Manufacturing method for laminated material for magnetostrictive vibration power generation

Abstract

To provide a manufacturing method for a laminated material for magnetostrictive vibration power generation that suppresses embrittlement of an Fe-Co alloy material, and enables highly productive production of laminated materials that have excellent magnetostrictive response and excellent bonding strength, thereby providing significant industrial benefits.SOLUTION: A manufacturing method for a two-layer laminated material uses two types of metal strips as raw materials: an Fe-Co alloy material with a surface hardness of 250 HV or less, and a Ni material with a surface hardness of 140 HV or less. The method includes, in this order, a compression bonding step of stacking the two types of metal strips and compression bonded at a rolling reduction of 45 to 90%, a diffusion heat treatment step of performing diffusion heat treatment at 730 to 1400°C, a cold rolling step of performing cold rolling at a cumulative rolling reduction of 10 to 98%, and a finish heat treatment step of performing finish heat treatment at a heating temperature of 730 to 1000°C.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a laminated material having a two-layer clad structure used for magnetostrictive vibration power generation. Here, "magnetostrictive vibration power generation" refers to vibration power generation that utilizes the inverse magnetostrictive characteristics due to the vibration of a magnetostrictive material.

Background Art

[0002] Magnetostrictive vibration power generation is a method of generating electricity by stress such as impact and vibration using an energy conversion element that can utilize the shape change due to magnetization. Further, when an alternating magnetic field is applied to the above-described energy conversion element, vibration is generated.

[0003] As the configuration of the energy conversion element, a two-layer clad structure in which a material that expands when a magnetic field is applied and a material that contracts are joined is common. The material used for magnetostrictive vibration power generation is preferably a magnetic material having a large magnetostriction and a high saturation magnetic flux density.

[0004] Magnetostriction is a phenomenon in which the dimensions of a magnetic material change when magnetized. For a Fe-Co-based alloy material with a relatively large change amount, the saturation magnetostriction (λs / 10 -6 ) is about 70. For a Ni material, the saturation magnetostriction (λs / 10 -6 ) is about -40.

[0005] The saturation magnetic flux density is the magnetic flux density when the magnetic material is magnetically saturated. The larger the saturation magnetic flux density, the stronger the magnet. For example, a Fe50%-Co50% alloy material is an alloy material in which Co is added to Fe, which is a widely used magnetic material, to increase the saturation magnetic flux density. It is known as an alloy with very strong magnetic force that shows a peak in the Bohr magneton number in the Slater-Pauling curve.

[0006] For example, Patent Document 1 discloses an energy conversion member in which a magnetostrictive material and a soft magnetic material are joined. The energy conversion member described in Patent Document 1 uses, as the magnetostrictive material, an Fe-Co alloy, an Fe-Al alloy, Ni, a Ni-Fe alloy, or a Ni-Co alloy, and as the soft magnetic material, it is shown that the coercive force is 3 A / cm or less and it is made of a magnetic material having a magnetostriction constant with a sign different from that of the magnetostriction constant of the magnetostrictive material. As a specific combination, an energy conversion member is exemplified in which one is made of an Fe-Co alloy or an Fe-Al alloy having a positive magnetostriction constant, and the other is made of a Ni-0 to 20 mass% Fe alloy or a Ni-Co alloy having a negative magnetostriction constant.

[0007] And in the technology described in Patent Document 1, it is stated that a solid magnetostrictive material and a solid soft magnetic material are joined by thermal diffusion bonding, hot rolling, or hot drawing.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] However, Patent Document 1 does not describe specific conditions and the like regarding the above-described joining process.

[0010] For example, in the case of an Fe-Co alloy, embrittlement may occur or the magnetostrictive responsiveness may decrease depending on the manufacturing conditions such as heat treatment conditions. Also, in the case of an alloy with a body-centered cubic structure, since the magnetic domain walls are difficult to move due to stress, it is necessary to remove the stress generated during processing such as joining by heat treatment or the like. For these reasons, it is important to manufacture magnetic materials and the like used in energy conversion elements under manufacturing conditions suitable for the material.

[0011] In addition, in the technology described in Patent Document 1, in the joining process, single-sheet processing using strip-shaped materials is adopted. However, the yield is poor, the productivity is inferior, and it is affected from the viewpoints of materials and parts, equipment and machinery, workers, working methods, and inspection and measurement for individual products. Therefore, it is necessary to thoroughly implement quality control for each product, and there is a risk that the quality will vary depending on the management method.

[0012] In view of such a situation, an object of the present invention is to provide a method for manufacturing a laminated material for magnetostrictive vibration power generation that is excellent in productivity, has little quality variation, and has excellent vibration power generation characteristics.

Means for Solving the Problems

[0013] In order to achieve the above object, the present inventors first came up with the idea of using the material (magnetic material) to be used as a coiled metal strip from the viewpoints of improving productivity and further reducing quality variations in quality control. Then, various manufacturing conditions were studied, and two types of metal strip materials (Fe-Co-based alloy material and Ni material) were overlapped, crimped, and joined to form a laminated material having a two-layer clad structure. As a result, it can be manufactured under consistent manufacturing conditions, the productivity is improved, and from the viewpoint of quality control, the quality can be stably maintained and the quality inspection can be reduced. In addition, by using a long metal strip wound in a coil shape as the material, it becomes easy to obtain a laminated material having a uniform thickness ratio.

[0014] Based on the above findings, the present invention has been completed by further consideration. The gist is as follows. [1] A method for manufacturing a laminated material for magnetostrictive vibration power generation having a two-layer clad structure, using two types of metal strip materials, namely, an Fe-Co-based alloy material having a surface hardness of 250 HV or less and a Ni material having a surface hardness of 140 HV or less, as materials, a crimping step of overlapping the two types of metal strip materials and performing a crimping process with a reduction ratio of 45 to 90% to form a laminated material having a two-layer clad structure, a diffusion heat treatment step of performing a diffusion heat treatment at a heating temperature of 730 to 1400 °C, A cold rolling process for performing cold rolling with a cumulative reduction ratio of 10 to 98%, and a finish heat treatment process for performing finish heat treatment at a heating temperature of 730 to 1000°C, characterized in that the method for manufacturing a laminated material for magnetostrictive vibration power generation comprises these steps in this order. [2] The method for manufacturing a laminated material for magnetostrictive vibration power generation according to [1], characterized in that the laminated material after cold rolling is a cold-rolled metal strip having a plate thickness of 0.03 to 2.0 mm. [3] The method for manufacturing a laminated material for magnetostrictive vibration power generation according to [1] or [2], characterized in that the laminated material after cold rolling contains an Fe-Co alloy layer with a thickness of 40 to 60% of the total plate thickness. [4] The method for manufacturing a laminated material for magnetostrictive vibration power generation according to any one of [1] to [3], characterized in that the crimping treatment is performed in a processing temperature range of 20 to 720°C. [5] The method for manufacturing a laminated material for magnetostrictive vibration power generation according to any one of [1] to [4], characterized in that the diffusion heat treatment has a holding time of 1 to 30 minutes, and the finish heat treatment has a holding time of 2 hours or more. [6] The Fe-Co alloy material has a composition consisting of, by mass%, Fe: 40 to 60%, or further V: 1 to 5%, with the balance being Co and unavoidable impurities, and the Ni material has a composition consisting of, by mass%, Ni: 99.5% or more, with the balance being unavoidable impurities. The method for manufacturing a laminated material for magnetostrictive vibration power generation according to any one of [1] to [5]. [Advantages of the Invention]

[0015] According to the present invention, embrittlement of the Fe-Co alloy material is suppressed, a laminated material excellent in magnetostrictive responsiveness and having excellent bonding strength can be obtained with high industrial productivity, and as a laminated material for vibration power generation, it has an extremely remarkable effect in the industry. [Brief Description of the Drawings]

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Mode for Carrying Out the Invention

[0017] The present invention is a method for manufacturing a laminated material having a two-layer clad structure, which is useful for magnetostrictive vibration power generation. The laminated material obtained in the present invention has a two-layer clad structure of an Fe-Co based alloy material and a Ni material.

[0018] In the method for manufacturing the laminated material of the present invention, two types of metal strip plates, an Fe-Co based alloy material and a Ni material, are used as materials. As shown in FIG. 1, preferably, a pretreatment step, a crimping step, a diffusion heat treatment step, a cold rolling step, and a finishing heat treatment step are provided in this order to obtain a laminated material (metal strip plate) having a two-layer clad structure. Hereinafter, each step will be described.

[0019] [Materials] In the present invention, two types of metal strip plates, an Fe-Co based alloy material and a Ni material, are used as materials. Here, the Fe-Co based alloy material has a composition consisting of Fe: 40 to 60% by mass, and the balance Co and unavoidable impurities. Further, it may have a composition containing 1 to 5% of V.

[0020] If the Fe-Co based alloy material has a composition within the above range, the saturation magnetostriction (λs / 10 -6 ) is as large as 50 to 70, and the saturation magnetic flux density also shows a strong magnetic force such that the Bohr magneton number exceeds 2.25 in the Slater-Pauling curve. By using an Fe-Co based alloy material having such characteristics, an energy conversion element with high vibration power generation characteristics can be obtained. In addition, by further containing V within the above range, the cold workability is improved, and the magnetostriction and the saturation magnetic flux density can be maintained at a high level.

[0021] In addition, as the Ni material, it is preferable to use a material having a Ni content of 99.5% or more by mass, with the balance being inevitable impurities. If the Ni content is less than 99.5%, the softening temperature and work hardening characteristics will change, which may affect the uniformity of the thickness ratio after bonding. Note that for the Ni material with the above composition, the saturation magnetostriction (λs / 10 -6 ) is -40, and the magnetostriction difference from the Fe-Co alloy material becomes very large.

[0022] The metal strip used as the material should have a surface hardness such that the Fe-Co alloy material has a Vickers hardness of 250 HV or less and the Ni material has a Vickers hardness of 140 HV or less. If each exceeds the above hardness, the bonding at the bonding interface will be poor and the adhesion strength (also referred to as the bonding strength) will decrease. When bonding (crimping) in the crimping process, a softer material has better workability and a larger reduction ratio per crimping can be achieved. Therefore, the adhesion strength improves along with the degree of deformation at the bonding interface. Also, at this time, the bonding is between the newly formed surfaces of the bonding interface. The higher the reduction ratio, the larger the area of the newly formed surface, so the adhesion strength improves. Note that the adjustment of the surface hardness of the metal strip used as the material is preferably performed by heating in an annealing furnace or the like.

[0023] Note that since the Fe-Co alloy material used as the material has a higher surface hardness (deformation resistance) than the Ni material to be combined, when manufacturing a laminated material by crimping or the like using metal strips (materials) of the same thickness as the Ni material, the thickness of the Ni material becomes thinner due to the difference in deformation resistance. Therefore, it is necessary to appropriately adjust the material thicknesses of the Fe-Co alloy material and the Ni material according to the difference in the surface hardness (deformation resistance) of the materials. In the present invention, it is preferable that the material thickness of the Fe-Co alloy material is 85 to 95% of the material thickness of the Ni material. Thereby, the thickness of the Fe-Co alloy layer in the laminated material as the product can be 40 to 60% of the total thickness of the laminated material. Note that it is preferably 45 to 55%. By making the thickness of the Fe-Co alloy layer approach 50% of the total thickness of the laminated material, the cancellation of the magnetostriction effect and the inverse magnetostriction effect is eliminated.

[0024] Note that instead of the Fe-Co alloy material, Fe-Ni alloy materials or Fe-Al alloy materials, which are the same magnetic materials, may be used. Although these alloy materials are inferior to the Fe-Co alloy material in terms of saturation magnetostriction and saturation magnetic flux density, by applying the manufacturing method of the present invention, they can be used as laminated materials for magnetostrictive vibration power generation.

[0025] Also, instead of the Ni material having the above-described composition, Ni-Co alloy materials and soft magnetic materials (Fe materials) such as SPCC can be mentioned as materials that can similarly maintain vibration power generation characteristics when combined with the Fe-Co alloy material. By combining Ni-Co alloy materials or Fe materials with the Fe-Co alloy material and applying the manufacturing method of the present invention, although the characteristics are inferior to those of the combination of the Fe-Co alloy material and the Ni material, it is possible to manufacture a laminated material for magnetostrictive vibration power generation that can similarly maintain vibration power generation characteristics. Note that the surface hardness of the Fe-Co alloy material, Fe-Ni alloy material, and Fe-Al alloy material used as the material is preferably 250 HV or less in terms of Vickers hardness, and the surface hardness of the Ni material, Ni-Co alloy material, and soft magnetic material (Fe material) is preferably 140 HV or less in terms of Vickers hardness.

[0026] [Pretreatment process] First, in order to facilitate the pressure bonding of the two materials, it is preferable to perform a treatment for activating the surface of the entire surface of the Fe-Co alloy material and the Ni material, which are the materials, before the pressure bonding process. The treatment for activating the surface is preferably a brushing treatment. The brushing treatment is a treatment for polishing the surface of the material with a brush. Note that as long as it is a treatment for activating the surface, a chemical treatment such as pickling, a mechanical treatment such as grinding or blasting with a grinder or a blast, or an ion etching method may be applied. The surface roughness after the activation treatment is preferably at least twice the surface roughness before the activation treatment in terms of the arithmetic mean roughness Ra, with Ra: 0.1 μm or more and 3.0 μm or less for the Fe-Co alloy material and Ra: 0.1 μm or more and 4.0 μm or less for the Ni material. Here, the surface roughness shall be measured in accordance with the provisions of JIS B 0601.

[0027] [Pressure bonding process] In the crimping process, two types of materials (Fe-Co alloy material and Ni material) that have undergone surface activation treatment are overlapped, and a crimping treatment is performed with a reduction ratio of 45 to 90% to mechanically and physically bond (crimp) them into a laminated material with a two-layer clad structure. In the crimping process, as shown in FIG. 2, a method is used in which the metal strip plates 1 and 2 are overlapped and crimped by rolling using a roll 3.

[0028] If the reduction ratio is less than 45%, the joining (crimping) is not sufficiently performed. If the reduction ratio exceeds 90%, ear cracking occurs during crimping, making crimping difficult. Here, ear cracking refers to cracks that occur on the surface of the plate material near the edge end in the plate width direction of the crimped material. For these reasons, the reduction ratio in the crimping process is in the range of 45 to 90%. Also, it is preferable that the crimping process is performed once.

[0029] The type of cold rolling mill used in the crimping process does not particularly need to be limited, and any commonly used rolling mills such as two-high rolling mills and four-high rolling mills can be applied, but it is preferable to use a multi-high rolling mill in which the reduction force distribution and the plate thickness profile in the plate width direction are uniform.

[0030] Also, the crimping process is performed in a processing temperature range of 20 to 720°C. If the temperature is less than 20°C, it is difficult to manufacture at a temperature lower than this temperature considering the heat generation during plastic processing. Also, if the temperature exceeds 720°C, there is a risk of becoming extremely brittle due to the regularization of the α' phase. Therefore, during the warm crimping process, it is preferable to adjust it within the above temperature range using a temperature controller or the like.

[0031] The regular-irregular transformation point of the body-centered cubic lattice α phase in the Fe-Co alloy material exists around 730°C, and in the temperature range of 700°C or lower, it becomes a mixed phase of the body-centered cubic lattice α' regular phase and the face-centered cubic lattice γ phase. In particular, when the cooling rate from around the transformation point of 730°C is slow, a embrittlement phenomenon is observed due to the regularization of the α' phase.

[0032] In addition, when a surface activation treatment is performed as a pretreatment step, the crimping treatment is preferably performed before 12 hours have elapsed after the pretreatment step. If the crimping treatment is performed after 12 hours have elapsed, the bonding strength at the bonding interface in the obtained laminated material (clad material) may decrease.

[0033] In addition, the laminated material (also referred to as the laminated material after the crimping treatment), which is a two-layer metal strip plate joined (crimped) in the crimping step, is usually wound up by a winder (not shown).

[0034] [Diffusion heat treatment step] The laminated material obtained through the crimping step (also referred to as the laminated material after the crimping treatment) is subjected to a diffusion heat treatment for the purpose of mutual diffusion of metal atoms at the bonding interface of the laminated material. The diffusion heat treatment is a treatment of heating in the temperature range of 730 to 1400°C.

[0035] When the heating temperature is less than 730°C, mutual diffusion at the bonding interface of the laminated material hardly occurs, and sufficient bonding strength may not be obtained. On the other hand, when the heating temperature exceeds 1400°C, since the melting point of nickel is 1453°C, there is a risk of melting.

[0036] In addition, the holding time of the diffusion heat treatment is preferably in the range of 1 to 30 minutes. When the holding time is less than 1 minute, mutual diffusion at the bonding interface of the laminated material hardly occurs, and sufficient bonding strength may not be obtained. On the other hand, when the holding time exceeds 30 minutes, the productivity is significantly reduced.

[0037] Through the diffusion heat treatment as described above, the bonding interface is firmly bonded, and the bonding strength of the laminated material is improved. The bond at the bonding interface after the mutual diffusion of metal atoms is very strong, and no peeling of the bonded portion has been confirmed even in the 90-degree repeated bending test.

[0038] The diffusion heat treatment as described above is preferably performed using a continuous heat treatment furnace. In addition, when using a continuous heat treatment furnace, the maximum thickness of the material to be heat-treated (the laminated material after the crimping treatment) is preferably 5.0 mm or less. When the maximum thickness exceeds 5.0 mm, the heat treatment cannot be completed within 30 minutes.

[0039] In addition, in order to prevent embrittlement due to regularization of the α' phase starting from around the transformation point of 730°C in the Fe-Co alloy material, it is necessary to increase the cooling rate after diffusion heat treatment, and it is preferably set to 300°C / min or more. Further, the diffusion heat treatment is preferably carried out in an inert gas atmosphere such as Ar or N or a reducing atmosphere of hydrogen gas.

[0040] [Cold rolling process] In the cold rolling process, for the diffusion heat-treated laminated material (bonded laminated material) in the form of a metal strip, the reduction rate is selected so that the cumulative reduction rate is 1 to 98%, and cold rolling is performed to obtain a laminated material with a predetermined product plate thickness (laminated material after cold rolling).

[0041] When the cumulative reduction rate is less than 1%, the force of the front and rear tensions of the coiler acts stronger than the rolling force, and the material to be rolled slips, making cold rolling difficult. Also, when the cumulative reduction rate exceeds 98%, the material to be rolled reaches the rolling limit due to work hardening, and it becomes necessary to add softening heat treatment, resulting in a decrease in productivity. Considering productivity, the cumulative reduction rate is preferably 5 to 90%. The cumulative reduction rate referred to here can be calculated by the following formula. Cumulative reduction rate (%) = {(plate thickness before cold rolling) - (plate thickness after cold rolling)} ÷ (plate thickness before cold rolling) × 100 Cold rolling is a repeated rolling that performs rolling multiple times. The number of repetitions is preferably 5 to 10 times. Also, although it is wound into a coil by a coil winder (not shown) for each rolling, when the number of rolling passes is large, it is preferably a reverse type that can be wound not only in one direction but also in the reverse direction. As the rolling mill used for cold rolling, any of a conventional two-high rolling mill, four-high rolling mill, and multi-high rolling mills such as a Sendzimir rolling mill and a Loewy rolling mill are suitable, but it is preferable to select a rolling mill with a uniform reduction force distribution and plate thickness profile in the plate width direction, for example, a multi-high rolling mill. This is because after the finish heat treatment process, which is the final process, it may be slit (not shown) as necessary and cut and shipped by dividing in the width direction. Fig. 3 shows an outline of cold rolling using a four-high rolling mill.

[0042] During cold rolling, the material to be rolled is cooled with rolling oil. However, since heat generation during plastic working is inevitable, cold rolling is preferably carried out in a processing temperature range of room temperature to 200°C. More preferably, it is in the temperature range of room temperature to 100°C.

[0043] Also, the plate thickness of the laminated material after cold rolling is preferably set to 0.03 to 2.0 mm, which is the predetermined product plate thickness. If the plate thickness is less than 0.03 mm, the flatness deteriorates, and it becomes difficult to correct the shape with a tension leveler. The flatness is preferably such that the warp or undulation is 1 mm or less in an area of 100 mm 2 The measurement of flatness shall be carried out on a surface plate using a thickness gauge or a dial gauge. When the plate thickness of the cold-rolled laminated material exceeds 2.0 mm, the holding time in the diffusion heat treatment process exceeds 30 minutes, resulting in a decrease in productivity.

[0044] In the laminated material after cold rolling, the thickness of the Fe-Co-based alloy layer in the laminated material is set to 40 to 60% of the total thickness. If the thickness of the Fe-Co-based alloy layer is less than 40% or exceeds 60% of the total thickness, the cancellation of the magnetostrictive effect / inverse magnetostrictive effect of the Fe-Co-based alloy material and the Ni material occurs, and the vibration power generation characteristics deteriorate. Preferably, it is 45 to 55% of the total thickness. The thickness of the Fe-Co-based alloy layer in such a laminated material after cold rolling can be achieved by adjusting the respective material thicknesses.

[0045] [Finishing heat treatment process] In the finishing heat treatment process, the above-mentioned laminated material (laminated material after cold rolling) is subjected to a finishing heat treatment with a heating temperature of 730 to 1000°C to obtain a product.

[0046] When the heating temperature is less than 730 °C, the stress in the Fe-Co alloy material cannot be removed. In the alloy with a BCC structure, the movement of magnetic domain walls becomes difficult due to the residual stress, resulting in a decrease in vibration power generation characteristics. Also, when the heating temperature exceeds 1000 °C, the γ phase begins to precipitate, the function as a magnetic material deteriorates, and the magnetostriction and saturation magnetic flux density also become smaller. Preferably, it is 900 °C or lower. When using an Fe-Ni alloy material or an Fe-Al alloy material as the raw material, the heating temperature is preferably 370 - 1200 °C for the Fe-Ni alloy material and 700 - 1200 °C for the Fe-Al alloy material.

[0047] In addition, since the heat treatment furnace used in the finish heat treatment needs to cool slowly after the finish heat treatment, it is preferably a batch-type heat treatment furnace. The finish heat treatment process is the final process, and it is important to increase the magnetostriction without considering embrittlement. The α' phase of the Fe-Co alloy material becomes brittle by normalization, but the saturation magnetostriction (λs / 10 -6 ) is 70, which is higher than that of the α phase and γ phase. Therefore, it is appropriate that the structure after the finish heat treatment is the α' phase. Therefore, the cooling after the finish heat treatment is preferably slow cooling, and the cooling rate is preferably 300 °C / hour or less.

[0048] Also, the holding time of the finish heat treatment is preferably 2 hours or more. If the holding time is less than 2 hours, the α phase cannot be sufficiently precipitated in the heating temperature range of 730 - 1000 °C, and a mixed phase of the α' phase and γ phase will occur after cooling, resulting in a decrease in magnetostriction. The atmosphere of the finish heat treatment is preferably a reducing atmosphere of hydrogen gas. During cooling, an inert gas atmosphere such as Ar or N is preferably used.

[0049] The laminated material manufactured by the manufacturing method including the above-described steps can improve the power generation efficiency of vibration power generation utilizing the inverse magnetostriction characteristics as an energy conversion member. For example, when the laminated material according to the present invention is used as a double pendulum beam and vibrated in both directions, tensile and compressive deformations repeatedly occur in the Fe-Co alloy layer and the Ni layer to generate electricity. Moreover, since the direction of the voltage is always the same in both layers, high power generation efficiency can be achieved. Also, when the laminated material of the present invention is used, the vibration efficiency of the vibrating portion utilizing the magnetostriction characteristics can also be improved.

[0050] Hereinafter, the present invention will be further described based on examples.

Examples

[0051] An Fe-Co alloy material (types: F1 to F9) having the composition shown in Table 1 and a Ni material (types: N1 to N3) having the composition shown in Table 2 were prepared as materials. The shapes of the materials were both coiled metal strip plates (single quantity: 1.0 kg) for the Fe-Co alloy material and the Ni material, and the dimensions were a plate thickness of 0.2 to 4.8 mm × a width of 40 to 150 mm × a length of 20 to 100 m.

[0052] The hardness of the prepared Fe-Co alloy material and Ni material as materials was variously changed as shown in Table 3 by annealing treatment. Further, according to the hardness of the Ni material, the thickness of the Fe-Co alloy material was adjusted by cold rolling so as to be in the range of 85 to 95% of the thickness of the Ni material. In addition, in some cases, the thickness of the Fe-Co alloy material was prepared outside the range of 85 to 95% of the thickness of the Ni material. Further, as a pretreatment step, a surface activation treatment of performing brushing treatment on the entire surface of the metal strip plate as a material was performed. After the activation treatment, the surface roughness Ra measured according to JIS B 0601 was Ra: 0.1 to 3.0 μm for the Fe-Co alloy material and Ra: 0.1 to 4.0 μm for the Ni material.

[0053] The two types of materials (metal strip plates) whose hardness and thickness were adjusted as described above were combined as shown in Table 3, and a laminated material having a two-layer structure was manufactured by a manufacturing method including a crimping step, a diffusion heat treatment step, a cold rolling step, and a finishing heat treatment step in this order.

[0054] [Crimping step] The two types of materials (Fe-Co alloy material and Ni material) were overlapped, and using a multi-stage rolling mill, in the state of a metal strip plate, a single crimping treatment was performed at the temperature and reduction ratio shown in Table 3 to crimp the two types of materials to obtain a laminated material having a two-layer structure. After the crimping treatment, it was wound into a coil using a winder. In the case of non-crimping, the subsequent treatment was aborted. In addition, the plate thickness of the laminated material obtained by the crimping treatment was also noted in Table 3.

[0055] "Diffusion Heat Treatment Process" The laminated material after the obtained crimping treatment was subjected to diffusion heat treatment in a continuous heat treatment furnace at the temperatures and holding times shown in Table 3. The diffusion heat treatment was carried out in a hydrogen gas atmosphere. After the diffusion heat treatment, cooling was performed by indirect water cooling. The cooling rate was in the range of 300 - 350 °C / min.

[0056] In addition, the bonding strength of the laminated material after the diffusion heat treatment was evaluated using the laminated material as a test piece. The evaluation of the bonding strength was carried out by a bending test in accordance with the provisions of JIS Z 2248. The bending test was a 90° bend using a pressing jig (tip radius R: 0.4 mm). After repeatedly bending until breakage, the bending fracture surface was observed with a stereomicroscope (×20), and when the fracture surface did not peel at the joint, it was evaluated as "○", and when it peeled (broke) at the joint, it was evaluated as "×". The obtained results were also shown in Table 3. Note that those evaluated as "×" did not undergo subsequent processing.

[0057] [Cold Rolling Process] The laminated material after the diffusion heat treatment was repeatedly cold rolled using a multi-stage rolling mill at the temperatures and cumulative reduction ratios shown in Table 3 to obtain a laminated material with a predetermined product plate thickness (the laminated material after cold rolling). After cold rolling, it was wound into a coil using a coiler. The plate thickness of the obtained laminated material was also shown in Table 3.

[0058] In addition, when cold rolling the laminated material after the diffusion heat treatment, the presence or absence of breakage in the first cold rolling was observed. When it broke in the first cold rolling, it was evaluated as "×", and when it did not break, it was evaluated as "〇" for the embrittlement of the laminated material (the laminated material after the diffusion heat treatment). The obtained results were also shown in Table 3. Note that those that broke during cold rolling did not undergo subsequent processing.

[0059] [Final Heat Treatment Process] The obtained laminated material after cold rolling was subjected to finish heat treatment in a batch-type heat treatment furnace at the heating temperature and holding time shown in Table 3 to obtain a product (laminated material). The finish heat treatment was carried out in a reducing atmosphere of hydrogen gas. After the finish heat treatment, it was slowly cooled. The cooling rate was in the range of 250 to 300 °C / hour.

[0060] For the obtained product (laminated material), the power generation amount (mW) was measured using the power generation device shown in Fig. 4. The obtained power generation amount (mW) was compared with the power generation amount (mW) when a single material of Fe-Co-based alloy (type: 60Fe5VCo) was used to evaluate the power generation vibration characteristics. When the power generation amount was three times or more that when a single material of Fe-Co-based alloy was used, it was evaluated as ○, and when it was less than three times, it was evaluated as ×.

[0061] As shown in Fig. 4, the power generation device is composed of a yoke 9, a permanent magnet 8, a power generation coil 6, a vibration source 7, and a weight 10. The laminated material (two-layer structure composed of an Fe-Co-based alloy layer 5 and an Ni layer 4) as the measurement piece had a thickness equal to the product plate thickness and a width of 5 mm × a length of 50 mm. The weight of the weight was adjusted so that the resonance frequency was approximately 70 Hz.

[0062] Also, for the obtained product (laminated material), the cross-section in the plate thickness direction was polished, imaged using an optical microscope (magnification: 100 times), the thicknesses of each layer (Fe-Co-based alloy layer 5 and Ni layer 4) were measured, and the thickness ratios of each layer were calculated. The obtained results were also listed in Table 3.

[0063]

Table 1

[0064]

Table 2

[0065]

Table 3

[0066] In all of the examples of the present invention, it was confirmed that the bonding interface had high bonding strength, embrittlement of the laminate was suppressed, and excellent vibration power generation characteristics were obtained. On the other hand, in the comparative examples outside the scope of the present invention, either pressure bonding could not be achieved, or even if pressure bonding was possible, the bonding strength was insufficient, embrittlement was progressing, or the vibration power generation characteristics were degraded.

[0067] For laminate No. 25 (comparative example), since the surface hardness of the Ni material used as the material exceeded 140 HV and was high, the adhesion strength during the pressure bonding process was low and bonding could not be achieved (non-bonding). Also, for laminate No. 26, since the surface hardness of the Fe-Co alloy material used as the material exceeded 250 HV and was high, the bonding strength during the pressure bonding process was low and bonding could not be achieved (non-bonding). Further, for laminate No. 27, since the reduction rate during the pressure bonding process was less than 45% and was low, bonding could not be achieved (non-bonding). Also, for laminate No. 28, since the processing temperature during the pressure bonding process exceeded 720 °C, embrittlement due to the regularization of the α' phase progressed and it broke during the first cold rolling. Also, for laminate No. 29, since the heating temperature of the diffusion heat treatment was less than 730 °C, mutual diffusion at the bonding interface was difficult to occur and sufficient bonding strength could not be obtained. Also, for laminate No. 30, since the holding time of the diffusion heat treatment was less than 1 minute, mutual diffusion at the bonding interface was difficult to occur and sufficient bonding strength could not be obtained. Also, for laminate No. 31, since the heating temperature of the finish heat treatment was less than 730 °C, the stress in the Fe-Co alloy material could not be removed and the vibration power generation characteristics were degraded. Also, for laminate No. 32, since the holding time of the finish heat treatment was less than 2 hours, a mixed phase of the α' phase and the γ phase occurred after cooling and the vibration power generation characteristics were degraded. Also, for laminates No. 33 and No. 34, since the thickness of the Fe-Co alloy layer after cold rolling was outside the range of 40 to 60% of the total thickness of the laminate (cold-rolled laminate), cancellation of the magnetostriction / inverse magnetostriction effects of the Fe-Co alloy material and the Ni material occurred and the vibration power generation characteristics were degraded.

Explanation of Reference Numerals

[0068] 1 Fe-Co alloy material 2 Ni material 3 Roll 4 Ni layer 5 Fe-Co alloy layer 6 Coil for power generation 7 Vibration source 8 Permanent magnet 9 Yoke 10 Weight

Claims

1. A method for manufacturing a laminated material for magnetostrictive vibration power generation having a two-layer clad structure, comprising: using two types of metal strip materials, an Fe-Co alloy material having a surface hardness of 250 HV or less and a Ni material having a surface hardness of 140 HV or less as raw materials, a crimping step of overlapping the two types of metal strip materials and performing a crimping process with a reduction ratio of 45 to 90% to obtain a laminated material having a two-layer clad structure, a diffusion heat treatment step of performing a diffusion heat treatment at a heating temperature of 730 to 1400 °C, a cold rolling step of performing cold rolling with a cumulative reduction ratio of 10 to 98%, and a finish heat treatment step of performing a finish heat treatment at a heating temperature of 730 to 1000 °C, in this order. The method for manufacturing a laminated material for magnetostrictive vibration power generation is characterized by comprising these steps.

2. The method for manufacturing a laminated material for magnetostrictive vibration power generation according to claim 1, wherein the laminated material after cold rolling is a cold-rolled metal strip having a plate thickness of 0.03 to 2.0 mm.

3. The method for manufacturing a laminated material for magnetostrictive vibration power generation according to claim 2, wherein the laminated material after cold rolling contains an Fe-Co alloy layer with a thickness of 40 to 60% of the total plate thickness.

4. The method for manufacturing a laminated material for magnetostrictive vibration power generation according to claim 1, wherein the crimping process is performed in a processing temperature range of 20 to 720 °C.

5. The method for manufacturing a laminated material for magnetostrictive vibration power generation according to claim 1, wherein the diffusion heat treatment has a holding time of 1 to 30 minutes, and the finish heat treatment has a holding time of 2 hours or more.

6. The method for manufacturing a laminated material for magnetostrictive vibration power generation according to claim 1, wherein the Fe-Co alloy material has a composition consisting of, by mass%, Fe: 40 to 60%, or further V: 1 to 5%, with the balance being Co and unavoidable impurities, and the Ni material has a composition consisting of, by mass%, Ni: 99.5% or more, with the balance being unavoidable impurities.

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