Gd-based magnetic refrigeration material, preparation method and application

Abstract

The invention discloses a Gd-based magnetic refrigeration material which is a single-phase (Gd, Er) 3Al2 alloy, the chemical general formula of the Gd < 3-x > Er < x > Al2 is Gd < 3-x > Er < x > Al2, and x is more than or equal to 0 and less than or equal to 0.5. The invention further discloses a preparation method and application of the Gd-based magnetic refrigeration material. The Curie temperature of the alloy is changed by adjusting the proportion of the content of Gd and Er in the magnetic refrigeration material, high magnetocaloric performance is shown within the temperature range of 131 K to 279 K, the material has the characteristics of a secondary magnetic refrigeration material, and the problem that pure metal Gd cannot play a role in refrigeration at the room temperature or below is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of magnetic refrigeration, and in particular relates to a Gd-based magnetic refrigeration material, a preparation method and an application thereof. Background Art

[0002] Refrigeration technology has been widely used in many fields such as healthcare, food industry, energy industry, and aerospace, and has become an important pillar for promoting social progress and scientific and technological development. According to the International Energy Outlook report released by the U.S. Energy Information Administration, refrigeration energy consumption accounts for 40% of global building energy consumption and 17% of global electricity consumption. At present, gas compression refrigeration is a commonly used refrigeration technology, such as air conditioners, refrigerators, freezers, etc. However, gas compression refrigeration often uses hydrofluorocarbons (HFCs) as refrigerants. The global warming potential (GWP) of hydrofluorocarbons is thousands of times that of carbon dioxide, and has a significant greenhouse effect. Therefore, seeking new green and environmentally friendly refrigeration technology has become an important research direction and development trend in the future.

[0003] Compared with gas compression refrigeration technology, magnetic refrigeration is a green, energy-efficient, reliable solid-state refrigeration technology with great application potential. Magnetic refrigeration technology is based on the magnetocaloric effect of magnetic refrigeration materials and uses the Brinton cycle or the Scrin cycle to achieve refrigeration. The magnetocaloric effect refers to the phenomenon of heat absorption and release of magnetic materials in an alternating magnetic field. In 1976, Brown used the metal single substance Gd as a magnetic refrigeration material to prepare the first magnetic refrigerator, which was a milestone in the field of magnetic refrigeration. In the following 40 years, researchers developed reciprocating magnetic refrigerators and rotary magnetic refrigerators, and the performance of magnetic refrigerators has been gradually improved. At present, China, the Netherlands, Switzerland, Germany, Denmark, Spain, France, the United Kingdom, Italy, Japan, Canada, Russia, Slovenia, Poland, Brazil, South Korea and other countries are conducting research on magnetic refrigeration, and more than 60 magnetic refrigerators have been successfully developed worldwide.

[0004] Depending on whether the material undergoes a structural phase change when the magnetic phase change occurs, the magnetic refrigeration materials used in magnetic refrigerators can be divided into primary magnetic refrigeration materials and secondary magnetic refrigeration materials. Compared with primary magnetic refrigeration materials, secondary magnetic refrigeration materials have smaller hysteresis and thermal hysteresis, and a wider magnetic phase change temperature range. Therefore, the secondary magnetic refrigeration material metal Gd has become the preferred material in magnetic refrigerators. However, the Curie temperature of metal Gd is between 293K and 294K. When the temperature is lower than room temperature, metal Gd exhibits a weak magnetocaloric effect. Therefore, a magnetic refrigerator using Gd as a magnetic refrigeration material cannot achieve refrigeration at lower temperatures. Summary of the invention

[0005] The purpose of the present invention is to provide a Gd-based magnetic refrigeration material, a preparation method and a use thereof. By adjusting the ratio of the Gd and Er element contents in the magnetic refrigeration material, the Curie temperature of the alloy is changed, high magnetocaloric performance is exhibited in the temperature range of 131K to 279K, and the material has the characteristics of a secondary magnetic refrigeration material, thereby solving the problem that pure metal Gd cannot play a refrigeration role below room temperature.

[0006] To achieve the above purpose, the technical solution used in the present invention is:

[0007] Gd-based magnetic refrigeration material, single-phase (Gd, Er) 3Al2 alloy, its chemical formula is: Gd 3-x Er x Al2, the range of x is: 0≤x≤0.5.

[0008] Furthermore, the single-phase (Gd, Er)3Al2 alloy has a Zr3Al2 type tetragonal structure.

[0009] Furthermore, the Curie temperature range of the single-phase (Gd, Er)3Al2 alloy is 131K-279K.

[0010] Furthermore, the maximum isothermal magnetic entropy change value of the single-phase (Gd, Er)3Al2 alloy under 0-2T magnetic field change is 4.19J / (kg·K).

[0011] The preparation method of Gd-based magnetic refrigeration material comprises:

[0012] According to Gd 3-x Er x Al2 component configuration raw materials, wherein 0≤x≤0.5, and the purity of Gd, Er, and Al is greater than 99wt%;

[0013] The prepared raw materials are placed in the crucible of the high-frequency induction melting furnace, and the vacuum degree in the high-frequency induction melting furnace is made to reach 1.0×10 -2 Pa; use argon gas with a purity greater than 99% to perform gas washing operation on the high-frequency induction melting furnace, and the number of gas washing operations is 3 times or more;

[0014] Filling the furnace chamber of the high-frequency induction melting furnace with argon gas with a purity greater than 99% so that the atmospheric pressure in the furnace chamber of the high-frequency induction melting furnace is 0.3-0.6 standard atmospheric pressure;

[0015] Turn on the smelting power switch of the high-frequency induction melting furnace, gradually increase the power current of the smelting alloy, and the smelting temperature is 1000K-1800K to completely melt the raw materials. Put the alloy into ice water for quenching to obtain single-phase Gd 3-x Er x Al2 alloy.

[0016] Preferably, GdEr master alloy, metal Gd and metal Al are used as raw materials, and the total content of other impurity elements is less than 1 wt %.

[0017] Preferably, the prepared cast alloy is heat treated under vacuum conditions, the heat treatment temperature is 973K to 1073K, and the vacuum degree is less than 0.5×10 -3 Pa, the heat treatment time is 5 to 7 days.

[0018] Preferably, the alloy is smelted forward and backward 3-5 times to ensure the uniformity of the alloy ingot composition, and the temperature of the ice water for quenching treatment is 269K~272K.

[0019] Preferably, the prepared cast alloys are respectively wrapped with molybdenum foil and packaged in a vacuum chamber with a degree of vacuum of 0.5×10 -3 The packaged quartz tube is placed in a muffle furnace for heat treatment.

[0020] Application of Gd-based magnetic refrigeration materials, single-phase Gd 3-x Er x Al2 alloy is used as Gd-based magnetic refrigeration material in magnetic refrigerators.

[0021] The technical effects of the present invention include:

[0022] 1. The single-phase (Gd, Er)3Al2 alloy of the present invention achieves the change of the alloy Curie temperature by adjusting the ratio of the Gd and Er element contents, exhibits high magnetocaloric properties in the temperature range of 131K to 279K, and has the characteristics of a secondary magnetic refrigeration material, solving the problem that pure metal Gd cannot play a refrigeration role below room temperature.

[0023] Gd-based magnetic refrigeration material with continuously adjustable Curie temperature is single-phase Gd 3-x Er x Al2 alloy, by introducing the substitution of Er atoms in Gd3Al2 alloy, the magnetic phase transition temperature can be continuously adjusted in the temperature range of 131K-279K. 3-x Er x Al2 alloy exhibits higher magnetocaloric effect under low temperature conditions and is suitable for refrigeration in the temperature range of 131K-279K.

[0024] 2. The magnetic hysteresis of the single-phase (Gd, Er)3Al2 alloy of the present invention in an alternating magnetic field is close to 0, and no hysteresis loss is generated; during the heating and cooling process of the magnetic refrigeration material, the thermal hysteresis is close to 0, and no thermal hysteresis loss is generated.

[0025] 3. ΔS of the single-phase (Gd, Er)3Al2 alloy of the present invention M The half-width of the -T curve exceeds 30K, which has the characteristics of a wide operating temperature range.

[0026] 4. Gd provided by the present invention 3-x Er x Al2 magnetic refrigeration material can be used as a secondary refrigeration material for metal Gd.

[0027] The primary stage uses metal Gd to reduce the temperature of the heat exchange fluid to about 280K, and the secondary stage uses single-phase Gd 3-x Er x Al2 alloy further reduces the temperature of the heat exchange fluid, and uses the low-temperature heat exchange fluid to take away the heat of the space that needs to be refrigerated, thereby achieving refrigeration.

[0028] 5. Preparation of Gd provided by the present invention 3-x Er x The method of Al2 magnetic refrigeration material has the advantages of simple process, green and environmental protection, short preparation time, and using metal aluminum as raw material, thus reducing the cost of raw materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the positional occupation of Al atoms (small spheres) and Zr atoms (large spheres) in the Zr3Al2-type tetragonal structure of the present invention;

[0030] Figure 2 The Gd prepared in the embodiment of the present invention 3-x Er x XRD patterns of Al2 (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) magnetic refrigeration materials;

[0031] Figure 3 The Gd prepared in the embodiment of the present invention 3-x Er x The relationship curve between the magnetization intensity M and the temperature T of Al2 (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) magnetic refrigeration material during the heating process under a 0.05T magnetic field;

[0032] Figure 4a The Gd prepared in the embodiment of the present invention 3-x Er x The relationship curve between the magnetization intensity M and the external magnetic field intensity H of Al2 (x = 0) magnetic refrigeration material during magnetization at different temperatures;

[0033] Figure 4b The Gd prepared in the embodiment of the present invention 3-x Er x The relationship curve between the magnetization intensity M and the external magnetic field intensity H of Al2 (x = 0.1) magnetic refrigeration material during magnetization at different temperatures;

[0034] Figure 4cThe Gd prepared in the embodiment of the present invention 3-x Er x The relationship curve between the magnetization intensity M and the external magnetic field intensity H of Al2 (x = 0.2) magnetic refrigeration material during magnetization at different temperatures;

[0035] Figure 4d The Gd prepared in the embodiment of the present invention 3-x Er x The relationship curve between the magnetization intensity M and the external magnetic field intensity H of Al2 (x = 0.3) magnetic refrigeration material during magnetization at different temperatures;

[0036] Figure 4e The Gd prepared in the embodiment of the present invention 3-x Er x The relationship curve between the magnetization intensity M and the external magnetic field intensity H of Al2 (x = 0.4) magnetic refrigeration material during magnetization at different temperatures;

[0037] Figure 4f The Gd prepared in the embodiment of the present invention 3-x Er x The relationship curve between the magnetization intensity M and the external magnetic field intensity H of Al2 (x = 0.5) magnetic refrigeration material during magnetization at different temperatures;

[0038] Figure 5 The Gd prepared in the embodiment of the present invention 3-x Er x The relationship curve between the magnetization intensity M and the external magnetic field intensity H of Al2 (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) magnetic refrigeration material during demagnetization at different temperatures;

[0039] Figure 6a The Gd prepared in the embodiment of the present invention 3-x Er x Arrott curve of Al2(x=0,) magnetic refrigeration material;

[0040] Figure 6b The Gd prepared in the embodiment of the present invention 3-x Er x Arrott curve of Al2 (x = 0.1) magnetic refrigeration material;

[0041] Figure 6c The Gd prepared in the embodiment of the present invention 3-x Er x Arrott curve of Al2 (x = 0.2) magnetic refrigeration material;

[0042] Figure 6d The Gd prepared in the embodiment of the present invention 3-xEr x Arrott curve of Al2 (x = 0.3) magnetic refrigeration material;

[0043] Figure 6e The Gd prepared in the embodiment of the present invention 3-x Er x Arrott curve of Al2 (x = 0.4) magnetic refrigeration material;

[0044] Figure 6f The Gd prepared in the embodiment of the present invention 3-x Er x Arrott curve of Al2 (x = 0.5) magnetic refrigeration material;

[0045] Figure 7 The Gd prepared in the embodiment of the present invention 3-x Er x Isothermal magnetic entropy change ΔS of Al2 (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) magnetic refrigeration materials under 0-1.0T magnetic field M The relationship curve between the temperature T and the

[0046] Figure 8 The Gd prepared in the embodiment of the present invention 3-x Er x Isothermal magnetic entropy change ΔS of Al2 (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) magnetic refrigeration materials in 0-1.5T magnetic field M The relationship curve between the temperature T and the

[0047] Fig. 9 The Gd prepared in the embodiment of the present invention 3-x Er x Isothermal magnetic entropy change ΔS of Al2 (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) magnetic refrigeration materials under 0-2.0T magnetic field M The relationship curve between and temperature T. DETAILED DESCRIPTION

[0048] The following description sufficiently illustrates specific embodiments of the invention to enable those skilled in the art to practice and reproduce the invention.

[0049] like Figure 1 , which is a schematic diagram of the positional occupancy of Al atoms (small spheres) and Zr atoms (large spheres) in the Zr3Al2-type tetragonal structure in this application;

[0050] The term Zr3Al2 tetragonal structure used in the present application refers to a tetragonal lattice structure of a Zr3Al2 compound. Specifically, α=β=γ=90°, a=b≠c, and c / a≈0.91.

[0051] The occupancy of Al atoms and Zr atoms in the Zr3Al2-type tetragonal structure is shown in Table 1.

[0052] Table 1 Occupancy of Al and Zr atoms in Zr3Al2 tetragonal structure

[0053] Al Zr 0.121,0.121,0.213 0,0.5,0.25 0.879,0.879,0.213 0,0.5,0.75 0.379,0.621,0.713 0.5,0,0.25 0.621,0.379,0.713 0.5,0,0.75 0.379,0.621,0.287 0.343,0.343,0 0.621,0.379,0.287 0.657,0.657,0 0.121,0.121,0.787 0.157,0.843,0.5 0.879,0.879,0.787 0.843,0.157,0.5 0.199,0.801,0 0.801,0.199,0 0.699,0.699,0.5 0.301,0.301,0.5

[0054] Gd-based magnetic refrigeration material is a single-phase (Gd, Er) 3Al2 alloy, and its chemical formula is: Gd 3-x Er x Al2, the range of x is: 0≤x≤0.5, which is a Zr3Al2 type tetragonal structure.

[0055] The Curie temperature of the single-phase (Gd, Er) 3Al2 alloy ranges from 131K to 279K, and the maximum isothermal magnetic entropy change (ΔS M ) max The value is about 4.19 J / (kg·K).

[0056] This application uses pure metals Gd, Er, and Al as raw materials, smelting them in a smelting furnace and performing a long-term heat treatment in a vacuum environment to prepare a single-phase (Gd, Er)3Al2 magnetic refrigeration material.

[0057] The preparation method of Gd-based magnetic refrigeration material comprises the following specific steps:

[0058] Step 1: Follow Gd 3-x Er x Al2 component configuration raw materials, where 0≤x≤0.5;

[0059] The purity of the raw materials gadolinium Gd, erbium Er, and aluminum Al used is greater than 99% by mass, preferably greater than 99.9% by mass; or GdEr intermediate alloy, metal Gd, and metal Al are used as raw materials, and the total content of other impurity elements is less than 1% by mass, preferably less than 0.1% by mass.

[0060] Step 2: Place the prepared raw materials into the crucible of the high-frequency induction melting furnace, and use a mechanical pump and a molecular pump to evacuate the furnace to a vacuum degree of 1.0×10 -2 Pa; use argon gas with a purity greater than 99% to perform gas washing operation on the high-frequency induction melting furnace, and the number of gas washing operations is 3 times or more;

[0061] Step 3: Filling the furnace chamber of the high-frequency induction melting furnace with argon gas having a purity greater than 99% so that the atmospheric pressure in the furnace chamber of the high-frequency induction melting furnace is 0.3-0.6 standard atmospheric pressure;

[0062] Step 4: Turn on the smelting power switch of the high-frequency induction melting furnace, gradually increase the power current of the smelting alloy, and the smelting temperature is 1000K-1800K to completely melt the raw materials. The alloy is immediately placed in ice water for quenching to obtain single-phase Gd 3-x Er x Al2 alloy.

[0063] The prepared cast alloy was heat treated for a long time under vacuum conditions. The heat treatment temperature was 973K~1073K and the vacuum degree was less than 0.5×10 -3 Pa, the heat treatment time is 5 to 7 days.

[0064] The alloy is smelted forward and backward 3-5 times to ensure the uniformity of the alloy ingot composition. The temperature of the quenching ice water is 269K-272K.

[0065] Single-phase Gd 3-x Er x Al2 alloy is used as Gd-based magnetic refrigeration material in magnetic refrigerators.

[0066] In this example, Gd 3-x Er x Al2 (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) magnetic refrigeration material, the specific process is:

[0067] 1. Strictly follow Gd 3-x Er x Al2 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) alloy components are prepared, and the purity of raw materials Gd, Er, and Al are 99.9wt.%, 99.9wt.%, and 99.99wt.% respectively;

[0068] 2. Place the prepared raw materials into the crucible of the high-frequency induction melting furnace and perform vacuum operation;

[0069] 3. When the vacuum degree reaches 1.0×10 -2 When the pressure is below Pa, use 99.996% high-purity argon gas for three gas washing operations;

[0070] 4. Fill the high-purity argon gas with a purity of 99.996% into the furnace chamber of the high-frequency induction melting furnace, so that the atmospheric pressure of the furnace chamber is 0.5×10 5 Pa;

[0071] 5) Turn on the smelting power supply of the high-frequency induction smelting furnace, and gradually increase the smelting current to completely melt the raw materials Gd, Er, and Al;

[0072] 6. Gd 3-x Er xAl2 (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) alloy ingots were melted forward and reversely for 3 times;

[0073] 7. After smelting, the cast Gd 3-x Er x Al2 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) alloy ingot;

[0074] 8. Prepare the cast Gd 3-x Er x Al2 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) alloy ingots were wrapped with molybdenum foil and packaged in a vacuum chamber with a degree of vacuum of 0.5×10 -3 Pa in a quartz tube;

[0075] 9. Place the packaged quartz tube in a muffle furnace and heat treat it at 1073K for 7 days;

[0076] 10. After the heat treatment is completed, Gd 3-x Er x Al2 (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) alloy ingots were immediately placed in ice water for quenching to obtain single-phase Gd-based magnetic refrigeration samples;

[0077] 11. From the heat-treated Gd 3-x Er x Small pieces were cut from Al2 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) alloy ingots and ground into powder samples with a particle size of less than 300 mesh;

[0078] 12. Test the heat-treated Gd using Philips PW1700 X-ray diffractometer (XRD) 3-x Er x Phase composition of Al2 (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) powder samples, test voltage is 40kW, tube current is 40mA, Cu target, scanning angle range is 20°-90°, scanning speed is 2° / min.

[0079] like Figure 2 As shown, the Gd prepared in the embodiment of the present invention 3-x Er x XRD patterns of Al2 (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) magnetic refrigeration materials.

[0080] XRD test results show that the heat-treated Gd 3-x Er xAl2 (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) has a Zr3Al2-type tetragonal structure and is a single-phase Gd(Er)3Al2 compound.

[0081] 13. From the heat-treated Gd 3-x Er x Small blocks were cut from Al2 (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) alloy ingots, and the heating MT curve and cooling MT curve of the alloy block under a 0.05T magnetic field were measured using a multifunctional (magneto-electro-thermal) vibrating sample magnetometer (Versalab).

[0082] like Figure 3 As shown, the Gd prepared in the embodiment of the present invention 3-x Er x The relationship curve between the magnetization intensity M and temperature T of Al2 (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) magnetic refrigeration material during the heating process under a 0.05T magnetic field.

[0083] The test results show that the heat-treated Gd 3-x Er x The heating MT curve and cooling MT curve of Al2 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) alloy are basically coincident, indicating that the heat-treated Gd 3-x Er x The thermal hysteresis of Al2 (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) alloy is close to 0, and the thermal hysteresis loss caused is 0. Analysis Figure 3 It can be seen that the heat-treated Gd 3-x Er x The Curie temperature of Al2 (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) alloys shows a trend of gradually decreasing with the increase of Er element content, and the Curie temperature ranges from 140K to 280K.

[0084] 14. From the heat-treated Gd 3-x Er x Small blocks were cut from Al2 (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) alloy ingots, and the magnetization MH curves of the alloy blocks were measured using a multifunctional (magneto-electro-thermal) vibrating sample magnetometer (Versalab).

[0085] like Figure 4a As shown, the Gd prepared in the embodiment of the present invention 3-x Er x The relationship curve between the magnetization intensity M and the external magnetic field intensity H of Al2 (x = 0) magnetic refrigeration material during the magnetization process at different temperatures; Figure 4bAs shown, the Gd prepared in the embodiment of the present invention 3-x Er x The relationship curve between the magnetization intensity M and the external magnetic field intensity H of Al2 (x = 0.1) magnetic refrigeration material during the magnetization process at different temperatures; Figure 4c As shown, the Gd prepared in the embodiment of the present invention 3-x Er x The relationship curve between the magnetization intensity M and the external magnetic field intensity H of Al2 (x = 0.2) magnetic refrigeration material during the magnetization process at different temperatures; Figure 4d As shown, the Gd prepared in the embodiment of the present invention 3-x Er x The relationship curve between the magnetization intensity M and the external magnetic field intensity H of Al2 (x = 0.3) magnetic refrigeration material during the magnetization process at different temperatures; Figure 4e As shown, the Gd prepared in the embodiment of the present invention 3-x Er x The relationship curve between the magnetization intensity M and the external magnetic field intensity H of Al2 (x = 0.4) magnetic refrigeration material during the magnetization process at different temperatures; Figure 4f As shown, the Gd prepared in the embodiment of the present invention 3-x Er x The relationship curve between the magnetization intensity M and the external magnetic field intensity H of Al2 (x=0.5) magnetic refrigeration material during the magnetization process at different temperatures.

[0086] like Figure 5 As shown, the Gd prepared in the embodiment of the present invention 3-x Er x The relationship curve between the magnetization intensity M and the external magnetic field intensity H of Al2 (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) magnetic refrigeration material during the demagnetization process at different temperatures.

[0087] Figure 5 The annealed Gd 2.5 Er 0.5 The magnetization MH curve and demagnetization MH curve of Al2 alloy. The experimental results show that the heat-treated Gd 3-x Er x The magnetization MH curve and demagnetization MH curve of Al2(x=0,0.1,0.2,0.3,0.4,0.5) alloy are basically coincident, which indicates that the heat treatment of Gd 3-x Er x The hysteresis of Al2 (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) alloy is close to 0, and it responds quickly to changes in the external magnetic field, making it suitable for the field of magnetic refrigeration.

[0088] 15. Using the obtained MH data, use Origin software to make the heat-treated Gd 3-x Er x Arrott curves of Al2 (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) alloys.

[0089] like Figure 6a As shown, the Gd prepared in the embodiment of the present invention 3-x Er x Arrott curve of Al2(x=0,) magnetic refrigeration material; Figure 6b As shown, the Gd prepared in the embodiment of the present invention 3-x Er x Arrott curve of Al2 (x = 0.1) magnetic refrigeration material; Figure 6c As shown, the Gd prepared in the embodiment of the present invention 3-x Er x Arrott curve of Al2 (x = 0.2) magnetic refrigeration material; Figure 6d As shown, the Gd prepared in the embodiment of the present invention 3-x Er x Arrott curve of Al2 (x = 0.3) magnetic refrigeration material; Figure 6e As shown, the Gd prepared in the embodiment of the present invention 3-x Er x Arrott curve of Al2 (x = 0.4) magnetic refrigeration material; Figure 6f As shown, the Gd prepared in the embodiment of the present invention 3-x Er x Arrott curve of Al2 (x=0.5) magnetic refrigeration material.

[0090] It shows that heat-treated Gd 3-x Er x The slope of the Arrott curve of Al2 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) alloy is positive, indicating that the heat-treated Gd 3-x Er x Al2 (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) alloy is a secondary magnetic phase change material.

[0091] 16. Using the MH data obtained in step 14), use Maxwell's equations

[0092]

[0093] Calculation of heat-treated Gd 3-x Er xΔS of Al2(x=0,0.1,0.2,0.3,0.4,0.5) alloys at 0-1.0T, 0-1.5T, 0-2.0T M -T curve.

[0094] like Figure 7 As shown, the Gd prepared in the embodiment of the present invention 3-x Er x Isothermal magnetic entropy change ΔS of Al2 (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) magnetic refrigeration materials under 0-1.0T magnetic field M and the relationship curve between temperature T; such as Figure 8 As shown, the Gd prepared in the embodiment of the present invention 3-x Er x Isothermal magnetic entropy change ΔS of Al2 (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) magnetic refrigeration materials in 0-1.5T magnetic field M and the relationship curve between temperature T; such as Fig. 9 As shown, the Gd prepared in the embodiment of the present invention 3-x Er x Isothermal magnetic entropy change ΔS of Al2 (x=0, 0.1, 0.2, 0.3, 0.4, 0.5) magnetic refrigeration materials under 0-2.0T magnetic field M The relationship curve between and temperature T.

[0095] Gd3Al2, Gd 2.9 Er 0.1 Al2、Gd 2.8 Er 0.2 Al2、Gd 2.7 Er 0.3 Al2、Gd 2.6 Er 0.4 Al2、Gd 2.5 Er 0.5 The Al2 alloy achieved the maximum isothermal magnetic entropy change at 279K, 255K, 223K, 197K, 163K, and 313K under 0-2.0T magnetic field. M ) max The values ​​are 4.19 J / (kg·K), 4.06 J / (kg·K), 4.16 J / (kg·K), 4.06 J / (kg·K), 4.07 J / (kg·K) and 4.08 J / (kg·K) respectively.

[0096] Compared with metallic Gd, heat-treated Gd 3-x Er xAl2 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) alloys have low Curie temperatures and exhibit higher magnetocaloric effect at their respective Curie temperatures, and are suitable for refrigeration applications in the temperature range of 131K-279K.

[0097] Comparative example: rare earth pure metal Gd

[0098] A typical magnetic refrigeration material, rare earth pure metal Gd, was selected as a comparative example. The MH data of rare earth pure metal Gd in the magnetic field range of 0-2.0T was measured using a multifunctional (magnetoelectrical) vibrating sample magnetometer (Versalab), and the ΔS of rare earth pure metal Gd in the magnetic field range of 0-2.0T was obtained using Maxwell's equations. M -T curve. Isothermal magnetic entropy change ΔS of pure rare earth metal Gd at 140K-280K M The value is lower than 1.5 J / (kg·K).

[0099] The terms used in the present invention are illustrative and exemplary, rather than restrictive. Since the present invention can be implemented in various forms without departing from the spirit or essence of the invention, it should be understood that the above embodiments are not limited to any of the aforementioned details, but should be widely interpreted within the spirit and scope defined by the appended claims, so all changes and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

1. A Gd-based magnetic refrigeration material, characterized in that: Single-phase (Gd, Er) 3Al2 alloy, chemical formula: Gd 3-x Er x Al2, the range of x is: 0≤x≤0.

5.

2. The Gd-based magnetic refrigeration material according to claim 1, characterized in that: The single-phase (Gd, Er)3Al2 alloy has a Zr3Al2 type tetragonal structure.

3. The Gd-based magnetic refrigeration material according to claim 1, characterized in that: The Curie temperature range of single-phase (Gd, Er)3Al2 alloy is 131K-279K.

4. The Gd-based magnetic refrigeration material according to claim 1, characterized in that: The maximum isothermal magnetic entropy change of the single-phase (Gd, Er)3Al2 alloy under 0-2T magnetic field change is 4.19J / (kg·K).

5. The method for preparing the Gd-based magnetic refrigeration material according to any one of claims 1 to 4, characterized in that: include: According to Gd 3-x Er x Al2 component configuration raw materials, wherein 0≤x≤0.5, and the purity of Gd, Er, and Al is greater than 99wt%; The prepared raw materials are placed in the crucible of the high-frequency induction melting furnace, and the vacuum degree in the high-frequency induction melting furnace is made to reach 1.0×10 -2 Pa; use argon gas with a purity greater than 99% to perform gas washing operation on the high-frequency induction melting furnace, and the number of gas washing operations is 3 times or more; Filling the furnace chamber of the high-frequency induction melting furnace with argon gas with a purity greater than 99% so that the atmospheric pressure in the furnace chamber of the high-frequency induction melting furnace is 0.3-0.6 standard atmospheric pressure; Turn on the smelting power switch of the high-frequency induction melting furnace, gradually increase the power current of the smelting alloy, and the smelting temperature is 1000K-1800K to completely melt the raw materials. Put the alloy into ice water for quenching to obtain single-phase Gd 3-x Er x Al2 alloy.

6. The method for preparing the Gd-based magnetic refrigeration material according to claim 5, characterized in that: GdEr master alloy, metal Gd and metal Al are used as raw materials, and the total content of other impurity elements is less than 1wt%.

7. The method for preparing the Gd-based magnetic refrigeration material according to claim 5, characterized in that: The prepared cast alloy was heat treated under vacuum conditions at a temperature of 973K-1073K and a vacuum degree of less than 0.5×10 -3 Pa, heat treatment time is 5-7 days.

8. The method for preparing the Gd-based magnetic refrigeration material according to claim 5, characterized in that: The alloy is smelted forward and backward 3-5 times to ensure the uniformity of the alloy ingot composition. The temperature of the ice water for quenching treatment is 269K-272K.

9. The method for preparing the Gd-based magnetic refrigeration material according to claim 7, characterized in that: The prepared cast alloys were wrapped with molybdenum foil and packaged in a vacuum chamber with a degree of vacuum of 0.5×10 -3 The packaged quartz tube is placed in a muffle furnace for heat treatment.

10. The use of the Gd-based magnetic refrigeration material according to any one of claims 1 to 4, characterized in that: Single-phase Gd 3-x Er x Al2 alloy is used as Gd-based magnetic refrigeration material in magnetic refrigerators.

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