Rare earth-iron-nitrogen-based alloy material, method for producing rare earth-iron-nitrogen-based alloy material, rare earth-iron-based alloy material, and method for producing rare earth-iron-based alloy material

A method for producing a rare earth-iron-based alloy material used for a raw material of a rare earth magnet, the method comprising:

• a preparation step of heat-treating a rare earth-iron-based alloy powder containing a rare earth element in an atmosphere containing a hydrogen element at a temperature equal to or higher than a disproportionation temperature of the rare earth-iron-based alloy to prepare a multi-phase powder composed of a multi-phase particle in which a phase of a hydrogen compound of the rare earth element is dispersedly present in a phase of an iron-containing material containing Fe, and the content of the phase of the hydrogen compound of the rare earth element is 40% by volume or less;
• a molding step of forming a powder compact by compression-molding the multi-phase powder;
• and
• a dehydrogenation step of heat-treating the powder compact in an inert atmosphere or a reduced-pressure atmosphere at a temperature equal to or higher than a recombination temperature of the powder compact to form a rare earth-iron-based alloy material,
• wherein the heat treatment in the dehydrogenation step is performed by applying a magnetic field of 3 T or more to the powder compact.

A method for producing a rare earth-iron-nitrogen-based alloy material used for a raw material of a rare earth magnet, the method comprising:

• a preparation step of heat-treating a rare earth-iron-based alloy powder containing a rare earth element in an atmosphere containing a hydrogen element at a temperature equal to or higher than a disproportionation temperature of the rare earth-iron-based alloy to prepare a multi-phase powder composed of a multi-phase particle in which a phase of a hydrogen compound of the rare earth element is dispersedly present in a phase of an iron-containing material containing Fe, and the content of the phase of the hydrogen compound of the rare earth element is 40% by volume or less;
• a molding step of forming a powder compact by compression-molding the multi-phase powder;
• a dehydrogenation step of heat-treating the powder compact in an inert atmosphere or a reduced-pressure atmosphere at a temperature equal to or higher than a recombination temperature of the powder compact to form a rare earth-iron-based alloy material;
• and
• a nitriding step of heat-treating the rare earth-iron-based alloy material in an atmosphere containing a nitrogen element at a temperature equal to or higher than a nitriding temperature and equal to or lower than a nitrogen disproportionation temperature of the rare earth-iron-based alloy material to form a rare earth-iron-nitrogen-based alloy material,
• wherein the heat treatment in the dehydrogenation step is performed by applying a magnetic field of 3 T or more to the powder compact;
• and
• the heat treatment in the nitriding step is performed by applying a magnetic field of 3.5 T or more to the rare earth-iron-based alloy material.