阅读说明：本技术 Fe基纳米晶软磁合金 (Fe-based nanocrystalline magnetically soft alloy ) 是由 井上明久 孔凡利 朱胜利 于 2020-09-11 设计创作，主要内容包括：本发明提供具有更高饱和磁通密度和更高磁导率且具有较低矫顽力的Fe基纳米晶软磁合金。本发明的Fe基纳米晶软磁合金由下式(I)的组成式表示：Fe-(a)B-(b)P-(c)Si-(d)Cu-(e)M1-(f)C-(g) (I)在式(I)中,M1是选自Mo和Nb的至少一种元素,满足(Mo-(1-)-(x)Nb-(X))(其中,0≤X≤0.5)；a、b、c、d、e、f和g分别表示原子％,82≤a≤84,8≤b≤9,3≤c≤4,1≤d≤2,0.5≤e≤1,1≤f≤2,0.5≤g≤1,a+b+c+d+e+f+g＝100。(The invention provides the Fe-based nanocrystalline soft magnetic alloy with higher saturation magnetic flux density, higher magnetic conductivity and lower coercive force. The Fe-based nanocrystalline soft magnetic alloy of the present invention is represented by the compositional formula of the following formula (I): fe a B b P c Si d Cu e M1 f C g (I) In formula (I), M1 is at least one element selected from Mo and NbSatisfy (Mo) 1‑ x Nb X ) (wherein X is more than or equal to 0 and less than or equal to 0.5); a. b, c, d, e, f and g respectively represent atomic percent, 82 is less than or equal to 84, 8 is less than or equal to b is less than or equal to 9, 3 is less than or equal to c is less than or equal to 4, 1 is less than or equal to d is less than or equal to 2, 0.5 is less than or equal to e is less than or equal to 1, 1 is less than or equal to f is less than or equal to 2, 0.5 is less than or equal to g is less than or equal to 1, and a + b + c + d + e + f + g is 100.)

1. An Fe-based nanocrystalline soft magnetic alloy represented by the compositional formula of the following formula (I):

Fe_aB_bP_cSi_dCu_eM1_fC_g (I)

in formula (I), M1 is at least one element selected from Mo and Nb, satisfying (Mo)_1-xNb_X) Wherein X is more than or equal to 0 and less than or equal to 0.5;

a. b, c, d, e, f and g respectively represent atomic percent, 82 is less than or equal to 84, 8 is less than or equal to b is less than or equal to 9, 3 is less than or equal to c is less than or equal to 4, 1 is less than or equal to d is less than or equal to 2, 0.5 is less than or equal to e is less than or equal to 1, 1 is less than or equal to f is less than or equal to 2, 0.5 is less than or equal to g is less than or equal to 1, and a + b + c + d + e + f + g is 100.

2. The Fe-based nanocrystalline soft magnetic alloy according to claim 1, wherein,

the saturation magnetic flux density (Bs) is 1.7T or more.

3. The Fe-based nanocrystalline soft magnetic alloy according to claim 1 or 2, wherein,

the coercive force (Hc) is 10A/m or less.

4. The Fe-based nanocrystalline soft magnetic alloy according to any one of claims 1 to 3, wherein,

the effective magnetic permeability (μ e (1kHz)) is 15000 or more.

5. The Fe-based nanocrystalline soft magnetic alloy according to any one of claims 1 to 4,

has a structure in which fine crystal grains are precipitated in an amorphous phase.

6. The Fe-based nanocrystalline soft magnetic alloy according to claim 5, wherein,

the fine crystal grains are precipitated from the amorphous phase by heat treatment.

Technical Field

The invention relates to a Fe-based nanocrystalline magnetically soft alloy. And more particularly, to Fe-based nanocrystalline soft magnetic alloys with high saturation magnetic flux density, high magnetic permeability, and low coercivity. The Fe-based nanocrystalline soft magnetic alloy of the present invention can be suitably applied to an electric converter, an inductor, a motor core, a magnetic shield, a magnetic sensor, and the like.

Background

Soft magnetic materials are used as magnetic core (iron core) materials for many electric devices such as motors, converters, choke coils, and the like, power supplies, and the like. The saturation magnetic flux density of the soft magnetic material is required to be high for downsizing of the electric device, and the magnetic permeability and coercive force of the soft magnetic material are required to be high for reducing the loss of the electric device.

As an alloy used for these soft magnetic materials, an Fe-based nanocrystalline soft magnetic alloy is known. Among them, it is known that a so-called nanocrystalline alloy in which a crystal phase composed of crystal grains having a diameter of ten and several nm to several tens nm and an amorphous phase are uniformly coexistent by a crystallization reaction of the amorphous (amorphous) phase exhibits excellent functional characteristics which cannot be obtained by both of an equilibrium phase and an amorphous single phase having the same composition, and in recent years, research and development have been actively conducted in order to further improve performance (patent documents 1 to 4).

Patent document 1: japanese patent No. 2672306

Patent document 2: japanese laid-open patent publication No. 6-128704

Patent document 3: japanese laid-open patent publication No. 2002-322546

Patent document 4: japanese patent laid-open No. 2020 and 20023 ([0004], [0014], etc.)

Disclosure of Invention

The present invention has been made in view of the above-described conventional circumstances, and an object thereof is to provide an Fe-based nanocrystalline soft magnetic alloy having a higher saturation magnetic flux density and permeability and a lower coercive force.

In order to solve the above problems, the present invention provides an Fe-based nanocrystalline soft magnetic alloy represented by the compositional formula of the following formula (I).

Fe_aB_bP_cSi_dCu_eM1_fC_g (I)

In formula (I), M1 is at least one element selected from Mo and Nb, satisfying (Mo)_1-xNb_X) (wherein X is more than or equal to 0 and less than or equal to 0.5);

a. b, c, d, e, f and g respectively represent atomic percent, 82 is less than or equal to 84, 8 is less than or equal to b is less than or equal to 9, 3 is less than or equal to c is less than or equal to 4, 1 is less than or equal to d is less than or equal to 2, 0.5 is less than or equal to e is less than or equal to 1, 1 is less than or equal to f is less than or equal to 2, 0.5 is less than or equal to g is less than or equal to 1, and a + b + c + d + e + f + g is 100.

The invention also provides the Fe-based nanocrystalline soft magnetic alloy with the saturation magnetic flux density (Bs) of more than 1.7T.

The invention also provides the Fe-based nanocrystalline soft magnetic alloy with the coercive force (Hc) of less than 10A/m.

The present invention also provides the above-described Fe-based nanocrystalline soft magnetic alloy having an effective permeability (μ e (1kHz)) of 15000 or more.

The present invention also provides the above Fe-based nanocrystalline soft magnetic alloy having a structure in which fine grains are precipitated in an amorphous phase.

The present invention also provides the above-described Fe-based nanocrystalline soft magnetic alloy in which fine crystal grains are precipitated from an amorphous phase by heat treatment.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the invention, the Fe-based nanocrystalline soft magnetic alloy with higher saturation magnetic flux density, higher magnetic conductivity and lower coercive force is provided.

Detailed Description

The present invention will be described in detail below.

The nanocrystalline soft magnetic alloy according to the present invention is represented by the composition formula of the following formula (I).

Fe_aB_bP_cSi_dCu_eM1_fC_g (I)

In formula (I), M1 is at least one element selected from Mo and Nb, satisfying (Mo)_1-xNb_X) (wherein X is more than or equal to 0 and less than or equal to 0.5).

In the formula (I), a, b, c, d, e, f and g respectively represent atomic percent, 82 is less than or equal to 84, 8 is less than or equal to 9, 3 is less than or equal to 4, 1 is less than or equal to 2, 0.5 is less than or equal to 1, and a + b + c + d + e + f + g is 100.

When the ratio of the above elements is deviated, the effects of high saturation magnetic flux density, high magnetic permeability, and low coercive force cannot be obtained at the same time. In addition, when the above alloy is heat-treated, it is difficult to obtain a nanostructure of Fe fine crystal grains in which an amorphous (amorphous) phase precipitates a bcc structure (a body-centered cubic lattice structure), and thus it is difficult to obtain a low coercive force effect in particular.

The present invention is characterized by coexistence of Mo and C, and more preferably, coexistence of Nb with Mo and C. Due to coexistence of these elements, higher amorphous formability and saturation magnetic flux density can be obtained. Further, by adding Mo, stabilization of the P metal element in an annealed state can be achieved at the time of heat treatment for producing a nanomagnetic alloy. Further, the coexistence of the metalloid element (B, Si here) and the metal element (particularly Mo, Nb, and the like) can stabilize the nanocrystalline structure. Further, the coexistence of Mo and Nb can improve the corrosion resistance. In addition, it is possible to achieve an improvement in the ability to form amorphous glass upon heat treatment, maintenance of the particle size of nano-sized bcc-Fe particles in a large heat treatment temperature region, relaxation of heat treatment conditions, and the like.

The nanocrystalline magnetic alloy of the present invention represented by the composition of formula (I) above preferably has a saturation magnetic flux density (Bs) of 1.7T or more. By setting the saturation magnetic flux density (Bs) to 1.7T or more, the saturation magnetic flux density (Bs) of the Fe-based amorphous alloy is exceeded, and the ferromagnetic Fe-based amorphous alloy can be used as an efficient soft magnetic material in a high magnetic field region where the ferromagnetic Fe-based amorphous alloy cannot be used.

The coercive force (Hc) is preferably 10A/m or less, and more preferably 7A/m or less. If the coercive force (Hc) exceeds 10A/m, high magnetic permeability may not be obtained in a wide frequency region.

Further, the effective permeability (μ e (1kHz)) is preferably 15000 or more. By making the effective permeability (μ e (1kHz)) 15000 or more, it can be suitably used as a highly efficient soft magnetic material for information communication devices in a high-frequency alternating magnetic field.

The nanocrystalline magnetic alloy according to the present invention having the above-described configuration can be produced by a currently used method.

For example, an alloy having a composition represented by the above formula (I) is cooled and solidified from a molten state (alloy melt) by various known liquid quenching methods such as a single-roll method and a twin-roll method, thereby producing a thin ribbon-like (ribbon-like) or filament-like amorphous alloy thin ribbon. Alternatively, an amorphous alloy film is formed by a vapor quenching method such as a sputtering method or a steam method. In the case of the single-roll method, the alloy melt may be rapidly cooled in an inert gas atmosphere or a vacuum atmosphere, or may be cooled in an atmospheric atmosphere.

Next, the ribbon thus prepared is heated to a temperature within the range of (Tx2-60) K to (Tx2-10) K, preferably (Tx2-30) K to (Tx2-20) K, and then subjected to a cooling heat treatment to crystallize it, whereby a part of the amorphous phase of the ribbon is crystallized to obtain a structure in which the amorphous phase coexists with a fine crystal phase composed of Fe crystal grains having an extremely fine bcc structure with an average particle size of 20nm or less, preferably 15nm or less, and the target Fe-based nanocrystalline soft magnetic alloy can be obtained. Here, Tx2 is the second crystallization temperature corresponding to the disappearance of the residual amorphous phase when the heat of differential scanning is measured at a temperature increase rate of 0.67K/s from Tx1 (first crystallization temperature) of Fe in which the bcc structure is precipitated from the amorphous phase.

The reason why the fine crystal structure composed of the extremely fine bcc crystal grains (Fe crystal grains) is precipitated by the heat treatment is that the amorphous alloy ribbon in the quenched state is a structure mainly composed of an amorphous phase, and when it is heated, a fine crystal phase composed of body-centered cubic crystal grains having an average grain size of 20nm or less and bcc-Fe as a main component is precipitated when it is equal to or higher than Tx1 (first crystallization temperature).

Further, in the alloy of the composition which deviates from the scope of the present invention, carbides such as NbC which may deteriorate soft magnetic characteristics may be precipitated at a temperature higher than the temperature at which the Fe fine crystal phase is precipitated. The temperature at which only Fe crystal grains of bcc structure are precipitated from amorphous in the present invention depends on the alloy composition, and in the present invention, as described above, it is preferably (Tx2-60) K to (Tx2-10) K, and more preferably (Tx2-30) K to (Tx2-20) K.

The rate of temperature rise when the temperature is raised to the heat treatment temperature is preferably in the range of 5 to 400K/min, more preferably in the range of 200 to 300K/min.

The Fe-based nanocrystalline soft magnetic alloy obtained by the above-exemplified conventional method has both high saturation magnetic flux density and high magnetic permeability, and has a small iron loss.

In addition, in the Fe-based nanocrystalline soft magnetic alloy, the suitable volume ratio of the bcc phase is 40-70%, and the optimal volume ratio is 60-70%.

In the present invention, by using an alloy having a composition represented by the above formula (I), the following effects are obtained: the glass forming ability is improved, the nano-sized bccFe particles can be maintained in a large heat treatment temperature range, the temperature range of the temperature Tx1 (first crystallization temperature) at which metastable crystals appear in the amorphous alloy phase and the temperature Tx2 (second crystallization temperature) at which the entire amorphous alloy phase completes crystallization and becomes a stable phase is widened, the precipitation of carbide NbC due to the addition of Nb alone is suppressed, and the production cost is reduced compared with the addition of Nb alone.

From the above, the Fe-based nanocrystalline soft magnetic alloy of the present invention is a high-frequency soft magnetic material having good thermal stability and good soft magnetic characteristics.

The heat treatment of the sample to be applied for obtaining the soft magnetic alloy of the present invention is not particularly limited, and the following methods may be mentioned: vacuum packaging in the prior art, and placing the packaged product into a heat treatment furnace for rapid heating and rapid cooling.

However, in the case of a material exhibiting soft magnetism such as the soft magnetic alloy of the present invention, the following method is preferable as compared with the above-described conventional heat treatment method: wrapping the sample in aluminum foil (foil) or copper foil, and heat treating in ash powder, carbon powder, fine sand or ferric oxide fine powder heated to specified temperature in advance. By performing the above heat treatment, the heat treatment can be rapidly completed by heating to a predetermined temperature at an extremely high heating rate and accurately controlling the heating rate and the heating time.

The heat treatment is a brand new rapid precise heat treatment process, can make the nanocrystalline bccFe crystal grains in the Fe-based nanocrystalline magnetically soft alloy of the invention finer, and can make the nanocrystalline bccFe crystal grains uniformly dispersed, and as a result, can obtain higher saturation magnetic flux density, low coercive force and high magnetic conductivity.

[ examples ]

Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to the examples.

(examples 1 to 7, comparative examples 1 to 5)

Amorphous thin ribbons having a thickness of 0.02mm were prepared by a single roll liquid quenching method using alloys having the compositions shown in tables 1 and 2 below. Next, the ribbon is annealed in a nitrogen atmosphere. The annealing temperature is Tx2- (10-40) K, and the annealing time is 5-30 minutes. Using these respective samples (alloys), measurement and evaluation were performed for the following respective items.

[ alloy Structure ]

The structure of the alloy after annealing was confirmed by an X-ray diffraction pattern. bcc denotes the body-centered cubic lattice structure of Fe, and Am denotes amorphous (amorphous).

In tables 1 to 2 below, "bcc + Am" indicates a state in which a bcc phase (crystal phase) of Fe and an amorphous phase coexist.

[ measurement of bcc particle size ]

Evaluation was performed by bright field image observation using a transmission electron microscope and half-width measurement of an X-ray diffraction peak.

[ measurement of saturated magnetic flux Density ]

The measurement was performed in a magnetic field of 2T using a Vibrating Sample Magnetometer (VSM).

[ measurement of Hc (coercive force) ]

The magnetic load up to 200A/m was measured using a B-H loop analyzer.

[ μ e (effective permeability) ]

The measurement was carried out in an alternating magnetic field of 5mA/m over a wide range from 0.1kHz to 10MHz using an impedance analyzer.

The results are shown in tables 1 and 2.

[ TABLE 1 ]

[ TABLE 2 ]

As shown in Table 1, it was confirmed that all the samples shown in examples 1 to 7 were in the amorphous phase in which Fe-bcc existed as nanocrystalline particles having a particle size of 10 to 15 nm. The volume ratio of the Fe-bcc phase is in the range of 60% to 70%. The saturation magnetic flux density (Bs) is 1.7T or more, and the coercive force (Hc) is 7A/m or less. Further, it was confirmed that the effective permeability (. mu.e) at 1kHz was 1.7X 10⁴As described above, the effective magnetic permeability (. mu.e) at 10kHz is 1900 or more, and the soft magnetic material has good soft magnetic properties.

On the other hand, as shown in Table 2, comparative examples 1 to 7 which deviate from the scope of the present invention could not obtain the effects of the present invention.

That is, comparative example 1 is an alloy in which B is low, comparative examples 2 and 3 are alloys in which Fe is low and B is high, and although Fe-bcc grains are present in the amorphous phase, the grains have a grain size of 23 to 35nm and are larger than those of examples, and the coercive force (Hc) is also large and 11 to 14A/m. Further, the effective permeability (μ e) at 1kHz is 9000 to 12000, the effective permeability (μ e) at 10kHz is 150 to 470, and the magnetic permeability is extremely low and is not considered to have soft magnetic properties.

Comparative example 4 is a composition with Nb content but lacking Mo, without using Mo and C at the same time, and is an alloy with Fe and B in low content. In this case, although Fe-bcc grains are present in the amorphous phase, NbC particles are also precipitated. The coercive force (Hc) was also large, and in addition, the effective permeability (μ e) at 1kHz and 10kHz was extremely low, and it was not considered to have soft magnetic characteristics.

Comparative example 5 is an alloy having a composition in which Nb is contained and the content thereof is large. In this case, although Fe-bcc grains are present in the amorphous phase, NbC particles are also precipitated. The coercive force (Hc) was also large, and in addition, the effective permeability (μ e) at 1kHz and 10kHz was also extremely low, and it was not considered to have soft magnetic characteristics.

In comparative examples 4 and 5, the deposition ratio of NbC particles was about 2% to 5% of the total alloy.

Comparative example 6 is an alloy of a composition containing Mo but no C ratio. In this case, although Fe-bcc grains were present in the amorphous phase, the grain size of these grains was 40nm, which is larger than that of example, and the coercive force (Hc) was also large, which was 27A/m. Further, the effective permeability (μ e) at 1kHz was 5000, which was extremely low, and the effective permeability (μ e) at 10kHz was too small in the measurement to obtain a reliable value, and was not considered to have soft magnetic characteristics.

Comparative example 7 is an alloy of a composition containing no Mo and Nb. In this case, although Fe-bcc grains are present in the amorphous phase, the grain size of these grains is large, 60nm, and the coercive force (Hc) is also large, 33A/m. Further, the effective permeability (μ e) at 1kHz was 3000 which was extremely low, and the effective permeability (μ e) at 10kHz was too small in the measurement value to obtain a reliable value, and was not considered to have soft magnetic characteristics.

Industrial applicability

The Fe-based nanocrystalline soft magnetic alloy of the present invention is an excellent soft magnetic material with high saturation magnetic flux density and low coercive force, and can be applied to electric converters, inductors, motor cores, magnetic shields, magnetic sensors, and the like.