JPH091296A - Rapid cooling roll for production of magnet alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain R-Fe-B alloy slab excellent in corrosion resistance by specifying the surface roughness near surface center part and the surface roughness near both ends of a rapid cooling roll for production of magnet respectively and specifying the relationship between both surface roughness. SOLUTION: A rapid cooling roll 1 for production of magnet alloy, by which R-Fe-B or R-Fe-B-C magnet alloy molten metal is rapidly solidified, has a surface roughness Ra2 of 0.1-10μm at a center neighborhood of part 4 in the direction of width L of the wear resistant metal surface arranged on the surface in contact with molten metal, that is, T=0.5-0.9L. Further, the surface roughness Rag near both end neighborhood part 5, that is, t=0.005-0.25L is 2-20μm, the relationship of surface roughness of each region is Ra1 >Ra2 . A base metal 2 of rapid cooling roll 1 is preferably Cu or Cu alloy of high heat conductivity, Cr, Cr alloy, Ni, Ni alloy are preferably for a wear resistant metal layer. By this method, the alloy slab, in which difference in a grain size in the width direction of slab and variance in magnetic property reduced, is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an R-Fe-B system or R-F system having a fine homogeneous structure in which a molten magnet alloy melted in a vacuum melting furnace is poured from a nozzle into a quenching roll.
According to the improvement of the quenching roll for producing the e-B-C system magnet alloy, the surface in the vicinity of the center and both sides in the width direction of the quenching roll that comes into contact with the molten metal are each made to have a specific surface roughness, It is possible to cast a slab having homogeneous fine crystal grains in the width direction of the slab so that the surface roughness in the vicinity of both sides is higher than the surface roughness in the vicinity of the center. The present invention relates to a quenching roll for producing a Fe-B type or R-Fe-B-C type magnet alloy.

[0002]

2. Description of the Related Art A typical R-Fe as a high performance permanent magnet
The B-type permanent magnet (Japanese Patent Laid-Open No. 59-46008) has high magnet characteristics due to the structure having the main phase of the ternary tetragonal compound and the R-rich phase. R-Fe-B based permanent magnets of various compositions have been proposed so that they can be used in a wide range of fields, including peripheral devices, and exhibit various magnet characteristics depending on the application.

The R-Fe-B system permanent magnets have extremely excellent magnetic properties, but have problems in corrosion resistance and temperature characteristics. A method of coating the surface of the magnet with a corrosion resistant metal film or a resin film has been proposed (JP-A-60-54406 and JP-A-60-63901), and in order to improve the temperature characteristics of the magnetic characteristics of the magnet, the magnet has been proposed. Proposed to replace a part of Fe in the composition with Co (Japanese Patent Laid-Open No. 59-64733).
However, there is a problem that the cost is still insufficient and the cost of the magnet increases.

Recently, a part of B of the R-Fe-B system magnet is replaced with C
R-Fe-B- for improving the corrosion resistance and temperature characteristics by generating a boundary phase having excellent corrosion resistance by substitution with
A C-based magnet has been proposed (JP-A-3-82744). The R-Fe-BC system magnet has a B content of 2 at%.
It is characterized in that it is below and contains a large amount of C.

That is, if a part of B is replaced by C,
The R ₂ Fe ₁₄ B tetragonal crystal of the main phase becomes an R ₂ Fe ₁₄ (B _1-x C _x ) tetragonal crystal in which a part of B is replaced by C, but the crystal structure is the same and the grain boundary The phase changes from the R-rich phase to the R-rich phase (R-Fe-C phase) with good corrosion resistance, and in the R-Fe-Co-BC system magnet in which a part of Fe is replaced by Co, the main phase is R ₂ Fe ₁₄ B having the same crystal structure as tetragonal R ₂ (F
e _1-x Co _x ) ₁₄ (B _1-y C _y ) becomes a tetragonal crystal, and the grain boundary phase is from an R-rich phase to an R-rich phase (R-F) with good corrosion resistance.
e-Co-C phase), but when a large amount of C is contained in the magnet, C reacts with R (rare earth element) to easily form an RC phase (rare earth carbide), which causes An RC phase is produced in the sintered magnet.

In short, in the R-Fe-B-C type magnet, R reacts with C to form the R-C phase, and R is consumed, so that R-Fe-B is required to obtain the required magnetic characteristics. It requires a larger amount of R than the system magnet. Therefore, since there are many RC phases that do not contribute to the magnetic characteristics, the abundance of the main phase is reduced, Br is lower than that of the R—Fe—B based magnet, and expensive R
Since a large amount is required, the cost is increased, and there is a problem that the magnetic characteristics are deteriorated and varied with the increase of the oxygen content.

In the R-Fe-B-C magnet, the molten alloy is cast in a mold to prepare an ingot, and the ingot is crushed.
Pulverization, molding, sintering, magnetizing by powder metallurgy method of aging treatment, or solution treatment of the ingot or coarse powder after crushing of the ingot, pulverizing, and magnetizing by the powder metallurgy method Although the corrosion resistance and the temperature characteristics are improved and improved, the magnetic characteristics of the R-Fe-B-C magnet are (BH) ma.
x was at most about 38 MGOe. Further, the R-Fe-B-C type magnet has extremely poor squareness of the demagnetization curve, and is demagnetized with respect to temperature and reverse magnetic field as compared with the R-Fe-B type magnet having the same size and shape. There was an easy problem.

In order to increase the residual magnetic flux density (Br) of the R-Fe-B system or R-Fe-B-C system sintered magnet,
1) Ferromagnetic phase, R ₂ Fe ₁₄ B phase or R ₂ F which is the main phase
possible to increase the abundance of _{e 14 (B 1-x C} x) phase, 2) to increase the density of the sintered body to a theoretical density of the main phase, 3) further, the main phase crystal grain easy magnetization axis direction of the It is required to increase the degree of orientation.

That is, in order to achieve the above item 1),
The composition of the magnet is R ₂ Fe ₁₄ B or R ₂ Fe ₁₄ (B _1-x
It is important to approach the stoichiometric composition of C _x ), but the alloy ingot having the above composition melted and cast in a mold is used as a starting material for R-Fe-B system or R-Fe-B system.
When an attempt is made to produce a —C-based sintered magnet, it becomes difficult to pulverize particularly when finely pulverizing because α-Fe crystallized in the alloy lump and the R-rich phase are locally distributed. There was a problem such as deviation.

Recently, in order to prevent coarsening of crystal grains, residual α-Fe, and segregation, which are defects of the R-Fe-B alloy powder by the ingot crushing method, an R-Fe-B alloy molten metal is added. A method has been proposed (Japanese Patent Laid-Open No. 63-317643) in which a slab having a specific plate thickness is formed by a roll method, and the slab is manufactured by a conventional powder metallurgy method.

Further, as a method for producing a quenching cast piece for a permanent magnet by a horizontal pouring strip casting method using a single roll of R-Fe-B alloy molten metal, a nozzle having a required width in the horizontal direction at the tip of the tundish. Is provided, and one roll is horizontally supported adjacent to this nozzle, and after the molten metal melted in the high-frequency melting furnace is accommodated in the tundish, the molten roll is horizontally arranged from the nozzle and continuously rolled. A method for producing a rapidly-quenched slab by pouring the molten metal into the molten steel and rapidly solidifying it is proposed (JP-A-5-222488 and JP-A-6-846).
No. 24).

[0012]

On the other hand, when a molten slab of R-Fe-B alloy is produced with a quenching roll, even if the slab is cooled at a speed that optimizes the magnetic characteristics, the slab roll is used. There is a difference in the crystal grain size on the contact surface side and the opposite side, the region where a preferable crystal grain size can be obtained is extremely narrow, and the magnetic properties in the cooling direction of the quenched alloy cast piece become non-uniform,
In order to reduce the dependency of the magnetic characteristics on the roll peripheral speed, it has been proposed to arrange the average roughness Ra of the peripheral surface of the quench roll within a specific range of 0.07 μm to 5 μm (JP-A-4-28457). .

Further, in order to reduce the difference between the cooling rate on the slab roll contact surface side and the cooling rate on the opposite side, a quenching roll of copper or copper alloy is provided with a surface layer of Cr or the like having an optimum thickness.
It has been proposed (Japanese Patent Laid-Open No. 4-55042) to control heat transfer in a quench roll during cooling of the molten alloy. However, the slab that is the target of the proposed method has a small dimension such that the width (L) in the case of producing a super-quenched ribbon for a bonded magnet having an average crystal grain size of 1 μm or less is 2 mm and a thickness is about 45 μm.

In the case of industrial mass production of R-Fe-B or R-Fe-B-C type alloy slabs, for example, the width (L) dimension of the slab is 50 mm or more and the thickness is 0.01. ~
About 1.0 mm is desirable, but this slab size is more than 25 times larger than the slab size of the proposed method, so when casting with a quenching roll, the slab center and its width direction Although the cooling rate in the vicinity is fast, the vicinity of both sides warps upwards of the cooling roll during cooling, so contact with the quenching roll becomes insufficient, and due to the difference in crystal grain size in the thickness direction of the slab, the width direction The difference in the crystal grain size becomes large, and the crystal grain size in the vicinity of both sides becomes larger than the crystal grain size in the vicinity of the center, so that there is a possibility that the magnetic properties of the obtained magnet may be deteriorated or varied.

The present invention is a large R-Fe having a width (L) dimension of 50 mm or more and a thickness of 0.01 to 1.0 mm.
-B or R-Fe-B-C magnet alloy for the purpose of industrial mass production of quenched slabs, the difference in crystal grain size in the width direction of the slabs is small, and the magnetic properties of the obtained magnets are small. R-Fe-B system or R-Fe-B-
It is intended to provide a quenching roll for producing a magnet alloy for obtaining a C-based magnet alloy slab.

[0016]

DISCLOSURE OF THE INVENTION The inventors have found that the width of a cast piece is 5
R-Fe-B system or R-Fe- with a large dimension of 0 mm or more
When a B-C magnet alloy slab is cast with a quenching roll, the crystal grain size of the obtained slab in the vicinity of the center and both sides in the width direction is made uniform to deteriorate the magnetic properties of the obtained magnet. As a result of various studies on the structure of the quenching roll for the purpose of preventing variation, the surface roughness of the wear-resistant metal layer coated on the surface of the quenching roll was measured in the vicinity of the widthwise center of the roll surface in contact with the molten alloy. The present invention has been completed by finding that a quenched slab having a fine and uniform crystal grain size can be obtained by roughening both side portions to a specific roughness from the portion.

That is, according to the present invention, in a quenching roll for producing a magnet alloy for quenching and solidifying an R-Fe-B type or R-Fe-B-C type magnet alloy melt, the surface of the quenching roll with which the alloy melt comes into contact. The surface roughness Ra ₂ of the central portion (T = 0.5L to 0.9L) in the width (L) direction of the provided wear-resistant metal layer is 0.1 μm to 10 μm, and both side portions (t = 0.05L to 0.25 L) surface roughness Ra ₁ of 2
.About.20 μm, and the relationship of the surface roughness of each region is Ra ₁
> Ra ₂ is a quenching roll for producing a magnet alloy.

The R-Fe-B magnet alloy of the present invention is characterized in that it contains R10 atom% to 25 atom%, B2 atom% to 15 atom%, and Fe60 atom% to 88 atom% as main components. A quenching roll for manufacturing magnet alloys,
The —Fe—B—C magnet alloy is R10 atomic% to 30 atomic%, B + C4 atomic% to 10 atomic% (however, B6 atomic% or less, C4 atomic% to 10 atomic%), Fe60 atomic% to 86.
A quenching roll for producing a magnet alloy, which is characterized by containing atomic% as a main component.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The operation of the quenching roll according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic front view showing the constitution of the quenching roll of the present invention. Quenching roll 1
The base material 2 of Cu, Cu alloy, Ag, Ag alloy, A
Although Al and Al alloys can be used, Cu or Cu alloy is preferable from the viewpoint of high thermal conductivity and low cost.
The size of the quenching roll is not particularly limited and may be an appropriate size according to the purpose, but usually the diameter is 150 to 200.
The roll has a width of about 0 mm and a width of about 50 to 1000 mm, and a passage for cooling the surface is provided inside the roll.

The wear-resistant metal layer 3 of the surface layer of the quenching roll 1 is preferably Cr, Cr alloy, Ni, Ni alloy, or may be a combination of these, and the surface hardness is 500 to Vickers hardness Hv. 1200 is preferable, and 600 to 1000 is more preferable.

The quenching roll of the present invention is characterized in that the surface roughness is specified depending on the part. When the width of the cast piece to be produced is L, the quenching roll 1 in contact with the molten alloy has a width of 0. The range of 5 L to 0.9 L is defined as the central portion 4 of the width T, and the surface roughness Ra ₂ of the central portion 4 is 0.1 μm to
10 .mu.m, preferably 0.15 .mu.m to 5 .mu.m, and the widths t of the portions 5 and 5 on both sides of the surface of the quenching roll are 0.05 L to 0.25 L, respectively.
The surface roughness Ra ₁ of 5 is 2 to 20 μm, preferably ₃ to ₁
The surface roughness Ra ₁ of the portions 5 and 5 on both sides must be larger than the surface roughness Ra _{2 of the} portion 4 on the center. However, in the definition of the region, T + 2t ≧ L 2.

In the present invention, the surface roughness is appropriately determined within the above range depending on the alloy composition and the thickness of the cast piece. Further, the width t of the portions 5 and 5 near both sides may be 0.05 L to 0.25 L with respect to the slab width L, but in operation,
Since the positions of the slab and the roll cannot be strictly controlled, it is preferable to widen the width in the vicinity of both sides in both directions of the roll.

In the present invention, when the width T of the central portion 4 of the quenching roll 1 contacting the molten alloy is less than 0.5 L, the surface roughness is large, that is, the cooling rate of the slab is slow and the grain size The growth area becomes too wide, and the average crystal grain size of the entire slab becomes large. Also, if it exceeds 0.9 L, it is not possible to control the warp of both sides of the slab toward the upper side of the quenching roll, and the vicinity of both sides. It is not preferable because the crystal of the part becomes coarse, so it is limited to 0.5 L to 0.9 L.

Further, the surface roughness Ra ₂ of the central portion 4 is
The reason for limiting 0.1 to 10 μm is not preferable because the wettability between the molten metal and the roll surface is poor and the molten metal slips on the roll surface when it is less than 0.1 μm. On the other hand, if it exceeds 10 μm, the cooling rate becomes too slow and the crystals may become coarse, which is not preferable.

The width t of the portions 5 and 5 near both sides of the quenching roll 1
Is less than 0.05 L, it is not possible to control the warp of both sides of the slab upward of the quenching roll, and if it exceeds 0.25 L, it is possible to control the slab warping above the roll, but Area of high roughness, that is, the cooling rate of the slab is slow,
Since the area of large crystal grain size becomes too wide, the average crystal grain size of the entire slab becomes large, which is not preferable.
It is limited to 0.05L to 0.25L.

In the present invention, the both side portions 5, 5
The reason for limiting the surface roughness Ra ₁ of 2 to 20 μm is 2
If it is less than μm, it is not possible to control the warp of the slab on both sides upward, and if it exceeds 20 μm, it is possible to control the warp upward, but the cooling rate becomes too slow,
This is because the crystals in the vicinity of both sides become coarse, which is not preferable.

In the present invention, the surface roughness Ra ₂ of the portion 4 near the center of the quenching roll 1 and the surface roughness Ra ₁ of the portions 5 and 5 near both sides are such that Ra ₁ > Ra ₂ The surface roughness of the entire area of the vicinity part 4 and the surface roughness of the entire areas of the both side vicinity parts t may be set to specific surface roughnesses, or the surface roughness of the center part of the center vicinity part 4 is set to the minimum value. As described above, it is possible to set the surface roughness to be continuously changed so that the surface roughness is gradually reduced from the both side portions of the both side vicinity portions 5 and 5 within the limited range of the surface roughness. . The center line average roughness Ra is specified in JISB0601.

In the present invention, as a method of forming the surface of the quenching roll to a predetermined surface roughness, the substrate surface of the quenching roll is machined in advance, or the method of shot blasting steel balls, glass pieces, ceramic pieces, etc. After forming the substrate surface to the required surface roughness with a method of depositing a wear-resistant metal layer, or after depositing the wear-resistant metal layer on the substrate, the surface of this metal layer by the method described above. You may adjust to the required surface roughness.

The preferred alloy composition of the alloy slab for producing the R-Fe-B system or R-Fe-B-C system permanent magnet in the present invention will be described below. The rare earth element R contained in the alloy slab for permanent magnets of the present invention is a rare earth element including yttrium (Y) and including light rare earths and heavy rare earths.

Usually, one kind of R is sufficient, but in practice, a mixture of two or more kinds (Misch metal, didymium, etc.) can be used for reasons of availability, Sm,
Y, La, Ce, Gd etc. can be used as a mixture with other R, especially Nd, Pr etc. Note that R may not be a pure rare earth element, and may contain impurities that are unavoidable in production within the industrially available range.

R is an R-Fe-B system permanent magnet or R-
It is an essential element of alloy slabs for producing Fe-B-C based permanent magnets, and in the case of R-Fe-B based magnets, high magnetic properties, especially high coercive force cannot be obtained at less than 10 atomic%, and 25 atomic %
If it exceeds, the residual magnetic flux density (Br) decreases, and a permanent magnet with excellent characteristics cannot be obtained. Therefore, R is 10 atomic%
-25% by atom. The preferred range is 12
It is from atomic% to 18 atomic%.

In the case of the R-Fe-B-C system magnet, R
If it is less than 10 atom%, high magnetic properties, particularly high coercive force, cannot be obtained, and if it exceeds 30 atom%, the residual magnetic flux density (Br) is lowered and a permanent magnet having excellent characteristics cannot be obtained. Therefore, R is in the range of 10 atom% to 30 atom%. The preferred range of R is 12 atom% to 18 atom%.

B is an essential element of the alloy slab for producing the R-Fe-B system permanent magnet. If it is less than 2 atom%, a high coercive force (iHc) cannot be obtained, and if it exceeds 15% atom, it remains. Since the magnetic flux density (Br) decreases, an excellent permanent magnet cannot be obtained. Therefore, B is in the range of 2 atom% to 15 atom%. The preferable range of B is 4 atom% to 12 atom%.

In the R-Fe-B-C type permanent magnet, B and C are essential elements. If B + C is less than 4 atomic%, a high coercive force (iHc) cannot be obtained and exceeds 10 atomic%. And the residual magnetic flux density (Br) decreases, an excellent permanent magnet cannot be obtained, and when B exceeds 6 at%, corrosion resistance decreases, which is not preferable, and C is 4a.
If it is less than t%, the corrosion resistance decreases, which is not preferable, and C is 10
When it exceeds at%, the amount of the RC phase increases, the residual magnetic flux density (Br) decreases, and the squareness of the demagnetization curve deteriorates, which is not preferable. Therefore, B + C is in the range of 4 atom% to 10 atom% (however, C4 atom% to 10 atom% and B6 atom% or less). The preferred range of B + C is 6 atom% to
8 atomic%.

Fe is an R--Fe--B system permanent magnet or R
It is an essential element of alloy slabs for producing —Fe—B—C type permanent magnets, and in the case of R—Fe—B type magnets, the residual magnetic flux density (Br) decreases if it is less than 60 atom%, and 88% atom If it exceeds, a high coercive force cannot be obtained, so Fe is 60 atomic%
It is limited to 88 atom%. The preferable range of Fe is 70 atomic% to 84 atomic%.

Further, in the case of the R-Fe-BC system magnet, F
When e is less than 60 atomic%, the residual magnetic flux density (Br) is reduced, and when it exceeds 86 atomic%, a high coercive force cannot be obtained, so Fe is limited to 60 atomic% to 86 atomic%. The preferable range of Fe is 74 atom% to 82 atom%.

Further, R-Fe-B system magnet or R-F
Part of Fe in the e-B-C magnet can be replaced with one or two kinds of Co and Ni, because the effect of improving the temperature characteristics of the permanent magnet and the effect of improving corrosion resistance can be obtained. However, one or two of Co and Ni are 50% of Fe.
If it exceeds, a high coercive force cannot be obtained, and an excellent permanent magnet cannot be obtained. Therefore, the upper limit of the substitution amount of one or two of Co and Ni is 50% of Fe.

In order to obtain an excellent permanent magnet having both a high residual magnetic flux density and a high coercive force in the R-Fe-B type alloy slab according to the present invention, R12 atom% to 16 atom% and B5 atom% to 8 atomic% and Fe76-83 atomic% are preferable.

In order to obtain a high-performance magnet having a high residual magnetic flux density, a high coercive force, a squareness of a demagnetization curve, and a high corrosion resistance in the R-Fe-B-C type alloy slab according to the present invention, R13 atomic% to 17 atomic%, B + C = 6 atomic% to 8 atomic% (however, B2 atomic% to 4 atomic%, C4 atomic% to 6 atomic%) and Fe75 atomic% to 81 atomic% are preferable.

Further, the R-Fe-B type alloy slab according to the present invention can tolerate the presence of impurities inevitable in industrial production such as O ₂ , C, Ca and Mg in addition to R, B and Fe. ,
Part of B is at least one of 4.0 at% or less of C, 3.5 at% or less of P, 2.5 at% or less of S, and 3.5 at% of Cu or less, and a total amount of 4 By substituting at 0.0 atomic% or less, it is possible to improve the manufacturability and reduce the cost of the magnet alloy.

The R-Fe-B-C type slab has R,
In addition to B, Fe and C, the presence of impurities unavoidable in industrial production such as O ₂ , Ca, and Mg can be tolerated, but a part of B is 3.5 atomic% or less P, 2.5 atomic% or less. S, 3.
By substituting at least one of Cu of 5 atomic% or less with a total amount of 4.0 atomic% or less, it is possible to improve the manufacturability of the magnet alloy and reduce the cost.

Further, the R, B, Fe alloy or R,
B, C, Fe alloy or R containing Co in the above alloy
-Fe-B alloy or R-Fe-B-C alloy, 9.5
Atom% or less Al, 4.5 atom% or less Ti, 9.5 atom% or less V, 8.5 atom% or less Cr, 8.0 atom%
Mn below, Bi at 5 atomic% or less, Nb at 12.5 atomic% or less, Ta at 10.5 atomic% or less, Mo at 9.5 atomic% or less, W at 9.5 atomic% or less, 2.5 S of atomic% or less
b, Ge of 7 atomic% or less, Sn of 3.5 atomic% or less,
By adding at least one of Zr of 5.5 atomic% or less and Hf of 5.5 atomic% or less, a high coercive force of the permanent magnet alloy becomes possible.

R-Fe-B system or R-F of the present invention
In the e-B-C system permanent magnet, it is indispensable that the main phase of the crystal phase is a tetragonal crystal, and in particular, a fine and uniform alloy powder is obtained, and sintering having excellent magnetic properties and excellent corrosion resistance is performed. It is effective for producing permanent magnets.

[0044]

【Example】

Example 1 In a quenching roll according to the present invention, a base material is a Cu alloy (99
wt% Cu-1 wt% Cr), and the surface layer is provided with a Cr layer having a layer thickness of 30 μm and hardness Hv900 and a diameter of 500 m.
Using a water-cooled quenching roll having a length of m and a length of 300 mm, the surface roughness Ra ₂ in the vicinity of the center having a width T of 70 mm in contact with the molten metal was processed to 2 μm, and the surface roughness Ra ₁ in the vicinity of both sides of the width t 15 mm was processed to 7 μm. .

30.5Nd-1.0D in a vacuum melting furnace
After melting so as to obtain a magnet composition of y-1.0B-0.9Co-balFe (wt%), the quenching roll was rotated at a rotation speed of 80.
While rotating at rpm, the molten metal is poured from a nozzle to have a width of 100 mm and a thickness of 0.41 mm to 0.45 m.
m, an average value of 0.43 mm, and a length of about 50 to 300 mm were obtained. The obtained cast piece has a resinous crystal structure, and the average short-axis crystal grain size in the vicinity of the center and in the vicinity of both sides is shown in Table 1.

The slab was coarsely pulverized and finely pulverized by a known method to obtain an alloy powder having an average particle size of 3.5 μm, which was then molded at a magnetic field strength of 15 kOe and a pressing force of 1.0 ton / cm ² , After sintering at 1060 ° C. for 3 hours, aging treatment was performed at 600 ° C. for 1 hour to obtain a permanent magnet. Table 2 shows the magnetic properties of the obtained permanent magnets.

Comparative Example 1 Using a molten alloy having the same composition as in Example 1, and using a water-cooled rapid cooling roll having the same structure as in Example 1 and a diameter of 500 mm, the width T of the surface of the rapid cooling roll contacting the molten metal was about 70 mm in the vicinity of the center. After processing the surface roughness Ra ₂ and the surface roughness Ra ₁ at both sides near the width t of 15 mm to 2 μm, a quenched slab was obtained under the same conditions as in Example 1.

The size of the obtained quenched slab is 100 mm in width.
× Thickness 0.39 mm to 0.43 mm, average value 0.41 m
m, and the length was about 50 to 300 mm. Table 1 shows the average minor axis crystal grain sizes in the vicinity of the center and both sides of the obtained slab.
Shown in Table 2 shows the magnetic characteristics of the permanent magnets obtained by magnetizing the cast pieces under the same conditions as in Example 1.

Example 2 A quenching roll having the same material, size and surface roughness as in Example 1 was used. 12.8Nd-1.5 in vacuum melting furnace
Dy-4.4C-10.1Co-68Fe-3.2B
After being melted so that the magnet composition was (at%), the melt was poured from a nozzle while rotating the quenching roll at a rotation speed of 80 rpm, and the width was 100 mm and the thickness was 0.27.
mm-0.32 mm, average thickness 0.30 mm, length 60
A quenched slab of about 300 mm was obtained. The obtained slab had a resinous crystal structure, and Table 1 shows the average short-axis crystal grain size in the central portion (Ra ₁ ) and both side portions (Ra ₂ ) in the width direction.

The slab was coarsely pulverized and finely pulverized by a known method to obtain an alloy powder having an average particle size of 3.2 μm, which was then molded with a magnetic field strength of 15 kOe and a pressing force of 1.0 ton / cm ² . After sintering at 1040 ° C. for 3 hours, aging treatment was performed at 900 ° C. for 1 hour to obtain a permanent magnet. Table 2 shows the magnetic properties and corrosion resistance test results of the obtained permanent magnets. The corrosion resistance test is represented by the increase in oxidation amount per unit area after standing under the condition of 80 ° C. × 90% RH × 500 hours.

Comparative Example 2 A molten alloy having the same composition as in Example 2 was used, and in a water-cooled quenching roll having the same structure as in Example 1 and a diameter of 500 mm, the width T of the surface of the quenching roll in contact with the molten metal was about 70 mm in the vicinity of the center. After the surface roughness Ra ₂ and the surface roughness Ra ₁ in the vicinity of both sides having a width t of 15 mm were both set to 2 μm, a quenched slab was obtained under the same conditions as in Example 2.

The size of the obtained quenched slab is 100 mm in width.
× Thickness 0.30 mm to 0.35 mm, average thickness 0.32
mm, and the length was about 50 to 300 mm. Table 1 shows the average minor axis crystal grain sizes in the vicinity of the center and the vicinity of both sides of the obtained slab. Table 2 shows the magnetic properties and corrosion resistance test results of permanent magnets obtained by magnetizing the cast pieces under the same conditions as in Example 2. The test conditions for corrosion resistance are the same as in Example 2.

[0053]

[Table 1]

[0054]

[Table 2]

[0055]

According to the present invention, the surface roughness of the wear-resistant metal layer coated on the surface of the quenching roll is determined by the specific roughness R near the center of the width T of the roll surface in contact with the molten alloy.
than a _2, identify the sides near portion consisting width t, t roughness Ra ₁
By quenching to a large size, a quenching cast piece of a large R-Fe-B system or R-Fe-B-C series magnet alloy having a cast piece width of 50 mm or more and a thickness of about 0.01 to 1.0 mm is industrially produced. Even in the case of mass production, as is clear from the examples, the difference in crystal grain size in the width direction of the cast slab is small, the magnetic properties of the obtained magnet are reduced, the variation is reduced, or the corrosion resistance is excellent.
It is possible to obtain a -Fe-B-based or R-Fe-B-C-based alloy slab.

[Brief description of the drawings]

FIG. 1 is a schematic front view showing the structure of a quenching roll of the present invention.

[Explanation of symbols]

 1 Quenching roll 2 Base material 3 Abrasive metal layer 4 Central area 5 Both sides area

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaki Ueda 2-19-1 Minami Suita, Suita City, Osaka Prefecture Sumitomo Special Metals Co., Ltd. Suita Works (72) Inventor Takashi Kojima 2-19 Minami Suita City, Suita City, Osaka Prefecture No. 1 Sumitomo Special Metals Co., Ltd. Suita Works (72) Inventor Yukiyoshi Watanabe 2-19-1 Minami Suita, Suita City, Osaka Prefecture Sumitomo Special Metals Co., Ltd. Suita Works

Claims (4)

[Claims] 1. A quenching roll for producing a magnet alloy for quenching and solidifying a magnet alloy melt, in the vicinity of the center (T = 0. 0) in the width (L) direction of the wear-resistant metal layer on the surface of the quench roll which the alloy melt contacts. Surface roughness Ra ₂ of 5 L to 0.9 L) is 0.1 μm to 10 μm, and both side portions (t = 0.05 L
0.25 L) surface roughness Ra ₁ of 2 to 20 μm,
A quenching roll for producing a magnet alloy in which the relation of the surface roughness of each region is Ra ₁ > Ra ₂ . 2. The magnet alloy according to claim 1, wherein the magnet alloy is R-Fe.
A quenching roll for producing a magnet alloy which is a -B magnet alloy or an R-Fe-BC magnet alloy. 3. The magnet alloy manufacturing method according to claim 2, wherein the R-Fe-B based magnet alloy is composed of R10 atomic% to 25 atomic%, B2 atomic% to 15 atomic% and Fe60 atomic% to 88 atomic% as main components. Quenching roll for. 4. The R-Fe-B-C based magnet alloy according to claim 2, wherein R is 10 atom% to 30 atom% and B + C is 4 atom%.
A quenching roll for producing a magnet alloy, which comprises a main component of 10 at% (however, B6 at% or less, C4 to 10 at%) and Fe at 60 at% to 86 at%.