ORIGIN OF MAGNETIC-ANISOTROPY FORMATION IN THE HDDR-PROCESS OF ND2FE14B-BASED ALLOYS

To clarify the mechanism inducing magnetic anisotropy in the hydrogena tion, disproportionation, desorption and recombination process of NdFe B-based alloys, the disproportionation of Nd13.0Fe67.9Co11.0Ga1.0Zr0.1 B7.0 and its relation to the magnetic properties have been investigate d. The disproportionated microstructure under optimum hydriding condit ions for energy product mainly consists of the coarse-grained alpha-Fe and Fe2B involving two kinds of particle. One is NdH2 particles, and the other has been identified as ''crystallographically aligned'' Nd2F e14B particles. The size of the Nd2Fe14B particles is less than 50 nm. The crystallographic orientation of the nano-scale Nd2Fe14B particles is almost the same as that of the original Nd2Fe14B. It is therefore most likely that this nano-scale Nd2Fe14B acts as a recombination cent er during the desorption leading to the magnetic anisotropy formation.