Sm-Fe-N magnetic material and method for manufacturing the same

Abstract

To provide an Sm-Fe-N-based magnetic material that can improve saturation magnetization while minimizing the decrease in anisotropic magnetic field even when the use amount of Sm is reduced, and a method for manufacturing the same.SOLUTION: A magnetic material has a main phase having a predetermined crystal structure. The composition of the main phase is expressed as (Sm(1-x-y-z)LaxCeyR1z)2(Fe(1-p-q-s)CopNiqMs)17 Nh, where R1 represents a predetermined rare earth element or the like, M represents a predetermined element, and satisfies 0.25≤x+y≤0.73, 0.25≤x≤0.73, x / (x+y)≥0.80, 0≤z≤0.10, 0.10≤p+q≤0.53, p+q≥1.45(x+y)-0.5485, 0≤s≤0.10, and 2.9≤h≤3.3. A manufacturing method includes nitriding a precursor having a crystalline phase having a composition represented by (Sm(1-x-y-z)LaxCeyR1z)2(Fe(1-p-q-s)CopNiqMs)17.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to Sm-Fe-N magnetic materials and methods for producing the same. In particular, this disclosure relates to Th2Zn 17 Type and Th2Ni 17 This invention relates to an Sm-Fe-N magnetic material having a main phase having at least one of the crystal structures of the type, and a method for producing the same. [Background technology]

[0002] While Sm-Co and Nd-Fe-B magnetic materials have been put into practical use as high-performance magnetic materials, other magnetic materials have been investigated in recent years. For example, Th2Zn 17 Type and Th2Ni 17 Sm-Fe-N magnetic materials (hereinafter sometimes simply referred to as "Sm-Fe-N magnetic materials") having a main phase with at least one of the following crystal structures are being investigated.

[0003] Sm-Fe-N magnetic materials include Th2Zn 17 Type and Th2Ni 17 It comprises a main phase having at least one of the following crystal structures. This main phase is thought to be an Sm-Fe crystalline phase in which nitrogen has been intermittently introduced.

[0004] For example, Patent Document 1 discloses a method for producing an Sm-Fe-N magnetic material, which involves reducing an oxide containing Sm, Fe, La, and W, and then nitriding the reduced product to obtain an Sm-Fe-N magnetic material.

[0005] Furthermore, Patent Documents 2 and 3 disclose Sm-Fe-N magnetic materials containing light rare earth elements in addition to Sm, as well as methods for producing the same. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2017-117937 [Patent Document 2] Japanese Patent Publication No. 2022-53187 Public Relations [Patent Document 3] Japanese Patent Publication No. 2022-53207 Public Relations [Overview of the project] [Problems that the invention aims to solve]

[0007] The magnetic properties of Sm-Fe-N magnetic materials, particularly saturation magnetization, are achieved by selecting Sm as the rare earth element. As Sm-Fe-N magnetic materials become more widespread, the price of Sm, the main element in Sm-Fe-N magnetic materials, is expected to rise. For this reason, attempts have been made to replace some of the Sm with other rare earth elements, especially light rare earth elements that are less rare than Sm.

[0008] In the Sm-Fe-N magnetic material described in Patent Document 1, an attempt was made to substitute a portion of Sm with La, but the amount of La substitution was small, resulting in only a limited reduction in the amount of Sm used. In the Sm-Fe-N magnetic material described in Patent Document 2, the amount of Sm used was reduced by substituting a portion of Sm with La and / or Ce, but high saturation magnetization was not achieved, and a decrease in the anisotropic magnetic field remained a challenge. In the Sm-Fe-N magnetic material described in Patent Document 3, high saturation magnetization was achieved by substituting a portion of Sm with La and / or Ce, but the amount of La and / or Ce substitution was small, resulting in only a limited reduction in the amount of Sm used.

[0009] From this, the inventors have identified a problem in which there is a need for an Sm-Fe-N based magnetic material and a method for manufacturing the same that can improve saturation magnetization while suppressing the decrease in anisotropic magnetic field as much as possible, even when the amount of Sm used is reduced.

[0010] The present disclosure has been made to solve the above problems. That is, an object of the present disclosure is to provide a Sm—Fe—N-based magnetic material capable of improving saturation magnetization while suppressing a decrease in the anisotropic magnetic field as much as possible even when the amount of Sm used is reduced. In the present specification, unless otherwise specified, "saturation magnetization" means saturation magnetization at room temperature.

Means for Solving the Problems

[0011] The inventors of the present invention have conducted intensive studies to achieve the above object, and have completed the Sm—Fe—N-based magnetic material and its manufacturing method of the present disclosure. The Sm—Fe—N-based magnetic material and its manufacturing method of the present disclosure include the following aspects. 〈1〉 A Sm—Fe—N-based magnetic material including a main phase having at least one crystal structure of the Th2Zn 17 type and the Th2Ni 17 type, wherein the composition of the main phase is 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 ), 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 0.25 ≦ x + y ≦ 0.73, 0.25 ≦ x ≦ 0.73, x / (x + y) ≧ 0.80, 0 ≦ z ≦ 0.10, 0.10 ≦ p + q ≦ 0.53, p + q ≧ 1.45(x + y) - 0.5485, 0 ≦ s ≦ 0.10, and 2.9 ≦ h ≦ 3.3 are satisfied, Sm—Fe—N-based magnetic material. (2) The Sm-Fe-N magnetic material according to (1), wherein p and q satisfy 0.22 ≤ p + q ≤ 0.53. (3) The Sm-Fe-N magnetic material according to (1) or (2), wherein the lattice constant of the main phase is 1.4350 to 1.4460. (4) The Sm-Fe-N magnetic material according to (1) or (2), wherein the lattice volume of the main phase is 0.829 to 0.838 nm. (5) The Sm-Fe-N magnetic material according to (1) or (2), wherein the volume fraction of the main phase is 80 to 100%. <6> The density of the main phase is 7.40 to 7.76 g / cm³. 3 The Sm-Fe-N magnetic material described in (1) or (2). A method for producing an Sm-Fe-N magnetic material as described in <7> and <1>, Mole 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 It is represented as R 1 The present invention provides a magnetic material precursor having a crystalline phase that satisfies 0.25≦x+y≦0.73, 0.25≦x≦0.73, x / (x+y)≧0.80, 0≦z≦0.10, 0.10≦p+q≦0.53, p+q≧1.45(x+y)-0.5485, and 0≦s≦0.10, and Nitriding the magnetic material precursor, A method for producing Sm-Fe-N-based magnetic materials, including the material itself. (8) A method for producing an Sm-Fe-N magnetic material according to (7), wherein p and q satisfy 0.22 ≤ p + q ≤ 0.53. (9) A method for producing an Sm-Fe-N based magnetic material according to (7) or (8), comprising crushing the magnetic material precursor to obtain a magnetic material precursor powder, and then nitriding the magnetic material precursor powder. (10) A method for producing an Sm-Fe-N magnetic material according to (7) or (8), comprising dissolving and solidifying raw materials containing elements constituting the magnetic material precursor to obtain the magnetic material precursor. [Effects of the Invention]

[0012] According to this disclosure, even if Sm is replaced with a predetermined proportion of La to reduce the amount of Sm used, Fe is replaced with a predetermined proportion of Co, thereby providing an Sm-Fe-N magnetic material that can improve saturation magnetization while suppressing the decrease in anisotropic magnetic field as much as possible.

[0013] Furthermore, according to this disclosure, in order to reduce the amount of Sm used, even if Sm is substituted with a predetermined proportion of La, by nitriding a magnetic material precursor in which Fe is substituted with a predetermined proportion of Co, it is possible to provide a method for producing an Sm-Fe-N based magnetic material that can improve saturation magnetization while suppressing the decrease in anisotropic magnetic field as much as possible. [Brief explanation of the drawing]

[0014] [Figure 1] Figure 1 is a graph showing the relationship between the molar ratio of La x and the molar ratio of Co p and phase stability. [Figure 2] Figure 2 is a graph showing the relationship between the lattice constant and the saturation magnetization Ms. [Figure 3] Figure 3 is a graph showing the relationship between the sum of the molar ratios of La (x) and Ce (y) and the anisotropic magnetic field (Ha). [Figure 4] Figure 4 is a graph showing the relationship between the molar ratio x of La and the saturation magnetization Ms when the molar ratio p of Co is 0.3. [Modes for carrying out the invention]

[0015] The following describes in detail embodiments of the Sm-Fe-N magnetic material and its manufacturing method according to this disclosure. Note that the embodiments described below are not limiting to the Sm-Fe-N magnetic material and its manufacturing method according to this disclosure.

[0016] Although not bound by theory, the reason why we can provide an Sm-Fe-N magnetic material and a method for manufacturing the same that can improve saturation magnetization while suppressing the decrease in anisotropic magnetic field as much as possible, even when reducing the amount of Sm used, is explained below.

[0017] As described above, the Sm-Fe-N magnetic material of this disclosure is Th2Zn 17 Type and Th2Ni 17 The material comprises a main phase having at least one of the crystal structures of the type. The main phase of the Sm-Fe-N magnetic material of this disclosure exhibits magnetism upon nitridation. Th2Zn 17 Type and Th2Ni 17 When the main phase having at least one of the crystal structures of type is composed of Sm, Fe, and N, the most representative composition of the main phase is Sm2Fe 17 It is represented as N3. Hereafter, a phase having such a composition will be called "Sm2Fe 17 It is sometimes referred to as the "N3 phase."

[0018] Sm2Fe 17 The N3 phase is Sm2Fe 17 Obtained by nitriding the phase, Sm2Fe 17 The N3 phase is Sm2Fe 17 It has a crystalline structure in which nitrogen (N) is interstitially introduced into the phase. Sm2Fe 17 The lattice volume of the N3 phase is approximately 0.838 nm. 3 That is the case.

[0019] To reduce the use of Sm, Sm2Fe 17 When some of the Sm in the N3 phase is replaced with La, which is less expensive than Sm, the lattice volume of the main phase changes. This change in the lattice volume of the main phase then alters the magnetic properties, particularly the saturation magnetization.

[0020] Since the ionic radius of La is much larger than that of Sm, substituting some of Sm with La basically increases the lattice volume of the main phase. If the amount of La substitution is too large, the lattice volume becomes excessive, and Th2Zn 17 Type and Th2Ni 17It becomes difficult to maintain at least one of the crystal structures of the type. Therefore, by substituting some of the Fe with Co and / or Ni, which have smaller ionic radii than Fe, the increase in lattice volume can be suppressed, and as a result, Th2Zn 17 Type and Th2Ni 17 This makes it possible to maintain at least one of the crystal structures of the type.

[0021] Generally, when a portion of Sm is replaced with light rare earth elements such as Ce and La, the saturation magnetization and anisotropic magnetic field decrease by the amount of substitution. However, even if Sm is replaced with a predetermined proportion of La, if Fe is replaced with a predetermined proportion of Co, Th2Zn 17 Type and Th2Ni 17 Not only is it possible to maintain at least one of the crystal structures of the type, but an improvement in magnetic properties was also observed. In other words, the inventors found that even if Sm is substituted with a predetermined proportion of La, if Fe is substituted with a predetermined proportion of Co, it is possible to improve the saturation magnetization while suppressing the decrease in the anisotropic magnetic field as much as possible, more than would be predicted from the amount of La substitution.

[0022] The constituent elements of the Sm-Fe-N magnetic material and its manufacturing method described herein, which have been completed based on the knowledge and other information described above, are now explained.

[0023] 《Sm-Fe-N magnetic material》 The Sm-Fe-N magnetic material disclosed herein is Th2Zn 17 Type and Th2Ni 17 The material comprises a main phase having at least one of the following crystal structures. The Sm-Fe-N magnetic material of this disclosure exhibits magnetism due to the main phase. The main phase will be described below.

[0024] <Crystal structure of the main phase> The main phase is Th2Zn 17 Type and Th2Ni 17It has at least one of the following crystal structures. In addition to the structures described above, the crystal structure of the main phase may also include the TbCu7 type crystal structure, etc. Here, 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, X-ray diffraction analysis of Sm-Fe-N magnetic materials.

[0025] The phase having the crystalline structure described above can be achieved with various combinations (compositions) of elements, but the main phase of the Sm-Fe-N magnetic material of this disclosure is achieved with the following combination (composition). The composition of the main phase of the Sm-Fe-N magnetic material of this disclosure will be described below.

[0026] <Composition of the main phase> The main phase is given 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 It has the composition represented by the above compositional formula. In the above compositional formula, Sm is samarium, La is lanthanum, Ce is cerium, Fe is iron, Co is cobalt, and Ni is nickel. 1 Sm is one or more rare earth elements other than Sm, La, and Ce, and Zr, and M is one or more elements other than Fe, Co, Ni, and rare earth elements, and unavoidable impurity elements. Note that Zr is zirconium. Also, in the above formula, for the sake of explanation, Sm (1-x-y) La x Ce y R 1 z Fe (1-p-q-s) Co p Ni q M s This is sometimes referred to as a "railway enthusiast site."

[0027] As can be understood from the above equation, the main phase contains 2 moles of one or more elements from the rare earth sites, 17 moles of one or more elements from the iron group sites, and h moles of nitrogen (N). In other words, the phase having the above-described crystal structure is composed of one or more elements from the rare earth sites and one or more elements from the iron group sites, and h moles of nitrogen (N) are introduced intermittently into this phase. The above-described crystal structure can be maintained if the amount of nitrogen (N) introduced is h moles (where h is 2.9 to 3.1). Details about nitrogen (N) in the main phase will be described later.

[0028] The rare earth sites are Sm, La, Ce, and R 1 It consists of Sm, La, Ce, and R 1 Each exists in molar ratio in the proportion (1-xyz):x:y:z. Since (1-xyz)+x+y+z=1, a portion of Sm is La, Ce, and R 1 This means that it is substituted with one or more elements selected from the group consisting of [the specified elements].

[0029] The iron group sites consist of Fe, Co, Ni, and M, with each of these present in a molar ratio of (1-pqs):p:q:s. Since (1-pqs)+p+q+s=1, this means that a portion of the Fe is substituted by one or more elements selected from the group consisting of Co, Ni, and M.

[0030] The following explains each element that makes up the above equation and their respective content ratios (molar ratios).

[0031] <Sm> Sm is a major element that, along with Fe and N, constitutes the aforementioned crystal structure. Some of the Sm is found in La, Ce, and R 1 It is substituted with one or more elements selected from the group consisting of the following: La, Ce, and R 1 I will explain this.

[0032] <La> La belongs to the so-called light rare earth elements, and compared to sm, it has a large reserve (resource) and is inexpensive. Since the ionic radius of La is much larger than that of sm, substituting some of the sm with La basically increases the lattice volume of the main phase.

[0033] As mentioned above, the ionic radius of La is much larger than that of Sm. Therefore, substituting some of Sm with La has a significant effect on the change in the lattice volume of the main phase. However, if the amount of La substitution is too large, the main phase will change to Th2Zn 17 Type and Th2Ni 17 It becomes difficult to maintain at least one of the crystal structures of the type. Therefore, if some of the Fe is replaced with Co and / or Ni, which have smaller ionic radii than Fe, the increase in lattice volume is suppressed, and as a result the main phase becomes Th2Zn 17 Type and Th2Ni 17 It is possible to maintain at least one of the crystal structures of the type. The substitution ratios when a portion of Sm is substituted with La, and when a portion of Fe is substituted with Co, will be described later.

[0034] 〈Ce〉 Ce belongs to the so-called light rare earth elements, and compared to Sm, it has a larger reserve (resource) and is inexpensive. Since the ionic radius of Ce is slightly larger than that of Sm, substituting some of Sm with Ce basically increases the lattice volume of the main phase. However, because Ce ions can exist in trivalent and tetravalent states, substituting some of Sm with Ce may increase or decrease the lattice volume of the main phase.

[0035] As described above, the ionic radius of Ce is slightly larger than that of Sm. Therefore, even if a part of Sm is replaced with Ce, the influence on the change in the lattice volume of the main phase is small, and thus the influence on the saturation magnetization and the anisotropy magnetic field is small. Therefore, Ce may be optionally contained in the Sm-Fe-N-based magnetic material of the present disclosure. As described above, since La has a large influence on the change in the lattice volume of the main phase, replacing a part of Sm with La needs to be carried out simultaneously with replacing a part of Fe with Co, and there is also an upper limit on the replacement ratio of La. Therefore, in order to increase the reduction amount of Sm, optionally, a part of Sm may be replaced with Ce.

[0036] 〈R 1 〉 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, when purifying raw materials containing Sm, La, and Ce respectively, it is difficult to completely separate them from each other, and one or more rare earth elements other than Sm, La, and Ce that 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 a part of Sm may be replaced with Zr. Even if a part of Sm is replaced with Zr, if the replacement amount is small, the magnetic properties of the Sm-Fe-N-based magnetic material will not be significantly impaired.

[0037] In this specification, unless otherwise specified, rare earth elements consist of 17 elements: Sc (scandium), Y (yttrium), La (lanthanum), Ce (cerium), Pr (praseodymium), Nd (neodymium), Pm (promethium), Sm (samarium), Eu (eurobium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Yb (ytterbium), and Lu (ruthenium). Of these, unless otherwise specified, Sc, Y, La, and Ce are light rare earth elements. Also, unless otherwise specified, Pr, Nd, Pm, Sm, and Eu are medium rare earth elements. Unless otherwise specified, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu are heavy rare earth elements. Generally, heavy rare earth elements are rare, and light rare earth elements are rare. The rarity of medium rare earth elements falls between that of heavy and light rare earth elements.

[0038] <Fe> Fe, along with Sm and N, is a major element constituting the crystal structure described above. A portion of Fe must be substituted with one or more elements selected from the group consisting of Co and Ni, and may also be substituted with M. Co, Ni, and M will be explained below.

[0039] <Co> A portion of the Fe is substituted with Co and / or Ni, and substitution with Co is preferred. Co belongs to the so-called iron group elements, and the ionic radius of Co is smaller than that of Fe. Substituting a portion of Sm with La basically increases the lattice volume of the main phase, so by substituting a portion of Fe with Co, it is possible to suppress an excessive increase in the lattice volume of the main phase.

[0040] Replacing some of the Fe with Co increases the Curie temperature of the main phase, which is advantageous because it suppresses the decrease in saturation magnetization at high temperatures (403-473K).

[0041] <Ni> Some of the Fe is substituted with Co and / or Ni. Ni belongs to the so-called iron group elements, and its ionic radius is smaller than that of Fe. Substituting some of Sm with La basically increases the lattice volume of the main phase, so substituting some of Fe with Ni can suppress an excessive increase in the lattice volume of the main phase.

[0042] Replacing part of Fe with Ni raises concerns about a decrease in magnetic properties. However, since the ionic radius of Ni is smaller than that of Co, when replacing part of Fe with Ni, the lattice volume of the main phase decreases significantly even without a very high substitution rate of Ni, compared to when replacing part of Fe with Co. Therefore, for example, when replacing part of Sm with a large amount of La excessively increases the lattice volume of the main phase, using a relatively small amount of Ni can advantageously suppress the lattice volume of the main phase. As a result, suppressing the lattice volume of the main phase outweighs the degradation of magnetic properties caused by replacing part of Fe with Ni, thus improving Th2Zn 17 Type and Th2Ni 17 It contributes to the stabilization of maintaining at least one of the crystal structures of the type. Furthermore, even when the amount of Sm used is increased by substituting some of the Sm with La, it contributes to improving the saturation magnetization while suppressing the decrease in the anisotropic magnetic field as much as possible.

[0043] <M> M is one or more elements other than Fe, Co, Ni, and rare earth elements, as well as unavoidable impurity elements. M is one or more elements and unavoidable impurity elements that are permitted to be included in a range that does not impair the magnetic properties of the Sm-Fe-N magnetic material of this disclosure. An unavoidable impurity element is an impurity element whose inclusion cannot be avoided when manufacturing the Sm-Fe-N magnetic material of this disclosure, or whose avoidance would lead to a significant increase in manufacturing costs. Examples of such unavoidable impurity elements include impurity elements in the raw materials, or elements such as Cu (copper), Zn (zinc), Ga (gallium), Al (aluminum), and B (boron), which, for example, diffuse and / or penetrate into the surface of the main phase when forming a bonded molded body. Other examples include elements contained in lubricants used during molding that diffuse and / or penetrate into the surface of the main phase.

[0044] Examples of M, excluding unavoidable impurity elements, include one or more elements selected from the group consisting of Ti (titanium), Cr (chromium), Mn (manganese), V (vanadium), Mo (molybdenum), W (tungsten), and C (carbon). These elements, for example, form nuclei during the formation of the main phase, contributing to the refinement of the main phase and / or the suppression of grain growth in the main phase.

[0045] Furthermore, M may include Zr. As mentioned above, Zr is not a rare earth element, but in some cases, a portion of Sm may be substituted with Zr, while in other cases, a portion of Fe may be substituted with Zr. In either case, if the amount of substitution is small, it will not significantly impair the magnetic properties of the Sm-Fe-N magnetic material.

[0046] <N> N is introduced intermittently into the main phase having the aforementioned crystalline structure. The introduction of N, to an extent that does not destroy the phase having the aforementioned crystalline structure, allows a magnetic moment to emerge within the main phase.

[0047] The Sm-Fe-N-based magnetic material of the present disclosure is such that part of Sm is replaced by essential La and optionally Ce, and part of Fe is replaced by Co and / or Ni, preferably Co. Regarding this, 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 is used to explain as follows.

[0048] 〈x + y〉 In the above formula representing the composition of the main phase, the value of x indicates the ratio (molar ratio) of the part of Sm replaced by La, and the value of y indicates the ratio (molar ratio) of the part of Sm replaced by Ce.

[0049] If the value of x + y is 0.25 or more, an improvement in economy can be substantially recognized due to part of Sm being replaced by inexpensive La and / or Ce. Also, if the value of x + y is 0.25 or more, it is substantially recognized that the saturation magnetization is improved while suppressing the decrease in the anisotropy magnetic field as much as possible. From these viewpoints, the value of x + y may be 0.28 or more, 0.30 or more, 0.35 or more, 0.40 or more, 0.47 or more, 0.51 or more, or 0.55 or more. On the other hand, if the value of x + y is 0.73 or less, considering that part of Fe is replaced by Co and / or Ni, the main phase can maintain at least one of the crystal structures of the Th2Zn 17 type and the Th2Ni 17 type. From this viewpoint, the value of x + y may be 0.70 or less, 0.65 or less, or 0.58 or less.

[0050] Furthermore, while the value of x+y satisfies the above range, the value of x may be 0.25 or greater, 0.28 or greater, 0.30 or greater, 0.35 or greater, 0.40 or greater, 0.47 or greater, 0.48 or greater, 0.51 or greater, or 0.55 or greater, and may be 0.73 or less, 0.70 or less, 0.65 or less, or 0.58 or less. Similarly, while the value of x+y satisfies the above range, the value of y may be 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, 0.10 or less, or 0.05 or less, and may be 0. When y is 0, it means that Ce is not intentionally included, and that the presence of Ce cannot be practically measured.

[0051] <Relationship between x and x+y> When a portion of Sm is substituted by La (essentially) and Ce (optionally), a higher proportion of La is preferable to improve saturation magnetization while minimizing the decrease in anisotropic magnetic field. Therefore, x / (x+y) may be 0.80 or greater, 0.82 or greater, 0.85 or greater, 0.90 or greater, or 0.95 or greater, and may be 1. When x / (x+y) is 1, it means that y is 0, that is, that Ce is intentionally not included, and that the presence of Ce cannot be practically measured.

[0052] <z> In the above equation representing the composition of the main phase, z is where a part of Sm is R 1 This indicates the proportion (molar ratio) of substitution with R. 1 z is one or more rare earth elements and Zr that are permitted to be included in a range that does not impair the magnetic properties of the Sm-Fe-N magnetic material of this disclosure. Therefore, z may 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, if the Sm-Fe-N magnetic material of this disclosure is R 1 It does not contain any of the above, i.e., z may be 0, but when manufacturing the Sm-Fe-N magnetic material of this disclosure, if the raw materials contain R 1 It is difficult to completely eliminate the presence of [the substance]. From this perspective, z may be 0.01 or greater.

[0053] <p+q> In the above equation representing the composition of the main phase, the value of p indicates the proportion (molar ratio) in which some of the Fe is replaced by Co, and the value of q indicates the proportion (molar ratio) in which some of the Fe is replaced by Ni.

[0054] If a portion of Sm is substituted with a small amount of La and / or Ce, and a portion of Fe is not substituted with Co and / or Ni, i.e., even if the value of p+q is 0, Th2Zn 17 Type and Th2Ni 17 It is possible to maintain at least one of the crystal structures of the type.

[0055] However, in magnetic materials of the present invention, such as the Sm-Fe-N system, in order to significantly reduce the amount of Sm used, a portion of Sm is substituted with La (essentially) and Ce (optionally). In such cases, the amount of substitution is large, and the lattice volume of the main phase basically increases. Therefore, a portion of Fe is substituted with Co and / or Ni, resulting in Th2Zn. 17 Type and Th2Ni 17 Maintain at least one of the crystal structures of the type.

[0056] If the value of p+q is 0.10 or greater, then Th2Zn 17 Type and Th2Ni 17 At least one of the crystal structures of the type can be maintained. From this viewpoint, the value of p+q may be 0.15 or greater, 0.20 or greater, 0.22 or greater, or 0.30 or greater. On the other hand, although Co and Ni are more expensive than Fe, if the value of p+q is 0.53 or less, it will not offset the economic improvement achieved by substituting some of Sm with inexpensive La and / or Ce. From this viewpoint, the value of p+q may be 0.50 or less, 0.45 or less, 0.40 or less, 0.35 or less, or 0.33 or less.

[0057] Furthermore, while the value of p+q satisfies the above range, the value of p may be 0.10 or greater, 0.15 or greater, 0.20 or greater, 0.22 or greater, or 0.30 or greater, and may be 0.53 or less, 0.50 or less, 0.45 or less, 0.40 or less, 0.35 or less, or 0.33 or less. Similarly, while the value of p+q satisfies the above range, the value of q may be 0.20 or less, 0.15 or less, 0.10 or less, 0.08 or less, 0.06 or less, 0.04 or less, or 0.02 or less, and may be 0. When q is 0, it means that Ni is not intentionally included, and that the presence of Ni cannot be practically measured.

[0058] <Relationship between x+y and p+q> x+y and p+q satisfy the relationship p+q≧1.45(x+y)-0.5485. If this relationship is satisfied, then Th2Zn 17 Type and Th2Ni 17 The saturation magnetization is improved while maintaining at least one of the crystal structures of the type and suppressing the decrease in the anisotropic magnetic field as much as possible.

[0059] As explained above, when a portion of Sm is replaced with La or Ce, and when a portion of Fe is replaced with Co or Ni, La and Co have a significant influence on improving saturation magnetization while suppressing the decrease in the anisotropic magnetic field as much as possible. From this, in the relationship p+q≧1.45(x+y)-0.5485, we can roughly approximate q and y as 0, and consider that the relationship p≧1.45x-0.5485 is approximately satisfied. According to this, the value of x represents the proportion (molar ratio) in which a portion of Sm is replaced with La, and the value of p represents the proportion (molar ratio) in which a portion of Fe is replaced with Co, so the substitution effect of La can be considered to be 1.45 times that of Co.

[0060] 〈s〉 In the above formula representing the composition of the main phase, s represents the proportion (molar ratio) of Fe that is substituted with M. As described above, M is one or more elements and unavoidable impurity elements that are permitted to be included in a range that does not impair the magnetic properties of the Sm-Fe-N magnetic material of this disclosure. For this reason, s may 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 magnetic material of this disclosure may contain no M at all, i.e., s may be 0, but it is difficult to completely eliminate unavoidable impurity elements from M. From this viewpoint, s may be 0.01 or more.

[0061] <h> Next, we will explain h, which indicates the degree of nitriding. Sm2Fe 17 When the phase is nitrided, it basically becomes Sm2Fe 17 N h It forms a phase (where h=3). Nitriding is typically performed in Sm2Fe 17 This process is carried out by exposing a phase-containing Sm-Fe-N magnetic material precursor (hereinafter sometimes simply referred to as "precursor") to a nitrogen gas atmosphere at high temperatures. Therefore, because the degree of nitriding differs between the surface and interior of the precursor, h can vary in the range of 2.9 to 3.3. The same applies when, in the precursor, part of the Sm is substituted with La and / or Ce, and part of the Fe is substituted with Co and / or Ni. That is, (Sm, La, Ce)2(Fe, Co, Ni) 17 When the phase is nitrided, (Sm, La, Ce)2(Fe, Co, Ni) 17 N h It forms a phase (where h is between 2.9 and 3.3).

[0062] The main phase of the Sm-Fe-N magnetic material of this disclosure has the composition described above, and furthermore, if the lattice volume, lattice constant, volume fraction, and density are as follows, the saturation magnetization is improved while remaining even more stable and suppressing the decrease in the anisotropic magnetic field as much as possible. The lattice volume, lattice constant, volume fraction, and density will be described below.

[0063] <Lattice volume> The lattice volume of the main phase is 0.829–0.838 nm. 3 It is preferable that the lattice volume of the main phase is within this range. 17 Type and Th2Ni 17 This makes it easier to maintain at least one of the crystal structures of the type.

[0064] As mentioned above, saturation magnetization originates from the emergence of a magnetic moment within the main phase due to the intrusion of nitrogen (N) into the main phase. Therefore, saturation magnetization is greatly influenced by the Fe-N distance (hereinafter sometimes simply referred to as the "Fe-N distance") within the lattice of the main phase. Since Fe and N are arranged three-dimensionally within the lattice of the main phase, the lattice volume of the main phase is convenient for determining the Fe-N distance.

[0065] In the Sm-Fe-N magnetic material of this disclosure, a portion of Sm is substituted by La, optionally by Ce, and a portion of Fe is substituted by Co and / or Ni. This results in Sm2Fe 17 The lattice volume of the N3 phase is changed. At this time, the Fe-N distance in the lattice of the main phase is changed to Sm2Fe 17 It is considered best to approximate the Fe-N distance in the N3 phase lattice. 17 The lattice volume of the N3 phase is approximately 0.838 nm. 3 Therefore, the lattice volume of the main phase of the Sm-Fe-N magnetic material of this disclosure is set to 0.838 nm. 3 It is considered best to bring it closer to Th2Zn. 17 Type and Th2Ni 17 To maintain at least one of the crystal structures of the type and to improve saturation magnetization while suppressing the decrease in anisotropic magnetic field as much as possible, the lattice volume of the main phase should be Sm2Fe 17 It is preferable that the lattice volume of the N3 phase is the same as or slightly smaller than that of the N3 phase. From these viewpoints, the lattice volume of the main phase is 0.829 nm. 3 Above, 0.830nm 3 Above, 0.831nm 3 Above, 0.832nm 3 Above, 0.833nm 3Above or above, or 0.834nm 3 The above is sufficient, and 0.838nm 3 Below, 0.837nm 3 Below, 0.836nm 3 The following, or 0.835nm 3 The following is acceptable:

[0066] The lattice volume of the main phase can be determined as follows: The Sm-Fe-N magnetic material is subjected to X-ray diffraction analysis, and the a-axis length and c-axis length are determined from the X-ray diffraction pattern based on the relationship between the plane index and the lattice plane spacing value (d value). When determining the a-axis length and c-axis length, it can be assumed that the main phase of the Sm-Fe-N magnetic material of this disclosure is a rhombohedral crystal, since the main phase has the above-described crystal structure. Therefore, the (202), (113), (104), (211), (122), and (300) planes can be used as plane indices. The lattice volume can then be calculated according to the following formula. (Lattice volume) = {(a-axis length) / 2} 2 ×6×3 0.5 ×{(c-axis length) / 3}

[0067] <Lattice constant> The lattice constant of the main phase is preferably 1.4350 to 1.4460. When the lattice constant of the main phase is within this range, the main phase is flattened, the saturation magnetization is improved, and the decrease in the anisotropic magnetic field is smaller than expected from the reduction in the amount of Sm used. From these viewpoints, the lattice constant of the main phase may be 1.4360 or higher, 1.4370 or higher, 1.4380 or higher, 1.4390 or higher, 1.4400 or higher, 1.4410 or higher, 1.4420 or higher, or 1.4430 or higher, and may also be 1.4459 or lower, 1.4458 or lower, or 1.4457 or lower.

[0068] The lattice constant of the main phase can be determined as follows: The Sm-Fe-N magnetic material is subjected to X-ray diffraction analysis, and the a-axis length and c-axis length are determined from the X-ray diffraction pattern based on the relationship between the plane index and the lattice plane spacing value (d value). When determining the a-axis length and c-axis length, it can be assumed that the main phase of the Sm-Fe-N magnetic material of this disclosure is a rhombohedral crystal, since the main phase has the above-described crystal structure. Therefore, the (202), (113), (104), (211), (122), and (300) planes can be used as plane indices. The lattice constant can then be calculated according to the following formula. Lattice constant (a / c) = (a-axis length) / (c-axis length)

[0069] <Volume ratio> The Sm-Fe-N magnetic material of this disclosure comprises a main phase represented by the above-described composition formula. The magnetic properties of the Sm-Fe-N magnetic material of this disclosure are exhibited by the main phase. Therefore, it is preferable that the volume fraction of the main phase is high relative to the entire Sm-Fe-N magnetic material of this disclosure. Specifically, the volume fraction of the main phase may be 80% or more, 81% or more, or 85% or more relative to the entire Sm-Fe-N magnetic material of this disclosure. On the other hand, when manufacturing the Sm-Fe-N magnetic material of this disclosure, there may be processes in which phases other than the main phase represented by the above-described composition formula are in a stable temperature range. Also, it may be difficult to completely eliminate the inclusion of unavoidable impurity elements that do not constitute the main phase. For these reasons, while a volume fraction of 100% for the main phase is ideal, as long as the aforementioned volume fraction of the main phase is ensured, there are no practical problems even if the volume fraction of the main phase is 99% or less, 98% or less, 97% or less, 96% or less, or 95% or less.

[0070] Phases other than the main phase typically exist at grain boundaries between main phases, particularly at the triple point. Typical examples of phases other than the main phase include the SmFe3 phase and its nitrided phase. In the SmFe3 phase and its nitrided phase, some of the Sm is replaced with La, Ce, and R 1A phase in which one or more elements selected from the group consisting of are substituted and its nitrided phase, a phase in which a portion of Fe is substituted with one or more elements selected from the group consisting of Co, Ni, and M and its nitrided phase, and a portion of Sm is substituted with La, Ce, and R 1 The present invention includes a phase in which one or more elements selected from the group consisting of are substituted, and in which a portion of Fe is substituted with one or more elements selected from the group consisting of Co, Ni, and M, and its nitrided phase.

[0071] The volume fraction of the main phase was determined by measuring the overall composition of the precursor before nitriding using inductively coupled plasma atomic emission spectroscopy (ICP-AES), and from the measured values, the precursor before nitriding was determined to be (Sm, La, Ce, R 1 )2(Fe, Co, Ni, M) 17 Phase and (Sm, La, Ce, R 1 Assuming that it is separated into three phases (Fe, Co, Ni, M), the volume fraction of the main phase is calculated. Specifically, after obtaining the mass concentration (mass fraction) of each element from the measurement results by ICP, Sm2Fe 17 First, calculate the mass ratio of the phase and the SmFe3 phase, and then calculate the volume fraction from the density of each phase. Note that (Sm, La, Ce, R 1 )2(Fe, Co, Ni, M) 17 The phase is Sm2Fe 17 phase, Sm2Fe 17 Some of the phase Sm are Sm, La, Ce, and R 1 A phase in which one or more elements selected from the group consisting of Sm2Fe are substituted. 17 A phase in which part of the Fe in the phase is replaced by one or more elements selected from the group consisting of Co, Ni, and M, and Sm2Fe 17 Some of the phase Sm are Sm, La, Ce, and R 1 It is substituted with one or more elements selected from the group consisting of and Sm2Fe 17 This represents a phase in which a portion of the Fe in the phase is replaced by one or more elements selected from the group consisting of Co, Ni, and M. Also, (Sm, La, Ce, R 1The (Fe, Co, Ni, M) three-phase is SmFe three-phase, and a portion of the Sm in the SmFe three-phase is Sm, La, Ce, and R 1 A phase in which one or more elements selected from the group consisting of are substituted, a phase in which a portion of the Fe in the SmFe3 phase is substituted with one or more elements selected from the group consisting of Co, Ni, and M, and a phase in which a portion of the Sm in the SmFe3 phase is substituted with Sm, La, Ce, and R 1 It is substituted with one or more elements selected from the group consisting of and Sm2Fe 17 This represents a phase in which a portion of the Fe in the phase is replaced by one or more elements selected from the group consisting of Co, Ni, and M.

[0072] The overall composition (sum of the main phase and other phases) of the Sm-Fe-N magnetic material of this disclosure is such that, from the viewpoint of suppressing the appearance of the α-(Fe, Co, Ni, M) phase and its nitride phase during the manufacturing of the Sm-Fe-N magnetic material of this disclosure, the main phase consists of Sm, La, Ce, and R 1 The total number of moles can be kept above this amount. That is, the overall composition of the Sm-Fe-N magnetic material of this disclosure is (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 (However, w may be 2.00 to 3.00). In this case, 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 expression of the α-(Fe, Co, Ni, M) phase, it is more preferable that w is 2.02 or higher, 2.04 or higher, 2.06 or higher, 2.08 or higher, 2.10 or higher, 2.20 or higher, 2.30 or higher, 2.40 or higher, or 2.50 or higher. On the other hand, the above-mentioned (Sm, La, Ce, R 1 From the viewpoint of reducing the volume fraction of the (Fe, Co, Ni, M) three phases, w is more preferably 2.90 or less, 2.80 or less, 2.70 or less, or 2.60 or less.

[0073] <Density of the main phase> The density of the main phase is 7.40 g / cm³. 3 More than 7.45g / cm 3 Above, or 7.50 g / cm³ 3 The above is preferable, 7.76 g / cm³ 3 Below, 7.70g / cm 3 The following, or 7.65 g / cm³ 3 The following is preferable: When the density of the main phase is within this range, it contributes to improving the saturation magnetization.

[0074] The density of the main phase is obtained by grinding the Sm-Fe-N magnetic material to obtain a powder, and then measuring the density of the powder using a pycnometer. As described above, in the Sm-Fe-N magnetic material of this disclosure, it is preferable that the volume fraction of the main phase is 80%. Also, Sm2Fe 17 The densities of the N3 phase and the SmFe3 phase are 7.65 g / cm³, respectively. 3 and 8.25 g / cm³ 3 Therefore, they are not that different. From this, the density of the main phase can be approximated by the value obtained by the measurement method described above.

[0075] 《Manufacturing method》 Next, the method for manufacturing the Sm-Fe-N magnetic material of this disclosure (hereinafter sometimes referred to as "the manufacturing method of this disclosure") will be described.

[0076] The manufacturing method disclosed herein includes a magnetic material precursor preparation step and a nitriding step. Each of these steps will be described below.

[0077] <Magnetic material precursor preparation process> In the manufacturing method of this disclosure, 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 A magnetic material precursor is prepared, comprising a crystalline phase having the composition represented by [the formula shown].

[0078] In the formula representing the composition of the crystalline phase, Sm, La, Ce, R 1 Fe, Co, Ni, and M, as well as x, y, z, p, q, and s, are as explained in "《Sm-Fe-N Magnetic Materials》".

[0079] The crystalline phase of the magnetic material precursor is Th2Zn 17 Type and Th2Ni 17 It has at least one of the following crystal structures. When the magnetic material precursor is nitrided, the crystalline phase in the magnetic material precursor is nitrided, and the main phase of the Sm-Fe-N-based magnetic material of this disclosure is formed. The main phase of the Sm-Fe-N-based magnetic material of this disclosure is Th2Zn 17 Type and Th2Ni 17 It has at least one of the crystal structures of the type. From this, it can be seen that nitriding is Th2Zn 17 Type and Th2Ni 17 The process is carried out to the extent that at least one of the crystal structures of the type is maintained, and a main phase having the lattice volume and lattice constant within the range described above can be obtained.

[0080] As described above, the crystalline phase in the magnetic material precursor is nitrided to form the main phase of the Sm-Fe-N magnetic material of this disclosure. Therefore, the volume fraction of the crystalline phase in the magnetic material precursor can be considered equivalent to the volume fraction of the main phase in the Sm-Fe-N magnetic material of this disclosure. For this reason, the volume fraction of the crystalline phase in the magnetic material precursor may be 80% or more, 81% or more, or 85% or more of the total volume fraction of the magnetic material precursor. When manufacturing the magnetic material precursor, there may be processes in which phases other than the crystalline phase represented by the above composition formula are in a stable temperature range. In addition, it may be difficult to completely eliminate the inclusion of unavoidable impurity elements that do not constitute the crystalline phase. While a volume fraction of 100% for the crystalline phase is ideal, as long as the aforementioned volume fraction of the crystalline phase is secured, there is no practical problem even if the volume fraction of the main phase is 99% or less, 98% or less, 97% or less, 96% or less, or 95% or less.

[0081] Phases other than crystalline phases typically exist at grain boundaries between crystalline phases, particularly at triple points. Typical examples of non-crystalline phases include the SmFe3 phase. In the SmFe3 phase, some of the Sm is replaced by La, Ce, and R1 A phase in which one or more elements selected from the group consisting of are substituted, a phase in which part of Fe is substituted with one or more elements selected from the group consisting of Co, Ni, and M, and a phase in which part of Sm is substituted with La, Ce, and R 1 The phase is substituted with one or more elements selected from the group consisting of , and includes a phase in which a portion of Fe is substituted with one or more elements selected from the group consisting of Co, Ni, and M.

[0082] The volume fraction of the crystalline phase was determined by measuring the overall composition of the precursor before nitriding using inductively coupled plasma atomic emission spectroscopy (ICP-AES), and from the measured values, the precursor before nitriding was determined to be (Sm, La, Ce, R 1 )2(Fe, Co, Ni, M) 17 Phase and (Sm, La, Ce, R 1 Assuming that it is separated into three phases (Fe, Co, M), the volume fraction of the crystalline phase is calculated. Specifically, after obtaining the mass concentration (mass fraction) of each element from the measurement results by ICP, Sm2Fe 17 First, calculate the mass ratio of the phase and the SmFe3 phase, and then calculate the volume fraction from the density of each phase. Note that (Sm, La, Ce, R 1 )2(Fe, Co, Ni, M) 17 The phase is Sm2Fe 17 phase, Sm2Fe 17 Some of the phase Sm are Sm, La, Ce, and R 1 A phase in which one or more elements selected from the group consisting of Sm2Fe are substituted. 17 A phase in which part of the Fe in the phase is replaced by one or more elements selected from the group consisting of Co, Ni, and M, and Sm2Fe 17 Some of the phase Sm are Sm, La, Ce, and R 1 It is substituted with one or more elements selected from the group consisting of and Sm2Fe 17 This represents a phase in which a portion of the Fe in the phase is replaced by one or more elements selected from the group consisting of Co, Ni, and M. Also, (Sm, La, Ce, R 1The (Fe, Co, Ni, M) three-phase is SmFe three-phase, and a portion of the Sm in the SmFe three-phase is Sm, La, Ce, and R 1 A phase in which one or more elements selected from the group consisting of are substituted, a phase in which a portion of the Fe in the SmFe3 phase is substituted with one or more elements selected from the group consisting of Co, Ni, and M, and a phase in which a portion of the Sm in the SmFe3 phase is substituted with Sm, La, Ce, and R 1 This represents a phase in which one or more elements selected from the group consisting of are substituted, and in which a portion of the Fe in the SmFe3 phase is substituted with one or more elements selected from the group consisting of Co, Ni, and M.

[0083] The overall composition of the magnetic material precursor (total of crystalline and non-crystalline phases) is important from the viewpoint of suppressing the emergence of the α-(Fe, Co, Ni, M) phase during the production of the magnetic material precursor, specifically the crystalline phases Sm, La, Ce, and R 1 The total number of moles can be kept above this. That is, the overall composition of the magnetic material precursor is (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 (However, w may be 2.00 to 3.00). In this case, x, y, z, p, q, and s may be the same as x, y, z, p, q, and s in the formula representing the composition of the crystalline phase described above. From the viewpoint of suppressing the appearance of the α-(Fe, Co, Ni, M) phase, it is more preferable that w is 2.02 or higher, 2.04 or higher, 2.06 or higher, 2.08 or higher, 2.10 or higher, 2.20 or higher, 2.30 or higher, 2.40 or higher, or 2.50 or higher. On the other hand, (Sm, La, Ce, R 1 From the viewpoint of reducing the volume fraction of the (Fe, Co, Ni, M) three phases, w is more preferably 2.90 or less, 2.80 or less, 2.70 or less, or 2.60 or less.

[0084] Magnetic material precursors can be obtained using well-known manufacturing methods. One method for obtaining magnetic material precursors is to dissolve and solidify raw materials containing the elements that constitute the magnetic material precursor. One method for dissolving the raw materials is to charge the raw materials into a container such as a crucible, obtain molten metal by arc melting or high-frequency melting the raw materials in the container, and then pour the molten metal into a mold such as a book mold, or to solidify the molten metal in a crucible. From the viewpoint of suppressing the coarsening of the crystalline phase in the magnetic material precursor and homogenizing the crystalline phase, it is preferable to increase the cooling rate of the molten metal. From this viewpoint, it is preferable to pour the molten metal into a mold such as a book mold. Furthermore, from the viewpoint of suppressing the coarsening of the crystalline phase in the magnetic material precursor and improving the homogenization of the crystalline phase, for example, the following method may be adopted. In other words, the raw materials may be melted by high-frequency induction melting or arc melting in a container and solidified to obtain an ingot, which may then be melted again by high-frequency induction melting or the like, and the melt may be rapidly cooled using a strip casting method or liquid quenching method to obtain a thin piece, which may then be used as a magnetic material precursor.

[0085] Prior to the nitriding process described later, the magnetic material precursor may be heat-treated (hereinafter, such heat treatment may be referred to as "homogenization heat treatment") to homogenize the crystal grains in the magnetic material precursor. The temperature of the homogenization heat treatment may be, for example, 1273K or higher, 1323K or higher, or 1373K or higher, and may be 1523K or lower, 1473K or lower, or 1423K or lower. The time for the homogenization heat treatment may be, for example, 6 hours or more, 12 hours or more, 18 hours or more, or 24 hours or more, and may be 48 hours or less, 42 hours or less, 36 hours or less, or 30 hours or less.

[0086] To suppress oxidation of the magnetic material precursor, the homogenization heat treatment is preferably carried out in an inert gas atmosphere. The inert gas atmosphere does not include a nitrogen gas atmosphere. When the homogenization heat treatment is carried out in a nitrogen gas atmosphere, Th2Zn 17 Type and / or Th2Ni 17 This is because phases with a specific crystal structure are easily decomposed.

[0087] <Nitriding process> The magnetic material precursor described above is nitrided. As a result, the crystalline phase in the magnetic material precursor is nitrided, forming the main phase of the Sm-Fe-N magnetic material of this disclosure.

[0088] While there are no particular limitations on the nitriding method as long as the desired main phase can be obtained, typical methods include, for example, exposing the magnetic material precursor to a nitrogen gas-containing atmosphere while heating it, or to a nitrogen (N)-containing gas atmosphere. Examples of nitrogen gas-containing atmospheres include a nitrogen gas atmosphere, a mixed gas atmosphere of nitrogen gas and an inert gas, and a mixed gas atmosphere of nitrogen gas and hydrogen gas. Examples of nitrogen (N)-containing gas atmospheres include an ammonia gas atmosphere, or a mixed gas atmosphere of ammonia gas and hydrogen gas. Combinations of the atmospheres exemplified above may also be used. From the viewpoint of nitriding efficiency, an ammonia gas atmosphere, a mixed gas atmosphere of ammonia gas and hydrogen gas, and a mixed gas atmosphere of nitrogen gas and hydrogen gas are preferred.

[0089] The magnetic material precursor may be pulverized before nitriding to obtain a magnetic material precursor powder, and then the magnetic material precursor powder may be nitrided. By pulverizing the magnetic material precursor before nitriding, the crystalline phase present inside the magnetic material precursor can be sufficiently nitrided. It is preferable to pulverize the magnetic material precursor in an inert gas atmosphere. The inert gas atmosphere may include a nitrogen gas atmosphere. This suppresses oxidation of the magnetic material precursor during pulverization. The particle size of the magnetic material precursor powder is D 50 The particle size may be 5 μm or larger, 10 μm or larger, or 15 μm or larger, and may be 50 μm or smaller, 40 μm or smaller, 30 μm or smaller, 25 μm or smaller, or 20 μm or smaller.

[0090] The nitriding temperature may be, for example, 673K ​​or higher, 698K or higher, 723K or higher, or 748K or higher, and may be 823K or lower, 798K or lower, or 773K or lower. The nitriding time may be, for example, 4 hours or more, 8 hours or more, 12 hours or more, or 16 hours or more, and may be 48 hours or less, 36 hours or less, 24 hours or less, 20 hours or less, or 18 hours or less.

[0091] 《Transformation》 The Sm-Fe-N magnetic material and its manufacturing method described herein are not limited to the embodiments described herein, and may be modified as appropriate within the scope of the claims. For example, the Sm-Fe-N magnetic material of this disclosure may be a powder or a molded body of the powder. The molded body may be a bonded molded body or a sintered molded body. In the case of a molded body, a bonded molded body is preferred from the viewpoint of easily avoiding temperatures at which nitrogen (N) in the main phase detaches (decomposes) during the molding process. Examples of the bond include resins and low-melting-point metal bonds. Examples of low-melting-point metal bonds include metallic zinc or zinc alloys and combinations thereof. [Examples]

[0092] The Sm-Fe-N magnetic material and its manufacturing method described herein will be further described in detail below with reference to examples and comparative examples. However, the Sm-Fe-N magnetic material and its manufacturing method described herein are not limited to the conditions used in the following examples.

[0093] Sample preparation Samples of Sm-Fe-N magnetic material were prepared as follows.

[0094] Metallic materials Sm, La, Ce, Fe, Co, and Ni were blended so that the main phase had the composition shown in Table 1. This mixture was then high-frequency dissolved at 1673K (1400°C) and solidified to obtain a magnetic material precursor. During blending, the total number of moles of Sm, La, and Ce added was greater than the total number of moles of Sm, La, and Ce in the main phase, so that the volume fraction of the main phase was 80-100%. In this specification, for example, "metallic Sm" refers to unalloyed Sm. Of course, metallic Sm, metallic La, metallic Ce, metallic Fe, metallic Co, and metallic Ni may contain unavoidable impurities.

[0095] The magnetic material precursor was subjected to homogeneous heat treatment in an argon gas atmosphere at 1373K for 24 hours.

[0096] The magnetic material precursor after homogenization heat treatment was placed in a glove box and pulverized using a cutter mill in a nitrogen gas atmosphere. The particle size of the pulverized magnetic material precursor powder was D 50 The size was 20 μm or less.

[0097] Magnetic material precursor powder was heated to 748K in a nitrogen gas atmosphere and nitrided for 16 hours. The amount of nitriding was determined by the change in mass of the magnetic material precursor powder before and after nitriding.

[0098] "evaluation" For each sample, the composition of the main phase, lattice volume, lattice constant, density, and volume fraction were determined using the measurement methods described above. Furthermore, for each sample, the magnetic properties were measured using the PPMS(registered trademark)-VSM physical property processing system, applying a maximum magnetic field of 9T. For the measurement of magnetic properties, each sample powder, after nitriding, was solidified in epoxy resin while being oriented in a magnetic field. The magnetic properties of each solidified sample were then measured at 300-453K in both the easy-magnetization axis direction and the hard-magnetization axis direction. Saturation magnetization was calculated from the measured values ​​in the easy-magnetization axis direction using the saturation asymptotic law. Then, the saturation magnetization Ms was calculated by dividing the saturation magnetization obtained using the saturation asymptotic law by the volume fraction of the main phase. Additionally, the anisotropic magnetic field Ha was determined from the intersection of the hysteresis curve in the easy-magnetization axis direction and the hysteresis curve in the hard-magnetization axis direction.

[0099] The results are shown in Table 1. In Table 1, "-" indicates that the crystal structure, density, and volume fraction of the main phase, as well as the saturation magnetization and anisotropic magnetic field, could not be measured due to poor phase stability.

[0100] [Table 1-1]

[0101] [Table 1-2]

[0102] [Table 1-3]

[0103] [Table 1-4]

[0104] Figure 1 is a graph showing the relationship between the molar ratio of La x and the molar ratio of Co p and phase stability. In this specification, unless otherwise specified, phase stability refers to the state in which the main phase is Th2Zn. 17 Type and Th2Ni 17 This means whether or not at least one of the crystal structures of the type can be maintained. Good phase stability means that Th2Zn 17 Type and Th2Ni 17 This means that at least one of the crystal structures of the type can be maintained. Furthermore, poor phase stability means that Th2Zn 17 Type and Th2Ni 17 This means that it is difficult to maintain at least one of the crystal structures of the type. Figure 2 is a graph showing the relationship between the lattice constant and the saturation magnetization Ms. Figure 3 is a graph showing the relationship between the sum of the molar ratios of La x and Ce y and the anisotropic magnetic field Ha. Figure 4 is a graph showing the relationship between the molar ratio of La x and the saturation magnetization Ms when the molar ratio of Co p is 0.3.

[0105] From Table 1 and Figure 1, it can be seen that in the samples of Examples 1 to 6, the saturation magnetization was improved while suppressing the decrease in anisotropic magnetic field as much as possible. On the other hand, in the samples of Comparative Examples 1 to 14, although the phase stability was good, the saturation magnetization was not improved. Furthermore, in the samples of Comparative Examples 15 to 33, the phase stability was poor.

[0106] From Table 1 and Figure 2, it can be seen that the saturation magnetization Ms is high when the lattice constant of the main phase is between 1.4350 and 1.4460.

[0107] As shown by the dashed line in Figure 3, when a portion of Sm is replaced with La and Ce, a decrease in the anisotropic magnetic field Ha is predicted as the substitution ratio of La and Ce increases. However, from Table 1 and Figure 3, it can be seen that the samples of Examples 1 to 6 have an anisotropic magnetic field Ha higher than the anisotropic magnetic field Ha predicted from the substitution ratio of La and Ce.

[0108] From Table 1 and Figure 4, it can be seen that when the molar ratio of Co is 0.3, the decrease in the anisotropic magnetic field Ha is within a range that is not practically problematic in the samples of Examples 2 and 3, where the molar ratio x of La is 0.25 or higher.

[0109] These results confirm the effectiveness of the Sm-Fe-N magnetic material and its manufacturing method described herein.

Claims

1. Th ２ Zn １７ Type and Th ２ Ni １７ An Sm-Fe-N magnetic material comprising a main phase having at least one of the following crystal structures, The composition of the main phase is 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 and is represented by R １ is one or more rare earth elements other than Sm, La, and Ce, and Zr, and M is one or more elements other than Fe, Co, Ni, and rare earth elements, and unavoidable impurity elements, and 0.25 ≤ x + y ≤ 0.73, 0.25 ≤ x ≤ 0.73, x / (x+y)≧0.80, 0 ≤ z ≤ 0.10, 0.10 ≤ p + q ≤ 0.53, p+q≧1.45(x+y)−0.5485, 0 ≤ s ≤ 0.10, and 2.9 ≤ h ≤ 3.3 Satisfying, Sm-Fe-N magnetic material.

2. The Sm-Fe-N magnetic material according to claim 1, wherein p and q satisfy 0.22 ≤ p + q ≤ 0.

53.

3. The Sm-Fe-N magnetic material according to claim 1 or 2, wherein the lattice constant of the main phase is 1.4350 to 1.4460.

4. The Sm-Fe-N magnetic material according to claim 1 or 2, wherein the lattice volume of the main phase is 0.829 to 0.838 nm.

5. The Sm-Fe-N magnetic material according to claim 1 or 2, wherein the volume fraction of the main phase is 80 to 100%.

6. The density of the main phase is 7.40–7.76 g / cm³. ３ The Sm-Fe-N magnetic material according to claim 1 or 2.

7. A method for producing an Sm-Fe-N magnetic material according to claim 1, Mole 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 It is represented as R １ The present invention provides a magnetic material precursor having a crystalline phase that satisfies 0.25≦x+y≦0.73, 0.25≦x≦0.73, x / (x+y)≧0.80, 0≦z≦0.10, 0.10≦p+q≦0.53, p+q≧1.45(x+y)-0.5485, and 0≦s≦0.10, and Nitriding the magnetic material precursor, A method for producing an Sm-Fe-N-based magnetic material, including the material itself.

8. A method for producing an Sm-Fe-N magnetic material according to claim 7, wherein p and q satisfy 0.22 ≤ p + q ≤ 0.

53.

9. A method for producing an Sm-Fe-N-based magnetic material according to claim 7 or 8, comprising grinding the magnetic material precursor to obtain a magnetic material precursor powder, and then nitriding the magnetic material precursor powder.

10. A method for producing an Sm-Fe-N-based magnetic material according to claim 7 or 8, comprising dissolving and solidifying raw materials containing elements constituting the magnetic material precursor to obtain the magnetic material precursor.

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