JPS61143553A - Production of material for permanent magnet - Google Patents

Abstract

PURPOSE:To obtain the mateial for a permanent magnet having improved orientative properties of a magner alloy by annealing an alloy ingot mainly composed of rare earth elements, B, and Fe under specific conditions, by crush ing and pulverizing the ingot, and by subjecting the obtained alloy powder to compacting, sintering and heat treatment. CONSTITUTION:The alloy ingot mainly composed of 10-30atomic% R (where R is >=1 kind among rare earth elements contg. Y), 2-28atomic% B, and 65-82atomic% Fe is annealed at 1,000-1,150 deg.C for 0.5-50hr. The ingot is crushed and pulverized to form alloy powder, which is subjected to compacting, sintering and heat treatment to form the material for permanent magnet.

Description

Detailed Description of the Invention Field of Application The present invention relates to a method for manufacturing a sintered permanent magnet material whose main components are R (R is at least one rare earth element including Y), B, and Fe. The present invention relates to a method for producing a permanent magnet material that prevents deterioration of magnetic properties due to component segregation during ingot production and improves the orientation of a magnet alloy.

BACKGROUND ART Current typical permanent magnet materials are alnico, hard ferrite and rare earth cobalt magnets.

As the raw material situation for cobalt has become unstable in recent years, demand for alnico magnets containing 20 to 35 wt% cobalt has decreased.
Inexpensive hard ferrite, whose main component is iron oxide, has come to dominate magnet materials.

On the other hand, rare earth cobalt magnets contain 50 to 60wt of cobalt.
It is very expensive because it contains % and is not included in rare earth ores, but it is very expensive compared to other magnets.
Due to its extremely high magnetic properties, it has come to be used mainly in small, high-value-added magnetic circuits.

Therefore, the present inventor previously proposed a Fe-B-R-based permanent magnet (R is at least one rare earth element including Y) as a new high-performance permanent magnet that does not contain expensive shafts or 6 (specially (Gan Sho 57-145072). Furthermore, Fe-B
In order to improve the temperature characteristics of a permanent magnet made of an R-based magnetically anisotropic sintered body, some of the Fe was replaced with 6 to raise the Curie point of the resulting alloy and improve the temperature characteristics. We proposed a permanent magnet made of Fs Co BR magneto-optical anisotropic sintered body (Japanese Patent Application No. 166663/1982).

These permanent magnets use resource-rich light rare earth materials such as ceramics and circles as R, and 25M magnets with Fe as the main component.
It is an excellent permanent magnet that exhibits an extremely high energy product exceeding GOe.

The above novel Fe-B-R system, FeCoB
Rare earth metals as starting materials for producing R-based permanent magnets are generally produced by a pseudo reduction method or an electrolytic method, for example,
It is manufactured by the following steps.

(2) As a starting material, the rare earth metal, electrolytic iron, ferroboron alloy, or further electrolytic 6 is melted by high frequency to cast an ingot.

(2) After coarsely pulverizing the ingot using a stamp mill, the ingot is wet-pulverized using a ball mill to obtain a fine powder of 1.5 JJn to 10 AM.

■Mold with orientation in a magnetic field.

■After sintering in vacuum, let it cool.

■Aging treatment in an Ar atmosphere.

As mentioned above, this alloy powder for permanent magnets is obtained by mechanically crushing and finely crushing an ingot of the desired composition.
For example, in the case of Fs-Nd-B ingots, compositional segregation is likely to occur during solidification, resulting in a state where Fe and ceramic metal phases are precipitated, and when such an ingot is crushed and oriented in a magnetic field,
These precipitated phases hinder the orientation, and the portion of the ingot that was in contact with the mold tends to generate fine crystal grains due to the fast cooling rate, and the crystal growth direction of Fe-NdB tetragonal crystals is Since it does not coincide with the direction of easy magnetization, when the cast alloy is crushed and oriented in a magnetic field, there is a problem that the degree of orientation decreases because the powder contains a plurality of crystal grains with irregular orientation directions.

Purpose of the Invention The present invention aims to improve the orientation of a magnetic alloy by preventing deterioration of magnetic properties due to component segregation during production of an alloy ingot.
The purpose of the present invention is to provide a method for manufacturing eBR-based sintered permanent magnet materials.

Structure and Effects of the Invention ゛As a result of various studies aimed at preventing component segregation within the Fe-BRR permanent magnet alloy, the present invention has revealed that by applying an annealing treatment, component segregation can be prevented and crystal grains can be coarsened. hand,
It was discovered that this method is effective in improving the degree of orientation, magnetic properties, and mechanical properties.

That is, this invention includes: R (wherein R is at least one kind of rare earth elements including Y) 10 atomic % to 30 atomic %, B 2 atomic % to 28 atomic %,
An alloy ingot whose main component is Fe 65 atomic % to 82 atomic % is annealed at 1000° C. to 1150° C. for 0.5 to 50 hours, and then the ingot is coarsely crushed and finely crushed. After forming the alloy powder with an average particle size of 0.3 to 80ρ in a magnetic field, it is sintered in a vacuum at, for example, 900°C to 1200°C, and then heat-treated in a temperature range of 350°C to the sintering temperature. A method for producing a permanent magnet material characterized by:

The reasons for limiting the alloy powder for permanent magnets in this invention are as follows.

In addition, in this invention, the annealing treatment temperature is 1000°C ~
The reason for setting the temperature to 1150°C is that below 1000°C, the diffusion rate becomes very slow and it takes a long time to coarsen the crystal grains and eliminate segregation. This is because segregation of Fa or ceramic cannot be prevented.

In addition, if the annealing treatment time is less than 0.5 hours, the effect of coarsening the crystal grains and eliminating segregation will not be sufficiently obtained, and if the annealing treatment time exceeds 50 hours, it will be effective in preventing segregation and coarsening the crystal grains. Since mass productivity is poor, the time is set at 0.5 to 50 hours.

Generally, in the production of rare earth cobalt magnet alloys, solution treatment of ingots has been proposed (Japanese Unexamined Patent Publication No. 126944/1983), but the effect of solution treatment of rare earth cobalt magnet alloy ingots is (R; rare earth element,
The purpose of solution treatment of R2T+7 type permanent magnet ingots is to transform the unstable phase (R
After solution treatment,
Oil quenching or rapid cooling into liquid nitrogen is required.

However, unlike the rare earth cobalt magnet mentioned above, the annealing treatment of the ingot in this invention is to obtain a single phase state of the RzFII4B compound, which is a compound stable at low temperatures, and the rapid cooling after the above annealing treatment is , may be applied, but is not necessarily required.

Preferred Embodiment In the production method according to the present invention, the required amount of starting materials are blended, melted and alloyed in a vacuum or inert gas atmosphere to form an ingot, and then subjected to an annealing treatment, which is a feature of the present invention, It is best to coarsely grind it.

Coarse pulverization is performed by mechanical pulverization using a stamp mill, show crusher, etc., and further fine pulverization is performed using a jet mill, ball mill, etc. Fine pulverization is carried out by dry pulverization in an inert gas atmosphere or wet pulverization using an organic solvent such as acetone or toluene.

The average particle size of the alloy powder obtained by fine pulverization is 0.3
−~80ρ, and in order to obtain excellent magnetic properties,
Fine powders with an average particle size of 1 to 20 parts are preferred, and most preferred are fine powders with an average particle size of 2 to 10 parts.

Sintering is carried out in a vacuum of 10-2 Torr or less or in a
Sintering is performed at a temperature of 900°C to 1200°C for 0.5 to 4 hours in an inert or reducing atmosphere of at least non-oxidizing or purity of 99.9% or more, such as a pressure atmosphere of 760 Torr. preferable.

As for the aging treatment conditions after sintering in this invention, in order to suppress excessive growth of crystal grains in the magnet body and develop excellent magnetic properties, the aging treatment temperature is preferably in the range of 450°C to 700°C; The aging treatment time is preferably 5 minutes to 40 hours. The aging treatment time is closely related to the aging treatment temperature, but if it is less than 5 minutes, the aging treatment effect will be small and the magnetic properties of the obtained magnet material will vary widely, and if it exceeds 40 hours, it will take a long time for industrial purposes. Too impractical. From the viewpoint of desirable development of magnetic properties and practical aspects, the aging treatment time is preferably 30 minutes to 8 hours.

Moreover, multi-stage aging treatment of two or more stages can also be used for the aging treatment. For example, a sintered body sintered at 1060°C is subjected to an initial aging treatment at 150°C to ioooo°C for 30 minutes to 6 hours as the first stage, and then in the second and subsequent stages,
The residual magnetic flux density is reduced by performing one or more stages of aging treatment at 50°C to 150°C for 2 to 30 hours.

A magnetic material having extremely excellent magnetic properties in both coercive force and squareness of the demagnetization curve can be obtained.

In addition, instead of multi-stage aging treatment, a cooling method such as air cooling or water cooling from the aging treatment temperature of 450°C to 700°C to room temperature at a cooling rate of 0.2°C/lll1n to 20°C/min can be used. Also, it is possible to obtain a permanent magnet material having magnetic properties equivalent to those obtained by the above-mentioned aging treatment. ' Reason for limitation of alloy powder for permanent magnet The rare earth element R used in the permanent magnet material of this invention is 10
atomic% to 30 atomic% Nd, Pr, DV.

At least one of Ho, Tb, or further,
La, Ce, Sm, Gd, Er, Eu, PIIl.

Those containing at least one of Tm, Yb, and Y are preferred.

Further, one type of R is usually sufficient, but in practice, a mixture of two or more types (Mitsuhmetal, dididium, etc.) can be used for reasons such as convenience of availability.

Note that this R does not have to be a pure rare earth element, and may contain impurities that are unavoidable in production within an industrially available range.

R (at least one rare earth element including Y) is an essential element in the alloy ingot for manufacturing the new above-mentioned permanent magnet, and if it is less than 10 at%, the crystal structure is the same as α-iron. Because of the cubic crystal structure, high magnetic properties, especially high coercive force, cannot be obtained.If it exceeds 30 at%, the R-rich nonmagnetic phase increases, and the residual magnetic flux density (Sr) decreases, making it difficult to obtain excellent magnetic properties. A permanent magnet with the same characteristics cannot be obtained. Therefore,
The rare earth element is in the range of 10 atomic % to 30 atomic %.

B is an essential element in the above-mentioned new alloy ingot for permanent magnets, and when it is less than 2 atomic %, it becomes a rhombohedral structure,
A high coercive force (iHC) cannot be obtained, and if it exceeds 28 at %, the B-rich nonmagnetic phase increases and the residual magnetic flux density (B
r ) decreases, making it impossible to obtain an excellent permanent magnet. Therefore, B is in the range of 2 atomic % to 28 atomic %.

Fe is an essential element in the above-mentioned new alloy ingot for permanent magnets, and if it is less than 65 at%, the residual magnetic flux density (Br
) decreases, and if it exceeds 82 atom %, high coercive force cannot be obtained, so Fe is contained in a range of 65 atom % to 82 atom %.

In addition, in the alloy for permanent magnets according to the present invention, replacing a part of Fe with 6 can improve the temperature characteristics without impairing the magnetic properties of the obtained magnet, but the amount of Fe replaced is If it exceeds 50%, the magnetic properties will deteriorate, which is not preferable.

In the alloy powder of this invention, in order to obtain high residual magnetic flux density and high coercive force, R12.5 to 15 at%,
Preferably B66 to 14 atom % and l'' e7171 atom 82 atom %.

Moreover, the alloy ingot for permanent magnets according to the present invention has R, B,
In addition to Fe, the presence of unavoidable impurities in industrial production can be tolerated, but a portion of B can be
R12 at % or less, S at 0 at % or less, 2.0 at %
By replacing at least one of the following CLIs in a total amount of 2.0 atomic % or less, it is possible to improve the manufacturability and reduce the cost of permanent magnets.

In addition, at least one of the following additional elements is R-F3
-It is added to Fe-based or R-B-Go-FI-based permanent magnets because it is effective in improving the coercive force, etc., improving manufacturability, and reducing costs. However, addition to improve coercive force causes a decrease in residual magnetic flux density (Br), so it is desirable to add in the following range.

At 5.0 atomic % or less, Ti15 3.0 atomic % or less
．． 5 at% or less of V, 4.5 at% or less of Cr.

Mn not more than 5.0 at % B119.0 not more than 15 at %
Nb at % or less, Ta at 7.0 atomic% or less.

M6 of 5.2 atomic % or less, Wll of 5.0 atomic % or less,
0 at% or less Sb, 3.5 at% or less Ge11.5
Contains at least one of Sn at % or less, Zr at 3.3 atomic% or less, Ni at 16.0 atomic% or less, 3i at 5.0 atomic% or less, and Hf at 3.3 atomic% or less, however,
When two or more elements are contained, the maximum content is at most atomic % of the one having the maximum value among the added elements, thereby making it possible to increase the coercive force of the permanent magnet.

The crystalline phase of the alloy powder in this invention is such that the main phase is at least 50% tetragonal and at least 1% non-magnetic intermetallic compound to produce a sintered permanent magnet with excellent magnetic properties. It is essential to

Further, the permanent magnet of the present invention can be press-molded in a magnetic field to obtain a magnetically anisotropic magnet, and can be press-molded in a non-magnetic field to obtain a magnetically isotropic magnet.

The magnetically anisotropic permanent magnet material according to the present invention exhibits a residual magnetic flux density Br >10.5KG, and has a maximum energy product (
B H) max≧25MGOe, the maximum value is 40
Reach more than MG Os.

Further, the composition of the alloy ingot for permanent magnets of this invention is R12.
atomic% to 16 atomic%, 84 atomic% to 15 atomic%, Co4
In the case of 5 atomic % or less and the remainder being Fs, the obtained magnetically anisotropic permanent magnet alloy exhibits magnetic properties equivalent to those of the above magnet alloy, and the temperature coefficient of residual magnetic flux density is 0.1%/℃ or less, which is excellent. characteristics can be obtained.

In addition, when the main component of R in the alloy powder for permanent magnets of this invention is light rare earth metals accounting for 50% or more, R12.5
atomic% to 15 atomic%, B66 atomic to 14 atomic%, F.
In the case of 71 atomic % to 82 atomic %, or even Co5
When the main component is from atomic% to 45 atomic%, sintered magnets exhibit excellent magnetic properties, and especially when the light rare earth metal is ceramic, the maximum value of (B H) l1ax is 4.
Reach 0MGOs or more.

Example! A 1- alloy ingot having a composition of 77F/8B15t&l in terms of atomic percentage was obtained by high-frequency melting of the starting raw material in a gas, followed by water-cooled copper casting.

This alloy ingot was annealed at 1050° C. for 20 hours, then coarsely crushed in a show crusher to a mesh throughput of 40 or less, and further finely crushed in a ball mill.

The obtained alloy powder with an average particle size of 1 to 20 um was heated at 10 k
- After pressure molding at a pressure of 2 tons4 in a magnetic field of
A sintered body was obtained by sintering for a period of time.

Then, after aging treatment at 600° C. for 1 hour, the density and magnetic properties were measured. The results are shown in Table 1.

In addition, for comparison, a comparative magnet material (Comparison 1) was manufactured using the above manufacturing method except that the ingot was not annealed, and its density and magnetic properties were similarly measured. Table 1 shows the results. show.

In terms of atomic percentage, 79Fe 7B 0.25 Dy13.
One alloy ingot having a composition of 75 Nd was obtained by high-frequency melting of a starting material in a gas, followed by water-cooled copper casting.

This alloy ingot was annealed at 1100° C. for 1011 IJ, then coarsely crushed in a show crusher to 40 mesh through or less, and further finely crushed in a ball mill.

The obtained alloy powder with an average particle size of 1 to 20 sl was heated to 10 kO
After pressure molding at a pressure of 1.8 ton4 in a magnetic field of
℃ for 2 hours to obtain a sintered body.

Then, after aging treatment at 600°C for 2 hours, the density and magnetic properties were measured. The results are shown in Table 2.

In addition, for comparison, a comparative magnet material (Comparison 2) was manufactured using the above manufacturing method except that the ingot was not annealed, and its density and magnetic properties were similarly measured. Table 2 shows the results. show.

As is clear from the results in Tables 1 and 2 in the margin below, the permanent magnet material produced by the method of this invention has improved magnetic properties due to prevention of compositional segregation and increased density. It turns out that was obtained.

Claims (1)

[Claims] 1 An alloy ingot whose main components are 10 at% to 30 at% of R (where R is at least one kind of rare earth elements including Y), B2 at% to 28 at%, and Fe65 at% to 82 at%, After annealing at 1000°C to 1150°C for 0.5 to 50 hours, the ingot is roughly crushed and finely crushed, and the resulting alloy powder is molded and sintered, followed by heat treatment. A method for producing a characteristic permanent magnet material.