Patent Application
20190221341
The present invention relates to a soft magnetic alloy and a magnetic device.
Low power consumption and high efficiency have been demanded in electronic, information, communication equipment, and the like. Moreover, the above demands are becoming stronger for a low carbon society. Thus, reduction in energy loss and improvement in power supply efficiency are also required for power supply circuits of electronic, information, communication equipment, and the like. Then, improvement in saturation magnetic flux density and permeability and reduction in core loss (magnetic core loss) are required for the magnetic core of the magnetic element used in the power supply circuit. The reduction in core loss reduces the loss of power energy, and the improvement in permeability downsizes a magnetic element. Thus, high efficiency and energy saving are achieved.
Patent Document 1 discloses a Fe—B-M based soft magnetic amorphous alloy (M=Ti, Zr, Hf, V, Nb, Ta, Mo, and W). This soft magnetic amorphous alloy has favorable soft magnetic properties, such as a high saturation magnetic flux density, compared to a saturation magnetic flux density of a commercially available Fe based amorphous material.
Patent Document 1: JP3342767 (B2)
As a method of reducing the core loss of the magnetic core, it is conceivable to reduce coercivity of a magnetic material constituting the magnetic core.
Patent Document 1 discloses that soft magnetic characteristics can be improved by depositing fine crystal phases in the Fe based soft magnetic alloy. However, Patent Document 1 does not sufficiently examine a composition where fine crystal phases can stably be deposited.
The present inventors have studied a composition where fine crystal phases can stably be deposited. As a result, the present inventors have found that fine crystal phases can stably be deposited even in a composition that is different from the composition disclosed in Patent Document 1.
It is an object of the invention to provide a soft magnetic alloy having a high saturation magnetic flux density and a low coercivity at the same time and further having an improved surface nature.
To achieve the above object, a soft magnetic alloy according to the first aspect of the present invention includes a main component of (Fe(1-(α+β))X1αX2β)(1-(a+b+c+d+e+f+g))MaBbPcSidCeSfTig, in which
X1 is one or more of Co and Ni,
X2 is one or more of Al, Mn, Ag, Zn, Sn, As, Sb, Cu, Cr, Bi, N, O, and rare earth elements,
M is one or more of Nb, Hf, Zr, Ta, Mo, W, and V,
0.020≤a≤0.14 is satisfied,
0.020<b≤0.20 is satisfied,
0.040<c≤0.15 is satisfied,
0≤d≤0.060 is satisfied,
0≤e≤0.030 is satisfied,
0≤f≤0.010 is satisfied,
0≤g≤0.0010 is satisfied,
α≥0 is satisfied,
β≥0 is satisfied,
0≤α+β≤0.50 is satisfied, and
at least one or more of f and g are larger than zero,
wherein the soft magnetic alloy has a nanohetero structure where initial fine crystals exist in an amorphous phase.
To achieve the above object, a soft magnetic alloy according to the second aspect of the present invention includes a main component of (Fe(1-(α+β))X1αX2β)(1-(a+b+c+d+e+f+g))MaBbPcSidCeSfTig, in which
X1 is one or more of Co and Ni,
X2 is one or more of Al, Mn, Ag, Zn, Sn, As, Sb, Cu, Cr, Bi, N, O, and rare earth elements,
M is one or more of Nb, Hf, Zr, Ta, Mo, W, and V,
0.020≤a≤0.14 is satisfied,
0.020<b≤0.20 is satisfied,
0<c≤0.40 is satisfied,
0≤d≤0.060 is satisfied,
0.0005<e<0.0050 is satisfied,
0≤f≤0.010 is satisfied,
0≤g≤0.0010 is satisfied,
α≥0 is satisfied,
β≥0 is satisfied,
0≤α+β≤0.50 is satisfied, and
at least one or more of f and g are larger than zero,
wherein the soft magnetic alloy has a nanohetero structure where initial fine crystals exist in an amorphous phase.
In the soft magnetic alloy according to the first and second aspects of the present invention, the initial fine crystals may have an average grain size of 0.3 to 10 nm.
To achieve the above object, a soft magnetic alloy according to the third aspect of the present invention includes a main component of (Fe(1-(α+β))X1αX2β)(1-(a+b+c+d+e+f+g))MaBbPcSidCeSfTig, in which
X1 is one or more of Co and Ni,
X2 is one or more of Al, Mn, Ag, Zn, Sn, As, Sb, Cu, Cr, Bi, N, O, and rare earth elements,
M is one or more of Nb, Hf, Zr, Ta, Mo, W, and V,
0.020≤a≤0.14 is satisfied,
0.020<b≤0.20 is satisfied,
0.040<c≤0.15 is satisfied,
0≤d≤0.060 is satisfied,
0≤e≤0.030 is satisfied,
0≤f≤0.010 is satisfied,
0≤g≤0.0010 is satisfied,
α≥0 is satisfied,
β≥0 is satisfied,
0≤α+β≤0.50 is satisfied, and
at least one or more of f and g are larger than zero,
wherein the soft magnetic alloy has a structure of Fe based nanocrystallines.
To achieve the above object, a soft magnetic alloy according to the fourth aspect of the present invention includes a main component of (Fe(1-(α+β))X1αX2β)(1-(a+b+c+d+e+f+g))MaBbPcSidCeSfTig, in which
X1 is one or more of Co and Ni,
X2 is one or more of Al, Mn, Ag, Zn, Sn, As, Sb, Cu, Cr, Bi, N, O, and rare earth elements,
M is one or more of Nb, Hf, Zr, Ta, Mo, W, and V,
0.020≤a≤0.14 is satisfied,
0.020<b≤0.20 is satisfied,
0<c≤0.040 is satisfied,
0≤d≤0.060 is satisfied,
0.0005<e<0.0050 is satisfied,
0≤f≤0.010 is satisfied,
0≤g≤0.0010 is satisfied,
α≥0 is satisfied,
β≥0 is satisfied,
0≤α+β≤0.50 is satisfied, and
at least one or more of f and g are larger than zero,
wherein the soft magnetic alloy has a structure of Fe based nanocrystallines.
In the soft magnetic alloy according to the third and fourth aspects of the present invention, the Fe based nanocrystallines may have an average grain size of 5 to 30 nm.
Since the soft magnetic alloy according to the first aspect of the present invention has the above features, the soft magnetic alloy according to the third aspect of the present invention is easily obtained by heat treatment. Since the soft magnetic alloy according to the second aspect of the present invention has the above features, the soft magnetic alloy according to the fourth aspect of the present invention is easily obtained by heat treatment. In the soft magnetic alloy according to the third aspect and the soft magnetic alloy according to the fourth aspect, a high saturation magnetic flux density and a low coercivity can be achieved at the same time, and surface nature is improved.
The following description regarding the soft magnetic alloys according to the present invention is common among the first to fourth aspects.
In the soft magnetic alloys according to the present invention, 0≤α{1−(a+b+c+d+e+f+g)}≤0.40 may be satisfied.
In the soft magnetic alloys according to the present invention, a=0 may be satisfied.
In the soft magnetic alloys according to the present invention, 0≤β{1−(a+b+c+d+e+f+g)}≤0.030 may be satisfied.
In the soft magnetic alloys according to the present invention, β=0 may be satisfied.
In the soft magnetic alloys according to the present invention, α=β=0 may be satisfied.
The soft magnetic alloys according to the present invention may have a ribbon shape.
The soft magnetic alloys according to the present invention may have a powder shape.
A magnetic device according to the present invention is composed of the above-mentioned soft magnetic alloy.
Hereinafter, First Embodiment to Fifth Embodiment of the present invention are explained.
A soft magnetic alloy according to the present embodiment includes a main component of (Fe(1-(α+β))X1αX2β)(1-(a+b+c+d+e+f+g))MaBbPcSidCeSfTig, in which
X1 is one or more of Co and Ni,
X2 is one or more of Al, Mn, Ag, Zn, Sn, As, Sb, Cu, Cr, Bi, N, O, and rare earth elements,
M is one or more of Nb, Hf, Zr, Ta, Mo, W, and V,
0.020≤a≤0.14 is satisfied,
0.020<b≤0.20 is satisfied,
0.040<c≤0.15 is satisfied,
0≤d≤0.060 is satisfied,
0≤e≤0.030 is satisfied,
0≤f≤0.010 is satisfied,
0≤g≤0.0010 is satisfied,
α≥0 is satisfied,
β≥0 is satisfied,
0≤α+β≤0.50 is satisfied, and
at least one or more of f and g are larger than zero,
wherein the soft magnetic alloy has a nanohetero structure where initial fine crystals exist in an amorphous phase.
When the above-mentioned soft magnetic alloy according to First Embodiment undergoes a heat treatment, Fe based nanocrystallines are deposited easily. In other words, the soft magnetic alloy according to First Embodiment easily becomes a starting raw material of a soft magnetic alloy where Fe based nanocrystallines are deposited.
When the above-mentioned soft magnetic alloy (a soft magnetic alloy according to the first aspect of the present invention) undergoes a heat treatment, Fe based nanocrystallines are easily deposited in the soft magnetic alloy. In other words, the above-mentioned soft magnetic alloy easily becomes a starting raw material of a soft magnetic alloy where Fe based nanocrystallines are deposited (a soft magnetic alloy according to the third aspect of the present invention). Incidentally, the initial fine crystals preferably have an average grain size of 0.3 to 10 nm.
The soft magnetic alloy according to the third aspect of the present invention includes the same main component as the soft magnetic alloy according to the first aspect and a structure of Fe based nanocrystallines.
The Fe based nanocrystallines are crystals whose grain size is nano-order and whose crystal structure of Fe is bcc (body-centered cubic). In the present embodiment, it is preferable to deposit Fe based nanocrystallines having an average grain size of 5 to 30 nm. The soft magnetic alloy where Fe based nanocrystallines are deposited is easy to have a high saturation magnetic flux density and a low coercivity.
Hereinafter, each component of the soft magnetic alloy according to the present embodiment is explained in detail.
M is one or more of Nb, Hf, Zr, Ta, Mo, W, and V.
The M content (a) satisfies 0.020≤a≤0.14. The M content (a) is preferably 0.040≤a≤0.10, more preferably 0.050≤a≤0.080. When the M content (a) is small, a crystal phase composed of crystals having a grain size of larger than 30 nm is easily generated in the soft magnetic alloy before heat treatment. When the crystal phase is generated, Fe based nanocrystallines cannot be deposited by heat treatment, and coercivity easily becomes high.
When the M content (a) is large, saturation magnetic flux density easily becomes low.
The B content (b) satisfies 0.020<b≤0.20. The B content (b) may be 0.025≤b≤0.20 and is preferably 0.060≤b≤0.15, more preferably 0.080≤b≤0.12. When the B content (b) is small, a crystal phase composed of crystals having a grain size of larger than 30 nm is easily generated in the soft magnetic alloy before heat treatment. When the crystal phase is generated, Fe based nanocrystallines cannot be deposited by heat treatment, and coercivity easily becomes high. When the B content (b) is large, saturation magnetic flux density easily becomes low.
The P content (c) satisfies 0.040<c≤0.15. The P content (c) may be 0.041≤c≤0.15 and is preferably 0.045≤c≤0.10, more preferably 0.050≤c≤0.070. When the P content (c) is in the above range, especially in the range of c>0.040, the soft magnetic alloy has an improved resistivity, a low coercivity, and an improved surface nature. That is, when the soft magnetic alloy has a ribbon shape, the soft magnetic alloy has a small surface roughness, and a core to be obtained from the soft magnetic alloy has an improved space factor and an improved saturation magnetic flux density and can be suitable for large current and downsizing. When the soft magnetic alloy has a powder shape, the soft magnetic alloy has an improved sphericity, and a dust core to be obtained from the soft magnetic alloy has an improved filling rate. Moreover, when both resistivity and surface nature are improved, permeability is improved, and a high permeability can be maintained to a higher frequency. When the P content (c) is small, the above-mentioned effects are hard to be obtained. When the P content (c) is large, saturation magnetic flux density is decreased easily.
The Si content (d) satisfies 0≤d≤0.060. That is, Si may not be contained. The Si content (d) is preferably 0.005≤d≤0.030, more preferably 0.010≤d≤0.020. When the soft magnetic alloy contains Si, coercivity is particularly easily decreased. When the Si content (d) is large, coercivity is increased on the contrary.
The C content (e) satisfies 0≤e≤0.030. That is, C may not be contained. The C content (e) is preferably 0.001≤e≤0.010, more preferably 0.001≤e≤0.005. When the soft magnetic alloy contains C, coercivity is particularly easily decreased. When the C content (e) is large, coercivity is increased on the contrary.
The S content (f) satisfies 0≤f≤0.010. Preferably, 0.002≤f≤0.010 is satisfied. When the soft magnetic alloy contains S, it becomes easier to reduce coercivity and improve surface nature. When the S content (f) is large, coercivity is increased.
The Ti content (g) satisfies 0≤g≤0.0010. Preferably, 0.0002≤g≤0.0010 is satisfied.
When the soft magnetic alloy contains Ti, it becomes easier to reduce coercivity and improve surface nature. When the Ti content (g) is large, the soft magnetic alloy before heat treatment easily has a crystal phase composed of crystals having a grain size of larger than 30 nm. When the crystal phase is generated, Fe based nanocrystallines cannot be deposited by heat treatment, and coercivity easily becomes high.
It is important that the soft magnetic alloy according to the present embodiment particularly contain P and contain S and/or Ti. When the soft magnetic alloy does not contain P, or when the soft magnetic alloy does not contain S or Ti, surface nature is particularly easily decreased. Incidentally, “S is contained” means that f is not zero, and more specifically means that f≥0.001 is satisfied. “Ti is contained” means that g is not zero, and more specifically means that g≥0.0001 is satisfied.
The Fe content (1−(a+b+c+d+e+f+g)) is not limited, but is preferably 0.73≤(1−(a+b+c+d+e+f+g))≤0.95. When the Fe content (1−(a+b+c+d+e+f+g)) is in the above range, a crystal phase composed of crystals having a grain size of larger than 30 nm is harder to be generated in manufacturing the soft magnetic alloy according to First Embodiment.
In the soft magnetic alloys according to First Embodiment and Second Embodiment, a part of Fe may be substituted by X1 and/or X2.
X1 is one or more of Co and Ni. The X1 content may be α=0. That is, X1 may not be contained. Preferably, the number of atoms of X1 is 40 at % or less if the number of atoms of the entire composition is 100 at %. That is, 0≤α{1−(a+b+c+d+e+f+g)}≤0.40 is preferably satisfied.
X2 is one or more of Al, Mn, Ag, Zn, Sn, As, Sb, Cu, Cr, Bi, N, O, and rare earth elements. The content X2 may be β=0. That is, X2 may not be contained. Preferably, the number of atoms of X2 is 3.0 at % or less if the number of atoms of the entire composition is 100 at %. That is, 0≤β{1−(a+b+c+d+e+f+g)}≤0.030 is preferably satisfied.
The substitution amount of Fe by X1 and/or X2 is half or less of Fe based on the number of atoms. That is, 0≤α+β≤0.50 is satisfied. When α+β≥0.50 is satisfied, the soft magnetic alloy according to Second Embodiment is hard to be obtained by heat treatment.
Incidentally, the soft magnetic alloys according to First and Second Embodiments may contain elements other than the above-mentioned elements as unavoidable impurities. For example, 0.1 wt % or less of unavoidable impurities may be contained with respect to 100 wt % of the soft magnetic alloy.
Hereinafter, a method of manufacturing the soft magnetic alloy according to First Embodiment is explained.
The soft magnetic alloy according to First Embodiment is manufactured by any method. For example, a ribbon of the soft magnetic alloy is manufactured by a single roller method. The ribbon may be a continuous ribbon.
In the single roller method, pure metals of respective metal elements contained in a soft magnetic alloy finally obtained are initially prepared and weighed so that a composition identical to that of the soft magnetic alloy finally obtained is obtained. Then, the pure metal of each metal element is melted and mixed, and a base alloy is prepared. Incidentally, the pure metals are melted by any method. For example, the pure metals are melted by high-frequency heating after a chamber is evacuated. Incidentally, the base alloy and the soft magnetic alloy finally obtained normally have the same composition.
Next, the prepared base alloy is heated and melted, and a molten metal is obtained. The molten metal has any temperature, and may have a temperature of 1200 to 1500° C., for example.
On the other hand,
In the single roller method, it is conventionally considered that a molten metal is preferably cooled rapidly by increasing a cooling rate, that the cooling rate is preferably increased by increasing a contact time between the molten metal and a roller and by increasing a temperature difference between the molten metal and the roller, and that the roller thereby preferably normally has a temperature of about 5 to 30° C.
The present inventors can achieve a rapid cooling of the ribbon 24 even if the roller 23 has a high temperature of about 50 to 70° C. by rotating the roller 23 in the opposite direction (see
In the single roller method, the thickness of the ribbon 24 to be obtained can be controlled by mainly controlling the rotating speed of the roller 23, but can also be controlled by, for example, controlling the distance between the nozzle 21 and the roller 23, the temperature of the molten metal, and the like. The ribbon 24 has any thickness. For example, the ribbon 24 may have a thickness of 15 to 30 μm.
The chamber 25 has any inner vapor pressure. For example, the chamber 25 may have an inner vapor pressure of 11 hPa or less using an Ar gas whose dew point is adjusted. Incidentally, the chamber 25 has no lower limit for inner vapor pressure. The chamber 25 may have a vapor pressure of 1 hPa or less by being filled with an Ar gas whose dew point is adjusted or by being turned into a state close to vacuum.
The ribbon 24 (soft magnetic alloy according to the present embodiment) is an amorphous phase containing no crystals having a grain size of larger than 30 nm and has a nanohetero structure where initial fine crystals exist in the amorphous phase. When the soft magnetic alloy undergoes the following heat treatment, a Fe based nanocrystalline alloy can be obtained.
Incidentally, any method, such as a normal X-ray diffraction measurement, can be used for confirming whether the ribbon 24 contains crystals having a grain size of larger than 30 nm.
The existence and average grain size of the above-mentioned initial fine crystals are observed by any method, and can be observed by, for example, obtaining a selected area electron diffraction image, a nano beam diffraction image, a bright field image, or a high resolution image using a transmission electron microscope with respect to a sample thinned by ion milling. When using a selected area electron diffraction image or a nano beam diffraction image, with respect to diffraction pattern, a ring-shaped diffraction is formed in case of being amorphous, and diffraction spots due to crystal structure are formed in case of being non-amorphous. When using a bright field image or a high resolution image, an existence and an average grain size of initial fine crystals can be confirmed by visual observation with a magnification of 1.00×105 to 3.00×105.
The roller has any temperature and rotating speed, and the chamber has any atmosphere. Preferably, the roller has a temperature of 4 to 30° C. for amorphization. The faster a rotating speed of the roller is, the smaller an average grain size of initial fine crystals is. Preferably, the roller has a rotating speed of 25 to 30 m/sec. for obtaining initial fine crystals having an average grain size of 0.3 to 10 nm. In view of cost, the chamber preferably has an atmosphere air.
Hereinafter, explained is a method of manufacturing a soft magnetic alloy having a structure of Fe based nanocrystallines (a soft magnetic alloy according to the third aspect of the present invention) by carrying out a heat treatment against a ribbon 24 composed of a soft magnetic alloy having a nanohetero structure (a soft magnetic alloy according to the first aspect of the present invention).
The soft magnetic alloy according to the present embodiment is manufactured with any heat-treatment conditions. Favorable heat-treatment conditions differ depending on a composition of the soft magnetic alloy. Normally, a heat-treatment temperature is preferably about 450 to 650° C., and a heat-treatment time is preferably about 0.5 to 10 hours, but favorable heat-treatment temperature and heat-treatment time may be in a range deviated from the above ranges depending on the composition. The heat treatment is carried out in any atmosphere, such as an active atmosphere of air and an inert atmosphere of Ar gas.
Any method, such as observation using a transmission electron microscope, is employed for calculation of an average grain size of Fe based nanocrystallines contained in the soft magnetic alloy obtained by heat treatment. The crystal structure of bcc (body-centered cubic structure) is also confirmed by any method, such as X-ray diffraction measurement.
A ribbon composed of the soft magnetic alloy obtained by heat treatment has a high surface nature. Here, when a ribbon has a high surface nature, the ribbon has a small surface roughness. In a ribbon composed of the soft magnetic alloy according to the present embodiment, surface roughness Rv and surface roughness Rz particularly tend to be clearly small compared to those of ribbons of conventional soft magnetic alloys. Incidentally, surface roughness Rv is a maximum valley depth of a roughness curve, and surface roughness Rz is a maximum height roughness of a roughness curve. Then, a high volume fraction of a magnetic material is exhibited in a core obtained by winding a ribbon composed of a soft magnetic alloy having a small surface roughness and a core obtained by stacking ribbons composed of a soft magnetic alloy having a small surface roughness. Thus, a favorable core (particularly a troidal core) is obtained.
In addition to the above-mentioned single roller method, a powder of the soft magnetic alloy according to the present embodiment is obtained by a water atomizing method or a gas atomizing method, for example. Hereinafter, a gas atomizing method is explained.
In a gas atomizing method, a molten alloy of 1200 to 1500° C. is obtained similarly to the above-mentioned single roller method. Thereafter, the molten alloy is sprayed in a chamber, and a powder is prepared.
At this time, the above-mentioned favorable nanohetero structure is obtained easily with a gas spray temperature of 50 to 200° C. and a vapor pressure of 4 hPa or less in the chamber.
After the powder composed of the soft magnetic alloy having the nanohetero structure is prepared by the gas atomizing method, a heat treatment is conducted at 400 to 600° C. for 0.5 to 10 minutes. This makes it possible to promote diffusion of atoms while the powder is prevented from being coarse due to sintering of each grain, reach a thermodynamic equilibrium state for a short time, remove distortion and stress, and easily obtain a Fe based soft magnetic alloy having an average grain size of 10 to 50 nm.
The powder composed of the soft magnetic alloy according to First Embodiment and a soft magnetic alloy according to Second Embodiment mentioned below have an excellent surface nature and a high sphericity. A dust core obtained by the powder composed of the soft magnetic alloy having a high sphericity has an improved filling rate.
Hereinafter, Second Embodiment of the present invention is explained. The same matters as First Embodiment are not explained.
In Second Embodiment, a soft magnetic alloy before heat treatment is composed of only amorphous phases. Even if the soft magnetic alloy before heat treatment is composed of only amorphous phases, contains no initial fine crystals, and has no nanohetero structure, a soft magnetic alloy having a Fe based nanocrystalline structure, namely, a soft magnetic alloy according to the third aspect of the present invention can be obtained by heat treatment.
Compared to First Embodiment, however, Fe based nanocrystallines are hard to be deposited by heat treatment, and the average grain size of the Fe based nanocrystallines is hard to be controlled. Thus, excellent characteristics are hard to be obtained compared to First Embodiment.
Hereinafter, Third Embodiment of the present invention is explained. The same matters as First Embodiment are not explained.
The soft magnetic alloy according to the present embodiment includes a main component of (Fe(1-(α+β))X1αX2β)(1-(a+b+c+d+e+f+g))MaBbPcSidCeSfTig, in which
X1 is one or more of Co and Ni,
X2 is one or more of Al, Mn, Ag, Zn, Sn, As, Sb, Cu, Cr, Bi, N, O, and rare earth elements,
M is one or more of Nb, Hf, Zr, Ta, Mo, W, and V,
0.020≤a≤0.14 is satisfied,
0.020<b≤0.20 is satisfied,
0<c≤0.40 is satisfied,
0≤d≤0.060 is satisfied,
0.0005<e<0.0050 is satisfied,
0≤f≤0.010 is satisfied,
0≤g≤0.0010 is satisfied,
α≥O is satisfied,
β≥0 is satisfied,
0≤α+β≤0.50 is satisfied, and
at least one or more of f and g are larger than zero,
wherein the soft magnetic alloy has a nanohetero structure where initial fine crystals exist in an amorphous phase.
When the above-mentioned soft magnetic alloy (a soft magnetic alloy according to the second aspect of the present invention) undergoes a heat treatment, Fe based nanocrystallines are easily deposited in the soft magnetic alloy. In other words, the above-mentioned soft magnetic alloy easily becomes a starting raw material of a soft magnetic alloy where Fe based nanocrystallines are deposited (a soft magnetic alloy according to the fourth aspect of the present invention). Incidentally, the initial fine crystals preferably have an average grain size of 0.3 to 10 nm.
The soft magnetic alloy according to the fourth aspect of the present invention has the same main component as the soft magnetic alloy according to the second aspect and has a structure of Fe based nanocrystallines.
The content P (c) satisfies 0<c≤0.040. The content P (c) is preferably 0.010≤c≤0.040, more preferably 0.020≤c≤0.030. When the content P (c) is in the above range, the soft magnetic alloy has a low coercivity. When c=0 is satisfied, the above-mentioned effects cannot be obtained.
The C content (e) satisfies 0.0005<e<0.0050. The C content (e) is preferably 0.0006≤e≤0.0045, more preferably 0.0020≤e≤0.0045. When the C content (e) is larger than 0.0005, the soft magnetic alloy particularly easily has a low coercivity. When the C content (e) is too large, saturation magnetic flux density and surface nature are decreased.
Hereinafter, Fourth Embodiment of the present invention is explained. The same matters as Third Embodiment are not explained.
In Fourth Embodiment, a soft magnetic alloy before heat treatment is composed of only amorphous phases. Even if the soft magnetic alloy before heat treatment is composed of only amorphous phases, contains no initial fine crystals, and has no nanohetero structure, a soft magnetic alloy having a Fe based nanocrystalline structure, namely, a soft magnetic alloy according to the fourth aspect of the present invention can be obtained by heat treatment.
Compared to Third Embodiment, however, Fe based nanocrystallines are hard to be deposited by heat treatment, and the average grain size of the Fe based nanocrystallines is hard to be controlled. Thus, excellent characteristics are hard to be obtained compared to Third Embodiment.
A magnetic device, especially a magnetic core and an inductor, according to Fifth Embodiment is obtained from the soft magnetic alloy according to any of First Embodiment to Fourth Embodiment. Hereinafter, a magnetic core and an inductor according to Fifth Embodiment are explained, but the following method is not the only one method for obtaining the magnetic core and the inductor from the soft magnetic alloy. In addition to inductors, the magnetic core is used for transformers, motors, and the like.
For example, a magnetic core from a ribbon-shaped soft magnetic alloy is obtained by winding or laminating the ribbon-shaped soft magnetic alloy. When the ribbon-shaped soft magnetic alloy is laminated via an insulator, a magnetic core having further improved properties can be obtained.
For example, a magnetic core from a powder-shaped soft magnetic alloy is obtained by appropriately mixing the powder-shaped soft magnetic alloy with a binder and pressing this using a die. When an oxidation treatment, an insulation coating, or the like is carried out against the surface of the powder before the mixture with the binder, resistivity is improved, and the magnetic core becomes more suitable for high-frequency regions.
The pressing method is not limited. Examples of the pressing method include a pressing using a die and a mold pressing. There is no limit to the type of the binder. Examples of the binder include a silicone resin. There is no limit to a mixture ratio between the soft magnetic alloy powder and the binder either. For example, 1 to 10 mass % of the binder is mixed with 100 mass % of the soft magnetic alloy powder.
For example, 100 mass % of the soft magnetic alloy powder is mixed with 1 to 5 mass % of a binder and compressively pressed using a die, and it is thereby possible to obtain a magnetic core having a space factor (powder filling rate) of 70% or more, a magnetic flux density of 0.45T or more at the time of applying a magnetic field of 1.6×104 A/m, and a resistivity of 1 Ω·cm or more. These properties are equivalent to or more excellent than those of normal ferrite magnetic cores.
For example, 100 mass % of the soft magnetic alloy powder is mixed with 1 to 3 mass % of a binder and compressively pressed using a die under a temperature condition that is equal to or higher than a softening point of the binder, and it is thereby possible to obtain a dust core having a space factor of 80% or more, a magnetic flux density of 0.9T or more at the time of applying a magnetic field of 1.6×104 A/m, and a resistivity of 0.1 Ω·cm or more. These properties are more excellent than those of normal dust cores.
Moreover, a green compact constituting the above-mentioned magnetic core undergoes a heat treatment after the pressing for distortion removal. This further reduces core loss and improves usefulness. Incidentally, core loss of the magnetic core is decreased by reduction in coercivity of a magnetic material constituting the magnetic core.
An inductance product is obtained by winding a wire around the above-mentioned magnetic core. The wire is wound by any method, and the inductance product is manufactured by any method. For example, a wire is wound around a magnetic core manufactured by the above-mentioned method at least in one or more turns.
Moreover, when using soft magnetic alloy grains, there is a method of manufacturing an inductance product by pressing and integrating a magnetic material incorporating a wire coil. In this case, an inductance product corresponding to high frequencies and large electric current is obtained easily.
Moreover, when using soft magnetic alloy grains, an inductance product can be obtained by carrying out firing after alternately printing and laminating a soft magnetic alloy paste obtained by pasting the soft magnetic alloy grains added with a binder and a solvent and a conductor paste obtained by pasting a conductor metal for coils added with a binder and a solvent. Instead, an inductance product where a coil is incorporated into a magnetic material can be obtained by preparing a soft magnetic alloy sheet using a soft magnetic alloy paste, printing a conductor paste on the surface of the soft magnetic alloy sheet, and laminating and firing them.
Here, when an inductance product is manufactured using soft magnetic alloy grains, in view of obtaining excellent Q properties, it is preferred to use a soft magnetic alloy powder whose maximum grain size is 45 μm or less by sieve diameter and center grain size (D50) is m or less. In order to have a maximum grain size of 45 μm or less by sieve diameter, only a soft magnetic alloy powder that passes through a sieve whose mesh size is 45 μm may be used.
The larger a maximum grain size of a soft magnetic alloy powder is, the further Q values in high-frequency regions tend to decrease. In particular, when using a soft magnetic alloy powder whose maximum grain diameter is larger than 45 μm by sieve diameter, Q values in high-frequency regions may decrease greatly. When Q values in high-frequency regions are not so important, however, a soft magnetic alloy powder having a large variation can be used. When a soft magnetic alloy powder having a large variation is used, cost can be reduced as it can be manufactured comparatively inexpensively.
Hereinbefore, the embodiments of the present invention are explained, but the present invention is not limited to the above embodiments.
The soft magnetic alloy has any shape. For example, the soft magnetic alloy has a ribbon shape or a powder shape as mentioned above, but may have another shape of block etc.
The soft magnetic alloys (Fe based nanocrystalline alloys) according to First Embodiment to Fourth Embodiment are used for any purposes, such as magnetic devices (particularly magnetic cores), and can favorably be used as magnetic cores for inductors (particularly for power inductors). In addition to magnetic cores, the soft magnetic alloys according to the embodiments can favorably be used for thin film inductors and magnetic heads.
Hereinafter, the present invention is specifically explained based on Examples.
Raw material metals were weighed so that the alloy compositions of Examples and Comparative Examples shown in the following table would be obtained, and the weighed raw material metals were melted by high-frequency heating. Then, base alloys were manufactured. Incidentally, the compositions of Sample No. 13 and Sample No. 14 were a composition of a normally well-known amorphous alloy.
The manufactured base alloys were thereafter heated, melted, and turned into a molten metal at 1250° C. This metal was sprayed against a roller rotating at 25 m/sec. (single roller method), and ribbons were thereby obtained. Incidentally, the roller was made of Cu.
The roller was rotated in the direction shown in
Each of the obtained ribbons underwent an X-ray diffraction measurement and was confirmed if it contained crystals having a grain size of larger than 30 nm. When crystals having a grain size of larger than 30 nm did not exist, the ribbon was considered to be composed of amorphous phases. When crystals having a grain size of larger than 30 nm existed, the ribbon was considered to be composed of crystalline phases. Incidentally, all of Examples except for Sample No. 322 mentioned below had a nanohetero structure where initial fine crystals existed in amorphous phases.
After that, each ribbon of Examples and Comparative Examples underwent a heat treatment with the conditions shown in the following table. Each ribbon after the heat treatment was measured for saturation magnetic flux density, coercivity, and surface roughness (Rv and Rz). The saturation magnetic flux density (Bs) was measured in a magnetic field of 1000 kA/m using a vibrating sample type magnetometer (VSM). The coercivity (Hc) was measured in a magnetic field of 5 kA/m using a DC BH tracer. The surface roughness (Rv and Rz) was measured using a laser microscope.
In Experimental Examples 1 to 3, a saturation magnetic flux density of 1.30T or more was considered to be good, a saturation magnetic flux density of 1.35T or more was considered to be better, and a saturation magnetic flux density of 1.40T or more was considered to be still better. In Experimental Examples 1 to 3, a coercivity of 3.0 A/m or less was considered to be good, a coercivity of 2.5 A/m or less was considered to be better, a coercivity of 2.0 A/m or less was considered to be still better, and a coercivity of 1.5 A/m or less was considered to be best. In Experimental Examples 1 to 3, a surface roughness Rv of 12 μm or less was considered to be good, and a surface roughness Rz of 20 μm or less was considered to be good.
Unless otherwise noted, a measurement of X-ray diffraction and an observation using a transmission electron microscope confirmed that all of Examples shown below contained Fe based nanocrystallines having an average grain size of 5 to 30 nm and having a crystal structure of bcc. An ICP analysis also confirmed that the alloy composition did not change before and after the heat treatment.
Table 1 shows that all characteristics were good in Sample No. 9 to Sample No. 12 (each component content was in a predetermined range, and the roller contact distance and the roller temperature were favorable). On the other hand, Table 1 shows that surface roughness was bad in Sample No. 1 to Sample No. 8, Sample No. 13, and Sample No. 14 (any component content was outside a predetermined range).
Experimental Example 2 was carried out with the same conditions as Experimental Example 1 except that base alloys were manufactured by weighing raw material metals so that alloy compositions of Examples and Comparative Examples shown in the following tables would be obtained and by melting the raw material metals with high-frequency heating.
Table 2 to Table 11 show Examples and Comparative Examples whose S content (f) and Ti content (g) were changed with respect to a combination of several types of a to e. Incidentally, the type of M was Nb. In Examples whose each component content was in a predetermined range, saturation magnetic flux density Bs, coercivity Hc, and surface roughness were good.
In Comparative Examples containing neither S nor Ti, surface roughness was bad.
In Comparative Examples whose S content (f) was too large, the ribbon before the heat treatment was easily composed of a crystal phase. When the ribbon before the heat treatment was composed of a crystal phase, coercivity He after the heat treatment was significantly large. Even if the ribbon before the heat treatment was composed of an amorphous phase, coercivity He was large.
In Comparative Examples whose Ti content (g) was too large, the ribbon before the heat treatment was easily composed of a crystal phase and had a significantly large coercivity after the heat treatment.
Table 12 shows that saturation magnetic flux density Bs, coercivity Hc, and surface roughness were good in Examples whose each component content was in a predetermined range.
Sample No. 235 to Sample No. 243 in Table 12 were Examples and Comparative Examples whose M content (a) was changed. In Sample No. 235 (M content (a) was too small), the ribbon before the heat treatment was composed of a crystal phase, and coercivity He after the heat treatment was significantly large. In Sample No. 243 (M content (a) was too large), saturation magnetic flux density Bs was low.
Sample No. 244 to Sample No. 251 in Table 12 were Examples and Comparative Examples whose B content (b) was changed. In Sample No. 244 (B content (b) was too small), the ribbon before the heat treatment was composed of a crystal phase, and coercivity He after the heat treatment was significantly large. In Sample No. 251 (B content (b) was too large), saturation magnetic flux density Bs was low.
Sample No. 252 to Sample No. 259 in Table 12 were Examples and Comparative Examples whose P content (c) was changed. In Sample No. 252 (P content (c) was too small), coercivity He after the heat treatment was large, and surface roughness was bad. In Sample No. 259 (P content (c) was too large), saturation magnetic flux density Bs was low.
Sample No. 260 to Sample No. 274 in Table 12 were Examples and Comparative Examples whose Si content (d) and C content (e) were changed. In Sample No. 270 (Si content (d) was too large), coercivity He after the heat treatment was large. In Sample No. 264 (C content (e) was too large), coercivity He after the heat treatment was large.
Table 13 to Table 15 show Examples where a part of Fe of was substituted by X1 and/or X2 in Sample No. 24).
Table 13 to Table 15 show that favorable characteristics were exhibited even if a part of Fe was substituted by X1 and/or X2.
Table 16 shows Examples that were the same as Sample No. 237, Sample No. 24, or Sample No. 241 except for the type of M. Sample No. 237a to Sample No. 237i were the same as Sample No. 237. Sample No. 24a to Sample No. 24i were the same as Sample No. 24. Sample No. 241a to Sample No. 241i were the same as Sample No. 241.
Table 16 shows that favorable characteristics were exhibited even if the type of M was changed.
In Experimental Example 3, the average grain size of the initial fine crystals and the average grain size of the Fe based nanocrystalline alloy in Sample No. 24 were changed by appropriately changing the temperature of molten metal and the heat-treatment conditions after the ribbon was manufactured. Table 17 shows the results.
Table 17 shows that when the initial fine crystals had an average grain size of 0.3 to 10 nm and when the Fe based nanocrystalline alloy had an average grain size of 5 to 30 nm, both saturation magnetic flux density and coercivity were good compared to those when these ranges were not satisfied.
Raw material metals were weighed so that the alloy compositions of Examples and Comparative Examples shown in Tables 18 to 21 shown below were obtained, and the weighed raw material metals were melted by high-frequency heating. Then, base alloys were manufactured.
The manufactured base alloys were thereafter heated, melted, and turned into a molten metal at 1250° C. This molten metal was sprayed against a roller rotating at 25 m/sec. (single roller method), and ribbons were thereby obtained. Incidentally, the roller was made of Cu.
The roller was rotated in the direction shown in
Each of the obtained ribbons underwent an X-ray diffraction measurement and was confirmed if it contained crystals having a grain size of larger than 30 nm. When crystals having a grain size of larger than 30 nm did not exist, the ribbon was considered to be composed of amorphous phases. When crystals having a grain size of larger than 30 nm existed, the ribbon was considered to be composed of crystalline phases. Incidentally, all of Examples except for Sample No. 322 mentioned below had a nanohetero structure where initial fine crystals existed in amorphous phases.
After that, the ribbons of Examples and Comparative Examples underwent a heat treatment with the conditions shown in the following tables. Each of the ribbons after the heat treatment was measured for saturation magnetic flux density, coercivity, and surface roughness (Rv and Rz). The saturation magnetic flux density (Bs) was measured in a magnetic field of 1000 kA/m using a vibrating sample type magnetometer (VSM). The coercivity (Hc) was measured in a magnetic field of 5 kA/m using a DC BH tracer. The surface roughness (Rv and Rz) was measured using a laser microscope.
In Experimental Examples 4 and 5, a saturation magnetic flux density of 1.50T or more was considered to be good. In Experimental Examples 4 and 5, a coercivity of 3.0 A/m or less was considered to be good, a coercivity of 2.5 A/m or less was considered to be better, and a coercivity of 2.0 A/m or less was considered to be still better, and a coercivity of 1.5 A/m or less was considered to be best. In Experimental Examples 4 and 5, a surface roughness Rv of 12 μm or less was considered to be good, and a surface roughness Rz of 20 m or less was considered to be good.
Unless otherwise noted, a measurement of X-ray diffraction and an observation using a transmission electron microscope confirmed that all of Examples shown below contained Fe based nanocrystallines having an average grain size of 5 to 30 nm and having bcc crystal structure. An ICP analysis also confirmed that the alloy composition did not change before and after the heat treatment.
Tables 18 and 19 show that all characteristics were good in Examples whose each component content was in a predetermined range. On the other hand, Tables 18 and 19 show that one or more of coercivity, saturation magnetic flux density, and surface roughness were bad in Comparative Examples whose any component content was outside a predetermined range. Tables 18 and 19 show that the ribbon before the heat treatment was composed of a crystal phase, had a significantly large coercivity He after the heat treatment, and might have a bad surface roughness in Comparative Examples whose M content (a) was too small, Comparative Examples whose B content (b) was too small, and Comparative Examples whose Ti content (g) was too large.
Table 20 shows Examples where a part of Fe was substituted by X1 and/or X2 in Sample No. 410.
Table 20 shows that excellent characteristics were exhibited even if a part of Fe was substituted by X1 and/or X2.
Table 21 shows Examples whose M type was changed in Sample No. 410.
Table 21 shows that excellent characteristics were exhibited even if the type of M was changed.
In Experimental Example 5, the average grain size of the initial fine crystals and the average grain size of the Fe based nanocrystalline alloy in Sample No. 410 were changed by appropriately changing the temperature of molten metal and the heat-treatment conditions after the ribbon was manufactured. Table 22 shows the results.
Table 22 shows that when the initial fine crystals had an average grain size of 0.3 to 10 nm and when the Fe based nanocrystalline alloy had an average grain size of 5 to 30 nm, both saturation magnetic flux density and coercivity were good compared to those when these ranges were not satisfied.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-003405 | Jan 2018 | JP | national |
| 2018-160491 | Aug 2018 | JP | national |
