JPH04120253A - Permanent magnet alloy and bond magnet using same - Google Patents

Abstract

PURPOSE:To obtain a permanent magnet alloy having high residual magnetic flux density by providing a thin slab prepared by subjecting a molten metal consisting of specific percentages of rare earth metal, transition metal, B, and V to direct rapid cooling, specifying the total content of Nd and Pr in the above rare earth metal, and using an Fe-base alloy containing specific amounts of Co as the above transition metal. CONSTITUTION:A molten metal having a composition which contains rare earth metal (R), transition metal (T), B, and V in the proportion, by atom. of X% R-(100-X-Y-Z)%T-Y%B-Z%V (where 5<=X<9, 3<=Y<15, 0.5<=Z<5) and in which the above rare earth metal (R) is composed of lanthanoide series elements including >=50%, in total, of Nd and/or Pr and also the above transition metal (T) is composed of an Fe-base alloy containing 5-<30% Co is directly subjected to rapid cooling so as to be formed into thin slab or powder. By this method, the permanent magnet alloy in which residual magnetic flux density Br and maximum magnetic energy product BHmax are regulated to about 10-12KG and about 18-22MGOe can be obtained. This alloy is useful for bond magnet.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to improvements in rare earth metal/iron/boron alloys for permanent magnets, and to bonded magnets made by solidifying powder of the alloys with resin.

(Prior Art) Permanent magnets based on rare earth metals, iron, and boron, which have been developed in recent years, have superior magnetic properties compared to conventional rare earth cobalt magnets, so their range of use is expanding. On the other hand, bonded magnets made by hardening rare earth metal/iron/boron alloy powder with resin are generally divided into compression molded magnets using thermosetting resin and injection molded magnets using thermoplastic resin.
In recent years, the market for use in motors and other applications has been expanding due to Heneru Hs-Yoshi T's flexible design, excellent precision in dimensioning, and ability to be molded in composites with other parts. .

By the way, the above-mentioned bonded magnets contain a non-magnetic material (resin) of about 10-10% to about 40% by volume, so they have the disadvantage of inevitably deteriorating their magnetic properties by a considerable amount compared to sintered magnets. had.

- As an example, the residual magnetic flux density of a sintered magnet is Br12KG.

The maximum magnetic energy product BHmax is 30MGOe, which is about 6 KG and 10MGOe, respectively. This drawback in the magnetic properties of bonded magnets can naturally be improved by reducing the amount of resin blended, but in this case, problems with magnet strength and mass production will occur, and the advantages of bonded magnets will be lost. will be exposed.

Therefore, various studies have recently been carried out on the composition of alloys used as raw materials for bonded magnets.
In Publication No. 662, an element containing at least 50 atomic % neodymium (Nd) is selected as a rare earth element, and this is combined with iron (Fe), cobalt (Co), and boron (B).
, an alloy S in combination with Nadium (V) is disclosed.

(Problem to be solved by the invention) However, according to the new alloy disclosed in the above publication, the effect of improving magnetic properties is insufficient, and it is insufficient to improve the magnetic properties of bonded magnets. There was a problem that could not be fundamentally solved, and the viewpoints of designing motors, which are applied products, often focused on the magnitude of the residual magnetic flux density Br rather than the maximum magnetic energy product BHmax. 5. In the aforementioned alloy, the residual magnetic flux density Br was as small as 10 KG or less, and the range of its application was also limited.

Therefore, an object of the present invention is to provide an alloy for permanent magnets having a high residual magnetic flux density, and a bonded magnet using this alloy which can be used in a wide range of applications.

(Means for Solving the Problems) In the present invention, an alloy for permanent magnets having excellent magnetic properties was realized by the following technical means.

That is, the rare earth metal (R), transition metal (T), B,
%B-Z%V (5≦X<9゜3≦Y<15.0
．． The rare earth metal (R) is contained in a proportion of 5≦Z<5).
is composed of a lanthanide element containing 50% or more of one or both of Nd and Pr, and the transition metal (T) is CO
It is characterized in that it is made of an Fe-based alloy containing 5% or more and less than 30% of molten metal, and is formed into flakes or powder by directly quenching the molten metal.

In the present invention, neodymium (N
d) and praseodymium (Pr) were chosen because N
This is because the theoretical values of anisotropy energy and saturation magnetization of both the d1Fe+J and PrJe+J compounds are larger than those of similar compounds using other rare earth elements, and excellent magnetic properties have been experimentally confirmed. This is also because these two elements are abundant in terms of resources and have high utility value. However, when the rare earth metal (R) content is less than 5 at%, the coercive force not only decreases due to the increase in the soft magnetic phase mainly composed of Fe, but also the magnetic energy decreases, while when the rare earth metal (R) content exceeds 9 at%, the residual magnetic flux density decreases. Since this decreases and makes it difficult to obtain the desired magnetic energy, in the present invention, the rare earth metal content X is set to 5≦X.
<9. In the present invention, rare earth metals include Ce and La to reduce alloy cost, or D y , G d , and T b to improve and adjust magnetic properties.
, Ho, Sm, and other rare earth elements. However, in order to obtain good magnetic properties, it is necessary that Nd and Pr, alone or in total, be 50 atomic % or more.

Regarding transition metals (T), mainly Fe is used, and cobalt CO, which is known as a substitution element, is added to improve the temperature characteristics by increasing the Curie temperature, and Fe is estimated from the Slater-Pauling curve. The objective was to improve the saturation magnetization by solid solution of CO. The CO substitution rate was set in the range of 5 at.% or more and less than 30 at.% because at less than 5 at.%, the Curie temperature does not improve significantly, and at 30 at.% or more, the coercive force decreases rapidly. Depends on the reason why it is no longer possible to obtain.

Regarding B, if its content is less than 3 at%, R, T,
The 4B compound phase becomes unstable, leading to a sudden drop in magnetic properties.On the other hand, if it exceeds 15 atomic %, the magnetic energy decreases significantly due to an increase in the non-magnetic phase. <15.

Regarding (2), various transition metal elements Ti, Cr, W, and Hf are used to suppress the decrease in coercive force.

As a result of investigating the effects of adding Zr, Mo, Nb, Ta, etc. to alloys, this was found to be the most effective. However, when the content of the lever (■) is less than 0.5 at%, the coercive force decreases due to the appearance of a soft magnetic phase mainly composed of Fe, while when it exceeds 5 at%, the residual magnetic flux density decreases due to an increase in the non-magnetic phase. (Therefore, in the present invention, this content 2 is set to 0.5≦Z<5
And so. Note that this (2) has a function of suppressing the appearance of a soft magnetic phase, especially in a case where the rare earth metal composition is low.

The alloy of the present invention can be manufactured by conventionally known methods. The most common manufacturing method is the melt spin method used by General Motors, in which a high-frequency melted alloy with a predetermined composition is spun at tens of meters per second through a quartz nozzle using the pressure of a gas such as argon. The material is injected onto the surface of a copper roll rotating at a circumferential speed of . Further, if necessary, heat treatment can be performed after injection to adjust the internal structure of the alloy.

As another method of obtaining the alloy, other metals or ceramic disks can be used instead of the copper roll. Furthermore, an atomization method in which a molten alloy is ejected into a gas or liquid at high speed can also be used when high-speed cooling is not required. In addition, according to scanning electron microscopy, the alloy powder that showed good magnetic properties in the present invention has a diameter of several tens to several hundred nm (1 nm = 10-9 m).
Fine crystal grains were observed, and X-ray diffraction revealed the presence of typical RiT+4B compounds and some alpha iron.

The alloy according to the present invention can be applied to any range, including not only isotropic bonded magnets, but also sintered magnets, isotropic or anisotropic metal magnets obtained by hot working, or metal magnets. It can be used in anisotropic bonded magnets that use pulverized powder.

The present invention is also characterized in that a bonded magnet is prepared by mixing a resin with the flakes or powder of the above-described alloy. In this bonded magnet, the type of resin is not particularly important;
For example, thermosetting resins such as epoxy resins and phenolic resins, or nylon and polyphenylene sulfide (
A thermoplastic resin such as PPS) can be used. When manufacturing this bonded magnet, molding in a magnetic field may be performed, and by this, it is possible to achieve a slight improvement in magnetic properties.

(Function) In the permanent magnet alloy configured as described above, due to the synergistic effect of the specified composition of rare earth metals, transition metals, boron, and vanadium, the residual magnetic flux density Br: 1O ~ 12KG
, Maximum magnetic energy product: BHmax18~22MGO
e, and the residual magnetic flux density was significantly increased, not only in comparison with conventional general-purpose alloys for bonded magnets, but also in comparison with the alloy disclosed in JP-A-2-57662. Incidentally,
Conventional general-purpose alloy powder for bonded magnets has been manufactured and sold by General Motors Corporation in the United States, and its representative powder (product name:
The magnetic properties of MQP-B) are the residual magnetic flux density Br:
8.5KG, maximum magnetic energy product BHmax:
It is 12MGOe. As a result, the magnetic properties of bonded magnets formed using this alloy were also significantly improved.

(Example) Examples of the present invention will be described below.

Example 1 A cast ingot was manufactured by high-frequency melting of an alloy having a predetermined composition as shown in Table 1. Each melted raw material contains Nd, Pr with a purity of 99% or more, and other rare earth metals with a purity of 95% or more,
Commercial grade ferroboron (Fe-B) containing electrolytic iron with a purity of 99% or more, melted cobalt, gamma-doped wood, brocade bamboo, and 1% by weight of C, Si, and Al was used. The above-mentioned ingot was coarsely crushed, loaded into a quartz injection tube, and subjected to high frequency melting, and then injected from the pores at the bottom of the quartz tube onto the surface of a rotating single roll using argon gas pressure and quenched. The obtained alloy has a width of 1 + n + a, a length of 100 to 500 mm, and a thickness of 0.
．． It was in the shape of a thin piece or ribbon of 0.03 mm. The roll is a water-cooled copper roll with a chrome-plated surface, and has a diameter of 4.
00mm. In addition, the peripheral speed of the roll is closely related to the magnetic properties of the obtained alloy flakes, so
/second range. The magnetic properties of the obtained alloy are shown in Table 1. Magnetic properties are measured using a vibrating sample magnetometer (VSM)
The measurement was carried out at room temperature after pulse magnetization of 60 KOe. Note that since the measurement was performed in the longitudinal direction of the thin section, no demagnetizing field correction was required.

As is clear from Table 1, the rare earth metal (R) in the alloy
In a suitable range of atomic percentage (5 atomic % or more and less than 9 atomic %), the residual magnetic flux density Br is loKG or higher, and the maximum magnetic energy product BHmax is about 20 MGOe,
Excellent magnetic properties were obtained. In addition, No, 1 and N
o and 8 are comparative examples.

Table 1 (#Comparative Example) Example 2 In the same manner as in Example 1, rapidly solidified alloy flakes were produced with a predetermined alloy composition, and their magnetic properties were measured. The results are shown in Table 2. As is clear from Table 2, a residual magnetic flux density Br greater than loKG was obtained at a moderate Co substitution rate. If the substitution of Co for Fe is too small (No,
11, 12), the effect is not remarkable, and in the case of excessive force (No, 18), it has become clear that the coercive force suddenly decreases.

Table 2 (#Comparative Example) Example 3 In the same manner as in Example 1, rapidly solidified alloy flakes were produced with a predetermined alloy composition, and their magnetic properties were measured. The results are shown in Table 3. As is clear from Table 3, 10K in an appropriate content range (more than 3 at%, ]5 at%)
A residual magnetic flux density of G or more was obtained. If the B content is too low (N.

, 19), the alloy becomes soft magnetic and the coercive force decreases rapidly,
It has become clear that when the amount is more than a certain amount (No, 24), the residual magnetic flux density decreases due to an increase in the non-magnetic phase.

Table 3 (#Comparative Example) Example 4 An ingot having a predetermined composition as shown in Table 4 was produced, and the molten alloy was injected from a quartz injection tube onto the surface of a rotating single roll and rapidly cooled. At this time, the roll peripheral speed was set to 35 m/sec in order to make the alloy amorphous. The obtained rapidly solidified alloy has a width of 0
．． It had the shape of a thin piece with a length of 5 mm, a length of 5 to 20 mm, and a thickness of 0.02 mm, and its magnetic properties showed that the coercive force was almost zero. Next, this thin piece was heated for 6 hours under an argon gas atmosphere.
Coercive force was restored by heat treatment in a temperature range of 00 to 750°C. The best magnetic property values thus obtained are shown in Table 4.

Table 4 (# Comparative Example) As is clear from Table 4, the appropriate content range (0,
5 atomic % or more and less than 5 atomic %), a residual magnetic flux density of 10 KG or more was obtained. If it does not include ■ (No, 25
), the coercive force decreases due to the appearance of the soft magnetic phase, and when the amount exceeds a certain amount (No, 30), it has become clear that the residual magnetic flux density decreases due to the increase in the non-magnetic phase.

Example 5 Thin flakes No. 19 to 24 in Example 3 and General Motors alloy powder MQP-B (compositional formula: Nd
+2Fe7tCOaBs) was pulverized to 150 microns or less using an impact air flow pulverizer. The resulting powder was mixed with 2% by weight of liquid epoxy resin, which was then filled into a mold and compressed at a pressure of 5 tons/cm 2 to give a diameter of 12 mm, a length of 1 O + nm, and a density of about 6.2 mm. g
/ cm" cylindrical sample was fabricated. Subsequently, a curing treatment was performed at 150°C for 1 hour to harden the epoxy resin. The magnetic properties of the sample were determined using a direct current B-H tracer under a maximum measurement magnetic field of 24 KOe. Measure the results with the fifth
Shown in the table. In addition, sample No. 19 A~ in Table 5
24A corresponds to sample Nos. 19 to 24 in Example 3, and sample No. 25A corresponds to powder MQP-H.

As is clear from Table 5, the bonded magnet using the rapidly solidified alloy flakes having the predetermined composition according to the present invention exhibited an excellent residual magnetic flux density of 8 KG or more compared to the bonded magnet shown as a comparative example. In addition, No, 19A, 24A
, and 25A are comparative examples.

Table 5 (#Comparative Example) Example 6 Similarly to Example 5, No. 19 in Example 3
~24 flakes and General Motors powder MQP-
B (compositional formula: Nd+tFetyCOaBg),
It was pulverized to 150 microns or less using an impact type air flow pulverizer. To the obtained powder, 8% by weight of nylon 12 was added and kneaded at 260°C, cooled and cut into pellets. Next, using an injection molding machine manufactured by Nippon Steel Corporation, the pellets were molded at an injection temperature of 290"C while nitrogen gas was flowed through the pellet supply port into a diameter of 16 mm, a length of 10 mm,
A cylindrical sample with a density of 5 g/cIIl'' was prepared. The magnetic properties of the sample were measured using a direct current B-H tracer under a maximum measuring magnetic field of 24 KOe, and the results are shown in Table 6.

In addition, sample Nos. 19B to 24B in Table 6 are as follows:
Sample Nos. 19 to 24 in Example 3 correspond, and sample No. 25B corresponds to powder MQP-B.

Table 6 (#Comparative Example) As is clear from Table 6, the magnet using the rapidly solidified alloy flakes having a predetermined composition according to the present invention exhibits an excellent residual magnetic flux density of 6 KG or more compared to the magnet shown as a comparative example. Ta. In addition, No. 19B.

24B and 25B are comparative examples.

(Effects of the Invention) As explained above in detail, according to the alloy for permanent magnets according to the present invention, the residual magnetic flux density is significantly reduced due to the synergistic effect of the predetermined composition of rare earth metals, transition metals, boron, and vanadium. It became an increasing thing. In addition, bonded magnets using this alloy have similarly high magnetic properties, and the range of their application has been expanded.

(2 others)

Claims (2)

[Claims] (1) Rare earth metal (R), transition metal (T), B, V in atomic percentage, X%R-(100-X-Y-Z)%T-Y
%B-Z%V (however, 5≦X<9, 3≦Y<15, 0.5≦Z<5), and the rare earth metal (R) is one or two of Nd and Pr. The transition metal (T) is made of an Fe-based alloy containing 5% or more and less than 30% of Co, and is characterized in that it is formed into flakes or powder by directly quenching the molten metal. Alloy for permanent magnets. (2) Rare earth metals (R), transition metals (T), B, B, V
is the atomic percentage, X%R-(100-X-Y-Z)%T
-Y%B-Z%V (5≦X<9, 3≦Y<15,
0.5≦Z<5), and the rare earth metal (R
) is made of a lanthanide element containing 50% or more of one or both of Nd and Pr, and the transition metal (T) is made of an Fe-based alloy containing 5% or more and less than 30% of Co, and the molten metal is directly quenched. A bonded magnet characterized by being made by mixing resin with flakes or powder formed by bonding.