JP2006253413A - Iron group rare earth nano composite magnet and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rare-earth-based nano composite magnet improving rectangularity and containing Ti. <P>SOLUTION: The molten metal of an alloy has a compositional formula of (Fe<SB>1-n</SB>T<SB>n</SB>)<SB>100-x-y-z-l-m</SB>Q<SB>x</SB>R<SB>y</SB>Ti<SB>z</SB>Nb<SB>l</SB>M<SB>m</SB>. In this case, T is an element selected from a group of Co and Ni, Q is an element selected a group of B and C, R is an element selected from a group of yttrium and a rare earth element, and M is an element selected from a group of Al, Si, Mn, Cu, Zn, Ga, Ag, Pt, Au, Pb, V, Ta, W, Mo, and Cr; x, y, z, l, and m are 10≤x≤17, 6≤y≤11, 0.1≤z≤10, 0.1≤l≤6, and 0≤m≤6 atom.%, respectively; and 0≤n≤0.5 is met. The molten metal alloy is cooled and coagulated by a melt spinning method. An iron group rare earth nano composite magnet, which has magnetic characteristics of B<SB>r</SB>≥0.8 T, H<SB>cJ</SB>≥600 KA/m, and H<SB>k</SB>/H<SB>cJ</SB>≥0.35, is manufactured from the rapidly-coagulated alloy. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing an iron-based rare earth nanocomposite magnet with improved demagnetization curve squareness.

  In recent years, Ti-containing nanocomposite magnets have been developed and disclosed in Patent Document 1 and the like. On the other hand, so-called “MQ powder (manufactured by Magnequench)” has been sold and used as magnetic powder for isotropic bonded magnets. Patent Document 2 discloses an isotropic magnet having a fine crystal structure.

  As a parameter for evaluating the characteristics of the permanent magnet, the squareness of the demagnetization curve (magnetization curve in the second quadrant of the hysteresis loop) (hereinafter simply referred to as “squareness”) is important for both the residual magnetic flux density and the coercive force. It is. This squareness is determined by the shape of the demagnetization curve shown in FIG. 1, the vertical axis indicates the magnetization J, and the horizontal axis indicates the external magnetic field (reverse magnetic field) H. The demagnetization curve B shown in the figure shows a case where the squareness is excellent, and the demagnetization curve A shows a case where the squareness is relatively inferior.

Conventionally, numerical values such as J _r / J _s and J _r / J _1.2 have been used to evaluate the squareness. J _r is the remanent magnetic polarization and is equal to the remanent magnetic flux density B _r . J _s is the saturation magnetization, and J _1.2 is the magnetization when the external magnetic field H is _1.2 MA / m. J _r / J _s and J _r / J _1.2 are both parameters defined by the magnetization curve in the first quadrant, but in the case of an anisotropic magnet, it can be said that it corresponds to the squareness.

J _r / J _1.2 in a normal isotropic magnet has a value of about 0.5 due to the original properties of the isotropic magnet. This value is smaller than J _r / J _1.2 of the anisotropic magnet and indicates that the squareness is inferior. On the other hand, in the above-mentioned nanocomposite magnet, the value of J _r / J _1.2 is greatly improved to 0.8 to 0.95 although it is an isotropic magnet. The reason why the value of J _r / J _1.2 is improved in such a quenching magnet such as a nanocomposite magnet is that these magnets have a fine crystal structure, and therefore, the remanence enhancement is due to the exchange interaction between crystal grains. This is because an increase in Jr associated with is observed.
JP 2003-178908 A JP-A-10-64710

  As described above, it can be said that the Ti-containing nanocomposite magnet exhibits superior squareness compared to conventional isotropic magnets. However, when the actual squareness is carefully evaluated, it is less than anisotropic magnets. It is enough. If the squareness of the Ti-containing nanocomposite magnet can be further improved, it is expected that the versatility of the magnet will be expanded and further utilized in the fields of motors and electrical equipment.

  The present invention has been made in view of the above circumstances, and a main object thereof is to provide a Ti-containing rare earth nanocomposite magnet having further improved squareness.

Method of manufacturing an iron-based rare earth nanocomposite magnet of the present invention, composition formula _{(Fe 1-n T n)} 100-xyzlm Q x R y Ti z Nb l M m ( where, T is a group consisting of Co and Ni At least one selected element, Q is at least one element selected from the group consisting of B and C, R is at least one element selected from the group consisting of yttrium and rare earth elements, M is Al, At least one element selected from the group consisting of Si, Mn, Cu, Zn, Ga, Ag, Pt, Au, Pb, V, Ta, W, Mo, and Cr), and a composition ratio x, y , Z, l, m and n are respectively 10 ≦ x ≦ 17 atomic%, 6 ≦ y ≦ 11 atomic%, 0.1 ≦ z ≦ 10 atomic%, 0.1 ≦ l ≦ 6 atomic%, and 0 ≦ A molten alloy satisfying m ≦ 6 atomic% and 0 ≦ n ≦ 0.5. A step of meaning, allowed to cool and solidify the melt by melt spinning process, and forming a rapidly solidified alloy, from the rapidly solidified _{alloy, B r ≧ 0.8T, H cJ} ≧ 600KA / m, H An iron-based rare earth nanocomposite magnet having magnetic properties of _k / H _cJ ≧ 0.35 is produced.

  In a preferred embodiment, the step of forming the rapidly solidified alloy includes a step of supplying the molten metal onto a cooling roll through a pipe.

  In a preferred embodiment, the rapidly solidified alloy is a ribbon having an average thickness of 10 μm to 300 μm and a thickness standard deviation σ of 10 μm or less.

  In a preferred embodiment, the method further includes the step of subjecting the rapidly solidified alloy to a heat treatment to increase the volume ratio of the ferromagnetic phase.

  In a preferred embodiment, the ferromagnetic phase contains a hard magnetic phase and a soft magnetic phase, the average crystal grain size of the hard magnetic phase is 10 nm to 300 nm, and the average crystal grain size of the soft magnetic phase is 1 nm to 100 nm. It is.

  In a preferred embodiment, the soft magnetic phase includes an α-Fe phase and an iron-based boride phase.

  In a preferred embodiment, the method includes a step of pulverizing the rapidly solidified alloy to form an iron-based rare earth nanocomposite magnet powder.

  The method for producing a bonded magnet according to the present invention includes a step of preparing the iron-based rare earth nanocomposite magnet powder produced by the above-described production method, and a step of producing a bonded magnet using the iron-based rare earth nanocomposite magnet powder. Is included.

  The effect of simultaneous addition of Ti and Nb and the effect of uniform and rapid cooling by the melt spinning method are combined to produce an iron-based rare earth nanocomposite magnet having a uniform microstructure with improved squareness.

In the present invention, for improving the squareness of the iron-based rare earth nanocomposite magnet, a melt of the alloy having a composition formula of _{(Fe 1-n T n)} 100-xyzlm Q x R y Ti z Nb l M m This melt is cooled and solidified by melt spinning to form a rapidly solidified alloy. Here, T is at least one element selected from the group consisting of Co and Ni, Q is at least one element selected from the group consisting of B and C, and R is selected from the group consisting of yttrium and rare earth elements At least one selected element, M is at least one selected from the group consisting of Al, Si, Mn, Cu, Zn, Ga, Ag, Pt, Au, Pb, V, Ta, W, Mo, and Cr The composition ratios x, y, z, l, m, and n are 10 ≦ x ≦ 17 atomic%, 6 ≦ y ≦ 11 atomic%, 0.1 ≦ z ≦ 10 atomic%, 0.1 ≦ l ≦ 6 atomic%, 0 ≦ m ≦ 6 atomic%, and 0 ≦ n ≦ 0.5 are satisfied.

According to the present invention, an iron-based rare earth nanoparticle having magnetic properties of residual magnetic flux density B _r ≧ 0.8 T, coercive force H _cJ ≧ 600 KA / m, and H _k / H _cJ ≧ 0.35 is _obtained from the rapidly solidified alloy. Composite magnets can be manufactured. Here, “H _k / H _cJ ” is a parameter introduced by the present inventor for correctly evaluating the squareness of the isotropic nanocomposite magnet, and the content thereof will be described below.

First, referring to FIG. 1 again. H _k is the value of the magnetic field H at which the magnetization is equal to 0.9 Jr, and H _cj is the coercive force. In FIG. 1, H _kA is the absolute value of the magnetic field H at which the magnetization is equal to 0.9 Jr in the demagnetization curve A, and H _kB is the absolute value of the magnetic field H at which the magnetization is equal to 0.9 Jr in the demagnetization curve B. It is. As apparent from FIG. 1, the two demagnetization curve A, even if B is not a substantially equal J _r, H _k varies greatly depending on the squareness of the merits. In the example of FIG. 1, H _kB is larger than H _kA , and the relationship of H _kB / H _cj > H _kA / H _cj is established.

In an isotropic nanocomposite magnet, even if J _r / J _s have the same value, H _k / H _cj can take various sizes. For this reason, only improving the J _r / J _s of the nanocomposite magnet can realize only insufficient squareness, and for the first time by increasing H _k / H _cj (for example, 3.5 or more), Isotropic nanocomposites that are superior to the above.

According to the present invention, H _k / H _cj can be increased more than before. The reason why H _k / H _cj can be increased in this way is that Ti and Nb are added as the alloy composition and a rapidly solidified alloy is produced by the melt spinning method.

As described above, in the known Ti-containing nanocomposite magnet, even when the crystal phase is precipitated and grown in the rapidly solidified alloy by reducing the rapid cooling rate of the molten alloy, the effect of adding Ti is Nd ₂ Fe ₁₄ B type. The compound ferromagnetic phase can be formed predominantly. That is, when the rapid quenching rate of the molten alloy is reduced without adding Ti, precipitation and growth of α-Fe occurs preferentially, so that a large amount of α-Fe is present in the solidified alloy immediately after quenching, There was a problem that the final nanocomposite magnet characteristics were degraded. For this reason, before the effect of Ti addition is discovered, the rate of quenching of the molten alloy can be increased, and after producing a substantially completely amorphous rapidly solidified alloy, the heat treatment conditions are controlled, thereby making α-Fe Attempts have been made to curb the growth of.

  In recent years, it has become possible to reduce the cooling rate of molten alloy by adding Ti, so the production of nanocomposite magnets by the “strip casting method”, which is said to be superior to the melt spinning method, has been realized. did. Further, when Nb is added to the raw material alloy in addition to Ti, an amorphous phase is likely to be formed in the rapidly solidified alloy, so that the cooling rate of the molten alloy can be further reduced. The Ti-containing nanocomposite can be produced more stably.

  However, the nanocomposite magnet produced by the conventional method is required to further improve the squareness as described above.

On the other hand, according to the study by the present inventors, it is found that if the thickness σ of the rapidly solidified alloy is suppressed to 10 μm or less (preferably 5 μm or less), the structure of the rapidly solidified alloy is made uniform and the magnetic properties are improved. It was. By producing by the melt spinning method, the standard deviation σ of the thickness of the rapidly solidified alloy can be suppressed to 10 μm or less. However, it has also been found that H _k / H _cj is not sufficiently improved only by controlling the thickness σ of the rapidly solidified alloy to 10 μm or less.

Nb is known to have a high ability to form an amorphous material and to exhibit an effect of suppressing coarsening of crystal grains. For this reason, it has been predicted that the Nd ₂ Fe ₁₄ B type phase cannot be appropriately precipitated by the melt spinning method, and the magnet characteristics are deteriorated. However, when Nb was actually added and quenching was performed by the melt spinning method, a phenomenon that H _k / H _cj was unexpectedly improved was confirmed. Although the detailed mechanism is unknown, it is presumed that the addition of Nb acts on the grain boundary of the nanocomposite structure and has some influence on the exchange interaction between each particle, thereby improving the squareness. .

The iron-based rare earth alloy nanocomposite magnet of the present invention preferably contains iron-based boride or α-Fe having a saturation magnetization equivalent to or higher than the saturation magnetization of the R ₂ Fe ₁₄ B-type compound phase. is doing. This iron-based boride is, for example, Fe ₃ B (saturation magnetization 1.5T) or Fe ₂₃ B ₆ (saturation magnetization 1.6T). Here, the saturation magnetization of R ₂ Fe ₁₄ B is about 1.6 T, and the saturation magnetization of α-Fe is 2.1 T.

  Next, a preferred embodiment of the present invention will be described.

[Liquid quenching device]
In the melt spinning method, molten alloy is sprayed onto the surface of a metal cooling roll that rotates at high speed, whereby the molten alloy is brought into contact with the surface of the cooling roll and rapidly solidified. In order to bring an appropriate amount of molten alloy into contact with the surface of the cooling roll, the molten alloy is injected through an orifice (hole) whose inner diameter is reduced to, for example, about 1 mm.

  The molten alloy supplied from the nozzle orifice to the surface of the cooling roll is cooled by the cooling roll while being blown away from the cooling roll to form a thin ribbon-like rapidly solidified alloy.

  In the present embodiment, for example, the raw material alloy is manufactured using the quenching apparatus shown in FIG. In order to prevent oxidation of the raw material alloy containing rare earth elements R and Fe which are easily oxidized, the alloy manufacturing process is performed in an inert gas atmosphere. As the inert gas, a rare gas such as helium or argon or nitrogen can be used. Note that since nitrogen is relatively easy to react with the rare earth element R, it is preferable to use a rare gas such as helium or argon.

  The apparatus shown in FIG. 2 includes a raw material alloy melting chamber 1 and a quenching chamber 2 that can maintain a vacuum or an inert gas atmosphere and adjust the pressure. FIG. 1A is an overall configuration diagram, and FIG. 2B is a partially enlarged view.

  As shown in FIG. 2 (a), the melting chamber 1 includes a melting furnace 3 that melts a raw material 20 blended so as to have a desired magnet alloy composition at a high temperature, and a hot water storage container having a hot water discharge nozzle 5 at the bottom. 4 and a blended raw material supply device 8 for feeding the blended raw material into the melting furnace 3 while suppressing the entry of air. The hot water storage container 4 has a heating device (not shown) that stores the molten alloy 21 of the raw material alloy and can maintain the temperature of the hot water at a predetermined level. The quenching chamber 2 includes a rotary cooling roll 7 for rapidly cooling and solidifying the molten metal 21 discharged from the hot water nozzle 5.

  In this apparatus, the atmosphere in the melting chamber 1 and the quenching chamber 2 and the pressure thereof are controlled within a predetermined range. Therefore, atmospheric gas supply ports 1b, 2b, and 8b and gas exhaust ports 1a, 2a, and 8a are provided at appropriate locations in the apparatus. In particular, the gas exhaust port 2a is connected to a pump in order to control the absolute pressure in the quenching chamber 2 within a range of 0.1 kPa to normal pressure (atmospheric pressure).

  The melting furnace 3 can be tilted, and the molten metal 21 is appropriately poured into the hot water storage container 4 through the funnel 6. The molten metal 21 is heated in the hot water storage container 4 by a heating device (not shown). The hot water discharge nozzle 5 of the hot water storage container 4 is disposed in the partition wall between the melting chamber 1 and the quenching chamber 2 and causes the molten metal 21 in the hot water storage container 4 to flow down to the surface of the cooling roll 7 positioned below. The orifice diameter of the hot water nozzle 5 is, for example, 0.5 to 2.0 mm. When the viscosity of the molten metal 21 is large, the molten metal 21 is less likely to flow through the hot water nozzle 5, but in this embodiment, the quenching chamber 2 is held at a lower pressure than the melting chamber 1. During this time, a pressure difference is formed, and the molten metal 21 is smoothly discharged.

  The cooling roll 7 preferably has a substrate formed of carbon steel, tungsten, iron, copper, molybdenum, beryllium, or an alloy of the same type. This is because these substrates are excellent in thermal conductivity and durability. The surface of the base material of the cooling roll 7 is preferably plated with chromium, nickel, or a combination thereof. This is because the strength of the roll surface can be increased, and melting and deterioration of the roll surface during the rapid cooling process can be suppressed. The diameter of the cooling roll 7 is, for example, 300 to 500 mm. The water cooling capacity of the water cooling device provided in the cooling roll 7 is calculated and adjusted according to the solidification latent heat per unit time and the amount of hot water.

  According to the apparatus shown in FIG. 2, for example, a total of 10 kg of the raw material alloy can be rapidly solidified in 10 to 20 minutes. The quenched alloy thus formed becomes, for example, an alloy ribbon (alloy ribbon) 22 having a thickness of 10 to 300 μm and a width of 2 to 3 mm.

[Liquid quenching method]
First, the raw material alloy melt 21 expressed by the above-described composition formula is prepared and stored in the hot water storage container 4 of the melting chamber 1 of FIG. Next, the molten metal 21 is discharged from the hot water nozzle 5 onto the water-cooled roll 7 in the reduced-pressure Ar atmosphere, rapidly cooled by contact with the cooling roll 7, and solidified. As the rapid solidification method, it is necessary to use a method capable of controlling the cooling rate with high accuracy. In the case of this embodiment, when the molten metal 21 is cooled and solidified, the cooling rate is preferably 1 × 10 ² to 1 × 10 ⁸ ° C./second, and preferably 1 × 10 ⁴ to 1 × 10 ⁶ ° C./second. Further preferred.

The time during which the molten alloy 21 is cooled by the cooling roll 7 corresponds to the time from when the alloy comes into contact with the outer peripheral surface of the rotating cooling roll 7 until it leaves, during which time the temperature of the alloy decreases and supercooling occurs. Become liquid. Thereafter, the supercooled alloy leaves the cooling roll 7 and flies in an inert atmosphere. While the alloy is in the form of a ribbon, the temperature is further reduced as a result of the heat being taken away by the atmospheric gas. The pressure of the atmospheric gas is preferably set within the range of 0.1 kPa to normal pressure. As a result, when the adhesion between the alloy and the cooling roll is improved, the heat removal effect by the cooling roll is increased, and Nd ₂ is contained in the alloy. It is possible to deposit and grow the Fe ₁₄ B type compound uniformly and finely. More preferably, by setting the pressure of the atmospheric gas within the range of 30 kPa to normal pressure, the secondary cooling effect by the atmospheric gas is enhanced, and the Nd ₂ Fe ₁₄ B type compound in the alloy is precipitated more uniformly and finely. Can be grown. When an appropriate amount of Ti is not added to the raw alloy, α-Fe is preferentially precipitated and grown in the quenched alloy that has undergone the cooling process as described above. Magnet characteristics will deteriorate.

In the present embodiment, fine R ₂ Fe ₁₄ B having an average particle diameter of 80 nm or less is obtained by adjusting the roll surface speed within a range of 7 m / sec or more and 25 m / sec or less and setting the atmospheric gas pressure to 1.3 kPa or more. Quenched alloy containing type compound phase.

[Heat treatment]
In the present embodiment, the heat treatment is performed in an argon atmosphere. Preferably, the heating rate is 5 ° C./second to 20 ° C./second, and the temperature is maintained at 550 ° C. to 850 ° C. for 30 seconds to 20 minutes, and then cooled to room temperature. By this heat treatment, fine crystals of metastable phase are precipitated and grown in the amorphous phase, and a nanocomposite structure is formed. Since the fine Nd ₂ Fe ₁₄ B-type crystal phase is already present at, for example, 5% by volume or more of the whole at the start of the heat treatment, coarsening of the α-Fe phase and other crystal phases is suppressed, and Nd ₂ Fe ₁₄ Each constituent phase (soft magnetic phase) other than the B-type crystal phase is uniformly refined.

When the heat treatment temperature is lower than 550 ° C., a large amount of amorphous phase remains even after the heat treatment, and the coercive force may not reach a sufficient level depending on the rapid cooling conditions. Further, when the heat treatment temperature exceeds 850 ° C., the grain growth of the respective constituent phases is significantly reduced residual magnetic flux density B _r, is deteriorated squareness of the demagnetization curve. For this reason, the heat treatment temperature is preferably 550 ° C. or more and 850 ° C. or less, but the more preferable heat treatment temperature range is 570 ° C. or more and 820 ° C. or less.

In the present invention, depending on the rapid cooling conditions, a sufficient amount of Nd ₂ Fe ₁₄ B type compound phase can be uniformly and finely precipitated in the quenched alloy. In this case, the rapidly solidified alloy itself can exhibit sufficient magnet characteristics without crystallization heat treatment on the quenched alloy. Therefore, the crystallization heat treatment is not an essential step in the present invention, but it is preferable to perform this for improving the magnet characteristics. It should be noted that the magnet characteristics can be sufficiently improved even by heat treatment at a lower temperature than in the past.

  The heat treatment atmosphere is preferably an inert gas atmosphere in order to prevent oxidation of the alloy. The heat treatment may be performed in a vacuum of 0.1 kPa or less.

In the quenched alloy before heat treatment, in addition to the R ₂ Fe ₁₄ B type compound phase and the amorphous phase, the metastable of Fe ₃ B phase, Fe ₂ B phase, Fe ₂₃ B ₆ phase, R ₂ Fe ₂₃ B ₃ phase, etc. A phase may be included. In this case, the R ₂ Fe ₂₃ B ₃ phase disappears by heat treatment, and an iron-based boride (for example, Fe ₂₃ B ₆ ) exhibiting a saturation magnetization equivalent to or higher than the saturation magnetization of the R ₂ Fe ₁₄ B phase. And α-Fe can be grown.

  In the case of the present invention, even if a soft magnetic phase such as α-Fe is finally present, the soft magnetic phase and the hard magnetic phase are magnetically coupled by an exchange interaction, so that excellent magnetic properties are exhibited. Is done.

The average crystal grain size of the R ₂ Fe ₁₄ B-type compound phase after the heat treatment needs to be 300 nm or less, which is a uniaxial crystal grain size, preferably 10 nm or more and 150 nm or less, and 20 nm or more and 100 nm or less. Is more preferable. On the other hand, when the average crystal grain size of the boride phase or α-Fe phase exceeds 100 nm, the exchange interaction acting between the constituent phases is weakened, and the squareness of the demagnetization curve is deteriorated. It will decline. When the average crystal grain size is less than 1 nm, a high coercive force cannot be obtained. From the above, the average crystal grain size of the soft magnetic phase such as boride phase and α-Fe phase is preferably 1 nm or more and 100 nm or less, more preferably 50 nm or less, and further preferably 30 nm or less. preferable.

  Note that the quenched alloy ribbon may be roughly cut or pulverized before the heat treatment. If the obtained magnet is pulverized after heat treatment to produce magnet powder (magnetic powder), various bonded magnets can be produced from the magnetic powder by known processes. When producing a bonded magnet, the iron-based rare earth alloy magnetic powder is mixed with an epoxy resin, a nylon resin, a PPS resin, or the like, and formed into a desired shape. At this time, the nanocomposite magnetic powder may be mixed with other types of magnetic powder, for example, Sm—Fe—N magnetic powder or hard ferrite magnetic powder.

  Various rotary machines, such as a motor and an actuator, can be manufactured using the above-mentioned bond magnet.

  When the magnet powder of the present invention is used for an injection-molded bonded magnet, it is preferably pulverized so that the average particle size is 200 μm or less, and more preferably the average particle size of the powder is 30 μm or more and 150 μm or less. Moreover, when using for a compression-molded bond magnet, it is preferable to grind | pulverize so that a particle size may be 300 micrometers or less, and the average particle diameter of a more preferable powder is 30 micrometers or more and 250 micrometers or less. More preferably, the particle size distribution has two peaks and the average particle size is 50 μm or more and 200 μm or less.

  In addition, by performing a surface treatment such as a coupling treatment or a chemical conversion treatment on the surface of the powder, it is possible to improve the formability at the time of forming the bonded magnet and the corrosion resistance and heat resistance of the obtained bonded magnet regardless of the forming method. Further, when the surface of the bonded magnet after molding is subjected to surface treatment such as resin coating, chemical conversion treatment or plating, the corrosion resistance and heat resistance of the bonded magnet can be improved in the same manner as the powder surface treatment.

[composition]
When the total composition ratio x of B and C is less than 10 atomic%, when the cooling rate at the time of quenching is relatively low, such as about 10 ² ° C / second to 10 ⁵ ° C / second, the R ₂ Fe ₁₄ B type crystal phase It becomes difficult to produce a quenched alloy in which an amorphous phase is mixed, and a high coercive force cannot be obtained even if heat treatment is performed thereafter. For this reason, x needs to be 10 atomic% or more. On the other hand, when the composition ratio x exceeds 17 atomic%, the volume ratio of the amorphous phase remaining after the crystallization heat treatment increases, and at the same time, the abundance ratio of α-Fe having the highest saturation magnetization in the constituent phases decreases. As a result, the residual magnetic flux density _Br decreases. From the above, the composition ratio x is preferably set to be 10 atomic% or more and 17 atomic% or less. A more preferable range of the composition ratio x is more than 10 atomic% and 14.5 atomic% or less. In addition, it is preferable that the ratio of C with respect to the whole of B and C exists in the range of 0 or more and 0.25 or less by atomic ratio.

R is one or more elements selected from the group consisting of yttrium (Y) and rare earth elements. If La or Ce is present, R (typically Nd) in the R ₂ Fe ₁₄ B phase is replaced with La or Ce, and the coercive force and squareness deteriorate, so La and Ce are substantially not included. Is preferred. However, when a very small amount of La or Ce (0.5 atomic% or less) exists as an unavoidable impurity, there is no problem in terms of magnetic characteristics. Therefore, it can be said that La and Ce are not substantially contained when 0.5 or less atomic percent La and Ce are contained.

More specifically, R preferably contains Pr or Nd as an essential element, and part of the essential element may be substituted with Dy and / or Tb. When the R composition ratio y is less than 6 atomic% of the whole, the compound phase having the R ₂ Fe ₁₄ B type crystal structure necessary for the expression of the coercive force is not sufficiently precipitated, and a high coercive force H _cJ can be obtained. become unable. Further, when the composition ratio y of R is 10 atomic% or more, the abundance of iron-based boride having ferromagnetism decreases, and the abundance of the B-rich nonmagnetic layer increases instead. Not formed and magnetization decreases. Therefore, the composition ratio y of the rare earth element R is preferably adjusted to a range of 6 atomic% to 11 atomic%, for example, 6 atomic% to 10 atomic%. A more preferable range of R is 7 atom% or more and 9.5 atom% or less.

The addition of Ti is adapted to exert an effect of precipitating and growing the hard magnetic phase in the rapidly solidified alloy molten earlier than the soft magnetic phases, improved and demagnetization curve of coercive force H _cJ and remanence B _r It contributes to the improvement of the squareness and increases the maximum energy product (BH) _max .

When the Ti composition ratio z is less than 0.1 atomic% of the whole, the effect of adding Ti is not sufficiently exhibited. On the other hand, the mole fraction z of Ti exceeds 10 atomic% of the total, the volume ratio of the amorphous phase that remains after the crystallization heat treatment is increased, tends to lead to reduction of the remanence B _r. From the above, the composition ratio z of Ti is preferably in the range of 0.1 atomic% to 10 atomic%. A more preferable lower limit of the z range is 0.5 atomic%, and a more preferable upper limit of the z range is 8 atomic%. Furthermore, the upper limit of the preferable range of z is 7 atomic%.

  In order to obtain various effects, the metal element M may be added. M is at least one element selected from the group consisting of Al, Si, Mn, Cu, Zn, Ga, Ag, Pt, Au, Pb, V, Ta, W, Mo, and Cr.

Fe and T occupy the residual content of the above elements. T is Co and / or Ni. When the atomic ratio n of T with respect to the total Fe and T is more than 50% can not be obtained more high residual magnetic flux density B _r 0.7 T. For this reason, it is preferable to limit n to the range of 0 atomic% or more and 50 atomic% or less.

  The raw materials containing B, C, Fe, Co, Ti, Nd, Nb and other additive elements having a purity of 99.5% or more were weighed so that the alloy composition of each sample shown in Table 1 below was obtained, and the total amount was 600 g. The raw materials were adjusted. Next, a raw material having a desired alloy composition was put into an alumina crucible and then melted by high-frequency heating in an Ar atmosphere to prepare a molten metal. After the molten metal temperature reached 1500 ° C., the molten metal was cast on a water-cooled copper mold to produce a raw material alloy on a flat plate. Here, Sample No. 1-No. 2 corresponds to an example of the present invention, and sample No. 3-No. 6 corresponds to a comparative example.

  In Table 1, for example, “Nb1” indicates that 1 atomic% of Nb was added. Note that trace amounts of impurities inevitably mixed are not listed in Table 1.

  The raw material alloy was melted and rapidly cooled using a liquid quenching device (melt spinning device, strip casting device) to produce a rapidly solidified alloy. Specifically, a raw material alloy having a total amount of 10 g was put into a quartz crucible of a liquid quenching apparatus and melted by high-frequency heating in an Ar atmosphere at a pressure of 1.33 to 47.92 kPa, thereby producing a molten alloy. In the melt spinning apparatus, an orifice having an inner diameter of 0.8 mm is provided at the bottom of the crucible, and when the molten alloy surface is pressurized, the molten alloy is ejected downward through the orifice. The surface of the pure copper cooling roll that rotates at a controlled speed is located below the lower end of the orifice at a predetermined interval, so the molten alloy ejected from the orifice is the surface of the cooling roll that rotates at high speed. , The heat is removed by the cooling roll while moving in the direction of the rotational peripheral speed, and rapidly cooled. On the other hand, in the case of a strip casting apparatus, the molten alloy is supplied onto the inclined tundish from the quartz crucible, so that the molten alloy flows onto the surface of the cooling roll after flowing over the tundish.

  The alloy melt rapidly cooled by the cooling roll is further cooled while being moved away from the surface of the cooling roll in the direction of the rotational peripheral speed, and finally the temperature is lowered to the room temperature level.

  In this example and comparative example, after adjusting the molten metal temperature to 1350 ° C., the molten metal surface in the quartz crucible was pressurized with Ar gas to produce a rapidly solidified alloy having a width of 2 mm to 3 mm and a thickness of 20 μm to 50 μm. Sample No. About 1-2, 4-6, the rapid cooling conditions were prepared with the melt spinning apparatus so that the standard deviation (sigma) of thickness might be 10 micrometers or less. In contrast, sample no. For No. 3, the quenching condition was adjusted by a strip casting apparatus so that the standard deviation σ of the thickness exceeded 10 μm.

  The rapidly solidified alloy produced by the above method was held at a temperature of 600 to 800 ° C. for 6 to 8 minutes, and then cooled to room temperature. The above heat treatment was performed in an Ar atmosphere. Next, a sample having a width of 2 mm to 3 mm, a thickness of 50 μm to 70 μm, and a length of 3 mm to 5 mm was produced from the thin ribbon cooled to room temperature. Thereafter, the magnetic properties of each sample were measured using a VSM (vibrating magnetometer). The measurement results are shown in Table 2.

As can be seen from Table 2, Sample No. containing Nb and having a σ of 5 μm or less. In 1 and 2, the squareness is very excellent, and the value of H _k / H _cJ reaches 0.359. On the other hand, Sample No. containing Nb but with σ exceeding 10 μm. 3 and Sample No. containing no additive element such as Nb. 4, the value of H _k / H _cJ was less than 0.35.

In addition, sample No. 1 in which Mo or W was added instead of Nb and the quenching conditions were adjusted so that σ was 10 μm or less. In 5 and 6, the value of H _k / H _cJ was less than 0.3.

  Since the iron-based rare earth nanocomposite of the present invention exhibits excellent squareness, it has wide versatility and can be used in the fields of motors and electrical equipment.

It is a graph for demonstrating the squareness of a demagnetization curve. (A) is sectional drawing which shows the example of whole structure of the apparatus used for the method of manufacturing the quenching alloy for the iron-based rare earth alloy nanocomposite magnet by this invention, (b) is an expansion of the part by which rapid solidification is performed FIG.

Explanation of symbols

1b, 2b, 8b, and 9b Atmospheric gas supply ports 1a, 2a, 8a, and 9a gas exhaust ports 1 Melting chamber 2 Quenching chamber 3 Melting furnace 4 Hot water storage vessel 5 Hot water discharge nozzle 6 Funnel 7 Rotating cooling roll 21 Molten metal 22 alloy ribbon

Claims (7)

Composition formula _{(Fe 1-n T n)} 100-xyzlm Q x R y Ti z Nb l M m ( where, T is at least one element selected from the group consisting of Co and Ni, Q is B and C At least one element selected from the group consisting of: R is at least one element selected from the group consisting of yttrium and rare earth elements; M is Al, Si, Mn, Cu, Zn, Ga, Ag, Pt And at least one element selected from the group consisting of Au, Pb, V, Ta, W, Mo, and Cr), and the composition ratios x, y, z, l, m, and n are respectively
10 ≦ x ≦ 17 atomic%,
6 ≦ y ≦ 11 atomic%,
0.1 ≦ z ≦ 10 atomic%,
0.1 ≦ l ≦ 6 atomic%, and 0 ≦ m ≦ 6 atomic%
0 ≦ n ≦ 0.5
Preparing a molten alloy that satisfies
A step of cooling and solidifying the molten metal by a melt spinning method to form a rapidly solidified alloy;
Including
An iron-based rare earth nanocomposite magnet having magnetic properties of residual magnetic flux density B _r ≧ 0.8 T, coercive force H _cJ ≧ 600 KA / m, H _k / H _cJ ≧ 0.35 is manufactured from the rapidly solidified alloy. Manufacturing method of base rare earth nanocomposite magnet.   2. The manufacturing method according to claim 1, wherein the rapidly solidified alloy is a ribbon having an average thickness of 10 μm to 300 μm and a thickness standard deviation σ of 10 μm or less.   The manufacturing method according to claim 1, further comprising a step of subjecting the rapidly solidified alloy to a heat treatment to increase a volume ratio of the ferromagnetic phase. The ferromagnetic phase contains a hard magnetic phase and a soft magnetic phase,
The average crystal grain size of the hard magnetic phase is 10 nm or more and 300 nm or less,
The production method according to claim 2, wherein an average crystal grain size of the soft magnetic phase is 1 nm or more and 100 nm or less.   The manufacturing method according to claim 4, wherein the soft magnetic phase includes an α-Fe phase and an iron-based boride phase.   The manufacturing method according to claim 1, comprising a step of pulverizing the rapidly solidified alloy to form an iron-based rare earth nanocomposite magnet powder. Preparing the iron-based rare earth nanocomposite magnet powder produced by the production method according to claim 6;
Producing a bonded magnet using the iron-based rare earth nanocomposite magnet powder;
A method of manufacturing a bonded magnet including

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