JPH07122117B2 - Magnetostrictive alloy - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetostrictive alloy, and more particularly to a magnetostrictive alloy having negative magnetostriction and excellent in low magnetic field magnetostriction.

[0002]

2. Description of the Related Art In recent years, there have been remarkable improvements in machining accuracy in machining, and the era of micron to submicron is entering. It is not uncommon today that submicron processing accuracy is required for electronic devices, but in the era of mechatronics, ultra-fine processing and minute displacement control are being performed not only in the field of electronic engineering but also in the field of mechanical engineering. Problems are becoming important. Along with the development of optical information processing and optical recording equipment, the need for micro displacement control elements tends to increase.

Among various types of minute displacement control elements proposed, there is a magnetostrictive element as one method.

That is, it is a displacement generating element using a magnetostrictive material which is displaced by the application of an external magnetic field.

Various materials such as Ni are known as magnetostrictive materials, but among them, TbFe alloys are promising materials because they exhibit extremely large magnetostriction (US Pat. No. 437537).
2, U.S. Pat. No. 4,378,258, U.S. Pat. No. 4,308,474,
U.S. Pat. No. 4152178, Japanese Patent Publication No. 61-33892, JP Sho
49-2094, etc.).

A large magnetostriction can be obtained in such an R-Fe (R: rare earth) alloy system, but there is a problem in low magnetic field characteristics. That is, the amount of displacement at a low applied magnetic field was not sufficient.

[0007]

The present invention has been made in consideration of the above points, and an object thereof is to improve the low magnetic field magnetostriction characteristics of the R-Fe alloy system.

[0008]

According to the present invention, cobalt (Co) is 5 to 40% by weight, iron (Fe) is 2 to 35% by weight, samarium (Sm) is 0.01 to 60% by weight, and the balance is substantially. It is a magnetostrictive alloy characterized by having a composition of dysprosium (Dy).

In such a rare earth-transition metal alloy system of such a system, a Laves-type intermetallic compound is formed and excellent magnetostrictive properties are exhibited, and by adding Co to this Sm-Dy-Fe system, it is possible to further reduce the content significantly. It is possible to obtain the effect of improving the magnetostriction of the magnetic field.

The composition range of each element in the alloy of the present invention will be described below.

Cobalt (Co): If the amount is less than 5% by weight, sufficient magnetostrictive properties cannot be obtained when a low magnetic field is applied.
If it exceeds, the magnetic properties will rather deteriorate. Moreover, excessive addition leads to a decrease in the Curie temperature.

Iron (Fe): If it is less than 2% by weight, sufficient magnetostrictive properties cannot be obtained, and if it exceeds 35% by weight, the magnetic properties are rather deteriorated.

Samarium (Sm): D by addition of Sm
The magnetostriction characteristic can be improved compared to the case of only y, but 0.0
If it is less than 1% by weight, the effect of adding Sm cannot be obtained, and if it exceeds 60% by weight, the magnetostrictive properties are rather deteriorated.

Dy is an essential element for obtaining a large magnetostriction, and it is possible to obtain an alloy that exerts a synergistic effect with Sm and exhibits excellent magnetostriction characteristics. Sm and Dy belong to rare earths (lanthanides), and unlike 3d transition metals such as iron and nickel, they have extremely large magnetocrystalline anisotropy due to strong orbital momentum of 4f electrons, and have excellent magnetostrictive properties. It is an essential component as well as the main component of the alloy that imparts excellent toughness.

Although the above composition is basically used, Sm, Dy within a range that does not hinder the inclusion of an impurity element to the extent that characteristics are not deteriorated and does not impair the effects of the present invention.
It does not hinder the addition of other rare earth elements and other elements.

The manufacturing method is not particularly limited, and after melting an alloy material having a predetermined composition ratio in a vacuum, an inert gas atmosphere or a reducing gas atmosphere at a temperature equal to or higher than the melting point,
It may be cast to obtain an ingot, which is cut out into a desired shape and used. It is preferable to perform heat treatment for homogenization in the ingot state. Alternatively, the Bridgman method, the floating zone melt method, or the like can be used.

This magnetostrictive alloy shows a large negative magnetostrictive characteristic and can be used alone as a displacement generating element.
It can also be used as a bimetal by integrating with a magnetostrictive material exhibiting positive magnetostrictive properties.

Generally, the bending characteristic of bimetal is expressed by the following equation.

[0019]

[Equation 1] S = (3/4) (L) ² (1 / t) ・ Δd ・ H (S: Absolute stroke (mm), L: Plate length (mm), t: Plate thickness (mm) )) Therefore, in order to obtain S = 1mm as an absolute stroke, Δd · H = 2. Under the conditions of L = 30mm and t = 0.2mm.
It becomes 96 × 10 ^-4 .

The inventors of the present invention have diligently studied the magnetostrictive bimetal constituting magnetostrictive member and found that the magnetostrictive coefficient (d = dε / dH,
It is composed of two kinds of alloys whose absolute value of (strain amount / applied magnetic field) is 1 × 10 ^-6 Oe ^-1 or more and whose signs are opposite to each other, and Δd (=
| D ₁ −d ₂ |, d ₁ is the magnetostriction coefficient of the positive magnetostrictive alloy, d
₂ is a prototype of a magnetostrictive bimetal having a product Δd · H of the applied magnetic field (H) of the negative magnetostrictive alloy) of 2 × 10 ⁻⁴ or more, and its characteristics were evaluated. It was realized.

Examples of positive magnetostrictive alloys suitable for such bimetals include Tb-Dy-Fe-Mn-Co alloys.

The composition is, for example, cobalt (Co) 0.01
~ 5 wt%, iron (Fe) 25-40 wt%, manganese (Mn) 1
.About.15 weight, terbium (Tb) 0.1 to 25 weight and the balance substantially dysprosium (Dy).

Iron (Fe): If it is less than 25% by weight, sufficient magnetostrictive properties cannot be obtained, and if it exceeds 40% by weight, the toughness is remarkably reduced.

Manganese (Mn): If it is less than 1% by weight, sufficient magnetostrictive properties cannot be obtained, and if it exceeds 15% by weight, the magnetostrictive properties deteriorate.

Terbium (Tb): D by addition of Tb
The magnetostriction characteristic can be improved as compared with the case of only y, but 0.1
If it is less than 25% by weight, the effect of adding Tb cannot be obtained, and if it exceeds 25% by weight, the magnetostrictive property is rather deteriorated.

Dy is an essential element for obtaining a large magnetostriction, and it is possible to obtain an alloy that exerts a synergistic effect with Tb and exhibits excellent magnetostriction characteristics.

Here, cobalt (Co) is added to improve the low-field magnetostrictive property of Tb-Dy-Fe-Mn, but if it is less than 0.01% by weight, the effect of addition is not obtained, and 5 If the content exceeds 10% by weight, the magnetostrictive properties of the alloy as a whole deteriorate, so the range was set to 0.01-5% by weight. It should be noted that addition of excessive Co causes a decrease in the Curie temperature, but addition of Co in this range has the effect of increasing the Curie temperature of the entire alloy, which also leads to improvement in temperature characteristics.

A rare earth-transition metal alloy system of such a system also forms a Laves type intermetallic compound and exhibits excellent magnetostrictive properties at room temperature or higher.

Various methods can be used to bond the magnetostrictive materials, but powders having a eutectic alloy composition of Dy and Fe, Co such as Co ₃ Dy ₄ , Co ₃ Dy ₄ are used as fillers. Diffusion bonding at a temperature of about 1000 ° C. can be used.

[0030]

EXAMPLES Examples of the present invention will be described below. (Example 1) Co2 2.0 wt%, Fe 9.50 wt%, Sm4
An alloy material having a composition ratio of 9.3 wt% balance Dy was melted in a vacuum induction melting furnace and then cast to obtain an ingot.

Next, this ingot has a thickness of 150 μm ×
A strip sample having a width of 3 mm and a length of 30 mm was cut out to obtain a plate-shaped magnetostrictive member having a positive magnetostriction coefficient (d).

When the magnetostrictive characteristics of this magnetostrictive member were investigated,
The maximum magnetostrictive property of -2.5 × 10 ^-6 Oe ^-1 was shown in the low magnetic field application up to 100 Oe, and the magnetostrictive property in the low magnetic field was very good.

When the amount of Co was out of this range, the low magnetic field magnetostriction characteristics were inferior to those of this example both when it was small and when it was excessive.

As the negative magnetostrictive material and the positive magnetostrictive material, 100
μm thickness x 3mm width x 30mm length Fe-Co-V alloy (Permend
ur, d ₁ = 0.7 × 10 ⁻⁶ Oe ⁻¹ ) and superposed with a powder filler material having a Co ₃ Dy ₄ intermetallic compound composition, and subjected to diffusion treatment at 800 ° C. for 2 hours under a reduced pressure of 100 torr argon pressure. And joined to obtain a bimetal.

When this characteristic was examined, the applied magnetic field H = 100 Oe
Δd · H = 3 × 10 ^-4 under, displacement (stroke)
The characteristic was 0.8 mm, and the bending characteristic was 8.0 μmOe ⁻¹ . (Example 2) Co21.5 wt%, Fe20.3 wt%, Sm1
An alloy material having a composition ratio of 2.3 wt% balance Dy was melted in a vacuum induction melting furnace and then cast to obtain an ingot.

Next, this ingot has a thickness of 100 μm ×
A strip sample having a width of 3 mm and a length of 30 mm was cut out to obtain a plate-shaped magnetostrictive member having a negative magnetostriction coefficient (d).

When the magnetostrictive characteristics of this magnetostrictive member were investigated,
The low magnetic field magnetostrictive property was -3.1 × 10 ^-6 Oe ^-1, which was very good. (Example 3) Co8.6% by weight, Fe32.8% by weight, Sm5
When a magnetostrictive member was prepared in the same manner as in Example 2 using an alloy material having a composition ratio of 2.0 wt% balance Dy, the low magnetic field magnetostrictive property was -5 × 10 ^-6 Oe ^-1, which was a very good property. . Example 4 Using the negative magnetostrictive alloy prepared in Example 2, T
An example of a magnetostrictive bimetal using a b-Dy-Fe-Mn-Co alloy as a positive magnetostrictive member will be described.

Co0.5 wt%, Mn6.2 wt%, Fe2
An alloy material having a composition ratio of 9.0 wt% and Tb 12.5 wt% balance Dy was melted in a vacuum induction melting furnace and then cast to obtain an ingot.

Next, this ingot has a thickness of 100 μm ×
A strip sample having a width of 3 mm and a length of 30 mm was cut out to obtain a plate-shaped magnetostrictive member having a positive magnetostriction coefficient (d).

The low magnetic field magnetostrictive characteristic of this magnetostrictive member is 6.2 × 10
It was ^-6 Oe ^-1 .

Next, the positive and negative magnetostrictive members are replaced with Co ₃ Dy.
₄ Overlay via a powder filler material having an intermetallic compound composition, 800 torr at 100 torr argon pressure reduction, 2
Bonding was performed by diffusion treatment for a time to obtain a bimetal.

Under the applied magnetic field H = 100 Oe, Δd · H = 9
It was × 10 ^-4 .

With this structure, the displacement (stroke) characteristic of the magnetostrictive bimetal is 3 mm under an applied magnetic field of 100 Oe,
The bending property was 30 μm Oe ⁻¹ .

For comparison, Fe-Co-V alloy was used as a positive magnetostrictive member and Ni (d ₂ = -0.33 × 10 ^-6 O) as a negative magnetostrictive member.
From the clad material produced by rolling using e ^-1 ), 3
A magnetostrictive bimetal was prepared by cutting a rectangular sample with a width of 30 mm and a length of 30 mm, and its characteristics were examined. Applied magnetic field H = 100 Oe
Δd · H = 1 × 10 ^-4 under, the displacement (stroke)
The characteristic was 0.34 mm, and the bending characteristic was 3 μmOe ⁻¹ .

Further, by adopting the bimetal constitution in which both the positive and negative alloys are alloys having the above-mentioned composition containing Co, the absolute stroke is large, the linearity and the displacement history characteristics are excellent, and the fatigue strength, impact resistance, etc. Will be excellent.

More specifically, since both the positive and negative magnetostrictive alloys are composed of Co-containing intermetallic compounds, various characteristics such as Young's modulus are almost the same as in the case of combining the metal and the intermetallic compound, and displacement occurs. At times, stress does not concentrate on one side, so the reliability as a bimetal such as fatigue resistance and displacement history characteristics can be improved. Since the displacement characteristic, that is, the order of the magnetostriction coefficient is also about the same, it is possible to increase both the positive side displacement and the negative side displacement, and as a result, the effect of increasing the absolute stroke and improving the linearity is obtained. You can

[0047]

As described above, according to the present invention, it is possible to maintain the large negative magnetostriction characteristic of the rare earth-iron alloy and improve the low magnetic field characteristic. Therefore, by using the alloy of the present invention as a displacement generating element using magnetostriction, a large displacement can be obtained in a low magnetic field, which is a great contribution to the industry.

Claims (1)

[Claims] 1. Cobalt (Co) 5-40% by weight, iron (Fe) 2
A magnetostrictive alloy having a composition of about 35 wt%, samarium (Sm) 0.01 to 60 wt% and the balance substantially dysprosium (Dy).