A corrosion-resistant magnetic temperature compensation alloy and its preparation method

Abstract

The present invention discloses a corrosion-resistant magnetic temperature compensation alloy and a preparation method thereof, belonging to the field of soft magnetic materials. The alloy is composed, by atomic percentage, of Ni 32-38%, Co 0.8-1%, Cr 1-2%, Mn 0.8-1%, Si 0.8-1.2%, Al 1-2%, Ti 0.4-0.8%, La 0.1-0.5%, B 0.1-0.2%, and the remainder Fe and impurities. Al, Ti, La, and B are added in the form of pre-alloyed AlTiLaB alloy powder. The magnetic temperature compensation alloy is prepared by smelting, refining, adding AlTiLaB alloy powder, ultrasonic casting, and heat treatment. The alloy improves corrosion resistance, enhances magnetization intensity, and reduces coercive force through the synergistic effect of multiple elements. It is suitable for high-power electromagnetic equipment in complex corrosive environments and has good performance stability and consistency.

Description

Technical Field

[0001] The present invention relates to the field of soft magnetic materials, in particular to a corrosion-resistant magnetic temperature compensation alloy and a preparation method thereof. Background Art

[0002] Magnetic temperature compensation alloys are a class of functional materials with excellent soft magnetic properties. Their core advantage lies in their ability to rapidly magnetize in low applied magnetic fields and rapidly demagnetize after the field is removed. Their high permeability and low coercivity make these alloys key components of electromagnetic devices in industries such as power, communications, automotive, and manufacturing. For example, in transformers, their performance directly impacts energy conversion efficiency; in sensors, their magnetic response speed determines detection accuracy. Therefore, magnetic temperature compensation alloys are crucial to improving overall device performance.

[0003] However, traditional magnetic temperature compensation alloys (such as iron-nickel alloys and iron-silicon alloys) have gradually shown limitations in practical applications:

[0004] (1) Insufficient magnetic performance: In devices that require high magnetic field strength, such as high-power transformers and high-performance motors, the magnetization intensity and saturation magnetic induction intensity of traditional alloys have limited room for improvement, resulting in a bottleneck in the power output and efficiency of the equipment;

[0005] (2) Poor corrosion resistance: In an environment containing corrosive media such as acid, alkali, and salt spray, traditional alloys are prone to oxidation or corrosion, resulting in a decrease in magnetic properties and a shortened service life, which in turn increases the maintenance cost and replacement frequency of the equipment.

[0006] In the prior art, some patents attempt to improve soft magnetic properties through multi-element alloy design. For example, patent CN114242370A discloses a FeCoSiM soft magnetic alloy with an atomic percentage composition of: Fe 68-78at%, Co 4-12at%, Si 14-18at%, and M (one or more of V, Cr, and Ni) 0-4at%. This solution aims to enhance magnetic coupling by adding Co and optimize the magnetostriction coefficient by adding V / Cr / Ni elements. However, this solution has significant drawbacks: the high addition of Co (4-12at%) increases the alloy's brittleness; at the same time, its composition is not specifically optimized for corrosion resistance, making the alloy susceptible to oxidation in humid or high-temperature environments and lacking long-term stability.

[0007] Therefore, the development of new magnetic temperature compensation alloys with both high magnetic properties (high saturation magnetization and low coercive force) and excellent corrosion resistance has become a key direction to break through the existing technological bottleneck. Summary of the Invention

[0008] In order to address the deficiencies in the prior art, the present invention provides a corrosion-resistant magnetic temperature compensation alloy and a preparation method thereof, to achieve the following goals: improving corrosion resistance to adapt to complex corrosive environments; enhancing magnetization strength and reducing coercive force to meet the requirements of high-power equipment; and optimizing the preparation process to ensure alloy performance stability and consistency.

[0009] In order to achieve the above object, the specific scheme adopted by the present invention is:

[0010] In one aspect, the present invention discloses a corrosion-resistant magnetic temperature compensation alloy composed of the following elements in atomic percentages:

[0011] Ni 32~38%, Co 0.8~1%, Cr 1~2%, Mn 0.8~1%, Si 0.8~1.2%, Al 1~2%, Ti 0.4~0.8%, La 0.1~0.5%, B 0.1~0.2%, and the balance is Fe and inevitable impurities.

[0012] Furthermore, Al, Ti, La and B elements are added in the form of pre-alloyed AlTiLaB alloy powder during the alloy smelting process, and the particle size of the AlTiLaB alloy powder is 100-500 nm.

[0013] Furthermore, the AlTiLaB alloy powder is prepared by the following steps:

[0014] (1) Weigh Al, Ti, La, and B elemental raw materials according to atomic percentage, place them in a ball mill, and mix them evenly under the protection of inert gas to obtain a mixed powder;

[0015] (2) Pressing the mixed powder into a prefabricated block, then placing the prefabricated block in a vacuum melting furnace for vacuum melting and keeping the temperature for 30 minutes to obtain a molten alloy;

[0016] (3) Using high-pressure argon as the atomizing gas, the alloy liquid is atomized by ultrasonic atomization process to obtain powder;

[0017] (4) The powder is sieved to obtain AlTiLaB alloy powder of target particle size.

[0018] In another aspect, the present invention discloses a method for preparing a corrosion-resistant magnetic temperature compensation alloy, comprising the following steps:

[0019] Step 1: Alloy smelting: Weigh pure Fe, pure Ni, pure Co, pure Cr, pure Mn and pure Si raw materials according to atomic percentage, place them in a vacuum induction furnace for smelting, and the vacuum degree reaches 10 -3 ~10 -5Pa, melting temperature 1500~1550℃, stirring during the melting process, while introducing protective gas to obtain a melt;

[0020] Step 2, refining: keeping the melt obtained in step 1 at the melting temperature for 10-30 minutes;

[0021] Step 3: Add AlTiLaB alloy powder: Add AlTiLaB alloy powder to the refined melt and stir at 1500-1520°C for 3-5 minutes;

[0022] Step 4, ultrasonic casting: cool the melt treated in step 3 to 1400-1500°C and pour it into a mold. After the pouring is completed, ultrasonic vibration is immediately applied to the mold. After the vibration is completed, it is naturally cooled for 1-2 hours and demolded to obtain an ingot.

[0023] Step 5: Heat treatment: The ingot is subjected to homogenization annealing at 1100-1200° C. for 2-3 hours, and then slowly cooled to room temperature to obtain a corrosion-resistant magnetic temperature compensation alloy.

[0024] Furthermore, in step 1, the protective gas is argon with a flow rate of 1-3 L / min; the stirring is performed by electromagnetic stirring with a frequency of 15-25 Hz.

[0025] Furthermore, in step 4, the ultrasonic vibration frequency is 3 kHz, and the vibration duration is 5 to 10 minutes.

[0026] Furthermore, in step five, after annealing, the material is cooled to room temperature at a rate of ≤5°C / min.

[0027] In the present invention, the advantages and mechanism of adding Al, Ti, La, and B elements through pre-alloyed AlTiLaB alloy powder: In traditional methods, Al, Ti, La, and B elements are usually added separately, which is prone to segregation due to differences in melting points and diffusion rates. Pre-alloyed powder can solve this problem through the following mechanism:

[0028] (1) Inhibition of element segregation: The pre-alloyed AlTiLaB alloy powder is a uniform alloy phase. Each element has formed a stable chemical bond (such as Al-Ti bond, La-B bond). When it is melted / dissolved in the melt, it will not separate due to the difference in melting point. It can avoid the problem of Ti (high melting point) aggregation and Al (low melting point) preferential melting / diffusion when added alone, and ensure uniform distribution of elements.

[0029] (2) Enhanced refinement effect: Nano-scale (100-500 nm) pre-alloyed powder has a larger specific surface area and higher surface energy than traditional micron-scale single-element particles. It can serve as more heterogeneous nucleation cores in the melt, significantly refining the grains, while fine grains can reduce coercivity.

[0030] (3) Improve synergistic efficiency: Pre-alloying allows Al, Ti, La, and B to form a preliminary synergistic structure in the powder (such as TiB2 core wrapping Al and La atoms). After being added to the melt, they can directly play a role (such as TiB2 immediately acts as a refining phase, and Al quickly diffuses to the surface to form an oxide film). There is no need for re-nucleation, and the efficiency is better than adding them separately.

[0031] (4) Reduce oxidation loss: The pre-alloyed powder is ball-milled and stored in an inert gas, and a dense oxide film (Al2O3) is formed on the surface, which can prevent it from reacting with oxygen in the melt during the smelting process (Al added alone is easily oxidized to form Al2O3 inclusions), thereby reducing element loss.

[0032] Beneficial effects:

[0033] (1) Significantly Improved Corrosion Resistance: The present invention constructs a corrosion-resistant system of "composite oxide film-grain boundary purification-microstructure refinement" through the synergistic action of multiple elements: Cr and Al form a Cr2O3-Al2O3 composite oxide film, which enhances the barrier ability to corrosive media; La purifies the grain boundaries, reducing corrosion sources and lowering the risk of intergranular corrosion; and refined grains increase the adhesion area of ​​the oxide film, improving the bonding strength between the corrosion layer and the substrate. Electrochemical testing (3.5wt% NaCl solution) shows that the linear polarization resistance of the embodiment is significantly improved compared to the comparative example, the corrosion current is significantly reduced, and the corrosion potential is more positive, indicating that it has superior stability in corrosive environments.

[0034] (2) Optimization of magnetic performance

[0035] High magnetization intensity: The magnetic coupling effect of Co and the high spin order of Ni-Fe solid solution synergize to make the magnetization intensity of the alloy obtained by the present invention higher than that of the comparative example, which can meet the requirements of high-power equipment for strong magnetic fields;

[0036] Low coercivity: Si reduces the magnetostriction coefficient and grain refinement reduces domain wall resistance, making the coercivity of the alloy obtained by the present invention better than that of the comparative example. This ensures that the alloy can be quickly magnetized / demagnetized under low external magnetic fields, thereby improving the response speed of the device.

[0037] (3) Performance stability and extended service life: Pre-alloyed powder and ultrasonic vibration ensure uniform alloy composition, and homogenization annealing reduces internal stress, making the magnetic properties of the alloy less volatile within a wider temperature range and more stable. At the same time, excellent corrosion resistance reduces performance degradation caused by corrosion, significantly extending the service life of the alloy in complex environments, and reducing equipment maintenance costs and replacement frequency.

[0038] (4) Comprehensive improvement brought by process optimization: The AlTiLaB alloy powder prepared by ultrasonic atomization has no element segregation and fine grains. Combining it with the ultrasonic vibration casting process can not only further refine the alloy grains, but also reduce defects such as pores, thereby improving the consistency and stability of the alloy structure as a whole, providing a reliable guarantee for the realization of excellent performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is the microstructure diagram of the alloy obtained in Example 1 after electrochemical corrosion.

[0040] Figure 2 This is a three-dimensional contour diagram of the alloy obtained in Example 1 after electrochemical corrosion. DETAILED DESCRIPTION

[0041] The technical solutions of the present invention are described clearly and completely below with reference to specific embodiments. The embodiments described are only a part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative work are within the scope of protection of the present invention.

[0042] On the one hand, the present invention discloses a corrosion-resistant magnetic temperature compensation alloy, which is composed of the following elements in atomic percentage (at%): Ni 32~38%, Co 0.8~1%, Cr 1~2%, Mn 0.8~1%, Si 0.8~1.2%, Al 1~2%, Ti0.4~0.8%, La 0.1~0.5%, B 0.1~0.2%, and the balance is Fe and inevitable impurities.

[0043] The role of each element is explained below.

[0044] (1) Ni (32~38at%): As the core element of soft magnetic alloy, Ni forms a face-centered cubic (fcc) solid solution with Fe. This structure has low magnetocrystalline anisotropy (the magnetocrystalline anisotropy constant K1 is close to zero), which can significantly reduce the resistance to the movement of magnetic domain walls, thereby increasing the magnetic permeability and reducing the coercive force. At the same time, Ni can improve the plasticity of the alloy and improve the processing performance. When the Ni content is 32~38at%, the solid solution structure formed with Fe is stable, and the magnetic permeability can reach 10 4 ~10 5The coercive force can be controlled below 2A / m. If the Ni content is less than 32at%, the alloy tends to form a body-centered cubic (bcc) structure, which increases the magnetocrystalline anisotropy, leading to an increase in coercive force and a decrease in magnetic permeability. If the Ni content is greater than 38at%, not only will the raw material cost increase significantly, but the saturation magnetization of Ni (about 480kA / m) is also lower than that of Fe (about 1710kA / m), resulting in a decrease in the overall saturation magnetization of the alloy.

[0045] (2) Co (0.8~1at%): Co is a typical ferromagnetic element. Its 3d electron layer has unpaired electrons, which can form a strong magnetic exchange coupling with the 3d electrons of Fe and Ni, enhancing the spin order of the alloy and thus increasing the saturation magnetization. A low concentration of Co of 0.8~1at% can significantly enhance the magnetic coupling effect, making the saturation magnetization of the alloy significantly higher than that of traditional iron-nickel alloys, while avoiding the brittleness problem caused by high Co content (the atomic radius of Co is significantly different from that of Fe. High concentration addition will cause lattice distortion, increase the resistance to dislocation movement, and lead to increased brittleness of the alloy). If the Co content is <0.8at%, the magnetic coupling enhancement effect is not obvious and the magnetization strength is limited; if the Co content is >1at%, the lattice distortion is aggravated, which will lead to a decrease in the elongation of the alloy and deterioration of the processing performance.

[0046] (3) Cr (1~2at%): Cr is a key element to improve corrosion resistance. It easily forms a dense Cr2O3 oxide film (thickness of about 5~10nm) on the surface of the alloy. The oxide film has excellent chemical stability and can isolate water, oxygen and corrosive media (such as Cl - ) contact with the substrate, inhibiting the anodic reaction of electrochemical corrosion (such as Fe→Fe 2+ +2e - A Cr content of 1-2 at% ensures the formation of a continuous, dense Cr2O3 film, achieving a linear polarization resistance (a key indicator of corrosion resistance) exceeding 3000Ω. If the Cr content is less than 1 at%, the oxide film becomes discontinuous and porous, allowing corrosive media to easily penetrate the substrate through these pores, leading to localized corrosion (such as pitting). If the Cr content is greater than 2 at%, Cr forms a Cr-Fe intermetallic compound with Fe, increasing magnetocrystalline anisotropy and leading to an increase in coercivity.

[0047] (4) Mn (0.8~1at%): Mn is a strong deoxidizer. Its affinity with oxygen (△G°≈-363kJ / mol) is higher than that of Fe (△G°≈-244kJ / mol). It can preferentially combine with oxygen in the melt to form MnO (melting point 1650℃). The density of MnO is 5.43g / cm 3 ) is lower than the alloy melt (about 7g / cm 3), which floats to the melt surface to form slag, thereby reducing the oxygen content in the alloy. Mn also improves melt fluidity and reduces porosity caused by insufficient gas escape during casting. If the Mn content is less than 0.8at%, deoxidation is inadequate, and oxide inclusions such as FeO remain in the alloy. These inclusions act as pinning points for magnetic domain walls, reducing magnetic permeability. If the Mn content is greater than 1at%, it is likely to form MnS inclusions (melting point 1610°C) with S. MnS is a hard and brittle phase, which reduces the alloy's impact toughness.

[0048] (5) Si (0.8-1.2 at%): Si can significantly refine alloy grains (Si atoms have a small radius and tend to segregate at grain boundaries, inhibiting grain growth). Smaller grains can shorten the movement distance of magnetic domain walls and reduce coercivity. At the same time, Si can reduce the saturation magnetostriction coefficient of the alloy. When the saturation magnetostriction coefficient approaches zero, the interference of magnetostrictive stress under the action of an external magnetic field on the magnetic domain arrangement is reduced, further improving the magnetic permeability. If the Si content is less than 0.8 at%, the grain refinement and magnetostriction coefficient reduction effects are insufficient, and the coercivity will increase. If the Si content is greater than 1.2 at%, Si will form Fe3Si intermetallic compounds (hard and brittle phases) with Fe, resulting in increased hardness and decreased plasticity of the alloy, making it prone to cracking during cold rolling.

[0049] (6) Al (1-2 at%): Al and Cr work together to form a Cr2O3-Al2O3 composite oxide film on the alloy surface. Al2O3 has better chemical stability (does not dissolve in media with a pH of 2-12) than Cr2O3, which can enhance the acid and alkali resistance of the oxide film. At the same time, the thermal expansion coefficient of Al2O3 (about 7×10 -6 / ℃) and alloy matrix (about 11×10 -6 / °C), reducing oxide film cracking caused by temperature fluctuations and improving the adhesion between the corrosion layer and the substrate. 1-2 at% Al can achieve a composite oxide film thickness of 15-20 nm, with significantly higher density than a single Cr2O3 film. If the Al content is less than 1 at%, the Al2O3 content in the composite oxide film is insufficient, resulting in limited improvement in acid and alkali resistance. If the Al content is greater than 2 at%, an AlFe3 intermetallic compound forms, which is paramagnetic and reduces the overall magnetization of the alloy.

[0050] (7) Ti (0.4~0.8at%): Ti is a strong carbide and nitride forming element. It can combine with C and N in the alloy to form TiC and TiN (melting points > 3000℃). These fine particles can pin the grain boundaries and inhibit the coarsening of grains during high temperature treatment (such as annealing). At the same time, Ti can form TiB2 phase with B. TiB2 has a high hardness (about 34GPa), which can enhance the grain boundary strength and improve the high temperature stability of the alloy. If the Ti content is less than 0.4at%, the amount of TiC, TiN and TiB2 phases is insufficient, and the grain refinement effect is not obvious. If the Ti content is greater than 0.8at%, the excess Ti will form Fe2Ti intermetallic compound with Fe. This phase is a brittle phase and will lead to a decrease in the bending strength of the alloy.

[0051] (8) La (0.1-0.5 at%): As a rare earth element, La has strong surface activity and tends to segregate at grain boundaries. It can adsorb harmful impurities such as S and P at the grain boundaries (forming stable compounds such as La2S3 and LaP), thereby purifying the grain boundaries. At the same time, La can reduce the interfacial energy between the oxide film and the substrate, promote the uniform growth of the oxide film along the grain boundaries, and prevent the oxide film from peeling off due to interfacial stress concentration. If the La content is less than 0.1 at%, the effect of purifying the grain boundaries and enhancing the adhesion of the oxide film is insufficient. If the La content is greater than 0.5 at%, excessive La will form coarse La-rich phases at the grain boundaries. These phases are non-magnetic phases that hinder the movement of magnetic domain walls, resulting in a decrease in magnetic permeability.

[0052] (9) B (0.1-0.2 at%): B has a small atomic radius (about 0.082 nm) and tends to segregate at grain boundaries, which can reduce grain boundary energy and inhibit grain boundary migration, thereby refining the grains. At the same time, the TiB2 phase formed by B and Ti has a high melting point and chemical stability, and can serve as a heterogeneous nucleation core to promote grain refinement during solidification. If the B content is <0.1 at%, the grain refinement effect is limited; if the B content is >0.2 at%, the excess B will be enriched at the grain boundaries, resulting in increased grain boundary brittleness and decreased impact toughness of the alloy.

[0053] (10) Fe (balance): As a matrix element, Fe provides basic ferromagnetism (the 3d orbit of Fe atoms has 4 unpaired electrons and has a high saturation magnetization intensity), and is the main source of alloy magnetism; at the same time, Fe constitutes the skeleton of the alloy, ensuring that the alloy has a certain mechanical strength.

[0054] On the other hand, the present invention discloses a method for preparing a corrosion-resistant magnetic temperature compensation alloy, which mainly comprises the following steps:

[0055] Step 1: Preparation of AlTiLaB alloy powder

[0056] Al, Ti, La, and B are placed in a ball mill in proportion and ball milled at 150 rpm for 3 hours under inert gas protection to mix uniformly. The mixture is then poured into a mold and pressed into a prefabricated block. The prefabricated block is then placed in a vacuum melting furnace for vacuum melting and kept warm for 30 minutes to obtain an alloy liquid. The alloy liquid is atomized using an ultrasonic atomization process with high-pressure argon as the atomizing gas to obtain a powder. The powder is sieved to obtain an AlTiLaB alloy powder with a particle size of 100-500 nm.

[0057] The purpose of this step: During the ball milling process, mechanical force causes the raw material particles to undergo plastic deformation, break and weld together, achieving preliminary mixing of elements. Inert gas protection can prevent the raw materials from oxidation. Vacuum melting can eliminate gas impurities (such as H2, O2) in the raw materials to ensure powder purity. In ultrasonic atomization, high-frequency ultrasound (such as 30kHz) breaks the alloy liquid into fine droplets, and the droplets are rapidly cooled in high-pressure argon gas (cooling rate > 10 5 ℃ / s), which can inhibit element segregation and form nano-scale powders (100~500nm) with uniform composition. The large specific surface area of ​​nano-powders can enhance their dispersibility in the melt;

[0058] Step 2: Alloy melting

[0059] Weigh pure Fe, pure Ni, pure Co, pure Cr, pure Mn and pure Si raw materials according to atomic percentage, add them into vacuum induction furnace, and evacuate to 10 -3 ~10 -5 Pa, and the temperature is raised to 1500~1550℃. During the smelting process, the alloy melt is fully mixed by electromagnetic stirring to ensure uniform composition. At the same time, a small amount of argon (1~3L / min) is introduced into the furnace as a protective gas;

[0060] The function of this step: high vacuum (10 -3 ~10 -5 Pa) can remove gases such as oxygen and nitrogen from the furnace to prevent raw material oxidation (such as Fe oxidation to form FeO) and the formation of nitride inclusions (such as CrN); a temperature of 1500-1550°C ensures that all raw materials are fully dissolved to form a uniform melt; electromagnetic stirring drives the melt flow through electromagnetic force, eliminating composition gradients in the melt (such as local enrichment of Ni) and ensuring uniform distribution of various elements; argon (inert gas) protection can further isolate the air and prevent secondary oxidation of the melt;

[0061] Step 3: Refining

[0062] After smelting is completed, keep it at the smelting temperature for 10 to 30 minutes to allow impurities (such as low melting point metals and gases) to float or volatilize;

[0063] The purpose of this step is: at high temperatures, the viscosity of the melt decreases, and the solubility of impurities (such as low-melting-point metals such as Pb and Sn) decreases, causing them to form droplets and float to the surface of the melt. At the same time, the solubility of gases such as H2 and N2 decreases at high temperatures, causing them to escape in the form of bubbles, thereby reducing gas impurities and low-melting-point inclusions in the alloy and avoiding the adverse effects of these impurities on magnetic properties. For example, bubbles can cause a decrease in magnetic permeability, and inclusions can pin magnetic domain walls.

[0064] Step 4: Add AlTiLaB alloy powder

[0065] After refining, add 100-500nm AlTiLaB alloy powder at 1500-1520℃ and stir for 3-5min;

[0066] The purpose of this step: A temperature of 1500-1520°C ensures rapid dissolution and dispersion of the powder, preventing powder agglomeration due to excessively low temperatures. The high surface energy of the nanopowder makes it easy to diffuse in the melt, and the pre-alloyed powder is a uniform phase, which can avoid segregation (for example, Ti tends to aggregate in low-temperature regions) caused by differences in the melting points of elements when added individually (e.g., Al melts at 660°C, Ti melts at 1668°C). This ensures that Al, Ti, La, and B are evenly distributed and exert a synergistic effect (Al and Cr form a composite oxide film, Ti and B refine the grains, and La purifies the grain boundaries).

[0067] Step 5: Ultrasonic Casting

[0068] The melt treated in step 4 is cooled to 1400-1500°C and poured into a mold. After the pouring is completed, ultrasonic vibration is immediately applied to the mold. After the vibration is completed, it is naturally cooled for 1-2 hours and demolded to obtain an ingot;

[0069] The purpose of this step is to ensure the fluidity of the melt by maintaining a suitable casting temperature of 1400-1500°C (50-100°C above the liquidus temperature). Ultrasonic vibration (e.g., a frequency of 3kHz) generates mechanical vibrations that create periodic pressure fluctuations in the melt, impacting and breaking growing grains, forming more nucleation cores and thus refining the grains. Furthermore, the vibrations promote the escape of bubbles in the melt, reducing porosity defects and increasing the density of the alloy.

[0070] Step 6: Heat treatment

[0071] Homogenize the ingot at 1100-1200°C for 2-3 hours and cool it to room temperature at a rate of ≤5°C / min.

[0072] The purpose of this step: The annealing temperature of 1100~1200℃ can enable the alloy atoms to obtain sufficient diffusion energy and promote composition homogenization (eliminating dendritic segregation in cast alloys, such as the enrichment of Ni between dendrites); slow cooling (≤5℃ / min) can reduce the thermal stress caused by temperature gradient, avoid stress-induced magnetic anisotropy (stress will disrupt the arrangement of magnetic domains and increase coercivity), and at the same time promote uniform grain growth and improve structural stability.

[0073] The technical solution of the present invention is described in detail below with reference to specific embodiments and comparative examples. It should be noted that the following examples are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0074] Example 1

[0075] Alloy composition (at%): Ni 32%, Co 0.8%, Cr 1%, Mn 0.8%, Si 0.8%, Al 1%, Ti 0.4%, La 0.1%, B 0.1%, the balance is Fe and inevitable impurities.

[0076] The preparation method mainly comprises the following steps:

[0077] Step 1: Prepare AlTiLaB alloy powder: weigh raw materials according to the atomic percentage of Al 1%, Ti 0.4%, La 0.1%, and B 0.1%, place them in a ball mill (150 rpm, 3 hours), press them into prefabricated blocks after ball milling, place them in a vacuum melting furnace for melting, and keep them warm for 30 minutes; transfer the smelted alloy liquid to an ultrasonic atomization device, use high-pressure argon as the atomizing gas, and use 30kHz ultrasonic high-frequency vibration to break up the alloy liquid surface. The high-pressure airflow is then atomized into fine droplets, which are rapidly cooled and solidified in an inert gas to form AlTiLaB alloy powder;

[0078] Step 2: Melting: Calculate the mass of each raw material required for preparation according to the atomic percentage (at%) of each element Fe, Ni, Co, Cr, Mn, and Si in the alloy composition. Put the calculated mass of alloy raw materials into the crucible of the vacuum induction furnace, close the furnace door, and start vacuuming until the vacuum degree in the furnace reaches 10 -5 Pa; turn on the induction heating power supply, gradually increase the power, and the heating rate is 25℃ / min. The melting temperature is controlled at 1550℃. During the melting process, the alloy melt is fully mixed by electromagnetic stirring at a stirring frequency of 20Hz to ensure uniform composition; at the same time, argon gas at a flow rate of 2L / min is introduced into the furnace as a protective gas to prevent oxidation and reduce possible pores and inclusions;

[0079] Step 3: Refining: After smelting, refining treatment is carried out, maintaining the temperature at 1550°C for 30 minutes;

[0080] Step 4: Add AlTiLaB alloy powder: After refining, add AlTiLaB alloy powder according to the required content and stir for 4 minutes while maintaining the furnace temperature at 1510°C;

[0081] Step 5, casting: adjust the furnace temperature to 1450 ° C, prepare for casting, slowly pour the smelted alloy melt into the mold, and immediately perform ultrasonic vibration on the mold after casting for 10 minutes at an ultrasonic frequency of 3 kHz. After the vibration is completed, cool naturally for 2 hours and demold to obtain an ingot;

[0082] Step 6: Heat treatment: Perform homogenization annealing on the ingot, heat it to 1200°C and keep it for 3 hours, and then slowly cool it to room temperature at a rate of 3°C / min to obtain a corrosion-resistant magnetic temperature compensation alloy.

[0083] Example 2

[0084] Alloy composition (at%): Ni 36%, Co 0.9%, Cr 1.5%, Mn 0.9%, Si 1%, Al 1.5%, Ti 0.6%, La 0.3%, B 0.2%, the balance is Fe and inevitable impurities.

[0085] The preparation method mainly comprises the following steps:

[0086] Step 1: Prepare AlTiLaB alloy powder: weigh raw materials according to the atomic percentage of Al 1.5%, Ti 0.6%, La 0.3%, and B 0.2%, place them in a ball mill (150 rpm, 3 hours), press them into prefabricated blocks after ball milling, place them in a vacuum melting furnace for melting, and keep them warm for 30 minutes; transfer the smelted alloy liquid to an ultrasonic atomization device, use high-pressure argon as the atomizing gas, and use 30kHz ultrasonic high-frequency vibration to break up the alloy liquid surface. The high-pressure airflow is then atomized into fine droplets, which are rapidly cooled and solidified in an inert gas to form a powder;

[0087] Step 2: Melting: Calculate the mass of each raw material required for preparation according to the atomic percentage (at%) of each element Fe, Ni, Co, Cr, Mn, and Si in the alloy composition. Put the calculated mass of alloy raw materials into the crucible of the vacuum induction furnace, close the furnace door, and start vacuuming until the vacuum degree in the furnace reaches 10 -3 Pa, turn on the induction heating power supply, gradually increase the power, and the heating rate is 25℃ / min. The melting temperature is controlled at 1500℃. During the melting process, the alloy melt is fully mixed by electromagnetic stirring at a stirring frequency of 15Hz to ensure uniform composition. At the same time, argon gas with a flow rate of 1L / min is introduced into the furnace as a protective gas to prevent oxidation and reduce possible pores and inclusions;

[0088] Step 3: Refining: After smelting, refining treatment is carried out, maintaining the temperature at 1500℃ for 20 minutes;

[0089] Step 4: Add AlTiLaB alloy powder: After refining, add AlTiLaB alloy powder according to the required content and stir for 3 minutes while maintaining the furnace temperature at 1520°C;

[0090] Step 5, casting: adjust the furnace temperature to 1400℃, prepare for casting, slowly pour the smelted alloy melt into the mold, and immediately perform ultrasonic vibration on the mold after casting for 8 minutes at an ultrasonic frequency of 3kHz. After the vibration is completed, naturally cool for 1.5 hours and demold to obtain the ingot;

[0091] Step 6: Heat treatment: Perform homogenization annealing on the ingot, heat it to 1150° C. and keep it for 2.5 hours, then slowly cool it to room temperature at a rate of 5° C. / min to obtain a corrosion-resistant magnetic temperature compensation alloy.

[0092] Example 3

[0093] Alloy composition (at%): Ni 38%, Co 1%, Cr 2%, Mn 1%, Si 1.2%, Al 2%, Ti 0.8%, La 0.5%, B 0.2%, the balance is Fe and inevitable impurities.

[0094] The preparation method mainly comprises the following steps:

[0095] Step 1: Prepare AlTiLaB alloy powder: weigh raw materials according to the atomic percentage of Al 2%, Ti 0.8%, La 0.5%, and B 0.2%, place them in a ball mill (150 rpm, 3 hours), press them into prefabricated blocks after ball milling, place them in a vacuum melting furnace for melting, and keep them warm for 30 minutes; transfer the smelted alloy liquid to an ultrasonic atomization device, use high-pressure argon as the atomizing gas, and use 30kHz ultrasonic high-frequency vibration to break up the alloy liquid surface. The high-pressure airflow is then atomized into fine droplets, which are rapidly cooled and solidified in an inert gas to form powder;

[0096] Step 2: Melting: Calculate the mass of each raw material required for preparation according to the atomic percentage (at%) of each element Fe, Ni, Co, Cr, Mn, and Si in the alloy composition. Put the calculated mass of alloy raw materials into the crucible of the vacuum induction furnace, close the furnace door, and start vacuuming until the vacuum degree in the furnace reaches 10 -4Pa, turn on the induction heating power supply, gradually increase the power, the heating rate is 25℃ / min, and the melting temperature is controlled at 1530℃. During the melting process, the alloy melt is fully mixed by electromagnetic stirring at a stirring frequency of 25Hz to ensure uniform composition. At the same time, argon gas at a flow rate of 3L / min is introduced into the furnace as a protective gas to prevent oxidation and reduce possible pores and inclusions;

[0097] Step 3: Refining: After smelting, refining treatment is carried out, maintaining the temperature at 1530°C for 10 minutes;

[0098] Step 4: Add AlTiLaB alloy powder: After refining, add AlTiLaB alloy powder according to the required content and stir for 5 minutes while maintaining the furnace temperature at 1500°C;

[0099] Step 5, casting: adjust the furnace temperature to 1500℃, prepare for casting, slowly pour the smelted alloy melt into the mold, and immediately perform ultrasonic vibration on the mold after casting for 5 minutes at an ultrasonic frequency of 3kHz. After the vibration is completed, cool naturally for 1 hour and demold to obtain the ingot;

[0100] Step 6: Heat treatment: Perform homogenization annealing on the ingot, heat it to 1100°C and keep it for 2 hours, and then slowly cool it to room temperature at a rate of 1°C / min to obtain a corrosion-resistant magnetic temperature compensation alloy.

[0101] Comparative Example 1

[0102] The comparative example is a commercially available 1J32 soft magnetic alloy, the main components of which are: Ni 31.5-32.5at%, Co 1.5-2.5at%, Mn 0.5-1at%, Si 0.2-0.5at%, and the rest is Fe.

[0103] The properties of the alloys obtained in Examples 1-3 and Comparative Example 1 were tested below. First, the coercivity (Hc) of the alloys obtained in Examples 1-3 and Comparative Example 1 was tested using the demagnetization curve method. The magnetization intensity (M) of the alloys obtained in Examples 1-3 and Comparative Example 1 was tested using a vibrating sample magnetometer. The test results are shown in Table 1.

[0104] Table 1 Test results of coercivity and magnetization of alloys obtained in Examples 1 to 3 and Comparative Example 1

[0105]

[0106] As shown in Table 1, the coercive force of the alloys obtained in Examples 1-2 is less than that in Comparative Example 1, and the magnetization intensity is greater than that in Comparative Example 1. The coercive force of the alloy obtained in Example 3 is greater than that in Comparative Example 1, but the magnetization intensity is significantly greater than that in Comparative Example 1. The specific reasons are as follows:

[0107] First, the mechanism of lower coercivity and higher magnetization intensity of the alloy obtained in Example 1-2

[0108] (1) The core reason for the coercive force advantage

[0109] The coercive forces of Example 1 (1.81 A / m) and Example 2 (1.63 A / m) are lower than that of Comparative Example 1 (2 A / m). The key lies in the effective reduction of the resistance to magnetic domain wall movement by the composition and process:

[0110] Precise control of Si content: The Si content in Example 1 is 0.8 at%, and in Example 2 is 1 at%, both within the upper limit of 1.2 at%. Si inhibits grain growth by segregating at grain boundaries. The refined grains shorten the distance traveled by magnetic domain walls, while also reducing the saturation magnetostriction coefficient and alleviating stress interference with magnetic domain alignment, thereby lowering coercivity.

[0111] Synergistic refinement of Ti and B: In Examples 1-2, the Ti content is 0.4-0.6 at%, and the B content is 0.1-0.2 at%. The TiB2 phase formed by the two is small in size, which can pin the grain boundaries but does not hinder the movement of magnetic domain walls, thus avoiding the increase in coercivity caused by excessive second phases;

[0112] Reasonable matching of low Co content: The Co content (0.8~0.9at%) enhances magnetic coupling without causing obvious lattice distortion, ensuring smooth dislocation movement and avoiding the increase in magnetic domain wall resistance indirectly caused by increased brittleness.

[0113] (2) Key factors for improving magnetization intensity

[0114] The magnetization intensity of Example 1-2 (1.24×10 6 ~1.29×10 6 A / m) is higher than that of comparative example 1 (1.1×10 6 A / m), due to the synergistic enhancement of magnetic elements:

[0115] Magnetic coupling enhancement of Co: The 3d unpaired electrons of Co form strong exchange coupling with Fe and Ni, improving spin ordering. Low concentrations (0.8-0.9 at%) can significantly enhance the saturation magnetization intensity.

[0116] Structural stabilization effect of Ni: 32~36at% Ni forms a stable face-centered cubic (fcc) solid solution with Fe, providing a uniform lattice environment for the magnetic coupling of Co and avoiding magnetic attenuation caused by structural defects.

[0117] Second, the mechanism of significantly improved magnetization intensity but slightly higher coercive force in Example 3

[0118] (1) Dominant factors of magnetization strength advantage

[0119] The magnetization intensity of Example 3 (1.31×10 6 A / m) is the highest among the three, which is mainly due to the optimization of Co and Ni content:

[0120] The Co content reaches 1at% (the upper limit of the formula), which further strengthens the magnetic exchange coupling and enhances the spin order, and is the primary driving force for the increase in magnetization intensity; the Ni content is 38at% (the upper limit of the formula), which ensures the stability of the fcc structure, provides support for magnetic coupling under high Co content, and avoids the weakening of magnetism due to lattice distortion.

[0121] (2) Reasons for slightly higher coercivity

[0122] The coercivity of Example 3 (2.27 A / m) is slightly higher than that of Comparative Example 1, which is mainly related to the side effects of the high content of elements:

[0123] Ti (0.8at%) and La (0.5at%) both reach the upper limit of the formula. Excessive Ti may form more TiB2 phases, and La may form coarse La-rich non-magnetic phases at the grain boundaries. Both become pinning points for the movement of magnetic domain walls, increasing resistance. Si (1.2at%) reaches the upper limit. Although it refines the grains, it may precipitate a small amount of Fe3Si hard and brittle phase, further hindering the movement of magnetic domain walls and causing a slight increase in coercivity.

[0124] In summary, Examples 1-2 achieve an optimized balance of "low coercivity + high magnetization intensity" through a balanced design of components, while Example 3 prioritizes magnetization intensity by increasing the content of magnetic elements such as Co and Ni. Although the coercivity increases slightly due to the upper limit of some elements, the overall magnetic comprehensive performance is still better than that of Comparative Example 1.

[0125] Next, electrochemical open circuit potential and Tafel tests were performed on the alloys obtained in Example 1 and Comparative Example 1 using a CHI760E electrochemical workstation. A three-electrode system was used, with a saturated calomel electrode (SCE) serving as the reference electrode, a platinum sheet as the counter electrode, and the sample as the working electrode. To prevent electrochemical reactions from occurring in unexposed areas of the sample, the sample surface was sealed with epoxy resin, leaving only approximately 0.5 cm exposed. 2 The test area was 1000 nm. The test medium was a 3.5 wt% NaCl solution. The experimental temperature was room temperature. The test results are shown in Table 2.

[0126] Table 2 Electrochemical open circuit potential and Tafel test results of the alloys obtained in Example 1 and Comparative Example 1

[0127]

[0128] As shown in Table 2, electrochemical corrosion testing shows that Example 1 has a linear polarization resistance of approximately 3300Ω, significantly higher than that of the comparative example. The corrosion current is significantly lower than that of Comparative Example 1, and the corrosion potential is more positive. These results demonstrate that the corrosion resistance of the new soft magnetic alloy is significantly improved.

[0129] Figure 1 The surface micromorphology of the alloy obtained in Example 1 after electrochemical corrosion is shown. It can be observed that the corrosion surface is relatively flat as a whole, without obvious deep and wide pitting pits or intergranular corrosion cracks, and the corrosion is mainly uniform, indicating that the oxide film formed on the alloy surface has good continuity and can effectively block the corrosive medium (such as Cl - )penetration.

[0130] Figure 2 Three-dimensional scanning visually depicts the corroded surface of the alloy obtained in Example 1. Analysis reveals that the height difference of the corroded surface is small (the numerical range in the contour plot shows gentle undulations) and the maximum corrosion depth is shallow, indicating a slow corrosion rate. This is consistent with the electrochemical testing results of "low corrosion current and high linear polarization resistance," confirming the alloy's excellent corrosion resistance. Furthermore, the absence of localized, prominent corrosion defects on the surface further demonstrates the uniform protective effect of the composite oxide film, preventing localized accelerated corrosion caused by film defects and demonstrating the synergistic corrosion resistance enhancement achieved by the Cr, Al, and La components in the compositional design.

[0131] The present invention solves the problems of poor corrosion resistance and insufficient magnetism of traditional magnetic temperature compensation alloys by optimizing the alloy composition and preparation process. It can meet the needs of electromagnetic equipment in high-power and complex environments and has broad application prospects.

[0132] The above embodiments are only used to help understand the method and core concept of the present invention. It should be noted that for those skilled in the art, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention fall within the scope of protection of the present invention.

Claims

1. A corrosion-resistant magnetic temperature compensation alloy, characterized in that: Composed of the following elements in atomic percentages: Ni 32~38%, Co 0.8~1%, Cr 1~2%, Mn 0.8~1%, Si 0.8~1.2%, Al 1~2%, Ti 0.4~0.8%, La0.1~0.5%, B 0.1~0.2%, the balance is Fe and unavoidable impurities; Wherein, Al, Ti, La and B elements are added in the form of pre-alloyed AlTiLaB alloy powder during the alloy smelting process, and the particle size of the AlTiLaB alloy powder is 100-500nm; The preparation method of the corrosion-resistant magnetic temperature compensation alloy comprises the following steps: Step 1: Prepare AlTiLaB alloy powder: weigh Al, Ti, La, and B elemental raw materials according to atomic percentage, place them in a ball mill, and mix them evenly by ball milling under inert gas protection to obtain a mixed powder; press the mixed powder into a prefabricated block, then place the prefabricated block in a vacuum melting furnace for vacuum melting and keep it warm for 30 minutes to obtain an alloy liquid; use high-pressure argon as an atomizing gas and an ultrasonic gas atomization process to atomize the alloy liquid to obtain a powder; sieve the powder to obtain AlTiLaB alloy powder of the target particle size; Step 2: Alloy smelting: Weigh pure Fe, pure Ni, pure Co, pure Cr, pure Mn and pure Si raw materials according to atomic percentage, place them in a vacuum induction furnace for smelting, and the vacuum degree reaches 10 -3 ~10 -5 Pa, melting temperature 1500~1550℃, stirring during the melting process, while introducing protective gas to obtain a melt; Step 3: Refining: Keep the melt obtained in step 2 at the melting temperature for 10 to 30 minutes; Step 4: Add AlTiLaB alloy powder: Add the AlTiLaB alloy powder prepared in step 1 to the refined melt and stir at a temperature of 1500-1520° C. for 3-5 minutes; Step 5, ultrasonic casting: cool the melt treated in step 4 to 1400-1500°C and pour it into a mold. After the pouring is completed, ultrasonic vibration is immediately applied to the mold. After the vibration is completed, it is naturally cooled for 1-2 hours and demolded to obtain an ingot. Step 6: Heat treatment: The ingot is subjected to homogenization annealing at 1100-1200° C. for 2-3 hours, and then slowly cooled to room temperature to obtain a corrosion-resistant magnetic temperature compensation alloy.

2. The corrosion-resistant magnetic temperature compensation alloy according to claim 1, characterized in that: In step 2, the protective gas is argon with a flow rate of 1-3 L / min; the stirring is performed by electromagnetic stirring with a frequency of 15-25 Hz.

3. The corrosion-resistant magnetic temperature compensation alloy according to claim 1, characterized in that: In step five, the ultrasonic vibration frequency is 3 kHz, and the vibration duration is 5 to 10 minutes.

4. The corrosion-resistant magnetic temperature compensation alloy according to claim 1, characterized in that: In step six, after annealing, the film is cooled to room temperature at a rate of ≤5°C / min.

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