| 简介 |
PROBLEM TO BE SOLVED : To provide a method for producing a rare earth-transition metal-nitrogen based magnetic powder by a reduction diffusion process where a rare earth composition can be relatively easily and securely made close to a stoichiometric composition, and to provide a rare earth-transition metal-nitrogen based magnetic powder whose saturated magnetization is improved without deteriorating its coercive force and squareness.
SOLUTION : The method for producing rare earth-transition metal-nitrogen based magnetic powder comprises : a first stage where a rare earth-transition metal based master alloy in which the amount of a rare earth element(s) present in the master alloy is a surplus by a specified amount or above than the stoichiometric composition of a rare earth element(s) present in the main phase thereof is produced from a raw material mixture comprising a surplus rare earth oxide powder, transition metal powder and a reducing agent by utilizing a reduction diffusion process, and the master alloy is thereafter nitrided in a nitrogen-containing atmosphere under heating, so as to obtain a rare earth-transition metal-nitrogen based magnetic powder; and a second stage where the obtained magnetic powder is cleaned with an acidic aqueous solution in such a manner that the rare earth element(s) present in the magnetic powder is removed till the surplus amount of the same reaches a specified amount or below to the stoichiometric composition of the rare earth element(s) present in the main phase, and thereafter, drying is performed.
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