JPH0549737B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field] The present invention relates to a method for manufacturing rare earth/iron/boron permanent magnets that does not use cobalt, which is expensive and a scarce resource. [Prior Art] Typical permanent magnets currently used are alnico, hard ferrite, and rare earth cobalt magnets. However, due to the recent instability in the cobalt raw material situation, the demand for Alcon magnets containing 20 to 30% cobalt by weight has decreased, and cheap hard ferrite, which is mainly composed of iron oxides, has become the mainstream magnet material. It became. On the other hand, rare earth cobalt magnets contain 50 to 65% by weight of cobalt and use Sm, which is not contained in rare earth ores, so they are very expensive, but because their magnetic properties are much higher than other magnets, they are mainly used for small size magnets. It is often used in high value-added magnetic circuits. The present inventor previously developed a new high-performance permanent magnet that does not contain expensive Sm or Co.
proposed a permanent magnet (at least one rare earth element containing Y) (Japanese Patent Application Laid-open No. 59-46008), and
We have discovered that by subjecting a B-R alloy to heat treatment under specific conditions after sintering, so-called aging treatment, the magnetic properties, especially the coercive force and the squareness of the demagnetization curve, can be significantly improved after sintering. (Tokukai Akira
59−217304). [Problems to be Solved] The present applicant has further discovered that the coercive force and the squareness of the demagnetization curve can be significantly improved by performing a two-stage heat treatment consisting of specific conditions in the heat treatment process. (Special Application No. 59-16923). In other words, permanent magnets that are heat-treated in two stages under specific conditions after sintering have a coercive force of iHc3kOe or more and a residual magnetic flux density.
Br4kG or more and maximum energy product (BH)
It has max4MGOe or more. By the way, recently, applications of permanent magnets at high temperatures and applications with strong reverse magnetic fields such as motors, generators, and magnetic couplings have been expanding, and magnetic properties, especially coercive force and squareness of demagnetization curves, have been expanding. There is a need for excellent permanent magnets. The object of the present invention is to obtain a permanent magnet that further improves the coercive force and the squareness of the demagnetization curve of a new permanent magnet material whose main components are rare earth elements, boron, and iron that do not contain expensive and rare Co. . Another object of the present invention is to obtain a permanent magnet that has excellent high-temperature resistance properties so that it can withstand use at high temperatures, and that can also withstand applications with strong reverse magnetic fields. [Summary of the structure of the invention] In order to achieve the above object, the present inventors conducted intensive research and found that the magnetic properties of Fe-BR alloy within a certain composition range can be improved by compacting and sintering powder with a specific particle size. It has been found that by performing heat treatment under specific conditions, particularly three-stage heat treatment, after sintering, the magnetic properties after sintering, particularly the coercive force and the squareness of the demagnetization curve, can be significantly improved. That is, the present invention has R of 8 to 30% as an atomic percentage.
(However, R is at least one kind of rare earth element including Y), 2 to 28% B, and the balance Fe is formed and sintered at 750 to 1000℃ after sintering.
After the first heat treatment at a temperature of 3 to 2000℃/min, the cooling rate is 3 to 2000℃/min. After the secondary heat treatment is 480 to 700℃, the cooling rate is 10 to 2000℃/min.
After cooling to 200℃ or less, raise the temperature again at a heating rate of 10 to 2000℃/min, perform tertiary heat treatment at a temperature of 350 to 450℃, and cool to 200℃ or less at a cooling rate of 10 to 2000℃/min. Provided is a method for manufacturing a permanent magnet including: [Preferred Embodiments of the Invention] The present invention will be described in detail below. The present invention is not limited to magnetically anisotropic permanent magnets, but can also obtain magnetically isotropic permanent magnets by performing molding without applying a magnetic field during the manufacturing process. In the permanent magnet of the present invention, B has a coercive force iHc
In order to satisfy 5kOe or more, the residual magnetic flux density must be 2% (hereinafter % indicates the atomic percentage in the alloy) or more.
Br is required to be 28% or less to obtain more than about 4kG of hard ferrite. As boron B, pure boron or ferroboron can be used, and those containing Al, Si, C, etc. as impurities can also be used. Also, R is coercive force
8% or more is required for 5kOe or more. However, R is flammable, difficult to handle and manufacture industrially, and is also expensive, so it should be kept at 30% or less. As R, a light rare earth element which is abundant in resources can be used, and since Sm is not necessarily required or does not need to be mainly composed of Sm, the raw material is inexpensive and extremely useful. The rare earth element R used in the present invention includes Y, and is a rare earth element including light rare earths and heavy rare earths, and one or more of them is used. That is, as R
Nd, Pr, La, Ce, Tb, Dy, Ho, Er, Eu,
Included are Sm, Gd, Pm, Tm, Yb, Lu and Y. As R, it is sufficient to have one of Nd, Rr, Dy, Tb, Ho, etc., and Nd and Pr are particularly preferred, especially (Nd+Pr), which accounts for 50% or more (particularly 80% or more) of the total R.
This is preferable in order to reliably achieve high magnetic properties at low cost. Generally, it is sufficient to have one type of these R, but in practice, a mixture of two or more types (mitsushimetal, didymium, etc.) can be used for reasons such as convenience of availability, and Sm, Y, La,
Ce, Gd, etc. are other R, especially Nd, Pr, Dy, Tb, Ho.
It can be used as a mixture with etc. however
It is better for Sm and La to be as small as possible. Note that R does not need to be a pure rare earth element; it may contain impurities that are unavoidable during manufacturing (other rare earth elements, Ca,
Those containing Mg, Fe, Ti, C, O, etc.) can also be used. In addition, R is one or more of Dy, Tb, Gd, and Ho as R ₁ , and R ₂ is one or more of Dy, Tb, Gd, and Ho.
A combination of one or more rare earth elements containing Y other than R ₁ in a total of 80% or more of Nd and Pr is most preferable for the effect of increasing iHc. In addition to these B and R, the balance of the magnet material of the present invention is Fe, but there is no problem in that it contains impurities that are unavoidable during production. In the basic composition of Fe-BR-R, 13-16%R,
6~11%B is (BH) max35MGOe or more, 13~
14.5%R, 6~7.5%B is 40MGOe or more (maximum
45MGOe or more). A predetermined amount of additive element M can be added to the permanent magnet of the present invention whose main components are Fe, B, and R. That is, the additive element M has the effect of increasing the coercive force, particularly in the maximum region of Br, and has the effect of improving the squareness. Increasing the coercive force increases the magnet's stability at high temperatures, expanding its applications. However, as the amount of M added increases, Br decreases, and therefore the maximum energy product (BH) mal decreases. M-containing alloys are very useful as there have recently been many applications that require a high coercive force Hc even if (BH)max is a little low, but (BH)max is particularly useful in the range of 8MGOe or higher. It is. In order to clarify the effect of each addition of the additive element M on Br, the amount added was varied.
The change in Br was measured and the Br of hard ferrite was approximately 4kG.
Considering the much higher range than the hard ferrite (BH) max of about 4MGOe, the upper limit of the addition amount of M is V 9.5%, Nb 12.5%, Ta 10.5%, Mo 9.5
%, W 9.5%, Cr 8.5%, Al 9.5%, Ti 4.5%,
Zr 5.5%, Hf 5.5%, Mn 8.0%, Ni 8.0%, Ge
7.0%, Sn 3.5%, Bi 5.0%, Sb 2.5%, Si 5.0
%, and Zn2.0%. M does not contain 0% and may be used alone or in combination of two or more. When containing two or more types of M, it generally indicates the intermediate value of the characteristics of each added element, and the content of each element is within the range of the above percentage, and the maximum content is the maximum value among the added elements. less than atomic percent of the substance. M is generally effective in small amounts (approximately 0.1 to 3%, however, Sb is 1% or less, Zn is 0.5
% or less), preferably 0.1 to 1%, V,
Nb, Cr, Ta, Mo, W, and Al are preferred. The permanent magnet of the present invention has a maximum energy product (BH) max in the composition mainly composed of FeBR.
is much higher than that of hard ferrite magnets (~4MGOe). In the magnetically anisotropic permanent magnet according to the present invention, when the light rare earth element is contained in a composition range of 50% or more of the total R and the composition is in the range of 12 to 20% R, 4 to 24% B, and the balance Fe, or Add one or more of the following additive elements M: V 6.5% or less, Nb 8.5% or less, Ta
8.5% or less, Mo 5.5% or less, W 5.5% or less, Cr
4.5% or less, Al 5.5% or less, Ti 3.5% or less, Zr 3.5
% or less, Hf 3.5% or less, Mn 4.0% or less, Ni 2.0
% or less, Ge 4.0% or less, Sn 1.0%, Bi 3.0 or less,
When Sb is 0.5% or less, Si is 4.0% or less, and Zn is 1.0% or less, and two or more types of M are combined, the total amount of M includes the atomic percent or less of the maximum value of each element of M contained. For a composition range, (BH)max is
This is a preferred range showing 17MGOe. Furthermore, the above
In the case of a composition range of _R1 0.2 to 3%, R13 to 19%, B5 to 11%, and the balance Fe, or the above-mentioned additional element M is added to the composition.
One or more types (0.1 to 3%, especially 0.1 to 1
%) If included, maximum energy product (BH)
This is the most preferable range that exhibits magnetic properties of max 35 MGOe or higher, and even max 42 MGOe or higher. For isotropic, 10-25% R, 3-23% B, balance
In Fe (BH) max4MGOe or more, 12~20%
In R, 5-18% B, balance Fe (BH)
max5MGOe or higher. The crystal phase of the magnet alloy in this invention has a main phase of at least 50 vol% or more (preferably 80 vol% or more)
It is essential to produce a sintered permanent magnet with excellent magnetic properties that the grain boundaries of the main phase are surrounded by at least a nonmagnetic phase. The non-magnetic phase is mainly an R-rich phase (R90 atomic%
metals above) or further B-rich phase (R ₂ Fe ₇ B ₆
or R ₁ Fe ₄ B ₄ etc.), and even a small amount is effective; for example, 1 vol% or more is a sufficient amount. The parameters of the tetragonal lattice are a about 8.8 Å and c about
12.2 Å, and its central composition is thought to be R ₂ Fe ₁₄ B. It is believed that the three-stage aging treatment of the present invention provides a more preferable metal structure, thereby providing high magnetic properties. In addition, in the magnetically isotropic permanent magnet according to the present invention, light rare earths such as Nd and Pr are the main components of R (total R medium and light rare earths are 50 atomic % or more), and 12 to 16% R, 6
In the case of a composition range of ~18% B and the balance Fe, or if the composition contains one or more additive elements M similar to the above anisotropic magnet (BH)
This is a preferable range for an isotropic permanent magnet with a max of 8 MGOe or more (maximum 11 MGOe or more) that exhibits extremely high magnetic properties. Regarding isotropy, M
0.1 to 3% is sufficiently effective, and 0.1 to 1% is preferable, and the preferable elements are the same as in the case of anisotropy. In the present invention, binders and lubricants are generally not used in the case of anisotropic magnets because they interfere with orientation during molding, but in the case of isotropic magnets, binders, lubricants,
By including a lubricant or the like, it is possible to improve the press efficiency and increase the strength of the molded product. The permanent magnet of the present invention can tolerate the presence of impurities that are unavoidable in industrial production, whether it is anisotropic or isotropic. That is, in addition to R, B, and Fe, within a certain range C,
Ca, Mg, P, Cu, S, O, etc. can also be contained, making it possible to improve manufacturability and reduce costs.
C, Ca, Mg each 4.0% or less, P, Cu each 3.3% or less,
If the content is S2.5% or less and O2.0% or less (however, the total amount is less than the maximum value of each element), it can be used as a magnet. , useful. However, the levels of these impurities are determined depending on the desired properties. In particular, in order to achieve high magnetic properties of (BH)max35MGOe or higher, it is preferable to keep the contents of O, C, and Ca particularly low. Ca, Mg, P, Cu, etc. are obtained from inexpensive raw materials, and C is obtained from organic forming aids, etc.
S and O may be mixed in during the manufacturing process. The permanent magnet of the present invention is obtained by the above-mentioned specific manufacturing method. The manufacturing method of the present invention involves forming and sintering the alloy powder having a composition mainly composed of FeBR, and after sintering, the
After primary heat treatment at a temperature of 1000℃, cooling to 680℃ or less at a cooling rate of 3 to 2000℃/min, then 480 to 700℃.
After secondary heat treatment at a temperature of 10 to 2000℃/min, cool to below 200℃ at a cooling rate of 10 to 2000℃/min.
It is characterized in that the temperature is raised at a heating rate of 100° C./min, and after the tertiary heat treatment at a temperature of 350 to 450° C., the temperature is cooled to 200° C. or less at a cooling rate of 10 to 2000° C./min. The alloy powder preferably has an average particle size of generally 0.3 to 80 μm. It is possible to make it even finer if a completely non-oxidizing atmosphere is ensured, but since the powder is extremely oxidizing, it will oxidize and catch fire.
Under normal conditions, the thickness is preferably 0.3 μm or more. The forming and sintering process generally involves press forming (in a magnetic field in the case of anisotropy, and without a magnetic field in the case of isotropy) and sintering.
Sintering is preferably carried out in a reducing or non-oxidizing atmosphere (in vacuum or in an inert gas atmosphere under reduced pressure, normal pressure or pressure) at a temperature of 900 to 1200°C. When sintering at relatively low temperatures, it is necessary to sinter for a long time. The manufacturing method of the present invention will be explained below based on experimental examples in the case of magnetically anisotropic permanent magnets. As starting materials for the experiment, Fe is electrolytic iron with a purity of 99.0% or more, B is pure boron with a purity of 99.0% or more and ferroboron with a purity of 90.0% or more, and R is a purity of 95%.
I used the above. These raw materials are blended and adjusted within the above range, melted and alloyed by high frequency melting, arc melting, etc. in a vacuum or inert gas atmosphere, and then cooled to produce an alloy. Coarsely pulverized powder may be obtained by coarsely pulverizing with a shear or the like, or coarsely pulverized powder may be obtained by a reduction method from an oxide using a reducing agent such as Ca. The coarsely ground powder thus obtained is further finely ground using a jet mill, a ball mill, or the like. For fine pulverization, either dry pulverization in an inert gas atmosphere or wet pulverization in an organic solvent such as acetone or toluene can be used. The alloy powder obtained by pulverization has an average particle size of 0.3 to 80 μm. If the average particle size is less than 0.3 μm, the oxidation of the powder will be significant during the pulverization and subsequent steps, and the density after sintering will not increase, and the resulting magnetic properties will be poor. If the average particle size exceeds 80 μm, excellent magnetic properties, especially high coercive force, cannot be obtained. In order to exhibit excellent magnetic properties, the average particle size of the fine powder is preferably 1 to 40 μm, particularly 2 to 20 μm.
is most preferred. Powder with an average particle size of 0.3~80μm,
In the case of an anisotropic magnet, it is
(above) to perform pressure molding. The pressure used for molding is
0.5-3.0 tons/ ^cm2 is preferred. For pressure molding in a magnetic field, either a method of molding the powder as it is or a method of molding it in an organic solvent such as acetone or toluene can be used. The obtained molded body is heated in a reducing or non-oxidizing atmosphere, for example, in a vacuum of 10 ^-2 Torr or less or in an atmosphere of 99.9% or more inert gas or reducing gas under a pressure of 1 to 760 Torr.
Sinter at a temperature of 1200℃ for a specified time. Sintering temperature
If the temperature is lower than 900°C, sufficient sintered density and high residual magnetic flux density cannot be obtained. Furthermore, when the temperature exceeds 1200°C, the sintered body is deformed and the orientation of crystal grains is disrupted, resulting in a decrease in residual magnetic flux density and a decrease in the squareness of the demagnetization curve. Further, the sintering time may be 5 minutes or more, but if it is too long, it will be a problem in terms of mass production, so 0.5 to 4 hours is preferable from the viewpoint of the development of magnetic properties. Note that the sintering atmosphere is preferably a non-oxidizing atmosphere such as a high vacuum, an inert gas, or a reducing gas, since R in the composition is extremely easily oxidized at high temperatures. When an inert gas is used, the sintering can be carried out under a reduced pressure atmosphere of 1 to less than 760 Torr in order to obtain a high sintering density. There is no need to specify the temperature increase rate during sintering, but if a wet molding method is used, the temperature should be increased at 40℃/min or less to remove the organic solvent, or the temperature should be increased at 200 to 800℃ during heating. Preferably, the temperature is maintained for 0.5 hours or more. When cooling after sintering, a cooling rate of 20°C/min or less is preferable in order to reduce product variation, and in order to improve the magnetic properties due to aging treatment in the subsequent heat treatment, the cooling rate after sintering is 100°C/min. The above is preferable. However, it is also possible to immediately enter a heat treatment step following sintering. The heat treatment after sintering consists of the following steps. First, the sintered body is subjected to a first heat treatment at a temperature of 750 to 1000℃, then cooled to 680℃ or less at a cooling rate of 3 to 2000℃/min, and then a second heat treatment at a temperature of 480 to 700℃. and then at a cooling rate of 10 to 2000℃/min.
Cool to below 200℃, then cool again to 10~2000℃/
Raise the temperature at a heating rate of min, and at a temperature of 350 to 450℃
The second stage heat treatment consists of cooling to below 200°C at a cooling rate of 10 to 2000°C/min. If the temperature of the first stage heat treatment is less than 750°C, the first stage heat treatment will not be effective and the obtained coercive force will be low, and if it exceeds 1000°C, the crystals of the sintered body will grow grains and the coercive force will decrease. . The cooling rate after the first stage heat treatment is cooling rate 3.
If it is less than 2000°C/min, the coercive force and the squareness of the demagnetization curve will decrease, and if it exceeds 2000°C/min, micro-cracks will occur in the sintered body and the coercive force will decrease. The temperature range in which this predetermined cooling rate should be maintained is limited to a range from the first stage heat treatment temperature to 680° C. or less. 680℃
The following cooling rates are available for both slow cooling and rapid cooling. The lower limit of the cooling temperature range at the specified cooling rate is 680
When the temperature is below ℃, the coercive force decreases significantly. The second heat treatment is at 680℃ after the first heat treatment.
After cooling by prescribed quenching to below 480
Performed in a temperature range of ~700℃. If the primary heat treatment is followed by cooling, such as furnace cooling, then the secondary heat treatment is performed, the obtained magnetic properties are poor. Note that the secondary heat treatment can be performed following a predetermined deterioration after the primary heat treatment, but it can also be performed after a predetermined cooling and after being allowed to cool. The second stage heat treatment temperature is limited to 480-700°C.
If it is below 480°C or above 700°C, the coercive force and the squareness of the demagnetization curve will decrease. After the second stage heat treatment, cool to below 200℃ at a cooling rate of 10 to 2000℃/min, and then cool again to 10 to 2000℃/min.
The temperature rises at a heating rate of
When the value exceeds min, the magnetic properties, particularly the coercive force and the squareness of the demagnetization curve, deteriorate. The temperature range in which this predetermined cooling rate should be maintained is limited to a range from the second stage heat treatment temperature to 200° C. or less. As for the cooling rate below 200°C, both slow cooling and rapid cooling are possible. When the lower limit of the cooling temperature range at a predetermined cooling rate is 200°C or higher, the coercive force and the squareness of the demagnetization curve are significantly reduced. In order to improve magnetic properties and reduce variations, the lower limit of the cooling temperature range at a predetermined speed is preferably 150°C or less, and most preferably 100°C or less. In order to increase the squareness of the coercive force and demagnetization curve and reduce variations in magnet properties, the cooling rate after the second heat treatment and the subsequent heating rate should be 20 to 1500℃/
min, and most preferably 40 to 1000°C/min. The feature of this three-stage heat treatment is that after the secondary heat treatment is performed at a temperature of 480 to 700℃, it is cooled to below 200℃ and heated to a temperature of 300 to 700℃.
The square shape of the coercive force and demagnetization curve after passing through a temperature range of 250°C with a prescribed rapid cooling, then increasing the temperature again to the third stage heat treatment temperature, and passing through a range of 250 to 300°C with a prescribed rapid temperature increase. Perform tertiary heat treatment at a predetermined temperature range of 350 to 450℃, which is effective for improving properties.After tertiary heat treatment,
The purpose is to cool down to below 200℃ at a cooling rate of 200℃/min. If the secondary heat treatment is followed by tertiary heat treatment by cooling such as furnace cooling,
The amount of increase in magnetic properties obtained is low. Also, when cooling to 200℃ or less after secondary heat treatment and raising the temperature to the temperature for tertiary heat treatment, and 200℃ after tertiary heat treatment.
Cooling and temperature raising are performed at a predetermined rate in order to eliminate the influence of the metal phase instability region that degrades magnetic properties between 250 and 300° C. when cooling to 250 to 300° C. Note that the tertiary heat treatment can be performed following the predetermined cooling after the secondary heat treatment, but it can also be performed after the predetermined cooling and cooling. The third stage heat treatment temperature is limited to 350 to 450°C.
If it is below 350°C or above 450°C, the coercive force and the squareness of the demagnetization curve will decrease. In order to increase the squareness of the coercive force and demagnetization curve and reduce the variation in magnet properties, the temperature range for the third stage heat treatment is 360°C.
-440 degreeC is desirable, and 375-425 degreeC is most desirable. The time for the first heat treatment is not particularly limited, but it is preferably 0.5 to 8.0 hr, since it is difficult to control the temperature if it is short, and the industrial merit decreases if it is long. The heat treatment times for the second and third stages are also not particularly limited, but 0.5 to 12.0 hr is preferable since it is difficult to control the temperature if the heat treatment is short and the industrial merit decreases if the heat treatment is long. In particular, in order to increase the coercive force and the squareness of the demagnetization curve, the third heat treatment time should be
1.0~6.0hr is most desirable. Since R in the alloy composition rapidly reacts with oxygen or moisture at high temperatures, the aging treatment atmosphere should be a vacuum with a vacuum level of 10 ^-3 Torr or less, and an inert gas or reducing gas atmosphere with a purity level of the atmosphere. 99.99% or higher is desirable. Note that the sintering temperature is selected within the above range depending on the composition of the permanent magnet, and the aging treatment temperature is selected below the sintering temperature. In addition, the aging treatment including these 1-stage, 2-stage, and 3-stage heat treatments can be performed following sintering, or can be performed by cooling to room temperature after sintering and then raising the temperature again; in either case, the results are the same. magnetic properties are obtained.
However, once cooled to room temperature, the temperature will drop from the sintering temperature.
The temperature range below 200°C shall be cooled at a cooling rate of 10 to 2000°C/min. In addition, when a magnetic field is applied in the third aging treatment step of the present invention, magnetic properties equivalent to or better than those without a magnetic field can be obtained, but when carried out with a magnetic field applied, 5 kOe is required to improve the magnetic properties. A magnetic field larger than this is required. Further, it is particularly desirable to apply a magnetic field in a temperature range of 200 to 350° C. in order to improve magnetic properties, particularly coercive force. The above description has been made regarding the case of magnetically anisotropic permanent magnets, but the present invention is not limited to the case of magnetically anisotropic permanent magnets, but also applies to the case of magnetically isotropic permanent magnets in which forming is performed during the process without applying a magnetic field. Therefore, a completely similar method can be adopted. As described in detail above, the present invention is based on Co-free Fe・
The magnetic properties of a new permanent magnet mainly composed of B/R have been improved, especially the coercive force and the squareness of the demagnetization curve, and it is a permanent magnet that has excellent high temperature resistance and can withstand applications with strong reverse magnetic fields. It has extremely high value. The aspects and effects of the present invention will be further explained below with reference to Examples. However, the present invention is not limited to the examples and described aspects. Example 1 An alloy with an atomic percentage composition of 73Fe10B9Nd8Pr was
After melting in a gas arc, it was cast in a water-cooled copper mold. This alloy was coarsely ground to 40 mesh or less using a stamp mill, and then finely ground using a ball mill to an average particle size of 2.5 μm in an organic solvent. After the obtained powder was pressure-molded in a 15kOe magnetic field at a pressure of 1.5ton/ ^cm2 ,
% purity 220 TorrAr at 1100℃ for 2 hours,
After sintering, it was cooled to room temperature at a cooling rate of 150°C/min. Furthermore, the first aging treatment was performed at 820℃ for 2 hours in a vacuum of 3×10 ^-5 Torr, and the cooling rate was 400℃.
After cooling to below 600℃ at ℃/min, a second aging treatment is performed at 620℃ for 4 hours, and then 400℃/min.
The magnet of the invention I got it. The magnet characteristics results are shown in Table 1 along with a comparative example (magnet subjected to two-stage aging treatment).

[Table] Example 2 Fe-B- having the atomic percentage composition shown in Table 2
The R alloy was melted in an Ar gas arc and then cast into a water-cooled copper mold. This alloy is stamped and milled.
After coarsely grinding to 50mesh or less, the average particle size is reduced in an organic solvent.
It was ball milled to 3.2 μm. The obtained powder was pressure molded at a pressure of 1.5 ton/cm ² in a 15 kOe magnetic field, and then molded at 1080°C in 180 TorrAr with 99.999% purity.
After sintering, it was rapidly cooled to room temperature at a cooling rate of 800°C/min. Furthermore, 500Torr high purity Ar
The first stage of aging treatment is carried out inside at 800℃ for 3 hours.
After cooling to 630℃ or less at 350℃/min, 600℃,
450℃/min after 4hr second aging treatment
After cooling to 120℃, the temperature was raised at 80℃/min.
After aging the stage at 400℃ for 1 hour, 250℃
This alloy magnet was obtained by cooling to 120°C at a rate of °C/min.
The magnet characteristics results are shown in Table 2 together with a comparative example (magnet subjected to two-stage aging treatment).

【table】

[Table] Example 3 An Fe-B-R alloy having the following atomic percentage composition was melted in an Ar gas arc and then cast into a water-cooled copper mold. This alloy is stamped and milled into 35mesh
After coarse pulverization, the mixture was pulverized using a ball mill in an organic solvent to an average particle size of 3.5 μm. After the obtained powder was pressure molded at a pressure of 1.0 ton/cm ² in a non-magnetic field,
Sintered at 1080℃ for 4 hours in 180TorrAr with % purity,
After sintering, it was rapidly cooled to room temperature at a cooling rate of 300°C/min. Furthermore, a first aging treatment was performed at 800°C for 2 hours in 600 Torr high purity Ar, and after cooling to below 600°C at a cooling rate of 250°C/min, a second aging treatment was performed at 600°C for 1 hour. After 400℃/min
After cooling to 100°C at
The magnet of the present invention was obtained by cooling to 150°C. Samples subjected to two-stage aging treatment for magnetic properties results (comparative example)
It is shown in Table 3.

[Table] Example 4 An Fe-B-R alloy having the following atomic percentage composition was high-frequency melted in Ar gas and then cast into a water-cooled copper mold. This alloy was coarsely ground to 35 mesh or less using a stamp mill, and then finely ground by a ball mill to an average particle size of 2.0 μm in an organic solvent. The obtained powder was placed in a 15kOe magnetic field.
After pressure molding at a pressure of 1.5 ton/cm ² , sintering was performed at 1060° C. for 2 hours in 200 TorrAr of 99.99% purity, and after sintering, the material was rapidly degraded to room temperature at a cooling rate of 500° C./min. Further, the first stage aging treatment was performed at 800℃ for 1 hour in 760 TorrAr, and after cooling to room temperature at a cooling rate of 300℃/min, the second stage aging treatment was further performed at 620℃ for 3 hours, and then the temperature was increased to 400℃. /min to 100°C, then heated at 120°C/min, third stage aging treatment at 375°C for 1 hour, and then cooled to 150°C at 200°C/min to obtain the magnet of the present invention. . The magnetic property results are shown in Table 4 together with a comparative example (after two-stage aging treatment).

[Table] Example 5 Fe-BRM alloy powder having an average particle size of 1 to 6 μm and the original percentage composition shown in Table 5 was press-molded in a 15 kOe magnetic field at a pressure of 1.5 Ton/cm ² to give a powder of 99.999. %
Sintered at 1100℃ for 2 hours in 180TorrAr of purity,
After sintering, it was rapidly cooled to room temperature at a cooling rate of 600°C/min. Furthermore, aging treatment was performed at 800℃ for 2 hours in high-purity Ar of 550Torr, and then 550℃ at 300℃/min.
After cooling to below, first aging treatment at 600℃ for 2 hours, then cooling to 120℃ at 350℃/min.
The temperature was raised at a rate of 150°C/min, a third aging treatment was performed at 380°C for 1 hour, and then the magnet was cooled to 120°C at a rate of 250°C/min to obtain a permanent magnet. Comparative example of magnet characteristics results (2
The results are shown in Table 5 along with the magnet properties (after stage aging treatment).

【table】

[Table] Example 6 Fe-B-R-M having the following atomic percentage composition
The alloy was obtained by high-frequency melting in Ar gas and then cast into a water-cooled copper mold. This alloy was coarsely ground to 35 mesh or less using a stamp mill, and then finely ground by a ball mill to an average particle size of 2.5 μm in an organic solvent. The obtained powder was placed in a 12kOe magnetic field.
After pressure molding at a pressure of 1.5 ton/cm ² , sintering was performed at 1100° C. for 2 hours in 200 TorrAr of 99.999% purity, and after sintering, it was rapidly cooled to room temperature at a cooling rate of 600° C./min. Furthermore, after performing a first stage aging treatment at 800°C for 1 hour in 760 TorrAr, and cooling to room temperature at a cooling rate of 250°C/min, a second stage aging treatment was performed at 600°C for 2 hours. After cooling to 120°C at 450°C/min, heating at 150°C/min, and performing the third aging treatment at 380°C for 4 hours, then at 250°C/min.
The magnet of the present invention was obtained by cooling to 150°C. The magnetic property results are shown in Table 6 together with a comparative example (after two-stage aging treatment).

【table】

Claims (1)

[Scope of Claims] 1 8 to 30% R as an atomic percentage (wherein R is Y
at least one rare earth element including), 2-
A process of forming and sintering an alloy powder whose main components are 28% B and the balance Fe, at a temperature of 750 to 1000℃ after sintering, and at a cooling rate of 3 to 2000℃/min after primary heat treatment.
The process of cooling to below 680℃, secondary heat treatment at a temperature of 480 to 700℃, and a cooling rate of 10 to 2000℃/min.
Cooling process to below 200℃, and then again
Raise the temperature at a rate of 10 to 2000℃/min to 350 to 450℃
A method for producing a permanent magnet, comprising the steps of tertiary heat treatment at a temperature of 10 to 2000C/min and cooling to 200C or less at a cooling rate of 10 to 2000C/min. 2 In place of a part of the Fe, one or more of the following additive elements M are contained in the following specified percentage or less based on the total composition (however, when two or more types of additive elements M are included, the following of the contained additive elements) 2. The method according to claim 1, wherein: V 9.5%, Nb 12.5%, Ta 10.5%, Mo 9.5
%, W 9.5%, Cr 8.5%, Al 9.5%, Ti 4.5%,
Zr 5.5%, Hf 5.5%, Mn 8.0%, Ni 8.0%, Ge
7.0%, Sn 3.5%, Bi 5.0%, Sb 2.5%, Si 5.0
%, and Zn 2.0%.