JPH04280403A - Rare-earth magnet alloy and rare-earth permanent magnet - Google Patents

Abstract

PURPOSE:To obtain a rare-earth magnet alloy and a rare-earth permanent magnet with high magnetic characteristics by allowing an alloy composition to consist of a specific expression, its main phase to be in centroid tetragonal ThMn12 structure, and an intrusion atom between grids to be provided. CONSTITUTION:An Sm metal with a purity of 99.9% and Fe, Co, and C with a purity of 99.9% are weighed, they are melted by high frequency within an inactive gas, and then the melt is cooled by the use of a copper mold. After this ingot is roughly ground, it is crushed into a fine powder of 3-5mum in diameter by a jet mill of N2 gas. While this fine powder is oriented in a static magnetic field of 15kOe, press formation is performed with a pressure of 1ton/cm<2>, this formed body is sintered at a temperature of 1050-1250 deg.C within the inert gas for 1-2 hours, and then it is subjected to heat treatment for 1 hour or longer at a temperature range of 500-900 deg.C before it is rapidly cooled, thus enabling R(Fe, Co)12 magnetic body in ThMn12 structure to be stabilized by introducing C and N.

Description

[Detailed description of the invention]

0001

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

0002

BACKGROUND OF THE INVENTION Among body-centered tetragonal ThMn12 type rare earth-transition metal compounds, high Fe content ternary compounds were previously invented by the present inventors. ThMn12 type RF
There is no e12 compound, and the compound in the high Fe region is stabilized for the first time by introducing a third element. Typical stoichiometry is SmTiFe11, SmV2Fe1
0, SmCr2Fe10, SmMo2Fe10, SmW
Fe11, 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 the high content of Fe. Moreover, among these, Sm-based compounds have a significantly high anisotropic magnetic field and are optimal as permanent magnet materials, and in fact, high coercive forces of 10 KOe or more have been obtained in liquid super-quenched magnets. 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. However, although Sm2Fe17 exhibits good magnetic properties,
It rusted easily and had problems in terms of oxidation resistance. (X.P.ZH
ONG, et al. , J. Magn. Magn. Ma
ter. 86, 333 (1990). , J. M. D.
Coey and HongSUN, J. Magn. M
agn. Mater. 87, L251 (1990). reference)

[0005]

[Problems to be Solved by the Invention] From the above points of view, the present invention provides rare earth magnet alloys and rare earth magnetic The idea is to provide a permanent magnet.

[0006]

[Means for solving the problem] The present inventors have developed R(MF
e) 12 As a result of repeated research on the role of the M element in compounds, the present invention was completed, and the alloy composition is of the formula R(Fe1-XCoX)Y AZ (However, R is S
One or more rare earth elements mainly consisting of m, A
is one or more of C or N, 0≦X≦0.5, 10≦Y
≦13, 0.1≦Z≦2), the main phase of which has a body-centered tetragonal ThMn12 structure and has interstitial atoms, and rare earth permanent magnets. be.

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.

[0008] From the above considerations, it is clear that
It is considered that if an element that expands the crystal lattice exists, the restrictions on the space in which the Fe atom should enter are relaxed, and it is possible to reduce or eliminate the amount of substitution of the M element. In R2Fe17 compounds, it is known that C and N enter in the interstitial form, so RFe12 or R(
As a result of investigating the stabilization of the ThMn12 structure by C and N in MFe)12, it was found that it is possible.

[0009] C and N can penetrate up to three atoms according to the compositional formula (RFe12A3), but in reality, three atoms cannot penetrate, and only two atoms at most. If the amount of penetration is too small, the spread of the lattice is too small and the ThMn12 structure cannot be stabilized, so it is necessary to penetrate 0.1 atoms or more. Fe atoms can be replaced with Co atoms, and Co substitution improves the Curie temperature and improves the temperature stability of magnetic properties. Further, 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 X≦0.5 or less. The amount of transition metal is Y<
10, R2Fe17 Ax is stabilized and Y<1
3, Fe becomes the main phase and the ThMn12 structure is not stabilized, so it is necessary to be within this range. Here, R is a rare earth element mainly composed of Sm, preferably Sm
, Ce, Pr, and Nd.

[0010] In producing the magnetic alloy of the present invention, RF
e12Cx and RFe12Nx and RFe12Cx
In the case of NY, 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. As the form of C, powder or lump of pure C, or carbide such as Fe-C or R-C may be used. On the other hand, for N-based, the constituent metals are weighed and
After melting, the alloy is crushed and nitrided in a nitrogen gas atmosphere or an ammonia gas atmosphere while being maintained at a high temperature of 100° C. or higher to introduce nitrogen into the alloy. 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.

0012

[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
Table 1 (Alloy No. 2, 4,
6, 8, 10), high-frequency melting was performed in an inert gas, and the molten metal was cooled in a copper mold. After coarsely pulverizing the ingot, use a jet mill using N2 gas to grind the ingot to 3 to 5 μm.
It was finely pulverized to a diameter. 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 body was placed in an inert gas at 1.0
Sintering was performed at a temperature of 50 to 1,250°C for 1 to 2 hours, followed by heat treatment at a temperature of 500 to 900°C for 1 hour or more, and then rapidly cooled. Magnetic properties of the sintered body i
Table 1 shows the results of measuring Hc using a self-recording magnetometer. As a comparative example, an alloy without C added was alloy No. 1, 3, 5
, 7, and 9, and are also listed in Table 1. As shown in Table 1, those without C do not have a ThMn12 structure but a 2-17 phase with a Th2Zn17 structure and Fe and C
Since it separates into the o phase, it does not exhibit good magnetic properties.

[0013]

[Table 1]

(Example 2) Sm metal with a purity of 99%, Fe, Co and C with a purity of 99.9% were prepared in Table 2 (Alloy No.
2, 4, 6, 8, 10), high-frequency melting was performed in an inert gas, and the melt was cooled in a copper mold. The ingot was heat-treated in an inert gas at a temperature range of 500 to 900°C for 1 hour or more, and then crushed and further heated with N2.
The powder was pulverized to 3 to 5 μm using a gas jet mill, and then nitrided in N2 gas at a temperature of 400 to 550°C. 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 were investigated iH
c was measured and shown in Table 2. Comparative example (Alloy No. 1,
3, 5, 7, and 9), which were magnetized without nitriding after pulverization, are also listed in Table 2. As shown in Table 2, those subjected to nitriding have improved magnetic properties compared to those not subjected to nitriding.

[0015]

[Table 2]

[0016]

[Effect of the invention] The present invention enables ThMn1 to be stabilized, which conventionally could not be stabilized without introducing a metal such as Ti to the transition metal side.
Not only was the R(Fe,Co)12-based magnetic material with a two-structure structure stabilized by the introduction of C and N, but by using this to reduce the amount of Co compared to conventional SmCo-based magnets and replacing it with Fe. Since a lower-cost magnetic alloy has been realized, its utility value in industry is extremely large.

Claims (1)

[Claims] [Claim 1] The alloy composition has the formula R(Fe1-XCoX)
Y AZ (However, R is one or more rare earth elements mainly composed of Sm, A is one or more of C or N, 0
≦X ≦0.5, 10≦Y ≦13, 0.1≦Z ≦2
), the main phase of which has a body-centered tetragonal ThMn12 structure and has interstitial atoms, and a rare earth permanent magnet.