JP7240874B2 - MAGNETOSTRICTIVE ELEMENT FOR GENERATION, MANUFACTURING METHOD THEREOF, AND GENERATOR - Google Patents

Description

The present invention relates to a magnetostrictive element for power generation, a method for manufacturing the same, and a power generator.

In the use of the Internet of Things (hereafter abbreviated as "IoT"), which has been developing in recent years, a wireless system that integrates a sensor, a power supply, a wireless communication device, etc. is used to connect things and the Internet. Use a sensor module. As a power source for such wireless sensor modules, there is no need for periodic manual maintenance such as battery replacement or charging work, and a power generation device that can generate power from the energy generated in the environment of the installation site. Development is desired.

An example of such a power generator is a magnetostrictive vibration power generator that uses inverse magnetostriction, which is the opposite effect of magnetostriction. Inverse magnetostriction is a phenomenon in which the magnetization of a magnetostrictive material changes when stress such as vibration is applied to the magnetostrictive material. Magnetostrictive vibration power generation applies stress to the magnetostrictive material due to vibration, and the change in magnetization caused by the inverse magnetostrictive effect generates an electromotive force in the coil wound around the magnetostrictive element according to the law of electromagnetic induction. be.

Conventionally, in order to improve the power generation performance of magnetostrictive materials, attempts have been made to increase the amount of magnetostriction. This is because the greater the magnetostriction, the greater the change in magnetic flux density (ΔB) using reverse magnetostriction and the greater the power output when tensile stress and compressive stress are alternately applied to the magnetostrictive material. One method of increasing the magnetostriction of a magnetostrictive material is to control the crystal structure of the magnetostrictive material. The basic lattice structure of conventionally developed Fe--Co alloys and Fe--Ga alloys is the bcc structure, and the <100> orientation has the maximum magnetostriction. Therefore, a method of aligning the Goss orientation {110}<100> texture by rolling, recrystallization, or the like, or a method of cutting a single crystal into <100> orientation has been implemented.

For example, regarding the Fe--Ga alloy of the magnetostrictive material, Patent Document 1 discloses a method of forming an Fe--Ga alloy sheet containing one or more additional elements selected from Al, Be, B and the like. In this forming method, a texture of {110}<001> orientation (Goss orientation) having a large amount of magnetostriction is produced by a pack rolling method. Further, Patent Document 2 discloses a magnetostrictive material in which carbide (Nb ₂ C) is finely dispersed in an Fe—Ga alloy to refine the crystal structure and improve rolling workability.

Regarding the Fe—Co alloy of the magnetostrictive material, Patent Document 3 discloses an Fe—Co alloy massive bulk, thin plate, and ribbon alloy with a Co atomic % of 56 to 80% and a magnetostriction of 60 ppm or more. ing. Furthermore, Patent Document 4 discloses that 67 to 87% by mass of Co and 1% by mass or less of one or more selected from Nb, Mo, V, Ti and Cr are melted and solidified, hot rolling, cold rolling, and a method of making Fe—Co alloys including heat treatment.

U.S. Patent Application Publication No. 2008/0115864 U.S. Patent Application Publication No. 2015/0028724 JP 2013-177664 A WO2015/083821

The Fe—Ga alloys described in Patent Document 1 and Patent Document 2 are brittle and thus have low workability. Moreover, since it is difficult to manufacture by normal hot rolling or cold rolling, it is inferior in mass productivity. Furthermore, since the Ga element is more expensive than the Co element, there is also the problem that the raw material cost is high and the material price is also high.

On the other hand, the Fe—Co alloys described in Patent Documents 3 and 4 can be processed by normal hot rolling and cold rolling, so they are excellent in mass productivity, and the material price is also lower than that of the Fe—Ga alloy. and cheap. However, the amount of magnetostriction is small, and when used as an element for power generation, there is a problem that the power output is low.

Thus, in the conventional alloy design of magnetostrictive materials, it is necessary to improve the magnetostriction amount in order to increase the power generation output. Alloys with a high magnetostriction (Fe--Ga alloys) are brittle and thus have low workability, are difficult to mass-produce, and are expensive. Moreover, if mass productivity and price are prioritized, the amount of magnetostriction becomes low, and there is a problem that it is difficult to improve the power generation output.

Further, in the conventional magnetostrictive element for power generation, it is difficult to uniformly change the magnetic domain with respect to the stress over the entire magnetostrictive element, and there are portions in the magnetostrictive element that cannot contribute to the magnetic flux density change ΔB. This is because the magnetic domain structure of the conventional magnetostrictive element is not uniform over the entire element, but differs from place to place.

The present invention has been made in view of the above circumstances, and a magnetostrictive element for power generation that has a high power output and can be stably mass-produced for use in magnetostrictive power generation, a method for manufacturing the same, and the magnetostrictive element for power generation A power generator using the element is provided.

In view of the above problems, the first aspect of the present invention is the following magnetostrictive element for power generation.
[1] A plate-shaped magnetostrictive element for power generation made of an Fe-based magnetostrictive alloy,
At least one of the front and back surfaces of the magnetostrictive element for power generation is a magnetic surface on which a first magnetic domain including a 180° domain wall and a second magnetic domain including a 90° domain wall are present, and the magnetic field with respect to the area of the magnetic surface The ratio of the total area of the first magnetic domains present on the surface is 0% or more and 70% or less, and the ratio of the total area of the second magnetic domains is 50% or more and 100% or less, and the distribution of the second magnetic domains on the magnetic surface is uniform over the entire magnetic surface,
The ratio of the total area of the first magnetic domain, the ratio of the total area of the second magnetic domain, and the distribution of the second magnetic domain are obtained by demagnetizing the magnetic surface of the magnetostrictive element for power generation with an alternating magnetic field and then demagnetizing A magnetostrictive element for power generation, which is a value measured by a magneto-optical method with no external stress applied to the surface.
[2] The magnetic surface has a magnetic domain altering surface treatment portion, and the total area of the magnetic domain altering surface treatment portion is 0.5% or more and 10% or less of the area of the magnetic surface. The magnetostrictive element for power generation according to [1].
[3] The magnetostrictive element for power generation according to [2], wherein the magnetic domain altering surface treatment portion is at least one selected from concave portions and residual stress portions.
[4] The magnetostrictive element for power generation according to [3], wherein the magnetic domain altering surface treatment portion is a concave portion.
[5] The magnetostrictive element for power generation according to [4], wherein the depth of the concave portion is 0.03t or more and 0.4t or less with respect to the thickness t of the magnetostrictive element for power generation.
[6] The magnetostrictive element for power generation according to [4] or [5], wherein the plurality of recesses are arranged in a dotted line, or the recesses are linear.
[7] The magnetostrictive element for power generation according to [3], wherein the magnetic domain altering surface treatment portion is a residual stress portion.
[8] The magnetostrictive element for power generation according to [7], wherein the residual stress portion on the surface of the magnetic surface has a range of 50 μm or more and 500 μm or less.
[9] The magnetostrictive element for power generation according to [7] or [8], wherein the residual stress portion has a depth of 0.1 t or more and 0.7 t or less with respect to the thickness t of the magnetostrictive element for power generation.
[10] The magnetostrictive element for power generation according to any one of [1] to [9], wherein the Fe-based magnetostrictive alloy is an Fe--Ga-based alloy, an Fe--Co-based alloy, or an Fe--Al-based alloy.
[11] The magnetostrictive element for power generation according to any one of [1] to [10], wherein the Fe-based magnetostrictive alloy has a saturation magnetostriction value λs of 20×10 ⁻⁶ or more.

A second aspect of the present invention is the following method for manufacturing a magnetostrictive element for power generation.
[12] providing a plate-shaped magnetostrictive material made of an Fe-based magnetostrictive alloy, and subjecting at least one of the front and back surfaces of the plate-shaped magnetostrictive material to a surface treatment for changing the magnetic domain to obtain a surface-treated magnetic surface; including
The magnetic surface has a first magnetic domain including a 180° domain wall and a second magnetic domain including a 90° domain wall, and the ratio of the total area of the first magnetic domains present on the magnetic surface to the area of the magnetic surface is 0. % or more and 70% or less, and the ratio of the total area of the second magnetic domains is 50% or more and 100% or less, and the distribution of the second magnetic domains on the magnetic surface is uniform over the entire magnetic surface,
The percentage of the total area of the first magnetic domains, the percentage of the total area of the second magnetic domains, and the distribution of the second magnetic domains are obtained by demagnetizing the magnetic surface of the plate-shaped magnetostrictive material with an alternating magnetic field and then demagnetizing the magnetic A method for manufacturing a magnetostrictive element for power generation, which is a value measured by a magneto-optical method with no external stress applied to the surface.
[13] The manufacturing method according to [12], wherein the magnetic domain altering surface treatment is at least one selected from formation of recesses and application of residual stress.

A third aspect of the present invention is the following power generator.
[14] A power generator comprising the magnetostrictive element for power generation according to any one of [1] to [11].

According to the present invention, a power generating magnetostrictive element for use in magnetostrictive power generation, which has a high power output and is capable of stable mass production, a method for manufacturing the same, and a power generator using the power generating magnetostrictive element are provided. .

FIG. 2 is a schematic diagram showing a magnetic surface of a magnetostrictive element having surface-treated portions (recesses);

As described above, in the magnetostrictive power generator, the greater the amount of magnetostriction of the magnetostrictive element, the greater the change in magnetic flux density (ΔB) using reverse magnetostriction when tensile stress and compressive stress are alternately applied to the magnetostrictive material. , the power output also increases. Therefore, in the past, attempts have been made to increase the amount of magnetostriction in order to improve the power generation performance of magnetostrictive elements. Specifically, techniques aimed at increasing ΔB by aligning crystal orientations in a predetermined direction have been studied.

In response to this, the present inventors conceived a method of increasing ΔB by controlling the magnetic domain structure of the magnetostrictive material, instead of aligning the crystal orientations in a predetermined direction to increase ΔB. Specifically, the ratio of the total area of the first magnetic domain including the 180° domain wall to the area of at least one surface (magnetic surface) of the front surface and the back surface of the magnetostrictive element is 0% or more and 70% or less, and the 90° domain wall When the ratio of the total area of the second magnetic domain including the also found to be larger.

Furthermore, the present inventor has found a method of manufacturing a magnetostrictive element for power generation, which includes surface treatment for controlling the first magnetic domain and the second magnetic domain of the magnetic surface of the magnetostrictive material so as to satisfy the above conditions. The manufacturing method of the present invention makes it possible to increase the power generation output of a magnetostrictive material with a low magnetostriction amount, such as an Fe—Co alloy.

The present invention will be described below with reference to exemplary embodiments, but the present invention is not limited to the following embodiments.

1. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate-like magnetostrictive element for power generation made of an Fe-based magnetostrictive alloy.
In the present invention, the “magnetostrictive element for power generation” (hereinafter sometimes abbreviated as “magnetostrictive element”) is composed of a magnetic material that exhibits magnetostrictive properties, that is, shape change (i.e., strain) due to the application of a magnetic field. It means a magnetostrictive material capable of generating electricity based on reverse magnetostriction.

In the magnetostrictive element of the present invention, at least one of the front and back surfaces of the plate-shaped magnetostrictive element is a magnetic surface on which a first magnetic domain including a 180° domain wall and a second magnetic domain including a 90° domain wall are present. Furthermore, the ratio of the total area of the first magnetic domain to the area of the magnetic surface (hereinafter sometimes abbreviated as "the ratio of the first magnetic domain") is 0% or more and 70% or less, and the ratio of the second magnetic domain The ratio of the total area (hereinafter sometimes abbreviated as "second magnetic domain ratio") is 50% or more and 100% or less. In the present invention, the front and back surfaces of the plate-shaped magnetostrictive element mean the surfaces with the widest area, and do not include side surfaces with smaller areas.

In the magnetic domain structure of a magnetic material, there is a space between the magnetic domains in which the magnetic moment of the atoms is continuously reversed little by little. , 90° is referred to as a “90° domain wall”. A magnetic domain including a 180° domain wall is defined as a first magnetic domain, and a magnetic domain including a 90° domain wall is defined as a second magnetic domain. Note that some magnetic domains include both 180° domain walls and 90° domain walls, that is, there are domains that are both the first magnetic domain and the second magnetic domain. Therefore, the ratio of each magnetic domain is a value independently obtained with respect to the area of the magnetic surface, and the sum of the ratio of the first magnetic domain and the ratio of the second magnetic domain may exceed 100%.

The "area of the magnetic surface", which is the denominator of the ratio of magnetic domains, is the area obtained from two-dimensional dimensions without considering the irregularities of the magnetic surface. Therefore, in the case where the magnetic surface has recesses such as grooves as surface treatment portions for altering magnetic domains, which will be described later, the "area of the magnetic surface" is not the surface area including the area of the inner walls of the grooves. For example, if the shape of the magnetostrictive element is rectangular, the area is obtained as the product of the dimension in the longitudinal direction and the dimension in the lateral direction.

Although the reason why the power generation output is improved when the ratio of the first magnetic domain and the second magnetic domain satisfies the above requirements is not clear, it is presumed as follows.

The first magnetic domain including the 180° domain wall cannot contribute to power generation because its magnetization direction does not change even if a tensile stress is applied in a direction parallel to the 180° domain wall. Therefore, when tensile stress and compressive stress are alternately applied to the magnetostrictive element, half of the stress is not utilized. Therefore, when the ratio of the first magnetic domain exceeds 70%, the power generation capacity of the magnetostrictive element is lowered. In addition, the second magnetic domain containing the 90° domain wall has the effect of helping the change in the magnetization direction of the first magnetic domain when a compressive stress is applied parallel to the 180° domain wall. However, this effect tends to decrease when the first domain fraction exceeds 70%. For these reasons, in the present invention, the ratio of the first magnetic domain is 0% or more and 70% or less, preferably 10% or more and 50% or less. If the ratio of the first magnetic domain is 50% or less, the power generation capacity is further improved, which is preferable. Further, when the first magnetic domain is 10% or more, the effect of increasing ΔB is exhibited more effectively.

On the other hand, the second magnetic domain can change its magnetization even when a tensile stress is applied in the direction parallel to the 180° domain wall and the magnetization of the first magnetic domain does not change, so it can contribute to power generation. Therefore, the greater the ratio of the second magnetic domain, the more the power generation efficiency is improved. Furthermore, the effect of helping the second magnetic domain to change the magnetization direction of the first magnetic domain tends not to achieve a sufficient effect of improving the power generation efficiency unless the ratio of the second magnetic domain is 50% or more. For these reasons, in the present invention, the ratio of the second magnetic domain is 50% or more and 100% or less, preferably 70% or more and 100% or less. When the ratio of the second magnetic domain is 70% or more, the effect of helping the change of the magnetization direction of the first magnetic domain by the second magnetic domain is further improved.

The ratio of the total area of the first magnetic domain and the ratio of the total area of the second magnetic domain are obtained by demagnetizing the magnetic surface of the magnetostrictive element for power generation with an alternating magnetic field, and then applying no external stress to the demagnetized magnetic surface. It is the value measured by the magneto-optical method in the state. Specifically, it was measured by the following method.

Since the first magnetic domain and the second magnetic domain change depending on the magnetic field and stress, an alternating magnetic field is applied to the magnetostrictive element, and the magnitude of the magnetic field is gradually weakened until it becomes zero, thereby demagnetizing the magnetostrictive element. After that, magnetic domains are observed by a magneto-optical method with no external stress applied to the demagnetized magnetic surface. The positions of the 180° domain wall and the 90° domain wall are determined from the contrast of the observed image, the shape of the contrast, and the like, and the respective regions of the first magnetic domain and the second magnetic domain are obtained.
The definition of the ratio of magnetic domains is as follows.
The ratio of the first magnetic domain is defined as S1/So×100 (%) where So is the total area of one side of the magnetostrictive element and S1 is the total area of the first magnetic domain in So.
The ratio of the second magnetic domain is defined as S2/So×100(%) where So is the total area of one side of the magnetostrictive element and S2 is the total area of the second magnetic domain in So.

The definition of the proportion of the first magnetic domain and the proportion of the second magnetic domain will be specifically described with reference to FIG. FIG. 1 is a schematic diagram showing a magnetic surface 10 having concave portions 1 as surface-treated portions. The distance a in the drawing is the lengthwise dimension of the magnetostrictive element, and the distance b is the widthwise dimension of the magnetostrictive element. Therefore, the total area So of one surface of the magnetostrictive element is a×b.

Next, the arrows in the figure represent the magnetization directions within the magnetic domains. As described above, the region containing the 180° domain wall has the first magnetic domain (180° magnetic domain), and the region containing the 90° domain wall has the second magnetic domain (90° magnetic domain). On the magnetic surface 10, only the second magnetic domain exists in the region 2 containing only the 90° domain wall 5 represented by thick diagonal lines, while the 180° domain wall 4 and the 90° domain wall 5 represented by thick straight lines are present. Both the first magnetic domain and the second magnetic domain are present in the region 3 containing both. Therefore, the total area S1 of the first magnetic domain is equal to the total area of region 3, and the total area S2 of the second magnetic domain is the sum of the total area of region 2 and the total area of region 3.

Therefore, the ratio of the first magnetic domain defined as S1/So×100 (%) is
(Total area of region 3) / (a × b) × 100 (%),
The ratio of the second magnetic domain defined as S2/So×100 (%) is
(total area of region 2+total area of region 3)/(a×b)×100(%).
As will be described later, since the magnetic domain cannot be observed from the concave portion 1, the concave portion 1 is not indicated with an arrow, and the area of the concave portion 1 is not included in the calculation of the ratio of magnetic domains.

The area ratio of the magnetic domains and its distribution can also be actually determined by magneto-optical methods. When measuring the ratio of the first magnetic domain and the second magnetic domain by this method, it is not necessary to observe the entire magnetic surface of the magnetostrictive element. As the So-corresponding region, the proportions of the first magnetic domain and the second magnetic domain in the representative region may be obtained by the method described above.

For example, when the magnetostrictive element is plate-shaped and the shape of the magnetic surface is rectangular, a portion near the central portion in the longitudinal direction and the width direction perpendicular thereto, or approximately the center between the longitudinal ends and the central portion and the central portion between the width direction end and the central portion are selected as representative regions, and the total number of first magnetic domains and second magnetic domains in each of these three locations is about 100. Then, the ratio of magnetic domains can be observed using a magneto-optical method.

Furthermore, the distribution of the second magnetic domains on the magnetic surface is uniform over the entire magnetic surface. In the present invention, the expression that the magnetic domain distribution is "uniform over the entire magnetic surface" means the following state. Drawing a plurality of straight lines of arbitrarily the same length on the image of the magnetic surface containing the first magnetic domain and the second magnetic domain obtained by the method described above for determining the ratio of the first magnetic domain and the second magnetic domain, When the straight line is entirely on the second magnetic domain, part of the straight line is on the first magnetic domain, and the other part is on the second magnetic domain. Some patterns emerge. In the present invention, five or more lines of the same length are drawn on the image so as to be randomly arranged vertically, horizontally, and obliquely, and the pattern of each straight line straddling the second magnetic domain is observed. , record the number of times each straight line straddles the second magnetic domain. At this time, when the number of crossing over the second magnetic domain is the same for all five straight lines, or when the maximum and minimum values of crossing over the second magnetic domain satisfy the relationship of the following formula (1): , determines that the distribution of the second domain is "uniform".
(N1-N2)/N1≦0.5 (1)
In the formula, N1 is the maximum number of times the straight line straddles the second magnetic domain, and N2 is the minimum number of times the straight line straddles the second magnetic domain.

In the magnetostrictive element of the present invention, if the distribution of the second magnetic domains having an area ratio of 50% or more and 100% or less is uniform over the entire magnetic surface, the magnetostrictive element will not spread over the entire magnetic surface when an external stress is applied. It is considered that the generated power output is improved because the magnetization change that contributes to the power generation is caused by the On the other hand, if the distribution of the second magnetic domains is uneven, for example, if there are many at the ends of the magnetic surface and few at the center, when an external stress is applied, power generation will not occur over the entire region of the magnetostrictive element. It is considered that the power generation output decreases because the contributing magnetization change cannot occur.

In the present invention, it is sufficient that one surface of the magnetostrictive element is a magnetic surface that satisfies the above requirements for the ratio and distribution of magnetic domains. However, both sides of the magnetostrictive element may be the magnetic surfaces. If both surfaces of the magnetostrictive element are magnetic surfaces, each magnetic surface independently satisfies the requirements for the magnetic domains described above.

The magnetostrictive element may have a magnetic domain altering surface treatment on its magnetic surface. In the present invention, the “surface treatment portion for changing the magnetic domain” (hereinafter sometimes abbreviated as “surface treatment portion”) means that the first magnetic domain including the 180° domain wall existing on the magnetic surface is reduced and relatively It is possible to increase the proportion of the second domain containing the 90° domain wall at . As described above, the 180° domain wall has a weak effect of contributing to power generation, but the 90° domain wall can improve the power generation efficiency. By adjusting the balance with the proportion of the 90° domain wall, the power output of the magnetostrictive element can be increased.

The surface-treated portion intended for magnetic domain control may also be found on the surface of a general electromagnetic steel sheet (that is, an electromagnetic steel sheet not intended to utilize magnetostrictive properties). However, the surface-treated portion in a general electrical steel sheet is for controlling magnetic domains so as to reduce the amount of magnetostriction for the purpose of noise reduction. Therefore, the surface treatment portion is provided so as to reduce the number of magnetic domains including 90° domain walls and increase the number of magnetic domains including 180° domain walls. The purpose of the further surface treatment is to refine the magnetic domains containing the 180° domain walls in order to reduce core losses. Therefore, a general surface-treated portion found in an electrical steel sheet reduces the proportion of magnetic domains containing 90° domain walls and increases the proportion of magnetic domains containing 180° domain walls. It is intended for opposite magnetic domain control.

The number of surface-treated portions present on the magnetic surface is not particularly limited, and may be one or more. However, the total area of the surface-treated portions present on the magnetic surface is preferably 0.5% or more and 10% or less, more preferably 2.0% or more and 10% or less, with respect to the area of the magnetic surface. The area of the surface-treated portion is based on two-dimensional dimensions that can be confirmed from the surface of the magnetic surface. Therefore, when the surface-treated portion is a concave portion to be described later, the area of the inner wall of the concave portion is not added to the "total area of the surface-treated portion."

If the total area of the surface-treated portions in the magnetostrictive element is less than 0.5% with respect to the area of the magnetic surface, the ratio of the second magnetic domain may not be 50% or more. In particular, it is sometimes difficult to reduce the proportion of the first magnetic domain to 70% or less, so the total area of the surface-treated portion is preferably 0.5% or more. Further, the effect of magnetic domain control due to the presence of the surface-treated portion is maximized when the total area of the surface-treated portion is 10%. less.

Although there is no particular limitation on such a surface treatment portion, examples thereof include recesses and residual stress portions.

It is thought that the provision of the concave portion on the magnetic surface of the magnetostrictive element increases the magnetostatic energy of the side surface of the concave portion, and in order to reduce the energy, the second magnetic domain consisting of only the 90° domain wall is generated on the side surface of the concave portion. . As a result, it is considered that the ratio of the second magnetic domain increases and the power generation output increases. In the present invention, the second magnetic domain is a magnetic domain including a 90° domain wall, but naturally a magnetic domain composed only of a 90° domain wall is also the second magnetic domain. Since the second magnetic domain consisting only of the 90° domain wall does not include the 180° domain wall, by forming about 30% of the magnetic domain consisting of only the 90° domain wall with the concave portion, the ratio of the first magnetic domain is reduced. can be reduced to 70% or less.

If the surface-treated portion is a concave portion, the magnetic domain in the concave portion cannot be observed. Therefore, the ratio of the first magnetic domain and the ratio of the second magnetic domain do not include the magnetic domain in the concave portion. Therefore, the ratio of the second magnetic domain never reaches 100%.

When there are two or more recesses, the area of the opening of one recess is not particularly limited, but it is preferably 0.02% or more, more preferably 0.2% or more, relative to the area of the magnetic surface. If the area of the opening is less than 0.02%, the effect of increasing the ratio of the second magnetic domain to 50% or more may be insufficient. In particular, it may be difficult to reduce the first magnetic domain to 70% or less.

Although the depth of the concave portion is not particularly limited, it is preferably 0.03 t or more and 0.4 t or less, more preferably 0.1 t or more and 0.4 t or less with respect to the thickness t of the magnetostrictive element. If the depth of the concave portion is less than 0.03t, it may be difficult to increase the magnetic flux density improvement ΔB to 30% or more. Also, even if the depth of the concave portion exceeds 0.4t, the change in the proportion of the first magnetic domain and the proportion of the second magnetic domain is small. Furthermore, if the depth of the concave portion exceeds 0.4t, the strength of the magnetostrictive element itself is lowered, and the element itself may be destroyed when external stress is repeatedly applied, which is not preferable.

Although the recesses exert their effects when they are locally present at arbitrary locations on the magnetic surface, they are preferably arranged in a dotted pattern or a linear pattern. As described above, when recesses are formed on the magnetic surface, magnetic poles are generated on the surfaces of the recesses perpendicular to the magnetic surface, and the magnetic poles are extinguished to form the second magnetic domains in order to reduce the static magnetic energy. Since this effect is exerted by the presence of the recesses locally at arbitrary locations on the magnetic surface, when the recesses are arranged in a dotted pattern, the interaction between the adjacent second magnetic domains works effectively. It becomes possible to effectively increase the ratio of the second magnetic domain. Further, if the concave portion is linear, that is, groove-shaped, the interaction between the second magnetic domains can be further enhanced, and the ratio of the second magnetic domains can be further effectively increased, which is more preferable.

The angle of the longitudinal center line of the dotted-line or linear recess is preferably 0° or more and 90° or less, and 40° or more and 90° or less with respect to the longitudinal direction of the magnetostrictive element for power generation. is more preferred. With such an angle, the ratio of the first magnetic domains, the ratio of the second magnetic domains, and the uniformity of the distribution of the second magnetic domains on the magnetic surface can be made to satisfy the requirements of the present invention.

When there are two or more dot-sequence or linear recesses, the distance (that is, the pitch) between the center lines of two adjacent dot-sequence or linear recesses is preferably 1 mm or more and 7 mm or less. , 2 mm or more and 7 mm or less. With such a pitch, the ratio of the first magnetic domains, the ratio of the second magnetic domains, and the uniformity of the distribution of the second magnetic domains on the magnetic surface can be made to satisfy the requirements of the present invention.

When the recesses are arranged in a dotted line, the distance (that is, the pitch) between two adjacent recesses in the same row is preferably 0.1 mm or more and 1.0 mm or less, and 0.4 mm or more and 1.0 mm or less. It is more preferable to have With such a pitch, the ratio of the first magnetic domains, the ratio of the second magnetic domains, and the uniformity of the distribution of the second magnetic domains on the magnetic surface can be made to satisfy the requirements of the present invention.

When the concave portion is linear, the width thereof is preferably 10 μm or more and 200 μm or less, more preferably 50 μm or more and 200 μm or less. With such a width, the ratio of the first magnetic domains, the ratio of the second magnetic domains, and the uniformity of the distribution of the second magnetic domains of the magnetic surface can be made to satisfy the requirements of the present invention.

The area, width and depth of the opening of the recess can be measured using a digital microscope.

The surface treated portion may be a residual stress portion. The presence of the residual stress portion on the magnetic surface of the magnetostrictive element makes it possible to control the balance between the first magnetic domain and the second magnetic domain of the present invention, as in the case of the presence of the recess. Specifically, when a local stress portion is provided on the magnetic surface, local compressive stress is introduced to the surface of the magnetic surface, generating a magnetic domain including a 90° domain wall. As a result, it is thought that the ratio of magnetic domains containing 90° domain walls increases and the power output increases. In particular, when the component of the residual stress that is substantially parallel to the magnetic plane is compressive stress, the formation of the second magnetic domain is facilitated.

When the surface-treated portion is the residual stress portion, the magnetic domain in the residual stress portion can be observed unlike the concave portions. Therefore, the above ratio of the first magnetic domain and the ratio of the second magnetic domain include the magnetic domain in the residual stress portion, and the ratio of the second magnetic domain may be 100%.

The shape of the residual stress portion is not particularly limited, and is preferably circular or elliptical. The surface range of the residual stress portion on the magnetic surface (that is, the diameter or major axis of the residual stress portion observed on the magnetic surface) is not particularly limited, but is preferably 50 μm or more and 500 μm or less, and 200 μm or more. 500 μm or less is more preferable. If the range of the residual stress portion is less than 50 μm, it may be difficult to increase the margin of improvement ΔB of the magnetic flux density to 30% or more. Moreover, even if the range of the residual stress portion exceeds 500 μm, the change in the proportion of the first magnetic domain and the proportion of the second magnetic domain is considered to be small.

Although the depth of the residual stress portion is not particularly limited, it is preferably 0.1 t or more and 0.7 t or less, more preferably 0.3 t or more and 0.7 t or less, with respect to the thickness t of the magnetostrictive element. If the depth of the residual stress portion is less than 0.1t, it may be difficult to increase the margin of improvement ΔB of the magnetic flux density to 30% or more. Also, even if the depth of the residual stress portion exceeds 0.7t, it is considered that the change in the proportion of the first magnetic domain and the proportion of the second magnetic domain is reduced.

The range and depth of the residual stress portion can be measured by the X-ray residual stress measurement method. For example, the range of residual stress on the sample surface is measured by shifting the residual stress in the longitudinal direction and width direction of the sample at a pitch of 10 μm from the center position where the laser is irradiated. Find the distribution of directions. As for the depth, chemical etching is performed at a pitch of 10 μm in the depth direction from the surface, and residual stress is repeatedly measured at positions dug down to determine the distribution of the residual stress in the depth direction. Comparing these results with the value of the residual stress of the part not irradiated with the laser (for example, the middle position of the irradiated part), ± 10% for the part not irradiated with the laser Let the part with the above change be a residual stress part.

Although the residual stress portion exerts its effect when it is locally present at an arbitrary location on the magnetic surface, it is preferable that the residual stress portion be arranged in a dotted line or a line. Similar to the concave portion, the effect of forming the second magnetic domain by the residual stress portion is that when the residual stress portion is arranged in a dotted pattern, the interaction between the adjacent second magnetic domains works effectively to form the second magnetic domain. It becomes possible to effectively increase the ratio. Further, if the residual stress portion is linear, the interaction between the second magnetic domains can be further enhanced, and the ratio of the second magnetic domains can be further effectively increased, which is more preferable.

The angle of the longitudinal center line of the dotted or linear residual stress portion is preferably 0° or more and 90° or less, more preferably 40° or more and 90° or less, with respect to the longitudinal direction of the magnetostrictive element for power generation. It is more preferable to have With such an angle, the ratio of the first magnetic domains, the ratio of the second magnetic domains, and the uniformity of the distribution of the second magnetic domains on the magnetic surface can be made to satisfy the requirements of the present invention.

When there are two or more dot-sequence or linear residual stress portions, the distance (i.e., pitch) between the center lines of two adjacent dot-sequence or linear residual stress portions is 1 mm or more and 7 mm or less. It is preferable that there is, and it is more preferable that there is 2 mm or more and 7 mm or less. With such a pitch, the ratio of the first magnetic domains, the ratio of the second magnetic domains, and the uniformity of the distribution of the second magnetic domains on the magnetic surface can be made to satisfy the requirements of the present invention.

When the residual stress portions are in the form of a dotted line, the distance (that is, the pitch) between two adjacent residual stress portions in the same line is preferably 0.1 mm or more and 1 mm or less, and 0.4 mm or more and 1.0 mm. The following are more preferable. With such a pitch, the ratio of the first magnetic domains, the ratio of the second magnetic domains, and the uniformity of the distribution of the second magnetic domains on the magnetic surface can be made to satisfy the requirements of the present invention.

The surface-treated portion present on the magnetic surface of the magnetostrictive element of the present invention may be of only one type, or may be of a plurality of types. For example, both recesses and residual stress portions may be present in the magnetic surface of the magnetostrictive element.

The Fe-based magnetostrictive alloy constituting the magnetostrictive element of the present invention is not particularly limited, but an alloy having magnetostrictive properties and known to be used as a magnetostrictive element can be used. Among such alloy systems, those whose crystal orientation is controlled by a rolling method or a single crystal growth method are known. By controlling the ratio of the two magnetic domains, the power output can be further increased. Specific examples of Fe-based magnetostrictive alloys include Fe--Co-based alloys that are relatively inexpensive and can be rolled, and Fe--Ga alloys that have a high magnetostriction but are relatively expensive, brittle, and difficult to roll. , and Fe—Al alloys.

Further, the Fe-based magnetostrictive alloy forming the magnetostrictive element preferably has a saturation magnetostriction value λs of 20×10 ⁻⁶ or more, more preferably 50×10 ⁻⁶ or more. If the saturation magnetostriction value λs is less than 20×10 ⁻⁶ , the magnetization in the magnetostrictive element is unlikely to change due to the inverse magnetostriction effect when an external stress is applied, which is undesirable because the power generation output decreases. On the other hand, if the saturation magnetostriction value λs is 20×10 ⁻⁶ or more, the effect of the present invention works more effectively as an effect of assisting the magnetization change due to the inverse magnetostriction effect, so an improvement in power generation output is expected.

Incidentally, the saturation magnetostriction value λs can be measured by a strain gauge method. A strain gauge is attached to one side of the sample at approximately the center of the sample so that the length of the gauge is parallel to the longitudinal direction of the sample. Apply a magnetic field in the longitudinal direction of the sample _and measure the magnetic field dependence of the strain. _⊥ and obtain λs of the sample from λs=2/3( _λ∥ - _λ⊥ ).

As an index for evaluating the performance of the magnetostrictive element, the magnetic flux density change ΔB of the element that occurs when an external stress is applied to the magnetostrictive element can be used. A method for measuring ΔB (unit: mT or T) is as follows.
A magnetostrictive element with a cross-sectional area S is inserted into a coil with N turns to apply an external stress. At this time, if the magnetic flux density ΔB changes during the time Δt, a voltage of V=−N (S·ΔB/Δt) is generated in the coil. Therefore, ΔB can be obtained as a time integral value of the voltage signal generated in the coil. The performance index of the magnetostrictive vibration power generation element was evaluated as the total voltage generated during Δt. That is, it was evaluated as a change ΔB in the magnetic flux density, which is the time integrated value of the voltage. ΔB can be measured by connecting the voltage generated in the coil to a flux meter.

2. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a magnetostrictive element for power generation according to the invention described above. Specifically, the manufacturing method includes the following steps.
First step: providing a plate-shaped magnetostrictive material made of an Fe-based magnetostrictive alloy.
Second step: At least one surface of the plate-shaped magnetostrictive material is subjected to a magnetic domain altering surface treatment to obtain a surface-treated magnetic surface.

In the first step, a plate-like magnetostrictive material made of an Fe-based magnetostrictive alloy is provided. The Fe-based magnetostrictive alloy as a starting material is not particularly limited, and is the same as the Fe-based magnetostrictive alloy constituting the magnetostrictive element of the present invention. Such alloys can be produced by known methods, such as the examples herein. Moreover, the plate-like magnetostrictive material provided in the first step may be commercially available for magnetostrictive elements for power generation. By subjecting such a magnetostrictive element to the second step, which will be described later, the power output can be increased.

The ratio of the first magnetic domain and the second magnetic domain of the plate-shaped magnetostrictive material provided in the first step is not particularly limited. Anything that satisfies

In the second step, at least one surface of the plate-shaped magnetostrictive material is subjected to a magnetic domain altering surface treatment (hereinafter sometimes abbreviated as "surface treatment") to obtain a surface-treated magnetic surface. In the present invention, the surface treatment for changing the magnetic domain means that the first magnetic domain including the 180° domain wall present on the magnetic surface can be reduced, and the proportion of the second magnetic domain including the 90° domain wall can be relatively increased. is preferred. As described above, the 180° domain wall has a weak effect of contributing to power generation, but the 90° domain wall can improve the power generation efficiency. By adjusting the balance with the proportion of the 90° domain wall, the power output of the magnetostrictive element can be increased.

The surface treatment performed in the second step is not particularly limited, but it is preferably at least one selected from formation of recesses and application of residual stress. Only one type of surface treatment may be used, or a plurality of types may be used. For example, the formation of recesses and the application of residual stress can be performed on one magnetic surface.

The present invention relatively improves the power generation output of the magnetostrictive element by forming recesses or residual stress portions on the surface of the magnetostrictive material to control the magnetic domain structure. Therefore, it is possible to improve the power generation output even with Fe--Co alloys that are relatively inexpensive and can be rolled, or Fe--Ga alloys that are relatively expensive and brittle and difficult to roll. .

There is no particular limitation on the method of forming the recesses on at least one surface of the plate-shaped magnetostrictive material, and the recesses can be formed by a known method used for surface treatment of steel plates. For example, the recesses can be formed by electrolytic etching, chemical etching, electrical discharge machining, or the like.

It is preferable to form the recesses by the above method so that the recesses are formed in the shape described above in relation to the magnetostrictive element of the present invention. For example, in a method in which a copper electrode with a convex portion having a shape opposite to the shape of the concave portion to be formed is produced, and the electrode is used to perform electrical discharge machining to form a concave portion in the desired shape, the size of the copper electrode can be determined with precision. It is possible to accurately reproduce the dimensions of the width and depth of the recess by making it well.

There is no particular limitation on the method of forming the residual stress portion on at least one surface of the plate-shaped magnetostrictive material, and any known residual stress imparting method used for surface treatment of steel plates can be used. For example, the residual stress portion can be formed by laser irradiation.

Residual stress is preferably applied by the method described above so that the residual stress portion described above in relation to the magnetostrictive element of the present invention is formed. For example, by changing the spot diameter, output, and pulse width of the laser, it is possible to adjust the range on the sample surface where residual stress is generated, the range in the depth direction, the magnitude of residual stress, etc. .

Incidentally, the surface treatment for the purpose of magnetic domain control may be applied to a general electromagnetic steel sheet (that is, an electromagnetic steel sheet whose magnetostrictive characteristics are not intended to be used). However, the surface treatment of a general electrical steel sheet is intended to control the magnetic domains so as to reduce the amount of magnetostriction for the purpose of noise reduction. To that end, the surface treatment is performed so as to reduce the magnetic domains containing 90° domain walls and increase the magnetic domains containing 180° domain walls. The purpose of further surface treatments is to refine the magnetic domains containing the 180° domain walls in order to reduce core losses. Therefore, a general surface treatment performed on an electrical steel sheet reduces the proportion of magnetic domains containing 90° domain walls and increases the proportion of magnetic domains containing 180° domain walls. is intended for opposite domain control.

The total area of the surface-treated portions formed on the magnetic surface by the surface treatment in step 2 is preferably 0.5% or more and 10% or less of the area of the magnetic surface. When there are a plurality of surface-treated portions, the total area thereof is preferably within the above range. The area of each surface-treated portion is based on two-dimensional dimensions that can be confirmed from the surface of the magnetic surface. Therefore, when the surface-treated portion is a concave portion, which will be described later, the depth, the area of the inner wall, etc. shall not be added to the "total area of the surface-treated portion."

By the surface treatment, the ratio of the total area of the first magnetic domain including the 180° domain wall to the area of the surface-treated magnetic surface is 0% or more and 70% or less, and the total area of the second magnetic domain including the 90° domain wall is 50% or more and 100% or less, and the distribution of the second magnetic domains is uniform over the entire magnetic surface. Here, the ratio of the total area of the first magnetic domains, the ratio of the total area of the second magnetic domains, and the preferred numerical ranges of the distribution of the second magnetic domains are as described for the magnetostrictive element of the present invention. Moreover, the above ratio and distribution are values measured by the same method as described for the magnetostrictive element of the present invention.

3. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power generator including the magnetostrictive element for power generation of the present invention described above.
The structure of the power generating device of the present invention is not particularly limited as long as the above-described magnetostrictive element for power generation of the present invention is used as the magnetostrictive element. can be done.

For example, there is a power generator including the magnetostrictive element of the present invention, a coil wound therearound, a magnet, a frame, and a weight attached to the frame. In such a device, the magnetic lines of force of the magnet pass through the frame and the magnetostrictive element to form a magnetic circuit. The vibration of the weight causes the frame to vibrate, and by applying tensile force and compressive force to the magnetostrictive element, the magnetization of the magnetostrictive element is changed by the inverse magnetostrictive effect, and an induced current (or induced voltage) can be generated in the coil. .

At this time, on the magnetic surface of the magnetostrictive element of the present invention, the ratio of the 180° domain wall and the ratio of the 90° domain wall are well balanced as described above, so that a high power output can be obtained.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these.

(Example 1)
Magnetostrictive element made of Fe—Co alloy having recesses (1) Manufacture of alloy Electrolytic iron with a purity of 99.98% and metal Co with a purity of 99.9% were arc-cured with a composition of Fe-70.6 mass% Co. It melted and the button ingot of 200g was produced. The button ingot had a diameter of 60 mm and a thickness of about 10 mm. This button ingot was cut into two lines in the plate thickness direction, and cut into rectangular rod-shaped samples having a width of 10 mm and a length of 60 mm. After that, the square bar-shaped sample was held at 1100° C. for 1 hour in an Ar atmosphere, cooled to 800° C. at 300° C./h, held at 800° C. for 3 hours, and cooled to room temperature at 50° C./h. The square rod-shaped sample subjected to such heat treatment was cold-rolled from a plate thickness of 10 mm to 0.52 mm to produce a cold-rolled plate.

After cutting a plurality of sheets with a length of 25 mm in the cold rolling direction and a width of 6.5 mm in the width direction from the cold-rolled sheet, the temperature was raised to 800 ° C. at 20 ° C./min in a vacuum, and after holding at 800 ° C. for 3 hours, 20 The sample was cooled to room temperature at a rate of °C/min and subjected to recrystallization treatment, and was used as a sample to be subjected to surface treatment for magnetic domain modification.
The saturation magnetostriction value λs of the obtained sample was measured by the method described later and found to be 88×10 ⁻⁶ .

(2) Formation of Concave Grooves were formed on the surface of the recrystallized sample obtained in (1) above by using electrical discharge machining. Specifically, the shape (width and depth) of the recesses shown in the table is opposite to the shape (width and depth) of the recesses. A recess of a desired shape was formed so as to form an angle.

(3) Evaluation method The following evaluations were performed on the samples before surface treatment and the samples after surface treatment.

(3-1) Measurement of Saturation Magnetostriction λs The saturation magnetostriction λs was measured by the strain gauge method before the sample obtained in (1) above was subjected to the surface treatment for changing the magnetic domain. A strain gauge was attached to one side surface of a sample having a length of 25 mm and a width of 6.5 mm so that the length direction of the gauge was parallel to the longitudinal direction of the sample, approximately at the center position of the sample. Apply a magnetic field in the longitudinal direction of the sample _and measure the magnetic field dependence of the strain. When _⊥ , λs of the sample was obtained from λs=2/3( _λ∥ − _λ⊥ ).

(3-2) Measurement of first magnetic domain ratio and second magnetic domain ratio At a total of three locations: a location near the center in the longitudinal direction and the width direction perpendicular to it, an approximate center position between the longitudinal ends and the center, and an approximate center position between the width direction ends and the center , the area corresponding to So of each observed portion was determined so that the total number of the first and second magnetic domains was about 100. The areas of the first magnetic domain and the second magnetic domain were obtained, the respective ratios were calculated, and the average value of the three sites was obtained. Before the observation, AC demagnetization was performed at 50 Hz, and the observation was made in a state where no external stress was applied.

(3-3) Evaluation of the uniformity of the distribution of the second magnetic domain Five straight lines of the same length are randomly arranged vertically, horizontally, and diagonally on the image of the magnetic domain taken by the Kerr effect magnetic domain observation device. I pulled like Specifically, one straight line passing through the center of the sample was drawn in the longitudinal direction of the sample, and the remaining four lines were drawn through the center of the sample at 36° to each other. For each straight line, the pattern straddling the second magnetic domain was observed, and the number of times each straight line straddled the second magnetic domain was recorded. At this time, when the number of crossing over the second magnetic domain is the same for all five straight lines, or when the maximum and minimum values of crossing over the second magnetic domain satisfy the relationship of the following formula (1): , the distribution of the second magnetic domain was evaluated as "uniform".
(N1-N2)/N1≦0.5 (1)
In the formula, N1 is the maximum number of times the straight line straddles the second magnetic domain, and N2 is the minimum number of times the straight line straddles the second magnetic domain.

(3-4) Performance Evaluation of Magnetostrictive Element A tensile stress and a compressive stress were applied in the longitudinal direction of a sample having a length of 25 mm and a width of 6.5 mm, and a change ΔB in the magnetic flux density of the sample was measured. Specifically, a sample with a length of 25 mm was inserted into a coil formed by winding 3,000 turns of a copper wire of 50 μm around an acrylic bobbin having an inner space of 8 mm in width, 4 mm in height, and 10 mm in length. Next, the change ΔB in the magnetic flux density was measured by connecting a flux meter to the coil when a tensile stress of 25 MPa was applied to a compressive stress of 25 MPa. However, the sample was sandwiched between acrylic plates having a thickness of 1 mm so that the sample would not warp when the compressive stress was applied. At this time, the coil and the sample were placed in a solenoid coil so that a DC bias magnetic field could be applied to the sample, and ΔB was obtained when the bias magnetic field maximized ΔB.

Table 1 below shows the shape (width, pitch, depth, angle) and ratio of the concave portions that are the surface treatment portions, the ratio of the first magnetic domain to the second magnetic domain, the uniformity of the second magnetic domain, and ΔB. .

As is clear from the results in Table 1, the ratio of the first magnetic domain to the second magnetic domain is outside the scope of the present invention, and the value of equation (1), which is an index of the uniformity of the distribution of the second magnetic domain, is 0.5. The non-uniform Comparative Example 1 sample greater than 5 had a ΔB of 30 mT. However, in Invention Examples 1-1 to 1-19 in which the same sample as in Comparative Example 1 was surface-treated, the ratio of the first magnetic domain was 0% or more and 70% or less, and the ratio of the second magnetic domain was 50% or more and 100%. Then, the value of formula (1) becomes 0.5 or less (that is, the distribution of the second magnetic domain is uniform), and ΔB is improved by 20% or more. Furthermore, in invention examples 1-5 to 1-17 in which the first magnetic domain is 10% or more and 50% or less, the second magnetic domain is 70% or more and 100% or less, and the value of formula (1) is 0.3 or less, ΔB is improved by more than 50%.

On the other hand, in Comparative Example 2, although the surface treatment was performed, the groove width of the formed groove-shaped recess was as narrow as 5 μm, and the groove pitch was as wide as 2.5 mm with respect to the narrow groove width. As a result, the ratio of the first magnetic domain decreased, the ratio of the second magnetic domain slightly increased, and the value of equation (1) decreased, but none of them fell within the scope of the present invention. In such samples outside the scope of the present invention, almost no improvement in ΔB was observed.

As is clear from Invention Examples 1-1 to 1-19, ΔB was improved by 20% or more when the angle θ of the longitudinal direction of the recess with respect to the longitudinal direction of the sample was within the range of 10° or more and 90° or less. Furthermore, when the angle θ is in the range of 40° or more and 90° or less (Invention Examples 1-1 to 1-17), compared to Invention Examples 1-18 and 1-19 in which the angle θ is 10° or more and less than 40° , ΔB increased.

In addition, invention examples 1-2 to 1-11 in which the width of the concave portion is 10 μm or more and 200 μm or less, the pitch is 1 mm or more and 7 mm or less, the depth is 0.03 t or more and 0.4 t or less, and the angle θ is 10° or more and 90° or less. And invention examples 1-13 to 1-19 improved ΔB by 30% or more. This improvement rate of ΔB was higher than that of Invention Example 1-1 in which the width of the concave portion was less than 10 μm, the pitch was less than 1 mm, and the depth was less than 0.03 t. Furthermore, compared to Invention Example 1-12, in which the width of the concave portion exceeded 200 μm and the depth exceeded 0.40 t, the durability against vibration was excellent.

Invention Examples 1-5 to 1-11 in which the width of the concave portion is 50 μm or more and 200 μm or less, the pitch is 2 mm or more and 7 mm or less, the depth is 0.1 t or more and 0.4 t or less, and the angle θ is 40° or more and 90° or less; In invention examples 1-13 to 1-17, ΔB was improved by 50% or more. As a result, the angle θ of the recess is less than 40°, the ratio of the first magnetic domain and the second magnetic domain, and the distribution of the second magnetic domain (the value of formula (1)) are within the scope of the present invention, but it is preferable. It was an excellent value compared to Inventive Examples 1-18 and 1-19, which were out of range.

Furthermore, from a comparison between Invention Example 1-4, in which the ratio of the recesses to the area of the magnetic surface is less than 2%, and Invention Examples 1-5 to 1-14, in which the ratio is 2% or more, the ratio of the recesses is 2% or more. and ΔB are improved by more than 50%. In addition, from a comparison of Invention Example 1-13 in which the ratio is 10% or less and Invention Example 1-14 in which the ratio exceeds 10%, even if the ratio of concave portions exceeds 10%, ΔB increases as much as Invention Example 1-13. I know you won't.

(Example 2)
1. Magnetostrictive element made of Fe—Co alloy having residual stress portion (1) Manufacture of alloy As in Example 1, a sample was prepared for surface treatment for changing the magnetic domain.

(2) Formation of residual stress portion A stress residual portion was introduced into the surface of the recrystallized sample obtained in (1) above using a known laser irradiation technique. Specifically, using a YAG laser, the diameter of the laser spot that hits the sample is adjusted to about 10 to 100 μm with a condenser lens, and the average energy density is about 1 to 4 mJ/mm ² for laser irradiation. did By changing the laser spot diameter, average energy density, and irradiation time, the magnitude of residual stress is changed, and the range on the sample surface where residual stress is generated and the range in the sample depth direction are shown below. A desired shape of the residual stress portion was formed so as to change as shown in the table and to have the pitch and angle shown in the table.

(3) Evaluation method A sample before surface treatment and a sample after surface treatment were evaluated in the same manner as in Example 1 (3). Furthermore, the range and depth of the residual stress portion were measured by the following method.

(3-5) Evaluation method of residual stress Residual stress was measured using an X-ray residual stress measurement method. The range of residual stress on the sample surface is measured by shifting the residual stress in the longitudinal direction and width direction of the sample from the center position where the laser is irradiated at a pitch of 10 μm. distribution was obtained. Chemical etching was performed from the surface in the depth direction at a pitch of 10 μm, and the residual stress was measured at dug-down positions repeatedly to obtain the distribution of the residual measurement in the depth direction. Comparing these results with the value of the residual stress of the part not irradiated with the laser (for example, the middle position of the irradiated part), ± 10% for the part not irradiated with the laser The portions with the above changes were defined as the magnetic domain altering surface treatment portions, and the measurement results thereof were used as the evaluation results of the residual stress. The measured laser irradiation sites were the longitudinal direction of the sample and the site near the center in the width direction perpendicular to it, the approximately center position between the longitudinal end and the center, and the width direction end and center. A total of 3 positions were set at approximately the center position between . One place was selected for each site, the residual stress was measured, and the average was obtained.

(3-6) Ratio of the area of the residual stress part Since the shape of the residual stress part was almost circular, the range of the residual stress part was defined as the diameter of one residual stress part, and the area of one residual stress part was calculated. rice field. Then, the area was multiplied by the total number of residual stress portions to obtain the total area of the residual stress portions, and the total area was divided by the area of the magnetic surface to determine the ratio of the area of the residual stress portions.

Table 2 below shows the shape (range, depth, pitch, angle) of the residual stress portion, which is the surface treatment portion, the ratio thereof, the ratio of the first magnetic domain to the second magnetic domain, the uniformity of the second magnetic domain, and ΔB. Indicated.

As is clear from the results in Table 2, the ratio of the first magnetic domain to the second magnetic domain is outside the scope of the present invention, and the value of equation (1), which is an index of the uniformity of the distribution of the second magnetic domain, is 0.5. The non-uniform Comparative Example 1 sample greater than 5 had a ΔB of 30 mT. However, in invention examples 2-1 to 2-14 in which the same samples as in comparative example 1 were surface-treated, the ratio of the first magnetic domain was 0% or more and 70% or less, and the ratio of the second magnetic domain was 50% or more and 100%. Then, the value of formula (1) becomes 0.5 or less (that is, the distribution of the second magnetic domain is uniform), and ΔB is improved by 20% or more. Furthermore, in invention examples 2-5 to 2-12 in which the first magnetic domain is 10% or more and 50% or less, the second magnetic domain is 70% or more and 100% or less, and the value of formula (1) is 0.3 or less, ΔB is improved by more than 60%.

As is clear from Invention Examples 2-1 to 2-14, when the angle θ of the dot-sequence direction of the residual stress portion with respect to the longitudinal direction of the sample is in the range of 10° or more and 90° or less, ΔB is 20%. More than improved. Furthermore, when the angle θ is in the range of 40° or more and 90° or less (Invention Examples 2-1 to 2-12), compared to Invention Examples 2-13 and 2-14 in which the angle θ is 10° or more and less than 40° , ΔB increased.

In addition, the range of residual stress is 50 μm or more and 500 μm or less, the depth is 0.1 t or more and 0.7 t or less, the pitch in the longitudinal direction of the sample is 1 mm or more and 7 mm or less, and the pitch in the width direction of the sample is 0.10 mm or more and 1.0 mm or less. In Examples 2-2 to 2-14, ΔB was improved by 30% or more. This improvement rate of ΔB is higher than that of Invention Example 2-1 in which the range of residual stress is less than 50 μm, the depth is less than 0.1 t, the pitch in the longitudinal direction of the sample is less than 1 mm, and the pitch in the width direction of the sample is less than 0.10 mm. rice field.

Range of residual stress is 200 μm or more and 500 μm or less, depth of residual stress is 0.3 t or more and 0.7 t or less, pitch in the longitudinal direction of the sample is 2 mm or more and 7 mm or less, pitch in the width direction of the sample is 0.40 mm or more and 1.0 mm or less, angle In invention examples 2-5 to 2-8 in which θ is 40° or more and 90° or less, ΔB increased by 60 to 130%. However, in Invention Example 2-9 where the range of residual stress is over 500 μm, the depth of residual stress is over 0.7 t, the pitch in the longitudinal direction of the sample is over 7 mm, and the pitch in the width direction of the sample is over 1.0 mm, Invention Example 2 No significant change in ΔB compared to -8 was observed.

Furthermore, from a comparison of Invention Example 2-2 in which the ratio of the residual stress portion to the area of the magnetic surface is less than 2% and Invention Examples 2-3 to 2-9 in which the ratio is 2% or more, it is found that the ratio of the residual stress portion is 2%. % or more, the improvement rate of ΔB increased.

(Example 3)
Magnetostrictive element made of Fe-Al alloy having recesses (1) Manufacture of alloy Electrolytic iron with a purity of 99.98% and metal Al with a purity of 99.9% were arc-melted with a composition of Fe-13 mass% Al. A button ingot of 200 g was produced. The button ingot had a diameter of 60 mm and a thickness of about 10 mm. A button ingot is cut in the plate thickness direction into a plate shape having a length of about 60 mm, a width of about 10 mm, and a thickness of 0.5 mm. cut out to The cut multiple plates were heated to 1000° C. at 20° C./min in vacuum, held at 1000° C. for 3 hours, cooled to room temperature at 20° C./min, and subjected to surface treatment for magnetic domain modification after heat treatment. It was used as a sample for application.
When the saturation magnetostriction value λs of the obtained sample was measured in the same manner as in Example 1, it was 40×10 ⁻⁶ .

(2) Formation of recesses As in Example 1, recesses were formed on the surface of the sample to be subjected to the surface treatment for changing magnetic domains.

(3) Evaluation method The samples before surface treatment and the samples after surface treatment were evaluated in the same manner as in Example 1.

Table 3 below shows the shape (width, pitch, depth, angle) and ratio of the concave portions that are the surface treatment portions, the ratio of the first magnetic domain to the second magnetic domain, the uniformity of the second magnetic domain, and ΔB. .

As is clear from the results in Table 3, the ratio of the first magnetic domain to the second magnetic domain is outside the scope of the present invention, and the value of formula (1), which is an index of the uniformity of the distribution of the second magnetic domain, is 0.5. The sample of Comparative Example 3, which was greater than 5 and non-uniform, had a ΔB of 14 mT. However, in Invention Examples 3-1 to 3-19 in which the same samples as in Comparative Example 3 were surface-treated, the ratio of the first magnetic domain was 0% or more and 70% or less, and the ratio of the second magnetic domain was 50% or more and 100%. Then, the value of formula (1) becomes 0.5 or less (that is, the distribution of the second magnetic domains is uniform), and ΔB is improved by 2.80% or more. Furthermore, in invention examples 3-5 to 3-17 in which the first magnetic domain is 10% or more and 50% or less, the second magnetic domain is 70% or more and 100% or less, and the value of formula (1) is 0.3 or less, ΔB is 7. Improved by more than 10%.

On the other hand, in Comparative Example 4, although the surface treatment was performed, the groove width of the formed groove-shaped recess was as narrow as 5 μm, and the groove pitch was as wide as 2.5 mm with respect to the narrow groove width. As a result, the ratio of the first magnetic domain decreased, the ratio of the second magnetic domain increased, and the value of equation (1) decreased, but none of them fell within the scope of the present invention. In such samples outside the scope of the present invention, almost no improvement in ΔB was observed.

As is clear from Invention Examples 3-1 to 3-19, when the angle θ of the longitudinal direction of the recess with respect to the longitudinal direction of the sample is in the range of 10° or more and 90° or less, ΔB is improved by 2.80% or more. bottom. Furthermore, when the angle θ is in the range of 40° or more and 90° or less (Invention Examples 3-1 to 3-17), compared to Invention Examples 3-18 and 3-19 in which the angle θ is 10° or more and less than 40° , ΔB increased.

In addition, invention examples 3-2 to 3-11 in which the width of the concave portion is 10 μm or more and 200 μm or less, the pitch is 1 mm or more and 7 mm or less, the depth is 0.03 t to 0.4 t, and the angle θ is 10° or more and 90° or less, and In invention examples 3-13 to 3-17, ΔB was improved by 2.80% or more. This improvement rate of ΔB was higher than that of Invention Example 3-1 in which the width of the concave portion was less than 10 μm, the pitch was less than 1 mm, and the depth was less than 0.03 t. Furthermore, compared to Invention Example 3-12, in which the width of the concave portion exceeded 200 μm and the depth exceeded 0.40 t, the durability against vibration was excellent.

Invention Examples 3-5 to 3-11 in which the width of the concave portion is 50 μm or more and 200 μm or less, the pitch is 2 mm or more and 7 mm or less, the depth is 0.1 t or more and 0.4 t or less, and the angle θ is 40° or more and 90° or less; In invention examples 3-13 to 3-17, ΔB was improved by 70% or more. As a result, the angle θ of the recess is less than 40°, the ratio of the first magnetic domain and the second magnetic domain, and the distribution of the second magnetic domain (the value of formula (1)) are within the scope of the present invention, but it is preferable. It was an excellent value compared to Invention Examples 3-1, 3-18 and 3-19, which were out of range. Furthermore, compared to Invention Example 3-12, in which the width of the concave portion exceeded 200 μm and the depth exceeded 0.40 t, the durability against vibration was excellent.

Furthermore, from a comparison between Invention Example 3-4 in which the ratio of the recesses to the area of the magnetic surface is less than 2% and Invention Examples 3-5 to 3-14 in which the ratio is 2% or more, the ratio of the recesses is 2% or more. and ΔB improved by more than 70%. In addition, from the comparison between Invention Example 3-13 in which the ratio is 10% or less and Invention Example 3-14 in which the ratio exceeds 10%, even if the ratio of concave portions exceeds 10%, ΔB increases as much as Invention Example 3-13. I know you won't.

(Example 4)
1. Magnetostrictive element made of Fe—Al alloy having residual stress portion (1) Manufacture of alloy As in Example 3, a sample was prepared for surface treatment for changing the magnetic domain.

(2) Formation of Residual Stress Portion As in Example 2, a residual stress portion was formed on the surface of a sample to be subjected to surface treatment for changing magnetic domains.

(3) Evaluation method The samples before surface treatment and the samples after surface treatment were evaluated in the same manner as in Example 2.

Table 4 below shows the shape (range, depth, pitch, angle) and the ratio of the residual stress portion, which is the surface treatment portion, the ratio of the first magnetic domain to the second magnetic domain, the distribution of the second magnetic domain, and ΔB. rice field.

As is clear from the results in Table 4, the ratio of the first magnetic domain to the second magnetic domain is outside the scope of the present invention, and the value of formula (1), which is an index of uniformity of the distribution of the second magnetic domain, is 0.5. The sample of Comparative Example 3, which was greater than 5 and non-uniform, had a low ΔB of 14 mT. However, in Invention Examples 4-1 to 4-14 in which the same sample as in Comparative Example 1 was surface-treated, the ratio of the first magnetic domain was 0% or more and 70% or less, and the ratio of the second magnetic domain was 50% or more and 100%. Then, the value of formula (1) becomes 0.5 or less (that is, the distribution of the second magnetic domains is uniform), and ΔB is improved by 40% or more. Furthermore, in invention examples 4-5 to 4-12 in which the first magnetic domain is 10% or more and 50% or less, the second magnetic domain is 70% or more and 100% or less, and the value of formula (1) is 0.3 or less, ΔB is More than 90% improvement.

As is clear from Invention Examples 4-1 to 4-14, when the angle θ of the dot-sequence direction of the residual stress portion with respect to the longitudinal direction of the sample is in the range of 10° or more and 90° or less, ΔB is 40%. More than improved. Furthermore, when the angle θ is in the range of 40° or more and 90° or less (Invention Examples 4-1 to 4-12), compared to Invention Examples 4-13 and 4-14 in which the angle θ is 10° or more and less than 40° , ΔB increased.

Further, the range of residual stress is 50 μm or more and 500 μm or less, the depth is 0.1 t or more and 0.7 t or less, the sample longitudinal pitch is 1 mm or more and 7 mm or less, and the sample width direction pitch is 0.10 mm or more and 1.0 mm or less, Furthermore, in invention examples 4-2 to 4-14 in which the angle θ is 10° or more and 90° or less, ΔB is improved by 60% or more. This improvement rate of ΔB is higher than that of Invention Example 4-1 in which the range of residual stress is less than 50 μm, the depth is less than 0.1 t, the pitch in the longitudinal direction of the sample is less than 1 mm, and the pitch in the width direction of the sample is less than 0.10 mm. rice field.

Range of residual stress is 200 μm or more and 500 μm or less, depth of residual stress is 0.3 t or more and 0.7 t or less, pitch in the longitudinal direction of the sample is 2 mm or more and 7 mm or less, pitch in the width direction of the sample is 0.40 mm or more and 1.0 mm or less, angle In invention examples 4-5 to 4-8 in which θ is 40° or more and 90° or less, ΔB increased by 90 to 150%. However, in Invention Example 4-9 where the residual stress range is over 500 μm, the residual stress depth is over 0.7 t, the sample longitudinal pitch is over 7 mm, and the sample width direction pitch is over 1.0 mm, Invention Example 4 No significant change in ΔB compared to -8 was observed.

Furthermore, from a comparison of Invention Example 4-2, in which the ratio of the residual stress portion to the area of the magnetic surface is less than 2%, and Invention Examples 4-3 to 4-9, in which the ratio is 2% or more, it is found that the ratio of the residual stress portion is 2%. % or more, the improvement rate of ΔB increased.

(Example 5)
Magnetostrictive element made of Fe—Ga alloy having recesses (1) Manufacture of alloy Electrolytic iron with a purity of 99.98% and metallic Ga with a purity of 99.99% were arc-melted with a composition of Fe-22 mass% Ga. , 200 g button ingots were produced. The button ingot had a diameter of 60 mm and a thickness of about 10 mm. A button ingot is cut in the plate thickness direction into a plate shape having a length of about 60 mm, a width of about 10 mm, and a thickness of 0.5 mm, and a size of 25 mm in length, 6.5 mm in width, and 0.5 mm in thickness is obtained from the plate. cut out to The plurality of cut plates were heated to 1000° C. at 20° C./min in vacuum, held at 1000° C. for 10 hours, cooled to room temperature at 20° C./min, and subjected to surface treatment for changing the magnetic domain after heat treatment. It was used as a sample for application.
When the saturation magnetostriction value λs of the obtained sample was measured in the same manner as in Example 1, it was 153×10 ⁻⁶ .

(2) Formation of recesses As in Example 1, recesses were formed on the surface of the sample to be subjected to the surface treatment for changing magnetic domains.

(3) Evaluation method The samples before surface treatment and the samples after surface treatment were evaluated in the same manner as in Example 1.

Table 5 below shows the shape (width, pitch, depth, angle) and ratio of the concave portions that are the surface treatment portions, the ratio of the first magnetic domain to the second magnetic domain, the uniformity of the second magnetic domain, and ΔB. .

As is clear from the results in Table 5, the ratio of the first magnetic domain to the second magnetic domain is outside the scope of the present invention, and the value of formula (1), which is an index of the uniformity of the distribution of the second magnetic domain, is 0.5. The sample of Comparative Example 5, which was greater than 5 and non-uniform, had a ΔB of 85 mT. However, in Invention Examples 5-1 to 5-19 in which the same samples as in Comparative Example 5 were subjected to surface treatment, the ratio of the first magnetic domain was 0% or more and 70% or less, and the ratio of the second magnetic domain was 50% or more and 100%. Then, the value of formula (1) becomes 0.5 or less (that is, the distribution of the second magnetic domains is uniform), and ΔB is improved by 2.50% or more. Furthermore, in invention examples 5-5 to 5-17 in which the first magnetic domain is 10% or more and 50% or less, the second magnetic domain is 70% or more and 100% or less, and the value of formula (1) is 0.3 or less, ΔB is improved by more than 50%.

On the other hand, in Comparative Example 6, although the surface treatment was performed, the groove width of the formed groove-shaped recess was as narrow as 5 μm, and the groove pitch was as wide as 2.5 mm with respect to the narrow groove width. As a result, the ratio of the first magnetic domain decreased, the ratio of the second magnetic domain slightly increased, and the value of equation (1) decreased, but none of them fell within the scope of the present invention. In such samples outside the scope of the present invention, almost no improvement in ΔB was observed.

As is clear from Invention Examples 5-1 to 5-19, when the angle θ of the longitudinal direction of the recess with respect to the longitudinal direction of the sample is in the range of 10° or more and 90° or less, ΔB is improved by 2.50% or more. bottom. Furthermore, when the angle θ is in the range of 40° or more and 90° or less (Invention Examples 5-1 to 5-17), compared to Invention Examples 5-18 and 5-19 in which the angle θ is 10° or more and less than 40° , ΔB increased.

In addition, invention examples 5-2 to 5-11 in which the width of the concave portion is 10 μm or more and 200 μm or less, the pitch is 1 mm or more and 7 mm or less, the depth is 0.03 t to 0.4 t, and the angle θ is 10° or more and 90° or less, and In invention examples 5-13 to 5-19, ΔB was improved by 30% or more. This improvement rate of ΔB was higher than that of Example 5-1 in which the width of the concave portion was less than 10 μm, the pitch was less than 1 mm, and the depth was less than 0.03 t. Furthermore, compared to Invention Example 5-12 in which the width of the recess exceeded 200 μm and the depth exceeded 0.40 t, the durability against vibration was excellent.

Invention Examples 5-5 to 5-11 in which the width of the concave portion is 50 μm or more and 200 μm or less, the pitch is 2 mm or more and 7 mm or less, the depth is 0.1 t or more and 0.4 t or less, and the angle θ is 40° or more and 90° or less, and In invention examples 5-13 to 5-17, ΔB was improved by 50% or more. As a result, the angle θ of the recess is less than 40°, the ratio of the first magnetic domain and the second magnetic domain, and the distribution of the second magnetic domain (the value of formula (1)) are within the scope of the present invention, but it is preferable. It was an excellent value compared to Inventive Examples 5-18 and 5-19, which were out of range. Furthermore, compared to Invention Example 5-12 in which the width of the recess exceeded 200 μm and the depth exceeded 0.40 t, the durability against vibration was excellent.

Invention Examples 5-5 to 5-11 in which the width of the concave portion is 50 μm or more and 200 μm or less, the pitch is 2 mm or more and 7 mm or less, the depth is 0.1 t or more and 0.4 t or less, and the angle θ is 40° or more and 90° or less, and In invention examples 5-13 to 5-17, ΔB was improved by 50% or more. As a result, the angle θ of the recess is less than 40°, the ratio of the first magnetic domain and the second magnetic domain, and the distribution of the second magnetic domain (the value of formula (1)) are within the scope of the present invention, but it is preferable. It was an excellent value compared to Inventive Examples 5-18 and 5-19, which were out of range.

Furthermore, from a comparison between Invention Example 5-4, in which the ratio of the recesses to the area of the magnetic surface is less than 2%, and Invention Examples 5-5 to 5-14, in which the ratio is 2% or more, the ratio of the recesses is 2% or more. and ΔB improved by more than 50%. In addition, from a comparison of Invention Example 5-13 in which the ratio is 10% or less and Invention Example 5-14 in which the ratio exceeds 10%, even if the ratio of concave portions exceeds 10%, ΔB increases as much as Invention Example 5-13. I know you won't.

(Example 6)
2. Magnetostrictive element made of Fe--Ga alloy having residual stress portion (1) Manufacture of alloy As in Example 5, a sample to be subjected to surface treatment for changing the magnetic domain was prepared.

(2) Formation of Residual Stress Portion As in Example 2, a residual stress portion was formed on the surface of a sample to be subjected to surface treatment for changing magnetic domains.

(3) Evaluation method The samples before surface treatment and the samples after surface treatment were evaluated in the same manner as in Example 2.

Table 6 below shows the shape (range, depth, pitch, angle) and ratio of the residual stress portion, which is the surface treatment portion, the ratio of the first magnetic domain to the second magnetic domain, the distribution of the second magnetic domain, and ΔB. .

As is clear from the results in Table 6, the ratio of the first magnetic domain to the second magnetic domain is outside the scope of the present invention, and the value of formula (1), which is an index of uniformity of the distribution of the second magnetic domain, is 0.5. The sample of Comparative Example 5, which was greater than 5 and non-uniform, had a ΔB of 85 mT. However, in Invention Examples 6-1 to 6-14 in which the same samples as in Comparative Example 5 were surface-treated, the ratio of the first magnetic domain was 0% or more and 70% or less, and the ratio of the second magnetic domain was 50% or more and 100%. Then, the value of formula (1) becomes 0.5 or less (that is, the distribution of the second magnetic domain is uniform), and ΔB is improved by 30% or more. Furthermore, in invention examples 6-5 to 6-12 in which the first magnetic domain is 10% or more and 50% or less, the second magnetic domain is 70% or more and 100% or less, and the value of formula (1) is 0.3 or less, ΔB is improved by more than 60%.

As is clear from Invention Examples 6-1 to 6-14, when the angle θ of the dot-sequence direction of the residual stress portion with respect to the longitudinal direction of the sample is in the range of 10° or more and 90° or less, ΔB is 30%. More than improved. Furthermore, when the angle θ is in the range of 40° or more and 90° or less (Invention Examples 6-1 to 6-12), compared to Invention Examples 6-13 and 6-14 in which the angle θ is 10° or more and less than 40° , ΔB increased.

In addition, the range of residual stress is 50 μm or more and 500 μm or less, the depth is 0.1 t or more and 0.7 t or less, the pitch in the longitudinal direction of the sample is 1 mm or more and 7 mm or less, and the pitch in the width direction of the sample is 0.10 mm or more and 1.0 mm or less. In Examples 6-2 to 6-14, ΔB was improved by 40% or more. This ΔB improvement rate is higher than that of Invention Example 6-1 in which the range of residual stress is less than 50 μm, the depth is less than 0.1 t, the pitch in the longitudinal direction of the sample is less than 1 mm, and the pitch in the width direction of the sample is less than 0.10 mm. rice field.

Range of residual stress is 200 μm or more and 500 μm or less, depth of residual stress is 0.3 t or more and 0.7 t or less, pitch in the longitudinal direction of the sample is 2 mm or more and 7 mm or less, pitch in the width direction of the sample is 0.40 mm or more and 1.0 mm or less, angle In invention examples 6-5 to 6-8 in which θ is 40° or more and 90° or less, ΔB increased by 60 to 80%. However, in Invention Example 6-9 where the range of residual stress is over 500 μm, the depth of residual stress is over 0.7 t, the pitch in the longitudinal direction of the sample is over 7 mm, and the pitch in the width direction of the sample is over 1.0 mm, Invention Example 6 No significant change in ΔB compared to -8 was observed.

Furthermore, when comparing Invention Example 6-2, in which the ratio of the residual stress portion to the area of the magnetic surface is less than 2%, and Invention Examples 6-3 to 6-9, in which the ratio is 2% or more, the ratio of the residual stress portion is 2%. % or more, the improvement rate of ΔB increased.

As shown in Examples 1 and 2 above, the present invention is applicable to Fe—Co alloys that can be produced by cold rolling, which enables mass production. Further, as shown in Examples 5 and 6, the present invention can be applied to Fe--Ga alloys which are brittle and difficult to manufacture by normal hot rolling or cold rolling. Therefore, the production method of the present invention is applicable to stable mass production of magnetostrictive elements for power generation with high power generation output regardless of the magnetostrictive material used as the raw material.

INDUSTRIAL APPLICABILITY According to the present invention, a power generation magnetostrictive element for use in magnetostrictive power generation, which has a high power generation output and can be stably mass-produced, a manufacturing method thereof, and a power generator using the power generation magnetostrictive element are provided. Since the magnetostrictive element for power generation of the present invention has a higher power generation output than conventional magnetostrictive elements, it enables the development of a magnetostrictive power generator useful as a power source for wireless sensor modules in IoT and the like.

1 recess (surface treatment part)
2, 3 region 4 180° domain wall 5 90° domain wall 10 magnetic surface a lengthwise dimension b widthwise dimension

Claims (14)

A plate-shaped magnetostrictive element for power generation made of an Fe-based magnetostrictive alloy,
At least one of the front and back surfaces of the magnetostrictive element for power generation is a magnetic surface on which a first magnetic domain including a 180° domain wall and a second magnetic domain including a 90° domain wall are present,
The ratio of the total area of the first magnetic domains present on the magnetic surface to the area of the magnetic surface is 0% or more and 70% or less, and the ratio of the total area of the second magnetic domains is 50% or more and 100% or less,
the distribution of the second magnetic domains on the magnetic surface is uniform over the entire magnetic surface;
The ratio of the total area of the first magnetic domain, the ratio of the total area of the second magnetic domain, and the distribution of the second magnetic domain are obtained by demagnetizing the magnetic surface of the magnetostrictive element for power generation with an alternating magnetic field and then demagnetizing A value measured by a magneto-optical method with no external stress applied to the surface,
Magnetostrictive element for power generation. the magnetic surface has a magnetic domain altering surface treatment,
2. The magnetostrictive element for power generation according to claim 1, wherein the total area of said magnetic domain altering surface treatment portion is 0.5% or more and 10% or less with respect to the area of said magnetic surface. 3. The magnetostrictive element for power generation according to claim 2, wherein the magnetic domain altering surface treatment portion is at least one selected from a concave portion and a residual stress portion. 4. The magnetostrictive element for power generation according to claim 3, wherein the magnetic domain altering surface treatment portion is a concave portion. 5. The magnetostrictive element for power generation according to claim 4, wherein the depth of said concave portion is 0.03t or more and 0.4t or less with respect to the thickness t of said magnetostrictive element for power generation. 6. The magnetostrictive element for power generation according to claim 4, wherein a plurality of said recesses are arranged in a dotted line, or said recesses are linear. 4. The magnetostrictive element for power generation according to claim 3, wherein the magnetic domain altering surface treatment portion is a residual stress portion. 8. The magnetostrictive element for power generation according to claim 7, wherein the residual stress portion on the surface of the magnetic surface has a diameter or major axis range of 50 μm or more and 500 μm or less. 9. The magnetostrictive element for power generation according to claim 7, wherein the depth of said residual stress portion is 0.1 t or more and 0.7t or less with respect to the thickness t of said magnetostrictive element for power generation. The magnetostrictive element for power generation according to any one of claims 1 to 9, wherein the Fe-based magnetostrictive alloy is an Fe--Ga-based alloy, an Fe--Co-based alloy, or an Fe--Al-based alloy. 11. The magnetostrictive element for power generation according to claim 1, wherein the Fe-based magnetostrictive alloy has a saturation magnetostriction value λs of 20×10 ⁻⁶ or more. Providing a plate-shaped magnetostrictive material made of an Fe-based magnetostrictive alloy,
At least one of the front and back surfaces of the plate-shaped magnetostrictive material is subjected to a surface treatment for changing the magnetic domain to obtain a surface-treated magnetic surface;
including
The magnetic surface has a first magnetic domain including a 180° domain wall and a second magnetic domain including a 90° domain wall,
The ratio of the total area of the first magnetic domains present on the magnetic surface to the area of the magnetic surface is 0% or more and 70% or less, and the ratio of the total area of the second magnetic domains is 50% or more and 100% or less,
the distribution of the second magnetic domains on the magnetic surface is uniform over the entire magnetic surface;
The percentage of the total area of the first magnetic domains, the percentage of the total area of the second magnetic domains, and the distribution of the second magnetic domains are obtained by demagnetizing the magnetic surface of the plate-shaped magnetostrictive material with an alternating magnetic field and then demagnetizing the magnetic A value measured by a magneto-optical method with no external stress applied to the surface,
A method for manufacturing a magnetostrictive element for power generation. 13. The manufacturing method according to claim 12, wherein the magnetic domain altering surface treatment is at least one selected from formation of recesses and application of residual stress. A power generator comprising the magnetostrictive element for power generation according to any one of claims 1 to 11.

Images