WO2000006792A1

WO2000006792A1 - Permanent magnetic alloy with excellent heat resistance and process for producing the same

Info

Publication number: WO2000006792A1
Application number: PCT/JP1999/004048
Authority: WO
Inventors: Masami Kamata; Michio Obata; Yuichi Sato
Original assignee: Dowa Mining Co., Ltd.
Priority date: 1998-07-29
Filing date: 1999-07-28
Publication date: 2000-02-10
Also published as: EP1607491A1; EP1026279A1; DE69927931T2; HK1032247A1; JP4034936B2; DE69938467D1; CN1098368C; DE69938467T2; DE69927931D1; EP1026279A4; EP1607491B1; CN1274394A; EP1026279B1

Abstract

A permanent magnetic alloy having excellent heat resistance which comprises 0.1 to 15 at.% C, 0.5 to 15 at.% B (the sum of C and B is 2 to 30 at.%), 0 to 40 at.%, excluding 0 at.%, Co, 0.5 to 5 at.% Dy and Tb, 8 to 20 at.% R (provided that R represents at least one element selected from the group consisting of Nd, Pr, Ce, La, Y, Gd, Ho, Er, and Tm), and Fe and unavoidable impurities as the remainder.

Description

Description Permanent magnet alloy with excellent heat resistance and manufacturing method

The present invention relates to an R-B-C-Co-Fe-based permanent magnet alloy (R is Y) which has extremely excellent heat resistance such that the magnetic force hardly deteriorates even when used at 200 ° C in the atmosphere. Or rare earth elements). Background art

Sm—Co magnets are known as rare earth magnets having excellent heat resistance. However, this magnet is expensive. The heat resistance here means that the magnetic force does not deteriorate by heat. As a rare earth magnet which is cheaper and has improved heat resistance, R-B described in Japanese Patent Application Laid-Open No. HEI 4-116164 (Patent No. 274,981) by the same applicant. — C— Co-Fe permanent magnet alloys are available. This magnet alloy uses C (carbon) as an essential alloying element and uses a combination of light rare earth and heavy rare earth as R. The publication indicates that the inclusion of C significantly improves the irreversible demagnetization rate (negative values approach the 0% side), and that the use of heavy rare earth elements in part of R further irreversible. It teaches that the demagnetization rate is improved. Purpose of the invention

When a permanent magnet is attached to equipment installed near a heat source, it is required that the magnetic force does not decrease even when the temperature rises, that is, that the residual magnetic flux density (B r) does not deteriorate. If the operating temperature is around 200 ° C (for example, some devices installed around the engine for automobiles will be around 200 ° C, and motors for electric vehicles are unparalleled. ), Obedience Only Sm-Co magnets can be applied. However, this is expensive as mentioned above. The conventional X d- F e (C o - the B rare earth magnet used in such a high temperature (e.g., 2 0 0 ^{C C)} is impossible.

As described in the above-mentioned Japanese Patent Application Laid-Open No. H11-164144, in the case of using C (carbon) as an alloying element, the irreversible demagnetization rate is improved by the inclusion of C, and a part of R is superposed. The use of rare earth elements further improves the irreversible demagnetization rate, but the publication does not disclose anything that does not demagnetize even when the temperature is raised to 200 ° C.

Accordingly, an object of the present invention is to obtain an inexpensive permanent magnet alloy that has excellent heat resistance enough to withstand use even at 200 ° C. Disclosure of the invention

In order to solve the above-mentioned problems, based on the basic idea that the content of C improves heat resistance as proposed in Japanese Patent Application Laid-Open No. 4-116164, the heavy rare earth element Investigations into the effects on individual heat resistance revealed that, in addition to basic rare earth elements such as Nd and Pr, when Dy and Tb were added in an appropriate amount in combination, Dy and Tb It was newly found that the heat resistance was remarkably improved when added in amounts related to each other.

That is, the present invention provides an atomic percentage (at.

C: 0.1-1 5 at.

B: 0.5-15 at.%,

C + B: 2-30 at.%,

C o: 40 at. Or less (not including 0%),

D y + T b: 0.5 to 5 at.%,

Preferably T b (at.¾) / D y (at.¾): 0.1-0.8

R: 8 to 20 at.%,

Where R is Nd, Pr, Ce, La, Y, Gd, Ho, Er and T m represents at least one element selected from the group consisting of m. The balance: Fe and unavoidable impurities,

And a permanent magnet alloy having excellent heat resistance.

The heat resistance of this permanent magnet alloy is determined by the irreversible demagnetization rate (20

It is characterized in that 0 ° C shows a range of 0% to 120%, more preferably a range of 0% to 115% (iHc ≥ 13 KOe).

Irreversible demagnetization (2 0 0 ° C) = 1 0 0 X (A 2 .. - A 25) / A 2 5 · · (1) where

A _25: permeance coefficient (P c) is after magnetization of the specimen to the shape was adjusted to 1 with 5 0 K 0 e, at room temperature (2 5 ° C) measured flux value

A ₂₀ . : Samples were measured _{A 25 2 0 0 ° 1 2} 0 minute hold was followed at room temperature (2 5 ° C) the flux values measured was cooled to C.

In particular, when the irreversible demagnetization rate is 0 to 120%, the proper combination of Dy and Tb, for example, Dy + Tb: 0.5 to 5 at. It can be obtained in a combination of 3 to 4.9 at.% And Tb in the range of 0.1 to 4.7 at.% (The range surrounded by points A, B, C, and D in Fig. 1). Those with a demagnetization ratio of 0 to 115% can be obtained by the Dy content and Tb content in the range surrounded by points B, C, H, E, F and G shown in Fig. 1. BRIEF DESCRIPTION OF THE FIGURES

Figure 1 is a distribution diagram of the irreversible demagnetization rate of the magnets in Table 2 at 200 ° C, organized by Dy and Tb contents.

FIG. 2 shows the shape of the magnet of Example 24 in Japanese Patent Application Laid-Open No. HEI 4-11616 and that of Example 2 according to the present invention so that the permeance coefficient (P c) becomes 3. The figure shows the results of measuring the irreversible demagnetization rate at different measurement temperatures when the adjusted sample was magnetized at 50 KOe.

Figure 3 shows the shape adjusted so that the harmony coefficient (P c) is 1. This figure shows the same irreversible demagnetization rate measurement results as in Fig. 2, except that the used sample was used. Preferred mode of the invention

When designing equipment based on the assumption that the operating temperature of the magnet may reach 200 ° C in some cases, the guideline is the irreversible demagnetization rate at 200 ° C. That is, the value (minus) of the irreversible demagnetization rate (200 ° C) in the above equation (1) should be as close to 0% as possible.

R is typically Nd or Nd + Pr. R—B—Co—Fe The value of irreversible demagnetization (160 ° C) when an appropriate amount of C is added to the sintered magnet alloy. (Minus) approaches 0. This fact is shown in the example of Japanese Patent Application Laid-Open No. 4-116164. However, the irreversible demagnetization rate (160 ° C) shown in this publication is A ₂ Q in the above equation (1). _A16 . (A ₁₆ is the flux value measured at ₁₆₀ ° C for 120 minutes and then cooled to room temperature), and the value measured when the permeance coefficient (P c) is 3. . That is, after magnetization at 5 0 KO e on samples prepared shaped so that P c force 3, eight ₂₅ and eight _16. This is the irreversible demagnetization rate (160 ° C) obtained by measuring the flux value. As shown in this publication, the effect of improving heat resistance (and the effect of oxidation resistance) by containing C is known, but the irreversible demagnetization rate at 200 ° C was unknown. In addition, the value of the irreversible demagnetization (200 ° C) of all conventional R- (F e, C o) -B sintered magnet alloys (without using C as alloying element) is 0% to 1%. No indication of 20% was known.

Since the present inventors have proposed in the above-mentioned publications, we have further improved the heat resistance of sintered R-Fe-Co-C-B series magnet alloys, and have studied their alloy composition and manufacturing method. We have been conducting various tests and studies, but even among the rare earth elements, when Dy and Tb are added in an appropriate amount, the irreversible demagnetization rate becomes remarkably high. It has been found that a low magnet alloy can be obtained. Addition of Dy and Tb alone does not provide much effect, but when both are added in combination, the heat resistance improves.

Hereinafter, the outline of the reason for restricting the range of the content of each component of the magnet alloy of the present invention and the method of manufacturing the alloy magnet according to the present invention will be described.

[C: ϋ. 1 to 15 at.%]

C, as described in Japanese Patent Application Laid-Open No. HEI 4-11616, improves the easily oxidizable property of rare earth magnets while maintaining good magnetic properties of the magnet alloy, and improves the oxidation resistance. Provides an effect of improving It also contributes to lowering the irreversible demagnetization rate. If the effect of improving the oxidation resistance and heat resistance of C is less than 0.1 lat.%, It is not sufficient. However, when it exceeds 15 at.%, Br decreases. Therefore, the ability to contain a C content of 0.1 to 15 at.! ¾ is preferably in the range of 1.0 to 10 at.%, And more preferably 2.5 to 7 at.%. It is a range.

[B: 0.5 to 15 at.! ¾]

B is required for the formation of the magnetic phase, which requires at least 0.5 at.%. However, excessive addition actually degrades the magnetic properties. Therefore, the ability to contain 0.5 to 15 at.% Of B is preferable. The preferred amount of B is in the range of 1.0 to 10 at.%, And the more preferable B is in the range of 1.5 to 7 at.%. It is an enclosure.

C C + B: 2 to 30 at.

C + B contains at least 2 at. ¾i to form a magnetic phase and improve oxidation resistance. However, if it exceeds 30 at.%, The magnetic properties deteriorate, so C + B is set to 2 to 30 at.%.

C C 0: 40 at. ¾ or less]

C 0 has the effect of increasing the Curie point while maintaining magnetic properties. For this reason, if the force required to contain C 0 exceeds 40 at. Because it becomes significant, it is contained in an amount of 40 at.% Or less.

[Dy ten Tb: 0.5 to 5 at. ¾]

Dy and Tb are characteristic elements of the magnet of the present invention, and the irreversible demagnetization rate can be significantly reduced by adding both elements in combination. For this reason, the total amount of Dy + Tb is 0.5 at. ¾; the force that requires the above, even if the total weight exceeds 5 at. Since the characteristics may be degraded, the total amount is 0.5 to 5 at. The addition of Dy alone or Tb alone does not contribute much to the reduction of the irreversible demagnetization as shown in the comparative examples below. This suggests that the irreversible demagnetization rate decreases due to the synergistic effect of both elements. Further, the content ratio Tb (at.¾) ZDy (at.¾) of both elements is preferably in the range of 0.1 to 0.8, and as shown in the examples described later, Dy is 0.3 to 4.9 at. T and Tb is 0.:! Within the range of ~ 4.7 at.%, The irreversible demagnetization rate at 200 ° C under the permean coefficient = 1 is 0 to 20%, preferably 0 to 15%. A magnet with excellent heat resistance as shown can be obtained.

[R: 8 to 20 at.%]

As a rare earth element other than Dy and Tb, one or more of Nd, Pr, Ce, La, Y, Gd, Ho, Er, and Tm are 8 to 20 at.%. By containing it, a magnetic phase and a grain boundary phase are formed in the sintered magnet alloy, and high iHc and Br can be maintained. Among these R elements, particularly preferred elements are Nd and Pr, and it is particularly desirable to add Nd alone or a combination of Nd and Pr. If R is less than 8 at.%, Sufficient Br cannot be obtained, and if it exceeds 2 O at.%, Sufficient Br cannot be obtained. The preferred content of the R element is 13 to 18 at.%.

The permanent magnet alloy of the present invention having the above composition has a low irreversible demagnetization rate (200) according to the above equation (1) of 0 to 120%, preferably 0 to 115%. Values, and even values from 0 to 15%, rare earth magnets For the first time other than Sm-Co magnets, permanent magnet alloys for high temperature applications are provided. In conventional B-containing rare earth magnets, this problem has been dealt with by using a magnet with a high coercive force in anticipation of demagnetization when the temperature is raised. Since demagnetization hardly occurs, it can continue to function as a permanent magnet with a high magnetic force. In particular, the magnet of the present invention can maintain its magnetic properties even when used for temperature rise applications if iHc is 13 KOe or more, preferably 15 KOe or more. Compared to conventional magnets, which had to have considerably high iHc in order to maintain the magnetic properties for heating applications, they could be said to be effective permanent magnet alloys. In order to produce the permanent magnet alloy of the present invention, a sintered magnet can be obtained by a series of steps of melting, forging, pulverizing, forming, and sintering. Vacuum melting, sintering, inert gas atmosphere melting, sintering, quenching roll method, atomizing method, etc. can be adopted as the melting and forming method. In order to obtain a sintered magnet with excellent magnetic properties and heat resistance, insert a heat treatment step between the manufacturing and pulverizing steps, and heat the pre-pulverized one in an inert gas atmosphere at a temperature of 600 ° C or more. It is preferable to perform the heat treatment at, so that the irreversible demagnetization rate can be further reduced. In the sintering process, sintering is performed at a temperature of 1000 to 1200 ° C in an inert gas, and the temperature is gradually cooled from this sintering temperature to 600 to 900 ° C. It is preferable to rapidly cool from that temperature. The irreversible demagnetization rate can be further reduced by rapid cooling after the sintering.

Except for the above heat treatment and the quenching treatment after sintering, the sintered magnet alloy of the present invention can be manufactured according to the same method as that for the sintered magnet described in Japanese Patent Application Laid-Open No. 4-116164. . The outline is as follows.

First, the raw materials of each component weighed so as to have an alloy composition are melted in a vacuum melting furnace at 160 ° C or higher, and rapidly cooled in a water-cooled mold. The obtained lump is heat-treated in an Ar atmosphere at 600 ° C or higher as described above, and then coarsely ground with a jaw crusher. The obtained coarse powder is finely pulverized with a vibrating ball mill. Reduce the diameter to 2 to 1 2m powder. These grinding processes are also performed in an Ar atmosphere. In the latter pulverization process, part of the C raw material can be added. That is, a part of the raw material C is put into the vacuum melting furnace, and the rest is added in this fine pulverization process. Carbon black is suitable as the C raw material, but organic substances containing C such as aliphatic hydrocarbons, higher fatty alcohols, higher fatty acids, fatty amides, metallic soaps, and fatty acid esters can also be used.

Next, the powder is compacted in an external magnetic field. Range. 1 to 5 t Roh cm ² The molding pressure, it is appropriate or 1 5 KO e as the external magnetic field. This molding step is also desirably performed in an Ar atmosphere. This molded product is sintered in an Ar atmosphere at 100 to 1200 ° C. for about 2 hours. Then, as described above, it is gradually cooled from the sintering temperature to 600 to 900 ° C, and then rapidly cooled from that temperature. The quenching can be started from 600 to 900 ° C by blowing a low-temperature inert gas from that temperature, or by immersion in water or oil or a similar liquid. This quenching start temperature is from 600 to 900 ° C to 400 ° C or below — at 50 ° C Zmin or more, preferably at a cooling rate of-100 / min or more. Is good.

Therefore, according to the present invention, each raw material of the alloy component is melted and formed, the obtained alloy is pulverized, the powder is compacted, and the molded product is subjected to 100 Q to 100 Q in an inert gas. When sintering at a temperature of 1200 ° C to produce a sintered magnet alloy with the above composition, the alloy before grinding is heat-treated in an inert gas at a temperature of 600 ° C or more. And / or sintering in an inert gas at a temperature of 1000 to 1200 ° C, then slowly cooling from the sintering temperature to 600 to 900 ° C, Provided is a method for producing a permanent magnet alloy having excellent heat resistance characterized by rapid cooling. At that time, part of the C raw material can be added during melting, and the other part of the C raw material can be added during alloy grinding.

Hereinafter, typical examples of the magnet of the present invention will be described. Example

(Example 1)

An alloy having the following composition was produced by the method described below.

"Ingredient composition of alloy (at.¾)"

C: 5.0 at.

B: 1.8 at.%,

C o: 12.0 at.

N d: 13.0 at.

D y: 2.5 at.

T b: 0.5 at.

F e: 6 5.2 at.

C + B = 6.8 at.%,

D y + T b = 3.0 at at ¾,

T b / D y = 0. 2

`` Manufacturing method ''

Each component raw material was weighed so as to have the above-mentioned alloy composition and melted in a vacuum melting furnace. At that time, a part of the C raw material was stored without being put into the melting furnace. The obtained molten metal was rapidly quenched in a copper water-cooled mold from 160 ° C. to obtain a lump alloy. This lump alloy is coarsely ground with a jaw crusher with or without heat treatment in an Ar atmosphere at the temperature shown in Table 1, and the coarse powder and the stored C raw material are vibrated ball mill. And pulverized to obtain a powder with an average particle size of 5 m.

After this powder was a magnetic field formed by an external magnetic field of 1 in 5 KO e at a pressure 2 t Z cm ² and the molded body was sintered for 2 hours at 1 1 0 0 ° C in an A r atmosphere, the sintering temperature Then, it was gradually cooled to the quenching start temperature shown in Table 1, and Ar was sprayed from the quenching start temperature to quench at the indicated cooling rate. The magnetic properties, heat resistance and oxidation resistance of the obtained sintered product were evaluated, and the results are shown in Table 1. Heat resistance and resistance Oxidation evaluation was performed as follows.

"Heat resistance evaluation"

(1) Measurement of irreversible demagnetization rate at 20 () ° C

Adjust the shape of the sample so that the permeance coefficient (P c) becomes 1. Specifically, cut out a 2.5 mm x 2.5 mm x l.05 mm sample.

This sample is magnetized with an external magnetic field of 50 KOe, and the flux is measured at room temperature (25 ° C). The measurement of the flux was performed by mounting an iron core coil on a flux meter manufactured by Toyo Magnetic Industry Co., Ltd. The value of the flux at this time is A _25.

Next, the magnetized sample was kept at 200 ° C for 120 minutes. The heating was performed in an oil bath filled with silicon oil. The temperature of the oil bath was precisely controlled at 0.1. After the sample taken out of the oil bath is sufficiently cooled at room temperature, the flux is measured again using the flux meter described above. The flux value at this time is A ₂₀ . And From A ₂₅ and A ₂₀₀ was measured to calculate the irreversible demagnetization by the following equation.

Irreversible demagnetization (2 0 0) (%) = 1 0 0 X (A 2 ..- A 25) / A 25

(2) Measurement of irreversible demagnetization rate at 160 ° C

The shape of the sample was adjusted so that the admittance coefficient (P c) became 3 in the same manner as in the embodiment of Japanese Patent Application Laid-Open No. 4-116144, and the heating and holding in an oil bath were performed. ° except for using CX 1 2 0 minutes, and a ₂₅ to measure the same way in the above 2 0 0 ° C a _16. Is measured, and the irreversible demagnetization rate is calculated using the above formula.

(3) Temperature coefficient of magnetic properties and coercive force

After magnetizing the sample with an external magnetic field of 50 KOe, measure the magnetic properties at room temperature (25 ° C) using a vibrating magnetometer. The temperature coefficient of the coercive force is calculated by the following equation, using the coercive force at room temperature as _BQ and the coercive force measured at 160 ° C with a vibrating magnetometer.

Temperature coefficient of coercive force (% Z ° C) = 1 0 0 (B,-B oJ / B o / (1 60-25;

(4) Measurement of oxidation resistance

The progress of 鍩 is measured by the pre-shock cooker test (PCT). Specifically, the occurrence of 錡 when the sample is held at 120 ° C, 2 atm, and 100% RH (saturation condition) for 1 () 0 hours is visually observed using a tester manufactured by Tabai Espec.

table 1

As can be seen from the results in Table 1, a permanent magnet alloy with an irreversible demagnetization rate (at 200) of -3% was obtained (for example, a in Table 1). In addition, the irreversible demagnetization rate (160 ° C; is 1% for alloy a), which is almost 0. Therefore, high magnetic force can be maintained even in high-temperature applications.

Looking at the manufacturing conditions, it is clear from comparison of a and b, for example, that the irreversible demagnetization rate decreases when a lump is heat-treated. As is clear from comparison of a, c, and d, rapid cooling from a temperature of at least 700 ° C after sintering improves the coercive force and lowers the irreversible demagnetization rate.

[Examples 2 to 16] and [Comparative Examples 1 to 6]

A sintered product was manufactured under the same manufacturing conditions as in Example 1, except that the composition of the alloy was changed as shown in Table 2. The characteristics of the obtained sintered magnet were measured in the same manner as in Example 1, and the results are shown in Table 2.

Table 2

*) Coercive force fluctuates significantly, making accurate measurement impossible

As can be seen from Table 3, the irreversible magnetic susceptibility of each of Examples 2 to 16 to which both Dy and Tb were added was low at 200 ° C, The irreversible demagnetization rate is also almost 0%. It also has a low temperature coefficient of coercive force and excellent oxidation resistance.

On the other hand, Comparative Example 1 with no addition of Dy and Tb, Comparative Example 2 with no addition of Tb at 0.5 at.! Dy, and 0.5 at. In the case of Comparative Example 4, the irreversible demagnetization rates at 200 ° C were 195%, —95%, and —91%, and the magnetic force was almost completely reduced when the temperature was raised to 200 ° C. Lost. In other words, adding only one of Dy and Tb has no effect on the irreversible demagnetization rate at 200. As in Comparative Example 3, the irreversible demagnetization rate is reduced to some extent by increasing the content of Dy alone, but it is still insufficient. Comparative Example 5 is inferior in oxidation resistance because the C content is lower than the range specified in the present invention. In Comparative Example 6, Tb was added without addition of Dy. 3. O at. ¾; Force that was added Although irreversible demagnetization at 200 ° C. was better than Comparative Example 4, although heat resistance was better. Low at 0%.

Figure 1 shows the Dy content (at.%) On the horizontal axis and the Tb content (at.! 0) on the vertical axis, and all magnets in Table 2 (except for Comparative Example 5 where point 錡 occurred). ) Shows the distribution of the irreversible demagnetization value at 200 ° C for the amounts of Dy and Tb contained in each of them. The figure shows the value of the irreversible demagnetization factor at that position at 200 ° C. From the results in Fig. 1, Dy: 2 to 3 at.! ¾ and Tb: 0.3 to 1 It can be seen that there is a peak (point where the irreversible demagnetization approaches 0%) in the irreversible demagnetization at 200 ° C in the .5 at.% Region. In the region where the irreversible demagnetization rate at 0 ° C is 0 to 120%, the points A, B, and 6 of the intersections of the straight lines (1) (2) (3) (4) (5) (6) The area surrounded by C and D, where the irreversible demagnetization rate at 200 ° C is 0 to 115%. , Point B, C, H, it can be seen that a range surrounded by E. F and G. The straight lines Π) to (6) are represented by the following equations.

Line (1): D y = 0.3

Line (2): Tb + Dy = 0.5

Straight line (3): T b = 0.1

Line (4): T b = 0.1 D y

Line (5): T b = 0.8 D y

Line (6): Tb + Dy = 5.0

The coordinates (D yat.¾i, T bat.%) Of points A to H are as follows: Point A (0.3. 4.7)

Point B (0.3, 0.2)

Point, C (0.4, 0.1)

Point D (4.9, 0.1)

Point E (4.5, 0.5)

Point F (2.8, 2.2)

Point G (0.3, 0.24)

Point H (1.0, 0.1)

FIGS. 2 and 3 show the magnets of Example 24, which are considered to have the highest heat resistance among the magnets disclosed in Japanese Patent Application Laid-Open No. HEI 4-116144, and those according to the present invention. When a sample whose shape was adjusted so that the permeance coefficient (P c) became 3 with the sample of Example 2 was magnetized at 50 KOe (Fig. 2), and? (The figure shows the results of measuring the irreversible demagnetization rate at different measurement temperatures for the case where the sample whose shape was adjusted to become 1 was magnetized at 50 KOe (Fig. 3). The magnet of Example 24 (referred to as open magnet) of Japanese Patent Application Laid-Open No. HEI 4-1-164144 is 9 Nd—9 Dy—59 Fe—15 Co—IB—7 C The publication describes that the irreversible demagnetization rate at 160 ° C. at P c = 3 is 11.0%.

As shown in Fig. 2, in the sample whose shape was adjusted so that Pc = 3, 16 The irreversible demagnetization rate at () ° C. was −1.0% for the open magnet and −0.7% for the magnet of Example 2 of the present invention, and there was not much difference. When Pc = 3, the irreversible demagnetization rate at 2 () () ° C is -12.9% for the open magnet, whereas that of Example 2 of the present invention is 1. Up to 9%. This tendency can be seen more clearly in Fig. 3 using a sample whose shape has been adjusted to have a Pc force of 1. That is, at P c = l, the irreversible demagnetization rate at 160 ° C is -9.4% for the open magnet, whereas it is improved to 11.7% in Example 2 of the present invention. The irreversible demagnetization rate at 200 is 12.3% in the case of the open magnet, whereas it is increased to 14% in Example 2 of the present invention.

As described above, according to the present invention, in the field of R-Fe (Co) -B magnets, a permanent magnet alloy having excellent heat resistance and oxidation resistance that has never been achieved so far. Is obtained. Therefore, a low-cost material with excellent magnetic properties can be provided as a permanent magnet to be mounted on equipment that is expected to heat up.

Claims

The scope of the claims

1 · Atomic percentage (atl)

C: (). G 1 5 at. ¾ !,

B: 0.5 to 15 at.

C + B: 2 to 30 at.%,

C 0: 4 Oat.% Or less (excluding 0%),

D y + T b: 0.5 to 5at.%

R: 8 to 20 at.! ¾,

Where R represents at least one element selected from the group consisting of Nd, Pr, Ce, La, Y, Gd, Ho, Er, and Tm.

The balance: Fe and unavoidable impurities,

Permanent magnet alloy with excellent heat resistance.

2. The permanent magnet alloy excellent in heat resistance according to claim 1, wherein Tb (at.¾) / Dy (at.¾): 0.1 to 0.8.

3. The permanent magnet alloy excellent in heat resistance according to claim 1 or 2, wherein C: 1 to 10 at.%.

4. The permanent magnet alloy having excellent heat resistance according to claim 1, 2 or 3, wherein R is Nd alone or Nd and Pr.

5. The permanent magnet alloy having excellent heat resistance described in claims 1, 2, 3, or 4, wherein iHc is 13 KOe or more.

6. The heat resistance according to claim 1, wherein the irreversible demagnetization rate (200 ° C) according to the following equation (1) is in the range of 0% to 120% (however, iHc ≥ 13 KOe). Excellent R-B-C-Co-Fe-based sintered magnet alloy.

Irreversible demagnetization rate (200 ° C) = 100 X (A ₂ oo-A ₂₅ ) / A ₂₅ (1)

A _25: permeance coefficient after magnetization of the (P c) is adjusting the shape so that the 1 specimen at 5 0 K 0 e, flux value measured at room temperature (2 5 ° C). A zoo: Samples were measured _{A 25 2 0 0 ° 1 2} 0 minute hold was followed chamber temperature (2 5 ° C) flux value measured was cooled to C.

7. D y: (). 3 ~ /! 9 at. T b: (). The irreversible demagnetization rate at 2〜 () ^C C at 1 to 4.7 at.% Is () to −20%. Excellent R-B-C-Co-Fe sintered magnet alloy.

8. The content of Dy and Tb (at.¾;) is in the range enclosed by points B, C, H, E, F and G shown in Fig. 1, and irreversible decrease at 200 ° C 7. The heat-resistant R—B—C—Co—Fe based sintered magnet alloy according to claim 6, having a magnetic susceptibility of 0 to 115%.

9. The heat-resistant R-B-C-Co-Fe sintered magnet according to claim 2, wherein the irreversible demagnetization rate (200 ° C) is in the range of 0% to 15%. alloy.

100. Melt the raw materials of the alloy components, pulverize the obtained alloy, compact the powder, and mold the molded product in an inert gas at 100 ° C to 120 ° C. In the method of producing a sintered magnet alloy having the following composition by sintering at an ambient temperature of, the alloy before pulverization is heat-treated in an inert gas at a temperature of 600 ° C or more. Manufacturing method of permanent magnet alloy with excellent heat resistance.

[Component composition of sintered magnet alloy]

C: 0.1 to 15 at.%,

B: 0.5 to 15 at.

C + B: 2 to 30 at.

C 0: 40 at.% Or less (excluding 0%),

D y + T b: 0.5 to 5at.%

R: 8 to 20 at.! ¾,

The balance: Fe and unavoidable impurities.

1 1. After sintering at a temperature of 1000 to 1200 ° C in an inert gas, The method for producing a permanent magnet alloy according to claim 1, wherein the temperature is gradually cooled from the sintering temperature to 600 to 900 ° C.

12. The method for producing a permanent magnet alloy according to claim 1, wherein a part of the C raw material is added during melting and the other part of the C raw material is added during pulverization of the alloy.