Polycrystalline ferromagnetic shape memory alloy with high cold workability and preparation method thereof
By preparing Fe44Mn28Ga28 polycrystalline ferromagnetic shape memory alloy, introducing γ phase and B2 phase and induced transformation through stress, the brittleness problem of Heusler alloy was solved, and high cold processing performance and mechanical property improvement were achieved.
Patent Information
- Application Number
- CN202510565623.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-30
- Publication Date
- 2025-09-09
AI Technical Summary
Heusler alloys cannot be processed and formed by traditional methods due to their intrinsic brittleness, and existing methods of doping γ phases make it difficult to control the effects on martensitic transformation and magnetic properties.
By preparing Fe44Mn28Ga28 polycrystalline ferromagnetic shape memory alloy, introducing γ phase structure and B2 phase structure, using stress to induce B2 phase-γ phase transformation, controlling the content of γ phase structure to adjust the influence of martensitic transformation temperature and magnetic properties, and adopting arc melting, cold rolling and annealing processes.
The high cold processing performance and ductility of polycrystalline ferromagnetic shape memory alloys were achieved, and the mechanical properties and fracture strain were improved. The maximum compressive strength was increased by 6 times and the fracture strain was increased by 5 times.
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Figure CN120608235A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of metal alloys, and in particular relates to a polycrystalline ferromagnetic shape memory alloy with high cold workability and a preparation method thereof. Background Art
[0002] Heusler magnetic shape memory alloys play an important role in high-tech fields such as aerospace, advanced manufacturing and new energy. Heusler-type magnetic phase change materials achieve stress output, shape memory, and magneto-induced entropy change through magnetically driven martensitic phase transformation, that is, they have large output strain and high response frequency. They are currently used to make sensors, actuators and as solid-state refrigeration materials. Due to the inherent brittleness of Heusler alloys, they cannot be processed and formed by traditional methods, which limits their development. A common method to reduce the brittleness of Heusler alloys is to introduce a tough face-centered cubic (fcc) second phase (γ phase) with high plasticity. By introducing a γ phase with high plasticity, the mechanical properties of the material are improved.
[0003] Improvements in mechanical properties depend on the proportion of the introduced γ phase in the matrix. However, the γ phase does not undergo martensitic transformation, thus affecting the alloy's performance. A high proportion of γ phase can negatively impact magnetic transformation. Therefore, when doping with the γ phase, it is important to minimize any negative impacts on the martensitic transformation temperature and magnetic properties. Since the prior art typically uses other elements to achieve γ phase doping, it is difficult to control the adverse effects of the doping elements on the martensitic transformation temperature and magnetic properties. Therefore, it is necessary to find a method for introducing the γ phase that can improve mechanical properties while controlling the effects on the transformation temperature and magnetic properties. Summary of the Invention
[0004] The object of the present invention is to overcome the shortcomings and deficiencies of the prior art and provide a polycrystalline ferromagnetic shape memory alloy with high cold workability, excellent cold working performance and ductility, increased fracture strain, and improved mechanical properties of the material. The content of the γ phase structure is quantitatively regulated by stress induction to adjust the influence of the γ phase structure on the martensitic transformation temperature and magnetic properties. On the basis of improving the mechanical strength, the influence of the γ phase structure on the martensitic transformation temperature and magnetic properties is controlled within a certain range.
[0005] The present invention is achieved through the following technical solutions:
[0006] The present invention provides a polycrystalline ferromagnetic shape memory alloy with high cold workability, the chemical formula of which is Fe 44 Mn 28 Ga 28 The polycrystalline ferromagnetic shape memory alloy includes a γ phase structure and a B2 phase structure.
[0007] The polycrystalline ferromagnetic shape memory alloy with high cold workability provided by the present invention comprises a γ phase structure and a B2 phase structure, has excellent cold workability and ductility, increases fracture strain, and improves the mechanical properties of the material.
[0008] Furthermore, in the polycrystalline ferromagnetic shape memory alloy with high cold workability, the γ phase structure is obtained by stress induction of the B2 phase structure. By stress inducing the crystal of the B2 phase structure to undergo phase transformation, the B2 phase-γ phase transformation is achieved, and the Fe 44 Mn 28 Ga 28 The greater the stress, the more γ phase is formed. The content of the γ phase structure can be quantitatively controlled according to performance requirements to adjust the influence of the γ phase structure on the martensitic transformation temperature and magnetic properties. On the basis of improving mechanical strength, the influence of the γ phase structure on the martensitic transformation temperature and magnetic properties can be controlled within a certain range.
[0009] The present invention also provides a method for preparing the polycrystalline ferromagnetic shape memory alloy having high cold workability, comprising the following steps: 44 Mn 28 Ga 28 The invention relates to a method for manufacturing a polycrystalline ferromagnetic shape memory alloy comprising a ferromagnetic shape memory alloy having an atomic percentage composition, mixing an Fe source, a Mn source and a Ga source, and performing arc melting to obtain an alloy ingot of B2 phase; cutting the alloy ingot to obtain a billet; cold rolling the billet to obtain an alloy sheet including a γ phase; annealing the alloy sheet; and quenching the annealed alloy sheet to obtain a polycrystalline ferromagnetic shape memory alloy.
[0010] In the method for preparing a polycrystalline ferromagnetic shape memory alloy with high cold workability provided by the present invention, a B2 phase alloy ingot is obtained by arc melting, and then a cold rolling treatment is performed. The B2 phase crystal undergoes a phase transformation through stress induction, achieving a B2 phase-γ phase transformation, thereby improving the mechanical properties of the polycrystalline ferromagnetic shape memory alloy.
[0011] Furthermore, in the step of cold rolling the billet to obtain an alloy sheet including a γ phase, the billet is cold rolled at room temperature using a cold rolling mill, and the billet is rolled multiple times, with the reduction rate gradually increasing at a certain amplitude each time, until an alloy sheet of a certain thickness is obtained. By stress-inducing a phase transition of the B2 phase structure crystal, the transformation from B2 phase to γ phase is achieved, and Fe 44 Mn 28 Ga 28 The greater the stress, the greater the proportion of γ phase formed. The rolling reduction rate can be quantitatively adjusted according to performance requirements to regulate the content of the γ phase structure. On the basis of improving mechanical strength, the influence of the γ phase structure on the martensitic transformation temperature and magnetic properties can be controlled within a certain range.
[0012] Furthermore, in the step of cold-rolling the billet to obtain an alloy sheet including a γ phase, the rolling reduction ratio ε of the final rolling process is 27% < x < 90%. The rolling reduction ratio ε is controlled to form a polycrystalline ferromagnetic shape memory alloy in which a γ phase structure and a B2 phase structure coexist, avoiding a rolling reduction ratio that is too low, resulting in the failure to form the γ phase structure, or a rolling reduction ratio that is too high, resulting in the complete transformation of the B2 phase structure into the γ phase structure.
[0013] Furthermore, in the step of cold-rolling the billet to obtain an alloy sheet containing a gamma phase, the billet is rolled multiple times, with the difference in reduction between each rolling pass and the previous rolling pass being 1% to 3%. The rolling reduction is gradually increased by 1% to 3%, increasing the stress applied to the billet and gradually adjusting the rolling reduction to form an appropriate proportion of the gamma phase structure.
[0014] Further, according to Fe 44 Mn 28 Ga 28 In the step of mixing an Fe source, a Mn source and a Ga source and arc melting to obtain an alloy ingot of B2 phase, the alloy ingot is melted 3-5 times in an inert gas in a metal arc furnace, and after each melting, the alloy ingot is turned over and the next melting is carried out.
[0015] Further, according to Fe 44 Mn 28 Ga 28 In the step of arc melting to obtain an alloy ingot of B2 phase, the melting temperature is 1500℃~1600℃ and the melting current is 70A~90A. The appropriate melting temperature and melting current intensity are selected to fully melt and mix the Fe source, Mn source and Ga source to form Fe2 phase. 44 Mn 28 Ga 28 .
[0016] Further, according to Fe 44 Mn 28 Ga 28 In the step of arc melting the Fe, Mn, and Ga sources to obtain a gold ingot with a B2 phase, a Mn source is added at a level of 0.3% to 1% by weight of the total Fe, Mn, and Ga sources. Due to the low saturated vapor pressure of Mn, the volatilization loss of Mn during the melting process exceeds that of the other two elements in the alloy. Therefore, an appropriate amount of Mn can be added to the batching.
[0017] Furthermore, in the step of annealing the alloy sheet, the annealing time is 9-11 hours and the annealing temperature is 1200-1300K; in the step of quenching the annealed alloy sheet to obtain a polycrystalline ferromagnetic shape memory alloy, the quenching speed is 8×10 3 -1.2×10 4 K / s.
[0018] For better understanding and implementation, the present invention is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 This is a flow chart of the method for preparing the polycrystalline ferromagnetic shape memory alloy of Example 2.
[0020] Figure 2 Fe of Example 3 44 Mn 28 Ga 28 Metallographic microscope image of the alloy.
[0021] Figure 3 Fe of Example 3 44 Mn 28 Ga 28 X-ray diffraction pattern of polycrystalline ferromagnetic shape memory alloy.
[0022] Figure 4 Fe of Example 3 44 Mn 28 Ga 28 Stress-strain curve of the alloy.
[0023] Figure 5 Fe of Example 3 44 Mn 28 Ga 28 Diagram of the crystal structure evolution of the alloy during cold rolling. DETAILED DESCRIPTION
[0024] The following is a further detailed description of the embodiments of the present invention in conjunction with the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the embodiments of the present invention and are not intended to limit the embodiments of the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions of the embodiments of the present invention, rather than all structures.
[0025] Furthermore, the terms "first," "second," "third," etc., in the specification and claims are used solely for descriptive purposes to distinguish between identical technical features. They are not to be construed as indicating or implying relative importance, or as implicitly specifying the number of technical features, nor do they necessarily describe a sequential or chronological order. The terms are interchangeable where appropriate. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one of those features.
[0026] Similarly, the terms "fixed" and "connected" used in the specification and claims should not be construed as limited to direct connections. Thus, the expression "device A is connected to device B" should not be limited to devices or systems in which device A is directly connected to device B. Rather, it means that a path exists between device A and device B, which may include other devices or tools.
[0027] Example 1
[0028] This embodiment provides a polycrystalline ferromagnetic shape memory alloy with high cold workability, the chemical formula of which is Fe 44 Mn 28 Ga 28 The polycrystalline ferromagnetic shape memory alloy includes a γ phase structure and a B2 phase structure.
[0029] The polycrystalline ferromagnetic shape memory alloy with high cold workability provided in this embodiment includes a γ phase structure and a B2 phase structure, has excellent cold working performance and ductility, and increases the fracture strain and improves the mechanical properties of the material.
[0030] In this embodiment, in the polycrystalline ferromagnetic shape memory alloy, the γ phase structure is obtained by stress induction of the B2 phase structure. By stress inducing the crystal of the B2 phase structure to undergo phase transformation, the B2 phase-γ phase transformation is achieved. 44 Mn 28 Ga 28 The greater the stress, the more γ phase is formed. The content of the γ phase structure can be quantitatively controlled according to performance requirements to adjust the influence of the γ phase structure on the martensitic transformation temperature and magnetic properties. On the basis of improving mechanical strength, the influence of the γ phase structure on the martensitic transformation temperature and magnetic properties can be controlled within a certain range.
[0031] The polycrystalline ferromagnetic shape memory alloy provided in this embodiment has high cold workability and can be cold worked. It can withstand large deformation without breaking during cold working and can be made into various complex shapes, such as cold-rolled steel plates, cold-drawn aluminum profiles, etc., and can be used in steel nodes, seismic-resistant materials and other fields.
[0032] Example 2
[0033] This embodiment provides a method for preparing the polycrystalline ferromagnetic shape memory alloy with high cold workability of embodiment 1. Figure 1 This is a flow chart of the preparation method of polycrystalline ferromagnetic shape memory alloy, please refer to Figure 1 The preparation method of the polycrystalline ferromagnetic shape memory alloy comprises the following steps:
[0034] Step S1: According to Fe 44 Mn 28 Ga 28 The atomic percentage composition is obtained by mixing Fe source, Mn source and Ga source, and arc melting is performed to obtain an alloy ingot of B2 phase;
[0035] Step S2: cutting the alloy ingot to obtain billets;
[0036] Step S3: cold rolling the blank to obtain an alloy sheet including a γ phase;
[0037] Step S4: annealing the alloy sheet;
[0038] Step S5: quenching the annealed alloy sheet to obtain a polycrystalline ferromagnetic shape memory alloy.
[0039] In the method for preparing a polycrystalline ferromagnetic shape memory alloy with high cold workability provided by the present invention, a B2 phase alloy ingot is obtained by arc melting, and then a cold rolling treatment is performed. The B2 phase crystal undergoes a phase transformation through stress induction, achieving a B2 phase-γ phase transformation, thereby improving the mechanical properties of the polycrystalline ferromagnetic shape memory alloy.
[0040] In this embodiment, in step S1, according to Fe 44 Mn 28 Ga 28 In the step of mixing an Fe source, a Mn source and a Ga source and arc melting to obtain an alloy ingot of B2 phase, the alloy ingot is melted 3-5 times in an inert gas in a metal arc furnace, and after each melting, the alloy ingot is turned over and the next melting is carried out.
[0041] In one embodiment, before use, the Fe source and the Mn source are cleaned and dried for pretreatment, and are cleaned in an ultrasonic cleaner with anhydrous ethanol for 5 minutes and then dried. The Ga source does not need to be cleaned.
[0042] In this embodiment, in step S1, the Fe source, Mn source, and Ga source are selected from Fe metal particles, Mn metal particles, and Ga metal particles, respectively, and the average particle size of the Fe metal particles, Mn metal particles, and Ga metal particles is 1-3 mm. In one embodiment, the Fe source can be irregularly shaped Fe metal particles with an average particle size of 2 mm; the Mn source can be irregular flake-shaped Mn metal with a thickness of 1 mm and a length and width of 3 to 5 mm, respectively; and the Ga source can be spherical Ga metal particles with a diameter of 1 mm.
[0043] The purity of the Fe source, the Mn source, and the Ga source is ≥99.99 wt %. In one embodiment, the purity of the metal elements of the Fe source, the Mn source, and the Ga source is 99.995 wt %.
[0044] In this embodiment, in step S1, according to Fe 44 Mn 28 Ga 28 In the step of arc melting to obtain an alloy ingot of B2 phase, the melting temperature is 1500℃~1600℃ and the melting current is 70A~90A. The appropriate melting temperature and melting current intensity are selected to fully melt and mix the Fe source, Mn source and Ga source to form Fe2 phase. 44 Mn 28 Ga 28 .
[0045] In this embodiment, in step S1, according to Fe 44 Mn 28 Ga 28 In the step of mixing Fe source, Mn source and Ga source and arc melting to obtain B2 phase alloy ingot, in this embodiment, in step S1, according to Fe 44 Mn 28 Ga 28 In the step of arc melting the Fe, Mn, and Ga sources to obtain a gold ingot with a B2 phase, a Mn source is added at a level of 0.3% to 1% by weight of the total Fe, Mn, and Ga sources. Due to the low saturated vapor pressure of Mn, the volatilization loss of Mn during the melting process exceeds that of the other two elements in the alloy. Therefore, an appropriate amount of Mn can be added to the batching.
[0046] In this embodiment, in step S2, the alloy ingot is cut using a wire-cut electric discharge machine to obtain a billet of a certain thickness from the center area of the alloy ingot.
[0047] In this embodiment, in step S3, the billet is cold rolled to obtain an alloy sheet including a γ phase. The billet is cold rolled at room temperature using a cold rolling mill. The billet is rolled multiple times, and the reduction rate is gradually increased by a certain amplitude each time until an alloy sheet of a certain thickness is obtained. By stress-inducing a phase transition of the B2 phase structure crystal, the B2 phase-γ phase transition is achieved. 44 Mn 28 Ga 28 The greater the stress, the greater the proportion of γ phase formed. The rolling reduction rate can be quantitatively adjusted according to performance requirements to regulate the content of the γ phase structure. On the basis of improving mechanical strength, the influence of the γ phase structure on the martensitic transformation temperature and magnetic properties can be controlled within a certain range.
[0048] Rolling reduction rate Among them, d is the thickness of the alloy sheet after cold rolling, d0 is the initial thickness of the billet before cold rolling, and the greater the rolling reduction rate, the deeper the rolling degree, and the thinner the alloy sheet.
[0049] In this embodiment, in step S3, in which the billet is cold rolled to obtain an alloy sheet including a γ phase, the rolling reduction ratio ε of the final rolling process is 27% < x < 90%. The rolling reduction ratio ε is controlled to form a polycrystalline ferromagnetic shape memory alloy in which a γ phase structure and a B2 phase structure coexist, avoiding situations where the rolling reduction ratio is too small, resulting in the failure to form the γ phase structure, or where the rolling reduction ratio is too large, resulting in the complete transformation of the B2 phase structure into the γ phase structure.
[0050] In this embodiment, in step S3, during the cold rolling of the billet to obtain the alloy sheet including the γ phase, the billet is rolled multiple times, with the difference between the rolling reduction rate of each rolling pass and the rolling reduction rate of the previous rolling pass being 1%-3%. The rolling reduction rate is gradually adjusted to form an appropriate proportion of the γ phase structure, and the rolling reduction rate is gradually increased by 1%-3% to ensure consistency in each rolling process. Before each rolling pass, the gap between the cold rolling mill rollers is adjusted using the cold rolling mill handle to increase the rolling reduction rate by 1%-3%. During the rolling process, the billet is subjected to compression force, undergoing plastic deformation and reducing its thickness.
[0051] In one embodiment, the blank is cold rolled at room temperature using a cold rolling mill, with the reduction ratio increasing by 2% each time until an alloy sheet of a certain thickness is obtained.
[0052] In this embodiment, in step S4, in the step of annealing the alloy sheet, the annealing time is 9-11 hours and the annealing temperature is 1200-1300K.
[0053] In step S4, the annealed alloy sheet is quenched to obtain a polycrystalline ferromagnetic shape memory alloy. The quenching speed is 8×103 -1.2×10 4 K / s.
[0054] Example 3
[0055] This embodiment provides a method for preparing a polycrystalline ferromagnetic shape memory alloy, comprising the following steps:
[0056] Step S1: According to Fe 44 Mn 28 Ga 28 The atomic percentage composition of Fe, Mn and Ga is mixed and arc-melted to obtain an alloy ingot of B2 phase. 44 Mn 28 Ga 28 According to the set atomic percentage, 44 parts by mass of Fe material, 28 parts by mass of Mn material and 28 parts by mass of Ga material are taken, and Mn material accounting for 1% of the total mass of the metal raw materials (Fe material, Mn material and Ga material) is added. After mixing, the mixture is placed in a metal arc furnace; under the protection of inert gas argon, the alloy is melted at 1550°C with a melting current of 80A for 4 times, 2 times on the front and back sides, and each melting time is 1 minute to obtain an alloy ingot of B2 phase.
[0057] Step S2: Cut the alloy ingot to obtain a billet. Specifically, use an electric discharge cutting machine to cut the center area of the alloy ingot to form a 1 mm thick billet.
[0058] Step S3: The billet is cold rolled to produce an alloy sheet containing the γ phase. Specifically, the billet is cold rolled at room temperature using a cold rolling mill, with the reduction ratio increasing by 2% each time. During the rolling process, the billet is subjected to compressive forces, undergoing plastic deformation and reducing its thickness until an alloy sheet of a certain thickness is obtained. By increasing the reduction ratio by 2%, the rolling strength gradually increases, and stress-induced phase transformation of the B2 phase crystals occurs, achieving a B2-γ phase transition.
[0059] Step S4: annealing the alloy sheet, specifically, annealing at 1273K for 10 hours.
[0060] Step S5: quenching the annealed alloy sheet to obtain a polycrystalline ferromagnetic shape memory alloy. 4 K / s cooling rate rapid quenching, obtain Fe 44 Mn 28 Ga 28 Polycrystalline ferromagnetic shape memory alloys.
[0061] The prepared polycrystalline ferromagnetic shape memory alloy was examined by metallographic microscope. Figure 2 It is Fe 44 Mn28 Ga 28 For metallographic microscope images of the alloy, please refer to Figure 2 The Fe prepared in this example 44 Mn 28 Ga 28 The alloy has a polycrystalline strip-like grain texture.
[0062] Figure 3 It is Fe 44 Mn 28 Ga 28 X-ray diffraction pattern of polycrystalline ferromagnetic shape memory alloy, please refer to Figure 3 , under stress induction with a rolling reduction of 27%, Fe 44 Mn 28 Ga 28 The alloy begins to produce γ phase. Under the stress induction of 90% rolling reduction, Fe 44 Mn 28 Ga 28 The alloy produces a pure γ phase, and the B2 phase is completely transformed into the γ phase. Therefore, the rolling reduction ratio ε is controlled between 27% and 90% to form a polycrystalline ferromagnetic shape memory alloy in which the γ phase structure and the B2 phase structure coexist. It is avoided that the rolling reduction ratio is too small, resulting in the failure to form the γ phase structure, or the rolling reduction ratio is too large, resulting in the complete transformation of the B2 phase structure into the γ phase structure.
[0063] Fe 44 Mn 28 Ga 28 The alloy can be formed into Fe including γ phase by cold rolling 44 Mn 28 Ga 28 Polycrystalline ferromagnetic shape memory alloys can withstand large deformation without breaking during the cold rolling process. They can be made into various complex shapes, such as cold-rolled steel plates, cold-drawn aluminum profiles, etc., and can be used in steel nodes, seismic materials and other fields.
[0064] The B2 phase Fe 44 Mn 28 Ga 28 As a comparative example, the γ phase Fe 44 Mn 28 Ga 28 Alloy with B2 phase Fe 44 Mn 28 Ga 28 The alloy was subjected to mechanical compression test. Figure 4 It is Fe 44 Mn 28 Ga 28 For stress-strain curves of alloys, see Figure 4In this embodiment, the γ phase Fe 44 Mn 28 Ga 28 The maximum engineering compressive strength of the alloy exceeds 4000 MPa, and the fracture strain is 78%. 44 Mn 28 Ga 28 The maximum compressive strength of the alloy is 700Mpa, and it breaks after 15% strain. 44 Mn 28 Ga 28 The alloy's maximum compressive strength increased by 6 times, its fracture strain increased by 5 times, and its strength and ductility after cold rolling were significantly improved. In practical applications, the γ phase content was quantitatively controlled through stress induction to regulate its effect on the martensitic transformation temperature and magnetic properties. While improving mechanical strength, the effects of the γ phase on the martensitic transformation temperature and magnetic properties were controlled within a certain range.
[0065] Fe 44 Mn 28 Ga 28 Measuring the evolution of the crystal structure during deformation of polycrystalline ferromagnetic shape memory alloys, Figure 5 It is Fe 44 Mn 28 Ga 28 For a diagram of the evolution of the alloy's crystal structure during cold rolling, see Figure 5 When the rolling reduction rate is 27%, the BCC phase (B2 phase) and FCC phase (γ phase) coexist. As the rolling reduction rate increases to 90%, Fe 44 Mn 28 Ga 28 The alloy eventually transformed into a complete FCC phase, revealing that the crystal structure of the sample underwent an obvious BCC-FCC phase transformation during the deformation process to form the γ phase. 44 Mn 28 Ga 28 The alloy undergoes a stress-induced phase transformation, which can lead to a BCC-FCC phase transition. The magnitude of the stress is positively correlated with the proportion of the γ phase structure. The greater the stress, the greater the proportion of the γ phase structure, which is beneficial for improving the material's mechanical properties. Therefore, based on the actual requirements for mechanical properties, martensitic transformation temperature, and magnetic properties, the proportion of the γ phase structure can be controlled by quantitatively controlling the rolling reduction during the cold rolling process, thereby achieving a balance between mechanical properties, martensitic transformation temperature, and magnetic properties.
[0066] Example 4
[0067] This embodiment provides a method for preparing a polycrystalline ferromagnetic shape memory alloy, comprising the following steps:
[0068] Step S1: According to Fe 44 Mn 28 Ga 28 The atomic percentage composition of Fe, Mn and Ga is mixed and arc-melted to obtain an alloy ingot of B2 phase. 44 Mn 28 Ga 28 According to the set atomic percentage, 44 parts by mass of Fe material, 28 parts by mass of Mn material and 28 parts by mass of Ga material are taken, and 0.3% of the total mass of Mn material is added to the metal raw materials (Fe material, Mn material and Ga material). After mixing, the mixture is placed in a metal arc furnace; under the protection of inert gas argon, the alloy is melted at 1500°C with a melting current of 70A for 3 times, 2 times on the front side and 1 time on the back side, and each melting time is 1 minute to obtain an alloy ingot of B2 phase.
[0069] Step S2: cutting the alloy ingot to obtain billets.
[0070] Step S3: The billet is cold rolled to obtain an alloy sheet containing the γ phase. Specifically, the billet is cold rolled at room temperature using a cold rolling mill, with the rolling reduction increasing by 1% each time. During the rolling process, the billet is subjected to compressive forces, undergoing plastic deformation and reducing its thickness until an alloy sheet of a certain thickness is obtained. By increasing the rolling reduction by 1%, the rolling strength gradually increases, and stress-induced phase transformation of the B2 phase crystals occurs, achieving a B2-γ phase transition.
[0071] Step S4: annealing the alloy sheet, specifically, annealing at 1200K for 9 hours.
[0072] Step S5: quenching the annealed alloy sheet to obtain a polycrystalline ferromagnetic shape memory alloy. 3 K / s cooling rate rapid quenching, obtain Fe 44 Mn 28 Ga 28 Polycrystalline ferromagnetic shape memory alloys.
[0073] Example 5
[0074] This embodiment provides a method for preparing a polycrystalline ferromagnetic shape memory alloy, comprising the following steps:
[0075] Step S1: According to Fe 44 Mn 28 Ga 28 The atomic percentage composition of Fe, Mn and Ga is mixed and arc-melted to obtain an alloy ingot of B2 phase. 44 Mn 28 Ga28 According to the set atomic percentage, 44 parts by mass of Fe material, 28 parts by mass of Mn material and 28 parts by mass of Ga material are taken, and Mn material accounting for 1% of the total mass of the metal raw materials (Fe material, Mn material and Ga material) is added. After mixing, the mixture is placed in a metal arc furnace; under the protection of inert gas argon, the alloy is melted at 1600°C with a melting current of 80A for 5 times, 3 times on the front side and 2 times on the back side, and each melting time is 1 minute to obtain an alloy ingot of B2 phase.
[0076] Step S2: cutting the alloy ingot to obtain billets.
[0077] Step S3: The billet is cold rolled to produce an alloy sheet containing the γ phase. Specifically, the billet is cold rolled at room temperature using a cold rolling mill, with the reduction ratio increasing by 3% each time. During the rolling process, the billet is subjected to compressive forces, undergoing plastic deformation and reducing its thickness until an alloy sheet of a certain thickness is obtained. By increasing the reduction ratio by 10%, the rolling strength gradually increases, and stress-induced phase transformation of the B2 phase crystals occurs, achieving a B2-γ phase transition.
[0078] Step S4: annealing the alloy sheet, specifically, annealing at 1300 K for 11 hours.
[0079] Step S5: quenching the annealed alloy sheet to obtain a polycrystalline ferromagnetic shape memory alloy. 4 K / s cooling rate rapid quenching, obtain Fe 44 Mn 28 Ga 28 Polycrystalline ferromagnetic shape memory alloys.
[0080] The present invention is not limited to the above-mentioned embodiments. If various changes or modifications of the present invention do not depart from the spirit and scope of the present invention, and if these changes and modifications fall within the scope of the claims of the present invention and equivalent technologies, the present invention is also intended to include these changes and modifications.
Claims
1. A polycrystalline ferromagnetic shape memory alloy with high cold workability, characterized in that: The chemical formula of the polycrystalline ferromagnetic shape memory alloy is Fe 44 Mn 28 Ga 28 The polycrystalline ferromagnetic shape memory alloy includes a γ phase structure and a B2 phase structure.
2. The polycrystalline ferromagnetic shape memory alloy with high cold workability according to claim 1, characterized in that: In the polycrystalline ferromagnetic shape memory alloy, the γ phase structure is obtained by stress induction of the B2 phase structure.
3. A method for preparing the polycrystalline ferromagnetic shape memory alloy with high cold workability according to any one of claims 1 to 2, characterized in that: The following steps are involved: According to Fe 44 Mn 28 Ga 28 The atomic percentage composition is obtained by mixing Fe source, Mn source and Ga source, and arc melting is performed to obtain an alloy ingot of B2 phase; Cutting the alloy ingot to obtain billets; cold-rolling the billet to obtain an alloy sheet including a γ phase; Annealing the alloy sheet; The annealed alloy slices are quenched to obtain a polycrystalline ferromagnetic shape memory alloy.
4. The method for preparing a polycrystalline ferromagnetic shape memory alloy with high cold workability according to claim 3, wherein: In the step of cold rolling the billet to obtain an alloy sheet including a γ phase, the billet is cold rolled at room temperature using a cold rolling mill, and the billet is rolled multiple times, with the reduction rate gradually increasing by a certain amplitude each time, until an alloy sheet of a certain thickness is obtained.
5. The method for preparing a polycrystalline ferromagnetic shape memory alloy with high cold workability according to claim 4, characterized in that: In the step of cold-rolling the billet to obtain an alloy sheet including a γ phase, the rolling reduction ratio ε of the last rolling is 27%<x<90%.
6. The method for preparing a polycrystalline ferromagnetic shape memory alloy with high cold workability according to claim 5, characterized in that: In the step of cold rolling the billet to obtain the alloy sheet including the γ phase, the billet is rolled multiple times, and the difference between the rolling reduction rate of each rolling and the rolling reduction rate of the previous rolling is 1%-3%.
7. The method for preparing a polycrystalline ferromagnetic shape memory alloy with high cold workability according to any one of claims 3 to 6, characterized in that: According to Fe 44 Mn 28 Ga 28 In the step of mixing an Fe source, a Mn source and a Ga source and arc melting to obtain an alloy ingot of B2 phase, the alloy ingot is melted 3-5 times in an inert gas in a metal arc furnace, and after each melting, the alloy ingot is turned over and the next melting is carried out.
8. The method for preparing a polycrystalline ferromagnetic shape memory alloy with high cold workability according to claim 7, characterized in that: According to Fe 44 Mn 28 Ga 28 In the step of mixing an Fe source, a Mn source and a Ga source and arc melting to obtain an alloy ingot of B2 phase, the melting temperature is 1500° C. to 1600° C. and the melting current is 70A to 90A.
9. The method for preparing a polycrystalline ferromagnetic shape memory alloy according to claim 7, wherein: According to Fe 44 Mn 28 Ga 28 In the step of mixing an Fe source, a Mn source and a Ga source and arc melting to obtain a gold ingot of B2 phase, a Mn source accounting for 0.3%-1% of the total mass of the Fe source, the Mn source and the Ga source is added.
10. The method for preparing a polycrystalline ferromagnetic shape memory alloy with high cold workability according to claim 3, characterized in that: In the step of annealing the alloy sheet, the annealing time is 9-11 hours and the annealing temperature is 1200-1300K; In the step of quenching the annealed alloy sheet to obtain a polycrystalline ferromagnetic shape memory alloy, the quenching speed is 8×10 3 -1.2×10 4 K / s.