JP2022025181A - Rapidly solidified product of rare earth-iron-boron type alloy, magnetic refrigerator arranged by use thereof, and method for manufacturing rapidly solidified permanent magnet made of phases of intermetallic compound re2iron14boron - Google Patents

Abstract

To provide a permanent magnet which is proper for use at an extremely low temperature suitable for liquefaction of N2, H2, He, etc.SOLUTION: A permanent magnet comprises a rapidly solidified product of a crystal grain-like rare earth-iron-boron intermetallic material having a substantially stable magnetic property, and molded as an effective ferromagnetic phase, of which the compositional formula is given by {(NdzPr1-z)1-xLREx}2y-(FewCo1-w)14-B, where 0.0≤x≤0.5, 1.0≤y≤1.22, 0.0≤z≤0.8 and 0.0≤w≤0.8, and light rare earth LRE includes an effective amount of a light rare earth element selected from a group consisting of cerium (Ce), lanthanum (La), yttrium (Y) and their mixtures. The permanent magnet has a maximum energy product of 250 (kJ/m3) or more in a temperature range from 4K to 135K.SELECTED DRAWING: Figure 3

Description

The present invention relates to a quenching solidification product of a rare earth-iron-boron type alloy, a magnetic refrigerating apparatus using the quenching solidification product, and a method for producing a quenching solidification permanent magnet composed of an intermetallic compound RE ₂ Fe ₁₄ B phase.

Magnetic refrigeration (MR) is considered to be a promising next-generation energy _- efficient and environmentally friendly refrigeration technology that can be used at cryogenic temperatures for the liquefaction of _N2 , H2, and He. Magnetic refrigeration uses the giant magnetocaloric effect (MCE) of magnetic calorific materials. In this magnetic calorific material, when an external magnetic field is applied, the material undergoes an isothermal change in magnetic entropy (ΔSM) or an adiabatic change in temperature (ΔTad). In the case of cryogenic magnetic refrigeration (CMR), superconducting magnets are used to provide a large external magnetic field (> 5T) to the magnetic material. Since this is premised on the inadequate magnetic calorific value of known magnetic calorie materials, the giant magnetic calorie effect can only be achieved by applying a large external magnetic field of as much as 5T.

On the other hand, Patent Documents 1 and 2 propose a material composition of a high-performance magnetic magnet of iron-boron-rare earth type (Fe-B-RE) and a manufacturing method by powder metallurgy. This was developed to replace rare earth cobalt magnets, and samarium (Sm) and cobalt (Co) were more expensive than ferrite at the resource price at that time, so iron is cheaper than cobalt (Co). (Fe) and neodymium (Nd) are adopted. Further, in Patent Document 3, neodymium (Nd) suitable for use in a magnetic resonance imaging (MRI) or a computer is partially replaced with praseodymium (Pr) or cerium (Ce), and the amount of neodymium used is described. Reduced high-performance permanent magnets have been proposed. With regard to rare earths, there was a time when resource prices soared around 2011 and it became difficult to obtain them, and the material composition of high-performance magnetic magnets with alternative elemental compositions is being sought.

Further, as disclosed in Non-Patent Documents 1 to 3, the present inventor is searching for a neodymium-iron-boron type (Nd-Fe-B) high-performance magnetic magnet material. And, a permanent magnet material that exhibits sufficient coercive force, large residual magnetization, and maximum energy product even at extremely low temperatures required for liquefaction of natural gas, _N2 , H2, and He, which is suitable for magnetic refrigeration ₍ MR) applications. We are aware of the need for exploration.
On the other hand, in the Nd-Fe-B based magnet, the saturation magnetization of the Nd ₂ Fe ₁₄ B compound is large, and μ ₀ Ms = 1.61 T at room temperature, so that the maximum energy product (BH) is the maximum at room temperature (RT). ) It is known to show max. This makes anisotropic Nd-Fe-B based magnets the most important industrial permanent magnets due to their wide range of applications. However, the spin reorientation of the Nd ₂ Fe ₁₄ B compound at about 135 K deteriorates the demagnetization curve of the anisotropic Nd-Fe-B sintered magnet, making these materials unsuitable for cryogenic applications. There was a problem.

In Non-Patent Document 4, (Nd _0.5 Pr _0.5 ) _12.9 Dy0.4Fe _74.3 Co _6.7 B _5.7 hot deformed magnet, 1.58T at 75K. Residual magnetization was reported and it is stated that a very small spin reorientation effect was observed. To generalize the results of this experiment, one way to suppress spin reorientation of Nd-Fe-B magnets is to replace neodymium with other rare earth elements such as dysprosium (Dy) and Pr.

U.S. Pat. No. 4,648,406 U.S. Pat. No. 4,509,938 Special table 2003-525345

Xin Tang, H. Sepehri-Amin, M. Matsumoto, T. Ohkubo, K. Hono, Acta Materialia 175 (2019) 1-10. Xin Tang, H. Sepehri-Amin, T. Ohkubo, K. Hono, Scripta Materialia 147 (2018) 108-113. Xin Tang, J. Li, Y. Miyazaki, H. Sepehri-Amin, T. Ohkubo, T. Schrefl, K. Hono, Acta Materialia 183 (2020) 408-417 D. Hinz, et. Al., J. Magn. Magn. Mater. 272-276 (2004) e321-e322

In the conventional cryogenic magnetic refrigeration system, a large magnetic field (> 5T) is required for the magnetic material in order to realize a huge MCE by using a superconducting magnet. However, miniaturization using a permanent magnet magnetic source is indispensable for room temperature cooling assuming applications for home appliances and air conditioners. If the ultra-low temperature magnetic cooling can be performed under a low magnetic field of about 1 to 2 T that can be generated by a permanent magnet, the manufacturing and maintenance costs of the ultra-low temperature magnetic refrigeration apparatus can be significantly reduced.

In recent years, magnetic calorific materials have been developed in which a sufficient change in magnetic entropy can be seen in a magnetic field of about 1 to 2 T. With conventional CMR materials such as DyFeAl and DyIn ₂ , the externally applied magnetic field required to generate a change in magnetic entropy reaches 5 T, but a sufficient magnetic entropy change can be seen in the above-mentioned magnetic field of about 1 to 2 T. If a magnetic calorific material with an excellent magnetic calorific effect can be developed, there will be room for using permanent magnets for ultra-low temperature magnetic refrigeration applications instead of expensive superconducting magnets. The iron-boron-rare earth type (Fe-B-RE) high-performance permanent magnet can generate a residual magnetic field of about 1.45 T at room temperature, and by strengthening the saturation magnetization at low temperature, a larger magnetic field can be generated at extremely low temperature. Expected to generate. In the case of an external magnetic field generated by a permanent magnet, this value may vary between 1.0 and 2.0 T, depending on the system design and the gap distance from the permanent magnet. That is, it shows that iron-boron-rare earth type (Fe-B-RE) high-performance permanent magnets have the potential to replace expensive superconducting magnets.

However, in Non-Patent Documents 1 to 4, the spin reorientation of the Nd ₂ Fe ₁₄ B compound at about 135 K is overcome, and the extremely low temperature required for liquefaction of N ₂ , H ₂ and He is about 1 to 2 T. There is no description about the magnetic material to which a relatively low external magnetic field can be applied.
An object of the present invention is to solve such a problem, and by using it together with a magnetic calorific material in which a sufficient entropy change is observed in an external magnetic field of about 1 to 2 T, natural gas, N ₂ , H ₂ , He, etc. It is an object of the present invention to provide a magnetic material suitable for use at an extremely low temperature, which is suitable for liquefaction of gas.

As a result of diligent research to solve the above problems, the present inventor was subjected to Pr-Fe-B and partially Ce-replacement by the liquid quenching method and the subsequent hot deformation processing (Pr, Ce)-. Fe-B anisotropic permanent magnets were prepared and their hard magnetism as ultra-low temperature permanent magnets was investigated. Surprisingly, (Pr _0.75 Ce _0.25 ) -Fe-B hot-worked magnets are superior permanent at very low temperatures compared to Nd-Fe-B and Pr-Fe-B based magnets. It was found that it exhibits magnetic properties, and the present invention was completed.

[1] The quenching solidification product of the present invention is a quenching solidification product containing a rare earth-iron-boron type alloy, and the composition formula of the alloy is {(Nd _z Pr _1-z ) _1-x LRE _x . } _2y- (Fe _w Co _1-w ) ₁₄ -B; 0.0≤x≤0.5, 1.0≤y≤1.22, 0.0≤z≤0.8, 0.0≤w Pre-cooled solidification formation with ≤0.8, where the light rare earth LRE contains an effective amount of light rare earth selected from the group consisting of cerium (Ce), lantern (La), yttrium (Y), and mixtures thereof. It is a thing and has a maximum energy product of 250 (kJ / m ³ ) or more in the temperature range of 4K to 135K.
[2] In the quenching solidification product of the present invention, it is preferably a quenching solidification product containing a rare earth-iron-boron type alloy, and the composition formula of the alloy is {(Nd _z Pr _1-z ) _1- . _x LRE _x } _2y- (Fe _w Co _1-w ) ₁₄ -B; 0.05 ≦ x ≦ 0.45, 1.03 ≦ y ≦ 1.17, 0.0 ≦ z ≦ 0.6, 0. 0 ≦ w ≦ 0.5 and the light rare earth LRE contains an effective amount of light rare earth selected from the group consisting of cerium (Ce), lanthanum (La), yttrium (Y), and mixtures thereof. It is a quenching solidification product and preferably has a maximum energy product of 500 (kJ / m ³ ) or more in the temperature range of 4K to 135K.
[3] In the quenching solidification product of the present invention, it is preferably a quenching solidification product containing a rare earth-iron-boron type alloy, and the composition formula of the alloy is {(Nd _z Pr _1-z ) _1-x . LRE _x } _2y- (Fe _w Co _1-w ) ₁₄ -B; 0.20≤x≤0.30, 1.07≤y≤1.14, 0.0≤z≤0.4, 0.0 ≤w≤0.3, where the light rare earth LRE is quenched with an effective amount of light rare earth selected from the group consisting of cerium (Ce), lanthanum (La), yttrium (Y), and mixtures thereof. It is a solidification product and has a residual magnetization in the temperature range of 4K to 135K with a maximum value of 1.6T at 135K and 1.4T at 4K, and has a maximum energy product of 500 (kJ) in the temperature range of 4K to 135K. It is preferable to have a value of / m ³ ) or more.

[4] The isotropic alloy material of the present invention is an isotropic alloy material of a rare earth-iron-boron type alloy, and the composition formula is {(Nd _z Pr _1-z ) _1-x LRE _x } _2y . -(Fe _w Co _1-w ) ₁₄ -B; 0.0≤x≤0.5, 1.0≤y≤1.22, 0.0≤z≤0.8, 0.0≤w≤0 8.8, the light rare earth LRE contains an effective amount of light rare earth selected from the group consisting of cerium (Ce), lantern (La), ittrium (Y), and mixtures thereof, and isotropic as described above. The maximum energy product in the temperature range of 4K to 135K is 250 (when quenched and solidified as an anisotropic permanent magnet consisting of substantially magnetically aligned RE2Fe14B square crystal grains using an alloy material. It has a value of kJ / m ³ ) or higher.
[5] In the isotropic alloy material of the present invention, it is preferably an isotropic alloy material of a rare earth-iron-boron type alloy, and the composition formula is {(Nd _z Pr _1-z ) _1-x LRE. _x } _2y- (Fe _w Co _1-w ) ₁₄ -B; 0.05 ≦ x ≦ 0.45, 1.03 ≦ y ≦ 1.17, 0.0 ≦ z ≦ 0.6, 0.0 ≦ w ≦ 0.5 and the light rare earth LRE comprises an effective amount of light rare earth selected from the group consisting of cerium (Ce), lantern (La), ittrium (Y), and mixtures thereof. Maximum energy product in the temperature range of 4K to 135K when quenched and solidified as an anisotropic permanent magnet consisting of substantially magnetically aligned RE2Fe14B square crystal grains using an isotropic alloy material. It is preferable that the value is 500 (kJ / m ³ ) or more.
[6] In the isotropic alloy material of the present invention, it is preferably an isotropic alloy material of a rare earth-iron-boron type alloy, and the composition formula is {(Nd _z Pr _1-z ) _1-x LRE _x . } _2y- (Fe _w Co _1-w ) ₁₄ -B; 0.20≤x≤0.30, 1.07≤y≤1.14, 0.0≤z≤0.4, 0.0≤w ≤0.3 and the light rare earth LRE contains an effective amount of light rare earth selected from the group consisting of cerium (Ce), lantern (La), ittrium (Y), and mixtures thereof, and the like. Remaining magnetization in the temperature range of 4K to 135K is 135K when rapidly cooled and solidified as an anisotropic permanent magnet consisting of RE2Fe14B square crystal grains that are substantially magnetically aligned using a square alloy material. It is preferable to have a maximum value of 1.6 T at 4K, 1.4 T at 4K, and a value having a maximum energy product of 500 (kJ / m ³ ) or more in the temperature range of 4K to 135K.

[7] The anisotropic permanent magnet of the present invention is a rare earth-iron-boron type anisotropic permanent magnet, and the composition formula is {(Nd _z Pr _1-z ) _1-x LRE _x } _2y- . (Fe _w Co _1-w ) ₁₄ -B; 0.0 ≦ x ≦ 0.5, 1.0 ≦ y ≦ 1.22, 0.0 ≦ z ≦ 0.8, 0.0 ≦ w ≦ 0. 8. The light rare earth LRE contains an effective amount of light rare earth selected from the group consisting of cerium (Ce), lantern (La), ittrium (Y), and a mixture thereof, and is substantially magnetic. It consists of RE2Fe14B square crystal grains aligned with and has a maximum energy product of 250 (kJ / m ³ ) or more in the temperature range of 4K to 135K.
[8] The anisotropic permanent magnet of the present invention is preferably a rare earth-iron-boron type anisotropic permanent magnet having a composition formula of {(Nd _z Pr _1-z ) _1-x LRE _x }. _2y- (Fe _w Co _1-w ) ₁₄ -B; 0.05 ≦ x ≦ 0.45, 1.03 ≦ y ≦ 1.17, 0.0 ≦ z ≦ 0.6, 0.0 ≦ w ≦ At 0.5, the light rare earth LRE contains substantially an effective amount of light rare earth selected from the group consisting of cerium (Ce), lantern (La), ittrium (Y), and mixtures thereof. It is preferably composed of magnetically aligned RE2Fe14B square crystal grains and has a maximum energy product of 500 (kJ / m ³ ) or more in the temperature range of 4K to 135K.
[9] The anisotropic permanent magnet of the present invention is preferably a rare earth-iron-boron type anisotropic permanent magnet and has a composition formula of {(Nd _z Pr _1-z ) _1-x LRE _x . } _2y- (Fe _w Co _1-w ) ₁₄ -B; 0.20≤x≤0.30, 1.07≤y≤1.14, 0.0≤z≤0.4, 0.0≤w ≤0.3, the light rare earth LRE contains a valid amount of light rare earth selected from the group consisting of cerium (Ce), lantern (La), ittrium (Y), and mixtures thereof, substantially. Composed of RE2Fe14B square crystal grains magnetically aligned with, the residual magnetization in the temperature range of 4K to 135K has a maximum value of 1.6T at 135K, 1.4T at 4K, and 4K to 135K. It is preferable that the maximum energy product in the temperature range has a value of 500 (kJ / m ³ ) or more.

[10] The permanent magnet of the present invention has substantially stable magnetic properties and has a quenching solidification product of a molded crystalline grain rare earth-iron-boron metal material as an effective ferromagnetic phase. In the case of a magnet, the composition formula of the quenching solidification product is {(Nd _z Pr _1-z ) _1-x LRE _x } _2y- (Fe _w Co _1-w ) ₁₄ -B; 0.0≤x≤ 0.5, 1.0 ≦ y ≦ 1.22, 0.0 ≦ z ≦ 0.8, 0.0 ≦ w ≦ 0.8, and the light rare earth LRE is cerium (Ce), lantern (La). ), Ittrium (Y), and an effective amount of light rare earth selected from the group consisting of a mixture thereof, and has a maximum energy product of 250 (kJ / m ³ ) or more in the temperature range of 4K to 135K. ..
[11] In the permanent magnet of the present invention, preferably, the composition formula is {(Nd _z Pr _1-z ) _1-x LRE _x } _2y- (Fe _w Co _1-w ) ₁₄ -B; 0.05 ≦ x ≦ 0.45, 1.03 ≦ y ≦ 1.17, 0.0 ≦ z ≦ 0.6, 0.0 ≦ w ≦ 0.5, and the light rare earth LRE is cerium (Ce), lantern. A value with a maximum energy product of 500 (kJ / m ³ ) or greater in the temperature range of 4K to 135K, including an effective amount of light rare earths selected from the group consisting of (La), yttrium (Y), and mixtures thereof. It is good to have.
[12] In the permanent magnet of the present invention, preferably, the composition formula is {(Nd _z Pr _1-z ) _1-x LRE _x } _2y- (Fe _w Co _1-w ) ₁₄ -B; 0.20 ≦ x ≦ 0.30, 1.07 ≦ y ≦ 1.14, 0.0 ≦ z ≦ 0.4, 0.0 ≦ w ≦ 0.3, and the light rare earth LRE is cerium (Ce), lantern. Containing an effective amount of light rare earth selected from the group consisting of (La), yttrium (Y), and mixtures thereof, consisting of substantially magnetically aligned RE2Fe14B square crystal grains, 4K to 135K. The residual magnetism in the temperature range of 135K has a maximum value of 1.6T, 4K has a maximum value of 1.4T, and the maximum energy product in the temperature range of 4K to 135K has a value of 500 (kJ / m ³ ) or more. It is good to do it.

[13] The quenching and solidifying permanent magnet material of the present invention is an ultrafine particle size rare earth-iron-boron alloy, and the iron, boron, and rare earth substantially correspond to the amount desired for the quenching and solidifying permanent magnet material. An alloy ingot consisting of an intermetallic phase having the composition of rare earth-iron-boron is produced by a liquid quenching method, and the alloy ingot produced by the liquid quenching method is crushed to form a fine earth rare earth-. An iron-boron alloy is prepared, and the composition formula is {(Nd _z Pr _1-z ) _1-x LRE _x } _2y- (Fe _w Co _1-w ) ₁₄ -B; 0.0 ≦ x ≦ 0. .5, 1.0 ≦ y ≦ 1.22, 0.0 ≦ z ≦ 0.8, 0.0 ≦ w ≦ 0.8, and the light rare earth LRE is cerium (Ce), lantern (La). Contains an effective amount of light rare earths selected from the group consisting of, yttrium (Y), and mixtures thereof, and has a maximum energy product of 250 (kJ) in the temperature range of 4K to 135K when quenched and solidified as a permanent magnet. It has a value of / m ³ ) or more, and is for hot-compressing the fine-grained alloy to produce a rapidly cooled solidified permanent magnet having a predetermined shape.
[14] In the rapidly cooled solidified permanent magnet material of the present invention, preferably, the composition formula is {(Nd _z Pr _1-z ) _1-x LRE _x } _2y- (Fe _w Co _1-w ) ₁₄ -B; 0. .05 ≦ x ≦ 0.45, 1.03 ≦ y ≦ 1.17, 0.0 ≦ z ≦ 0.6, 0.0 ≦ w ≦ 0.5, and the light rare earth LRE is cerium (Ce). ), Lantern (La), yttrium (Y), and an effective amount of light rare earth selected from the group consisting of a mixture thereof, and the maximum in the temperature range of 4K to 135K when quenched and solidified as a permanent magnet. It is preferable that the energy product has a value of 500 (kJ / m ³ ) or more.
[15] In the rapidly cooled solidified permanent magnet material of the present invention, preferably, the composition formula is {(Nd _z Pr _1-z ) _1-x LRE _x } _2y- (Fe _w Co _1-w ) ₁₄ -B; 0. .0≤x≤0.5, 1.0≤y≤1.22, 0.0≤z≤0.4, 0.0≤w≤0.3, and the light rare earth LRE is cerium (Ce). ), Lantern (La), yttrium (Y), and an effective amount of light rare earth selected from the group consisting of a mixture thereof, which remains in the temperature range of 4K to 135K when rapidly cooled and solidified as a permanent magnet. It is preferable that the magnetization has a maximum value of 1.6T at 135K, 1.4T at 4K, and the maximum energy product in the temperature range of 4K to 135K has a value of 500 (kJ / m ³ ) or more.

[16] The magnetic refrigerating apparatus of the present invention comprises the quenching solidification products described in [1] to [3], the isotropic alloy materials described in [4] to [6], and [7] to [9]. The anisotropic permanent magnets described above, the anisotropic permanent magnets described in [10] to [12], or the rare earth-iron-boron type quenching solidified permanent magnet materials described in [13] to [15] were used. It is a thing.
[17] The method for producing a rare earth-iron-boron type quench-solidifying permanent magnet of the present invention is an alloy of rare earth-iron-boron in the form of fine particles, and the fine particles have the composition of the rare earth-iron-boron. Includes a step of producing an alloy ingot consisting of an intermetall phase having The fine particles have an average particle size of up to about 60 microns, and the alloy fine particles are essentially {(Nd _z Pr _1-z ) _1-x LRE _x } _2y- (Fe _w Co _1-w ). ₁₄ -B; 0.0 ≦ x ≦ 0.5, 1.0 ≦ y ≦ 1.22, 0.0 ≦ z ≦ 0.8, 0.0 ≦ w ≦ 0.8, and light rare earth LRE Has a composition consisting of an effective amount of light rare earth selected from the group consisting of cerium (Ce), lanthanum (La), ittrium (Y), and mixtures thereof, and hot-compresses the finely divided alloy. The method includes a step of compressing and deforming into a quenching and solidifying permanent magnet having a predetermined shape to produce a quenching and solidifying permanent magnet. be.

According to the (Pr, Ce) -Fe-B magnetic material as a quenching solidification product of the rare earth-iron-boron type alloy of the present invention, the maximum energy product in the temperature range of 4K to 135K is 500 (kJ / m ³ ). Since it has the above values, it is suitable for applying a relatively low external magnetic field of about 1 to 2 T at an extremely low temperature required for liquefaction of N ₂ , H ₂ , and He. Further, it is more suitable if the residual magnetization in the temperature range of 4K to 135K has a maximum value of 1.6T at 135K and 1.4T at 4K when it is rapidly cooled and solidified as a permanent magnet.
According to the magnetic refrigeration apparatus using the (Pr, Ce) -Fe-B magnetic material of the present invention, a magnetic material having a maximum energy product of 500 (kJ / m ³ ) or more in a temperature range of 4K to 135K can be obtained. Since it is used, it is suitable for applying a relatively low external magnetic field of about 1 to 2 T at an extremely low temperature required for liquefaction of N ₂ , H ₂ , and He.
According to the method for producing a quenching solidification permanent magnet composed of the intermetallic compound RE2Fe14B phase of the present invention, Pr-Fe-B and Partially Ce were substituted by the liquid quenching method and the subsequent hot deformation processing (Pr, Ce). ) -Fe-B anisotropic permanent magnets can be manufactured, and permanent magnets exhibiting excellent permanent magnetic properties at extremely low temperatures can be manufactured as compared with Nd-Fe-B and Pr-Fe-B based magnets.

In the hysteresis loop of residual magnetization showing one embodiment of the present invention, (a) is an anisotropic Nd-Fe-B thermally deformable magnet, (b) is Pr-Fe-B, and (c) is (Pr, Ce). -Indicates a Fe-B magnet. Further, for Nd-Fe-B, Pr-Fe-B, and (Pr, Ce) -Fe-B magnets, (d) shows coercive force, (e) shows residual magnetization, and (f) shows saturation magnetization. .. In the low-magnification and high-magnification BSE-SEM images showing one embodiment of the present invention, (a) and (d) are anisotropic hot-deformed Nd-Fe-B magnets, and (b) and (e) are anisotropic. Sexual hot deformation Pr-Fe-B magnets, (c) and (f) indicate anisotropic hot deformation (Pr, Ce) -Fe-B magnets. It is a figure of the maximum energy product (BH) max vs. temperature of an anisotropic RE-Fe-B magnet which shows one Embodiment of this invention. For comparison, the (BH) max values of the anisotropic Nd _0.5 Pr _0.5 -Fe-B and Nd _0.75 Pr _0.25 -Fe-B magnets are also shown.

Hereinafter, the present invention will be described with reference to the drawings.

An alloy ingot having a composition of RE _13.1 Fe _80.05 Ga _0.5 B _5.81 (at%) (RE = Nd, Pr) was prepared by dissolving high-purity constituent elements. The alloy ingot was manufactured by the liquid quenching method at 30 m / s. In the liquid quenching method, a molten metal of a raw material alloy is jetted from a nozzle onto a rotating metal roll and rapidly cooled to form a thin band. By making it a quenching thin body, fine Nd-Fe-B type crystals are generated. Then, the thin body is crushed into powder to obtain a magnetic powder for developing an anisotropic bulk magnet having a large residual magnetic flux density and coercive force required for a permanent magnet.
The quenched and thinned ribbon was pulverized into flakes sized to 20-50 μm and hot pressed in vacuum at 380 MPa at 650 ° C. Hot pressed magnets were hot deformed at 800 ° C. to achieve a height reduction of 75%. Hot pressing is used to fill powder with high density and obtain high magnetization and residual magnetic flux density. On the other hand, in hot working such as the diapset method, the crystal grains have a flat shape extending in the direction perpendicular to the pressurizing direction, and the c-axis direction, which is the easy axial direction of the Nd ₂ Fe ₁₄ B phase, is added. The crystals are arranged so as to be parallel to the compression direction. The developed magnet is an anisotropic Nd-Fe-B bulk magnet having a perfect density and having an ultrafine crystal grain size.
Hereinafter, the (Pr, Ce) -Fe-B magnet having a composition of (Pr _0.75 Ce _0.25 ) _12.77 Fe _80.02 Ga _0.5 B _5.81 (at%) is (Pr, Ce). It is displayed as Ce) -Fe-B, and was also prepared as a low-cost permanent magnet. The total rare earth content of the (Pr, Ce) -Fe-B alloy composition is slightly smaller than the total rare earth content of Nd-Fe-B and Pr-Fe-B in order to maximize the residual magnetization.

The cryogenic magnetic properties were investigated by a program performance measurement systems (PPMS) with a maximum magnetic field of 14T. The microstructure of the anisotropic heat-deformed magnet was investigated using a scanning electron microscope (SEM) and Carl Zeiss CrossBeam 1540EsB, respectively. The Carl Zeiss CrossBeam1540EsB combines the imaging and analysis functions of a high-resolution field emission scanning electron microscope (FE-SEM) with the processing functions of a focused ion beam (FIB).

FIG. 1A shows a hysteresis loop of an anisotropic Nd-Fe-B hot-worked magnet measured at 300 to 20 K. The kink in the second quadrant of the hysteresis loop can only be observed with an anisotropic Nd-Fe-B magnet when the temperature drops below 150 K. This is because the magnetization facilitation axis direction changes from one axis to a cone due to the spin direction of the Nd ₂ Fe ₁₄ B compound.
1 (b) and 1 (c) show the magnetization in the temperature range of 300-20K obtained from the anisotropic hot-worked Pr-Fe-B magnet and the (Pr, Ce) -Fe-B magnet, respectively. It shows a curve. Unlike hot-worked Nd-Fe-B magnets, both the Pr-Fe-B magnets at very low temperatures and the (Pr, Ce) -Fe-B magnets have good kinks-free squareness in the hysteresis loops. Observed.
1 (d)-(f) show the temperature dependence of the coercive force, the residual magnetization, and the saturation magnetization obtained from the Nd-Fe-B, Pr-Fe-B and (Pr, Ce) -Fe-B magnets, respectively. Shows sex. The coercive force of these samples continues to increase as the temperature decreases, due to the temperature dependence of the anisotropic magnetic field. Unlike the temperature-dependent tendency of the coercive force of Nd-Fe-B magnets, the coercive force of Pr-Fe-B rapidly increases from 1.72T at 300K to 8.52T at 20K.

By substituting 25 at% Pr with Ce, the coercive force of the (Pr, Ce) -Fe-B magnet reaches 4.8 T at 20K, which is comparable to the coercive force of the Nd-Fe-B magnet. This result shows that when RE of RE ₂ Fe ₁₄ B is replaced with Ce, the coercive force of the permanent magnet decreases in high temperature applications. The addition of Ce reduces the cost of the magnet and allows a large residual magnetization with a sufficiently high coercive force to be obtained at 20K. Since the coercive force can be kept high at an extremely low temperature, the total rare earth content of the (Pr, Ce) -Fe-B alloy can be reduced while maintaining the saturation magnetization comparable to that of the Pr-Fe-B magnet.

As shown in FIG. 1 (d), the saturation magnetization μ ₀ Ms measured at 14T of these three types of permanent magnets first increases when the temperature drops from 300 K, reaches a peak at 125 K, and then further. It decreases when the temperature is lowered to 20K. This is due to the very large anisotropic magnetic field at low temperatures, so the applied 14T magnetic field is not sufficient to saturate the magnetization and the measurements remain in a minor loop at very low temperatures. To obtain accurate remanent magnetization, these three samples are saturated only once under a magnetic field of 14T at room temperature, then the temperature dependence of the remanence magnetization ranges from 300K to 20K without resaturating the magnets. Be measured. Due to the spin reorientation effect, the residual magnetization of Nd-Fe-B increased from 1.45T at 300K to 1.59T at 200K, then slightly decreased to 1.58T at 125K and 1.41T at 20K.

In contrast, the remanent magnetization of Pr-Fe-B and (Pr, Ce) -Fe-B hot-worked magnets continuously increases at 20K to 1.71T and 1.76T, respectively. The residual magnetization of the (Pr, Ce) -Fe-B magnet is slightly higher than the residual magnetization of the Pr-Fe-B magnet. This is because the content of rare earths is low.
Recently, Non-Patent Document 2 reports that when Nd is replaced with Ce by 20% or more, the magnetization of the (Nd, Ce) -Fe-B magnet is slightly reduced. However, this can be compensated for by slightly reducing the total rare earth content at the expense of coercive force. Here, in order to reduce the cost of permanent magnets, Pr was replaced with 25 at% Ce to slightly reduce the total content of rare earths and increase the magnetization.
Nevertheless, the anisotropic (Pr, Ce) -Fe-B magnet provides a sufficient coercive force of 0.85 T even at room temperature, and the residual magnetic flux density is slightly higher than that of the Pr-Fe-B magnet. An increased 1.45T is obtained. The Mr / Ms ratio at room temperature is calculated to be about 0.91 for Nd-Fe-B magnets, about 0.89 for Pr-Fe-B magnets, and 0.935 for (Pr, Ce) -Fe-B magnets. Will be done.

2 (a)-(c) show backscattered electron scanning electron microscopes (BSE SEMs) of anisotropic Nd-Fe-B, Pr-Fe-B, and (Pr, Ce) -Fe-B hot deforming magnets. ) Shows a low magnification image. Bright contrast rare earth oxides (REOx) can be observed alongside the interface of the original flake surface, as is commonly observed with Nd—Fe—B group hot-worked magnets (Non-Patent Documents 1 and 3). reference). Based on the contrast, the area ratio of the bright contrast rare earth-rich phase is about 1.2% for Nd-Fe-B magnets, about 1.0% for Pr-Fe-B magnets, (Pr, Ce) -Fe. -B magnet is 0.6%. This difference can be explained by the total rare earth content in the alloy composition of the three samples.

High-magnification BSE-SEM images obtained from anisotropic Nd-Fe-B, Pr-Fe-B, (Pr, Ce) -Fe-B hot-worked magnets are shown in FIGS. 2 (d) to 2 (f). It is shown. The plate-like particles are formed in a fine structure covered with a RE-rich intergranular phase.
The average particle size of Nd ₂ Fe ₁₄ B calculated from FIG. 2 (d) is ~ 473 nm (Dc) along the c-plane and ~ 136 nm (Dab) in the direction perpendicular to the c-plane. This slightly changes to ~ 455 nm (Dc) and ~ 141 nm (Dab) in the Pr-Fe-B magnet shown in FIG. 2 (e), and (Pr, Ce) -Fe-B shown in FIG. 2 (f). For magnets, it is significantly reduced to ~ 253 nm (Dc) and ~ 116 nm (Dab).

In this experiment, the cryogenic magnetic properties of two types of 2: 14: 1 permanent magnets were systematically investigated.
In the case of Nd-Fe-B magnets, the residual magnetic flux density increases from 1.45T at 300K to 1.59T at 200K, and pin reorientation occurs at about 130K, so it decreases significantly to 1.41T at 20K. , Nd-Fe-B type magnets are not suitable for ultra-low temperature applications.

In contrast, the residual magnetization of the Pr-Fe-B hot-worked magnet continuously increased from 1.43T at 300K to 1.71T at 20K, which was the grain boundary diffusion treated Pr-Fe-B. It is superior to quenching solidifying magnets and much larger than the Nd _0.75 Pr _0.25 -Fe-B alloy of isotropic nanocrystals. As a result, as shown in FIG. 3, a maximum energy product (BH) max of 570 kJ / m ³ or more can be obtained at a temperature of 20 to 60 K. The maximum energy product (BH) max was calculated from hysteresis loops at various temperatures after normalizing the residual magnetization μ ₀ Mr value to the value obtained in the residual magnetization state, as shown in FIG. An equivalent maximum energy product (BH) max of 385 kJ / m ³ has been reported for Nd _0.5 Pr _0.5 5-Fe-B quenching solidification magnets at about 300 K. However, since Pr was partially replaced by Nd, the value of the maximum energy product (BH) max became much smaller at low temperatures.

This experiment shows that a hot deformed Pr-Fe-B magnet can achieve a coercive force of 1.72 T at room temperature. This is because the coercive force increases above 8.0T at very low temperatures and the total rare earth content is further reduced to maximize residual magnetization, or Pr is replaced with lighter rare earths to sacrifice the coercive force at room temperature. It suggests that the cost can be reduced.
Based on this, the composition of the Pr-Fe-B based magnet was further optimized, and in the (Pr, Ce) -Fe-B magnet, the residual magnetization of about ~ 1.75T and the maximum energy product (BH) max 610kJ / m. ³ was achieved in the temperature range of 20-60K.
Instead of expensive superconducting magnets, these magnets are not only cheap candidates for magnetic field sources, but can also add portability benefits to cryogenic magnetic refrigeration systems.

Although the embodiments shown in FIGS. 1 to 3 are shown as examples of the present invention, the present invention is not limited thereto, and various embodiments can be considered within a range obvious to those skilled in the art. Therefore, such a trivial scope is also included in the scope of rights of the present invention.

As described in detail above, according to the (Pr, Ce) -Fe-B magnetic material as a quenching solidification product of the rare earth-iron-boron type alloy of the present invention, an external magnetic field of about 1 to 2 T is sufficient. It is suitable for liquefaction of _N2 , H2, He, etc. by using it _together with a magnetic calorific material that shows an entropy change.
Further, according to the magnetic refrigeration device using the (Pr, Ce) -Fe-B magnetic material of the present invention, when used together with the magnetic calorific value material in which a sufficient entropy change is observed in an external magnetic field of about 1 to 2 T, N _2. Suitable for liquefaction of _H2 , He and the like.

Claims (17)

It is a quenching solidification product of a rare earth-iron-boron type alloy, and the composition formula of the alloy is
{(Nd _z Pr _1-z ) _1-x LRE _x } _2y- (Fe _w Co _1-w ) ₁₄ -B;
0.0 ≦ x ≦ 0.5, 1.0 ≦ y ≦ 1.22, 0.0 ≦ z ≦ 0.8, 0.0 ≦ w ≦ 0.8
The light rare earth LRE is a quenching solidification product containing an effective amount of light rare earth selected from the group consisting of cerium (Ce), lanthanum (La), yttrium (Y), and mixtures thereof. A quenching solidification product having a maximum energy product of 250 (kJ / m ³ ) or more in the temperature range of 4K to 135K. It is a rare earth-iron-boron type alloy quenching solidification product, and the composition formula of the alloy is
{(Nd _z Pr _1-z ) _1-x LRE _x } _2y- (Fe _w Co _1-w ) ₁₄ -B;
0.05 ≦ x ≦ 0.45, 1.03 ≦ y ≦ 1.17, 0.0 ≦ z ≦ 0.6, 0.0 ≦ w ≦ 0.5, and the light rare earth LRE is cerium ( A quenching solidification product containing an effective amount of light rare earths selected from the group consisting of Ce), lanthanum (La), yttrium (Y), and mixtures thereof, with a maximum energy product in the temperature range of 4K to 135K. The quenching solidification product according to claim 1, which has a value of 500 (kJ / m ³ ) or more. It is a rare earth-iron-boron type alloy quenching solidification product, and the composition formula of the alloy is
{(Nd _z Pr _1-z ) _1-x LRE _x } _2y- (Fe _w Co _1-w ) ₁₄ -B;
0.20 ≦ x ≦ 0.30, 1.07 ≦ y ≦ 1.14, 0.0 ≦ z ≦ 0.4, 0.0 ≦ w ≦ 0.3, and the light rare earth LRE is cerium ( A quenching solidification product containing an effective amount of light rare earths selected from the group consisting of Ce), lanthanum (La), yttrium (Y), and mixtures thereof, with a residual magnetization of 135K in the temperature range of 4K to 135K. 1 or 2 according to claim 1 or 2, which has a maximum value of 1.6 T in, has 1.4 T in 4K, and has a maximum energy product of 500 (kJ / m ³ ) or more in the temperature range of 4K to 135K. Quenching solidification product. It is an isotropic alloy material of rare earth-iron-boron type alloy, and its composition formula is
{(Nd _z Pr _1-z ) _1-x LRE _x } _2y- (Fe _w Co _1-w ) ₁₄ -B;
0.0 ≦ x ≦ 0.5, 1.0 ≦ y ≦ 1.22, 0.0 ≦ z ≦ 0.8, 0.0 ≦ w ≦ 0.8
The light rare earth LRE comprises an effective amount of the light rare earth selected from the group consisting of cerium (Ce), lanthanum (La), yttrium (Y), and mixtures thereof.
Maximum in the temperature range of 4K to 135K when quenched and solidified as an anisotropic permanent magnet consisting of RE2Fe14B square crystal grains that are substantially magnetically aligned using the isotropic alloy material. An isotropic alloy material having an energy product of 250 (kJ / m ³ ) or more. It is an isotropic alloy material of rare earth-iron-boron type alloy, and its composition formula is
{(Nd _z Pr _1-z ) _1-x LRE _x } _2y- (Fe _w Co _1-w ) ₁₄ -B;
0.05 ≦ x ≦ 0.45, 1.03 ≦ y ≦ 1.17, 0.0 ≦ z ≦ 0.6, 0.0 ≦ w ≦ 0.5, and the light rare earth LRE is cerium ( Contains an effective amount of light rare earths selected from the group consisting of Ce), lanthanum (La), yttrium (Y), and mixtures thereof.
Maximum in the temperature range of 4K to 135K when quenched and solidified as an anisotropic permanent magnet consisting of RE2Fe14B square crystal grains that are substantially magnetically aligned using the isotropic alloy material. The isotropic alloy material according to claim 4, wherein the energy product has a value of 500 (kJ / m ³ ) or more. It is an isotropic alloy material of rare earth-iron-boron type alloy, and its composition formula is
{(Nd _z Pr _1-z ) _1-x LRE _x } _2y- (Fe _w Co _1-w ) ₁₄ -B;
0.20 ≦ x ≦ 0.30, 1.07 ≦ y ≦ 1.14, 0.0 ≦ z ≦ 0.4, 0.0 ≦ w ≦ 0.3, and the light rare earth LRE is cerium ( Contains an effective amount of light rare earths selected from the group consisting of Ce), lanthanum (La), yttrium (Y), and mixtures thereof.
When quenched and solidified as an anisotropic permanent magnet using the isotropic alloy material, it consists of RE2Fe14B square crystal grains that are substantially magnetically aligned and has residual magnetization in the temperature range of 4K to 135K. 4 or 5 has a maximum value of 1.6T at 135K, 1.4T at 4K, and a maximum energy product of 500 (kJ / m ³ ) or more in the temperature range of 4K to 135K. The isotropic alloy material described. Rare earth-iron-boron type anisotropic permanent magnet with a composition formula,
{(Nd _z Pr _1-z ) _1-x LRE _x } _2y- (Fe _w Co _1-w ) ₁₄ -B;
0.0 ≦ x ≦ 0.5, 1.0 ≦ y ≦ 1.22, 0.0 ≦ z ≦ 0.8, 0.0 ≦ w ≦ 0.8
The light rare earth LRE comprises an effective amount of the light rare earth selected from the group consisting of cerium (Ce), lanthanum (La), yttrium (Y), and mixtures thereof.
Consists of substantially magnetically aligned RE2Fe14B tetragonal grains,
An anisotropic permanent magnet having a maximum energy product of 250 (kJ / m ³ ) or more in the temperature range of 4K to 135K. Rare earth-iron-boron type anisotropic permanent magnet with a composition formula,
{(Nd _z Pr _1-z ) _1-x LRE _x } _2y- (Fe _w Co _1-w ) ₁₄ -B;
0.05 ≦ x ≦ 0.45, 1.03 ≦ y ≦ 1.17, 0.0 ≦ z ≦ 0.6, 0.0 ≦ w ≦ 0.5, and the light rare earth LRE is cerium ( Contains an effective amount of light rare earths selected from the group consisting of Ce), lanthanum (La), yttrium (Y), and mixtures thereof.
Consists of substantially magnetically aligned RE2Fe14B tetragonal grains,
The anisotropic permanent magnet according to claim 7, wherein the maximum energy product in the temperature range of 4K to 135K has a value of 500 (kJ / m ³ ) or more. Rare earth-iron-boron type anisotropic permanent magnet with a composition formula,
{(Nd _z Pr _1-z ) _1-x LRE _x } _2y- (Fe _w Co _1-w ) ₁₄ -B;
0.20 ≦ x ≦ 0.30, 1.07 ≦ y ≦ 1.14, 0.0 ≦ z ≦ 0.4, 0.0 ≦ w ≦ 0.3, and the light rare earth LRE is cerium ( Contains an effective amount of light rare earths selected from the group consisting of Ce), lanthanum (La), yttrium (Y), and mixtures thereof.
Consists of substantially magnetically aligned RE2Fe14B tetragonal grains,
The residual magnetization in the temperature range of 4K to 135K has a maximum value of 1.6T at 135K, 1.4T at 4K, and
The anisotropic permanent magnet according to claim 7 or 8, wherein the maximum energy product in the temperature range of 4K to 135K has a value of 500 (kJ / m ³ ) or more. It is a permanent magnet having substantially stable magnetic properties and having a quenching solidification product of a molded fine earth-iron-boron metal material as an effective ferromagnetic phase, and the composition formula is:
{(Nd _z Pr _1-z ) _1-x LRE _x } _2y- (Fe _w Co _1-w ) ₁₄ -B;
0.0 ≦ x ≦ 0.5, 1.0 ≦ y ≦ 1.22, 0.0 ≦ z ≦ 0.8, 0.0 ≦ w ≦ 0.8
The light rare earth LRE comprises an effective amount of the light rare earth selected from the group consisting of cerium (Ce), lanthanum (La), yttrium (Y), and mixtures thereof.
A permanent magnet having a maximum energy product of 250 (kJ / m ³ ) or more in the temperature range of 4K to 135K. The rare earth-iron-boron type permanent magnet according to claim 10, wherein the composition formula is.
{(Nd _z Pr _1-z ) _1-x LRE _x } _2y- (Fe _w Co _1-w ) ₁₄ -B;
0.05 ≦ x ≦ 0.45, 1.03 ≦ y ≦ 1.17, 0.0 ≦ z ≦ 0.6, 0.0 ≦ w ≦ 0.5, and the light rare earth LRE is cerium ( Contains an effective amount of light rare earths selected from the group consisting of Ce), lanthanum (La), yttrium (Y), and mixtures thereof.
The permanent magnet according to claim 10, wherein the maximum energy product in the temperature range of 4K to 135K has a value of 500 (kJ / m ³ ) or more. The rare earth-iron-boron type permanent magnet according to claim 10 or 11, wherein the composition formula is.
{(Nd _z Pr _1-z ) _1-x LRE _x } _2y- (Fe _w Co _1-w ) ₁₄ -B;
0.20 ≦ x ≦ 0.30, 1.07 ≦ y ≦ 1.14, 0.0 ≦ z ≦ 0.4, 0.0 ≦ w ≦ 0.3, and the light rare earth LRE is cerium ( Contains an effective amount of light rare earths selected from the group consisting of Ce), lanthanum (La), yttrium (Y), and mixtures thereof.
Consists of substantially magnetically aligned RE2Fe14B tetragonal grains,
The residual magnetization in the temperature range of 4K to 135K has a maximum value of 1.6T at 135K, 1.4T at 4K, and the maximum energy product in the temperature range of 4K to 135K is 500 (kJ / m ³ ) or more. The permanent magnet according to claim 10 or 11, which has a value. A rare earth-iron-boron alloy in the form of fine particles,
The iron, boron, and rare earths are used in an amount substantially corresponding to the amount desired for the quenching solidified permanent magnet material.
An alloy ingot composed of an intermetallic phase having the composition of rare earth-iron-boron was prepared by a liquid quenching method.
The alloy ingot produced by the liquid quenching method is crushed to prepare a fine-grained rare earth-iron-boron alloy, and the composition formula is as follows.
{(Nd _z Pr _1-z ) _1-x LRE _x } _2y- (Fe _w Co _1-w ) ₁₄ -B;
0.0 ≦ x ≦ 0.5, 1.0 ≦ y ≦ 1.22, 0.0 ≦ z ≦ 0.8, 0.0 ≦ w ≦ 0.8
The light rare earth LRE comprises an effective amount of the light rare earth selected from the group consisting of cerium (Ce), lanthanum (La), yttrium (Y), and mixtures thereof.
When rapidly cooled and solidified as a permanent magnet, the maximum energy product in the temperature range of 4K to 135K has a value of 250 (kJ / m ³ ) or more.
A rare earth-iron-boron type rapidly cooled and solidified permanent magnet material for hot-compressing the finely divided alloy to produce a rapidly cooled and solidified permanent magnet having a predetermined shape. A rare earth-iron-boron alloy in the form of fine particles according to claim 13.
The composition formula is
{(Nd _z Pr _1-z ) _1-x LRE _x } _2y- (Fe _w Co _1-w ) ₁₄ -B;
0.05 ≦ x ≦ 0.45, 1.03 ≦ y ≦ 1.17, 0.0 ≦ z ≦ 0.6, 0.0 ≦ w ≦ 0.5, and the light rare earth LRE is cerium ( Contains an effective amount of light rare earths selected from the group consisting of Ce), lanthanum (La), yttrium (Y), and mixtures thereof.
The rare earth-iron-boron type quenched permanent magnet according to claim 13, which has a maximum energy product of 500 (kJ / m ³ ) or more in the temperature range of 4K to 135K when it is quenched and solidified as a permanent magnet. material. A rare earth-iron-boron alloy in the form of fine particles according to claim 13 or 14, wherein the composition formula is.
{(Nd _z Pr _1-z ) _1-x LRE _x } _2y- (Fe _w Co _1-w ) ₁₄ -B;
0.0 ≦ x ≦ 0.5, 1.0 ≦ y ≦ 1.22, 0.0 ≦ z ≦ 0.4, 0.0 ≦ w ≦ 0.3
The light rare earth LRE comprises an effective amount of the light rare earth selected from the group consisting of cerium (Ce), lanthanum (La), yttrium (Y), and mixtures thereof.
When rapidly cooled and solidified as a permanent magnet, the maximum energy product in the temperature range of 4K to 135K has a value of 250 (kJ / m ³ ) or more.
The rare earth-iron-boron type quenching solidified permanent magnet material according to claim 13 or 14. The quenching solidification product according to claims 1 to 3, the isotropic alloy material according to claims 4 to 6, the anisotropic permanent magnet according to claims 7 to 9, and the difference according to claims 10 to 12. A magnetic refrigerating apparatus using an anisotropic permanent magnet or a quenching solidified permanent magnet material of the rare earth-iron-boron type according to claims 13 to 15. A method for producing rare earth-iron-boron type quenching solidification permanent magnets.
A rare earth-iron-boron alloy in the form of fine particles,
The fine particles
The step of preparing an alloy ingot composed of an intermetallic phase having a rare earth-iron-boron composition by a liquid quenching method, and
Manufactured including the step of crushing the alloy ingot produced by the liquid quenching method to prepare a fine particle rare earth-iron-boron alloy.
The fine particles have an average particle size of up to about 60 microns.
Alloy fine particles are essentially
{(Nd _z Pr _1-z ) _1-x LRE _x } _2y- (Fe _w Co _1-w ) ₁₄ -B;
0.0 ≦ x ≦ 0.5, 1.0 ≦ y ≦ 1.22, 0.0 ≦ z ≦ 0.8, 0.0 ≦ w ≦ 0.8
The light rare earth LRE has a composition consisting of an effective amount of light rare earth selected from the group consisting of cerium (Ce), lanthanum (La), yttrium (Y), and mixtures thereof.
A step of hot-compressing the fine-grained alloy and compressing and deforming it into a quench-cooling permanent magnet having a predetermined shape to produce a quench-cooling permanent magnet is included.
The quenching and solidifying permanent magnet is a method for producing a quenching and solidifying permanent magnet composed of a substantially intermetallic compound RE2Fe14B phase.

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