The powder mixture for powder metallurgy includes a raw material powder, a binder, and a graphite powder, where the raw material powder contains an iron-based powder in a content of 90 mass % or more of the raw material powder, the graphite powder has an average particle size of less than 5 μm, a ratio in mass of the binder to the sum the raw material powder and the graphite powder is 0.10 mass % to 0.80 mass %, a ratio of mass of the graphite powder to the sum of mass of the raw material powder and mass of the graphite powder is 0.6 mass % to 1.0 mass %, surface of the raw material powder is covered with at least a part of the binder, and surface of the binder covering the surface of the raw material powder is covered with at least a part of the graphite powder.

It has been found that duplex monolithic parts can be manufactured in high volume at low cost by using powder metal technology to mold and sinter an inner component of the part into an outer component of the part. This technique reduces the cost of manufacturing intricate metal products by taking advantage of the attributes of powder metal technology in making the inner component of the part. The outer component of the part can be wrought machined, stamped or forged, or made by double press double sinter or forging a powder metal component of the part. In any case, this technique can beneficially be used in making a wide variety of toroid parts, such as gears, clutches, sprags, bearing races, one-way diodes, and the like.

A soft magnetic powder, including an Fe alloy, and containing 0.1 to 15 mass % of Si, wherein a ratio (Si/Fe) of an atomic concentration of Si and an atomic concentration of Fe is from 4.5 to 30 at a depth of 1 nm from a particle surface of the soft magnetic powder.

A soft magnetic powder, including an Fe alloy, and containing 0.1 to 15 mass % of Si, wherein a ratio (Si/Fe) of an atomic concentration of Si and an atomic concentration of Fe is from 4.5 to 30 at a depth of 1 nm from a particle surface of the soft magnetic powder.

Provided is an iron-based powder for dust core with which a dust core with low iron loss and high insulation properties can be obtained. In the iron-based powder for dust core of the present disclosure, a median particle size calculated based on cumulative volume frequency of particles of the iron-based powder for dust core is 150 μm or less, and cumulative volume frequency of the particles with an aspect ratio of 0.70 or less is 70% or less, and a median aspect ratio calculated based on cumulative volume frequency is 0.60 or more.

A method of manufacturing a sintered gear includes preparing a green compact having two gear-shaped end surfaces, one on each of two sides in an axial direction of the green compact, and having a plurality of teeth on an outer peripheral surface formed between the two end surfaces; chamfering an edge of the teeth by a brush; and sintering the green compact. The brush is a wheel-type brush including a disk-shaped wheel and a bristle member radially protruding from an outer periphery of the wheel. The chamfering includes disposing the brush with respect to the green compact such that the axial direction of the green compact and an axial direction of the wheel intersect with each other; bringing a tip of the bristle member into contact with a tooth bottom edge; and relatively moving the brush in a circumferential direction of the green compact while rotating the brush.

Included is a method of preparing a compound for bonded magnets, the method including: coating a magnetic material having an average particle size of 10 μm or less with a thermosetting resin and a curing agent at a ratio of the equivalent weight of the curing agent to the equivalent weight of the thermosetting resin of 2 or higher and 10 or lower to obtain a coated material; granulating the coated material by compression to obtain a granulated product; milling the granulated product to obtain a milled product; and surface treating the milled product with a silane coupling agent to obtain a compound for bonded magnets, the method either including, between the granulation and the milling, heat curing the granulated product to obtain a cured product, or including, between the milling and the surface treatment, heat curing the milled product to obtain a cured product.

Included is a method of preparing a compound for bonded magnets, the method including: coating a magnetic material having an average particle size of 10 μm or less with a thermosetting resin and a curing agent at a ratio of the equivalent weight of the curing agent to the equivalent weight of the thermosetting resin of 2 or higher and 10 or lower to obtain a coated material; granulating the coated material by compression to obtain a granulated product; milling the granulated product to obtain a milled product; and surface treating the milled product with a silane coupling agent to obtain a compound for bonded magnets, the method either including, between the granulation and the milling, heat curing the granulated product to obtain a cured product, or including, between the milling and the surface treatment, heat curing the milled product to obtain a cured product.

A method for manufacturing magnetic alloy powder constituted by magnetic grains whose alloy phase is coated with an oxide film, includes: providing a material powder for magnetic alloy whose Fe content is 96.5 to 99 percent by mass and which also contains Si and at least one of non-Si elements (element M) that oxidize more easily than Fe; and heat-treating the material powder and thus forming an oxide film on a surface of each grain constituting the material powder, to obtain a magnetic alloy powder, wherein a content of Fe in the alloy phase is higher than in the material powder; and at a location in the oxide film where its content of Si is in element distributions in a film thickness direction is highest, the content of Si is higher than a content of Fe, and also higher than its content of element M, at the location.

Provided is alloyed steel powder having excellent fluidity, formability, and compressibility without containing Ni, Cr, or Si. The alloyed steel powder includes iron-based alloy containing Mo, in which Mo content is 0.4 mass % to 1.8 mass %, a weight-based median size D50 is 40 μm or more, and among particles contained in the alloyed steel powder, those particles having an equivalent circular diameter of 50 μm to 200 μm have a number average of solidity of 0.70 to 0.86, the solidity being defined as (particle cross-sectional area/envelope-inside area).