Magnetic performance optimization heat treatment method for additive manufacturing Fe-Ga alloy, product and application

Abstract

The invention belongs to the technical field of metal material heat treatment, and discloses a heat treatment method for optimizing the magnetic performance of an additive manufacturing Fe-Ga alloy, a product and application, and the heat treatment method is characterized by comprising the following steps: S1, taking a Fe-Ga alloy part formed by melting in a laser powder bed, and placing the Fe-Ga alloy part in a protective atmosphere or a vacuum environment; s2, the alloy part is heated to the first heat treatment temperature T, and heat preservation is conducted for time t at the temperature T; wherein the first heat treatment temperature T is greater than or equal to 720 DEG C and less than or equal to 800 DEG C; the heat preservation time t is larger than or equal to 0.5 h and smaller than or equal to 2 h; s3, after heat preservation is finished, the part is rapidly cooled till the room temperature is reached; wherein the cooling rate is not lower than 50 DEG C / s; the method solves the technical problem that when the traditional high-temperature annealing treatment is carried out on the LPBF to form the Fe-Ga alloy, residual stress release, texture retention and metastable phase regulation and control cannot be taken into account at the same time.

Description

Technical Field

[0001] This invention relates to the field of heat treatment technology for metallic materials, specifically to a method, product, and application for optimizing the magnetic properties of additively manufactured Fe-Ga alloys through heat treatment. Background Technology

[0002] Laser bed melting (LPBF) technology offers unprecedented freedom in fabricating Fe-Ga alloy magnetostrictive components with complex internal cavities or intricate structures. However, the LPBF process introduces residual tensile stresses of up to hundreds of megapascals within the formed part due to localized rapid solidification and intense temperature cycling. While these residual stresses stabilize the non-equilibrium nano-L60 precipitates to some extent, they also act as strong pinning points, severely hindering the displacement and rotation of magnetic domain walls. This results in sluggish magnetostrictive response, low sensitivity, and a high driving field threshold under actual working magnetic fields (especially low magnetic fields), limiting its application in low-power, high-precision sensors and actuators.

[0003] To eliminate residual stress, the conventional approach is to perform high-temperature annealing. However, for LPBF-formed Fe-Ga alloys with metastable L60 phase and strong texture, traditional annealing faces a "triple contradiction":

[0004] 1. The contradiction between stress relief and texture preservation: Completely eliminating residual stress usually requires heating to near or above the recrystallization temperature (approximately 900 °C or higher), but this triggers the recrystallization process, causing the LPBF to form a strong texture. <100> The columnar crystal texture is replaced by randomly oriented equiaxed crystals, thus losing the magnetic property advantages brought by the texture.

[0005] 2. The contradiction between stress relief and phase stability: The nano-L60 phase is key to improving the magnetostriction coefficient of Fe-Ga alloys, but it has poor thermodynamic stability and begins to dissolve above approximately 500 °C. High-temperature treatments aimed at relieving stress can lead to a large or complete re-dissolution of the L60 phase, resulting in irreversible loss of magnetostriction capacity.

[0006] 3. The contradiction in performance orientation: pursuing a high saturation magnetostriction coefficient (λ) s The pursuit of high and low field sensitivity (dλ / dH@0-500Oe) is often at odds with the pursuit of low and high field sensitivity (dλ / dH@0-500Oe). The former requires strong texture and high L60 phase density, while the latter requires extremely low domain wall pinning (i.e., low residual stress). Existing heat treatment processes struggle to achieve an ideal balance between the two. Summary of the Invention

[0007] This invention aims to provide a heat treatment method for optimizing the magnetic properties of additively manufactured Fe-Ga alloys. It can perform non-equilibrium solid solution treatment within a specific temperature window to optimize the overall magnetostrictive properties of the alloy, especially significantly improving its low-field magnetostrictive response sensitivity. This solves the technical problem that traditional high-temperature annealing treatment of LPBF-formed Fe-Ga alloys cannot simultaneously achieve residual stress release, favorable texture retention, and metastable phase control.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A heat treatment method for optimizing the magnetic properties of additively manufactured Fe-Ga alloys includes the following steps:

[0010] S1. Place the Fe-Ga alloy parts formed by laser powder bed melting in a protective atmosphere or vacuum environment;

[0011] S2. Heat the alloy parts to a first heat treatment temperature T and hold them at temperature T for a time t; wherein, the first heat treatment temperature T satisfies: 720 °C ≤ T ≤ 800 °C; the holding time t satisfies: 0.5 hours ≤ t ≤ 2 hours;

[0012] S3. After the heat preservation is completed, the parts are rapidly cooled until room temperature; the cooling rate shall not be less than 50 °C / s.

[0013] Furthermore, in S1, the composition of the Fe-Ga alloy is Fe. 81 Ga 19 Furthermore, the Fe-Ga alloy exhibits properties along the construction direction formed by the LPBF process. <100> Texture; the protective atmosphere is argon or nitrogen.

[0014] Furthermore, in S2, the first heat treatment temperature T is 740 °C~760 °C.

[0015] Furthermore, the first heat treatment temperature T is 750 °C.

[0016] Furthermore, the heat preservation time t is 1 hour.

[0017] Furthermore, the rapid cooling method is water quenching.

[0018] Furthermore, after step S3, step S4 is also included: aging the rapidly cooled parts in a temperature range of 250 °C to 400 °C for 1 to 4 hours.

[0019] The Fe-Ga alloy products obtained by the above-described additive manufacturing Fe-Ga alloy magnetic property optimization heat treatment method retain the magnetic properties along the original construction direction. <100> Columnar crystal texture; the average geometrically required dislocation density of the Fe-Ga alloy product is less than 8.0 × 10⁻⁶. 13 m -2 The magnetostrictive strain response of the Fe-Ga alloy product in the low magnetic field range of 0-500 Oe is higher than that of the LPBF forming reference sample of the same composition and process without heat treatment.

[0020] Furthermore, the saturation magnetostrictive strain λ of the Fe-Ga alloy product parallel to the original construction direction... ∥ The magnetostriction sensitivity of Fe-Ga alloy products under low magnetic fields is more than twice that of the LPBF forming reference sample. The value is 130ppm~170ppm.

[0021] Furthermore, Fe-Ga alloy products are used as sensing or actuating elements in magnetostrictive sensors or microactuators.

[0022] The beneficial effects of the technical solution are:

[0023] 1. This invention proposes a novel heat treatment window and objective: Unlike traditional annealing objectives of "stress relief" or "complete recrystallization," this invention, for the first time, explicitly defines a short-time treatment within a specific mid-temperature range of 720-800 °C (especially 750 °C), with the objective of achieving a "non-equilibrium optimized state." Within this window, the thermal activation energy is sufficient to drive large-scale dislocation slip and rearrangement (stress relaxation), but insufficient to drive large-angle grain boundary migration and recrystallization nucleation (texture retention); simultaneously, this temperature is sufficient to partially dissolve the L60 phase, reducing its strong pinning to domain walls, but rapid cooling inhibits its complete dissolution and subsequent coarsening.

[0024] 2. This invention achieves precise control and optimization of performance: Alloys treated by the method of this invention exhibit a clear performance transformation: saturation magnetostrictive strain (λ) s The magnetostrictive response (MR) decreased moderately from an ultra-high level (>200 ppm) before processing to a still excellent level (~150 ppm), but its low-field (0-500 Oe) magnetostrictive response improved from near zero to a very significant level. This shift from "high output but high drive" to "moderate output but easy drive" is of crucial value for many practical applications, such as low-power sensors and precision micro-displacement platforms.

[0025] 3. The mechanism of this invention is clear and the effects are predictable: This method precisely regulates the degree of microstructure evolution by controlling the "degree" of temperature and time. Stress release improves domain wall mobility; the partially retained L60 phase and texture continue to contribute to magnetoelastic coupling anisotropy; and the partially dissolved L60 phase reduces local pinning strength. These three factors work together to open up the magnetization and strain output path under low field conditions.

[0026] 4. The process of this invention is simple and applicable to complex parts: This method is a single-step or two-step (solution + aging) heat treatment, which can be completed in a conventional heat treatment furnace. It is also applicable to LPBF near-net-shape parts with complex geometries, without the need for subsequent complex machining, and has good engineering applicability. Attached Figure Description

[0027] Figure 1 For Fe 81 Ga 19 SEM and EBSD analyses of the alloy after annealing at different temperatures; SEM images of the XZ plane of a, b, and c after annealing at 750 ℃, 950 ℃, and 1150 ℃, respectively; and the corresponding IPF color maps and IPF maps of a1, b1, and c1 after annealing at 750 ℃, 950 ℃, and 1150 ℃, respectively.

[0028] Figure 2 The recrystallization distribution and KAM distribution are shown for annealing at different temperatures; a, b, and c are recrystallization distribution and corresponding recrystallization fraction statistics after annealing at 750 ℃, 950 ℃, and 1150 ℃, respectively; d, e, and f are KAM distribution and corresponding statistical analysis after annealing at 750 ℃, 950 ℃, and 1150 ℃.

[0029] Figure 3 Fe at different annealing temperatures 81 Ga 19 TEM analysis of the alloy; a, b, and c represent LPBF samples at morphology, 750℃, and 1150℃, respectively, along the green areas in figures a1, b1, and c1. <100> TEM bright-field image and selected area electron diffraction pattern of the region axis; high-resolution TEM images of a2, b2, and c2 and corresponding Fourier analysis; geometric phase analysis of a3, b3, and c3 corresponding to a2, b2, and c2.

[0030] Figure 4 Fe under different heat treatment conditions 81 Ga 19 The magnetostrictive properties; (a) along parallel (λ) ‖ ) and vertical (λ) ⊥ (a) Magnetostriction curve measured in direction, (b) Definition of λ ‖ and λ⊥ (c) Schematic diagram of measurement, magnified view of magnetostrictive response in low field range (λ@0-500 Oe), (d) first derivative of parallel magnetostriction (dλ) ‖ / dH), highlighting the difference in sensitivity. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments:

[0032] Currently, the conventional approach to eliminate residual stress is high-temperature annealing. However, for LPBF-formed Fe-Ga alloys with metastable L60 phase and strong texture, traditional annealing faces a triple challenge:

[0033] 1. The contradiction between stress relief and texture preservation: Completely eliminating residual stress usually requires heating to near or above the recrystallization temperature (approximately 900 °C or higher), but this triggers the recrystallization process, causing the LPBF to form a strong texture. <100> The columnar crystal texture is replaced by randomly oriented equiaxed crystals, thus losing the magnetic property advantages brought by the texture.

[0034] 2. The contradiction between stress relief and phase stability: The nano-L60 phase is key to improving the magnetostriction coefficient of Fe-Ga alloys, but it has poor thermodynamic stability and begins to dissolve above approximately 500 °C. High-temperature treatments aimed at relieving stress can lead to a large or complete re-dissolution of the L60 phase, resulting in irreversible loss of magnetostriction capacity.

[0035] 3. The contradiction in performance orientation: pursuing a high saturation magnetostriction coefficient (λ) s The pursuit of high and low field sensitivity (dλ / dH@0-500 Oe) is often at odds with the pursuit of low and high field sensitivity (dλ / dH@0-500 Oe). The former requires strong texture and high L60 phase density, while the latter requires extremely low domain wall pinning (i.e., low residual stress). Existing heat treatment processes struggle to achieve an ideal balance between the two.

[0036] Therefore, this invention proposes a "non-equilibrium intermediate-temperature solution treatment" technique. The core idea is to perform short-term heat treatment in an intermediate-temperature range that is significantly higher than the dissolution temperature of the L60 phase but much lower than the large-scale recrystallization temperature of the LPBF state structure, followed by rapid cooling. This can effectively reduce residual stress while preserving favorable texture to the maximum extent and controlling the evolution of the L60 phase. It achieves a dynamic, non-equilibrium optimized state in the three dimensions of "stress-texture-phase transformation", thereby obtaining the best comprehensive magnetostrictive properties that combine good low-field sensitivity and moderate saturation strain.

[0037] A heat treatment method for optimizing the magnetic properties of Fe-Ga alloys, the composition of which is Fe... 81 Ga 19Furthermore, the Fe-Ga alloy exhibits properties along the construction direction formed by the LPBF process. <100> Texture, including the following steps:

[0038] S1. The Fe-Ga alloy parts formed by laser powder bed melting are placed in a protective atmosphere or vacuum environment; wherein the protective atmosphere is argon or nitrogen.

[0039] S2. Heat the alloy part to a first heat treatment temperature T and hold it at temperature T for a time t; wherein, the first heat treatment temperature T satisfies: 720 °C ≤ T ≤ 800 °C, in this invention, a more preferred first heat treatment temperature T is 740 °C~760 °C, and the most preferred first heat treatment temperature T is 750 °C; the holding time t satisfies: 0.5 hours ≤ t ≤ 2 hours, and a more preferred holding time t is 1 hour;

[0040] The combination of the first heat treatment temperature T and time t enables the Fe-Ga alloy to simultaneously achieve: (i) a reduction in residual stress level of at least 30% compared to before treatment; (ii) <100> The strength retention rate of the texture is not less than 80% of that before treatment; (iii) the nano-L60 ordered precipitates in the alloy undergo partial re-dissolution, but their number density is not less than 30% of that before treatment.

[0041] S3. After the heat preservation is completed, the parts are subjected to water quenching and cooling until room temperature; the cooling rate shall not be less than 50 °C / s.

[0042] After step S3, step S4 may also be included: aging the rapidly cooled parts in a temperature range of 250 °C to 400 °C for 1 to 4 hours.

[0043] The additively manufactured Fe-Ga alloy products obtained by the above method retain a clear orientation along the original structure. <100> Columnar crystal texture; the average geometrically required dislocation density of this product is less than 8.0 × 10⁻⁶. 13 m -2 The magnetostrictive strain response of this product in a low magnetic field range of 0-500 Oe is significantly higher than that of the untreated LPBF-formed reference sample of the same composition and process. Specifically, the magnetostrictive sensitivity of this product under a low magnetic field (e.g., 200 Oe) is more than twice that of the reference sample. Furthermore, the saturation magnetostrictive strain λ of this product parallel to the original construction direction... ∥ The values ​​range from 130 ppm to 170 ppm.

[0044] The processing method of this invention can be directly used as the final or intermediate heat treatment process for LPBF-formed Fe-Ga alloy magnetostrictive parts. It is particularly suitable for manufacturing devices that require low operating magnetic fields, high sensitivity, and fast response. The Fe-Ga alloy product can be used as a sensing or driving element to prepare magnetostrictive sensors or microactuators, such as micro-displacement sensors, vibration detection probes, active vibration damping system actuators, microfluidic valves, etc.

[0045] The present invention will be described in detail below with reference to Examples 1-2 and Comparative Examples 1-4. The LPBF used to form Fe... 81 Ga 19 All alloy reference samples were prepared using the same process (including in-situ remelting) and possess strong... <100> / / BD texture and high-density nano-L60 phase, its initial λ ∥ It is approximately 212 ppm, with a near-zero response at low fields (<500 Oe).

[0046] Example 1

[0047] S1. Pretreatment: Pretreatment of Fe formed by LPBF. 81 Ga 19 The alloy sample (10×3×12 mm) was vacuum sealed in a quartz tube (with a small amount of argon gas left in the tube).

[0048] S2. Heat treatment: Place the sealed sample into a box furnace and heat it to 750 °C at a rate of 10 °C / min, and hold it at that temperature for 1 hour.

[0049] S3. Cooling: After the heat preservation is completed, the quartz tube is quickly removed and quenched in room temperature water to achieve rapid cooling (water quenching).

[0050] Organization and performance analysis:

[0051] From the perspective of stress state, the KAM analysis of EBSD is as follows: Figure 2 As shown, the average GND density of the treated sample decreased from approximately 11.6 × 10⁻⁶ before treatment. 13 m -2 Significantly reduced to approximately 7.0 × 10⁻⁶ 13 m -2 This indicates that residual stress has been effectively released (reduced by approximately 40%). The KAM diagram shows a more uniform distribution and a reduction in high-strain regions.

[0052] From the perspective of texture evolution, such as Figure 1 The EBSD IPF plot shows a clear columnar crystal morphology and strong... <100> / / The BD texture was well preserved, and no obvious equiaxed recrystallized grains were observed. Calculation <100> The area fraction retention rate of oriented grains reaches over 85%;

[0053] From the perspective of phase evolution, such as Figure 3 As shown, TEM / SAED analysis indicates that the intensity of the L60 superlattice spots in the

[100] zone axis diffraction is significantly reduced but not completely disappeared, indicating that the L60 phase has undergone partial re-dissolution, and the estimated number density is retained at about 40-50%.

[0054] From the perspective of magnetostrictive properties: such as Figure 4 As shown by the curve, the saturation magnetostrictive strain λ ∥ The magnetostrictive response decreased from 212 ppm to 146 ppm. However, in the low-field range of 0-500 Oe, the magnetostrictive response improved from near 0 ppm to a clear upward curve. The magnetostrictive strain value at 500 Oe (λ@0-500 Oe) increased by more than 10 times compared to before treatment, demonstrating a qualitative leap in low-field sensitivity.

[0055] Example 2 (solution treatment + aging)

[0056] Based on Example 1, this embodiment further aging the sample after water quenching at 750 °C for 1 h in a vacuum furnace at 300 °C for 2 hours, followed by air cooling.

[0057] Results: Aging treatment induced the re-precipitation of finer L60 phases. Compared with the sample treated only by solution treatment, λ ∥ The saturation strain was reduced from 146 ppm to approximately 160 ppm, while the low-field sensitivity remained significantly higher than that of the untreated reference sample. This represents a further optimization of the balance between saturated strain and low-field sensitivity.

[0058] Comparative Example 1 (High-Temperature Full Annealing)

[0059] The reference sample was annealed at 1150 °C for 2 hours, followed by water quenching.

[0060] result: Figure 1 EBSD analysis showed complete recrystallization, forming equiaxed crystals. <100> Texture is completely lost, and orientation becomes randomized. The L60 phase is completely dissolved in the matrix. Figure 4 As shown by the curve, λ ∥ It further decreased to about 100 ppm (close to the level of ordinary untextured polycrystalline materials), and although the low-field response was improved, the absolute value was very low, resulting in the worst overall performance.

[0061] Comparative Example 2 (Low-Temperature Stress-Relief Annealing)

[0062] The reference sample was annealed at 550 °C for 2 hours, followed by furnace cooling.

[0063] Results: Residual stress release was limited (GND density decreased by approximately 15%). The L60 phase remained largely undissolved. Magnetostrictive properties showed little change compared to the reference sample, and the low-field response remained poor. This indicates that insufficient temperature is insufficient to effectively relieve domain wall pinning.

[0064] Comparative Example 3 (within the window of this invention but taking too long)

[0065] The reference sample was annealed at 770 °C for 4 hours, followed by water quenching.

[0066] Results: A small number of recrystallized grains were observed to nucleate at columnar grain boundaries. <100> Texture strength begins to decrease (retention rate approximately 70%). The L60 phase dissolves more completely. In terms of performance, λ... ∥ The concentration decreased to ~120 ppm, and the improvement in low-field sensitivity was not as significant as in Example 1. This indicates that excessively long heat treatment times begin to damage the texture, deviating from the optimal balance point.

[0067] Comparative Example 4 (Partial Recrystallization Annealing)

[0068] The reference sample was annealed at 950 °C for 2 hours, followed by water quenching.

[0069] result: Figure 1 EBSD analysis showed partial recrystallization, resulting in recrystallized grains. <100> Texture strength is weakened. The L60 phase is completely dissolved in the matrix. For example... Figure 4 As shown by the curve, λ ∥ It drops to approximately 133 ppm, with a low-field response second only to the window of this invention.

[0070] Experimental data analysis

[0071] Figure 4 The effects of different heat treatment temperatures (holding for 1 hour) on two key performance indicators of the alloy are comprehensively demonstrated. It can be seen that within the temperature window of 720-800 °C (especially near 750 °C), although the saturated strain λ... ∥ While the peak value decreases, the low-field strain value (λ@0-500 Oe) reaches a peak, indicating that this window is the "critical point" for optimizing low-field driven performance. Too low a temperature (e.g., 550 °C) results in insufficient stress release and poor low-field response; too high a temperature (>850 °C) severely damages texture and precipitates, deteriorating both performance indicators.

[0072] In summary, this invention proposes a novel heat treatment window and objective: unlike the traditional annealing objectives of "stress relief" or "complete recrystallization," this invention, for the first time, explicitly defines a short-time treatment within a specific mid-temperature range of 720-800 °C (especially 750 °C), with the objective of achieving a "non-equilibrium optimized state." Within this window, the thermal activation energy is sufficient to drive large-scale dislocation slip and rearrangement (stress relaxation), but insufficient to drive large-angle grain boundary migration and recrystallization nucleation (texture retention); simultaneously, this temperature is sufficient to partially dissolve the L60 phase, reducing its strong pinning to domain walls, but rapid cooling inhibits its complete dissolution and subsequent coarsening.

[0073] This invention achieves precise control and optimization of performance: alloys treated by the method of this invention exhibit a clear property transformation: saturation magnetostrictive strain (λ) s The magnetostrictive response (MR) decreased moderately from an ultra-high level (>200 ppm) before processing to a still excellent level (~150 ppm), but its low-field (0-500 Oe) magnetostrictive response improved from near zero to a very significant level. This shift from "high output but high drive" to "moderate output but easy drive" is of crucial value for many practical applications, such as low-power sensors and precision micro-displacement platforms.

[0074] The mechanism of this invention is clear, and its effects are predictable: This method precisely regulates the degree of microstructure evolution by controlling the "degree" of temperature and time. Stress release improves domain wall mobility; the partially retained L60 phase and texture continue to contribute to magnetoelastic coupling anisotropy; and the partially dissolved L60 phase reduces local pinning strength. These three factors work together to open up the magnetization and strain output pathway under low-field conditions.

[0075] The present invention has a simple process and is suitable for complex parts: the method is a single-step or two-step (solution + aging) heat treatment, which can be completed in a conventional heat treatment furnace, and is suitable for LPBF near-net-shape parts with complex geometries. No subsequent complex machining is required, and it has good engineering applicability.

[0076] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific technical solutions or characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A heat treatment method for optimizing the magnetic properties of additively manufactured Fe-Ga alloys, characterized in that, Includes the following steps: S1. Place the Fe-Ga alloy parts formed by laser powder bed melting in a protective atmosphere or vacuum environment; S2. Heat the alloy parts to a first heat treatment temperature T and hold them at temperature T for a time t; wherein, the first heat treatment temperature T satisfies: 720 °C ≤ T ≤ 800 °C; the holding time t satisfies: 0.5 hours ≤ t ≤ 2 hours; S3. After the heat preservation is completed, the parts are rapidly cooled until room temperature; the cooling rate shall not be less than 50 °C / s.

2. The heat treatment method for optimizing the magnetic properties of additively manufactured Fe-Ga alloys according to claim 1, characterized in that: In S1, the composition of the Fe-Ga alloy is Fe. 81 Ga 19 Furthermore, the Fe-Ga alloy exhibits properties along the construction direction formed by the LPBF process. <100> Texture; the protective atmosphere is argon or nitrogen.

3. The heat treatment method for optimizing the magnetic properties of additively manufactured Fe-Ga alloys according to claim 1, characterized in that: In S2, the first heat treatment temperature T is 740 °C~760 °C.

4. The heat treatment method for optimizing the magnetic properties of additively manufactured Fe-Ga alloys according to claim 3, characterized in that: The first heat treatment temperature T is 750 °C.

5. The heat treatment method for optimizing the magnetic properties of additively manufactured Fe-Ga alloys according to claim 1, characterized in that: The heat preservation time t is 1 hour.

6. The heat treatment method for optimizing the magnetic properties of additively manufactured Fe-Ga alloys according to claim 1, characterized in that: The rapid cooling method is water quenching.

7. The heat treatment method for optimizing the magnetic properties of additively manufactured Fe-Ga alloys according to claim 1, characterized in that: After step S3, step S4 is also included: aging the rapidly cooled parts in a temperature range of 250 °C to 400 °C for 1 to 4 hours.

8. The Fe-Ga alloy product obtained by the magnetic property optimization heat treatment method for additive manufacturing of Fe-Ga alloys according to claim 1, characterized in that: Fe-Ga alloy products retain the original structural orientation. <100> Columnar crystal texture; the average geometrically required dislocation density of the Fe-Ga alloy product is less than 8.0 × 10⁻⁶. 13 m -2 The magnetostrictive strain response of the Fe-Ga alloy product in the low magnetic field range of 0-500 Oe is higher than that of the LPBF forming reference sample of the same composition and process without heat treatment.

9. The Fe-Ga alloy product obtained by the magnetic property optimization heat treatment method for additive manufacturing of Fe-Ga alloys according to claim 8, characterized in that: The saturation magnetostrictive strain λ of the Fe-Ga alloy product parallel to the original construction direction ∥ The magnetostriction sensitivity of Fe-Ga alloy products under low magnetic fields is more than twice that of the LPBF forming reference sample, ranging from 130 ppm to 170 ppm.

10. The application of the Fe-Ga alloy product according to any one of claims 8-9, characterized in that: Fe-Ga alloy products are used as sensing or actuating elements in magnetostrictive sensors or microactuators.

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