Method for optimizing coercive force and saturation flux density of NiFeMo magnetically soft alloy formed through SLM

Abstract

The invention discloses a method for optimizing coercive force and saturation flux density of NiFeMo magnetically soft alloy formed through SLM, and relates to the field of laser additive manufacturing technologies and soft magnetic materials. According to the method, 0.1-2.0 wt.% of Cu element powder is added for in-situ alloying regulation and control of chemical components of the NiFeMo alloy formed through SLM, the Cu element serves as an accelerant for melt non-spontaneous nucleation in the SLM forming process, a stable nanoscale FCC soft magnetic phase is separated out in a NiFeMo alloy microstructure, and under the condition that aging treatment is not needed, the coercive force of the alloy is effectively reduced, and the saturation flux density is increased. According to the technology, an efficient and economical solution is provided for SLM preparation of a high-performance soft magnetic material by accurately regulating and controlling the chemical components of the NiFeMo soft magnetic alloy.

Description

Technical Field

[0001] The invention relates to the field of laser additive manufacturing technology and soft magnetic materials, and specifically provides an innovative method for optimizing the coercive force and saturation magnetic induction intensity of a NiFeMo soft magnetic alloy formed by SLM. Background Art

[0002] NiFeMo soft magnetic alloy, with its excellent low coercivity and high saturation magnetic induction intensity, has always been a key material for high-precision magnetic shielding in the fields of navigation, aviation and aerospace. At present, the traditional processing technology is relatively complicated in the preparation process of soft magnetic alloy, and it is difficult to form complex shapes and fine structures, which cannot meet the requirements of high efficiency and low cost, limiting its application in the manufacture of precision parts.

[0003] Selective Laser Melting (SLM) technology has brought revolutionary changes to the manufacturing of complex structural parts with its excellent integrated forming capabilities. This technology has shown significant development potential in promoting the lightweight and functionalization of parts, especially in the manufacture of precision, high-end soft magnetic material functional components, and its application prospects are extremely broad. Compared with traditional processing technology, SLM technology can directly produce complex shapes, significantly improve material utilization, shorten processing time, reduce costs, and more finely control microstructure and surface quality. These advantages have opened up new paths for the innovative application of NiFeMo soft magnetic alloys, making SLM-formed NiFeMo soft magnetic alloys gradually become a research hotspot. In the exploration of SLM-formed NiFeMo soft magnetic alloys, researchers usually improve the soft magnetic properties of materials by optimizing process parameters, adjusting scanning strategies, and improving aging treatment processes. Despite this, the fixed chemical composition of NiFeMo soft magnetic alloys and the high cost of adjusting the chemical composition of special SLM pre-alloyed powders still limit the further improvement of the magnetic properties of NiFeMo soft magnetic alloys to a certain extent. These challenges also make it difficult for the alloy to meet the personalized requirements of different application fields for the specific properties of NiFeMo soft magnetic alloys. Therefore, in order to overcome these limitations and further promote the optimization of the performance of NiFeMo soft magnetic alloys, researchers are actively exploring new alloy design strategies to achieve the dual goals of cost-effectiveness and performance improvement to meet the diverse needs of industrial applications. Summary of the invention

[0004] In view of the problems raised by the background technology, the present invention aims to provide a method for optimizing the coercive force and saturation magnetic induction intensity of SLM-formed NiFeMo soft magnetic alloy, that is, by adding Cu element powder to in-situ alloying to control the chemical composition of SLM-formed NiFeMo soft magnetic alloy, change the single FCCγ-(Ni,Fe) solid solution structure of the microstructure, control the easy magnetization direction <001> The preferred grain orientation in the direction achieves the effect of reducing the coercive force and increasing the saturation magnetic induction intensity without complex aging treatment to control the metallurgical defects and morphology of the NiFeMo soft magnetic alloy microstructure.

[0005] The technical route implemented by the present invention is as follows:

[0006] The present invention provides a method for optimizing the coercive force and saturation magnetic induction intensity of a NiFeMo soft magnetic alloy formed by SLM, comprising the following steps:

[0007] S1, NiFeMo soft magnetic alloy powder is prepared by gas atomization technology. Before preparation by SLM forming technology, Cu element powder is doped into the SLM formed NiFeMo soft magnetic alloy powder by in-situ alloying technology as a heterogeneous nucleating agent to promote the formation of stable solid solution and FCC structure soft magnetic phase precipitates.

[0008] S2, mixing the in-situ alloyed Cu element powder in S1 with the NiFeMo soft magnetic alloy powder by using a planetary ball mill to ensure the uniformity of the in-situ alloyed Cu element powder particles.

[0009] S3, taking NiFeMo soft magnetic alloy powder obtained by in-situ alloy doping with Cu element powder obtained by mixing S2 as raw material, and using SLM forming technology, the alloy powder can be melted layer by layer on a fixed substrate under the action of a laser light source until the oxygen content is lower than the standard value to obtain NiFeMo soft magnetic alloy with in-situ alloying of Cu element powder particles.

[0010] S4, the SLM-formed NiFeMo soft magnetic alloy is separated from the substrate by wire cutting technology.

[0011] Furthermore, the proportion of in-situ alloyed Cu element powder added in S1 accounts for 0.1% to 2.0% of the mass of NiFeMo soft magnetic alloy powder; wherein the chemical composition (mass percentage) of NiFeMo soft magnetic alloy powder is Ni: 79: wt.%, Mo: 4.8 wt.%, Mn: 0.3 wt.%, Si: 0.15 wt.%, Cu: 0.20 wt.%, the balance is Fe, and the particle size range is: 15 to 53 μm. The chemical composition of the in-situ alloyed Cu element powder is composed of 100 wt.% Cu element, and the particle size range is 15 to 75 μm.

[0012] Furthermore, the rotation speed of the planetary ball mill in S2 is 350 r / min, the ball milling time is 4.0 h, and the ball milling forms are: revolution and rotation.

[0013] Furthermore, the laser power of the SLM forming technology in S3 is: 200~450W, scanning speed: 600~1200mm / s, scanning spacing: 0.08~0.13mm, powder layer thickness: 20~80μm, substrate temperature: 30~150℃, scanning direction: 67° interlayer rotation.

[0014] The advantages and beneficial effects of the present invention are:

[0015] The present invention mixes Cu element powder with NiFeMo soft magnetic alloy powder by a planetary ball mill, effectively regulates the chemical composition of SLM-formed NiFeMo soft magnetic alloy, changes the crystal structure and phase composition of SLM-formed NiFeMo soft magnetic alloy without subsequent heat treatment process, and precipitates a soft magnetic phase with a stable FCC structure.

[0016] The present invention explores the relationship between the chemical composition and soft magnetic performance index parameters of SLM-formed NiFeMo soft magnetic alloy through Cu in-situ alloying, avoiding the cumbersome process and high cost of regulating the chemical composition of NiFeMo soft magnetic alloy by gas atomization technology.

[0017] The present invention optimizes the soft magnetic properties of the SLM-formed NiFeMo soft magnetic alloy by in-situ alloying by adding Cu element powder, and significantly reduces the coercive force and significantly improves the saturation magnetic induction intensity of the NiFeMo soft magnetic alloy without subsequent aging treatment and process parameter optimization. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Attached Figure 1 (a) is the X-ray diffraction (XRD) pattern of Example 1, Figure 1 (b) is the hysteresis loop of Example 1, Figure 1 (c) is the microstructure of Example 1; Phase characterization results of the Cu in-situ alloying SLM-formed NiFeMo soft magnetic alloy of the present invention

[0019] Attached Figure 2 (a) is the X-ray diffraction (XRD) pattern of Example 2, Figure 2 (b) is the hysteresis loop of Example 2, Figure 2 (c) is the microstructure of Example 2;

[0020] Attached Figure 3 (a) is the X-ray diffraction (XRD) pattern of Example 3, Figure 3 (b) is the hysteresis loop of Example 3, Figure 3(c) is the microstructure of Example 3; DETAILED DESCRIPTION

[0021] Example 1

[0022] This embodiment describes in detail the preparation and SLM forming process of NiFeMo soft magnetic alloy, and the specific steps are as follows:

[0023] (1) First, NiFeMo soft magnetic alloy powder was prepared by gas atomization process, and its chemical composition (mass percentage) was: Ni: 79: wt.%, Mo: 4.8 wt.%, Mn: 0.3 wt.%, Si: 0.15 wt.%, Cu: 0.20 wt.%, and the balance was Fe. Before the experiment, the NiFeMo alloy powder was placed in a drying oven at 100°C for 2 hours to remove moisture from the powder and improve its fluidity.

[0024] (2) Place the NiFeMo soft magnetic alloy powder into the powder chamber of the SLM equipment and prepare for SLM forming of NiFeMo soft magnetic alloy. Level and clean the 316L stainless steel substrate, and then conduct a powder spreading experiment. Ensure that the forming chamber door is closed after all preparations are completed.

[0025] (3) The position placement and process planning of the processed parts are performed on the computer software. The process parameters of the SLM forming process are set as follows: laser power: 250 W, scanning speed: 700 mm / s, scanning spacing: 0.09 mm, powder layer thickness: 30 μm, substrate temperature: 60 °C, and interlayer rotation angle: 67°.

[0026] (4) Import the processing part data with the formed process parameters set on the SLM machine. Before printing, prepare the forming atmosphere by delivering argon gas to the forming chamber until the oxygen content drops to <15ppm to ensure a good forming atmosphere. Then, click the start button to officially start the SLM forming experiment of NiFeMo soft magnetic alloy.

[0027] (5) After the SLM forming of the processed parts is completed, the processed parts are separated from the substrate using wire cutting technology. In order to reduce the residual stress generated during the SLM forming process and protect the microstructure and soft magnetic properties from negative impacts, the parts are placed in a vacuum tube furnace at 500°C for annealing for 2 hours.

[0028] Example 2

[0029] The main steps are as follows:

[0030] (1) Mix 1.1wt.% Cu with 98.9wt.% NiFeMo soft magnetic alloy (chemical composition (mass percentage): Ni: 79wt.%, Mo: 4.8wt.%, Mn: 0.3wt.%, Si: 0.15wt.%, Cu: 0.20wt.%, and the balance is Fe). Mix in a planetary ball mill at 350r / min for 4 hours before the experiment to ensure the uniformity of the powder. After mixing, place the mixed powder in a drying oven at 100°C for 2 hours to remove moisture from the powder and improve its fluidity.

[0031] (2) The mixed Cu element powder particles and NiFeMo soft magnetic alloy powder are placed in the powder chamber of the SLM equipment, and the preparation work for SLM forming of NiFeMo soft magnetic alloy is carried out. The 316L stainless steel substrate is leveled and cleaned, and then the powder spreading experiment is carried out to ensure that the forming chamber door is closed after all preparations are completed.

[0032] (3) The position placement and process planning of the processed parts are performed on the computer software. The process parameters of the SLM forming process are set as follows: laser power: 300 W, scanning speed: 800 mm / s, scanning spacing: 0.1 mm, powder layer thickness: 40 μm, substrate temperature: 80 °C, and interlayer rotation angle of 67°.

[0033] (4) Import the processing part data with the formed process parameters set on the SLM machine. Before printing, prepare the forming atmosphere by delivering argon gas to the forming chamber until the oxygen content drops to <15ppm to ensure a good forming atmosphere. Then, click the start button to officially start the experiment of Cu in-situ alloying SLM forming NiFeMo soft magnetic alloy.

[0034] (5) After the SLM forming of the processed parts is completed, the processed parts are separated from the substrate using wire cutting technology. In order to reduce the residual stress generated during the SLM forming process and protect the microstructure and soft magnetic properties from negative impacts, the parts are placed in a vacuum tube furnace at 500°C for annealing for 2 hours.

[0035] Example 3

[0036] The main steps are as follows:

[0037] (1) Mix 2.0wt.% Cu with 98wt.% NiFeMo soft magnetic alloy (chemical composition (mass percentage): Ni: 79wt.%, Mo: 4.8wt.%, Mn: 0.3wt.%, Si: 0.15wt.%, Cu: 0.20wt.%, and the balance is Fe). Mix in a planetary ball mill at 350r / min for 4 hours before the experiment to ensure the uniformity of the powder. After mixing, place the mixed powder in a drying oven at 100°C for 2 hours to remove moisture from the powder and improve its fluidity.

[0038] (2) The mixed Cu element powder particles and NiFeMo soft magnetic alloy powder are placed in the powder chamber of the SLM equipment, and the preparation work for SLM forming of NiFeMo soft magnetic alloy is carried out. The 316L stainless steel substrate is leveled and cleaned, and then the powder spreading experiment is carried out to ensure that the forming chamber door is closed after all preparations are completed.

[0039] (3) The position placement and process planning of the processed parts are performed on the computer software. The process parameters of the SLM forming process are set as follows: laser power: 350 W, scanning speed: 1000 mm / s, scanning spacing: 0.12 mm, powder layer thickness: 60 μm, substrate temperature: 120 °C, and interlayer rotation angle of 67°.

[0040] (4) Import the processing part data with the formed process parameters set on the SLM machine. Before printing, prepare the forming atmosphere by delivering argon gas to the forming chamber until the oxygen content drops to <15ppm to ensure a good forming atmosphere. Then, click the start button to officially start the experiment of Cu in-situ alloying SLM forming NiFeMo soft magnetic alloy.

[0041] (5) After the SLM forming of the processed parts is completed, the processed parts are separated from the substrate using wire cutting technology. In order to reduce the residual stress generated during the SLM forming process and protect the microstructure and soft magnetic properties from negative impacts, the parts are placed in a vacuum tube furnace at 500°C for annealing for 2 hours.

[0042] The microstructure of the NiFeMo soft magnetic alloy formed by in-situ alloying by SLM with 0.1-2.0 Cuwt.% addition is mainly characterized by FCCγ-(Ni,Fe) solid solution structure. As the Cu in-situ alloying ratio increases, the lattice parameters of the FCC structure show a decreasing trend. Compared with the NiFeMo alloy microstructure in Example 1 (see Appendix Figure 1 ), under the in-situ nucleation of Cu, a soft magnetic phase with a nanoscale FCC structure rich in Cu and Fe is generated inside the microstructure of the SLM-formed NiFeMo soft magnetic alloy, as shown in the attached Figure 2 and 3As shown. Compared with the traditional SLM-formed NiFeMo alloy, we have achieved significant performance improvements by optimizing the alloy ratio. Specifically, in Example 1, the SLM-formed NiFeMo alloy has a coercive force of 27.4A / m and a saturation magnetic induction intensity of 0.6531T; under the in-situ alloying action of Cu in Example 2, the SLM-formed NiFeMo alloy has a coercive force of 16.83A / m, which is reduced by about 12A / m, while the saturation magnetic induction intensity is 0.7089T, which is increased by about 0.06T. These improvements not only confirm the key role of copper in the alloying process, but also demonstrate the great potential for optimizing the properties of soft magnetic alloys by precisely controlling the alloy composition.

[0043] It should be noted that the above embodiments are only intended to illustrate the technical solutions of the present invention and do not constitute a limitation thereto. Although the present invention has been described in detail according to the above embodiments, professionals in the technical field should recognize that they can still adjust the technical solutions described in these embodiments, or implement equivalent substitutions for any or all of the technical features. These adjustments or substitutions will not change the essence of the relevant technical solutions and still fall within the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for optimizing the coercive force and saturation magnetic induction intensity of SLM-formed NiFeMo soft magnetic alloy, characterized in that: NiFeMo alloy is prepared by gas atomization technology, with the mass percentage of Ni: 79wt.%, Mo: 4.8wt.%, Mn: 0.3wt.%, Si: 0.15wt.%, Cu: 0.20wt.%, and the balance is Fe, and the particle size range is: 15-53μm; Adding copper element powder to in-situ alloy SLM-formed NiFeMo alloy, the Cu in-situ alloying ratio is NiFeMo alloy mass: 0.1-2.0wt.%, and the particle size range is 15-75μm; It includes two stages: in the first stage, Cu powder and NiFeMo alloy powder are mixed in a planetary ball mill with a rotation speed of 350r / min and a ball milling time of 4 hours; in the second stage, Cu is added to in-situ alloy the NiFeMo alloy by SLM forming, the oxygen atmosphere during the SLM forming process is <15ppm, and the SLM forming process parameters include laser power of 200-450W, scanning speed of 600-1200mm / s, scanning spacing of 0.08-0.13mm, powder layer thickness of 20-80μm, substrate temperature of 30-150℃, and scanning direction: interlayer rotation of 67°.

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