Aichi Steel Corporation

Aichi Steel Works, Ltd.

Chisato Mishima

Yoshinobu Honkura

Norihiko Hamada

Hironari Mitarai

Masao Yamazaki

Hiroshi Matsuoka

Kouji Murata

Yoshinobu Sugiura

Takenobu Yoshimatsu

Tooru Matsuo

Yasuji Fukui

Yoshikazu Amahiro

Mitsuyuki Maeda

Anisotropic rare earth magnet powder particles include RTMB-type crystals of a tetragonal compound consisting of one or more rare earth element, B, and one or more transition element, and enveloping layers containing at least Nd and Cu. Surfaces of the RTMB-type crystals are enveloped by the enveloping layers. The particles has an average crystal grain diameter of 0.05 to 1 &#x3bc;m. The particles contain, when the whole particles are taken as 100 atomic %, 11.5 to 15 atomic % of total rare earth element (Rt); 5.5 to 8 atomic % of B; and about 0.05 atomic % to about 2 atomic % of Cu. The powder particles have an atomic ratio of Cu, which is a ratio of the total number of Cu atoms to a total number of atoms of Rt, falling within the range of 1 to 6%. The powder particles do not include dysprosium Dy, Tb, Ho and Ga. Coercivity of the magnetic powder is more than 955 kA/m.

Anisotropic rare earth magnet powder, method for producing the same, and bonded magnet

The anisotropic rare earth magnet powder of the present invention includes powder particles having RTMB-type crystals of a tetragonal compound of a rare earth element (R), boron (B), and a transition element (TM) having an average crystal grain diameter of 0.05 to 1 &#x3bc;m, and enveloping layers containing at least a rare earth element (R') and copper (Cu) and enveloping surfaces of the crystals. Owing to the presence of the enveloping layers, coercivity of the anisotropic rare earth magnet powder can be remarkably enhanced without using a scarce element such as Ga and Dy.

A method for manufacturing an anisotropic magnet powder includes a high-temperature hydrogenation process of holding an RFeB-based alloy containing rare earth elements (R), B and Fe as main ingredients in a treating atmosphere under a first treating pressure (P) of which a hydrogen partial pressure ranges from 10 to 100 kPa and at a first treating temperature (T) which ranges from 953 to 1133 K, a structure stabilization process of holding the RFeB-based alloy after the high-temperature hydrogenation process under a second treating pressure (P) of which a hydrogen partial pressure is 10 or more and at a second treating temperature (T) which ranges from 1033 to 1213 K such that the condition T&#x3e;Tor P&#x3e;Pis satisfied, a controlled evacuation process of holding the RFeB-based alloy after the structure stabilization process in a treating atmosphere under a third treating pressure (P) of which a hydrogen partial pressure ranges from 0.1 to 10 kPa and at a third treating temperature (T) which ranges from 1033 to 1213 K, and a forced evacuation process of removing residual hydrogen (H) from the RFeB-based alloy after the controlled evacuation process. With this method, the magnetic properties of the anisotropic magnet powder can be improved.

Process for producing anisotropic magnet powder

An alloy for bonded magnets of the present invention includes at least a main component of iron (Fe), 12-16 atomic % (at %) of rare-earth elements (R) including yttrium (Y), and 10.8-15 at % of boron (B), and is subjected to a hydrogen treatment method as HDDR process or d-HDDR process. Using the magnet powder obtained from carrying out d-HDDR processing, etc. on this magnet alloy, pellets with superior insertion characteristics into bonded magnet molding dies can be obtained, and bonded magnets with superior magnetic properties and showing low cost can be obtained.

Alloy for bonded magnets, isotropic magnet powder and anisotropic magnet powder and their production method, and bonded magnet

This invention aims to provide a manufacturing method of an anisotropic magnet powder from which a bonded magnet with an improved loss of magnetization due to structural changes can be achieved. This is achieved by employing a low-temperature hydrogenation process, high-temperature hydrogenation process and the first evacuation process to an RFeB material (R: rare earth element) to manufacture a hydride powder (RFeBHx); the obtained RFeBHx powder (the precursory anisotropic magnet powder) is subsequently blended with a diffusion powder composed of hydride of dysprosium or the like and a diffusion heat-treatment process and a dehydrogenation process are employed. Through this series of processes, an anisotropic magnet powder with a great coercivity and a great degree of anisotropy can be achieved.

Manufacturing method of an anisotropic magnet powder, precursory anisotropic magnet powder and bonded magnet

A production method to produce an anisotropic NdFeB based alloy magnet having a high anisotropic ratio and coercivity by a simple procedure. The production method consists of a first hydrogenation process, a second hydrogenation process and a desorption process. The first hydrogenation process at a low temperature produces the hydride that stores hydrogen needed in advance of the phase transformation. After that, the second hydrogenation process at an elevated temperature proceeds smoothly at a moderate reaction rate of the phase transformation and produces the mixture of NdH , Fe and Fe B from the hydride in addition to making the crystallographic orientation of Fe B phase consistent with the original R Fe B matrix phase. Subsequently, the desorption process produces the fine grained microstructure of Nd Fe BHx with high degrees of alignment of the crystallographic orientation consistent with the original crystallographic orientation of Fe B phase. Fine and uniform grained microstructure of RFeB based alloy is produced by recombination of the mixture during the hydrogen heat treatment and consequently offers the anisotropic rare earth magnet powder to have a high anisotropic ratio and high coercivity.

Production method of anisotropic rare earth magnet powder

An apparatus that gives continuous hydrogen heat treatment to anisotropic rare earth magnet powders is invented. The apparatus a comprises shopper 12, a furnace 11 to carry out a hydrogen heat treatment, a heat compensating means 14 that is placed in the heating room of the furnace to keep the treatment temperature constant, a movable stopper 15 to support the material in the heating room of the furnace 11 and a cooling container 18. The raw magnet powder is fed into the furnace 11 and supported by the stopper 15, then hydrogen heat treatment is carried out. After the treatment the stopper opens the bottom end of the heating room and the processed magnet powder falls into the cooling room. By the operation described above, the present apparatus can carry out continuous hydrogen heat treatment without stopping the heating of the furnace batch by batch. Continuous hydrogen heat treatment greatly improves the production efficiency and quality of the processed magnet powder.

Production apparatus for rare earth anisotropic magnet powders

A rare earth permanent magnet powder having high anisotropy, that means Br/Bs of more than 0.65, is produced by applying present invented hydrogen heat treatment. The rare earth permanent magnet powder consists essentially of rare earth element including yttrium, iron, and boron. It is subjected to hydrogen heat treatment accompanied with phase transformations. The treatment is carried out at the relative reaction rate within the range of 0.25-0.50 at 830.degree. C. and hydrogen pressure of 0.1 MPa. Here the relative reaction rate is defined as the ratio of actual reaction rate to the standard reaction rate which measured at the temperature of 830.degree. C. and hydrogen pressure of 0.1 MPa.

Anisotropic magnet powders and their production method

Rare earth magnetic powder, its fabrication method, and resin bonded

A rare earth magnet alloy including, by weight, 8 to 20% of Sm, 6 to 20% of one or more of elements selected from the group consisting of Nd, Pr and Y, 10 to 25% of Fe, 5 to 10% of Cu, 0.1 to 1% of Ti, 1 to 4% of Zr, 0.1 to 1.0% of Mn, 0.003 to 0.015% of B, optional amount of Ce and the balance of Co, in which the total sum for the amount of Nd, Pr, Y and Ce and the amount of Sm is from 22 to 28%. P and/or S may be added instead of or together with B. The magnet alloy has the coercive force of greater than 10 KOe, the residual magnetic flux density of greater than 10.5 KG and the maximum energy product of about 28 MGOe.

Growing community of inventors

Tokai, Japan

Chisato Mishima