Method for manufacturing iron-chromium-cobalt alloy magnet and iron-chromium-cobalt alloy magnet

Abstract

To provide a method for manufacturing an iron-chromium-cobalt alloy magnet which is superior in shape flexibility and exhibits desired magnetic characteristics, and to provide the iron-chromium-cobalt alloy magnet.SOLUTION: A method for manufacturing an iron-chromium-cobalt alloy magnet includes: an additive manufacturing step of producing an additive product through a shaping step of irradiating an alloy powder with a heat source to melt and solidify the alloy powder and a lamination shaping step of repeating the shaping step; and a heat treatment step of performing heat treatment on the additive product. The alloy powder comprises, by mass%, 26 to 45% of Cr, 3 to 35% of Co, 1.0% or less of Ni, and 1.0% or less of Ti, with the balance being Fe and impurities. In the heat treatment step, a coercive force Hc of the additive product is 50 kA / m or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing an iron-chromium-cobalt alloy magnet and to an iron-chromium-cobalt alloy magnet. [Background technology]

[0002] Conventionally, an iron-chromium-cobalt alloy magnet manufactured by additive manufacturing is disclosed in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] WO2022 / 172995 issue Summary of the Invention [Problem to be solved by the invention]

[0004] Due to their flexibility in shape, metal magnets manufactured using additive manufacturing methods are expected to be used in complex shapes as devices become more compact and in a variety of environments. As a result, in addition to this freedom in shape, they are also required to exhibit magnetic properties that are suitable for the environment in which they are used.

[0005] Therefore, an object of the present invention is to provide a method for producing an iron-chromium-cobalt alloy magnet that has excellent freedom in shape and exhibits desired magnetic properties, and to provide an iron-chromium-cobalt alloy magnet. [Means for solving the problem]

[0006] The present invention provides an additive manufacturing process that produces an additively manufactured product through a shaping step of irradiating a heat source to an alloy powder to melt and solidify it, and an additive manufacturing step of repeating the shaping step, and a heat treatment step that performs a heat treatment on the additively manufactured product, wherein the alloy powder contains, by mass%, 26 to 45% Cr, 3 to 35% Co, 1.0% or less Ni, and the balance Fe and impurities, and the heat treatment step is carried out to reduce the coercive force H cThis is a method for producing an iron-chromium-cobalt alloy magnet, characterized in that the magnetic field is set to 50 kA / m or more.

[0007] Furthermore, in the manufacturing method of the iron-chromium-cobalt alloy magnet, the content is, by mass, 30 to 45% Cr and 0.1 to 0.8% Ni, and the heat treatment step preferably improves the hardness of the additive product to more than 125% after the heat treatment step, assuming that the hardness before the heat treatment step is 100%.

[0008] The present invention also provides an additive product containing, by mass%, Cr: 26 to 45%, Co: 3 to 35%, Ni: 1.0% or less, and the balance being Fe and impurities, and having a coercive force H c The iron-chromium-cobalt alloy magnet is characterized in that its magnetic flux density is 50 kA / m or more.

[0009] In addition, in the iron-chromium-cobalt alloy magnet, the residual magnetic flux density B r is preferably greater than 1.10T. [Effects of the Invention]

[0010] The present invention provides a method for producing an iron-chromium-cobalt alloy magnet that has excellent freedom in shape and exhibits desired magnetic properties, and an iron-chromium-cobalt alloy magnet. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram of the phase separation structure of an iron-chromium-cobalt alloy magnet. [Figure 2] FIG. 2 is a diagram showing the hardness of each of the iron-chromium-cobalt alloy magnets produced before and after heat treatment. [Figure 3] FIG. 10 is a diagram showing the temperature dependence of each magnetic property of the additive product F1. [Figure 4] STEM image of an additively manufactured alloy magnet produced using additive manufacturing methods. [Figure 5] These are STEM images and EDS area analysis images of an additively manufactured alloy magnet after heat treatment. [Figure 6] These are STEM images and EDS area analysis images of rolled magnet W1, which was produced using the rolling method. [Figure 7] These are STEM images and EDS area analysis images of rolled magnet W2, which was produced using the rolling method. DETAILED DESCRIPTION OF THE INVENTION

[0012] Below, we will explain a method for manufacturing an iron-chromium-cobalt alloy magnet and embodiments of the iron-chromium-cobalt alloy magnet. In the following explanation, % indicates mass %. Furthermore, in this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. Furthermore, the upper and lower limits can be combined in any way.

[0013] The present invention provides an additive manufacturing process that produces an additively manufactured product through a shaping step of irradiating a heat source to an alloy powder to melt and solidify it, and an additive manufacturing step of repeating the shaping step, and a heat treatment step that performs a heat treatment on the additively manufactured product, wherein the alloy powder contains, by mass%, 26 to 45% Cr, 3 to 35% Co, 1.0% or less Ni, and the balance Fe and impurities, and the heat treatment step is carried out to reduce the coercive force H c One of the features of this method is that the current is 50 kA / m or more.

[0014] The present invention provides an iron-chromium-cobalt alloy magnet that offers excellent shape flexibility and can achieve desired magnetic properties, as well as a manufacturing method for the iron-chromium-cobalt alloy magnet. As a result, by adopting additive manufacturing as a manufacturing method for the alloy magnet, it is possible to reduce the processing allowance in the final finishing process by achieving a near-net shape that is close to the desired part shape, which is expected to improve the yield of magnet products.

[0015] (Method for manufacturing iron-chromium-cobalt alloy magnets) The following describes embodiments of the present invention. Regarding the manufacturing method of an iron-chromium-cobalt alloy magnet, a method using powder bed fusion (PBF) is exemplified as a representative additive manufacturing method. However, directed energy deposition (DED) and other methods may also be used, and the manufacturing method of the alloy magnet of the present invention is not limited to the embodiments described below.

[0016] [Raw material powder] The iron-chromium-cobalt alloy magnet has a composition containing 26-45% Cr, 3-35% Co, and the balance being Fe and impurities. Alternatively, the composition may be 26-45% Cr, 3-35% Co, 1.0% or less Ni, 1.0% or less Ti, and the balance being Fe and impurities.

[0017] By setting the Cr content in the range of 26 to 45%, the magnetic properties after heat treatment, such as the coercive force H c The electric conductivity can be 50 kA / m or more. Furthermore, the formation of a phase-separated structure of α1 ferromagnetic phase and α2 paramagnetic phase during heat treatment is promoted, which is expected to have the effect of improving hardness after heat treatment. Cr is preferably 30 to 45%, more preferably 32 to 45%. Ni is preferably more than 0%, and Ti is preferably more than 0%.

[0018] The addition of a small amount of Ni has the effect of promoting the formation of a phase-separated structure of an α1 ferromagnetic phase and an α2 paramagnetic phase during heat treatment, which will be described later, thereby further enhancing the hardness improvement effect. Therefore, Ni is preferably contained in the range of 0.1 to 1.0%, more preferably in the range of 0.1 to 0.8%, and even more preferably in the range of 0.3 to 0.6%.

[0019] In addition to the elements Fe, Cr, Co, Ni, and Ti, metalloid elements such as Si may be contained in an amount of 1.0% or less. The total amount of impurities is preferably 1.0% or less.

[0020] The raw materials, which are prepared by weighing and mixing the required amounts of each elemental feedstock to obtain an additive product of the desired composition, are loaded into a crucible and high-frequency melted. The molten alloy is then dropped from a nozzle below the crucible and atomized with high-pressure argon to produce a gas-atomized powder. This gas-atomized powder is then classified to obtain an iron-chromium-cobalt alloy powder, which serves as the alloy powder (raw material powder). The particle size distribution range is preferably between 10 and 150 μm, and more preferably between 10 and 80 μm.

[0021] <Additive manufacturing process> The additive manufacturing process is a process using an additive manufacturing method, and includes a manufacturing step in which alloy powder is irradiated with a heat source to melt and solidify it, and a layered manufacturing step in which the manufacturing step is repeated to produce an additive product. The heat source can be a high-energy density heat source such as a laser or an electron beam.

[0022] The thickness of one layer of the raw material powder in the shaping step is not particularly limited, but is preferably 20 to 80 μm. The laser beam diameter at the position of the irradiated raw material powder is preferably 0.05 to 0.5 mm, more preferably 0.08 to 0.1 mm. The laser output is preferably 200 to 400 W. The laser scanning speed is preferably 500 to 2500 mm / s. The laser scanning pitch is preferably 0.05 to 0.15 mm.

[0023] The density of the energy input by laser irradiation to melt and solidify the raw material powder (energy density of the heat source: J / mm 3 ) is set to suppress the magnetic properties, especially the decrease in squareness ratio and the defect rate, and to melt the raw material powder to the desired extent so as to maintain the shape of the additive product. The energy density E of the heat source is 35 J / mm 3 More than 35 to 130 J / mm is preferable. 3 The range of 50 to 110 J / mm is more preferable. 3 The range of 50 to 95 J / mm is more preferable. 3 The range is even more preferred.

[0024] Energy density E (J / mm 3 ) can be calculated from E=P / (vad) using the laser power P (W), laser scanning speed v (mm / s), laser scanning pitch a (mm), and thickness d (mm) of the raw material powder layer.

[0025] [Additive Manufacturing] For example, when using a powder bed type three-dimensional additive manufacturing device, the additive product is produced by melting and solidifying raw material powder supplied onto a base plate using laser irradiation, and then detaching the additive product from the base plate. The resulting additive product becomes the iron-chromium-cobalt alloy magnet of this embodiment. The additive manufacturing conditions are determined appropriately taking into consideration the particle size and composition of the raw material powder, the size, shape, characteristics, and production efficiency of the shaped object, etc.

[0026] <Heat treatment process> The heat treatment process is a process in which the additive product produced in the additive manufacturing process is subjected to heat treatment such as solution treatment, heat treatment in a magnetic field, and aging treatment. If the hardness of the additive product before the heat treatment is 100%, the hardness of the additive product after the heat treatment is preferably more than 125%, more preferably 200% or more.

[0027] When the hardness of the additive product before heat treatment is 100%, the percentage increase in hardness of the additive product after heat treatment is sometimes referred to as the improvement rate. In other words, an improvement rate of 100% means that the hardness of the additive product before and after heat treatment remains unchanged, and an improvement rate of 200% means that the hardness of the additive product before and after heat treatment has doubled.

[0028] The heat treatment process may include, for example, a solution treatment to convert the structure to the α phase, a heat treatment in a magnetic field to develop magnetic properties, and an aging treatment to separate the structure into an α1 ferromagnetic phase and an α2 paramagnetic phase. Regarding the heat treatment conditions, the temperature range for the solution treatment is preferably 1000°C to 1300°C, more preferably 1150°C to 1250°C, and the holding time is preferably 0.5 to 1.5 hours. The heat treatment in a magnetic field is preferably in a magnetic field of 150 to 300 kA / m, and is preferably held at 600 to 700°C for 1 to 5 hours. The aging treatment is preferably held at 600 to 700°C for 0.5 to 3 hours, followed by cooling at a rate of about 2 to 8°C / min.

[0029] An iron-chromium-cobalt alloy magnet produced by the above-described manufacturing method has excellent freedom in shape and can achieve desired magnetic properties.

[0030] (iron-chromium-cobalt alloy magnet) One embodiment of the iron-chromium-cobalt alloy magnet according to the present invention is an additive product containing 26 to 45% Cr, 3 to 35% Co, 1.0% or less Ni, 1.0% or less Ti, and the balance Fe and impurities, and has a coercive force H c As mentioned above, by setting the Cr content in the range of 26 to 45%, the magnetic properties, for example, the coercive force H c It is possible to improve the

[0031] The Cr content is preferably 30 to 45%, more preferably 32 to 45%. Ni content is also preferably more than 0%. Alternatively, the composition may be Cr: 26 to 45%, Co: 3 to 35%, Ni: 1.0% or less, Ti: 1.0% or less, with the balance being Fe and impurities.

[0032] The addition of a small amount of Ni has the effect of promoting the formation of a phase-separated structure of α1 ferromagnetic phase and α2 paramagnetic phase during heat treatment, which will be described later, thereby further enhancing the hardness improvement effect. Therefore, Ni is preferably contained in the range of 0.1 to 1.0%, more preferably in the range of 0.1 to 0.8%, and even more preferably in the range of 0.3 to 0.6%. In addition to Fe, Cr, Co, Ni, and Ti, semimetallic elements such as Si may also be contained.

[0033] <Hardness> The harder the iron-chromium-cobalt alloy magnet, the more it can be prevented from being scratched or deformed. Therefore, the Vickers hardness of the iron-chromium-cobalt alloy magnet is preferably greater than 250 HV, more preferably 400 HV or greater. The Vickers hardness can be measured using a Vickers hardness tester, for example, at room temperature with a load of 0.1 kgf and a holding time of 10 seconds. The measurement can be performed three times and the average value recorded.

[0034] <Magnetic properties> A permanent magnet has a residual magnetic flux density B r In order to make it less susceptible to demagnetizing fields, the magnetic properties of the material must be large, and the coercive force H c Therefore, the magnetic properties are determined by the coercive force H c is 50kA / m or more.

[0035] Also, at room temperature, for example, at 22° C., the residual magnetic flux density B r is 1.10~1.50T, coercive force H c is 55~67kA / m, maximum energy product BH max is 30-50kJ / m 3 and more preferably, the residual magnetic flux density B r is 1.11T or more, coercive force H c is 58~62kA / m, maximum energy product BH max is 35kJ / m 3 The residual magnetic flux density B at 20°C rIt is preferable that the temperature dependency of is in the range of 0.03 to 0.05% / K.

[0036] Also, (BH) max / (B r ×H cB ) is preferably 0.30 to 0.55, and more preferably 0.40 to 0.55.

[0037] In general, H k / H cJ H is a parameter measured to find k is in the second quadrant of the J (magnetization strength)-H (magnetic field strength) curve, where J is 0.9 × J r (J r is the remanent magnetization, J r =B r The H axis reading at the position where the value of this H k H of the demagnetization curve cJ The value divided by (H k / H cJ ) is defined as the squareness ratio.

[0038] However, for iron-chromium-cobalt alloy magnets, H k is lower than Nd-Fe-B magnets and ferrite magnets, and H cJ and H cB Since the values ​​are almost the same, there is no concept of a JH curve, and the squareness is expressed as (BH) max / (B r ×H cB ) is more suitable. cB Simply H c This will be explained as follows.

[0039] The iron-chromium-cobalt alloy magnet of this embodiment is expected to be applied to sensors. For example, the magnetic properties of the coercive force H c Because of its high magnetism, it is expected to be applicable to sensors that require the ability to avoid demagnetization due to external magnetic fields.

[0040] In additively manufactured products, many dislocations are formed in the alloy structure when they are not heat treated. The structure after heat treatment (solution treatment, magnetic field annealing, and aging treatment) is explained using Figure 1.

[0041] As shown in FIG. 1, the additive product after heat treatment has a phase-separated structure including an α1 ferromagnetic phase 13 and an α2 paramagnetic phase (Cr-rich phase) 12 containing a large amount of Cr, and it is preferable that the α1 ferromagnetic phase 13 and the α2 paramagnetic phase 12 are refined. It is also preferable that the α2 paramagnetic phase 12 is refined. By subjecting the additive product to heat treatment, the α2 paramagnetic phase 12 is refined, and the hardness of the additive product can be improved. Hereinafter, the α1 ferromagnetic phase may be simply referred to as α1, and the paramagnetic phase may be simply referred to as α2.

[0042] The α1 ferromagnetic phase 13 is evaluated by a composition mapping image obtained by energy-dispersive X-ray spectroscopy (EDS) using a scanning transmission electron microscope (STEM).

[0043] For example, in a compositional mapping image at a magnification of 1,000,000 times, a region where the Cr composition is lower than the average value is defined as the α1 ferromagnetic phase 13. The size (diameter) of the α1 ferromagnetic phase 13 is defined as the average value measured at five or more locations in the compositional mapping image. The average diameter of the α1 ferromagnetic phase is preferably less than 100 nanometers, more preferably less than 50 nanometers, and even more preferably less than 30 nanometers.

[0044] The α2 paramagnetic phase 12 is formed around the α1 ferromagnetic phase 13, and the thickness 15 of the α2 paramagnetic phase 12, in other words, the width of the α2 paramagnetic phase 12 sandwiched between adjacent α1 ferromagnetic phases 13, can be preferably less than 30 nanometers, more preferably less than 20 nanometers, and even more preferably less than 10 nanometers.

[0045] In the case of iron-chromium-cobalt alloy magnets produced by additive manufacturing, rapid solidification after melting introduces many dislocations into the structure, promoting the formation of a phase separation structure. This results in smaller average diameters of the α1 ferromagnetic phase 13 and thicknesses 15 of the α2 paramagnetic phase 12 compared to rolled magnets and cast magnets, thereby improving the hardness of the alloy magnet. [Example]

[0046] Example 1 Iron-chromium-cobalt alloy magnet F was produced and evaluated using additive manufacturing. The raw materials, consisting of a mixture of the specified amounts of each elemental feed material to produce additive product F, were loaded into a crucible and melted by high-frequency induction in a vacuum. The molten alloy was then dropped from a nozzle below the crucible and sprayed with high-pressure argon gas to produce gas-atomized powder. This gas-atomized powder was then classified to obtain iron-chromium-cobalt alloy powder with a particle size distribution range of 10 to 60 μm.

[0047] As shown in Table 1, additive product F has a composition of Co: 18%, Cr: 32%, Ni: 0.6% and the balance Fe, which is designated F1, and a composition of Co: 10%, Cr: 25%, Ti: 0.6% and the balance Fe, which is designated F2.

[0048] <Additive manufacturing process> Additive manufacturing products F1 and F2 were produced through a molding step in which a laser was irradiated as a heat source onto the prepared raw material powder to melt and solidify the raw material powder, and an additive manufacturing step in which the melted and solidified powder was layered by repeating the molding step. Specifically, using a PBF (powder bed) type 3D additive manufacturing device (EOS EOS-M290), the raw material powder supplied onto an S45C base plate was melted and solidified by laser irradiation to produce additive manufacturing products F1 and F2 with a width of 10 mm, length of 10 mm, and layer height of 10 mm. The additive manufacturing conditions were as follows:

[0049] · Thickness of raw powder layer d: 40 μm Laser beam diameter: approx. 0.1 mm Laser output power: 275W Laser scanning speed v: 875mm / s Scanning pitch a: 0.11mm Energy density E: 71.4J / mm 3

[0050] <Heat treatment process> The prepared additive products F1 and F2 were subjected to heat treatment. The heat treatment consisted of a solution treatment at 1250°C for 1.3 hours, followed by 2.5 hours at 620°C in a magnetic field of 260 kA / m, and then 1.2 hours at 600°C for aging treatment. After that, they were cooled at a rate of about 5 to 10°C / min.

[0051] (Rolled magnets W1 and W2) Rolled magnet W was prepared as an iron-chromium-cobalt alloy magnet produced by the rolling method. As shown in Table 1, W1 had a composition of 18% Co, 32% Cr, 0.6% Ni, and the remainder Fe, while W2 had a composition of 10% Co, 26% Cr, 0.5% Ti, and the remainder Fe. The heat treatments (solution treatment, magnetic field heat treatment, and aging treatment) were the same as those for additive product F1.

[0052] (Cast magnet C1) Cast magnet C was prepared as an iron-chromium-cobalt alloy magnet produced by the casting method. As shown in Table 1, the composition was Co: 10%, Cr: 25%, Ti: 1.0%, and the balance was Fe. The heat treatment (solution treatment, magnetic field heat treatment, aging treatment) was the same as that for additive product F1.

[0053] [Table 1]

[0054] Next, the hardness of the prepared F1, F2, W1, W2, and C1 was measured before and after the heat treatment, and the percentage improvement in hardness (percent change) before and after the heat treatment was evaluated. The evaluation results are shown in Table 2 and Figure 2. The hardness was measured using a Vickers hardness tester (microhardness tester FM-110, manufactured by Future Tech Co., Ltd.). The measurement conditions were a load of 0.1 kgf and a holding time of 10 seconds.

[0055] As shown in Table 2 and Figure 2, the hardness of F1 was 240 HV before heat treatment, but increased to 483 HV after heat treatment, representing an improvement of 201%.Furthermore, the hardness of F2 was 234 HV before heat treatment, but increased to 385 HV after heat treatment, representing an improvement of 165%.

[0056] For the rolled magnets W1 and W2, the hardness of W1 was 238 HV before heat treatment, but increased to 494 HV after, a 208% improvement. For W2, the hardness was 253 HV before heat treatment and 316 HV after, a 125% improvement. For the cast magnet C1, the hardness was 294 HV before heat treatment and 367 HV after, a 125% improvement.

[0057] From this, it was confirmed that additive product F1 and additive product F2, which were produced using additive manufacturing methods, had a hardness improvement rate of 165% or more, and in particular, additive product F1, which contained 26% or more Cr and 1.0% or less Ni, had a hardness improvement rate of 200% or more.

[0058] [Table 2]

[0059] [Magnetic properties] The magnetic properties of F1 were evaluated using a BH tracer, and the magnetic properties for each temperature are shown in Table 3 and Figure 3. The magnetic properties of F1 were determined by obtaining a BH curve. Regarding the magnetic properties for each temperature shown in Table 3 and Figure 3, for example, the residual magnetic flux density B r is 1.124T, coercive force H c is 60.05kA / m, maximum energy product (BH) max is 37.1kJ / m 3 In addition, the residual magnetic flux density B r The temperature dependence of was 0.04% / K at 20°C.

[0060] For reference, Table 4 shows a comparison of the representative values ​​of the magnetic properties of W1 and W2 after heat treatment (measurement temperature: 25°C) with the magnetic properties of F1 (measurement temperature: 22°C).

[0061] The magnetic properties of F1, which was produced using additive manufacturing, were superior to those of the rolled magnets W1 and W2. Compared to W1, it had a high coercive force, which made it highly resistant to reverse magnetic fields, while compared to W2, it had a similar high coercive force and excellent properties in residual magnetic flux density and maximum energy product, demonstrating overall good properties. F1 had a coercive force H c is 55kA / m or more, and the residual magnetic flux density B r It was confirmed that the magnet was an iron-chromium-cobalt alloy with a magnetic field of 1.10T or more.

[0062] [Table 3]

[0063] [Table 4]

[0064] The microstructure of the additive product F1 was observed before and after the heat treatment, and W1 and W2 were subjected to structural observation and elemental analysis. The microstructure was observed using a scanning transmission electron microscope (STEM, JEOL, model: JEM-F200) with an accelerating voltage of 200 kV, an electron diffraction camera length of 500 mm, a STEM probe size of 7, a camera length of 300 mm, quantitative analysis time of 30 Lsec, and an elemental map of 256 × 256 pixels at 0.01 msec / pixel.

[0065] The test specimens used for the analysis were thin sections obtained by a focused ion beam (FIB) microsampling method from a sample prepared by cutting a portion of the additive product into small pieces, embedding them in resin, and polishing the cut surface of the embedded additive product to a mirror finish.

[0066] The elemental analysis was carried out using energy-dispersive X-ray spectroscopy (EDS) attached to the above-mentioned STEM device.

[0067] Figure 4 shows a STEM image of additive product F1 before heat treatment. Figure 4(a) shows the STEM image, (b) and (c) show enlarged STEM images, and Table 5 shows the elemental analysis results for positions A to E shown in Figure 4(a) to (c). Before heat treatment, F1 had many dislocations in its structure.

[0068] [Table 5]

[0069] Next, for F1 after heat treatment, Figure 5(a) shows a STEM image, (b) shows the Fe distribution, (c) shows the Cr distribution, and (d) shows an enlarged EDS area analysis image of (c). Table 6 shows the elemental analysis results for positions F to I shown in Figures 5(b) to (d). Note that the position of F in Figure 5(a) corresponds to carbide 11, the position of G corresponds to the phase-separated structure, the position of H corresponds to α2, and the position of I corresponds to α1.

[0070] As shown in Figures 5(b) to (d) and Table 6, the phase-separated structure was confirmed in the microstructure after the heat treatment, and it was refined. Furthermore, refinement of the paramagnetic phase α2 (Cr-rich phase) was also confirmed. The average diameter of α1 was less than 30 nanometers, and the thickness of α2 formed around the phase-separated α1 was less than 30 nanometers. Carbide 11 precipitated at the grain boundaries, and M 23 It is presumed to be a C6 type carbide.

[0071] [Table 6]

[0072] Next, similar to F1, W1 was also subjected to structural observation and elemental analysis. Figure 6(a) shows a STEM image of W1, (b) shows the distribution of Fe, (c) shows the distribution of Cr, and (d) shows an enlarged EDS area analysis image of (c). Table 7 shows the elemental analysis results at positions J to M shown in Figures 6(b) to 6(d).

[0073] As shown in Figures 6(b) to 6(d) and Table 7, the analysis position for J in Figures 6(b) to 6(d) is carbide 11, the analysis position for K is near the grain boundary, and the analysis position for L is α2 because Cr is concentrated (Cr-rich phase) even in the phase-separated structure. The analysis position for M is estimated to be α1 because no Cr concentration was confirmed at the analysis position for L and it is surrounded by a region where Cr is concentrated.

[0074] [Table 7]

[0075] Structural observation and elemental analysis were also performed on W2. Figures 7(a)-(e) show STEM images and EDS area analysis images of the grain boundaries of W2, and Figures 7(f)-(j) show STEM images and EDS area analysis images of the phase separation structure. Figures 7(a) and (f) show STEM images, (b) and (g) show EDS area analysis images of Fe distribution, (c) and (h) show EDS area analysis images of Cr distribution, (d) and (i) show Co distribution, and (e) and (j) show EDS area analysis images of Ti distribution. Table 8 also shows the elemental analysis results at positions N to Q shown in Figures 7(a), (f), and (h).

[0076] As shown in Figures 7(b) to 7(j) and Table 8, the analysis positions for N in Figures 7(b) to 7(j) are carbides 11, the analysis positions for O are near grain boundaries, and the analysis position for P is α2 because Cr is concentrated (Cr-rich phase) even in the phase-separated structure. The analysis position for Q is estimated to be α1 because no Cr concentration was confirmed at the analysis position for P and the Q is surrounded by a region where Cr is concentrated.

[0077] In addition, in terms of the phase separation structure, when comparing W1 shown in Figures 7(b) to 7(j) with F1 shown in Figures 5(b) to 5(d), W2 had a larger average diameter of α1 and a thicker α2 formed around α1. Although not shown, the carbide 1 precipitated at the grain boundaries of F1 and W1 was found to be M from the analysis of the electron diffraction image. 23 It is presumed to be a C6 type carbide.

[0078] [Table 8]

[0079] From the above, it is estimated that additive product F1, produced using additive manufacturing methods, has dislocations introduced into its structure by being rapidly solidified, and subsequent heat treatment promotes phase separation between the α1 ferromagnetic phase and the α2 paramagnetic phase, resulting in an average diameter of the α1 ferromagnetic phase and a thickness of the α2 paramagnetic phase that are smaller than those of rolled magnets and cast magnets, thereby improving hardness.

[0080] As described above, the manufacturing method of an iron-chromium-cobalt alloy magnet and the iron-chromium-cobalt alloy magnet according to the present embodiment can provide an iron-chromium-cobalt alloy magnet and a manufacturing method of an iron-chromium-cobalt alloy magnet that has excellent freedom in shape and can achieve desired magnetic properties. [Explanation of symbols]

[0081] 11: Carbide 12:α2 paramagnetic phase 13:α1 ferromagnetic phase 15: Thickness of the α2 paramagnetic phase 16: Diameter of α1 ferromagnetic phase

Claims

1. The method comprises an additive manufacturing process for producing an additive manufactured product through a shaping step in which a heat source is irradiated onto the alloy powder to melt and solidify it, and an additive manufacturing step in which the shaping step is repeated, and a process for subjecting the additive manufactured product to heat treatment, The alloy powder is In mass%, Cr: 26-45%, Co: 3 to 35%, Ni: 1.0% or less, Ti: 1.0% or less, The balance includes Fe and impurities, The heat treatment step reduces the coercive force H ｃ A method for producing an iron-chromium-cobalt alloy magnet, characterized in that the current is set to 50 kA / m or more.

2. In mass%, Cr: 30-45%, Ni: 0.1-0.8% The method for producing an iron-chromium-cobalt alloy magnet according to claim 1, characterized in that the hardness of the additive product after the heat treatment process is improved to more than 125% when the hardness before the heat treatment process is 100%.

3. In mass%, Cr: 26-45%, Co: 3 to 35%, Ni: 1.0% or less, the balance being an additive product containing Fe and impurities; Coercive force H ｃ is 50 kA / m or more An iron-chromium-cobalt alloy magnet characterized by:

4. Residual magnetic flux density B ｒ 4. The iron-chromium-cobalt alloy magnet according to claim 3, wherein the magnetic field strength is greater than 1.10 T.

Images