JPH0418707A - Manufacture of permanent magnet - Google Patents

Abstract

PURPOSE:To obtain a highly efficient permanent magnet at low cost by a method wherein a cast ingot of the alloy fundamentally composed of R, Fe, B and Cu is treated at a specific temperature, and then a heat treatment is conducted thereon. CONSTITUTION:An alloy, containing R (provided that when R has Nd or Pr as an essential element and it is formed as R=(PrxNd1-x)R'1z, R' contains Y and one or more kinds of rare-earth element in the form of 1>=z>=0.9), Fe, B and Cu, is melted using an induction heating furnace in an argon atmosphere, and it is cast. At this time, rare-earth, iron and copper of 99.9% purity are used as raw material, feroboron is used as boron. Then, this cast ingot is hot- worked at the temperature of 500 deg.C or higher, and then a heat treatment is conducted at the temperature of T2 to 800 deg.C (T2=490-40x). Also, after performance of hot-working, a heat treatment is conducted at 800 to 1100 deg.C, and then a heat treatment is conducted at the temperature of T2 to 800 deg.C (T2=490-40x) for the purpose of accomplishment of high coercive force and high efficiency.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a permanent magnet having magnetic anisotropy due to mechanical orientation, particularly a rare earth element (including Y) + Fe
, B as a basic raw material component.

[Prior art] Permanent magnets are one of the important electrical and electronic materials used in a wide range of fields, from various household electrical appliances to peripheral terminal equipment for large computers, and are becoming more and more compact in recent years. With the demand for higher efficiency, permanent magnets are also required to have increasingly higher performance.

A permanent magnet is a material that generates a magnetic field without supplying electrical energy from the outside, and one that has a large coercive force and a high residual magnetic flux density is suitable.

Typical permanent magnets currently in use are alnico cast magnets, ferrite magnets, and rare earth-transition metal magnets, especially rare earth-transition metal magnets.
Co-based permanent magnets and R-FeB-based permanent magnets have been extensively researched and developed as permanent magnets with extremely high coercive force and energy product.

Conventionally, there are the following methods for manufacturing these R-Fe-B-based high-performance anisotropic permanent magnets.

(1) First, JP-A-59-46008, M, S
Agawa.

S., Fujimura, N., Togawa, I.
mamoto and Y, Hatsu-ura; J,
Appl, Phys4o1.55(8), 15 Mar
ch 1984. p2083 etc. have an atomic percentage of 8~
A permanent magnet characterized by being a magnetically anisotropic sintered body consisting of 30% R (where R is at least one rare earth element including Y), 2 to 28% B, and the balance Fe is produced using a powder metallurgy method. It is disclosed that it is manufactured by sintering based on.

In this sintering method, an alloy ingot is produced by melting and casting, and then pulverized to obtain magnetic powder with an appropriate particle size (several μm).

The magnetic powder is kneaded with a binder, which is a molding aid, and press-molded in a magnetic field to complete a molded product. The compact is sintered in argon at a temperature of around 1100° C. for 1 hour and then rapidly cooled to room temperature.

After sintering, the permanent magnet is heat-treated at a temperature of around 600°C to further improve its coercive force.

Regarding the heat treatment of this sintered magnet, Japanese Patent Application Laid-Open No. 61-2
The effects of multi-stage heat treatment are disclosed in Japanese Patent Laid-Open No. 17540, Japanese Patent Application Laid-open No. 165305/1983, and the like.

(2) JP-A-59-211549 and R1ν1. L
ee; Appl.

Phys, Lett, Vol, 46(8), 15 A
pril 1985. P790 discloses an R-Fe-B magnet in which fine pieces of melt-spun alloy ribbon with a very fine crystalline magnetic phase are bonded together with a resin.

This permanent magnet is manufactured by making a quenched thin piece with a thickness of about 30 μm using a quenched ribbon manufacturing apparatus used for manufacturing an amorphous alloy, and then kneading the thin piece with a resin and press-molding it.

(3) JP-A-60-100402, R, W, Le
e; Appl.

Phys, Lett, Vol, 46(8), 15 Ap
ril 1985. According to p790, the quenched flakes used in the method (2) above are subjected to a method called a two-step hot pressing method in a vacuum or an inert atmosphere to obtain a dense and anisotropic R-Fe-B magnet. is disclosed.

(4) Japanese Patent Application Laid-Open No. 62-276803 states that R (where R is at least one rare earth element including Y) 8 to
30 atom%, B2 to 28 atom%, Co50 atom% or less,
After melting and casting an alloy consisting of 115 at. A rare earth-iron permanent magnet is disclosed in which the cast alloy is magnetically anisotropic by orienting its axis in a specific direction.

[Problems to be Solved by the Invention] The conventional methods for manufacturing R-Fe-B permanent magnets (1) to (4) above have the following drawbacks.

The manufacturing method for permanent magnets in (1) requires that the alloy be made into powder, but R-Fe-B alloys are highly active towards oxygen, so if they are made into powder, they will oxidize even more violently. Therefore, the oxygen temperature in the sintered body inevitably becomes high.

Also, when compacting the powder, a compacting aid such as zinc stearate must be used, which is removed beforehand during the sintering process. This carbon remains in the form of carbon, which is undesirable because it significantly reduces the magnetic performance of the R-Fe-B magnet.

The molded body after press molding with the addition of a molding aid is called a green body, which is extremely brittle and difficult to handle.

Therefore, a major drawback is that it takes a considerable amount of effort to arrange them neatly in the sintering furnace.

Because of these drawbacks, -R-Fe-B in terms of boat fishing.
Not only does the production of sintered magnets of this type require expensive equipment, but the production method has poor production efficiency, resulting in an increase in the production cost of the magnets. Therefore, it is not possible to take advantage of the advantages of R-Fe-B magnets, which have relatively low raw material costs.

Next, the permanent magnet manufacturing methods (2) and (3) use a vacuum melt spinning device, but this device currently has very low productivity and is expensive.

The permanent magnet (2) is isotropic in principle, so it has a low energy product, and the squareness of the hysteresis loop is also poor.
It is disadvantageous both in terms of temperature characteristics and in terms of use.

The method (3) for manufacturing permanent magnets is a unique method of using hot press in two stages, but it cannot be denied that it is inefficient when considering actual mass production.

Furthermore, in this method, at high temperatures, for example, 80° C. or higher, the crystal grains become significantly coarsened, resulting in an extremely low coercive force iHc, making it impossible to produce a practical permanent magnet.

Method (4) for manufacturing permanent magnets does not involve a powder process and only requires one step of hot pressing, so the manufacturing process is the simplest, but in terms of performance it is There was a problem that it was slightly inferior.

The present invention is intended to solve the above-mentioned drawbacks of the prior art, particularly the drawback (4) in terms of performance of permanent magnets, and its purpose is to provide a high-performance, low-cost manufacturing method for permanent magnets. It's about doing.

[Means for Solving the Problems] The method for manufacturing a permanent magnet of the present invention is characterized in that R (where R is essentially Nd or Pr, R= (P r x N d +
-,X) -R' +-z, R' is one or more rare earth elements including Y, and 1≧z≧0.9
It is. ) + Fe, B, Cu as basic raw material components,
The alloy as the basic component is melted and cast, then the cast ingot is hot worked at a temperature of 500°C or higher, and then T2~
It is characterized by heat treatment at a temperature of 8008C (T 2 = 490-40x).

In addition, in order to further increase coercive force and improve performance, heat treatment at 800-1100℃ after hot working is required.
It is characterized by heat treatment at a temperature of 00°C (T 2 = 490 40x).

Next, examples of the present invention will be described.

[Example] [Example 1] A process diagram of the manufacturing method according to the present invention is shown in FIG.

According to this process, using an induction heating furnace in an argon atmosphere, Pr+5Nd25Fets5B5Cu+I! An alloy with the following composition was melted and blow-cast. At this time, rare earths,
The iron and copper raw materials used were those with a purity of 99.9%, and the boron used was ferroboron.

Next, this cast ingot was placed in an argon atmosphere for 10
At 00'C, hot pressing was carried out to a working degree of 80%. The press pressure at this time is 0.2 to 0.9 ton/am
2, and the strain rate was 10"3 to 10-'/sec.

Further, during this hot working, the axis of easy magnetization of the crystal was oriented parallel to the direction in which the alloy was pressed.

After that, heat treatment was performed at 1000°C for 24 hours,
After being heat treated at 515°C for 4 hours, the pieces were cut and polished, and their magnetic properties were measured.

The magnetic properties and other characteristic values of this magnet are compared as a comparison example without heat treatment at 515°C, (1) sintered magnet (Nd+5Fe77Be) and (3) permanent magnet (Nd+3Fes2) in the conventional method described above. .sBa,a)
Table 1 shows the values for .

All magnetic properties are B- at a maximum applied magnetic field of 25 kOe.
Measured using No. 11 tracer.

As shown in Table 1, the magnet of the present invention has improved coercive force and maximum energy product compared to the case without heat treatment at 515°C. It is clear that the magnetic properties are not inferior to those of magnets, and the magnetization is superior.

The permanent magnet of the present invention is different from the conventional sintered magnet of (1) by 0. The C content and porosity are different, and the conventional (2)
It has a different crystal grain size from permanent magnets and has excellent magnetization.

Table 1 Comparative Example 1: No heat treatment at 515°C Comparative Example 2: Conventional method (1) magnet Comparative Example 3: Conventional method (3) magnet [Example 2] Same as Example 1, According to the manufacturing process shown in the figure, using an induction heating furnace in an argon atmosphere, Nd+5Fe79
．． Melting an alloy with the composition sBa, tC+, b+, a,
It was cast in Kei.

At this time, rare earth, iron, and copper raw materials with a purity of 99.9% were used as in Example 1, and boron was ferroboron.

For blowing, put this cast ingot into an iron capsule,
Degassed and sealed. This was hot-rolled in air at 950° C. and a working degree of 30% four times to give a final working degree of 76%.

Sample 2a cut out from the rolled ingot was not subjected to heat treatment, and sample 2b was
Heat treatment was performed at 0°C for 5 hours, and sample 2C was heat treated at 950°C for 10 hours and 550°C for 2 hours.

Table 2 shows the magnetic properties of the three types of samples.

Table 2 It is clear that the extremely low temperature heat treatment shown in Table 2 improves the magnetic properties, particularly the coercive force and the maximum energy product. Furthermore, it can be seen that the combination of high and low temperature heat treatments further improves the magnetic properties.

[Example 3] Alloy with composition Pr+7Feve, 5BsCu+, s (
Rimple 3a) and Pr+ +Nd5Dy+, eFet
e, 5Bs2Cu+[+ alloy (Ripple 3b
) and Pr5Nd++Fe77BsCu+ 3Ga[1,
An alloy with the composition v (Linfur 3c) and Ce[1,e
An alloy having a composition of Nd+eFes9CoeBs, 5Cue, 7 ('7:/7'le 3d) was melted and cast in the same manner as in Examples 1 and z to obtain a cast ingot.

Next, this cast ingot is placed in an iron capsule,
Sealed. This was hot-rolled four times in air at 950° C. and a working degree of 28%, so that the final working degree was 73%.

After this, the rolled ingot was heated from 350°C to 90°C.
Heat treatment was performed for 4 hours at various temperatures up to 0° C., and the coercive force iHc was measured. The results are shown in FIG. In addition,
The coercive force without heat treatment is 8.8 kOe (3
a), 10.0kOe (3b), 7.4kOe (3c
), 6.8 kOe (3d).

In addition, after heat treatment at 950°C for 4 hours on Linf 0ru 3a, heat treatment was performed at various temperatures from 350°C to 900°C.
A heat treatment was performed for a time and the coercive force iHc was measured.

This result (3a-2) is also shown in FIG.

From FIG. 1, it is clear that heat treatment at 12 to 800° C. is effective in improving coercive force.

From the above examples, R (where R requires Nd or Pr, R" (P r x N d 1-X)
When expressed as 2R1-z, R' is one or more rare earth elements including Y, and 1≧z≧0.9. )F
Permanent magnets whose basic raw materials are e, B, and Cu are: 50
It is made anisotropic by hot working at 0℃ or higher, and has a T2 to 800
It is clear that the heat treatment at °C (T 2 = 490-40x) shows a high coercive force, and the highest (BH)max exceeds 308 GOe.

[Effects of the Invention] As described above, the method for manufacturing a permanent magnet of the present invention has the following effects.

(1) The c-axis orientation rate can be increased, and the residual magnetic flux density B
By making the crystal grains finer, the coercive force 1 [(c) could be increased, and the maximum energy product (BH) max could be significantly improved.

(2) The cost is low because the manufacturing process is simple.

(3) The degree of 02 immersion in the magnet is low.

(4) Compared to conventional sintering methods, processing man-hours and production investment can be significantly reduced.

(5) Compared to the conventional method of producing magnets using melt spinning, it is possible to produce magnets with high performance and at low cost.

(6) Magnetic properties, especially coercive force, can be improved compared to conventional hot-worked magnets.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between heat treatment temperature and coercive force. that's all

Claims (2)

[Claims] (1) R (However, R requires Nd or Pr, and R
=(Pr_xNd_1_-_x)_zR'_1_-_z
When expressed as, R' is one or more rare earth elements including Y, and 1≧z≧0.9. ), Fe, B, and Cu are the basic raw material components, and the alloy containing the basic components is melted and cast, and then the cast ingot is hot worked at a temperature of 500℃ or higher, and then T_2 to 800℃ (T_2=490℃). -40x
) A method for manufacturing a permanent magnet, characterized by heat treatment at a temperature of (2) The method for manufacturing a permanent magnet according to claim 1, characterized in that after hot working, heat treatment is performed at a temperature of 800 to 1100°C, and then heat treatment is performed at a temperature of T_2 to 800°C (T_2 = 490-40x).