Magnetostrictive member and method of manufacturing the same

Abstract

A magnetostrictive member and a method for manufacturing the same are provided, which have a high distortion constant and a high amount of parallel magnetostriction and little variation in the magnetostriction constant and amount of parallel magnetostriction between members. [Solution] The magnetostrictive member is a plate-shaped body made of crystals of an iron-based alloy having magnetostrictive properties, and having a longitudinal and lateral direction. At least one of the front and back surfaces of the plate has grinding marks, a magnetostriction constant of 200 ppm or more, and a parallel magnetostriction amount, which is the amount of magnetostriction when a magnetic field parallel to the longitudinal direction is applied and the amount of magnetostriction in the longitudinal direction is saturated, is 200 ppm or more.

Description

[Technical Field]

[0001] The present invention relates to a magnetostrictive member and a method for manufacturing a magnetostrictive member. [Background technology]

[0002] Magnetostrictive materials have been attracting attention as functional materials. For example, Fe-Ga alloys, which are iron-based alloys, exhibit magnetostrictive and inverse magnetostrictive effects, exhibiting large magnetostriction of approximately 100 to 350 ppm. Therefore, in recent years, they have attracted attention as vibration-powered energy harvesting materials in the energy harvesting field, and are expected to be applied to wearable devices, sensors, and the like. A single crystal growth method using the Czochralski method (hereinafter abbreviated as the "Cz method") is known as a method for producing Fe-Ga alloy single crystals (e.g., Patent Document 1). Other known production methods besides the Cz method include the vertical Bridgman method (VB method) and the vertical gradient freezing method (VGF method) (e.g., Patent Documents 2 and 3).

[0003] Fe-Ga alloys are crystalline <100> The magnetostrictive material of Fe-Ga alloy has an easy axis of magnetization in the direction of the magnetization, and can exhibit large magnetostriction in this direction. <100> Magnetostrictive materials are manufactured by cutting a single crystal portion oriented in a certain direction to the desired size (for example, Non-Patent Document 1). However, since the crystal orientation has a large effect on the magnetostrictive properties, the direction in which the magnetostriction of the magnetostrictive material is required and the direction in which the magnetostriction of the crystal is greatest are also important. <100> It is believed that a single crystal with the same orientation is the best material for the magnetostrictive member.

[0004] Fe-Ga alloy single crystals are <100> When a magnetic field is applied parallel to the direction, positive magnetostriction appears (hereinafter referred to as "parallel magnetostriction"). <100> When a magnetic field is applied perpendicular to the orientation, negative magnetostriction appears (hereinafter referred to as "perpendicular magnetostriction"). When the strength of the applied magnetic field is gradually increased, the parallel magnetostriction or perpendicular magnetostriction saturates. The magnetostriction constant (3 / 2λ 100) is determined by the difference between the saturated parallel magnetostriction amount and the saturated perpendicular magnetostriction amount, and is calculated by the following formula (1) (for example, Patent Document 4, Non-Patent Document 2).

[0005] 3 / 2λ 100 =ε( / / )― ε(⊥) ···Equation (1) 3 / 2λ 100 : Magnetostriction constant ε( / / ): <100> Parallel magnetostriction when saturated by applying a magnetic field parallel to the direction ε(⊥): <100> Amount of perpendicular magnetostriction when saturated by applying a magnetic field perpendicular to the direction

[0006] The magnetostrictive properties of Fe-Ga alloys are believed to affect the magnetostrictive and inverse magnetostrictive effects and the characteristics of magnetostrictive vibration power generation devices, and are an important parameter in device design (e.g., Non-Patent Document 4). In particular, the magnetostrictive constant depends on the Ga composition of the Fe-Ga alloy single crystal, and it is known that the magnetostrictive constant is maximized at Ga compositions of 18-19 at% and 27-28 at% (e.g., Non-Patent Document 2). It is considered desirable to use Fe-Ga alloys with such Ga concentrations in devices. Furthermore, in recent years, it has been reported that in addition to a large magnetostrictive constant, the greater the parallel magnetostriction, the better the device characteristics, such as output voltage, tend to be (e.g., Non-Patent Document 3).

[0007] A magnetostrictive vibration power generation device is composed of, for example, an Fe-Ga magnetostrictive member wound around a coil, a yoke, and a permanent magnet for the field magnet (for example, Patent Document 5 and Non-Patent Document 4). In this magnetostrictive vibration power generation device, when the yoke, which is the moving part of the device, is vibrated, the Fe-Ga magnetostrictive member fixed to the center of the yoke vibrates in conjunction with it, and the inverse magnetostrictive effect changes the magnetic flux density of the coil wound around the Fe-Ga magnetostrictive member, generating an electromagnetically induced electromotive force and generating electricity. In a magnetostrictive vibration power generation device, a force is applied in the longitudinal direction of the yoke, causing vibration, so the Fe-Ga magnetostrictive member used in the device must be aligned along the easy axis of magnetization. <100> It is desirable to process it so that the direction of the arrow is in the longitudinal direction. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 2016-28831 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-138028 [Patent Document 3] Japanese Patent Application Publication No. 4-108699 [Patent Document 4] Special Publication No. 2015-517024 [Patent Document 5] International Publication No. 2011-158473 [Non-patent literature]

[0009] [Non-Patent Document 1] Etrema, State of the Art of Galfenol Processing. [Non-patent document 2] AE Clark et al., Appl. Phys. 93(2003)8621. [Non-patent document 3] Jung Jin Park, Suok-Min Na, Ganesh Raghunath, and Alison B. Flatau., AIP ADVANCES 6, 056221(2016). [Non-patent document 4] Toshiyuki Ueno, Journal of the Japan Society for Precision Engineering, Vol. 79, No. 4, (2013) 305-308. Summary of the Invention [Problem to be solved by the invention]

[0010] Since the device characteristics of magnetostrictive vibration power generation devices are affected by the magnetostrictive properties of the magnetostrictive member, the magnetostrictive member is required to have high magnetostrictive properties and little variation in the magnetostrictive properties. <100> It was thought that if the Ga concentration was uniform, a magnetostrictive member with a uniform magnetostriction constant would be obtained. However, as described in Non-Patent Document 3, it has been disclosed that device characteristics are affected not only by the magnetostriction constant but also by the amount of parallel magnetostriction. As a result of the inventor's investigation, it was found that magnetostrictive members manufactured as described above have variations in the amount of parallel magnetostriction (or the amount of perpendicular magnetostriction) even if the magnetostriction constant is uniform, and that the magnetostriction constant itself varies.

[0011] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a magnetostrictive member having a high magnetostriction constant and a high amount of parallel magnetostriction, and having little variation in the magnetostriction constant and amount of parallel magnetostriction between members, and a method for manufacturing the magnetostrictive member. [Means for solving the problem]

[0012] According to one aspect of the present invention, there is provided a magnetostrictive member which is a plate-shaped body made of crystals of an iron-based alloy having magnetostrictive properties, which has a longitudinal direction and a lateral direction, and at least one of the front and back surfaces of the plate has grinding marks, has a magnetostriction constant of 200 ppm or more, and has a parallel magnetostriction amount, which is the amount of magnetostriction when a magnetic field parallel to the longitudinal direction is applied and the amount of magnetostriction in the longitudinal direction is saturated, of 200 ppm or more.

[0013] The grinding marks may extend in the longitudinal direction. The surface roughness of the surface having the grinding marks may be such that the surface roughness Ra in the longitudinal direction is smaller than the surface roughness Ra in the lateral direction. The surface roughness Ra in the longitudinal direction may be 0.3 μm or more and 1.5 μm or less, and the surface roughness Ra in the lateral direction may be 0.6 μm or more and 4.5 μm or less.

[0014] Furthermore, according to an aspect of the present invention, there is provided a method for manufacturing a magnetostrictive member, which comprises forming grinding marks on at least one of the front and back surfaces of a plate-shaped body made of crystals of an iron-based alloy having magnetostrictive properties and having a longitudinal direction and a lateral direction, wherein the magnetostrictive member has a magnetostriction constant of 200 ppm or more, and a parallel magnetostriction amount, which is the amount of magnetostriction when a magnetic field parallel to the longitudinal direction is applied and the amount of magnetostriction in the longitudinal direction is saturated, is 200 ppm or more. [Effects of the Invention]

[0015] The magnetostrictive member of the present invention has the characteristics of a high magnetostriction constant and a high parallel magnetostriction amount, and small variations in the magnetostriction constant and the parallel magnetostriction amount between members. The method for manufacturing a magnetostrictive member of the present invention can easily manufacture a magnetostrictive member having a high magnetostriction constant and a high parallel magnetostriction amount, and small variations in the magnetostriction constant and the parallel magnetostriction amount between members. [Brief explanation of the drawings]

[0016] [Figure 1] 1A and 1B are photographs showing an example of a magnetostrictive member according to an embodiment, where 1A is an overall image and 1B is an enlarged image of a portion of 1A. [Figure 2] 3 is a flowchart showing an example of a method for manufacturing a magnetostrictive member according to an embodiment. [Figure 3] 1A and 1B are diagrams showing a first example of a single crystal, a thin plate member, and a magnetostrictive member. [Figure 4] 10A and 10B are diagrams showing a second example of a single crystal, a thin plate member, and a magnetostrictive member. [Figure 5] 10A and 10B are diagrams showing a third example of a single crystal, a thin plate member, and a magnetostrictive member. [Figure 6] FIG. 1 is a diagram showing the strain gauge method used in the examples. [Figure 7] FIG. 2 is a diagram showing a magnetostrictive member of Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0017] The following description will be made with reference to the drawings. In each drawing, some or all of the components are shown in schematic form and scaled as appropriate.

[0018] [Embodiment] The magnetostrictive member and the method for manufacturing the magnetostrictive member according to this embodiment will be described below.

[0019] 1A and 1B are photographs showing an example of a magnetostrictive member according to an embodiment, with 1A being an overall image and 1B being an enlarged image of a portion of 1A.

[0020] As shown in Fig. 1(A), the magnetostrictive member 1 is a plate-like body having a longitudinal direction D1 and a lateral direction D2. The plate-like body is rectangular in plan view. The plate-like body has a front surface 3 and a back surface 4. The front surface 3 and the back surface 4 are preferably parallel to each other, but do not have to be parallel to each other.

[0021] The magnetostrictive member 1 is made of a crystal of an iron-based alloy. The iron-based alloy is not particularly limited as long as it has magnetostrictive properties. Magnetostrictive properties refer to the property of undergoing a change in shape when a magnetic field is applied. Examples of the iron-based alloy include Fe-Ga, Fe-Ni, Fe-Al, Fe-Co, Tb-Fe, Tb-Dy-Fe, Sm-Fe, and Pd-Fe alloys. The above alloys may also be alloys to which a third component has been added. For example, an Fe-Ga alloy may be alloyed to which Ba, Cu, or the like has been added. Among these iron-based alloys, Fe-Ga alloys have greater magnetostrictive properties and are easier to process than other alloys. Therefore, they are used in vibration power generation materials in the energy harvesting field, wearable devices, sensors, and the like. In the following explanation, an example of the magnetostrictive member 1 will be described in which the magnetostrictive member 1 is made of a single crystal of an Fe-Ga alloy.

[0022] The single crystal of the Fe-Ga alloy has a body-centered cubic lattice structure, and the first to third directional indices in the Miller indices <100> The basis of this is that the axes (see Figs. 3 to 5) are equivalent, and the first to third {100} planes (see Figs. 3 to 5) among the plane indices in the Miller index are equivalent (i.e., (100), (010) and (001) are equivalent). Furthermore, Fe-Ga alloys have the property of producing large magnetostriction in a specific orientation of the crystal. When this property is utilized in a magnetostrictive vibration power generation device, it is desirable to match the direction in the device where magnetostriction of the magnetostrictive member 1 is required with the orientation (direction) where the magnetostriction of the crystal is at its maximum. Specifically, as mentioned above, the direction of easy magnetization in a single crystal is <100> It is desirable to set the direction in the longitudinal direction D1 of the magnetostrictive member 1. <100> The direction can be set to the longitudinal direction D1 of the magnetostrictive member 1, for example, by calculating the crystal orientation of the single crystal using known crystal orientation analysis and cutting the single crystal based on the calculated crystal orientation of the single crystal.

[0023] The crystal that can be used for the magnetostrictive member 1 of this embodiment may be a single crystal or a polycrystal. <100> In order to increase the degree of orientation integration in the direction and improve the properties of the magnetostrictive material, it is more advantageous to use single crystals than polycrystals. Although polycrystals have inferior magnetostrictive properties to single crystals, they can be produced at low cost, so polycrystals are sometimes used.

[0024] Magnetostrictive members 1 are used, for example, as materials (components) for vibration power generation devices in the energy harvesting field, as well as for wearable devices and sensors. For example, a magnetostrictive vibration power generation device such as that shown in Patent Document 5 above is composed of a coil, a magnetostrictive member made of an Fe-Ga alloy wound around the coil, a yoke, and a permanent magnet for a field magnet. When the yoke, which is the moving part of the device, is vibrated, the magnetostrictive member fixed to the center of the yoke vibrates in tandem. The inverse magnetostrictive effect changes the magnetic flux density of the coil wound around the magnetostrictive member, generating electromagnetically induced electromotive force, thereby generating electricity. When used in such a mechanism, the magnetostrictive member 1 is preferably thin and rectangular in shape in a plan view. There are no particular limitations on the thickness of the magnetostrictive member 1. The lower limit of the thickness is preferably 0.3 mm or more, more preferably 0.4 mm or more, and even more preferably 0.5 mm or more. The upper limit of the thickness of the magnetostrictive member 1 is preferably 2 mm or less, more preferably 1.8 mm or less, and even more preferably 1.5 mm or less. The thickness of the magnetostrictive member 1 is preferably 0.3 mm or more and 2 mm or less, more preferably 0.4 mm or more and 1.8 mm or less, and even more preferably 0.5 mm or more and 1.5 mm or less. As explained above, the mechanism by which the magnetostrictive member 1 generates electricity is the inverse magnetostriction effect generated by applying stress (vibration) to the magnetostrictive member. If the thickness of the magnetostrictive member 1 is less than 0.3 mm, it is prone to breakage during vibration. Conversely, if the thickness of the magnetostrictive member 1 exceeds 2 mm, the stress caused by vibration must be increased, resulting in poor efficiency. The shape and size of the magnetostrictive member 1 are appropriately set according to the size of the intended device. For example, the size of the magnetostrictive member 1 is such that the length (dimension) L1 in the longitudinal direction D1 is 16 mm, the width (dimension) L2 in the lateral direction D2 is 4 mm, and the thickness is 1 mm.

[0025] The shape and dimensions of the magnetostrictive member 1 are not particularly limited. For example, the magnetostrictive member 1 does not have to be rectangular in plan view. For example, the shape of the magnetostrictive member 1 may be elliptical, track-shaped, or irregular in plan view. When the shape of the magnetostrictive member 1 is other than rectangular in plan view, the longitudinal direction D1 is the major axis direction, long axis direction, etc., and the lateral direction D2 is the direction perpendicular to the longitudinal direction D1.

[0026] As described above, the present inventors have developed a single crystal of an Fe—Ga alloy, the principal plane of which is the {100} plane, and the direction of easy magnetization. <100> We fabricated several plate-shaped magnetostrictive members with a rectangular shape in a planar view, with the grinding direction parallel to the longitudinal direction of the magnetostrictive member. We confirmed the magnetostrictive properties of several magnetostrictive members cut from single crystals of an Fe-Ga alloy with a uniform Ga concentration. We found that the magnetostrictive constants of the several magnetostrictive members we fabricated were high, but that the parallel magnetostriction varied greatly. Furthermore, we found that the magnetostrictive constants themselves varied among these magnetostrictive members, and that the magnetostrictive constant varied depending on the position at which the magnetostrictive member was cut from the single crystal. Further investigation revealed that the magnetostrictive constant and parallel magnetostriction were related to the grinding direction of the magnetostrictive member. The present invention was made based on the above findings.

[0027] Magnetostrictive members are manufactured, for example, by cutting grown iron-based alloy crystals in a certain direction to create a thin plate-like member, and then cutting the created thin plate-like member to a predetermined size. Conventional magnetostrictive members have been polished or otherwise processed on the front and back surfaces to give them a smooth finish.

[0028] 1(A) and 1(B), the magnetostrictive member 1 of this embodiment is characterized in that at least one of the front surface 3 and the back surface 4 (sometimes collectively referred to as the "front and back surfaces") has a plurality of grooves 2 extending in the longitudinal direction D1. This will be explained in detail below.

[0029] As described above, the magnetostrictive properties of several magnetostrictive members cut from Fe—Ga single crystals with a uniform Ga concentration were examined, and it was found that the magnetostrictive constant was high, but the parallel magnetostriction varied. According to this embodiment, even in magnetostrictive members with such variability in parallel magnetostriction, by forming a plurality of grooves 2 extending in the longitudinal direction D1 on at least one of the front and back surfaces of the magnetostrictive member, it is possible to improve both the magnetostrictive constant and the parallel magnetostriction so that they are high and have little variation between members (also referred to as "improving the magnetostrictive constant and the parallel magnetostriction"). In particular, it is possible to improve the parallel magnetostriction. It is presumed that this improvement phenomenon occurs because the formation of the plurality of grooves 2 applies stresses such as residual strain within the crystal, uniformly rearranging the magnetic moments and uniformizing the magnetostrictive properties.

[0030] The following describes the modification of the magnetostriction constant and the amount of parallel magnetostriction. In this embodiment, as shown in the examples described later, a sample of a magnetostrictive member that had a low amount of parallel magnetostriction before forming the grooves 2 was formed with multiple grooves 2 extending in different directions on both the front and back surfaces of the magnetostrictive member, and the changes in the magnetostriction constant and the amount of parallel magnetostriction due to the formation of the multiple grooves 2 were examined. In this embodiment, the magnetostrictive constant and the amount of parallel magnetostriction were measured when multiple grooves 2 extending in the same direction as the longitudinal direction D1 were formed in the magnetostrictive member (Examples 3, 13, 16, 17, 19, etc.) and when multiple grooves 2 extending in the same direction as the lateral direction D2 were formed (Comparative Examples 2, 3, etc.). The results are shown in Table 1.

[0031] In magnetostrictive member samples with low parallel magnetostriction before forming the grooves 2, when multiple grooves 2 extending in the same direction as the longitudinal direction D1 were formed in the magnetostrictive member (Examples 3, 13, 16, 17, 19, etc.), the magnetostriction constant and parallel magnetostriction changed from low to high and stabilized at a high level by forming the multiple grooves 2. In particular, the parallel magnetostriction increased significantly by forming the multiple grooves 2. Furthermore, the values ​​of the magnetostriction constant and parallel magnetostriction showed little variation between members (samples).

[0032] In contrast, in a sample of a magnetostrictive member that had a low amount of parallel magnetostriction before forming the plurality of grooves 2, when a plurality of grooves 2 extending in the same direction as the short-side direction D2 were formed in the magnetostrictive member (Comparative Examples 2 and 3), the amount of parallel magnetostriction remained low and stable, similar to before forming the plurality of grooves 2. Furthermore, there was little variation in the value of the amount of parallel magnetostriction between members (samples).

[0033] Furthermore, in this embodiment, even in samples of magnetostrictive members that had a high amount of parallel magnetostriction before the formation of the plurality of grooves 2, a plurality of grooves 2 extending in different directions were formed on both the front and back surfaces of the magnetostrictive member, and changes in the magnetostriction constant and the amount of parallel magnetostriction due to the formation of the plurality of grooves 2 were investigated. In this embodiment, the magnetostrictive constant and the amount of parallel magnetostriction were measured when a plurality of grooves 2 extending in the same direction as the longitudinal direction D1 were formed in the magnetostrictive member (Examples 2, 5, 6 to 11, etc.), and when a plurality of grooves 2 extending in the same direction as the lateral direction D2 were formed (Comparative Examples 1 and 4).

[0034] In samples of magnetostrictive members that had a high amount of parallel magnetostriction before forming the plurality of grooves 2, when a plurality of grooves 2 extending in the same direction as the longitudinal direction D1 were formed in the magnetostrictive member (Examples 2, 5, 6 to 11, etc.), the magnetostriction constant and the amount of parallel magnetostriction remained high and stable, just as they were before forming the plurality of grooves 2. Furthermore, there was little variation in the values ​​of the magnetostriction constant and the amount of parallel magnetostriction between members (samples).

[0035] In contrast, in the magnetostrictive member samples in which the parallel magnetostriction was high before the formation of the grooves 2, when multiple grooves 2 extending in the same direction as the short-side direction D2 were formed in the magnetostrictive member (Comparative Examples 1 and 4), the parallel magnetostriction changed from a high level before the formation of the grooves 2 to a low level and stabilized at a low level. Furthermore, there was little variation in the parallel magnetostriction between members (samples).

[0036] The above results show that the magnetostriction constant and the amount of parallel magnetostriction are affected by the surface condition of the magnetostrictive member. It is also found that by forming multiple grooves 2 extending in the longitudinal direction D1 on at least one of the front surface 3 and back surface 4 of the magnetostrictive member, it is possible to improve (modify) both the magnetostriction constant and the amount of parallel magnetostriction to a high level with little variation between members.

[0037] In addition, in this embodiment, in Examples 34 to 37 and Comparative Examples 7 to 9, the magnetostriction constant and parallel magnetostriction were measured when multiple grooves 2 extending in directions from 0° to 60° with respect to the longitudinal direction D1 were formed. The results are shown in Table 6. In a magnetostrictive member sample with low parallel magnetostriction before forming the multiple grooves 2, when multiple grooves 2 extending in directions from 0° to 60° with respect to the longitudinal direction D1 were formed, the parallel magnetostriction increased by forming the multiple grooves 2. However, as the angle between the extension direction of the multiple grooves 2 and the longitudinal direction D1 approached 0°, the value became similar to that when multiple grooves 2 extending in the same direction as the longitudinal direction D1 were formed. As the angle increased, the value tended to approach that when multiple grooves 2 extending in the same direction as the short-side direction D2 were formed. The value of parallel magnetostriction was roughly intermediate between the value at 0° and the value at 60° with respect to the longitudinal direction D1, around 45°. This angle (the angle formed by the extension direction of the grooves 2 and the longitudinal direction D1) is preferably less than 40°, more preferably 35° or less, and more preferably 30° or less. When the angle is within the above preferred range, the effect of improving the magnetostriction constant and parallel magnetostriction is more reliably manifested. When the angle is 30° or less, it becomes possible to more reliably manage the parallel magnetostriction at a high level of 200 ppm or more.

[0038] Furthermore, the above results show that by forming multiple grooves 2 extending in the longitudinal direction D1 on at least one of the front surface 3 and the back surface 4 of the magnetostrictive member, variations in the magnetostriction constant and parallel magnetostriction resulting from differences in relative position within the single crystal are suppressed, and the magnetostriction constant and parallel magnetostriction are stabilized at high levels, with this tendency being particularly pronounced for the parallel magnetostriction. Furthermore, the above results show that the parallel magnetostriction is determined according to the angle between the longitudinal direction D1 and the extension direction of the multiple grooves 2, and that the parallel magnetostriction is high when the longitudinal direction D1 and the extension direction of the multiple grooves 2 are parallel, and is presumed to be maximum in this case. As described above, the multiple grooves 2 extending in the longitudinal direction D1 provided in the magnetostrictive member 1 of this embodiment can modify both the magnetostriction constant and the parallel magnetostriction (at least the parallel magnetostriction). The multiple grooves 2 extending in the longitudinal direction D1 of the magnetostrictive member 1 of this embodiment can be modified to significantly increase the parallel magnetostriction (for example, to 200 ppm or more, preferably 250 ppm or more) in a magnetostrictive member that has a low parallel magnetostriction (for example, 50 ppm or less) when smoothed by polishing under the conditions shown in Example 2.

[0039] The parallel magnetostriction is the magnetostriction amount when a magnetic field parallel to the longitudinal direction D1 of the magnetostrictive member 1 is applied and the magnetostriction amount in the longitudinal direction D1 is saturated. The perpendicular magnetostriction is the magnetostriction amount when a magnetic field parallel to the transverse direction D2 of the magnetostrictive member 1 is applied and the magnetostriction amount in the transverse direction D2 is saturated. The magnetostriction constant, parallel magnetostriction amount, and perpendicular magnetostriction amount of the magnetostrictive member 1 of this embodiment are values ​​obtained as described in the examples described later. The magnetostriction amount is a value obtained by correcting the actual strain detection value with the gauge factor according to equation (3). The parallel magnetostriction amount is the magnetostriction amount when the magnetic field direction is parallel to the longitudinal direction of the strain gauge, and the perpendicular magnetostriction amount is the magnetostriction amount when the magnetic field direction is perpendicular to the longitudinal direction of the strain gauge. The magnetostriction constant is a value obtained as the difference between the parallel magnetostriction amount and the perpendicular magnetostriction amount according to equation (1). The angle between the extension direction of the multiple grooves 2 and the longitudinal direction D1 is a value obtained by averaging the values ​​for multiple different grooves.

[0040] Next, the multiple grooves 2 will be described. The multiple grooves 2 are formed on at least one of the front surface 3 and the back surface 4. In the example shown in FIGS. 1(A) and 1(B), the multiple grooves 2 are formed on both the front surface 3 and the back surface 4. When the multiple grooves 2 are formed on one of the front surface 3 and the back surface 4, the effect of improving the magnetostriction constant and the amount of parallel magnetostriction described above tends to be smaller than when the multiple grooves 2 are formed on both the front surface 3 and the back surface 4, and the variation in magnetostriction characteristics tends to increase. Therefore, it is preferable that the multiple grooves 2 are formed on both the front surface 3 and the back surface 4.

[0041] The plurality of grooves 2 are formed to extend in the longitudinal direction D1. Each groove 2 is linear (stripe-like). It is preferable that each groove 2 is linear, from the viewpoint of efficiently achieving the effect of improving the magnetostriction constant and the amount of parallel magnetostriction. Note that each groove 2 may also be curved. The length of each groove 2 in the longitudinal direction D1 is not particularly limited. From the viewpoint of efficiently achieving the effect of improving the magnetostriction constant and the amount of parallel magnetostriction, it is preferable that the plurality of grooves 2 are formed evenly within the plane at predetermined intervals in the short direction D2, and it is preferable that they are formed throughout the plane. Note that in this embodiment, the magnetostrictive member 1 may include grooves extending in directions other than the longitudinal direction as long as the effects of the present invention are not impaired, and such magnetostrictive members are not excluded, but it is ideal that there are no grooves extending in directions other than the longitudinal direction.

[0042] In this embodiment, the plurality of grooves 2 extending in the longitudinal direction D1 includes the plurality of grooves 2 extending in a direction parallel to the longitudinal direction D1, and the plurality of grooves 2 extending in a direction intersecting the longitudinal direction D1 at an angle of less than 40°. As described above, if the extension direction of the plurality of grooves 2 deviates from a direction parallel to the longitudinal direction D1, the amount of parallel magnetostriction decreases, so it is preferable that the extension direction of the plurality of grooves 2 be a direction parallel to the longitudinal direction D1.

[0043] The multiple grooves 2 shown in FIG. 1(B) can be formed, for example, by surface grinding on at least one of the front surface 3 and the back surface 4 of a thin plate member obtained by cutting a single crystal. In this case, the multiple grooves 2 are grinding marks (grinding streaks) formed on the processed surface after surface grinding. Grinding marks are marks formed by a grinding stone during surface grinding. These grinding marks are streaky (linear) marks formed along the grinding direction (the direction of movement of the grinding stone or the processing table) by surface grinding. The direction of the grinding marks (the direction in which the multiple grooves 2 extend) can be controlled by controlling the grinding direction. The grinding marks can be controlled by the grit size (grit) of the grinding stone. The state of the multiple grooves 2 formed by surface grinding can be confirmed using a microscope, etc. Note that the method of forming the multiple grooves 2 is not limited to surface grinding, as will be described later. The multiple grooves 2 may include grooves extending in different directions or grooves with different lengths or depths.

[0044] The surface roughness Ra of the surface on which the plurality of grooves 2 are formed is usually smaller in the longitudinal direction D1 than in the lateral direction D2. The plurality of grooves 2 are formed linearly (stripe-like) extending in the longitudinal direction D1. Therefore, the lateral direction D2 of the magnetostrictive member 1 has an uneven shape, and the surface roughness Ra is larger than in the longitudinal direction D1. Furthermore, the longitudinal direction D1 of the magnetostrictive member 1 follows the linear (stripe-like) grooves 2 extending in the longitudinal direction D1, and therefore the surface roughness Ra is smaller than in the lateral direction D2. In this embodiment, the surface roughness Ra is an average value obtained by measuring values ​​at a plurality of different portions of one magnetostrictive member 1.

[0045] On the surface on which the plurality of grooves 2 are formed, the surface roughness Ra in the longitudinal direction D1 is smaller than the surface roughness Ra in the lateral direction D2. On the surface on which the plurality of grooves 2 are formed, the lower limit of the surface roughness Ra in the longitudinal direction D1 is preferably 0.3 μm or more, and the upper limit is preferably 1.5 μm or less, and more preferably 0.3 μm or more and 1.5 μm or less. On the surface on which the plurality of grooves 2 are formed, the lower limit of the surface roughness Ra in the lateral direction D2 is preferably 0.6 μm or more, more preferably 0.7 μm or more, and the upper limit is preferably 4.5 μm or less, and the range is preferably 0.6 μm or more and 4.5 μm or less, and more preferably 0.7 μm or more and 4.5 μm or less. When the surface roughness Ra in the longitudinal direction D1 or the lateral direction D2 on the surface on which the plurality of grooves 2 are formed is within the above range, the effect of improving the magnetostriction constant and the parallel magnetostriction amount can be efficiently exhibited.

[0046] The characteristics of the magnetostrictive member 1 of this embodiment will be described. The magnetostrictive member 1 of this embodiment can have a magnetostriction constant of 200 ppm or more, preferably 250 ppm or more, due to the above-mentioned configuration. Furthermore, the magnetostrictive member 1 can have a parallel magnetostriction amount of 200 ppm or more, preferably 250 ppm or more, due to the above-mentioned configuration. When the magnetostrictive constant and parallel magnetostriction amount of the magnetostrictive member 1 are to be within the above-mentioned ranges, it is preferable that the magnetostrictive member 1 be formed from a single crystal of an Fe—Ga alloy.

[0047] Furthermore, the magnetostrictive member 1 of this embodiment is modified (corrected) so that both the magnetostriction constant and the parallel magnetostriction amount are high and have little variation between members by forming multiple grooves 2 extending in the longitudinal direction D1 on at least one of the front surface 3 and back surface 4 of the magnetostrictive member. Therefore, in the case of multiple magnetostrictive members 1 of this embodiment manufactured from a single crystal, the variation in the magnetostriction constant among the multiple magnetostrictive members 1 can be kept within 15% and the variation in the parallel magnetostriction amount can be kept within 10%. Furthermore, in the case of multiple magnetostrictive members 1 of this embodiment manufactured from a single crystal, the coefficient of variation in the magnetostriction constant among the multiple magnetostrictive members 1 can be preferably 0.1 or less, more preferably 0.06 or less, and the coefficient of variation in the parallel magnetostriction amount can be preferably 0.1 or less, more preferably 0.05 or less. In this embodiment, the variations in the magnetostriction constant and the parallel magnetostriction amount among the multiple magnetostrictive members 1 are values ​​calculated using the following formula (2): Variation (%) = |difference between the mean and the largest outlier| / mean value···Equation (2) The term "one grown crystal" refers to the effective crystal (the part actually used as a part) that is used as a magnetostrictive member. For example, a crystal grown by the BV method has a solidification rate in the range of 10% to 85%, and a crystal grown by the CZ method has a uniform diameter (excluding the growth shoulder, etc.).

[0048] As described above, the magnetostrictive member 1 of this embodiment is a plate-like body made of crystals of an iron-based alloy having magnetostrictive properties, having longitudinal and lateral directions, and at least one of the front and back surfaces of the plate-like body has multiple grooves extending in the longitudinal direction. Note that the configuration of the magnetostrictive member 1 of this embodiment other than the above is optional. The magnetostrictive member 1 of this embodiment has the characteristics of a high magnetostriction constant and parallel magnetostriction, and small variations in the magnetostriction constant and parallel magnetostriction between members. Furthermore, the magnetostrictive member 1 of this embodiment is modified in the above-mentioned magnetostriction constant and parallel magnetostriction, thereby correcting the variations in the magnetostriction constant and parallel magnetostriction in conventional magnetostrictive members manufactured from the same single crystal, allowing for stable production with high yields. Because the magnetostrictive member 1 of this embodiment has a high magnetostriction constant and parallel magnetostriction, it can be suitably used as a final product of a member (material) exhibiting excellent magnetostriction and inverse magnetostriction effects.

[0049] Next, a method for manufacturing the magnetostrictive member of this embodiment will be described. The method for manufacturing the magnetostrictive member of this embodiment is the method for manufacturing the magnetostrictive member 1 of this embodiment described above. The method for manufacturing the magnetostrictive member of this embodiment comprises forming a plurality of grooves 2 extending in the longitudinal direction D1 on at least one of the front surface 3 and the back surface 4 of a plate-shaped body made of crystals of an iron-based alloy having magnetostrictive properties and having a longitudinal direction D1 and a lateral direction D2. Note that in the following description, a method for manufacturing the magnetostrictive member 1 from a single crystal ingot of an Fe-Ga alloy will be described as an example, but the method for manufacturing the magnetostrictive member of this embodiment is not limited to the following description. Furthermore, any description in this specification that is applicable to the method for manufacturing the magnetostrictive member of this embodiment will also be applied to the method for manufacturing the magnetostrictive member of this embodiment.

[0050] Fig. 2 is a flowchart showing an example of a method for manufacturing a magnetostrictive member of this embodiment. Figs. 3 to 5 are diagrams showing first to third examples of a single crystal, a thin plate member, and a magnetostrictive member. The method for manufacturing a magnetostrictive member of this embodiment includes a crystal preparation step (step S1), a crystal cutting step (step S2), a groove formation step (step S3), and a cutting step (step S4).

[0051] In the manufacturing method of the magnetostrictive member of this embodiment, first, in the crystal preparation step (step S1), a crystal of an iron-based alloy having magnetostrictive properties is prepared. The prepared crystal may be a single crystal or a polycrystal. Furthermore, the prepared crystal may be a grown crystal or a commercially available crystal. For example, in the crystal preparation step, a single crystal of an Fe-Ga alloy is prepared. There are no particular limitations on the method for growing the single crystal of an Fe-Ga alloy. The method for growing the single crystal of an Fe-Ga alloy may be, for example, a pulling method or a unidirectional solidification method. For example, the Cz method can be used as the pulling method, and the VB method, VGF method, and micro-pulling-down method can be used as the unidirectional solidification method.

[0052] The magnetostriction constant of a single crystal of an Fe—Ga alloy is maximized by adjusting the gallium content to 18.5 at% or 27.5 at%. Therefore, the Fe—Ga single crystal is preferably grown so that the gallium content is 16.0 to 20.0 at% or 25.0 to 29.0 at%, and more preferably 17.0 to 19 at% or 26.0 to 28.0 at%. The shape of the grown single crystal is not particularly limited, and may be, for example, cylindrical or rectangular prism. The grown single crystal may be cut into a cylindrical single crystal, if necessary, by cutting the seed crystal, the diameter-increasing portion, or the shoulder portion (the portion that increases the diameter from the seed crystal to the predetermined diameter of the single crystal) with a cutting device. The size of the grown single crystal is not particularly limited, as long as the magnetostrictive member can be secured in the predetermined direction. When growing an Fe—Ga single crystal, the growth axis direction is <100> The seed crystal is grown using a seed crystal whose top or bottom surface is processed to a {100} plane so that the Fe-Ga alloy single crystal grows in a direction perpendicular to the top or bottom surface of the seed crystal, and inherits the orientation of the seed crystal.

[0053] Following the crystal preparation step (step S1), a crystal cutting step (step S2) is carried out. The crystal cutting step is a step of cutting a crystal to produce a thin plate member. The thin plate member is a member that will be the material for the magnetostrictive member 1 of this embodiment. The crystal cutting step is, for example, a step of cutting a single crystal of an Fe-Ga alloy having magnetostrictive properties using a cutting device to produce a thin plate member having a {100} plane as the main surface. The cutting device may be a wire electric discharge machine, an inner diameter blade cutting device, a wire saw, or other cutting device. Among these, it is particularly preferable to use a multi-wire saw, since it can cut multiple thin plate members simultaneously. The cutting direction of the single crystal is, in the case of an Fe-Ga single crystal, <100> The cutting is performed so that the cut surface, i.e., the main surface of the thin plate member, is the {100} plane. The cutting direction of the single crystal is not particularly limited. For example, as shown in Figures 3 to 5, the cutting direction of the single crystal may be perpendicular or parallel to the growth direction of the single crystal (the direction in which the crystal is grown).

[0054] Following the crystal cutting step (step S2), a groove forming step (step S3) is carried out. In the groove forming step, a plurality of grooves 2 are formed on at least one of the front and back surfaces 3 and 4 of the obtained thin plate member. In the groove forming step, a plurality of grooves 2 are formed in the thin plate member so that, when the thin plate member is finally cut into the magnetostrictive member 1, a plurality of grooves 2 extending in the longitudinal direction D1 of the magnetostrictive member 1 are formed. As described above, a plurality of grooves 2 can be formed by performing a surface grinding process on at least one of the front and back surfaces of the thin plate member obtained by the crystal cutting step. Below, an example will be described in which the groove forming step is performed by surface grinding the thin plate member. When a plurality of grooves 2 are formed by surface grinding, the effect of improving the magnetostriction constant and parallel magnetostriction amount can be efficiently achieved.

[0055] The surface grinding process is performed using a surface grinding machine. In order to efficiently achieve the effect of modifying the magnetostriction constant and the amount of parallel magnetostriction, it is preferable that the direction of the grinding marks formed on the thin plate member be parallel to the longitudinal direction D1 of the magnetostrictive member 1. For this reason, it is preferable that the grinding marks be linear. When making the grinding marks linear, it is preferable that the surface grinding machine be a type in which the grinding wheel or processing table moves in a linear direction, and it is preferable to use a surface grinding machine that uses a flat grinding wheel and has a processing table that moves back and forth. It is also possible to use a surface grinding machine that uses a cup grinding wheel and has a processing table that rotates, but when using such a surface grinding machine, the grinding marks will be curved, so it is preferable to set the curvature of the grinding marks to be small (the degree of curvature is small).

[0056] Furthermore, the grinding marks must be formed on the surface of the magnetostrictive member 1. For this reason, when processing a thin plate member to adjust its thickness, etc., the surface grinding process may be performed after the predetermined processing is performed using a processing machine other than a surface grinder, such as a double-sided lapping machine or a surface grinder using a cup grinding wheel. Alternatively, the surface of the thin plate member (magnetostrictive member) may be polished as in the conventional method to give a mirror finish to the surface, and then the surface grinding process may be performed. From the viewpoint of efficiently achieving the effect of modifying the magnetostriction constant and parallel magnetostriction, it is preferable to perform the surface grinding process on both the front and back surfaces of the thin plate member.

[0057] The grinding stone used in surface grinding preferably has a lower limit of roughness (grit) of #40 or more, more preferably #100 or more, and an upper limit of #500 or less, more preferably #400 or less, preferably a range of #40 to #500, more preferably #40 to #400 or less, and more preferably #100 to #400 or less. When the roughness (grit) of the grinding stone is within the above range, the effect of improving the magnetostriction constant and parallel magnetostriction can be more reliably achieved. Note that using a grinding stone smaller than #40 may result in an unstable size of grinding marks. Using a grinding stone exceeding #500 may result in the surface of the magnetostrictive member being smooth, which may prevent the effect of improving the magnetostriction constant and parallel magnetostriction from being efficiently achieved.

[0058] In the groove forming step, as described above, the grooves 2 are preferably formed so that the surface roughness Ra in the longitudinal direction D1 of the surface on which the grooves 2 are formed in the magnetostrictive member 1 falls within the above-described preferred range. For example, the grooves 2 are preferably formed so that the lower limit is preferably 0.3 μm or more and the upper limit is preferably 1.5 μm or less, and the range is 0.3 μm to 1.5 μm. The grooves 2 are preferably formed so that the surface roughness Ra in the lateral direction D2 of the surface on which the grooves 2 are formed in the magnetostrictive member 1 falls within the above-described range. Furthermore, the grooves 2 are preferably formed so that the magnetostrictive constant and the parallel magnetostriction of the magnetostrictive member 1 fall within the above-described range. For example, the grooves 2 are preferably formed so that the magnetostrictive constant and the parallel magnetostriction of the magnetostrictive member 1 fall within the above-described range. The grooves 2 having the above-described preferable surface roughness Ra, magnetostriction constant, and parallel magnetostriction can be formed by the above-described surface grinding process. The groove formation process may be performed by a method other than surface grinding, as long as it is possible to form the grooves 2 on at least one of the front surface 3 and the back surface 4 of the obtained thin plate member. For example, the thin plate member may be produced using a fixed abrasive wire saw. That is, the grooves 2 may be grooves formed when slicing a crystal with a fixed abrasive wire saw to produce the thin plate member. Cutting with a wire saw can be divided into two types: a free abrasive method, in which the workpiece is pressed against a row of parallel ultra-fine wires arranged at a constant pitch, and cutting is performed by supplying a machining fluid containing abrasive grains (also called a slurry) between the workpiece and the wire while feeding the wire in the linear direction; and a fixed abrasive method, in which the workpiece is cut while feeding a wire to which abrasive grains such as diamond are fixed by electrodeposition or adhesive in the linear direction. The cut surface using the free abrasive method is a non-directional matte finish, and the effect of the present invention cannot be obtained, but when cutting with a fixed abrasive wire saw, grinding marks are generated in the wire feed direction, and multiple grooves 2 can be formed similar to those in the above-mentioned surface grinding process.When cutting with a fixed abrasive wire saw, the crystal cutting process (step S2) and the groove forming process (step S3) can be performed in the same process, allowing for efficient production of thin plate members. Alternatively, multiple grooves 2 may be formed by applying a constant pressure using sandpaper or the like.

[0059] After the groove forming step (step S3), a cutting step (step S4) is carried out. The cutting step is a step in which the thin plate member in which the plurality of grooves 2 have been formed in the groove forming step is cut to obtain the magnetostrictive member 1 of this embodiment.

[0060] In the cutting process, when cutting a thin plate member having a plurality of grooves 2 formed therein to form magnetostrictive members 1, the thin plate member is cut so as to form a plurality of grooves 2 extending in the longitudinal direction D1 of the magnetostrictive member 1. In the cutting process, the thin plate member is cut to a predetermined size. In the cutting process, the thin plate member is cut into magnetostrictive members 1 so that the magnetostrictive members 1 become rectangular plate-like bodies in a plan view. In the cutting process, the thin plate member is cut using a cutting device. The cutting device used in the cutting process is not particularly limited, and for example, a peripheral blade cutting device, a wire electric discharge machine, a wire saw, etc. can be used. The direction in which the magnetostrictive members are extracted from the thin plate member is not particularly limited, and for example, it may be set to a direction that allows for efficient extraction based on the size of the magnetostrictive members, etc.

[0061] As described above, the method for manufacturing a magnetostrictive member of this embodiment comprises forming a plurality of grooves 2 extending in the longitudinal direction D1 on at least one of the front surface 3 and the back surface 4 of a plate-shaped body made of crystals of an iron-based alloy having magnetostrictive properties and having a longitudinal direction D1 and a lateral direction D2. Note that in the method for manufacturing a magnetostrictive member of this embodiment, configurations other than those described above are optional. The method for manufacturing a magnetostrictive member of this embodiment can manufacture a magnetostrictive member having a high magnetostriction constant and parallel magnetostriction amount, and having little variation in the magnetostriction constant and parallel magnetostriction amount between members. The method for manufacturing a magnetostrictive member of this embodiment can be easily implemented because it only requires forming a plurality of grooves 2 in a material having magnetostrictive properties.

[0062] In the past, magnetostrictive members extracted from the same single crystal varied in parallel magnetostriction depending on the extraction position of the magnetostrictive member from the single crystal, and magnetostrictive members with a high parallel magnetostriction were selected. However, in the method for manufacturing a magnetostrictive member of this embodiment, the above-mentioned magnetostriction constant and parallel magnetostriction amount are modified to correct the variation in the magnetostrictive constant and parallel magnetostriction amount in magnetostrictive members produced from the same single crystal in the past. This makes it possible to stably produce magnetostrictive members with high magnetostriction constants and parallel magnetostriction amounts and little variation in the magnetostrictive constants and parallel magnetostriction amounts between members at a high yield. [Example]

[0063] The present invention will be specifically explained below using examples, but the present invention is not limited to these examples.

[0064] [Example 1] The raw materials were prepared with a stoichiometric ratio of iron to gallium of 81:19, and a cylindrical Fe-Ga alloy single crystal was grown by the vertical Bridgman (VB) method. The growth axis of the single crystal was <100> The orientation of the {100} plane on the top or bottom surface of the single crystal, which was perpendicular to the crystal growth axis, was confirmed by X-ray diffraction. At this time, measurements of the top and bottom surface samples of the crystal using a Shimadzu sequential plasma emission spectrometer (ICPS-8100) revealed that the gallium content of the single crystal was 17.5 to 19.0 at%.

[0065] A magnetostrictive member was manufactured from the grown single crystal as follows. First, a wire saw with a free abrasive grain type was used to cut the single crystal in a direction parallel to the direction of growth ( <100> The single crystal was cut in a direction parallel to the {100} orientation to produce a thin plate member with a cut surface, i.e., the main surface, in {100}. Next, the obtained thin plate member was subjected to surface grinding using a #200 flat grinding wheel on a surface grinder to adjust the thickness of the thin plate member and to form multiple grooves (grinding marks) on the front and back surfaces. After that, the cutting position was set so that the longitudinal direction of the magnetostrictive member was the same as the grinding direction during surface grinding, i.e., the direction of the grinding marks, and a peripheral blade cutting device was used to cut out a magnetostrictive member with dimensions of 16 mm in the longitudinal direction, 4 mm in the lateral direction, and 1 mm in thickness.

[0066] Next, the magnetostriction properties of the cut-out magnetostrictive members were measured. The magnetostriction properties were measured using a strain gauge method. As shown in Fig. 6, a strain gauge (manufactured by Kyowa Electronics Co., Ltd.) was attached with an adhesive to the {100} plane, which is the main surface of the manufactured magnetostrictive member. Note that the longitudinal direction of the strain gauge is the direction in which magnetostriction is detected, so the longitudinal direction of the strain gauge was aligned with the longitudinal direction of the magnetostrictive member and <100> It was glued so that it was parallel to the direction.

[0067] The magnetostriction measuring device (manufactured by Kyowa Electronics Co., Ltd.) consisted of a neodymium permanent magnet, a bridge box, a compact recording system, a strain unit, and dynamic data acquisition software.

[0068] The amount of magnetostriction was determined by correcting the actual strain detection value with the gauge factor. The gauge factor was calculated using the following formula (3). ε=2.00 / Ks × εi...Equation (3) (ε: gauge factor, εi: measured strain value, Ks: gauge factor of the gauge used)

[0069] Furthermore, the amount of magnetostriction when the magnetic field direction is parallel to the longitudinal direction of the strain gauge was defined as the parallel magnetostriction. On the other hand, the amount of magnetostriction when the magnetic field direction is perpendicular to the longitudinal direction of the strain gauge was defined as the perpendicular magnetostriction. The magnetostriction constant was determined by the difference between the parallel and perpendicular magnetostriction according to formula (1). When processed so that the longitudinal direction was parallel to the grinding mark direction, the parallel magnetostriction of this magnetostrictive member was 280 ppm, and the magnetostriction constant was 285 ppm.

[0070] The surface roughness Ra of the magnetostrictive member was measured at five locations in each of the longitudinal and lateral directions of the magnetostrictive member using a surface roughness meter (Keyence Corporation, VK-X1050) at a magnification of 20x, and the average value was taken as the surface roughness Ra. The surface roughness Ra in the longitudinal direction was 0.56 μm, and the surface roughness Ra in the lateral direction was 0.82 μm. The manufacturing conditions and evaluation results are shown in Table 1.

[0071] [Examples 2 to 3] In Examples 2 and 3, in order to confirm the change in the amount of parallel magnetostriction before and after surface grinding, grinding was performed using a cup grinding wheel, a conventional method, to prevent grinding marks from remaining, and then the magnetostrictive member's surface was polished to a smooth finish and cut to a specified size, and the amount of parallel magnetostriction and magnetostriction constant were measured. The magnetostrictive member was then ground using a flat grinding wheel, with its longitudinal direction set to the same direction as the grinding direction during surface grinding. Other than the above, the same procedures were followed as in Example 1. The manufacturing conditions and evaluation results are shown in Table 1.

[0072] [Comparative Examples 1 to 2] In Comparative Examples 1 and 2, the surface grinding process in Examples 2 and 3 was carried out with the short side direction of the magnetostrictive member being the same as the grinding direction during the surface grinding process. Other than the above, the processes were the same as Examples 2 and 3. The manufacturing conditions and evaluation results are shown in Table 1. The magnetostrictive member of Comparative Example 1 is shown in FIG.

[0073] [Examples 4 to 5, Comparative Examples 3 to 4] In Examples 4 and 5 and Comparative Examples 3 and 4, the direction in which the thin plate members were cut from the single crystals in Examples 2 and 3 and Comparative Examples 1 and 2 was changed to a direction perpendicular to the crystal growth direction. Other than the above, the same procedures were followed as in Examples 4 and 5 and Comparative Examples 3 and 4. Surface roughness measurement was omitted. The manufacturing conditions and evaluation results are shown in Table 1.

[0074] [Examples 6 to 15, Examples 16 to 23] In Examples 6 to 15 and Examples 16 to 23, multiple thin plate members were produced from the same single crystal, and random magnetostrictive members were taken from among them. The rest was the same as Example 4. That is, Examples 6 to 15 and Examples 16 to 23 are magnetostrictive members produced from the same single crystal. The production conditions and evaluation results are shown in Table 1. The results of the variation in parallel magnetostriction and magnetostriction constant are shown in Tables 2 and 3. Note that surface roughness measurement was omitted.

[0075] [Examples 24 to 29, Comparative Examples 5 to 6] Examples 24 to 29 and Comparative Examples 5 and 6 were compared by varying the cutting direction of the single crystal and the grit size (grit) of the grinding stone used in the surface grinding process. Example 25 was performed in the same manner as Example 2. Examples 24 and 26 were performed in the same manner as Example 2, except that the grit size (grit) of the grinding stone used in the surface grinding process was changed. Example 28 was performed in the same manner as Example 4. Examples 27 and 29 were performed in the same manner as Example 4, except that the grit size (grit) of the grinding stone used in the surface grinding process was changed. Comparative Example 5 was performed in the same manner as Comparative Example 1. Comparative Example 6 was performed in the same manner as Comparative Example 3. The surface roughness in each example was measured in the same manner as Example 1. The manufacturing conditions and evaluation results are shown in Table 4.

[0076] [Examples 30 to 33] Examples 30 to 33 were compared by varying the plate thickness conditions of the magnetostrictive member. Example 31 was performed in the same manner as Example 2. Examples 30, 32 to 33 were the same as Example 2 except that the plate thickness conditions for the surface grinding process and the grit size (number) of the grinding stone used were changed. The surface roughness in each example was measured in the same manner as Example 1. The manufacturing conditions and evaluation results are shown in Table 5.

[0077] [Examples 34 to 37, Comparative Examples 7 to 9] Examples 34 to 37 and Comparative Examples 7 to 9 were compared by changing the angle between the extension direction of the grooves 2 and the longitudinal direction D1 to 0°, 10°, 20°, 30°, 40°, 50°, and 60°. The plate thickness was 0.5 mm. Example 34 was performed in the same manner as Example 2. Examples 35, 36, and Comparative Examples 8 and 9 were similar to Example 2 except that the grinding direction in the surface grinding process was changed to 10°, 20°, 40°, and 60°, respectively. Example 37 and Comparative Example 8 were similar to Example 4 except that the grinding direction in the surface grinding process was changed to 30° and 50°. The surface roughness in each example was measured in the same manner as Example 1. The manufacturing conditions and evaluation results are shown in Table 6.

[0078] [Examples 38 to 42] In Examples 38 to 42, polycrystals were used as the crystal material. Examples 38 to 42 were the same as Example 2, except that the prepared single crystals were changed to polycrystals. The prepared polycrystals were prepared by adjusting the raw materials to a stoichiometric ratio of iron and gallium of 81:19, and were cylindrical Fe-Ga alloy polycrystals grown by the vertical Bridgman (VB) method. The growth axis direction of the polycrystals was <100> The orientation of the {100} plane on the top or bottom surface of the polycrystal, which was perpendicular to the crystal growth axis, was confirmed by X-ray diffraction. At this time, a sample of the top surface of the crystal was measured using a Shimadzu sequential plasma emission spectrometer (ICPS-8100), and the polycrystal concentration was found to have a gallium content of 17.5 to 19.0 at%. The manufacturing conditions and evaluation results are shown in Table 7.

[0079] [Table 1]

[0080] [Table 2]

[0081] [Table 3]

[0082] [Table 4]

[0083] [Table 5]

[0084] [Table 6]

[0085] [Table 7]

[0086] [summary] The results of the examples confirm the above-mentioned improvements in the magnetostriction constant and parallel magnetostriction amount. Furthermore, the results of the examples confirm that the magnetostrictive member 1 of this embodiment has the characteristics of a high magnetostriction constant and parallel magnetostriction amount, and small variations in the magnetostriction constant and parallel magnetostriction amount between members. Furthermore, the results of the examples confirm that the manufacturing method of the magnetostrictive member according to this aspect of the present invention can easily manufacture a magnetostrictive member that has a high magnetostriction constant and parallel magnetostriction amount, and small variations in the magnetostriction constant and parallel magnetostriction amount between members.

[0087] The technical scope of the present invention is not limited to the aspects described in the above-mentioned embodiments. One or more of the requirements described in the above-mentioned embodiments may be omitted. The requirements described in the above-mentioned embodiments may be combined as appropriate. Furthermore, to the extent permitted by law, the disclosures of Japanese Patent Applications Nos. 2019-207723 and 2020-144760, as well as all documents cited in the above-mentioned embodiments, are incorporated herein by reference. [Explanation of symbols]

[0088] 1: Magnetostrictive material 2:Groove 3: Surface 4: Back side D1: Longitudinal direction D2: Lateral direction S1: Crystal preparation process S2: Crystal cutting process S3:Groove formation process S4: Cutting process

Claims

1. It is made of Fe—Ga alloy crystals having magnetostrictive properties, A plate-like body having a longitudinal direction and a lateral direction, At least one of the front and back surfaces of the plate-like body has grinding marks, The magnetostriction constant is 200 ppm or more, a parallel magnetostriction amount, which is the amount of magnetostriction when a magnetic field parallel to the longitudinal direction is applied and the amount of magnetostriction in the longitudinal direction is saturated, is 200 ppm or more; The surface roughness of the surface having the grinding marks is such that the surface roughness Ra in the longitudinal direction is smaller than the surface roughness Ra in the lateral direction. Magnetostrictive material.

2. The magnetostrictive member according to claim 1 , wherein the grinding marks extend in the longitudinal direction.

3. 3. The magnetostrictive member according to claim 2, wherein the surface roughness Ra in the longitudinal direction is 0.3 μm or more and 1.5 μm or less, and the surface roughness Ra in the lateral direction is 0.6 μm or more and 4.5 μm or less.

4. A method for manufacturing a magnetostrictive member, forming grinding marks on at least one of a front surface and a back surface of a plate-like body made of Fe—Ga alloy crystals having magnetostrictive properties and having a longitudinal direction and a lateral direction; The magnetostrictive member has a magnetostriction constant of 200 ppm or more, and a parallel magnetostriction amount, which is the amount of magnetostriction when a magnetic field parallel to the longitudinal direction is applied and the amount of magnetostriction in the longitudinal direction is saturated, is 200 ppm or more, The surface roughness of the surface having the grinding marks is such that the surface roughness Ra in the longitudinal direction is smaller than the surface roughness Ra in the lateral direction. A manufacturing method of a magnetostrictive member.

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