应变速率对热变形NdFeB磁体微观结构和性能的影响

Influences of Stain Rate on the Microstructure and Properties for Hot Deformed NdFeB Magnets

以放电等离子烧结(SPS)磁体为前驱烧结磁体,通过热变形制备了纳米晶各向异性磁体。研究了变形速率对磁体微观结构和性能的影响。研究发现,对于不同的应变速率,SPS磁体中不同区域的微观结构显示了不同的热变形行为。较大的晶粒尺寸不利于通过热变形制备各向异性Nd Fe B磁体。在不添加重稀土元素和较低稀土含量的情况下,制备出具有良好磁性能(Jr=1.35 T、jHc=829 k A/m和(BH)max=336 k J/m3)和较低矫顽力温度系数(β=–0.682%K-1)的纳米晶热变形磁体。

Anisotropic nanocrystalline NdFeB magnets were prepared by hot deformation using the Spark Plasma Sintered （SPSed） magnets as precursors. The influences of strain rate on the microstructure and properties were investigated. The two-zone microstructure within the SPSed magnets shows different hot deformation behavior for various stain rates. The results indicate that the microstructure with large grain size is not beneficial in obtaining anisotropic magnets by plastic deformation. With no addition of heavy rare earth elements and low rare earth content, the optimal magnetic properties are obtained with Jr=1.35 T、jHc=829 k A/m, （Bn）max = 336 kJ/m3 and the low temperature coefficient of coercivity with β=-0.682%K-1.