A grain boundary diffusion method based on 1:2 phase for simultaneously improved corrosion resistance and coercivity of a mixed rare-earth permanent magnetic material is provided. After a Ce-rich mixed rare-earth sintered permanent magnet is prepared using a powder metallurgy process, one of a vapor deposition, an electroplating, a direct physical contact and an adhesive bonding is used to load a grain boundary diffusion alloy source on a surface of the magnet, followed by a grain boundary diffusion heat treatment and a tempering process. The process thereof is simple, and makes full use of the synergistic effect and characteristic diffusion behavior of multiple rare earths in the grain boundary diffusion process to increase the fraction of 1:2 phase in the magnet, and to regulate the composition and distribution of 1:2 phase, thereby simultaneously improving the corrosion resistance and coercivity of the mixed rare-earth permanent magnetic material.

Methods for the production of magnetic powders, compacted magnetic bodies and sintered magnetic bodies. The methods include the use of metal carboxylate precursor compounds such as metal oxalates. The precursor compounds are heated under pressure to form metal alloy particles which can be directly formed into compacted magnetic bodies or can be further refined by using a reductant at elevated temperatures and pressures. The sintered magnetic bodies may have strong magnetic properties even if produced in the absence of a strong magnetic field.

A production method of a Sm—Fe—N-based rare earth magnet, enabling to stably impart sufficient anisotropy, is provided.

The present disclosure provides a production method of a rare earth magnet, including preparing a raw material powder containing a magnetic powder (SmFeN powder 10) having a magnetic phase which contains Sm, Fe and N and at least partially has a crystal structure of at least either Th.sub.2Zn.sub.17 type or Th.sub.2Ni.sub.17 type, and pressure-sintering the raw material powder. In this production method, magnetic orientation is imparted to the raw material powder by applying a magnetic field before the pressure sintering, and the application of magnetic field is continued to maintain the magnetic orientation at least until the middle of the pressure sintering.

A powder metal material for additive manufacturing contains: (A) a non-magnetic steel powder which is free of nitrogen; and (B) a ferromanganese nitride powder, a particle size of the component (B) is 15.0 μm≤D50≤25.0 μm in terms of volume average particle size, and a content of the component (B) is 0.4 mass % to 4.0 mass % with respect to a total amount of the powder metal material.

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.

A sintered magnet and method of manufacturing the same are disclosed herein. According to an exemplary embodiment, a manufacturing method of a sintered magnet includes mixing the neodymium iron boron (NdFeB)-based powders and rare-earth hydride powders to prepare a mixture, heat-treating the mixture at a temperature of 600 to 850° C., and sintering the heat-treated mixture at a temperature of 1000 to 1100° C. to prepare the sintered magnet, wherein the rare earth hydride powders are neodymium hydride (NdH.sub.2) powders or mixed powers of NdH.sub.2 and praseodymium hydride (PrH.sub.2). In an embodiment, the NdFeB-based powders are prepared by a reduction-diffusion method.

The present invention discloses a high-strength R-T-B rare earth permanent magnet and a preparation method thereof. The magnet contains 0.3-1.5 wt. % of an element Zr, and a cast strip prepared through vacuum induction melting and melt spinning is treated at a high temperature to make the element Zr therein precipitate in a form of fibrous Zr compounds from R-rich phases, and the fibrous Zr compounds can be uniformly mixed with magnetic powder after hydrogen decrepitation and powder jet milling and mixing, and gradually grow into rod-like Zr compounds existing in the R-rich intergranular phases during the sintering of a green compact. By adjusting the content of the element Zr, sintering temperature and time and other process parameters, the morphology, size and distribution of Zr compounds can be effectively controlled, and the mechanical properties of the magnet can be improved by strengthening the R-rich intergranular phases without deteriorating the magnetic properties of the magnet.

The present disclosure relates to a method for preparing a category of alloy powder and an application thereof. By selecting a suitable alloy system and melting initial alloy melt through low-purity raw materials, high-purity alloy powder, and matrix phase wrapping high-purity alloy powder are precipitated during the solidification process of the initial alloy melt, and the solid solution alloying of the high-purity alloy powder is achieved at the same time. Alloy powder can be obtained by removing the matrix phase wrapping the high-purity alloy powder; high-purity alloy powder can also be obtained by removing the matrix phase wrapping the high-purity alloy powder at an appropriate time. The method is simple and can prepare a variety of alloy powder materials with different morphology at nano-scale, sub-micron level, micron level, and even millimeter level.

There are provided a method for producing a magnetic refrigeration material whose magnetic transition temperature can be adjusted with high accuracy, and a magnetic refrigeration material whose magnetic transition temperature has been adjusted with high accuracy. The magnetic refrigeration material production method of the present invention includes the steps of: preparing a first predetermined magnetic refrigeration material and a second predetermined magnetic refrigeration material which differs from the first magnetic refrigeration material; and mixing the first magnetic refrigeration material and the second magnetic refrigeration material to obtain a third magnetic refrigeration material. The content of the first magnetic refrigeration material and the content of the second magnetic refrigeration material in the third magnetic refrigeration material are determined by the magnetic transition temperatures of the first magnetic refrigeration material and the second magnetic refrigeration material and by a target magnetic transition temperature of the third magnetic refrigeration material. The magnetic refrigeration material of the present invention includes at least a first predetermined magnetic refrigeration material and a second predetermined magnetic refrigeration material which differs from the first magnetic refrigeration material. The absolute value of the difference between the magnetic transition temperature of the present magnetic refrigeration material and a target magnetic transition temperature is 0.7 K or less.

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.