Method for controlling grain orientation and magnetic performance of Ni-Fe-based magnetically soft alloy prepared through SLM

Abstract

A method for controlling grain orientation and magnetic performance of Ni-Fe-based magnetically soft alloy prepared through SLM belongs to the field of additive manufacturing, and comprises the steps that in the process of forming the Ni-Fe-based magnetically soft alloy through SLM, the particle size range of doped Mo element powder and the preheating temperature of a substrate are controlled, the particle size range of the Mo element powder is 15-105 microns, and the preheating temperature of the substrate is 120-180 DEG C. Regulating the grain size of the Ni-Fe-based magnetically soft alloy formed by SLM to be 1t by controlling the doped Mo element powder particles and the preheating temperature of the substrate; 001gt, 001gt; due to the preferred orientation of the direction, the difficult magnetization shaft lt is reduced; 001gt, 001gt; the number of the crystal grains hinders a thick columnar crystal structure growing in the construction direction, and generation of an ordered phase is promoted. And the grain orientation in the easy magnetization axis direction is controlled, the coercive force of the alloy is effectively reduced, and the requirement for high magnetic performance of higher-end parts of the Ni-Fe-based magnetically soft alloy formed through SLM is met.

Description

Technical Field

[0001] The invention belongs to the field of metal additive manufacturing, and in particular relates to a method for controlling the grain orientation and magnetic properties of a Ni-Fe based soft magnetic alloy prepared by SLM. Background Art

[0002] Ni-Fe-based soft magnetic alloy, as a typical soft magnetic material, is widely used in transformers, motors, sensors, electromagnetic shielding and other fields due to its excellent comprehensive magnetic properties and good mechanical properties. However, the traditional preparation methods of Ni-Fe-based soft magnetic alloys, such as smelting, hot rolling, cold rolling and annealing, have some limitations that are difficult to overcome. For example, these methods are usually difficult to accurately control the microstructure and grain orientation of the alloy, resulting in large fluctuations in the magnetic properties of the alloy, which is difficult to meet the needs of high-performance applications. In addition, alloys prepared by traditional methods often have problems such as coarse grains, uneven structure and large internal stress, which seriously affect the magnetic properties and application performance of the alloy.

[0003] In order to solve these problems, the materials science community has been exploring new preparation methods and technologies. As an emerging additive manufacturing technology, Selective Laser Melting (SLM) technology provides new possibilities for the preparation of Ni-Fe-based soft magnetic alloys due to its ability to manufacture complex structural parts with high precision and quickly. SLM technology is based on the principle of powder bed melting, and uses high-energy lasers to melt metal powder layer by layer to achieve direct manufacturing of parts. This technology has the advantages of fast cooling speed, fine microstructure, and controllable grain orientation, providing a new way to improve the magnetic properties of Ni-Fe-based soft magnetic alloys. For example, <100> Oriented grains usually have higher permeability and lower coercivity, while <111> Oriented grains have higher saturation magnetic induction. Therefore, controlling the grain orientation during SLM preparation is crucial to improving the magnetic properties of Ni-Fe based soft magnetic alloys.

[0004] In summary, the traditional method for preparing Ni-Fe-based soft magnetic alloys has certain limitations, and SLM technology provides new opportunities for the precision preparation of alloys. However, how to comprehensively utilize the advantages of SLM technology to accurately control the grain orientation and magnetic properties of the alloy is still a problem to be solved in the field of materials science. The present invention aims to provide a method for controlling the grain orientation and magnetic properties of Ni-Fe-based soft magnetic alloys prepared by SLM, so as to overcome the shortcomings of the prior art and improve the comprehensive performance and application value of the alloy. Summary of the invention

[0005] In response to the problems raised in the background technology, the present invention provides a method for controlling the grain orientation and magnetic properties of Ni-Fe-based soft magnetic alloys prepared by SLM, which can customize the Ni-Fe-based soft magnetic alloys with specific grain orientation, low coercive force and high saturation magnetic induction intensity, thereby achieving the purpose of customized magnetic shielding of parts.

[0006] To achieve the above effects, the present invention is mainly implemented through the following technical routes:

[0007] A method for controlling the grain orientation and magnetic properties of Ni-Fe-based soft magnetic alloy prepared by SLM, optimizing the existing SLM-based Ni-Fe-based soft magnetic alloy forming process, combining Mo element powder doping with adjusting the preheating substrate temperature, wherein the Mo element powder particle size is 15 to 105 μm, and the Mo element powder particle size needs to be classified according to 10 μm as an order of magnitude. The substrate preheating temperature range is: 120 to 180 ° C.

[0008] Preferably, the Ni-Fe-based soft magnetic alloy is prepared by gas atomization, and its element mass fraction is: 14.9wt.% Fe, 4.95wt.% Mo, 0.30wt.% Cr, 0.50wt.% Mn, 0.20wt.% Si, 0.80wt.% Cu, and the balance is Ni. The powder particle size range is 15-53μm.

[0009] Preferably, the particle size range of the Mo element-doped powder is 15-105 μm, and is classified using sieves of different mesh sizes: 15-25 μm, 25-35 μm, 35-45 μm, 45-55 μm, 55-65 μm, 65-75 μm, 75-85 μm, 85-95 μm, 95-105 μm.

[0010] Preferably, the Ni-Fe-based soft magnetic alloy is doped with Mo element powder, the mass fraction of the Ni-Fe-based soft magnetic alloy powder is 99%, and the remainder is Mo element powder.

[0011] Preferably, the forming step comprises

[0012] S1, placing the Mo / Ni-Fe-based mixed powder with the prepared ratio in a planetary ball mill for thorough mixing, and then keeping it warm at 100° C. for 2 hours in a drying oven to ensure the dryness of the powder and enhance the fluidity of the powder.

[0013] S2, import the part model and plan the printing path and process parameters.

[0014] S3, before printing, fill with argon gas to ensure that the oxygen content in the atmosphere of the forming chamber is reduced to <15ppm, and adjust the substrate temperature to the set value.

[0015] S4, click the SLM forming button until the part is printed.

[0016] S5, taking out the formed part sample from the forming chamber, and separating the part sample from the substrate by using wire cutting technology.

[0017] Preferably, the laser power of the SLM forming process is 350 W, the scanning speed is 700 mm / s, the scanning spacing is 0.1 mm, the powder layer thickness is 60-90 μm, and the scanning direction is rotated 67°.

[0018] Preferably, the substrate preheating temperature ranges from 120 to 180°C.

[0019] The present invention has the following advantages and beneficial effects compared with the existing SLM formed Ni-Fe based soft magnetic alloy:

[0020] (1) The embodiment of the present invention provides a method for controlling the grain orientation and magnetic properties of Ni-Fe-based soft magnetic alloy prepared by SLM. By doping Mo element powder and controlling the particle size range of the doped powder during the SLM forming process of Ni-Fe-based soft magnetic alloy, combined with the setting of the substrate temperature, high-density forming quality is achieved, overcoming the influence of the thermal cycle effect and the preferred orientation of grains in the (001) direction of the traditional SLM forming microstructure. Under the SLM forming condition along the building direction, the number of grains in the easy magnetization direction (111) is regulated to adjust the magnetic properties of the Ni-Fe-based soft magnetic alloy prepared by SLM.

[0021] (2) The embodiment of the present invention provides a method for controlling the grain orientation and magnetic properties of Ni-Fe-based soft magnetic alloy prepared by SLM, wherein the substrate preheating temperature is 120-180°C, and the particle size of the Mo element powder is in the range of 15-105 μm. By hindering the growth of coarse columnar crystals along the construction direction and forming favorable factors for equiaxed grain transformation, the grain orientation of the SLM-formed Ni-Fe-based soft magnetic alloy in the (111) direction increases by about 18%, and the coercivity decreases by about 20 A / m.

[0022] (3) An embodiment of the present invention provides a method for controlling the grain orientation and magnetic properties of Ni-Fe-based soft magnetic alloys prepared by SLM, thereby achieving the control of the microstructure and magnetic properties of the chemical composition of the Ni-Fe-based soft magnetic alloy under gas atomization without the need for subsequent expensive aging treatment and tedious preliminary control. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions involved in the specific embodiments of the present invention, the drawings used in the embodiments are briefly introduced below. It should be emphasized that these drawings only show several embodiments of the present invention and do not limit the scope of protection of the present invention. For those skilled in the art, other related drawings can be derived based on these drawings without creative work. In the drawings provided:

[0024] Figure 1 The electron backscatter diffraction (EBSD) patterns of SLM-formed Ni-Fe based soft magnetic alloys are shown in Example 1, Example 2 and Example 3 when the substrate preheating temperatures are 130°C, 150°C and 170°C, and the Mo element powder particle sizes are 15-25μm, 65-75μm and 95-105μm, respectively.

[0025] Figure 2 Hysteresis loops of Ni-Fe based soft magnetic alloy formed by SLM are shown in Example 1, Example 2 and Example 3 when the substrate preheating temperatures are 130°C, 150°C and 170°C, and the particle sizes of Mo element powder are 15-25μm, 65-75μm and 95-105μm, respectively.

[0026] Figure 3 The coercive force and grain orientation ratio diagram of SLM-formed Ni-Fe based soft magnetic alloy are shown in Example 1, Example 2 and Example 3 when the substrate preheating temperatures are 130°C, 150°C and 170°C, and the Mo element powder particle sizes are 15-25μm, 65-75μm and 95-105μm, respectively. DETAILED DESCRIPTION

[0027] In order to further reveal the purpose, technical details and potential advantages of the present invention, the present invention will be further described in detail with the help of specific embodiments and related drawings. The purpose of these embodiments and drawings is to illustrate the core concepts and technical features of the present invention, and should not be interpreted as a strict limitation on the scope of protection of the present invention.

[0028] Example 1

[0029] The main steps are as follows:

[0030] (1) The Mo element powder prepared by gas atomization is screened with a sieve with mesh numbers of #500 and #1000, and the particle size range of the Mo element powder is controlled to be 15-25 μm. The Mo element powder is doped in the Ni-Fe-based soft magnetic alloy, and the mass fraction of the Ni-Fe-based soft magnetic alloy powder is 99%, and the remainder is the Mo element powder. Subsequently, the Mo / Ni-Fe-based mixed powder is placed in a planetary ball mill and mixed and kept in a drying oven at 100°C for 2 hours.

[0031] (2) Pour the processed Mo / Ni-Fe-based mixed powder into the powder chamber of the 3D printing equipment, and use a tool to level the substrate, scraper and powder.

[0032] (3) Use software to slice the imported model and set the printing parameters: laser power 350 W, scanning speed 700 mm / s, scanning spacing 0.1 mm, powder layer thickness 60 μm, scanning direction rotation 67°, and substrate preheating temperature 130 °C.

[0033] (4) When the oxygen content is less than 15ppm and the substrate temperature reaches 130°C, you can click to start printing until the part is printed.

[0034] (5) After the SLM forming of Ni-Fe based soft magnetic alloy parts is completed, the parts are separated from the substrate by wire cutting technology and placed in a vacuum tube furnace at 450 °C for annealing for 2 h to eliminate the internal stress that may be generated during the rapid cooling stage before mechanical processing can be performed for microstructure and magnetic property testing.

[0035] Example 2

[0036] The main steps are as follows:

[0037] (1) The Mo element powder prepared by gas atomization is screened with a sieve with mesh numbers of #200 and #240, and the particle size range of the Mo element powder is controlled to be 65-75 μm. The Ni-Fe-based soft magnetic alloy is doped with Mo element powder, and the mass fraction of the Ni-Fe-based soft magnetic alloy powder is 99%, and the remainder is Mo element powder. Subsequently, the Mo / Ni-Fe-based mixed powder is placed in a planetary ball mill and a drying oven at 100°C for 2 hours.

[0038] (2) Pour the processed Mo / Ni-Fe-based mixed powder into the powder chamber of the 3D printing equipment, and use a tool to level the substrate, scraper and powder.

[0039] (3) Use software to slice the imported model and set the printing parameters: laser power 350 W, scanning speed 700 mm / s, scanning spacing 0.1 mm, powder layer thickness 85 μm, scanning direction rotation 67°, and substrate preheating temperature 130 °C.

[0040] (4) When the oxygen content is less than 15ppm and the substrate temperature reaches 150°C, you can click to start printing until the part is printed.

[0041] (5) After the SLM forming of Ni-Fe based soft magnetic alloy parts is completed, the parts are separated from the substrate by wire cutting technology and placed in a vacuum tube furnace at 450 °C for annealing for 2 h to eliminate the internal stress that may be generated during the rapid cooling stage before mechanical processing can be performed for microstructure and magnetic property testing.

[0042] Example 3

[0043] The main steps are as follows:

[0044] (1) The Mo element powder prepared by gas atomization was screened with a sieve with mesh number of #150 and #170, and the particle size range of the Mo element powder was controlled to be 95-105 μm. The Mo element powder was doped in the Ni-Fe-based soft magnetic alloy, and the mass fraction of the Ni-Fe-based soft magnetic alloy powder was 99%, and the remainder was Mo element powder. Subsequently, the Mo / Ni-Fe-based mixed powder was placed in a planetary ball mill and a drying oven at 100°C for 2 hours.

[0045] (2) Pour the processed Mo / Ni-Fe-based mixed powder into the powder chamber of the 3D printing equipment, and use a tool to level the substrate, scraper and powder.

[0046] (3) Use software to slice the imported model and set the printing parameters: laser power 350 W, scanning speed 700 mm / s, scanning spacing 0.1 mm, powder layer thickness 95 μm, scanning direction rotation 67°, and substrate preheating temperature 130 °C.

[0047] (4) When the oxygen content is less than 15ppm and the substrate temperature reaches 170°C, you can click to start printing until the part is printed.

[0048] (5) After the SLM forming of Ni-Fe based soft magnetic alloy parts is completed, the parts are separated from the substrate by wire cutting technology and placed in a vacuum tube furnace at 450 °C for annealing for 2 h to eliminate the internal stress that may be generated during the rapid cooling stage before mechanical processing can be performed for microstructure and magnetic property testing.

[0049] Mo element powder is doped in Ni-Fe based soft magnetic alloy, the mass fraction of Ni-Fe based soft magnetic alloy powder is 99%, and the balance is Mo element powder, the particle size range of Mo element powder is mainly controlled to be 15-105 μm, and 10 μm is used as a particle size range for screening, combined with the preheating substrate temperature adjusted to 120-180 ° C, the SLM forming Ni-Fe based soft magnetic alloy molten pool temperature distribution is affected, the temperature gradient of grain growth is reduced, the metallurgical behavior of diffusion and combination of Mo element as nucleation particle and surrounding matrix elements hinders the growth of coarse columnar crystals, and changes the preferred orientation of grains in the (001) direction under SLM forming, such as the attached Figure 1 Compared with the traditional SLM formed Ni-Fe based soft magnetic alloy, the grain orientation and magnetic properties are regulated by controlling the particle size range of the Mo element powder and the preheating substrate temperature. Specifically, as the particle size range of the Mo element powder increases, the number of grains in the easy magnetization direction (111) of the Ni-Fe based soft magnetic alloy increases by about 18%, and the coercive force value continues to decrease to about 13A / m, which is significantly improved. Figure 3 It is shown that there is great potential in controlling the particle size range of Mo element powder and the preheating temperature of the substrate to optimize the microstructure and magnetic properties.

[0050] It is worth noting that the description of the above-mentioned embodiments is intended to illustrate the technical solution of the present invention, not to strictly define its protection scope. Although we have explained the present invention in detail through specific embodiments, professionals in the field should understand that they can make appropriate adjustments according to the technical solutions disclosed in these embodiments, or make equivalent replacements for any one or all of the technical features. These adjustments or replacements will not change the core essence of the technical solution, and still fall within the protection scope of the technical solution of the embodiments of the present invention. In other words, the protection of the present invention is not limited to the specific details of the above-mentioned embodiments, but covers all equivalent changes and improvements that do not change its basic concept. Therefore, the protection scope of the present invention should be based on the content of the claims, and the above-mentioned embodiments are only used as a reference for understanding the present invention.

Claims

1. A method for controlling the grain orientation and magnetic properties of Ni-Fe based soft magnetic alloy prepared by SLM, characterized in that: The Ni-Fe-based alloy powder prepared by gas atomization technology has the following inherent elements by mass fraction: iron (Fe) 14.9wt.%, molybdenum (Mo) 4.95wt.%, chromium (Cr) 0.30wt.%, manganese (Mn) 0.50wt.%, silicon (Si) 0.20wt.%, copper (Cu) 0.80wt.%, and the rest is nickel (Ni), and the powder particle size range is: 15-53μm; then, Mo element powder is doped into the Ni-Fe-based alloy powder, and the mass fraction of the Ni-Fe-based alloy powder is 99%, and the rest is Mo element powder.

2. The method according to claim 1, characterized in that The following steps are involved: Step (1): Mo element powder is prepared by gas atomization; Step (2): SLM forming parameter setting Laser power 350W, scanning speed 700mm / s, scanning spacing 0.1mm, powder layer thickness 60-90μm, substrate preheating temperature 120-180℃, scanning direction rotation 67°; Step (3): SLM forming process When the oxygen content is less than 15ppm and the substrate temperature reaches 120-180℃, click to start printing until the part is printed; Step (4): Sample annealing Vacuum tube furnace: temperature 450 °C, time 2 h, to eliminate the internal stress generated during the rapid cooling stage of SLM.

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