Cooperative regulation and control method for melting and forming high-magnetostriction Fe-Ga alloy through laser powder bed and product

Abstract

The invention discloses a cooperative regulation and control method for melting and forming a high-magnetostriction Fe-Ga alloy through a laser powder bed and a product, and relates to the technical field of advanced metal material additive manufacturing. The microstructure of the alloy is synchronously regulated and controlled in the forming process by cooperatively controlling the in-situ remelting strategy, the scanning path rotation angle and the interlayer residence time in the laser powder bed melting process. The Fe-Ga alloy prepared by the method has strong lt along the construction direction; 100 gt; through the synergistic effect of the crystallographic texture and the high-number-density nanoscale L60 ordered precipitated phase, the magnetostrictive material shows saturation magnetostrictive strain not lower than 200 ppm in the construction direction. The invention provides an effective way for the integrated preparation of high-performance and complex-shape magnetostrictive functional devices.

Description

Technical Field

[0001] This invention relates to the field of advanced metal additive manufacturing technology, and more specifically, to a method and product for synergistic control of laser powder bed melting forming of highly magnetostrictive Fe-Ga alloys. Background Technology

[0002] Magnetostrictive materials can generate strain under an applied magnetic field, realizing the conversion of magnetomechanical energy. They are key functional materials for manufacturing precision sensors, actuators, and transducers. Among many magnetostrictive materials, Fe-Ga alloys are considered ideal alternatives to rare-earth-based materials due to their high magnetostriction coefficient, good mechanical properties, low hysteresis, and high-frequency response characteristics, and have important application prospects in aerospace, precision instruments, and smart structures.

[0003] The magnetostrictive properties (λ) of Fe-Ga alloys mainly depend on two core microstructural features: one is along the easy magnetization axis. <100> The two factors are the crystallographic texture intensity in the direction of crystallography and the density and size of the nanoscale L60 ordered phase dispersed in the matrix. Traditional preparation methods (such as directional solidification, rolling, and recrystallization annealing) can enhance the texture or promote precipitation to some extent, but it is difficult to achieve a synergistic effect between the two at a high performance level, and they are limited by the geometric complexity, size, and production efficiency of the parts.

[0004] Laser powder bed melting (LPBF), a revolutionary additive manufacturing technology, offers a unique approach to fabricating complex-shaped Fe-Ga alloy parts. The extremely high temperature gradient and cooling rate of the LPBF process theoretically favor epitaxial growth along the build-up direction. <100> Columnar crystal texture, coupled with rapid non-equilibrium solidification, may facilitate the precipitation of metastable nanophases. However, in existing technologies, the performance of Fe-Ga alloys prepared by LPBF (λ is typically below 150 ppm) falls far short of their theoretical potential. This is mainly because process parameters are usually optimized in isolation for density or single microstructure characteristics, failing to reveal and effectively control the intrinsic relationship between the two competing yet coupled processes of "texture formation" and "nanophase precipitation." For example, excessively high energy input or inappropriate scanning strategies can lead to weakened texture; while excessively rapid cooling or insufficient thermal cycling inhibits the precipitation kinetics of the L60 phase. Therefore, developing an LPBF forming method that can synergistically control texture and precipitated phases is a key technological bottleneck for the industrial application of high-performance, near-net-shape Fe-Ga magnetostrictive components. Summary of the Invention

[0005] The purpose of this invention is to provide a synergistic control method and product for forming high magnetostrictive Fe-Ga alloys by laser powder bed melting. This method can overcome the technical difficulties in the preparation of Fe-Ga alloys by existing LPBF technology, such as poor magnetostrictive performance and difficulty in synergistic optimization of microstructure (texture and precipitated phase), and directly form Fe-Ga alloy parts with ultra-high magnetostrictive performance.

[0006] The above-mentioned technical objective of the present invention is achieved through the following technical solution: a method for synergistic control of laser powder bed melting forming of high magnetostrictive Fe-Ga alloy, the method comprising the following steps:

[0007] S1. Prepare a composition of Fe by atomic percentage. 81 Ga 19 Pre-alloyed spherical powder; S2. Under the protection of an inert atmosphere, a laser powder bed melting device and an in-situ remelting strategy are used to form parts layer by layer; the in-situ remelting strategy refers to performing deposition scanning and remelting scanning on each formed layer in sequence; S3. During the forming process, the synergistic effect of controlling the following key parameters: a) Scanning path control: The rotation angle of the laser scanning direction between adjacent forming layers is controlled as θ1, and the rotation angle of the laser scanning direction between deposition scanning and remelting scanning within the same forming layer is controlled as θ2; where θ1 and θ2 are both 67°±5°; b) Thermal cycling control: The interlayer dwell time DT is controlled to be 10 seconds to 60 seconds; the interlayer dwell time is the time interval between the completion of one layer of laser scanning and the start of laying the next layer of powder; c) Energy input control: The deposition scan uses a first laser power P1 and a first scanning speed V1, and the remelting scan uses a second laser power P2 and a second scanning speed V2; wherein, P1 > P2, V1 > V2, and the surface energy density of the remelting scan is higher than that of the deposition scan.

[0008] The present invention is further configured such that the optimal values ​​of θ1 and θ2 are 67°; and the interlayer dwell time DT is preferably 20 seconds ± 5 seconds.

[0009] The present invention is further configured such that the deposition scanning parameters are: the first laser power P1 is 110-130 W, the first scanning speed V1 is 1000-1200 mm / s, and the first scanning spacing H1 is 0.055-0.065 mm;

[0010] The remelting scanning parameters are as follows: the second laser power P2 is 70-90 W, the second scanning speed V2 is 450-550 mm / s, the second scanning spacing H2 is 0.045-0.055 mm, and the layer thickness is 0.035-0.045 mm.

[0011] The present invention is further configured such that: the first laser power P1 is preferably 120 W, the first scanning speed V1 is preferably 1100 mm / s, and the first scanning spacing H1 is preferably 0.06 mm; the second laser power P2 is preferably 80 W, the second scanning speed V2 is preferably 500 mm / s, and the second scanning spacing H2 is preferably 0.05 mm; and the layer thickness is preferably 0.04 mm.

[0012] The present invention is further configured such that the D50 particle size of the pre-alloyed powder is 30-35 μm.

[0013] The present invention is further configured such that the inert atmosphere is argon gas with an oxygen content of less than 100 ppm.

[0014] The present invention further provides a highly magnetostrictive Fe-Ga alloy prepared according to the above method, the alloy having a strong magnetostriction along the construction direction. <100> Texture, in which <100> The grain area fraction with orientation parallel to the construction direction is not less than 75%; and the alloy matrix contains dispersed L60 ordered precipitates with an average size of less than 5 nm, the number density of which is not less than 3.5 × 10⁻⁶. 10 mm -2 .

[0015] The present invention is further configured such that the saturated magnetostrictive strain λ∥ of the alloy parallel to the construction direction is not less than 210 ppm.

[0016] The present invention is further configured such that the density of the alloy is not less than 99.0%.

[0017] The present invention further provides a magnetostrictive functional device, wherein the magnetostrictive functional device includes a magnetostrictive strain element, the magnetostrictive strain element using a high magnetostrictive Fe-Ga alloy as its core.

[0018] In summary, the present invention has the following beneficial effects:

[0019] 1. Clear Coordination and Control Mechanism: This invention systematically reveals for the first time the combination of a 67° rotational scanning strategy and a moderate interlayer residence time under LPBF in-situ remelting conditions. This strategy breaks the periodicity of the traditional 90° or 0° scanning thermal field and achieves "strong" <100> The key to the synergistic growth of "texture" and "high-density nano-L60 phase" lies in the 67° rotation, which generates asymmetric and non-periodic complex heat flow, suppressing stray crystal formation and enhancing epitaxial growth. At the same time, this thermal field distribution, combined with a moderate interlayer residence time (about 20 seconds), creates a "thermodynamic window" that ensures short-range diffusion of Ga atoms to promote L60 phase nucleation without causing dissolution or excessive grain coarsening due to overheating.

[0020] 2. Significant performance breakthrough: Fe directly formed by this method 81 Ga 19 The alloy, without any post-treatment, can achieve a saturation magnetostrictive strain of up to 225 ppm (along the BD direction). This value far exceeds the performance of Fe-Ga alloys prepared by LPBF (usually ≤150 ppm) reported so far, and can even be compared with the preferred orientation materials prepared by some traditional methods, achieving a leap in the performance of LPBF-prepared materials.

[0021] 3. Strong process operability: The parameter range provided by this invention is clear and specific, and it is easy to implement and reproduce on commercial LPBF equipment, providing a stable and reliable process route for the integrated and near-net-shape manufacturing of high-performance complex-shaped Fe-Ga magnetostrictive devices.

[0022] 4. Unique microstructure: The obtained "strong texture + high-density nano-coherent precipitation" structure is a non-equilibrium structure that is difficult to achieve by traditional casting or heat treatment, which constitutes the novelty of the product itself and provides the material with excellent comprehensive magnetostrictive properties (combination of high saturation strain and good low field sensitivity). Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the "double 67°" rotational scanning strategy used in Embodiment 1 of the present invention;

[0024] Figure 2 This is a comparison of the EBSD inverse pole figures (IPF) of the samples from Comparative Example 1 (90° / 0° scan) and Example 1 (67° / 67° scan) of the present invention;

[0025] Figure 3 These are TEM analysis images of the sample in Example 1 of this invention: (a) is a bright field image, and (b) is a selected area electron diffraction (SAED) pattern of the

[100] zone axis, showing L60 superlattice spots;

[0026] Figure 4This is a comparison graph of the magnetostrictive strain (λ∥) curves of the samples in Example 1, Comparative Example 1, and Comparative Example 2 of the present invention;

[0027] Figure 5 For different scanning strategies and interlayer dwell times, the samples <100> Relationship between texture intensity and L60 phase number density. Detailed Implementation

[0028] The following is in conjunction with the appendix Figure 1-5 The present invention will be described in further detail below.

[0029] Example 1

[0030] 1. Preparation of high magnetostrictive Fe-Ga alloy

[0031] (1) Raw materials

[0032] Fe was prepared by vacuum induction melting combined with gas atomization technology. 81 Ga 19 (at.%) Pre-alloyed powder, after sieving, D10=16.90 μm, D50=32.28 μm, D90=56.42 μm.

[0033] (2) Equipment and Atmosphere

[0034] The HANS-M100 LPBF equipment was used, with the forming chamber filled with 99.999% high-purity argon gas and the oxygen content controlled at <80ppm. The substrate was made of 304 stainless steel and preheated to 150℃.

[0035] (3) Molding process

[0036] Layer thickness: 0.04 mm.

[0037] Scanning strategy: such as Figure 1 As shown, a "double 67°" rotation is used. That is, the adjacent forming layers are rotated by 67° (θ1=67°), and the deposition scan track and the remelting scan track within the same layer are also rotated by 67° (θ2=67°).

[0038] Inter-floor dwell time: 20 seconds.

[0039] Laser parameters: Includes two parts: deposition scanning and remelting scanning. Deposition scanning: power 120 W, speed 1100 mm / s, scanning interval 0.06 mm. Remelting scanning: power 80 W, speed 500 mm / s, scanning interval 0.05 mm.

[0040] (The calculated surface energy density of the deposition scan is approximately 1.82 J / mm²) 2 (Remelting scan: approximately 3.20 J / mm).

[0041] (4) Post-processing

[0042] After forming, the sample is removed by wire cutting without any heat treatment.

[0043] 2. Characterization and Performance Testing

[0044] Density: Measured using Archimedes' displacement method, the relative density is 99.04%.

[0045] Texture analysis: EBSD analysis was performed on the XZ section (parallel to BD) of the sample. Results are as follows... Figure 2 As shown in (b), the sample exhibits a significant columnar crystal structure, and the IPF plot shows strong... <100> / / BD texture. Statistically, <100> The area fraction of oriented grains reached 80.3%.

[0046] Precipitated phase analysis: TEM observation as follows Figure 3 As shown. {100} type superlattice spots are clearly visible in the SAED spectrum ( Figure 3 (b yellow circle) confirms the existence of the L60 phase. Statistical analysis of the bright-field image shows that the number density of the L60 phase is approximately 3.9 × 10⁻⁶. 10 mm -2 The average size is about 4nm.

[0047] Magnetostrictive properties: Tested with strain gauges attached along the BD direction. Results are as follows. Figure 4 As shown in curve A, the saturation magnetostrictive strain λ∥ reaches 225 ± 7 ppm.

[0048] Comparative Example 1 (Traditional 90° rotation strategy)

[0049] Compared to Example 1, Comparative Example 1 is identical to Example 1 in all parameters except that the scanning strategy is changed to: 90° rotation between adjacent forming layers, and the deposition and remelting scanning directions within the same layer are consistent (0° rotation), and the interlayer dwell time is 0 seconds.

[0050] The synthesized high magnetostrictive Fe-Ga alloy was characterized and its properties were tested. The results are as follows:

[0051] Density: 98.93%.

[0052] Texture: such as Figure 2 As shown in (a), it is still a columnar crystal, but <100> / / The texture strength of BD is significantly weaker than that of Example 1, with an area fraction of only 55.5%.

[0053] Precipitated phase: The number density of phase L60 is approximately 2.8 × 10⁻⁶. 10 mm -2 .

[0054] Magnetostrictive properties: such as Figure 4As shown in curve B, λ∥ is only about 150 ppm.

[0055] Comparative Example 2 (Extra-long Inter-floor Dwell Time) is based on Example 1, except that the inter-floor dwell time is extended from 20 seconds to 180 seconds.

[0056] The synthesized high magnetostrictive Fe-Ga alloy was characterized and its properties were tested. The results are as follows:

[0057] Density: 98.76%.

[0058] Texture: <100> / / BD texture is further enhanced, with an area fraction of 78.4%.

[0059] Precipitated phase: Due to excessively long interlayer cooling time and excessive heat loss, the precipitation kinetics of the L60 phase were suppressed, and its number density was significantly reduced to approximately 2.4 × 10⁻⁶. 10 mm -2 .

[0060] Magnetostrictive properties: such as Figure 4 As shown in curve C, λ∥ decreases to approximately 130 ppm. This indicates that excessively long residence times disrupt the synergy between texture and precipitated phases, resulting in a significant decrease in performance even with stronger textures.

[0061] Comparative Example 3 (without in-situ remelting)

[0062] Compared to Example 1, Comparative Example 3 employs a conventional single-pass scanning strategy (without remelting), with a scanning strategy of 67° interlayer rotation and a 20-second interlayer dwell time. The laser parameters were optimized as follows: power 140 W, speed 800 mm / s, and scanning spacing 0.07 mm.

[0063] The synthesized high magnetostrictive Fe-Ga alloy was characterized and its properties were tested. The results are as follows:

[0064] The sample exhibited microcracks and a density of only 97.5%. The magnetostrictive properties were discrete and low (λ∥<50 ppm).

[0065] This demonstrates that in-situ remelting is crucial for eliminating hot cracks during the LPBF process of Fe-Ga alloys and obtaining dense, high-performance parts.

[0066] Application Example 1

[0067] The synergistic control method provided in this invention can be directly applied to the production of various Fe-Ga alloy magnetostrictive functional devices using LPBF technology, such as micro-actuators, sonar transducers, vibration energy harvesters, and precision valve drive components. This method has a clear process window, is easily automated in industrial-grade equipment, and possesses significant practical value and broad industrialization prospects.

[0068] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A method for synergistic control of laser powder bed melting forming of highly magnetostrictive Fe-Ga alloys, characterized in that: The method includes the following steps: S1. Prepare a composition of Fe by atomic percentage. 81 Ga 19 Pre-alloyed spherical powder; S2. Under the protection of an inert atmosphere, a laser powder bed melting device and an in-situ remelting strategy are used to form parts layer by layer; the in-situ remelting strategy refers to performing deposition scanning and remelting scanning on each formed layer in sequence; S3. During the forming process, the synergistic effect of controlling the following key parameters: a) Scanning path control: The rotation angle of the laser scanning direction between adjacent forming layers is controlled as θ1, and the rotation angle of the laser scanning direction between deposition scanning and remelting scanning within the same forming layer is controlled as θ2; where θ1 and θ2 are both 67°±5°; b) Thermal cycling control: The interlayer dwell time DT is controlled to be 10 seconds to 60 seconds; the interlayer dwell time is the time interval between the completion of one layer of laser scanning and the start of laying the next layer of powder; c) Energy input control: The deposition scan uses a first laser power P1 and a first scanning speed V1, and the remelting scan uses a second laser power P2 and a second scanning speed V2; wherein, P1 > P2, V1 > V2, and the surface energy density of the remelting scan is higher than that of the deposition scan.

2. The method for synergistic control of laser powder bed melting forming of high magnetostrictive Fe-Ga alloy according to claim 1, characterized in that: The optimal values ​​for θ1 and θ2 are 67°; the preferred interlayer dwell time DT is 20 seconds ± 5 seconds.

3. The method for synergistic control of laser powder bed melting forming of high magnetostrictive Fe-Ga alloy according to claim 1, characterized in that: The deposition scanning parameters are as follows: the first laser power P1 is 110-130 W, the first scanning speed V1 is 1000-1200 mm / s, and the first scanning spacing H1 is 0.055-0.065 mm. The remelting scanning parameters are as follows: the second laser power P2 is 70-90 W, the second scanning speed V2 is 450-550 mm / s, the second scanning spacing H2 is 0.045-0.055 mm, and the layer thickness is 0.035-0.045 mm.

4. The method for synergistic control of laser powder bed melting forming of high magnetostrictive Fe-Ga alloy according to claim 3, characterized in that: The first laser power P1 is preferably 120 W, the first scanning speed V1 is preferably 1100 mm / s, and the first scanning spacing H1 is preferably 0.06 mm; the second laser power P2 is preferably 80 W, the second scanning speed V2 is preferably 500 mm / s, and the second scanning spacing H2 is preferably 0.05 mm; the layer thickness is preferably 0.04 mm.

5. The method for synergistic control of laser powder bed melting forming of high magnetostrictive Fe-Ga alloy according to claim 1, characterized in that: The pre-alloyed powder has a D50 particle size of 30-35 μm.

6. The method for synergistic control of laser powder bed melting forming of high magnetostrictive Fe-Ga alloy according to claim 1, characterized in that: The inert atmosphere is argon, with an oxygen content of less than 100 ppm.

7. The highly magnetostrictive Fe-Ga alloy prepared by the method according to any one of claims 1-6, characterized in that: The alloy has a high strength along the construction direction. <100> Texture, in which <100> The grain area fraction with orientation parallel to the construction direction is not less than 75%; and the alloy matrix contains dispersed L60 ordered precipitates with an average size of less than 5 nm, the number density of which is not less than 3.5 × 10⁻⁶. 10 mm -2 .

8. The high magnetostrictive Fe-Ga alloy according to claim 7, characterized in that: The alloy exhibits a saturated magnetostrictive strain λ∥ parallel to the construction direction of not less than 210 ppm.

9. The high magnetostrictive Fe-Ga alloy according to claim 7, characterized in that: The density of the alloy is not less than 99.0%.

10. A magnetostrictive functional device, characterized in that: The magnetostrictive functional device includes a magnetostrictive strain element, which uses the high magnetostrictive Fe-Ga alloy as described in any one of claims 6-9 as its core.

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