JPS59217305A - Permanent magnet material and manufacture thereof - Google Patents

Abstract

PURPOSE:To elevate a Curie point of a magnet material, and to improve temperature characteristics by replacing one part of Fe as the principal ingredient of a Fe.B.R group magnet with Co. CONSTITUTION:Alloy powder of 0.3-80mum mean grain size consisting of R (where R is rare-earth elements containing Y) of 8-30% as an atomic percent, B of 2-28%, Co of 50% or less and the remainder and inevitable impurities is molded, sintered at a temperature of 900-1,200 deg.C under a reducing or a nonoxidizable atmosphere, and thermally treated at a temperature from 350 deg.C to said sintering temperature after sintering. When one part of Fe.B.R group Fe is replaced with Co, a Curie point rises, and not only excellent temperature characteristics are given but also corrosion resistance can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a permanent magnet material with improved temperature characteristics of Fe-B/R permanent magnets and a manufacturing method thereof. It is one of the extremely important electrical and electronic materials used in a wide range of fields. With the recent demands for smaller size and higher efficiency of electrical and electronic equipment, permanent magnet materials are required to have increasingly higher performance.

Current representative permanent magnet materials are alnico, . . . -doferrite, and rare earth cobalt magnets.

With the recent instability of the raw material situation for cobalt, the demand for alnico magnets containing 20 to 30% cobalt by weight has decreased, and inexpensive nord ferrite has become the mainstream magnet material.On the other hand, rare earth Cobalt magnets are all cobalt 50
It is very expensive because it contains up to 65% by weight and Sm, which is not very present in rare earth ores. However, because it has much higher magnetic properties than other ores, it is mainly used in small, high-value-added magnetic circuits. Rare earth ores are mainly composed of light rare earths, which are contained in large amounts in ores as rare earth metals, which cannot be used cheaply and in large quantities in a wide range of fields because they do not contain all the expensive cobalt. It is necessary. Attempts have been made to develop such permanent magnet materials. For example, Clark (A-E・C1ark)
is an amorphous 'I1. ”b
Fe2 has a total energy product of 29.5 MGOe at 4.2°, and when it is heat-treated at 300 to 500°C, the coercive force 11C at room temperature becomes 3.4] (Oe most dog energy product (
Bi-f), ηax was found to be 7 MOOe.

A similar study was conducted on SmFe2, and it was reported that SmFe2 exhibited an energy concentration of 9.2 MGOe at 77°. However, these materials (-I) are all fabricated by sputtering and cannot be used as practical magnets. Also, ribbons made by rapid cooling of PrFe alloys have a coercive force iHc of 2.8 KOe f. Furthermore, Kuhn et al. reported that (Fe 13 )0.9 Tbo,
os Lao, amorphous ribbon by ultra-quenching of 62
It was found that when annealed at 7°C, the coercive force IHC reached as high as 9 KOe and the residual magnetic flux density Br was 5 KG. However, due to the poor squareness of this partial magnetization curve, the (131
-1,) may be low (N, C, Koon et al., Appl, 1.'hys, Left39(
1'0) 1981. pp. 840-842). Matakabakotsu (
L.

1gabacoff) etc. is (F”eB), -xPrx
A ribbon was prepared by ultra-quenching with a composition of
It has been reported that there are some that have a coercive force of almost the same level. However, these ultra-quenched ribbons or suction thin films are not practical permanent magnets that can be used as such, so it is not possible to obtain practical permanent magnets from ribbons or thin films. That is, it is not possible to obtain a bulk magnet (2) having an arbitrary shape and dimension from the conventional ultra-quenched Fe-B-R ribbon or RFe-based sputtered thin film. F reported so far
The magnetization curve of the e-B-R system IJ and yen has poor squareness (it cannot be used as a British water magnet material that can compete with conventional magnets). Both the above-mentioned sputtered thin film and ultra-quenched ribbon are isotropic in nature, and it is virtually impossible to obtain a practical permanent magnet with solid-state anisotropy from them.

In addition, the inventors of the present invention discovered and applied for a Fe-B-R magnet, which is a new high-performance permanent magnet that does not contain expensive Sm or Co, but its Curie point Tc is from 300°C to a maximum of 370°C.

One object of the present invention is to improve the temperature characteristics of this Fe.13.l (Fe.13.l) system magnet and to obtain a new permanent magnet material advantageous to that which cannot be obtained by conventional methods. It has good magnetic properties at high temperatures, can be molded into any shape and practical size, has a high squareness of magnetization curve, and is made of light rare earth elements that are abundant in resources. It is something.

In order to meet these objectives, as a result of intensive research by the present inventors, we first replaced a portion of Fe, which is the main component of Fe-B-R magnets, with fco! It is possible to raise the temperature of the magnetic material by one point and completely improve the temperature characteristics.
Furthermore, in order to improve the magnetic properties of an alloy with a certain composition, a certain amount of powder is molded and sintered, and after sintering, heat treatment under specific conditions (so-called aging treatment) is performed to improve the coercive force and the squareness of the demagnetization curve. It has been found that the invention is significantly improved, that is, the present invention has an atomic percentage of 8 to 30% R (wherein R is at least one kind of rare earth element including Y), 2 to 28
% B, 50% or less Co (excluding LCOO%), and the balance and unavoidable impurities, with an average particle size of 0.3~
A permanent magnet material obtained by molding 80 μm alloy powder, sintering and heat-treating it is provided.

The present invention is still characterized in that in the above series of steps, sintering is performed at a temperature of 900 to 1200 °C in a reducing or non-oxidizing atmosphere, and after sintering, heat treatment is performed at a temperature of 350 °C to the sintering temperature. A method of manufacturing a permanent magnet is provided. This heat treatment is an aging treatment.

Generally, when Co is added to an Fe alloy, as the amount of Co added increases, the Curie point Tc increases in some cases and decreases in others, and it is difficult to predict the result.

In the present invention, a part of l'le of the Fe-B-u system is
As shown in FIG. 1, as the amount of Co replaced increases, Tc gradually increases. Fe-B-R alloy VC's? A similar trend is confirmed regardless of the type. C.

Even if the amount of substitution is small, it is effective for increasing Tc, and as illustrated in Fig. 1, (77-x)Fe-xCo-88-L
Any T of about 300 to about 800°C depending on the amount of X in 5Nd
An alloy with cf is obtained.

The respective compositional amounts of BR and (Fe+Co) of the Fe-Co-B-'fL permanent magnet of the present invention are Fe -B, -R
It is basically the same as the case of the system. In other words, B is 2 in order to satisfy the coercive force HC as a permanent magnet material of IKOe or more.
% (hereinafter, ``chi'' indicates the total atomic percentage in the components) or more, and in order to make the residual magnetic flux density of the hard ferrite Br about 4 KG or more, it is 28% or less. R needs to be 8φ or more in order to make the coercive force IKOe or more. However, 1(,
Because it is easily flammable, difficult to handle and manufacture industrially, and is also expensive, it should be kept at 30% or less.

The amount of Fe substitution for Co is 50% due to the improvement of TC and the cost.
% or less. As R, light rare earths, which are abundant in resources, can be used, and Smk is not necessarily required, or Sm
Since there is no need to use wo as the main ingredient, the raw material is inexpensive and extremely useful.

The rare earth elements R used in the present invention include Yi, light rare earths, and heavy rare earths, and one or more of them are all used. R as U Nd, Pr.

La, Ce, Tb, Dy, Ho,
Er, Eu-, Sm, Gd, Pm, T
m.

Yb, Lu and Y are included. Further, as 1t, a light rare earth metal is sufficient, and Nd and Pr are particularly preferable. Normally, one type of L is sufficient, but in practice, a mixture of two or more types (Mitushmetal, Nonom, etc.) can be used depending on the convenience of obtaining all of them, Sm, Y, L.
a.

Ce, Gd, etc. can be used as a mixture with other R, especially Nd, Pr, etc. Note that this R does not have to be a pure rare earth element, and it is also possible to use an element containing impurities that are unavoidable in manufacturing as long as it is industrially available.

Boron or ferro yt'07i can be used, and materials containing At, Si, C, etc. as impurities can also be used.

The permanent magnet material of the present invention has an R of 8 to 30, a B of 2 to 28%, a CO balance of 50% or less, and a coercive force of I
KOe or higher, the residual magnetic flux density 13r is 4 KG or higher, and the maximum energy product (BH) is no m
It is equal to or better than ax-door elite.

Light rare earth 2 The main component of R is 50% or more of light rare earth in the total R, and it is 1t of 11 to 24 and B of 3 to 27.

Less than 50% co, the remainder substantially Fe (BH)ma
x is 7I mark e or more, which is a preferable composition range. In addition, all light rare earths 1 (containing 50 or more of them and 12
-1 of 20 Chi, B of 4-24, Co of 50% or less.

The remainder is essentially KFe, and the temperature coefficient (b) of Br is 1%/
℃ or less, the temperature characteristics are good, and (BH)ma
x is an extremely preferable composition that exhibits full magnetic properties of 1.0 M30e or more, reaching a maximum of 33 MGOe.

The Fe-, Co-B-R magnet of the present invention is a Co
Not only does it have better temperature characteristics than the Fe-B-L3r system which does not contain f, but also the squareness of the demagnetization curve is improved even before Co addition, so the maximum energy product is improved.

Furthermore, since CO has higher corrosion resistance than Fe, the addition of CO can provide the entire corrosion resistance.

The permanent magnet material 1 having excellent magnetic properties of the present invention is obtained by a manufacturing method that involves a series of steps of pulverizing the above composition alloy, molding it, sintering it, and further heat treating it. The manufacturing method of the present invention will be described below with reference to the case of a magnetically anisotropic permanent magnet material.

As a starting material, Fe is electrolytic iron with a purity of 99.0% or more.

B is pure boron with a purity of 99.0% or more and a purity of 90-O
Ferroboron with a purity of 95 or higher was used for R. These raw materials are blended within the above composition range and melted and alloyed by high frequency melting, arc melting, etc. in vacuum or an inert gas atmosphere.

The alloy obtained by cooling this is coarsely crushed using a stamp mill, a show crusher, etc., and then the Noet mill is applied to the side.

Finely grind using a ball mill, etc. Fine pulverization is done by dry pulverization in an inert gas atmosphere or by pulverization (guacetone).

Any wet grinding in a shoulder solvent such as toluene can be used. The alloy powder obtained by pulverization has an average particle size of 0.9 to 80 μm. If the average particle size is smaller than 0.311 m, the oxidation of the powder becomes significant during the pulverization or subsequent steps, and the density after sintering does not increase, resulting in poor magnetic properties. Also, the average particle size is 80μ
If the mf is exceeded, excellent magnetic properties, especially high coercive force, cannot be obtained. In order to exhibit excellent magnetic causticity, the average particle size of the fine powder is preferably from 2 to 40 μm.
μtn is also suitable for powders with an average particle size of 0.3 to 80 μm in a magnetic field (for example, 5 μm).
KOe or higher) and pressurize and mold. Pressure forming in a magnetic field (
Now let's look at acetone, a method of molding the entire powder as it is.

A method of molding in an organic solvent such as toluene, and other powder molding methods (a method using all yjy type auxiliary agents such as Rough-in and Stair IJ 7A) can be used.

The obtained molded body is heated with at least a non-oxidizing or 99.9% or more inert or reducing gas, for example, in a vacuum of 10 to 2 Torr or under a pressure of 760'J,'orr. It is sintered at a temperature of 900 to 1200°C in an atmosphere of If the sintering time exceeds 5 minutes, the sintered body will be deformed and the orientation of the crystal grains will be disrupted, resulting in a decrease in the residual magnetic flux density and the squareness of the demagnetization curve.If the sintering time is 5 minutes or more, it is good, but if the sintering time is too long, it may be difficult to mass-produce. Since this is a problem, 0.5 to 4 hours is preferable from the viewpoint of development of magnetic properties, etc. 2. The atmosphere during sintering is a non-oxidizing atmosphere as R in the composition is extremely easily oxidized at high temperatures. It is desirable to secure a high degree of sintering in a high vacuum, under an inert gas, under a reducing gas, etc. If an inert gas is used, it is also possible to conduct the sintering under a reduced pressure atmosphere of less than 1 to 760 Torr in order to obtain a high sintering density. .

There is no need to specify the temperature increase rate during sintering, but if a wet molding method is used, the rate of temperature increase during sintering is 40℃/
It takes less than 20 minutes to raise the temperature (200~800℃ during heating).
Preferably, the sail is maintained in a temperature range of 0.00°C for 5 hours or more. When cooling after sintering, a cooling rate of 20°C/min or higher is preferable in order to reduce product variation, and in order to improve the magnetic properties of the subsequent heat treatment, so-called aging treatment (σ cooling rate is 100°C/min). The above is preferable (however, it is also possible to immediately enter the heat treatment step following sintering). Aging treatment is performed for a predetermined period of time at a temperature below the sintering temperature.

Since R in the alloy composition reacts rapidly with oxygen or moisture at high temperatures, the atmosphere for aging treatment is vacuum 10"""l.
In the case of an atmosphere of inert gas or reducing gas, the purity of the atmosphere is 99.99% or more.

The sintering temperature is selected within the above range depending on the composition of the permanent magnet material, and the aging temperature is correspondingly selected below the sintering temperature. For example, 50FelOCo20B2ONd alloy +
For the 65 Fe 2'''0Co5 B10Nd alloy, the upper limit temperatures for aging treatment are 950°C and 1050°C, respectively.

Generally, alloys with a high Fe content, a low B content, or a low R content can exceed the aging temperature limits. However, if the aging treatment temperature is too high, the crystal grains of the magnet body of the present invention will grow excessively, leading to a decrease in the magnetic properties, especially the coercive force, and the optimum aging treatment time will be extremely short, which may make it difficult to control the manufacturing conditions. be. If it is below 350°C, the aging treatment will take a long time and the squareness of the demagnetization curve will deteriorate, making it impossible to obtain a good permanent magnet.

In order to fully develop the excellent magnetic properties without causing excessive growth of the crystal grains of the cornerstone body of the present invention, the aging treatment temperature is set at 450~450°C.
A temperature range of 800°C is preferred. Further, the aging treatment time is preferably 5 minutes to 40 hours. The aging treatment time is also related to the aging treatment temperature, but if it is less than 5 minutes, the effect of aging treatment is small;
The variation in the magnetic properties of the obtained magnet body also increases. On the other hand, 40 hours or more is not practical because it requires too much time industrially. From the viewpoint of good development of magnetic properties and practical aspects, the aging treatment time is 30 minutes, preferably 8 hours.

Furthermore, a multi-stage aging treatment method of two or more stages is also effective and can be used in the method of the present invention.

For example, a composition alloy of 65Fel 5Co7B 13Nd'
After sintering at 1060℃ and cooling, the first stage is 800~
The first stage aging treatment is carried out at 900℃ for 30 minutes to 6 hours, and the second and subsequent stages are then subjected to one or more stages of aging treatment at 400 to 750℃ for 2 to 30 hours to improve the residual magnetic flux density, coercive force,
A magnet body having extremely excellent magnetic properties in all of the squareness of the demagnetization curve can be obtained. In multi-stage aging treatment, the second and subsequent aging treatments are effective in significantly improving coercive force. In addition, as another method of aging treatment, 3.
From the aging treatment temperature of 50℃ to 900℃ to room temperature by cooling methods such as air cooling or water cooling! l) 0.2~b
A magnet body having similar magnetic properties can be obtained even if the magnet body is cooled at the same cooling rate. The aging treatment including a series of these treatment methods can be performed subsequent to sintering, or can be performed after sintering by cooling to room temperature and then raising the temperature.

The present invention is not limited to the welding of magnetically anisotropic permanent magnets, but also in the case of magnetically isotropic permanent magnets, by performing the molding process without applying a total magnetic field during the forming process, the same method can be adopted, which is excellent. All magnetic properties can be expressed. Biisotropic ringing K trs, R10-25%, 83-23%, Co
(BH) may 2 M
30e or more can be obtained. Isotropic magnets originally have magnetic properties that are poor to rare compared to anisotropic magnets, but according to the present invention, they can be improved. □Yes. 1. Good characteristics can be obtained. As the amount of R increases, i
Hc increases, but Br decreases after reaching its maximum value (see Figure 1). Thus, the R amount that satisfies (BH)n, ax2MGOe or more is a factor of 10 or more and 25% or less.

Further, as the amount of B increases, iHc increases, but Br decreases after reaching its maximum value (see FIG. 2). Thus (Bl(
) 83-23% to obtain max 2' MGOe or higher
must be within the range.

Preferably, the main component of light rare earth iR (total R medium light rare earth is 5
0 atoms or more) and 12-20% R15-18% B
, the balance is Fe, and exhibits high magnetic properties of (1-'H)max 4 or more. The most preferred range is Nd,
In the composition of light rare earths such as Pr, i L (as the main component of R16-18%, B balance Fe, (BH) ma
When x is 7 or more, high characteristics never seen before in an isotropic permanent magnet can be obtained.

Binders and lubricants are generally not used in the case of anisotropic magnets because they interfere with orientation during molding, but in the case of isotropic magnets, binders and lubricants are included to improve press efficiency. It is possible to improve the strength of the molded product, etc.

Although the permanent magnet of the present invention can tolerate the presence of impurities that are inevitable in industrial production, the following developments are also possible and the practicality can be further improved. That is, in addition to RlB and Fe, C, P, S, and Cu may be contained within a predetermined range, contributing to manufacturing convenience and cost reduction.

C is an organic binder, and S, P, Cu, etc. may be contained from raw materials and manufacturing processes. C4.0% or less,
P3.3% or less, 82.5% or less, Cu3.3% or less,
However, these sums are practical if they are less than the maximum value of each component.

Example 1 An alloy iA+ having an atomic percentage composition of 66Fe6B 14NdL4Co was obtained by casting in a water-cooled copper mold by high-medium-high frequency melting in a gas. This alloy is made into 35 mesh by stamp mill.
After coarsely pulverizing, the material was finely pulverized in an Ar atmosphere to an average particle size of 5 μm using a ball mill. 2. The obtained powder was heated in an Oe magnetic field. After pressure molding at a pressure of Q ton/crl, it was sintered at 1120°C for 2 hours in 99.99 qb linear purity 760'l'orrAr, and after sintering it was cooled to room temperature at a cooling rate of 500°C/min. Cooled. Further, aging treatment was carried out at 650° C. for each time shown in Table 1 to obtain a magnet according to the present invention. The results of the magnet properties and the temperature coefficient α (%/'C) t of the residual magnetic flux density (Br) of this alloy magnet are shown in Table 1 together with a comparative example (after sintering). Also, in Figure 2, 6
6Fe14C.

Post-sintering (curve A) and aging treatment of 6B14Nd alloy 65
The respective demagnetization curves after 0°C x 12Qmin (curve B) are shown.

Table 1 Example 2 Atomic percentage composition 54Fe 15B 16Nd 2Y 1
An alloy f of 3Co was melted in an Ar gas arc and then cast in a water-cooled copper mold. This alloy is stamped and milled to 50%
After coarse grinding under mesh, the average particle size is 3μ in an organic solvent.
The mixture was finely ground in a ball mill. 15% of the obtained powder
After pressure molding in a KOe magnetic field at a pressure of 1.5 ton/-d, it was sintered at 1175°C for 4 hours in 99.999% pure 250 TorrAr, and after sintering, the cooling rate was 180 ton/-d.
'C/fnin to cool to room temperature. 3 more X
Aging treatment was performed in a vacuum of 10-5 Torr at each temperature shown in Table 2 for 2 hours to obtain magnets according to the present invention. Magnet property results and temperature coefficient α (%) of residual magnetic flux density (Br)
/°C) t-shown in Table 2 together with a comparative example (after sintering).

Example 3 Fe-B-kL having the atomic percentage composition shown in Table 3
・CO alloy obtained by melting in an iAr gas arc and then casting into a water-cooled copper mold. This alloy is stamped and milled to produce 40 mes
After coarsely pulverizing the powder to a particle size of 7 μm or less, it was pulverized in an organic solvent using a gall mill to an average particle size of 7 μm. The obtained powder was press-molded in a magnetic field of 15 KOe at a pressure of 1, Q ton/cJ, and then 9
1060 in 180 TorrAr with 9.999% purity
℃ for 2 hours, and after sintering the cooling rate was 350℃/m i
It was rapidly cooled to room temperature at n. Another 600 Torr
Aging treatment was performed in Ar at a temperature of 725° C. for 2 hours to obtain a magnet according to the present invention. Magnet property 2 and temperature coefficient α of Br (
%/°C) is shown in Table 3 together with a comparative example that does not contain f.

Table 3 Example 4 Fe-B-kL-C having the following atomic percentage composition.

The alloy was melted in an iAr gas arc and then cast into a water-cooled copper mold. After coarsely pulverizing this alloy to 25 mesh or less using a stamp mill, it was ball-milled in an organic solvent to an average particle size of 4 μm.
Finely ground in a mill. The obtained powder was heated to 1.5
After pressure molding at a pressure of ton/ctA, 99.999
It was sintered at 1025° C. for 2 hours in 380 TorrAr with a high purity, and after sintering, it was rapidly cooled to room temperature at a cooling rate of 250° C./min. Furthermore, aging treatment was performed at 700° C. for 4 hours in 650 TorrAr to complete the magnet according to the present invention. The results of the magnet properties are shown in Table 4 along with a sample without any aging treatment (comparative example).

Table 4

[Brief explanation of the drawing]

Figure 1 shows Co in Fe-Co-B-lt alloy.
It is a graph showing the relationship between the content of sulfur and Curie single point Tc (6). FIG. 2 shows an example of the present invention (66Fe 14 Co
6 B14, Nd) is a graph of the demagnetization curve. Applicant Sumitomo Special Metals Co., Ltd. Agent Patent Attorney Asahi Kato Figure 1 (77-x) Fe-xCo・8B-15NdCO 100% x (%) Figure 2 66Fe14Co6B14Nd (KOe) Procedural amendment ( (Spontaneous) February 28, 1980 Commissioner of the Japan Patent Office Kazuo Wakasugi 1 Description of the case Patent Application No. 90802 of 1988 (filed on May 25, 1988) 2 Name of the invention Permanent magnet material and its manufacturing method 3 Amendment Applicant 5 Date of amendment order Voluntary action 6 Column for detailed explanation of the invention in the specification subject to amendment 7 Contents of the amendment As shown in Appendix 1, the column for detailed explanation of the invention in the specification Correct as follows. (1) On page 8, line 11, add "(other rare earth elements, Ca, Mg, Fe, Ti, C, 0, etc.)" after "impurities". (2) Page 11, line 9, "10-2 TOrr"
Corrected to lo TorrJ. (3) Delete "(See Figure 1)" from the last line of page 15 to the first line of page 16. (4) Delete "(See Figure 2)" on page 16, line 4. (5) Page 17, line 3 rCuJ (7) Next r, Ca. Add Mg, O, Si, etc. (6) Line 5 on the same page, r, Ca, M before "etc."
g. 0. Add SiJ. (7) In line 7 of the same page, add "rCa, Mg each 4% or less, 0.2% or less, Si 5% or less" before "However". May 23, 1980 Commissioner of the Patent Office Kazuo Wakasugi 1 Indication of $ 1980 Patent Application No. 90802 (filed on May 25, 1980) 2 Name of the invention Permanent magnet Materials and manufacturing methods thereof 3 Relationship with the person making the amendment Name of applicant Sumitomo Special Metals Co., Ltd. 5 Date of amendment order Voluntary 6 Number of inventions increased by the amendment None 7 Detailed description of the invention in the specification subject to amendment Column 8: Contents of the amendment As shown in the attached sheet, the column for detailed explanation of the invention in the specification is amended as follows. , 1) Correct “0.2 to 206 C/min” in the second line of page 15 to “0.2°C/min to 20°C, /se CJ.” 2) Correct the 20th line of page 15 ``(See Figure 1)'' in the first line of page 16 is deleted from . 3) Delete "(See Figure 2)" on the 4th line of page 16. , 4) Page 21 Table 3 Fifth Example (, 38Fe6B9Nd
2Ho45Co) value r6.9J to "8°9" r2
0.3J was corrected to r24.3J, and the sixth embodiment (75F
elOB1ONd5Ce) column, "(Comparative example)" is corrected to "Comparative example (after sintering)". that's all

Claims (2)

[Claims] (1) It is 8 to 30% as an atomic percentage (where R is at least one of the rare earth elements). An alloy powder with an average particle size of 0.3 to 80 μm consisting of 2 to 28% B, 50% or less Co (excluding C. 0%), and the balance Fe2 and unavoidable impurities is molded.9
A permanent magnet material which is sintered at 00 to 1200°C and heat treated at 350°C to the sintering temperature after sintering. (2) 8 to 30% R as an atomic percentage (however, R is)'
at least one type of rare earth element). A process of forming an alloy powder with an average particle size of 0.3 to 80 μm consisting of 8.50% or less of Co (excluding all COO%) of 2 to 28% and the balance Fe and unavoidable impurities, reducing or non-oxidizing A method for producing a permanent magnet material, comprising the steps of sintering at 900 to 1200°C in a neutral atmosphere, and heat treating at 350°C to the sintering temperature after sintering.