JPH1022112A - Method for manufacturing rare earth magnet of selected grade using a plurality of particle batches - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize low price by mixing a plurality of particle batches of permanent magnet alloy containing rare earth element with particle batches having different chemical composition and magnetic characteristics, for manufac turing permanent magnet of specified grade. SOLUTION: Relating to manufacturing of a permanent magnet, containing rare earth element, of specified grade, with particle batches having different chemical composition and magnetic characteristics, a plurality of particle batches for permanent magnet alloys are produced, and with different batch preparations in quantity, a specified particle mixture of different compositions is made. When worked into a permanent magnet, the particle mixture obtains a specified combination of magnetic characteristics different from other mixtures, while different from magnetic characteristics of permanent magnets manufactured each of a plurality of particle batches. Then, one mixture of specified composition is worked, to manufacture a permanent magnet of specified grade. In addition, at least one of permanent magnet alloy of particle batch is of heavy rare earth element and light rare earth element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method of selecting a rare earth element-containing permanent magnet by mixing a plurality of batches of a permanent magnet alloy containing a rare earth element with each of batches having different chemical compositions and different magnetic properties. The present invention relates to a method of producing a graded grade, in which different grades of rare earth-containing permanent magnets are produced without requiring the production of a specific alloy corresponding to each grade produced. Would.

[0002]

BACKGROUND OF THE INVENTION It is known to produce permanent magnet alloys and magnets made therefrom which contain rare earth elements, especially transition elements, ie, rare earth elements in combination with boron, and boron. This type of magnet is used in a variety of things, including electric motors, road speakers, imaging devices, and the like. As a result of the many unusual uses for these rare earth magnets, there is a need to produce many grades of magnets with the desired combination of magnetic properties for various specific uses. In this regard, it is desirable to retain a minimum of many molten alloy compositions in order to reduce the cost of the end product in which the magnet is used.

[0003] Conventionally, this is not possible. This is because the required combination of magnetic properties of many magnet grades required to satisfy the many unusual uses of these magnets has required the melting of a particular alloy composition for each required grade. In particular, it is common practice for this purpose to produce a specific alloy composition for each magnet grade produced. The alloy for each magnet grade has an alloy composition that has the necessary amount to obtain the desired properties in the magnet for the intended use. The manufacture and inventory of alloys of properties for each magnet produced significantly increases the cost of the magnet and the product in which it is used.

[0004]

SUMMARY OF THE INVENTION It is a first object of the present invention to provide a method for producing rare earth element containing permanent magnets, in which different grades of permanent magnets are used for each grade of magnet. It will be manufactured without requiring the manufacture of a particular alloy. A more specific object of the present invention is to provide a method for producing a rare earth-containing magnet,
The desired combination of magnetic properties may be varied by a method that involves blending multiple batches of particles of different permanent magnet alloy compositions to obtain a final magnet composition that will produce the desired combination of magnetic properties. Will be varied to produce the same magnet grade.

[0005]

According to the present invention,
The method reduces the selected grade of rare earth-containing permanent magnet by producing multiple particle batches of the rare earth-containing permanent magnet alloy, with each batch having a different chemical composition and different permanent magnet properties. Offering to manufacture.

[0006] The batches are blended in varying amounts to obtain a mixture of particles each having a different composition selected. The different compositions chosen differ from the permanent properties of the permanent magnets produced from each batch when processed to obtain permanent magnets,
It has been determined that each of the other mixtures will exhibit a selected combination of different permanent magnet properties.

Accordingly, one of these mixtures is processed in a conventional manner, resulting in the desired selected grade of rare earth-containing permanent magnet. Processing will include sintering. For compounding multiple particle batches, this will increase the intrinsic coercivity for the desired grade of magnets produced from the compounded particle batch, and correspondingly reduce remanence and energy product (and vice versa). ) Will be achieved by a method which includes selectively increasing the heavy rare earth elements of the resulting mixture.

[0008] At least one of the permanent magnet alloys of the particle batch preferably has a heavy rare earth element and a light rare earth element. The heavy rare earth element will be Dr and the light rare earth element will be Nd. Heavy rare earth elements Ho and Tb will also be present.

[0009] The plurality of particle batches may be of a composition having a rare earth element content, a transition metal and boron. The total rare earth element content is 50% or more of the total rare earth element content of Nd, Tb, Ho.
And up to 15% of at least one heavy rare earth element of Dy
5 to 40%, and 30 to 100% of all transition elements
Fe, total transition element content 40-75% in Co up to 20%,
0.8 to 1.5% of B, Al, Cu, Ag, Ga, Sn, Nb,
Contains at least one of W, Mo, Cr, V, Ti and Zn up to 20%. Each batch will have a different rare earth content and different permanent magnet properties.

[0010] Perhaps two batches of particles will be used in the formulation to obtain a particle mixture. When a two-particle batch is used in the formulation, one particle batch has a heavy rare earth content of up to 7% and the second particle batch has a 4-15%
Heavy rare earth element content. The heavy rare earth element content will be Dy, Tb or Ho. Each of these will have the same or varying amounts of the elements noted above.

When a three-particle batch is used for compounding,
The total rare earth content of the batch will be 26-32% with heavy rare earth contents up to 7%. The second batch of particles is 7
% Will have a total rare earth content of 30-34%. And the third batch of particles is 4
With a heavy rare earth content of １５15%, it will have a total rare earth content of 30-36%.

[0012]

DETAILED DESCRIPTION OF THE INVENTION Sintered magnets were made by conventional powder metallurgy processes from either cast ingots or spray particles. A predetermined alloy composition is melted in an inert gas atmosphere and the melt is poured into a metal mold and a cast ingot is made or otherwise sprayed onto the powder by use of an inert gas. In ingot formation, the ingot is coarsely ground. In both methods, coarse or atomized particles will be exposed to a hydrogen atmosphere for hydrogen repellency. The coarse hydrogen repellent particles are further broken down into fine particles, as by a attritor, to a particle size of about 1 to 20 microns. The microparticles are magnetically arranged and shaped.

The resulting molding is then 900 to 1
Sintered at a temperature of 200 ° C and aged at 400-700 ° C. The completely dense magnet obtained in this operation is then machined to the final shape and coated with a corrosion resistant layer. With this common method, magnets are generally prepared directly from a single alloy. No matter how a single alloy is prepared,
Inventory of specific alloys, each corresponding to a specific grade, is manufactured and stocked for magnet manufacture. According to the invention, a plurality of alloys and two particularly preferred alloys are prepared,
A variety of alloys are obtained which are compounded and suitable for the desired grade of the desired permanent magnet, each showing a different combination of magnetic properties suitable for use in the manufacture of a particular end product.

[0014]

EXAMPLES Two alloys were prepared in a vacuum induction melting furnace and atomized into a powder. Table 1 shows the composition of these alloys.
(% By weight).

[0015]

[Table 1]

The alloys in Table 1 were hydrogenated and jet milled into powders having an average particle size of 1-5 microns. The milled powder was formulated in a predetermined ratio as shown in Table 2.

[0017]

[Table 2]

The formulation was placed in a rubber mold, magnetically aligned, and cold isostatically pressed. The pressed compact was sintered in a vacuum furnace at 1050 ° C. for 1.5 hours and aged at 520 ° C. for 1 hour. The magnetic properties of these formulations are shown in Table 3.

[0019]

[Table 3]

As shown in this table, many grades of magnets are generated by blending two master alloys A and B. The magnetic properties are also shown in FIGS.
Assigned to Dy content. As shown in Table 3 and FIGS. 1 and 2, the Dci and TRE contents increased,
Increases almost linearly, and Br and BH _max decrease almost linearly. This shows that by blending these two alloys, various grades of magnet are formulated and made within certain (upper and lower) limits. In other words, many magnet grades can be made with only two master alloys. Therefore, the master alloy inventory can be reduced from many alloys to two, corresponding to the number of magnet grades produced. This significantly reduces inventory costs and improves production efficiency.

It is also noted that magnets from the formulated alloys show Br and BH _max slightly higher than expected (or a single alloy), but their Hci are consistent with the expected values. ing. Thus, magnets resulting from the blending of two master alloys exhibit equal or improved magnet properties compared to magnets made from a single alloy. The term grade as used herein refers to the chemical composition of the final magnet with selected and defined magnet properties. As used herein, all percentages are weight percentages unless otherwise indicated. The following general abbreviations are used here: Br remanence Hci intrinsic coercivity BH _max maximum energy product Tc Curie temperature TRE All rare earth elements

[Brief description of the drawings]

FIG. 1 is a graph showing that as the Dy content and total rare earth element content increase, the intrinsic coercivity increases almost linearly and the remanence decreases almost linearly. FIG.

FIG. 2. As the Dy content and the total rare earth content increase,
FIG. 4 is a similar graph showing that the energy product decreases almost linearly.

Continued on front page (72) Inventor Floyd E. Camp United States, Pennsylvania 15085, Trafford, Jennie Court 102 (72) Inventor William B. Eisen USA, Pennsylvania 15228, Pittsburgh, Terrace Drive 1390 (72) Inventor Seve Gaifi United States, Kentucky 42701, Elizabethtown, Oak Meadow Drive 2024

Claims (21)

[Claims] 1. A method for producing selected grades of rare earth-containing permanent magnets, the method comprising: preparing a plurality of rare earth-containing permanent magnet alloys in batches of particles each having a different chemical composition and different permanent magnet properties. When producing a batch of particles and blending the batch in varying amounts to obtain a mixture of particles with different compositions selected and processed to produce a permanent magnet,
The particle mixture differs from the permanent magnet properties of permanent magnets made from each of the plurality of individual particle batches, each exhibiting a selected combination of different permanent magnet properties from the other mixture, and having a selected composition. A method comprising processing one of the mixtures and producing therefrom a selected grade of rare earth-containing permanent magnet. 2. The method of claim 1 wherein at least one of said permanent magnet alloys of said particle batch comprises heavy rare earth elements and light rare earth elements. 3. The method of claim 2 wherein said heavy rare earth element comprises Dy and said light rare earth element comprises Nd. 4. The method according to claim 1, wherein the plurality of particle batches are blended and the particle mixture with the heavy rare earth element selectively increased to obtain increased intrinsic coercivity and reduced remanence and energy product and vice versa. 4. The method of claim 2 or claim 3, wherein 5. The method of claim 2, wherein said plurality of particle batches comprise two rare earth-containing magnetic alloys, one of said particle batches having a higher rare earth content than the other of said particle batches. 6. The method of claim 3 wherein said rare earth content further comprises at least one heavy rare earth element of Dy, Ho and Tb in combination with said Nd. 7. The method of claim 2, wherein at least one of said plurality of said permanent magnet alloys of a particle batch comprises Nd, Fe and B. 8. The method of claim 7, wherein said at least one of said permanent magnet alloys further comprises Dy. 9. A method for producing selected grades of rare earth elements, transition metals and boron permanent magnets, the method comprising:
A plurality of particle batches of rare earth elements, transition metals and boron permanent magnet alloys, each of which, in weight percent,
25-40% total rare earth content, up to 15% of at least one heavy rare earth element of Ho, Tb and Dy, total transition element content 4
0 to 75%, Fe is 30 to 100% of the total transition element content, Co is up to 20%, B is 0.8 to 1.5%, Al, Cu, Ag,
Up to at least 20% of at least one of Ga, Sn, Nb, W, Mo, Cr, V, Ti and Zn, and each of the batches has a different rare earth content and different permanent magnet properties, blending the batches in varying amounts And obtaining a mixture of particles having different selected compositions and processing to produce permanent magnets, unlike the permanent magnet properties of permanent magnets made from each of the plurality of individual particle batches, and A method comprising displaying a selected combination of permanent magnet properties different from the mixture, processing one of the mixture having the selected composition, and producing therefrom a selected grade of rare earth-containing permanent magnet. 10. At least one of said permanent magnet alloys of said particle batch comprises at least one of said heavy rare earth elements Ho, Tb and Dy.
The method of claim 9 comprising: 11. The method of claim 10, wherein said heavy rare earth element comprises Dy and said light rare earth element comprises Nd. 12. The particle mixture wherein said plurality of particle batches are blended and said heavy rare earth elements are selectively increased, said particles having increased intrinsic coercivity and reduced remanence and energy product. And the converse is obtained.
the method of. 13. The method of claim 1, wherein said plurality of particle batches comprise two rare earth-containing permanent magnet alloys, one of said particle batches having a higher rare earth element content than the other of said particle batches.
0 method. 14. The method of claim 10, wherein said rare earth content further comprises at least one of Dy, Ho and Tb in combination with said Nd. 15. The method of claim 10, wherein at least one of said plurality of said permanent magnet alloys of a particle batch comprises Nd, Fe and B. 16. The at least one of the permanent magnet alloys further comprising:
16. The method of claim 15, comprising Dy. 17. The method of claim 1, 2, 9, or 10, wherein said plurality of particle batches is two or more. 18. The method according to claim 18, wherein said plurality of particle batches comprises one particle batch having a heavy rare earth element content of up to 7% and 4-15%
2. A second batch having a heavy rare earth element content of
Method 7. 19. The method of claim 18, wherein the heavy rare earth element is at least one of Ho, Dy and Tb. 20. The method according to claim 1, wherein the plurality of particle batches has a total rare earth element content of 26 to 32% with a heavy rare earth element content of up to 7%, a total rare earth element content of up to 7% with a heavy rare earth element content of 30%. A second particle batch having ~ 34% and a total rare earth element content of 30-3 with a heavy rare earth content of 4-15%
16. The method of claim 15, comprising a third batch of particles having 6%. 21. The method of claim 1, wherein said processing comprises sintering.