JP2727506B2 - Permanent magnet and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a high-performance magnet used for various electric devices, etc.
Particularly, the present invention relates to an alloy-based quenched magnet containing a rare-earth element and a method for manufacturing the same, wherein a Fe-RB-based (R is a rare-earth element including Y, the same applies hereinafter) and Fe-Co-RB-based alloy melts are rapidly solidified. Thus, a magnet having excellent magnet properties is obtained, and the magnet after rapid solidification is annealed under specific conditions to obtain a uniform and stable magnet performance. In the present specification, R is at least one of rare earth elements including Y, and R 'is at least one of rare earth elements including Y, except for Ce and La, as described in the claims. Is shown. [Prior art] As a rare earth magnet with high performance, 32MGOe is mass-produced as an energy product with a powder metallurgy Sm-Co magnet, but Sm, Co has the disadvantage that the raw material price is high . Among the rare earth elements, rare earth elements having a small atomic weight, such as cerium, praseodymium, and neodymium, are more abundant and cheaper than samarium. Fe is inexpensive. In recent years, Nd-Fe-B magnets have been developed.
Japanese Patent No. 46008 describes a sintered magnet, and Japanese Patent Application Laid-Open No. 60-9852 describes a method using a rapid quenching method. In the magnet by the sintering method, although the conventional Sm-Co powder metallurgy process can be applied, it is difficult to handle because it has a step of pulverizing the easily oxidizable Nd-Fe alloy ingot to about 2 to 10 μm. In addition, the powder metallurgy process has many steps (melting → casting → ingot coarse pulverization → fine pulverization → press → sintering → magnet), so that the characteristic of using inexpensive raw materials cannot be used. On the other hand, the magnet using the rapid quenching method has the advantage that the process is simplified (melting → high speed quenching → coarse pulverization → cold press (warm press) → magnet) and that a fine powdering process is not required. However, in order to make the magnet by the rapid quenching method an industrial material, it has been desired to further increase the coercive force, increase the energy product, reduce the cost, and improve the magnetization characteristics. Among various properties of rare earth-iron-boron permanent magnets, the coercive force is sensitive to temperature, and the temperature coefficient of the coercive force (iHc) of the rare earth cobalt permanent magnet is 0.15% / ° C., whereas the rare earth-iron -There is a problem that the temperature coefficient of the coercive force (iHc) of the boron permanent magnet material is 0.6 to 0.7% / ° C., which is four times higher. Therefore, the rare-earth-iron-boron permanent magnet material has a high risk of demagnetization as the temperature rises, which has necessitated a limited design on a magnetic circuit. Furthermore, for example, it cannot be used as a permanent magnet for parts in an engine room of an automobile used in the tropics. Rare earth-iron-
It has been known that a boron permanent magnet material has a practical problem where the temperature coefficient of coercive force is large, and the appearance of a magnet having a large absolute value of coercive force has been desired (Nikkei New Materials, 1986). , 4-28 (No. 9) p. 80). Japanese Patent Application Laid-Open No. 60-9852 proposes that an RB-Fe alloy be provided with a high coercive force iHc and an energy product by a liquid quenching method.
The composition of the publication is that the rare earth element R (Nd, Pr) = 10% or more,
B = 0.5 to 10%, with the balance being Fe is described in the claims. Conventionally, the excellent magnetic properties of the RB-Fe alloy have been described as being due to the Nd ₂ Fe ₁₄ B phase compound,
Therefore, many proposals for improving magnet characteristics (Japanese Patent Application Laid-Open
59-89401, 57-141901) are based on experiments with alloys near the composition corresponding to this compound, that is, alloys in the range of R = 12 to 17% and B = 5 to 8%. Rare earth elements are expensive, so it is desirable to reduce the content,
When the content of the rare earth element is less than 12%, there is a problem that the coercive force iHc is rapidly deteriorated. Japanese Patent Application Laid-Open No. 60-9852 shows that when R = 10%, the iHc becomes 6 kOe or less. . That is, when the content of the rare earth element in the RB-Fe-based alloy is less than 12%, the coercive force iHc is deteriorated. However, in such a composition range, the coercive force iHc is prevented from being deteriorated. The method of designing the composition and the structure of the material has not been known. In the sintering method and the rapid quenching method, basically Nd ₂ Fe ₁₄ B
Although a compound is used, Applied Physics Vol. 55, No. 2 (198
6) As shown on page 121, the magnets are completely different types of magnets from the viewpoint of the alloy structure and the coercive force generation mechanism as well as the mere difference in manufacturing method. In other words, the sintered magnet has a crystal grain size of about 10 μm, and speaking of conventional Sm-Co magnets, it is a nucleation type such as the SmCo ₅ type magnet, in which nucleation of the reverse domain determines the coercive force. The quenched magnet is a pinning type magnet such as a Sm ₂ CO ₁₇ type magnet in which pinning of a domain wall determines a coercive force by an extremely fine structure in which an amorphous phase surrounds fine particles of 0.01 to 1 μm. Therefore, it was necessary to consider the approach to both magnets for improving the characteristics in consideration of the fact that the coercive force generating mechanisms are sufficiently different. [Means for Solving the Problems] The present invention focuses on a rapid quenching method capable of relatively easily producing a non-equilibrium phase as well as an equilibrium phase. As a result of considering adding an element, T
By adding i, V, and Cr, it is possible to provide a high-performance magnet suitable for practical use, showing high HcJ and high energy product even if isotropic in the composition region where the R content is less than 10 atomic%. Is found. The present invention can be obtained by a rapid quenching method and cannot be realized by a sintering method. Further, the present invention provides a magnet alloy having good magnetization characteristics and corrosion resistance by rapid quenching using an additive element such as Ti, V, Cr and the like. The present invention also provides a method for more stably obtaining the performance of the magnet. That is, the present invention, except _{{R 'a (Ce b La} 1-b) 1-a} x (Fe 1-z Co z) 100-xyw B y M w ( where, R' is Ce, the La, At least one rare earth element including Y, 5.5
≦ x <10, 2 ≦ y <15, 0 ≦ z ≦ 0.7, 0 <w ≦ 10, 0.8
0 ≦ a ≦ 1.00, 0 ≦ b ≦ 1, M is at least one of Ti, V and Cr
Seeds) and a permanent magnet comprising a microcrystalline phase or a mixed phase of microcrystalline and amorphous phases. The magnet of the present invention comprises Fe-RB and Fe-C having the above-described composition.
It is obtained by solidifying a molten alloy of o-RB at a high speed by a so-called liquid quenching method. The liquid quenching method is a method of injecting a molten metal from a nozzle onto a surface of a metal rotating body cooled by water cooling or the like, rapidly solidifying the molten metal at a high speed, and obtaining a ribbon-shaped material. (Single roll method), twin roll method, etc., and in the case of the present invention, the single roll method, that is, the method of injecting the molten metal onto the peripheral surface of one rotating roll is most suitable. When the magnet of the present invention is obtained by the one-roll method, the peripheral speed of the water-cooled rotating roll is desirably in the range of 2 m / sec to 100 m / sec.
The reason is that when the roll peripheral speed is less than 2m / sec and 10
This is because the coercive force iHc decreases in any case where the speed exceeds 0 m / sec. In order to obtain a high coercive force and a high energy product, the roll peripheral speed is desirably 5 to 40 m / sec. By rapidly solidifying the molten alloy having the above composition at a roll peripheral speed of 2 to 100 m / sec by the single roll method, the coercive force iHc is increased to about 20,000 Oe and the magnetization σ is 65 to 150 emu / sec.
gr magnet is obtained. Thus, if the molten metal is rapidly quenched and solidified, an amorphous or extremely fine crystalline structure can be obtained, and as a result, a magnet having excellent magnet properties as described above can be obtained. The structure after quenching differs depending on the quenching conditions, but consists of amorphous or microcrystalline or a mixed structure thereof.The structure and size of the microcrystalline or amorphous and microcrystalline can be further controlled by annealing, and higher high characteristics can be obtained. Can be As a microcrystalline phase, when at least 50% or more has a size in the range of 0.01 to less than 3 μm, preferably 0.01 to less than 1 μm, high characteristics can be obtained. High characteristics are obtained when the material is composed of a structure not containing an amorphous phase. A magnet quenched and solidified by the liquid quenching method in an inert atmosphere or vacuum at a temperature range of 300 to 900 ° C.
Anneal for 0.001 to 50 hours. By performing such annealing heat treatment, the quenched magnet of the component targeted in the present invention becomes less sensitive to various characteristics depending on the quenching condition, and easily obtains stable characteristics. Here, if the annealing temperature is lower than 300 ° C., the effect of the annealing is not obtained, and if it exceeds 900 ° C., the coercive force iHc sharply decreases. If the annealing time is less than 0.001 hour, the effect of annealing is not obtained, and if it exceeds 50 hours, the characteristics are not further improved, and it is only economically disadvantageous. Therefore, the annealing conditions are specified as described above. In addition, during the annealing, the magnetic properties can be improved by performing the treatment in a magnetic field. The Cr-added Fe-based alloy has a region where γ-Fe exists at a lower temperature than that of the Ti- and V-added systems, and heat treatment for obtaining high characteristics requires precise temperature control in the heat treatment furnace. The obtained ribbon-shaped magnet is preferably used.
A high-density bulk magnet can be formed by pulverizing to a particle size of 30 to 500 μm and performing cold pressing or warm pressing. Further, the permanent magnet according to the present invention, in addition to the liquid quenching method, powder bonding method, that is, after further annealing and pulverizing the ribbon or powder obtained by the liquid quenching method, if necessary,
Bonded magnets can be formed by bonding with resin or the like. A ribbon-shaped magnet obtained by a conventional high-speed quenching method, or a magnet and a bonded magnet obtained by pulverizing the ribbon-shaped magnet and the bonded magnet are known as disclosed in JP-A-59-211549. However, the conventional magnet is JAP60 (10), vol 15
(1986) As shown on page 3865, a magnetizing magnetic field of 40 kOe or more and 110 kOe is required to magnetize to the saturation magnetization, and a magnet which can be saturated with 15 to 20 kOe, which is an ordinary electromagnet, is desired. Was rare. The magnet alloy containing Ti, V, etc. in the present invention has an advantage that it can be sufficiently magnetized at 15 to 20 kOe as shown in FIG. 1, so that the properties after magnetization at 15 to 20 kOe are very large. Be improved. In the figure, Fe-13.5Nb-5B is an example of the conventional magnet, Fe-9.5
Nd-8B-4Ti is an example of the magnet of the present invention, and the horizontal axis is the magnetizing magnetic field (kO
e), the vertical axis is the ratio of the residual magnetization to the magnetization field of Br (40k) -40 kOe with respect to Br (Hex) -the residual magnetization at a certain magnetization field. Next, the reason for limiting the components in the present invention will be described. When the value x of the rare earth element is less than 5.5, the coercive force iHc tends to decrease, and when the value x exceeds 20, the magnetization value decreases. If the total addition of Ce and La exceeds 20%, the maximum energy product decreases.
a ≦ 1.00. Sm metal also reduces the anisotropy constant, so it is better to keep it at 20% or less of x. When the value y of B is less than 2, the coercive force iHc is small, and when it is 15 or more, Br decreases. The magnetic performance is improved by replacing Fe with Co, and the Curie temperature is also improved. However, when the substitution amount z exceeds 0.7, the coercive force decreases. If the amount w of at least one M element of Ti, V, and Cr exceeds 10, a rapid decrease in magnetization will occur. In order to increase iHc, w is preferably 0.1 or more, and in order to increase corrosion resistance, 0.5 or more, more preferably 1 or more is good. M
When two or more elements are added in combination, the effect of improving the coercive force iHc is greater than in the case of single addition. Note that the upper limit of the amount added in the case of composite addition is 10%. Substituting 50% or less of B with Si, C, Ga, Al, P, N, Ce, S, etc. has the same effect as B alone. y is in the range of less than 2 to 15, z is in the range of 0 to 0.7, w is 0
Must be within the range of ~ 10. In addition, as a preferable region for obtaining a high coercive force, x is preferably 12 to 20, more preferably 12 to 15, y is less than 2 to 15, more preferably 4 to 12, still more preferably 4 to 10, and z is more preferably 0 to 0.7. Is 0
0.6 and w are in the range of 0.1 to 10, more preferably 2 to 10. In addition, a preferable region for obtaining a high energy product in an isotropic manner is that x is less than 12, more preferably less than 10, y is less than 2 to 15, more preferably 4 to 12, and even more preferably 4 to 10, z is 0 to 0.7 is more preferable, 0 to 0.6, and w is in the range of not including 0 to 10 and more preferably 2 to 10. Also, a preferable region for obtaining a high energy product with good isotropic and magnetizing characteristics is that x is less than 6 to 10, y is less than 2 to 15, more preferably 4 to 12, still more preferably 4 to 10, and z is 0 to 0.7, more preferably 0 to 0.6, w does not include 0 to 10
More preferably, it is in the range of 2 to 10. In order to obtain a high energy product under anisotropic conditions, x is preferably 6 to 12, more preferably 6 to less than 10, y is less than 2 to 15, more preferably 4 to 12, still more preferably 4 to 10, and z is 0 to 10.
The value of w is preferably in the range of 0 to 0.6, more preferably 0 to 0.6, and excluding 0, more preferably 2 to 10. [Action] FIG. 2 shows the action of M addition. The figure shows the coercive force iHc of the ribbon ribbon obtained by the method shown in Example 1 and the maximum energy product (BH) _max obtained by the hot pressing method shown in Example 2. Further, as the composition, A: R-8B-remainder iron (comparative example) and B: R-8B- (3-6) Ti-remainder iron (the present invention), wherein R is an example of Nd. As can be seen from the figure, the addition of M contributes particularly to a high coercive force at about 10 atomic% Nd or more, and improves the maximum energy product (BH) _max especially at about 10 atomic% Nd or less at less than about 10 atomic% Nd where cost reduction is possible. You can see the contribution. M also has a large contribution to improving the coercive force. This tendency is almost the same when other additive elements are used. The cause of the high coercive force as described above is that the R content is
When the content is less than 10 atomic%, the element M is dissolved in supersaturation by a rapid quenching method instead of a coercive force mechanism using a stable tetragonal R ₂ Fe ₁₄ B compound as seen in a conventional R-Fe-B magnet. This is caused by the microstructure having the metastable R ₂ Fe ₁₄ B phase as the main phase. Therefore, the additive element M stabilizes the R ₂ Fe ₁₄ B phase even at a low R composition, but this effect can be obtained only in the rapid quenching method, and there is no such effect in the sintered magnet. If expressed as R _x M _w B _y (Fe, Co) 1- _xyw , 2 ≦ w ≦
The effect of the above effect is large when 10, 5.5 ≦ x <10, preferably 6 ≦ x <10, 4 ≦ y ≦ 12, preferably 4 ≦ y ≦ 10.
Further, it is considered that the additive element M has a function of generating and strengthening a sub-phase acting as a boundary phase for the pinning site. In addition, α-Fe and other phases can also be present as some sub-phases. And the Example _{1 Nd x (Fe 1 zCo z} ) 100-xyzw B y M w becomes alloy having a composition prepared by arc melting. The obtained alloy was thinned using a molten metal quenching method. The molten alloy was injected and cooled at a gas pressure of argon through a quartz nozzle on the surface of a roll rotating at 10 to 80 m / sec to obtain a ribbon made of amorphous or microcrystalline. This ribbon was subjected to aging treatment in an argon gas atmosphere in a temperature range of 550 to 900 ° C. The best magnetic properties obtained are
It is shown in the table. From Table 1, it can be seen that a magnet having high iHc and (BH) _max can be obtained by adding M. Table 1 shows that the addition of one or more of Ti, V, and Cr can provide higher properties than the alloy without addition. Further, when the sample of the present invention and the sample of the comparative example (No. 12 to 15) were left in an atmosphere of 40 ° C. and 90% humidity for 100 hours, rust of 0.1 to 1 mm was generated in the sample of the comparative example. However, not much was observed in the sample of the present invention. This indicates that the sample of the present invention has good corrosion resistance. Example 2 An alloy having the composition shown in Table 2 was produced in the same manner as in Example 1. Using a vibrating magnetometer, the sample was first subjected to magnetization measurement at 18 kOe, and then compared with those measured after pulse magnetization at 40 kOe. The value is shown as Br _18K / Br _40k (%). The values in the table are the values of the sample subjected to pulse magnetization at 40 kOe. Table 2 shows that this alloy is easy to magnetize. Example 3 A ribbon having a composition shown in Table 3 below was applied to a thickness of about 100 μm.
m, press-mixing with thermosetting resin, density about 6g
/ cc bond magnet was obtained. Table 3 shows the measurement results obtained by applying a pulse magnetization of 40 kOe. The magnets of Nos. 1 to 5 of the present invention had good magnetization at 97 kOe, which was 97% or more as compared with the pulse magnetization at 40 kOe. Further N
o The temperature coefficients of iHc and Br for the samples of
When measured over 100 ° C, And a good value. The magnetization at 18 kOe of the sample No. 7 of the comparative example was 92%. Further, the temperature characteristics (20 to 110 ° C) of Br and iHc of the comparative example were examined. Met. Example 4 Raw materials were blended so as to obtain an alloy having a composition as shown in Table 4, and these materials were melted by high-frequency heating, and copper rotating at a peripheral speed of 40 m / sec in an argon atmosphere was used. Molten metal is ejected from the quartz nozzle onto the roll, and the thickness is about 20μ.
m, a ribbon having a width of 5 mm was obtained. Then the ribbon is 50 ~ 200μm
It was pulverized to particles having a particle size of the order. Using the obtained powder,
The first hot pressing process was performed at about 780 ° C, 1,000 kg / cm ² for 15 minutes in an argon atmosphere.
It was formed into a compact of 30φ × 30 mm. Next, the molded product is 78 so that the final product shape has an outer diameter of 50 mm, an inner diameter of 44 mm, and an arc angle of 60 °.
Extruded at 0 ° C. Extrusion ratio is 8 and extrusion pressure is 8ton /
It was cm ^2. Thereafter, the obtained extruded product was cut into a length of 10 mm. The extrudate obtained showed anisotropy in the radial direction. The magnet properties were as shown in Table 4. [Effects of the Invention] As is clear from the above description, and particularly from the examples, by adding the M element according to the present invention, the magnet is compared with a magnet without the M element added, which has almost the same R, Fe, and B contents. Thus, a coercive force iHc of 1.5 times or more is achieved, depending on the amount of addition. Therefore, despite the disadvantage that the temperature characteristics of the coercive force iHc of the RB-Fe alloy magnet are not excellent, a sufficiently high improvement of the coercive force iHc is achieved to compensate for such a defect, and a practical permanent magnet is provided. Was done. Further, it is characterized in that the magnet has extremely excellent magnetizing characteristics. Further, it should be noted that even when the content of the rare earth element R is less than 10%, magnet characteristics comparable to the case where the content of the rare earth element R is 10% or more can be obtained. Therefore, according to the present invention, a magnet having a low cost and a high coercive force and high energy product is provided, and the present invention is significant in this field.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing the magnetization characteristics, and FIG. 2 is a graph explaining the effects of the rare earth element content and Ti on the magnet characteristics.

   ────────────────────────────────────────────────── ─── Continuation of front page    (31) Priority claim number Japanese Patent Application No. 62-23509 (32) Priority date February 5, 1987 (33) Priority claim country Japan (JP)        Referee number Hei 23-23656 (72) Inventor Tetsuto Yoneyama               1-13-1 Nihonbashi, Chuo-ku, Tokyo               IDK Corporation                (56) References JP-A-60-9852 (JP, A)                 JP-A-61-174364 (JP, A)                 JP-A-60-254708 (JP, A)

Claims (1)

(57) [Claims] _{{R 'a (Ce b La} 1-b) 1-a} x (Fe 1-z Co z) 100-xyw B y M w ( where, R' is Ce, except for La, rare earth elements including Y At least one of 5.5 ≦
x <10, 2 ≦ y <15, 0 ≦ z ≦ 0.7, 0 <w ≦ 10, 0.80
≦ a ≦ 1.00, 0 ≦ b ≦ 1, M is at least 1 of Ti, V, Cr
Seed) and a permanent magnet comprising a microcrystalline phase or a mixed phase of microcrystalline and amorphous phases. 2. 2. The permanent magnet according to claim 1, which is in the form of a ribbon. 3. 3. The permanent magnet according to claim 1 or 2 manufactured by rapid quenching and subsequent annealing. 4. 2. The permanent magnet according to claim 1, wherein the powder having the composition and the structure is compacted. 5. 2. The permanent magnet according to claim 1, wherein the ribbon having the composition and the structure is pulverized after being pulverized. 6. The permanent magnet according to any one of claims 1 to 5, wherein the permanent magnet can be magnetized by 95% or more in a low magnetic field of about 20 kOe. 7. 7. The permanent magnet according to claim 1, wherein x satisfies 6 ≦ x <10. 8. 8. The permanent magnet according to claim 1, wherein y satisfies 4 ≦ y ≦ 12 and w satisfies 2 ≦ w ≦ 10. 9. The permanent magnet according to any one of claims 1 to 8, wherein the coercive force (iHc) is 7 kOe or more. 10. 8. The permanent magnet according to claim 7, which is a magnet other than a bonded magnet, and has a maximum energy product (BH) max of more than 8 MGOe. 11. _{{R 'a (Ce b La} 1-b) 1-a} x (Fe 1-z Co z) 100-xyw B y M w ( where, R' is Ce, except for La, rare earth elements including Y At least one of 5.5 ≦
x <10, 2 ≦ y <15, 0 ≦ z ≦ 0.7, 0 <w ≦ 10, 0.80
≦ a ≦ 1.00, 0 ≦ b ≦ 1, M is at least 1 of Ti, V, Cr
Seed) and a bonded magnet made of a powder comprising a microcrystalline phase or a mixed phase of a microcrystal and an amorphous phase. 12. _{{R 'a (Ce b La} 1-b) 1-a} x (Fe 1-z Co z) 100-xyw B y M w ( where, R' is Ce, except for La, rare earth elements including Y At least one of 5.5 ≦
x <10, 2 ≦ y <15, 0 ≦ z ≦ 0.7, 0 <w ≦ 10, 0.80
≦ a ≦ 1.00, 0 ≦ b ≦ 1, M is at least 1 of Ti, V, Cr
A method for producing a permanent magnet, in which a molten alloy of the above type is rapidly quenched and then annealed in a temperature range of 300 to 900 ° C.