DE69203405T3 - Anisotropic rare earth magnet. - Google Patents

Description

Territory of invention

The present invention relates to an anisotropic magnet of R- (where R is at least one rare earth element including Y represents) -Fe-Co-B system, the superior magnetic anisotropy and a small coercive force temperature coefficient owns, and in particular relates to an anisotropic magnet a hot-pressed molded body or a hot isostatic pressed Moldings.

State of technology

In the Japanese patent application No. Hei 1-132106 are a permanent magnet powder from the R-Fe-B system, obtained by hydrogen treatment of an R-Fe-B system mother alloy and a permanent magnet powder from the R-Fe-Co-B system, which is produced by hydrogen treatment of an R-Fe-Co-B system mother alloy was disclosed.

The above permanent magnetic powder from the R-Fe-B system uses an R-Fe-B system mother alloy as a raw material for the main phase of an R ₂ Fe ₁₄ B-type intermetallic compound phase (hereinafter referred to as "R ₂ Fe ₁₄ B phases). which is a ferromagnetic phase; after heat treating this parent alloy raw material in an H ₂ atmosphere in a specified temperature range and growing a phase-change state in each of the RH _x , Fe ₂ B and remaining Fe phases, H _{2 is} removed from the starting material by means of an H ₂ desorption process and the R ₂ Fe ₁₄ B phase, i.e. the ferromagnetic phase, is restored; the permanent magnetic powder obtained from the R ₂ Fe ₁₄ B system consequently has an aggregate structure such that its main phase is an extremely fine R ₂ Fe ₁₄ B phase with a recrystallized structure and an average grain diameter of 0.05-3 μm.

In addition, in the same way, the above permanent magnetic powder from the R-Fe-Co-B system uses a mother alloy from the R-Fe-Co-B system, which as one of its main phases uses an R ₂ (Fe, Co) ₁₄ B type intermetallic Compound (hereinafter referred to as R ₂ (Fe, Co) ₁₄ B phase) which is a ferromagnetic phase as its starting material, and this is processed in an identical manner to that in the case of the above R-Fe-B system; this powder has an aggregate structure, the main phase of which is an extremely fine R ₂ (Fe, Co) ₁₄ B phase with a recrystallized structure and an average grain diameter of 0.05–3 μm.

EP-A-0 274 034 discloses magnetic anisotropic magnetic powders including R-Fe-B-Ga alloys, which may contain other elements such as V, Si and Al. The Processes for making these powders include u. a. the steps of hot pressing and the plastic processing of the material.

• (a) Herstellung eines Seltenerd-Eisen-Bor-Legierungsmaterials;
• (b) anschließend Einschließen von Wasserstoff in dieses Legierungsmaterial bei einer Temperatur von 500 bis 1.000°C in einer Atmosphäre von Wasserstoffgas, das gegebenenfalls mit einem Inertgas vermischt ist;
• (c) anschließende Dehydrierung des Legierungsmaterials bei einer Temperatur von 500 bis 1.000°C, bis der Wasserstoffdruck in der Atmosphäre auf nicht mehr als 1 × 10^–1 Torr verringert ist; und
• (d) anschließendes Abkühlen des Legierungsmaterials.

EP-A-0 304 054 discloses a method for producing a rare earth-iron-boron alloy magnetic powder comprising the steps of:

• (a) preparing a rare earth iron boron alloy material;
• (b) subsequently including hydrogen in this alloy material at a temperature of 500 to 1,000 ° C in an atmosphere of hydrogen gas, which is optionally mixed with an inert gas;
• (c) then dehydrating the alloy material at a temperature of 500 to 1,000 ° C until the hydrogen pressure in the atmosphere is reduced to not more than 1 x 10 ^-1 torr; and
• (d) then cooling the alloy material.

The powder so produced is then mixed with a resin and compression molded in a magnetic field, followed from a heat treatment, to solidify the resin to produce a bonded magnet.

The above R-Fe-B system and R-Fe-Co-B system permanent magnet powders are unable to obtain sufficient magnetic anisotropy simply as a result of being molded as a hot-pressed molded article, so that, as in Japanese Patent Laid-Open No. Hei 2-39503, by performing a hot rolling process such as hot rolling or the like with the above hot pressed molded articles, and thus creating a rolled structure, the C-axes of the crystal grains with R2Fe14B phase or R ₂ (Fe, Co) ₁₄ B phase be oriented and their magnetic anisotropy is increased.

Rolled magnets from R-Fe-B system and R-Fe-Co-B system by further hot rolling obtained a hot-pressed molded body become better magnetic anisotropy; however, increases in comparison to magnets created by hot pressing of permanent magnetic powders of the above R-Fe-B system and R-Fe-Co-B systems obtained by means of a hydrogen treatment are produced, the temperature coefficient of the coercive force in unwanted Way, and in the event that a such a rolled magnet is installed in a motor or the like, The performance of such an engine or the like fluctuates with temperature and there is a problem that the Engine the stability is missing.

In addition, in the above rolled magnets from the R-Fe-B and R-Fe-Co-B systems, cause Po sitions fluctuations in the course of processing fluctuations in the magnetic anisotropy, so that to prevent this, it is impossible to avoid an increased complexity of the plastic hot working processes.

Assuming that the above increase of the temperature coefficient of the coercive force is a result of the hot rolling a hot-pressed molded body, and based on the belief that if a magnet with superior magnetic anisotropy without the use of hot rollers could be obtained this increase of the temperature coefficient of the coercive force would not occur, researched the inventors of this invention and obtained the anisotropic according to the invention R-Fe-B system magnets and R-Fe-Co-B system.

Full Description of the invention

The first made according to the invention anisotropic magnet is made by a first method, such as it is defined by claim 1.

This first anisotropic magnet has a coercive force temperature coefficient which is low, and has almost no localized fluctuations in magnetic anisotropy compared to the conventional rolled magnets, and also has superior corrosion resistance. In addition, since the magnet has an aggregate structure of crystallized grains, it has superior magnetic anisotropy and high coercive force in the area of an R ₂ (Fe, Co) ₁₄ B-type composition, that is, in the area of an R _{11.8 (} Fe , Co) _balance B _5.9 (atom%) - composition.

It is acceptable to use one or more of the elements Al, V and Si in a total amount of 0.01 to 2.0 Add atomic% to the composition of this first anisotropic magnet. In such a case, the maximum energy product is further increased.

When making this first Anisotropic magnets from the R-Fe-Co-B system will first be an R-Fe-Co-B mother alloy with a fixed component composition, the Ga, Zr and Hf, or an R-Fe-Co-B mother alloy with a specified Component composition in which Al, V and Si to the above alloy are added.

Then this mother alloy from R-Fe-Co-B system heated in a hydrogen atmosphere, a heat treatment at a temperature of 500 to 1000 ° C in a hydrogen gas atmosphere or a mixed atmosphere of hydrogen gas and an inert gas, and then one Hydrogen removal is carried out at a temperature of 500-1000 ° C, wherein a vacuum atmosphere with a hydrogen gas pressure of less than 1 torr or an inert gas atmosphere in which the partial pressure of the hydrogen gas is less than 1 Torr and by cooling received a permanent magnetic powder from the R-Fe-Co-B system.

Through an additional process for homogenization at a temperature of 600 to 1200 ° C before executing the heat treatment of the above R-Fe-Co-B mother alloy and with an additional Process for heat treatment at a temperature of 300 to 1000 ° C after the Above hydrogen desorption step, it is possible to use a permanent magnetic R-Fe-Co-B powder to produce the even better magnetic anisotropy and corrosion resistance having.

The structure of the permanent magnetic R-Fe-Co-B powder produced in the above manner includes a recrystallized aggregate structure in which recrystallized grains of an intermetallic compound phase of R ₂ (Fe, Co) ₁₄ B type, which are free from impurities or tensions within the grains or at the grain boundaries are aggregated. The average grain diameter of the recrystallized grains with this recrystallized aggregate structure is sufficiently in a range of 0.05-20 μm; however, a range of 0.05-3 µm that is close to the dimensions of the grain diameter of a single magnetic domain (about 0.3 µm) is more preferable.

Preferably the individual recrystallized grains with the dimensions above such a shape that the value of the ratio b / a of the smallest grain diameter a and the largest grain diameter b smaller is as 2; it is necessary that recrystallized grains with this form in an amount of more than 50 vol.% of the total recrystallized grains, that make up the structure of the individual powders are available. By determining the shape of the recrystallized grains, see above that this relationship b / a of the smallest grain diameter a and the largest grain diameter b a Has a value of less than 2, the coercive force of the permanent magnetic R-Fe-Co-B powder and the coercive force temperature coefficient αiHc in the temperature range from 25 ° C to 100 ° C becomes smaller as -0.6% / ° C.

In addition, since the recrystallized structure of the permanent magnetic powder produced in this way with the R-Fe-Co-B system has a recrystallized aggregate structure consisting essentially of only one intermetallic compound phase of the R ₂ (Fe, Co) ₁₄ B type, in which a grain boundary phase is almost non-existent, it is possible to increase the magnetization values of only the part without a grain boundary phase; corrosion progressing along the grain boundary phase is stopped, and since stress deformation due to thermoplastic processes also does not occur, the probability is of stress corrosion low and thus the corrosion resistance increased.

After that, the above becomes permanent magnetic R-Fe-Co-B powder into a green body in pressed a magnetic field and by subjecting this green body to one Hot press or a HIP process it is a temperature of 600 ° C-900 ° C possible, to manufacture an anisotropic magnet with the R-Fe-Co-B system, which the superior Characteristics of the above permanent magnetic powder from the R-Fe-Co-B system reserves. Moreover it is through execution a heat treatment at 300 ° C up to 1000 ° C if necessary possible to increase the coercive force.

If the above green body after a conventional one Process sintered, grow since the sintering temperature is normal high, the fine recrystallized grains of the permanent magnetic R-Fe-Co-B powder too big crystallized grains and since the magnetic characteristics and especially the Deteriorate coercivity, this is not preferred. Since also the Magnetic anisotropy in a magnetic field accomplished it is not necessary to carry out a thermoplastic process after the hot pressing or the HIP process.

The reasons for limiting component composition, of the average crystallized grain diameter and the crystallized Grain shape of the first anisotropic magnet from the R-Fe-Co-B system as follows:

(a) R

R represents one or more of the elements Nd, Pr, Tb, Dy, La, Ce, Ho, Er, Eu, Sm, Gd, Tm, Yb, Lu and Y; in general, Nd is used as the main element and this is other rare earth elements added; in particular, Tb, Dy and Pr the effect of the increase the coercive force iHc.

(b) B

It is possible to pass part of the B through to replace one or more elements from C, N, O, P and F; This is also the case with the second anisotropic described below Magnet.

(c) Ga, Zr and Hf

Ga, Zr and Hf have the function the increase the coercive force and also a stable award superior magnetic anisotropy and corrosion resistance; however if one or multiple elements of Ga, Zr and Hf in a total of less than 0.001 atomic% are contained, the desired ones Effects cannot be obtained while on the other hand, if the total contained more than 5.0 atomic% is, the magnetic characteristics deteriorate. Accordingly is the total amount of one or more elements contained from Ga, Zr and Hf in a range of 0.001-5.0 atom%.

(d) Al, V and Si

Where necessary, Al, V and Si as components of the anisotropic magnet of the R-Fe-Co-B system be added. They have the effect of increasing the coercive force; however, if one or more elements of Al, V and Si in one Total amount less than 0.01 atomic% can be contained desired Effects are not achieved while on the other hand, if this amount exceeds 2.0 atomic%, the magnetic ones Characteristics deteriorate. It is therefore preferred that an or several elements made of Al, V and Si in a total amount of 0.01–2.0 atom% are included.

(e) Average diameter of the crystallized grains and crystal form

If the average grain diameter of the crystallized grains having the structure of the anisotropic magnet is smaller than 0.05 µm, magnetization becomes a problem, so that this is not desirable, while on the other hand, if the value is more than 20 µm, the coercive force and perpendicularity of the Hysteresis loop are reduced and also the temperature coefficient of the coercive force increases, so that this is also not advantageous. Accordingly, the average diameter of the crystallized grains is set at 0.05-20 μm. It is more preferable that the average diameter of the crystallized grains is in the range of 0.05-3 µm, which is close to the dimensions of the grain diameter of the simple magnetic domains (0.3 µm). It is preferred that the individual crystallized grains have a value less than 2 for the ratio b / a, the ratio of the smallest grain diameter a and the largest grain diameter b; it is necessary that crystallized grains with such a shape be present in an amount of more than 50% by volume of the total crystallized grains. By making the shape of the crystal lized grains is set so that a value of less than 2 for the ratio b / a between the smallest grain diameter a and the largest grain diameter b is obtained, the coercive force of the anisotropic R-Fe-B magnet is improved, the corrosion resistance is increased and the temperature coefficient of the coercive force is reduced. Accordingly, the value b / a of the individual crystallized grains is set to less than 2.

With regard to the amount of Co contained are made by adding Co to the composition of the anisotropic magnet the coercive force and magnetic temperature characteristics (e.g. the Curie point) of the anisotropic magnet improved and beyond the effect of an increase corrosion resistance receive; however, if the amount contained is less than 0.1 Atomic% is can these effects are not achieved while, on the other hand, when the Amount exceeds 50 atomic%, the magnetic characteristics deteriorate so that it does not is preferred. Accordingly, the amount of Co is in a range from 0.1-50 Atom% set. If the amount of Co contained in one area from 0.1-20 atomic% lies, the coercive force increases the most, so that it is special it is preferred that the amount of Co contained is 0.1-20 atom% set.

In addition, the reasons for restricting the preferred range of amounts of Al, V and Si that contain are the same as in the case of the second anisotropic discussed below Magnet.

The second anisotropic according to the invention Magnet is an anisotropic magnet from the R-Fe-Co-B system as it passes through Claim 3 is defined.

As in the case of the first anisotropic magnet above, this second anisotropic magnet has a small coercive force temperature coefficient, has almost no localized fluctuations in magnetic anisotropy compared to conventional rolled magnets, has superior corrosion resistance and, because this magnet has an aggregate structure of crystallized grains , it has superior magnetic anisotropy and high coercive force even in the vicinity of an R ₂ (Fe, Co) ₁₄ B compound composition, that is, near an R _11.8 (Fe, Co) _residue B _5.9 (atom%) -Composition.

To this second anisotropic magnet to produce, an R-Fe-Co-B mother alloy with a specified component composition that one or more which contains elements Ti, V, Nb, Ta, Al and Si, subjected to melt casting, and using this alloy as a raw material processing performed become identical to that in the case of the first anisotropic magnet above is.

The reasons for the limitation of R, B, Co, the average diameter of the crystallized grains and the crystallized grain shape in the composition of the components of the anisotropic invention Magnets as stated above are the same as in the case of the first anisotropic magnet that was previously discussed.

Regarding Ti, V, Nb, Ta, Al and You can by adding one or more of these elements to the components of the anisotropic magnet from the R-Fe-B system have the effects of increasing the Coercive force and the stable imparting of superior magnetic anisotropy and corrosion resistance be preserved; however, if the total amount of these items, the is less than 0.001 atomic%, can be desired Effects cannot be obtained while on the other hand, if this amount exceeds 5.0 atomic%, the magnetic Deteriorate characteristics. Accordingly, the total amount of one or more of the elements Ti, V, Nb, Ta, Al and Si, which is contained to a value in the range of 0.001-5.0 atom% set.

Even if this second anisotropic Magnet at least one element made of Ni, Cu, Zn, Ga, Ge, Zr, Mo, Hf and W in an amount of 0.001-5.0 Atomic% contains he has a superior one magnetic anisotropy and corrosion resistance.

Examples

The first and second anisotropic Magnets according to the present Invention were made in the following manner and their characteristics certainly.

(Examples for the first anisotropic magnets)

A first anisotropic magnet according to the present Invention was made in the manner described below and determined its characteristics.

Ingots of various R-Fe-Co-B alloys, which contained Co and one or more elements made of Ga, Zr and Hf, and bars of R-Fe-Co-B alloys that did not contain Ga, Zr or Hf, which had been obtained by plasma melting and casting, were made, these alloy bars of homogenization in an argon gas atmosphere subjected to conditions such that its temperature is 1120 ° C and the Processing time was 40 h, and then this homogenized Ingots broken to a fineness of 20 mm, making a starting alloy was formed.

The temperature of this starting alloy was raised from room temperature to a temperature of 830 ° C in a hydrogen atmosphere at a pressure of 101 kPa (1 atmosphere), a heat treatment was carried out in this hydrogen atmosphere at a temperature of 830 ° C for a period of 4 hours and then Desorbed hydrogen at a temperature of 830 ° C to create a vacuum of less than 13 Pa (1 x 10 ^-1 Torr), and immediately afterwards argon gas was introduced and rapid cooling was carried out.

After completing the above hydrogen treatment the ingots became light in mortars grated and various R-Fe-Co-B permanent magnet powder with a average particle size of 50 microns obtained.

These R-Fe-Co-B permanent magnet powders were press-molded in a magnetic field to form green bodies, and these green bodies were subjected to hot pressing under conditions such that the temperature was 700 ° C and the pressure was 1.5 t / cm ² , The arrangement and the hot pressing were carried out in such a way that the direction of orientation was identical to the pressing direction during the hot pressing.

By further heat processing the various molded articles at a temperature of 620 ° C for 2 hours, the anisotropic magnets 79-109 of the present invention and the anisotropic comparison magnets 30-39 shown in Tables 20-23 were produced. The densities of these anisotropic magnets were sufficiently precise and ranged from 7.5 to 7.6 g / cm ³ .

On the other hand, an R-Fe-Co-B permanent magnet powder, made from an ingot of an alloy without Ga, Zr or Hf had been put in a vacuum in a copper can, on a Temperature of 700 ° C heated and rolled several times so that the rolling ratio 80% reached, and the conventional anisotropic magnet 3 shown in Table 23 receive.

The different structures of the anisotropic according to the invention Magnets 79-109, of the anisotropic comparison magnets 30-39 and the conventional one anisotropic magnets 3 with those shown in Tables 20-22 Component compositions were examined using a scanning electron microscope observed and the average diameter of the crystallized grains that Amount of the present crystallized grains having a shape in which The relationship the largest grain diameter, divided by the smallest grain diameter, a value of less than 2, the coercive force temperature coefficient αiHc and the magnetic characteristics were determined. The thus obtained Values are shown in Tables 24–27 shown. The calculation method for the coercive force temperature coefficient αiHc is like mentioned above.

It is clear from the results shown in Tables 20-27 that the anisotropic magnets 79-109 of the present invention containing one or more elements made of Ga, Zr and Hf have superior magnetic characteristics and, in particular, a superior maximum energy product (BH) _max and one have better residual magnetic flux density Br and moreover have a superior anisotropy. In addition, compared to the conventional anisotropic magnet 3 obtained by rolling, the anisotropic magnets 79-109 of the present invention have substantially identical magnetic characteristics; however, their coercive force temperature coefficient αiHc is significantly smaller and reaches a value of –0.5% / ° C. In addition, in the case of the comparative anisotropic magnets 30-39 whose compositions are outside the scope of the present invention, the magnetic characteristics and the magnetic anisotropy are deteriorated.

(More examples for the first anisotropic magnets)

Then ingots were made from various alloys with component compositions, the egg Contained nes or more of the elements Al, V and Si in addition to the R-Fe-Co-B alloy with one or more elements made of Ga, Zr and Hf and obtained by means of high-frequency induction melting and casting; these bars were subjected to an identical procedure as the anisotropic magnets 79-109 and the anisotropic comparison magnets 30-39 above, and thus R-Fe-Co-B permanent magnet powder with an average particle size of 40 μm was produced. These permanent magnet powders were press-molded in the presence or absence of a magnetic field to form green bodies, these green bodies were subjected to hot isostatic pressing under conditions such that their temperature was 710 ° C. and their pressure was 1.7 t / cm ² , and the anisotropic magnets 110–11 according to the invention 119 and the anisotropic comparison magnets 40-42, which had the compositions shown in Table 28, were obtained.

The average diameter of the crystallized grains the amount (% by volume) of the present crystallized grains for which the Value of the ratio of largest grain diameter / smallest Grain diameter was less than 2, the coercive force temperature coefficient αiHc and the magnetic characteristics of these anisotropic magnets in the same way as determined above. The results of this will be shown in Table 29.

As from the results of tables 28 and 29 can be seen, is added by adding 0.1-2.0 atom% one or more of the elements Al, V and Si at 0.01-5.0 atom% the maximum of one or more elements made of Ga, Zr and Hf Energy product increased further. Moreover it becomes clear that the Diameter of the crystallized grains and the shape of the crystallized grains a big Effect on reducing the coercive force temperature coefficient to have.

(Examples of one second anisotropic magnet)

Then a second anisotropic magnet according to the present invention was applied to the following described manner and determined its characteristics.

Ingot made of an R-Fe-Co-B alloy with one or more elements made of Ti, V, Nb, Ta, Al and Si and Bars made of an R-Fe-Co-B alloy that does not contain Ti, V, Nb, Ta, Al or contained Si, which were obtained by plasma melting and casting were subjected to homogenization in an argon gas atmosphere subject to conditions such that their temperature is 1130 ° C and the Processing time was 20 hours, and then they were homogenized Ingots broken to a fineness of approximately 15 mm, so that starting alloys were formed.

The temperature of these starting alloys was raised from room temperature to 830 ° C in a hydrogen gas atmosphere at a pressure of 101 kPa (1 atmosphere), heat treatment was carried out in a hydrogen gas atmosphere at a temperature of 830 ° C for 1 hour, hydrogen at a temperature of 830 ° C desorbed so that a vacuum of less than 13 Pa (1 × 10 ^-1 Torr) was generated, and immediately afterwards, argon gas was blown in and rapid cooling was performed. After this hydrogen treatment was completed, heat processing was carried out in a vacuum at a temperature of 630 ° C for a period of 2 hours. The starting alloys obtained in this way were lightly ground in mortars and magnetic powder with an average particle size of 40 μm was obtained.

These magnetic powders were press-molded in a 25 KOe magnetic field to produce green bodies, and each green body was subjected to hot pressing under conditions such that its temperature was 720 ° C and its pressure was 1.5 t / cm ² , or was subjected to HIP Process was subjected to conditions such that its temperature was 710 ° C and its pressure was 1.5 t / cm ² , and moreover, each molten body was subjected to heat treatment at a temperature of 620 ° C for a period of 2 hours. The green bodies, which were formed in a magnetic field, were arranged and hot pressed in such a manner that their direction of orientation was identical to the pressing direction of the hot pressing.

Among the anisotropic magnets 120-164 of the present invention and the anisotropic comparison magnets 43-56 manufactured in the above manner, the anisotropic magnets 120-144 of the present invention and the anisotropic comparison magnets 43-49 were manufactured by hot pressing while the Anisotropic magnets 145-164 according to the invention and the anisotropic comparison magnets 50-56 were generated by a HIP method. In all cases, their density was sufficiently precise and was in the range from 7.5 to 7.6 g / cm ³ .

It was also used for comparison purposes an R-Fe-Co-B permanent magnet powder from an ingot of an alloy without Ti, V, Nb, Ta, Al or Si put in a copper can in a vacuum, to a temperature of 720 ° C heated and rolled several times, so that the rolling ratio one Reached a value of 80%, and so a conventional anisotropic magnet 4 received.

The component compositions of the anisotropic magnets 120-164 of the present invention, the anisotropic comparison magnets 43-56 and of the conventional anisotropic magnet obtained in the above manner 4 are shown in Tables 30-35 shown. About that In addition, the average diameter of the crystallized grains that Amount (vol.%) Of the crystallized grains present a form in which the value of the ratio of the largest grain diameter / smallest Grain diameter was less than 2, the magnetic characteristics and the coercive force temperature coefficient αiHc of these anisotropic magnets an identical method as determined above and the resulting Values in Tables 36–40 shown.

From the results of the tables 36-40 it becomes clear that the anisotropic R-Fe-Co-B magnets according to the invention 120-164 of the present invention comprising one or more of the elements Ti, V, Nb, Ta, Al and Si contain essentially identical magnetic ones Characteristics compared to conventional anisotropic magnets 4, which does not contain these elements; however, the coercive force is temperature coefficient noticeably smaller. If also the contained amount of Ti, V, Nb, Ta, Al and Si outside the ranges of the present invention are as in the case of the anisotropic ones Comparative magnets 43-56, magnetic anisotropy deteriorates and it is clear that the Diameter of the crystallized grains and the crystallized Grain shape also a big one Influence on which have magnetic characteristics.

possibilities for industrial use

According to the invention, by using a hydrogen-treated powder R-Fe-Co-B system containing one or more elements made of Ga, Zr and Hf or one or more elements made of Ti, V, Nb, Ta, Al and Si, possible to obtain an anisotropic magnet for which the magnetic anisotropy is large and, moreover, the coercive force-temperature coefficient is small, so that there is no need to carry out a magnetic anisotropization process such as a thermoplastic process or the like as is the case with the conventional process, and thereby the production cost can be considerably reduced become. Accordingly, the invention greatly contributes to the possibility of manufacturing electronic machines such as motors and the like, and to improvements in stability.

Claims (4)

A process for producing an anisotropic magnet of the rare earth Fe-Co-B system, which is a hot pressed molded body or a hot isostatically pressed molded body, and comprises: a rare earth element including Y, B, 0.001-5 atomic% in total of one or more elements made of Ga , Zr and Hf, and 0.1-50 atomic% Co; the balance being Fe and inevitable impurities; said body having an aggregate structure of crystallized grains comprising essentially only one phase of an R ₂ (TM) ₁₄ B type intermetallic compound having a tetragonal structure, wherein R is at least one rare earth element including Y and TM is Fe and Co, and the crystallized grains have dimensions of 0.05-20 µm; and the ratio of the largest grain diameter b to the smallest grain diameter a is less than two for individual crystallized grains representing more than 50% by volume of the total crystallized grains of the aggregate structure; the method comprising the steps of: (i) heating an R-Fe-Co-B mother alloy including one or more elements of Ga, Zr and Hf in a hydrogen gas atmosphere, which optionally includes an inert gas, at 500 to 1,000 ° C, ( ii) removing hydrogen from the atmosphere at a temperature of 500 to 1,000 ° C so as to create a vacuum atmosphere with a hydrogen gas pressure of less than 0.13 kPa (less than 1 Torr) or an inert gas atmosphere in which the partial pressure of hydrogen gas is less than Is 0.13 kPa (less than 1 Torr), (iii) cooling the alloy to obtain a permanent magnetic powder from the R-Fe-Co-B system with a recrystallized aggregate structure that is essentially only a phase of one intermetallic compound of R ₂ (Fe, Co) ₁₄ B type comprises, (iv) pressing the magnetic powder in a magnetic field into a green body, and (v) hot press molding or hot isostatic molding of the Gr nkörpers at a temperature of 600 to 900 ° C. Method according to claim 1, the magnet totaling 0.01-2.0 atomic% of one or more Al, V and Si elements. A process for producing an anisotropic magnet of the rare earth Fe-Co-B system, which is a hot-pressed molded body or a hot isostatically pressed molded body, and comprises a rare earth element including Y, B, 0.001-5 atom% in total of one or more elements made of Ti, V, Nb, Ta, Al and Si, and 0.1-50 atomic% Co; the balance being Fe and inevitable impurities; said body having an aggregate structure of crystallized grains comprising essentially only one phase of an R ₂ (TM) ₁₄ B type intermetallic compound having a tetragonal structure, wherein R is at least one rare earth element including Y and TM is Fe and Co, and the crystallized grains have dimensions of 0.05-20 µm; and the ratio of the largest grain diameter b to the smallest grain diameter a is less than two for individual crystallized grains which account for more than 50% by volume of the total crystallized grains of the aggregate structure, the method comprising the steps of: (i) heating an R-Fe -Co-B mother alloy including one or more elements of Ti, V, Nb, Ta, Al and Si in a hydrogen gas atmosphere, which optionally includes an inert gas, at 500 to 1,000 ° C, (ii) removing hydrogen from the atmosphere a temperature of 500 to 1,000 ° C so as to create a vacuum atmosphere with a hydrogen gas pressure of less than 0.13 kPa (less than 1 Torr) or an inert gas atmosphere in which the partial pressure of Hydrogen gas is less than 0.13 kPa (less than 1 Torr ) be (iii) cooling the alloy to obtain a permanent magnetic powder from the R-Fe-Co-B system with a recrystallized aggregate structure that is essentially only one phase of an intermetallic compound from R ₂ (Fe, Co) ₁₄ B-type comprises (iv) pressing the magnetic powder in a magnetic field into a green body, and (v) hot molding or hot isostatic molding the green body at a temperature of 600 to 900 ° C. Procedure according to a the preceding claims, where the average diameter of the crystallized grains is 0.05 up to 3 μm is.