JPS6357722A - Production of permanent magnet alloy - Google Patents

Abstract

PURPOSE:To lower the residual Ca content and to improve the magnetic characteristics by adding a reducing agent such as metallic Ca and a flux to Nd2O3, Fe and B and reducing the Nd2O3 under prescribed conditions. CONSTITUTION:Metallic Ca and/or CaH2 as a reducing agent and CaCl2, NaCl or KCl as a flux are added to Nd2O3, Fe and B. These starting materials are melted by heating to 1,000-1,300 deg.C in an atmosphere of a nonoxidizing gas to reduce the Nd2O3 and to obtain an Nd-B-Fe alloy consisting of 25-50wt% Nd, 0.3-5wt% B and the balance Fe.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a manufacturing method for manufacturing a neodymium-boron-iron alloy for permanent magnets at low cost.

[Prior art] The manufacturing method for rare earth-boron-iron permanent magnets, which are new high-performance permanent magnets, involves melting, melting, and
Shatter, 1! A manufacturing method comprising in-field molding and sintering has been disclosed (Japanese Patent Laid-Open No. 59-215460).

Recently, there has been a so-called reduction diffusion method as an alternative to the dissolution method. This is rare earth oxide powder.

Add metallic calcium or calcium hydride to a mixed powder of iron powder, boron-iron alloy powder, and cobalt powder, and add 2 to 4 times (by weight) the chemically necessary amount of calcium hydride to reduce the rare earth oxide powder.
The reaction product was mixed and heated to 900 to 1200°C in an inert gas atmosphere, and the resulting reaction product was poured into water to form a reaction U [alloy powder for rare earth-boron iron-based permanent magnet alloy to remove the product]. A manufacturing method for
4).

In addition, it is disclosed that the viscosity of molten metal is lowered by using flux in the reduction diffusion method.
No. 346).

Problems to be Solved by the Invention F However, the conventional melting method uses expensive rare earth metals, resulting in high raw material costs.

Furthermore, in the so-called reduction-diffusion method according to the conventional method, a long period of water washing is required to remove calcium oxide which is a by-product after the reaction. Rare earths containing a lot of iron - boron -
Iron-based powders undergo severe oxidation during this water washing process, resulting in a high oxygen content in the raw material powder subjected to IJ, making it difficult to stably maintain good magnetic properties.

At the same time, it is extremely difficult to completely remove calcium oxide by washing with water, and the remaining calcium oxide inhibits sinterability in the sintering process of producing permanent magnets, resulting in a decrease in magnetic properties.

Further, even in the conventional reduction diffusion method using flux, the amount of residual calcium could not be reduced to an extent that would allow magnetic properties.

The object of the present invention is to solve these problems of the prior art and provide an alloy for neodymium-n-iron permanent magnets that is inexpensive and has excellent magnetic properties.

[Means for Solving the Problems] The present invention adds metallic calcium, calcium hydride, or a mixture thereof as a reducing agent to neodymium oxide, iron, boron (or boron-iron alloy), and further adds calcium chloride or chloride as a flux. 1.) Add at least one of J rum or potassium chloride, and place these raw materials in an inert gas atmosphere or)! Neodymium oxide is reduced by heating and melting at 1000 to 1350°C in an original gas atmosphere or under substantially vacuum conditions, and the neodymium oxide is reduced to 25% by weight to 50% by weight. Ovt% neodymium, 0.3wt%~5. This is a method for producing an alloy for a permanent magnet, which is characterized in that a neodymium-Ii1 wire-iron alloy is obtained which consists of Owt% boron and the balance substantially iron.

However, neodymium oxide is used as the rare earth raw material, and the composition after reduction is 25. Owt%~50. OWE%
Neodymium, 0.3wt%~5. Iron and boron (or boron-iron alloy) are added so that Owt% boron and the balance is iron, and further a reducing agent of metallic calcium or calcium hydride or a mixture thereof and a flux of calcium chloride or sodium chloride or At least one kind of potassium chloride is added, and these raw materials are heated under conditions of an inert gas atmosphere, a reducing gas atmosphere, or a substantial vacuum.
The method is to obtain a neodymium-boron-iron alloy having the above composition by heating at 170° C. to 000° C. to 1,350° C.

[Function] Neodymium liquefaction begins to be reduced by the reducing agent at around 800°C during the heating process, and is completely reduced at 1000 to 1350°C. The amount of reducing agent used is preferably 1.0 times (weight ratio) or more than the stoichiometric amount necessary for reduction in order to more reliably carry out reduction.

However, the use of a large amount of reducing agent is undesirable because it increases the manufacturing cost of the alloy and at the same time increases the amount of residual calcium in the produced alloy. Therefore, the upper limit of ω of a practical reducing agent is 2.0 times (weight ratio). Table 1 shows the reducing agent (times [weight ratio])
The relationship between the residual calcium in the resulting alloy and the magnetic properties when this alloy is used as a permanent magnet is shown.

The reduced neodymium is alloyed with iron and boron (or boron-iron alloy). During this process, calcium oxide is produced as a by-product, forming slag.

Calcium oxide has a high melting point of approximately 2570°C, so
Separation of the slag from the alloy is difficult at temperatures between 0°C and 1350°C.

The first aspect of the present invention is to add at least one of calcium chloride, sodium chloride, or potassium chloride as a flux to lower the melting point of the slag and facilitate separation of the slag from the alloy. The melting point of calcium chloride is about 770°C, the melting point of sodium chloride is about 800°C,
The melting point of potassium chloride is about 780°C, and by adding these fluxes, the alloy having the above composition and slag can be separated well at temperatures of 1000°C or higher. This will be explained in more detail later. The amount of flux added is desirably 0.03 times or more and less than 0.5 times (molar ratio) the stoichiometric production capacity of calcium oxide produced by reduction. If the amount of flux added is less than 0.03 times (molar ratio), the melting point of the slag will not be lowered, and the separation of the alloy and the slag will be insufficient. Table 2 shows the relationship between the amount of flux added (molar ratio) and the state of separation of base metal and slag.

(Hereinafter, blank space) When the ratio is 0.5 times (molar ratio) or more, the ratio of flux to the raw material (particularly the volume ratio) increases, and the efficiency of alloy production deteriorates. At the same time, the use of a large amount of flux is undesirable because it increases the manufacturing cost of the alloy.

The above separation effect can be obtained by adding one of calcium chloride, thorium chloride, and potassium chloride as a flux. Further, by adding two or more of these fluxes in combination, a separation effect as good as or better than that obtained by adding them alone can be obtained.

The second point of the present invention is that the composition of neodymium oxide after being reduced is 25%. Owt% to 50.0wt% neodymium.

0.3wt%~5. Weigh out neodymium oxide, iron, and boron (or boron-iron alloy) so that the balance is 0% boron and the balance is iron, add the above-mentioned reducing agent and flux, and heat and melt at +000 to 1350°C. The purpose is to separate the alloy and slag.

In this case, there is a close relationship between the above composition and the heating temperature of 1000 to 1350°C. The reason why the composition of the alloy is limited to the above composition in the present invention is that excellent magnetic properties as a permanent magnet can be obtained only at the above composition. The reason for limiting the composition of each element will be described later. That is, the feature of the present invention is to separate and recover an alloy having the same composition as that of a permanent magnet. In order to effectively separate the alloy and slag, it is first necessary to lower the melting point of the slag to turn the slag into a molten body, and for this purpose, the addition of flux as described above is effective.

At the same time, it is an essential and sufficient condition that the neodymium-boron-iron alloy produced becomes a melt. Only when these two conditions are met can the alloy and slag be separated well. According to research conducted by the inventors, an alloy having the above composition does not become a melt at a temperature below 1000° C., and therefore the alloy and slag do not separate. At a temperature of 1000° C. or higher, the alloy having the above composition becomes a melt, and as a result, the alloy and the slag separate. Therefore, a heating temperature of 1000° C. or higher is required. Table 3 shows the relationship between heating temperature and alloy-slag separation status.

For more reliable separation, a heating temperature of 1050° C. or higher is preferable. On the other hand, if the heating temperature is too high, impurities from the container into which the raw materials are inserted will increase. Furthermore, since a large amount of energy is consumed, it is not preferable from an economic point of view. Therefore, there is an upper limit to the heating temperature. The inventors conducted experiments using containers made of various materials as described below. As a result, it was found that heating temperatures higher than 1350° C. for any material of the container resulted in a large amount of impurities coming from the container, which adversely affected the magnetic properties of the obtained alloy. Table 4 does not show an example of heating temperature, impurity m, 'fIi gas characteristics when a tantalum container is used.

(Left below) Therefore, the heating temperature needs to be 1350° C. or lower. From the above results, the heating temperature is preferably 1000 to 1350°C, preferably 1050 to 1350°C. Heating time is 1
0 minutes or more is sufficient. Separation becomes more reliable if the time is 30 minutes or more.

On the other hand, the melting points of slags of various compositions produced under the conditions of the present invention are less than 1000°C. Therefore, 1000-135
At a heating temperature of 0 DEG C., the slag forms a melt, so that the alloy with a higher specific gravity separates to the bottom of the container and the slag with a lower specific gravity to the top of the alloy.

It is not impossible to separate the alloy and slag at heating temperatures below 1000° C. by applying the method of the invention. As is well known, the eutectic m degree of the neodymium-iron binary system is about 640°C. Therefore, the composition of the alloy after reduction is a neodymium-iron binary eutectic composition (75 wt% neodymium, 2
The addition ratio of neodymium oxide and iron (or boron-iron alloy) may be selected so as to be close to 5 wt% iron. By making the composition of the alloy contain more neodymium than the composition shown in the present invention, the alloy and slag are separated at a heating temperature of 100° C. (specifically, 700 to 950° C.). However, there are two major drawbacks in this case. One is that since the neodymium content is high in composition, the amount of residual solid solution calcium derived from the reducing agent in the separated alloy is inevitably large.

Another problem is that the composition of the obtained alloy deviates significantly from the composition for a permanent magnet, and in order to obtain an alloy for a permanent magnet, the composition must be adjusted by remelting.

These drawbacks have a large impact on the magnetic properties of permanent magnets or on manufacturing costs.

In other words, in the method for producing an alloy according to the present invention, the composition of the obtained alloy is the same as that of the permanent magnet, and the powder metallurgy process consists of directly pulverizing this into powder, and molding, sintering, and heat treating this powder. Since it can be made into a permanent magnet using a conventional method, manufacturing costs are reduced. At the same time, the alloy obtained by the present invention contains far less neodymium than the eutectic composition of neodymium-iron, and therefore the loss of residual solid solution calcium in the alloy is extremely small, which has no adverse effect on magnetic properties. cannot be seen. For the same reason, the amount of oxygen in the alloy is also lower than in alloys with compositions near the eutectic composition. The above are the characteristics of the present invention, and by the manufacturing method of the present invention, an alloy for neodymium-boron-iron permanent magnets having excellent magnetic properties can be manufactured at low cost.

Next, various raw materials used in the method for producing an alloy for permanent magnets of the present invention will be explained. A commercially available neodymium oxide with a particle size of -100 mesh is used. H! It is desirable that the degree is 95W (% (Nd content in total rare earth elements) or more. Iron can basically be used even in lump form. However, it is difficult to alloy it with the reduced neodymium element. It is advantageous to be in powder form in order to
It is desirable to use one with a -32111 esh culm. The purity may be comparable to that of commercially available pure iron. Boron is 110 mesh
Use commercially available pure boron. This may be powdered and added.

In some cases, commercially available nM may also be used. In this case, an additional amount of reducing agent necessary to reduce the added 11512 must be added.

The boron content of the alloy produced by the manufacturing method of the present invention is 0.3w
t%~5. The amount is as small as Owt%. Therefore, the proportion of calcium oxide produced by using li1 acid in the slag component is extremely small, and under the conditions of the production method of the present invention, it does not adversely affect the separation of the alloy and slag. Furthermore, from the point of view of economy, it is advantageous to use a commercially available boron-iron alloy instead of pure boron or fit acid.

Basically, it can be used even if it is in the form of a block. However, for the same reason as in the case of iron, it is desirable to use a 132 mesh powder.

Commercially available metallic calcium and calcium hydride are used as reducing agents. The shape is not particularly limited in view of its intended use, and may be powder or granules of about 120 mesh. It is desirable that the purity is 99% or more.

Flux is commercially available calcium chloride, sodium chloride,
Use potassium chloride. Before use, it is preferable to ignite them in advance to make them anhydrous.

Next, a container used in the method for producing an alloy for permanent magnets of the present invention will be explained. As the container in which the raw materials are charged and reacted, those made of iron or stainless steel can be used. In order to minimize the reaction between the molten alloy and these containers, it is effective to coat the inner walls of the containers with, for example, boron nitride.

Moreover, containers made of tungsten or tantalum are preferable because they have excellent corrosion resistance against molten alloys containing neodymium. Furthermore, containers made of ceramics, such as boron nitride or aluminum nitride, are suitable for this purpose because they have little reaction with the molten alloy.

The various raw materials of the present invention are placed on a predetermined weighing scale, mixed in, for example, a type mixer, and the resulting mixture is charged into a container as described above and heated and melted to form an alloy and slag. can be separated.

The alloy is recovered by tilting the container and pouring it into a separately prepared ingot case. It is also possible to collect the alloy by providing a tap hole in the bottom of the container and listening to the tap hole. If a ceramic container is used that has little reaction with the molten alloy, the alloy and slag will be separated by 1 liter.
After II, the entire container is cooled to room temperature, and the alloy in the container can be recovered.

After R, the reason for limiting the components of the neodymium-boron-iron permanent magnet alloy to which the present invention is applied will be explained.

Neodymium is 2s, owt% to 50,0wt%.

If it is less than 25.0 wt%, sufficient coercive force cannot be obtained, and 50.
If it exceeds 0 wt%, the residual magnetic flux density will decrease. Figure 1 shows the results of an experimental example of the relationship between neodymium content and magnetic properties. Boron is 0.03wt%~5. Owt%.

If it is less than 0.3 wt%, sufficient residual magnetic flux density and coercive force cannot be obtained, and the Curie point TO is also low. If it exceeds 5.0 wt%, the residual magnetic flux density will decrease. Figure 2 shows the results of an experimental example of the relationship between boron content and magnetic properties.

Examples according to the present invention will be shown below to further clarify its effects.

[Example] (Example 1) Neodymium oxide powder 210. Og, -10mesh
granular metallic calcium 93.8 (1 (1.25 times [weight ratio]), -32 mesh particle size iron powder 288.1++, -32 mesh particle size boron-iron alloy powder (20 ,4wt%(ill, balance iron)
31.9g chloride power) Lt Si powder 41.5 (1 (0.2 times the stoichiometric production amount of calcium oxide [molar ratio]
) and mix them in a ■ type mixer to make a total of 665
．． A 31;l base material was prepared.

This base material was placed in a stainless steel container and heated at 1250°C x IH in an argon gas atmosphere.

After the alloy and slag were separated, the container was tilted and the alloy was poured into the ingot case. This resulted in an alloy of 483.0 mm. Analysis of the composition of the alloy revealed that it was 35.9wt.
% neodymium, 1.29wt% boron.

0.02wt% calcium, balance iron. Oxygenation was 50 ppm. This alloy was coarsely pulverized, and the coarse powder was further pulverized using a jet mill to obtain a fine powder with an average particle size of 3.0 μm. Next, this pulverization was carried out using an orienting magnetic field of 10 kOe and a molding pressure of 2 tO.
The molded body was molded under the conditions of n101+12 and 1q was sintered under the conditions of 1090°C x 11-() in an argon gas atmosphere.Finally, the sintered body was heat treated under the conditions of 620°C x 1H. When the magnetic properties of the sample were measured, the residual magnetic flux density was 4πl r = 12.0 KG, and the coercive force was IHC.
= 11.4 KOe, maximum energy product (BH) m = 34
．． A value of 4M-G-Oe was obtained. Oxygenation of the sample is 44
50 ppm, and the amount of calcium was 0.02 wt%.

(Example 2) Neodymium oxide powder 150.5g, -10mesh
Granular metallic calcium 107,5Q (2.0 times the stoichiometric requirement [gravitational ratio]), -32mesh
151.9 g of iron powder with a particle size of -32IIlesh, boron-iron alloy powder with a particle size of -32IIlesh (20.4 wt% boron, residual pig iron)
19.1 (l Calcium chloride powder 7.4 () O, OS times the stoichiometric production amount of acid oxidized calcilla [molar ratio]
) and mix them in a ■ type mixer to make a total of 43G.
, 4Q base material was prepared.

This base material was placed in a stainless steel container and heated at 1000° C. for 2 hours in a hydrogen gas atmosphere. After the alloy and slag were separated, the container was tilted and the alloy was poured into the ingot case. As a result, an alloy of 293.8 () was obtained. Analysis of the composition of the alloy revealed that it contained 42.6 wt% neodymium and 1.29 wt% boron.

It contained 0.03 wt% calcium and the balance iron. Oxygenation′
was 65 ppm. This alloy was made into a permanent magnet under the same conditions as in Example 1, and its magnetic properties were measured; the residual magnetic flux density was 4πl r = 11.5 KG, and the coercive force tl-1
c = 14.2KOe, maximum energy product (BH) n+
A value of =31.0 M-G-Oe was obtained. The oxygen of the sample is 4900pi+m, and the calcium m is 0.03w.
It was t%.

(Example 3) 149.3 g of neodymium oxide powder, 95.2 fJ of powdered calcium hydride (1.7 times the stoichiometric required amount [weight ratio]), 266 iron powder with a particle size of -32 mesh
．． 4(], -10mesh particle size pure boron 5]0
, weighed 31.1 o of sodium chloride powder (0.4 times the stoichiometric production amount of calcium M chloride [mole ratio]),
These were mixed in a type 2 mixer to prepare a base material having a total of 547.6 CI.

This base material was placed in a container made of boron nitride, and heated at 1350° C. x iH in an argon gas atmosphere. After the alloy and slag were separated, the container was tilted and the alloy was poured into the ingot case. This gave alloy 386,70. Analysis of the composition of the alloy revealed that it contained 31.6 wt% neodymium and 1.39 wt% boron.

It contained 0.01 wt% calcium and the balance was iron. The amount of oxygen was 37 ppm. This alloy was made into a permanent magnet under the same conditions as in Example 1, and its magnetic properties were measured. Residual magnetic flux density 4π1r = 12.8 KG, coercive force IHC = 7.
5KOe, maximum energy v4 (13H) m=38.4
A value of MG-oe was obtained. The amount of oxygen in the sample is 380
0 ppm, and the amount of calcium was 0.01 wt%.

(Example 4) Neodymium oxide powder 91.0 (), powdered calcium hydride 34.Ig (1.0 times the stoichiometric requirement [weight ratio]), -32mesh particle size iron powder 120.Og
Weighed 2.0 g of pure boron with a particle size of -10 mesh and potassium chloride powder s, og (0.1 times the stoichiometric production amount of calcium oxide [molar ratio 1)], and mixed them in a V-type mixer. A total of 253.1 g of base material was prepared.

This base material was placed in a tantalum container and heated at 1150° C. for 4 hours under substantially vacuum conditions. After the alloy and slag were separated, the container was tilted and the alloy was poured into the ingot case. This resulted in 195.3g of alloy (
It was 9. Analysis of the composition of the alloy revealed that it contained 38.9 wt% neodymium and 0.97 wt% boron.

It contained 0.03 wt% calcium and the balance iron. The amount of oxygen was f33 ppm. This alloy was made into a permanent magnet under the same conditions as in Example 1, and its magnetic properties were measured: residual magnetic flux density 4πI r =11.7KG, coercive force x li
c −12,4K Oe, maximum energy product (BH
) m=32.7 MG·Oe was obtained. The amount of oxygen in the sample is 4800 ppm, and the amount of calcium powder is 0.03
It was wt%.

(Example 5) Neodymium oxide powder 126.0g, -10mesh
granular metallic calcium 67.50 (1.5 times the chemically required amount [weight ratio]), -32mesh particle size iron powder 171.4g, -32IIesh particle size boron-iron alloy powder (20.4wt) % boron, residual pig iron) 20
．． 6 g, calcium chloride powder 6.2 (1 (0.05 times the stoichiometric amount of calcium oxide produced [molar ratio]), 3.3 g of sodium chloride (0.05 times the stoichiometric amount of calcium oxide produced) (mole ratio)) and mixed them in a type mixer to prepare a total of 395.0g of base material.

This base material was placed in a stainless steel container and heated at 1200° C. for 2 hours in an argon gas atmosphere. After the alloy and slag were separated, the container was tilted and the alloy was poured into the ingot case. This gave an alloy of 293.09. Analysis of the composition of the alloy revealed: 3s, awt% neodymium, 1.39wt% boron, 0.02wt
% calcium, balance iron. The amount of oxygen was 56 ppm. This alloy was made into a permanent magnet under the same conditions as in Example 1, and its magnetic properties were measured. The residual magnetic flux density was 4πT.
r = 11.9KG, coercive force IHC = 12.4KOe,
Maximum energy product (B H) m = 33.5M-G-
I got a value of . The oxygen content of the sample was 4700 ppm, and the calcium content was 0.02 wt%.

(Example 6) Neodymium oxide powder 91.0 (1, powdered calcium hydride 27.3 iJ (0.8 times the chemically necessary amount [
Weight ratio]), -10 mesh granular metallic calcium 26,00 (0.8 times the chemically necessary amount [weight ratio]), -32 mesh particle size iron powder 119.4 g, -
2.6 g of pure boron (1, 14.2 g of sodium chloride powder (0.3 times the stoichiometric production amount of calcium chloride [mole ratio]) with a particle size of 10 meSh was weighed and placed in a V-type mixer. A total of 280.5Q of base materials were prepared.

This base material was placed in a container made of boron nitride wood, and heated at 1250°C x 41-1 in an argon gas atmosphere. After the alloy and slag were separated, the container was cooled to room temperature and the alloy was recovered from the container. As a result, the alloy of 192.7 (l) was (q). When the composition of the alloy was analyzed, it was found that it was 38.9 wt.
% neodymium, 1,29wt% boron, 0,03
wt% calcium.

The remainder was iron. The amount of oxygen was 69 ppll. This alloy was made into a permanent magnet under the same conditions as in Example 1, and its magnetic properties were measured. The residual magnetic flux density was 4π [r = 11
．． 6KG, coercive force I Hc = 12.7K Oe.

Maximum energy product (BH) m=32.3 M-G-O
A value of a was obtained. The amount of oxygen in the sample was 4900 ppm,
Calcium content was 0.03 wt%.

(Example 7) Neodium oxide powder 210.0g, -10111e
Granular metallic calcium of sh 93.8 (1 (1.25 times the chemically required amount [weight ratio]), -32 mes
288.1 g of iron powder with a particle size of -32mesh, boron-iron alloy powder with a particle size of -32mesh (20.4vt% boron, residual iron) 3
1.9 (], calcium chloride powder 20.8 (+ (
10.9 g of sodium chloride powder (0.1 times the stoichiometric amount of calcium oxide [mole ratio]), potassium chloride Powder 14.0 (1 (0.1 times the stoichiometric production amount of calcium oxide [mole ratio]) was weighed and mixed in a V-type mixer to prepare a total of 669.5 g of base material. This base material was placed in an iron container whose inner wall was coated with boron nitride, and heated at 1300° C. for 4 hours in an argon gas atmosphere.

After the alloy and slag were separated, the container was tilted and the alloy was poured into the ingot case. This results in 492.0 (
An alloy of 1 was obtained. When the composition of the alloy was analyzed, it was found that 35,
8wt% neodymium, 1.27wt% boron.

0.02wt% calcium, balance iron. The amount of oxygen was 48 ppm. This alloy was made into a permanent magnet under the same conditions as Example 1, and its magnetic properties were measured. Residual magnetic flux density 4πl r = 12.0 KG, coercive force IHC = 1
1.2KOe, maximum energy combined (BH) m-34,
A value of 1M-G-Oe was obtained. The amount of oxygen in the sample is 435
0 ppm, and the amount of calcium was 0.02 wt%.

(Comparative Example 1) Metal neodymium 43.2G, pure iron 69. Og, boron-
Iron alloy (boron 20.4 wt%, residual pig iron) 7.8 () was weighed and arc melted in an argon gas atmosphere.

As a result, an alloy of 118.5 (l) was obtained. Analysis of the composition of this alloy revealed that it contained 35.8 wt% neodymium, 1,
The content was 30wt% boron, 0.004wt% calcium, and the balance iron.

The amount of oxygen was 48 ppm. This alloy was made into a permanent magnet under the same conditions as in Example 1, and its magnetic properties were measured. The residual magnetic flux density was 4π (r = 12.0 KG, the coercive force rHc
=+1.2KOe, maximum energy product (BH) m=3
4.2 The value fvlG·Oe was obtained. The amount of oxygen in this sample is 4400 ppn, and the amount of calcium is 0.00 ppn.
It was 4wt%.

(Comparative Example 2) Neodymium oxide powder 125.9g, -10mesh
Granular metallic calcium 56.2Q (1.25 times the stoichiometric requirement), -100mesh
172.3g of iron powder with a particle size of -100mesh, boron-iron alloy powder with a particle size of -100mesh (20.4wt% boron, residual pig iron) 1
9.81 liters were weighed and mixed in a V-type mixer to produce a total of 374.2Q of base materials.

This base material was placed in a stainless steel container and subjected to reduction/diffusion treatment at 1200° C. for 4 hours in an argon gas atmosphere.

Next, this reaction product was poured into water and washed repeatedly to remove generated CaO.

After drying the coarse powder obtained as a result, the mm
was 288.0 (l). Also, the compositional analysis value of the coarse powder was 3
5.4 wt% neodymium, 1.30 wt% boron.

It contained 0.25 wt% calcium and the balance was iron. The amount of oxygen was 6000 ppn.

Using this coarse powder, pulverization, molding, sintering, and heat treatment were performed under the same conditions as in Example 1, and the magnetic properties of the sample were measured. As a result, the residual magnetic flux density was 4πI r = 11.8 KG, and the coercive force IHC = 8. 5KOe, maximum energy product (BH) m
The value was 32.0M-G-Oe.

Further, the oxygen content of this sample was 9000 ppm, and the calcium stone content was 0.25*t%.

(Comparative Example 3) Neodymium oxide powder 262.4g, -10mesh
Granular metallic calcium 117.2 (] <1.25 times the chemical requirement [weight ratio), -32meS
Iron powder with a particle size of h 75.0 (], calcium chloride powder s
i, 9g (0 of the stoichiometric production amount of calcium oxide
．． 2 times [molar ratio]) were weighed and mixed in a V-type mixer to prepare a total of 506.5 (l) of the mother material. This mother material was placed in a stainless steel container and heated in an argon gas atmosphere. After the alloy and slag were separated, the container was tilted and the alloy was poured into the ingot case. As a result, 294.8 (l) of the alloy was obtained. When the composition of the alloy was analyzed, it was found to be 74.6 wt% neodymium, 0.32 wt% calcium, and the balance iron.The amount of oxygen was 87 ppm.This alloy 48.
3 (L pure iron 45.3 (L and boron-iron alloy (20.4W)
t%, residual pig iron) was added, and these were arc melted in an argon gas atmosphere. A large amount of calcium gas was generated during the dissolution process. As a result, 98.8 g of alloy was obtained.

The composition of this alloy was analyzed and found to be 35.7wt% neodymium, 1.28wt% boron, and 0.08wt% calcium.

The remainder was iron. The amount of oxygen was 55 ppm. This alloy was made into a permanent magnet under the same conditions as in Example 1, and its magnetic properties were measured. The residual magnetic flux density was 4πI r =11.
9KG, coercive force rHc = 10.7KOe.

Maximum energy 'HA (BH) m = 32.9M-
The value was G-Oe. Also, the amount of oxygen in the sample was 47
50ppm.

The amount of calcium was 0.01hvt%.

[Effects of the Invention] As described above, the present invention makes it possible to inexpensively produce an alloy for neodymium-boron-iron permanent magnets that has excellent magnetic properties that can be used as a practical material with extremely low amounts of residual calcium and oxygen groups. can do.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between neodymium suspension and magnetic properties of a neodymium-boron-iron permanent magnet. FIG. 2 is a diagram showing the relationship between boron loading and magnetic properties of a neodymium-boron-iron permanent magnet. Keio “Kumu, Kei 16! □ 1985 Patent Application No. 199767 Name of invention
Relationship with the case concerning a person amending the manufacturing method of an alloy for permanent magnets Patent applicant address 2-1-2 Marunouchi, Chiyoda-ku, Tokyo Name (5)
08) Hitachi Metals, Ltd. Amendment Contents 1, page 16, line 16, “75 wt%” was changed to “75 at%”
” is corrected.

Claims (3)

[Claims] (1) Neodymium oxide, iron, boron (or boron-iron alloy)
Metallic calcium, calcium hydride, or a mixture thereof is added as a reducing agent, and at least one of calcium chloride, sodium chloride, or potassium chloride is added as a flux, and these raw materials are placed in an inert gas atmosphere or a reducing gas atmosphere. or 25.0 wt% to 50.0 wt% neodymium by heating and melting at 1000 to 1350°C under substantially vacuum conditions and reducing neodymium oxide,
A method for producing an alloy for permanent magnets, which comprises obtaining a neodymium-boron-iron alloy consisting of 0.3 wt% to 5.0 wt% boron and the remainder substantially iron. (2) In the method for producing an alloy for permanent magnets as set forth in claim 1, metallic calcium, calcium hydride, or a mixture thereof as a reducing agent is used in a stoichiometric range of 1. A method for producing an alloy for permanent magnets, characterized by adding 0 times to 2.0 times (weight ratio). (3) In the method for producing an alloy for permanent magnets according to claim 1 or 2, calcium oxide produced by reducing at least one of calcium chloride, sodium chloride, or potassium chloride as a flux 0.03 times or more and less than 0.5 times the stoichiometric production amount (
A method for producing an alloy for permanent magnets, characterized in that a molar ratio) is added.