The composition map shows the accumulation of Nd/Pr-rich phase in the coarse grains’ region.

中文翻译：

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纳米晶/非晶Nd-Fe-B粉末热变形磁体的制备及性能

采用自制热压设备在不同热压温度（600-750℃，间隔25℃）下制备纳米晶/非晶Nd-Fe-B粉末热变形磁体。还研究了在不同温度下制备的热变形磁体的微观结构和磁性能。当温度高于 650 °C 时，磁铁的密度达到 7.5 g·cm-3。热变形磁体的最佳磁性能为Br = 1.3 T，(BH)max的最佳能积= 282.5 kJ·m-3，Hcj的本征矫顽力= 1130.0 kA·m-1 - 压制温度为 650 °C。X 射线衍射仪图案显示已获得 (00L) 纹理。对于微观结构特征，一方面，良好的磁性能归因于在 625 至 675 °C 的热压温度范围内平均长度为 410-440 nm 的细小片状晶粒。另一方面，在所有样品中都观察到未排列的粗晶粒。并且随着热压温度的升高，它们的面积分数逐渐增加，这趋于降低磁性能。成分图显示了在粗晶粒区域中富 Nd/Pr 相的积累。