放电等离子烧结NdFeB的晶界结构与矫顽力

Grain Boundary Microstructure and Coercivity of NdFeB Magnet Prepared by Spark Plasma Sintering (SPS)

摘要:

选取Nd11Dy2Gd2FebalAl4.0Nb0.8Zr0.8B6/Dy2O3磁粉采用放电等离子烧结技术制备各向异性磁体。微观组织和磁性能研究表明，烧结温度对磁体中晶界相的分布形态起决定作用。样品经870 ℃，12 min (40 MPa)放电等离子烧结及后续970 ℃, 2 h + 600 ℃, 1 h二级回火后，致密度达到7.39 g/cm3，剩磁达到1.08 T，矫顽力达到1181 kA·m-1。与同成分的传统烧结磁体相比较，放电等离子烧结磁体中晶界相分布不连续、晶界相中的稀土元素相对含量因烧损而显著下降以及晶界结构存在一定程度的不平衡等问题，都导致磁体的矫顽力较低。

Abstract:

Anisotropic magnets were synthesized by spark plasma sintering Nd11Dy2Gd2FebalAl4.0Nb0.8Zr0.8B6/Dy2O3 powder. The analyses of microstructure and magnetic property indicate that the sintering temperature determines the distribution of grain boundary phase in the magnets. After spark plasma sintering of 870 oC, 12 min (40 MPa) followed by tempering of 970 oC, 2 h + 600 oC, 1 h, the average density of samples reaches 7.39 g/cm3, residual magnetization is 1.08 T, and intrinsic coercive force is 1181 kA·m-1. The coercivity of the SPSed magnet is smaller than that of traditional sintered magnet with the same compositions, which is attributed to the discontinuous distribution of grain boundary phases, obvious decrease of rare earth relative contents in grain boundary phase because of their loss during the process, and some non-equilibrium structures in them.