JPS60224761A - Permanent magnet alloy - Google Patents

Abstract

PURPOSE:To obtain a highly efficient Ce-Nd-Pr-Fe-W-B permanent magnet alloy with low cost by specifying the atomic ratio of a rare earth element to the other element, and said respective ratios in a rare earth element group and the other element group. CONSTITUTION:In the Ce-Nd-Pr-Fe-W-B alloy, the atomic ratio of the rare earth element R to the other element M is denoted as (z) (z=atomic number of M/atomic number of R), the atomic ratio in the element R as R=Ce1-a-bNdaPrb, the atomic ratio in the element M is expressed as M=Fe1-x-yWxBy. In this case, the respective values are regulated to 0.05<=a<=0.8, 0.05<=b<=0.5, 0.03<=x<=0.3, 0.001<=y<=0.15, 3.5<=z<=9.0. By the alloy compsn., highly efficient plastic bond magnet and sintered magnet can be presented even by using inexpensive rare earth compound.

Description

Detailed Description of the Invention [Technical Field] The present invention relates to cerium (Co)-didymium (Dl)-iron (
The present invention relates to a low-cost, high-performance permanent magnetic alloy consisting of (Fe)-tungste/(W]-poro/(B) or chain thread as a main component. However, didymium is a common name for Nd-Pr alloy.

Table 1 shows the main types of magnets that have been put to practical use, classified according to their chemical composition and manufacturing method.

In Table 1, the ○ marks indicate those that are produced, and the x marks indicate those that are not produced. In the Japanese market, five types of magnets other than sintered alnico are produced. This ssi
These types of magnets account for more than 99% (1985) of the Japanese market in terms of shipment value and production weight, and when it comes to magnets, it can be said to be one of these. The reason why there are so many types of magnets is that each type has its own advantages and disadvantages, and is used depending on the specifications required for various applications. Let's list the advantages and disadvantages of these magnets. First of all, it is a sintered ferrite) FF1 stone, but this magnet is currently used in many IKs because it has the lowest unit price compared to other magnets (59,000 tons in Japan, estimated in 1985). . The unit price is isotropic and α5~
1 yen/2, and 2 to 5 yen/'/ for anisotropic, and the performance is IMGOe for isotropic when expressed in energy product (BH) max.
The degree of anisotropy is about 15 to 4.0 MGOe. In this way, although sintered ferrite magnets have low performance, they have an even greater advantage in unit price.

However, since they are originally ceramic magnets, they are hard, porous, and have poor impact resistance. It also has the disadvantage of being difficult to process into complex shapes. Glass bonded ferrite magnets are made to compensate for this drawback. These magnets, commonly called ferrite bonded magnets, have high toughness and workability, making them resistant to cracking and chipping, making it easy to create magnets with complex shapes. An isotropic magnet is (B H) m a
x == 0.5~1MGOa, unit price is about α6 yen/?
The anisotropic magnet has (BH)max=about 1.5 and the unit price is about 2-8 yen/V. The reason why the unit price of the anisotropic material is equal to or higher than that of sintered ferrite and its performance is lower is that it contains 40 to 50% of expensive engineered glass as a binder material at Vo1%. However, despite the disadvantages of high unit price and low performance of ferrite bond magnets, demand for anisotropic magnets is rapidly increasing. The reason for this is that the above-mentioned advantages are effective.

Next is alnico magnets, but before the advent of rare earth magnets, this was the only magnet available to obtain high magnetic flux density, and its production value was so large that it surpassed that of ferrite magnets. However, due to factors such as the small magnetic force iHc, the instability of cobalt prices, the ease of processing, and the emergence of rare earth magnets, demand continued to decline from around 1979, and finally in 1985. has been surpassed by rare earth magnets in terms of production value. This trend is likely to continue in the future. Finally, rare earth magnets began to be manufactured on a trial basis around 1970, and industrial production began around 1976. Production in Japan in 1976 was only 5to.
n, but after that it rapidly increased and in 1985 Vi29 D
It is estimated that ton was produced. The reason why rare earth magnets have grown so much is that their energy product is significantly higher than that of previous magnets (16 to 50 MGOp when sintered), which perfectly matches market needs. It will be done. However, the unit price is an order of magnitude higher than other magnets, at 40 to 50 yen/2. Furthermore, sintered rare earth magnets have the disadvantage of being very porosity and are prone to cracking and chipping, making them difficult to use. Trap plastic bonded cedar rare earth magnets overcome this weakness. For those manufactured by compaction, (BH)max=10-18MGO
a, and in this range it maintains an advantage over sintered magnets. In recent years, injection molding, extrusion molding, and ℃/cold technology have been applied to this magnet, making it easier to use and expanding its range of applications. However, since a binder is mixed in, the magnetic performance is inevitably limited, and the unit price is not actually lower than that of sintering, so the cost performance does not improve much.

Conventionally, to evaluate the cost performance of magnets, (
BH) maw (MGOe) divided by the unit price (yen/2) was used as an index for convenience, but when actually using a magnet, what is important is the energy product not only per weight but also per volume. The cost performance indicator should also be pressure per volume. Therefore, if the dense variation is ρ, then
It is best to set the index ID to ID:=(BH)max/(ρ4 unit price). This indicator also includes the five factors mentioned above.
I calculated the cost performance of 4@ magnets (-@2
Tables a, b).

Table 2 (-) Table 2 (b) As can be seen from this table, magnets with high cost performance (D) have low performance, and conversely, magnets with high performance have low cost performance. There is.

Therefore, in the conventional magnets, there has been a problem that there is no magnet whose performance is high enough to meet market requirements and whose cost performance is excellent.

〔the purpose〕

The present invention is intended to solve these problems, and its purpose is to provide a magnet with high performance and low cost.

〔overview〕

The permanent magnet alloy according to the present invention comprises cerium didymium, iron,
It is an alloy whose main components are tungsten and boron. In a broad sense, it falls under the category of rare earth magnets, but the magnet composition is completely different from conventional magnets, which are mainly composed of Namarium and Cobalt.

Generally, 15 types of rare earth elements are produced as mixed clay. To extract individual elements, the mixed clay must be separated and purified. Moreover, if only a specific element is used in large quantities, other elements will be left over, which is inconvenient. Therefore, the price of rare earth elements is determined not only by the abundance of resources and the amount in demand, but also by the order in which they are extracted, how difficult they are, and their balance with other elements. As a result, Sm is approximately 60,000 yen/
Mitsu 7 Yumetal is determined to be 3,000 yen/Kt stronger (both as of 1985). Ca-Dl (didymium; Nd-Pr alloy) contains about 75% and 7% in mixed rare earths of monazite and bastnaesite, respectively.
Since it is extracted and heated at the beginning of the refining process, no refining man-hours are required, and in recent years heavy rare earth (S)
Elements from m to LuK) growth and demand for metals f
There is a tendency for a surplus to arise from the area, so there is no need to worry about balance. Therefore, if it were to be used as a trap, it would be a trap so that it could be obtained at a price close to that of the metal.

The first feature of the permanent magnet alloy according to the present invention is that it uses inexpensive rare earth metals.The second feature of the permanent magnet alloy according to the present invention is that it uses one of the main components of conventional rare earth magnets. It does not use cobalt, which is Normally, Co-DI-Fe steel has a low Curie point Te and cannot be used as a ferromagnetic material, but by adding boron, the Tc increases and the ferromagnetism becomes stable. Boron with high purity may be used, and inexpensive ferroboron may also be used. By using iron instead of cobalt, it is freed from resource constraints and the cost of the nine alloys is also significantly reduced.

A fifth feature of the permanent magnet alloy according to the present invention is that tungsten (W) is added to increase the magnetic coercive force and to obtain a large coercive force even in the bulk state. By adding Mn, the coercive force IHe is increased to a level that does not pose a problem for practical use. Furthermore, it is particularly important to obtain a large coercive force in the bulk state for application to resin-bonded magnets, and magnetic particles of 10 μm or more can be used without problems, thereby improving the reliability and characteristics of the magnet. In addition, being able to handle magnetic powder with large particle size is also advantageous for its production. Part of T I * Z r HHr + V+N
When at least one element among b and Ta is substituted with one element, this effect of W is enhanced.

Moreover, a part of B of the Ce-DI-Fe-W-B combined line of the present invention is At, Ga, In, St, Ge, or P.

Substitution with at least one element of S HB i HS n HP b + C further enhances the strong stability effect. Even if a portion of the rare earth element is replaced with La, the magnetic force will not decrease even if the amount is small. By adding La, the rare earth component can be manufactured more easily and the cost of the alloy can be lowered.

Next, the reason for limiting the composition range will be described. Atomic ratio of elements in rare earth elements R=C'e 1- a -b N d
The coefficients a and b shown by aPrb are in the composition range 1ffiK, which allows Ce-DI alloy to be produced industrially at low cost. Also, when M=F e 1 x−yWx By y, R
The ratio 2 (Z=M/R) of M and M must be between 4.0 and 90 in order to produce a coercive force of 5 koe or more. The amount of W in M, X, was determined on the basis that the effect begins to appear above l101, and the saturation magnetic flux density decreases significantly when it exceeds α2. Similarly, the range of y is determined by the fact that the effect of boron starts to appear at α001 or higher, and when it exceeds 0.15, the coercive force and saturation magnetization decrease rapidly.

〔Example〕

Hereinafter, the present invention will be described in detail based on examples.

Example 1゜CeO, 4NdO, 4Pr0.2 (Fe0.1lWO,
1Bal) In the composition formula of Z, 2 is 9 in 0.5 increments from 4.0.
11 types of alloys (compositional formulas are atomized) were made into liquid layers using a low frequency induction furnace. B was made into a master alloy with Fe in advance to make it easier to melt. Each alloy was homogenized for 4 hours at an optimal temperature between 1100 and 1200 C in an argon atmosphere and then quenched to room temperature. Thereafter, it was subjected to isothermal heat treatment at 820 C for 6 hours and at 650 C for 4 hours, and then gradually cooled to room temperature at a cooling rate of 1.5 C/ml. The alloy was ground to an average particle size of 10-20 μm and mixed with 5 wt% epoxy resin.

The mixed magnetic powder was pressure molded in a 15 koe magnetic field, and the epoxy resin was cured to form a magnet. The magnetic properties of the obtained magnets are shown in FIG. 1 according to the values of 2. 2 is between 4.0 and 90, the coercive force iHc is of a level that does not cause any practical problems, the residual magnetic flux density Br is high, and the energy ill (
It can be seen that BH) max is obtained.

Example 2 A magnet was produced in the same manner as in Example 1 using an alloy having the composition shown in Table 5. The magnetic performance of the obtained magnet is shown in Table 4.

Table 3 Table 4 For each composition, properties of (BH)mar of 7 or more were obtained, and in some cases, properties equivalent to the highest performance of S m2 C and It systems were obtained. It is significant that such magnets can be made at low cost.

An alloy in which - of Example 2 was replaced with TI, Zr, Hf, V, Nb, and Ta was melted by the method of Example 1. However, M=Fe
αax-wWαIA w B O, 0B (A is the above six elements), take 11 types of W from 0 to [Q, 20 in 102 increments, R: Cea4NdO, 5Pral and R
The ratio 2 of M and M was set to 6.0. The magnet manufacturing method was the same as in Example 1. Figure 2 shows the results when icA is Zr. However, in the heat treatment after homogenization, since the addition of Zr improves lHe, in order to obtain a high energy product, i
Optimal conditions were adopted with the aim of suppressing the helium to an appropriate level and achieving the same squareness of hysteresis. It can be seen that better results were obtained when 71B was added to some extent than when Zr was not added. Table 5 shows how much the performance was improved by adding the above six elements compared to before addition.

Table 5 Example 4 A part of B is A tlG & + I n HS l
, G o , P + S I HBi, Sr+, Pb
The alloy substituted with was melted by the method of Example 1. However, M
=lF60.75Wal BcLli-uQu (Qa above 10 elements), R: Ce O, 4N d as Pr
1ll and Z=6.5 (RM as ), and 10 types of U were taken from 0.01 to Ql in increments of 0.01.

Magnet production was performed in the same manner as in Example 1. Among the magnets obtained with each substitution element (BH) max 210 MGOe or higher, Table 6 shows the improvement in Curi point of the alloy with the highest improvement in Curi point compared to before addition for each valley element. become that way.

Table 6 Example 5 An alloy in which a part of the rare earth element was replaced with La was made into a magnet using the same method as in Example 1. However, the composition is R:Ca
α45-c Ndα45 p rαI L a c
(C=lQ2゜α08.[115,0,25), M”:
Fe(L82WαI B 0.08 and Z=6.5
(RMILS). The obtained magnetic properties are shown in FIG. It has been shown that when La is added in a small amount, the squareness of hysteresis is slightly improved. Squareness evaluation 8-value is 4 on the 4πI-H demagnetization curve.
Letting Hk be the absolute value of the magnetic field H that makes yJ=[l, 9XBy, it is given by S Q '' Hk / l He.

Example 6 An alloy having the same composition as in Example 5 was melted in the same manner as in Example 1, and a magnet was produced by a sintering method. Sintering temperature is 120
Sintering was carried out under optimal conditions between 0 and 1300C (conditions that cause the largest contraction), and after sintering, it was slowly cooled to room temperature for 2 to 6 hours. Then, the temperature was raised again and multistage aging was performed from 850 to 400C. The magnetic performance of the obtained magnet is shown in FIG.

As shown in the figure, even if an inexpensive material such as this composition is used, a
It can be seen that a magnet equivalent to the mCo-based magnet can be obtained.

〔effect〕

As described above, according to the present invention51, high performance glass bonded magnets and sintered magnets can be produced even by using the inexpensive rare earth compound Ce-DI, and high cost performance not found in conventional magnets can be achieved. has.

[Brief explanation of drawings]

Figure 1 shows (e(1,4Ndα4 P r O,2(F
Fig. 2 shows the magnetic properties of a plastic bonded magnet when the ratio 2 of rare earth to other elements is changed in the e O, 8W O, IBO, +)2 composition. Figure 2 shows Ce0.4NdO,5prO,I (Feα
82-wWo, IZrwBαoa) 6.0 composition and shows the energy product of a plastic magnet when changing tW of 2''. Figure 3: Coα4s-cNdα4B P r o, +
L a c (Feo, 52WO, IBαos)
Figure 2 shows changes in the squareness and energy product of a glass bonded magnet when the gc of La is changed in the as composition. Figure 4 shows Ceα4s-cNdO,45P r o,
+ Lac(FeO, 82W at B cog)
The energy product of a magnet made by sintering an alloy with a composition of 46 is La
It is shown as the number of sections of change in the amount C. 5G789 2 Straight -- Figure 1 o, o+ o, ota o, 09 D-130, 170,
2+W value Figure 2 0.00 0.05 0.10 0,15 0.20
0.250 iJ - Figure 3 o, oo o, 05 0.10 0.15 0.20
0.2jiCi1 → Figure 4

Claims (1)

[Claims] (j) In the Ca-N d-P r-F e -W-B alloy, the atomic ratio of the rare earth element R and other elements M is 2.
When (2=number of atoms in M/number of atoms in R), the atomic ratio in R is R=Ce1-a-bNdaPrb, and the atomic ratio in M is expressed as M=Fe1-x-yWxBy , coefficient alb+! +y+” is in the following value range, i.e. 0.05
A permanent magnetic alloy characterized in that: ≦a≦α8 α05≦b≦α5 α01≦X≦0.5 0,001≦y≦α15 3.5≦2≦90. (2) Part of W is TI, Zr, Hf, V, Nb, Ta
Special # characterized by being replaced with at least one element of! F. A permanent magnet alloy according to claim 1. (5) Part of B is At, Ga, In+81. Ga, P
The permanent magnet alloy according to claim 1, characterized in that the permanent magnet alloy is substituted with at least one element of IS, Bi, Sn+Pb, and C. (4) The permanent magnet alloy according to claim 1, wherein a part of the rare earth element is replaced with Lm.