| 摘要 |
A production method to produce an anisotropic NdFeB based alloy magnet having a high anisotropic ratio and coercivity by a simple procedure. The production method consists of a first hydrogenation process, a second hydrogenation process and a desorption process. The first hydrogenation process at a low temperature produces the hydride that stores hydrogen needed in advance of the phase transformation. After that, the second hydrogenation process at an elevated temperature proceeds smoothly at a moderate reaction rate of the phase transformation and produces the mixture of NdH2, Fe and Fe2 B from the hydride in addition to making the crystallographic orientation of Fe2 B phase consistent with the original R2 Fe14 B matrix phase. Subsequently, the desorption process produces the fine grained microstructure of Nd2 Fe14 BHx with high degrees of alignment of the crystallographic orientation consistent with the original crystallographic orientation of Fe2 B phase. Fine and uniform grained microstructure of RFeB based alloy is produced by recombination of the mixture during the hydrogen heat treatment and consequently offers the anisotropic rare earth magnet powder to have a high anisotropic ratio and high coercivity.
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