JPH07122116B2 - 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 positive magnetostriction and excellent in low magnetic field magnetostrictive characteristics.

[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]

[Means and Action for Solving the Problems] The present invention comprises: 0.01 to 5% by weight of cobalt (Co), 25 to 40% by weight of iron (Fe), 1 to 15% by weight of manganese (Mn), and terbium (Tb). ) 0.
1 to 25% by weight and the balance substantially dysprosium (Dy)
It is a magnetostrictive alloy having the composition

In such a rare earth-transition metal alloy system of such a system, a Laves type intermetallic compound is formed and excellent magnetostriction characteristics are exhibited at room temperature or higher. Coation is made in this Tb-Dy-Fe-Mn system.
By adding a small amount of, it is possible to obtain a more significant effect of improving the low-field magnetostrictive characteristic.

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

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 exhibits a synergistic effect with Tb and exhibits excellent magnetostriction characteristics. Tb and Dy belong to rare earths (lanthanides), and unlike 3d transition metals such as iron and nickel, Tf and Dy have extremely large magnetocrystalline anisotropy due to strong orbital momentum of 4f electrons to obtain excellent magnetostriction characteristics. It is an essential component as well as the main component of the alloy that imparts excellent toughness. However, Tb, Dy alone or a Tb-Dy alloy shows excellent magnetostriction characteristics in a low temperature region, but does not exhibit magnetostriction characteristics in a temperature region above room temperature.
With the Tb-Dy-Fe-Mn system, excellent magnetostrictive characteristics can be obtained in a temperature range of room temperature or higher.

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, its effect cannot be 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 to 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.

Although the above composition is basically used, the inclusion of an impurity element to the extent that the characteristics are not deteriorated is not hindered, and Tb and Dy are contained within a range not impairing 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 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 exhibits a large positive 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 negative magnetostrictive characteristics (for example, Ni).

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

[0020]

[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.

As a negative magnetostrictive alloy suitable for such a bimetal, for example, a Co-Fe-Sm-Dy type alloy can be cited.

The composition is, for example, cobalt (Co) 5-40.
% By weight, iron (Fe) 2 to 35% by weight, samarium (Sm) 0.0
1-60% by weight and the balance substantially dysprosium (Dy)
The composition of

The 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.

The composition ranges of such a negative magnetostrictive alloy are as follows.

Cobalt (Co): If it is less than 5% by weight, sufficient magnetostrictive properties when a low magnetic field is applied cannot be obtained, and 40% by weight.
If it exceeds, the magnetic properties will rather deteriorate.

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.

Various methods can be used for joining 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, etc. are used as fillers. Diffusion bonding at a temperature of about 1000 ° C. can be used.

[0031]

EXAMPLES Examples of the present invention will be described below. (Example 1) Co 1.2 wt%, Mn 7.3 wt%, Fe2
An alloy material having a composition ratio of 8.1 wt% and Tb 13 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 examined,
The maximum magnetostriction characteristic was 5 × 10 ⁻⁶ Oe ⁻¹ when a low magnetic field was applied up to 100 Oe, and the magnetostrictive characteristic at a low magnetic field was very good.

For comparison, when the same characteristics were examined for the above composition containing no Co, it was 3 × 10 ^-6 Oe ^-1 .

As described above, it is understood that the addition of Co improves the low magnetic field magnetostriction characteristic.

Further, when the same characteristics were investigated in the case of containing an excessive amount of Co (15% by weight), 0.7 × 10 ^-6 Oe ^{-1 was obtained.}
Therefore, it can be seen that the addition of excess Co rather deteriorates the magnetostrictive property.

As the positive magnetostrictive material and the negative magnetostrictive material, 100 μ
m thickness x 3 mm width x 30 mm length Ni (0.33 x 10 ^-6 Oe ^-1 )
Using thin plates, they are superposed through a powder filler material having a Co ₃ Dy ₄ intermetallic compound composition, and joined by diffusion treatment at 800 ° C. for 2 hours under a reduced pressure of 100 torr argon pressure,
Got a bimetal.

When this characteristic was examined, the applied magnetic field H = 100 Oe
Δd · H = 5 × 10 ^-4 under, displacement (stroke)
The characteristic was 1.35 mm, and the bending characteristic was 13.5 μm Oe ⁻¹ . (Example 2) Co 0.5 wt%, Mn 6.2 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).

When the magnetostrictive characteristics of this magnetostrictive member were investigated,
The low magnetic field magnetostrictive property was 6.2 × 10 ^-6 Oe ^-1, which was very good. (Example 3) 2.2% by weight of Co, 2.0% by weight of Mn, Fe3
When a magnetostrictive member was prepared in the same manner as in Example 2 using an alloy material having a composition ratio of 6.8 wt% and Tb23.3 wt% balance Dy, the low magnetic field magnetostrictive property was 8 × 10 ^-6 Oe ^-1, which was very good. It showed various characteristics. (Example 4) Using the positive magnetostrictive alloy prepared in Example 2, S
An example of a magnetostrictive bimetal using an m-Dy-Fe-Co alloy as a negative magnetostrictive member will be described.

Co21.5% by weight, Fe20.3% by weight, 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).

The low magnetic field magnetostrictive characteristic of this magnetostrictive member is -3.1 × 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.

Δd · H = 9 under applied magnetic field H = 100 Oe
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 (Permendur, d ₁
= 0.7 × 10 ⁻⁶ Oe ⁻¹ ) as a positive magnetostrictive member and Ni (d ₂ = −0.33 × 10 ⁻⁶ Oe ⁻¹ ) as a negative magnetostrictive member. A magnetostrictive bimetal was prepared by cutting a 30 mm long strip sample, and its characteristics were examined. Under an applied magnetic field H = 100 Oe, Δd · H = 1.
× is ^10-4, the displacement (stroke) characteristic 0.34 mm, the curved characteristic was 3μmOe ^-1.

Further, by adopting the bimetal structure in which both the positive and negative alloys are alloys of the above-mentioned composition containing Co, the absolute stroke is large, the linearity and 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 an intermetallic compound containing Co, various characteristics such as Young's modulus are almost the same as those in the case of combining the metal and the intermetallic compound, and the 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

[0050]

As described above, according to the present invention, it is possible to maintain the large positive 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) 0.01 to 5% by weight, iron (F)
e) Magnetostrictive alloy characterized by having a composition of 25-40% by weight, manganese (Mn) 1-15% by weight, terbium (Tb) 0.1-25% by weight and the balance substantially dysprosium (Dy). .