JP2713364B2 - Ultra-microcrystalline soft magnetic alloy with excellent heat resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a microcrystalline soft magnetic alloy having excellent heat resistance used for various magnetic cores such as various transformers, choke coils, and magnetic heads.

[Related Art] In recent years, amorphous alloys have attracted attention and have been put into practical use as materials having high saturation magnetic flux density and excellent high-frequency characteristics as core materials for high-frequency transformers, choke coils, magnetic heads, and the like.

Amorphous alloys are mainly classified into Fe-based and Co-based.Fe-based amorphous alloys have the advantage of high saturation magnetic flux density and the material cost is lower than that of Co-based alloys. However, there is a problem that the core loss is larger and the magnetic permeability is lower than that of the Co-based amorphous alloy. Further, the Fe-based amorphous alloy has a remarkably large magnetostriction, and when used as a magnetic core, there is a disadvantage that the magnetic core is beaten or the properties are significantly deteriorated when impregnated or coated.

On the other hand, Co-based amorphous alloys have low core loss at high frequencies and high magnetic permeability, but have the disadvantage that the core loss and magnetic permeability change over time and the saturation magnetic flux density is not sufficient. Furthermore, since expensive Co is used as a main raw material, a disadvantage in terms of price is inevitable.

Various proposals have been made for Fe-based amorphous alloys under such conditions.

JP-B-60-17019 discloses that 74 to 84 atomic% of Fe and 8 to 2
It has a composition of 4 at% B and at least one of 16 at% or less of Si and 3 at% or less of C, wherein at least 85% of its structure is in the form of an amorphous metal body. , And having a precipitate of crystalline particles that are discontinuously distributed throughout the amorphous metal substrate, and the crystalline particles
An iron-based boron-containing magnetic amorphous material having an average particle size of 1 to 1 μm and an average interparticle distance of 1 to 10 μm, wherein the particle group occupies an average volume fraction of 0.01 to 0.3 in total. An alloy is disclosed. The crystalline particles of this alloy have a discontinuous distribution of α- (Fe, S
i) It is considered to be a particle group.

Further, in _{JP-A-60-52557 Fe a Cu b B c Si} d ( however, 75
≤a≤85,0 <b≤0.5,10≤c≤20, d≤10 and c + d≤3
No. 0) is disclosed.
This amorphous alloy is heat-treated at a temperature lower than the crystallization temperature and higher than the Curie temperature.

[Problems to be Solved by the Invention] The core of Fe-based soft magnetic alloy disclosed in JP-B-60-17019 has a reduced core loss due to the presence of discontinuous crystalline particles, but the core loss is still large. In particular, there is a problem that a beat is generated due to a large magnetostriction, and a core loss and a remarkable deterioration of magnetic permeability are caused by performing impregnation coating.

On the other hand, the Fe-based amorphous alloy disclosed in JP-A-60-52557 contains Cu and the core loss of the magnetic core using Cu is reduced, but is the same as the magnetic core using the Fe-based magnetic alloy containing crystal grains. Not satisfied. Further, there is a problem that the change with time of the core loss and the magnetic permeability are not sufficient.

As a result of study to solve such problems, the present inventors have found that the Fe-Cu-Nb-Si-B-based alloy has an ultrafine grain structure and exhibits excellent soft magnetic properties. And Japanese Patent Application No. 62-317189.

However, if impurity elements other than the above elements are present in these alloys, the soft magnetic properties deteriorate at a relatively low temperature.

With such an alloy, the heat treatment temperature cannot be too high, which imposes restrictions not only on manufacturing but also on the process of reheating for bonding like a magnetic head, which imposes great restrictions on the process.

An object of the present invention is to provide a microcrystalline soft magnetic alloy having excellent heat resistance.

[Means for Solving the Problems] As a result of earnest studies to achieve the above object, the present inventors have determined that the elements C, P, O, S, and N in the microcrystalline soft magnetic alloy are By making the amount less than the above, it has been found out that an ultra-microcrystalline soft magnetic alloy which can be subjected to high-temperature heat treatment and has a small deterioration of soft magnetic properties even when reheated and has excellent heat resistance can be obtained.

That is, in the present invention, at least 50% of the structure is fine crystal grains, and the average of the particle diameters measured at the maximum size of the crystal grains is 1000 ° or less, and the composition is 0.1 to 3 atomic% of Cu,
M 'is 0.1 to 30 atomic% (where M' is Nb, W, Ta, Zr, Hf, Ti
And at least one element selected from the group consisting of Mo), B at 25 atomic% or less, and Y at 0.15 atomic% or less (Y is selected from the group consisting of C, P, O, S, N). And the balance is Fe and has heat resistance, and is a microcrystalline soft magnetic alloy having excellent heat resistance.

In the present invention, the ultra-microcrystalline soft magnetic alloy contains 30 atomic% or less of Si in its composition component (provided that the total of Si and B is 5 to 5%).
30 atomic%), M "(where M" is at least one element selected from the group consisting of V, Cr, Mn, Al, a white metal element, Zn, Sn, Ge, Ga) at 10 atomic% or less May be contained.

Further, in the present invention, the ultra-microcrystalline soft magnetic alloy,
Fe of the composition component is Fe _1-a M _a (where M is Co and / or N
i and a may be 0.1 or less). In this case, the Si
Or M '.

More preferred soft magnetic properties are obtained when the average of the particle diameters is 500 ° or less, particularly preferably 20 to 200 ° or less.

In the Fe-based soft magnetic alloy of the present invention, Fe can be substituted with Co and / or Ni in the range of 0 to 0.1 to improve corrosion resistance.

However, "a" is limited to 0 to 0.1 for good magnetic properties (low core loss, low magnetostriction).

In the present invention, Cu is an essential element, and its content x
Ranges from 0.1 to 3 atomic%. If less than 0.1 atomic%
There is almost no effect of lowering the core loss and increasing the magnetic permeability due to the addition of Cu. On the other hand, if it is more than 3 atomic%, the core loss may be larger than that of the non-added one, and the magnetic permeability also deteriorates. Preferred Cu content x in the present invention is 0.5 to
In this range, the core loss is particularly small and the magnetic permeability is high. Further, Cu has an effect of forming nuclei of bccFe solid solution crystals and also has an effect of suppressing the formation of a compound phase.

In the present invention, M ′ has an action of refining the crystal grains precipitated by complex addition with Cu, and Nb, W, Ta,
It is at least one element selected from the group consisting of Zr, Hf, Ti and Mo. Nb and others have the effect of raising the crystallization temperature of the alloy, but the interaction with Cu, which has the effect of forming clusters and lowering the crystallization temperature, suppresses the growth of crystal grains and refines the crystal grains that precipitate. It is thought to be.

The content α of M ′ is 0.1 to 30 atomic%, and if it is less than 0.1 atomic%, the effect of crystal grain refinement is insufficient, and if it exceeds 30 atomic%, the saturation magnetic flux density is remarkably reduced.

The preferred addition amount of M 'is 2 to 8 atomic%. Si and B are particularly useful elements for refining the alloy composition. The Fe-based soft magnetic alloy of the present invention is preferably obtained by once forming an amorphous alloy by the effect of adding Si and B and then forming fine crystal grains by heat treatment. The reason for limiting the contents y and z of Si and B is that if y is not more than 30 at%, z is not more than 25 at%, and y + z is not 5 to 30 at%, there is a remarkable decrease in the saturation magnetic flux density of the alloy. is there.

M ″, which is at least one element selected from the group consisting of V, Cr, Mn, Al, a white metal element, Zn, Sn, Ge, and Ga, improves corrosion resistance, improves magnetic characteristics, and improves magnetostriction. Can be added for the purpose of adjusting the content, but the content is not more than 10 atomic% at most. If the content exceeds 10 atomic%, the saturation magnetic flux density is remarkably reduced. It is.

C, P, O, S, and N, which are features of the present invention, are elements that easily enter impurities as a raw material, and when ferroalloy or the like is used as a raw material, C, P, O, S, and N may be contained in an alloy in large amounts.

As a result of intensive studies, these elements were found to be Fe-Cu-Nb-Si-B
It was found that this was the cause of the deterioration of the soft magnetic properties during heating of the base alloy, and these elements were 0.15 at% or less in total, especially C: 0.2 at% or less, P: 0.05 at% or less, and O: 0.05 at%. %.
When S: 0.02 atomic% or less and N: 0.02 atomic% or less, it was found that an ultra-microcrystalline soft magnetic alloy excellent in heat resistance was obtained without being affected by these elements.

Since these elements easily form a compound phase or segregate easily, it is considered that when the temperature is increased, the soft magnetic properties are easily deteriorated.

EXAMPLES Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to the scope of these examples.

Example 1 B having a purity of 99.5% or more, Si having a purity of 99.99% or more, and a purity of 99.5%
Using the above Nb, Cu with a purity of 99.9% or more, and Fe with a purity of 99.9% or more, vacuum melting was performed to prepare a mother alloy. Next, an alloy ribbon having a width of 5 mm and a thickness of 19 μm was produced by a single roll method using the mother alloy.

As a result of composition observation by X-ray diffraction and transmission electron microscope,
It was confirmed that this alloy ribbon was an amorphous alloy.

Next, this alloy ribbon was wound with the roll contact surface inside, to produce a toroidal magnetic core, and heat-treated in an Ar gas atmosphere. FIG. 1 shows the heat treatment temperature dependence of the magnetic properties of the alloy A of the present invention. The heat treatment time is one hour.

Next, the alloy A was analyzed. As a result, B; 7.21at
%, Si; 13.61at%, Nb; 2.61at%, Cu; 1.01at%, C; 0.022at
%, P; 0.001at%, O; 0.005at%, S; 0.001at%, N; 0.001at%
Met. (Each value is the analysis value of weight% as Fe bal.
It is a value converted to atomic%. Comparative Example 1 As a comparative example, the analysis value is B; 7.51 at%, Si; 13.22 at%, N
b; 2.41at%, Cu; 0.99at%, C; 0.53at%, P; 0.8at%, O; 0.06
At%, S; 0.03 at%, N; 0.03 at%, the balance being substantially Fe, an alloy B was prepared by the same method as that for the alloy A, and the core was subjected to the same heat treatment as the alloy A. This comparative alloy B
FIG. 1 also shows the dependence of the magnetic properties on the heat treatment temperature.

After the heat treatment at a temperature of 510 ° C. or more, the ultrafine crystal grains having a grain size of about 200 ° occupy most of the composition in both alloys A and B.

As can be seen from the figure, in the case of the alloy of the present invention having a small amount of C, P, O, S, and N, the heat treatment can be performed at a higher temperature.

Next, the alloy A of the present invention and the comparative alloy B, which were heat-treated at 550 ° C. for 1 hour, were heated to 570 ° C., held for 50 minutes, cooled to room temperature, and cooled to 1 kHz.
The effective magnetic permeability μelk at z was measured.

Ratio of effective magnetic permeability μelk at 1kHz before and after heating μ _a
/ mu _b result of comparison, the present invention alloy A is 0.97, C, P, O, S, N
Comparative alloy B having a large amount was 0.09, and it was confirmed that the present invention exhibited less deterioration of soft magnetic properties due to heating and was excellent in heat resistance. Here, mu _a is μelk after heating, the mu _b is μelk before heating.

Example 2 A wound core made of an ultrafine crystalline soft magnetic alloy having an analytical composition shown in Table 1 was prepared, and was subjected to a heat treatment at 570 ° C. in the same manner as in Example 1, and at 1 kHz before and after heating as in Example 1. The ratio of the value of the effective magnetic permeability μelk, μ _a / μ _b, was determined. Table 1 shows the obtained results.

As can be seen from Table 1, the alloy of the present invention has μ _a / μ _b of 0.90
As described above, it was confirmed that the alloy was substantially degraded without any problem and was excellent in heat resistance.

On the other hand, C defined in the present invention, O, comparative alloy exceeds P, S, a range of N are all a μ _a / μ _b is less than 0.90, rapidly further exceeds this provision the range mu _a / value of mu _b decreases, the heat resistance was confirmed to be reduced.

[Effects of the Invention] According to the present invention, an ultra-microcrystalline soft magnetic alloy having excellent heat resistance can be obtained, and the effect is remarkable.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing the heat treatment temperature dependence of the magnetic properties of the alloy according to the present invention and a comparative alloy.

Claims (4)

(57) [Claims] At least 50% of the structure is fine grains, and the average of the grain sizes measured at the largest dimension of the grains is 1000 °.
The composition is as follows: Cu is 0.1 to 3 atomic%, M ′ is 0.1
-30 atomic% (M 'is at least one element selected from the group consisting of Nb, W, Ta, Zr, Hf, Ti and Mo), B is 25 atomic% or less, and Y is 0.15 atomic% in total. The following (however, Y is C, P, O,
One or more elements selected from the group consisting of S, N)
An ultra-microcrystalline soft magnetic alloy having excellent heat resistance, with the balance being Fe and heat resistance. 2. The ultra-fine heat-resistant ultra-fine alloy according to claim 1, wherein the content of Si is 30 atomic% or less, and the total of Si and B is 5 to 30 atomic%. Crystal soft magnetic alloy. 3. M ″ of 10 atomic% or less (where M ″ is V, Cr, M
3. At least one element selected from the group consisting of n, Al, a white metal element, Zn, Sn, Ge, and Ga). 2. A microcrystalline soft magnetic alloy having excellent heat resistance according to 1.). (4) Fe is Fe _1-a M _a (where M is Co and / or N)
4. The microcrystalline soft magnetic alloy with excellent heat resistance according to claim 1, wherein i and a are each 0.1 or less.