放电等离子烧结纳米晶NdFeB合金的组织特征和磁性能

Microstructure and magnetic properties of spark plasma sintered nanocrystalline NdFeB alloys

通过对快淬NdFeB粉末进行放电等离子烧结(SPS),制备出各向同性NdFeB永磁材料,研究了烧结工艺对磁体组织形貌和性能的影响。结果表明,SPS烧结产生的颗粒放电导致粉末边界区域晶粒长大,形成了边界粗晶区,而粉末内部仍保持了快淬粉末的细晶结构。烧结温度和压力对晶粒尺寸有较大的影响,从而影响烧结磁体的磁性能。较低的烧结温度和高的烧结压力既可以获得高致密磁体,也可以有效减小粗晶区的尺寸,从而提高材料综合磁性能。

Isotropic NdFeB magnets were synthesized by spark plasma sintering（SPS） using melt spun powders as start materials.The effects of SPS process on the microstructure and magnetic properties were investigated.The grain growth was found at the initial particles surface due to the high temperature during SPS and the coarse grain zones formed at the vicinity of particle boundaries,but the fine grain structure still exists in the interior of the particles.The SPS temperature and pressure have important effect on the sizes of both coarse grain zone and fine grain zone,and thus leads to the changes in magnetic properties.By employing lower SPS temperature and higher pressure,high density magnets with small size of coarse grain zone can be obtained,resultantly higher comprehensive magnetic properties can be achieved.