JPH0316762B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an alloy for permanent magnets mainly containing Fe and rare earth elements, particularly to an Fe-BR alloy for permanent magnets. Permanent magnet materials have been known as one of the ferromagnetic alloys. Permanent magnet materials are extremely important electrical and electrical components used in a wide range of fields, from various household appliances to peripheral terminals for large computers.
It is one of the electronic materials. In recent years, with the demand for smaller size and higher efficiency of electrical and electronic equipment, permanent magnet materials are required to have even higher performance. Current typical permanent magnet materials are alnico, hard ferrite, and rare earth cobalt-based magnet materials. With the recent instability in the raw material situation for cobalt, the demand for alnico magnet materials containing 20 to 30% by weight of cobalt has decreased, and inexpensive hard ferrite, whose main component is iron oxide, has become the mainstream magnet material. It became. On the other hand, rare earth cobalt magnet materials contain 50 to 65% by weight of cobalt and use Sm, which is not contained in rare earth ores, so they are very expensive, but they have better magnetic properties than other magnet materials. Because it is much more expensive, it has come to be used primarily in small, high-value-added magnetic circuits. In order for magnetic materials using rare earth elements to be used in large quantities and at low cost in a wide range of fields, it is necessary to
It is necessary that it does not contain expensive cobalt and that the main component is a light rare earth metal, which is contained in large amounts in ores. As one attempt at such a permanent magnet material, an RFe ₂ compound (where R is a symbol representing a rare earth element) was investigated. JJCroat has reported that an ultra-quenched ribbon of Pro. ₄ Fe _{0. 6} exhibits a coercive force of Hc = 2.8 kOe at 295 K (JJCroat Appl. Phys. Lett. 37 (12)
15 December 1980, pp. 1096-1098). after that
Even in _the ultra-quenched ribbon _{of Nd 0.4 Fe 0.6} at 295K
It is reported that the coercive force is Hc=7.45kOe (JJCroat Appl.Phys.Lett.39(4)15
August 1981, pp. 357-358). However, all of these ultra-quenched ribbons have low (BH)max (less than 4 MGOe). Furthermore, _N.C. Kuhn et al.
We found that when _an ultra-quenched _amorphous amorphous ribbon _{of 82La0.18)0.9Tb0.05La0.05 is annealed at} 627 _℃ , Hc reaches as _high as _9kOe (Br=5kG). However, in this case, the (BH)max is low due to the poor squareness of the magnetization curve (NCKoon et al., Appl. Phys. Lett. 39 (10),
1981, pp. 840-842). Also, L. Kabacoff et al. (Fe ₀ . ₈ B ₀ .
₂ ) An ultra-quenched amorphous ribbon with a composition of _1-x Pr _x (x = 1 to 0.3 atomic ratio) was prepared, and the amorphous alloy was
It has been reported that it has an Hc of about 50e. (L.
Kabakoff et al.: J.Appl.Phys.53(3) March 1982,
pp. 2255-2257). Most of the ultra-quenched ribbons listed above have light rare earths as their main components, but all of them have lower (BH)max than conventionally used permanent magnet materials, so they cannot be used as practical permanent magnet materials. It was difficult to do so. In addition, these ultra-quenched ribbons are not practical permanent magnets (body) that can be used in general speakers, motors, etc.
It has not been possible to obtain practical permanent magnets having arbitrary shapes and dimensions from these ribbons. The basic object of the present invention is to provide a novel alloy for practical permanent magnets that should meet such demands, particularly one useful as a magnetically anisotropic permanent magnet material. In particular, the purpose is to obtain a material mainly composed of Fe, which can effectively use resource-rich light rare earth elements as R. As such an alloy for permanent magnets, the present inventor first developed a ferromagnetic alloy that essentially requires specific rare earth elements, mainly Nd and Pr, and Fe and B in a specific ratio, particularly magnetic anisotropy. We have developed a completely new type of practical ferromagnetic alloy that has the ability to orient in a magnetic field, and filed an application by the same applicant as the present application (Japanese Patent Application No. 1983).
-145072 (Japanese Patent Application No. 59-246897 as a divisional application).
In this Fe-B-R ternary alloy, boron (B) is not added in the conventional way, for example, as an amorphous promoting element when creating an amorphous alloy or as a sintering promoting element in powder metallurgy. No, Fe-B-R
It is an essential constituent element of the R-Fe-B ternary compound that is magnetically stable above room temperature and has high magnetic anisotropy, which is the base of the ternary alloy. This alloy has a sufficiently high Curie temperature (approximately 300°C or higher) for practical use. The above-mentioned Fe-B-R ternary ferromagnetic alloy does not necessarily need to contain Co, and as R, light rare earths mainly consisting of Nd and Pr, which are abundant in resources, can be used, and Sm is not necessarily required. Without or Sm
Since there is no need to use mainly
Extremely useful. Moreover, the magnetic properties of the Fe-BR-based magnetically anisotropic sintered permanent magnet obtained using this ferromagnetic alloy are superior to those of hard ferrite magnets (coercive force iHc≧1kOe, residual magnetic flux density
Br≧4kG, maximum energy product (BH) max≧
4MGOe) In a particularly preferred composition range, it can exhibit an extremely high energy product equal to or higher than that of rare earth cobalt magnets. This Fe-B-R ternary ferromagnetic alloy is useful as such, but according to the present invention, other minor elements X (Cu, P,
Even if it is an alloy containing one or more of C and S, by limiting the content to a predetermined value or less, a permanent magnet, especially a magnetically anisotropic sintered body, which has magnetic properties equivalent to or better than hard ferrite. It has become clear that permanent magnets can be realized, which achieve the above-mentioned objectives. That is, the alloy for permanent magnets of the present invention is as follows. First invention of the present application: R in atomic percentage (R is Nd and
(one or two types of Pr) 8-30%, B2-28%, one or two or more types of element 4.0% or less), and the remainder substantially consists of Fe; Cu 3.5%, S 2.5%, C 4.0%, and P 3.5%. Second invention of the present application: R (R is Nd,
At least one of Pr, Dy, Ho, Tb, La, Ce, Gd, Y, and 50% or more of R is one or two of Nd and Pr) 8-30%, B2-28%, specified percentage below
One or more of the following elements X (excluding 0%) (however, if there are two or more types of element X, the total amount of
(below), and the remainder substantially consists of Fe; Cu 3.5%, S 2.5%, C 4.0%, and P 3.5%. Minor elements X such as Cu, S, C, and P are industrially
When manufacturing FeBR magnets, it is often contained due to raw materials, manufacturing processes, etc. For example, FeB
When used as a raw material, S and P are often contained, and C is often contained as a residue of an organic binder (molding aid) in the powder metallurgy process.
As for the influence of these small amounts of element X, according to the present invention, it has been recognized that the residual magnetic flux density Br tends to decrease as its content increases, as shown in FIG. As a result, the atomic percentage (the same applies below unless otherwise specified) is S2.5% or less, C4.0% or less, P3.5%
Properties equal to or higher than those of hard ferrite (Br about 4 kG) can be obtained when the total amount of S, P, and C is below 4%. In addition, as X, Cu is contained in a large amount in low-purity and inexpensive raw material iron, and Cu can be contained at 3.5% or less, and the total of X (S, C, P, Cu) is 4
% or less, it is possible to obtain Br equivalent to or higher than that of hard ferrite. Thus, the present invention is a Fe-B-R ternary alloy further containing a specific small amount of element X, and a novel Fe-B-R compound based on Fe-B-R.
-B-R-X alloy for permanent magnets is provided. Similar to the Fe-BR-R ternary alloy, the present invention
The Fe-B-R-X alloy for permanent magnets also exhibits a high anisotropic magnetic field and has the ability to align in a magnetic field, so it is particularly useful as a material for anisotropic magnets. According to the present invention, there is provided a novel high-performance permanent magnet material that has magnetic properties equivalent to or better than conventional hard ferrite, and is industrially extremely useful and can be substituted for Sm-Co magnet materials. The alloy for permanent magnets of the present invention is Fe-B-R-X system, does not necessarily contain Co, and does not necessarily contain Co.
As the material, light rare earths mainly composed of Nd and Pr, which are abundant in resources, can be used, and since Sm is not necessarily required or does not need to be mainly composed of Sm, the raw material is inexpensive and extremely useful. As is clear from the examples, the alloy of the present invention has the ability to align in a magnetic field. In the Fe-B-R-X permanent magnet alloy of the present invention, the composition range of R and B is basically the same range as the composition of the Fe-B-R ternary alloy (8 to 30% R, 2
~28% B). That is, as an anisotropic sintered magnet, if B is less than 2%, a coercive force iHc of 1 kOe or more cannot be obtained, and if B is more than 28%, the residual magnetic flux density Br of hard ferrite cannot be made to be more than about 4 kG. . If R is less than 8%, the coercive force cannot be increased to 1 kOe or more, and if R is more than 30%, it is undesirable because it becomes flammable, makes industrial handling and manufacturing difficult, and increases product cost. In this B and R range, the maximum energy product (BH) max of the anisotropic sintered magnet is hard ferrite (~
4MGOe). Further, in order to improve the temperature characteristics of the Fe-B-R-X permanent magnet of the present invention, a portion of Fe may be replaced with 50% or less of Co. Inclusion of Co has the effect of raising the Curie point of the Fe-B-R-X alloy. Furthermore, as a preferred embodiment of the present invention,
The range of Br7kG or more is S1.5% or less, C3.0% or less,
P2.0% or less, Cu2.3% or less, and S, C, P, Cu
If the total is 3.0% or less (X is 2 of S, C, P, Cu)
(if the number of seeds or more), each can be obtained. Using the Fe-B-R-X alloy of the present invention, practical permanent magnets can be manufactured in the same manner as the Fe-B-R alloy previously filed. For example, melting an alloy, cooling it,
For example, a practical high-performance permanent magnet can be obtained most effectively by casting, pulverizing the resulting alloy, and then shaping and sintering it to form an appropriate microstructure. The alloy for permanent magnets of the present invention does not matter its form,
It includes permanent magnetic materials in any form, including known forms such as ingots or powders. Rare earth element R in the alloy for permanent magnets of the present invention
is a rare earth element that includes Y and includes light rare earth elements and heavy rare earth elements, and one or more of them is used.
That is, this R includes Nd, Pr, La, Ce, Tb,
Dy, Ho, Er, Eu, Sm, Gd, Pm, Tm, Yb,
Lu and Y are included. R is usually Nd,
It is sufficient to have one or two types of Pr, but these
Other Dy, Ho, with Nd, Pr being 50% or more of R
At least one of Tb, La, Ce, Gd, and Y can be used as a mixture. In practice, a mixture of two or more types (Mitsushimetal, didymium, etc.) can be used for reasons such as convenience of availability. Note that this R does not have to be a pure rare earth element, and may contain impurities that are unavoidable in manufacturing (other rare earth elements, Ca, Mg, Fe, Ti, C, O, etc.) within the industrially available range. do not have. As described above, the present invention is extremely advantageous in that R that is industrially easily available can be mainly used. As B (boron), pure boron or ferroboron can be used, and as impurities Al, Si,
Those containing C or the like can also be used. The reasons for limiting the composition range of the alloy for permanent magnets of the present invention will be explained in detail with reference to Examples described below, but in particular, when the present invention is used most effectively, that is,
We selected a composition range that would provide magnetic properties equivalent to or better than hard ferrite when used as a magnetically anisotropic sintered permanent magnet. That is, the alloy for permanent magnets of the present invention contains 8 to 30% R, 2 to 28% B, and a predetermined percentage.
Hereinafter, X, the balance Fe (atomic percentage), coercive force
It can be an anisotropic sintered magnet that exhibits magnetic properties of Hc≧1kOe, residual magnetic flux density Br>4kG, and has a maximum energy product (BH) max equivalent to or higher than that of hard ferrite (about 4MGOe). Let Nd and Pr be the main components of R (i.e. 50% or more of Nd and Pr in all R), 11 to 24% R, 3 to 27
%B, X2.5% or less (Cu2.0% or less, S1.5% or less,
(C2.5% or less, P2.0% or less), the remaining Fe composition is the maximum energy product (BH) when made into an anisotropic sintered body.
max≧7MGOe, which is a preferable range. Most preferably, Nd and Pr are the main components of R (same as above), 12 to 20% R, 4 to 24% B, X2.0% or less (S1.0% or less, C2.0% or less, P1.5 %below,
The composition is Cu (1.0% or less), the balance is Fe, and the maximum energy product (BH) max ≥ when made into an anisotropic sintered body.
10MGOe, and (BH)max reaches a maximum of 25MGOe or more. A permanent magnet made using the alloy of the present invention exhibits good squareness (see FIG. 2), and as described above, within the preferred range, exhibits high magnetic properties comparable to rare earth cobalt magnets. Of the above-mentioned minor elements It is advantageous because the characteristics are secured. Although the inclusion of C slightly increases the sintering temperature, as mentioned above, it is advantageous in the manufacturing process because carbon from the organic binder commonly used in powder metallurgy does not have to completely disappear. . Furthermore, in the Fe-B-R-X alloy for permanent magnets of the present invention, Ti is 4.5% or less, Ni is 4.5% or less,
Bi5% or less, V9.5% or less, Nb12.5% or less, Ta10.5
% or less, Cr8.5% or less, Mo9.5% or less, W9.5% or less, Mn3.5% or less, Al9.5% or less, Sb2.5% or less,
Ge7% or less, Sn3.5% or less, Zr5.5% or less and
It may contain at least one type of Hf of 5.5% or less. These include those that can provide permanent magnetic materials with higher iHc, and are particularly suitable as permanent magnetic materials used in harsh environments. In addition to Fe, B, R, and X, the alloy for permanent magnets of the present invention includes Ca, Mg,
The presence of industrially unavoidable impurities such as O and Si can be tolerated. These impurities are often mixed in from raw materials or manufacturing processes, and the total amount is preferably 5% or less. In this way, the predetermined content of the minor element X is
It is extremely advantageous industrially because it allows the use of low-purity raw materials and can be manufactured at low cost.By controlling the small amount of element , a magnetically anisotropic sintered permanent magnet having a high energy product is provided with stable quality. Hereinafter, aspects and effects of the present invention will be explained according to examples. However, the embodiments and descriptions are as follows:
The present invention is not limited to these. <Example> The following materials were used as raw materials. After weighing the raw materials so that the atomic composition of the alloy for permanent magnets was as shown in Tables 1 and 2, the materials were melted in a high-frequency induction furnace and cast in a water-cooled copper mold. Various Fe-B-R-X alloys were produced using the following methods. Fe: Electrolytic iron with a purity of 99.9% by weight or more B: Ferroboron alloy (contains 19.4% by weight of B) and pure boron with a purity of 99.9% by weight R: 99.7% by weight or more in purity S: 99% by weight or more in purity P: Ferro P (P26 (Contains .7% by weight) C: Purity of 99% by weight or more Cu: Electrolytic Cu with purity of 99.9% by weight or more Permanent magnet samples are made using this alloy as follows (1) Pulverized with a 1Kg ingot stamp mill up to 35 mesh through Coarsely pulverize, then finely pulverize into crystal particles (1 to 30 μm) that can be oriented in a magnetic field for 3 hours using a ball mill; (2) Orientation and shaping in a magnetic field (10 kOe) (pressurized at 1.5 ton/cm ² ); (3) ) Sintering After sintering in an inert gas atmosphere at 1000 to 1200°C or in vacuum for 1 to 2 hours, let it cool. The iHc, Br, and (BH)max of the above samples were measured, and the results for representative samples are shown in Tables 1 and 2. In Tables 1 and 2, the sample
Samples Nos. 1 to 36 are examples of the present invention, and samples Nos. C37 to C40 are comparative examples. In addition, when the properties of the alloy (powder state) after being finely pulverized in the production process of the permanent magnet sample were investigated, it showed a high value of iHc1kOe or more. Furthermore, by changing the blended raw materials in a magnet alloy composition consisting of 15 atomic % Nd, 8 atomic % B and the balance Fe, small amounts of elements X (P, C, S,
P, C, S,
Figure 1 shows the relationship between the amount of Cu and the residual magnetic flux density of an anisotropic sintered permanent magnet. (If two or more types of Although it decreases over time, C4%, P3.5%, S2.5%, Cu3.5
% or less, Br is 4kG (hard ferrite Br
It can be seen that greater characteristics can be maintained (equivalent to ). Further preferred ranges can be clearly read from Tables 1 and 2 and FIG. 1 by partitioning Br in steps of 7 kG. The alloy for permanent magnets of the present invention is the base thereof.
In the Fe-B-R ternary system, 8-30% R, 2-
It is recognized that in the entire range of 28% B and the balance Fe (atomic percentage), the presence of element X at a predetermined % or less is allowed. Next, as a representative example, Fig. 2 shows that P, C, S, and Cu as minor elements X each contain 0.5 at%.
Nd ₁₅ Fe ₇₆ . ₅ B ₈ P ₀ . ₅ (Sample No. 1), Nd ₁₅ Fe ₇₆ . ₅ B ₈ S ₀ . ₅
(Sample No. 17), Nd ₁₅ Fe ₇₆ . ₅ B ₈ C ₀ . ₅ (Sample No. 9) and
The initial magnetization and demagnetization curves of a sintered magnet made of Nd ₁₅ Fe ₇₆ . ₅ B ₈ Cu ₀ . ₅ (Sample No. 25) alloy are shown. All exhibit high squareness useful as permanent magnet materials.

【table】

[Table] As detailed above, the present invention provides novel Fe-B-
R-X ferromagnetic alloy, i.e., Fe-B-R, which is mainly composed of Fe and does not require Co, and R is mainly composed of rare earth elements (Nd, Pr), which are rich in resources and easy to obtain industrially. It is a compound-based alloy for permanent magnets, and is particularly useful as a magnetically anisotropic permanent magnet material. By using this, it has become possible to provide Fe-B-R-X magnetically anisotropic sintered permanent magnets that have magnetic properties superior to hard ferrite and can be substituted for Sm-Co materials. It has extremely high industrial value. In particular, its advantages as a permanent magnet material are extremely significant when compared with conventional Sm-Co based materials in terms of its main constituent elements. In addition, since it allows the use of raw materials with low purity and can be produced at low cost, it is extremely advantageous industrially and can also contribute to increasing practical value.

[Brief explanation of the drawing]

Figure ₁ shows the residual magnetization Br ( _vertical axis _kG ) versus the atomic percentage _a of Figure 2 is a graph showing the initial magnetization/demagnetization curves for samples No. 1, 9, 17, and 25 of typical examples of the present invention (horizontal axis: magnetic field kOe, vertical axis: magnetization kG). ), respectively.

Claims (1)

[Claims] 1. R (R is one or both of Nd and Pr) 8 to 30%, B2 to 28%, below specified % (0
%) of one or more types of element X (however, when there are two or more types of element X, the total amount of X is 4.0% or less),
An alloy for permanent magnets, characterized in that the remainder essentially consists of Fe; Cu 3.5%, S 2.5%, C 4.0%, and P 3.5%. 2 R in atomic percentage (R is Nd, Pr, Dy, Ho,
At least one of Tb, La, Ce, Gd, Y,
and 50% or more of R is one or both of Nd and Pr)8
~30%, B2~28%, one or more types of element An alloy for permanent magnets, characterized in that the balance essentially consists of Fe; 3.5% Cu, 2.5% S, 4.0% C, and 3.5% P.