JPS5822350A - Rare earth metal-cobalt permanent magnet - Google Patents

Abstract

PURPOSE:To improve a magnetic property, by preparing a Sm-Co-Cu-Fe-V-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:A Sm-Co-Cu-Fe-V-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 0<U<0.2, 0<V<0.5, 0<W<0.1, 0<X<0.05, 0<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*Cotvll crystals. To be more specific, Sm-
Co-Cu-Fe-V-C-M (M is 5s8e1Te
%Ce1PbsCdSBS, which indicates at least one type of Si, will be followed hereinafter. ) When melting and casting alloys,
Due to the effects of leg element C and the special element MO, the casting 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, and then crushed and formed in a magnetic field. This relates to a permanent magnet that has been scratched by a binder and has strengthened its bond.

The object of the present invention is to
In order to improve the magnetic performance of an alloy made of M, it is necessary to make the cast structure of an alloy ingot into columnar crystals as much as possible.

We are Sm-C under Japanese Patent Application No. 55-3226.

-C:U-Fe-Zr system, and when the alloy ingot is made into a columnar crystal, it has been shown that the magnetic performance of a magnet using this alloy is significantly improved compared to equicrystalline and chilled crystals. The present invention shows that the same effect can be obtained even if the columnar structure is increased by adding carbon C and special element M to the Sm-C0-Cu-F/-V alloy. It is something.

The present invention produces a magnet by subjecting a cast ingot mass to IT heat treatment, crushing it, mixing it with a binder, molding it in a magnetic field, and bonding and strengthening the binder. It is extremely effective in improving the performance of resin, metal, or ceramic bonded magnets. In other words, the process before pulverization is the same as for cast magnets, and the crystalline state of the cast ingot is used, so the columnar crystals that provide the above-mentioned high-performance magnetic properties are combined with carbon C added in a small amount to the cast ingot. It is possible to obtain a high-performance magnet by producing as much of the special element as possible due to the MO effect.

Generally, when molten metal is poured from a crucible into a mold, solidification begins at the casting walls. This is explained by the fact that an embryo (6 buds) in contact with a solid foreign material has a smaller energy μ barrier to stable nucleation than a book floating in a melt without contact. . Crystals formed on the casting wall grow into the molten metal while competing with neighboring crystals. As shown in Fig. 1, the region of intensive growth of crystals in the outermost layer of the ingot is called the chill layer. Since crystals have anisotropy in growth rate, crystals whose maximum growth rate is parallel to the direction of heat flow grow preferentially, suppressing the growth of adjacent crystals. During crystal growth, the closer the preferential orientation is to the heat flow, the fewer the crystals will survive for a longer time, and as a result, other crystals will be weeded out, and the number of crystals will decrease as they move closer to the inside of the ingot.One condition for the formation of columnar crystal bands is Once arranged, the columnar crystal bands will collide with each other *tii will be completed, but
Normally, as shown in Figure 1, isocrystals are formed inside a single columnar crystal.The main cause of isocrystals was not well known in the case of monographs, but now the casting wall is cooled and purified on the surface of the molten metal. It has become clear that the crystals released are liberated and become free crystals, and these free crystals form equicrystals (A, 0hn
o, T, Motegi and H,5oda:T
rans, l5IJ, 11 (1971) 1B).

A magnet using a 7-component alloy of the 8m-Co-Cu-Fe-V-CM system is called a precipitation hardening type or a two-phase separation type magnet. This is because a different phase is precipitated in the ma)9x.
The 0-line magnet, which is used for magnetic hardening, is initially Sm
-Co-CuS elemental alloy, which has been widely developed since it was first magnetized with a composition mainly using Sm and Co1y crystals. -When replaced with CotF@, saturation magnetization reaches a certain amount 4πIs 8m, (Co 1-x Fez), the crystal exhibits uniaxial ease in the range where the
Indicated by y, X is in the range of Ω to 0.6. This fact does not change even if a certain amount of CO is substituted for Cut.

When V is further added to Sm, (CoCuFe), etc., the magnetic performance is greatly improved even if the amount of (■) is very small. In other words, by adding ■, even if the amount of Cu decreases or the amount of iron decreases to ◆, a sufficient coercive force I Hc can be obtained as a practical magnet, making it possible to create a magnet with a high energy product.
l became possible.

As mentioned above, in this alloy, it has been revealed that among the chill crystal zone, columnar crystal zone, and equicrystalline zone, the columnar crystal zone is the most suitable for making into a magnet. In addition, Amano ingots, in which small amounts of carbon C and special element M are added to the alloy to increase the columnar crystal zone in the ingot, are superior to ingots cast under the same conditions. Now, an example will be explained using a resin head type rare earth edge fi/) magnet. This magnet is made from a magnetic alloy using the method shown in FIG. When we use exactly the same manufacturing methods to make magnets from equicrystalline alloys, columnar crystal alloys, and chill crystal alloys, the columnar crystal alloys exhibit saturation magnetization.

It was found that all performances, such as 4πII% coercive force iHc, bHc, and hysteresis loop squareness, were excellent. Conversely, equicrystalline alloys and chilled crystalline alloys are inferior in performance. In addition, ingots cast under the same conditions but 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 the columnar crystal zone is increased by compound addition of .

Since the crystals of the columnar crystal base metal are aligned, it can be used as a magnet and has good orientation in the uniaxial direction during travel. It is also believed that this alloy is more sensitive to precipitates formed during heat treatment than other alloys. This improves the squareness of the Hinuteli V.

In addition, the crystal structure of the precipitate, iH
It is thought that it is formed in a direction that greatly increases c.

Therefore, it is important to produce a good magnet by making the chill crystals near the casting wall into columnar chill crystals and the other parts into columnar crystals.・The chill crystal zone in the entire alloy is small. Therefore, what is important in manufacturing is to prevent equicrystalline zones and increase the ratio of columnar zones.
gm-Co-Cu-p*-V alloy with carbon C and 8.
Se, Te.

By casting with trace amounts of Ces Pb, Cd, and Bts si cape added, oxides and nitrides that promote the formation of crystallization from the melt are wrapped in electrides, sulfides, etc., and this effect is achieved. The inactivated carbon C1 special element M is combined with oxygen, nitrogen, etc. in the melt, reducing the generation of oxides, electrified substances, etc. that become nuclei for crystal formation, and forming homocrystals. is suppressed as much as possible.

In this case, the effects are not necessarily the same depending on the added elements, but the roles they play in promoting columnar crystals are the same. In terms of composition, columnar crystallization is expected to have the most effect.
When expressed as MY)z, o < u < Q, s The preferred composition range for obtaining a high-performance magnet is 0 (u ((L 2 0 (v ((L 5 0 6,5 (z (9°0). This is the same as the composition range shown in the claims.The reasons for limiting the components and composition range will be described below.

In this alloy system and its composition range, Sm-C0 yarn is basic. Cu is added to obtain coercive force in Sm, COl, and type alloys, and by adding Cu, i
Hc improves. However, 4πIa decreases. Therefore, as a practical magnetic material, Sm(Co1-uCuu)
The value of U in z is (limited to L2. The value of 2 is 5
(z (When IIL is between 5 and 5, the Sm-Co alloy separates into SmCo, type compound and Sm, Co1. type compound. The value of 4πIs is 20% higher for Sm, Co1y.
Therefore, in order to realize a high 4π engineering 8, 2 is 6
．． 5 or more is desirable. On the other hand, when 2 becomes 90 or more, iH
This is not preferable because e is significantly reduced and a large amount of Co--Fe phase is produced, which impairs the squareness of the hysteresis micrometer. (2) significantly lowers the 4π■8 of the alloy, so if more than L1 is added, there is no point in increasing Fe and reducing Cu to increase 4πIa.

As the amount of C increases, 4πI8 and iHc decrease, so the upper limit was set at αo5 in consideration of this limit. The effect of M varies depending on the additive element, but 4πII and iHc decrease when mass-marketed, so the upper limit was set at α1 in consideration of this limit. These numbers indicate the total amount of compound additives, and the ratio is not particularly specified.

The binder may be a variety of polymers such as epoxy, phenol, rubber, polyester, etc. or a metal binder, preferably a low melting point alloy having a melting point of 400'O or less.

The present invention will be explained below according to Examples.

Example 1 Sm after casting (CoalCuaayFeassVaaz
The raw materials are mixed to have a composition of CaotS (L(11) Kame!), and a total of 1 to 9 alloys are melted in an Ar gas atmosphere using a high frequency furnace to form an iron alloy as shown in Figure 3. The molten metal was poured into a mold at a temperature of 1550'O, and the molten metal cooled mainly from the side walls, forming the structure shown in Figure 1. ◎Figure 1 shows the structure when the ingot is cut at the center. In these parts, the chill layer is
Let B be the single columnar structure, and C be the equiaxed edge. Cast ingots were cut from parts A, B, and 0 of the alloy ingot, and resin-bonded magnets were produced according to manufacturing method 1 shown in FIG. The solution treatment was carried out at 1150'O for 2 U hours, and the aging treatment was carried out at 810'O for 16 hours in an argon atmosphere. Magnet fine powder pulverized to an average particle size of 10μ by the POLMI V method and EBOKI V resin 1.8 wt as a binder.
% was kneaded. This kneaded mixture was press-molded in a 16KG magnetic field, and a suitable amount of heat was applied to the molded body to harden the resin (kier treatment) to complete a magnet. The results are shown in Table 1. As can be seen in the table, the magnetic properties obtained from the columnar crystal bands in part B are much better than those obtained from the equiringous bands in part 0. Although the 1,000-μ crystal band in part A is lower than that in part B, it is better than part 0.

Table 1 However, SQ is an index indicating the rectangular prism of the hysteresis loop, and is given by 5Q-Hk/iHc. Hk is (L9
This is the magnitude of the magnetic field given by Br. From these results,
It became clear that the columnar crystal part in part B had the best performance. The chill crystal zone a in part A is generated only in the vicinity of the casting wall, and is very small in the whole ingot. The key is to develop From the occurrence situation of part A, part A used in this example contains:
It seems that a certain amount of columnar crystal B is included.

Example 2 In the same manner as in Example 1, resin-bonded magnets were manufactured from alloys having the compositions shown in Table 2. However, the solution treatment was carried out for 20 hours at the most appropriate temperature between 1120° and 1180°0.

Table 2 This example was carried out on an ingot of B, 0 parts.

The results are shown in Figure 4. Even if the amount of Fe increases, columnar crystal zone B provides better magnetic performance. For this,
It has become clear that even if the amount of FeO is increased to a certain extent, a certain degree of iHc can be obtained.0 Example 3 In exactly the same manner as in Example 2, a resin-bonded magnet was manufactured from an alloy having the composition shown in Table 3. The results are shown in Figure 5. S m-
, (CoCuFeVCM)sy type alloys, iHc decreases as the amount of CuO decreases, but in columnar crystals, iHc decreases to low Cu compositions compared to isometric
It can be seen that a high value of Hc can be obtained. In addition, the columnar crystal portion has better squareness.

Table 3 Example 4 In exactly the same manner as in Example 2, resin-bonded magnets were manufactured from alloys having the compositions shown in Table 4. The hot water temperature during alloy casting is 1600"
It is 0. The cast ingot has a cross-sectional macrostructure as shown in FIG. The proportion of the columnar structure of B was approximately 55% in alloy shop 1, 80 to 87 inches in alloy shops 2 to 4, and 65 to 75 in alloys 45 to 6. The proportion of columnar structure was estimated by observing the cross section of the ingot under a microscope and using the Metssie method.

Table 4 The results are shown in Table 5. As can be seen from Table 5, the one with the most cylindrical and columnar structures has the best magnetic performance. In this way, carbon C and 518eqTeSCeSP are included in the alloy composition.
By adding a special element M such as b-Cd-BisSi,
It can be seen that the magnetic performance is improved by promoting the columnar structure as much as possible.

Table 5 Example 5 A resin-bonded magnet was manufactured using the alloy having the composition 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, by adding small amounts of carbon C, S, Se, Te, C6% Pb5CdBt, St, etc. to the Sm-Co-Cu-Fe-V alloy, the columnar crystallization of the alloy ingot is further promoted, and the resin , the performance of metal- or ceramic-bonded SIMtCOtv type magnets has been improved.

The high performance magnet of the present invention has a wide range of industrial applications such as step motors for watches, micro speakers, coreless motors, and magnetic sensors.

[Brief explanation of the drawing]

FIG. 1 is a cross section of an incott cast into a mold, taken along the center of the mold. A, B, and C represent a chill layer, a columnar layer, and an equiaxed layer, respectively. D is the cross section of the mold O. Figure 2 shows the manufacturing process of the resin-bonded magnet. In FIG. 5, all zero wall thicknesses showing iron molds are 45-. The unit of length is -O.
In the composition of vVa, ozc taxes (Lot) at, the magnetic performance of the resin-bonded magnet is shown when changing ■. FIG. 5 shows Sm(Coa7se-ucuuFe Nz
Goose VCLo2sCCLogSα01)! The magnetic performance of the resin-bonded magnet is shown when U is varied in the composition of Lm. Applicant: Shikiwa Seikosha Co., Ltd. Agent Patent Attorney Mogami No. 21-1. −／

Claims (1)

[Claims] Samarium (Sm), cobalt (CO), copper (Cu),
Iron (Fe), Panadium (V), Subelemental (C), and M
(M is sulfur (S), selenium (Se), TeA/~(T
e), cerium (Ce), lead (pb), cadmium (C
d), bismuth (Bi), silicon (81)], whose composition has a compositional formula using an atomic ratio, 8m(Co1-u-v-w-x-YCuuFevVwc
When expressed as xMY)z, the composition range is 0〈u〈α2 0<v However, a rare-earth covafi/) permanent magnet is characterized in that it is an alloy mainly composed of SmtCotvll crystals, and the macrostructure of the ingot at the time of casting is mainly a columnar structure.