JP4863377B2 - Samarium-iron permanent magnet material - Google Patents

Description

  The present invention relates to a new permanent magnet material that replaces the conventional permanent magnet material.

Rare earth magnets such as samarium-cobalt magnets and neodymium-iron-boron magnets are widely used as high-performance magnets from computer peripherals, consumer electronic devices, measuring / communication devices to automobiles and medical devices. It has increased. Ferrite magnets are inferior in magnetic properties to high-performance neodymium-iron-boron magnets, but they are oxide magnets and are cheaper and chemically stable. It is a magnet that is widely used in large quantities. Alnico magnets are also used for measuring instruments because of their good temperature characteristics. The rare earth magnets, ferrite magnets, and alnico magnets mentioned above are representative magnets that are currently used, accounting for 99% of the amount of magnets used, but manganese-aluminum magnets and iron-chromium cobalt magnets are put to practical use as other magnets. Has been.
Since the development of neodymium-iron-boron (Nd-Fe-B) magnets containing the rare earth metal neodymium, permanent magnet research has mainly focused on finding new intermetallic compounds of rare earth metals. .
As a result, a new rare earth magnet called a samarium-iron-nitrogen (Sm-Fe-N) magnet obtained by nitriding an intermetallic compound (Sm ₂ Fe ₁₇ ) of samarium and iron has been developed and put into practical use (for example, Patent Document 1). reference). The basic magnetic properties of this samarium-iron-nitrogen magnet are known to be high enough to be comparable to the magnetic properties of neodymium-iron-boron magnets, but the disadvantage is that this nitrogen-containing compound decomposes at high temperatures. Therefore, a high-performance sintered magnet such as a neodymium-iron-boron magnet cannot be produced. Therefore, this samarium-iron-nitrogen magnet is mainly used as a bonded magnet bonded with resin in the form of powder.
In addition, new rare earth magnets have been developed as new rare earth metals (R) and iron intermetallic compounds (RFe ₁₂ ) and nitride magnets that nitride rare earth metals (R) and iron intermetallic compounds (RFe ₇ ). It was done. However, rare earth metal (R) and iron intermetallic compound (RFe ₁₂ ) and rare earth metal (R) and iron intermetallic compound (RFe ₇ ) are obtained in binary alloys of rare earth metal (R) and iron. It can only be obtained as a ternary alloy of rare earth metal (R) and iron and titanium with a small amount of titanium (Ti) added, and the magnetic properties of rare earth magnets nitrided with these intermetallic compounds are samarium. It is not put into practical use because it is inferior to a samarium iron nitrogen magnet (Sm-Fe-N) magnet obtained by nitriding an intermetallic compound of iron and iron (Sm ₂ Fe ₁₇ ).
JP 2006-2187 A

  An object of the present invention is to provide a new permanent magnet material capable of obtaining a high-performance sintered magnet made of a binary alloy of rare earth metal (R) and iron.

In this invention, a samarium-iron-based permanent magnet containing 10-40% samarium (Sm) in atomic percent, the balance being substantially composed of iron (Fe), and the main phase being an Sm ₅ Fe ₁₇ intermetallic compound phase The above problems are solved by the material.
In the present invention, an alloy containing 10 to 40% by weight of samarium (Sm) and the balance being substantially iron (Fe) is subjected to a rapid solidification method so that the main phase is between Sm ₅ Fe ₁₇ metals. A samarium-iron-based permanent magnet material is manufactured by a method of refining the structure by applying a heat treatment to the amorphous alloy after forming an amorphous alloy that is a compound phase.
In the present invention, an alloy containing 10 to 40% by weight of samarium (Sm) and the balance being substantially iron (Fe) is subjected to a rapid solidification method so that the main phase is between Sm ₅ Fe ₁₇ metals. The amorphous alloy is a compound phase. A samarium-iron permanent magnet material is manufactured by a method of refining the structure by controlling the cooling rate in the rapid solidification method.

  According to the present invention, a high-performance sintered magnet having a high coercive force can be obtained from a binary alloy of samarium (Sm) and iron.

As a result of intensive investigations into the permanent magnets of new rare earth alloys that do not contain metals other than rare earth metals and 3d transition metals, the inventors have found that Sm ₅ Fe ₁₇ type intermetallic compounds composed of samarium and iron It has been found that it has an indispensable coercive force as a permanent magnet. Further, after producing an amorphous alloy by a rapid solidification method or the like, it has been found that a very fine coercive force is exhibited by heat treatment.

Furthermore, the present inventors have found that even if this Sm ₅ Fe ₁₇ type intermetallic compound composed of samarium and iron is directly made into a fine structure by a rapid solidification method, a high coercive force essential for a permanent magnet is produced.

  This alloy is a metal and can be used as a permanent magnet as it is. Further, like a rare earth magnet or a ferrite magnet, a magnet alloy is pulverized and bonded with a resin or the like, so that it can be used as a bonded magnet.

Example 1
A samarium-iron alloy ingot composed of 22.6 atomic% of samarium (Sm22.6 at%) and 77.4 atomic% of iron (Fe 77.4 at%) was produced by high-frequency melting in an argon atmosphere. The obtained samarium-iron alloy ingot was subjected to a rapid solidification method to produce an amorphous alloy. As the rapid solidification method, a melt spin method was used in which a molten metal in which an alloy ingot was melted at a high frequency in an argon atmosphere was jetted onto a copper roll rotating at a high speed to rapidly cool and solidify. The obtained amorphous alloy was heat-treated at 700 ° C. for 1 hour in an argon atmosphere as a sample. The magnetic properties of the obtained sample were measured. The result is shown in FIG. In FIG. 1, the horizontal axis represents the magnetic field (unit Oe) applied to the sample, and the vertical axis represents the magnetization (unit emu) generated in the sample. The coercive force is a magnetic field when the magnetization becomes zero, that is, the value of the intersection with the horizontal axis of the hysteresis curve. It was found that a sample obtained by heat-treating this amorphous alloy at 700 ° C. for 1 hour showed a very large coercive force of 36.8 kOe.

(Comparative example)
A samarium-iron alloy ingot composed of 22.6 atomic% of samarium (Sm22.6 at%) and 77.4 atomic% of iron (Fe 77.4 at%) was produced by high-frequency melting in an argon atmosphere. The magnetic properties of the samarium-iron alloy ingot and a sample obtained by heat-treating the alloy ingot at 700 ° C. for 1 hour were measured. It was found that the samarium-iron alloy ingot produced by this high frequency melting and the sample subjected to heat treatment showed only a small coercive force of 1 kOe or less.

(Example 2)
A samarium-iron alloy ingot composed of 22.6 atomic% samarium (Sm22.6 at%) and 77.4 atomic% iron (Fe 77.4 at%) was prepared by high-frequency melting in an argon atmosphere. The obtained samarium-iron alloy ingot was subjected to a rapid solidification method to produce an amorphous alloy. As the rapid solidification method, a melt spin method was used in which a molten metal in which an alloy ingot was melted at a high frequency in an argon atmosphere was jetted onto a copper roll rotating at high speed to rapidly solidify. The obtained amorphous alloy was heat-treated at 500 ° C. to 800 ° C. for 1 hour in an argon atmosphere, and the change in coercive force thereof was examined. The results are shown in Table 1.
It was found that a high coercive force can be obtained when the amorphous alloy obtained as described above is subjected to an appropriate heat treatment. In order to investigate the cause of the coercive force, observation with a transmission electron microscope was performed. FIG. 2 shows a structure photograph of a sample (sample showing a very high coercive force of 36800 Oe) obtained by heat-treating an amorphous alloy at 700 ° C. for 1 hour. It was found that a sample obtained by heat-treating this amorphous alloy at 700 ° C. for 1 hour was composed of a very fine Sm ₅ Fe ₁₇ type intermetallic compound phase (crystal grain size of about 10 nm). In addition, when the structure of a sample (sample showing a very high coercive force of 27000 Oe) that was heat-treated at 600 ° C. for 1 hour on an amorphous alloy was also examined with a transmission electron microscope, a very fine Sm ₅ Fe ₁₇ type intermetallic compound was obtained. It was found to consist of a phase (crystal grain size about 100 nm). Furthermore, when the structure of a sample (sample showing a coercive force of 2600 Oe) that was heat-treated at 800 ° C. for 1 hour on an amorphous alloy was examined with a scanning electron microscope, a somewhat larger Sm ₅ Fe ₁₇ type intermetallic compound phase (crystal It was found that the particle size was about 1000-2000 nm. From this, it can be seen that very high coercive force can be obtained when the crystal grain size is 10 nm-100 nm, and it still shows some coercive force even when it exceeds 1000 nm, but not so much coercive force. It was.

Example 3
A samarium-iron alloy ingot composed of 22.6 atomic% samarium (Sm22.6 at%) and 77.4 atomic% iron (Fe 77.4 at%) was prepared by high-frequency melting in an argon atmosphere. The obtained samarium-iron alloy ingot was subjected to a rapid solidification method to produce an amorphous alloy. As the rapid solidification method, a melt spin method was used in which a molten metal in which an alloy ingot was melted at a high frequency in an argon atmosphere was jetted onto a copper roll rotating at high speed to rapidly solidify. When the rotational speed of the copper roll is changed, the cooling speed is changed. Here, an amorphous alloy was obtained when the rotational speed of the copper roll was 30 m / s or more, but an alloy having a fine crystalline with a crystal grain size of 50 to 500 nm was obtained at 10-20 m / s. It was found that the alloy with fine crystallinity produced at a copper roll rotational speed of 10-20 m / s showed a high coercive force similar to the sample obtained by subjecting the amorphous alloy to an appropriate heat treatment. From this, it was found that an alloy having fine crystallinity can be produced not only by heat-treating the amorphous alloy produced by the rapid solidification method but also by directly controlling the cooling rate of the rapid solidification method. In addition, it is clear that a coercive force can be obtained by a person skilled in the art by refining the structure by another manufacturing method such as a gas atomizing method or a mechanical alloying method.

Example 4
A samarium-neodymium-iron alloy ingot in which a portion of samarium in a samarium-iron alloy ingot composed of 22.6 atomic percent (Sm22.6 at%) and iron 77.4 atomic percent (Fe77.4 at%) is replaced by the same rare earth metal, neodymium. Was prepared by high-frequency dissolution in an argon atmosphere. The obtained alloy ingot was subjected to a rapid solidification method to produce an amorphous alloy. The obtained amorphous alloy was heat-treated at 700 ° C. for 1 hour in an argon atmosphere as a sample. The magnetic properties of the obtained sample were measured. The results are shown in Table 2.
It was found that even when a samarium-neodymium-iron amorphous alloy in which a part of samarium of the samarium-iron alloy ingot was replaced by 10-40% with the same rare earth metal, neodymium, was subjected to heat treatment, a large coercive force was exhibited.

(Example 5)
Cobalt (Co), a part of iron of samarium-iron alloy ingot composed of 22.6 atomic% (Sm22.6at%) and 77.4 atomic% (Fe77.4at%) of iron, is known as a magnetic material with the same 3d transition metal A samarium-iron-cobalt alloy ingot substituted with the above was prepared by high-frequency melting in an argon atmosphere. The obtained alloy ingot was subjected to a rapid solidification method to produce an amorphous alloy. The obtained amorphous alloy was heat-treated at 700 ° C. for 1 hour in an argon atmosphere as a sample. The magnetic properties of the obtained sample were measured. The results are shown in Table 3.
Large coercive force even if heat treatment is applied to amorphous alloy of samarium-iron-cobalt alloy in which part of iron of this samarium-iron alloy ingot is substituted with 1 to 50% of cobalt which is known as magnetic material with the same 3d transition metal It was found that

Example 6
An alloy ingot was prepared by adding a small amount of boron and carbon to 1 atom% to a samarium-iron alloy ingot composed of 22.6 atom% (Sm22.6 at%) and 77.4 atom% (Fe77.4 at%) iron. The obtained alloy ingot was subjected to a rapid solidification method to produce an amorphous alloy. The obtained amorphous alloy was heat-treated at 700 ° C. for 1 hour in an argon atmosphere as a sample. When the obtained sample was examined by an X-ray diffraction method, it was found that it was composed of an Sm ₅ Fe ₁₇ type intermetallic compound phase in the same manner as a samarium-iron alloy ingot to which boron and carbon were not added. A comparison of the magnetic properties of the sample that was heat-treated under the same conditions as the one not added showed that the coercive force was slightly improved compared to the one not added.

(Example 7)
A samarium-iron alloy ingot composed of 22.6 atomic% samarium (Sm22.6 at%) and 77.4 atomic% iron (Fe 77.4 at%) was prepared by high-frequency melting in an argon atmosphere. The obtained samarium-iron alloy ingot was subjected to a rapid solidification method to produce an amorphous alloy. As the rapid solidification method, a melt spin method was used in which a molten metal in which an alloy ingot was melted at a high frequency in an argon atmosphere was jetted onto a copper roll rotating at high speed to rapidly solidify. The obtained amorphous alloy was heat-treated at 500 ° C. to 800 ° C. for 0.1 hour in an argon atmosphere, and the change in coercive force thereof was examined. The results are shown in Table 4.
The coercive force at a high temperature (800 ° C.) is larger than that of a sample (Table 1) subjected to heat treatment at 500 ° C. to 800 ° C. for 1 hour in an argon atmosphere. This is because the heat treatment time is short, so that the sample was obtained as fine as possible without coarsening the crystal grains. Thus, it has been found that changing the heat treatment time gives the same result as changing the heat treatment temperature. From this, it was found that a high coercive force can be obtained when the obtained amorphous alloy is heat-treated under a heat treatment condition in which an appropriate heat treatment time and heat treatment temperature are selected.

It is a table | surface graph about the hysteresis curve of the sample which heat-processed the samarium iron alloy produced by the melt spin method. It is the structure | tissue photograph which observed the sample which heat-processed the samarium iron alloy produced by the melt spin method with the transmission electron microscope, and its electron diffraction pattern.

Claims (4)

Samarium (Sm) comprise 10-40% by atomic percentage, and the balance of iron (Fe), main phase Sm ₅ Fe ₁₇ intermetallic phase der is, the crystal grain size 10 nm to 1000 nm of the fine structure samarium characterized Rukoto that have a - iron permanent magnet material.   2. The samarium-iron permanent according to claim 1, wherein a part of samarium (Sm) is substituted with another rare earth metal element (R) to contain R: 10 to 40% in atomic percentage. Magnet material.   The samarium-iron-based permanent magnet material according to claim 1 or 2, wherein Co is contained in an atomic percentage of 1 to 50% by substituting a part of Fe with cobalt (Co).   A nonmetallic element X (X is one or a combination of two or more of nitrogen (N), boron (B), and carbon (C)) is contained in an amount of 0.1 to 5.0% for refining crystal grains. Item 4. The samarium-iron permanent magnet material according to any one of Items 1 to 3.