JPH10102215A - Iron base alloy for fine crystal permanent magnet and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an amorphous structure at a specified ratio or above by a melt quenching method at a roll circumferential speed by which stable industrial production is made possible, in an Fe-B-R compsn. in which the ratios of Pr and Nd are regulated to specified ones, by forming the compsn. into the one added with small amounts of Zr, Nb, Mo, Hf, Ta and W. SOLUTION: Alloy molten metal expressed by the compositional formula of T100-x-y Bx Ry Mz and in which the symbols (x), (y) and (z) limiting the compositional ranges satisfy, by at%, 15<=x<=30, 1<=y<=6 and 1<=z<=5 is rapidly cooled at 2 to 10m/sec roll circumferential speed by a melt quenching method using rapid cooling rolls and is subjected to crystallization heat treatment at 600 to 700 deg.C, where, in the formula, T denotes Fe or the one in which a part of Fe is substituted with one or more kinds among Co, Ni and Cr, R denotes one or more kinds of Or and Nd, and M denotes one or more kinds among Zr, Nb, Mo, Hf, Ta and W. By this method, the iron base alloy for a permanent magnet having an amorphous structure by >=90% and excellent in amorphousness formability can be mass-produced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an iron base for a permanent magnet as a base material of a fine crystal type isotropic magnet in which a compound phase having a Fe ₃ B type compound and a compound phase having an Nd ₂ Fe ₁₄ B type crystal structure coexist. Regarding the alloy, conventionally, in a liquid super-quenching method using a super-quenching roll, one or two types of Pr and Nd which are difficult to obtain an amorphous structure only under ultra-quenching conditions in which the roll peripheral speed is 15 m / sec or more are 1 to 1 In a 6 at% Fe-BR composition, a molten alloy having a composition to which a small amount of a specific additive element is added is rapidly quenched by a liquid quenching method at a roll peripheral speed at which stable industrial production is possible. The present invention relates to an iron-based alloy for a microcrystalline permanent magnet excellent in the ability to form an amorphous body and having an excellent amorphous forming ability, and a method for producing the same.

[0002]

2. Description of the Related Art As a permanent magnet applicable to various motors, actuators, magnetic circuits for magnetic sensors, magnet rolls and speakers, etc., it has a residual magnetic flux density Br of 10 kG or more and an average crystal grain size of 1 nm to 50 nm.
Fine crystalline isotropic permanent magnets in which a Fe ₃ B type compound having a thickness of nm and a compound phase having an Nd ₂ Fe ₁₄ B type crystal structure coexist have been developed.

[0003] In such a microcrystalline permanent magnet, a molten Fe-BR alloy having a specific composition is turned into an amorphous structure of 90% or more by a liquid super-quenching method, and then 600 ° C. It is manufactured by performing a crystallization heat treatment at a rate of temperature rise up to a processing temperature of 700 ° C. from 10 ° C./min to 50 ° C./min.

[0004] F having an amorphous structure of 90% or more
In order to obtain an eBR alloy, in a liquid quenching method using a quenching roll, for example, a single roll, a molten alloy quenching of 10 ⁵ ° C / sec or more can be achieved only when the roll peripheral speed exceeds 15 m / sec. The speed is required, and the ultra-quenching condition of the molten alloy satisfying the quenching speed is extremely narrow, and is not practical for industrial production.

[0005]

In order to obtain a quenching speed of the alloy melt of 10 ⁵ ° C / sec or more, in the above-mentioned liquid super-quenching method using a single roll, if the roll peripheral speed exceeds 15 m / sec, the The entrainment of the atmosphere gas due to the rotation of the roll increases, and not only the quenching speed fluctuates due to the gas entrapped between the molten alloy and the roll surface, but also the molten metal is splashed on the roll to stably produce a quenched ribbon. Can not do.

Further, damage to the roll surface caused by the molten alloy during the quenching of the molten alloy increases in proportion to the roll peripheral speed. There is a problem that the quenching condition is not constant due to the damage of the steel.

Further, in order to obtain a quenching rate of the alloy melt of 10 ⁵ ° C / sec or more, it is necessary to set the quenching rate of the alloy melt per unit area of the roll surface to 700 gr / sec or less.
In order to increase the throughput, the size of the liquid quenching device must be increased, which increases the manufacturing cost.

The present invention relates to Fe ₃ B type compounds and Nd ₂
In a method for producing an iron-based alloy for a permanent magnet having an amorphous structure of 90% or more and serving as a base material of a fine crystal type isotropic magnet in which a compound phase having an Fe ₁₄ B type crystal structure coexists, a quenching method of a liquid quenching method is used. In view of the fact that the conditions are severe and impractical for industrial production, the roll peripheral speed in the liquid quenching method using a quenching roll is set to 10 m / sec or less at which a quenched ribbon can be stably produced for industrial production, and 90% An object of the present invention is to provide an iron-based alloy for a microcrystalline permanent magnet capable of obtaining such an iron-based alloy for a permanent magnet having the above-mentioned amorphous structure, and a method for producing the same.

[0009]

Means for Solving the Problems In producing an iron-based alloy for a permanent magnet, which is a base material of a microcrystalline isotropic magnet having a residual magnetic flux density Br of 10 kG or more, the present inventors have employed a liquid quenching method. For the purpose of a method capable of stabilizing industrial production by relaxing the quenching condition, various studies were conducted on a method of obtaining a microcrystalline alloy having an amorphous structure of 90% or more with a roll peripheral speed of 10 m / sec or less. Pr, Nd
Is a composition in which one or two or more of Zr, Nb, Mo, Hf, Ta, and W are added to a small amount of a specific additive element in an Fe-BR composition of 1 to 6 at%. Thereby, the alloy melt is quenched by a liquid quenching method at a roll peripheral speed of 10 m / sec or less that enables stable industrial production,
The present inventors have found that an amorphous structure of 90% or more can be obtained, and that an iron-based alloy for a microcrystalline permanent magnet having excellent amorphous forming ability can be obtained, and the present invention has been completed.

That is, in the present invention, the composition formula is represented by T
_100-xy B _x R _y M _z (where T is Fe or a part of Fe is replaced by one or more of Co, Ni or Cr, R is one or two of Pr and Nd, M Is Zr, N
b, Mo, Hf, Ta, W, or more), and the symbols x, y, and z that limit the composition range satisfy the following values and have an amorphous structure of substantially 90% or more, This is an iron-based alloy for microcrystalline permanent magnets that becomes a microcrystalline permanent magnet by crystallization heat treatment. 15 ≦ x ≦ 30 at% 1 ≦ y ≦ 6 at% 1 ≦ z ≦ 5 at%

Further, the present invention provides a composition formula of T _100-xy B _x
R _y M _z (where, T is a part of Fe or Fe Co, Ni
Or substituted by one or more types of Cr, R is P
one or two of r and Nd, M is Zr, Nb, Mo, H
f, Ta, W, or two or more), and the symbols x, y, and z, which limit the composition range, satisfy the above values. The roll peripheral speed is determined by a liquid quenching method using a quenching roll. Is rapidly cooled to 2 m / sec to 10 m / sec, and substantially cooled to 90 m / sec.
This is a method for producing an iron-based alloy for a microcrystalline permanent magnet, which has an amorphous structure of at least% and is subjected to a crystallization heat treatment at 600 ° C. to 700 ° C. to become a microcrystalline permanent magnet.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION

Reasons for Limiting Composition Rare earth element R is one or two of Pr and Nd.
Is less than 1 at%, a compound phase having an Nd ₂ Fe ₁₄ B type crystal structure does not precipitate during crystallization heat treatment, iHc of 2 kOe or more cannot be obtained, and if it exceeds 6 at%, 10 kG
Since the above residual magnetic flux density Br cannot be obtained, 1 at% to
The range is 6 at%. Preferably, 2 at% to 5 at
% Is good.

When B is less than 15 at%, an amorphous structure of 90% or more cannot be obtained even by using the ultra-quenching method, iHc of less than 1 kOe can be obtained even by heat treatment, and when it exceeds 30 at%, Since the squareness of the demagnetization curve is significantly reduced and Br of 10 kG or more cannot be obtained,
t% to 30 at%. Preferably, 15 at
% To 20 at% is good.

One or more of Zr, Nb, Mo, Hf, Ta, and W greatly contribute to the improvement of the amorphous forming ability of the present alloy, and a quenching roll is required to obtain an amorphous structure of 90% or more. In the liquid quenching method used, the peripheral speed of the roll can be reduced to 2 m / sec to 10 m / sec. However, if the content is less than 1 at%, such an effect cannot be obtained. If the content exceeds 5 at%, crystallization heat treatment is performed. Since the temperature becomes higher than the decomposition temperature of the Nd ₂ Fe ₁₄ B type compound phase which is a metastable phase and iHc cannot be obtained, the range is 1 at% to 5 at%. Preferably, 1 at% to 2 at% is good.

The occupancy of the above elements is occupied by Fe, and by replacing a part of Fe with Co and Ni, the squareness of the depletion curve is improved and the maximum energy product (B
H) An improvement in max and heat resistance can be obtained.
Substantially improves iHc.

Reasons for Limiting Manufacturing Conditions The liquid quenching method in the present invention includes a liquid quenching method using a quenching roll and a strip casting method which is an alloy casting method. The alloy melt having the above specific composition is cooled by a liquid quenching method, preferably in a reduced-pressure inert gas atmosphere, at a roll peripheral speed of 2 m / sec to 10 m / sec, and a cooling speed of the alloy melt of 10 ² ° C / sec to 10 ^5. C./sec. Can produce a quenched ribbon with a suitable quenched structure and stable quality.
An amorphous structure of 0% or more can be obtained.

When a Cu roll is used as the quenching roll,
When the roll peripheral speed is less than 2 m / s, an amorphous structure of substantially 90% or more cannot be obtained, and when the roll peripheral speed exceeds 10 m / sec, entrainment of atmospheric gas by the rotating roll is large, and Atmospheric gas enters between the molten alloys, losing uniformity of quenching conditions,
Since the molten metal is splashed off on the roll and a quenched ribbon cannot be produced stably, the roll peripheral speed is 2 m / s or more.
Limited to 10 m / s. A more preferable roll peripheral speed is 3 m / s to 10 m / s.

Magnetization Method As described above, a molten alloy having a specific composition is converted into a metal structure having substantially 90% or more of an amorphous structure by a liquid quenching method.
From 10 ° C / min to the processing temperature of
By performing the crystallization heat treatment at 50 ° C./min, the Fe ₃ B-type compound having soft magnetism, α-Fe and Nd ₂ Fe
₁₄ A hard magnetic compound phase having a B-type crystal structure coexists in the same powder, each constituent phase has an average crystal grain size of 1 nm to 50 nm, an intrinsic coercive force iHc ≧ 2 kOe, and a residual magnetic flux density Br.
A microcrystalline permanent magnet having magnetic properties of ≧ 10 kG can be obtained.

[0019]

【Example】

Example 1 No. 1 in Table 1. 1 to No. Purity 9 so as to have a composition of 6.
9.5% or more of Fe, Zr, Nb, Mo, Hf, Ta,
Using metals of W, Ni, Co, Cr, B, Nd and Pr,
Weigh so that the total amount is 30 g, and the diameter is 0.8 m at the bottom.
m orifice into a quartz crucible and pressure 5
Melting is performed by high frequency heating in an Ar atmosphere maintained at 6 cmHg, and after the melting temperature is set to 1300 ° C., the molten metal surface is pressurized with Ar gas, and rapidly cooled at room temperature at a roll peripheral speed shown in Table 1 by a Cu quenching. The molten metal is spouted from the height of 0.7 mm on the outer peripheral surface of the single roll to obtain a width of 2 mm to 3 mm and a thickness of 70 mm.
A rapidly quenched alloy ribbon of μm to 180 μm was produced.

The obtained quenched ribbon has the characteristic X of Cu-Kα.
As a result of examination by a line, it was confirmed that substantially 90% or more of the structure was amorphous. The constituent phase is Fe ₃
B is a multi-phase structure in which B phase and Nd ₂ Fe ₁₄ B phase are mixed.
In each of these phases, r, Nb, Mo, Hf, Ta, W, Ni, Co, and Cr are replaced with part of Fe. The average crystal grain size of each phase was 30 nm or less.

The quenched ribbon is heated to 580 ° C. in Ar gas.
600 ° C. or more was heated at a heating rate of 20 ° C./min, kept at the heat treatment temperature shown in Table 1 for 7 minutes, then cooled to room temperature, and the ribbon was taken out, and the width was 2 mm to 3 mm and the thickness was 2 mm.
Table 2 shows the results of preparing samples having a length of 0 μm to 40 μm and a length of 3 mm to 5 mm, and measuring the magnetic characteristics using a VSM.

Comparative Example Under the same conditions as in Example 1, No. 7-No. A quenched alloy ribbon was prepared using Fe, B, and R having a purity of 99.5% so as to obtain a composition of No. 9. As a result of an examination of the sample by the characteristic X-ray of Cu-Kα, No. The quenched ribbon of 7 is α
No.-Fe as a main phase, a metal structure in which Fe ₃ B phase and Nd ₂ Fe ₁₄ B phase are mixed. 8 and no. 9 quenched ribbons
It was a mixed structure of an α-Fe phase and amorphous.

No. 7-No. After heat-treating the quenched ribbon No. 9 under the same conditions as in Example 1, the magnetic properties were measured using VSM. Table 2 shows the measurement results. In addition, the metal structure after heat treatment was a metal structure in which each sample contained α-Fe as a main phase and a Fe ₃ B phase and an Nd ₂ Fe ₁₄ B phase were mixed, and the average crystal grain size was about 100 nm. No. 1 to N
o. 6 was coarser.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

As is clear from the examples, the iron-based alloy for a microcrystalline permanent magnet having an amorphous structure of 90% or more according to the present invention has a temperature of about 60% from the temperature at which crystallization starts.
By performing a crystallization heat treatment at a heating rate of 10 ° C./min to 50 ° C./min to a treatment temperature of 0 ° C. to 700 ° C., a Fe ₃ B-type compound having soft magnetism, α-Fe and Nd ₂ F
The hard magnetic compound phase having the e ₁₄ B type crystal structure coexists in the same powder, and the average crystal grain size of each constituent phase is 1 nm to 50 nm.
And the specific coercive force iHc ≧ 2 kOe, the residual magnetic flux density B
A microcrystalline permanent magnet having magnetic characteristics of r ≧ 10 kG can be obtained.

That is, in the present invention, one or two of Zr, Nb, Mo, Hf, Ta, and W are used in a Fe—BR composition in which one or two of Pr and Nd are 1 to 6 at%.
By making a composition to which at least one or more kinds of specific additive elements are added, the molten alloy is quenched by a liquid quenching method at a roll peripheral speed of 10 m / sec or less, which enables stable industrial production, and
% Or more of an amorphous structure, and Fe ₃ B
-Based alloys for permanent magnets with excellent amorphous forming ability, which are the base materials of isotropic magnets of the fine crystal type in which the compound phase and the compound phase having the Nd ₂ Fe ₁₄ B type crystal structure coexist, in a stable industrial production It can be mass-produced and offered at low cost.

Claims (2)

[Claims] 1. The composition formula is represented by T _100-xy B _x R _y M _z (where T
Is Fe or a part of Fe substituted with one or two of Co, Ni or Cr, and R is one or two of Pr and Nd.
Species, M is one or more of Zr, Nb, Mo, Hf, Ta, W), and symbols x, y,
An iron-based alloy for a microcrystalline permanent magnet, wherein z satisfies the following values, has an amorphous structure of substantially 90% or more, and becomes a microcrystalline permanent magnet by crystallization heat treatment. 15 ≦ x ≦ 30 at% 1 ≦ y ≦ 6 at% 1 ≦ z ≦ 5 at% 2. The composition formula is represented by T _100-xy B _x R _y M _z (where T
Is Fe or a part of Fe substituted with one or two of Co, Ni or Cr, and R is one or two of Pr and Nd.
Species, M is one or more of Zr, Nb, Mo, Hf, Ta, W), and symbols x, y,
The molten alloy whose z satisfies the following values was rolled at a roll peripheral speed of 2 m / sec to 10 m /
A method for producing an iron-based alloy for a fine crystal permanent magnet, which is rapidly cooled in seconds, has an amorphous structure of substantially 90% or more, and is subjected to a crystallization heat treatment at 600 ° C. to 700 ° C. to become a fine crystal permanent magnet. 15 ≦ x ≦ 30 at% 1 ≦ y ≦ 6 at% 1 ≦ z ≦ 5 at%