JP2005270988A - Method for producing rare-earth-metal alloy thin sheet, rare-earth-metal alloy thin sheet and rare-earth-metal magnet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably make producable of high characteristic rare-earth-metal magnetic alloy exceeding 400 KJ/m3 in a mass-production level. <P>SOLUTION: A method for producing a rare-earth-metal alloy thin sheet is performed as the followings, that is, when the alloy thin sheet is obtained by rapidly cooling with a cooling roll to molten alloy having the composition composed of 26.8-32.0% R (rare-earth-metal elements containing Y), 0.3-1.5% B, 0.005-1.2% C, 0-4.0% additional element M (Ga, Zr, Nb, Hf, Ta, W, Mo, Al, Si, V, Cr, Ti, Cu, Ag, Mn, Ni, Ge, Sn, Bi, Pb, Zn) and the balance T (Fe and/or Co) with inevitable impurities, the cooling roll is used to one, in which the surface layer in contact with the molten alloy has 10-30 mm thickness and 500-1000 mm the outer diameter formed of copper or a copper alloy having ≥200 W/m°C thermal conductivity, and the molten alloy is rapidly cooled by rotating, the cooling roll at 20-120 rotation/min speed while water-cooling this inner part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a rare earth alloy ribbon as a raw material for a rare earth permanent magnet having excellent magnetic properties, a rare earth alloy ribbon obtained by the method, and a rare earth magnet using the rare earth alloy ribbon.

Rare earth permanent magnets are widely used in the field of electrical and electronic equipment because of their excellent magnetic properties and economy, and in recent years, their performance is increasingly required. Among these permanent magnets, R ₂ T ₁₄ B rare earth permanent magnets (commonly known as neodymium magnets) are richer in the main element Nd than rare earth cobalt magnets compared to rare earth cobalt magnets and do not use expensive Co frequently. It is an extremely excellent permanent magnet that is inexpensive and has magnetic properties far superior to those of rare earth cobalt magnets.

Conventionally, alloys for raw materials of rare earth magnets have been manufactured by a mold casting method in which a molten metal is cast into a mold. According to this method, primary γ-Fe precipitates during the cooling and solidification process of the alloy, After cooling, it was segregated as α-Fe. This α-Fe not only deteriorates the pulverization ability in the fine pulverization step in the rare earth magnet manufacturing process, but also causes a decrease in magnetic properties when remaining in the magnet after the sintering step. For this reason, it is necessary to perform heat treatment at a high temperature for a long time to homogenize and eliminate α-Fe, but this heat treatment coarsens the crystal grain size of the main phase (R ₂ T ₁₄ B) in the alloy, As a result, the magnetic characteristics are deteriorated and the manufacturing cost is increased. In order to solve such problems, an alloy ribbon obtained by using a quenching technique such as a strip casting method to control segregation of α-Fe and control the crystal grain size of the main phase to be small. A technique for producing a rare earth magnet using a rare earth magnet raw material alloy has been reported.

  For example, in (1) Japanese Patent No. 1889311 (Patent Document 1), a main phase which is crystalline of 5 μm or less is obtained, and the alloy is not only a raw material for a bonded magnet but also a raw material for a sintered magnet. (2) Japanese Patent No. 2665590 (Patent Document 2) obtains a homogeneous columnar crystal having a minor axis of 3 to 20 μm as a main phase, and a magnet having a high coercive force (iHc) as a raw material. (3) Japanese Patent No. 2639609 (Patent Document 3) uniformly solidifies at a cooling rate of 10 to 500 ° C./second, and the crystal grain size of the main phase is 0.1 to 0.1 on the minor axis. A technique for producing a permanent magnet raw material alloy having a length of 50 μm and a major axis of 0.1 to 100 μm and increasing the remanent magnetization (Br) is disclosed. (4) JP-A-7-176414 (Patent Document 4) Columnar crystals with an average particle size of 3 to 50 μm A technique for improving magnetic properties and improving grindability by mixing a grain boundary assistant alloy having a particle size of 0.1 to 20 μm and occluding hydrogen is disclosed. (5) JP-A-9-170055 In the publication (Patent Document 5), by controlling the cooling at 800 to 600 ° C. to 10 ° C./second or less after casting, the average particle size of the main phase is 20 to 100 μm and the Nd rich phase interval is 15 μm or less. A technique for producing an alloy and increasing the remanent magnetization is disclosed.

These reports are characterized by improving the magnetic properties by using a homogeneous alloy with a uniform average particle diameter, but neodymium magnets have become more sophisticated and require mass production in excess of 400 kJ / m ^3. Therefore, an alloy having a higher quality structure has been demanded, and JP 2000-219943 A (Patent Document 6) controls the precipitation form of chill crystals and α-Fe phase. Thus, a technique has been disclosed in which the density increases at a sintering temperature lower by 20 to 100 ° C. than before, and a high coercive force (iHc) can be obtained without impairing the residual magnetization (Br). In Japanese Patent Application Laid-Open No. 2000-303153 (Patent Document 7), not only an α-Fe phase, but also an R-rich phase, a B-rich phase (Nd _{1 + α} Fe ₄ B ₄ phase in many cases), and R ₂ T ₁₄ A technique for improving the residual magnetic flux density by controlling the four-phase coexistence region including the B phase is disclosed. However, it is difficult to stably produce the structure in a large-scale furnace of mass production level, which has been a problem.

Japanese Patent No. 1889311 Japanese Patent No. 2665590 Japanese Patent No. 2639609 JP-A-7-176414 JP-A-9-170055 JP 2000-219943 A JP 2000-303153 A

  The present invention has been made in view of the above circumstances, and a method for producing a rare earth alloy ribbon having a high-quality crystal structure as a raw material for a rare earth permanent magnet having excellent magnetic properties, and a rare earth alloy thin film obtained by the method. It is an object of the present invention to provide a band and a rare earth magnet using the rare earth alloy ribbon.

As a result of diligent investigations to achieve the above object, the inventors of the present invention have thought that the conventional roll quenching method controls the peripheral speed of the roll, thereby controlling the cooling rate and controlling the crystal structure. However, even with the same roll peripheral speed, it was found that the structure changes greatly if the outer diameter, thickness, and thermal conductivity of the material used are different. A four-phase coexistence region which is a very active region composed of a chill crystal region, an α-Fe phase, an R-rich phase, a B-rich phase, and an R ₁₂ T ₁₄ B phase, a spherical crystal region, a columnar crystal region, In addition, the inventors have found that a rare earth alloy ribbon having a high-quality crystal structure in which a phase region caused by the additive element M is mixed can be stably produced, and the present invention has been made.

Accordingly, the present invention provides a method for producing a rare earth alloy ribbon, a rare earth alloy ribbon and a rare earth magnet as described below.
[1] R (R is one or a combination of two or more of rare earth elements including Y), T (T is Fe, or Fe and Co), B as a main component, and R is 26.8 to 32.0 Mass%, B is 0.3 to 1.5 mass%, C is 0.005 to 1.2 mass%, additive element M (M is Ga, Zr, Nb, Hf, Ta, W, Mo, Al, Si V, Cr, Ti, Cu, Ag, Mn, Ni, Ge, Sn, Bi, Pb, Zn) or a combination of two or more) is 0 to 4.0% by mass, the balance is T and inevitable impurities When the molten alloy having the composition is rapidly cooled with a cooling roll to obtain an alloy ribbon, the surface layer in contact with the molten alloy has a thickness of 10 to 30 mm and a thermal conductivity of 200 W / m · ° C. or higher. Cooling with an outer diameter of 500 to 1,000 mm formed by copper or copper alloy having Using Lumpur, the method of producing the rare-earth alloy ribbon, characterized by rapidly cooling the cooling roll inside the rotate with water cooling while 20-120 rev / min the molten alloy.
[2] The method for producing a rare earth alloy ribbon according to [1], wherein the molten alloy temperature is 1,500 to 1,600 ° C.
[3] The average thickness produced by the method according to [1] or [2] is 100 to 800 μm, the volume ratio is 1 to 30%, and the average particle size is 8 μm or less. It has a four-phase coexistence region consisting of an α-Fe phase, an R-rich phase having an average particle size of 10 μm or less, a B-rich phase having an average particle size of 8 μm or less, and an R ₂ T ₁₄ B phase in a volume ratio of 1 to 20%, and the balance Is a rare earth alloy ribbon characterized by comprising a phase due to spherical crystals, columnar crystals, and additive element M.
[4] A rare earth magnet comprising the rare earth alloy ribbon according to [3].

According to the present invention, it is possible to stably manufacture a high-performance rare earth magnet alloy having a maximum energy product exceeding 400 kJ / m ³ at a mass production level.

The raw material alloy used for the production of the rare earth alloy ribbon of the present invention is 26.8-32.0 mass% R (R is one or a combination of two or more of the rare earth elements including Y), 0.3 -1.5 mass% B, 0.005-1.2 mass% C, 0-4.0 mass% additive element M (M is Ga, Zr, Nb, Hf, Ta, W, Mo, Al , Si, V, Cr, Ti, Cu, Ag, Mn, Ni, Ge, Sn, Bi, Pb, Zn, or a combination of two or more), the balance being T (T is Fe, or Fe and Co) And an R ₂ T ₁₄ B alloy having a composition comprising inevitable impurities.

  Here, R is preferably one or more rare earth elements selected from Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. Of these, Pr, Nd, Tb, and Dy are preferably used. On the other hand, M is selected from Ga, Zr, Nb, Hf, Ta, W, Mo, Al, Si, V, Cr, Ti, Cu, Ag, Mn, Ni, Ge, Sn, Bi, Pb, and Zn. One or more metal elements, among which Zr, Al, Si, and Cu are preferably used. T is Fe, or Fe and Co.

  If the amount of R is less than 26.8% by mass, the coercive force is remarkably reduced. On the other hand, if it exceeds 32.0% by mass, the amount of R-rich phase is increased more than necessary, resulting in a low residual magnetization. As a result, the magnetic properties deteriorate. Above all, the amount of R is preferably between 27.0 and 29.0% by mass because it is easy to control the precipitation of a fine α-Fe phase or the like in the four-phase coexistence region.

Further, when the amount of B is less than 0.3% by mass, the coercive force is remarkably lowered due to precipitation of the Nd ₂ Fe ₁₇ phase, and when it exceeds 1.5% by mass, the B-rich phase (which varies depending on the composition, In this case, the amount of Nd _{1 + α} Fe ₄ B ₄ phase) increases and the residual magnetization decreases. A preferable amount of B is 0.8 to 1.2% by mass.

  C is an additive that often forms an intermetallic compound similar to B in a sintered magnet alloy. However, if it is less than 0.005% by mass, the increase in density during sintering is hindered, and the residual magnetization is reduced. If it exceeds 1.2% by mass, the coercive force will be significantly reduced. A preferable amount of C is 0.01 to 0.3% by mass.

The additive element M is used depending on the purpose such as increasing the coercive force, but if it exceeds 4.0% by mass, the residual magnetization is remarkably reduced. A preferable amount of M is 0.05 to 1.5% by mass.
In addition to the above elements, the rare earth alloy may contain impurities unavoidable in production, such as H, O, and N.

  In the present invention, the molten metal temperature of the alloy is generally said to be 1,400 to 1,500 ° C., but in order to obtain a desired structure with the cooling roll of the present invention, 1,500 to It is preferable to set it as 1,600 degreeC, especially 1,520-1,580 degreeC. If the temperature is lower than 1,500 ° C., the ratio of the four-phase coexistence region may decrease. If the temperature exceeds 1,600 ° C., the reactivity between the crucible and the molten metal increases, which may cause a decrease in yield and a decrease in crucible life. is there.

  In the method for producing a rare earth alloy ribbon according to the present invention, an alloy ribbon is obtained by rapidly cooling the molten alloy having the above composition with a cooling roll. In this case, as the cooling roll, the molten alloy is brought into contact with the molten alloy. Use a roll with a surface layer of 10 to 30 mm in thickness and an outer diameter of 500 to 1,000 mm formed of copper or a copper alloy having a thermal conductivity of 200 W / m · ° C. or more and the inside of which can be water-cooled. Is rotated at a speed of 20 to 120 revolutions / minute while water-cooling the inside, and the molten alloy is poured onto the surface to quench the molten alloy.

  Here, as described above, the outer diameter of the cooling roll is 500 to 1,000 mm, and preferably 600 to 800 mm. As the cooling roll, a roll having an outer diameter of 200 to 400 mm is generally used. However, in this case, a four-phase coexistence region including a fine α-Fe phase, an R-rich phase, a B-rich phase, etc. is stably provided. This cannot be obtained, and this can be achieved by setting the outer diameter of the roll to 500 mm or more. If it is less than 500 mm, it is necessary to increase the rotational speed in order to obtain a predetermined peripheral speed. For this reason, the centrifugal force works strongly, and the ratio of objects that peel off before the alloy ribbon is completely cooled by the roll increases. Since the alloy ribbon is not cooled by a roll, the cooling rate is greatly reduced, so the particle size of each phase in the four-phase coexistence region cannot be controlled, and the coarsened α exceeds 8 μm and sometimes exceeds 20 μm. The -Fe phase is precipitated and the magnetic properties are deteriorated. In addition, since a roll is a part exchanged regularly, when it exceeds 1,000 mm, it is unpreferable on a maintenance.

  For the same reason, the rotation speed of the cooling roll is 120 revolutions / minute or less, and if it is less than 20 revolutions / minute, the thickness of the alloy ribbon becomes thick, so that it can be 20 to 120 revolutions / minute. It is necessary and it is preferable to set it as 30 to 90 rotations / minute.

  The thickness of the surface layer of the cooling roll is 10 to 30 mm, and preferably 15 to 25 mm. As the roll thickness (surface layer thickness), a thickness of 30 to 60 mm is generally used, but this can stably obtain a chill crystal having a volume ratio of 1 to 30% in the vicinity of the cooling surface. However, it is possible to make the surface layer thickness 30 mm or less. If the thickness exceeds 30 mm, the distance between the outer surface of the roll that is brought into contact with a high-temperature molten metal (cooled into an alloy ribbon) and the temperature rises, and the inner surface of the roll that is cooled and kept near the water temperature is increased. Since it becomes slow and the cooling rate decreases, chill crystals will decrease. Moreover, if it is less than 10 mm, it is unpreferable on safety.

  The material of the surface layer of the cooling roll is preferably copper or a copper alloy as a metal having high thermal conductivity. In general, silver and copper are mentioned as metals having high thermal conductivity, but from the viewpoint of cost, an alloy system mainly composed of copper or copper is used. The thermal conductivity of pure copper is slightly different depending on the amount of unavoidable impurities such as oxygen, but it is about 400 W / m · ° C, so it is better to be close to this, but pure copper is soft and the roll is easily damaged. Since there is a problem with the roll life, various additives, for example, additives such as Cr, Zr, Be, etc., which increase the hardness, and additives such as Ag, which improve the thermal conductivity, were alloyed to increase the hardness. Things are used. In the present invention, copper or a copper alloy having a thermal conductivity of 200 W / m · ° C. or more, particularly 250 to 400 W / m · ° C. is used. If the thermal conductivity is less than 200 W / m · ° C., the ratio of chill crystals may decrease, and the particle diameter of α-Fe phase and the like in the four-phase coexistence region may increase.

  The cooling medium that flows inside the cooling roll is not particularly limited, but cooling water is usually used. As the cooling water temperature rises and bubbles are generated, the cooling efficiency decreases. Therefore, the amount of cooling water is secured or the supplied cooling water temperature is lowered so that the cooling water temperature does not rise to 80 ° C. or higher, preferably 50 ° C. or higher. There is a need.

  The method for producing a rare earth alloy ribbon of the present invention is a method in which an alloy ribbon is obtained by quenching the molten alloy with the above-described cooling roll. In this case, a known method is used except for the above-described roll conditions. And may be a single roll method or a twin roll method.

The thus obtained rare-earth alloy ribbon has an average thickness of 100 to 800 μm, a volume ratio of 1 to 30% of chill crystals, and an α-Fe phase having an average particle diameter of 8 μm or less, an average It has a four-phase coexistence region consisting of an R-rich phase with a particle size of 10 μm or less, a B-rich phase with an average particle size of 8 μm or less, and an R ₂ T ₁₄ B phase in a volume ratio of 1 to 20%, with the remainder being spherical crystals And a phase caused by the additive element M.

The structure of the obtained rare earth alloy ribbon will be briefly described. Since the chill crystal is finely pulverized at the time of fine pulverization due to the fineness of the particle size, the optimum sintering temperature is lowered and the residual magnetization is not impaired. Although there is an effect of obtaining a high coercive force, the effect is reduced when the content is less than 1% by volume in the rare earth alloy ribbon, and the oxygen concentration increases when the content exceeds 30% by volume. Is. For production of a high-performance rare earth magnet having a maximum energy product exceeding 400 kJ / m ³ , it is more preferable to have a ratio of 5 to 15% by volume.

  The chill crystals are isocrystalline microcrystals cooled at the moment when the molten alloy comes into contact with the roll, and generally have a particle size of 3 μm or less. The volume ratio of the chill crystal is measured by observing a cross section of the alloy ribbon with a polarizing microscope at a magnification of 200 times, and measuring the area ratio (%) of the chill crystal in the alloy ribbon to obtain the volume ratio ( %).

  In the four-phase coexistence region, the reaction of α-Fe phase, R-rich phase, and B-rich phase contained in the rare earth alloy ribbon is active, the density of the magnet during sintering tends to increase, and the residual magnetic flux density increases. However, if the content is less than 1% by volume in the rare earth alloy ribbon, the effect decreases. If the content exceeds 20% by volume, the oxygen concentration increases due to the high activity, 1 to 20% by volume, preferably 3 to 12% by volume.

The four-phase coexistence region has an average particle size of 8 μm or less, preferably 1 to 5 μm α-Fe phase, an average particle size of 10 μm or less, preferably 1 to 8 μm of an R-rich phase, an average particle size of 8 μm or less, preferably 1 It consists of a B rich phase of ˜5 μm and preferably an R ₂ T ₁₄ B phase. The alloy ribbon was not controlled and cooled on the roll because the alloy ribbon was peeled off before the cooling of the alloy ribbon was completed, or there was a part where the alloy ribbon and the roll were not in contact. In this case, the particle diameter of the α-Fe phase and the like contained in the four-phase coexistence region becomes large. It is well known that the particle size of the α-Fe phase greatly affects the magnetic properties. However, as in the present invention, the average particle size of the α-Fe phase is controlled to 8 μm or less, and the average particle size is When the R-rich phase having a particle diameter of 10 μm or less and the B-rich phase having an average particle diameter of 8 μm or less are precipitated simultaneously, the magnetic properties are improved. If the average particle diameter of the α-Fe phase exceeds 8 μm, the effect is lost, and if it exceeds 20 μm, the magnetic properties (particularly Br and bHc) may be greatly reduced.

  In the present invention, the average particle size of the four-phase coexistence region is a value measured at an magnification of 1,000 to 5,000 times, mainly 5,000 times, using an Auger electron spectrometer having an FE electron gun. is there. When the particle size was large and it was difficult to measure at 5,000 times, it was measured at 1,000 times. The volume ratio of the four-phase coexistence region can be a value measured with a polarizing microscope (magnification 200 times) in the same manner as the measurement of the volume ratio of chill crystals.

  Further, the portion other than the chill crystal and the four-phase coexistence region in the rare earth alloy ribbon may be composed of a spherical crystal, a columnar crystal, or a phase caused by the additive element M. Even if this phase exists, the effect of the present invention is not impaired as long as the other phase is less than 5% by volume.

  The thickness of the rare earth alloy ribbon is not limited as long as the internal structure is the above ratio, but a good internal structure is easily obtained when the average thickness is 100 to 800 μm. Above all, when the average thickness is 200 to 400 μm, an alloy ribbon having a desired structure can be obtained more stably.

  Such a rare earth alloy ribbon is finely pulverized to a mean particle size of 2 to 8 μm using a jet mill or the like, and the obtained fine powder is pressed while being oriented in a magnetic field of 600 kA / m or more, particularly 900 kA / m or more. Subsequently, sintering is performed at 950 to 1,200 ° C., particularly 1,000 to 1,080 ° C. in a vacuum atmosphere, and further, an aging treatment is performed in a vacuum or Ar atmosphere, whereby a rare earth magnet (rare earth sintered magnet) is obtained. ).

At this time, the rare earth alloy ribbon according to the present invention was used as a mother alloy, and R-rich R-TM-B type alloy powder (TM: transition metal such as Fe, Co) was added as an additive aid in an amount of 1 to 20% by mass. May be. Furthermore, it is optional to appropriately mix a lubricant such as stearic acid.
Further, the rare earth alloy ribbon of the present invention can be used as a raw material for a bond magnet formed into a fine powder and bonded with a resin or the like.

The rare earth magnet of the present invention thus obtained can have high characteristics in which the maximum energy product exceeds 400 kJ / m ³ at the mass production level.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not limited to the following Example. In the following example, the volume ratio of the chill crystal and the four-phase coexistence region was measured by measuring the area ratio (%) in the cross section of the alloy ribbon by observing a photograph with a polarizing microscope, and using this as the volume ratio (%). The average particle diameter of the α-Fe phase, the average particle diameter of the R-rich phase, and the average particle diameter of the B-rich phase in the four-phase coexistence region are values measured by an Auger electron spectrometer having an FE electron gun. Indicates.

[Example]
About 500 kg of raw materials weighed to have a composition of composition formula 27.8Nd-0.95B-0.05C-1.0Co-80.0Fe-0.2Al (each mass%) were melted at high frequency in an Ar atmosphere. It heated to 1,550 degreeC and it was set as the molten metal. In a single roll method in which a molten roll is supplied in about 8 minutes in a state where a cooling roll having an outer diameter of 600 mm and a thickness of 20 mm is rotated at a speed of 64 revolutions / minute so as to have a peripheral speed of about 2.0 m / second. Cooled to produce an alloy ribbon for the main phase. The material of the cooling roll used was oxygen-free copper to which about 0.6% by mass of Cr and about 0.07% by mass of Zr were added. Its thermal conductivity was about 340 W / m · ° C., and cooling started. Previously, it was polished with # 200 sandpaper for about 5 minutes to obtain a metallic luster. The production of the alloy ribbon as described above was repeated 10 lots. Table 1 shows the average thickness and structure of each manufactured alloy ribbon.

The manufactured alloy ribbon was subjected to a hydrogen storage treatment at room temperature for 4 hours, and then heated in a vacuum at 600 ° C. for 8 hours for a dehydrogenation treatment to obtain a main phase alloy powder. Separately, an alloy having a composition of 40.0Nd-16.0Dy-0.5B-25.0Co-18.3Fe-0.2Al (mass%) was produced by a die casting method, To obtain an alloy powder for grain boundary phase. Thereafter, 93% by mass of the obtained main phase alloy powder, 6.95% by mass of grain boundary phase alloy powder, and 0.05% by mass of stearic acid as a lubricant were mixed. Next, the obtained coarse powder was finely pulverized to a mean particle size of 4.8 μm using a jet mill in a nitrogen atmosphere. The obtained fine powder was pressure-molded while being oriented in a magnetic field of 955 kA / m in a nitrogen atmosphere in which oxygen was blocked. Next, this molded body was sintered in vacuum at 1,020 ° C. for 2 hours, and further subjected to aging heat treatment in an Ar atmosphere for 2 hours to produce a magnet alloy. Table 2 shows the magnetic property values for each lot of the manufactured magnet alloy.
In addition, the oxygen concentration in the obtained magnet alloy was 0.12-0.17 mass%, and C concentration was 0.07-0.09 mass%.

[Comparative example]
A molten alloy having the same composition as the example was melted at high frequency in an Ar atmosphere and heated to 1,450 ° C. By a single roll method in which a molten roll is supplied in a state where a cooling roll having an outer diameter of 300 mm and a thickness of 40 mm is rotated at a speed of 128 revolutions / minute so as to have a peripheral speed of about 2.0 m / second as in the embodiment. Cooled to produce an alloy ribbon for the main phase. The material of the cooling roll is the same as in the example. The production of the alloy ribbon was repeated 10 times. Table 1 shows the average thickness and structure of each manufactured alloy ribbon. Subsequent steps were carried out in the same manner as in the Examples to produce a magnet alloy. Table 2 shows the magnetic property values for each lot of the manufactured magnet alloy. The oxygen concentration in the magnet alloy was 0.13 to 0.19 mass%, and the C concentration was 0.07 to 0.09 mass%.

As shown in Table 1, in the alloy ribbon of the example, not only the precipitation amount is stable with 10 to 13% by volume of chill crystals and 6 to 9% by volume of the four-phase coexistence region, but also the coexistence of four phases. The average particle diameter of the α-Fe phase in the region was also controlled to 2.9 to 3.2 μm. The average particle size of the R-rich phase was 4.1 to 5.3 μm, and the average particle size of the B-rich phase was 2.0 to 2.5 μm.
On the other hand, the alloy ribbon of the comparative example has a small variation in the amount of chill crystals of 1 to 6% by volume and large variation. The amount of precipitation in the four-phase coexistence region is 4 to 10% by volume, but the average particle size of the α-Fe phase in the four-phase coexistence region is 5.2 to 20.5 μm and exceeds 8 μm. doing. The average particle size of the R-rich phase is 7.8 to 24.5 μm, and the average particle size of the B-rich phase is 4.1 to 10.2 μm.

As shown in Table 2, the magnetic alloy of the example uses an alloy ribbon that stably has a chill crystal and a four-phase coexistence region with a fine grain size. .43T or higher, iHc is 1,210 kA / m or higher, bHc is 1,100 kA / m or higher, and (BH) max is 400 kJ / m ³ or higher. On the other hand, the magnetic properties of the magnet alloy of the comparative example are not only small in the amount of chill crystals, but also the particle diameter of the α-Fe phase in the four-phase coexistence region is large. Not only does it fall under the magnetic properties of magnet alloys, but its variation is also great.

Claims (4)

  R (R is one or a combination of two or more of rare earth elements including Y), T (T is Fe, or Fe and Co), B as a main component, and R is 26.8-32.0 mass%, B is 0.3 to 1.5 mass%, C is 0.005 to 1.2 mass%, additive element M (M is Ga, Zr, Nb, Hf, Ta, W, Mo, Al, Si, V, Cr, Ti, Cu, Ag, Mn, Ni, Ge, Sn, Bi, Pb, Zn) or a combination of two or more) is 0 to 4.0% by mass, the balance is T and inevitable impurities. When the molten alloy is rapidly cooled with a cooling roll to obtain an alloy ribbon, the surface layer in contact with the molten alloy has a thickness of 10 to 30 mm and a thermal conductivity of 200 W / m · ° C. or more as the cooling roll. Or a cooling roll formed of a copper alloy and having an outer diameter of 500 to 1,000 mm Use and method for producing a rare earth alloy ribbon, characterized by rapidly cooling the cooling roll interior is rotated at 20 to 120 revolutions / min while water-cooling in the molten alloy.   The method for producing a rare earth alloy ribbon according to claim 1, wherein the molten alloy temperature is set to 1,500 to 1,600 ° C. An α-Fe phase produced by the method according to claim 1 or 2, having an average thickness of 100 to 800 µm, a chill crystal of 1 to 30% by volume, and an average particle size of 8 µm or less, It has a four-phase coexistence region consisting of an R-rich phase with an average particle size of 10 μm or less, a B-rich phase with an average particle size of 8 μm or less, and an R ₂ T ₁₄ B phase in a volume ratio of 1 to 20%, the balance being spherical crystals A rare earth alloy ribbon characterized by comprising a phase caused by crystals and an additive element M. A rare earth magnet comprising the rare earth alloy ribbon according to claim 3.