Sm-Fe-N-based magnetic materials and method for manufacturing the same

Abstract

The present disclosure relates to an Sm-Fe-N-based magnetic material and a method for manufacturing the same. The magnetic material of the present disclosure includes a main phase having a specified crystal structure. The main phase has a composition represented by (Sm (1‑x‑y‑z) La x Ce y R 1 z )2(Fe (1‑p‑q‑s) Co p Ni q M s ) 17 N h (where R 1 is a specified rare earth element, etc., M is a specified element, and 0.04 ≦ x + y ≦ 0.50, 0 ≦ z ≦ 0.10, 0 ≦ p + q ≦ 0.10, 0 ≦ s ≦ 0.10, and 2.9 ≦ h ≦ 3.1 are satisfied.). The crystal volume of the main phase is 0.833 to 0.840 nm 3 . The method for manufacturing the magnetic material of the present disclosure includes nitriding a magnetic material precursor having a crystal phase with a composition represented by (Sm (1‑x‑y‑z) La x Ce y R 1 z )2(Fe (1‑p‑q‑s) Co p Ni q M s ) 17 .

Description

Technical Field

[0001] The present disclosure relates to an Sm-Fe-N-based magnetic material and a method for manufacturing the same. The present disclosure particularly relates to an Sm-Fe-N-based magnetic material having a main phase with at least one crystal structure of Th2Zn 17 type and Th2Ni 17 type and a method for manufacturing the same. Background Art

[0002] As high-performance magnetic materials, Sm-Co-based magnetic materials and Nd-Fe-B-based magnetic materials have been put into practical use. In recent years, magnetic materials other than these have been studied. For example, an Sm-Fe-N-based magnetic material having a main phase with at least one crystal structure of Th2Zn 17 type and Th2Ni 17 type (hereinafter sometimes simply referred to as "Sm-Fe-N-based magnetic material") has been studied.

[0003] The Sm-Fe-N-based magnetic material has a main phase with at least one crystal structure of Th2Zn 17 type and Th2Ni 17 type. Regarding this main phase, it is considered that nitrogen is introduced into the crystal phase of the Sm-Fe system in an invasive manner.

[0004] Japanese Patent Application Laid-Open No. 2017-117937 discloses a method for manufacturing an Sm-Fe-N-based magnetic material, in which oxides containing Sm, Fe, La, and W are reduced and the reduced product is nitrided to obtain an Sm-Fe-N-based magnetic material. Summary of the Invention

[0005] The magnetic properties of the Sm-Fe-N-based magnetic material, particularly the saturation magnetization, are achieved by selecting Sm as the rare earth element. With the spread of the Sm-Fe-N-based magnetic material, it is expected that the price of Sm, which is the main element of the Sm-Fe-N-based magnetic material, will soar. Therefore, the present inventors have found the following problem: There is a need for an Sm-Fe-N-based magnetic material and a method for manufacturing the same that can increase the saturation magnetization even when the amount of Sm used is reduced, or suppress the decrease in saturation magnetization within a range that is practically acceptable.

[0006] The present disclosure has been completed to solve the above problems. That is, an object of the present disclosure is to provide an Sm-Fe-N-based magnetic material and a method for manufacturing the same that can increase the saturation magnetization even when the amount of Sm used is reduced, or suppress the decrease in saturation magnetization within a range that is practically acceptable. It should be noted that in this specification, unless otherwise specified, "saturation magnetization" refers to the saturation magnetization at room temperature.

[0007] In order to achieve the above object, the inventor of the present invention repeatedly and deeply studied and completed the Sm-Fe-N based magnetic material and its manufacturing method disclosed herein. The Sm-Fe-N based magnetic material and its manufacturing method disclosed herein include the following solutions.

[0008] 〈1〉 The Sm-Fe-N based magnetic material is a Sm-Fe-N based magnetic material having a main phase with at least one crystal structure of the Th2Zn 17 type and the Th2Ni 17 type. Among them, the main phase has a composition represented by the molar ratio formula (Sm (1-x-y-z) La x Ce y R 1 z )2(Fe (1-p-q-s) Co p Ni q M s ) 17 N h . Among them, R 1 is one or more rare earth elements other than Sm, La, and Ce, and Zr. M is one or more elements other than Fe, Co, Ni, and rare earth elements, and inevitable impurity elements, and satisfies 0.04 ≦ x + y ≦ 0.50, 0 ≦ z ≦ 0.10, 0 ≦ p + q ≦ 0.10, 0 ≦ s ≦ 0.10, and 2.9 ≦ h ≦ 3.1. And the crystal volume of the main phase is 0.833 - 0.840 nm 3 .

[0009] 〈2〉 The Sm-Fe-N based magnetic material according to item 〈1〉, wherein the volume fraction of the main phase is 95 - 100%.

[0010] 〈3〉 The Sm-Fe-N based magnetic material according to item 〈1〉 or 〈2〉, wherein the density of the main phase is 7.30 - 7.70 g / cm 3 .

[0011] 〈4〉 The Sm-Fe-N based magnetic material according to item 〈1〉 or 〈2〉, wherein the density of the main phase is 7.40 - 7.60 g / cm 3 .

[0012] 〈5〉 The manufacturing method of the Sm-Fe-N based magnetic material is the manufacturing method of the Sm-Fe-N based magnetic material described in 〈1〉, including: preparing a magnetic material precursor, the magnetic material precursor having a composition represented by the molar ratio formula (Sm (1-x-y-z) La x Ce y R 1 z )2(Fe(1-p-q-s) Co p Ni q M s ) 17 The crystalline phase of the represented composition, where R 1 is one or more rare earth elements other than Sm, La, and Ce and Zr, M is one or more elements other than Fe, Co, Ni, and rare earth elements and inevitable impurity elements, and 0.04 ≦ x + y ≦ 0.50, 0 ≦ z ≦ 0.10, 0 ≦ p + q ≦ 0.10, and 0 ≦ s ≦ 0.10 are satisfied; and nitriding the magnetic material precursor.

[0013] <6> The method according to item <5>, wherein the volume fraction of the crystalline phase is 95 to 100%.

[0014] <7> The method according to item <5> or <6>, wherein after pulverizing the magnetic material precursor to obtain a magnetic material precursor powder, the magnetic material precursor powder is nitrided.

[0015] <8> The method according to any one of items <5> to <7>, wherein a raw material containing elements constituting the magnetic material precursor is melted and solidified to obtain the magnetic material precursor.

[0016] According to the present disclosure, it is possible to provide an Sm-Fe-N-based magnetic material which, even when a part of Sm is replaced with La and / or Ce in order to reduce the use amount of Sm, increases the saturation magnetization or suppresses the decrease in saturation magnetization within a range that is practically acceptable by keeping the lattice volume of the main phase within a specified range.

[0017] Furthermore, according to the present disclosure, it is possible to provide a method for manufacturing an Sm-Fe-N-based magnetic material which, by nitriding a magnetic material precursor in which a part of Sm is replaced with La and / or Ce and keeping the lattice volume of the main phase within a specified range, increases the saturation magnetization or can suppress the decrease in saturation magnetization within a range that is practically acceptable even when the use amount of Sm is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, where like reference numerals denote like elements, and wherein:

[0019] Figure 1 is a coordinate diagram showing the relationship between the lattice volume and the saturation magnetization Ms (300K).

[0020] Figure 2 is a coordinate diagram showing the relationship between the use amount of Sm (molar ratio of Sm) and the saturation magnetization Ms (300K).

[0021] Figure 3 A coordinate graph showing the relationship between lattice volume and density. Detailed implementation mode

[0022] The following details the implementation modes of the Sm-Fe-N based magnetic material and its manufacturing method of the present disclosure. It should be noted that the implementation modes shown below do not limit the Sm-Fe-N based magnetic material and its manufacturing method of the present disclosure.

[0023] Without being bound by theory, the reasons for the Sm-Fe-N based magnetic material and its manufacturing method that can provide an increase in saturation magnetization even when the usage amount of Sm is reduced, or suppress the decrease in saturation magnetization within a range that is practically acceptable, are described below.

[0024] As described above, the Sm-Fe-N based magnetic material of the present disclosure has a main phase having at least one crystal structure of the Th2Zn 17 type and the Th2Ni 17 type. The main phase of the Sm-Fe-N based magnetic material of the present disclosure exhibits magnetism through nitridation. When the main phase having at least one crystal structure of the Th2Zn 17 type and the Th2Ni 17 type is composed of Sm, Fe, and N, the composition of the most representative main phase is represented by Sm2Fe 17 N3. Hereinafter, the phase having such a composition is sometimes referred to as "Sm2Fe 17 N3 phase".

[0025] The Sm2Fe 17 N3 phase is obtained by nitriding the Sm2Fe 17 phase. The Sm2Fe 17 N3 phase has a crystal structure in which nitrogen (N) is introduced in an intrusion type into the Sm2Fe 17 phase. The lattice volume of the Sm2Fe 17 N3 phase is about 0.838 nm 3 .

[0026] If a part of Sm in the Sm2Fe 17 N3 phase is replaced with La and / or Ce, which are cheaper than Sm, in order to reduce the usage amount of Sm, the lattice volume of the main phase changes. Moreover, due to the change in the lattice volume of the main phase, the magnetic properties, especially the saturation magnetization, change.

[0027] Compared with the ionic radius of Sm, the ionic radius of La is very large. Therefore, if a part of Sm is replaced by La, basically, the lattice volume of the main phase increases. However, due to fluctuations in the intrusion of nitrogen (N) that intrudes into the main phase in an intrusion type during nitridation, etc., when the replacement amount of La is small, sometimes the lattice volume of the main phase decreases. Compared with the ionic radius of Sm, the ionic radius of Ce is slightly larger. Therefore, if a part of Sm is replaced by Ce, basically, the lattice volume of the main phase increases. However, Ce ions can be trivalent and tetravalent, and there are fluctuations in the intrusion of nitrogen (N) that intrudes into the main phase in an intrusion type during nitridation. Therefore, when a part of Sm is replaced by Ce, the lattice volume of the main phase sometimes increases and sometimes decreases.

[0028] If a part of Sm is replaced by inexpensive La and / or Ce, basically, the lattice volume of the main phase increases. At this time, if a part of Fe is optionally replaced by Co and / or Ni with an ionic radius smaller than that of Fe, the increase in the lattice volume can be suppressed.

[0029] In this way, by replacing a part of Sm with La and / or Ce, and optionally replacing a part of Fe with Co and / or Ni, the lattice volume of the main phase in the Sm-Fe-N-based magnetic material can be changed. Moreover, the present inventors have found that by making the lattice volume of the main phase in the Sm-Fe-N-based magnetic material fall within a specified range, the saturation magnetization of the Sm-Fe-N-based magnetic material can be increased, or the decrease in saturation magnetization can be suppressed within a range that is practically acceptable.

[0030] Hereinafter, the technical features of the Sm-Fe-N-based magnetic material and its manufacturing method of the present disclosure, which are completed based on the understandings described so far, etc., will be described.

[0031] 《Sm-Fe-N-based Magnetic Material》

[0032] The Sm-Fe-N-based magnetic material of the present disclosure includes a main phase having at least one of the crystal structures of the Th2Zn 17 type and Th2Ni 17 type. The Sm-Fe-N-based magnetic material of the present disclosure exhibits magnetism through the main phase. Hereinafter, the main phase will be described.

[0033] 〈Crystal Structure of the Main Phase〉

[0034] The main phase has the Th2Zn 17 type and Th2Ni 17At least any one of the crystal structures in the type. As the crystal structure of the main phase, in addition to the above structures, it may include a crystal structure of the TbCu7 type, etc. It should be noted that Th is thorium, Zn is zinc, Ni is nickel, Tb is terbium, and Cu is copper. The crystal structure of the main phase can be identified by, for example, performing X-ray diffraction analysis on the Sm-Fe-N-based magnetic material.

[0035] The phase having the above crystal structure can be realized by various combinations (compositions) of elements. The main phase of the Sm-Fe-N-based magnetic material of the present disclosure is realized by the following combination (composition) of elements. The composition of the main phase of the Sm-Fe-N-based magnetic material of the present disclosure will be described below.

[0036] 〈Composition of the main phase〉

[0037] The main phase has a composition represented by the molar ratio formula (Sm (1-x-y-z) La x Ce y R 1 z )2(Fe (1-p-q-s) Co p Ni q M s ) 17 N h In the above composition formula, Sm is samarium, La is lanthanum, Ce is cerium, Fe is iron, Co is cobalt, and Ni is nickel. R 1 is one or more rare earth elements other than Sm, La, and Ce, and Zr. M is one or more elements other than Fe, Co, Ni, and rare earth elements, and inevitable impurity elements. Further, Zr is zirconium. In addition, in the above formula, for the convenience of explanation, sometimes Sm (1-x-y) La x Ce y R 1 z is called the rare earth site, and Fe (1-p-q-s) Co p Ni q M s is called the iron group site.

[0038] As can be understood from the above formula, the main phase contains 2 moles of one or more elements in the rare earth site, 17 moles of one or more elements in the iron group site, and h moles of nitrogen (N). That is, a phase having the above crystal structure is formed by one or more elements in the rare earth site and one or more elements in the iron group site. In this phase, h moles of nitrogen (N) are introduced in an intrusion type. As long as the introduction amount of nitrogen (N) is h moles (where h is 2.9 to 3.1), the above crystal structure can be maintained. The details of nitrogen (N) in the main phase will be described later.

[0039] The rare earth site consists of Sm, La, Ce, and R 1 and Sm, La, Ce, and R 1 are each expressed in terms of molar ratio and exist in the ratio of (1 - x - y - z):x:y:z. (1 - x - y - z)+x+y+z = 1, which means that a part of Sm is replaced by one or more elements selected from La, Ce, and R 1 among them.

[0040] The iron group site consists of Fe, Co, Ni, and M. Fe, Co, Ni, and M are each expressed in terms of molar ratio and exist in the ratio of (1 - p - q - s):p:q:s. (1 - p - q - s)+p+q+s = 1, so it means that a part of Fe is replaced by one or more elements selected from Co, Ni, and M.

[0041] The following explains each element constituting the above formula and its content ratio (molar ratio).

[0042] 〈Sm〉

[0043] Sm is a main element that constitutes the above crystal structure together with Fe and N. A part of Sm is replaced by one or more elements selected from La, Ce, and R 1 among them. The following explains La, Ce, and R 1 in detail.

[0044] 〈La〉

[0045] La belongs to the so-called light rare earth elements. Compared with Sm, its reserves (resource volume) are larger and the price is cheaper. The ionic radius of La is much larger than that of Sm. Therefore, if a part of Sm is replaced by La, basically, the lattice volume of the main phase increases. However, there are fluctuations in the intrusion of nitrogen (N) that intrudes into the main phase in an intrusion type during nitriding. Therefore, when the replacement amount of La is small, the lattice volume of the main phase sometimes decreases.

[0046] As described above, the ionic radius of La is much larger than that of Sm. Therefore, if a part of Sm is replaced by La, it has a great influence on the change of the lattice volume of the main phase. If the lattice volume of the main phase exceeds the specified range, the above crystal structure cannot be maintained, or even if the above crystal structure can be maintained, the magnetic properties, especially the saturation magnetization, deteriorate. To prevent the above situation, when replacing a part of Sm with La, it is necessary to ensure that the replacement rate of La is not too high. However, in this case, it is difficult to increase the reduction amount of Sm. Therefore, it is effective to use Ce, which has a smaller influence on the change of the lattice volume of the main phase, compared with La. Next, Ce will be explained.

[0047] 〈Ce〉

[0048] Ce belongs to the so-called light rare earth elements. Compared with Sm, the burial amount (resource amount) is larger and the price is cheaper. The ionic radius of Ce is slightly larger than that of Sm. Therefore, if a part of Sm is replaced by Ce, basically, the lattice volume of the main phase increases. However, since Ce ions can be trivalent and tetravalent, there are fluctuations in the intrusion of nitrogen (N) intruded into the main phase in an intrusion type during nitridation. When a part of Sm is replaced by Ce, the lattice volume of the main phase sometimes increases and sometimes decreases.

[0049] As described above, the ionic radius of Ce is slightly larger than that of Sm. Therefore, even if a part of Sm is replaced by Ce, the influence on the change of the lattice volume of the main phase is small. In order to maintain the above crystal structure and obtain the desired magnetic properties, especially saturation magnetization, it is necessary to make the lattice volume of the main phase within a specified range. Since Ce has little influence on the change of the lattice volume of the main phase, when a part of Sm is replaced by Ce, the replacement rate caused by Ce is relatively high. As a result, it is possible to relatively easily increase the reduction amount of Sm. In addition, as described above, La has a large influence on the change of the lattice volume of the main phase and easily causes the lattice volume of the main phase to decrease excessively. Therefore, when a part of Sm is replaced by La, it is difficult to increase the replacement rate caused by La. Thus, by replacing a part of Sm with both La and Ce, the reduction amount of Sm can be increased.

[0050] 〈R 1 〉

[0051] R 1 is one or more rare earth elements other than Sm, La, and Ce, and Zr. R 1 is one or more elements that are allowed to be contained within a range that does not impair the magnetic properties of the Sm-Fe-N based magnetic material of the present disclosure. R 1 Typically, it is one or more rare earth elements other than Sm, La, and Ce that are difficult to completely separate these individually during the refining of raw materials containing Sm, La, and Ce respectively and remain in small amounts in the raw materials, etc. In addition to such rare earth elements, R 1 may contain Zr. Zr is not a rare earth element, but sometimes a part of Sm is replaced by Zr. Even if a part of Sm is replaced by Zr, as long as the replacement amount is small, the magnetic properties of the Sm-Fe-N based magnetic material will not be significantly impaired.

[0052] In this specification, rare earth elements include 17 elements: Sc (scandium), Y (yttrium), La (lanthanum), Ce (cerium), Pr (praseodymium), Nd (neodymium), Pm (promethium), Sm (samarium), Eu (europium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Yb (ytterbium), and Lu (lutetium).

[0053] 〈Fe〉

[0054] Fe is a main element that forms the above crystal structure together with Sm and N. A part of Fe can be replaced by one or more elements selected from Co, Ni, and M. Co, Ni, and M will be described below.

[0055] 〈Co〉

[0056] Co belongs to the so-called iron group elements, so a part of Fe can be replaced by Co. The ionic radius of Co is smaller than that of Fe. If a part of Sm is replaced by La and / or Ce, basically, the lattice volume of the main phase increases. Therefore, by replacing a part of Fe with Co, an excessive increase in the lattice volume of the main phase can be suppressed.

[0057] If a part of Fe is replaced by Co, the Curie temperature of the main phase rises, and a decrease in saturation magnetization at high temperatures (403 - 473K) can be suppressed, which is advantageous.

[0058] 〈Ni〉

[0059] Ni belongs to the so-called iron group elements, so a part of Fe can be replaced by Ni. The ionic radius of Ni is smaller than that of Fe. If a part of Sm is replaced by La and / or Ce, basically the lattice volume of the main phase increases. Therefore, by replacing a part of Fe with Ni, an excessive increase in the lattice volume of the main phase can be suppressed.

[0060] If a part of Fe is replaced by Ni, a decrease in magnetic properties is a concern. However, the ionic radius of Ni is smaller than that of Co. Therefore, compared with the case of replacing a part of Fe with Co, when a part of Fe is replaced by Ni, even if the replacement rate of Ni is not so high, the lattice volume of the main phase significantly decreases. Thus, for example, when a part of Sm is replaced by a large amount of La and / or Ce and the lattice volume of the main phase increases excessively, by using a relatively small amount of Ni, the lattice volume of the main phase can be made within a specified range. As a result, compared with the deterioration of magnetic properties caused by replacing a part of Fe with Ni, the contribution to the improvement of magnetic properties, especially saturation magnetization, for making the lattice volume of the main phase within the specified range can be greater, and the reduction amount of Sm brought about by the replacement of a large amount of La and / or Ce can be increased.

[0061] 〈M〉

[0062] M is one or more elements other than Fe, Co, Ni, and rare earth elements, and inevitable impurity elements. M is one or more elements and inevitable impurity elements that are allowed to be contained within a range that does not impair the magnetic properties of the Sm-Fe-N-based magnetic material of the present disclosure. The so-called inevitable impurity elements refer to impurity elements that are inevitably contained when manufacturing the Sm-Fe-N-based magnetic material of the present disclosure, or impurity elements that cause a significant increase in manufacturing cost in order to avoid them. As such inevitable impurity elements, for example, impurity elements in raw materials, or elements such as Cu (copper), Zn (zinc), Ga (gallium), Al (aluminum), and B (boron) that diffuse and / or penetrate into the surface of the main phase, etc. during the formation of a bonded molded body, etc., can be cited. In addition, elements contained in lubricants, etc. used during molding, and elements that diffuse and / or penetrate into the surface of the main phase, etc. can be cited. Furthermore, the bonded molded body will be described later.

[0063] As M other than inevitable impurity elements, for example, one or more elements selected from Ti (titanium), Cr (chromium), Mn (manganese), V (vanadium), Mo (molybdenum), W (tungsten), and C (carbon), etc. can be cited. These elements, for example, form nucleating substances during the formation of the main phase, and contribute to promoting the refinement of the main phase and / or suppressing the grain growth of the main phase.

[0064] In addition, as M, Zr can be included. As described above, Zr is not a rare earth element, but sometimes a part of Sm is replaced with Zr, and on the other hand, sometimes a part of Fe is replaced with Zr. In either case, as long as the replacement amount is small, the magnetic properties of the Sm-Fe-N-based magnetic material will not be significantly impaired.

[0065] 〈N〉

[0066] N is introduced into the main phase having the above crystal structure in an intrusion type. Regarding N, by introducing N to the extent that the phase having the above crystal structure is not destroyed, a magnetic moment appears in the main phase.

[0067] When the main phase of the Sm-Fe-N-based magnetic material of the present disclosure is composed of the elements described so far and the lattice volume of the main phase is within a specified range, the Sm-Fe-N-based magnetic material of the present disclosure has a desired saturation magnetization even when the amount of Sm used is reduced. The lattice volume of the main phase will be described below.

[0068] 〈Lattice volume〉

[0069] The lattice volume of the main phase of the Sm-Fe-N-based magnetic material of the present disclosure is 0.833 to 0.840 nm 3range. If the lattice volume of the main phase is within the above range, the desired saturation magnetization can be obtained, that is, compared with the case where the main phase is the Sm2Fe 17 N3 phase, the saturation magnetization can be increased, or the decrease in saturation magnetization can be suppressed within a range where there is no practical problem.

[0070] Without being bound by theory, the reason for obtaining the desired saturation magnetization when the lattice volume of the main phase is within the above range is as follows.

[0071] As described above, the saturation magnetization of the Sm-Fe-N based magnetic material comes from: by introducing N into the main phase in an intrusive type, a magnetic moment appears in the main phase. Thus, the saturation magnetization is greatly affected by the Fe-N distance (hereinafter sometimes simply referred to as "Fe-N distance") in the lattice of the main phase. Fe and N are three-dimensionally arranged in the lattice of the main phase, so the lattice volume of the main phase is advantageous for grasping the Fe-N distance.

[0072] In the Sm-Fe-N based magnetic material of the present disclosure, a part of Sm is replaced with La and / or Ce, and optionally a part of Fe is replaced with Co and / or Ni. Thus, the lattice volume of the Sm2Fe 17 N3 phase changes. At this time, it is considered appropriate to make the Fe-N distance in the lattice of the main phase close to the Fe-N distance in the lattice of the Sm2Fe 17 N3 phase. Since the lattice volume of the Sm2Fe 17 N3 phase is about 0.838 nm 3 , it is considered appropriate to make the lattice volume of the main phase of the Sm-Fe-N based magnetic material of the present disclosure close to 0.838 nm 3 . From this viewpoint, the lattice volume of the main phase of the Sm-Fe-N based magnetic material of the present disclosure can be 0.833 nm 3 or more, 0.834 nm 3 or more, 0.835 nm 3 or more, 0.836 nm 3 or more, or 0.837 nm 3 or more, and can be 0.840 nm 3 or less, 0.839 nm 3 or less, or 0.838 nm 3 or less.

[0073] The lattice volume of the main phase can be obtained as follows. Perform X-ray diffraction analysis on the Sm-Fe-N-based magnetic material, and from its X-ray diffraction pattern, based on the relationship between the plane indices and the lattice plane spacing (d value), obtain the a-axis length and the c-axis length. When obtaining the a-axis length and the c-axis length, since the main phase of the Sm-Fe-N-based magnetic material of the present disclosure has the above crystal structure, the main phase can be assumed to be a rhombohedral crystal. Therefore, as the plane indices, the (202) plane, (113) plane, (104) plane, (211) plane, (122) plane, and (300) plane can be used. Then, calculate the lattice volume according to the following formula.

[0074] (Lattice volume) = {(a-axis length) / 2} 2 ×6×3 0.5 ×{(c-axis length) / 3}

[0075] Regarding the Sm-Fe-N-based magnetic material of the present disclosure, in such a manner that the lattice volume of the main phase falls within the above range, a part of Sm is replaced with La and / or Ce, and optionally a part of Fe is replaced with Co and / or Ni. In this regard, the following will be described using the formula (Sm (1-x-y-z) La x Ce y R 1 z )2(Fe (1-p-q-s) Co p Ni q M s ) 17 N h to represent the composition of the main phase.

[0076] 〈x + y〉

[0077] In the above formula representing the composition of the main phase, the value of x represents the proportion (molar ratio) of replacing a part of Sm with La, and the value of y represents the proportion (molar ratio) of replacing a part of Sm with Ce.

[0078] If the value of x + y is 0.04 or more, an improvement in economy due to substitution of a part of Sm with inexpensive La and / or Ce can be substantially confirmed. Further, if the value of x + y is 0.04 or more, a change in the lattice volume of the main phase due to substitution of a part of Sm with La and / or Ce can be significantly confirmed. From these viewpoints, the value of x + y can be 0.06 or more, 0.08 or more, 0.10 or more. On the other hand, if the value of x + y is 0.50 or less, including substitution of a part of Fe with Co and / or Ni, the lattice volume of the main phase does not increase excessively. From this viewpoint, the value of x + y can be 0.46 or less, 0.44 or less, 0.40 or less, 0.36 or less, 0.34 or less, 0.30 or less, or 0.29 or less.

[0079] Further, while the value of x + y satisfies the above range, the value of x can be 0 or more, 0.02 or more, 0.04 or more, 0.06 or more, 0.08 or more, 0.09 or more, or 0.10 or more, and can be 0.50 or less, 0.45 or less, 0.40 or less, 0.35 or less, 0.30 or less, 0.28 or less, 0.26 or less, 0.24 or less, 0.22 or less, 0.20 or less, 0.18 or less, 0.16 or less, 0.14 or less, 0.12 or less, or 0.11 or less. Similarly, while the value of x + y satisfies the above range, the value of y can be 0 or more, 0.02 or more, 0.04 or more, 0.06 or more, 0.08 or more, 0.09 or more, or 0.10 or more, and can be 0.50 or less, 0.45 or less, 0.40 or less, 0.35 or less, 0.30 or less, 0.28 or less, 0.26 or less, 0.24 or less, 0.22 or less, 0.20 or less, 0.19 or less, 0.18 or less, 0.16 or less, 0.14 or less, 0.12 or less, or 0.10 or less.

[0080] 〈z〉

[0081] In the above formula representing the composition of the main phase, z represents the substitution ratio (molar ratio) of substituting a part of Sm with R. 1 As described above, R 1 is one or more rare earth elements and Zr that can be contained within a range not impairing the magnetic properties of the Sm-Fe-N-based magnetic material of the present disclosure. Accordingly, z can be 0.10 or less, 0.08 or less, 0.06 or less, 0.04 or less, or 0.02 or less. On the other hand, the Sm-Fe-N-based magnetic material of the present disclosure may contain no R 1 at all, that is, z can be 0, but it is difficult to make the raw material completely free of R 1 when manufacturing the Sm-Fe-N-based magnetic material of the present disclosure. From this viewpoint, z can be 0.01 or more.

[0082] 〈p + q〉

[0083] In the above formula representing the composition of the main phase, the value of p represents the ratio (molar ratio) of replacing a part of Fe with Co, and the value of q represents the ratio (molar ratio) of replacing a part of Fe with Ni.

[0084] As described above, if a part of Sm is replaced with La and / or Ce, basically, the lattice volume of the main phase increases. When a part of Sm is replaced with La and / or Ce and the lattice volume of the main phase increases, optionally, a part of Fe can be replaced with Co and / or Ni to suppress the increase in the lattice volume of the main phase.

[0085] When a part of Sm is replaced with a small amount of La and / or Ce, even if a part of Fe is not replaced with Co and / or Ni, that is, the value of p + q is 0, the lattice volume of the main phase can be within the above range.

[0086] However, even when a part of Sm is replaced with a small amount of La and / or Ce, a part of Fe can be replaced with Co and / or Ni to reduce the lattice volume of the main phase within the above range. In addition, when a part of Sm is replaced with a large amount of La and / or Ce and the crystal volume of the main phase increases excessively, a part of Fe can be replaced with Co and / or Ni to reduce the lattice volume of the main phase so that the lattice volume of the main phase becomes within the above range. In either case, as long as the value of p + q is 0.01 or more, a reduction in the crystal volume of the main phase can be substantially confirmed. From this point of view, the value of p + q can be 0.02 or more, 0.03 or more, 0.04 or more, or 0.05 or more. On the other hand, Co and Ni are more expensive than Fe. If the value of p + q is 0.10 or less, the economic improvement resulting from replacing a part of Sm with inexpensive La and / or Ce will not be offset. From this point of view, the value of p + q can be 0.09 or less, 0.08 or less, 0.07 or less, or 0.06 or less.

[0087] In addition, while the value of p + q satisfies the above range, the value of p can be 0 or more, 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, or 0.05 or more, and can be 0.10 or less, 0.09 or less, 0.08 or less, 0.07 or less, or 0.06 or less. Similarly, while the value of p + q satisfies the above range, the value of q can be 0 or more, 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, or 0.05 or more, and can be 0.10 or less, 0.09 or less, 0.08 or less, 0.07 or less, or 0.06 or less.

[0088] 〈s〉

[0089] In the above formula representing the composition of the main phase, s represents the ratio (molar ratio) of replacing a part of Fe with M. As described above, M is one or more elements and inevitable impurity elements that can be contained within a range that does not impair the magnetic properties of the Sm-Fe-N based magnetic material of the present disclosure. Thus, s can be 0.10 or less, 0.08 or less, 0.06 or less, 0.04 or less, or 0.02 or less. On the other hand, the Sm-Fe-N based magnetic material of the present disclosure may contain no M at all, that is, s can be 0. However, it is difficult to completely exclude inevitable impurity elements from M. From this perspective, s can be 0.01 or more.

[0090] 〈Relationships among x, y, z, p, q, and s〉

[0091] x, y, z, p, q, and s each satisfy the conditions for x, y, z, p, q, and s described so far, and are appropriately determined such that the lattice volume of the main phase falls within the above range. At this time, x, y, p, and q preferably satisfy the relationship of the following formula (1).

[0092] 833 ≦ 16.267x + 3.927y - 26.279p - 56.5327q + 836 ≦ 840 ··· Formula (1)

[0093] The reason why x, y, p, and q preferably satisfy Formula (1) will be described below.

[0094] In Formula (1), the relational expression represented by "16.267x + 3.927y - 26.279p - 56.5327q + 836" sandwiched by inequality signs is an expression for representing the lattice volume of the main phase using x, y, p, and q. This relational expression represents the result of calculating the lattice volume of the main phase when a part of Sm is replaced with La and / or Ce and a part of Fe is replaced with Co and / or Ni for the Sm2Fe 17 N3 phase by using machine learning. Hereinafter, the "16.267x + 3.927y - 26.279p - 56.5327q + 836" sandwiched by inequality signs in Formula (1) is sometimes referred to as the "relational expression representing the lattice volume of the main phase".

[0095] Then, Formula (1) means that the "relational expression representing the lattice volume of the main phase" is in the range of 833 to 840 cubic angstroms (0.833 to 0.840 nm 3 ). As described above, the lattice volume of the main phase of the Sm-Fe-N based magnetic material of the present disclosure is in the range of 0.833 to 0.840 nm 3 . Thus, it means that in the composition of the main phase of the Sm-Fe-N based magnetic material of the present disclosure, s, y, p, and q preferably satisfy Formula (1).

[0096] In the "relation expression representing the lattice volume of the main phase", there is no z related to R 1 and s related to M for the following reasons.

[0097] R 1 and M are one or more elements that can be contained within a range that does not impair the magnetic properties of the Sm-Fe-N-based magnetic material of the present disclosure. Since the magnetic properties are closely related to the lattice volume of the main phase, if the magnetic properties of the Sm-Fe-N-based magnetic material of the present disclosure are not impaired, the influence on the lattice volume of the main phase is small, and the necessity of considering z and s is low. Therefore, z and s are not considered in the "relation expression representing the lattice volume of the main phase".

[0098] As described above, the "relation expression representing the lattice volume of the main phase" is obtained through machine learning, represents the following technical meaning, and is considered to have high reliability.

[0099] First, when x = y = p = q = 0, it means that a part of Sm is not replaced by La and / or Ce, and a part of Fe is not replaced by Co and / or Ni. That is, it means that the lattice volume of the Sm2Fe 17 N3 phase is 836 cubic angstroms (0.836 nm 3 ). It is known that the lattice volume of the actual Sm2Fe 17 N3 phase is about 0.838 nm 3 , so it can be understood that the value of the lattice volume of the Sm2Fe 17 N3 phase in the "relation expression representing the lattice volume of the main phase" is very close to the actual value.

[0100] In addition, the ratio of the coefficients of x and y (16.267:3.927) is close to the ratio of the ionic radius of La to the ionic radius of Ce. In addition, the ratio of the absolute values of the coefficients of p and q (26.279:56.5327) is close to the ratio of the ionic radius of Co to the ionic radius of Ni.

[0101] Moreover, the above coefficients respectively represent the magnitude of the influence on the change in the lattice volume of the main phase when a part of Sm is replaced by La and / or Ce, or when a part of Fe is replaced by Co and / or Ni.

[0102] The coefficients of x and y are positive, indicating that if a part of Sm is replaced by La and / or Ce, basically, the lattice volume of the main phase increases. The coefficient of x is larger than the coefficient of y, indicating that since the ionic radius of La is larger than the ionic radius of Ce, the influence on the change in the lattice volume of the main phase is greater when a part of Sm is replaced by La than when a part of Sm is replaced by Ce.

[0103] The coefficients of p and q are negative, indicating that if part of Fe is replaced by Co and / or Ni, basically, the lattice volume of the main phase decreases. The absolute value of the coefficient of q is larger than the absolute value of the coefficient of p, indicating that since the ionic radius of Ni is larger than the ionic radius of Co, the influence on the change in the lattice volume of the main phase is greater when part of Fe is replaced by Ni than when part of Fe is replaced by Co.

[0104] In the expressions of the coefficients of the "relation expression representing the lattice volume of the main phase" so far, explain the reason for the part expressed as "basically".

[0105] In formula (1), regarding Sm2Fe 17 N3 phase, assuming that part of Sm is replaced by La and / or Ce, and part of Fe is replaced by Co and / or Ni, use machine learning to obtain the "relation expression representing the lattice volume of the main phase". Actually, if Sm2Fe 17 phase is nitrided, not only Sm2Fe 17 N3 phase, but also depending on the nitriding situation, Sm2Fe 17 N h (where h is 2.9 to 3.1). The details of h will be described later.

[0106] Depending on the nitriding situation, the coefficients of x, y, p, and q change. The smaller the absolute value of the coefficient, the more easily it is affected by the nitriding situation. For example, among the coefficients of x, y, p, and q, the absolute value of the coefficient of y is the smallest, so y is easily affected by the nitriding situation. Specifically, when part of Sm is replaced by Ce, basically, the lattice volume of the main phase increases. Therefore, basically, the coefficient of y is positive. However, depending on the nitriding situation, sometimes the coefficient of y decreases. In this case, since the absolute value of the coefficient of y is small, by the decrease of the coefficient of y, the coefficient of y can become negative. The coefficient of y becoming negative means that even when part of Sm is replaced by Ce, the lattice volume of the main phase decreases. The reason is that although the ionic radius of Ce is larger than that of Sm, the difference is very small, so the absolute value of the coefficient of y is small. In addition, it is also due to the fact that Ce ions have trivalent and tetravalent, and the coefficient of y is easily changed.

[0107] On the other hand, compared with the ionic radius of Sm, the ionic radius of La is very large, so it is not easily affected by the nitriding situation. Specifically, when a part of Sm is replaced by La, basically, the lattice volume of the main phase increases. Therefore, basically, the coefficient of x is positive. However, depending on the nitriding situation, sometimes the coefficient of x decreases. Even in such a case, since the absolute value of the coefficient of x is relatively large, it is difficult for the coefficient of x to become negative even if the coefficient of x decreases. As a case where the coefficient of x decreases according to the nitriding situation until the coefficient of x becomes negative, a case where the replacement amount generated by La is small can be cited.

[0108] When a part of Fe is replaced by Co and / or Ni, basically, the lattice volume of the main phase decreases. Therefore, basically, the coefficients of p and q are negative. However, depending on the nitriding situation, sometimes the coefficients of p and q increase. Even in such a case, since the absolute value of the coefficients of p and q is larger than the absolute value of the coefficients of x and y, it is difficult for the coefficients of p and q to become positive even if the coefficients of p and q increase.

[0109] As described so far, in formula (1), the "relationship representing the lattice volume of the main phase" is obtained by machine learning and also includes the above technical meaning. Moreover, it is experimentally confirmed that as long as the lattice volume of the main phase is in the range of 0.833 to 0.840 nm 3 the desired saturation magnetization is obtained. Thus, for x, y, p, and q, it is preferable to satisfy formula (1).

[0110] 〈h〉

[0111] Next, h representing the nitriding situation will be described. When the Sm2Fe 17 phase is nitrided, basically, the Sm2Fe 17 N h phase (where h = 3) is formed. Regarding nitriding, typically, it is carried out by exposing a Sm-Fe-N-based magnetic material precursor having a Sm2Fe 17 phase (hereinafter sometimes simply referred to as "precursor") to a nitrogen atmosphere at a high temperature, etc. Therefore, on the surface and inside of the precursor, the nitriding situation is different, so h can vary in the range of 2.9 to 3.1. The same applies to the case where a part of Sm is replaced by La and / or Ce and a part of Fe is replaced by Co and / or Ni in the precursor. That is, when the (Sm, La, Ce)2(Fe, Co, Ni) 17 phase is nitrided, the (Sm, La, Ce)2(Fe, Co, Ni) 17 N h phase (where h is 2.9 to 3.1) is formed.

[0112] 〈Volume fraction of the main phase〉

[0113] The Sm-Fe-N based magnetic material of the present disclosure has a main phase represented by the above compositional formula. The magnetic properties of the Sm-Fe-N based magnetic material of the present disclosure are manifested by the main phase. Therefore, with respect to the entire Sm-Fe-N based magnetic material of the present disclosure, it is preferable that the volume fraction of the main phase is high. Specifically, with respect to the volume fraction of the main phase, with respect to the entire Sm-Fe-N based magnetic material of the present disclosure, it may be 95% or more, 96% or more, or 97% or more. On the other hand, when manufacturing the Sm-Fe-N based magnetic material of the present disclosure, there may be a process or the like in which a phase other than the main phase represented by the above compositional formula becomes a stable temperature region. In addition, there may sometimes be a case where it is difficult to completely contain no inevitable impurity elements that do not constitute the main phase. From these, although it is ideal that the volume fraction of the main phase is 100%, as long as the above volume fraction of the main phase is ensured, even if the volume fraction of the main phase is 99% or less or 98% or less, there is no problem in practical use.

[0114] Phases other than the main phase typically exist at grain boundaries between the main phases, particularly at triple points. As phases other than the main phase, typically, SmFe3 phase and its nitrides can be cited. The SmFe3 phase and its nitrides include: phases in which a part of Sm is replaced with one or more elements selected from La, Ce, and R 1 and their nitrides, phases in which a part of Fe is replaced with one or more elements selected from Co, Ni, and M and their nitrides, and phases in which a part of Sm is replaced with one or more elements selected from La, Ce, and R 1 and a part of Fe is replaced with one or more elements selected from Co, Ni, and M and their nitrides.

[0115] With respect to the volume fraction of the main phase, the overall composition of the precursor before nitridation is measured using high-frequency inductively coupled plasma atomic emission spectroscopy (ICP-AES: Inductively Coupled Plasma Atomic Emission Spectroscopy). Assuming that the precursor before nitridation is phase-separated into (Sm, La, Ce, R 1 )2(Fe, Co, Ni, M) 17 phase and (Sm, La, Ce, R 1 )(Fe, Co, Ni, M)3 phase, based on the measured values, the volume fraction of the main phase is calculated. Specifically, after obtaining the mass concentration (mass fraction) of each element from the measurement result using ICP, first, the mass ratio of the Sm2Fe 17 phase and the SmFe3 phase is calculated, and the volume fraction is calculated from the density of each phase. It should be noted that (Sm, La, Ce, R 1 )2(Fe, Co, Ni, M) 17Phase representation: Sm2Fe 17 phase, Sm2Fe 17 phase, a part of Sm is replaced with one or more elements selected from Sm, La, Ce, and R 1 phase, Sm2Fe 17 phase, a part of Fe is replaced with one or more elements selected from Co, Ni, and M, and Sm2Fe 17 phase, a part of Sm is replaced with one or more elements selected from Sm, La, Ce, and R 1 phase and a part of Fe of Sm2Fe 17 phase is replaced with one or more elements selected from Co, Ni, and M. Additionally, (Sm, La, Ce, R 1 )(Fe, Co, Ni, M)3 phase represents: SmFe3 phase, a part of Sm of SmFe3 phase is replaced with one or more elements selected from Sm, La, Ce, and R 1 phase, a part of Fe of SmFe3 phase is replaced with one or more elements selected from Co, Ni, and M, and a part of Sm of SmFe3 phase is replaced with one or more elements selected from Sm, La, Ce, and R 1 phase and a part of Fe of SmFe3 phase is replaced with one or more elements selected from Co, Ni, and M.

[0116] Regarding the overall composition (the sum of the main phase and the phases other than the main phase) of the Sm-Fe-N based magnetic material of the present disclosure, when manufacturing the Sm-Fe-N based magnetic material of the present disclosure, from the viewpoint of suppressing the appearance of α-(Fe, Co, Ni, M) phase and its nitrided phase, the total molar number of Sm, La, Ce, and R 1 which are the main phase can be made to be equal to or more than. That is, the overall composition of the Sm-Fe-N based magnetic material of the present disclosure can be (Sm (1-x-y-z) La x Ce y R 1 z ) w (Fe (1-p-q-s) Co p Ni q M s ) 17 N h(wherein, w is 2.00 to 3.00). At this time, x, y, z, p, q, s, and h may be the same as x, y, z, p, q, s, and h in the formula representing the composition of the main phase described above. From the viewpoint of suppressing the appearance of the α-(Fe, Co, Ni, M) phase, w is preferably 2.02 or more, 2.04 or more, 2.06 or more, 2.08 or more, 2.10 or more, 2.20 or more, 2.30 or more, 2.40 or more, or 2.50 or more. On the other hand, from the viewpoint of reducing the volume fraction of the above (Sm, La, Ce, R 1 )(Fe, Co, Ni, M)3 phase, w is more preferably 2.90 or less, 2.80 or less, 2.70 or less, or 2.60 or less.

[0117] 〈Density of the main phase〉

[0118] In the Sm-Fe-N-based magnetic material of the present disclosure, there is a close relationship between the lattice volume of the main phase and the density of the main phase.

[0119] The density of the main phase may be 7.30 g / cm 3 or more, 7.35 g / cm 3 or more, 7.39 g / cm 3 or more, or 7.40 g / cm 3 or more, and may be 7.70 g / cm 3 or less, 7.65 g / cm 3 or less, or 7.60 g / cm 3 or less.

[0120] The density of the main phase is obtained by pulverizing the Sm-Fe-N-based magnetic material to obtain a powder and measuring the density of the powder by the pycnometer method. As described above, in the Sm-Fe-N-based magnetic material of the present disclosure, the volume fraction of the main phase is preferably 95%. In addition, the densities of the Sm2Fe 17 N3 phase and the SmFe3 phase are 7.65 g / cm 3 and 8.25 g / cm 3 respectively, and the difference is not so large. Thus, the density of the main phase can be approximated by the value obtained by the above measurement method.

[0121] 《Manufacturing method》

[0122] Next, a manufacturing method of the Sm-Fe-N-based magnetic material of the present disclosure (hereinafter sometimes referred to as "the manufacturing method of the present disclosure".) will be described.

[0123] The manufacturing method of the present disclosure includes a magnetic material precursor preparation step and a nitriding step. Each step will be described below.

[0124] 〈Magnetic Material Precursor Preparation Process〉

[0125] In the manufacturing method of the present disclosure, a magnetic material precursor having a crystal phase with a composition represented by the formula (Sm (1-x-y-z) La x Ce y R 1 z )2(Fe (1-p-q-s) Co p Ni q M s ) 17 is prepared.

[0126] In the formula representing the composition of the crystal phase, for Sm, La, Ce, R 1 , Fe, Co, Ni, and M, and x, y, z, p, q, and s, it is as described in "《Sm-Fe-N Series Magnetic Materials》".

[0127] The crystal phase of the magnetic material precursor has at least one of the Th2Zn 17 type and the Th2Ni 17 type crystal structures. When the magnetic material precursor is nitrided, the crystal phase in the magnetic material precursor is nitrided to form the main phase of the Sm-Fe-N series magnetic material of the present disclosure. The main phase of the Sm-Fe-N series magnetic material of the present disclosure has at least one of the Th2Zn 17 type and the Th2Ni 17 type crystal structures. Therefore, nitriding is carried out to the extent of maintaining at least one of the Th2Zn 17 type and the Th2Ni 17 type crystal structures.

[0128] As described above, the crystal phase in the magnetic material precursor is nitrided to form the main phase of the Sm-Fe-N series magnetic material of the present disclosure. Therefore, it can be considered that the volume fraction of the crystal phase in the magnetic material precursor is equivalent to the volume fraction of the main phase in the Sm-Fe-N series magnetic material of the present disclosure. Thus, with respect to the volume fraction of the crystal phase of the magnetic material precursor, it can be 95% or more, 96% or more, or 97% or more with respect to the entire magnetic material precursor. When manufacturing the magnetic material precursor, there may be processes such as a temperature region where a phase other than the crystal phase represented by the above composition formula becomes stable. In addition, there may also be cases where it is difficult to completely contain no inevitable impurity elements that do not constitute the crystal phase. It is ideal for the volume fraction of the crystal phase to be 100%, but as long as the above volume fraction of the crystal phase is ensured, even if the volume fraction of the main phase is 99% or less or 98% or less, there is no problem in practical use.

[0129] Phases other than the crystalline phase typically exist at grain boundaries between the crystalline phases, particularly at triple points. As phases other than the crystalline phase, typically, phases such as SmFe3 can be cited. The SmFe3 phase includes: a phase in which a part of Sm is replaced with one or more elements selected from La, Ce, and R 1 ; a phase in which a part of Fe is replaced with one or more elements selected from Co, Ni, and M; and a phase in which a part of Sm is replaced with one or more elements selected from La, Ce, and R 1 and a part of Fe is replaced with one or more elements selected from Co, Ni, and M.

[0130] Regarding the volume fraction of the crystalline phase, the overall composition of the precursor before nitridation is measured using high-frequency inductively coupled plasma optical emission spectrometry (ICP-AES: Inductively Coupled Plasma Atomic Emission Spectroscopy). Assuming that the precursor before nitridation is phase-separated into (Sm, La, Ce, R 1 )2(Fe, Co, Ni, M) 17 phase and (Sm, La, Ce, R 1 )(Fe, Co, Ni, M)3 phase, the main phase fraction is calculated based on the measured values. Specifically, after obtaining the mass concentration (mass fraction) of each element from the measurement results using ICP, first, the mass ratio of the Sm2Fe 17 phase and the SmFe3 phase is calculated, and the volume fraction is calculated from the density of each phase. It should be noted that the (Sm, La, Ce, R 1 )2(Fe, Co, Ni, M) 17 phase represents: the Sm2Fe 17 phase, a phase in which a part of Sm in the Sm2Fe 17 phase is replaced with one or more elements selected from Sm, La, Ce, and R 1 ; a phase in which a part of Fe in the Sm2Fe 17 phase is replaced with one or more elements selected from Co, Ni, and M; and a phase in which a part of Sm in the Sm2Fe 17 phase is replaced with one or more elements selected from Sm, La, Ce, and R 1 and a part of Fe in the Sm2Fe 17 phase is replaced with one or more elements selected from Co, Ni, and M. In addition, the (Sm, La, Ce, R 1 )(Fe, Co, Ni, M)3 phase represents: the SmFe3 phase, a phase in which a part of Sm in the SmFe3 phase is replaced with one or more elements selected from Sm, La, Ce, and R 1A phase in which one or more elements in it are replaced, a phase in which a part of Fe in the SmFe3 phase is replaced by one or more elements selected from Co, Ni, and M, and a part of Sm in the SmFe3 phase is replaced by one or more elements selected from Sm, La, Ce, and R 1 A phase in which one or more elements in it are replaced and a part of Fe in the SmFe3 phase is replaced by one or more elements selected from Co, Ni, and M.

[0131] Regarding the overall composition of the magnetic material precursor (the sum of the crystalline phase and the phase other than the crystalline phase), in the manufacture of the magnetic material precursor, from the viewpoint of suppressing the appearance of the α-(Fe, Co, Ni, M) phase, the total molar number of Sm, La, Ce, and R in the crystalline phase can be made equal to or more than a certain value. That is, the overall composition of the magnetic material precursor can be (Sm 1 La (1-x-y-z) La x Ce y R 1 z ) w (Fe (1-p-q-s) Co p Ni q M s ) 17 (where w is 2.00 - 3.00). At this time, x, y, z, p, q, and s can be the same as x, y, z, p, q, and s in the formula representing the composition of the crystalline phase above. From the viewpoint of suppressing the appearance of the α-(Fe, Co, Ni, M) phase, w is preferably 2.02 or more, 2.04 or more, 2.06 or more, 2.08 or more, 2.10 or more, 2.20 or more, 2.30 or more, 2.40 or more, or 2.50 or more. On the other hand, from the viewpoint of reducing the volume fraction of the (Sm, La, Ce, R 1 )(Fe, Co, Ni, M)3 phase, w is more preferably 2.90 or less, 2.80 or less, 2.70 or less, or 2.60 or less.

[0132] The magnetic material precursor can be obtained by known manufacturing methods. As a method for obtaining the magnetic material precursor, for example, melting and solidifying raw materials containing elements constituting the magnetic material precursor can be cited. As a method for melting the raw materials, for example, the raw materials are put into a container such as a crucible, and the raw materials are arc-melted or high-frequency melted in the container. After obtaining a metal melt, the metal melt is poured into a mold such as a hinged mold, or the metal melt is solidified in the crucible, etc. From the viewpoints of suppressing the coarsening of the crystal phase in the magnetic material precursor and improving the homogenization of the crystal phase, etc., it is preferable to increase the cooling rate of the metal melt. From this viewpoint, it is preferable to pour the metal melt into a mold such as a hinged mold. Further, from the viewpoints of suppressing the coarsening of the crystal phase in the magnetic material precursor and improving the homogenization of the crystal phase, etc., for example, the following method can be adopted. That is, an ingot obtained by high-frequency melting or arc-melting and solidifying raw materials in a container can be melted again by high-frequency melting, etc., and the molten metal is quenched by a strip casting method, a liquid quenching method, etc. to obtain a thin sheet, and this thin sheet is used as the magnetic material precursor.

[0133] Before the nitridation described later, in order to homogenize the crystal grains in the magnetic material precursor, the magnetic material precursor can be heat-treated (hereinafter, such heat treatment is sometimes referred to as "homogenization heat treatment"). The temperature of the homogenization heat treatment can be, for example, 1273 K or higher, 1323 K or higher, or 1373 K or higher, and can be 1523 K or lower, 1473 K or lower, or 1423 K or lower. The homogenization heat treatment time can be, for example, 6 hours or longer, 12 hours or longer, 18 hours or longer, or 24 hours or longer, and can be 48 hours or shorter, 42 hours or shorter, 36 hours or shorter, or 30 hours or shorter.

[0134] In order to suppress the oxidation of the magnetic material precursor, it is preferable to perform the homogenization heat treatment in an inert gas atmosphere. The inert gas atmosphere does not include a nitrogen atmosphere. This is because if the homogenization heat treatment is performed in a nitrogen atmosphere, the phase having a Th2Zn 17 type and / or Th2Ni 17 type crystal structure is liable to decompose.

[0135] 〈Nitriding process〉

[0136] The above-mentioned magnetic material precursor is nitrided. Thereby, the crystal phase in the magnetic material precursor is nitrided to form the main phase of the Sm-Fe-N-based magnetic material of the present disclosure.

[0137] There is no particular limitation on the nitriding method as long as the desired main phase can be obtained. Typically, for example, it can be cited as follows: heating the magnetic material precursor while exposing it to an atmosphere containing nitrogen, or exposing it to a gas atmosphere containing nitrogen (N), etc. For the atmosphere containing nitrogen, for example, it can be cited as a nitrogen atmosphere, a mixed gas atmosphere of nitrogen and an inert gas, and a mixed gas atmosphere of nitrogen and hydrogen, etc. For the gas atmosphere containing nitrogen (N), for example, it can be cited as an ammonia atmosphere, or a mixed gas atmosphere of ammonia and hydrogen, etc. The atmospheres exemplified so far can also be combined. From the viewpoint of nitriding efficiency, an ammonia atmosphere, a mixed gas atmosphere of ammonia and hydrogen, and a mixed gas atmosphere of nitrogen and hydrogen are preferred.

[0138] The magnetic material precursor can also be pulverized before nitriding. After obtaining the magnetic material precursor powder, the magnetic material precursor powder is nitrided. By nitriding after pulverizing the magnetic material precursor, the crystal phase existing inside the magnetic material precursor can be sufficiently nitrided. The pulverization of the magnetic material precursor is preferably carried out in an inert gas atmosphere. The inert gas atmosphere can include a nitrogen atmosphere. Thus, oxidation of the magnetic material precursor during pulverization can be suppressed. As the particle size of the magnetic material precursor powder, represented by D 50 it can be 5 μm or more, 10 μm or more, or 15 μm or more, and can also be 50 μm or less, 40 μm or less, 30 μm or less, 25 μm or less, or 20 μm or less.

[0139] The nitriding temperature can be, for example, 673 K or more, 698 K or more, 723 K or more, or 748 K or more, and can be 823 K or less, 798 K or less, or 773 K or less. In addition, the nitriding time can be, for example, 4 hours or more, 8 hours or more, 12 hours or more, or 16 hours or more, and can be 48 hours or less, 36 hours or less, 24 hours or less, 20 hours or less, or 18 hours or less.

[0140] "Modification"

[0141] The Sm-Fe-N-based magnetic material and its manufacturing method of the present disclosure are not limited to the embodiments described so far, and can be appropriately modified within the scope described in the patent claims. For example, the Sm-Fe-N-based magnetic material of the present disclosure can be a powder or a molded body of the powder. The molded body can be a bonded molded body or a sintered molded body. In the case of a molded body, from the viewpoint of easily avoiding the temperature at which nitrogen (N) in the main phase dissociates (decomposes) during the molding process, a bonded molded body is preferred. As the binder, for example, resins and low-melting-point metal binders, etc. can be cited. As the low-melting-point metal binder, for example, metallic zinc or zinc alloys and their combinations, etc. can be cited.

[0142] The Sm-Fe-N-based magnetic material and its manufacturing method of the present disclosure will be described in more detail below through examples and comparative examples. Furthermore, the Sm-Fe-N-based magnetic material and its manufacturing method of the present disclosure are not limited to the conditions used in the following examples.

[0143] 《Preparation of Specimens》

[0144] Specimens of the Sm-Fe-N-based magnetic material were prepared according to the following procedures.

[0145] Metallic Sm, metallic La, Ce-Fe alloy, metallic Fe, metallic Co, and metallic Ni were combined so that the main phase had the composition shown in Table 1, and they were melted by high-frequency heating at 1673 K (1400 °C) and then solidified to obtain a magnetic material precursor. During the combination, the total molar number of Sm, La, and Ce in the main phase was made to be more than the total molar number of Sm, La, and Ce in the main phase in such a manner that the volume fraction of the main phase was 95 to 100%. It should be noted that in this specification, for example, "metallic Sm" refers to Sm that has not been alloyed. Of course, unavoidable impurities may be contained in metallic Sm.

[0146] The magnetic material precursor was subjected to homogenization heat treatment in an argon atmosphere at 1373 K for 24 hours.

[0147] The magnetic material precursor after the homogenization heat treatment was placed in a glove box and pulverized using a cutter in a nitrogen atmosphere. The particle size of the pulverized magnetic material precursor powder was measured by D 50 and was 20 μm or less.

[0148] In a nitrogen atmosphere, the magnetic material precursor powder was heated to 748 K and nitrided for 16 hours. The amount of nitridation was grasped by the mass change of the magnetic material precursor powder before and after nitridation.

[0149] 《Evaluation》

[0150] For each specimen, the composition, volume fraction, density, and lattice volume of the main phase were determined using the above-described measurement methods. In addition, for each specimen, the magnetic properties were measured using a physical property measurement system PPMS (registered trademark)-VSM with a maximum applied magnetic field of 9 T. Regarding the measurement of the magnetic properties, the nitrided powder of each specimen was magnetically oriented and cured in epoxy resin, and the magnetic properties of the cured specimens were measured in the easy magnetization axis direction and the hard magnetization axis direction at 300 to 453 K. Based on the measured values in the easy magnetization axis direction, the saturation magnetization Ms was calculated using the saturation approach method. In addition, the anisotropy magnetic field Ha was obtained from the intersection point of the hysteresis curves in the easy magnetization axis direction and the hard magnetization axis direction.

[0151] The results are shown in Table 1. Figure 1A coordinate diagram showing the relationship between the lattice volume and the saturation magnetization Ms (300K). Figure 2 A coordinate diagram showing the relationship between the usage amount of Sm (molar ratio of Sm) and the saturation magnetization Ms (300K). Figure 3 A coordinate diagram showing the relationship between the lattice volume and the density.

[0152]

[0153]

[0154] From Table 1 and Figure 3 it can be understood that there is a close relationship between the lattice volume and the density. Moreover, from Table 1 and Figure 1 it can be understood that, compared with the sample of Comparative Example 1 having the Sm2Fe 17 N3 phase as the main phase, the samples of Examples 1 to 5 having the main phase with a lattice volume of 0.833 to 0.840 nm 3 although reduced the usage amount of Sm, the saturation magnetization increased, or the decrease in the saturation magnetization was suppressed within a range that is not a problem in practical use. Furthermore, in Table 1 and Figure 1 the lattice volumes of the samples of Comparative Examples 1, 6, and 9 are 0.833 to 0.840 nm 3 . In the sample of Comparative Example 1, a part of Sm was not replaced with La and / or Ce (0.04 ≦ x + y ≦ 0.50 was not satisfied, and the usage amount of Sm was not reduced), in the sample of Comparative Example 6, although a part of Fe was replaced with Co, the replacement amount of Co was too much, so the economy brought by replacing a part of Sm with La was offset (0 ≦ p + q ≦ 0.10 was not satisfied), and in the sample of Comparative Example 9, although a part of Sm was replaced with La, the replacement amount of La was too small (0.04 ≦ x + y ≦ 0.50 was not satisfied).

[0155] In addition, from Table 1 and Figure 2 it can be understood that in the samples of the comparative examples (other than those with a lattice volume of 0.833 to 0.840 nm 3 ), as the usage amount of Sm was reduced (the molar ratio of Sm decreased), there was a tendency for the saturation magnetization Ms (300K) to decrease, while in the samples of Examples 1 to 5 (with a lattice volume of 0.833 to 0.840 nm 3 ), although the usage amount of Sm was reduced, they had a saturation magnetization Ms (300K) above a specified value.

[0156] From these results, the effects of the Sm-Fe-N-based magnetic material and its manufacturing method of the present disclosure can be confirmed.

Claims

1. The Sm-Fe-N based magnetic material has a main phase with at least one of the crystal structures of the Th2Zn 17 type and the Th2Ni 17 type. Among them, The main phase has a formula composed of a molar ratio of (Sm （1-x-y-z） La x Ce y R 1 z )2(Fe （1-p-q-s） Co p Ni q M s ) 17 N h Represents the composition, where R 1 is one or more rare earth elements other than Sm, La and Ce, M is an inevitable impurity element, and satisfies 0.08≦x+y≦0.50, 0≦z≦0.02, 0≦p+q≦0.10, 0≦s≦0.02, and 2.9≦h≦3.1, and the lattice volume of the main phase is 0.833-0.840nm 3 , The volume fraction of the main phase is 95 to 100%.

2. The Sm-Fe-N based magnetic material according to claim 1, wherein, The density of the main phase is 7.30 to 7.70 g / cm 3 .

3. The Sm-Fe-N based magnetic material according to claim 1, wherein, The density of the main phase is 7.40 to 7.60 g / cm 3 .

4. A method for manufacturing an Sm-Fe-N-based magnetic material, which is the method for manufacturing an Sm-Fe-N-based magnetic material according to claim 1, comprising: Prepare a magnetic material precursor, the magnetic material precursor having a formula (Sm （1-x-y-z） La x Ce y R 1 z )2(Fe （1-p-q-s） Co p Ni q M s ) 17 represents the composition of the crystalline phase, where R 1 is one or more rare earth elements other than Sm, La and Ce, M is an inevitable impurity element, and satisfies 0.08≦x+y≦0.50, 0≦z≦0.02, 0≦p+q≦0.10, and 0≦s≦0.02; and nitriding the magnetic material precursor, wherein the volume fraction of the crystalline phase is 95 to 100%.

5. The method according to claim 4, wherein After crushing the magnetic material precursor to obtain a magnetic material precursor powder, nitriding the magnetic material precursor powder.

6. The method according to claim 4 or 5, wherein Melting and solidifying a raw material containing elements constituting the magnetic material precursor to obtain the magnetic material precursor.

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