Powder for magnet

A method for producing a powder for magnet used for a rare earth magnet, the method comprising:

• a preparation step of preparing an alloy powder composed of a rare earth-iron-boron-based alloy;
• and
• a hydrogenation step of heat-treating the alloy powder in an atmosphere containing a hydrogen element at a temperature equal to or higher than the disproportionation temperature of the rare earth-iron-boron-based alloy to produce the powder for a magnet,
• wherein each of magnetic particles which constitute the powder for a magnet is composed of less than 40% by volume of a hydrogen compound of a rare earth element, and the balance composed of an iron-containing material;
• the iron-containing material containing iron and an iron-boron alloy containing iron and boron;
• a phase of the hydrogen compound of a rare earth element and a phase of the iron-containing material are present adjacent to each other;
• and the distance between the phases of the rare earth element hydrogen compound adjacent to each other with the phase of the iron-containing material provided therebetween is 3 μm or less.

A method for producing a rare earth-iron-boron-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-boron-based alloy;
• a hydrogenation step of heat-treating the alloy powder in an atmosphere containing a hydrogen element at a temperature equal to or higher than the disproportionation temperature of the rare earth-iron-boron-based alloy to produce a powder for a magnet which includes magnetic particles each composed of less than 40% by volume of a hydrogen compound of a rare earth element, and the balance composed of an iron-containing material;
• the iron-containing material containing iron and an iron-boron alloy containing iron and boron;
• a phase of the hydrogen compound of a rare earth element and a phase of the iron-containing material being present adjacent to each other;
• and the distance between the phases of the rare earth element hydrogen compound adjacent to each other with the phase of the iron-containing material provided therebetween being 3 μm or less;
• a molding step of compacting the powder for a magnet to form a powder compact having a relative density of 85% or more;
• and
• a desorption step of heat-treating the powder compact in an inert atmosphere or a reduced-pressure atmosphere at a temperature equal to or higher than the recombination temperature of the powder compact to form a rare-earth-iron-boron alloy phase.

A method for producing a rare earth-iron-boron-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-boron-based alloy;
• a hydrogenation step of heat-treating the alloy powder in an atmosphere containing a hydrogen element at a temperature equal to or higher than the disproportionation temperature of the rare earth-iron-boron-based alloy to produce a powder for a magnet which includes magnetic particles each composed of less than 40% by volume of a hydrogen compound of a rare earth element, and the balance composed of an iron-containing material;
• the iron-containing material containing iron and an iron-boron alloy containing iron and boron;
• a phase of the hydrogen compound of a rare earth element and a phase of the iron-containing material being present adjacent to each other;
• and the distance between the phases of the rare earth element hydrogen compound adjacent to each other with the phase of the iron-containing material provided therebetween being 3 μm or less;
• a molding step of compacting the powder for a magnet to form a powder compact having a relative density of 85% or more;
• and
• a desorption step of heat-treating the powder compact in an inert atmosphere or a reduced-pressure atmosphere at a temperature equal to or higher than the recombination temperature of the powder compact to form a mixed phase containing a rare earth-iron-boron alloy phase and at least one phase selected from an iron phase, an iron-boron alloy phase, and a rare earth-iron alloy phase.