Magnetic material comprising an ordered Fe-Ni alloy and method for producing the same

Abstract

Magnetic material comprising an ordered FeNi alloy, wherein the ordered FeNi alloy with ordered L10 structure is doped with a light element and is provided as a granular particle (1), wherein the granular particle (1) having a main phase not doped with the light element at a central portion (1a) of the granular particle (1) providing the ordered FeNi alloy, and having a doped phase containing the light element in a surface layer (1b) surrounding the central portion (1a).

Description

Technical area

[0001] The present invention relates to a magnetic material comprising an ordered L10-FeNi alloy having an ordered L10 structure and a manufacturing method for the same. State of the art

[0002] An ordered L10-type FeNi alloy, which has Fe (iron) and Ni (nickel) as its main components, is expected to be a promising magnetic material and a promising magnetic recording material, using no rare earth element or noble metal at all. Here, the ordered L10 structure is a crystal structure that has a face-centered cubic lattice as its basic structure and in which Fe and Ni are layered in the (001) direction. Such an ordered L10 structure is found in alloys such as FePt, FePd, and AuCu and is typically obtained by thermally treating a random alloy with an order-to-disorder transition temperature equal to or lower than Tλ and promoting diffusion.

[0003] To use a magnetic material containing this ordered L10-FeNi alloy for a magnetic material or a magnetic recording medium, a high coercivity is required. Non-Patent Literature 1 below proposes stopping the crystallization of the ordered L10-FeNi alloy to obtain a high coercivity in the ordered L10-FeNi alloy. Using this manufacturing method, it is possible to obtain an ordered L10-FeNi alloy with a coercivity of 56 kA / m. It is reported that the ordered FeNi alloy obtained in this way also has a high degree of ordering, not overall but locally, and a magnetization of 100 emu / g or Am2 / kg and a volume fraction of roughly 8%. State of the art literaturePatent literature

[0004] DE 11 2016 004 716 T5 discloses an ordered FeNi alloy of the L10 type and a method for producing the ordered FeNi alloy, wherein the degree of order S of the FeNi alloy is equal to or greater than 0.5.

[0005] An ordered FeNi alloy with L10 structure and its production are also described in US 2014 / 0 271 324 A1, wherein the alloy has a particle shape and can contain one or more of the elements Ti, V, Al, B, C, P and S.

[0006] WO 2016 / 036856 A1 discloses a magnetic material based on an FeNi alloy with an L10 structure and a method for its production, wherein one or more of the elements Ti, V, Al, B, and C can be added during melting of the starting materials. The resulting material can be ground into a powder with a particle size in the nanometer to micrometer range.

[0007] Non-patent literature 1: Artificially produced rare-earth free cosmic magnet, A. Makino et al., Scientific Reports 5, (2015) 16627 Summary of the invention

[0008] The use of a magnetic material containing the ordered FeNi alloy for a magnetic material or a magnetic recording medium requires a large coercive force, particularly 87.5 [kA / m] or more. The coercive force can be obtained as follows: A magnetic field is applied to the obtained ordered FeNi alloy, and the coercive force is obtained as the strength of the magnetic field at which a magnetization direction of the ordered Fe-Ni alloy is changed due to the magnetic field. In the SI system of units, the coercive force is expressed in the unit kA / m. In the OGS system of units, the coercive force is expressed in the unit Oe [Oersted]. Thus, 1 [A / m] = 4π × 10 -3 [Oe] and 87.5 [kA / m] = 1100 [Oe].

[0009] The use of a magnetic material containing an ordered FeNi alloy for a magnetic material or a magnetic recording medium requires not only a large coercive force but also a large saturation magnetization. Specifically, a large saturation magnetization of 1.0 [T] or more is required.

[0010] In this regard, the saturation magnetization and the coercivity exhibit a trade-off relationship in that the coercivity decreases as the saturation magnetization increases, and conversely, the coercivity increases as the saturation magnetization decreases. Therefore, it is desirable to realize both a large coercivity and a large saturation magnetization while allowing control of the coercivity and the saturation magnetization.

[0011] It is an object of the present invention to provide a magnetic material comprising an ordered L10-FeNi alloy and a manufacturing method for the same, which enable control of a coercive force and a saturation magnetization and which realize both a large coercive force and a large saturation magnetization.

[0012] A magnetic material according to one aspect of the present invention comprises an ordered FeNi alloy having an ordered L10 structure, doped with a light element, and provided as a granular particle, the granular particle having a main phase not doped with the light element at a central portion of the granular particle providing the ordered FeNi alloy, and having a doped phase containing the light element in a surface layer surrounding the central portion.

[0013] As described above, the ordered FeNi alloy contained in the magnetic material is present as a granular particle and doped with the light element. This structure makes it possible to create a magnetic material with an ordered FeNi alloy that has a coercive force of 87.5 [kA / m] or more and a saturation magnetization of 1.0 [T] or more.

[0014] A method for producing a magnetic material comprising an ordered FeNi alloy having an ordered L10 structure according to one aspect of the present invention comprises: preparing an ordered FeNi alloy provided as a granular particle; and doping a light element into the ordered FeNi alloy.

[0015] By preparing the ordered FeNi alloy as a granular particle and then doping the light element into the ordered FeNi alloy in the above manner, it is possible to obtain a magnetic material having an ordered FeNi alloy having a coercive force of 87.5 [kA / m] or more and a saturation magnetization of 1.0 [T] or more.

[0016] Note that the reference numerals in parentheses of the elements indicate examples of a correspondence relationship of the elements to concrete elements described in the following embodiments. Short description of the drawings Fig. 1A is a diagram showing a cross-sectional structure of a granular particle of an ordered FeNi alloy contained in a magnetic material not covered by the present invention. Fig. 1B is a diagram showing a cross-sectional structure of a granular particle of an ordered FeNi alloy contained in a magnetic material according to the first embodiment of the invention. Fig. 1C is a diagram showing a cross-sectional structure of a granular particle of an ordered FeNi alloy contained in a magnetic material not covered by the present invention. Fig. Figure 2A is a diagram showing a lattice structure of an ordered FeNi alloy. Fig. Figure 2B is a diagram showing a state where a light element is contained in an Fe layer of an ordered FeNi alloy. Fig. Figure 2C is a diagram showing a state where a light element is contained in a Ni layer of an ordered FeNi alloy. Fig. Figure 3 is a flowchart showing details of a doping process. Fig. Figure 4 is a diagram showing a manufacturing apparatus for an ordered FeNi alloy. Fig. 5 is a diagram schematically showing a doping device used in a doping process. Fig. Figure 6 is a flowchart showing details of a doping process. Fig. 7 is a diagram showing conditions in a doping process of respective working examples and measurement results of a saturation magnetization and a coercive force of the respective working examples and a comparative example. Fig. 8A is a graph showing a measurement result of a doping ratio in a sample of Working Example 1. Fig. 8B is a diagram showing a measurement result of a doping ratio in a sample of Working Example 2. Fig. 8C is a graph showing a measurement result of a doping ratio in a sample of Working Example 3. Fig. 8D is a graph showing a measurement result of a doping ratio in a sample of Comparative Example 3. Fig. Figure 9 is a diagram showing a measurement result of an X-ray spectrograph (hereinafter referred to as XDR). Fig. Figure 10 is a diagram showing a lattice structure of FeNiN, which is an intermediate. Fig. 11 is a diagram showing a result of X-ray spectral analysis of an ordered L10-FeNi alloy contained in a magnetic material according to a second embodiment. Fig. 12 is a graph showing measurement results of a coercive force. Description of the embodiments

[0017] Embodiments of the present invention will be described below with reference to the drawings. In the following embodiments, the same reference numerals are mainly used for the same or equivalent parts. First embodiment

[0018] The first embodiment will be described below. The ordered L10 FeNi alloy according to the present embodiment, that is, a magnetic material having a FeNi superlattice, is used for a magnetic material, a magnetic recording medium, or the like.

[0019] The ordered L10-FeNi alloy included in the magnetic material according to the present embodiment is a granular particle doped with a light element, has a coercive force of 87.5 kA / m or more, and has a saturation magnetization of 1.0 [T] or more. Specifically, the ordered L10-FeNi alloy is doped with, for example, B (boron), C (carbon), and N (nitrogen) as light elements, or may be doped with at least one of several types of two or more of the light elements.

[0020] The granular particles of the ordered L10-FeNi alloy have an average particle size of, for example, 40 µm. As Fig. 1A as a non-inventive alternative, in the granular particles 1 of the ordered L10-FeNi alloy, a respective individual granular particle as a whole, that is, an entire area of ​​a cross-section of a respective individual granular particle, has a doped phase in which the light element is contained. As shown in Fig. 1B as an alternative according to the invention, in the granular particles 1 of the ordered L10-FeNi alloy, each individual granular particle has: a main phase with a central portion 1a in which almost no light element is contained in the L10-FeNi; and a doped phase at a surface layer 1b surrounding the central portion 1a, wherein the light element is contained in the doped phase. As shown in Fig. 1C as a non-inventive alternative, in the granular particles 1 of the ordered L10-FeNi alloy, each individual granular particle has: a doped phase in the central portion 1a in which the light element is contained; and a main phase in the surface layer 1b surrounding the central portion 1a, wherein almost no light element is contained in the main phase.

[0021] The regular L10 structure is a structure based on a face-centered cubic lattice and has a lattice structure as shown in Fig. 2A. In this drawing, the uppermost layer in the layered structure of the

[001] plane of the face-centered cubic lattice is a Ni layer in which Ni is mainly present (hereinafter referred to simply as the Ni layer). The intermediate layer located between the uppermost layer and the lowermost layer is an Fe layer in which Fe is mainly present (hereinafter referred to simply as the Fe layer).

[0022] In the ordered L10-FeNi alloy, which has a structure as described in Fig. As shown in Figure 2B, the light element is located in an octahedral central position in the Fe layer, i.e., in the middle position between Fe atoms. Fig. As shown in Figure 2C, the light element is similarly arranged at the octahedral center site in the Ni layer, that is, at the middle position between the Ni atoms. It was confirmed that when the light element is arranged in the Fe layer or the Ni layer, the coercive force increases or is larger compared to an ordered L10 FeNi alloy in which no light element is included.

[0023] Therefore, the ordered L10-FeNi alloy contained in the magnetic material according to the present embodiment is provided as granular particles 1 as shown in the Fig. 1A to 1C, while all or part of the surface layer 1b of each granular particle 1 has the doped phase containing the light element. With such structures, the coercive force of the magnetic material comprising the ordered L10-FeNi alloy is increased.

[0024] This magnetic material with the ordered L10-FeNi alloy according to the present embodiment can be obtained, for example, by performing a doping process of the ordered L10-FeNi alloy with a light element; however, the magnetic material is obtained by performing various processes according to the flow chart of Fig. 3 received.

[0025] First, in step S100, an ordered FeNi alloy is prepared, and a nitriding-denitriding treatment is performed on it to obtain an ordered L10 FeNi alloy. Specifically, after performing a nitriding treatment to nitride the disordered FeNi alloy, a denitriding treatment is performed to remove nitrogen from the nitrided disordered FeNi alloy to obtain an ordered FeNi alloy. Here, a random alloy is an alloy in which an arrangement of atoms has no order but is random.

[0026] Subsequently, in step S110, the obtained ordered FeNi alloy is subjected to an electrochemical treatment, thereby performing a light element doping process. Specifically, the light element doping process is performed by boronization, carbonization, and nitriding through the electrochemical treatment. Then, in step S120, a purification treatment is performed as needed. In this way, it is possible to produce the magnetic material with the ordered L10 FeNi alloy according to the present embodiment.

[0027] In particular, the nitriding treatment and the denitriding treatment can be carried out using, for example, a nitriding-denitriding treatment apparatus provided in Fig. 4. This nitriding-denitriding treatment apparatus includes: a tubular furnace 10 as a heating furnace heated by a heater 11; and a glove box 20 for placing a sample in the tubular furnace 10. As shown in Fig. 4, the nitriding-denitriding treatment apparatus further includes a gas introduction part 30 that switches the gas introduced into the tubular furnace 10 between Ar (argon) serving as a purge gas, NH3 (ammonia) for the nitriding treatment, and H2 (hydrogen) for the denitriding treatment.

[0028] The nitriding-denitriding treatment using such a nitriding-denitriding treatment apparatus is as follows. First, a powder sample of a random FeNi alloy 100 is placed in the tubular furnace 10. During the nitriding treatment, NH3 gas is introduced into the tubular furnace 10 so that the interior of the tubular furnace 10 has an NH3 atmosphere, and the random FeNi alloy is heated at a predetermined temperature for a predetermined time to perform nitriding. At the same time, N is introduced into FeNi through the nitriding treatment, and crystal ordering occurs. Specifically, when FeNiN, which is an FeNi compound, is produced, the metal element arrangement structure of the ordered FeNi alloy is obtained in the nitriding treatment stage.

[0029] Then, in the denitriding treatment, H2 gas is introduced into the heating furnace so that the interior of the tubular furnace 10 has an H2 atmosphere, and the randomly nitrided FeNi alloy is heated at a predetermined temperature for a predetermined time to remove nitrogen. By removing the nitrogen in this way, an ordered L10 FeNi alloy is obtained, into which the light element is doped.

[0030] The doping process can be carried out using, for example, a doping device as described in Fig. 5. In this doping apparatus, a molten salt 41 is filled into a liquid storage container 40, and doping with the light element is performed by applying a predetermined voltage via a DC power source 45 in a state where a working electrode 42, a counter electrode 43, and a reference electrode 44 are immersed in the molten salt 41.

[0031] The molten salt 41 is a solution in which a doping source of a light element is dissolved, and contains ions of the doping source. As the working electrode 42 absorbs the ions, the light element is doped into the working electrode 42. The molten salt 41 is used as a doping source of various light elements such as B, C, and N. For example, K2O3 or KBF4 can be used as a doping source of B. K2CO3, CaC2, or the like can be used as a doping source of C. Li3N, NH4Cl, or the like can be used as a doping source of N. An alkali metal halide can be used as the molten salt 41 for melting these. The alkali metal halide used can be LiF, NaF, KF, CsF, LiCl, NaCl, KCl, CsCl, LiBr, NaBr, KBr, CsBr, LiI, NaI, KL, CsI, or the like. A combination of two or more of these can be used.For example, lithium chloride-potassium chloride-cesium chloride (LiCl-KCl-CsCl), lithium fluoride-sodium fluoride-potassium fluoride (LiF-NaF-KF), or lithium bromide-potassium bromide-cesium bromide (LiBr-KBr-CsBr) can be used. Regarding multiple types of light element doping sources, a combination of the materials described above can be used for the light element doping source. For example, lithium chloride-potassium chloride-cesium chloride-potassium borofluoride-potassium carbonate (LiCl-KCl-CsCl-KBF4-K2CO3) can be used as the doping source for B and C.

[0032] The working electrode 42 is, for example, a flat metal made of the material to be doped with the light element, that is, the ordered L10-FeNi alloy before doping. Since the ordered L10-FeNi alloy is provided as granular particles 1, they are solidified into a plate shape. Although the ordered L10-FeNi alloy is used here, a compound having the same metal element arrangement as the ordered L10-FeNi alloy, such as the FeNiN described above, can be used as is.

[0033] The counter electrode 43 is, for example, a flat metal made of a different metal than the working electrode 42, for example Al (aluminum).

[0034] The reference electrode 44 provides a reference point for measuring an equilibrium potential between the reference electrode 44 and the working electrode 42 and is made of a stable material, such as silver-silver chloride. A voltmeter 46 is arranged between the reference electrode 44 and the working electrode 42, and the equilibrium potential is measured by the voltmeter 46.

[0035] Based on the equilibrium potential measured by the voltmeter 46, the DC power source 45 generates a potential difference between the working electrode 42 and the counter electrode 43 that exceeds the electrolytic potential at which the ions serving as the doping source of the light element contained in the molten salt 41 are adsorbed on the working electrode 42. The voltage generated by the DC power source 45 and the direction of this voltage, i.e., the polarity, are controllable and are controlled based on the strength of the equilibrium potential measured by the voltmeter 46.

[0036] Since the positive and negative polarities of the equilibrium potential are fundamentally determined according to the materials of the respective electrodes, the direction of the voltage generated by the DC power source 45 can be determined according to the materials of the respective electrodes, and the magnitude of the voltage can be determined based on the equilibrium potential measured by the voltmeter 46. For example, when the molten salt 41 contains KBF4, which serves as a B dopant source, due to "KBF4 to K + + BF4 - ” the direction of the voltage of the DC power source 45 is determined such that the working electrode 42 becomes or is positive. In cases where the molten salt 41 contains Li3N, which serves as the N-dopant source, due to “Li3N to 3Li++ N 3 -“ the direction of the voltage of the DC power source 45 is set such that the working electrode 42 becomes or is negative.

[0037] The container 40 is housed in a core tube 47 defining an inner wall, and the molten salt 41 is heated by a temperature adjusting heater 48 arranged around the core tube 47.

[0038] Using this doping device, the working electrode 42, the counter electrode 43, and the reference electrode 44 are immersed in the molten salt 41, and the molten salt 41 is heated to 300 to 500 degrees Celsius (C) by the heater 48. Based on the equilibrium potential measured by the voltmeter 46, a desired voltage is applied by the DC power source 45. As a result, the ions of the dopant source contained in the molten salt 41 are adsorbed on the working electrode 42 and doped into the working electrode 42. In this way, the light element is doped into the ordered L10-FeNi alloy. Thereafter, the working electrode 42 is cleaned as needed, and the magnetic material with the ordered L10-FeNi alloy according to the present embodiment is obtained.The ordered L10-FeNi alloy obtained as described above has a plate shape which is an aggregate of granular particles 1, and thus the ordered L10-FeNi alloy obtained as described above is provided as granular particles.

[0039] The doping process can be carried out by gas treatment instead of or in addition to the electrochemical treatment. In particular, with respect to N, an ordered L10-FeNi alloy can be nitrided by gas nitriding. As shown, for example, in the flow chart of Fig. 6, after the nitriding-denitriding treatment in step S100, similar to Fig. 3, the gas nitriding is carried out in step S105. The gas nitriding treatment can be carried out here using the Fig. 4 under the same conditions as the nitriding treatment in step S100. In addition, in step S110, the same electrochemical treatment as in Fig. 3. At the same time, N can be doped by the electrochemical treatment, but since the doping of N has already been performed in step S105, only doping of B and C can be performed. Thereafter, in step S120, the magnetic material with the ordered L10-FeNi alloy according to the present embodiment can be obtained by a purification treatment, as needed.

[0040] As described above, it is possible to nitride the ordered L10-FeNi alloy by gas nitriding. Therefore, the electrochemical process shown in step S110 must be included in the flow chart of Fig. 6 may not be carried out in the doping process, and only the gas nitriding treatment may be carried out.

[0041] In the following, the saturation magnetization and the coercive force of the ordered L10-FeNi alloy according to the present embodiment obtained by the above manufacturing method are compared for Working Examples 1 to 8 and a Comparative Example 1 with reference to Fig. 7 described.

[0042] The working examples 1 to 8 in Fig. 7 show cases where magnetic materials with an ordered L10-FeNi alloy were prepared through respective steps according to the flow chart of Fig. 3 or the Fig. 6. Comparative Example 1 shows a case where a magnetic material with an ordered L10-FeNi alloy without a catalyst used in the flow chart of Fig. 3 or Fig. 6, in particular without carrying out the doping process. Fig. Figure 7 shows the saturation magnetization and coercive force values ​​for the respective cases of Working Examples 1 to 8 and Comparative Example 1. For Working Examples 1 to 8, the conditions of the respective steps are also shown in the drawing. For example, using Quantum Design's small-sized coolant-free PPMS VersaLab, the magnetic properties were obtained with a magnetic field sweep rate of 10 [Oe].

[0043] As it is in Fig. As shown in Figure 7, working examples 1, 2 and 4 were prepared by performing the respective steps of the flow chart of Fig. 3. In the doping process for Working Examples 1, 2, and 4, the electrochemical treatment was carried out for 20 hours using only one of the doping sources B, C, and N. In Working Examples 1, 2, and 4, the coercive force was 88 [kA / m], 95 [kA / m], and 101 [kA / m], respectively, and the magnetic saturation was 1.0 [T] in all cases.

[0044] In Working Example 3, only the gas nitriding treatment in S105 was used for the doping process in the flow chart of Fig. 3. The gas nitriding treatment was carried out for 4 hours. In Working Example 3, the saturation magnetization was 1.1 [T], and the coercive force was 105 [kA / m].

[0045] In working example 5, the respective steps in the flow chart of the Fig. 3. In the doping process of Working Example 5, the electrochemical treatment was carried out for 20 hours using two of the doping sources of B, C, and N, specifically a doping source consisting of a combination of B and C. In Working Example 5, the saturation magnetization was 1.2 [T], and the coercive force was 96 [kA / m].

[0046] In working examples 6 and 7, each step in the flow chart of the Fig. 6. In the doping processes of Working Examples 6 and 7, after gas nitriding, the electrochemical treatment was performed using the doping source of B or C for 20 hours. In both cases of Working Examples 6 and 7, the saturation magnetization was 1.0 [T] or more, and the coercive force was 99 and 110 [kA / m], respectively.

[0047] In Working Example 8, each step in the flowchart of Fig. 6. In the doping process of Working Example 8, after gas nitriding, electrochemical treatment was performed using the doping source of B and C for 20 hours. In Working Example 8, the saturation magnetization was 1.0 [T], and the coercive force was 114 [kA / m].

[0048] On the other hand, in the case of Comparative Example 1, in which neither the gas treatment nor the electrochemical treatment was performed, the saturation magnetization had a large value of 1.4 [T], but the coercive force had a small value of 72 [kA / m].

[0049] As shown in Working Examples 1 to 8, by performing the doping process by the gas treatment or the electrochemical treatment, a magnetic material having the ordered L10-FeNi alloy doped with the light element such as B, C and N, which has both a large saturation magnetization and a large coercive force, is obtained.

[0050] Furthermore, in Working Examples 1 to 3 and Comparative Example 1, a doping ratio of the doping element in the obtained magnetic material containing the ordered L10-FeNi alloy was investigated. To confirm that the doping elements were uniformly doped, the doping ratio in Working Example 1 was measured at several measurement points (1) to (4). Fig. Figures 8A to 8D show the measurement results. The doping ratio was measured using an SEM / EDS, which is a scanning electron microscope (hereinafter referred to as SEM) to which an energy-dispersive X-ray analyzer (hereinafter referred to as EDS) is attached. The numerical values ​​in the figure represent the element ratio of each sample measured by the SEM / EDS.

[0051] As it is in Fig. As shown in Figure 8A, in Working Example 1, element B was present at a ratio of 58% or more at the respective measurement points (1) to (4). This shows that element B was accurately and uniformly contained in the magnetic material with the ordered L10-FeNi alloy. As shown in Fig. As shown in Figure 8B, in Working Example 2, element C was present at a ratio of 39%, and this shows that, as in Working Example 1, element C was exactly contained in the magnetic material with the ordered L10-FeNi alloy. As shown in Fig. As shown in Figure 8C, in Working Example 3, the element N was present at a ratio of 43%, and this shows that, as in Working Examples 1 and 2, the element N was exactly contained in the magnetic material with the ordered L10-FeNi alloy. As shown in Fig. On the other hand, as shown in Fig. 8D, in Comparative Example 1, the ratio of element B or the like was 0%, and this shows that only Fe and Ni were contained in the magnetic material having the ordered L10-FeNi alloy.

[0052] In addition, the measurement in working example 1 was carried out using XRD. Fig. Figure 9 shows the XRD measurement results. These XRD measurement results show that there were two components, i.e., an L10-FeNi phase and a B-doped phase, and that a compound of an ordered L10-FeNi alloy, i.e., a boride, was formed. Thus, by forming a compound by doping a light element such as B, it is possible to obtain a magnetic material with an ordered L10-FeNi alloy that achieves both a large saturation magnetization and a large coercive force.

[0053] When the volume ratio of each element in Working Example 1 was examined, it was found that the ratio of the L10-FeNi phase to the B-doped phase was 95:5. Based on this result and the average particle size of 40 μm of the granular particles 1 of the ordered L10-FeNi alloy, the thickness of the B-doped phase from the particle surface was calculated to be 3 μm. That is, in Working Example 1, it was confirmed that the central portion 1a of each granular particle 1 of the ordered L10-FeNi alloy was the main phase containing almost no B, and its surface layer 1b was the B-doped phase. Thus, even if the surface layer 1b is mainly doped with the light element, it is possible to obtain a magnetic material with an ordered L10-FeNi alloy that achieves both a large saturation magnetization and a large coercive force.The ratio and thickness of the doped phase can be adjusted according to the conditions of the doping process. By providing the doped phase not only in the surface layer 1b but also throughout the entire granular particle 1, it is possible to achieve a high coercive force.

[0054] As described above, the ordered L10-FeNi alloy contained in the magnetic material according to the present embodiment is present as granular particles 1 and doped with the light element. Specifically, the ordered L10-FeNi alloy has a structure in which, for example, B, C, and N are contained as light elements in the octahedral center site of the Ni layer or the octahedral center site of the Fe layer. With this structure, a magnetic material having an ordered L10-FeNi alloy can be obtained, which has a coercive force of 87.5 [kA / m] or more and a saturation magnetization of 1.0 [T] or more. If not only some of the granular particles 1 constituting the magnetic material, but the entire granular particles 1 contain the Fig. 1A to 1C, it is possible to obtain a larger coercive force and a larger saturation magnetization. If only some of the granular particles 1 constituting the magnetic material have at least one Fig. 1A to 1C and there is an ordered L10-FeNi alloy that is not doped with the light element, it is of course possible to obtain a high coercivity and a high saturation magnetization.

[0055] However, if the granular particles 1 as a whole have the Fig. 1A to 1C, a larger coercive force and a larger saturation magnetization can be obtained. Second embodiment

[0056] The second embodiment will be described below. In this embodiment, a magnetic material comprising an ordered L10-FeNi alloy doped with light elements is manufactured using a different manufacturing method than the first embodiment.

[0057] Specifically, in the first embodiment, after performing the nitriding treatment and the denitriding treatment, the doping process is performed to dope the light element into the ordered L10-FeNi alloy. On the other hand, in the present embodiment, the ordered L10-FeNi alloy doped with the light element is produced by adjusting the denitriding treatment conditions so that the light element N remains, with the denitriding treatment being performed after the nitriding treatment.

[0058] First, as in the first embodiment, the disordered NeNi alloy is prepared and nitriding is carried out using the method described in Fig. 4, so that N is introduced into FeNi and crystal order occurs. This produces FeNiN, which is a FeNi compound, as an intermediate. The FeNiN has the Fig. 10, ie has a lattice structure in which the element N is arranged between the elements Fe in the Fe layer adjacent to the element Fe.

[0059] Next, as a denitriding treatment, using the nitriding-denitriding device, the denitriding treatment is performed under conditions such that the denitriding is performed even more slowly than in the first embodiment. Here, the denitriding treatment is performed in an H2 atmosphere at an atmospheric temperature of 150 to 400 degrees Celsius (C), for example, 250 degrees Celsius (C), for a treatment time of 0.1 to 7 hours. The H2 atmosphere is generated by introducing H2 gas into Ar, which serves as a purge gas, and the H2 atmosphere ratio is set to 5% or more.

[0060] The treatment temperature, treatment time, and H2 atmosphere ratio can be adjusted appropriately and have the following relationships: When the treatment temperature is higher, the treatment time is shorter; when the treatment temperature is lower or the treatment time is shorter, a larger ratio (proportion) of the H2 atmosphere can be used. Although a range based on experiments is shown, the treatment temperature, treatment time, and H2 atmosphere ratio can be adjusted here based on the above relationships.

[0061] In addition, NH3 used for nitriding treatment can be introduced simultaneously, so that denitration occurs slowly during the denitriding treatment. By introducing N2 instead of or together with NH3 to generate the nitrogen atmosphere, or by providing an atmosphere in which N2 and H2 react to generate NH3, it is also possible to prevent the occurrence of denitriding compared to cases where N2 is not introduced.

[0062] When slow denitration is carried out under these conditions, the separation of nitrogen from FeNiN, which serves as an intermediate, results in the synthesis of L10-Fe2Ni2N, rather than all FeNiN becoming FeNi, and thus a mixed phase of FeNi and Fe2Ni2N is also formed. L10-Fe2Ni2N has a metal element arrangement of the ordered L10-FeNi alloy and also has a structure in which N is contained at an intermediate position between Fe atoms, as shown in Fig. 2B, and nitrogen is partially separated from FeNiN, but a part of the nitrogen is not separated and remains. The structure of the granular particle 1 of the ordered L10-FeNi alloy, which has L10-Fe2Ni2N, can be the one shown in Fig. 1A, where the entire particle has the L10-Fe2Ni2N, or can the structure shown in Fig. 1B, where only the surface contains the L10-Fe2Ni2N.

[0063] In the following, the lattice structure and lattice constant of L10-Fe2Ni2N synthesized by the above preparation method are described with reference to L10-FeNi and the like.

[0064] The L10-FeNi has a lattice structure based on the Fig. 2. In L10-FeNi, when a Ni isotopic abundance ratio in the Ni layer is 100% and a Fe isotopic abundance ratio in the Fe layer is 100%, the lengths of the x-axis and the y-axis in the lattice structure, i.e., the distance a and the length b between the Ni atoms, are equal, so that a = b = 0.3576 nm to 0.3582 nm is satisfied. In addition, the length of the z-axis, i.e., the distance c between the Ni atoms, is different from the distance a and is c = 0.3589 nm to 0.3607 nm.

[0065] On the other hand, the L10-Fe2Ni2N has the Fig. 2B, where N is contained at the middle position between the Fe atoms, it has the same ordered structure as L10-FeNi. In L10-Fe2Ni2N, when the Ni isotopic abundance ratio in the Ni layer is 100% and the Fe isotopic abundance ratio in the Fe layer is 100%, the lengths of the x-axis and the y-axis in the lattice structure, that is, the distance a and the distance b between the Ni atoms, are equal, so that a = b = 0.377 nm is satisfied. In addition, the length of the z-axis, that is, the distance c between the Ni atoms, is different from the distances a and b and is given as c = 0.374 nm. L10-Fe2Ni2N has special lattice constants.

[0066] A similar material is Fe2Ni2N, where N is located at the center of the body of L12-FeNi. This is a similar structure to the lattice structure of Fig. 2B, but the face center position is not defined, so this is a cubic crystal, and the length of each axis is a = b = c = 0.773 nm, and therefore there is no anisotropy. The Fe layer also contains a lot of Ni and has a structure where the Fe content is 2 / 3 and the Ni content is 1 / 3. A lot of Fe is also present near Ni in the center of the Ni layer, and the Fe content is 1 / 3 and the Ni content is 2 / 3 in the structure.

[0067] The crystal structure of the ordered L10-FeNi alloy contained in the magnetic material prepared by the above manufacturing method was investigated by X-ray diffraction. Specifically, an X-ray beam with a wavelength of λ = 1.75653 angstroms (=0.175653 nm) was applied, and a diffraction peak was observed. Fig. Figure 11 shows the results. For reference, the X-ray diffraction study of the crystal structures of L10-Fe2Ni2N and L10-FeNi was also investigated by simulation. The result is shown in Fig. 10. The L10-Fe2Ni2N used in the simulation exhibits a Ni isotopic abundance of 100% in the Ni layer and a Fe isotopic abundance of 100% in the Fe layer. Similarly, the L10-Fe2Ni2N used in the simulation exhibits a Ni isotopic abundance of 100% in the Ni layer and a Fe isotopic abundance of 100% in the Fe layer.

[0068] As can be seen from the simulation results, L10-Fe2Ni2N and L10-FeNi exhibited different diffraction peak values ​​of the incident angle [2θ (degrees)] when X-ray diffraction was performed. Specifically, two peaks appeared in L10-Fe2Ni2N at an incident angle of approximately 55 degrees, while the diffraction peak was absent in L10-FeNi. In the ordered L10-FeNi alloy actually prepared by the above preparation method, two peaks appeared at an incident angle of approximately 55 degrees. This indicates that L10-Fe2Ni2N is present in the ordered L10-FeNi alloy prepared by the above preparation method. From this result, it can be seen that an ordered L10-FeNi alloy consisting of a doped phase of L10-Fe2Ni2N was successfully prepared by the above preparation method.

[0069] In addition, the coercive force of the ordered L10-FeNi alloy having a mixed phase of L10-FeNi and L10-Fe2Ni2N of the present embodiment was investigated. Fig. 12 shows the result. As a comparison, the coercive force of a conventional ordered L10-FeNi alloy was also investigated. This result is also shown in Fig. 12 shown.

[0070] As shown in this drawing, in the ordered L10-FeNi alloy having a mixed phase of L10-FeNi and L10-Fe2Ni2N according to the present embodiment, the obtained coercive force is 92 [kA / m], which is greater than 87.5 [kA / m]. Furthermore, in the ordered L10-FeNi alloy having a mixed phase of FeNi and Fe2Ni2N according to the present embodiment, the coercive force increases by 4.5 [kA / m] compared to the conventional ordered L10-FeNi alloy. By providing an ordered L10-FeNi alloy having L10-Fe2Ni2N as in the present embodiment, both a high coercive force and a high saturation magnetization can be obtained as in the first embodiment, and the coercive force can be further increased. Further embodiments

[0071] Although the present invention has been described with reference to the above embodiments, the present invention is not limited to the embodiments

[0072] In the embodiments described above, the ordered L10-FeNi alloy provided as the granular particle 1 is obtained, for example, by means of the nitriding treatment and the denitriding treatment. However, the ordered L10-FeNi alloy may be obtained by a method other than the nitriding treatment and the denitriding treatment. Specifically, after a process for synthesizing a compound in which Fe and Ni are aligned in the same lattice structure as in the ordered L10-FeNi structure, a process for removing unnecessary elements other than Fe and Ni from this compound may be performed to obtain the ordered L10-FeNi alloy provided as the granular particle 1. In addition, a process for synthesizing a compound having the same aligned lattice structures as the ordered L10-FeNi alloy need not be performed.

[0073] In the above embodiments, examples of nitriding treatment and denitriding treatment are shown, and an example of gas nitriding treatment and electrochemical treatment performed as a doping process is shown. However, the conditions shown are only examples. As long as a magnetic material comprising an ordered L10-FeNi alloy doped with a light element can be obtained, the above processing examples are not limiting.

[0074] Furthermore, the above embodiments illustrate cases where the granular particles 1 constituting the ordered L10-FeNi alloy have an average particle size of 40 µm and a surface layer 1b thickness of 3 µm. However, these are only examples. The average particle size of the granular particles 1 can be any suitable value and may be within a range of 40 µm + / - 10 µm or more. Furthermore, the thickness of the surface layer 1b does not necessarily have to be 3 µm and may be less or more. As long as the doped phase is formed in at least the surface layer 1b, it is possible to ensure a large saturation magnetization and a large coercive force as in the above embodiments, and the doped phase can be formed over the entire cross section of the granular particle 1.

[0075] After the denitriding treatment described in the second embodiment, the doping process for introducing B or C as the light element may be performed, and further, the doping process for introducing N may be performed by means of the gas nitriding treatment.

[0076] In the second embodiment, in the L10-Fe2Ni2N, when the Ni isotope abundance ratio in the Ni layer is 100% and the Fe isotope abundance ratio in the Fe layer is 100%, the distance a and the distance b satisfy the equation a = b = 0.377 nm, and the distance c satisfies the equation c = 0.374 nm. This is directed to an example of Fe2Ni2N, which has the Ni isotope abundance ratio of 100% in the Ni layer and the Fe isotope abundance ratio of 100% in the Ni layer. However, the Ni isotope abundance ratio in the Ni layer does not need to be 100%, and the Fe isotope abundance ratio in the Ni layer does not need to be 100%. Even in this case, distance a is equal to distance b, and distance c is different from distances a and b. In particular, it may be sufficient if a / c is equal to or greater than 1.005.

Claims

[1] Magnetic material comprising an ordered FeNi alloy, wherein the ordered FeNi alloy with ordered L10 structure is doped with a light element and is provided as a granular particle (1), wherein the granular particle (1) having a main phase not doped with the light element at a central portion (1a) of the granular particle (1) providing the ordered FeNi alloy, and having a doped phase containing the light element in a surface layer (1b) surrounding the central portion (1a). [2] A magnetic material comprising the ordered FeNi alloy according to claim 1, wherein the ordered FeNi alloy is doped with at least one or more elements of B, C and N. [3] A magnetic material comprising the ordered FeNi alloy according to claim 1 or 2, wherein the ordered FeNi alloy has a layered structure of a [001] plane of a face-centered cubic lattice; and the light element is contained in at least one of the following: a middle position of Ni atoms in a Ni layer in which mainly Ni is present; and an intermediate position of Fe atoms in an Fe layer in which mainly Fe is present. [4] A method of producing a magnetic material comprising an ordered FeNi alloy having an ordered L10 structure, the method comprising: Preparing an ordered FeNi alloy provided as a granular particle (1); and after preparing the ordered FeNi alloy, doping a light element into the ordered FeNi alloy. [5] A method of producing a magnetic material comprising an ordered FeNi alloy having an ordered L10 structure, the method comprising: Preparing an ordered FeNi alloy provided as a granular particle (1); and Doping a light element into the ordered FeNi alloy, where doping the light element includes performing an electrochemical treatment using a doping source of one or more elements B, C and N serving as the light element. [6] The method for producing the magnetic material comprising the ordered FeNi alloy according to claim 4 or 5, wherein the doping of the light element includes performing a gas nitriding treatment for doping N as the light element.

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