Method for evaluating embrittlement of amorphous alloy ribbon

Abstract

To provide a new method for evaluating the embrittlement of an amorphous alloy ribbon.SOLUTION: A method for evaluating the embrittlement of an amorphous alloy ribbon comprises: pressing a pressing member at a plurality of positions on an amorphous alloy ribbon from the side of one surface to dot a pressed part having an impression formed by pressing the pressing member on the amorphous alloy ribbon; and estimating embrittlement by the number or distribution of the pressed parts having a generated crack.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for evaluating embrittlement of an amorphous alloy ribbon and a test apparatus for evaluating embrittlement of an amorphous alloy ribbon.

Background Art

[0002] The molten metal adjusted to an appropriate composition is continuously cast by a single-roll ultra-rapid solidification method or the like under a cooling condition of about 10 6 °C / second. The ribbon-shaped amorphous alloy obtained is long and has excellent magnetic properties, and is adopted as a magnetic material for magnetic cores used in transformers, reactors, filters, motors, etc.

[0003] Although the atomic structure of the amorphous alloy is ideally in an amorphous state as a whole, in the amorphous alloy ribbon, due to surface scratches of the cooling roll, unevenness of the cooling roll surface due to adhesion of foreign substances, non-uniform temperature distribution of the cooling roll, etc., there are parts where cooling cannot be obtained at an appropriate speed due to various factors in the manufacturing process, and some may become crystallized. Also, due to the influence of impurities contained in the alloy, etc., there may be cases where partial fluctuations in the alloy composition occur in the amorphous alloy ribbon. Such amorphous alloy ribbons tend to become embrittled, and even if predetermined magnetic properties are obtained, there is a problem that the strength becomes weak in the embrittled parts.

[0004] It is known that tear tests are used to evaluate the embrittlement of amorphous alloy ribbons. Specifically, there are evaluation methods defined as strip tear ductility in JIS C2534 (2017) and IEC60404-8-11. In these tests, a test piece (sample) of a certain length (twice the circumference of the casting roll) is obtained from a long amorphous alloy ribbon, and the test piece is torn in the casting direction of the amorphous alloy ribbon, and it is classified and evaluated by the number of brittle spots generated. A brittle spot is defined as an area where damage occurs with a dimension of about 6 mm or more, such as a change in the path or direction of the crack and fragment separation, when the test piece is torn. The characteristics of strip tear ductility are classified into five levels by the number of brittle spots. It is specified that the test piece is torn in the direction parallel to the casting direction at five positions in the center of the width direction, as well as 12.7 mm and 25.4 mm in the width direction from the edge, and the number of brittle spots in one test piece does not exceed 10.

[0005] Amorphous alloy ribbons are provided to the market as they are after primary processing by casting, or after additional processing such as cutting off the edge portions in the width direction of the ribbon or cutting them to a predetermined width dimension and length so that they can be easily handled during transportation. Generally, those subjected to secondary processing such as further cutting or punching are used for cores. Hereinafter, the amorphous alloy ribbon before secondary processing is distinguished and called the raw material for the sake of easy explanation.

[0006] It is known that brittle raw materials have problems with cuttability, such as cracks occurring at the edges of the amorphous alloy ribbon or the ribbon breaking due to cutting. Therefore, as in Patent Document 1, the embrittlement evaluation by the tear test may be used as an index for the cuttability of the amorphous alloy ribbon (raw material).

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] Evaluating the degree of embrittlement of an amorphous alloy ribbon by a tearing test is useful for reducing breakage or the like when subjecting a selected base material to secondary processing and performing splitting in the same direction as cutting. However, in the said tearing test, there is a limit to the lower limit of the width dimension of the sample to be subjected to the test due to the definition of the tearing position, and the possibility of overlooking embrittled portions increases with wider samples.

[0009] In addition, when continuously punching the base material at a narrow pitch, punching it into a complex shape or a wide width, or cutting the base material at a narrow pitch in a direction different from the casting direction, it is required to evaluate the embrittled state in more detail. However, since the said tearing test is a simple evaluation method, it is difficult to examine in detail the degree of brittleness, embrittled portions, and their distribution. In response to such demands, no new evaluation method different from the tearing test has been proposed so far, nor has a test apparatus for evaluation been provided.

[0010] Therefore, an object of the present disclosure is to provide a new method for evaluating the embrittlement of an amorphous alloy ribbon, or to provide a test apparatus used for a new method for evaluating the embrittlement of an amorphous alloy ribbon.

Means for Solving the Problems

[0011] A method for evaluating embrittlement of an amorphous alloy ribbon according to the present invention is as follows. Pressing members are pressed against one side of the amorphous alloy ribbon disposed on an elastic member from a plurality of positions to form pressure-applied portions with indentations scattered thereon. Embrittlement is evaluated based on the number or distribution of cracks generated in the plurality of pressure-applied portions. This is a method for evaluating embrittlement of an amorphous alloy ribbon. It is preferable to magnetically adsorb and fix the amorphous alloy ribbon. It is also preferable to determine cracks based on discontinuity of undulation of the surface shape of the pressure-applied portion, or the light transmission state of the pressure-applied portion, or a change in the decrease of the pressing force of the pressing member.

Effects of the Invention

[0012] According to the present disclosure, a new method for evaluating embrittlement of an amorphous alloy ribbon can be provided. Further, according to the present disclosure, a test apparatus used for the new method for evaluating embrittlement of an amorphous alloy ribbon can be provided.

Brief Description of the Drawings

[0013]

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Embodiments for Carrying Out the Invention

[0014] The present disclosure will be described with reference to the drawings in relation to preferred embodiments, but is not necessarily limited to the embodiments described below, and includes alternatives and modifications included in the claims unless otherwise specified. Also, in the drawings referred to, the same reference numerals indicate the same elements, and duplicate content in the description may be omitted as appropriate.

[0015] A method for evaluating the embrittlement of an amorphous alloy ribbon according to the present disclosure is a method in which a pressing member is pressed against a plurality of positions of the amorphous alloy ribbon from one side, and pressure-imparted portions where the pressing member is pressed and indentations are formed are scattered on the amorphous alloy ribbon, the cracks in the pressure-imparted portions are observed, and the embrittlement is evaluated based on the number or distribution of the pressure-imparted portions where cracks have occurred.

[0016] FIG. 1 is a flowchart showing an embodiment of a method for evaluating the embrittlement of an amorphous alloy ribbon. In the method for evaluating the embrittlement of an amorphous alloy ribbon newly proposed by the present inventors (hereinafter referred to as the embrittlement evaluation method), for example, an amorphous alloy ribbon of a predetermined size obtained from a mother roll (hereinafter referred to as a sample) is used, and in a pressing step of pressing a pressing member against the sample to form a pressure-imparted portion, the sample is pressed from one side so that an indentation is formed to partially deform the sample, and a sample having a plurality of pressure-imparted portions formed at a predetermined interval is created. In the following description, the sample before pressing is referred to as a test sample, and the sample after pressing is referred to as an evaluation sample for distinction, but the reference numerals assigned to each sample are the same. Note that the amorphous alloy ribbon for evaluating embrittlement is not limited to the mother roll, and may be a secondary-processed amorphous alloy ribbon. The secondary-processed amorphous alloy ribbon may be evaluated as a sample as it is, or a sample may be cut out from the secondary-processed amorphous alloy ribbon for evaluation.

[0017] In the next pressing part confirmation process, the obtained evaluation sample is used to check for cracks in the pressing part. In the pressing process, for the purpose of evaluating embrittlement, the force applied to the test sample (also referred to as the pressing force) is set such that in a plurality of pressing parts formed in the test sample, there are both pressing parts where cracks have occurred and pressing parts where cracks have not occurred. By forming pressing parts across the entire plane of the area for evaluating embrittlement in the test sample, the embrittlement of the amorphous alloy ribbon can be evaluated using the number of pressing parts where cracks have occurred (degree of embrittlement) and the distribution of the pressing parts (embrittlement locations) where cracks have occurred. Although details will be described later, by detecting the change from the pressing force information obtained in the formation of the pressing part, it is possible to determine the presence or absence of cracks in the pressing part, and it is also possible to perform a crack inspection process together with the pressing process.

[0018] The amorphous alloy ribbon of the present disclosure is not particularly limited. For example, those having a composition of the Fe-Si-B system known as Metglas (registered trademark) 2605SA1 material or 2605HB1M material, and those having compositions of the Fe-Si-B-C system, Fe-Si-B-C-Cr system, etc. containing other elements. Also, the amorphous alloy ribbon may be one that can be nanocrystallized by heat treatment. For example, those having a composition of the Fe-Si-B-Cu-Nb system known as Finemet (registered trademark), and those having compositions of other Fe-Cu-Si-B systems, Fe-Cu-B systems, Fe-Ni-Cu-Si-B systems, etc. These amorphous alloy ribbons are available in a thickness of 10 to 40 μm and a width of 50 mm to 220 mm.

[0019] When evaluating the embrittlement of the original web, the test sample is preferably obtained from a continuous portion of a certain length across the entire width of the original web. The certain length is preferably, for example, equal to or greater than the circumference of the casting roll in continuous casting, typically 1 m or more in length, and it may be used as a test sample as a whole, or divided into a plurality of pieces of predetermined dimensions for use as test samples. The size of the test sample is not particularly limited as long as it can be placed on the sample stage of the device described below and a pressurized portion can be formed. The upper limit dimension of preference is defined by the width dimension of the amorphous alloy ribbon. The lower limit dimension is preferably determined in consideration of the tip dimension of the pressurizing member and the interval of the pressurized portion described below. Typically, it is rectangular or square, with a width of 10 mm to 250 mm and a length of 10 mm to 250 mm. Preferably, the width is 20 mm or more and the length is 20 mm or more, and more preferably, the width is 30 mm or more and the length is 30 mm or more. When evaluating the embrittlement of an amorphous alloy ribbon different from the original web, the amorphous alloy ribbon to be evaluated may be evaluated as a test sample as it is, or a test sample may be taken out from the amorphous alloy ribbon to be evaluated for evaluation.

[0020] The embrittlement evaluation method and the test apparatus used therefor will be described in detail. FIGS. 2 and 3 are schematic diagrams showing the schematic configuration of the test apparatus used for embrittlement evaluation. In an example of the configuration of the test apparatus 100 of the present disclosure, it includes at least a sample stage 110 having a plane on which a test sample 10 can be placed, and a pressurizing means located above the sample stage 110 and capable of pressurizing in a direction substantially perpendicular to the plane of the test sample 10 placed on the sample stage 110.

[0021] In the test apparatus 100 illustrated in FIG. 2, an X-axis direction drive unit 130 and a Z-axis direction drive unit 150 for moving the position of the pressurizing means, and a Y-axis direction drive unit 140 for moving the sample stage 110 are provided, and they are used as moving means to relatively move the pressurizing means to any position on the test sample 10. As shown in FIG. 3, the test apparatus may be such that the pressurizing means is moved by the X-axis direction drive unit 130, the Y-axis direction drive unit 140, and the Z-axis direction drive unit 150 without using the sample stage 110 as a movable stage, and the test sample 10 is placed on the sample stage 110. Each of the drive units 130, 140, and 150 preferably has a stepping motor or a servo (pulse) motor (not shown), a ball screw, and a linear guide, and further includes an encoder for position detection.

[0022] With respect to the test sample 10 disposed on the sample stage 110 of the test apparatus 100, the pressurizing means located above has a pressurizing member 125 capable of pressurizing the test sample 10 to form an indentation.

[0023] The pressurizing member 125 has a rod-like structure and has rigidity, and is preferably formed of a non-ferrous alloy such as beryllium copper or nickel bronze, or a material such as super steel or ceramic. The end of the pressurizing member 125 is brought into contact with the plane of the test sample 10, and depending on the shape of the end, there are differences in the force for causing an indentation in the test sample 10 and the way of cracking. Therefore, the dimensional shape of the pressurizing member 125 is set in consideration of the mechanical properties of the amorphous alloy ribbon, and it is preferable to appropriately consider the interval of the pressurizing portion formed in the test sample 10 and the like.

[0024] FIG. 4 is a schematic view showing an example of a pressing member used in the test apparatus. In the illustrated example, a cylindrical body portion 126 and a conical portion 127 at its end are shown. If the shape of the end of the pressing member 125 is an acute-angled needle shape, it is easy to break through the test sample 10 all at once. Therefore, it is preferable that the shape of the end of the pressing member 125 is conical (circular cone shape, square pyramid shape). The angle (apex angle θ) of the tip of the conical shape is preferably 60° to 130°. A more preferable lower limit is 70°, and a more preferable lower limit is 90°. A more preferable upper limit is 125°, and a more preferable upper limit is 120°. Preferred shapes are a hemispherical shape or a conical shape with an obtuse apex angle, and the diameter dimension of the end is preferably φ1.0 mm or more and φ5.0 mm or less.

[0025] The pressing means includes, for example, a force gauge 120 and a pressing member 125, and is configured by connecting a rod-shaped pressing member 125 to the force gauge 120 via a fixing means such as a collet chuck. The pressing means is fixed to the slider of the Z-axis direction driving unit 150 of the test apparatus 100 by bolt fastening or the like. The Z-axis direction driving unit 150 lowers the pressing means toward the plane of the test sample 10 at a predetermined speed, and presses the tip side of the pressing member 125 against the test sample 10. The tip of the pressing member 125 descends until it reaches a preset position, forms a pressed portion with an indentation on the test sample 10, and then rises to a predetermined position by the Z-axis direction driving unit 150 so as to separate from the test sample 10. Next, the X-axis direction driving unit 130 and the Y-axis direction driving unit 140 move the pressing means to different positions on the plane of the test sample 10, and then repeat the formation of the next pressed portion a predetermined number of times. A series of operations for forming the pressed portion is preferably automatically controlled by a programmable control device. The force (pressing force) applied to the test sample 10 during the formation of the pressed portion can be measured by the force gauge 120 to which the pressing member 125 is attached. The thickness of the test sample 10 is thin, and in the pressed portion where an indentation remains, the pressing surface side of the evaluation sample 10 is recessed and the opposite surface side is protruded. If the tip of the pressing member 125 is hemispherical or conical with an obtuse apex angle, cracks in the pressed portion are likely to occur from near the top of the protrusion to the bottom.

[0026] Further, the pressing means may be configured to include a load sensor (load cell) (not shown) and a pressing member 125. Based on the pressing force information obtained from the electrical signal from the load cell, it is also possible to control the formation of the pressing portion on the test sample 10. As the tip side of the pressing member 125 comes into contact with the plane of the test sample 10 and further descends until it reaches a set position, the force (pressing force) applied to the test sample 10 increases. If a crack occurs in the pressing portion before the pressing member 125 reaches a predetermined descending position, the pressing force decreases. Such a change in the pressing force is detected by the load cell, an electrical signal corresponding to the pressing force applied to the test sample 10 in the formation of the pressing portion is obtained, and by the AD conversion means, the output of the analog signal from the amplifying means for amplifying the electrical signal is converted into a digital signal and detected, it is possible to determine the presence or absence of cracks in the pressing portion. Further, data such as the pressing force distribution in the pressing portion, the distribution of the pressing portion where cracks have occurred, and the number of pressing portions where cracks have occurred can also be easily obtained by the arithmetic processing means.

[0027] Further, based on the information from the load cell, the tip side of the pressing member 125 may be lowered until the force applied to the pressing portion reaches a preset pressing force value. When the occurrence of cracks is detected, the descent of the pressing member 125 may be stopped, it may be raised to a predetermined position, and the operation may proceed to the formation of the next pressing portion.

[0028] FIG. 5 is a diagram showing an example of a state in which a test sample is placed on the sample stage of a test apparatus. In the example shown in FIG. 5, a plate-shaped metal base member 20 is placed on a flat sample stage, and the test sample 10 is placed on top of the magnetic adsorption member 25 and the elastic member 30 stacked in order. Note that the portion indicated by the blacked-out ellipse in the test sample 10 corresponds to the pressing portion of the evaluation sample 10. In order to prevent the base member 20 from moving and the position of the test sample 10 from shifting, it is preferable that through holes are formed in the base member 20 so that it can be fastened and fixed to the sample stage 110 with screws or the like. The fixing may be known means such as clamping or adsorption in addition to fastening. Considering workability, it is preferable to use aluminum for the base member 20, but it may also be made of steel or stainless steel so that it can be easily fixed to the magnetic adsorption member 25.

[0029] The magnetic adsorption member 25 is a magnetic adsorption means for fixing the test sample 10 by magnetic adsorption, and is preferably composed of a magnet sheet. If the base member 20 is non-magnetic, the magnet sheet may be fixed by an adhesion means such as double-sided tape. Although the test sample 10 is in a plate shape with a thickness of at most several tens of μm or less, by using a magnet sheet having a size that covers at least a part of the region where the pressurized portion is formed, and preferably the entire region, the test sample 10 can be magnetically adsorbed and fixed via the elastic member 30 over the entire surface. Further, it is preferable to adjust the adsorption force by the magnetic force of the magnetic adsorption means itself or the distance between the magnetic adsorption means and the test sample 10 so that it is also easy to remove.

[0030] In order to make the test sample 10 into a pressurized portion having a plastic deformation and an indentation, it is preferable to dispose the elastic member 30 as an elastic base between the sample stage 110 and the test sample 10 so as not to hinder the deformation. The elastic member 30 can also absorb and disperse the pressure applied during the formation of the pressurized portion applied to the lower magnet sheet or the like via the test sample 10.

[0031] The elastic member 30 is preferably a sheet of fluororubber or silicone rubber. The size of the elastic member 30 also preferably covers at least a part of the region where the pressurized portion of the test sample 10 is formed, and further preferably has a size that covers the entire region, similar to the magnetic adsorption member 25. From the required functions, the elastic member 30 preferably has a Shore A hardness of 30 or more and 100 or less, more preferably 35 or more and 90 or less, and even more preferably 40 or more and 70 or less. Also, the thickness is preferably 0.5 mm or more, more preferably 0.8 mm or more, and even more preferably 1.0 mm or more. Since it becomes more difficult to obtain the magnetic adsorption force of the test sample 10 by the magnetic adsorption member 25 as the elastic member 30 becomes thicker, the thickness is preferably 3.0 mm or less, more preferably 2.5 mm or less, and even more preferably 2.0 mm or less.

[0032] Next, a method for checking the evaluation sample 10 that has undergone the pressurization process will be described. The state of the pressurized portion (presence or absence of cracks) can be obtained by observing the indentation, and it may be visually evaluated using a magnifying glass or an optical microscope, or the indentation may be observed using imaging means such as a CCD camera or a CMOS camera, and the obtained image data may be processed by image processing for evaluation.

[0033] FIG. 6 is a diagram for explaining an example of a crack checking method. In the illustrated example, a plate such as a transparent resin or inorganic glass is used as the stage 160, and a light source device in which a light source 170 such as a fluorescent lamp, a halogen lamp, or a light-emitting diode is arranged below it is used. The evaluation sample 10 is overlapped on the stage 160 of the light source device so that the concave side of the pressurized portion faces the light source 170 side, and the light from the light source 170 is transmitted through the crack 11 formed in the pressurized portion of the evaluation sample 10. By placing the light source on the concave side of the pressurized portion, the transmitted light of the pressurized portion can be clearly confirmed by visual observation from the protruding side. Further, by observing with a microscope or a magnifying glass at a low magnification (typically about 10 to 50 times), the portion of the crack 11 that shines in a streak shape with a width becomes clear. Defects such as scratches and holes originally present in the amorphous alloy ribbon can be distinguished from differences in local light transmission (brightness), the location of occurrence, and the form of cracks formed by the formation of the pressurized portion, and even fine cracks can be determined.

[0034] It is also preferable to observe the pressurized portion in a state where it is enlarged and projected onto a monitor using a CCD camera or a CMOS camera. Further, image analysis may be performed to evaluate the state of the pressurized portion. It has been found that the degree of cracking (severity of damage) and the degree of embrittlement occurring in the pressurized portion of the evaluation sample 10 to be observed are correlated. For example, the photographed image is binarized by arithmetic processing means, and the presence or absence of a streak-like pattern portion corresponding to the cracked portion, its area, etc. are quantified, and it is also preferable to judge the presence or absence and degree of cracks based on a threshold value. This enables easy determination and suppresses variations in determination due to individual differences. By performing such determination processing for each pressurized portion and processing the information on the presence or absence of cracks obtained, data such as the distribution of the pressurized portions where cracks have occurred in the evaluation sample 10 and the number of pressurized portions where cracks have occurred can be obtained.

[0035] The cracking may be determined by the discontinuity of the undulation of the surface shape of the pressing portion. The measurement of the undulation of the surface of the pressing portion of the evaluation sample 10 can be performed non - contact using a laser microscope or the like.

[0036] From the information obtained from the evaluation sample 10, it is possible to evaluate in detail the degree of brittleness, the embrittled portions and their distribution, etc. of the amorphous alloy ribbon, which were difficult in the conventional tear test. For example, the embrittlement can be evaluated by taking the number of pressing portions per unit area where cracks occur as the embrittlement degree, or taking the ratio of the number of pressing portions where cracks occur to the total number of pressing portions as the embrittlement degree. Also, by evaluating the embrittlement of the mother roll, the ranking of the mother roll can be subdivided, and it can be used as a more accurate index for cuttability when cutting the mother roll. Also, since the distribution of embrittlement in the mother roll can be evaluated, the mother roll can be further processed secondarily and the ribbons obtained by dividing it into a plurality with a predetermined width dimension by a cutting means can also be ranked. Of course, it is also possible to evaluate the embrittlement of amorphous alloy ribbons other than the mother roll in the same way.

Example

[0037] (Example 1) The embrittlement of an Fe - Si - B - based amorphous alloy ribbon (2605HB1M manufactured by Hitachi Metals, Ltd.) was evaluated. This amorphous alloy ribbon had a width of 142 mm, a thickness of 26 μm, and a weight of about 700 kg. The brittleness code of JIS C2534(2017) was 1 (the number of brittle spots in one test piece; 0). Further, it was processed into a mother roll so that the width became 70 mm. Samples were cut out from the mother roll with a length of 1 m, and further 5 test samples with a width of 70 mm and a length of 70 mm and discontinuity were cut out from there.

[0038] As a test device, a three-axis robot was used to form a pressurized portion with 313 indentations on a test sample to obtain an evaluation sample. As the three-axis robot, a tabletop robot TT series manufactured by AIAI Co., Ltd. was used. A push-pull gauge manufactured by AIKO Engineering Co., Ltd. with a pressurizing member attached was bolted and fixed to the slider of the Z-axis drive unit thereof. The pressurizing member was provided with a cylindrical body portion as shown in Fig. 4 and a conical body portion with an obtuse apex angle at its end. The pressurizing member used was made of beryllium copper, with the body portion having a diameter of φ1.4 mm, the conical body portion having a bottom diameter of φ4 mm, and the apex angle θ being 120°.

[0039] An aluminum plate with a thickness of 15 mm was bolted and fixed as a base member to the slider (sample stage) of the Y-axis drive unit of the three-axis robot, and a commercially available magnet sheet with a thickness of 0.7 mm was fixed on both sides with a double-sided tape as a magnetic adsorption member. A commercially available silicon rubber sheet was placed on the magnet sheet as an elastic member. The silicon rubber had a thickness of 0.8 mm and a Shore A hardness of 50. Markings for positioning were formed on the silicon rubber sheet for placing the test sample, and the test sample was placed on top based on this reference to form the pressurized portion. All five test samples were placed on the sample stage with the casting directions aligned.

[0040] The plan view of the test sample is shown in Fig. 7. The multiple locations indicated by black circles in the figure show the locations where the pressurized parts are formed. Note that the black circles can be read as the pressurized parts for explaining the evaluation sample 10 using Fig. 7. The operation of the three-axis robot is pre-programmed, and the range S for pressurizing (the area indicated by the thin lines connecting the centers of the pressurized parts at the four corners in the figure) is an area with a width of 53.5 mm and a length of 53.5 mm, about 8.3 mm inside from each edge of the test sample. The tips of the pressurizing members are formed in a staggered pattern so that the interval between adjacent pressurized parts (the center-to-center distance of the pressurized parts) is 4.46 mm, and the operations of the X-axis driving part and the Y-axis driving part are controlled so that 313 pressurized parts are formed per test sample. Also, the pressurizing member is lowered to a preset position at 300 mm / s, and the Z-axis driving part is controlled to rise from the lowered position to a predetermined position. The position in the Z-axis direction is set using a sample for condition setting obtained from the same raw material as the test sample so that the pressurized parts with cracks and the pressurized parts without cracks are mixed. The pressurizing force measured by a force gauge at the pressurized parts without cracks was about 14 N. Pressurized parts were formed under the same conditions for all five test samples to obtain evaluation samples.

[0041] The pressurized parts of the evaluation sample were observed from the protrusion side in a region of 520 μm × 700 μm with a magnification of 20 times using a laser microscope (Keyence VK-X1000) to confirm the crack state. Enlarged photos of the pressurized parts taken by the laser microscope are shown in Figs. 8 and 9. Fig. 8 is a photo of the pressurized part without cracks, and Fig. 9 is a photo of the pressurized part with cracks, each shown as a typical form. Also, in the same observation field as Figs. 8 and 9, the surface undulations were processed by image processing and converted to a visually confirmable color tone for confirmation. Figs. 10 and 11 are photos of the surface undulations as the difference in brightness. For the pressurized part without cracks shown in Fig. 10, the surface undulations were observed in a halo shape as continuous brightness. On the other hand, for the pressurized part with cracks shown in Fig. 11, cracks spread from the center in all directions, and in the regions partitioned by the cracks, the surface undulations were observed as different brightness.

[0042] Next, a light source device using a fluorescent lamp as a light source was used, and the evaluation sample was arranged such that the concave side of the pressurized portion faced the light source side. The presence or absence of cracks was visually confirmed by the transmitted light passing through the cracks in 313 pressurized portions. The number N of pressurized portions where cracks occurred in each of the five evaluation samples was measured and recorded. The number of pressurized portions where cracks occurred per unit area was defined as the embrittlement degree (N / S) (pieces / mm 2 ), and the ratio of the number of pressurized portions where cracks occurred to the total number N0 of pressurized portions was defined as the embrittlement degree (N / N0) (%). These are shown in Table 1. The embrittlement degree (N / S) was calculated by dividing the number N of pressurized portions where cracks occurred by the area (width 53.5 mm × length 53.5 mm) of the range S where the pressurized portions were applied.

[0043]

Table 1

[0044] The number of pressurized portions where cracks occurred differed among the evaluation samples, and the embrittlement degree varied in the casting direction of the amorphous alloy ribbon for each sheet.

[0045] (Example 2) Similar to Example 1, the embrittlement of an Fe—Si—B-based amorphous alloy ribbon (2605HB1M manufactured by Hitachi Metals, Ltd.) was evaluated. Four amorphous alloy ribbons with different manufacturing lots from the amorphous alloy ribbon of Example 1 were prepared. These amorphous alloy ribbons had a width of 142 mm, a thickness of 26 μm, and each had a weight of approximately 700 kg, and the brittleness code of JIS C2534 (2017) was 1 (the number of brittle spots in one test piece; 0). This was used as a raw material and cut into a length of 1.03 m to obtain test samples with a width of 142 mm and a length of 1.03 m. (Evaluation samples 6 to 9) In addition, the embrittlement of an Fe—Si—B-based amorphous alloy ribbon (2605HB1M manufactured by Hitachi Metals, Ltd.) produced by a process different from the amorphous alloy ribbons from which evaluation samples 6 to 9 were obtained was evaluated. The width, thickness, etc. were the same as above, and evaluation samples (evaluation sample 10) were prepared from the raw material in the same manner as above.

[0046] Using a three-axis robot for the fabricated test sample, in the same manner as in Example 1, a region S to be pressurized with a width of 53.5 mm and a length of 53.5 mm was set, and an evaluation sample was fabricated such that 313 pressurized portions were formed per region S to be pressurized.

[0047] As shown in Fig. 12, the region where the pressurized portions are formed (pressurizing range S) is approximately 8.3 mm inside from each edge of the test sample. At the right and left sides in the width direction of the test sample, five pressurized portions were formed in the casting direction of the raw material sheet respectively, and at the central portion in the width direction of the test sample, five pressurized portions were formed in the casting direction of the raw material sheet respectively. The interval between the pressurizing ranges S arranged in the casting direction is set to approximately 150 mm. The test sample is about 1 m long and could not be entirely accommodated on the sample stage in the length direction. Therefore, the test sample was appropriately repositioned on the sample stage and the pressurized portions were formed while changing the position, and it was used as the evaluation sample. Since other conditions are the same as in Example 1, the description is omitted.

[0048] In the same manner as in Example 1, a light source device using a fluorescent lamp as the light source was used, and the presence or absence of cracks was visually confirmed by the transmitted light passing through the cracks. For each of the right side, left side, and central portion of the evaluation sample, the number M (total of five locations) of the pressurized portions where cracks occurred was measured and recorded. The number M of the pressurized portions where cracks occurred in each of the right side, left side, and central portion of the evaluation sample, and the number N (total of three M's) of the pressurized portions where cracks occurred in one evaluation sample were both used to evaluate the degree of embrittlement. The results are shown in Table 2. The degree of embrittlement was evaluated in the following two ways as the number of pressurized portions where cracks occurred per unit area. First, as the degree of embrittlement (M / 5S) of each of the left side, central portion, and right side, the number M of the pressurized portions where cracks occurred in each of the left side, central portion, and right side was divided by the area of the total of the respective pressurizing ranges S (5 × S). Second, the number N of the pressurized portions where cracks occurred in the entire evaluation sample was divided by the area of the total of the pressurizing ranges S (15 × S). Also, the degree of embrittlement (N / N0) was calculated as the ratio of the number N of the pressurized portions where cracks occurred to the total number N0 of the pressurized portions as N / N0 (%). The thickness of each raw material sheet from which the evaluation sample was taken is also shown in Table 2.

[0049]

Table 2

[0050] The number N of the pressurized parts where cracks occurred differed among the evaluation samples and was 21 to 170. Also, there were cases where the number of the pressurized parts where cracks occurred differed by 10 or more among the left side part, the central part, and the right side part of the evaluation samples.

[0051] As shown in Example 1 and Example 2, with the embrittlement evaluation method of the present disclosure and the test apparatus used therefor, the embrittled state can be evaluated in more detail than before. For example, it can be evaluated numerically as the degree of embrittlement. This is a new method, and by applying the embrittlement evaluation method of the present disclosure, for example, the original material and the amorphous alloy ribbon obtained by dividing it can be more finely classified according to the degree of embrittlement. Further, the test apparatus for embrittlement evaluation of the present disclosure can be configured by combining general mechanical devices, and thus can be provided at low cost.

Explanation of Signs

[0052] 10 Test sample, evaluation sample 11 Crack 20 Base member 25 Magnetic adsorption member 30 Elastic member 100 Test apparatus 110 Sample stage 120 Force gauge 125 Pressurizing member 126 Cylindrical body part 127 Conical part I30 X-axis direction drive unit 140 Y-axis direction drive unit 150 Z-axis direction drive unit 160 Stage 170 Light source

Claims

1. Pressing members are pressed against one side of an amorphous alloy ribbon disposed on an elastic member from a plurality of positions to form pressure-applied portions with indentations scattered, evaluating embrittlement based on the number or distribution of cracks generated in the plurality of pressure-applied portions, a method for evaluating embrittlement of an amorphous alloy ribbon.

2. The method for evaluating embrittlement of an amorphous alloy ribbon according to Claim 1, characterized in that the amorphous alloy ribbon is magnetically adsorbed and fixed.

3. Characterized in that cracks are discriminated by the discontinuity of the undulation of the surface shape of the pressure-applied portion, the method for evaluating embrittlement of an amorphous alloy ribbon according to Claim 1 or 2.

4. Characterized in that cracks are discriminated from the light transmission state of the pressure-applied portion, the method for evaluating embrittlement of an amorphous alloy ribbon according to Claim 1 or 2.

5. Characterized in that cracks are discriminated by the change in the decrease of the pressing force of the pressing member, the method for evaluating embrittlement of an amorphous alloy ribbon according to Claim 1 or 2.

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