Patent Publication Number: US-2020291507-A1

Title: Soft magnetic alloy and magnetic component

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a soft magnetic alloy and a magnetic component. 
     In recent years, there is a demand for higher efficiency and lower power consumption in electronic, information, and communication equipment or the like. Furthermore, the above demand is further strengthened for the realization of a low-carbon society. Therefore, there is also a demand for improvement of power supply efficiency and reduction of energy loss in a power supply circuit for the electronic, information, and communication equipment or the like. As a result, there is a demand for improvement of saturation magnetic flux density and reduction of core loss (magnetic core loss) in a magnetic core included in a magnetic component used in the power supply circuit. If the core loss is reduced, the energy loss of the power supply circuit decreases, and high efficiency and energy saving of the electronic, information, and communication equipment or the like can be achieved. 
     As one of the methods for reducing the core loss, it is effective to constitute the magnetic core with a magnetic material having high soft magnetic properties. For example, in Patent Document 1, a Fe—B-M soft magnetic alloy is disclosed. M denotes at least one element selected from Ti, Zr, Hf, V, Nb, Ta, Mo, and W.
         Patent Document 1: Japanese Patent Laid-Open No. 7-268566       

     Patent Document 1 describes that the soft magnetic properties and the saturation magnetic flux density of the soft magnetic alloy can be improved by performing a heat treatment on an amorphous metal produced by liquid phase cooling to deposit fine crystalline phase. However, it is necessary to reduce coercivity in order to improve the soft magnetic properties of the soft magnetic alloy, but reduction in the coercivity has not been sufficiently considered in Patent Document 1. 
     The coercivity is mainly derived from magnetocrystalline anisotropy and magnetoelastic effect. The coercivity derived from the magnetoelastic effect appears when stress is applied to a magnetic material having a large magnetostriction. The coercivity derived from the magnetocrystalline anisotropy can be reduced by isotropically depositing nanometer scale fine Fe-based crystal phase. 
     However, it is also necessary to reduce the magnetostriction in order to sufficiently reduce the coercivity derived from the magnetoelastic effect. In addition, in a composition region in which the content ratio of M is relatively small and the content ratio of B and P having a role of enhancing an amorphous forming ability is relatively large, an amorphous state before the heat treatment is uniform and thus fine crystals after the heat treatment are also easy to become uniform. Therefore, it is advantageous for suppressing the magnetocrystalline anisotropy, and a high saturation magnetic flux density is obtained. However, on the other hand, the magnetostriction tends to increase. As a result, there is a problem that, during the manufacturing of the magnetic component, the property deterioration due to the residual stress caused by the magnetostriction becomes remarkable. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention has been made in view of the above circumstances, and an objective thereof is to provide a soft magnetic alloy capable of achieving both low coercivity and high saturation magnetic flux density by reducing both the magnetostriction and the magnetocrystalline anisotropy. 
     Aspects of the present invention includes:
         [1] A soft magnetic alloy comprising a composition formula       

       (Fe (1−(α+β)) X1 α X2 β ) (1−a+b+c+d+e+f)) M a B b P c Si d C e Zn f ,         wherein X1 denotes at least one selected from the group consisting of Co and Ni;   X2 denotes at least one selected from the group consisting of Cu, Mg, Al, Mn, Ag, Sn, Bi, O, N, S, and rare earth elements;   M denotes at least one selected from the group consisting of Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W;   a, b, c, d, e, f, α and β satisfy the relationships of:       
       0.080≤ b≤ 0.150,
 
       0≤ c≤ 0.060,
 
       0≤ d≤ 0.060,
 
       0≤ e≤ 0.030,
 
       0.0030≤ f≤ 0.080,
 
       0.0030≤ a+f≤ 0.080,
 
         b+c≥ 0.100, 
         a≥ 0, 
       β≥0, and
 
       0≤α+β≤0.50; and
         the soft magnetic alloy has Fe-based nanocrystals with a bcc structure.       

     [2] The soft magnetic alloy according to [1], satisfying the relationships of: 
         c≤ 0.040, 
         d≤ 0.030, 
       0.010≤ f≤ 0.050, and
 
       0.010≤ a+f≤ 0.050.
 
     [3] The soft magnetic alloy according to [1] or [2], wherein an expansion value of a (110) plane spacing of the Fe-based nanocrystal with respect to a (110) plane spacing of pure iron is 0.002 angstroms or less. 
     [4] The soft magnetic alloy according to any one of [1] to [3], wherein an average grain size of the Fe-based nanocrystal is 5 nm or more and 30 nm or less. 
     [5] The soft magnetic alloy according to any one of [1] to [4] having a ribbon shape. 
     [6] The soft magnetic alloy according to any one of [1] to [4] having a powder shape. 
     [7] A magnetic component comprising the soft magnetic alloy according to any one of [1] to [4]. 
     According to the present invention, it is possible to provide a soft magnetic alloy capable of achieving both low coercivity and high saturation magnetic flux density. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter, the present invention is described in detail in the following order.
         1. Soft magnetic alloy   2. Manufacturing method for soft magnetic alloy   3. Magnetic component       

     (1. Soft Magnetic Alloy) 
     The soft magnetic alloy of the present embodiment has Fe-based nanocrystals and amorphous. The Fe-based nanocrystal is a crystal of which the crystal grain size is in the nanometer scale and which has a bcc (body-centered cubic lattice) structure. In the soft magnetic alloy, many Fe-based nanocrystals are deposited and dispersed in the amorphous. A soft magnetic alloy in which the Fe-based nanocrystals are dispersed in the amorphous is easy to exhibit high saturation magnetic flux density and low coercivity. 
     In the present embodiment, the average crystal grain size of the Fe-based nanocrystal is preferably 5 nm or more and 30 nm or less. With the average crystal grain size in the above range, it is easy to achieve low magnetostriction, high saturation magnetic flux density, and low coercivity. 
     Subsequently, the composition of the soft magnetic alloy of the present embodiment is described in detail. 
     The composition of the soft magnetic alloy of the present embodiment is represented by a composition formula (Fe (1−(α+β)) X1 α X2 β ) (1−(a+b+c+d+e+f)) M a B b P c Si d C e Zn f . 
     In the above composition formula, M denotes at least one element selected from the group consisting of Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W. 
     In addition, “a” represents the content ratio of M. In the present embodiment, “a” is determined by the relationship with “f” (described later) representing the content ratio of Zn. 
     In the above composition formula, “b” represents the content ratio of B (boron), and “b” satisfies 0.080&lt;b&lt;0.150. The content ratio (b) of B is preferably 0.130 or less. 
     In the above composition formula, “c” represents the content ratio of P (phosphorus), and “c” satisfies 0&lt;c&lt;0.060. That is, P is an optional component. The content ratio (c) of P is preferably 0.005 or more, and more preferably 0.010 or more. In addition, the content ratio (c) of P is preferably 0.040 or less. 
     In the present embodiment, the sum of the content ratios of B and P satisfies b+c≥0.100. 
     When “c” is within the above range, the coercivity tends to decrease. When “c” is too small, the above effects tend to be hardly obtained. On the other hand, when “c” is too large, the crystal grain size after the heat treatment tends to increase, and thus the coercivity tends to increase. When b+c is within the above range, homogeneity of amorphous phase during liquid phase quenching becomes high, uniform fine crystals can be obtained after the heat treatment, and thus the coercivity tends to decrease. 
     In the composition region in which the content ratios of B and P are relatively large and M is contained in a predetermined ratio, a structure is obtained in which the amorphous forming ability during liquid phase cooling of a raw material alloy is high and fine nanocrystals are deposited after the heat treatment of the alloy obtained by cooling. As a result, a soft magnetic alloy with suppressed magnetocrystalline anisotropy is obtained easily. In addition, high saturation magnetic flux density is obtained easily in a region in which the content ratio of M is relatively small. 
     However, the soft magnetic alloy having the above composition region tends to have large positive magnetostriction. As described above, the coercivity is affected by not only the magnetocrystalline anisotropy but also the magnetoelastic effect. If the magnetoelastic effect is great, that is, when the magnetostriction is large, the coercivity may not be sufficiently reduced. 
     Thus, in the present embodiment, a predetermined amount of Zn (zinc) is contained in the soft magnetic alloy. In this way, it is possible to reduce the positive magnetostriction of the soft magnetic alloy while maintaining the structure having fine nanocrystals and the high saturation magnetic flux density. In other words, the soft magnetic alloy of the present embodiment exhibits small coercivity and high saturation magnetic flux density, because both the magnetocrystalline anisotropy and the magnetoelastic effect are reduced. 
     Specifically, in the above composition formula, “f” represents the content ratio of Zn, and “f” satisfies 0.003≤f≤0.080, and “a” and “f” satisfy 0.003≤a+f≤0.080. That is, in the present embodiment, M is substituted with Zn (zinc). Zn may substitute all of M, or may substitute a part of M within the above range. 
     When “f” is too small, the magnetostriction reduction effect is small. As a result, the coercivity may not be reduced. On the other hand, when “f” is too large, the saturation magnetic flux density tends to decrease easily and the magnetostriction tends to increase. 
     In the present embodiment, “f” is preferably 0.010 or more. On the other hand, “f” is preferably 0.050 or less. In addition, a+f is preferably 0.010 or more. On the other hand, a+f is preferably 0.050 or less. 
     A mechanism in which the magnetostriction can be reduced by substituting M with Zn is not clear, but it can be inferred, for example, as follows. 
     One of the factors for the increase in magnetostriction is the expansion in the lattice spacing of bcc caused by solid-solution of M in the Fe-based nanocrystals having a bcc structure. Because Zn has an atomic radius smaller than that of the M element, the expansion of the lattice spacing of bcc can be suppressed when Zn, instead of M, is solid-soluted in the Fe-based nanocrystals. As a result, the positive magnetostriction of the Fe-based nanocrystals is considered to decrease. In addition, the lattice spacing tends to expand when Zn is added excessively, and as a result, the magnetostriction reduction effect is considered to decreases. 
     In addition to the above, because negative magnetostriction of the bcc structure is considered to increase when Zn is solid-soluted in the Fe-based nanocrystals, the positive magnetostriction of the Fe-based nanocrystals is considered to decrease thereby. 
     Moreover, similar to M, Zn also has the effect of refinement of the Fe-based nanocrystals, and thus it is possible to obtain a soft magnetic alloy of which the magnetostriction is reduced while the structure having fine nanocrystals is maintained. 
     In addition, it is preferable to suppress the solid-solution of M in bcc regardless of the presence or absence of the solid-solution of Zn in bcc. As described above, the lattice spacing of bcc expands when M is solid-soluted in bcc, and thus the expansion in the lattice spacing of bcc is preferably equal to or less than a predetermined value. 
     In the present embodiment, a (110) plane spacing of bcc is employed as the lattice spacing of bcc. Because pure iron does not contain M, M is not solid-soluted in bcc of pure iron. That is, the expansion in the plane spacing caused by the solid-solution of M in bcc does not occur. Accordingly, it means that the closer the (110) plane spacing of the soft magnetic alloy is to the (110) plane spacing of the pure iron, the lower the solid-solution ratio of M in bcc is. 
     In the present embodiment, a value obtained by subtracting the (110) plane spacing of pure iron from the (110) plane spacing of the soft magnetic alloy is defined as an expansion value of the (110) plane spacing. The expansion value of the (110) plane spacing is preferably 0.002 angstroms or less. 
     With the expansion value of the (110) plane spacing in the above range, the magnetostriction of the soft magnetic alloy can be reduced. 
     The (110) plane spacing of the soft magnetic alloy and the (110) plane spacing of pure iron can be calculated by XRD (X-Ray Diffraction) measurement. That is, the (110) plane spacing can be calculated from the angle at which a diffraction peak of the (110) plane is observed and the wavelength of X-ray. Then, the expansion value of the (110) plane spacing may be calculated based on the calculated spacing. 
     Note that, in order to reduce the influence of the inherent error of the XRD measurement device, the (110) plane spacing of the soft magnetic alloy and the (110) plane spacing of pure iron are preferably measured with the same device and under the same measurement conditions. 
     In the above composition formula, “d” represents the content ratio of Si (silicon), and “d” satisfies 0&lt;d&lt;0.060. That is, Si is an optional component. The content ratio (d) of Si is preferably 0.001 or more, and more preferably 0.005 or more. In addition, the content ratio (d) of Si is preferably 0.030 or less. 
     When “d” is within the above range, there is a tendency that the resistivity of the soft magnetic alloy is particularly easy to be improved, and the coercivity is reduced easily. On the other hand, when “d” is too large, the coercivity of the soft magnetic alloy tends to increase. 
     In the above composition formula, “e” represents the content ratio of C (carbon), and “e” satisfies 0&lt;e&lt;0.030. That is, C is an optional component. The content ratio (e) of C is preferably 0.001 or more. In addition, the content ratio (e) of C is preferably 0.015 or less. 
     When “e” is within the above range, there is a tendency that the coercivity of the soft magnetic alloy is particularly easy to be reduced. When “e” is too large, the crystal grain size tends to increase and the coercivity tends to increase. 
     In the above composition formula, 1−(a+b+c+d+e+f) represents the total content ratio of Fe (iron), X1 and X2. The total content ratio of Fe, X1 and X2 is not particularly limited as long as “a”, “b”, “c”, “d”, “e” and “f” are within the above ranges. In the present embodiment, the total content ratio (1−(a+b+c+d+e+f)) is preferably 0.73 or more and 0.95 or less. With the total content ratio set to 0.73 or more, high saturation magnetic flux density is obtained easily. In addition, with the total content ratio set to 0.95 or less, crystal phase configured by crystals having a grain size larger than 30 nm is hardly generated. As a result, a soft magnetic alloy in which the Fe-based nanocrystals are deposited by heat treatment tends to be obtained easily. 
     X1 denotes at least one element selected from the group consisting of Co and Ni. In the above composition formula, “a” represents the content ratio of X1, and “α” is 0 or more in the present embodiment. That is, X1 is an optional component. 
     In addition, when the total number of atoms of the composition is set to 100 at %, the number of atoms of X1 is preferably 40 at % or less. That is, it is preferable to satisfy 0≤a {1−(a+b+c+d+e+f)}≤0.40. 
     X2 denotes at least one element selected from the group consisting of Cu, Mg, Al, Mn, Ag, Sn, Bi, O, N, S, and rare earth elements. In the above composition formula, “0” represents the content ratio of X2, and “β” is 0 or more in the present embodiment. That is, X2 is an optional component. 
     In addition, when the total number of atoms of the composition is set to 100 at %, the number of atoms of X2 is preferably 3.0 at % or less. That is, it is preferable to satisfy 0≤β{1−(a+b+c+d+e+f)}≤0.030. 
     Furthermore, the range (substitution ratio) in which X1 and/or X2 substitutes for Fe is set equal to or less than half of the total number of Fe atoms in terms of the number of atoms. That is, 0≤α+β≤0.50 is satisfied. When α+β is too large, it tends to be difficult to obtain a soft magnetic alloy in which the Fe-based nanocrystals are deposited by heat treatment. 
     Note that, the soft magnetic alloy of the present embodiment may include elements other than the above elements as inevitable impurities. For example, the elements other than the above elements may be included in a total of 0.1% by mass or less with respect to 100% by mass of the soft magnetic alloy. 
     (2. Manufacturing Method of Soft Magnetic Alloy) 
     Subsequently, a method for manufacturing the soft magnetic alloy is described. The soft magnetic alloy of the present embodiment is manufactured by, for example, depositing Fe-based nanocrystals in an amorphous alloy having the above composition. 
     As the method for obtaining the amorphous alloy, for example, a method of quenching a molten metal to obtain an amorphous alloy is exemplified. In the present embodiment, a ribbon or flake of the amorphous alloy may be obtained by a single roll method, or powder of the amorphous alloy may be obtained by an atomization method. Hereinafter, a method of obtaining the amorphous alloy by the single roll method and a method of obtaining the amorphous alloy by a gas atomization method as an example of the atomization method are described. 
     In the single roll method, first, a raw material (pure metal or the like) of each metal element contained in the soft magnetic alloy is prepared and is weighed so as to obtain a composition of the finally obtained soft magnetic alloy, and the raw material is melted to obtain molten metal. Note that, the method for melting the raw material of the metal elements is not particularly limited; for example, a method of melting the material by high-frequency heating in a predetermined atmosphere is exemplified. The temperature of the molten metal may be determined in consideration of the melting point of each metal element and may be, for example, 1200-1500° C. 
     Next, for example, inside a chamber filled with an inert gas, the molten metal is injected and supplied from a nozzle to a cooled rotary roll, and thereby a ribbon-shaped or flaky amorphous alloy is manufactured toward the rotating direction of the rotary roll. Examples of the material of the rotary roll include copper. The temperature of the rotary roll, the rotating speed of the rotary roll, the atmosphere inside the chamber, and the like may be determined corresponding to the conditions under which the Fe-based nanocrystals are easily deposited in the amorphous during the heat treatment described later. 
     In the gas atomization method, similar to the single roll method, first, molten metal is obtained in which the raw material of the soft magnetic alloy is melted. The temperature of the molten metal may be determined in consideration of the melting point of each metal element as in the case of the single roll method, and may be, for example, 1200-1500° C. 
     The obtained molten metal is supplied into the chamber as a linear continuous fluid through a nozzle provided at the bottom of the crucible, and a high-pressure gas is sprayed onto the supplied molten metal to make the molten metal into droplets, and the droplets are quenched to obtain a powder-shaped amorphous alloy. The gas injection temperature, the pressure in the chamber, and the like may be determined corresponding to the conditions under which the Fe-based nanocrystals are easily deposited in the amorphous during the heat treatment described later. In addition, the particle size can be adjusted by sieving classification, airflow classification, or the like. 
     The ribbon and powder obtained by the above methods are configured by an amorphous alloy. The amorphous alloy may be an amorphous alloy in which fine crystals are dispersed in an amorphous, or may be an alloy not containing crystals. 
     Next, the obtained ribbon and powder are subjected to a heat treatment (first heat treatment). By performing the first heat treatment, diffusion of the elements constituting the soft magnetic alloy can be promoted, a thermodynamic equilibrium state can be achieved in a short time, and strain or stress existing in the soft magnetic alloy can be removed. As a result, it becomes easy to obtain a soft magnetic alloy in which the Fe-based nanocrystals are deposited. 
     In the present embodiment, the condition of the first heat treatment is not particularly limited as long as the Fe-based nanocrystals are easily deposited under this condition. In the case of ribbon, for example, the heat treatment temperature can be set to 400-700° C., and the holding time can be set to 0.5-10 hours. 
     In the present embodiment, it is preferable to further perform a heat treatment (second heat treatment) after the first heat treatment. By performing the second heat treatment, M solid-soluted in the Fe-based nanocrystals can be released out of the crystals. In the case of a composition containing a relatively large amount of Zn, excessively solid-soluted Zn can be released out of the crystals and the amount of solid-solution Zn in the crystals can be optimized. As a result, the (110) plane spacing of the Fe-based nanocrystal decreases and gets close to the (110) plane spacing of pure iron, and thus the magnetostriction can be reduced. 
     The heat treatment temperature of the second heat treatment is preferably lower than the heat treatment temperature of the first heat treatment, and more preferably lower by 50° C. or more. In addition, the holding time of the second heat treatment is preferably three hours or longer and ten hours or shorter. 
     After the above heat treatment, the soft magnetic alloy of the present embodiment having a ribbon shape or the soft magnetic alloy of the present embodiment having a powder shape is obtained. 
     In addition, there is no particular limitation on the calculation method of the average grain size of the Fe-based nanocrystals contained in the soft magnetic alloy obtained by the heat treatment. For example, the calculation can be made by a transmission electron microscope observation. In addition, there is no particular limitation on a method for confirming that the crystal structure is a bcc (body-centered cubic lattice) structure. For example, the confirmation can be made using X-ray diffraction measurement. 
     (3. Magnetic Component) 
     The magnetic component of the present embodiment is not particularly limited as long as this magnetic component includes the above soft magnetic alloy as a magnetic material. For example, the magnetic component may have a magnetic core configured by the above soft magnetic alloy. 
     Examples of the method for obtaining a magnetic core from the ribbon-shaped soft magnetic alloy include a method of winding the ribbon-shaped soft magnetic alloy or a method of laminating the ribbon-shaped soft magnetic alloy. When the ribbon-shaped soft magnetic alloy is laminated via an insulator during the lamination, a magnetic core with further improved properties can be obtained. 
     Examples of the method for obtaining a magnetic core from the powder-shaped soft magnetic alloy include a method in which the powder-shaped soft magnetic alloy is appropriately mixed with a binder and then molded using a press mold. In addition, by applying an oxidation treatment, an insulating coating or the like on the powder surface before the mixture with the binder, the magnetic core has an improved resistivity and is adapted to higher frequency regions. 
     The magnetic component of the present embodiment is suitable for a power inductor used in a power supply circuit. In addition, applications of the magnetic core include, in addition to the inductor, a transformer, a motor, and the like. 
     The present embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment and may be modified in various aspects within the scope of the present invention. 
     EXAMPLES 
     Hereinafter, the present invention is described in more detail with reference to examples, but the present invention is not limited to these examples. 
     Examples 1-21 and Comparative Examples 1-10 
     First, raw metal of the soft magnetic alloy was prepared. The prepared raw metal was weighed so as to satisfy the composition shown in Table 1 and was melted by high-frequency heating to prepare a mother alloy. 
     Then, the prepared mother alloy was heated and melted to obtain molten metal having a melting temperature of 1250° C. The molten metal was sprayed on a rotary roll by a single roll method to form a ribbon. Note that, the material of the rotary roll was Cu. In addition, the standard rotating speed of the rotary roll was 25 m/sec. By adjusting the roll rotating speed, the thickness of the obtained ribbon was set to 20 μm-30 μm, the width of the ribbon was set to 4 mm-5 mm, and the length of the ribbon was set to tens of meters. 
     As a result of performing X-ray diffraction measurement on each of the obtained ribbons, in all the examples, the ribbon had an amorphous or a nanohetero-structure in which initial fine crystals exist in the amorphous. 
     Then, the ribbons of Examples 1-21 and Comparative Examples 1-10 were subjected to heat treatment at a heat treatment temperature of 550° C. and for a holding time of one hour. As a result of the X-ray diffraction measurement and the transmission electron microscope observation performed on the ribbon after the heat treatment, in all the examples, it was confirmed that the ribbon after the heat treatment had Fe-based nanocrystals of which the crystal structure was bcc and the average crystal grain size of the Fe-based nanocrystals was 5-30 nm. In addition, it was confirmed by ICP analysis that there was no change in the alloy composition before and after the heat treatment. 
     The magnetostriction, saturation magnetic flux density, and coercivity were measured for each ribbon after the heat treatment. The magnetostriction was measured by a strain gauge method. The saturation magnetic flux density (Bs) was measured using a vibrating sample magnetometer (VSM) at a magnetic field of 1000 kA/m. The coercivity (Hc) was measured using a direct current BH tracer at a magnetic field of 5 kA/m. 
     Regarding the magnetostriction, a sample in which the absolute value of magnetostriction is 2.50 ppm or less was judged to be good. A sample in which the absolute value of magnetostriction is 1.50 ppm or less is more preferable. Regarding the saturation magnetic flux density, a sample in which the saturation magnetic flux density was 1.40 T or more was judged to be good. A sample in which the saturation magnetic flux density is 1.60 T or more was more preferable. Regarding the coercivity, a sample in which the coercivity is 2.0 A/m or less was judged to be good. A sample in which the coercivity is 1.5 A/m or less is more preferable. The results are shown in Table 1. 
     The value of the coercivity measured as described above includes both a component derived from the magnetocrystalline anisotropy and a component derived from the magnetoelastic effect caused by the magnetostriction. The component derived from the magnetoelastic effect is the product of the magnetostriction and the stress and thus cannot be detected as coercivity when the internal stress is not applied to the sample. Accordingly, it is necessary to confirm that both the coercivity and the magnetostriction show a low value and the saturation magnetic flux density shows a high value, in order to determine whether the effect of the present invention exists. 
     In view of the situation described above, in Table 1 and Tables 2-4 described later, as shown below, scores corresponding to the measured property values were allocated to each sample, and the superiority of the samples was comprehensively evaluated according to the numerical value of the product of the scores. The results are shown in a column of comprehensive evaluation. 
     With respect to each sample, zero point was allocated when the magnetostriction is greater than 2.50 ppm, one point was allocated when the magnetostriction is greater than 1.50 ppm and equal to or lower than 2.50 ppm, and two points were allocated when the magnetostriction is 1.50 ppm or less. With respect to each sample, zero point was allocated when the saturation magnetic flux density is less than 1.40 T, one point was allocated when the saturation magnetic flux density is 1.40 T or more and less than 1.60 T, and two points were allocated when the saturation magnetic flux density is 1.60 T or more. With respect to each sample, zero point was allocated when the coercivity is greater than 2.0 A/m, one point was allocated when the coercivity is greater than 1.5 A/m and equal to or lower than 2.0 A/m, and two points were allocated when the coercivity is 1.5 A/m or less. Then, the product of the allocated numerical values was calculated and a sample in which the numerical value of the product was equal to or greater than 1 was judged to be good. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 1 
               
             
            
               
                   
                   
               
               
                   
                 Soft magnetic alloy 
                 Property 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Fe (1−a−b−c−d−e−f) M a B b P c Si d C e Zn f □α 
                   
                 Saturation 
                   
               
            
           
           
               
               
               
               
               
               
            
               
                   
                 = β = 0 
                 Magneto- 
                 magnetic flux 
                 Coer- 
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 Fe 
                   
                   
                   
                   
                   
                   
                   
                   
                 striction 
                 density 
                 civity 
                 Compre- 
               
               
                   
                 1 − a − b − c − 
                 B 
                 P 
                 Si 
                 C 
                 M 
                 Zn 
                   
                   
                 λ 
                 Bs 
                 Hc 
                 hensive 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 d − e − f 
                 b 
                 c 
                 d 
                 e 
                 Element 
                 a 
                 f 
                 a + f 
                 b + c 
                 (×10 −6 ) 
                 (T) 
                 (A/m) 
                 evaluation 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                 Example 1 
                 0.830 
                 0.120 
                 0.000 
                 0.000 
                 0.000 
                 — 
                 0.000 
                 0.050 
                 0.050 
                 0.120 
                 1.13 
                 1.63 
                 1.7 
                 4 
               
               
                 Example 2 
                 0.850 
                 0.120 
                 0.000 
                 0.000 
                 0.000 
                 — 
                 0.000 
                 0.030 
                 0.030 
                 0.120 
                 0.63 
                 1.72 
                 1.5 
                 8 
               
               
                 Example 3 
                 0.860 
                 0.130 
                 0.000 
                 0.000 
                 0.000 
                 — 
                 0.000 
                 0.010 
                 0.010 
                 0.130 
                 0.97 
                 1.74 
                 1.8 
                 4 
               
               
                 Example 4 
                 0.830 
                 0.120 
                 0.000 
                 0.000 
                 0.000 
                 Nb 
                 0.020 
                 0.030 
                 0.050 
                 0.120 
                 1.40 
                 1.65 
                 1.0 
                 8 
               
               
                 Example 5 
                 0.850 
                 0.120 
                 0.000 
                 0.000 
                 0.000 
                 Nb 
                 0.010 
                 0.020 
                 0.030 
                 0.120 
                 0.85 
                 1.70 
                 1.2 
                 8 
               
               
                 Example 6 
                 0.847 
                 0.150 
                 0.000 
                 0.000 
                 0.000 
                 — 
                 0.000 
                 0.003 
                 0.003 
                 0.150 
                 2.39 
                 1.63 
                 1.8 
                 2 
               
               
                 Example 7 
                 0.820 
                 0.100 
                 0.000 
                 0.000 
                 0.000 
                 — 
                 0.000 
                 0.080 
                 0.080 
                 0.100 
                 1.72 
                 1.48 
                 1.7 
                 1 
               
               
                 Example 8 
                 0.820 
                 0.100 
                 0.000 
                 0.000 
                 0.000 
                 Nb 
                 0.040 
                 0.040 
                 0.080 
                 0.100 
                 1.59 
                 1.43 
                 1.3 
                 2 
               
               
                 Example 9 
                 0.840 
                 0.090 
                 0.040 
                 0.000 
                 0.000 
                 — 
                 0.000 
                 0.030 
                 0.030 
                 0.130 
                 0.89 
                 1.65 
                 1.3 
                 8 
               
               
                 Example 10 
                 0.830 
                 0.080 
                 0.060 
                 0.000 
                 0.000 
                 — 
                 0.000 
                 0.030 
                 0.030 
                 0.140 
                 2.33 
                 1.55 
                 1.1 
                 2 
               
               
                 Example 11 
                 0.840 
                 0.100 
                 0.000 
                 0.030 
                 0.000 
                 — 
                 0.000 
                 0.030 
                 0.030 
                 0.100 
                 1.46 
                 1.70 
                 1.3 
                 8 
               
               
                 Example 12 
                 0.810 
                 0.100 
                 0.000 
                 0.060 
                 0.000 
                 — 
                 0.000 
                 0.030 
                 0.030 
                 0.100 
                 2.43 
                 1.57 
                 1.1 
                 2 
               
               
                 Example 13 
                 0.840 
                 0.100 
                 0.000 
                 0.000 
                 0.030 
                 — 
                 0.000 
                 0.030 
                 0.030 
                 0.100 
                 1.05 
                 1.71 
                 1.3 
                 8 
               
               
                 Example 14 
                 0.830 
                 0.120 
                 0.000 
                 0.000 
                 0.000 
                 Ti 
                 0.020 
                 0.030 
                 0.050 
                 0.120 
                 1.41 
                 1.64 
                 1.5 
                 8 
               
               
                 Example 15 
                 0.830 
                 0.120 
                 0.000 
                 0.000 
                 0.000 
                 V 
                 0.020 
                 0.030 
                 0.050 
                 0.120 
                 1.47 
                 1.62 
                 1.3 
                 8 
               
               
                 Example 16 
                 0.830 
                 0.120 
                 0.000 
                 0.000 
                 0.000 
                 Cr 
                 0.020 
                 0.030 
                 0.050 
                 0.120 
                 1.99 
                 1.62 
                 1.5 
                 4 
               
               
                 Example 17 
                 0.830 
                 0.120 
                 0.000 
                 0.000 
                 0.000 
                 Zr 
                 0.020 
                 0.030 
                 0.050 
                 0.120 
                 1.39 
                 1.60 
                 0.8 
                 8 
               
               
                 Example 18 
                 0.830 
                 0.120 
                 0.000 
                 0.000 
                 0.000 
                 Mo 
                 0.020 
                 0.030 
                 0.050 
                 0.120 
                 1.80 
                 1.60 
                 1.2 
                 4 
               
               
                 Example 19 
                 0.830 
                 0.120 
                 0.000 
                 0.000 
                 0.000 
                 Hf 
                 0.020 
                 0.030 
                 0.050 
                 0.120 
                 1.74 
                 1.61 
                 0.8 
                 4 
               
               
                 Example 20 
                 0.830 
                 0.120 
                 0.000 
                 0.000 
                 0.000 
                 Ta 
                 0.020 
                 0.030 
                 0.050 
                 0.120 
                 1.68 
                 1.60 
                 1.0 
                 4 
               
               
                 Example 21 
                 0.830 
                 0.120 
                 0.000 
                 0.000 
                 0.000 
                 W 
                 0.020 
                 0.030 
                 0.050 
                 0.120 
                 1.55 
                 1.63 
                 1.3 
                 4 
               
               
                 Comparative 
                 0.820 
                 0.100 
                 0.000 
                 0.000 
                 0.000 
                 Nb 
                 0.080 
                 0.000 
                 0.080 
                 0.100 
                 2.78 
                 1.38 
                 0.7 
                 0 
               
               
                 Example 1 
               
               
                 Comparative 
                 0.830 
                 0.120 
                 0.000 
                 0.000 
                 0.000 
                 Nb 
                 0.050 
                 0.000 
                 0.050 
                 0.120 
                 8.01 
                 1.55 
                 1.4 
                 0 
               
               
                 Example 2 
               
               
                 Comparative 
                 0.850 
                 0.120 
                 0.000 
                 0.000 
                 0.000 
                 Nb 
                 0.030 
                 0.000 
                 0.030 
                 0.120 
                 4.61 
                 1.66 
                 1.7 
                 0 
               
               
                 Example 3 
               
               
                 Comparative 
                 0.860 
                 0.130 
                 0.000 
                 0.000 
                 0.000 
                 Nb 
                 0.010 
                 0.000 
                 0.010 
                 0.130 
                 2.65 
                 1.71 
                 1.9 
                 0 
               
               
                 Example 4 
               
               
                 Comparative 
                 0.790 
                 0.120 
                 0.000 
                 0.000 
                 0.000 
                 — 
                 0.000 
                 0.090 
                 0.090 
                 0.120 
                 3.88 
                 1.32 
                 2.4 
                 0 
               
               
                 Example 5 
               
               
                 Comparative 
                 0.848 
                 0.150 
                 0.000 
                 0.000 
                 0.000 
                 — 
                 0.000 
                 0.002 
                 0.002 
                 0.150 
                 2.82 
                 1.65 
                 4.5 
                 0 
               
               
                 Example 6 
               
               
                 Comparative 
                 0.790 
                 0.120 
                 0.000 
                 0.000 
                 0.000 
                 Nb 
                 0.050 
                 0.040 
                 0.090 
                 0.120 
                 5.32 
                 1.45 
                 1.4 
                 0 
               
               
                 Example 7 
               
               
                 Comparative 
                 0.880 
                 0.090 
                 0.000 
                 0.000 
                 0.000 
                 — 
                 0.000 
                 0.030 
                 0.030 
                 0.090 
                 0.60 
                 1.68 
                 135 
                 0 
               
               
                 Example 8 
               
               
                 Comparative 
                 0.810 
                 0.160 
                 0.000 
                 0.000 
                 0.000 
                 — 
                 0.000 
                 0.030 
                 0.030 
                 0.160 
                 4.03 
                 1.61 
                 78 
                 0 
               
               
                 Example 9 
               
               
                 Comparative 
                 0.870 
                 0.070 
                 0.030 
                 0.000 
                 0.000 
                 — 
                 0.000 
                 0.030 
                 0.030 
                 0.100 
                 0.70 
                 1.64 
                 23 
                 0 
               
               
                 Example 10 
               
               
                   
               
            
           
         
       
     
     From Table 1, it was confirmed that the numerical value of the product is equal to or greater than 1 when the content ratios of boron and zinc, the total content ratio of M and zinc, and the total content ratio of boron and phosphorus are within the above-described range. In particular, it was confirmed that the numerical value of the product is equal to or greater than 4 and particularly good properties are obtained when the content ratio of zinc, the total content ratio of M and zinc, the content ratio of phosphorus, and the content ratio of silicon are within the preferable range described above. 
     On the contrary, it was confirmed that when zinc is not contained (Comparative Examples 1-4), the magnetostriction is large and the above effect is not obtained even if the other content ratios are within the above ranges. In addition, it was confirmed that when the content ratio of zinc is too large (Comparative Example 5) and too small (Comparative Example 6), the magnetostriction is also large and the above effect is not obtained either. 
     In addition, it was confirmed that when the total content ratio of M and zinc is too large (Comparative Example 7), the magnetostriction is large and the above effect is not obtained. 
     Furthermore, it was confirmed that when the sum of the content ratios of boron and phosphorus (b+c) is too small (Comparative Example 8) and when the content ratio of boron is too small even if b+c is within the above range (Comparative Example 10), the coarse grain growth of initial fine crystals occurs during the heat treatment and thus the coercivity increases. In addition, it was confirmed that when the content ratio of boron is too large (Comparative Example 9), the magnetostriction increases and the coercivity increases due to the generation of an iron-boron compound such as Fe 3 B or the like. 
     Examples 22-34 
     Except that the “X1” and “X2” elements in the composition formula and the content ratios in the sample of Example 4 were set to the elements and the content ratios shown in Table 2, the soft magnetic alloy was produced in the same manner as in Example 4, and the same evaluation as in Example 4 was performed. The results are shown in Table 2. 
     
       
         
           
               
               
             
               
                   
                 TABLE 2 
               
             
            
               
                   
                   
               
               
                   
                 Property 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Soft magnetic alloy 
                   
                 Saturation 
                   
               
            
           
           
               
               
               
               
               
               
            
               
                   
                 (Fe (1−α−β) X1 α X2 β ) (1−a−b−c−d−e−f) M a B b P c Si d C e Zn f   
                 Magneto- 
                 magnetic flux 
                 Coer- 
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 X1 
                 X2 
                 striction 
                 density 
                 civity 
                 Compre- 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                   
                   
                 α (1 − a − b − c − 
                   
                 β (1 − α − b − c − 
                 λ 
                 Bs 
                 Hc 
                 hensive 
               
               
                   
                 element 
                 d − e − f) 
                 element 
                 d − e − f) 
                 (×10 −6 ) 
                 (T) 
                 (A/m) 
                 evaluation 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Example 22 
                 Co 
                 0.1 
                 — 
                 — 
                 1.42 
                 1.69 
                 1.7 
                 4 
               
               
                 Example 23 
                 Co 
                 0.4 
                 — 
                 — 
                 1.48 
                 1.74 
                 1.9 
                 4 
               
               
                 Example 24 
                 Ni 
                 0.1 
                 — 
                 — 
                 1.69 
                 1.66 
                 1.5 
                 4 
               
               
                 Example 25 
                 Ni 
                 0.4 
                 — 
                 — 
                 2.28 
                 1.56 
                 1.5 
                 4 
               
               
                 Example 26 
                 — 
                 — 
                 Cu 
                 0.008 
                 1.37 
                 1.72 
                 1.7 
                 4 
               
               
                 Example 27 
                 — 
                 — 
                 Mg 
                 0.03 
                 1.33 
                 1.66 
                 1.7 
                 4 
               
               
                 Example 28 
                 — 
                 — 
                 Al 
                 0.03 
                 1.48 
                 1.65 
                 1.8 
                 4 
               
               
                 Example 29 
                 — 
                 — 
                 Mn 
                 0.03 
                 1.49 
                 1.58 
                 1.5 
                 4 
               
               
                 Example 30 
                 — 
                 — 
                 Ag 
                 0.012 
                 1.55 
                 1.67 
                 1.4 
                 4 
               
               
                 Example 31 
                 — 
                 — 
                 Sn 
                 0.03 
                 1.22 
                 1.62 
                 1.5 
                 8 
               
               
                 Example 32 
                 — 
                 — 
                 Bi 
                 0.03 
                 1.40 
                 1.61 
                 1.6 
                 4 
               
               
                 Example 33 
                 — 
                 — 
                 Y 
                 0.03 
                 1.43 
                 1.59 
                 1.4 
                 4 
               
               
                 Example 34 
                 — 
                 — 
                 La 
                 0.03 
                 1.44 
                 1.52 
                 1.3 
                 4 
               
               
                   
               
            
           
         
       
     
     From Table 2, it was confirmed that good properties are obtained even when the element and the content ratios of the X1 element and the X2 element are changed. 
     Examples 35-38 
     Except that the heat treatment (second heat treatment) was performed under the conditions shown in Table 3 after the heat treatment (first heat treatment) performed at 550° C. for one hour for the sample of Example 8, the soft magnetic alloy was produced in the same manner as in Example 8. For the obtained soft magnetic alloy, in addition to the same evaluation as in Example 8, the (110) plane spacing was calculated. 
     The (110) plane spacing was calculated from 20 of the strongest peak belonging to the (110) plane among the diffraction peaks obtained by the XRD measurement and the wavelength of the measurement X-ray. In addition, for the sample of pure iron, the (110) plane spacing was calculated under the condition under which the above XRD measurement was performed using the same device as that used for the above XRD measurement. By subtracting the obtained spacing value of the (110) plane of pure iron from the obtained spacing value of the (110) plane of the soft magnetic alloy, the expansion values of the (110) plane spacing in the samples of Example 8 and Examples 35-38 were obtained. The results are shown in Table 3. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 3 
               
             
            
               
                   
                   
               
               
                   
                 Fe 0.820 Nb 0.040 B 0.100 Zn 0.040  α = β = 0 c = d = e = 0 
                   
               
            
           
           
               
               
               
            
               
                   
                 Fe-based 
                   
               
               
                   
                 nanocrystal 
                 Property 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 Heat treatment condition 
                   
                 Expansion 
                   
                 Saturation 
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                 Second heat 
                 Average 
                 of 110 
                 Magneto- 
                 magnetic flux 
                 Coer- 
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                   
                 First heat treatment 
                 treatment 
                 grain 
                 plane 
                 striction 
                 density 
                 civity 
                 Compre- 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 Temperature 
                 Time 
                 Temperature 
                 Time 
                 size 
                 spacing 
                 λ 
                 Bs 
                 Hc 
                 hensive 
               
               
                   
                 (° C.) 
                 (h) 
                 (° C.) 
                 (h) 
                 (nm) 
                 (Å) 
                 (×10 −6 ) 
                 (T) 
                 (A/m) 
                 evaluation 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                 Example 8 
                 550 
                 1 
                 — 
                 0 
                 26 
                 0.0029 
                 1.59 
                 1.43 
                 1.3 
                 2 
               
               
                 Example 35 
                 550 
                 0.25 
                 450 
                 1 
                 25 
                 0.0026 
                 1.54 
                 1.66 
                 1.7 
                 2 
               
               
                 Example 36 
                 550 
                 0.25 
                 450 
                 3 
                 24 
                 0.0020 
                 1.18 
                 1.64 
                 1.8 
                 4 
               
               
                 Example 37 
                 550 
                 0.25 
                 450 
                 5 
                 26 
                 0.0016 
                 0.98 
                 1.66 
                 1.7 
                 4 
               
               
                 Example 38 
                 550 
                 0.25 
                 450 
                 10 
                 27 
                 0.0005 
                 0.79 
                 1.67 
                 1.8 
                 4 
               
               
                   
               
            
           
         
       
     
     From Table 3, it was confirmed that the expansion value of the (110) plane spacing decreases due to the heat treatment at a lower temperature than that in the first heat treatment and the magnetostriction also decreases accordingly. Furthermore, it was confirmed that the expansion value of the (110) plane spacing decreases when the holding time of the second heat treatment is prolonged and the magnetostriction also decreases accordingly. 
     Examples 39-43 
     Except that the heat treatment conditions in the sample of Example 4 were changed to those shown in Table 4, the soft magnetic alloy was produced in the same manner as in Example 4, and the same evaluation as in Example 4 was performed. The results are shown in Table 4. 
     
       
         
           
               
               
             
               
                   
                 TABLE 4 
               
             
            
               
                   
                   
               
               
                   
                 Property 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Fe 0.830 Nb 0.020 B 0.120 Zn 0.030  α = β = 0 c = d = e = 0 
                   
                 Saturation 
                   
               
            
           
           
               
               
               
               
               
               
            
               
                   
                 Fe-based 
                 Magneto- 
                 magnetic flux 
                 Coer- 
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 Heat treatment condition 
                 nanocrystal 
                 striction 
                 density 
                 civity 
                 Compre- 
               
               
                   
                 First heat treatment 
                 Average grain size 
                 λ 
                 Bs 
                 Hc 
                 hensive 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                 Temperature (° C.) 
                 Time (h) 
                 (nm) 
                 (×10 −6 ) 
                 (T) 
                 (A/m) 
                 evaluation 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 Example 39 
                 400 
                 1 
                 3 
                 2.37 
                 1.41 
                 0.8 
                 2 
               
               
                 Example 40 
                 450 
                 1 
                 5 
                 1.49 
                 1.60 
                 1.0 
                 8 
               
               
                 Example 41 
                 500 
                 1 
                 21 
                 1.47 
                 1.62 
                 1.1 
                 8 
               
               
                 Example 4 
                 550 
                 1 
                 27 
                 1.40 
                 1.65 
                 1.0 
                 8 
               
               
                 Example 42 
                 600 
                 1 
                 30 
                 1.42 
                 1.69 
                 1.5 
                 8 
               
               
                 Example 43 
                 650 
                 1 
                 32 
                 1.39 
                 1.69 
                 1.9 
                 4 
               
               
                   
               
            
           
         
       
     
     From Table 4, it was confirmed that good properties are obtained when the average grain size of the Fe-based nanocrystals is within the above range.