Primary phase change magnetic refrigeration alloy material and preparation method thereof

Abstract

The invention discloses a primary phase change magnetic refrigeration alloy material and a preparation method thereof, the chemical formula of the alloy material is La0. 9Pr0. 1Fe12B6, and the alloy material has magnetocrystalline coupling and magnetoelastic coupling properties at the same time. The preparation method comprises the following steps: 1, preparing raw materials according to the chemical formula of the alloy material, and melting the prepared raw materials in a tungsten electrode non-consumable electric arc furnace to obtain an alloy ingot sample; and secondly, the ingot casting sample is subjected to heat treatment, and the La0. 9Pr0. 1Fe12B6 alloy material is obtained. According to the invention, the chemical formula of La1-xPrxFe12B6 is reasonably designed, the primary phase change magnetic refrigeration La1-xPrxFe12B6 alloy material with a lower critical magnetic field of magnetic field induced variable magnetic phase change is realized, and the material also has double coupling properties of magnetocrystalline coupling and magnetoelastic coupling.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic refrigeration materials, and in particular to a primary phase change magnetic refrigeration alloy material and a preparation method thereof. Background Art

[0002] The first-order phase change magnetocaloric materials have changes in crystal structure or discontinuous changes in unit cell size during the magnetic phase change process, which is commonly known as magnetocrystalline coupling or magnetoelastic coupling. Since the magnetic disorder-order transition induced by the magnetic field of such materials belongs to the first-order magnetic phase change, there is an obvious step in its isothermal magnetization curve, that is, a sudden change in magnetization intensity, which leads to the giant magnetocaloric effect (GMCE) of the first-order phase change magnetocaloric materials, and therefore they have attracted extensive attention in the field of magnetic refrigeration research.

[0003] In LaFe 12 In the B6 touring electron system, low-temperature AFM-FM (antiferromagnetic-ferromagnetic) and high-temperature PM-FM (paramagnetic-ferromagnetic) magnetic phase transitions caused by FIMT (field-induced magnetic phase transition) were observed. For example, at 2K, there were two mutations from low magnetic field intensity to high magnetization intensity with critical magnetic fields of 71.5kOe and 92.5kOe respectively. Above the Curie temperature, there was also a mutation in the magnetization intensity of PM-FM, which is a typical feature of the first-order magnetic phase transition. 12 The special magnetic phase transition and good magnetocaloric effect in B6 alloy have attracted extensive attention from researchers. These studies mainly focus on two aspects, namely 1) how to reduce the critical magnetic field of magnetic field-induced magnetic phase transition so that it can produce a larger magnetocaloric or magnetoresistance effect under a lower magnetic field; 2) observe its low-temperature and high-temperature magnetic phase transition process and properties.

[0004] At present, LaFe 12 There are very few studies on magnetocrystalline coupling or magnetoelastic coupling during the first-order phase transition of B6-based alloys. In addition, there is a technical problem that the giant magnetocaloric effect cannot be achieved because the critical magnetic field of the magnetic field-induced magnetoelastic phase transition is too large and the magnetoelastic phase transition cannot be observed under low fields.

[0005] In view of this, this patent application is filed. Summary of the invention

[0006] In order to solve the current LaFe 12 B6-based alloy has a technical problem that the critical magnetic field of magnetic field-induced magnetic phase transition is too large, and the magnetic phase transition cannot be observed under low field, resulting in the inability to achieve the giant magnetocaloric effect. The present invention provides a first-order phase change magnetic refrigeration alloy material and a preparation method thereof. The alloy material is LaFe 12 B6 alloy as base, with Pr replacing LaFe 12La in B6 alloy affects the Fe-Fe interaction between 3d itinerant electrons and the La / pr 4f-Fe 3d interaction between 3d and 4f electrons, thus achieving first-order phase transition magnetic refrigeration with a lower critical magnetic field of magnetic field-induced magnetic phase transition. 1- x Pr x Fe 12 B6 alloy material, which also has dual coupling properties of magnetocrystalline coupling and magnetoelastic coupling, and the resulting alloy has uniform phase and significant magnetocaloric effect, and can be widely used in the field of magnetic refrigeration technology.

[0007] The present invention is implemented by the following technical solutions:

[0008] The first object of the present invention is to provide a primary phase change magnetic refrigeration alloy material, the chemical formula of the alloy material is La 0.9 Pr 0.1 Fe 12 B6, the alloy material has both magnetocrystalline coupling and magnetoelastic coupling properties.

[0009] In the present invention, Pr is used instead of LaFe 12 La in B6 alloy and rational design of La 1-x Pr x Fe 12 The chemical formula of B6 is to achieve first-order phase change magnetic refrigeration La with a lower critical magnetic field of magnetic field-induced magnetic phase transition by affecting the Fe-Fe interaction between 3d itinerant electrons and the La / pr 4f-Fe 3d interaction between 3d and 4f electrons. 1-x Pr x Fe 12 B6 alloy material can solve the current LaFe 12 The B6-based alloy has the technical problem of too large critical magnetic field and unable to achieve giant magnetocaloric effect. The material also has dual coupling properties of magnetocrystalline coupling and magnetoelastic coupling. The alloy has uniform phase and significant magnetocaloric effect. It can be widely used in the field of magnetic refrigeration technology, providing ideas for the research of dual coupling alloys.

[0010] Due to single-phase RFe 12 The preparation of B6 (R stands for rare earth element) is very difficult, and all RFe 12 B6 alloys all contain a certain amount of impurities. The inventors found that when x = 0, LaFe 12 Fe2B in B6 contains about 8wt.%NdFe 12 The content of α-Fe in B6 is about 23 at.%, and PrFe 12 B6 contains even more α-Fe. When x>0.1, it will lead to La 1-x Prx Fe 12 SrNi in B6 alloy 12 The content of the main phase of the B6 type structure is reduced, exceeding the error analysis range (10%). The ingenious design of x = 0.1 in the present invention can not only ensure that the content of the main phase of the structure is high enough and reduce the critical magnetic field, but also unexpectedly find that the obtained La 0.9 Pr 0.1 Fe 12 The B6 alloy material has a dual coupling property and is a first-order phase change dual-coupled magnetic refrigeration material with a lower critical magnetic field of magnetic field-induced magnetic phase transition, which is not available in current first-order phase change refrigeration materials.

[0011] As a preferred design, the alloy has SrNi 12 B6 type structure main phase.

[0012] As a preferred design, it also has Fe2B mixed phase and / or α-Fe mixed phase.

[0013] As a preferred design, the SrNi 12 The mass percentage of the B6 type structural phase should be higher than (90±1)%, and the mass percentage of the Fe2B and / or α-Fe impurity phase should be lower than (10±1)%, so as to ensure that the material per unit mass has good magnetocaloric efficiency.

[0014] As a preferred design, variable temperature XRD and magnetization measurement are used to determine the magnetic phase change process of the alloy material and the dual coupling of magnetocrystalline coupling and magnetoelastic coupling.

[0015] Specifically, it can be done through the following process:

[0016] Step 1: Test and obtain the zero magnetic field room temperature X-ray powder diffraction pattern (XRD) of the alloy to determine La 0.9 Pr 0.1 Fe 12 The content of each phase in B6 alloy.

[0017] Step 2: Test the alloy's magnetization intensity (M) versus temperature (T) curve under ZFC and FC modes, i.e., MT diagram, to determine the alloy's magnetic phase transition process and magnetic phase transition temperature and type.

[0018] Step 3: Use the ZFC mode to measure the hysteresis loops in the magnetic field range of 0-70-0kOe at different temperatures to determine the magnetic phase transition process between the antiferromagnetic and paramagnetic states in the alloy.

[0019] Step 4: Test and obtain the zero magnetic field temperature X-ray powder diffraction pattern (XRD) of the alloy to determine La 0.9 Pr 0.1 Fe 12The process of temperature-induced magnetic phase transition in B6 alloy and the change of lattice constant with temperature during phase transition.

[0020] Step 5: Test and obtain the alloy's variable temperature X-ray powder diffraction pattern (XRD) under a magnetic field to determine La 0.9 Pr 0.1 Fe 12 Process of magnetic field-induced magnetic phase transition in B6 alloy.

[0021] Step 6: Test the isothermal magnetization curve (MH) of the alloy in the temperature range of 2K-320K and the external magnetic field of 0-7T to further determine the process of magnetic field-induced magnetic phase transition.

[0022] Step 7: Calculate La based on the isothermal magnetization curve and the discretized Maxwell equations 0.9 Pr 0.1 Fe 12 Isothermal magnetic entropy change curve of B6 alloy.

[0023] The present invention uses magnetization measurement and variable temperature XRD experiments to deeply study the magnetic phase transition process of the alloy and the magnetocrystalline coupling and magnetoelastic coupling phenomena contained therein, which has important scientific significance and application value.

[0024] The second object of the present invention is to provide a method for preparing the primary phase change magnetic refrigeration alloy material as described in any one of the above items, comprising the following steps:

[0025] Step 1: Prepare the raw materials according to the chemical formula of the alloy material, and melt the prepared raw materials in a tungsten electrode non-consumable arc furnace to obtain an alloy ingot sample;

[0026] Step 2: Heat treat the ingot sample to obtain La 0.9 Pr 0.1 Fe 12 Material: B6 alloy.

[0027] As a preferred design, during the preparation process, 3% of the mass of La and Pr in the normal stoichiometric ratio needs to be added for melting loss to prepare the sample.

[0028] As a preferred design, in step 2, the ingot sample is wrapped with a metal Ta sheet, sealed in a small quartz tube filled with high-purity argon gas, and then placed in a tube furnace for heat treatment to obtain an alloy material with uniform composition.

[0029] As a preferred design, the heat treatment is to keep the temperature at 900° C. for 4 weeks.

[0030] As a preferred design, the heat treatment further includes ice water quenching after the heat preservation treatment. During the quenching process, the ice water is always kept in a mixed state, and the small quartz tube is ensured to be completely submerged in the ice water without being broken. After the sample completely reaches the ice water temperature, the small quartz tube can be taken out, and the sample can be taken out after being broken.

[0031] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0032] The present invention rationally designs La 1-x Pr x Fe 12 B6 chemical formula, achieved a first-order phase change magnetic refrigeration La with a lower critical magnetic field of magnetic field-induced magnetic phase transition 1-x Pr x Fe 12 B6 alloy material can solve the current LaFe 12 The B6-based alloy has the technical problem of too large critical magnetic field and unable to achieve giant magnetocaloric effect. The material also has dual coupling properties of magnetocrystalline coupling and magnetoelastic coupling. The alloy has uniform phase and significant magnetocaloric effect. It can be widely used in the field of magnetic refrigeration technology, providing ideas for the research of dual coupling alloys. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0034] Figure 1 It's La 0.9 Pr 0.1 Fe 12 Room temperature XRD pattern of B6 alloy.

[0035] Figure 2 It's La 0.9 Pr 0.1 Fe 12 MT curves of B6 alloy under different magnetic fields using ZFCW (zero-field cooling and heating measurement) and FCC (field cooling measurement) modes, a1 represents the MT curve in ZFCW mode, and a2 represents the MT curve in FCC mode.

[0036] Figure 3 It's La 0.9 Pr 0.1 Fe 12dM / dT curves of MT curves in ZFCW and FCC modes of B6 alloy. b1 is the dM-dT curve in ZFCW mode with a temperature range of 5 to 30 kOe, b2 is the dM-dT curve in ZFCW mode with a temperature range of 30 to 70 kOe, and b3 is the dM-dT curve in FC mode at different temperatures.

[0037] Figure 4 It's La 0.9 Pr 0.1 Fe 12 Isothermal magnetization measurement curves of B6 alloy in the process of changing magnetic field from 0 to 70 kOe to 0. a~f are the isothermal magnetization measurement curves at T = 2, 5, 10, 30, 40, and 50 k, respectively.

[0038] Figure 5 It's La 0.9 Pr 0.1 Fe 12 XRD patterns of B6 alloy at different temperatures under zero field (a), and the curve of alloy lattice constant changing with temperature at the corresponding temperature (b).

[0039] Figure 6 It's La 0.9 Pr 0.1 Fe 12 Zero-field and 30kOe magnetic field XRD patterns of B6 alloy at 40K and 60K, (a) corresponds to 40K, and (b) represents 60K.

[0040] Figure 7 It's La 0.9 Pr 0.1 Fe 12 Isothermal magnetic entropy change curves of B6 alloy under different magnetic fields (ΔS M -T), a1, a2, a3 are ΔS from 2K to 42K, 46K to 86K, 90K to 130K respectively M -T curve.

[0041] Figure 8 For La 0.9 Pr 0.1 Fe 12 Isothermal magnetic entropy change curve of B6 alloy. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments. The illustrative embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0043] The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of the particular range. The range defined in this way can be inclusive or exclusive of the end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 60 to 120 and 80 to 110 is listed for a particular parameter, it is understood that a range of 60 to 110 and 80 to 120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following ranges can all be expected: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4 and 2 to 5. In the present application, unless otherwise specified, the numerical range "a to b" represents an abbreviation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0044] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0045] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0046] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0047] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0048] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0049] The following combination Figure 1 , 2 , 3, 4, 5, 6, and 7 illustrate the specific implementation method of this invention.

[0050] Example:

[0051] A magnetic refrigeration alloy having both magnetocrystalline coupling and magnetoelastic coupling properties is prepared by the following method:

[0052] Step 1: Use rare earth La (purity 99.98wt.%) and Pr (purity 99.98wt.%), and commercial grade Fe (99.95wt.%) and B (99.9wt.%) purchased from AlfaAeser, and consider 3% of the mass of La and Pr as melting loss according to the normal stoichiometric ratio for sample matching, and remelt 6 times in a tungsten electrode non-consumable arc furnace filled with high-purity argon to obtain an ingot sample;

[0053] Step 2: Wrap the sample with a metal Ta sheet, seal it in a small quartz tube filled with high-purity argon, and place it in a tubular furnace for heat treatment. The heat treatment mechanism process is: keep it at 900°C for 4 weeks, and then quench it with ice water (without breaking the quartz tube); keep the ice and water mixed during the quenching process, and ensure that the small quartz tube is completely submerged in the ice water without breaking it. After the sample has completely reached the ice water temperature, the small quartz tube can be taken out, and the sample can be taken out after breaking it.

[0054] Step 3: Use Philips X'Pert Pro diffractometer (copper target, containing Kα1 ray) powder diffraction test, where the scanning angle is 2θ=10°~70° and the step is 0.02° to obtain the room temperature X-ray powder diffraction pattern (XRD) of the alloy. Jade6.0 software is used to determine the hexagonal SrNi in the sample through the Retiveld refinement method. 12 The content of B6 type structure main phase and Fe2B and α-Fe miscellaneous components is shown in Figure 1 . SrNi alloy 12 The mass percentage of the B6 type structural phase is in the range of (90±1)%, and the mass percentage of impurity phases such as Fe2B and α-Fe is in the range of (10±1)%.

[0055] Step 4: Using a superconducting quantum interference magnetometer (SQUID, MPMS XL), the temperature range is 2K-300K, the magnetic field changes in the range of 0.1-70kOe, and the MT curves of magnetization intensity changing with temperature under zero field cooling and heating (ZFCW) and field cooling (FC) are shown in Figure 4. Figure 2 , and obtain the corresponding dM-dT curve by differentiation method to determine the phase transition process and phase transition temperature of the alloy. Figure 3 . It can be seen that: in the low temperature part of the alloy material of the present invention under the ZFC mode, there is a step-shaped transition from an antiferromagnetic state to a ferromagnetic state under a low field, and another step-shaped transition from an antiferromagnetic state to a ferromagnetic state under a high field; in the high temperature part of the curve, there is a step-shaped ferromagnetic and paramagnetic phase transition near the Curie temperature. Under the FC mode, there is only one step-shaped transition from high temperature paramagnetism to ferromagnetism. It can be seen that there are two antiferromagnetic to ferromagnetic phase transitions at low and high fields at low temperatures, and a paramagnetic to ferromagnetic phase transition at high temperatures.

[0056] Step 5: Using a superconducting quantum interference magnetometer (SQUID, MPMS XL), the hysteresis loop of the alloy material of the present invention is measured in the ZFC mode at different temperatures of 2K, 5K, 10K, 30K, 40K, and 50K in the magnetic field range of 0-70-0kOe to determine the magnetic phase transition process of the antiferromagnetic and paramagnetic states in the alloy. Figure 4 It can be seen that in the MH curves of step 5, the step-like shape due to the transition from antiferromagnetism to ferromagnetism will appear at low temperature, accompanied by a certain hysteresis. As the temperature rises, the antiferromagnetic content decreases, the step-like shape gradually becomes less obvious, and the hysteresis also gradually decreases; but when the temperature rises to near the Curie temperature, due to the magnetic field-induced paramagnetism to ferromagnetism, the curve shows an obvious step-like shape again, accompanied by added hysteresis.

[0057] Step 6: Philips X'Pert Pro diffractometer (copper target, containing Kα1 rays) was used to measure the XRD variation under zero magnetic field through Mo target (containing Kα1 and Kα2 rays). During the test, the sample was first cooled to 70KK, and then an X-ray test in the range of 2θ=10°-70° was performed. After the test, the sample was cooled to 60K, and then XRD was performed at 60K, 55K, 50K, 45K, 40K, 35K, 30K, 25K, 20K, 15K, 10K and other temperatures. Jade6.0 software was then used to determine the hexagonal SrNi in the sample through the Retiveld refinement method. 12 The relationship between the lattice constant of the main phase of the B6-type structure and the temperature change is used to determine the lattice constant mutation from paramagnetism to ferromagnetism, and from ferromagnetism to paramagnetism. Figure 5It can be seen that in the zero-magnetic field variable temperature XRD of the alloy in step six, when the temperature changes from high temperature to low temperature, when the temperature drops to a certain value, a new diffraction peak will appear in the spectrum, and as the temperature decreases, the intensity of the new diffraction peak gradually increases. At the same time, during the phase transition, the lattice constant has a sudden change from antiferromagnetism to ferromagnetism, and from paramagnetism to ferromagnetism, that is, the lattice constant has a discontinuous change at the phase transition temperature.

[0058] Step 7: Using the method in step 6 as above, test the XRD of the alloy at 60K and 40K under a 30kOe magnetic field, and compare it with the zero-field XRD at the corresponding temperature. That is, compared with the case of no field at 60K, the new diffraction peak appears due to the magnetic field-induced magnetic phase transition when the field is added; at 40K, the intensity of the new diffraction peak under the field is higher than that of the diffraction peak without the field, as shown in FIG. Figure 6 It can be seen that in the alloy plus magnetic field temperature change XRD, when the magnetic field reaches a certain value, a new diffraction peak will appear, and with the increase of the magnetic field, the intensity of the new diffraction peak will gradually increase.

[0059] Step 8: Use a superconducting quantum interference magnetometer (SQUID, MPMS XL) to measure the isothermal magnetization curves in the magnetic field range of 0-70 at 2K, 5K, 10K, 30K, 40K, and 50K using the ZFC mode to determine the isothermal magnetization phase transition process of the alloy. Figure 7 It can be seen that in the MH curve of step 8, a step-like shape appears at low temperature due to the transition from antiferromagnetism to ferromagnetism. As the temperature rises, the antiferromagnetic content decreases and the step-like shape gradually becomes less obvious. However, when the temperature rises to near the Curie temperature, the curve shows obvious steps again due to the magnetic field-induced paramagnetism to ferromagnetism transition.

[0060] Step 9: Based on the isothermal magnetization curve in step 8, combined with the discretized Maxwell equations, calculate La 0.9 Pr 0.1 Fe 12 Isothermal magnetic entropy change curve of B6 alloy, see Figure 8 It can be seen that: the ΔS of the alloy in step nine M The (T)-T curve shows two peaks of opposite positive and negative values, one is a smaller negative entropy change peak caused by the ordered phase transition from antiferromagnetism to ferromagnetism at low temperature, and the other is a larger positive diffraction peak caused by the magnetic field-induced paramagnetic to ferromagnetic phase transition.

[0061] The present invention verifies La by means of variable temperature X-ray powder diffraction in zero magnetic field and magnetic field in step 3 to step 9, as well as magnetization measurement in isothermal variable magnetization and isofield variable temperature. 0.9 Pr 0.1 Fe 12During the magnetoelastic phase transition between magnetic order and magnetic disorder in the main phase of the B6 alloy, magnetocrystalline coupling and magnetoelastic coupling phenomena exist simultaneously. The obtained alloy has a uniform phase and a low critical magnetic field. The magnetoelastic phase transition can also be observed under low fields. The magnetocaloric effect is significant and can be widely used in the field of magnetic refrigeration technology. The proposed alloy preparation and characterization method can provide important core technologies and related parameters for promoting the exploration of dual-coupled first-order phase transition magnetoelastic materials.

[0062] The above specific implementation methods further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific implementation methods of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A primary phase change magnetic refrigeration alloy material, characterized in that: The chemical formula of the alloy material is La 0.9 Pr 0.1 Fe 12 B6, the alloy material has both magnetocrystalline coupling and magnetoelastic coupling properties.

2. The primary phase change magnetic refrigeration alloy material according to claim 1, characterized in that: The alloy contains SrNi 12 B6 type structure main phase.

3. The primary phase change magnetic refrigeration alloy material according to claim 2, characterized in that: It also has Fe2B mixed phase and / or α-Fe mixed phase.

4. The primary phase change magnetic refrigeration alloy material according to claim 3, characterized in that: The SrNi 12 The mass percentage of B6 type structural phase is (90±1)%, and the mass percentage of Fe2B and / or α-Fe impurity phase is (10±1)%.

5. A primary phase change magnetic refrigeration alloy material according to any one of claims 1 to 4, characterized in that: The magnetic phase transition process of the alloy material and the dual coupling of magnetocrystalline coupling and magnetoelastic coupling are determined by variable temperature XRD and magnetization measurement.

6. The method for preparing a primary phase change magnetic refrigeration alloy material according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1: Prepare the raw materials according to the chemical formula of the alloy material, and melt the prepared raw materials in a tungsten electrode non-consumable arc furnace to obtain an alloy ingot sample; Step 2: Heat treat the ingot sample to obtain La 0.9 Pr 0.1 Fe 12 Material: B6 alloy.

7. The method for preparing a primary phase change magnetic refrigeration alloy material according to claim 6, characterized in that: During the preparation process, 3% of the mass of La and Pr in the normal stoichiometric ratio needs to be added for melting loss for sample preparation.

8. The method for preparing a primary phase change magnetic refrigeration alloy material according to claim 6, characterized in that: In step 2, the ingot sample is wrapped with a metal Ta sheet, sealed in a small quartz tube filled with high-purity argon gas, and then placed in a tube furnace for heat treatment to obtain an alloy material with uniform composition.

9. The method for preparing a primary phase change magnetic refrigeration alloy material according to claim 6, characterized in that: The heat treatment is carried out at 900° C. for 4 weeks.

10. The method for preparing a primary phase change magnetic refrigeration alloy material according to claim 6, characterized in that: The heat treatment further comprises ice water quenching after the heat preservation treatment.

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