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.

The present invention provides a low cost pre-alloyed iron based powder which has high compressibility, capable of rendering a compacted and sintered component high green density, (GD), and high sintered density, (SD). Also, a method or process for producing components, especially gears, including compaction of powder mixture containing the pre-alloyed iron-based powder, sintering of the compacted component, Low Pressure carburizing, (LPC), High Pressure Gas Quenching, (HPGQ), and tempering, is provided. In one embodiment, the process includes high temperature sintering. Other aspects of the present invention include a powder mixture containing the pre-alloyed iron based powder and components produced by the new process from the powder mixture. Such carburized components exhibit a hard surface combined with a softer and tougher core, necessary properties for e.g. automotive gears subjected to harsh environment.

The present invention discloses a short process preparation technology of sintered NdFeB magnets from the NdFeB sludge, which relates to a field of recycle technology of NdFeB sludge. The present invention comprises the following steps: water bath distillation of organics in sludge, ultrasonic cleaning, calcium reduction and diffusion, ultrasonic rinsing in a magnetic field and drying, powders mixing and sintering. NdFeB sludge as raw materials was directly prepared from recycled sintered magnets with high magnetic properties. Most of the organics in the sludge could be removed by a vacuum distillation process with stepwise heating. The ultrasonic rinsing process in a magnetic field could effectively remove the remaining organics. The recycled sintered magnets exhibited good maximum energy product [(BH).sub.max] of 35.26 MGOe. The present invention has important features, such as the short processing time, efficient environmental protection, high recycling rate and effective utilization rate of rare earth metals.

A sintered pulley may include a body of a metal alloy and configured with a substantially annular shape. The body may include a first face of contact with a crankshaft, a second face of contact with a securing element, and a concentric hole for associating the pulley with the crankshaft. The second face of contact may have a region of a point of contact with the securing element disposed proximate to the hole. The region of the point of contact may have a density of between 7.3 and 7.5 g/cm.sup.3.

An Fe—Mo—Cu—C-based alloy steel powder for powder metallurgy has a chemical composition containing Mo: 0.2 mass % to 1.5 mass %, Cu: 0.5 mass % to 4.0 mass %, and C: 0.1 mass % to 1.0 mass %, with a balance being Fe and incidental impurities, wherein an iron-based powder has a mean particle size of 30 μm to 120 μm, and a Cu powder has a mean particle size of 25 μm or less. Despite the alloy steel powder for powder metallurgy having a chemical composition not containing Ni, a part produced by sintering a press formed part of the powder and further carburizing-quenching-tempering the sintered part has mechanical properties of at least as high tensile strength, toughness, and sintered density as a Ni-added part.

A method for manufacturing a sintered gear comprising the steps of: preparing a cylindrical green compact; gear-cutting the green compact with a hob; and sintering the gear-hobbed green compact, wherein the hob is such that a ratio of a number of cutting edges thereof per round to a number of starts thereof exceeds 8.

A sintered magnet and a method for producing the same are provided. The method includes producing an R—Fe—B-based magnet powder by a reduction-diffusion method, adding a R—Al—Cu powder as a sintering agent to the R—Fe—B-based magnet powder to form a mixed powder, wherein the R—Al—Cu powder is an alloy of R, Al and Cu, and R is Nd, Pr, Dy, Tb or Ce, and sintering the mixed powder to form a sintered magnet.

A sintered magnet and a method for producing the same are provided. The method includes producing an R—Fe—B-based magnet powder by a reduction-diffusion method, adding a R—Al—Cu powder as a sintering agent to the R—Fe—B-based magnet powder to form a mixed powder, wherein the R—Al—Cu powder is an alloy of R, Al and Cu, and R is Nd, Pr, Dy, Tb or Ce, and sintering the mixed powder to form a sintered magnet.

A composite cemented carbide roll comprising an inner layer made of an iron-based alloy, and an outer layer made of cemented carbide which is metallurgically bonded to an outer peripheral surface of the inner layer; the cemented carbide of the outer layer comprising 55-90 parts by mass of WC particles and 10-45 parts by mass of an Fe-based binder phase having a particular composition; a shaft member and a shaft end member being metallurgically bonded to at least one axial end of the inner layer; the inner layer being made of an iron-based alloy containing 2.0% or more in total by mass of at least one selected from the group consisting of Cr, Ni and Mo; and the shaft member and the shaft end member being made of an iron-based alloy containing 1.5% or less in total by mass of at least one selected from the group consisting of Cr, Ni and Mo.

In an exemplary embodiment, a magnetic alloy powder is constituted by magnetic grains 100 whose alloy phase 1 is coated with an oxide film 2, wherein: the alloy phase 1 has a Fe content of 98 percent by mass or higher and also contains Si and at least one type of non-Si element that oxidizes more easily than Fe (element M); and the oxide film 2 is such that, at the location where the content of Si as expressed in percentage by mass is the highest according to the element distributions in the direction of film thickness, this content of Si is higher than the content of Fe, and also higher than the content of element M, at this location. The magnetic alloy powder has a high Fe content and also offers excellent insulating property.