A method for manufacturing a powder magnetic core, including a step of compacting a raw material powder to form a compact, a step of performing a first heat treatment on the compact to obtain a first heat-treated body, and a step of performing a second heat treatment on the first heat-treated body to obtain a second heat-treated body, wherein the raw material powder contains a soft magnetic powder and a lubricant that has a melting point Tm, the first heat treatment is performed in a temperature range from Tm to Tm+50° C. inclusive for a time longer than 10 minutes, and the second heat treatment is performed in a temperature range from 400° C. to 900° C. inclusive for a time of 3 minutes to 90 minutes inclusive, the temperature range of the second heat treatment being higher than the temperature range of the first heat treatment.

A method for manufacturing a sintered component includes a step of making a green compact having a relative density of at least 88% by compression-molding a base powder containing a metal powder into a metallic die, a step of machining a groove part having a groove width of 1.0 mm or less in the green compact by processing groove with a cutting tool, and a step of sintering the green compact in which the groove part is formed after the step of forming the groove part.

A method for manufacturing a sintered component includes a step of making a green compact having a relative density of at least 88% by compression-molding a base powder containing a metal powder into a metallic die, a step of machining a groove part having a groove width of 1.0 mm or less in the green compact by processing groove with a cutting tool, and a step of sintering the green compact in which the groove part is formed after the step of forming the groove part.

Provided is a raw material powder for powder metallurgy, capable of preventing stains, surface defects and decarburization of a sintered body, improving strength and density thereof. The raw material powder for powder metallurgy is for use in the production of a sintered body that is sintered at a temperature of not lower than 500° C., composed of a mixture of a metal powder and a lubricant, in which the lubricant is melamine cyanurate or terephthalic acid. Alternatively, the raw material powder for powder metallurgy is for use in the production of a sintered body that is sintered at a temperature of not lower than 500° C, composed of a mixture of a metal powder, a first lubricant and a second lubricant, in which the first lubricant is melamine cyanurate or terephthalic acid, while the second lubricant is preferably erucic acid amide or stearic acid amide.

Provided is a raw material powder for powder metallurgy, capable of preventing stains, surface defects and decarburization of a sintered body, improving strength and density thereof. The raw material powder for powder metallurgy is for use in the production of a sintered body that is sintered at a temperature of not lower than 500° C., composed of a mixture of a metal powder and a lubricant, in which the lubricant is melamine cyanurate or terephthalic acid. Alternatively, the raw material powder for powder metallurgy is for use in the production of a sintered body that is sintered at a temperature of not lower than 500° C, composed of a mixture of a metal powder, a first lubricant and a second lubricant, in which the first lubricant is melamine cyanurate or terephthalic acid, while the second lubricant is preferably erucic acid amide or stearic acid amide.

According to a method for pressing a green compact from a sintering powder for producing a gear having a first track and a second track, wherein a first helical toothing with a first helix angle and a first diameter is produced as the first track and a second helical toothing with a second helix angle and a second diameter is produced as the second track, the sintering powder is filled into a mold cavity of a die, and then the sintering powder is pressed to form the green compact with an upper stamp and a lower stamp, and wherein the first and the second helical toothings are produced having the same pitch height.

A magnetic core has a structure in which Fe-based soft magnetic alloy particles are connected via a grain boundary. The Fe-based soft magnetic alloy particles contain Al, Cr and Si. An oxide layer containing at least Fe, Al, Cr and Si is formed at the grain boundary that connects the neighboring Fe-based soft magnetic alloy particles. The oxide layer contains an amount of Al larger than that in Fe-based soft magnetic alloy particles, and includes a first region in which the ratio of Al is higher than the ratio of each of Fe, Cr and Si to the sum of Fe, Cr, Al and Si, and a second region in which the ratio of Fe is higher than the ratio of each of Al, Cr and Si to the sum of Fe, Cr, Al and Si. The first region is on the Fe-based soft magnetic alloy particle side.

A magnetic core has a structure in which Fe-based soft magnetic alloy particles are connected via a grain boundary. The Fe-based soft magnetic alloy particles contain Al, Cr and Si. An oxide layer containing at least Fe, Al, Cr and Si is formed at the grain boundary that connects the neighboring Fe-based soft magnetic alloy particles. The oxide layer contains an amount of Al larger than that in Fe-based soft magnetic alloy particles, and includes a first region in which the ratio of Al is higher than the ratio of each of Fe, Cr and Si to the sum of Fe, Cr, Al and Si, and a second region in which the ratio of Fe is higher than the ratio of each of Al, Cr and Si to the sum of Fe, Cr, Al and Si. The first region is on the Fe-based soft magnetic alloy particle side.

One aspect of the present invention is a lubricant to be incorporated into a powder metallurgical mixed powder containing an iron-based powder. The lubricant includes a flaky organic material having an average particle diameter of from 0.1 μm to less than 3 μm. Another aspect of the present invention is a powder metallurgical mixed powder which contains an iron-based powder and the lubricant. Yet another aspect of the present invention is a method for producing a sintered compact. The method includes the step of mixing materials to give a powder metallurgical mixed powder containing an iron-based powder and the lubricant. The powder metallurgical mixed powder is compacted using a die to give a powder compact. The powder compact is sintered to give a sintered compact.

One aspect of the present invention is a lubricant to be incorporated into a powder metallurgical mixed powder containing an iron-based powder. The lubricant includes a flaky organic material having an average particle diameter of from 0.1 μm to less than 3 μm. Another aspect of the present invention is a powder metallurgical mixed powder which contains an iron-based powder and the lubricant. Yet another aspect of the present invention is a method for producing a sintered compact. The method includes the step of mixing materials to give a powder metallurgical mixed powder containing an iron-based powder and the lubricant. The powder metallurgical mixed powder is compacted using a die to give a powder compact. The powder compact is sintered to give a sintered compact.