JPS61111514A - Manufacturing method for permanent magnet - Google Patents

Abstract

PURPOSE:To form a truly circular cylindrical or cylindrical permanent magnet easily at low cost and without any defect by molding alloy powder having Fe, B and R as its main constituents in a magnetic field while applying the magnetic field in the direction of the maximum radius of an elliptic cylindrical body and sintering the molded body. CONSTITUTION:In molding an alloy powder of which main constituents are R (provided that r is an at least one kind of rare earth elements including V) of 8-30 atomic %, B of 2-28 atomic % and Fe of 42-90 atomic %, a shape of a dice is made to be an ellipsoid having its maximum diameter in the direction of the magnetic field and its minimum diameter in the direction perpendicular to that of the magnetic field. Raw material powder is filled in a molded space and molded in the magnetic field while applying the magnetic field in the direction of the major diameter of the ellipsoid. Sintering and aging treatment of the obtained molded body make it possible to obtain sintered permanent magnet of an Fe-B-R series having an anisotropy in the radial direction of a circular cylinder or a cylinder and superior magnetic characteristics of (BH)max of 25 MGO8 or more.

Description

Detailed Description of the Invention Field of Application This invention relates to a method for manufacturing Fe-B-R based sintered permanent magnets having excellent magnetic properties. The present invention relates to a method of manufacturing a permanent magnet that can produce one type of R-based sintered permanent magnet.

BACKGROUND ART As permanent magnet materials containing rare earth elements as their main components, RCos and RZCoy magnets, whose main components are carbon and carbon, have excellent magnetic properties, and can be used, for example, in small, high value-added magnetic circuits, etc. However, there are problems such as rare resources, unstable supply, and high prices.

Although rare earth cobalt magnets containing a large amount of
It is used in applications that require weight reduction, such as permanent magnets that are cylindrical or cylindrical and have magnetic anisotropy in the radial direction, such as for meters and motors.

On the other hand, the present applicant previously proposed a Fe-B-R-based permanent magnet (R is at least one rare earth element including Y) as a new high-performance permanent magnet that does not contain expensive chips (patent application). No. 57-145072, patent application No. 57-16
No. 6663, Patent Application No. 1982-200204, Patent Application No. 1982
-5813). This permanent magnet uses resource-rich light rare earth materials such as ceramics and circles as R, and F.

It is an excellent permanent magnet that has B and R as its main components and exhibits an extremely high energy product of over 25MGOag.

Generally, when manufacturing such a permanent magnet having a cylindrical shape and having field orientation in the radial direction, in the case of rare earth cobalt river stone, the difference in shrinkage rate due to the magnetic field direction of the magnetic press and the sintering in the n-angle direction from the magnetic field. is less than 1%, and there is almost no difference between them. Therefore, rare earth Kobal 1-based magnet alloy powder is molded into the required columnar or cylindrical shape in a magnetic field, and the molded body is sintered. Due to the low strength of the body, the difference in shrinkage rate in the radial and axial directions, and the unevenness of the powder during molding, cracks and chips may occur during sintering, processing, and inspection. There was an easy problem.

However, this Fa-B-R based sintered permanent magnet cannot be obtained using the same method as the conventional rare earth cobalt based permanent magnet, which has a cylindrical or cylindrical shape and has magnetic anisotropy in the radial direction. This is difficult because the difference in shrinkage rate due to sintering in the direction of the magnetic field and in the direction perpendicular to the magnetic field is 5% or more, and there was a problem that a right circular columnar or cylindrical shape could not be obtained.

OBJECTS OF THE INVENTION The object of the invention is to provide a method for manufacturing a permanent magnet that can easily and inexpensively obtain a right circular columnar or cylindrical F·-BR based sintered permanent magnet without any defects.

Structure and effect of the invention This invention provides a perfect circular columnar or cylindrical F・-B-
As a result of various studies aimed at manufacturing methods that can obtain R-based sintered permanent magnets, we found that in the case of F-BR-based sintered permanent magnets, the magnetic field direction of the magnetic field press and the sintering direction perpendicular to the magnetic field are Since the difference in shrinkage rate due to solidification is 5% or more, when a magnetic field is applied in the direction of the maximum diameter of the elliptical cylinder and the molded body is molded in a magnetic field and this molded body is sintered, it becomes a perfect circular column or cylinder. It has been discovered that a sintered magnet having magnetic anisotropy in the radial direction can be manufactured without producing defects such as cracks, VL warps, and chips.

That is, the present invention provides a method for manufacturing a sintered permanent magnet having a cylindrical or cylindrical radial magnetic anisotropy, in which R (where R is at least one of the rare earth elements containing Y) is used.
species) 8 at% to 30 at%, B 2 at% to 28 at%
, when molding an alloy powder whose main component is Fe42 atomic % to 90 atomic % in a magnetic field, it is formed into an ellipse having a maximum diameter in the magnetic group orientation direction and a minimum diameter in the direction perpendicular to the magnetic anisotropy. This is a method for producing a permanent magnet, which is characterized in that the permanent magnet is molded into a body, molded in a magnetic field, and then sintered to obtain a perfectly circular cylindrical or cylindrical sintered body.

For example, the present invention provides a die shape for molding in a magnetic field, with a maximum diameter f in the direction of the magnetic field and a minimum diameter f in the direction perpendicular to the direction of the magnetic field.
An ellipsoid having a shape of By doing so, (B H) max 25M G
17 is a Fe-B-R based sintered permanent magnet that exhibits a cylindrical or circular n-shaped radial anisotropy that exhibits extremely excellent magnetic properties of Oe.

In addition, in J3 of the method of this invention, the ratio of the maximum diameter to the minimum diameter of the molded product is preferably in the range of 1.03 to 1.15,
Outside this range, the shape of the sintered body will not be a substantially perfect cylinder or cylinder, and the processing allowance after sintering will increase, resulting in a decrease in product yield.

In the method of this invention, the term "right circle" in the shape of the sintered body after sintering means a circle within a range in which outside diameter polishing can be carried out without any problem, and usually the roundness has an outside diameter tolerance of ±3% or less. It is.

Further, it is preferable that the F·-El-R based sintered permanent magnet obtained according to the present invention is used with a surface coating such as plating, chemical conversion treatment, paint coating, etc. applied to the magnet surface.

Reasons for limiting the alloy powder for permanent magnets The reasons for limiting the composition of the REIFI-based cylindrical sintered magnet according to this invention will be explained below.

The rare earth light SR used in the F-B-R based sintered permanent magnet of this invention encloses yttrium (Y) and contains light rare earth and f
l, a rare earth element including earth, at least one of these, preferably Nd.

Mainly light rare earths such as Pr, or Nd.

A mixture with pr etc. is used.

Also, one type of R is usually sufficient, but in practice 2)
I! It is not possible to use the above mixtures (Mitushmetal, dididium, etc.) for reasons such as availability, Sm, Y,
La, Cc, Gd, etc. can be used as a mixture with other R1, especially Nd, Pr, etc.

% J), this R does not have to be a pure rare earth element, and may contain impurities that are unavoidable in production within an industrially available range.

R (at least one rare earth element including Y) is W
It is an essential element in current Fe-EIR permanent magnets, and if it is less than 8 at%, the crystal structure becomes a cubic structure similar to that of α-iron, so it has poor magnetic properties, especially high coercive force. is not obtained, and if it exceeds 30 at %, the R-rich nonmagnetic phase increases, the residual magnetic flux density (Br) decreases, and a cylindrical shape with excellent properties is obtained.

Cylindrical sintered magnet cannot be 4q. Therefore, the rare earth element is in the range of 8 atomic % to 30 atomic %.

Further, it is necessary that the light rare earth metal accounts for 50% or more of R. In addition, 1 to 30% of R is replaced with heavy rare earth D.
y, Tb, )-1o, Gd, Er, Yb+7), the coercive force and the maximum energy product can be improved in one way.

B is a new FI EI R-based permanent magnet,
It is an essential element, and if it is less than 2 atomic %, it will form a rhombohedral structure and a high coercive force (iHc) will not be obtained, and if it exceeds 28 atomic %, B-rich nonmagnetic phase will increase, and the residual magnetic flux density ( Br ) decreases, making it impossible to obtain an excellent cylindrical sintered stone. Therefore, B is 2 atomic % to 28
The range is atomic percent.

Fe is an essential element in new F・-15-R permanent magnets, and if it is less than 421 species i; Since it is not possible to obtain Fe, the content of Fe is 42% to 90%.
Contains.

In addition, in the magnet alloy of this invention, a part of F.
Replacement with F can improve the temperature characteristics without impairing the magnetic properties of the resulting magnet, but if the amount of cou exchange exceeds 50% of F, the magnetic properties will deteriorate. Undesirable. In addition, several percent of other metal elements or nonmetallic elements may be contained.

Further, the alloy for a cylindrical sintered magnet of the present invention has a main phase of a compound having a square grain structure with a grain size in the range of 1 to 100, and has a volume ratio of 1% to 50. % of non-magnetic phase.

Examples Example A An F-BR based sintered permanent magnet alloy powder having a composition of 15 m -28-5Go-72F@ in atomic % and an average particle size of 3I was prepared, with a molding space having an elliptical cross section, Its maximum diameter is 2
Fill a die with a diameter of 5 mm and a radius of 23 mm, and make 10
The magnetic field of KOe was oriented in the maximum radial direction, and molding was performed in the magnetic field with the pressure of 2 paddles.

%i%, the molded body was heated at 00°C for 2 hours in Ar
A cylindrical radially anisotropic Fe-E3R-based sintered permanent magnet is produced by sintering it under medium conditions, followed by forced cooling, and aging treatment at 600°C for 2 hours in roughly Ar. was created.

The shape of the sintered body is 20 mmφ and 5 m wide.
1n, the outer diameter tolerance was within 10.3 mm.

1'? The cylindrical sintered permanent magnet is [3r 12.3
kG, 1)-1c 13.8 kos, (B H)
It had magnetic properties of max 35.7M Gos.

Example B In atomic %, 14t & 2Pr 2Dy-7B-7
Fs B with an average particle size of 2.5I with a composition of 5Fm
-R-based sintered permanent magnet alloy powder is molded so that the cross section of the molding space is elliptical, the maximum diameter is 13.1 mm, and the small diameter Ii is 12.
1 type 1 type 1 type 1. The major axis of the core is 4.3 mm, and the minor axis is 4.
Fill the die with the maximum diameter and major axis direction in the same direction between 0 and 2 t.
Molding was carried out in a magnetic field at a pressure of J.

The obtained molded body was sintered under the conditions of 00°C, 2 hours and 1 m in Ar, then forced cooling, and further sintered at 60°C in Ar.
A cylindrical radially anisotropic Fe BR based sintered permanent magnet according to the present invention was produced by aging at 0° C. for 2 hours.

The shape of the obtained sintered body is 10.5mmφX 3.5mm
φX was 20 mm, and the outer diameter and inner diameter tolerances were within ±0.2 mm.

The cylindrical sintered permanent magnet shown is 3r type 1. 7 kg
, iHc 18.5 koe, (B tl ) g
The magnetic properties of Iax 29.8MGOe were (1).

Comparative Example C Medium m%, Sm27. OCo47,6 Fa 12.
A rare earth cobalt magnet alloy powder having a composition of +-Ni 5,4-false 7.9 and an average particle size of 3.5f was placed in a circular molding space with a cross section of 12.4mmφ and a center of 4.1Mφ.
A core of 10 KOe was placed and filled in the I
With the tooth oriented in the radial direction, molding was carried out during IS at a pressure of 2 t4.

The q molded body was sintered under the conditions of 1220°C for 2 hours in Ar, and step 9! ! The magnet was rapidly cooled in liquid nitrogen and then aged at 800° C. for 4 hours to produce a rare earth cobalt cylindrical radianol anisotropic permanent magnet using a conventional manufacturing method.

The shape of the obtained sintered body is 10.5nvnφX 3.5m
mφ×20 mm, and the outer diameter and inner diameter tolerances were within ±0.2 barrel.

The obtained cylindrical sintered permanent magnet has a 3r 12.3 kG
.

iHc 13.8 kQs, (8H) 1lax 35
．． It had magnetic properties of 7M Gos.

The F・-El-R based sintered permanent magnets of Examples A and B according to the present invention are both conventional rare earth cobalt based sintered magnets (
It has a circular shape with the same precision as Comparative Example C), and the bending strength is 25kC compared to 1214 of Comparative Example C).
It had the strength of IJ and was extremely strong, with no defects such as cracks or chips during cooling or processing after sintering.

Applicant: Sumitomo Special Konkutsu Co., Ltd. Jikotewa"L: Nrll Masaguchi January 25, 1985 1988 Patent Application No. 233684 2 Name of the invention Method for manufacturing permanent magnets 3 Person making the amendment 'Relationship to the case Applicant 4, Agent 5, Detailed description of the invention: Column 6 of "Detailed description of the invention", δ of the amendment Pages 1 to 12 of the specification are attached as attached d3. Amended However, the "title of the invention" and "scope of claims" should be changed. m Book 1, Name of the invention Method for manufacturing permanent magnets 2, Claim 1 Magnetic anisotropy in the radial direction of a columnar or cylindrical shape In the method for manufacturing a sintered permanent magnet having
atomic%, B2 atomic% to 28 atomic%, Fe42 atomic% to 9
When molding alloy powder with an earth component of 0 atomic % in a magnetic field, it is formed into an elliptical molded body having a maximum diameter in the direction of magnetic anisotropy and a minimum diameter in a direction perpendicular to the magnetic anisotropy, and is then lath molded. A method for producing a permanent magnet, which comprises post-sintering to obtain a perfectly circular columnar or cylindrical sintered body.

3. Detailed Description of the Invention Industrial Field of Application This invention is directed to Fa B-
The present invention relates to a method for manufacturing an R-based sintered permanent magnet, and relates to a method for manufacturing a permanent magnet that can produce a perfectly circular cylindrical or cylindrical Fa-BR sintered permanent magnet.

BACKGROUND ART As a permanent EHE material whose main component is rare earth elements, S
RCo5 series and R2C0I7 series ta whose main component is myasa
B has excellent magnetic properties and is often used in applications such as small, high-value-added magnetic circuits, etc. However, there are problems such as it being a scarce resource and its supply being unstable and expensive. There is Sm, C above.

Rare earth cobalt magnets containing many sides are expensive, but due to their high magnetic properties, they are especially suitable for high performance, miniaturization,
It is used in applications that require light weight, such as permanent magnets that are cylindrical or cylindrical and have magnetic anisotropy in the radial direction, such as for meters and motors.

On the other hand, the present applicant has previously developed an Fa-8R series (R is at least one rare earth element including Y) permanent 'f! as a new high-performance permanent magnet that does not contain expensive Sm. proposed i-stone (Patent Application No. 145072, 1982, Patent Application No. 1983)
sses3@, Japanese Patent Application No. 1983-200204, Japanese Patent Application No. 1983
No. 8-5813). This permanent magnet uses resource-rich light rare earth metals, mainly cylindrical metals, as R, and Fa.

It is an excellent permanent magnet that contains B and R as its main components and exhibits an extremely high energy level exceeding 25) iGOe.

Generally, when manufacturing such a permanent magnet having a cylindrical shape and anisotropy in the radial direction, in the case of rare earth cobalt magnets, the difference in shrinkage rate due to sintering in the magnetic field direction of the magnetic field press and in the direction perpendicular to the magnetic field is 1% or less, and there is almost no difference, so rare earth cobalt magnet alloy powder is molded into the required columnar or cylindrical shape in a magnetic field, and the molded body is sintered to produce it, but the strength of the sintered body Due to the small shrinkage rate difference between the radial and axial directions and the unevenness of the powder during molding, cracks and chipping were likely to occur during sintering and subsequent processing and inspection. .

However, with this FsBR-based sintered permanent magnet, it is impossible to produce 1q of sintered permanent magnets that are columnar or cylindrical and have magnetic anisotropy in the radial direction using the same method as conventional rare earth cobalt-based permanent magnets. This is difficult because the difference in shrinkage rate due to sintering in the direction of the magnetic field and in the direction perpendicular to the magnetic field is more than 5%.
There was a problem in that a perfectly round columnar or cylindrical shape could not be obtained.

OBJECT OF THE INVENTION The object of the invention is to provide a method for manufacturing a permanent magnet that can easily and inexpensively produce 1 q of perfectly circular cylindrical or cylindrical Fil-BR based sintered permanent magnets without any defects.

Structure and effect of the invention The present invention provides a perfect circular columnar or cylindrical Fa-B-
As a result of various studies aimed at manufacturing methods that can produce 1q of R-based sintered permanent magnets, we found that in the case of Fe-BR R-based sintered permanent magnets, sintering is performed in the m-field direction of the magnetic field press and in the direction perpendicular to the magnetic field. Since the difference in shrinkage rate is 5% or more, when a magnetic field is applied in the direction of the maximum diameter of the elliptical columnar body and this molded body is sintered in an in-field acid, it becomes a perfect circular cylinder or cylindrical shape. It has been discovered that a sintered magnet having magnetic anisotropy in the radial direction can be manufactured without producing defects such as cracks, cracks, etc.

That is, the present invention provides a method for manufacturing a sintered permanent magnet having a cylindrical or cylindrical radial magnetic anisotropy.
species) 8 atom% to 30 atom%, B22 atom to 28 atom%,
When molding alloy powder whose main component is 42 at% to 90 at% Fe in a magnetic field, it is formed into an ellipse having a maximum diameter in the direction of magnetic anisotropy and a minimum diameter in the direction perpendicular to the magnetic anisotropy. This is a method for producing a permanent magnet, which is characterized in that the permanent magnet is molded into a body, molded in a magnetic field, and then sintered to obtain a perfectly circular cylindrical or cylindrical sintered body.

In this invention, for example, the die shape for performing molding in a magnetic field is an ellipsoid having a maximum diameter in the direction of the magnetic field and a minimum diameter in a direction perpendicular to the direction of the magnetic field, and a molding space is filled with raw material powder having the following composition. By molding in a magnetic field while applying a magnetic field in the direction of the maximum diameter of the ellipse, sintering the obtained molded body, and roughly aging it, it is possible to achieve extremely excellent magnetic retention exceeding (BH) max 25) IGOe. An Fa BR based sintered permanent magnet having a cylindrical or cylindrical radial anisotropy having the following properties can be obtained.

In addition, in the method of this invention, the ratio of the maximum diameter to the minimum diameter of the molded body is preferably in the range of 1.03 to 1.15, and outside this range, the shape of the sintered body is approximately cylindrical or completely circular. It does not become cylindrical, and the machining allowance after sintering increases, resulting in a lower product yield.

In the method of this invention, the term "right circle" in the shape of the sintered body after sintering means a circle within a range where outer diameter polishing can be carried out without any problem, and usually the outer diameter tolerance is within ±3% of the roundness. be.

Further, it is desirable to use the FaBR type to sintered permanent magnet obtained by the present invention by applying a surface coating such as plating, chemical conversion treatment, paint coating, etc. to the magnet surface.

Reasons for limiting the alloy powder for permanent magnets The reasons for limiting the composition of the RBFe-based cylindrical sintered magnet according to the present invention will be explained below.

The rare earth element R used in the Fa-B R-based sintered permanent magnet 5 of the present invention is a rare earth element including ythtrium (Y), light rare earths, and heavy rare earths, and at least one of these, preferably Nd. , Pr, etc., or a mixture with Nd, Pr, etc. is used.

In addition, one type of R is usually sufficient, but in practice, it is preferable to use a mixture of two or more types (Mitushmetal, dididim, etc.) for reasons such as convenience of availability, Sm, Y,
La, Ce, Gd, etc. can be used as a mixture with Nd, Pr, etc. in the R1 layer.

Note that this R does not have to be a pure rare earth element, and may contain impurities that are unavoidable in production within an industrially available range.

R (at least one rare earth element including Y) is an essential element in the new Fa B-R permanent magnet, and if it is less than 8 at%, the crystal structure is the same as α-iron. Because it becomes a cubic structure, the l@i magnetic properties and high coercive force are not maintained at 1q, and when it exceeds 30 at%, the R-rich nonmagnetic phase increases, and the residual magnetic flux density (Br) decreases. A cylindrical 7-cylindrical sintered magnet with excellent properties cannot be obtained.Therefore, the rare earth element content is set in the range of 8 at.% to 30 at.%.

Further, it is necessary that the light rare earth metal accounts for 50% or more of R. In addition, 1 to 30% of R is replaced with heavy rare earth D.
y, Tb, I(o, Gd, Er, back 1 of Yb
Replacing it with more than 100% of the species can improve the coercive force and the maximum energy product by 1q.

B is an essential element in the new Fe-BRR permanent magnet, and if it is less than 2 at%, it will form a rhombohedral structure and high coercive force (iHc) cannot be obtained, and if it exceeds 28 at%,
The amount of B-rich nonmagnetic phase increases, and the residual magnetic flux density (Br)
As a result, an excellent cylindrical sintered magnet cannot be obtained. Therefore, B is in the range of 2 atomic % to 28 atomic %.

In the new Fs BR permanent magnet, Fe is
It is an essential element, and if it is less than 42 at%, the residual magnetic flux density (B
If r) decreases and exceeds 90 atom %, high coercive force cannot be obtained, so Fe is contained in the range of 42 atom % to 90 atom %.

In addition, in the magnet alloy of the present invention, replacing a part of Fa with Ra can improve the temperature characteristics without impairing the magnetic properties of the resulting magnet. If it exceeds 50%, the magnetic properties will deteriorate, which is not preferable. In addition, several percent of other metal elements or non-metallic elements may be contained.

Further, the alloy for a cylindrical sintered magnet of the present invention has a compound having a tetragonal crystal structure with a grain size in the range of 1 to 1001 m as a main phase, and has a volume ratio of 1% to 50%. It is characterized by containing a non-magnetic phase.

Examples Example A A Fa BR based sintered permanent magnet alloy powder having a composition of 15Nd2B5Co-72Fa in atomic % and an average particle size of 3ts was molded into a molding cavity r1 with an elliptical cross section and a maximum diameter of 25 mm. , a die with a minimum diameter of 23 mm was filled, a magnetic field of 10 koe was oriented in the direction of the maximum diameter, and 2
Molding was performed in a magnetic field at a pressure of t4.

The obtained molded body was heated at 00'C for 2 hours in Ar.
The cylindrical radially anisotropic Fa B R based sintered permanent stone according to the present invention was obtained by sintering under the following conditions, followed by forced cooling and aging treatment for 2 hours at 600'C in rough Ar. Created.

The shape of the jqed sintered body is 20 mmφ and 5 mm in height.
The outer diameter tolerance was within ±0.3 mm.

The obtained cylindrical sintered permanent type 1 5 has Br 12.3 k
G, 1flc 13.8 koa, (8H) max 3
It had magnetic properties of 5.7 MGOa. Moreover, the density was 7.53 IJ4.

Example B In atomic %, 14Nd-2Pr 2Dy -7B -7
Fe B with an average particle size of 2.5 grains having a composition of 3Fa
The R-based sintered alloy powder for permanent magnets was made into a molding space with an elliptical cross section, a maximum diameter of 13.1 mm, and a minimum diameter of 12.1 mm.
1 mm, the major axis of the core is 4.3 mm, the minor axis is 4.0 mm, and the above maximum diameter and major axis direction are filled in the same direction,
A magnetic field of 10 kOa was oriented in the maximum radial direction, and molding was performed in the magnetic field at a pressure of 2 t4.

The obtained molded body was sintered at 00°C for 2 hours in Ar, then forcedly cooled, and
A cylindrical radially anisotropic Fs BR type sintered permanent magnet according to the present invention was produced by subjecting it to an aging treatment at .degree. C. for 2 hours.

The shape of the obtained sintered body is 10.5 mmφ x 3.5 mmφ
X20 mm, and the outer diameter and inner diameter tolerances were within ±0.2 mm.

The obtained cylindrical sintered permanent magnet was 3r type 1. 7 kg
, 1) fc IF3.5 koa, (Bl)max
It had magnetic properties of 29.88 GDa. Further, the density was 7.37 gdr.

Comparative Example C Sm27.% by weight. OCo47.6 Fe12.1
A rare earth cobalt magnet alloy powder having a composition of -NL 5.4-Ca7.9 and an average particle size of 3.5- is formed into a circular molding space with a cross section of 12.4 mmφ and a 4.1 type T1 in the center.
The material was filled into a die having a core of mφ, and a magnetic field of 10 koe was oriented in the radial direction, and molding was performed in the magnetic field at a pressure of 2 t and 7.

(The resulting molded body was sintered at 1220"C for 2 hours in Ar, then rapidly cooled in liquid nitrogen, and roughly aged at 800°C for 4 hours. Rare earth cobalt based cylindrical radial anisotropy permanent f!
I made one stone.

The shape of the obtained sintered body is 10.5mmφX 3.5nn
r+φ×20w+m, outer diameter and inner diameter tolerance is ±0.2m
It was within m.

The obtained cylindrical sintered permanent magnet has a Br of 10.6 kG.
, iHc 7.4 kOa, (BH)maX 27.
It had magnetic properties of 58 GOa. Also, the density is 8.
50 (It was IJ.

The Fs B R based sintered permanent magnets of Examples A and B according to the present invention are both conventional rare earth cobalt based sintered fj
It has a circular shape with the same accuracy as 1 stone (Comparative Example C), and the bending strength is roughly 12 to 14 in Comparative Example C.
It had a strength of 25-4, which was extremely high, and there were no defects such as cracks, chips, etc. during cooling or processing after sintering.

Claims (1)

[Claims] 1. In a method for manufacturing a sintered permanent magnet having a cylindrical or cylindrical radial magnetic anisotropy, R (where R is at least one rare earth element including Y) 8 at % to 30
atomic%, B2 atomic% to 28 atomic%, Fe42 atomic% to 9
When molding alloy powder whose main component is 0 atomic % in a magnetic field, it is formed into an elliptical molded body having a maximum diameter in the direction of magnetic anisotropy and a minimum diameter in a direction perpendicular to the magnetic anisotropy. A method for producing a permanent magnet, which comprises post-sintering to obtain a perfectly circular columnar or cylindrical sintered body.