A processing method for rapidly improving the magneto-caloric effect of high brittleness La-Fe-Co-Si rare earth magnetic refrigeration alloy

Abstract

The application relates to the alloy processing technical field, and particularly relates to a processing method for rapidly improving the magnetocaloric effect of high-brittle La-Fe-Co-Si rare earth magnetic refrigeration alloy. Under the protection of an argon atmosphere, high-temperature hot compression technology is adopted to make the high-brittle La-Fe-Co-Si rare earth magnetic refrigeration alloy reach high deformation at a low strain rate at high temperature, the deformation temperature is 950 DEG C to 1050 DEG C, the strain rate is 0.005 s ‑1 ~ 0.01 s ‑1 , and the deformation is 60% to 80%. The method of high-temperature, low-strain and large-deformation compression under the protection of an argon atmosphere effectively solves the problems that the magnetocaloric performance of the La-Fe-Co-Si magnetic refrigeration alloy is difficult to be obviously improved and the alloy is high-brittle, so that the alloy rapidly generates a magnetic heat phase in the process of high-temperature hot compression, and the magnetocaloric performance and the mechanical processability of the alloy are improved.

Description

Technical Field

[0001] This invention relates to the field of alloy processing technology, and in particular to a processing method for rapidly enhancing the magnetocaloric effect of highly brittle La-Fe-Co-Si rare earth magnetic refrigeration alloys. Background Technology

[0002] In recent years, magnetic refrigeration technology, as an environmentally friendly and low-carbon solid-state refrigeration technology, has attracted widespread attention. It can improve refrigeration efficiency by about 30% without using chemical refrigerants. The basic principle of this technology is to utilize the magnetocaloric effect of magnetic refrigeration materials to cool the device; that is, to achieve refrigeration by utilizing the temperature change generated by the material during a change in magnetic field, which is caused by the change in the magnetic moment within the material. La-Fe-Co-Si alloy is considered one of the most promising room-temperature magnetic refrigeration materials, possessing advantages such as easily adjustable operating temperature range, absence of toxic and harmful elements, high magnetocaloric effect, and low hysteresis loss, showing broad application prospects in refrigeration and energy storage. However, it is difficult to generate La(Fe,Co,Si) with a magnetocaloric effect when preparing this alloy using arc melting and induction melting methods. 13 Instead of producing a magnetocaloric phase, the as-cast La-Fe-Co-Si alloy will generate a non-magnetocaloric α-Fe phase and a La-rich phase. Therefore, the as-cast La-Fe-Co-Si alloy needs to undergo high-temperature heat treatment (above 1273K) for several weeks to achieve the peritectic reaction α-Fe + La-rich phase → La(Fe,Co,Si). 13 To obtain La(Fe,Co,Si). 13 Furthermore, due to the high brittleness and poor strength of La-Fe-Co-Si alloys, they are difficult to machine using traditional methods. Therefore, the difficulty in rapidly improving the magnetocaloric effect and poor machinability have always been the main factors limiting the application of La-Fe-Co-Si alloys.

[0003] Currently, the most common solution is to prepare the alloy into granules or thin plates. Granule preparation mainly employs processes such as ball milling, rotating electrode method, or gas atomization. While these methods can improve the alloy's brittleness to some extent by refining the grains, they cannot suppress component segregation within the granules. A homogenization heat treatment of at least three days is still required to allow the peritectic reaction to fully proceed and achieve the magnetocaloric effect. Thin plate preparation mainly involves mixing La-Fe-Co-Si granules with binders such as resin, low-melting-point alloys, and metals, followed by pressing. Although the addition of binders improves the material's machinability, it significantly reduces thermal conductivity and magnetocaloric properties, thereby reducing magnetocaloric performance. It can be seen that currently used preparation methods cannot simultaneously and significantly improve the magnetocaloric effect and mechanical properties of La-Fe-Co-Si alloys. The main reason is that the above preparation processes cannot induce the peritectic reaction in the alloy, nor can they change the coarse dendritic segregation structure that causes high brittleness. Therefore, developing a processing method to rapidly improve the magnetocaloric effect and machinability of La-Fe-Co-Si alloys is an urgent problem to be solved. In view of this, the present invention is proposed. Summary of the Invention

[0004] The purpose of this invention is to provide a processing method for rapidly improving the magnetocaloric effect of highly brittle La-Fe-Co-Si rare earth magnetic refrigeration alloys. By using a high-temperature, low-strain, and large-deformation compression method under an argon protective atmosphere, the invention effectively solves the problems of difficulty in significantly improving the magnetocaloric properties and high brittleness of La-Fe-Co-Si magnetic refrigeration alloys. This method enables the alloy to rapidly generate a magnetocaloric phase during high-temperature hot compression, thereby improving the alloy's magnetocaloric properties and machinability.

[0005] The technical solution of this invention is:

[0006] A processing method for rapidly enhancing the magnetocaloric effect of highly brittle La-Fe-Co-Si rare earth magnetic refrigeration alloys is proposed. Under an argon protective atmosphere, a high-temperature hot compression technique is employed to enable the highly brittle La-Fe-Co-Si rare earth magnetic refrigeration alloys to achieve high deformation at a low strain rate at high temperatures.

[0007] The aforementioned processing method for rapidly enhancing the magnetocaloric effect of highly brittle La-Fe-Co-Si rare earth magnetic refrigeration alloy, wherein the composition of the highly brittle La-Fe-Co-Si rare earth magnetic refrigeration alloy, by atomic percentage, is La 7.7 Fe 75.3 Co 6.4 Si 10.6 .

[0008] The processing method for rapidly enhancing the magnetocaloric effect of highly brittle La-Fe-Co-Si rare earth magnetic refrigeration alloy includes the following steps:

[0009] (1) Preparation of La using electric arc melting method7.7 Fe 75.3 Co 6.4 Si 10.6 alloy

[0010] Before arc melting, the raw materials are first polished and cleaned to remove the oxide scale on the surface of the pure metal raw materials. Then, a high-precision electronic balance is used to weigh each metal raw material according to the nominal composition of the alloy. The weighed metal raw materials are then placed in the melting furnace. The easily oxidized La and the Si with a higher melting point are placed in the lower layer, Co is placed in the middle layer, and Fe with a lower melting point is placed in the upper layer. The melting furnace is then evacuated to reduce the pressure inside the furnace to 10. -3 Pa, while high-purity argon gas is injected, and the alloy is homogenized by electromagnetic stirring. The entire melting process is repeated 4 to 5 times to obtain button ingots.

[0011] (2) Cutting alloy ingots using wire electrical discharge machining.

[0012] The alloy was cut into cylindrical ingots with a diameter of 8mm × 12mm along the longitudinal direction of the button ingot using wire electrical discharge machining. The ingots were then polished with #240, #400, #800, and #1000 sandpaper until no cutting marks were visible on the surface.

[0013] (3) High-temperature hot compression technology is used to enable the high-brittle La-Fe-Co-Si rare earth magnetic refrigeration alloy to achieve high deformation at a low strain rate at high temperature.

[0014] In the processing method for rapidly improving the magnetocaloric effect of the high-brittle La-Fe-Co-Si rare earth magnetic refrigeration alloy, in step (3), the cut cylindrical ingot is subjected to high-temperature hot compression on an MMS-200 thermal simulation experimental machine, and a NiCr-NiAl thermocouple is spot-welded to the side of the cylindrical ingot using a spot welding machine.

[0015] In the processing method for rapidly improving the magnetocaloric effect of the high-brittle La-Fe-Co-Si rare earth magnetic refrigeration alloy, in step (3), the high-temperature hot compression is carried out under an argon protective atmosphere with an argon flow rate of 10-20 sccm. After heating to the test temperature at a heating rate of 10℃ / s, the temperature is held for 60s before compression begins. After compression deformation, the material is cooled by air cooling.

[0016] The aforementioned processing method for rapidly enhancing the magnetocaloric effect of highly brittle La-Fe-Co-Si rare-earth magnetic refrigeration alloys involves a deformation temperature of 950℃~1050℃ and a strain rate of 0.005s. -1 ~0.01s -1 The deformation is 60% to 80%.

[0017] The design concept of this invention is:

[0018] The processing technology of the high-brittleness rare-earth magnetic refrigeration alloy of this invention is applied to the processing of magnetic refrigeration materials in magnetic refrigerators. It employs a high-temperature hot compression method under an argon protective atmosphere, eliminating the need for subsequent prolonged high-temperature heat treatment. This rapidly enhances the magnetocaloric effect of the alloy during processing. The magnetic refrigeration alloy is composed of La. 7.7 Fe 75.3 Co 6.4 Si 10.6 During high-temperature hot compression, by introducing shear stress in the appropriate direction of the alloy, the protruding atoms move towards a specific orientation. At the same time, a large number of lattice defects such as grain boundaries and unbalanced vacancies are introduced into the alloy, increasing the diffusion coefficient of the alloy and introducing a large amount of elastic energy. Diffusion is carried out by utilizing structural relaxation, thereby promoting the peritectic reaction, inducing the formation of a magnetocaloric phase, rapidly improving the magnetocaloric effect of the alloy, and significantly improving the machinability of the alloy.

[0019] The advantages and beneficial effects of this invention are as follows:

[0020] 1. This invention provides a processing technology for a La-Fe-Co-Si high-brittleness rare-earth magnetic refrigeration alloy, wherein the alloy composition is La. 7.7 Fe 75.3 Co 6.4 Si 10.6 This method utilizes the driving force provided by high-temperature hot compression under an argon protective atmosphere to direct atomic movement, introducing numerous lattice defects such as grain boundaries and unbalanced vacancies. This increases the alloy's diffusion coefficient and introduces a large amount of elastic energy, thereby promoting the intragranular reaction within the alloy, generating a magnetocaloric phase, and rapidly enhancing the alloy's magnetocaloric effect. At 2T, the magnetic cooling capacity can reach over 55 J / kg, and the magnetocaloric phase content can reach over 60 vol.%.

[0021] 2. The processing technology of the high brittle rare earth magnetic refrigeration alloy of the present invention can be applied in the field of magnetic refrigeration, providing theoretical and technical support for rapidly improving the magnetocaloric performance and machinability of magnetic refrigeration materials in magnetic refrigerators. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. It can be seen that the following drawings are only a part of the experimental embodiments. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 In this embodiment, the La-Fe-Co-Si alloy was subjected to a strain rate of 0.005 s⁻¹ at 1000 °C. -1X-ray diffraction patterns before and after hot compression under a deformation of 70%. The horizontal axis 2θ (degree) represents the diffraction angle (°), and the vertical axis Intensity (au) represents the relative intensity.

[0024] Figure 2 In this embodiment, the La-Fe-Co-Si alloy was subjected to a strain rate of 0.005 s⁻¹ at 1000 °C. -1 Scanning electron microscopy (SEM) images of the material before and after hot compression with a deformation of 70%; among which, Figure 2 (a) is a SEM image of the as-cast alloy before hot compression. Figure 2 (b) is a SEM image of the alloy after hot compression at 900°C.

[0025] Figure 3 In this embodiment, the temperature is 1000℃ and the strain rate is 0.005s. -1 The relationship between magnetization (M) and temperature (T) of the alloy after hot compression with a deformation of 70% at 0.02T and 2T.

[0026] Figure 4 shows the results of this embodiment at 1000℃ and a strain rate of 0.005s. -1 The isothermal magnetization curves and magnetic entropy change curves of the alloy after hot compression with a deformation of 70% in the temperature range of 240K to 320K are shown in Figure 4(a). Figure 4(a) shows the isothermal magnetization curve, where the horizontal axis H (T) represents the magnetic field strength and the vertical axis M (emu / g) represents the magnetization intensity. Figure 4(b) shows the magnetic entropy change curve, where the horizontal axis T (K) represents the temperature and the vertical axis ΔS... M (J / kg.K) represents the peak value of magnetic entropy change. Detailed Implementation

[0027] In its specific implementation, the processing technology of the La-Fe-Co-Si high-brittle rare-earth magnetic refrigeration alloy of this invention employs a high-temperature hot compression method under an argon protective atmosphere, eliminating the need for subsequent prolonged high-temperature heat treatment. This rapidly enhances the magnetocaloric effect of the alloy during processing. The magnetic refrigeration alloy is composed of La... 7.7 Fe 75.3 Co 6.4 Si 10.6 (at%). To prevent oxidation during alloy deformation, the entire process was carried out under a protective atmosphere of argon.

[0028] The La-Fe-Co-Si high-brittle rare-earth magnetic refrigeration alloy was processed using a high-temperature hot compression method under an argon protective atmosphere. Specific parameters were as follows: argon flow rate 10–20 sccm, deformation temperature 950℃–1050℃, and strain rate 0.005 s⁻¹. -1 ~0.01s -1The deformation is 60%–80%. It should be noted that by further optimizing the high-temperature hot compression process parameters, a greater number of magnetocaloric phases are formed, resulting in higher magnetocaloric performance. Processing the La-Fe-Co-Si high-brittle rare-earth magnetic refrigeration alloy within the above parameter range effectively ensures the alloy's magnetocaloric effect. In other embodiments of the invention, the process parameters can be adjusted as needed.

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. It is obvious that what is described is only a part of the embodiments, and not all of them. Below, the processing method of the La-Fe-Co-Si high-brittleness rare-earth magnetic refrigeration alloy provided by the embodiments of the present invention will be specifically described.

[0030] Example 1

[0031] This embodiment provides a processing method for a La-Fe-Co-Si highly brittle rare-earth magnetic refrigeration alloy, which is obtained through the following processing steps:

[0032] (1) Preparation of La using electric arc melting method 7.7 Fe 75.3 Co 6.4 Si 10.6 alloy

[0033] Before arc melting, the raw materials are first polished and cleaned to remove the oxide scale on the surface of the pure metal raw materials. Then, a high-precision electronic balance is used to weigh each metal raw material according to the nominal composition of the alloy. The weighed metal raw materials are then placed in the melting furnace. The easily oxidized La and the Si with a higher melting point are placed in the lower layer, Co is placed in the middle layer, and Fe with a lower melting point is placed in the upper layer. The melting furnace is then evacuated to reduce the pressure inside the furnace to 10. -3 Pa, while simultaneously introducing high-purity argon gas (volume purity 99.999%), and achieving alloy homogenization through electromagnetic stirring. The entire melting process is repeated 5 times to obtain button ingots.

[0034] (2) Cutting alloy ingots using wire electrical discharge machining.

[0035] The alloy was cut into cylindrical ingots of Φ8mm×12mm along the longitudinal direction of the button ingot using wire electrical discharge machining. The ingots were then polished with #240, #400, #800, and #1000 sandpaper until no cutting marks were visible on the surface.

[0036] (3) High-temperature hot compression technology is used to enable the high-brittle La-Fe-Co-Si rare earth magnetic refrigeration alloy to achieve high deformation at a low strain rate at high temperature. The cut cylindrical ingot is subjected to high-temperature hot compression test on MMS-200 thermodynamic simulation test machine, and NiCr-NiAl thermocouple is spot welded to the side of the cylindrical ingot using a spot welding machine.

[0037] The test was conducted under an argon protective atmosphere with an argon flow rate of 15 sccm. The temperature was increased to the test temperature at a heating rate of 10℃ / s, held for 60 seconds, and then compression began. The compressed and deformed sample was cooled by air cooling. The process parameters for high-temperature hot compression were: deformation temperature 1000℃, strain rate 0.005s. -1 The deformation was 70%, and the magnetic cooling capacity at 2T was 61J / kg.

[0038] Example 2

[0039] This embodiment provides a processing method for a La-Fe-Co-Si highly brittle rare-earth magnetic refrigeration alloy, which differs from Embodiment 1 only in that:

[0040] In step (3), the test was conducted under an argon protective atmosphere with an argon flow rate of 15 sccm. The temperature was increased to the test temperature at a heating rate of 10℃ / s, held for 60 seconds, and then compression began. The compressed and deformed sample was cooled by air cooling. The process parameters for high-temperature hot compression were: deformation temperature of 900℃ and strain rate of 0.005 s⁻¹. -1 The deformation amount is 70%, which is not enough to enable the alloy to acquire magnetic cooling capability. The reason is that at this deformation temperature, there is not enough driving force for atomic diffusion, so the peritectic reaction cannot be induced, and therefore the 1:13 magnetocaloric phase cannot be generated.

[0041] Example 3

[0042] This embodiment provides a processing method for a La-Fe-Co-Si highly brittle rare-earth magnetic refrigeration alloy, which differs from Embodiment 1 only in that:

[0043] In step (3), the test was conducted under an argon protective atmosphere with an argon flow rate of 15 sccm. The temperature was increased to the test temperature at a heating rate of 10℃ / s, held for 60 seconds, and then compression began. The compressed and deformed sample was cooled by air cooling. The process parameters for high-temperature hot compression were: deformation temperature of 1100℃ and strain rate of 0.005 s⁻¹. -1 The deformation amount is 70%, which cannot enable the alloy to acquire magnetic refrigeration capability. The reason is that at this deformation temperature, α-Fe will grow significantly due to obvious recrystallization, which inhibits the peritectic reaction and thus cannot generate a 1:13 magnetocaloric phase.

[0044] Example 4

[0045] This embodiment provides a processing method for a La-Fe-Co-Si highly brittle rare-earth magnetic refrigeration alloy, which differs from Embodiment 1 only in that:

[0046] In step (3), the test was conducted under an argon protective atmosphere with an argon flow rate of 15 sccm. The temperature was increased to the test temperature at a heating rate of 10℃ / s, held for 60 seconds, and then compression began. The compressed and deformed sample was cooled by air cooling. The process parameters for high-temperature hot compression were: deformation temperature 1020℃, strain rate 0.005s. -1 The deformation was 70%, and the magnetic cooling capacity at 2T was 58J / kg.

[0047] Example 5

[0048] This embodiment provides a processing method for a La-Fe-Co-Si highly brittle rare-earth magnetic refrigeration alloy, which differs from Embodiment 1 only in that:

[0049] In step (3), the test was conducted under an argon protective atmosphere with an argon flow rate of 15 sccm. The temperature was increased to the test temperature at a heating rate of 10℃ / s, held for 60 seconds, and then compression began. The compressed and deformed sample was cooled by air cooling. The process parameters for high-temperature hot compression were: deformation temperature of 1000℃ and strain rate of 0.008 s⁻¹. -1 The deformation was 70%, and the magnetic cooling capacity at 2T was 55J / kg.

[0050] Example 6

[0051] This embodiment provides a processing method for a La-Fe-Co-Si highly brittle rare-earth magnetic refrigeration alloy, which differs from Embodiment 1 only in that:

[0052] In step (3), the test was conducted under an argon protective atmosphere with an argon flow rate of 15 sccm. The temperature was increased to the test temperature at a heating rate of 10℃ / s, held for 60 seconds, and then compression began. The compressed and deformed sample was cooled by air cooling. The process parameters for high-temperature hot compression were: deformation temperature of 1000℃ and strain rate of 0.02 s⁻¹. -1 The deformation was 70%, and the alloy fractured during compression. The reason is that due to the intrinsic brittleness of the material, when the strain rate is too fast, a large stress concentration will be generated at the grain boundary, which will lead to the rapid initiation and propagation of cracks and thus fracture.

[0053] Example 7

[0054] This embodiment provides a processing method for a La-Fe-Co-Si highly brittle rare-earth magnetic refrigeration alloy, which differs from Embodiment 1 only in that:

[0055] In step (3), the test was conducted under an argon protective atmosphere with an argon flow rate of 15 sccm. The temperature was increased to the test temperature at a heating rate of 10℃ / s, held for 60 seconds, and then compression began. The compressed and deformed sample was cooled by air cooling. The process parameters for high-temperature hot compression were: deformation temperature of 1000℃ and strain rate of 0.005 s⁻¹. -1 The deformation amount is 50%, which cannot enable the alloy to acquire magnetic cooling capacity. The reason is that when the deformation amount is too low, it is impossible to introduce enough elastic energy into the material system during the plastic deformation process, and it is impossible to induce structural relaxation, thereby failing to promote the peritectic reaction and thus failing to form a 1:13 phase.

[0056] Example 8

[0057] This embodiment provides a processing method for a La-Fe-Co-Si highly brittle rare-earth magnetic refrigeration alloy, which differs from Embodiment 1 only in that:

[0058] In step (3), the test was conducted under an argon protective atmosphere with an argon flow rate of 15 sccm. The temperature was increased to the test temperature at a heating rate of 10℃ / s, held for 60 seconds, and then compression began. The compressed and deformed sample was cooled by air cooling. The process parameters for high-temperature hot compression were: deformation temperature of 1000℃ and strain rate of 0.005 s⁻¹. -1 The deformation was 80%, and the magnetic cooling capacity at 2T was 70J / kg.

[0059] Reference Figure 1 As shown, the thermally compressible state of La 7.7 Fe 75.3 Co 6.4 Si 10.6 The XRD results of the alloy showed that only diffraction peaks of the La-rich phase and α-Fe phase were present in the as-cast alloy, and no diffraction peaks of the magnetocaloric phase were present. At this time, the material had no magnetocaloric properties. After the alloy was subjected to high-temperature hot compression deformation, XRD tests on the alloy obtained in Example 1 showed that obvious magnetocaloric phase (1:13 phase) diffraction peaks appeared in the microstructure. Using RIR calculation, the content of the magnetocaloric phase could reach ~70 vol.%.

[0060] Reference Figure 2 As shown, the thermally compressible state of La 7.7 Fe 75.3 Co 6.4 Si 10.6 Backscattered scan image of the alloy, wherein: Figure 2 (a) shows the microstructure of the as-cast alloy before hot compression deformation. The microstructure contains only La-rich phase (light gray phase) and α-Fe phase (black phase). The results of backscattering analysis of the alloy obtained in Example 1 are as follows: Figure 2As shown in (b), the content of La-rich phase and α-Fe phase in the tissue is significantly reduced, while a large amount of magnetocaloric phase (dark gray phase) is formed.

[0061] Reference Figure 3 As shown, the thermally compressible state of La 7.7 Fe 75.3 Co 6.4 Si 10.6 The magnetization of the alloy at 0.02T and 2T is shown as a function of temperature. The inset shows the first derivative of the magnetization (δM / δT) as a function of temperature. It can be seen that the magnetization of the alloy decreases significantly between 255K and 315K under increasing temperature, indicating that the alloy changes from a paramagnetic state to a ferromagnetic state at this time. The Curie temperature corresponds to the temperature at which the absolute value of δM / δT is maximized, which is 284K.

[0062] Referring to Figure 4, the thermally compressed La 7.7 Fe 75.3 Co 6.4 Si 10.6 The isothermal magnetization and magnetic entropy change curves of the alloy within the magnetic phase transition temperature range of 240K–320K are shown in Figure 4(a). As can be seen from Figure 4(a), the isothermal magnetization curve does not exhibit the "S"-shaped characteristic of a first-order phase transition, and no magnetic hysteresis occurs during magnetic field cycling, indicating that the alloy undergoes a second-order phase transition. This alloy exhibits no energy loss during cyclic operation. Using Maxwell's equations… The calculated magnetic entropy change curve is shown in Figure 4(b). The alloy has a half-width at half-maximum of 60 K at 2 T and a peak magnetic entropy change of 1.05 J / kg·K. Therefore, the theoretical magnetic refrigeration capacity that the material can provide is... It is 61 J / kg.

[0063] For anyone skilled in the art, many possible variations and modifications can be made to the technical solutions of this invention, or equivalent embodiments can be modified based on the disclosed technical content, without departing from the scope of the technical solutions of this invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this invention without departing from the content of the technical solutions of this invention should still fall within the protection scope of the technical solutions of this invention.

Claims

1. A processing method for rapidly improving the magneto-caloric effect of high brittleness La-Fe-Co-Si rare earth magnetic refrigeration alloy, characterized in that, Under an argon protective atmosphere, a high-temperature hot compression technique was employed to achieve high deformation of the highly brittle La-Fe-Co-Si rare-earth magnetic refrigeration alloy at a low strain rate at high temperatures; the deformation temperature was 950℃ ~ 1050℃, and the strain rate was 0.005 s⁻¹. -1 ~0.01 s -1 The deformation is 60% to 80%.

2. The method for rapidly enhancing the magneto-caloric effect of high brittleness La-Fe-Co-Si rare earth magnetic refrigeration alloy according to claim 1, characterized in that, The composition of the high brittleness La-Fe-Co-Si rare earth magnetic refrigeration alloy is La 7.7 Fe 75.3 Co 6.4 Si 10.6 .

3. The method for rapidly enhancing the magneto-caloric effect of high brittleness La-Fe-Co-Si rare earth magnetic refrigeration alloy according to claim 1, characterized in that, Comprising the following steps: (1) La 7.7 Fe 75.3 Co 6.4 Si 10.6 alloys prepared by arc melting Before arc melting, the raw materials are polished and cleaned to remove the oxide skin on the surface of the pure metal raw materials. Then, the high-precision electronic balance is used to weigh each metal raw material according to the nominal composition of the alloy. The weighed metal raw materials are placed in the melting furnace. The easily oxidizable La and the Si with a high melting point are placed in the lower layer, the Co is placed in the middle layer, and the Fe with a low melting point is placed in the upper layer. The furnace is vacuumized to reduce the pressure in the furnace to 10 -3 Pa, high-purity argon is injected at the same time, the alloy is homogenized by electromagnetic stirring, and the whole melting process is repeated 4-5 times to obtain a button ingot. (2) Cutting alloy ingot by wire cut electrical discharge machining Cutting the alloy into Φ 8 mm x 12 mm cylindrical ingot along the longitudinal direction of the button ingot by wire cut electrical discharge machining, and polishing the cylindrical ingot surface to no wire cutting traces by using #240, #400, #800, #1000 sandpaper in turn; (3) Using high temperature hot compression technology, the high brittle La-Fe-Co-Si rare earth magnetic refrigeration alloy reaches high deformation at high temperature with low strain rate.

4. The method for rapidly enhancing the magneto-caloric effect of high brittleness La-Fe-Co-Si rare earth magnetic refrigeration alloy according to claim 3, characterized in that, In step (3), the cut cylindrical ingot is subjected to high temperature hot compression operation on the MMS-200 thermal simulation testing machine, and the NiCr-NiAl thermocouple is spot welded on the side surface of the cylindrical ingot.

5. The method for rapidly enhancing the magneto-caloric effect of high brittleness La-Fe-Co-Si rare earth magnetic refrigeration alloy according to claim 3, characterized in that, In step (3), the high temperature hot compression is carried out in an argon protective atmosphere, the argon flow rate is 10-20 sccm, the temperature is raised at a heating rate of 10℃ / s to the test temperature, and after holding for 60 s, compression is started, and after deformation, cooling is carried out in the form of air cooling.

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