JPH0525592A - Rare earth magnet material - Google Patents

Abstract

PURPOSE:To provide a rare earth magnet material capable of securing excellent magnetic performance and temp. properties even if hydrogen is not contained. CONSTITUTION:This material is a one having a compsn. of general formula RxFe(1-x-y-z)MyCz as well as consisting of R2Fe17 type tetragonal crystals as a main phase and in which the above R denotes at least one of rare earth metals, Sm, Ce, Nb and Pr, the above M denotes at least one of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Ni, Pd, Cu, Ag, Zn, Mg, B, Al, Ga, In, Si, and Sn, the above (x), (y) and (z) lie in the range of, by atom, 5<=x<=15% 0.1<=y<=20% and 5<=z<=25% and, furthermore, a part of Fe is substituted by Co by <=40at% of the total content and a part of C by N.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rare earth metal-iron-carbon or nitrogen-based rare earth magnet material containing an R ₂ Fe ₁₇ type rhombohedral compound as a main phase.

[0002]

2. Description of the Related Art In recent years, with the miniaturization of various electronic parts and equipment, high-performance permanent magnets have been required. 1980
The Nd-Fe-B system permanent magnets developed in the 1980s have high magnetic performance and are composed of abundant and inexpensive raw materials as compared with the Sm-Co system permanent magnets developed before that. It is being widely used industrially for the reason.

By the way, the Nd-Fe-B system permanent magnet has a low Curie point of about 300.degree. C. and thus has poor temperature characteristics, and is not suitable for use in an atmosphere of 150.degree. C. or higher. As a countermeasure against this, a part of Fe is replaced with Co, but the Curie point is slightly increased, but there is a problem that the coercive force is significantly reduced even with a very small amount of Co replacement. As another measure for temperature characteristics, N
It is also done to replace part of d with Dy, but Dy
Is expensive and causes a decrease in saturation magnetic flux density,
In reality, it was difficult to improve the temperature characteristics.

Therefore, it has been recently reported that a rare earth element-iron-nitrogen-hydrogen alloy having a R ₂ Fe ₁₇ type compound as a main phase can be used as a magnet material (for example, Japanese Patent Laid-Open No. 2-57).
663). According to this, when nitrogen and hydrogen coexist in the alloy, a saturation magnetic flux density equivalent to that of an Nd-Fe-B system permanent magnet and a higher Curie point can be expected.

[0005]

However, according to the above-mentioned rare earth element-iron-nitrogen-hydrogen permanent magnet, hydrogen in the alloy is relatively easily released and occludes due to changes in temperature and pressure. The long-term stability of magnetic properties is easily impaired, and in addition, there is a problem in that manufacturability is difficult because hydrogen gas or ammonia decomposition gas, which has a risk of ignition and explosion, is handled.

The present invention has been made in view of the above conventional problems, and it is a rare earth magnet material capable of ensuring the magnetic performance equivalent to that of the Nd-Fe-B system permanent magnet and the temperature characteristics superior thereto even without containing hydrogen. The purpose is to provide.

[0007]

To achieve the above object, the present invention provides a R ₂ Fe ₁₇ type rhombohedral compound having a composition of the general formula R _x Fe _(1-xyz) M _y C _z . R is a rare earth magnet material whose main phase is R, and R is Sm, Ce, Nd, P
Made of a rare earth metal containing at least one of r, M is T
i, Zr, Hf, V, Nb, Ta, Cr, Mo, W, M
n, Ni, Pd, Cu, Ag, Zn, Mg, B, Al,
It is composed of at least one of Ga, In, Si and Sn, and x, y and z are expressed in atomic percentage in the following range 5% ≦ x ≦ 15% 0.1% ≦ y ≦ 20% 5% ≦ z ≦ 25%. It is characterized in that it is configured in.

In the present invention, a part of the above Fe is added to the total amount of 40 at.
% Or less Co, or a part of the above C may be replaced with an appropriate amount of N. Further, in the present invention, it is desirable that the carbide of M is dispersed and precipitated in the matrix.

The present invention is characterized in that at least one of Sm, Ce, Nd, and Pr is selected as the rare earth metal (R) as described above, but La, Eu, and Gd, Tb, Dy, Ho, Er
, Tm, Yb, Lu and Nd may be selected in combination. When the total amount of the rare earth metal is less than 5% in atomic percentage (at%), the coercive force decreases, and when it exceeds 15%, the saturation magnetic flux density or the residual magnetic flux density becomes small and it is difficult to be a practical permanent magnet. If the content exceeds the above range, R ₂ Fe in the alloy
Other than the ₁₇ compound, for example, αFe or RFe ₃ compound appears in large quantity and causes deterioration of magnetic properties, so this is set to 5 to 15 at%.

C has the function of penetrating into the crystal lattice of the R ₂ Fe ₁₇ type compound and increasing the saturation magnetic flux density, the Curie point and the crystal magnetic anisotropy. Further, N also has the same function as C, so that part of C may be replaced with N. If the proportion of C to be closed in the alloy is less than 5 at%, the crystal magnetic anisotropy is small and the coercive force becomes extremely small. On the other hand, if it exceeds 25 at%, the coercive force becomes small due to an increase in α-Fe of soft magnetic property. Was 5 to 25 at%.

Regarding the additive metal M in the above general formula, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, selected from transition metals, low melting metals or light metals,
W, Mn, Ni, Pd, Cu, Ag, Zn, Mg, B,
At least one of Al, Ga, In, Si, and Sn is selected, and these are effective in improving the magnetic characteristics of the magnet material, particularly in improving the coercive force. Among these metals, for example, Ti, Ni, Al, Ga and the like have the effect of substituting a part of R or Fe of the R ₂ Fe ₁₇ type compound to enhance the magnetocrystalline anisotropy, and Zn, Sn and the like are , Has an effect of suppressing a decrease in coercive force by reacting with αFe contained in a small amount in the alloy to form a compound. Further, Ti, Zr, Ta, etc. all tend to form carbides and nitrides, so they have the function of dispersing and precipitating in the alloy to enhance the coercive force. However, in order to maximize the above-mentioned effects, it is necessary to set this M in the range of 0.1 to 20 at%.

[0012] Co has the effect of raising the Curie point to improve temperature characteristics and corrosion resistance, but if the total amount with respect to the magnet material exceeds 40 at%, the crystal magnetic anisotropy decreases and it is sufficient. Since no sufficient coercive force can be obtained, this is set to 40 at% or less.

In order to manufacture the rare earth magnet material according to the present invention, as an example, an alloy powder composed of a rare earth metal, iron and another additive metal (M) is obtained, and the alloy powder is subjected to a carburizing gas at a predetermined temperature. It is possible to employ a method of bringing C into contact with the alloy and invading C into the alloy to obtain a predetermined composition. In this case, as a method for obtaining the alloy powder, for example, a raw material in which a rare earth metal and iron (and cobalt) are mixed at a predetermined ratio is melted and cast in a high frequency induction furnace, and the obtained alloy ingot is mechanically cut by a jaw crusher or the like. Crushing method, quenching method that directly injects molten alloy onto the rotating roll surface, atomizing method that injects molten alloy at high speed into gas or liquid, mechanical alloying that uses mutual diffusion of solid metals instead of melting The law etc. can be selected. Also, the method of infiltrating C into the alloy powder is optional,
General-purpose gas carburizing method using endothermic metamorphic gas, carburizing method using solid carburizing agent, organic solvent dropping type carburizing method, vacuum carburizing method by introducing hydrocarbon gas into depressurized vacuum furnace it can. After these carburizing treatments, if desired, a heat treatment may be performed at a temperature of 500 ° C. or lower to improve and adjust the structure inside the alloy. When nitrogen is also contained, it is possible to employ a method in which the alloy powder is brought into contact with a nitriding gas at 400 to 600 ° C., that is, a so-called nitriding treatment is performed. Needless to say, carbon and nitrogen may be contained in the starting alloy regardless of the carburizing and nitriding treatments.

The rare earth magnet material according to the present invention may be used as a bonded magnet or a sintered magnet. When it is used as a bonded magnet, thermosetting resin such as epoxy resin or phenol resin is mixed with the above alloy powder after carburizing or nitriding treatment, and compression molding is performed with a mold, and then at a predetermined temperature (100 to 170 ° C). A method of curing to a magnet, a method of mixing and molding a metal such as zinc, tin or lead into the alloy powder, and then firing at a predetermined temperature (200 to 500 ° C.) to form a magnet, or a nylon resin to the alloy powder. It is possible to employ a method in which a thermoplastic resin such as the above is mixed and injection molding is performed to obtain a magnet. On the other hand, when used as a sintered magnet, the alloy powder may be mixed with a lubricant such as stearic acid, shaped, sintered in an inert gas or vacuum, and optionally heat-treated. In any case, an anisotropic magnet can be obtained by applying a magnetic field during molding.

[0015]

In the rare earth magnet material constructed as described above, C or N penetrates into the crystal lattice of the R ₂ Fe ₁₇ type rhombohedral compound to increase the saturation magnetic flux density, the Curie point and the crystal magnetic anisotropy. Acts to cause. Further, since the alloy does not contain hydrogen, stable performance can be ensured for a long period of time, and since hydrogen is not handled in the manufacturing process, safety is improved.

[0016]

EXAMPLES Examples of the present invention will be described below.

EXAMPLE 1 Samarium (Sm) having a purity of 99.9%, electrolytic iron (Fe), titanium sponge (Ti) having a purity of 99.5%, and pig iron containing 4.3% of carbon were blended in a predetermined ratio to form an alumina crucible. It was charged, melted in a high frequency induction furnace, and cast in a mold to produce alloy ingots of various composition. In many cases, segregation of the components was observed inside the alloy ingot. Therefore, the alloy ingot was heat-treated by holding it in an argon gas atmosphere at 1000 ° C for 12 hours and then rapidly cooling it. Next, this alloy ingot is subjected to a jaw crusher to be roughly crushed to a size of several mm, and then further crushed by a stamp mill to obtain magnet material samples 1 to 20 having an average particle diameter of 20 μm. It was subjected to a measurement test of magnetic properties, Curie points, and components. As a result of analyzing the crystal structure of each sample by the X-ray diffraction method, the presence of the R ₂ Fe ₁₇ compound as the main phase was confirmed in all the samples according to the present invention. The magnetic characteristics were measured by packing these magnet material samples in a predetermined holder in a magnetic field of 15 kOe and then using a vibrating sample magnetometer (abbreviated as VSM), and the Curie point was also measured by VSM. The component analysis was carried out by ICP emission spectrometry for Sm, Fe and Ti, and by combustion method for C.

Table 1 collectively shows the results of these tests.
In the table, sample numbers 1 to 7 show the results sorted by C, and sample numbers 8 to 12 show the results sorted by Sm. In the table, 4πIm represents the maximum magnetic flux density, iHc represents the coercive force, and Tc represents the Curie point. As the maximum magnetic flux density, it is difficult to measure the saturation magnetic flux density, so the magnetic flux density at the maximum measuring magnetic field of 20 kOe was adopted. Further, in the table, the symbol # added to the sample number represents a comparative example.

[0019]

[Table 1]

As is clear from Table 1, in the magnetic material samples 2 to 6 and 9 to 11 according to the present invention, the maximum magnetic flux density 4πIm, the coercive force iHc and the Curie point Tc were high. Especially for the Curie point Tc 340-53
The value is as high as 0, and it is clear that the value is sufficiently high even when compared with the Curie point of the Nd-Fe-B system permanent magnet of about 310 ° C. The coercive force iHc of the comparative sample 1 containing a small amount of C and the comparative sample 8 containing a small amount of Sm is extremely smaller than the others, and the reason is as follows.
According to X-ray diffraction, it is presumed that a large amount of αFe present in the alloy was the cause. Further, in Comparative Example Samples 7 and 12 containing an excessive amount of C or Sm, the maximum magnetic flux density 4πIm also decreased due to the decrease of the Fe content in the alloy along with the decrease of the coercive force iHc.

Example 2 Samarium having a purity of 99.9% and electrolytic iron, cobalt having a purity of 99.5% and titanium sponge, and pig iron containing 4.3% C were mixed at a predetermined ratio and melted to produce an alloy ingot. The alloy ingots were crushed by the same procedure as in Example 1 to produce magnet material samples 21 to 25, which were subjected to the same magnetic characteristic measurement test as in Example 1. The results are shown in Table 2.
Shown in.

[0022]

[Table 2]

As is clear from Table 2, the magnetic material samples 21 to 24 according to the present invention all have a maximum magnetic flux density of 4πI.
It was found that high values of m, coercive force iHc and Curie point Tc were obtained, and in particular the Curie point Tc increased as the Co content increased. The comparative sample 25 containing excessive Co has a decrease in the coercive force iHc and a maximum magnetic flux density of 4π as estimated from the Slater Pauling curve.
Im has also dropped slightly.

Example 3 Samarium and electrolytic iron having a purity of 99.9%, pig iron containing 4.3% C and Cu, Al, Ga, V and Ti having a purity of 95% or more.
, Zr, Ta, Sn, and Zn are mixed and dissolved at a predetermined ratio, and magnet material samples 31 to 45 are manufactured by the same procedure as in Example 1. It was subjected to an analytical test. Table 3 shows the measurement test results of the magnetic properties.

[0025]

[Table 3]

As is clear from Table 3, in the magnetic material samples 32 to 35 and 37 to 45 according to the present invention, both the maximum magnetic flux density 4πIm and the coercive force iHc are high, and various additive elements M are added. It was confirmed to be effective within the appropriate content range. Further, as a result of X-ray diffraction analysis of Samples 34 and 42, a small amount of TiC or ZrC was observed together with the R ₂ Fe ₁₇ type compound in which C invaded in each sample, and therefore precipitation of these carbides was αFe It is presumed that the coercive force of the alloy is increased by suppressing the generation of. The added metal M
Of the comparative example sample 31 having an excessively small amount of coercive force iHc is lower than that of the other sample, and the comparative sample 36 having an excessive amount of M has a coercive force of iHc.
The maximum magnetic flux density 4πIm also decreases with decreasing.

Example 4 Based on Sm-Fe-C-Sn alloy, Pr,
Any one or more of Nd, Ce, and Dy is selectively added, and a magnet material sample 51 is prepared by the same procedure as in Example 1.
.About.56 were obtained, and these were subjected to a magnetic characteristic measurement test. The results are shown in Table 4. From the results shown in Table 4, all of the magnetic material samples 51 to 55 according to the present invention have a maximum magnetic flux density of 4πI.
High values of m and coercive force iHc were obtained, and it became clear that rare earth metals other than Sm can be used in combination. In the comparative sample 56, the maximum magnetic flux density 4πIm and the coercive force iHc are both low because the total amount of rare earth metals is excessive.

[0028]

[Table 4]

Example 5 Samarium, electrolytic iron and vanadium were mixed and dissolved in a predetermined ratio, and the same procedure as in Example 1 was applied to obtain 50 to 150 μm.
An alloy powder of m 3 was obtained. Next, put this alloy powder in a stainless steel small plate and load it into a vacuum furnace. Continuously introduce methane gas at a pressure of 0.1 Torr into this vacuum furnace and keep it at 1050 ° C for 2 hours to inject C into the alloy powder. It was Then, this powder was further charged into a pressure type electric furnace and was placed under a nitrogen gas atmosphere for 5
Atmospheric pressure, 400-500 ° C, hold for 4 hours to let in N,
Further, it was pulverized by a ball mill to obtain magnet material samples 61 to 65 having an average particle size of 20 μm, and these were subjected to a magnetic characteristic measurement test. The results are shown in Table 5.

[0030]

[Table 5]

From the results shown in Table 5, the magnet material samples 61 to 64 according to the present invention have high coercive force iHc, and Sm-
It has been clarified that excellent magnetic properties can also be obtained by the method of infiltrating C and N into the Fe alloy by gas carburizing and gas nitriding. Further, as a result of performing an X-ray diffraction analysis on the sample 63 in the same manner as in Example 3, a small amount of VC or VN was recognized together with the R ₂ Fe ₁₇ type compound having C invaded. It is presumed that VC or VN suppresses the generation of αFe and enhances the coercive force. The comparative sample 65 is
The maximum magnetic flux density is 4 because the total amount of C and N is excessive.
Both .pi.Im and coercive force iHc decrease.

Example 6 Samarium, neodymium, electrolytic iron, pig iron and Sn were mixed and dissolved at a predetermined ratio, and magnet material samples 71 to 74 were obtained in the same procedure as in Example 1, and the magnetic properties were measured. It was submitted to the test. The results are shown in Table 6. From this, it was revealed that the magnetic material samples 71 to 74 according to the present invention all showed excellent magnetic characteristics and particularly high coercive force iHc was obtained.

[0033]

[Table 6]

Example 7 The magnet material sample 4 in Example 1 was mixed with 3% by weight of a one-pack type epoxy resin in a predetermined mold and filled with 15 kO.
A magnetic body sample was manufactured by performing compression molding at a pressure of 5 Ton / cm ² while applying a magnetic field of e, and performing a curing treatment in nitrogen gas at 150 ° C. for 1 hour. After applying a pulse magnetic field of 60 kOe to this sample, the magnetic characteristics were measured with a DC BH tracer. As a result, the maximum magnetic flux density is 4πIm
= 9780 (G), the residual magnetic flux density Br = 9660 (G), and the coercive force iHc = 4013 (Oe), it was revealed that excellent magnet characteristics can be obtained.

Example 8 The magnet material sample 4 in Example 1 was mixed with 10% by weight of zinc powder and mixed in a ball mill, and then compression molded at a pressure of 4 Ton / cm ² while applying a magnetic field of 15 kOe, Subsequently, heat treatment was performed in nitrogen gas at 350 to 450 ° C. for 2 hours to manufacture magnet body samples 81 to 83, which were subjected to a magnetic characteristic measurement test. Table 7 shows the results of the measurement test, and in this example, the coercive force iHc was remarkably improved. From this, it became clear that good magnetic characteristics can be obtained even when a low melting point metal such as zinc is mixed with the magnet powder instead of the resin.

[0036]

[Table 7]

Example 8 1% by weight of zinc stearate was mixed with the magnet material sample 4 in Example 1, compression-molded at a pressure of 1 Ton / cm ² while applying a magnetic field of 15 kOe, and then hot pressed. Was sintered in nitrogen gas at 450 ° C. under a pressure of 1 Ton / cm ² for 30 minutes to prepare a magnet body sample, which was subjected to a magnetic characteristic measurement test. As a result, the maximum magnetic flux density is 4πIm
= 11760 (G), residual magnetic flux density Br = 11420 (G), and coercive force iHc = 5137 (Oe), it was revealed that excellent magnet characteristics can be obtained.

[0038]

As described above in detail, according to the rare earth magnet material of the present invention, not only the magnetic characteristics equivalent to those of the Nd-Fe-B system permanent magnet can be secured, but also the Curie point is increased. The temperature characteristics can be greatly improved by the above, and further, since the magnet alloy does not contain hydrogen, the performance will be stable in the long term. Moreover, since hydrogen is not handled in the manufacturing process, safety is improved.

Claims (5)

[Claims] 1. A rare earth magnet material having a composition of the general formula R _x Fe _(1-xyz) M _y C _z and having an R ₂ Fe ₁₇ type tetragonal compound as a main phase, wherein R is Sm. , Ce, Nd,
It is made of a rare earth metal containing at least one of Pr, wherein M is Ti, Zr, Hf, V, Nb, Ta, Cr, Mo,
W, Mn, Ni, Pd, Cu, Ag, Zn, Mg, B,
And at least one of Al, Ga, In, Si and Sn, wherein x, y and z are atomic percentages within the following range: 5% ≦ x ≦ 15% 0.1% ≦ y ≦ 20% 5% ≦ z ≦ 25% A rare earth magnet material characterized by being present. 2. The rare earth magnet material according to claim 1, wherein a part of Fe is replaced with Co of 40 atomic% or less of the total amount. 3. The rare earth magnet material according to claim 1, wherein part of C is replaced with N. 4. The carbide of M is dispersed and precipitated in a matrix, according to any one of claims 1 to 3.
The rare earth magnet material according to the item. 5. The nitride of M is dispersed and precipitated in a matrix, according to any one of claims 1 to 3.
The rare earth magnet material according to the item.