JP2001329347A - Shape memory alloy actuator, and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase magnetostrictive susceptibility and to attain time saving and cost reduction at thin film deposition. SOLUTION: This shape memory alloy actuator utilizing a shape memory effect has a substrate 21 and a thin film 22 composed of Fe-Pd alloy which is formed on the substrate 21 and has an acicular metallic structure oriented in the directions of (111) face and (220) face. Moreover, respective atomic percentages of Fe and Pd satisfy the relation of Fe:Pd=(60 to 50):(40 to 50).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a shape memory alloy actuator and a method for manufacturing the same.

[0002]

2. Description of the Related Art Recently, reports on shape memory alloys induced by a magnetic field have been active.

First, as a performance that can be expected from the magnetically induced shape memory alloy, first, a higher response speed than a heat-sensitive shape memory alloy represented by nitinol can be cited. This is because the transmission speed of the magnetic field is much faster than heat. Second, a larger deformation can be expected than with a giant magnetostrictive material.
Examples of applications that take advantage of these capabilities include actuators for micromachines, lightweight, low-cost actuators,
A high-speed responsive actuator is exemplified.

When such a magnetically induced shape memory alloy is used in an aircraft as an intelligent actuator,
Lighter weight and lower cost can be expected. It is also expected that high speed turning will be possible. Conventionally, a sputtering method is known as a method for producing a thin film using the shape memory alloy. However, there has been a problem that the magnetostriction susceptibility is low, and a great deal of time and cost are required.

[0005]

SUMMARY OF THE INVENTION Since the present invention has been made in view of such circumstances, a substrate and a metal structure formed on the substrate are oriented in the (111) plane and the (220) plane, and the needle is formed. And a thin film made of an alloy of Fe and Pd in a state of Fe: Pd = 60-4.
An object of the present invention is to provide a shape memory alloy actuator having a high magnetostriction susceptibility by adopting a configuration of 0:40 to 60.

Further, according to the present invention, the metal structure is acicular with the (111) plane and the (220) plane oriented and the atomic% is Fe:
An alloy of Fe and Pd with Pd = 60 to 50:40 to 50 is deposited on a substrate by magnetron sputtering to form a thin film made of an alloy of Fe and Pd, so that the magnetostrictive susceptibility is high and a thin film is formed. It is an object of the present invention to provide a method of manufacturing a shape memory alloy actuator that can reduce the time and cost for the above.

[0007]

According to a first aspect of the present invention, there is provided a substrate comprising: a substrate and Fe and Pd formed on the substrate and having a metal structure oriented in the (111) plane and the (220) plane and having a needle shape. An alloy thin film, wherein the atomic% of Fe and Pd is F
e: Pd = 60 to 50: A shape memory alloy actuator utilizing the shape memory effect, which is characterized by being 40 to 50.

In the second invention of the present application, the metal structure is (111)
Needles oriented in the (220) plane and the atomic%
e: Fe and Pd with Pd = 60 to 50:40 to 50
Is deposited on a substrate by magnetron sputtering to form a thin film made of an alloy of Fe and Pd.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

In the magnetron sputtering method used in the present invention, the influence of a magnetic field is strong, and an irregularly disordered layer is easily formed. Further, since the deposition rate is high, a needle crystal structure can be obtained. As a result, anisotropy is strong, magnetostriction is easily generated, and magnetostriction-induced martensite transformation is easily generated, so that a thin film having high magnetostriction susceptibility can be obtained. In addition, the amount of strain induced by the total magnetic field is greater than that of the liquid quenched sample.
The magnetron sputtered sample is larger.
In other words, the maximum magnetostriction of the sample made by the magnetron sputtering method is larger than that of the liquid-quenched sample. A thin film having a good susceptibility can be formed by the ease of forming an irregular layer by magnetron sputtering and the anisotropy by forming a needle-like crystal sample.

In view of the above, according to the present invention, a predetermined compounding ratio of Fe prepared by magnetron sputtering is used.
-We propose a high sensitivity magnetostriction induced martensitic transformation type actuator using Pd thin film.

In the present invention, the atomic% of Fe and Pd in the alloy of Fe and Pd is Fe: Pd = 60-50: 40-
50, but preferably in atomic% Fe: Pd = 5
8 to 50: 42 to 55. The ratios of the atomic percentages of Fe and Pd are based on a phase diagram showing the relationship between the atomic percentages and the temperature in FIG. 1 (“The magnetic field effect on the initial process of FePd alloy”, Ryuichiro Oshima et al., Journal of the Japan Institute of Metals. Volume 62 Number 4
No. (1998) 317-326). In FIG. 1, high sensitivity is obtained in the range of Fe: Pd = 60 to 50:40 to 50 in the γ phase region. Here, if the atomic% of Pd is less than 40, the magnetostriction susceptibility is low, and if it exceeds 50, the magnetostriction becomes small.

In the present invention, the thin film has a metal structure of (1)
11) and (220) plane oriented and acicular Fe
And an alloy of Pd. According to the theory of Dr. O'Handley of the United States MIT, the magnetic shape memory effect
It is shown to occur when Twin transformation is caused by magnetostriction. In addition, we have reported in previous studies that rapid solidification can form granular and columnar crystals. In addition, it is generally known that the texture of columnar crystals tends to generate Twin because the anisotropy is clear. Such a material has a large magnetically induced shape memory effect, and the shape memory effect induced by magnetism may firstly have a large amount of strain, and secondly it may have a very high sensitivity. . Therefore, a columnar crystal sample was prepared by rapid solidification, and the characteristics with respect to the magnetic field were confirmed.

When the shape of the sample was changed when the temperature was changed, it was confirmed that the strain increased as the sample temperature increased. Conversely, it was confirmed that the strain decreased as the sample temperature decreased. For example, at a test start temperature of 300 K, the shape almost returns to the original shape. From this result, it can be seen that the columnar Fe-Pd alloy has a shape memory effect.

In the present invention, for example, a magnetron sputtering apparatus as shown in FIG. 2 is used. FIG.
In the figure, reference numeral 1 indicates a reaction vessel. In the reaction vessel 1, a target 2 is disposed at an upper part, a holder 4 for supporting a substrate 3 is disposed at a lower part, and a shutter 5 is provided between the two.
Is arranged. Here, the shutter 5 is opened after being stabilized. A vacuum device (TP) 7a and a vacuum device (RP) 7b are connected to lower and side portions of the reaction vessel 1 via valves 6a and 6b, respectively. Both vacuum devices 7a,
7b is also connected by a pipe 8 with a valve 6c interposed. A cylinder 9 containing H ₂ gas and a cylinder 10 containing Ar gas are connected to the reaction vessel 1, respectively.

In the present invention, the outline of the measurement of strain when a magnetic field is applied to the actuator and the direction of the applied magnetic field are as shown in FIG. In FIG. 4, reference numeral 11 denotes a substrate, on which a thin film 12 made of an alloy containing Fe and Pd as appropriate is formed. When measuring the strain of the actuator having such a configuration, for example, He-
The end of the thin film 12 is irradiated with a laser beam 15 from a Ne laser 13 via a reflection plate 14, and the deformation of the actuator caused by the irradiation is measured by a measure 16. The arrow A in the figure indicates the direction of the applied magnetic field.

[0017]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 shows a sectional view of a shape memory alloy actuator according to the present invention. In FIG. 3, reference numeral 21 indicates a substrate. On the Si substrate 21, a metal structure (11
An acicular thin film 22 made of an alloy of Fe and Pd is formed on the (1) and (220) planes. Here, the atomic% of Fe is 55%, and the atomic% of Pd is 45% (F
e-45 at% Pd).

Next, the manufacture of the actuator having such a configuration will be described.
The fabrication method will be described. First, the magnetrons shown in Fig. 2
Using a puttering device, place the Si substrate 2 on the holder 4
Set 1 Then, using the vacuum devices 7a and 7b
After the inside of the reaction container 1 is evacuated, the shutter 5 is opened,
H₂Gas and Ar gas are simultaneously sent into the reaction vessel 1 and
Using a planar magnetron type sputtering gun,
A thin film 22 having a thickness of about 2 μm was formed on a substrate 21. Film formation
The conditions are: ultimate vacuum: 3.9 × 10 ^-5Pa, Ricre
Light (gas leak): 5.0 × 10^-7Pa ・ m³/
s, Ar partial pressure: 6.0 × 10^-2Pa, sputtering
Gas: Ar, target input power: 200W, sputtering
Time: 3600s, Substrate material: Si (100) surface, substrate
Temperature: 300K (room temperature).

The shape memory alloy actuator according to the above embodiment is formed on a Si substrate 21 and on the substrate 21.
An alloy of Fe and Pd (Fe-45at% P) having a metal structure oriented in the (111) plane and the (220) plane and having a needle shape.
d). Therefore,
According to the present invention, the following effects are provided.

1) The magnetostriction susceptibility can be increased as compared with the prior art. For example, magnetostrictive susceptibility of Fe-45at% Pd _{is, (Tb x, Dy 1-} x) than y _{Fe 1-y} thin film, which showed about 3 times higher.

2) Generally, the preparation of a thin film is a sample preparation method that requires much labor, time, and cost. However, according to the present invention, since the thin film 22 is formed by the magnetron sputtering method, the film can be easily formed in a short time. Therefore, cost can be reduced.

3) Since the sample has good corrosion resistance, it can be used in the atmosphere. This is the current (Tb _x , Dy
_1-y ) _y Fe Compared with the _1-y thin film, it shows a great advantage in practical use.

In fact, when the shape change of the sample when the temperature was changed was examined, it was confirmed that the strain increased as the sample temperature increased. Conversely, it was confirmed that the strain decreased as the sample temperature decreased. For example, at a test start temperature of 300 K, the shape almost returns to the original shape. From this result, it was found that the columnar Fe-Pd alloy exhibited a shape memory effect.

An alloy of Fe and Pd (Fe-47a
Example 1 except that a thin film made of t% Pd) was used.
For the actuator manufactured in the same manner as in
The relationship between the applied magnetic field H (kOe) at 00K and the strain λ (ppm) induced by the magnetic field was examined.
The characteristic diagram shown in FIG. 2 was obtained. As a result, it has been found that the distortion has a good low magnetic field response.

The measurement of magnetostriction uses an optical lever method, which is generally used for measuring the warpage of a bimetal. A magnetic field of 0 kOe to 15 kOe is applied using an electromagnet to apply the magnetic field. However, since the strain of the Fe-45 at% Pd thin film is saturated at an applied magnetic field of 3 kOe, the thin film can be sufficiently driven even by applying a magnetic field using a permanent magnet. FIG. 5 shows an X-ray diffraction diagram of the prepared thin film sample. From FIG. 5, (111)
It can be seen that the crystal is strongly oriented on the (220) plane and the (220) plane.
In particular, Fe: Pd = 55:
Forty-five samples show large magnetostriction and magnetostriction susceptibility. FIG. 6 shows the relationship between the applied magnetic field and the magnetization of the thin film sample. As shown in FIG. 6, even when the influence of the demagnetizing field is considered, the magnetization anisotropy is clearly recognized. Although not shown, when the cross-sectional view was observed with an electron microscope, it was confirmed that the structure of the thin film was columnar. Therefore, it can be seen that the thin film sample has greater anisotropy than the liquid quenched sample.

FIG. 7 shows the relationship between temperature and strain of a thin film sample. It can be seen that large deformation exceeding 3000 ppm is shown. It can be seen that the deformation due to heating returns to almost the original shape by cooling. Further, as shown in FIG. 7, it can be seen that further distortion can be obtained by applying a magnetic field. FIG. 8 shows the relationship between the applied magnetic field and the amount of magnetostriction of the manufactured thin film. From FIG. 8, the Fe-Pd alloy thin film is 3k
It has been found that the strain is saturated in a low magnetic field of Oe. It has also been found that the maximum magnetostriction increases as the temperature decreases. The maximum magnetostriction of the Fe—Pd thin film is Tb _0.3 Dy _{0 . 7} It is about half the magnetostriction of the Fe ₂ giant magnetostrictive thin film, but it can be seen that the magnetostrictive susceptibility in a low magnetic field is better for the Fe—Pd alloy thin film.

FIG. 9 shows the quenched sample of the Fe—Pd liquid, the thin film sample, and Tb in a low magnetic field up to an applied magnetic field of 400 ke.
_The figure shows the magnetostriction of a _0.3 Dy _0.7 Fe ₂ thin film sample. From this result, it is understood that the magnetostriction susceptibility of the Fe—Pd thin film is very high. FIG. 10 shows the relationship between the sample temperature of the Fe—Pd thin film and the maximum strain. Thus, it can be seen that the maximum magnetostriction increases as the temperature decreases. FIG. 11 shows a sample of the quenched Fe—Pd liquid, a sample of the thin film,
The relationship between the temperature of the e ₂ Tb _0.3 Dy _0.7 Fe ₂ thin film sample and the magnetostriction susceptibility is shown. Fe ₂ Tb _0.3 Dy _0.7 Fe
_{In the two} thin film samples, it can be seen that the lower the substrate temperature during film formation, the better the magnetostrictive susceptibility. In addition, it can be seen that the Fe-Pd thin film sample has a better magnetostriction susceptibility than the Fe-Pd liquid quenched sample, and the magnetostriction susceptibility of the Fe-Pd thin film becomes higher as the test temperature decreases. , Fe-45 at% Pd thin film was formed, but the present invention is not limited to this, and the atomic% of Fe and Pd is Fe:
With a thin film in the range of Pd = 60 to 50:40 to 50, substantially the same effects as in the above embodiment can be obtained.

[0029]

As described above in detail, according to the present invention, it is possible to provide a shape memory alloy actuator having a high magnetostriction susceptibility and capable of reducing time and cost for producing a thin film, and a method of manufacturing the same.

[Brief description of the drawings]

FIG. 1 is a state diagram showing the relationship between atomic% palladium and temperature.

FIG. 2 is an overall view of a magnetron sputtering apparatus according to the present invention.

FIG. 3 is a sectional view of a shape memory alloy actuator according to one embodiment of the present invention.

FIG. 4 is a characteristic diagram showing a shape change when the temperature of the actuator of FIG. 1 is changed.

5 is an X-ray diffraction diagram of the actuator of FIG.

FIG. 6 is a characteristic diagram showing a relationship between an applied magnetic field and magnetization of a thin film sample.

FIG. 7 is a characteristic diagram showing a relationship between temperature and strain of a thin film sample.

FIG. 8 shows the relationship between the applied magnetic field and the amount of magnetostriction of the fabricated thin film.

FIG. 9 shows Fe in a low magnetic field up to an applied magnetic field of 400 ke.
-Pd liquid quenched sample, thin film sample, Tb _0.3 Dy _0.7
FIG. 4 is a characteristic diagram showing a magnetostriction amount of the Fe ₂ thin film sample.

FIG. 10 is a characteristic diagram showing a relationship between a sample temperature of a Fe—Pd thin film and a maximum strain amount.

FIG. 11: Fe-Pd liquid quenched sample, thin film sample, Tb
FIG. 4 is a characteristic diagram showing a relationship between a temperature of a _0.3 Dy _0.7 Fe ₂ thin film sample and a magnetostriction susceptibility.

FIG. 12 is a characteristic diagram showing a relationship between an applied magnetic field H at 300 K and a distortion λ induced by the magnetic field.

FIG. 13 is a characteristic diagram showing a relationship between an applied magnetic field H at 300 K and a strain λ induced by the magnetic field of each sample.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Reaction container, 2 ... Target, 3 ... Substrate, 4 ... Holder, 5 ... Shutter, 6a, 6b ... Valve, 7a, 7b ... Vacuum apparatus, 8 ... Piping, 9, 10 ... Cylinder, 21 ... Si substrate, 22 ... a thin film.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Kazuya Oguri 1117 Kita-Kaneme, Hiratsuka-shi, Kanagawa Pref. Yoshito Matsumura 1117 Kita-Kaneme, Hiratsuka-shi, Kanagawa Prefecture (72) Inventor Hirohisa Uchida 1117 Kita-Kaneme, Hiratsuka-shi, Kanagawa Tokai University Engineering Department

Claims (3)

[Claims] 1. A substrate comprising: a substrate; and a thin film made of an alloy of Fe and Pd formed on the substrate and having a metal structure oriented in the (111) plane and the (220) plane and having a needle shape.
And the atomic% of Pd is Fe: Pd = 60-50: 40-50
A shape memory alloy actuator utilizing a shape memory effect, characterized in that: 2. The atomic percentage of Fe and Pd is Fe: Pd = 58.
2. The shape memory alloy actuator according to claim 1, wherein the ratio is from 50 to 42:55. 3. A metal structure having a (111) plane and a (220) plane.
Needle-like with atomic orientation Fe: Pd = 60-5
An alloy of Fe and Pd having a ratio of 0:40 to 50 is deposited on the substrate by magnetron sputtering, and Fe and Pd are deposited.
A method for manufacturing a shape memory alloy actuator, comprising forming a thin film made of the alloy d.