Ordered FeNi alloy, magnet made of ordered FeNi alloy and method for producing an ordered FeNi alloy

Abstract

Ordered FeNi alloy with an ordered L10 structure, a mean order degree of 0.4 or more in the entire ordered FeNi alloy, wherein the mean order degree is an estimate of a mean order degree in the entire FeNi alloy, which is estimated by X-ray diffraction measurement, and a coercive force of 87.5 kA / m or more, where the average degree of order S in the entire ordered FeNi alloy is expressed as S = (I sup / I fund) obs (I sup / I fund) cal where I sup in (I sup / I fund ) obs an integrated intensity of a superlattice diffraction peak in an X-ray diffraction pattern obtained by X-ray diffraction measurement, I fund in (I sup / I fund ) obsan integrated intensity of a fundamental diffraction peak in the X-ray diffraction pattern obtained by X-ray diffraction measurement, I sup in (I sup / I fund ) cal an integrated intensity of a superlattice diffraction peak in a simulation result of an X-ray diffraction pattern of an ideally ordered L10-FeNi alloy, which has the mean order degree of 1 in the entire ordered L10-FeNi alloy, and I fund in (I sup / I fund ) cal an integrated intensity of a fundamental diffraction peak in the simulation result of the X-ray diffraction pattern of the ideally ordered L10-FeNi alloy, which has a mean order degree of 1 in the entire ordered L10-FeNi alloy, wherein the ordered L10 structure exhibits the superlattice diffraction peak of a (001) plane and where the superlattice diffraction peak is based on a 28° peak in the X-ray diffraction measurement with kβ X-ray radiation of Fe.

Description

Reference to related application

[0001] This application is based on Japanese patent application JP 2017 - 80 025 A, filed on April 13, 2017. Technical area

[0002] The present disclosure relates to an ordered L10-FeNi alloy having an ordered L10 structure and an ordered L10-FeNi alloy magnet made using such an ordered L10-FeNi alloy. State of the art

[0003] An ordered L10-type FeNi (iron-nickel) alloy is expected to be a promising magnetic material and magnetic recording material, which does not use any rare earth element or noble metal. The ordered L10 structure here is a crystal structure with a face-centered cubic lattice as its basic structure, 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 can typically be obtained by thermally treating a random alloy at the order-to-disorder transition temperature Tλ or below and promoting diffusion.

[0004] However, the transition temperature Tλ required to obtain an ordered L10-FeNi alloy is as low as 320 degrees Celsius, and synthesis by thermal treatment alone is difficult because diffusion is extremely slow at this temperature or below. Therefore, various attempts have been made to synthesize an ordered L10-FeNi alloy.

[0005] In particular, a method of alternately stacking single-atom layers of Fe and Ni using molecular beam epitaxy (abbreviation: MBE) as described in Non-Patent Literature 1, a method of performing heat treatment in a magnetic field using neutrons, and the like have been proposed.

[0006] Ordered FeNi alloys of the L10 type, methods for producing them and magnets containing them are described in Patent Literature 1. A method for producing an ordered FeNi alloy of the L10 type is also described in

[0007] Patent Literature 2 discloses. State of the art literature Patent literature 1: WO 2016 / 171 232 A1 Patent literature 2: JP 2016 - 79 484 A Non-patent literature 1: Kojima et al., “Fe-Ni composition dependence of magnetic anisotropy in artificially fabricated L10-ordered FeNi films,” J.Phys.: Condens. Matter, Volume 26, (2014), 064207 Summary of the invention

[0008] However, the degree of order of an ordered L10 FeNi alloy obtained by known methods such as the method using molecular beam epitaxy described in Non-Patent Literature 1 or the method using neutrons is generally low, approximately 0.4 at most. Furthermore, the highest degree of order is not obtained throughout the entire material of the ordered FeNi alloy, but only some parts exhibit a high degree of order. Furthermore, the coercive force of the obtained ordered FeNi alloy is not large enough to use the ordered FeNi alloy as a magnetic material or a magnetic recording material. For example, a magnetic recording material must have a coercive force large enough to prevent the stored data from being overwritten by the ambient magnetic field.

[0009] It is an object of the present disclosure to provide an ordered FeNi alloy usable also as a magnetic material or a magnetic recording material, and to provide an ordered FeNi alloy magnet produced using the alloy.

[0010] In a first aspect of the present disclosure, an ordered FeNi alloy has an ordered L10 structure, an average degree of order of 0.4 or more in the entire ordered FeNi alloy, wherein the average degree of order is an estimate of an average degree of order in the entire FeNi alloy estimated by X-ray diffraction measurement, and a coercive force of 87.5 kA / m or more, wherein the average degree of order S in the entire ordered FeNi alloy is expressed as S=(Isup / Ifund)obs(Isup / Ifund)cal where I sup in (I sup / I fund ) obsis an integrated intensity of a superlattice diffraction peak in an X-ray diffraction pattern obtained by X-ray diffraction measurement, I fund in (I sup / I fund ) obs is an integrated intensity of a fundamental diffraction peak in the X-ray diffraction pattern obtained by the X-ray diffraction measurement, I sup in (I sup / I fund ) cal is an integrated intensity of a superlattice diffraction peak in a simulation result of an X-ray diffraction pattern of an ideally ordered L10-FeNi alloy having the average order degree of 1 in the entire ordered L10-FeNi alloy, and I fund in (I sup / I fund ) calis an integrated intensity of a fundamental diffraction peak in the simulation result of the X-ray diffraction pattern of the ideally ordered L10-FeNi alloy, which has the average order degree of 1 in the entire ordered L10-FeNi alloy, where the ordered L10 structure has the superlattice diffraction peak of a (001) plane and where the superlattice diffraction peak is based on a 28° peak in the kβ X-ray diffraction measurement of Fe.

[0011] If the ordered FeNi alloy has an ordering degree of 0.4 or more and a coercive force of 87.5 kA / m or more, the ordered FeNi alloy can also be used as a magnetic material or a magnetic recording medium. For example, an ordered FeNi alloy magnet can be obtained using the ordered FeNi alloy.

[0012] In a second aspect of the present disclosure, a method for producing an ordered FeNi alloy having an ordered L10 structure comprises: performing a nitriding treatment to nitride a FeNi random alloy (100); and performing a denitriding treatment to remove nitrogen from the nitrided FeNi random alloy to obtain an ordered L10 FeNi alloy having an average degree of order of 0.4 or more in the entire material and a coercive force of 87.5 kA / m or more, wherein in the nitriding treatment, a treatment temperature of the nitriding treatment is greater than or equal to 300 degrees Celsius and less than or equal to 500 degrees Celsius, and a treatment time is 10 hours or more.

[0013] By this method for preparing an ordered FeNi alloy, it is possible to easily synthesize an ordered L10 FeNi alloy with an average degree of order of 0.4 or more throughout the material and a coercive force of 87.5 kA / m or more.

[0014] In a third aspect of the present disclosure, a method for producing an ordered FeNi alloy having an ordered L10 structure comprises: synthesizing a compound in which Fe and Ni are arranged in the same lattice structure as the ordered L10-FeNi structure, and producing an ordered L10-FeNi alloy by removing an unnecessary element other than Fe and Ni from the compound, wherein synthesizing the compound comprises: synthesizing FeNiN as an intermediate of the compound by nitriding a FeNi random alloy at a treatment temperature of greater than or equal to 200 degrees Celsius and less than or equal to 500 degrees Celsius for a treatment time of 10 hours or more, and wherein synthesizing the compound is performed after removing an oxide film from the FeNi random alloy,and the FeNiN as the intermediate is synthesized by nitriding the FeNi random alloy after removing the oxide film.

[0015] In this way, a compound is synthesized in which Fe and Ni are arranged in the same lattice structure as the ordered L10-FeNi structure, and an ordered L10-FeNi alloy is produced from the compound. This preparation method can easily synthesize an ordered L10-FeNi alloy with an average degree of order of 0.4 or more throughout the material and a coercive force of 87.5 kA / m or more.

[0016] It is noted that the reference numerals in parentheses added to the respective elements indicate examples of relationships to concrete elements described in the embodiments described below. Short description of the drawings Fig. Figure 1 is a schematic diagram showing a lattice structure of an ordered L10 FeNi structure. Fig. Figure 2 is a schematic diagram illustrating lattice structures of FeNi alloys with different degrees of order S between a FeNi random alloy with an order degree S of zero and a FeNi superlattice with an order degree S of one. Fig. Figure 3 is a perspective view illustrating processes in preparing a sample for measuring coercive force Hc. Fig. 4 is a table illustrating manufacturing conditions and evaluation results of working examples and comparative examples according to a first embodiment. Fig. 5 is a schematic diagram illustrating a structure of a manufacturing apparatus used for manufacturing ordered FeNi alloys of the working examples and the comparative examples according to the first embodiment. Fig. Figure 6 is a graph showing simulation results of an X-ray diffraction pattern of an ordered L10-FeNi alloy with an order degree S of one. Fig. Figure 7 is a graph showing simulation results of an X-ray diffraction pattern of a FeNi random alloy. Fig. Figure 8 is a graph showing measurement results of X-ray diffraction patterns of ordered FeNi alloys of comparative examples S0, S2 and S3. Fig. Figure 9 is a graph showing measurement results of X-ray diffraction patterns of ordered FeNi alloys of Comparative Examples S1 and S3. Fig. Figure 10 is a graph showing measurement results of X-ray diffraction patterns of ordered FeNi alloys of Comparative Examples S3, S4 and S5. Fig. Figure 11 is a graph showing measurement results of an X-ray diffraction pattern of an ordered FeNi alloy of Working Example S21. Fig. Figure 12 is a graph showing a relationship between the degree of ordering S and the treatment temperature of denitriding treatment with respect to the ordered FeNi alloys of the working examples and the comparative examples. Fig. 13 is a diagram showing a relationship between the degree of order S and the coercive force Hc with respect to the Fig. 4 shows the working examples and comparative examples shown. Fig. Figure 14 is a schematic diagram illustrating lattice structures obtained by subjecting a FeNi random alloy to a nitriding treatment to produce an intermediate product and then performing a denitriding treatment. Fig. Figure 15A is a timing chart showing profiles of oxide film removal treatment and nitriding treatment. Fig. Figure 15B is a time chart showing a profile of a denitriding treatment. Fig. Figure 16 is a diagram showing an X-ray diffraction pattern of an ordered L10 FeNi alloy powder with an order S of one. Fig. Figure 17 is a graph showing a relationship between the degree of order S and the diffraction intensity ratio. Fig. 18 is a diagram showing measurement results of an X-ray diffraction pattern of an ordered L10-FeNi alloy produced by a manufacturing method of a second embodiment. Description of embodiments

[0017] Based on the drawings, embodiments of the present disclosure will be described below. Throughout the description of the embodiments, like reference numerals are used to denote the same or equivalent parts. First embodiment

[0018] The first embodiment will be described. An ordered L10 FeNi alloy according to the present embodiment, that is, an FeNi superlattice, is applied to a magnetic material such as a magnetic material and a magnetic recording medium, and has an ordering degree S of 0.4 or more, a large coercive force Hc of 87.5 kA / m or more, and excellent magnetic properties.

[0019] Here, the degree of order S indicates the degree of order in the FeNi superlattice. As mentioned above, an ordered L10 structure has a face-centered cubic lattice as its basic structure and has a Fig. 1. In this diagram, the upper cover layer in the laminate structure on the

[001] plane of the face-centered cubic lattice is referred to as site I, and the intermediate layer located between the upper cover layer and the lower cover layer is referred to as site II. In this case, the ratio of metal A and metal B present at site I is given by A x B 1-x where x is the proportion of metal A present at site I and 1-x is the proportion of metal B present at site II. Similarly, the ratio of metal A and metal B present at site II is given by A1- x B xwhere x is the proportion of metal B present at site II and 1-x is the proportion of metal A present at site II. Here, x satisfies the relationship 0.5 ≤ x ≤ 1. Furthermore, in this case, the degree of order S is defined as S = 2x-1.

[0020] Accordingly, if metal A and metal B are, for example, Ni and Fe respectively, and if Ni and Fe are white and black respectively, the order degree S of a FeNi alloy is as in Fig. 2, in which the degree of order S is shown between the FeNi random alloy, which has the degree of order S of zero, and the FeNi superlattice, which has the degree of order S of one. In this regard, a completely white circle indicates that the proportion of Ni is 100% and the proportion of Fe is 0%, and a completely black circle indicates that the proportion of Ni is 0% and the proportion of Fe is 100%. Furthermore, a circle that is half white and half black indicates that the proportion of Ni is 50% and the proportion of Fe is 50%.

[0021] With the degree of order S represented in this way, if the ratio of Ni serving as metal A is higher at position I and if the ratio of Fe serving as metal B is higher at position II, for example, resulting in an average degree of order S of a material as a whole of 0.4 or more, as in the present embodiment, excellent magnetic properties can be obtained. However, in this regard, it is required that the degree of order S should be uniform throughout the material, and excellent magnetic properties cannot be obtained if the value is locally large.For example, the degree of order S in all face-centered cubic lattices of the ordered L10 structure should be a predetermined value or greater, and the magnetic properties will not be excellent if the degree of order S of some lattices is locally large, and these local large degrees of order cause the apparent degree of order S to be the same. Here, a case where the value is locally large is not included in the case where the average degree of order S in the entire material is 0.4 or more.

[0022] The coercive force Hc is determined as the intensity of the magnetic field at the point where the magnetization direction of the obtained ordered FeNi alloy changes due to the influence of a magnetic field when the magnetic field is applied to the ordered FeNi alloy. Specifically, as shown in (a) in Fig. 3, a sample holder 1 is prepared with a cylindrical container 1a with a bottom having an inner diameter of 2 mm and a height of 7 mm and a columnar rod element 1b with an outer diameter of 2 mm and a height of 15 mm. The container 1a is then filled with 10 mg of particles of an ordered FeNi alloy, as shown in (b) in Fig. 3, and the ordered FeNi alloy is pressed from the opening of the container 1a with the rod element 1b of another sample holder, as shown in (c) in Fig. 3. In this way, a columnar sample 2 is formed in the container 1a. A sufficiently strong magnetic field is applied to the ordered FeNi alloy sample 2 to reach a saturated state where the magnetization of the sample 2 no longer increases. Then, a magnetic field is applied in the opposite direction, and the moment at which the magnetization of the sample 2 becomes zero is detected. The intensity of the magnetic field at this point is defined as the coercive force Hc. For example, the strength of the magnetic field is determined as a magnetic field sampling rate of 10 [Oe] using a small refrigerant-free PPMS VersaLab manufactured by Quantum Design, Inc. (TM).

[0023] The unit of coercive force Hc in the SI system is kA / m and in the CGS system Oe [Oersted]. Since 1 A / m = 4π×10 -3 [Oe], are 87.5 kA / m = 1100 [Oe].

[0024] For an ordered FeNi alloy to be used as a magnetic material or a magnetic recording medium, the ordered FeNi alloy must have a coercive force Hc required for such a material. As a result of a comprehensive study of the coercive force Hc, the present inventor found that a coercive force Hc of 87.5 kA / m or more is required for an ordered FeNi alloy to be used as a magnetic material or a magnetic recording medium. It was also found that there is a correlation between the degree of order S and the coercive force Hc, and that the average degree of order S of the ordered FeNi alloy should be 0.4 or more in the entire ordered FeNi alloy to make the coercive force Hc of the ordered FeNi alloy 87.5 kA / m or more.

[0025] Accordingly, in the present embodiment, an ordered FeNi alloy with an ordering degree S of 0.4 or more and a coercive force Hc of 87.5 kA / m or more is used. It has also been found that the coercive force Hc of an ordered FeNi alloy also depends on the particle size and the manufacturing method of the ordered FeNi alloy. To obtain a larger coercive force Hc, it is desirable to use an ordered FeNi alloy with a suitable particle size or to use a suitable manufacturing method, as described below.

[0026] Such an ordered L10 FeNi alloy is obtained, for example, by performing a nitriding treatment to nitride a FeNi random alloy and then a denitriding treatment to remove nitrogen from the nitrided FeNi random alloy. A random alloy is an alloy in which the arrangement of atoms is irregular and random.

[0027] The method for producing an ordered L10-FeNi alloy according to the present embodiment will be described specifically with reference to the Fig. 4 shown comparative examples S0 to S17 and working examples S18 to S24 are explained.

[0028] In these working examples and comparative examples, powder samples of FeNi random alloys prepared by a thermal plasma process, a flame spraying process or a coprecipitation process were tested under the conditions described in Fig. The alloys were treated under the nitriding and denitriding conditions shown in Figure 4. The X-ray diffraction patterns of the alloys after the treatments were then measured, and it was assessed whether an ordered L10 structure had formed.

[0029] Here, the composition ratios of the powder samples of the Fig. For the FeNi random alloys of the working examples and comparative examples shown in Figure 4, the atomic weight ratios of Fe:Ni are shown, and the particle sizes are volume-average particle sizes (unit: nm). In addition, the treatment temperatures (unit: °C) and treatment times (unit: h) for the nitriding and denitriding treatment conditions are shown.

[0030] Nitriding and denitriding treatments are carried out, for example, using the Fig. 5. The production device comprises a tube furnace 10, which is heated by a heater 11, and a glove box 20 for providing a sample in the tube furnace 10.

[0031] As in Fig. 5, the manufacturing apparatus also includes a gas introduction element 30 that switches between Ar (argon) as a purge gas, NH3 (ammonia) for the nitriding treatment, and H2 (hydrogen) for the denitriding treatment, and introduces the gases into the tube furnace 10.

[0032] The manufacturing method of the present embodiment using such a manufacturing apparatus is as follows. First, a powder sample of a FeNi random alloy 100 is preliminarily charged into the tube furnace 10. During the nitriding treatment, NH3 gas is introduced into the tube furnace 10 to provide the interior of the tube furnace 10 with an NH3 atmosphere, and the FeNi random alloy is heated to a predetermined temperature for a predetermined period of time and nitrided.

[0033] Then, during the denitriding treatment, H2 gas is introduced into the heating furnace to make the interior of the tube furnace 10 an H2 atmosphere, and the nitrided FeNi random alloy is heated to a predetermined temperature for a predetermined period of time to remove nitrogen. Thus, an ordered L10 FeNi alloy with an average degree of order S of 0.4 or more throughout the material and a coercive force Hc of 87.5 kA / m or more is obtained.

[0034] In the Fig. In the working examples and comparative examples shown in Figure 4, the powder samples of the FeNi random alloys prepared by a thermal plasma process were custom-made products manufactured by Nisshin Engineering Inc. (TM) and had a Fe:Ni composition ratio of 50:50 and a volume-average particle size of 30 nm to 140 nm.

[0035] The powder sample of the FeNi random alloy prepared by a flame spraying process had the product number 677426-5G, manufactured by Sigma-Aldrich (TM) Japan, and had a composition ratio of Fe:Ni of 55:45 and a volume-average particle size of 50 nm.

[0036] The powder sample of the FeNi random alloy prepared by a coprecipitation method was obtained by subjecting FeNi oxide to hydrogen reduction and had a Fe:Ni composition ratio of 47:53 and a volume-average particle size of 200 nm.

[0037] As in Fig. 4, in Comparative Example S0, a FeNi random alloy prepared by a thermal plasma process and having a volume-average particle size of 104 nm and a Fe:Ni composition ratio of 50:50 was evaluated by X-ray diffraction without performing nitriding treatment and denitriding treatment.

[0038] In Comparative Example S1, using the same FeNi random alloy as in Comparative Example S0, nitriding was performed at 300 degrees Celsius for four hours, and the sample was evaluated by X-ray diffraction without performing the denitriding treatment. In Comparative Example S2, using the same FeNi random alloy as in Comparative Example S0, denitriding was performed at 300 degrees Celsius for four hours without performing the nitriding treatment, and the sample was evaluated by X-ray diffraction.

[0039] In Comparative Example S3, using the same FeNi random alloy as in Comparative Example S0, nitriding and denitriding were performed at 300 degrees Celsius for four hours, and denitriding was performed at 300 degrees Celsius for four hours. The sample was then evaluated by X-ray diffraction. In Comparative Example S4, which used the FeNi random alloy prepared by a flame spraying method, nitriding and denitriding were performed in the same manner as in Comparative Example S3, and the sample was evaluated by X-ray diffraction. In Comparative Example S5, which used the FeNi random alloy prepared by a coprecipitation method, nitriding and denitriding were performed in the same manner as in Comparative Example S3, and the sample was evaluated by X-ray diffraction.

[0040] In Comparative Examples S6, S7, S8, and S9, the same procedures as in Comparative Example S3 were performed, except that the treatment temperature in the nitriding treatment was changed to 325 degrees Celsius, 350 degrees Celsius, 400 degrees Celsius, or 500 degrees Celsius. In Comparative Examples S10, S11, S12, S13, S14, S15, and S16, the same procedures as in Comparative Example S3 were performed, except that the treatment temperature of the denitriding treatment was changed to 150 degrees Celsius, 200 degrees Celsius, 250 degrees Celsius, 350 degrees Celsius, 400 degrees Celsius, 450 degrees Celsius, and 500 degrees Celsius. In Comparative Example S17 and Working Examples S18, S19, S20, S21, S22, S23 and S24, samples with a volume-average particle size of 30 nm to 140 nm were used.The nitriding treatment was carried out at a temperature of 300 degrees Celsius for a long period of 50 hours, and the denitriding treatment was carried out at 300 degrees Celsius for one hour. The other conditions were the same as in Comparative Example S3.

[0041] By comparing it with the X-ray diffraction pattern of the ideal ordered FeNi alloy with the degree of order S of one, which is Fig. As shown in Figure 6, it is possible to evaluate whether an ordered L10 structure is formed or not based on X-ray diffraction. When an ordered L10-FeNi alloy is analyzed, in addition to the fundamental diffraction peak P2, peaks called superlattice diffraction peaks P1 are observed at the positions indicated by the arrows, as shown in Fig. 6 shown.

[0042] When a FeNi random alloy is analyzed, although the fundamental diffraction peak P2 is observed, the superlattice diffraction peaks P1 are not observed, as shown in Fig. 7. Here, in Fig. 6 and Fig. 7 assumed that the X-ray radiation is a kβ radiation from Fe Wavelength: 1.75653 Å = 0.175653 nm.

[0043] Based on the above points, it was determined for the working examples and comparative examples that an ordered L10 structure was formed when the superlattice P1 diffraction peaks were observed in the pattern measured by X-ray diffraction, and that no ordered L10 structure was formed when the superlattice P1 diffraction peaks were not observed. The determination was made by observing whether the peaks at 28° and 40°, which are particularly easily observed among the superlattice P1 diffraction peaks, were clearly visible.

[0044] In Fig. 4, the sample is labeled “YES” if an ordered L10 structure was formed, and the sample is labeled “NO” if no ordered L10 structure was formed. As in Fig. 4, the samples marked with “YES” are Comparative Examples S3 to S9, S11 to S14 and S17 and Working Examples S18 to S24, and the samples marked with “NO” are Comparative Examples S0 to S2, S10, S15 and S16.

[0045] Furthermore, the order degrees S of the samples in which an ordered L10 structure was formed among the working examples and the comparative examples were estimated based on the method described in Non-Patent Literature 1. This estimation of the order degrees S can be performed using the following equation for estimating the order degree S for an ordered L10 FeNi alloy. S=(Isup / Ifund)obs(Isup / Ifund)cal

[0046] In the mathematical expression 1, I sup the integrated intensity of the superlattice diffraction peaks P1. I fund is the integrated intensity of the fundamental diffraction peak P2. (I sup / I fund ) obs is the ratio of the integrated intensity of the superlattice diffraction peaks P1 and the integrated intensity of the fundamental diffraction peak P2 in the X-ray diffraction pattern measured in each of the working examples and comparative examples. (I sup / I fund ) cal is the ratio of the integrated intensity of the superlattice diffraction peaks P1 and the integrated intensity of the fundamental diffraction peak P2 in the X-ray diffraction pattern of Fig. 6. As shown by mathematical expression 1, the square root of the ratios is determined as the degree of order S.

[0047] Some typical examples of the X-ray diffraction patterns measured in the working examples and the comparative examples are shown in Fig. 8, Fig. 9, Fig. 10 and Fig. 11. Based on these X-ray diffraction patterns, it is explained whether ordered L10-FeNi alloys were obtained or not, and explanations are given of the relationships with the degree of order S and the coercive force Hc.

[0048] As in Fig. As shown in Figure 8, in Comparative Example S3, in which both the nitriding treatment and the denitriding treatment were performed, the superlattice diffraction peaks P1 were clearly observed at 28° and 40°. In contrast, in Comparative Example S0, in which the nitriding treatment and the denitriding treatment were not performed, and in Comparative Example S2, in which only the denitriding treatment was performed without performing the nitriding treatment, the superlattice diffraction peaks P1 were not observed. Fig. 8, it should be noted that the peak marked with the inverted triangle in Comparative Example S0 was due to FeNi oxide and was not the superlattice diffraction peak P1. These results demonstrate that an ordered L10 FeNi alloy was obtained by performing both nitriding and denitriding treatments.

[0049] In addition, as in Fig. As shown in Figure 4, comparative examples S0 and S2 had degrees of order S equal to zero, since no ordered L10-FeNi alloy was formed, and exhibited low coercive forces Hc, namely 10.2 kA / m and 4.0 kA / m, respectively. Comparative example S3 had a relatively high degree of order S, namely 0.52, and a coercive force Hc of 33.3 kA / m, which is not a high value.

[0050] As in Fig. As shown in Figure 9, the superlattice diffraction peaks P1 at 28° and 40° were clearly observed in Comparative Example S3, in which both the nitriding treatment and the denitriding treatment were performed, while the superlattice diffraction peaks P1 were not observed in Comparative Example S1, in which only the nitriding treatment was performed without the denitriding treatment. Fig. 9, in Comparative Example S1, peaks indicated by black circles were observed at positions different from those of the superlattice diffraction peaks P1, and these peaks were due to nitrided FeNi and were not the superlattice diffraction peaks P1. In Comparative Example S1, the nitriding treatment was performed, while the denitriding treatment was not performed, and a nitride of FeNi was obtained. As shown in Fig. As shown in Figure 4, Comparative Example S1 had zero degree of ordering since no ordered L10-FeNi alloy was formed and had a low coercive force Hc, namely 4.0 kA / m.

[0051] As in Fig. As shown in Figure 10, although the preparation method for the powder sample of the FeNi random alloy and the volume-average particle size were different among Comparative Examples S3, S4, and S5, the superlattice diffraction peaks P1 at 28° and 40° were clearly observed in all cases. The difference in the volume-average particle size is easily observed by observation with an electron microscope. By performing the nitriding treatment and the denitriding treatment, it is possible to prepare an ordered L10 FeNi alloy even when using samples prepared by different preparation methods and having different particle sizes. As shown in Fig. However, as shown in Figure 4, although the degree of order S of Comparative Example S4 was a relatively high value, namely 0.41, the coercive force Hc was a low value, namely 29.9 kA / m. Furthermore, the degree of order S of Comparative Example S5 was a low value, namely 0.37, and the coercive force Hc was also a low value, namely 27.6 kA / m.

[0052] The method for preparing the powder sample of the FeNi random alloy of Working Example S21 was almost the same as that of Comparative Example S3, except that the nitriding and denitriding times were 50 hours and 1 hour, respectively. Fig. 11, the superlattice diffraction peaks P1 at 28° and 40° were clearly observed in Working Example S21. Furthermore, the volume-average particle size was relatively large, namely 140 nm. As shown in Fig. As shown in Figure 4, the degree of order S of the working example S21 had a high value, namely 0.64, and the coercive force Hc also had a high value, namely 150.6 kA / m.

[0053] When at least one of the nitriding and denitriding treatments was omitted, as in Comparative Examples S0 to S2, an ordered L10 FeNi alloy could not be produced. Furthermore, the degree of order S was low, and the coercive forces were also low.

[0054] In contrast, it is possible to produce an ordered L10-FeNi alloy by performing nitriding and denitriding treatments, as shown in Comparative Examples S3 to S17. However, when the nitriding treatment time was short, a sufficient coercive force Hc value could not be obtained even though a degree of ordering S could be obtained at a certain level. Furthermore, when the denitriding treatment temperature was too low, as in Comparative Example S10, or when the denitriding treatment temperature was too high, as in Comparative Examples S15 and S16, an ordered L10-FeNi alloy could not be produced. In these cases, the degree of ordering S was zero, and the coercive forces Hc were low.

[0055] The relationships of the parameters with the degree of order S and the coercive force Hc are now described with reference to the above ordered FeNi alloys.

[0056] First, the relationship of the degree of ordering S or the coercive force Hc with the conditions for denitriding treatment or the conditions for nitriding treatment, the relationship between the coercive force Hc and the volume-average particle size, and the relationship between the degree of ordering S and the coercive force Hc are described.

[0057] Fig. 12 shows the relationship between the degree of order S and the treatment temperature of the denitriding treatment with respect to Comparative Examples S6 and S10 to S16, in which the same nitriding treatments were carried out using the same sample, but in which the treatment temperatures of the denitriding treatment were different.

[0058] From the Fig. The results shown in Figure 12 indicate that the treatment temperature for denitriding is desirably 250 degrees Celsius or more and 400 degrees Celsius or less. As shown in Fig. As shown in Figure 12, in Comparative Examples S12, S6, S13, and S14, where the denitriding treatment temperatures were 250 degrees Celsius or higher and 400 degrees Celsius or lower, order levels S of 0.4 or more were achieved. In these examples, the order levels S were higher, i.e., 0.5 or more. Although in Fig. 12, the degree of order S was also 0.4 or higher in Comparative Example S17 and Working Examples S18 to S24, where the denitriding treatment temperatures were 250 degrees Celsius or more and 400 degrees Celsius or less. However, the degree of order S was less than 0.4 in Comparative Examples S10 and S11, where the treatment temperatures were lower than 250 degrees Celsius, and in Comparative Examples S15 and S16, where the treatment temperatures were 450 degrees Celsius or higher, the superlattices were decomposed because the treatment temperatures were too high.

[0059] From the Fig. From the results shown in Figure 4, it can be seen that a short period of one hour or less is suitable for the denitration treatment. As shown by Comparative Examples S3, S4, S6 to S9, S12 to S14 and S17 and Working Examples S18 to S24 in Fig. 4, the desired order levels S were obtained when the treatment was carried out for four hours or one hour. In addition, as shown by the working examples S18 to S24 in Fig. 4, the coercive forces Hc were 87.5 kA / m or more even when the denitriding treatment times were short. On the other hand, as shown by Comparative Examples S2 to S17, the coercive forces Hc were not always 87.5 kA / m or more regardless of the denitriding treatment time. From the results, it was found that, with regard to the degree of order S and the coercive force Hc, it is possible to use a short denitriding treatment time as long as it is possible to produce an ordered FeNi alloy by performing the denitriding treatment.

[0060] From the Fig. 4, it is clear that the treatment temperature of the nitriding treatment is desirably 300 degrees Celsius or more and 500 degrees Celsius or less. As shown by Comparative Examples S3 to S9 and S11 to S14 in Fig. As shown in Figure 4, ordered FeNi alloys were obtained in all cases where the nitriding temperatures were in the range of 300 degrees Celsius or higher and 500 degrees Celsius or lower. Accordingly, it can be assumed that an ordered FeNi alloy can be obtained in this temperature range.

[0061] However, the results obtained show that if the treatment time of the nitriding treatment is short, undesirable results are obtained. That is, in the case where the treatment temperature of the nitriding treatment was 325 degrees Celsius, as in Comparative Examples S12 to S14 in Fig. 4, the coercive forces Hc were lower than 87.5 kA / m even though the order levels S were 0.4 or more, even when the treatment time was four hours. On the other hand, when the treatment temperature of the nitriding treatment was 300 degrees Celsius, as in Working Examples S18 to S24, when the treatment time was 50 hours, the order levels S were 0.4 or more, and the coercive forces Hc were large, namely 87.5 kA / m or more, resulting in excellent magnetic properties. Thus, the treatment time of the nitriding treatment is an important element for achieving a high coercive force Hc. As a result of various experiments, the coercive force Hc was 87.5 kA / m or more when the treatment times were set to 10 hours or longer. The duration varies slightly with the nitriding temperature, and the treatment time can be slightly shortened as the treatment temperature becomes higher.A high coercive force Hc was successfully obtained by setting the treatment time at 300 degrees Celsius for 10 hours or more, which is the lowest within the appropriate temperature range for nitriding treatment. Accordingly, at temperatures above 300 degrees Celsius, the coercive force Hc can be as high as 87.5 kA / m or more if the treatment time at temperatures above 300 degrees Celsius is set for at least 10 hours or more.

[0062] In this respect, the Fig. In the examples shown in Figure 4, examples of nitriding treatment temperatures are shown as 300 degrees Celsius, 325 degrees Celsius, 350 degrees Celsius, 400 degrees Celsius, and 500 degrees Celsius. However, the nitriding treatment temperature is not limited to these examples. The treatment temperature may have a wider range of temperatures as long as the nitriding treatment temperature is at least within a range of 300 degrees Celsius or higher and 500 degrees Celsius or lower in the cases of the manufacturing method of the present embodiment.

[0063] Furthermore, it was found that the coercive force Hc is also influenced by the volume-average particle size. Specifically, the coercive force Hc is larger as the volume-average particle size increases. As shown in Fig. As shown in Figure 4, the coercive force Hc was larger as the volume-average particle size became larger in the cases of Comparative Example S17 and Working Examples S18 to S24. When the volume-average particle size was 30 nm, as in Comparative Example S17, the coercive force Hc was a relatively large value, namely 58.1 kA / m, but this value was not large enough for use as a magnetic material or a magnetic recording medium. However, when the volume-average particle sizes were 45 nm, 60 nm, 80 nm, 120 nm, 140 nm, 130 nm, and 100 nm, respectively, as in Working Examples S18 to S24, the coercive forces Hc were all 87.5 kA / m or more.

[0064] Thus, by setting the volume-average particle size to 45 nm or more, it is possible to obtain not only the degree of order S of 0.4 or more but also a high coercive force Hc of 87.5 kA / m or more. Although the coercive force Hc generally increases as the volume-average particle size increases, the coercive force Hc decreases after the volume-average particle size exceeds the size of a single domain. For example, in some cases, the coercive force Hc decreases when the volume-average particle size exceeds 250 nm. Accordingly, it is desirable that the volume-average particle size not be too large. Although a volume-average particle size exceeding 250 nm is usable, the desired coercive force Hc can be more reliably achieved when the volume-average particle size is, for example, 60 nm or more and 250 nm or less.

[0065] In addition, the degree of order S is closely related to the coercive force Hc. That is, the coercive force Hc is larger when the degree of order S is larger. As in Fig. As shown in Figure 13, it becomes possible to produce an alloy with a coercive force Hc of 87.5 kA / m when the degree of order S is 0.4 or more. When the degree of order S is 0.6 or more, it becomes possible to produce an alloy with a coercive force Hc of 87.5 kA / m or more with a high probability. Of course, only a large degree of order S always makes it possible to obtain the desired coercive force Hc, as shown in Fig. 13, but in general, the coercive force Hc increases with increasing order S. In particular, when the order S is 0.7 or more, it becomes possible to obtain a coercive force Hc of 95.5 kA / m (1200 [Oe]) or more.

[0066] As described above, the ordered FeNi alloy can also be used as a magnetic material or a magnetic recording medium because the ordered FeNi alloy has an ordering degree S of 0.4 or more and a coercive force Hc of 87.5 kA / m or more in the present embodiment. In particular, when the ordering degree S is 0.7 or more and the coercive force Hc is 95.5 kA / m, an excellent magnetic material or an excellent magnetic recording medium with a larger coercive force Hc can be obtained. For example, when a magnetic powder is obtained from particles of an ordered L10 FeNi alloy having such a high ordering degree S and a high coercive force Hc and compressed into a magnetic shape, an ordered FeNi alloy magnet can be obtained.

[0067] A magnet made of an ordered FeNi alloy produced in this way can be applied, for example, to a motor magnet carried in a vehicle or the like. Furthermore, by coating a tape-shaped film with particles of the ordered FeNi alloy, a magnetic tape used as a magnetic recording medium, for example, can be configured. Since the ordered FeNi alloy obtained in the present embodiment has a high coercive force Hc, overwriting of the stored data by the ambient magnetic field can be limited when the ordered FeNi alloy is used as the magnetic material of a magnetic recording medium.

[0068] To obtain such an ordered FeNi alloy, after performing the nitriding treatment for nitriding the FeNi random alloy 100, the denitriding treatment can be performed to remove nitrogen from the nitrided FeNi random alloy. During the nitriding treatment, the treatment temperature is 300 degrees Celsius or more and 500 degrees Celsius or less, and the treatment time is 10 hours or more. During the denitriding treatment, the treatment temperature is 250 degrees Celsius or more and 400 degrees Celsius or less.

[0069] Regarding the composition of Fe, a composition close to 50 at.% is a composition with which an ordered L10-FeNi alloy can be easily obtained. In the present embodiment, a high degree of order S of 0.4 or more is achieved with an alloy with a composition in the range of Fe: 55 to 47 at.%, as shown by the above working examples and comparative examples.

[0070] The sample shape of the FeNi random alloy is not specified, but a powder sample is desirable, as described above, to shorten the nitriding and denitriding treatments. Since the nitriding treatment, in particular, is time-consuming, a nanoparticle sample of the FeNi random alloy is desirable to perform the treatments quickly. Furthermore, by setting the volume-average particle size to 45 nm or more, an ordered FeNi alloy with a higher coercive force Hc can be obtained.

[0071] In the present embodiment, the ordering of powders of FeNi random alloys prepared by various methods was investigated as described above. In particular, the method for preparing the random alloy is not limited to the thermal plasma method, the flame spraying method, or the coprecipitation method described above. Although this is Fig. 4 is not shown, when random alloys produced by a random alloy production method other than a thermal plasma method such as a flame spraying method or a coprecipitation method are used, and when the nitriding treatment conditions and the denitriding conditions are the same as the conditions of Working Examples S18 to S24, similar results to those of the Working Examples can be obtained.

[0072] In addition, to produce an ordered L10-FeNi alloy, the nitrogen concentration of the nitride produced by the nitriding treatment is desirably about 20 at% to 33 at%, expressed as an atomic weight ratio, based on the total amount of Fe, Ni and nitrogen.

[0073] According to the present embodiment, by nitriding with ammonia gas and denitriding with hydrogen gas as described above, an ordered L10-FeNi alloy can be obtained without contamination with impurities, but this does not limit the nitriding process and the denitriding process.

[0074] As demonstrated by the above working examples and comparative examples, by performing the denitriding treatment to remove nitrogen after subjecting the FeNi random alloy to the nitriding treatment, an ordered L10-FeNi alloy with a high degree of order S of 0.4 or more and a high coercive force Hc of 87.5 kA / m or more can be obtained. This is a simple method in terms of both the device and the steps compared to the above-described conventional layering method using molecular beam epitaxy and the conventional heat treatment method using neutrons. Therefore, according to the present embodiment, an ordered L10-FeNi alloy with a desired degree of order S and a desired coercive force Hc can be easily synthesized. Second embodiment

[0075] The second embodiment will be described. This embodiment enables a further increase in the degree of order S compared to that of the first embodiment. The basic manufacturing steps of the present embodiment are the same as those of the first embodiment, and therefore only the points that differ from the first embodiment will be described.

[0076] In order to further increase the degree of order S, in the present embodiment, when an ordered L10-FeNi alloy is produced from a FeNi random alloy, an intermediate product is produced. Although nitriding and denitriding are performed in the first embodiment, in the present embodiment, when the nitriding treatment is completed, FeNiN is produced as an intermediate product. In order to produce the intermediate product by the nitriding treatment with high accuracy, a treatment for removing an oxide film formed on the surface of the FeNi random alloy is performed before the nitriding treatment. By performing the denitriding treatment, the ordered L10-FeNi alloy is produced from FeNiN serving as the intermediate product.

[0077] In particular, as in Fig. 14, the FeNi random alloy is subjected to nitriding treatment, and FeNiN, which acts as an intermediate and contains many Ni atoms at site II, is formed by incorporating nitrogen into the Fig. Site II shown in Figure 1 is created. By performing the denitriding treatment and releasing nitrogen from site II, the ordered L10-FeNi alloy is provided.

[0078] First, a FeNi random alloy is prepared. Since an oxide film is present on the surface of the FeNi random alloy, a stripping treatment is performed to remove the oxide film on the surface of the FeNi random alloy before the nitriding treatment. Nitriding is then performed after the stripping treatment.

[0079] As a removal treatment, a heat treatment is performed at, for example, between 300°C and 450°C in an oxide film etching atmosphere. As a result, the oxide film on the surface of the FeNi random alloy is removed, and the surface enters a state that can be easily nitrided. As a nitriding treatment, a heat treatment is performed at, for example, between 200°C and 400°C in an atmosphere containing N. As a result, the FeNi random alloy, which is easily nitrided after the oxide film is removed, can be accurately nitrided, and FeNiN is produced as an intermediate. In this case, since the nitriding treatment is performed after the oxide film is removed, the nitriding reaction proceeds more easily, and thus the temperature can be lower than that of the first embodiment.Thus, the temperature of the nitriding treatment ranges from 200 °C to 400 °C, although the temperature may exceed 400 °C and may be 500 °C or less, as in the first embodiment.

[0080] Next, FeNiN, as the intermediate, is subjected to denitriding. Denitriding involves heat treatment, for example, between 200 and 400 degrees Celsius in a denitriding atmosphere. As a result, nitrogen leaves the intermediate, and the ordered L10-FeNi alloy can be produced. By producing FeNiN as the intermediate and then producing the ordered L10-FeNi alloy in this way, a higher degree of order S can be achieved.

[0081] A specific example is described in which an ordered L10-FeNi alloy was actually produced by the removal treatment, the nitriding treatment, and the denitriding treatment.

[0082] First, according to the Fig. The removal treatment and the nitriding treatment were carried out on the profiles shown in Figure 15A.

[0083] Specifically, a heating furnace such as tube furnace 10 or a muffle furnace was prepared, and a nanoparticle sample of a FeNi random alloy with an average particle size of 30 nm was placed into the heating furnace. Then, to remove the oxide film, the heating furnace was heated from room temperature to the removal temperature, 400 degrees Celsius in this case. At this time, an inert gas was introduced to limit the oxidation of the nanoparticle sample due to the oxygen in the heating furnace, and the heating step was performed while introducing N2 (nitrogen).

[0084] Although N2 was used as the inert gas, which can also be used in the subsequent nitriding treatment, inert gases other than N2 can also be used, such as Ar (argon) and He (helium).

[0085] After the furnace was heated to the removal temperature, the introduction of N2 was stopped, and an oxide film etching gas was introduced to create an etching atmosphere. Then, the furnace temperature was maintained at a temperature required for oxide film removal for a predetermined period of time. In this experiment, H2 (hydrogen) was used as the etching gas, and H2 was introduced into the furnace at a rate of 1 l / min. The furnace was maintained at 400 degrees Celsius for one hour. Thus, the oxide film on the surface of the nanoparticle sample was removed.

[0086] The time required to remove the oxide film can be any suitable time, but it has been found that it is possible to remove the oxide film to a certain extent, for example, in a period of 10 minutes or longer. The temperature for removing the oxide film can be at least between 300°C and 450°C.

[0087] The lower limit of the oxide film removal temperature is specified as 300 degrees Celsius because it has been found that the oxide film is removable at least at 300 degrees Celsius or higher. However, it is believed that the oxide film can be removed even at a temperature below 300 degrees Celsius if enough time is used. The upper limit of the oxide film removal temperature is specified so that the subsequent nitriding of the FeNi random alloy is easy to carry out. That is to say, if the oxide film removal temperature is higher than 450 degrees Celsius, the surface of the FeNi random alloy will be sintered after the oxide film is removed and will be difficult to nitride. Therefore, a temperature of 450 degrees Celsius or less is specified to limit the sintering of the surface of the FeNi random alloy.The rate for introducing the etching gas into the heating furnace is also any suitable rate, and in the case of H2, for example, the oxide film was removable at at least one rate in the range of 0.3 to 5 l / min.

[0088] After the oxide film removal treatment was completed, nitriding treatment was then performed in the same heating furnace. Specifically, by switching the gas introduced into the heating furnace from etching gas to nitriding gas, the interior of the heating furnace had an atmosphere containing N, and the temperature was maintained at a temperature required for nitriding. In this experiment, NH3 (ammonia) was used as the nitriding gas and introduced into the heating furnace at a rate of 5 l / min, and the heating furnace was maintained at 300 degrees Celsius for 50 hours. In this way, the nanoparticle sample was nitrided, and FeNiN was generated as an intermediate product.

[0089] The time required for the nitriding treatment is any suitable time, although it has been found that FeNiN as an intermediate, for example, can be synthesized in 10 hours. The temperature of the nitriding treatment can be at least between 200 degrees Celsius and 400 degrees Celsius. The rate for introducing the nitriding gas into the heating furnace to create an atmosphere containing N is also any suitable rate, and in the case of NH3, for example, a nanoparticle sample was nitrided at at least a rate in the range of 0.1 to 10 l / min.

[0090] After removing the oxide film in this way, the nitriding treatment was subsequently performed. This makes it possible to suppress the formation of another oxide film on the surface of the FeNi random alloy after the oxide film has been removed, and it eliminates the need for a further heating step. Thus, it is possible to simplify the heat treatment and shorten the time required.

[0091] Subsequently, denitriding was performed. The denitriding was performed according to the profile shown in Figure 15B. Although in this example, the denitriding was performed some time after the nitriding, it is possible to perform the treatments sequentially.

[0092] First, a heating furnace such as tube furnace 10 or a muffle furnace was prepared, and FeNiN as the material according to the profile in Fig. The intermediate product produced in Example 15A was placed in the heating furnace. The heating furnace was then heated from room temperature to the temperature of the denitriding treatment, namely 300 degrees Celsius in this example. At this time, an inert gas was also introduced to limit the oxidation of FeNiN, the intermediate product, due to the oxygen in the heating furnace, and the heating step was carried out while introducing N2.

[0093] After the furnace was heated to the denitriding temperature, the introduction of N2 was stopped, and an atmosphere suitable for denitriding was created. Then, the furnace temperature was maintained at a temperature required for denitriding for a predetermined period of time. In this experiment, the atmosphere suitable for denitriding was created using H2 (hydrogen), and H2 was introduced into the furnace at a rate of 1 l / min. The furnace was maintained at 300 degrees Celsius for four hours. Thus, FeNiN was denitrided as the intermediate product.

[0094] The time required for the denitriding treatment is any suitable time, but it has been found possible to produce an ordered L10 FeNi alloy by conducting the denitriding treatment for, for example, one hour or more. It has also been found that a denitriding treatment temperature of at least between 200 degrees Celsius and 400 degrees Celsius is preferred. The rate for introducing the gas into the heating furnace to create an atmosphere in which the denitriding treatment can be carried out is also any suitable rate, and in the case of H2, the denitriding treatment has been successfully carried out at, for example, at least a rate in the range of 0.1 to 5 l / min.

[0095] By performing the denitriding treatment described above, an ordered L10-FeNi alloy was successfully produced. The average degree of order S of the ordered L10-FeNi alloy produced in this way was determined throughout the material. Specifically, the degree of order S was determined using a powder X-ray diffraction pattern.

[0096] For example, the X-ray diffraction pattern of a powder of an ordered L10-FeNi alloy, in which the degree of order S is equal to one, is as in Fig. 16. In the X-ray diffraction pattern, the order degree S has the Fig. 17 with the diffraction intensity ratio, which is the ratio of the integrated intensity of the diffraction peak of the (001) plane as the superlattice reflection, i.e., the superlattice diffraction peak, and the integrated intensity of the diffraction peak of the (111) plane, i.e., the fundamental diffraction peak. Accordingly, the X-ray diffraction pattern of the ordered L10-FeNi alloy produced as in the present embodiment can be determined, and the degree of ordering S can be obtained from the results.

[0097] Specifically, as in the present embodiment, FeNiN was produced as an intermediate by performing the removal treatment of an oxide film of a random FeNi alloy and then the nitriding treatment, and an ordered L10 FeNi alloy was produced by further performing the denitriding treatment. Then, the X-ray diffraction pattern was determined. Fig. shows the results.

[0098] As in Fig. As shown in Figure 18, it is evident that a FeNi superlattice was formed, since the superlattice diffraction peak was observed from the (001) plane. Based on the results, the diffraction intensity ratio was calculated, and the diffraction intensity ratio was 0.8. The degree of order S at the diffraction intensity ratio of 0.8 was determined from Fig. 17, and the degree of order S was a large value, namely 0.71.

[0099] In this way, a high degree of order S was successfully obtained with respect to the ordered L10-FeNi alloy produced by the manufacturing method of the present embodiment. Furthermore, the magnetic properties of the ordered L10-FeNi alloy were evaluated, and a relatively high anisotropic magnetic field of 1120 kA / m was successfully obtained.

[0100] As explained above, in the present embodiment, a random FeNi alloy is subjected to nitriding treatment to produce FeNiN as an intermediate, and an ordered L10 FeNi alloy is produced by further performing denitriding treatment. By such a production method, it is possible to easily produce an ordered L10 FeNi alloy with a high average order degree S of 0.7 or more throughout the material. By achieving such a high order degree S, it is possible to provide an ordered FeNi alloy with a high coercive force Hc. Accordingly, it is possible to easily obtain an ordered FeNi alloy with a coercive force Hc of 87.5 kA / m or more.

[0101] In particular, by performing the nitriding treatment after performing the stripping treatment to remove the oxide film on the surface of the FeNi random alloy, it is possible to produce the intermediate product more accurately. Accordingly, by performing the stripping treatment, it is possible to obtain an ordered L10 FeNi alloy with a higher degree of order S.

[0102] It has been found that the present embodiment differs from the first embodiment in that the oxide film is removed; the intermediate product is obtained by the nitriding treatment; and it is possible to lower the treatment temperature of the nitriding treatment. Other points, such as the duration of the denitriding treatment and the volume-average particle size, are the same as in the first embodiment.

[0103] While the present disclosure has been described with reference to the above-described embodiments, the present disclosure covers various modifications and equivalent arrangements. Despite the various combinations and configurations, other combinations and configurations are also included within the spirit and scope of the present disclosure, including more, fewer, or only a single element.

[0104] For example, although the conditions for the nitriding treatment and the denitriding treatment are illustrated in the first embodiment, the illustrated conditions are merely examples. That is, as long as an ordered L10-FeNi alloy with an ordering degree S of 0.4 or more and a coercive force Hc of 87.5 kA / m or more can be obtained by the nitriding treatment and the denitriding treatment, the treatment temperatures and treatment times are not limited to the examples. Similarly, although the conditions for the oxide film removal treatment, the nitriding treatment, and the denitriding treatment are illustrated in the second embodiment, the conditions are merely examples.That is, the treatment temperatures and treatment times of the treatments are not limited to the examples, as long as an ordered L10 FeNi alloy with an ordering degree S of 0.4 or more and a coercive force Hc of 87.5 kA / m or more can be obtained.

[0105] Furthermore, although in the first and second embodiments, nitriding and denitriding are performed to obtain an ordered L10-FeNi alloy, a process other than nitriding and denitriding may be performed to obtain an ordered L10-FeNi alloy. Specifically, an ordered L10-FeNi alloy can be obtained by performing a treatment to synthesize a compound in which Fe and Ni are arranged in the same lattice structure as the ordered L10-FeNi structure, and then performing a treatment to remove an unnecessary element other than Fe and Ni from the compound.

[0106] Although the ordered L10 FeNi alloy according to the above embodiments is applied to a magnetic material such as a magnetic material and a magnetic recording material, the application range of the ordered FeNi alloy is not limited to these magnetic materials.

Claims

[1] Ordered FeNi alloy with an ordered L10 structure, an average degree of order of 0.4 or more in the entire ordered FeNi alloy, wherein the average degree of order is an estimate of an average degree of order in the entire FeNi alloy estimated by X-ray diffraction, and a coercive force of 87.5 kA / m or more, where the average degree of order S in the entire ordered FeNi alloy is expressed as S=(Isup / Ifund)obs(Isup / Ifund)cal where I sup in (I sup / I fund ) obs is an integrated intensity of a superlattice diffraction peak in an X-ray diffraction pattern obtained by X-ray diffraction measurement, I fund in (I sup / I fund ) obsis an integrated intensity of a fundamental diffraction peak in the X-ray diffraction pattern obtained by the X-ray diffraction measurement, I sup in (I sup / I fund ) cal is an integrated intensity of a superlattice diffraction peak in a simulation result of an X-ray diffraction pattern of an ideally ordered L10-FeNi alloy having the average order degree of 1 in the entire ordered L10-FeNi alloy, and I fund in (I sup / I fund ) cal is an integrated intensity of a fundamental diffraction peak in the simulation result of the X-ray diffraction pattern of the ideally ordered L10-FeNi alloy, which has the average order degree of 1 in the entire ordered L10-FeNi alloy, where the ordered L10 structure has the superlattice diffraction peak of a (001) plane and where the superlattice diffraction peak is based on a 28° peak in the kβ X-ray diffraction measurement of Fe. [2] The ordered FeNi alloy according to claim 1, further having a volume average particle size of 45 nm or more. [3] Ordered FeNi alloy according to claim 1 or 2, wherein the degree of order is 0.7 or more and the coercive force is 97.5 kA / m or more. [4] An ordered FeNi alloy magnet comprising an ordered FeNi alloy according to any one of claims 1 to 3. [5] A process for producing an ordered FeNi alloy having an ordered L10 structure, comprising Carrying out a nitriding treatment to nitride a FeNi random alloy (100) and Performing a denitriding treatment to remove nitrogen from the nitrided FeNi random alloy to obtain an ordered L10 FeNi alloy with an average degree of order of 0.4 or more throughout the material and a coercive force of 87.5 kA / m or more, wherein in the nitriding treatment, a treatment temperature of the nitriding treatment is greater than or equal to 300 degrees Celsius and less than or equal to 500 degrees Celsius and a treatment time is 10 hours or more. [6] A process for producing an ordered FeNi alloy having an ordered L10 structure, comprising Synthesizing a compound in which Fe and Ni are arranged in the same lattice structure as the ordered L10-FeNi structure, and Producing an ordered L10-FeNi alloy by removing an unnecessary element other than Fe and Ni from the compound, wherein synthesizing the compound comprises Synthesizing FeNiN as an intermediate of the compound by nitriding a FeNi random alloy at a treatment temperature of greater than or equal to 200 degrees Celsius and less than or equal to 500 degrees Celsius for a treatment time of 10 hours or more, and wherein synthesizing the compound is carried out after removing an oxide film from the FeNi random alloy, and FeNiN is synthesized as the intermediate by nitriding the FeNi random alloy after removing the oxide film.

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