RU2631055C2 - Method for manufacturing constant magnets from alloys based on rare-earth elements, iron and cobalt with improved magnetic properties - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to powder metallurgy associated with manufacturing of magnets from powder materials, rare earth alloys with cobalt and iron in particular, and can be used for manufacturing of metal-ceramic and metal-plastic constant magnets with high residual induction values and maximum energy product for engineering, instrument-making, electrotechnical and other industries. The method for constant magnets manufacturing allows the powder textured in the electromagnet in elastic matrices to be additionally textured in a pulsed magnetic field in the direction coinciding with the direction of the electromagnet field, then pressed in a hydrostat, after which the press blanks are removed from the elastic matrices and sent for sintering. Sinter containers with a loaded powder textured in electromagnet are closed with lids, after which the powders are sintered directly in the containers.

EFFECT: increasing density of constant magnets.

3 cl, 3 tbl, 3 dwg

Description

The invention relates to the field of powder metallurgy related to the manufacture of magnets from powder materials, in particular from alloys of rare-earth metals with cobalt and iron, and can be used in the production of cermet and metal-plastic permanent magnets with high values of residual induction and maximum energy product for machine-building, instrument-making , electrical and other industries.

For a theoretical assessment of the values of the residual induction B _r and the maximum energy product (HV) _{max of} permanent magnets, there are simple mathematical relationships that relate them to the characteristics of the phase composition and microstructure. The value of B _r can be determined from the formula:

where 4πM _s is the saturation magnetization of the ferromagnetic magnetic hard phase at room temperature,

V is the volume fraction of the ferromagnetic magnetic phase in the magnet,

α _ρ is the relative density of the sintered magnet to the density of the cast alloy,

α _t - the degree of texture of the grains of the magnetically solid phase.

To determine the theoretical limit of the value (BH) _max , the expression is used:

provided that the demagnetization curve of the magnet has perfect squareness, and for the values of the coercive force in magnetization _M H _c and in induction _B H _c the relation is satisfied:

Expressions (1) and (2) clearly show that the values of B _r and (BH) _{max are} proportional to the first and second degree α _t, respectively. In turn, the value of the degree of texture is experimentally determined on the basis of formula (1):

A known method of creating a crystalline texture in powder magnets is the orientation by an external magnetic field of single-crystal powder particles placed in a mold matrix of a non-magnetic material, followed by compaction by pressing. [I.B. Kekalo, B.A. Samarin. Physical metallurgy of precision alloys; alloys with special magnetic properties. M .: Metallurgy, 1989, 495 pp.] Several pressing schemes are used, differing in the mutual direction of the magnetic field created by the poles of the electromagnet and applied during compaction of the pressing force:

1. In a metal matrix placed in a press magnet, a pressing force is applied parallel to the direction of the texture magnetic field. In this scheme, the texture is most severely destroyed by pressing and, as a rule, the degree of texture in the billet does not exceed 90%.

2. In a metal matrix placed in a press magnet, a pressing force is applied perpendicular to the direction of the texture magnetic field [Endoh M., Shindo M., Material design and fabrication of high energy Nd-Fe-B sintered magnets. Proc. 13th Int. Workshop on REPM and their Applications. Birmingham, United Kingdom, 1994. P. 379-404]. The degree of texture in the billet obtained in this way can reach 95%, but for this it is necessary to significantly reduce the pressing pressure, which is accompanied by a decrease in the mechanical strength of the billet and its frequent destruction when removed from the matrix or during subsequent transportation and loading into the sintering furnace.

3. Texturing and pressing of powder placed in an elastic sleeve, which, in turn, is inserted into a metal matrix [Sagawa M, Nagata H. Novel processing technology for permanent magnets. IEEE Trans Magn MAG-29, 1993: 2747]. With this scheme, which is carried out in a press electromagnet, the pressing force is applied parallel to the direction of the texturing magnetic field, but the chains of powder particles that line up under the influence of the magnetic field are not destroyed during pressing, since they are affected by lateral support transmitted through an elastic sleeve. If the bulk density of the powder loaded into the elastic sleeve does not exceed 25% of the density of the original cast alloy, then the degree of texture in the billet obtained by this method can reach 95-97%. The disadvantage of this method is the inability to obtain press blanks of a given geometric shape with a uniform density distribution. The geometric shape of the billet is improved if the bulk density of the powder increases to 35-45%, however, this is accompanied by a decrease in the degree of texture due to increasing friction between the powder particles and the difficulty of creating a strong textural magnetic field, since an electromagnet is used as the field source.

4. A beneficial modification of the previous method is the loading of the powder into an elastic matrix, which is not inserted into the metal matrix, which allows texturing of the powder by a pulsed magnetic field, the intensity of which can be increased several times compared to the static field of an electromagnet, and subsequent pressing of the powder in an elastic matrix placing it in a hydrostat [M. Sagawa, Nagata H. Proc. 17th Int. Workshop on Rare-Earth Permanent Magnets and Their Applications, Newark, USA, 2002, pp 183-186]. The method is called isostatic pressing or RIP (Rubber Isostatical Pressing). Since the degree of texture in the ensemble of powder particles is higher, the higher the strength of the texture field, in accordance with formulas (1) and (2), the values of residual induction B _r and (BH) _max for the final products are higher.

The disadvantage of this method is the problem of maintaining the achieved high degree of texture after the termination of the external pulsed magnetic field. When a pulsed magnetic field is applied, the powder particles remain magnetized and form a permanent magnet with a relatively low density of material. Since the texturing and pressing processes in the hydrostat are separate, under the influence of the own magnetic field from the poles of the billet in its peripheral regions, the axes of the easy magnetization of the powder particles can turn from the original direction achieved under the influence of the texturing magnetic field, which worsens the texture in the magnetic poles. This negatively affects the final values of B _r and (BH) _{max of the} sintered magnet. An additional disadvantage is the complexity of the technology and the decrease in productivity associated with pressing in a hydrostat [W. Rodewald, B. Wall, M. Katter, K. Ustimer, S. Steinmetz. Extraordinary strong Nd-Fe-B magnets by a controlled microstructure // Proc. 17th International Workshop Rrare-Earth Magnets and Their Applications, Newark, Delaware, USA, 2002, P. 25-36].

5. Texturing of the powder by a pulsed magnetic field is also carried out in a progressive method for producing sintered permanent Nd-Fe-B magnets, characterized by the absence of a powder pressing stage [T. Hiroki, I. Naoyaki, JP 7153612 (A); M. Sagawa, JP 2007180373 (A); M. Sagawa, JP 2007180375 (A); M. Sagawa, Y. Une, A new process for producing Nd-Fe-B sintered magnets with small grain size, Proc. 20th Int. Workshop on Rare Earth Permanent Magnets and Their Applications (Knossos-Crete, 2008), p.103-105; WF Li, T. Ohkubo, Κ. Hono, M. Sagawa, The origin of coercivity decrease in fine grained Nd-Fe-B sintered magnets, J. Magn. Magn. Mater., 2009, V. 321, p. 1100-1105; M. Sagawa, Development and prospect of the Nd-Fe-B sintered magnets, Proc. of 21st Int. Workshop on REPM and their Applications (Bled, Slovenia, 2010), p. 183-186; Masato Sagawa, European Patent Application EP 2187410 A1; U.S. Patent 20120176212 A1]. In English transcription, this technology is called the "pressless process (PLP)", and for the Russian language it is appropriate to use the "process without pressing (BPP)" powders. The powders are loaded into special containers, compacted by the application of vibration, textured in a pulsed magnetic field and then sintered directly in the containers. The implementation of FSN provides a number of significant advantages: (1) simplifies the technology; (2) it makes it easier to carry out a low-oxygen process and thereby increase the coercive force H _{from the} magnets without using the additives Dy and / or Tb; (3) it contributes to obtaining sintered magnets of excellent shape and final size; therefore, the grinding procedure for the magnets after the UPS is either not performed or is minimized, ensuring a reduction in the cost of the starting material and a reduction in the price of the products.

The disadvantages of PBP include the need to use a high bulk density of powders ρ _n in sintering containers. If the values of ρ _n are less than 2.5 g / cm ³ (approximately 30% of the density of the initial cast alloy), then the required density of the magnets is not achieved after sintering, and at large values a low level of texture and a low residual induction B _{r are formed} . The reason for the decrease in the degree of texture is an increase in the friction forces between the powder particles, as ρ _n increases. The force torque acting on each particle of the powder from the side of the magnetic field is unable to overcome friction, and the particles do not orient themselves with their easy magnetization axes strictly along the direction of application of the field. Overcoming such friction forces is possible only with the application of powerful pulsed magnetic fields for texturing powders. For example, Sagawa, texturing powders with ρ _n = 3.6 g / cm ³ (47% of the density of the initial cast alloy), used pulsed fields with a maximum intensity of H _m > 60 kOe. To induce such powerful pulsed fields in the volume required to place the containers, very large-sized solenoids and powerful power sources are required.

One of the possible approaches to increasing the degree of texture of magnets manufactured using the PBP technology is to reduce the friction forces between the powder particles by introducing internal lubricants that cover the particles during the grinding of the powders. This method according to the patents [Masato Sagawa, US patent 2007245851 A1, Popov A.G., RF patent 2525867] allows to reduce the intensity of the texture pulsed magnetic field and at the same time to form a high degree of texture in the magnets. The disadvantage of this method is that at low concentrations of lubricating additives (less than 1% by weight of the alloy powder) it is difficult to uniformly coat the entire vast surface of the powder particles with lubricant. If the concentration of lubricants containing oxygen atoms in their composition exceeds the maximum permissible concentration, then the lubricant cannot be completely removed from the surface of the powder particles by slowly heating it in vacuum and oxygen interacts with the powder during sintering, sharply reducing the density and magnetic properties of sintered magnets ( first of all, coercive force).

Thus, the above review of texture guidance methods in magnetically uniaxial powders of alloys based on rare-earth elements of iron and cobalt shows that the problem of obtaining sintered magnets with high values of B _r and (BH) _max consists in the need to induce a high degree of texture in powders with a sufficiently high density constituting more than 40% of the density of the original cast alloy. In these methods, the task of texture guidance was solved in the following sequence: first loading the powder into the sintering matrix or container, and then turning on the texturing magnetic field created by the electromagnet or pulsed solenoid.

The basis of the present invention is the task of increasing the degree of texture and the values of B _r and (BH) _{max of} sintered permanent magnets from alloy powders based on rare-earth elements of iron and cobalt by reducing the friction forces between the particles of the powder textured in a magnetic field. According to the invention, in contrast to known methods in which a powder of alloys based on rare-earth elements of iron and cobalt is loaded into compression dies or sintering containers with a high bulk density (20-45% of the density of the initial cast alloy), then is textured by the inclusion of a constant or pulsed magnetic field and compacted by subsequent pressing or vibration, in this application, the powder is poured into a free state in the matrix for pressing or sintering, placed in a pre-included agnitnoe field. Free powder particles flying into a magnetic field practically do not experience friction against each other and are ideally aligned with their easy magnetization axes along the field direction, forming a high degree of texture. Then, the powder is compacted in such a state to the required loading density by applying pressure and / or vibration that does not destroy the induced texture, and then it is sintered in the form of press blanks or in sintering containers using the PBP method to a density close to 100% of the density of the initial cast alloy .

The problem is solved in that a method for producing a sintered permanent magnet from alloys based on rare-earth elements of iron and cobalt, including smelting and casting of the alloy, including using strip casting technology, the preparation of powders with an average particle size of 2.5-5 microns by grinding the alloy in vibrational or a jet mill, loading powders into pressing matrices or into sintering containers, texturing powders in a constant magnetic field of 10-20 kOe, compaction of powders by vibration with a frequency of 10-50 Hz and / and and compressing the powder with a piston in the direction perpendicular to the application of a magnetic field to a density of 20-45% of the density of the initial cast alloy and subsequent sintering of the powders, characterized in that to increase the degree of texture of the magnets, the powders are poured into matrices or sintering containers placed in the included magnetic field.

Wherein

- the powder textured in an electromagnet in elastic matrices is additionally textured in a pulsed magnetic field of 35 kOe with a pulse duration of 10 ms in the direction coinciding with the direction of the electromagnet field, and then pressed in a hydrostat at a pressure of 1.6-2.6 kbar, then press preforms are removed from elastic matrices and sent for sintering.

- sintering containers with loaded powder textured in an electromagnet are closed with lids, after which the powders are sintered directly in the containers.

In FIG. Figure 1 shows the dependences of the density ρ, B _r , the coercive force Н _с and (ВН) _{max of} sintered magnets on the bulk density of the powder textured in a constant magnetic field of 12 kOe according to the claimed (1) and traditional (2) methods.

In FIG. 2. The dependences of the properties of sintered magnets on the strength of the texture field are shown, into which powders were filled without vibration and with vibration at a frequency of 40 Hz.

In FIG. 3. demagnetization curves are shown along (B) and across (P) the texture of magnets prepared according to the claimed (1) and traditional (2) methods.

The claimed method is as follows. Alloys of the Sm-Co-Fe-Cu-Zr or Nd-Fe-B system are prepared by induction melting followed by casting. The ingots are pre-milled to a particle size of less than 500 microns, then the powders are further crushed to an average particle size of 2.5-5 microns in a jet mill using nitrogen as a working gas, or in a vibration mill in toluene. The powders are poured into elastic pressing matrices or sintering containers made of molybdenum or graphite, which are preliminarily placed in the interpolar space of an electromagnet with a 10-20 kOe field switched on. Under the influence of a magnetic field, textured powders are compacted by vibration with a frequency of 10-50 Hz and / or by applying a pressure to the powder through a piston, the value of which does not exceed 200 kg / cm ² and does not destroy the induced texture. The density of the loaded powders ρ _n varies from 2.5 to 3.5 g / cm ³ . After turning off the magnetic field, the matrices and containers are removed from the electromagnet. The textured powder in elastic matrices is additionally textured in a pulsed magnetic field of 35 kOe with a pulse duration of 10 ms in the direction coinciding with the direction of the electromagnet field, and then pressed in a hydrostat at a pressure of 1.6-2.6 kbar, after which the press blanks are removed from the elastic matrices and sent for sintering. Before removing sintering containers from the electromagnet, they are covered with lids, after which the powders are sintered directly in the containers. Sintering of the powders is carried out in vacuum or in an argon atmosphere at temperatures from 1020 to 1250 ° C, depending on the alloy composition for 1 hour. After sintering, all magnets are subjected to additional heat treatment and quenched to room temperature.

Case Study 1

Texturing Powder Sm-Co-Fe-Cu-Zr in an Elastic Matrix

An alloy having a composition of 25.9 Sm, 46.9 Co, 17.9 Fe, 6.6 Cu, 2.7 Zr (wt.%) Was smelted in an induction furnace and poured into a massive copper mold, then crushed in a jaw mill and further crushed in a vibration mill to an average particle size according to Fisher 3.7-3.9 microns. A rubber matrix (Silastic) with an inner rectangular cavity of 57 × 45 × 66 mm ³ was placed in the center of the interpolar gap of the electromagnet and a constant magnetic field of 12 kOe was included along the matrix size of 57 mm. The powder was poured into a matrix placed in the included field, and then compacted by vibration with a frequency of 10-50 Hz to a loading density ρ _n = 3.5 g / cm ³ . After switching off the texture field, the matrix was removed from the electromagnet, closed with a rubber cover and placed in a solenoid for additional texturing of the powder in a pulsed magnetic field of 35 kOe with a pulse duration of 10 ms in the direction coinciding with the direction of the electromagnet field. Next, a rubber matrix with a textured powder was placed in a chamber of a hydrostatic pressing machine with comprehensive compression at a pressure of 2.63 kbar. After removing the billets from the rubber matrix, they were sintered in argon at a temperature of 1210 ° С for 2 h, a high-temperature treatment was carried out at 1170 ° С with a holding time of 6 h, and an additional low-temperature treatment with slow cooling from 810 to 400 ° С for 30 h.

The properties of the obtained magnet are shown in the first row of Table 1. They are compared with the properties of the magnet obtained from the same powder, but textured in the traditional way, in which the powder was loaded into the same rubber matrix for pressing, but the texture field was turned on after the matrix with the powder was placed in the pole electromagnet clearance. Subsequent operations of the technological process were carried out in a single cycle. From a comparison of the data in the table it follows that the application of the claimed method allows to increase the texture of the magnets, as a result of which the values of B _r and (HV) _{max are} increased by 5 and 8%, respectively.

Case Study 2

Texturing Nd-Fe-B Powder in an Elastic Matrix

A strip casting alloy having a composition of 24.50 Nd, 5.00 Dy, 68.25 Fe, 0.95 V, 1.00 Co, 0.10 Cu, 0.15 Al (wt.%) Was hydrogenated and then ground in a jet mill to an average particle size of Fischer 3.0- 3.3 microns, using nitrogen as the working gas. A rubber matrix of the same shape and size as in Example 1 was placed in the center of the pole gap of the electromagnet and a constant magnetic field of 12 kOe was turned on. The powder was poured into a matrix placed in the included field, and then compacted by vibration with a frequency of 10-50 Hz to a loading density ρ _n = 2.8-3.0 g / cm ³ . After switching off the constant texturing field, the powder was additionally textured in a pulsed magnetic field, as in Example 1. Next, a rubber matrix with a textured powder was placed in a chamber of a hydrostatic pressing machine with comprehensive compression at a pressure of 1.58 kbar. After removing the press blanks from the rubber matrix, they were sintered in vacuum at a temperature of 1060 ° С for 1 h and additional low-temperature processing was performed: 900 ° С + 550 ° С with a holding time of 1 hour.

The properties of the obtained magnet are shown in the first row of Table 2. They are compared with the properties of the magnet obtained from the same powder loaded in the traditional way, in which the powder was loaded into the same rubber matrix for pressing, however, the texture field was turned on after placing the matrix with the powder in the interpolar gap electromagnet. From a comparison of the data in the table it follows that the application of the claimed method allows to increase the texture of the magnets, as a result of which the values of B _r and (HV) _{max are} increased by 7 and 19%, respectively.

Case Study 3

Texturing Nd-Fe-B Powder in a Sintering Container: Dependence of Properties on Powder Loading Density

Strip casting alloys having a composition of 30.00 Nd, 1.95 Dy, 66.42 Fe, 0.99 V, 0.54 Co, 0.1 Ga (wt.%) Were hydrogenated and then crushed in a vibration mill in toluene to an average particle size of 2.9 μm. The powder was poured into a molybdenum container with an internal rectangular cavity of 12 × 12 × 20 mm ³ . The container was placed in the center of the interpolar gap of the electromagnet and a constant magnetic field of no more than 12 kOe was turned on. Free powder was poured into the container and then compacted to a loading density ρ _n = 2.6-3.2 g / cm ³ using a piston and a screw device. Low pressure on the powder (not more than 100 kg / cm ² ) did not lead to the destruction of the induced texture. After turning off the texture field, the container was removed from the electromagnet, closed with a molybdenum lid, and transferred to a sintering furnace. The powders were sintered in vacuum directly in containers at a temperature of 1100 ° С for 1 h and an additional low-temperature treatment of 900 ° С + 600 ° С was carried out with an exposure time of 0.5 h.

In FIG. 1 bright triangles represent the dependence of the density ρ, B _r , coercive force H _c and (HH) _{max of} sintered magnets on the bulk density of the powder. The values of all characteristics increase with increasing ρ _n to 3.1 g / cm ³ .

The dark triangles in FIG. 1 also shows the dependences ρ, B _r , H _c and (BH) _{max of} sintered magnets obtained by loading the powder into containers according to the traditional scheme until the magnetic field is turned on. An almost linear decrease in B _{r of} these magnets indicates a significant violation of the texture with an increase in ρ _n . The increasing friction force arising between the particles of the compacted powder is quite large, and this prevents the texture from being induced in the applied magnetic field H ~ 12 kOe. Despite the fact that the magnets obtained according to the traditional scheme have higher density values, they are significantly inferior to the magnets, the powder of which is poured into the included magnetic field, according to the values of B _r and (BH) _max . For example, when ρ _n = 3.1 g / cm ^{3, the} values of B _r and (BH) _{max of} magnets manufactured by the claimed method are 71 and 214% higher than those of traditional technology magnets, respectively.

The reason for the lower density of magnets prepared by filling the powder in the switched-on magnetic field is that chains of particles are formed that are oriented along the direction of the field. As a result of magnetostatic interaction, the chains repel each other, which impedes the process of compaction. The loading density ρ _n = 3.1 g / cm ^{3 is} not enough to overcome the forces of magnetostatic repulsion between the chains. The resulting inhomogeneity in the density of the powder thus loaded into the container also leads to an inhomogeneous density of the sintered magnets.

Significantly exceed ρ _n = 3.1 g / cm ³ in the present experiment was not possible, since the applied pressure (about 100 kg / cm ² ) approached the tensile strength of the structure used to load the powder. Potentially, a further increase in ρ, B _r, and (BH) _{max is} possible with an increase in ρ _n up to 3.5 g / cm ³ (46% of the density of the initial cast alloy). However, further powder compaction is known [H. Kotera, H. Kitahara, A. Onoyama and S. Shima, Behavior of Magnetic Particles in Compaction, IEEE Transactions on magnetics 33 (1997) 1616-1619], is accompanied by the destruction of the texture in the pressing pattern, when the pressing force is applied perpendicular to the direction of the texture magnetic field .

Case Study 4

Texturing Nd-Fe-B Powder in a Sintering Container: Dependence of Properties on Textural Field Strength

An alloy of the "Strip casting" type, having the same composition as in Example 3, was hydrogenated and then ground in a vibration mill in toluene to an average particle size of 2.9 μm. The powders were loaded at various texture field intensities from 2 to 12 kOe, compacting to ρ _n ≈ 2.8 g / cm ³ , without vibration and with vibration at a frequency of 40 Hz, in the same molybdenum containers as in Example 3. The powders were sintered in vacuum directly in containers at a temperature of 1100 ° C for 1 h and an additional low-temperature treatment of 900 ° C + 600 ° C was carried out with a shutter speed of 0.5 h.

In FIG. Figure 2 shows the dependence of the properties of sintered magnets on the strength of the texture field N. When the texture field strength is less than 8 kOe, the density of sintered magnets prepared from powder without vibration gradually decreases.

The application of vibration at H <8 kOe contributes to a small increase in ρ. Values of B _r sharply increase in fields to 8 kOe, which at constant or decreasing density values indicates an increasing degree of texture. Apparently, while the intensity of the texture field is less than the demagnetizing field of the particles, determined by their shape, they are not magnetized to saturation and are unable to organize well-aligned chains. The applied pressure overcomes the magnetostatic repulsive forces arising between them, and the application of vibration favors the uniform packing of the powder, which helps to achieve high ρ values after sintering. A texture field of more than 8 kOe is guaranteed to overcome the demagnetizing field of each individual particle, magnetizing them to saturation and building them into ideal chains. In this case, the external pressure, providing ρ _n ≈ 2.8 g / cm ³ , is no longer able to overcome the forces of magnetostatic repulsion of the chains and is insufficient to create a uniform density distribution of the textured powder, which leads to porosity of the sintered magnets and a decrease in their density.

An example of a specific implementation 5.

Comparison of texturing of Nd-Fe-B powder according to the traditional PBP scheme and by filling it into a container placed in a magnetic field

Using an alloy of the same composition as in example 3, for comparison, PBP magnets were prepared according to the claimed method of loading the powder into an included permanent magnetic field of 12 kOe with subsequent compaction to ρ _n = 2.966 g / cm ³ and according to the scheme proposed by Sagawa , in accordance with which the powder was loaded into a sintering container with ρ _n = 2.975 g / cm ³ and then textured in a pulsed magnetic field of 46 kOe. Texturing in a pulsed field was performed by applying 5 pulses, and in each odd pulse the direction of the magnetic field vector was reversed. The powders textured in a pulsed magnetic field and according to the claimed method were jointly sintered in vacuum directly in containers at a temperature of 1100 ° C for 1 h and then an additional low-temperature treatment of 900 ° C + 600 ° C was carried out with a holding time of 0.5 h.

In FIG. 3 shows the demagnetization curves, measured along and across the texture, on magnets prepared according to the claimed and traditional method. The properties of the obtained magnets are shown in table 3.

From the presented data it is seen that the B _r value of the sample obtained by filling the powder in a magnetic field is higher than that of a sample that was textured in a pulsed magnetic field. Using the Fernengel formula [Fernengel W., Lehneret A., Katter M., Rodewald W., Wall B. Examination of the degree of alignment in sintered Nd-Fe-B magnets by measurements of the remanent polarizations // J. Magn. Magn. Mater. V. 157/158. 1996. P. 19-20]:

where B _r and B _rp are the residual induction of the magnet, measured along and across the axis of the texture, respectively, the coefficients of the degree of texture α _T were calculated, which are also shown in table 3. A high degree of texture is induced when the powder is filled by the claimed method in relatively small fields. It is 3% higher compared to the texture of a magnet textured in a pulsed magnetic field, the intensity of which is almost 4 times higher than the constant field strength used in the claimed texturing method.

Claims (3)

1. A method of producing a sintered permanent magnet from rare-earth alloys, iron and cobalt alloys, including smelting and casting of the alloy, including strip casting technology, the preparation of powders with an average particle size of 2.5-5 microns by grinding the alloy in a vibration or jet mill, loading of powders into pressing matrices or into sintering containers, texturing of powders in a constant magnetic field of 10-20 kOe, compaction of powders by vibration with a frequency of 10-50 Hz and / or compression of the powder with a piston in the direction SRI perpendicular to the applied magnetic field, to a density of 20-45% of the initial density of the cast alloy and subsequent sintering of powders, characterized in that to improve the degree of texture of the magnet powder is filled into the matrix or container for sintering, placed in an on magnetic field. 2. The method according to p. 1, characterized in that the powder textured in an electromagnet in elastic matrices is additionally textured in a pulsed magnetic field of 35 kOe with a pulse duration of 10 ms in the direction coinciding with the direction of the electromagnet field, and then pressed in a hydrostat at a pressure of 1.6-2.6 kbar, after which the press blanks are removed from the elastic matrices and sent for sintering. 3. The method according to claim 1, characterized in that the sintering containers with the powder textured in the electromagnet loaded are covered with lids, after which the powders are sintered directly in the containers.

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