JPH05343217A - Manufacture of rare earth magnet material - Google Patents

Abstract

PURPOSE:To obtain anisotropic materials with stable high orientability by using a rare earth-Fe-B alloy having columnar crystals in its cast macrotexture, and performing hydrogen occulusion and dehydrogenation processing of this alloy. CONSTITUTION:An alloy composed of 8-30atom.% of one or more kinds of rare earth elements, 3-15atom.% of B, and the rest; Fe, are arc-melted and poured into a casting die. And the casting die is cooled matching its cooling direction upwards from the bottom, and an alloy cast is manufactured so as to have more than 50vol.% of columnar crystals in its cast macrotexture. Following this, homogenization processing of this alloy cast is performed in an Ar atmosphere. After that, it is heated to a temperature in a range of 500-1,000 deg.C in a hydrogen gas atmosphere to occlude hydrogen. Following this, holding it at the same temperature in a vacuum atmosphere dehydrogenation is performed, and quenching is performed after that. Consequently, it becomes possible to orient crystals stably and obtain rare earth magnet materials having high coercive force and high magnetic anisotropy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a rare earth magnet material.

[0002]

2. Description of the Related Art As a rare earth magnet material, rare earth --Fe--
B-based alloys are provided. As a method for producing the above-mentioned rare earth-Fe-B based magnet material, conventional rare earth-Fe-B magnet materials have been used.
Ingots or powders of series alloys in hydrogen gas atmosphere
There is provided a method of heating in an ingot or powder of the alloy by heating in the range of 00 to 1000 ° C., then holding in a vacuum atmosphere for dehydrogenation, and then cooling (Japanese Patent Laid-Open No. 2-4901). ).

According to the above method, it is said that uniform crystal grains are formed in the alloy by the hydrogen absorption-dehydrogenation process, and thus a rare earth magnet material having high coercive force and magnetic anisotropy can be obtained.

[0004]

However, although a rare earth magnet material having a high coercive force and magnetic anisotropy can be obtained by the above method, the crystal orientation in the dehydrogenation step is insufficient and the crystal is stable. There was a defect that it was not oriented.

[0005]

As a means for solving the above-mentioned conventional problems, the present invention uses a rare earth-Fe-B type alloy cast so that the cast macrostructure becomes columnar crystals.

The rare earth-Fe-B system alloy used in the present invention has a rare earth element R of La, Ce, Pr, Nd, P.
m, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm
, Tb, Lu, Sc, Y, and Ac, or 2
The alloy is composed of at least 8 to 30 atomic% of B, 3 to 15 atomic% of B, and the balance of Fe and unavoidable impurities. In the alloy, a part of Fe is replaced by 0.01 to 50 atomic% of Co. May be. Furthermore, C, N, and
O, F, Al, Si, P, S, Cl, Sc, Ti, V,
Cr, Mn, Ni, Cu, Zn, Ga, Ge, As, S
e, Br, Zr, Nb, Mo, Tc, Rn, Rh, Pd
, Ag, Cd, In, Sn, Sb, Te, I, Hf,
Ta, W, Re, Os, Ir, Pt, Hg, Tl, Pb
, Bi, Po and At are 0.01 to
You may add 10 atomic%.

The above Co or additive element improves the magnetic characteristics of the rare earth magnet material of the present invention within the above additive amount range.

In step 1, the alloy is melted by arc melting, high frequency melting, or the like and poured into a casting mold to be cooled to form an ingot. In order to cast the cast macrostructure in the ingot into columnar crystals, The cooling direction of the molten metal in the casting mold is aligned, for example, from the bottom of the mold to the top or from the periphery of the mold to the center. By aligning the cooling directions as described above, the crystal growth directions are also aligned to form columnar crystals. In the present invention, 5 in the alloy casting
It is desirable that 0% by volume or more of columnar crystals be present.

If desired, the alloy casting obtained in step 1 may be homogenized. That is, the above alloy casting is used as an ingot or as it is, or pulverized into powder, and homogenized at 900 to 1200 ° C. If the homogenization temperature is lower than 900 ° C, it takes a long time to homogenize, and if it exceeds 1200 ° C, the alloy is melted. Bias is removed by such homogenization treatment.

Step 2 is a hydrogen storage step in which the alloy casting is heated to 500 to 1000 ° C. in a hydrogen gas or a mixed gas atmosphere of hydrogen gas and an inert gas to store hydrogen. It is considered that in the hydrogen storage step, R combines with hydrogen to form a hydride.

Step 3 is a dehydrogenation step. Following step 2, dehydrogenation of the hydrogen-absorbing alloy casting is performed in the same temperature range in a vacuum atmosphere where the hydrogen gas pressure is usually 1 × 10 ^-1 Torr or less. In the dehydrogenation step, the R hydride releases hydrogen to become an R intermetallic compound having a high magnetic property again, but due to such hydrogen absorption-release, the crystals in the alloy casting are arranged in a certain direction. At this time, the original columnar crystal structure affects this arrangement, and the crystals can be stably oriented. After dehydrogenation, the alloy casting is quenched.

[0012]

In the present invention, a rare earth-Fe-B system alloy having columnar crystals in the cast macrostructure is used, and hydrogen absorption-dehydrogenation treatment is performed on the alloy. An anisotropic rare earth magnet material is obtained which exhibits high orientation and thus high magnetic properties.
In particular, in the present invention, it was confirmed that high characteristic anisotropy can be obtained even if the particle size of the magnet material is large.

[0013]

EXAMPLE An R-Fe-B alloy having the composition shown in Table 1 was arc-melted and poured into a casting mold, and the casting mold was cooled from the bottom to the upper side in the same cooling direction to produce an alloy casting. did.
It was confirmed that 50% by volume or more of columnar crystals were present in the casting macrostructure of the alloy casting. FIG. 1 shows a photographic copy showing the structure of the alloy casting.

The above-mentioned alloy castings were stored at 1100 ° C. for 20 hours,
After homogenizing treatment in an Ar atmosphere, and then heating in a hydrogen gas atmosphere at 850 ° C. for 3 hours to occlude hydrogen, and subsequently at the same temperature for 1 hour, hydrogen gas pressure 1 × 10 ⁻¹ T
Dehydrogenation was performed by holding in a vacuum atmosphere at orr or lower, and then rapidly cooled to obtain an anisotropic rare earth magnet material.

[0015]

[Table 1]

The above anisotropic rare earth magnet material was pulverized to 400 μm or less, 3.0 wt% of epoxy resin was added and mixed as a binder, and 8 ton / cm ^{2 in} a magnetic field of 15 KOe.
Press molding was performed under the pressure of, and then thermosetting treatment was performed at 150 ° C. for 1 hour to produce an anisotropic bonded magnet. The residual magnetic flux density Br, the coercive force iHc, and the maximum energy product (BH) _max of each of the bonded magnets were measured. The results are shown in Table 2.

[Comparative Example] R-Fe-having the composition shown in Table 1
The B-based alloy was arc-melted, poured into a casting mold, and cooled from the entire surface of the casting mold without matching the cooling directions to manufacture an alloy casting. It was confirmed that the cast macrostructure of the alloy casting had columnar crystals of about 10% by volume. Homogenization treatment and hydrogen storage similar to the example for the above alloy castings
Dehydrogenation treatment was performed, followed by rapid cooling to obtain an anisotropic rare earth magnet material. An anisotropic bonded magnet was produced from the above anisotropic rare earth magnet material in the same manner as in the example, and Br, iHc, (BH) _max of each of the bonded magnets were measured. The results are also shown in Table 2.

[Table 2]

In Table 2, comparing the examples with the comparative examples, the examples show that Br, iHc,
Both (BH) _max show high values, and it is confirmed that the magnetic properties are excellent.

[0019]

Therefore, according to the present invention, an anisotropic rare earth magnet material having extremely good magnetic properties can be obtained.

[Brief description of drawings]

FIG. 1 is a photocopy drawing showing the structure of an alloy casting of an example.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location B22F 9/04 D C22C 33/02 D 38/00 303 D 38/10 H01F 1/06

Claims (3)

[Claims] 1. One or more rare earth elements of 8 to 3
Step 1 of melting an alloy composed of 0 atomic%, B of 3 to 15 atomic% and the balance of Fe and inevitable impurities and casting so that columnar crystals are present in the casting macrostructure. 50 in hydrogen gas atmosphere
Step 2 of heating in the range of 0 to 1000 ° C. to occlude hydrogen. Subsequent to Step 2, in the same temperature range, the hydrogen occlusive alloy casting is held in a vacuum atmosphere for dehydrogenation and then rapidly cooled. Method for producing rare earth magnet material comprising steps 1, 2 and 3 2. A part of Fe in the alloy is 0.01 to
The method for producing a rare earth magnet material according to claim 1, wherein an alloy substituted with 50 atomic% of Co is used. 3. The alloy containing C, N, O, F, Al, Si,
P, S, Cl, Sc, Ti, V, Cr, Mn, Ni, C
u, Zn, Ga, Ge, As, Se, Br, Zr, Nb
, Mo, Tc, Rn, Rh, Pd, Ag, Cd, In
, Sn, Sb, Te, I, Hf, Ta, W, Re, Os
Of the rare earth magnet material according to claim 1 or 2, wherein an alloy containing 0.01 to 10 atom% of one or more of Ir, Pt, Hg, Tl, Pb, Bi, Po and At is used. Production method