Effect of Nb addition on the crystallization behavior and magnetic properties of melt-spun Fe-rich Fe-Nd-B ribbons

摘要

We compared the crystallization behavior and subsequent magnetic properties of alpha-Fe/Nd2Fe14B-based exchange-spring magnets with and without Nb addition, using differential thermal analysis, X-ray diffraction, transmission electron microscopy, and vibrating sample magnetometer, In the optimally annealed Nd4Fe90Nb2B4 alloy, uniformly distributed alpha-Fe grains 50-80 nm in diameter are surrounded by Nd2Fe14B1 grains 10-20 nm in diameter as well as by amorphous intergranular layer regions enriched with Nb. The remanence, the coercivity, and the energy product are 1.35 T, 210 kA m(-1) (2.65 kOe) and 103 kJ m(2), respectively, In the annealed alloy without Nb, the alpha-Fe and Nd2Fe14B1 phases are brought about from two different intermediate states, resulting in a heterogeneous distribution. (C) 1998 Elsevier Science S.A. [References: 17]