JPS5822351A - Rare earth metal-cobalt permanent magnet - Google Patents

Abstract

PURPOSE:To improve a magnetic property, by preparing an Sm-Co-Cu-Fe-Ta-C-M alloy, whose composition defined by a special formula using atomic ratios is in a specified range, mainly composed of Sm2Co17-type crystal, and forming the macrostructure of the ingot during casting into a dendritic state as much as possible. CONSTITUTION:An Sm-Co-Cu-Fe-Ta-C-M alloy (M is one or more of S, Se, Te, Ce, Pb, Cd, Bi and Si) is cast. In this case, the alloy is mainly composed of Sm2Co17-type crystal, and its composition defined by the formula using atomic ratios is held in the range of O<u<0.2, O<V<0.5, O<W<=0.05, O<X<0.05, O<Y<0.1 and 6.5<=Z<=9. In addition, the macrostructure of the ingot during casting is formed into a dendritic state as much as possible. In this way, a permanent magnet excellent in its magnetic property is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a precipitation hardening magnet using Sm, Co□ type crystals. More specifically, Sm-Co
-Cu-Fe-Ta-C-M (M is 5SSe, Fes
Ce5Pbq Cds Bi, at least 1 of Si
Indicates more than one species. This notation will be followed below. ) During melting and casting of the alloy, due to the effects of the secondary element C and the special element M, the cast macrostructure of the alloy is made into columnar crystals as much as possible, and the alloy with many columnar crystals is heat-treated for magnetic hardening. ,after that,
This relates to a permanent magnet that has been crushed, formed in a magnetic field, and strengthened by a binder.

The object of the present invention is Sm-Co-Cu-Fe-Ta-
In order to improve the magnetic performance of an alloy made of C-M, it is necessary to convert the cast structure of the alloy ingot into columnar crystals as much as possible.

We are Sm-C in 11th Patent Application No. 55-5226.

-Cu-Fe-Zr alloy, it was shown that when the alloy ingot is made into columnar crystals, the magnetic performance of a magnet using this alloy is significantly improved compared to equicrystals and chill crystals.

The present invention shows that the same effect can be obtained by adding carbon C and a special element M to Sm-Co-Cu-Fe-Ta alloy to increase the columnar structure. be.

The present invention aims to improve the performance of resin-, metal-, or ceramic-bonded magnets by manufacturing magnets by heat-treating a lump of a cast ingot, pulverizing it, mixing it with a binder, molding it in a magnetic field, and strengthening the binding of the binder. It is extremely effective. In other words, the process up to pulverization is the same as for cast magnets, and since the crystalline state of the cast ingot is used, a small amount of columnar crystals that can obtain high-performance magnetic properties as described above are added to the cast ingot to create a ninth-order element. It is possible to obtain a high-performance magnet by producing as much C as possible due to the effects of C and the special element M.

Generally, when molten metal is poured from a crucible into a mold, it begins to solidify from the mold. This is explained by the fact that an embryo (6 buds) in contact with a solid foreign material has a smaller energy barrier to stable nucleation than an embryo floating in the melt without contact. Crystals formed on the casting wall grow into the molten metal while competing with neighboring crystals. The competitive growth region of crystals in the outermost layer of the ingot, as shown in FIG. 1, is called the chill layer. Crystals are rounded with anisotropy in growth rate, and crystals whose direction of maximum growth rate is parallel to the direction of heat flow preferentially grow by suppressing the growth of adjacent crystals. During crystal growth, the closer the preferred orientation is to the heat flow, the longer the crystals will survive, and other crystals will be weeded out.As a result, the number of crystals will decrease as they move into the ingot. When the columnar crystal bands collide and solidify, solidification is completed, but as shown in Figure 1, the main cause of 0-iso crystals, in which equicrystals are formed inside the columnar crystals, was previously unknown. However, it is now clear that nine crystals are formed on the casting wall or the cooled surface of the melt and become free crystals, and these free crystals form equicrystals (A, 0hno,
T6Mi5teg1 andH,5oda:Tran
a, l8IJ, 11 (1971) 18).

Magnets using a seven-element alloy of Sm-Co-Cu-Fe-Ta-C-M threads are called precipitation hardening type or two-phase separation type magnets. , for magnetic hardening. This system of magnets initially has g
It is an m-Co-Cu 5-element alloy, which has been widely developed since it was first made into a magnet with a composition mainly using 3m1CO1v crystals. It is known that when co is replaced with F, the saturation magnetization 4πIB increases up to a certain amount04
In the range where πIs increases, the crystal exhibits uniaxial eastropy as shown by s Sml (Co 1-xFe x) sv. It doesn't change even if you replace it.

When Ta is further added to Sml (Co Cu Fe ) tv, the magnetic performance can be greatly improved even if the amount of Ta is very small. That is, when Ta is added, Cu
Even if the amount of round iron is reduced, even if the amount of round iron is increased, sufficient coercive force i Hc can be obtained as a practical magnet, making it possible to create a magnet with a high energy product. It was revealed that among the cycrystalline, columnar, and equicrystalline zones, the columnar zone is the most suitable for making into magnets. Further, by adding a small amount of carbon C and special element M to the alloy to increase the columnar crystal zone in the ingot, the alloy is superior to an ingot cast under the same conditions.

An example will now be explained using a resin bonded rare earth cobalt magnet. This magnet is made from a magnetic alloy using the method shown in FIG. If we use exactly the same manufacturing method to make magnets from equicrystalline alloy columnar crystal alloy and chill crystal alloy, we find that columnar crystal alloy has a saturation magnetization of 4πI8, a coercive force of 1Hc, bHc, or the squareness of the hysteresis loop. It was found to be excellent in terms of performance. Conversely, equicrystalline alloys and chilled crystalline alloys are inferior in performance. Ingots cast under the same conditions and with a small amount of carbon C and special element M added to increase the columnar crystal zone, and ingots without carbon C and special element M added. The performance is better when element M is added to increase the columnar crystallinity region.

Since the crystals of columnar crystal alloys are aligned, they have good orientation in a uniaxial direction when made into a magnet. In addition, in this alloy, the precipitates formed by heat treatment are thought to be more uniform than in other alloys, so the squareness of the hysteresis is improved.

In addition, the crystal structure and morphology of the precipitates are also l
This rounding is thought to be formed in a direction that increases the Hc well. This rounding process makes it possible to obtain good magnets by making this alloy into columnar chill crystals for the chi crystals near the casting wall and columnar crystals in other parts. It is important. Since the radiation dose in the entire alloy is small for chiμ crystals, what is important in manufacturing is to prevent equiringous bands and increase the ratio of columnar crystal bands. From this point of view,
By adding a small amount of C, 5bSesTe, Ce5Pb, Cd, BL, Sl, etc. to a 3m-Co-Cu-F@-Ta-based alloy and casting it, nucleation of crystallization from the melt is promoted. Oxides, nitrides, etc. are wrapped in expanded substances, sulfides, etc. to inactivate the effect, and carbon C1 special element M combines with oxygen, nitrogen, etc. in the melt to form crystals. The formation of uniaxial crystals is suppressed as much as possible by reducing the generation of oxides, nitrides, etc. that serve as nuclei. Although the effect of this additive is not necessarily the same depending on the added element, the role it plays in promoting columnar crystals is the same.In terms of composition, the most effective effect is expected from columnar crystal formation. This is the composition formula using the atomic ratio, Sm(Co1-u-v-v-xCuuFevTtvCx
Mr. <1lL1 &0(z(t.

It was confirmed that A more preferable composition range for obtaining a high-performance magnet is 0<u<12 0kuma<(L5 o(v(CLas O<c((LO5 0<Y<11 U5(z (t This is the same as the composition range shown in the claims.The reason for limiting the components and composition range to promote sales will be described below.

In this alloy system and its composition range, the Sm-C0 system is basic. Cu is added to obtain the coercive force in the 8m Co11 type shell.l) By adding sCu, lHc is improved. However, 4π work s decreases. Therefore, as a practical magnet material, 8m (Col-ucu
u) The value of U in z is limited to (L2. When the value of 2 is between 5 (z < 15), The value of 4 to 8 is 20' for Bm and Co1g.
It's expensive. Therefore, in order to achieve a high 4fIs, it is desirable that 2 be 65 or more.

On the other hand, when 2 becomes 9θ or more, iHe decreases significantly and a lot of C0-Fe phase comes out, causing hysteresis 95
/ μm This is undesirable because it impairs the squareness of the sp.
Since this gradually lowers the 4πIs of the base metal, if more than aOS is added, there is no point in increasing the 4πIs by increasing Fe and reducing Cu.

As C increases, 4πl5stHc decreases, so considering its limit, the upper limit was set at α05 ・M depends on the additive element) ◆ Although the effect varies, at a certain mass sale level, 4πI s s i He becomes Therefore, the upper limit was set to α1 in consideration of the ocular world.These indicate gold measurements of composite additions, and the ratio is sometimes not specified. .

A low melting point alloy with a melting point of 40 (1'0 or less) is preferable.

The present invention will be explained below with reference to Examples.

Example '1゜After casting Sm(Co(L59 Cu107 Feα5T
aα01 Cα02 Sα01) [The raw materials were mixed to have the composition of 2, and a total of 1kl of the alloy was melted in an Ar gas atmosphere using a high frequency furnace, and the hot water was heated to an iron mold as shown in Figure 3. It was cast at 1550°0. The molten metal was cooled mainly from the side walls, and had the structure shown in FIG. FIG. 1 shows the structure when the ingot is cut at the center. In these parts, the chill layer is human and the columnar tissue is B.
1 and A and B of the 0 alloy ingot whose peak axis structure is C.
The cast ingots of parts 0 and 0 were cut out, and resin-bonded magnets were produced according to manufacturing method 1 shown in FIG. Solution treatment is
24 hours at 1150°C, aging treatment at 800°C for 20 hours
Time went on in the Agon atmosphere. Evoki V resin t 8 wtlG as a binder was kneaded into fine magnetic powder that had been ground to an average particle size of 10 μm using a ball mill method. This kneaded mixture is press-molded in a 14KG magnetic field, and the resin is hardened by applying appropriate heat to the molded product (Kheer treatment).
9. Complete the magnet. The results are shown in Table 1. As can be seen from the table, the magnetic performance obtained from the columnar crystal zone of part B is very superior to that obtained from the equiringous band of part 0. Although the chill crystal band of part A is lower than that of part B, it is better than part 0.

Table 1 However, SQ means hysteresis! - An index showing the squareness of the square shape, and is given by 5Q-HK/iHc. HK is a9B on the 4πI-H demagnetization curve
It is the magnitude of the magnetic field given by r. From these results, B
It became clear that the columnar crystal part of the part had the best performance. The chill crystal zone in part A is formed only in the vicinity of the brim wall, and is ingo.

The most important thing in making ingots is how to suppress the formation of equiaxed grains and develop columnar crystals. Judging from the occurrence of part A, it seems that part A used in the ceramic example contains a certain amount of columnar crystal 840 part.

Example 1 In a similar manner to Example t, the composition Q shown in Table 2 was prepared.
Resin-bonded magnets were manufactured from the alloy. However, solution treatment is 1
Bake for 20 hours at the most suitable temperature between 120 and 111 O'O.

Table 2 This example was carried out on an ingot in the B1C section.

The result is the 4th Ii! Even though the amount of Fe is increased, better magnetic performance is obtained in the columnar crystal zone B shown in FIG. As a result, it has become clear that even if the amount of Fe is increased to a certain extent, a certain amount of iHe can be obtained. A magnet was manufactured and the results are shown in Figure 5 @ Sm (
In tv-type alloys (CoCu, FeTaCM), iHc decreases as the amount of CuO decreases, but in columnar crystals,
It can be seen that higher values can be obtained for 1HC up to low Cu compositions than those with equiaxed weight. In addition, the columnar mold part has better squareness.

Table 3: Resin-bonded magnets were manufactured from alloys having the compositions shown in Table 4 in exactly the same manner as in Example 2. The hot water temperature during alloy casting is 1650°
It is 0. The cast ingot has a macrostructure on the shooting surface as shown in FIG. The ratio of the columnar structure of B was approximately 6091G in alloy layer 1, 7$ to 85-1 in alloys A2 to 4, and 68 to 759G in alloys A5 to 6. The proportion of the columnar structure was estimated by observing the cross section of the specimen with a microscope and using the Metsu V-method.

Table 4 The results are shown in Table 5. As can be seen from Table 5, the one with the most columnar structures has the best magnetic performance. In this way, the base metal composition includes C, S, and Se.

It can be seen that the magnetic performance is improved by adding special elements M such as Te, Ce%Pbs, Cd%Bi, and Fii in combination to promote the columnar structure as much as possible.

Table 5 Practical side Resin-bonded magnets were manufactured using alloys having the compositions shown in Table 6 in exactly the same manner as in Example 2. The results are shown in Table 7.

Table 6 Table 7 As shown above, even if the value of 2 was changed, a magnet with sufficiently high magnetic performance could be obtained.

In this way, in the 5rn-Co-Cu-Fe-Ta alloy,
Subprime C and 8% Se, Tes Ces Pbt Cd.

By adding Bi, ST, etc. in combination, the columnar crystallization of the alloy ingot is further promoted, and the performance of resin, metal, or Cefmic bound 08m1CoB type magnets is improved. , step motor for watches,
It has a wide range of industrial uses such as micro speakers, coreless speakers, and magnetic sensors.

[Brief explanation of the drawing]

Figure 1 shows an ingot cast into a mold, cut vertically through the center. It is an O cross section. A, B, and C represent a chill layer, a columnar layer, and an equiaxed layer, respectively. D is a cross section of the mold. FIG. 2 shows the manufacturing process of the resin-bonded magnet. FIG. 5 shows a # type made of iron, and the wall thickness is all 1S-. The unit of length is -. Figure 4 shows Sm(Co(LIS?-VCu CLO
7Fe vTa aOICa (12S ao 1 )a
In the composition of t, the magnetic performance of the resin-bonded magnet during travel is shown by changing . Figure 5 shows 8m (Coa73-ucuFe(L22T)
In the composition of aα02C(LD2Sαa1)as, U
This figure shows the magnetic performance of resin-bonded magnets when changing . Applicant: Iwa Seikosha Co., Ltd. Agent Patent Attorney Mogami Figure 2

Claims (1)

[Claims] Samarifu (Sm), Koba/S/) (CO), copper (Cu
), iron (Fe), tank/I/(T a ) s l
e element (C), and M (M is sulfur (S), selenium (
Se), TeAzA/(Te), cerium (Ce), lead (
8m(Co -1-u -v -x-YCu u Fe
v Ta v CxMY ) z, and the range of travel time and composition is 0kuu<, 2 0 (v ((L 5 0〈W α05 0x α05 0 (y < CL 1 ts(z A rare earth cobalt permanent magnet characterized in that it is an alloy mainly composed of Sm and Co1y type crystals, which have a t.