JPH01146307A - Manufacture of rare-earth permanent magnet - Google Patents

Abstract

PURPOSE:To obtain a magnet material having the magnetic characteristics superior than those of the magnet manufactured before at reduced cost of processing by a method wherein, in an extrusion processing, a degassing process is introduced before canning of the molded body which is formed in a magnetic field. CONSTITUTION:When an R-T-B (provided that R indicates one or more kinds of the rare-earth element containing Y, and T indicates a transition metal element) rare-earth magnet is manufactured, the alloy powder mainly composed of R of 28-40wt.%, B of 1.0-2.0wt.% and T of balance is compression-molded in a magnetic field, a degassing operation is conducted at the heating temperature of 1000 deg.C or below, and after a canning operation has been conducted, a hot extrusion-molding is performed at the extrusion ratio 3-20 at the temperature range of 500-1150 deg.C. For example, after the molded body, which is formed by compression-molding alloy fine powder in a magnetic field, has been filled into a pure iron pipe to be used for canning, a degassing operation is conducted by evacuation. Then, the molded body finished in canning is heated at 900 deg.C for thirty minutes, and an extrusion processing is conducted at the extrusion ratio of 11 and at the extrusion pressure of 8ton/cm<2>.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides R (R is one or more rare earth elements including Y),
The present invention relates to a method for producing rare earth permanent magnets whose main components are B and T (T is a transition metal), and particularly relates to a production method using a hot extrusion process as an alternative to powder metallurgy.

[Conventional technology]

The R-T-B rare earth permanent magnet material is R-C.

It has superior magnetic properties compared to other permanent magnet materials, and is becoming more popular as a permanent magnet. At the same time, development of methods for producing magnets with the aim of further improving performance and reducing costs is progressing.

Conventionally, rare earth permanent magnets have been produced using powder metallurgy, which involves melting in a vacuum or inert atmosphere, forming a magnet, coarsely pulverizing, finely pulverizing, forming in a magnetic field, sintering, heat treatment, and processing. Manufactured by process. In this manufacturing method, a magnet body having a maximum energy product (BH) max obtained from the RTB system - (particularly Nb-Fe-B) is 35 MGOe or more is manufactured.

Water-based rare earth permanent magnets are manufactured by the above-mentioned manufacturing process, and this process involves molding.

Particularly when molding thin-walled rings, arc-shaped molded objects, etc., it may cause uneven density of green powder in the molded object.

The disadvantage is that the molded product does not have sufficient strength, tends to have defects such as chips and cracks, and is extremely difficult to manufacture. For this reason, in the conventional method, the desired thin-walled rings and arc-shaped magnets were obtained by processing after sintering, but due to the amount of processing, etc., the yield was poor. It is expensive and undesirable.

As a solution to this problem, there is a method of manufacturing permanent magnets using a hot pressing method (Japanese Patent Application Laid-open No. 48904/1983). In the magnet manufacturing process using hot extrusion according to this document,
The method of manufacturing the ingot is by vacuum melting, coarse pulverization, fine pulverization, molding in a magnetic field, canning, and then hot extrusion processing.

When heating or extruding canned bits.

Since densification is achieved, there is no need for a densification process.

Become. Furthermore, according to this method, the extruded material.

A rod-like material that is long in the extrusion direction is obtained, and a dense extruded material that is very close to the final product is obtained.

According to this hot extrusion processing method, since extrusion processing is pressurized during extrusion, it is possible to continuously manufacture products with excellent mechanical strength even in thin wall shapes, and compared to powder metallurgy methods, it is possible to continuously manufacture products with excellent mechanical strength. It has been reported that the magnetic properties of the magnet obtained by extrusion processing are improved (improvement in Br due to improvement in the degree of orientation obtained during extrusion, and same as above for JHC due to grain refinement).

For this reason, the rare earth permanent magnet obtained by the extrusion method described above has excellent magnetic properties as well as the magnet obtained by the powder metallurgy method.

In addition, a wide range of applications are being developed in the magnet production cycle.

[Problem that the invention seeks to solve]

However, in the hot extrusion processing method according to the previous literature, when manufacturing by hot extrusion by canning the compact formed by magnetic field during the process, f , there is a gas (CINIO) adsorbed to the molded fine powder in the compact, and the extrusion process is performed with this adsorbed gas remaining, so this impure gas component (C9N, 0) significantly impairs the magnetic properties. It causes deterioration. For this reason, it has been extremely difficult to manufacture magnets with excellent characteristics. This is C,N
This is because impurity gases such as , O, etc. react with elements such as R to form carbides, oxides, etc., and these impurities significantly deteriorate magnetic properties.

In view of the above drawbacks, a technical object of the present invention is to provide a method for producing a rare earth permanent magnet in which impurity gas components are removed and magnetic properties are improved.

[Means for solving problems]

The present invention is performed within the process of an extrusion process.

This is based on the discovery that magnetic properties can be significantly improved by introducing a degassing process before canning a compact formed by magnetic field forming.

That is, according to the present invention, in R-T-B (R is one or more rare earth elements including Y, T is a transition metal), R:
28-40wt%, B: 1.0-2. .

wt%e T: bal, a molded body obtained by compression molding alloy powder with a different composition in a magnetic field is packed into a canning pipe, etc., and then heated at a temperature of 1000°C or less.

Canning is performed after degassing the molded body, pipes, etc. in an atmosphere such as a vacuum. Then, by hot extruding the canned compact at a temperature range of 500 to 1150°C and an extrusion ratio of 3 to 20, it has excellent magnetic properties compared to conventional methods, and also reduces processing costs. Magnetic materials (especially thin-walled rings, arc shapes, etc.) can be obtained.

According to the present invention, the green compact, pipes, etc. are degassed before canning.

Impure gases (C, N, -
0) is removed, and during extrusion processing, a gas component (C) that deteriorates the magnetic properties 9 mechanical strength is removed from the molded body.

N, 0) or compounds with these do not remain.

An extremely compact magnet with excellent mechanical strength can be obtained.

At this time, gas components (C, N, etc.) remaining in the molded body.

0) content is Ck3000ppm or more, N#150p
If it is more than 110,000 ppm or more than 110,000 ppm, the residual of these gas components or compounds with these gas components will cause deterioration of the magnetic properties.

It is difficult to manufacture magnets with excellent performance according to the present invention. Therefore, the content of the remaining gas component must be kept below the above value, preferably C"q200
0ppm or less, Nkl OOppm or less.

0'? By reducing the amount to 7,000 ppm or less, it becomes possible to manufacture a magnet with excellent magnetic properties ("H)ma!≧35 MGOe. In particular, the effect of +?C is extremely industrially difficult when trying to obtain a thin-walled magnet. Beneficial.

Here, the alloy powder composition used in the present invention is R:
28-40 wt%, B: 1.0-2. Owt%
+ T: 'bal is used because if a composition outside this range is used, it will not exhibit excellent magnetic properties as a rare earth permanent magnet material, and the process introduced in the present invention will not be effective. be.

Next, the degassing temperature was set to 1000°C or less.

This is because, if the temperature is higher than this, sintering of the molded body will proceed, and impurity gas components (CINIO) will remain in the molded body.

Next, the reason why the hot extrusion temperature is set in the temperature range of 500 to 1150°C is because if the hot extrusion temperature is lower than 500°C, plastic deformation is insufficient and extrusion is impossible.
Further, if the hot extrusion temperature is 1150°C or higher, there is a possibility that the unavoidable liquid phase may inhibit the hot extrusion process and the molded product may melt.

Next, the reason for setting the extrusion ratio to 3 to 20 is that when the extrusion ratio is less than 3, the orientation due to extrusion processing is improved;
And density cannot be realized.

This is because if the extrusion ratio exceeds 20, processing by normal extrusion becomes impossible.

〔Example〕

Next, nine embodiments of the present invention will be described with reference to the drawings.

<Example 1> Regarding the production of rare earth permanent magnet of R-T-B type, Nd is used as R, Fe is used as T, Nd: 26 wt%
．． 28, 30, 32.5, 35, 38, 40°42,
44, B: 1.0, Fe: When the amount of Nd is changed like bal, and Nd: 3 in wt%.
5. OI B: 0.6, 0.8, 1.0, 1.2f
1.5,1.7,2.0?2,2 v 2.5 t F
e: When the amount of B is changed like bal.

Alloys of each composition were created by vacuum high-frequency melting. The obtained ingot was coarsely ground using a disc mill to obtain a coarse powder. Next, this coarse powder is finely pulverized using a gall mill and then finely pulverized using a wet method.

A fine powder with a pulverized particle size of about 4 μm was obtained. This fine alloy powder was compression molded in a magnetic field to create a compact. After filling the obtained molded body into a pure iron pipe for canning,
The molded body and/or the mother plate were degassed by evacuating the inside of the pipe at a temperature of .degree. C. for 1 hour. After the degassing, canning is performed and the canned molded body is
Heating at 00°C for 30 minutes, the extrusion ratio was 11. Then, extrusion processing was performed at an extrusion pressure of 8 ton/cm2. The obtained magnet was heat treated at 600° C. for 1 hour and then rapidly cooled. The results of measuring the magnetic properties of the obtained magnet are shown in FIGS. 1 and 2.

As a result, the composition range used was Nd: 28 to 40 wt%.
,B:1. θ~2. It can be seen that Owtchi and Fe:ba1 are effective.

<Example 2> As a means of measuring the effectiveness of degassing, use the following method.

35, ONd-1,0B-Fe bal, (wt%
) was melted, coarsely pulverized, finely pulverized, and compression molded in a magnetic field in the same manner as in <Example 1>. A sample in which the obtained molded body was packed in a pure iron canning tube and then canned immediately without degassing.

and 25.200.400.600.800.

The sample was degassed by vacuuming the inside of the pipe for 1 hour at each temperature of 1000 and 1100°C, and the canned molded product was heated at 900°C for 30 minutes to achieve an extrusion ratio of 11 and extrusion. Pressure 8 tons/
It was extruded in crn2. 6 of the obtained magnets
The mixture was heat-treated at 00° C. for 1 hour and then rapidly cooled.

The results of measuring the magnetic properties of the obtained magnet are shown in FIG.

The results show that by introducing a degassing step at a temperature of 1000° C. or lower, the magnetic properties are improved, and a magnet that is extremely dense and has excellent magnetic properties can be obtained.

Therefore, it can be seen that a degassing temperature of 1000° C. or less is effective.

<Example 3> 35, ONd -1, OB -Fe bal (wt
%) was melted, coarsely pulverized, finely pulverized, and compression molded in a magnetic field in the same manner as in Example 1. The obtained molded body is made of pure iron for canning. After filling it in the igu, the inside of the pipe is vacuumed at a temperature of 800℃ for 1 hour.
Therefore, after degassing and canning the molded body, the canned molded body was heated to 450°, 500°, 700.900°.
．． Heating at each temperature of 1050, 1150, 1200C for 30 minutes, extrusion ratio 11 and extrusion pressure 8 ton/
It was extruded in crn2. 6 of the obtained magnets
The mixture was heat-treated at 00° C. for 1 hour and then rapidly cooled. The measurement results of the magnetic properties of the obtained magnet are shown in FIG. As a result, when the extrusion temperature is lower than 500℃, the magnetic properties also deteriorate.
Furthermore, when the extrusion temperature exceeded 1200° C., the molded product melted, making extrusion processing impossible. Therefore.

It can be seen that an extrusion temperature range of 500 to 1150°C is effective.

<Example 4> 35, ONd -1, OB -Fe bal , (w
t%) was melted, coarsely pulverized, finely pulverized, and compression molded in a magnetic field in the same manner as in Example 1. After packing the obtained molded body into a pure iron mother tube for canning, the inside of the mother tube was degassed by vacuuming for one hour at a temperature of 800°C, and after canning the molded body, The canned molded body was heated at 900 for 30 minutes, and 2.
Extrusion processing was performed at each extrusion ratio of 3, 7, 11, 15, and 20 and an extrusion pressure of 8 ton/crn2.

The obtained magnet was heat treated at 600° C. for 1 hour and then rapidly cooled.

The measurement results of the magnetic properties of the obtained magnet are shown in FIG.

As a result, when the extrusion ratio is small (3 or less), the density of the magnet is poor, the density is lower than that of magnets made with other extrusion ratios, and the magnetic properties are also lower than those of magnets made under other conditions. You can see that it is inferior in comparison.

Therefore, it can be seen that an extrusion ratio of 3 to 2 degrees is effective.

<Example 5> 35,ONd-1,0B-Fe bal (wt%)
An alloy having the following composition was melted, coarsely pulverized, finely pulverized, and compression molded in a magnetic field in the same manner as in Example 1. After filling the obtained molded body into a canning tube made of pure iron.

■ If the gas is not degassed.

■ If the inside of Noquig is degassed by vacuuming at a temperature of 800°C for 1 hour, the molded body is canned after each step, and the canned molded body is heated to 900°C.
The mixture was heated for 30 minutes at a temperature of 1, and extruded at an extrusion ratio of 11 and an extrusion pressure of 8 ton/crn2. The obtained magnet was heat treated at 600° C. for 1 hour and then rapidly cooled. Table 1 shows the measurement results of the magnetic properties of the magnets obtained under each condition (■ and ■) and the analysis results of gases (C, N, O) remaining in the magnet material. As a result, when the degassing process was not introduced, the amount of gas (C, N) analyzed in one analysis was determined.

0) is 2 to 2% compared to when the degassing process is introduced.
It can be seen that the gas adsorbed on the molded fine powder is insufficiently removed, causing deterioration of the magnetic properties.

In addition, when carrying out one test, Nb・F using Nd as R was used.
Although the e-B system has been described, it is easy to infer that similar effects can be expected for R-Fe-B system alloys when rare earth elements including Y are used.

〔Effect of the invention〕

As explained above, 9 According to the method of manufacturing rare earth permanent magnets using the hot extrusion processing method of the present invention, by introducing a degassing step before canning, it contributes to improving the magnetic properties and provides excellent magnetic properties. You can obtain magnetic materials with

[Brief explanation of the drawing]

Figure 1 shows a degassing temperature of 800℃ and an extrusion temperature of 900℃.
, at an extrusion ratio of 11, Nd: 24 to 44 (wt
%) + B: 1. O (wt%), Fe:
When the amount of Nd (wt%) is changed within the range of A of bal. A correlation diagram between each amount of Nd (wt%) and each magnet characteristic. Figure 2 shows a degassing temperature of 800℃ and an extrusion temperature of 900℃.
, at an extrusion ratio of 11, Nd: 35.0 (w
t%) = B: 0.6 to 2.5 (wt%) g
Fe: When the amount of B (wt%) is changed within the composition range of baL. Correlation diagram between each amount of B (wt%) and each magnet characteristic. Figure 3 shows 35. ONd-1, OB-Fe bal
, (wt%), extrusion temperature 900°C
, a correlation diagram between each estimated gas temperature and each magnet characteristic when there is no degassing step and when the degassing temperature is varied within the range of 25 to 1100° C. at an extrusion ratio of 11. Figure 4 shows 35. ONd-1, OB-Fe bal
, (wt%), degassing temperature 800°C,
At an extrusion ratio of 11, the extrusion temperature is 450-12
A correlation diagram between each extrusion temperature and each magnet characteristic when changing the temperature within the range of 00°C. Figure 5 shows 35. ONd-1, OB-Fe ba
l, (wt%), degassing temperature 800°C
, at an extrusion temperature of 900°C, an extrusion ratio of 2 to 2
FIG. 3 is a correlation diagram between each extrusion ratio and each magnet characteristic when the extrusion ratio is changed within a range of 0. Fig. 1 NdN (Sword L%) Fig. 2 81 (4%) Fig. 3 ゛!!My brother's strength (0C) Fig. 4 Extrusion temperature ('C)

Claims (1)

[Claims] 1. In the method for manufacturing R-T-B (here, R represents one or more rare earth elements including Y, and T represents a transition metal element) system rare earth magnet by extrusion processing, R: 28 to 4
0wt%, B: 1.0 to 2.0wt%, T: bal. An alloy powder whose main component is compression molded in a magnetic field,
1. A method for producing a rare earth permanent magnet, which comprises degassing and canning at a heating temperature of 0° C. or lower, followed by hot extrusion molding at a temperature of 500 to 1150° C. and an extrusion ratio of 3 to 20.