JPS62257704A - Permanent magnet - Google Patents

Abstract

PURPOSE:To obtain a sintered permanent magnet having stable magnetic characteristics, by producing the permanent magnet from a sintered material having a specific composition and a predetermined grain size and containing a predetermined amount of oxygen. CONSTITUTION:A permanent magnet is composed of a sintered material having a composition of [(CexLa1-x)yR1-y]z [(Fe1-uMu)1-vBv]1-z, containing 2000 ppm or less of oxygen and having an average grain size of 3-40mum. In the above formula, R represents at least one of rare-earth elements (containing Y) except Ce and La, M represents at least one of the group consisting of Al, Ti, V, Cr, Mn, Zr, Hf, Nb, Ta, Mo, Ge, Sb, Sn, Bi, Ni, W, Cu and Ag; 0.4<=x<=0.9, 2<=y<=1.0, 0.05<=z<=0.3, 0.01<=v<= 0.3, and 0<=u<=0.2. The composition of the magnet may be [(CexLa1-x)yR1-y]z[(Fe1-u-wCowMu)1-vBv]1-z when 0<w<=0.5. In this manner, a sintered permanent magnet having stable magnetic characteristics can be obtained.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to rare earth-iron permanent magnets.

[Conventional technology]

BACKGROUND ART Research has been actively conducted in recent years on permanent magnets containing rare earth elements -Fe-B as a basic component, and the results are beginning to be published in published patent publications and the like.

According to JP-A-57-141901, a composition consisting of a combination of a transition group metal (T), a metalloid metal (M), Y, and a lanthanide element R is made amorphous, and then the amorphous composition is crystallized by heat treatment. A method for manufacturing permanent magnet powder is described in which coercive force is generated by oxidation. According to this publication, T is Ti, V, Cr, Mn, Fe, C
o, Ni, Cu.

One or a combination of two or more selected from Zr, Nb, Mo, HE, Ta, and W, and M is B
, Si, P, and C; R is one or more combinations selected from Y and lanthanide elements;
MX) J+-g (however, 0≦x≦0.35
, 0.35≦z≦0.90).

According to JP-A-58-123853, a material containing La and Pr has been proposed, and its composition is (Fex
B+-Jy(La*Prw]z[(Fe1-*-w)
+-y, where R is La.

Rare earth metals other than Pr, x = 0.75 to 0.85
, )' -0,85~0.95, z = 0.4
0-0.75, w=0.25-0.60.

z+w≦1.0. In this publication, 1. The types and proportions of rare earth elements are determined by the above-mentioned (LaJrw]z[(Fe
1-z-w) is described.

JP-A No. 59-46008 discloses that 8 to 30 atomic % of R (wherein R is at least one rare earth element), 2 to 2
A magnetically anisotropic sintered body consisting of 8 at % B and the balance Fe has been proposed. One of the intentions of the invention disclosed in this publication is to make it possible to manufacture a permanent magnet body of any shape by a sintering method rather than by a liquid quenching method. Also,
R in the sintered body component includes Nd alone, Pr alone, Nd
and Pr combination, Nd and Ce combination, Sm and Pr combination, Pr and Y combination, Nd, Pr and La combination,
The magnetic properties of sintered bodies are shown for Tb alone, Dy alone, HO alone, a combination of Er and Tb, etc.

To summarize the prior art as mentioned above, R-Fe-B (however,
R is a rare earth metal) system permanent magnet, R is Nd or P
It can be seen that excellent magnetic properties were obtained when r.

In addition, some prior art patents claim that La and Ce can be used as rare earth elements, but rather than using only La as R, the upper limit of the content of La is limited. This prevents deterioration of magnetic properties due to a large amount of La. In the above-mentioned prior art, there is no example of a permanent magnet specifically composed of rare earth components mainly composed of La and Ce.

Figure 1 is from J, Appl, Phys, Vol 55 (19
84) This is the demagnetization curve of the R-Fe-B permanent magnet alloy, which is a reproduction of the graph published on page 2079. This graph also shows that Pr and Nd are the most desirable R components of R-Fe-B alloys, and alloys with La or Ce as R components of R-Fe-B alloys no longer have the characteristics as permanent magnets. I understand. From this point of view, even though the above-mentioned prior art discloses replacing a very small part of Pr, Nd, etc. with La or Ce, the R It can be said that there is no disclosure that the -Fe-B alloy can be used as a permanent magnet.

Recent notable developments in rare earth-iron permanent magnets include:
Fe-(3) announced at MMM in October 1984
2.5-34.5%) R-(1-1.6%) B1 (where R is didymium (Nd-10%Pr), 5Ce-didymium, or 4O-Ce didymium) is 1Hc = 10.2kg
(BH) m*X -40MGOe was achieved. (rDIDYMIUM-Fe-B 5INTER
ED PERMANENT MAGNETS J paper),
However, even in this permanent magnet, the R component is mainly Nd.

[Problem that the invention seeks to solve]

Permanent magnets whose basic components are R-Fe-B have excellent magnetic properties, but one problem with them is that in order to obtain excellent magnetic properties, Nd and Pr must be the main rare earth metals. This made permanent magnets expensive. Therefore, the didymium-containing permanent magnet is attracting attention because it can exhibit magnetic properties equivalent to those of Nd and Pr even when relatively inexpensive didymium is used.

La or Ce is produced in large quantities and is inexpensive compared to other rare earth elements, so if it were possible to use them as the main components of rare earth metals, it would be possible to significantly reduce the cost of rare earth-iron permanent magnets. . However, as can be seen from FIG. 1, La and Ce are elements harmful to magnetic properties. La
, Ce is harmful in terms of magnetic properties because the ferromagnetic component of rare earth-iron permanent magnets is a RzFe+4B compound, and if R is La, this compound becomes unstable or is not produced, and R is R (Ce) Jet
This is because 4B has a small coercive force.

As mentioned above, although the prior art has proposed various improvements, it has not yet come to the point of proposing a permanent magnet using La and Ce as the main components of the rare earth metal.

[Failure to solve the problem]

The present invention provides [(CexLa1-x)y]z[(Fe1-y)z
((Fe+-uMu)+-v Bv) +-g-
However, R is at least one rare earth metal (including Y) other than Ca and La, and M is Al or Ti.

V, Cr, Mn, Zr, Hf,
Nb, Ta, Mo.

Ge, Sb, Sn, Bi, Ni, W, Cu, and A
At least one element of the group consisting of g, 0.4≦x≦0
．． 9, 0.2<y≦1.0, 0.05≦z≦0.3
, 0.01≦v≦0.3.0≦u≦0.2-, the amount of oxygen is 2000 ppm or less, and the average crystal grain size of the sintered body is 3 to 40 μm. Features of sintered permanent magnet and C(CexLa+-x)y]z[(
Fe1-y) z ((Fe+-u-wcOJu)+-
vBj +-z- However, R is Ce, at least one rare earth metal other than La (including Y), and M is Ag, T
i.

V, Cr, Mn, Zr, Hf, Nb, Ta, Mo.

Ge, Sb, Sn, Bi, Ni, W, Cu, and Ag
At least one element of the group consisting of 0.4≦x≦0.
9,0.2<y≦1.0, 0.05≦z≦0.3,
0.01≦v≦0.3.0≦u≦0.2゜Q<w≦0.
Provided is a sintered permanent magnet having a composition of:

The present invention will be explained in detail below.

When X is less than 0.4 or more than 0.9, La
Since only a coercive force comparable to that of the composition of Ce alone or Ce alone can be obtained, x = 0.4 to 0.9.

Moreover, if 2 is less than 0.05, the squareness ratio and coercive force will decrease, and if 2 exceeds 0.3, the residual magnetic flux density will decrease, so z was set to 0.05 to 0.3. Furthermore, if ■ is less than 0.01, the coercive force decreases, and V is 0.3.
If it exceeds V=0, O1~ because the residual magnetic flux density decreases.
It was set to 0.3. Furthermore, in order to obtain higher coercive force, 0.6≦x≦0.8, 0.02≦v≦0.15゜0
．． It is preferable that the range is 1≦z≦0.2. More preferably, 0.03≦v≦0.12. The ratio of heavy rare earth elements in R is desirably 0.4 or less, particularly 0.2 or less.

Co increases the Curie temperature and improves magnetic properties, especially Br.
improve the temperature characteristics of If the amount W of CO added exceeds 0.5, the characteristics as an inexpensive permanent magnet will diminish and the coercive force will decrease, so Q<w≦0.5. Preferably 0.0
01≦W≦0.35.

The reason why the oxygen amount is set to 2000 ppm or less in the present invention is that if 0□ exceeding this value is included, the high performance inherent to this composition system as a permanent magnet will not be exhibited.

The (average) grain size of the sintered body was set to 3 to 40 μm because
In order to achieve a particle size of less than 3 μm, the particle size used for molding should be 2.5 μm.
Since it has to be less than μm, the grinding process becomes long and complicated, and it becomes difficult to maintain the oxygen content below 2000 ppm, resulting in a decrease in magnetic flux density (Br). 40
When larger than μm, the particles are no longer single-domain particles;
During magnetic field pressing, the orientation of the particles deteriorates and the magnetic flux density decreases, and the number of points where reversed magnetic domains occur increases and the coercive force also decreases.

A general explanation of the method for manufacturing a permanent magnet of the present invention is as follows. First, raw materials are blended to give the desired composition. This is carried out in an inert gas such as argon or
After melting and casting in vacuum, an alloy ingot is obtained. Next, the obtained ingot is subjected to solution treatment in a non-oxidizing atmosphere or pulverization after aging, as required. The grinding is carried out in a strictly non-oxidizing atmosphere according to known coarse grinding or fine grinding methods. The alloy is crushed to an average particle size of 2 to 15
It is adjusted so that it becomes μm. Thereafter, compression molding is performed in a non-magnetic field or in a magnetic field of approximately 3 to 15 KOe while maintaining a non-oxidizing atmosphere to obtain a molded body. The molded body is then transported to a heat treatment furnace while maintaining a non-oxidizing atmosphere, where it is heated to 900 to 1200°C in a vacuum or in an inert gas at a temperature of 0.
Cool after sintering for 5 to 6 hours. Next, if necessary, aging treatment is performed at a temperature of 50 to 750 degrees Celsius lower than the sintering temperature.
Apply for 0 hours. As for the aging treatment, a higher coercive force can be obtained by using a multi-stage aging treatment in which aging is performed on the low temperature side after the first stage aging on the high temperature side. In this way, the permanent magnet of the present invention is manufactured.

[For production]

One of the features of the permanent magnet according to the present invention is that it is less expensive in terms of composition than conventional permanent magnets.

That is, extremely inexpensive permanent magnets are manufactured mainly using La and Ce, which were conventionally thought to be unusable as components of Fe-BR permanent magnets.

Therefore, in the present invention, the coercive force is maximum when the atomic ratio of La and Ce is about 0.35 to about 0.65, and the coercive force (iHc) is about 35 times, which is about 3.5 times that of Ce alone.

In Japanese Patent Application No. 59-280125 assigned to the present applicant, the inventor proposed that the coercive force (i
In order to investigate the cause of the remarkable increase in Hc), FeysCL
, a+-xCer)+Js was examined using X-rays,
The presence of RzFe14B type crystals was confirmed. This crystal had the same crystal form as that conventionally detected in Nd-Fe-B alloys.

It has been conventionally believed that La does not form RzFe+4B type crystals, and therefore La has not been used as the main R component of R-Fe-B permanent magnets. However, La and Ce
The presence of RJe+ aB type crystals was confirmed in compositions where La and Ce coexist, so when La and Ce coexist, RJe+
It was found that the J-type crystal was the main crystal. Therefore, it was considered that this crystal contributed to the improvement of coercive force (iHc).

In addition, Ce, Fe, and B have the lattice constant a, = 0.8
77 square crystals were prepared, and their coercive force (iHc) was La.
-Fe-B is known to be much higher than that of -Fe-B.

However, by coexisting Ce and La, Ce
A much higher coercive force (iHc) than Je+aB is obtained. Considering this point, the high coercive force (iHc) obtained by the present invention is due to the fact that La and Ce are RzFe+J
It was thought that the presence of a certain proportion in the crystal also contributed.

Another feature of the permanent magnet according to the present invention is that stable magnetic properties are obtained by controlling the oxygen content and crystal grain size of the sintered body.

Since rare earth elements are easily oxidized, rare earth oxides are generated in the sintered magnet, and if they exist in the crystal grains, they become points of generation of reversed magnetic domains and reduce the coercive force of the sintered magnet. Furthermore, rare earth oxides are non-magnetic, or even if they are magnetic, they have a low saturation magnetic flux density, so they reduce the residual magnetic flux density of the sintered magnet. Such rare earth oxides make the magnetic properties of the sintered magnet of the present invention containing La and Ce as main rare earth components extremely unstable. That is, La and Ce
In sintered magnets whose main component is rare earth, the influence of rare earth oxides is greater than in permanent magnets whose main component is Nd, etc.
3000 ppm for permanent magnets whose main component is d
Oxygen levels above 2,000pp are allowed, but in this composition system, 2000pp
Oxygen must be regulated below m. Additionally, the grain size of the sintered magnet affects its magnetic properties. For permanent magnets containing Nd as a main component, good magnetic properties are obtained between 1 μm or less and 80 μm. However, in a permanent magnet whose main components are La and Ce as rare earth elements, the crystal grain range with good magnetic properties is narrower, from 3 to 40 μm, than in a permanent magnet whose main component is Nd.

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

〔Example〕

Example 1 An ingot having the composition shown in Table 1 was manufactured by an argas atmosphere melting method. Next, the mixture was coarsely pulverized and finely pulverized using a Shaw crusher, a Brown mill, and a jet mill in an argon atmosphere to obtain a fine powder of about 3 to 5 μm. Then, about 10 KOe was added to a fine powder.

Pressing was performed in a magnetic field in an argon atmosphere under conditions of 1.5 tons/cot. Subsequently, sintering was performed at 1000 to 1100°C for 2 hours in an argon atmosphere. Furthermore, the obtained sintered body was heated to a temperature of 500 to 90% in an argon atmosphere.
Aging treatment was performed at 0°C. The obtained magnetic properties are shown in Table 1.

18 and 19 in Table 1 are comparative examples of compositions in which Ce and La do not coexist. In these Nos. 18 and 19, the crystal grain size and oxygen concentration are within the range of the present invention, but
Since La and Ce do not coexist, the magnetic properties are extremely low. On the other hand, in the example of the present invention, a coercive force (iHc) of 5 kOe or more is obtained.

The permanent magnet of the present invention having a coercive force of 5 kOe or more can more than compete with rare earth cobalt-based, Fe-B-Pr (Nd)-based, and ferrite-based permanent magnets.

Comparative Example A sintered magnet having the composition shown in Table 2 was manufactured in the same manner as in Example 1. However, it was decided that the coarse pulverization and molding steps would be carried out in the atmosphere to achieve normal sintered magnet manufacturing conditions where oxidation is likely to occur. Table 2 shows the properties of the obtained permanent magnet.

The following table shows the difference in magnetic properties between the corresponding compositions in Table 1 and the compositions in Table 2.

Table 3 [Effects of the invention] The permanent magnet according to the present invention is extremely inexpensive and has a coercive force (
i Hc) is expected to be used in various applications because it has a satisfactorily high value.

[Brief explanation of drawings]

Figure 1 shows Ro, +3s (F e o, qzs B
o, obs) o, 1165. Figure 1

Claims (1)

[Claims] 1, [(Ce_xLa_1_-_x)_yR_1_-_
y]_z[(Fe_1_-_uM_u)_1_-_vB
_v]_1_-_z-However, R is Ce, at least one rare earth metal other than La (including Y), and M is Al,
Ti, V, Cr, Mn, Zr, Hf, Nb, Ta, Mo
, Ge, Sb, Sn, Bi, Ni, W, Cu, and A
At least one element of the group consisting of g, 0.4≦x≦0
．． 9, 0.2<y≦1.0, 0.05≦z≦0.3, 0
．． 01≦v≦0.3, 0≦u≦0.2-, the amount of oxygen is 2000 ppm or less, and the average crystal grain size of the sintered body is 3 to 40 μm. Sintered permanent magnet. 2, [(Ce_xLa_1_-_x)_yR_1_-_
y]_z[(Fe_1_-_u_-_wCo_wM_u
)_1_-_vB_v]_1_-_z-However, R is Ce
, at least one rare earth metal other than La (including Y)
, and M is Al, Ti, V, Cr, Mn, Zr, Hf,
Nb, Ta, Mo, Ge, Sb, Sn, Bi, Ni, W
, Cu, and at least one element of the group consisting of Ag, 0.4≦x≦0.9, 0.2<y≦1.0, 0.05
≦z≦0.3, 0.01≦v≦0.3, 0≦u≦0.2
A sintered permanent magnet having a composition such that 0<w≦0.5 -, an oxygen content of 2000 ppm or less, and an average crystal grain size of the sintered body of 3 to 40 μm.