JPS62262403A - Manufacture of rare earth permanent magnet - Google Patents

Abstract

PURPOSE:To improve magnetic characteristics of an obtained permanent magnet by improving a grindability of an ingot by making the magnet from an alloy which has a macro-structure of an ingot consisting of a rare earth metal, iron and boron changed into a column structure by zone heating. CONSTITUTION:An alloy which has a macro-structure of an ingot consisting of a rare earth metal, iron and boron changed into a column structure by zone heating is made into a magnet. As the rare earth metal, Y, La, Ce, Pr, Nd, and Pm are available. Thus. grindability of the ingot can be improved and magnetic characteristics of the obtained permanent magnet are improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing a rare earth permanent magnet whose basic composition is a rare earth metal, iron, and boron [Prior Art] Conventionally, the basic composition is a rare earth metal, iron, and boron. In order to make the macrostructure of an alloy ingot consisting of iron and boron into a columnar structure,
The cooling rate after casting was controlled by improving the structure of the casting mold.

[Problem that the invention seeks to solve]

However, although the above method is possible with melting of several tons, melting of tens to hundreds of tons results in extremely low Ff (M), and the casting structure cannot be completely obtained, and the melting process takes a long time. It has problems such as the fact that it is not suitable for company production.

The present invention solves the above problems, and its purpose is to make the macrostructure of the ingot into a columnar structure and improve the magnetic performance even during melting during mass production of tens to hundreds of tons. The purpose of the present invention is to provide a method for manufacturing rare earth permanent magnets that stabilizes quality.

[Means for solving problems]

The method for producing a rare earth permanent magnet of the present invention is characterized in that the basic composition is a rare earth metal, iron, and boron, and magnetization is performed using an alloy in which the macrostructure of an ingot is made into columnar fibers by a zone heating method. do.

Generally, when molten metal is poured from a crucible into a mold, the molten metal first contacts the walls of the mold and is rapidly cooled to a degree of 1 which causes extensive nucleation, forming a chill layer. Next, as heat flows into the mold, the columnar fibers extend inward perpendicular to the mold wall. When the heat flow further ceases, an equiaxed structure appears instead of a columnar structure, and solidification in the mold is completed.

Therefore, as shown in FIG. 2, the macrostructure at the time of casting is formed of a chilled structure (1'I), a columnar structure (2), and an equiaxed structure (3,).

By making the macrostructure of the ingot whose basic composition is a rare earth metal, iron, and boron into a columnar structure, the crushability of the ingot is improved, and the magnetic performance of the obtained permanent magnet is also improved.

However, as mentioned above, it is difficult to make the macrostructure of the ingot into a columnar structure, especially when the ingot is in a cryogenic state.

Therefore, as shown in Figure 1, a part of the ingot after casting is melted in a band shape using equipment similar to zone melting or zone refining, and this zone is moved. Oriental crystal growth becomes possible, and a columnar structure can be obtained.

In addition, as a rare earth permanent magnet whose basic composition is rare earth metal, iron, and boron, there is "Na-?" θ-B magnets are known, but examples of rare earth gold include Y, La, Oe, and Pr.
, Nd, Pm, Sm, Eu.

Any one or more of the rare earth elements Gd, T'b, Dy, Ho, l1ir, Tm, Yb and Lu may be used, and didymium (Pr-Na) and cerium didymium (O
e-P r-N d) can also provide sufficient magnetic performance and is advantageous from the standpoint of supply and price. Furthermore, by adding a small amount of heavy rare earth elements such as Dy and Tb, the coercive force 1Hc can be increased and a substantial improvement in temperature characteristics can be achieved.

In addition, by filling part of iron with cobalt, the Curie temperature was improved, and with other transition metal groups, tif
[Example] The present invention will be described in detail based on Examples below.

(Example-1) Nd15? Melt and cast in a high-frequency melting furnace under argon gas B) atmosphere so that the composition becomes 3g.
An alloy of 0KP was obtained. The obtained ingot contained only a small amount of columnar composition and was mostly equiaxed green. When this ingot was subjected to zone heating using the apparatus shown in FIG. 1, it became almost completely columnar.

As a comparative example, a cast ingot containing only a small amount of columnar fibers was also prepared.

These ingots were made into powder with a #32 mesh using a stamp mill, and finely ground using a ball mill while changing the grinding time, and the average particle size of the powder was measured using a 1.S-5-S.

The results are shown in FIG.

As is clear from FIG. 3, it can be seen that the powder of the present invention becomes fine powder in a shorter time than that of the comparative example. Comparing the macrostructures of the ingots, the ingots of the present invention have more complete columnar fibers, so it can be said that the crushability is improved by making the macrostructure into columnar fibers.

(Example-2) NdlL5D7L5'! 8670010BB, using the same method as in Example-1, changing the grinding time, to create predetermined magnetic powders of the present invention and comparative examples. This magnetic powder was oriented in a magnetic field of 15 KOe, and the molding pressure was 154/. 1 molding, sintering at an appropriate temperature of 1000 to 1200 tl'/i in an Alcon gas atmosphere, and aging at an optimum temperature of 400 to 1000°C.

Magnetic performance was measured using the obtained magnet or H tracer. FIG. 4 shows the relationship between the coercive force (iHc), which is the most significant point in the obtained magnetic performance, and the grinding time.

As is clear from FIG. 4, iHc reaches the maximum value in a shorter time in the present invention than in the comparative example, and the maximum value is also a large value. That is, by forming the macrostructure into a columnar molding, not only the crushability is improved, but also the magnetic performance of the resulting magnet is improved.

(Example-3) (2PrO to Os, 1N110.SD7α1)ls? e
The alloy of sToolOBa was finely pulverized using a vibration mill while changing the pulverization time, and the same method as in Example 1 was used to create predetermined magnets of the present invention and comparative example.

Similarly, the relationship between coercive force (iHc) and grinding time is shown in FIG.

As is clear from Fig. 5, in the present invention, 1Hc is somewhat lower than when using a ball mill, but it is sufficiently practical, whereas in the comparative example, it was not possible to obtain a satisfactory iHc. .

〔Effect of the invention〕

As described above, according to the present invention, by magnetizing using an alloy whose basic composition consists of rare earth metals, iron, and boron, and which has a columnar structure in the macro structure of the ingot by the zone heating method, Improved crushability compared to conventional methods,
Not only is the time required for the crushing process significantly reduced;
The magnetic performance of the resulting permanent magnet has also been greatly improved, and in particular, the crushing efficiency is much better than that of a ball mill, and even when using a vibration mill, which is indispensable for mass production, sufficient fIi performance can be obtained for practical use. This has great effects in shortening process time, improving yield, reducing costs, and stabilizing quality.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the zone heating method of the present invention. 1... Strip heating device 2... Column structure portion 3... Untreated portion FIG. 2 is a sectional view of the ingot during casting. 1... Chill structure 2... Column structure 3... Equiaxed structure fg3 Figure is a diagram showing the relationship between grinding time and average particle size of the present invention and comparative example. . Figure 4 shows the grinding time and coercive force (1HO
) relationship diagram. FIG. 5 is a diagram showing the relationship between the grinding time and coercive force (iHo) of the present invention and a comparative example using a vibratory mill. Applicant: Seiko Epson Corporation/Z6-No.20
Δ12/ρ0 2er. Mebushin 13 Machi Seki Yko figure 3 at the mouth / 2 Evening 10 20 rO1w 2
ρ0 shipping time [shi] Figure 4 ke 10 Z117 rO/co
2a. Face Koichi Samurai [y-4] Figure 5

Claims (2)

[Claims] (1) A method for producing a rare earth permanent magnet, characterized in that the basic composition is a rare earth metal, iron, and boron, and magnetization is performed using an alloy in which the macrostructure of the ingot is a columnar structure by a zone heating method. (2) The method for producing a rare earth permanent magnet according to claim 1, wherein a part of the iron is replaced with at least one transition metal group selected from the group of transition metals other than iron, such as cobalt.