JP3077995B2 - Permanent magnet material, cooling roll for producing permanent magnet material, and method for producing permanent magnet material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an Fe-R containing R (R is a rare earth element containing Y, the same applies hereinafter), Fe or Fe and Co, and B.
The present invention relates to a -B-based and Fe-Co-RB-based permanent magnet material, a cooling roll used for producing the permanent magnet material, and a method for producing the permanent magnet material.

<Conventional Technology> As a rare earth magnet having high performance, an Sm-Co based magnet manufactured by powder metallurgy and having an energy product of 32MGOe is mass-produced.

However, this has the disadvantage that the raw material prices of Sm and Co are high. Among rare earth elements, elements having a small atomic weight, for example, cerium, praseodymium, and neodymium are more abundant and cheaper than samarium. Fe is less expensive than Co.

Therefore, in recent years, R-Fe-B-based magnets such as Nd-Fe-B have been developed, and Japanese Patent Application Laid-Open No. 60-9852 discloses a high-speed quenching method.

The rapid quenching method is a method of quenching a molten metal by colliding the molten metal with the surface of a cooling substrate to obtain a metal such as a ribbon, a flake, and a powder. Depending on the type of the cooling substrate, a single-roll method, a twin-roll method, It is classified into the disc method, etc.

Among these high-speed quenching methods, the single-roll method uses one cooling roll as a cooling base. Then, the alloy in the form of a molten metal is ejected from the nozzle, collides with the surface of the cooling roll rotating with respect to the nozzle, and is brought into contact with the surface of the cooling roll to cool the alloy from one direction. Get the alloy. The cooling rate of the alloy is usually controlled by the peripheral speed of the cooling roll.

The single roll method is widely used because it has few mechanically controlled parts, has high stability, is economical, and is easy to maintain.

The twin-roll method is a method in which a pair of cooling rolls is used, and cooling is performed from two opposite directions with a molten alloy in between.

<Problems to be Solved by the Invention> In the single roll method, generally, when the cooling speed of the side of the alloy that contacts the cooling roll surface (hereinafter, referred to as the roll surface side) is set to an optimum range, the opposite side (hereinafter, referred to as the roll surface side) is set. The cooling rate on the free surface side is insufficient, and the roll surface side has a preferable crystal grain size, but the free surface side has coarse grains, so that a high coercive force cannot be obtained.

On the other hand, when cooling is performed so that the crystal grain size on the free surface side is in a preferable range, the cooling rate on the roll surface side becomes extremely high, and the roll surface side becomes almost amorphous, so that high magnetic characteristics cannot be obtained.

For this reason, in the related art, the peripheral speed of the cooling roll is set so as to maximize the number of crystal grains having a preferable particle diameter as the entire rapidly cooled alloy, and this is set as the optimum peripheral speed.

However, the optimum peripheral speed determined as described above is in a very narrow range, and varies depending on the alloy composition,
For example, it is about ± 0.5 to 2 m / s around 25 m / s. For this reason, the peripheral speed must be strictly controlled, and mass production at low cost is difficult.

By the way, the preferable range of the crystal grain size region (the thickness in the cooling direction) is almost constant and does not depend much on the thickness of the ribbon. Improves. When the injection amount of the molten alloy from the nozzle is constant, the thickness of the ribbon depends on the peripheral speed of the cooling roll.Thus, if the peripheral speed is increased, a thin ribbon can be obtained. Since the optimum peripheral speed is determined by the composition of the above, it is necessary to replace the cooling roll itself in order to increase the peripheral speed and reduce the thickness of the ribbon, which is not practical.

On the other hand, if the injection amount of the molten alloy is reduced, the thickness of the ribbon decreases, but the molten metal of the R-Fe-B alloy easily reacts with the material constituting the nozzle. easy. For this reason, when mass-producing industrially, the nozzle diameter cannot be unnecessarily reduced.

Furthermore, even when the cooling is performed at the above-described optimum peripheral speed, a difference of about 10 times in the crystal grain size occurs between the roll surface side and the free surface side, and the region where the preferable crystal grain size is obtained is extremely narrow. As a result, various magnetic characteristics become non-uniform in the cooling direction of the rapidly cooled alloy.

For this reason, when the quenched alloy is pulverized, magnet particles having high magnetic properties and magnet particles having low magnetic properties are mixed in the obtained magnet powder, and this magnet powder is dispersed in a resin binder to form a bonded magnet. , High magnetic properties cannot be obtained as a whole magnet.

On the other hand, in the twin-roll method, since there is no free surface, the crystal grain diameters on the opposing surfaces of the ribbon are substantially equal. However, the cooling rate is different between the roll surface and the center of the ribbon,
As in the single roll method, the difference in crystal grain size poses a problem.

The present invention has been made in view of these circumstances, and in producing an R-Fe-B-based permanent magnet material by bringing a molten alloy into contact with the surface of a chill roll and rapidly cooling the same, a wide area of the permanent magnet material is used. In order to obtain a permanent magnet material with high magnetic properties by realizing a preferable crystal grain size in the region, and to further increase the peripheral speed range of the cooling roll to obtain a permanent magnet material with high magnetic properties, that is, the peripheral speed of the magnetic properties The purpose is to reduce dependency.

<Means for Solving the Problems> Such an object is achieved by the present invention of the following (1) to (9).

(1) R (where R is at least one of rare earth elements including Y) and Fe or a molten alloy containing Fe and Co and B are brought into contact with the surface of the cooling roll to form A permanent magnet material produced by cooling from two directions or two opposing directions, comprising a substrate and a surface layer formed on the surface of the substrate,
The thermal conductivity of this surface layer is lower than the thermal conductivity of the base material, and the material constituting this surface layer is Cr, Ni, Co, V alone or an alloy containing at least one of these elements. The center line average roughness of the surface in contact with the surface of the cooling roll
Ra is 0.05-1.5 μm, average crystal in the area near the free surface when using the single-roll method of 1/5 of the magnet thickness or in the central area between the opposing main surfaces when using the twin-roll method Particle size d is 0.01 to 2 μm
And a ratio d / p of d to the average crystal grain size p in the region near the roll surface of 1/5 of the magnet thickness is 4 or less.

(2) R (where R is at least one of rare earth elements including Y), and a molten alloy containing Fe or Fe and Co and B are brought into contact with the surface of the cooling roll to form A permanent magnet material produced by cooling from two directions or two opposing directions, comprising a substrate and a surface layer formed on the surface of the substrate,
The thermal conductivity of the surface layer is 0.6 J / (cm · s · K) or less, and the material constituting this surface layer is Cr, Ni, Co, V alone or at least one of these elements. Manufactured using a cooling roll that is an alloy containing, the center line average roughness of the surface in contact with the cooling roll surface
Ra is 0.05-1.5 μm, average crystal in the area near the free surface when using the single-roll method of 1/5 of the magnet thickness or in the central area between the opposing main surfaces when using the twin-roll method Particle size d is 0.01 to 2 μm
Wherein the ratio d / p of d to the average crystal grain size p in the region near the roll surface at 1/5 of the magnet thickness is 4 or less.

(3) The permanent magnet material according to the above (1) or (2), wherein the permanent magnet material is manufactured by being cooled from one direction, and has a thickness in a normal direction of a surface in contact with a cooling roll of 45 μm or less.

(4) The above-mentioned (1), wherein the surface in contact with the cooling roll is cooled from two opposite directions and the thickness in the normal direction of the surface in contact with the cooling roll is 90 μm or less.
Or the permanent magnet material according to (2).

(5) The center line average roughness Ra of the surface in contact with the cooling roll is:
The permanent magnet material according to any one of (1) to (4), wherein the surface of the cooling roll has a center line average roughness Ra or less.

(6) The permanent magnet material according to any one of (1) to (5), wherein the region near the surface in contact with the cooling roll contains a constituent element near the surface of the cooling roll.

(7) A molten alloy containing R (where R is one or more rare earth elements including Y), Fe or Fe and Co, and B is cooled to obtain 1 / th of the magnet thickness. 5. The average crystal grain size d in the region near the free surface when using the single-roll method or in the central region between the opposing main surfaces when using the twin-roll method is 0.01 to 2 μm.
And d, a cooling roll for producing a permanent magnet material having a ratio d / p of 4 or less to an average crystal grain size p in a region in the vicinity of a roll surface having a thickness of 1/5 of the magnet thickness, The roll has a substrate and a surface layer formed on the surface of the substrate, the center line average roughness Ra of the surface in contact with the molten alloy is 0.07 to 1.7 μm, and the thermal conductivity of the surface layer is Is lower than the thermal conductivity of the base material and the material constituting this surface layer is Cr, Ni, Co, V alone or an alloy containing one or more of these elements. Cooling roll.

(8) R (where R is at least one rare earth element including Y), Fe or a molten alloy containing Fe and Co, and B is cooled to obtain 1 / th of the magnet thickness. 5. The average crystal grain size d in the region near the free surface when using the single-roll method or in the central region between the opposing main surfaces when using the twin-roll method is 0.01 to 2 μm.
And a cooling roll for producing a permanent magnet material having a ratio d / p of d and an average crystal grain size p in a region near a roll surface of 1/5 of the magnet thickness is 4 or less, The cooling roll has a substrate and a surface layer formed on the surface of the substrate, the center line average roughness Ra of the surface in contact with the molten alloy is 0.07 to 1.7 μm, and the heat conduction of the surface layer The degree is 0.6 J / (cm · s · K) or less, and the material constituting the surface layer is Cr, Ni, Co, V alone or an alloy containing at least one of these elements. A cooling roll for a permanent magnet material.

(9) A molten alloy containing R (where R is one or more rare earth elements including Y), Fe or Fe and Co, and B is injected from the nozzle to the nozzle. A method for producing a permanent magnet material, comprising a step of cooling the alloy from one direction or two opposing directions by bringing the alloy into contact with the surface of a rotating cooling roll, wherein: A method for producing a permanent magnet material using a cooling roll for producing a permanent magnet material.

<Operation> In the present invention, a permanent magnet material is manufactured by quenching a molten R-Fe-B alloy by a single roll method or a twin roll method.

In the single roll method and the twin roll method, the cooling rate of the alloy increases as the peripheral speed of the cooling roll increases. this is,
This is because when the peripheral speed increases, the surface area of the cooling roll supplied per unit time increases.

In the present invention, in these high-speed quenching methods, the center line average roughness Ra of the surface in contact with the molten alloy is used as a cooling roll.
Is used in the above range.

The alloy melt that comes into contact with the surface of the cooling roll at the time of quenching is in close contact with the projection on the surface of the cooling roll, but has low adhesion to the depression, and the adhesion to the depression is further reduced as the peripheral speed increases. Therefore, as the peripheral speed increases, the contact area between the surface of the cooling roll and the alloy decreases, and the cooling speed decreases.

Therefore, when the peripheral speed of the cooling roll is increased in the present invention, an increase in the cooling speed due to an increase in the surface area of the supplied cooling roll and a reduction in the cooling speed due to the surface of the cooling roll of Ra are integrated, and as a result, The cooling rate hardly changes. Therefore, in the permanent magnet material obtained by the present invention, the crystal grain size hardly changes even if the peripheral speed of the cooling roll fluctuates, and the peripheral speed dependence of magnetic properties is extremely low.

For this reason, it is not necessary to strictly control the peripheral speed of the cooling roll, and the practical life of the apparatus is extended, and mass production can be performed at low cost.

Further, since a substantially constant cooling rate can be obtained over a wide range of peripheral speeds, the thickness of the permanent magnet material can be freely changed by changing the peripheral speed, and the magnetic characteristic fluctuation at this time is extremely small.

Accordingly, a thin permanent magnet material can be obtained without reducing the diameter of the molten alloy injection nozzle, and a permanent magnet material having a high content of crystal grains having a preferable particle diameter can be manufactured with high mass productivity.

Further, even when a permanent magnet material having the same thickness is manufactured at the optimum peripheral speed, high magnetic properties can be obtained by using the above-described cooling roll of Ra.

In the permanent magnet material obtained by using the cooling roll of the present invention, Ra of the roll surface is in the above range, and Ra of the roll surface is usually equal to or lower than Ra of the cooling roll surface.
This is because as the peripheral speed of the cooling roll increases, the adhesion between the alloy and the cooling roll decreases as described above.

<Specific Configuration> Hereinafter, a specific configuration of the present invention will be described in detail.

In the present invention, a molten alloy containing R (where R is one or more rare earth elements including Y), Fe or Fe and Co, and B is injected from a nozzle, and The alloy is cooled from one direction or two opposing directions by contacting the surface of a rotating cooling roll to produce a permanent magnet material.

That is, in the present invention, the single roll method or the twin roll method is used for quenching the molten alloy.

In the present invention, a cooling roll having a center line average roughness Ra of 0.07 to 1.7 μm, preferably 0.15 to 1.2 μm on the surface in contact with the molten alloy is used as the cooling roll used in the single roll method and the twin roll method. If Ra of the cooling roll is less than the above range, even if the peripheral speed is increased, the adhesion between the surface of the cooling roll and the alloy does not decrease, and the peripheral speed dependence of the cooling speed increases. If the Ra of the chill roll exceeds the above range, the surface roughness of the chill roll becomes too large to be ignored with respect to the thickness of the ribbon-shaped permanent magnet material, which leads to uneven thickness of the ribbon.

The center line average roughness Ra is specified in JIS B0601.

There is no particular limitation on various configurations of the cooling roll other than the surface Ra, but in order to maintain Ra of the cooling roll surface within a predetermined range, in the present invention, the base material and the surface layer formed on the base material surface are separated. It is preferable to use a cooling roll having the same.

The base material of the cooling roll is selected from, for example, copper, a copper-based alloy, silver, a silver-based alloy, and the like. When used for high-speed quenching of an alloy having a low melting point, aluminum and an aluminum-based alloy can also be used. Copper or a copper-based alloy is preferably used because of its high conductivity and low cost. As the copper-based alloy, a copper beryllium alloy or the like is preferably used.

The surface layer formed on the surface of such a base material prevents the change of Ra on the surface of the cooling roll due to collision and contact of the molten alloy, and is made of a material having higher hardness and higher wear resistance than the base material. Is done.

Such surface layer constituent materials include Cr, Ni, Co, N
b, V alone or an alloy containing one or more of the above elements, such as stainless steel and hardened steel. In the case of an alloy, these elements are contained in an amount of 20 wt% or more.

In the cooling roll used in the present invention, it is preferable that the thermal conductivity of the surface layer is lower than the thermal conductivity of the substrate. By using such a cooling roll, the cooling rate of a region of the permanent magnet material farthest from the surface in contact with the cooling roll (hereinafter, referred to as region D) and the region near the surface in contact with the cooling roll (hereinafter, region D) P)), the difference between the average crystal grain size in the region D and the average crystal grain size in the region P can be reduced.

Specifically, the thermal conductivity of the surface layer is 0.6 J / (cm · s ·
K) or less, and particularly preferably 0.45 J / (cm · s · K) or less. When the thermal conductivity exceeds the above range, only the cooling roll side of the permanent magnet material is rapidly cooled to reduce the crystal grain size, and the difference between the average crystal grain size in the region P and the region D increases. The lower limit of the thermal conductivity of the surface layer is not particularly limited. However, when the thermal conductivity is less than 0.1 J / (cm · s · K), heat transfer becomes poor, so that only the vicinity of the surface of the surface layer becomes high temperature, and image sticking occurs. In some cases.

In addition, the thermal conductivity in this specification is a value at normal temperature and normal pressure.

Considering the stability of the cooling roll surface Ra and the durability of the cooling roll as described above, the material forming the surface layer is preferably selected from materials having a high melting point and high wear resistance, and specifically, Selected from various materials.

There is no particular limitation on the thickness of the surface layer, and various conditions such as the method of forming the surface layer, the thermal conductivity of the material constituting the surface layer, the size of the cooling roll, and the relative speed between the cooling roll and the molten metal are considered. However, when applied to the single-roll method or the twin-roll method, 0.005 to 3 mm, particularly 0.01 to 0.
Preferably, it is 5 mm.

There is no particular limitation on the method of forming the surface layer, and depending on the material and the like, liquid phase plating, vapor phase plating, thermal spraying, bonding of thin plates,
It can be selected from various methods such as shrink fitting of a cylindrical member. After formation of the surface layer, the surface may be polished as necessary to obtain a predetermined Ra.

The base material of the cooling roll is not particularly limited and can be selected as long as it is made of a material that satisfies the relationship of the thermal conductivity as described above. For example, from various materials such as the aforementioned copper and copper-based alloys It only has to be selected.

The preferred range of the thermal conductivity of the substrate is 1.4 J / (cm
S · K) or more, especially 2 J / (cm · s · K) or more.

A preferred combination of the base material and the surface layer material is a copper alloy base material and a Ni, Co or Cr surface layer,
Of these, a Co or Cr surface layer is more preferred, and a Cr surface layer is even more preferred.

When a cooling roll having a surface layer is used, the region P contains constituent elements near the surface of the cooling substrate, that is, Cr, Co, Ni, V, Nb, etc., which are constituent elements of the surface layer. This is what was diffused from the surface of the cooling base into the permanent magnet material during rapid quenching. In this case, the content of the surface layer constituent elements is 10 to 500 p in the range of 20 nm or less from the main surface in the thickness direction.
pm.

Hereinafter, the case where the single roll method is used for the rapid quenching method will be described in detail.

The size of the chill roll is not particularly limited, and may be an appropriate size according to the purpose, but is usually 150 to 1500 mm in diameter and 2 in width.
It is about 0 to 100 mm. Further, a hole for water cooling may be provided at the center of the roll.

The peripheral speed of the roll varies depending on various conditions such as the composition of the roll surface layer, the composition of the permanent magnet material, the target structure, and the presence or absence of heat treatment, but is preferably 1 to 50 m / s, particularly 5 to 35 m / s. It is preferable that

When the peripheral speed is less than the above range, most of the crystal grains of the obtained permanent magnet material become too large. On the other hand, when the peripheral speed exceeds the above range, most of the peripheral speed becomes amorphous and the magnetic characteristics are deteriorated.

In the present invention, even when the peripheral speed of the cooling roll changes, the rate of change of the cooling speed is extremely small, so that a permanent magnet material having good magnetic properties can be obtained in such a wide peripheral speed range.

When the one-roll method is used, a thin strip-shaped permanent magnet material is usually obtained.

In this case, the thickness of the permanent magnet material is preferably set to 45 μm or less. With such a thickness, the difference in the average crystal grain size between the roll surface side and the free surface side can be reduced. According to the present invention, since a substantially constant cooling rate can be obtained in a wide peripheral speed range,
A thin strip-shaped permanent magnet material having a thickness of 45 μm or less can be obtained without reducing the diameter of the molten alloy injection nozzle.

Note that the thickness of the permanent magnet material is preferably set to 10 μm or more. If the thickness is less than 10 μm, the surface area is unnecessarily increased in a powdering step and a handling thereof in forming a bonded magnet, so that the magnet is easily oxidized.

When the twin-roll method is used for the rapid quenching method, there is no particular limitation on the roll size and the interval between the two rolls, but usually the diameter is
~ 300mm, width about 20 ~ 80mm, the interval between both rolls is
It is preferable to set it to about 0.02 to 2 mm.

It is to be noted that rapid cooling may be performed by applying pressure between the two rolls during cooling of the molten metal.

The production conditions in the twin roll method may be in accordance with the single roll method described above, but the peripheral speed of the cooling roll is 0.3 to 20 m.
/ s is preferable.

The shape of the permanent magnet material obtained by the twin-roll method is usually a ribbon or flake. And its thickness is
It is preferably 90 μm or less. The reason for this is to reduce the difference in crystal grain size in the permanent magnet material, as in the case of the single roll method described above, and according to the present invention, the diameter of the injection nozzle for the molten alloy is reduced. However, by increasing the peripheral speed of the cooling roll, a permanent magnet material having such a thickness can be easily obtained.

In the twin-roll method, the thickness of the permanent magnet material is
The thickness is preferably 10 μm or more.

The permanent magnet material of the present invention obtained as described above,
Ra of the roll surface is 0.05 to 1.5 μm, preferably 0.13 to 1.0 μ
m.

The permanent magnet material of the present invention preferably has substantially only a main phase having a tetragonal crystal structure, or has such a main phase and an amorphous and / or crystalline sub-phase.

A tetragonal compound stable as an RTB compound (T is Fe and / or Co) is R ₂ T ₁₄ B (R = 11.76 at%, T = 82.
36 at%, B = 5.88 at%), and the main phase is substantially formed from this compound. The sub-phase exists as a grain boundary of the main phase.

A permanent magnet material manufactured using a cooling roll having a surface layer as described above, that is, a cooling roll in which the thermal conductivity of the surface layer is lower than the thermal conductivity of the substrate, is a region D.
Can be set to d / p ≦ 4, particularly d / p ≦ 2.5.

Although the lower limit of d / p is usually 1, a good value of about 1.5 ≦ d / p ≦ 2 can be easily obtained by using the cooling roll as described above.

In this specification, the area D and the area P are defined as follows.

The main surface of the permanent magnet material manufactured by the one-roll method or the twin-roll method is a surface in contact with the cooling roll and a surface facing the cooling roll. In the present specification, the thickness direction of the permanent magnet material means the normal direction of the main surface.

When the one-roll method is used, the above-described region D is a region near the main surface facing the main surface that has contacted the cooling roll during cooling,
That is, it is a so-called free surface vicinity region, and the region P
Is a so-called roll surface vicinity region.

In this case, the widths of the region D and the region P in the magnet thickness direction are both 1/5 of the magnet thickness.

When the twin-roll method is used, the region D is a central region between the opposing main surfaces, and the region P is a region near the roll surface.

Also in this case, the width in the magnet thickness direction of the region D and the region P is set to 1/5 of the magnet thickness.

The measurement of the average crystal grain size in these regions can be performed by a transmission electron microscope.

When the cooling roll is used, the average crystal grain size d in the region D can be easily obtained as 0.01 to 2 μm, particularly 0.02 to 1.0 μm.
005 to 1 μm, particularly 0.01 to 0.75 μm, can be easily obtained.

If the average particle size is less than this range, the coercive force is reduced because it is close to an amorphous state, and if it exceeds this range, a high energy product cannot be obtained.

The width of the crystal grain boundary is 0.001 to 0.1 μm in the region D.
m, especially about 0.002 to 0.05 μm.
The thickness can be about 0.001 to 0.05 μm, particularly about 0.002 to 0.025 μm. If the width of the crystal grain boundary is less than this range, a high coercive force cannot be obtained, and if it exceeds this range, the saturation magnetic flux density decreases.

The permanent magnet material manufactured according to the present invention may be subjected to a heat treatment for improving characteristics.

The composition of the alloy melt used in the present invention is R (where R is at least one of rare earth elements including Y), Fe or
There is no particular limitation on the composition as long as it contains Fe and Co and B, and the effect of the present invention can be realized with any composition, but since the magnetic properties of a permanent magnet are high, It preferably has the following composition.

 R: 5 to 20 at%, B: 2 to 15 at% and Co: 0 to 55 at%, with the balance being substantially Fe.

 More preferably, R: 5 to 17 at%, B: 2 to 12 at%, and Co: 0 to 40 at%, with the balance being substantially Fe.

To further explain R, R is one or more rare earth elements including Y.
Particularly preferably contains Nd and / or Pr.
The content of Nd and / or Pr is preferably at least 60% of the total R.

In addition to the above elements, Zr, Nb, Mo, Hf,
One or more of Ta, W, Ti, V and Cr may be contained. These elements have an effect of suppressing crystal growth. Further, one or more of Cu, Mn and Ag may be contained. These elements have an effect of improving workability during plastic working. The total content of these additional elements is
It is preferably 15 at% or less. Further, in order to improve corrosion resistance, it is preferable that Ni is contained. Ni
Is preferably at most 30 at% in total with the above-mentioned additional elements.

Note that part of B may be replaced with one or more of C, N, Si, P, Ga, Ge, S and O. Replacement amount is 50% of B
The following is preferred.

Such a composition can be easily measured by an atomic absorption method, a fluorescent X-ray method, a gas analysis method, or the like.

<Example> Hereinafter, the present invention will be described in more detail by showing specific examples of the present invention.

[Manufacture of permanent magnet material using single roll method] Using a cooling roll having a 0.12 mm thick Cr surface layer formed by electrolytic plating on the surface of a copper beryllium alloy base material having a diameter of 500 mm and a width of 60 mm A permanent magnet material was produced. The thermal conductivity of the substrate was 3.6 J / (cm · s · K), and the thermal conductivity of the surface layer was 0.43 J / (cm · s · K).

 The Ra of the surface layer is shown in Table 1 below.

First, an alloy ingot having a composition of 8.5Nd-4Zr-7.5B-80Fe (the numerical value represents an atomic percentage) was produced by arc melting. The obtained alloy ingot was put into a quartz nozzle, and was melted by high-frequency induction heating.

This molten metal was rapidly quenched by a single roll method using the above-mentioned cooling roll to obtain a permanent magnet material sample. The obtained permanent magnet material sample was in a ribbon shape.

The nozzle diameter was 1.2 mmφ, the distance between the nozzle tip and the surface of the cooling roll was 0.5 mm, the molten metal injection pressure was 1 kg / cm ^2, and Ar gas was used for pressurization. Also, the atmosphere at the time of molten metal injection is
An Ar gas atmosphere of 15 Torr was used.

Circumferential speed of cooling roll, thickness of each sample, Ra, iHc
And (BH) max are shown in Table 1.

Further, the same cooling rolls were used in Sample Nos. 1-1 to 1-3 shown in Table 1, and 2-1 to 2-3 and 3-
The same cooling roll was used for each of 1-3 to 3-3. In the case of using each of these cooling rolls, shown in Table 1 iHc is the width of 80% or more to become the peripheral speed of the maximum value as v _80.
The larger this value, the lower the peripheral speed dependence of the magnetic properties.

In addition, each sample was cut in a direction in which its cross section could be easily observed, and the average crystal grain size d in the range from the free surface to 1/5 of the ribbon thickness (region D) and the thickness of the ribbon from the roll surface. The average crystal grain size p in a range (region P) up to 1/5 of the above was measured with a transmission electron microscope, and d / p was calculated. Table 1 shows the results
Shown in

[Manufacture of permanent magnet material using twin roll method] Using a cooling roll having a 0.12 mm thick Cr surface layer formed by electrolytic plating on a copper base material having a diameter of 200 mm and a width of 40 mm, a permanent magnet material was prepared. Was prepared.

 Table 2 shows the Ra of the surface layer.

First, an alloy ingot having a composition of 11.5Nd-8B-80.5Fe (the numerical value represents an atomic percentage) was produced by arc melting. The obtained alloy ingot was put into a quartz nozzle, and was melted by high-frequency induction heating.

This molten metal was rapidly quenched by a twin-roll method using the above cooling roll to obtain a permanent magnet material sample. The obtained permanent magnet material sample was flaky.

The distance between the rolls is 0.2mm, and the injection pressure of the molten metal is 1.2kg
/ cm ² and Ar gas was used for pressurization.

Circumferential speed of cooling roll, thickness of each sample, Ra, iHc
And a (BH) max, and v ₈₀ described above, are shown in Table 2.

The obtained ribbon is cut in a direction in which the cross section thereof can be easily observed, and the center portion between both main surfaces is cut from the average crystal grain size d in the range of 1/5 width of the ribbon thickness and the roll surface to the ribbon. Thick
The average crystal grain size p in the range up to 1/5 was calculated by measuring with a transmission electron microscope. Table 2 shows the results.

The effects of the present invention are apparent from the results of the above examples.

That is, the permanent magnet material manufactured using the cooling roll having the Ra within the range of the present invention exhibits a high coercive force iHc in an extremely wide peripheral speed range.

In each of the samples shown in Tables 1 and 2, a Cr content of 100 ppm was observed in a range of 20 nm or less from the roll surface. Also, in the case of using a cooling roll having a surface layer formed by Ni electroless plating film, Co sprayed film, shrink fitting of V or bonding of Nb thin plate, d / p is the same as in the case of Cr surface layer.
, And the content of surface layer constituent elements of 10 to 500 ppm was observed in the range of 20 nm or less from the roll surface of the permanent magnet material.

<Effects of the Invention> According to the present invention, the peripheral speed dependency of the magnetic properties of the permanent magnet material can be reduced, and a permanent magnet material having excellent magnetic properties can be manufactured with high mass productivity.

Continuation of the front page (56) References JP-A-1-170553 (JP, A) JP-A-2-54718 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B22D 11 / 06 C22C 38/00

Claims (9)

(57) [Claims] 1. R (where R is one of the rare earth elements including Y)
More than a species. ), And a permanent magnet material produced by contacting a molten alloy containing Fe or Fe and Co and B with a cooling roll surface to cool it in one direction or two opposing directions. Material, and a surface layer formed on the surface of the substrate, wherein the thermal conductivity of the surface layer is lower than the thermal conductivity of the substrate, and the material constituting the surface layer is Cr, Ni, Co , V or a cooling roll which is an alloy containing one or more of these elements, and the center line average roughness Ra of the surface in contact with the cooling roll surface
Is 0.05 to 1.5 μm, and the average crystal grain in the region near the free surface when using the single-roll method of 1/5 of the magnet thickness or in the central region between the opposite main surfaces when using the twin-roll method A permanent magnet material having a diameter d of 0.01 to 2 μm and a ratio d / p of d to an average crystal grain diameter p in a region near a roll surface of 1/5 of the magnet thickness is 4 or less. 2. R (where R is one of the rare earth elements including Y)
More than a species. ), And a permanent magnet material produced by contacting a molten alloy containing Fe or Fe and Co and B with a cooling roll surface to cool it in one direction or two opposing directions. And a surface layer formed on the surface of the base material, and the thermal conductivity of the surface layer is 0.6 J / (cm · s · K) or less, and the material constituting the surface layer is Cr, Manufactured using a cooling roll which is a simple substance of Ni, Co, V or an alloy containing one or more of these elements, and the center line average roughness Ra of the surface in contact with the cooling roll surface
Is 0.05 to 1.5 μm, and the average crystal grain in the region near the free surface when using the single-roll method of 1/5 of the magnet thickness or in the central region between the opposite main surfaces when using the twin-roll method A permanent magnet material having a diameter d of 0.01 to 2 μm and a ratio d / p of d to an average crystal grain size p in a region near a roll surface of 1/5 of the magnet thickness is 4 or less. 3. It is manufactured by cooling from one direction, and has a thickness in the normal direction of a surface in contact with the cooling roll of 45 μm.
The permanent magnet material according to claim 1, wherein: 4. The permanent magnet material according to claim 1, wherein the permanent magnet material is cooled from two opposite directions and has a thickness in a normal direction of a surface in contact with the cooling roll of 90 μm or less. 5. A center line average roughness of a surface in contact with a cooling roll.
The permanent magnet material according to any one of claims 1 to 4, wherein Ra is not more than a center line average roughness Ra of the cooling roll surface. 6. The permanent magnet material according to claim 1, wherein the region near the surface in contact with the cooling roll contains a constituent element near the surface of the cooling roll. 7. R (where R is one of the rare earth elements including Y)
More than a species. ) And Fe or a molten alloy containing Fe and Co and B were cooled, and the area near the free surface in the case of using a single roll method with a magnet thickness of 1/5 or a twin roll method was used. In this case, the average crystal grain size d in the central region between the opposing main surfaces is 0.01 to 2 μm, and the ratio d / of the average crystal grain size p in the region near the roll surface at 1/5 of the magnet thickness is d / A cooling roll for producing a permanent magnet material having p of 4 or less, wherein the cooling roll has a base material and a surface layer formed on the surface of the base material, and is in contact with a molten alloy. The center line average roughness Ra of the surface is 0.07 to 1.7 μm, the thermal conductivity of the surface layer is lower than the thermal conductivity of the base material, and the material constituting this surface layer is Cr, Ni, Co, V A cooling roll for producing a permanent magnet material, which is a simple substance or an alloy containing one or more of these elements. 8. R (where R is one of the rare earth elements including Y)
More than a species. ), Fe or a molten alloy containing Fe and Co and B was cooled, and the area near the free surface in the case of using the single roll method with a magnet thickness of 1/5 or the twin roll method was used. In the case, the average crystal grain size d in the central region between the opposing main surfaces is 0.01 to 2 μm, and the ratio d / of the average crystal grain size p in the region near the roll surface at 1/5 of the magnet thickness is d / A cooling roll for producing a permanent magnet material having p of 4 or less, wherein the cooling roll has a base material and a surface layer formed on the surface of the base material, and is in contact with a molten alloy. The center line average roughness Ra of the surface is 0.07 to 1.7 μm, and the thermal conductivity of the surface layer is
0.6 J / (cm · s · K) or less, and the material constituting this surface layer is Cr, Ni, Co, V alone or an alloy containing at least one of these elements. Cooling roll for magnet material. 9. R (where R is one of the rare earth elements including Y)
More than a species. ), Fe or a molten alloy containing Fe and Co and B is injected from a nozzle and brought into contact with the surface of a cooling roll rotating with respect to the nozzle so that the alloy is unidirectional or opposed. A method for producing a permanent magnet material, comprising a step of cooling from two directions, wherein the method comprises using the cooling roll for producing a permanent magnet material according to claim 7.