| 简介 |
PROBLEM TO BE SOLVED : To provide a method for producing an inexpensive rare earth-iron-nitrogen based magnet powder having magnetic characteristics, by uniformly nitriding rare earth-transition metal master alloy obtained by a reduction diffusion method.
SOLUTION : Transition metal alloy powder, rare earth oxide powder and a reducing agent for reducing the rare earth oxide are mixed, the mixture is heated and fired in a nonoxidizing atmosphere to obtain a reduction-diffusion reaction product including rare earth-transition metal master alloy, and, by a reduction diffusion method of performing wet type treatment of removing the reducing agent from the reduction-diffusion reaction product and drying the same, rare earth-transition metal master alloy powder is obtained. Steps in which the obtained powder is heated up to 250 to 700°C, is held for 1 to 3.5 hr in a nitrogen gas atmosphere, and is thereafter cooled to ≤100°C are repeated two or more times, and, by the collapse of the powder by the expansion-contraction of the powder, a new face is formed, thus uniform nitriding can be achieved.
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