Method for producing powder for magnet

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

• a preparation step of preparing an alloy powder composed of a rare-earth-iron-based alloy that contains a rare-earth element serving as an additional element;
• a hydrogenation step of heat-treating the rare-earth-iron-based alloy powder in a hydrogen element-containing atmosphere at a temperature equal to or higher than the disproportionation temperature of the rare-earth-iron-based alloy to form a powder for a magnet, wherein the powder is constituted by magnetic particles, each of the magnetic particles contains a hydride of a rare-earth element in an amount of less than 40% by volume and the balance being an iron-containing material that contains Fe, wherein a phase of the hydride of the rare-earth element is adjacent to a phase of the iron-containing material, and an interval between adjacent phases of the hydride of the rare-earth element with the phase of the iron-containing material provided therebetween is 3 μm or less;
• a compacting step of compacting the powder for the magnet to provide a powder compact having a relative density of 85% or more;
• and
• a dehydrogenation step of heat-treating the powder compact in an inert atmosphere or a reduced atmosphere at a temperature equal to or higher than the recombination temperature of the powder compact to form the rare-earth-iron-based alloy material.

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

• a preparation step of preparing an alloy powder composed of a rare-earth-iron-based alloy that contains a rare-earth element serving as an additional element;
• a hydrogenation step of heat-treating the rare-earth-iron-based alloy powder in a hydrogen element-containing atmosphere at a temperature equal to or higher than the disproportionation temperature of the rare-earth-iron-based alloy to form a powder for a magnet, wherein the powder is constituted by magnetic particles, each of the magnetic particles contains a hydride of a rare-earth element in an amount of less than 40% by volume and the balance being an iron-containing material that contains Fe, wherein a phase of the hydride of the rare-earth element is adjacent to a phase of the iron-containing material, and an interval between adjacent phases of the hydride of the rare-earth element with the phase of the iron-containing material provided therebetween is 3 μm or less;
• a compacting step of compacting the powder for the magnet to provide a powder compact having a relative density of 85% or more;
• and
• a dehydrogenation step of heat-treating the powder compact in an inert atmosphere or a reduced atmosphere at a temperature equal to or higher than the recombination temperature of the powder compact to form the rare-earth-iron-based alloy material,
• wherein the rare-earth-iron-based-alloy is a Sm—Fe—Ti alloy.