JPH04308063A - Magnet alloy containing rare earth element and permanent magnet containing rare earth element - Google Patents

Abstract

PURPOSE:To improve magnetic characteristics and oxidation resistance by reducing the amt. of the tertiary element of a compd. in the high Fe region of a prescribed compsn. consisting of rare earth elements, Ze, Hf, Bi, Fe, Co, V, Cr, Mn, Mo, C, etc. CONSTITUTION:This magnet alloy contg. rare earth elements has a compsn. represented by a formula R1-XM1X[(Fe1-YCoY)1-ZM2Z]UAW (where R is one or more kinds of rare earth elements, M1 is element selected from Zr, Hf or Bi, M2 is element selected from Ti, V, Cr, Mn, Mo, W, Nb, Ta, Si or Al, A is C and/or N, X is 0.01-0.4, Y is 0-0.5, Z is 0.01-0.2, U is 10-13 and W is 0.1-2) and has a principal phase having body-centered tetragonal system TnMn12 structure. In this alloy, M1 atoms substitute for part of R atoms, M2 atoms substitute for part of Fe or Co atoms and A atoms are present as interstitial atoms. When this alloy is pulverized, molded under orientation in a magnetic field, sintered and aged, a permanent magnet contg. rare earth elements is obtd.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a new rare earth magnet alloy having a ThMn12 structure and high magnetic properties, and a rare earth permanent magnet.

0002

BACKGROUND OF THE INVENTION Among body-centered tetragonal ThMn12 type rare earth-transition metal compounds, a ternary compound with a high Fe content was previously invented by the present inventors (Patent Publication No. 1983-
241302, 62-241303, 62-24130
5, 63-248102, 63-248103, 63-
273302, 63-273303, Hei 01-0535
07, 01-067902) ThMn12 type R
No Fe12 compound exists, and the compound in the high Fe region is stabilized for the first time by introducing a third element. Typical stoichiometry is SmTiFe11, SmV2Fe
10, SmCr2Fe10, SmMo2Fe10, Sm
WFe11, SmSi2Fe10, SmReFe11, etc. are known. Of course, it is not limited to Sm, and there are compounds having the same stoichiometric ratio for almost all rare earth elements (R). A compound having such a ThMn12 structure in a high Fe region is converted into R(MFe
)12 Most of these compounds have a Curie temperature (Tc) of 300° C. or higher, and also have a high saturation magnetic flux density (Ms) due to their high Fe content. Among them, Sm-based compounds have a significantly high anisotropic magnetic field, making them optimal as permanent magnet materials.
In fact, a high coercive force of 10 KOe or more has been obtained with a liquid ultra-quenched magnet. Nd2Fe14B is the only other known ternary compound in such a high Fe region.

[0003] The R(MFe)12 compound has very high magnetic properties as mentioned above, but it
) is a non-magnetic element, and not only does it dilute the magnetism in proportion to its amount, but also the conduction electrons derived from the M element dilute the magnetic moment of the Fe atom, resulting in a significant decrease in the average magnetic moment of Fe. are doing. Therefore, for example, Nd2
Comparing Fe14B and SmTiFe11 compounds, F
Although the atomic percentages of e atoms are almost the same, the magnitude of saturation magnetization is considerably lower in the latter. For this reason R(MFe)
Efforts are being continued to reduce the ratio of the third element M in the 12 series as much as possible, and if possible, to bring it close to zero to increase the saturation magnetization. However, no success has been achieved in lowering the ratio of M element further than in RTiFe11 compounds and the like.

On the other hand, the R2Fe17 compound having a rhombohedral Th2Zn17 (or hexagonal Th2Ni17) structure has a low Curie temperature and a negative crystal magnetic anisotropy constant, so it is not suitable as a permanent magnet material. However, it has recently been found that it is possible to introduce carbon C or nitrogen N at interatomic positions. By interstitial introduction, the lattice widens, resulting in a significant increase in the Curie temperature,
Furthermore, it was found that the magnetocrystalline anisotropy also showed a significant increase. As a result, especially Sm2Fe17Ax (A=C
Or N) is a magnet material such as SmCo17 or Nd2F.
It was found that it showed a very high value comparable to e14B (X.P. ZHONG, et al., J. Magn.
Magn. Mater. 86, 333 (1990). ，
J. M. D. Coey and Hong SUN,
J. Magn. Magn. Mater. 87,L251
(1990). reference). However, although Sm2Fe17AX exhibits good magnetic properties, it easily rusts and has problems in terms of oxidation resistance.

[0005]

[Problems to be Solved by the Invention] From the above points of view, the present invention aims to improve the magnetic properties by reducing the third element M of the R(MFe)12 compound, which is a compound in the high Fe region, and at the same time improve the oxidation resistance. It is an object of the present invention to provide a rare earth magnet alloy and a rare earth permanent magnet having a ThMn12 structure with excellent properties.

[0006]

[Means for solving the problem] The present inventors have developed R(MF
e) As a result of repeated research on the role of the M element in 12 compounds, we found that the iron site, such as Zr and Hf of the M1 element, replaces the R site as the third element M, which had been introduced to stabilize the Th2Mn12 structure. It was discovered that M2 elements such as Ti, V, Cr, etc. that replace the oxide react with C and N to easily generate stable carbides and nitrides, improving oxidation resistance, and after thorough consideration of various conditions, the present invention was developed. is completed, and the alloy composition formula is (R1-XM1X[(Fe
1-YCoY)1-ZM2Z]U AW (However, R is one or more rare earth elements, M1 is Zr, Hf
, one or more elements selected from Bi, M2
are Ti, V, Cr, Mn, Mo, W, Nb, Ta, S
i, one or more elements selected from Al, A
is one or more of C or N, 0.01≦X≦0.4, 0
≦Y ≦0.5, 0.01≦Z ≦0.2, 10≦U
13,0.1 A rare earth magnetic alloy characterized by the presence of interstitial atoms, and finely pulverizing this rare earth magnetic alloy,
The gist is a rare earth permanent magnet formed by oriented forming in a magnetic field, sintering, and aging, and a rare earth bonded magnet formed by mixing an organic binder with this rare earth magnet alloy powder, oriented forming in a magnetic field, and hardening.

The present invention will be explained in detail below. When the lattice of the M element is slightly larger than that of Fe, it is thought that the M element replaces Fe, expands the lattice, and stabilizes the ThMn12 structure. It is known that when the M element is vanadium V, which has a wide solid solubility limit, the lattice shrinks as the V amount decreases. In other words, without the M element, the lattice becomes small, and the space in which Fe atoms should originally enter becomes too small. But also, if the M atom is much larger than the Fe atom,
Since the lattice must be expanded significantly, ThMn
12 structure cannot be stabilized. For this reason, R( M
It is thought that the elements that stabilize the Fe)12 compound are limited and the amount of substitution is also limited within a narrow range.

From the above considerations, it is possible to expand the crystal lattice by interstitially entering between atoms, replacing the iron site with a larger atom, or replacing the R site with an atom smaller than the rare earth atom. It is thought that if a gap is created by this, the restriction on the space in which iron atoms should enter will be relaxed, and it will be possible to reduce the amount of substitution of the third element. R2Fe
17 It is known that C and N enter in the interstitial form in the compound (R, M1) (Fe, M2) 12. As a result of investigating the stabilization of the ThMn12 structure by C and N in (R, M1) (Fe, M2) 12, it was found that it is possible. Ta. On the other hand, as the third element M, M1 elements such as Zr, Hf, etc. that substitute the R site, and M2 elements, such as Ti, V, Cr, etc. that substitute the iron site, substitute C.
It was also found that stable carbides and nitrides are easily produced by reacting with carbon and nitrogen.

From the above, it is possible to stabilize the ThMn12 structure by adding M1 and M2 elements that substitute the R site and Fe site, respectively, to the RFe12 compound, and to protect stable carbides and nitrides by introducing C and N. By forming a film, high Fe material with excellent magnetic properties and corrosion resistance can be produced.
It has been found that it is possible to obtain rare earth transition metal compounds in the region. Furthermore, by adding M1, M2, C, and N in combination, the ThMn12 structure can be stabilized with a smaller amount than when each of them is stabilized alone, so there is less magnetic dilution, compared to the conventional method. The effect was that the magnetic properties were superior to those stabilized alone.

[0010] Here, R includes Y La, Ce, Pr,
Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, E
One or more rare earth elements selected from r, Tm, Yb, Lu, etc., preferably Sm or two or more elements mainly composed of Sm. C and N are compositional formulas (
R,M1)(Fe,M2)12A3 Up to three atoms can penetrate, but in reality three atoms cannot penetrate, and only two atoms at most. If the amount added is too small, the formation of a protective film made of carbide or nitride of element M will be insufficient, and satisfactory oxidation resistance will not be obtained. Therefore, it is necessary to add 0.1 atom or more. The range of 1≦W≦2 is preferable. Fe atoms can be replaced with Co atoms, and Co substitution increases the Curie temperature and improves the temperature stability of magnetic properties. Furthermore, although the saturation magnetization increases slightly due to Co substitution, the crystal magnetic anisotropy decreases on the contrary, so the amount of Co substitution is preferably Y≦0.5 or less. The amount of transition metal is as follows: When U<10, R2Fe17 AW is stabilized, and U
If >13, Fe will become the main phase and the ThMn12 structure will not be stabilized, so it is necessary that it be within this range.

[0011] The amount of the added metal element M is such that the amount X of the element M1 substituting the R site is 0.01 or more and 0.4 or less.
The amount Z of the M2 element substituting the Fe site is desirably 0.01 or more and 0.2 or less. M1 element is less than 0.01, and M2 element is less than 0.01.
If it is less than 01, satisfactory corrosion resistance cannot be obtained. Furthermore, if the amount of M1 is more than 0.4, RFe12
Since the magnetic anisotropy of the system magnetic alloy mainly depends on the R element, in terms of anisotropy, and if the M2 element also exceeds 0.2, the saturation magnetization mainly depends on the amount of Fe atoms. As a result, their magnetic properties deteriorate in terms of saturation magnetization. Here, R is applied to one or more elements selected from the group consisting of rare earth elements mainly consisting of Y, Th, and Sm.

In producing the magnetic alloy of the present invention, (R,
M1) (Fe, M2) 12 CW , (R, M1) (F
e,M2)12NW and (R,M1)(Fe,M
2) In the case of 12 C1-W NW, the manufacturing method is slightly different. In the case of C-based metals, the constituent metals and C are weighed in a predetermined ratio, and then mixed and melted in a high-frequency furnace, arc furnace, etc. to produce an alloy. The form of C is pure C powder or lump, or Fe-C
A carbide such as or R-C may also be used. On the other hand, for N-based alloys, after weighing and melting the constituent metals, the alloy is crushed and 10
Nitrogen is introduced into the alloy by performing nitriding treatment in a nitrogen gas atmosphere or an ammonia gas atmosphere while maintaining the alloy at a high temperature of 0° C. or higher. The higher the gas pressure used, the better, but it is preferably 1 atm or higher, and the temperature at that time must be 700° C. or lower, otherwise the intruded N will not be stabilized. Further, nitriding treatment may be further added to the C-based material into which C is introduced.

The magnetic alloy of the present invention can be magnetized by various means. Typical means include sintered magnets or bonded magnetization. The obtained alloy is finely pulverized using a jet mill or the like to produce a magnet alloy powder. For this fine pulverization, a liquid super-quenching method, a mechanical alloying method, a gas atomization method, or the like may be used. For sintered magnets, magnet alloy powder is formed while being oriented in a magnetic field, sintered at a temperature in the range of 1,000 to 1,300°C, and then aged at 500 to 900°C. For bonded magnets, magnet alloy powder is mixed with an organic binder,
After orientation in a magnetic field, the organic binder may be cured to form a bonded magnet.

[0014]

[Examples] Hereinafter, embodiments of the present invention will be explained in detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. (Example 1) 99% purity Sm metal, 99.9% purity
Fe, Co, and additional metal elements M1, M2, and C were each weighed as shown in Table 1 (alloy numbers 2 to 7), high-frequency melting was performed in an inert gas, and the molten metal was cooled in a copper mold. After coarsely pulverizing the ingot, it is crushed in a jet mill using N2 gas for 3~
Fine pulverization was performed to a diameter of 5 μm. The fine powder was oriented in a static magnetic field of 15 KOe and press-molded at a pressure of 1 ton/cm2, and then the molded product was molded in an inert gas at a temperature of 1,050 to 1,250°C for 1 to 2 hours. Sintering was performed for a period of time, followed by heat treatment at a temperature range of 500 to 900° C. for 1 hour or more, followed by rapid cooling. Table 1 shows the results of measuring the magnetic properties iHc of the sintered body using a self-recording magnetometer. As a comparative example, an alloy without C added was alloy No. 1 and are also listed in Table 1. As shown in Table 1, the magnetic properties of the C-added alloys are improved compared to the C-added alloys. In addition, in the case of adding the additive elements M1, M2 and C, the amount of M1 element added is smaller than that of adding the M1 element alone, so magnetic dilution is reduced and the magnetic properties are improved. (Refer to JP-A-Sho and JP-A-Hei in the prior art column). Corrosion resistance test: The sintered magnets of alloy numbers 1 and 2 are left in the air at a temperature of 80°C and a humidity of 90%, and the rate of decrease in iHc from the initial value, that is, the degree of deterioration, is measured. The results of the corrosion resistance test are shown in Table 2. It can be seen that the C-added alloy has better corrosion resistance.

[0015]

[Table 1]

[Table 2]

(Example 2) In Example 1, the finely pulverized powder was subjected to nitriding treatment at 400 to 550°C in N2 gas for 24 hours (powder that was not nitrided was also made into a bond magnet, and the iHc was measured and recorded. ). After dispersing the powder in an epoxy resin, the resin was hardened by magnetic orientation in a static magnetic field of 15 KOe to produce a bonded magnet, and its magnetic properties iHc were measured and shown in Table 3. As a comparative example (alloy number 1), carbon-free products that were made into bonded magnets with and without nitriding treatment are also listed in Table 3. As shown in Table 3, those subjected to nitriding have improved magnetic properties compared to those not subjected to nitriding.

[0017]

[Table 3]

[0018]

Effects of the Invention According to the present invention, R(Fe,Co)12 of ThMn12 structure, which conventionally could not be stabilized unless Zr and Ti were replaced with rare earth sites or transition metal sites, respectively.
The problem with magnetic materials, that is, magnetic properties such as saturation magnetic flux density and Curie point become inferior to ideal values due to substitution with non-magnetic elements, can be solved by reducing the number of substitution elements by introducing C and N. As a result, good magnetic properties can be obtained. Moreover, since Fe is used as the main raw material instead of expensive Co, it has a large cost advantage compared to conventional SmCo-based magnets. Furthermore, Zr, Ti
Magnet alloy powder, which used to be easy to oxidize and difficult to handle, forms a protective film on the surface of magnets and magnet alloy powder, as carbides and nitrides, which are stable with C and N, are formed as a protective film on the surface of magnets and magnet alloy powder, although the amount of substitution elements such as C and N is small. It is possible to avoid the deterioration of magnetic properties due to oxidation of magnets, and it also has the advantage that unlike Nd2Fe14B magnets, there is no need for plating, resin coating, etc., and it can be used as is after forming and sintering. Extremely large.

Claims (3)

[Claims] Claim 1: The alloy composition formula is (R1-XM1X[(Fe
1-YCoY)1-ZM2Z]U AW (However, R is one or more rare earth elements, M1 is Zr, Hf
, one or more elements selected from Bi, M2
are Ti, V, Cr, Mn, Mo, W, Nb, Ta, S
i, one or more elements selected from Al, A
is one or more of C or N, 0.01≦X≦0.4, 0
≦Y ≦0.5, 0.01≦Z ≦0.2, 10≦U
13,0.1 A rare earth magnetic alloy characterized by the presence of interstitial atoms. 2. A rare earth permanent magnet, which is obtained by finely pulverizing the rare earth magnet alloy according to claim 1, orientation forming in a magnetic field, sintering, and aging. 3. The rare earth magnet alloy according to claim 1 is finely pulverized, an organic binder is mixed with the powder, and oriented molding in a magnetic field is performed.
A rare earth bonded magnet characterized by being made by hardening.