Rare-earth-based high-entropy amorphous alloy, preparation method and application method

Abstract

The invention discloses a rare-earth-based high-entropy amorphous alloy, the chemical general formula of which is GdxDyxErxAlxMx, x is atomic percent, and M is one or more of Fe, Co and Ni. The invention further discloses a preparation method and an application method of the rare-earth-based high-entropy amorphous alloy. According to the GdxDyxErxAlxMx series rare earth-based high-entropy amorphous alloy with the excellent magnetothermal effect, the problems that the phase change temperature span is narrow and the heat loss in a circulating magnetic field is large due to the fact that a crystalline magnetic refrigeration material generates first-stage magnetic transformation at a phase change critical point are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnetic refrigeration of functional materials, and in particular relates to a rare earth-based high-entropy amorphous alloy, a preparation method and an application method. Background Art

[0002] Refrigeration plays an increasingly important role in modern life and has been widely used in home air conditioners, medical equipment, superconducting technology, aerospace and other fields. At present, the commonly used refrigeration technology is gas compression refrigeration, which often uses hydrofluorocarbons as refrigerants. Hydrofluorocarbons are a greenhouse gas with a global warming potential thousands of times that of carbon dioxide. In addition, the energy efficiency of gas compression refrigeration is only 5% to 10% of that of the Carnot cycle. Gas compression refrigeration technology does not meet the development requirements of green environmental protection and high energy efficiency.

[0003] As a solid-state refrigeration technology, magnetic refrigeration has the advantages of environmental friendliness, high energy efficiency, and reliable operation, and has received widespread attention. In 1881, Warburg discovered that the temperature of metallic iron would rise or fall in a changing magnetic field. This phenomenon was later called the magnetocaloric effect, which means that when a magnetic material is in an increasing magnetic field, the internal magnetic moment will be reoriented, the magnetic entropy will decrease, and the lattice entropy will increase, causing its own temperature to rise; when a magnetic material is in a decreasing magnetic field, the magnetic entropy will increase, the lattice entropy will decrease, causing its own temperature to fall. Based on the magnetocaloric effect, magnetic refrigeration uses active magnetic regenerators (AMR) to achieve refrigeration. To date, the research on magnetic refrigeration has mainly focused on the development of magnetic refrigeration materials (magnetic working fluids), the design of magnetic circuits, and the optimization of heat exchange systems. Among them, the development of magnetic refrigeration materials, as a key part, has largely determined the development of magnetic refrigeration. The magnetocaloric effects that characterize magnetic refrigeration materials mainly include phase transition critical point, isothermal magnetic entropy change, adiabatic temperature change, and refrigeration capacity. According to the different atomic arrangements, the magnetic refrigeration materials that have been developed mainly include crystalline and amorphous. Crystalline magnetic refrigeration materials often exhibit advantages such as high phase change critical point and large isothermal magnetic entropy change. However, due to the characteristics of their first-order phase transition, their narrow refrigeration temperature span and low refrigeration capacity limit their practical applications.

[0004] In 2004, Ye Junwei and others proposed a research plan for a new type of alloy. The designed alloy includes multiple elements with similar atomic concentrations, which is later called high entropy alloy. Different from traditional alloys, high entropy alloys exhibit four core effects: high entropy effect, lattice distortion effect, slow diffusion effect, and cocktail effect. They have excellent mechanical properties, phase stability, corrosion resistance, and wear resistance. A large number of studies have shown that high entropy alloys exhibit magnetocaloric effect. Cast Gd 20 Dy 20 Er 20 Ho 20 Tb20 The high entropy alloy has a close-packed hexagonal structure from 20K to room temperature, showing strong structural stability. The critical point of phase transition of this high entropy alloy is 186K, and the maximum isothermal magnetic entropy change at 0-5T is 8.6J kg -1 K -1 , cooling capacity is 627J kg -1 , showing good magnetocaloric effect. However, the problem of narrow phase transition temperature span has not been solved. Studies have shown that due to the special structure of atomic arrangement, amorphous alloys undergo secondary magnetic transition near the critical point, causing the phase transition temperature span to widen. Therefore, the development of high-entropy amorphous alloys with a wide refrigeration temperature span has become a new research direction in the field of magnetic refrigeration. Summary of the invention

[0005] The present invention aims to provide a rare earth-based high entropy amorphous alloy, a preparation method and an application method, and the obtained Gd x Dy x Er x Al x M x It is a rare earth-based high-entropy amorphous alloy, which solves the problems of narrow phase change temperature span and large heat loss in the circulating magnetic field caused by the primary magnetic transition at the critical point of phase change in crystalline magnetic refrigeration materials.

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

[0007] Rare earth-based high entropy amorphous alloy, the general chemical formula is Gd x Dy x Er x Al x M x , x is the atomic percentage, and M is one or more of Fe, Co, and Ni.

[0008] Further, x=20.

[0009] Application method of rare earth based high entropy amorphous alloy for magnetic refrigeration.

[0010] Preferably, a wide refrigeration temperature range is shown at 0-5T, which is Fe: 102K, Co: 63K, and Ni: 59K.

[0011] Preferably, at 0-5T, Gd x Dy x Er x Al x Co x The amorphous alloys exhibit the highest maximum isothermal magnetic entropy change, which is Fe: 6.50 J kg -1 K -1 , Co: 9.59 J kg -1 K -1, Ni: 8.27 J kg -1 K -1 .

[0012] Preferably, the operating temperature range is: Fe: 31-133K, Co: 19-82K, Ni: 23-82K.

[0013] Preferably, the Curie temperatures are Fe:T C =79K, Co:T C =41K, Ni:T C =36K.

[0014] A method for preparing a rare earth-based high-entropy amorphous alloy comprises:

[0015] Accurately weigh metal gadolinium Gd, dysprosium Dy, erbium Er, aluminum Al, iron Fe, cobalt Co, and nickel Ni according to atomic ratio;

[0016] The weighed raw materials are placed in a copper crucible in a vacuum arc melting furnace and evacuated. The vacuum degree in the furnace chamber is less than 5*10 -3 When the furnace pressure reaches 0.5 atmospheres, high-purity argon gas is filled in. Then the metal raw materials are melted by electric arc. After the smelting is completed, the alloy ingot is quickly cooled to room temperature and the furnace is opened for sampling.

[0017] The prepared alloy ingot is crushed and placed in a glass tube, the glass tube containing the alloy block is installed in a belt-spinning furnace, the belt-spinning furnace is evacuated and purged, the alloy block is melted and belt-spinned, and the prepared strip is taken out from the collecting chamber of the belt-spinning furnace to obtain a rare earth-based high-entropy amorphous alloy.

[0018] Preferably, the vacuum degree in the furnace chamber is less than 10 -3 When the temperature reaches 0.0400 Pa, clean the furnace chamber with high-purity argon gas for at least 3 times; turn on the smelting power of the arc furnace, gradually increase the smelting current until all the metal raw materials are melted, keep warm for 5 minutes and then gradually reduce the smelting current. Each alloy ingot is smelted repeatedly for 3 times to ensure the uniformity of the alloy composition; grind the smelted alloy ingot, clean it with alcohol, then break the alloy ingot into blocks and put it into a glass tube; fix the glass in a vacuum belt spinning furnace, adjust the distance between the tube mouth of the glass tube and the copper roller to 1mm, and then adjust the injection pressure; turn on the power switch that controls the speed of the copper roller, wait until the speed of the copper roller reaches 3000 revolutions per minute, turn on the smelting power of the vacuum arc furnace, and gradually increase the current until the alloy block is completely melted; use the pressure difference to spray the alloy melt onto the high-speed rotating copper roller to form a strip with a width of 2mm and a thickness of 20um; turn off the smelting power, open the vent valve until the pressure in the furnace chamber reaches atmospheric pressure, open the furnace door of the vacuum arc furnace, and take out the sample.

[0019] The application method of rare earth-based high entropy amorphous alloy is applied to magnetic refrigerator.

[0020] The technical effects of the present invention include:

[0021] The GdDyErAlM high-entropy amorphous alloy developed by the present invention solves the problems of narrow phase change temperature span and large heat loss in a cyclic magnetic field caused by the primary magnetic transition at the phase change critical point of the crystalline magnetic refrigeration material. It has broad application prospects and special uses in aerospace, medical devices, cryogenic engineering, etc. The preparation process is simple and suitable for mass production.

[0022] 1. Rare earth-based high entropy amorphous alloy Gd prepared by the present invention x D y Er x Al x M x It is a secondary phase change material, M is one of Fe, Co, and Ni, with uniform composition and stable performance. It has a maximum isothermal magnetic entropy change and refrigeration capacity exceeding that of Gd.

[0023] 2. Rare earth-based high entropy amorphous alloy Gd under 0-5T magnetic field x D y Er x Al x M x The maximum isothermal magnetic entropy changes are 6.50 J / kgK, 9.59 J / kgK, and 8.27 J / kgK, and the refrigeration capacities are 519 J / kg, 485 J / kg, and 396 J / kg, respectively.

[0024] 3. The applicable temperature of rare earth-based high-entropy amorphous alloys is adjustable.

[0025] By adjusting the composition of elements, the phase change critical point can be continuously adjusted while ensuring a large magnetocaloric effect, making it suitable for refrigeration in magnetic refrigerators in different temperature ranges.

[0026] 4. Rare earth-based high-entropy amorphous alloys have a large magnetocaloric effect.

[0027] The alloying of the five elements overcomes the disadvantages of single elements such as easy oxidation and poor stability, and has a large isothermal magnetic entropy change. At the same time, it expands the refrigeration temperature span of the material and improves the refrigeration capacity of the material. x Dy x Er x Al x M x The greater the refrigeration capacity of the alloy, the wider its practical application. The introduction of Al, Fe, Co and Ni elements reduces the cost of rare earth-based alloys.

[0028] 5. The preparation method of rare earth-based high-entropy amorphous alloy is simple.

[0029] The preparation of the rare earth-based high-entropy amorphous alloy only requires a vacuum arc furnace and a vacuum belt-spinning furnace. The process is mature and only requires controlling the current during the vacuum arc furnace melting process and the current during the belt-spinning process of the vacuum belt-spinning furnace. The process flow is simple.

[0030] 6. The raw material cost for the preparation of rare earth-based high-entropy amorphous alloys is low.

[0031] The introduction of metal aluminum Al, iron Fe, cobalt Co, and nickel Ni reduces the cost of rare earth-based magnetic refrigeration materials and improves practical application capabilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is the Gd prepared in the embodiment of the present invention 20 Dy 20 Er 20 Al 20 Fe 20 , Gd 20 Dy 20 Er 20 Al 20 Co 20 , Gd 20 Dy 20 Er 20 Al 20 Ni 20 X-ray diffraction spectrum of the free surface of high entropy amorphous alloy;

[0033] Figure 2 is the Gd prepared in the embodiment of the present invention 20 Dy 20 Er 20 Al 20 Fe 20 , Gd 20 Dy 20 Er 20 Al 20 Co 20 , Gd 20 Dy 20 Er 20 Al 20 Ni 20 Differential scanning calorimetry curve (DSC curve) of high entropy amorphous alloy;

[0034] Figure 3 is the Gd prepared in the embodiment of the present invention 20 Dy 20 Er 20 Al 20 Fe 20 Scanning electron microscope image of the free surface of a high-entropy amorphous alloy strip (20 micron scale);

[0035] Figure 4Gd prepared in the embodiment of the present invention 20 Dy 20 Er 20 Al 20 Fe 20 Transmission electron microscopy image of high entropy amorphous alloy;

[0036] Figure 5 Gd prepared in the embodiment of the present invention 20 Dy 20 Er 20 Al 20 Fe 20 Thermomagnetic curve of high entropy amorphous alloy (external magnetic field is 500Oe);

[0037] Figure 6 Gd prepared in the embodiment of the present invention 20 Dy 20 Er 20 Al 20 Co 20 Thermomagnetic curve of high entropy amorphous alloy (external magnetic field is 500Oe);

[0038] Figure 7 Gd prepared in the embodiment of the present invention 20 Dy 20 Er 20 Al 20 Ni 20 Thermomagnetic curve of high entropy amorphous alloy (external magnetic field is 500Oe);

[0039] Figure 8 Gd prepared in the embodiment of the present invention 20 Dy 20 Er 20 Al 20 Fe 20 Isothermal magnetization curves of high entropy amorphous alloys;

[0040] Fig. 9 Gd prepared in the embodiment of the present invention 20 Dy 20 Er 20 Al 20 Co 20 Isothermal magnetization curves of high entropy amorphous alloys;

[0041] Fig.10 Gd prepared in the embodiment of the present invention 20 Dy 20 Er 20 Al 20 Ni 20 Isothermal magnetization curves of high entropy amorphous alloys;

[0042] Fig.11Gd prepared in the embodiment of the present invention 20 Dy 20 Er 20 Al 20 Fe 20 Magnetic entropy change curve of high entropy amorphous alloy;

[0043] Fig.12 Gd prepared in the embodiment of the present invention 20 Dy 20 Er 20 Al 20 Co 20 Magnetic entropy change curve of high entropy amorphous alloy;

[0044] Fig.13 Gd prepared in the embodiment of the present invention 20 Dy 20 Er 20 Al 20 Ni 20 Magnetic entropy change curve of high entropy amorphous alloy. DETAILED DESCRIPTION

[0045] The following description sufficiently illustrates specific embodiments of the invention to enable those skilled in the art to practice and reproduce the invention.

[0046] Rare earth-based high entropy amorphous alloy for magnetic refrigeration, chemical formula is Gd x Dy x Er x Al x M x , where x is atomic percentage, x=20, and M is one of Fe, Co, and Ni. The alloy is melted in a vacuum arc melting furnace and then prepared in a vacuum belt-spinning furnace.

[0047] The preparation method of rare earth-based high entropy amorphous alloy for magnetic refrigeration comprises the following steps:

[0048] (1) Accurately weigh metal gadolinium Gd, dysprosium Dy, erbium Er, aluminum Al, iron Fe, cobalt Co, and nickel Ni according to atomic ratio;

[0049] Pure metal gadolinium Gd, dysprosium Dy, erbium Er, aluminum Al, iron Fe, cobalt Co, nickel Ni are used as raw materials, strictly in accordance with Gd 20 Dy 20 Er 20 Al 20 Fe 20 , Gd 20 Dy 20 Er 20 Al 20 Co 20 , Gd 20 Dy20 Er 20 Al 20 Ni 20 The components of the high entropy amorphous alloy are formulated separately.

[0050] Use sandpaper or a grinder to remove oxides from the surface of the metal material, and clean it with ultrasonic vibration.

[0051] (2) Place the weighed raw materials in a copper crucible in a vacuum arc melting furnace and evacuate the furnace. The vacuum degree in the furnace chamber is less than 5*10 -3 When the pressure of the furnace chamber reaches 0.5 atmospheres, high-purity argon gas is filled in. Then the metal raw material is melted by electric arc. The melting time of each melting is not less than 3 minutes. After the melting is completed, the alloy ingot is quickly cooled to room temperature and the furnace is opened for sampling.

[0052] Place the prepared raw materials in an electric arc furnace and evacuate the furnace to make the vacuum degree in the furnace chamber less than 10 -3 Pa, clean the furnace chamber with high-purity argon gas for at least 3 times, and then fill it with high-purity argon gas to make the pressure in the furnace reach 0.5 atmospheres. Turn on the melting power of the arc furnace and gradually increase the melting current until all the metal raw materials are melted. Keep warm for 5 minutes, and then gradually reduce the melting current. Each alloy ingot is melted repeatedly 3 times to ensure the uniformity of the alloy composition.

[0053] (3) crushing the prepared alloy ingot and placing it in a glass tube, installing the glass tube containing the alloy block in a belt-spinning furnace, evacuating the belt-spinning furnace, and performing a gas washing operation; turning on the smelting power supply of the belt-spinning furnace to melt the alloy block and spin the belt, and then taking the prepared strip out from the collection chamber of the belt-spinning furnace to obtain a rare earth-based high-entropy amorphous alloy.

[0054] Grind the smelted master alloy ingot, clean it with alcohol, and then break it into blocks of appropriate size and put it into the glass tube. Fix the glass in the vacuum belt spinning furnace, adjust the distance between the tube mouth of the glass tube and the copper roller to about 1mm, and then adjust the injection pressure. Close the door of the vacuum belt spinning furnace and evacuate the furnace chamber of the vacuum belt spinning furnace. Wait until the vacuum degree in the chamber reaches 10 -3 Pa, perform gas washing operation on the chamber. Fill with high-purity argon gas to make the pressure of the chamber reach 0.5 atmospheres. Turn on the power switch that controls the speed of the copper roller, and wait until the speed of the copper roller reaches 3000 revolutions per minute. Turn on the smelting power supply of the vacuum arc furnace, and gradually increase the current until the alloy block is completely melted. Spray, and use the pressure difference to spray the alloy melt onto the high-speed rotating copper roller to form a strip with a width of about 2mm and a thickness of about 20um. Turn off the smelting power supply, open the vent valve, and wait until the pressure in the furnace chamber reaches atmospheric pressure. Open the door of the vacuum arc furnace and take out the sample.

[0055] Rare earth-based high entropy amorphous alloys are used in the field of low-temperature magnetic refrigeration. x Dy x Er x Al x M x The high-entropy amorphous alloy exhibits a higher magnetic entropy change than pure Gd under a 5T magnetic field (the maximum isothermal magnetic entropy change of pure Gd under a 5T magnetic field is 9.8 J kg -1 K -1 ), and the refrigeration capacity of the rare earth-based high entropy amorphous alloy is greater than that of some giant magnetocaloric materials. The Gd, Tb, and Dy elements in the alloy have a large atomic magnetic moment due to their special 4f electron layer structure; under the action of an external magnetic field, the atomic magnetic moment will deflect, resulting in a change in order, a large magnetic entropy change, and an endothermic phenomenon. Al, M (M = Fe, Co, Ni) atoms and rare earth Gd, Tb, Dy atoms have a large atomic radius difference. The introduction of Al and M elements improves the amorphous forming ability. The introduction of five elements can overcome the shortcomings of single elements such as easy oxidation and poor stability. At the same time, high entropy alloying expands the refrigeration temperature range of the material and improves the refrigeration capacity of the alloy.

[0056] like Figure 1 As shown, the Gd prepared in the embodiment of the present invention 20 Dy 20 Er 20 Al 20 Fe 20 , Gd 20 Dy 20 Er 20 Al 20 Co 20 , Gd 20 Dy 20 Er 20 Al 20 Ni 20 X-ray diffraction spectrum of the free surface of high entropy amorphous alloy; Figure 2 As shown, the Gd prepared in the embodiment of the present invention 20 Dy 20 Er 20 Al 20 Fe 20 , Gd 20 Dy 20 Er 20 Al 20 Co 20 , Gd 20 Dy 20 Er 20 Al 20 Ni 20 Differential scanning calorimetry (DSC) curve of high entropy amorphous alloy.

[0057] From Gd 20 Dy 20 Er 20 Al 20 Fe 20 , Gd 20 Dy 20 Er 20 Al 20 Co 20 , Gd 20 Dy 20 Er 20 Al 20 Ni 20 A section was cut from each high entropy alloy strip, and the sample structure was characterized using an X-ray diffractometer (XRD, Bruker D8 Focus, Cu Kα) with a scanning rate of 2° / min.

[0058] The test results are as follows Figure 1 , Figure 2 As shown, Gd 20 Dy 20 Er 20 Al 20 Fe 20 , Gd 20 Dy 20 Er 20 Al 20 Co 20 , Gd 20 Dy 20 Er 20 Al 20 Ni 20 The XRD patterns of the free surface and roller surface of the high entropy alloy strip have no sharp crystal peaks, only broad diffuse peaks, indicating that Gd 20 Dy 20 Er 20 Al 20 Fe 20 , Gd 20 Dy 20 Er 20 Al 20 Co 20 , Gd 20 Dy 20 Er 20 Al 20 Ni 20 High entropy alloy strips have an amorphous structure.

[0059] like Figure 3 As shown, the Gd prepared in the embodiment of the present invention 20 Dy 20 Er 20 Al 20 Fe20 Scanning electron microscopy image of the free surface of a high-entropy amorphous alloy strip (20 μm scale).

[0060] From Gd 20 Dy 20 Er 20 Al 20 Fe 20 , Gd 20 Dy 20 Er 20 Al 20 Co 20 , Gd 20 Dy 20 Er 20 Al 20 Ni 20 A portion of the high entropy alloy strip was cut and the temperature-increasing DSC curve was tested using a differential scanning calorimeter (DSC-404C) at a heating rate of 20 K / min.

[0061] G 20 Dy 20 Er 20 Al 20 Fe 20 , Gd 20 Dy 20 Er 20 Al 20 Co 20 , Gd 20 Dy 20 Er 20 Al 20 Ni 20 The glass transition temperatures of the high entropy amorphous alloys are 604, 572, and 602 K, respectively, showing high structural stability. 20 Dy 20 Er 20 Al 20 Fe 20 , Gd 20 Dy 20 Er 20 Al 20 Co 20 , Gd 20 Dy 20 Er 20 Al 20 Ni 20 The first crystallization temperatures of the high entropy amorphous alloys are 641, 603 and 629 K, respectively. The differences between the first crystallization temperature and the glass transition temperature are 37, 31 and 27 K, respectively, and the alloys have high amorphous forming ability.

[0062] like Figure 4 As shown, the Gd prepared in the embodiment of the present invention20 Dy 20 Er 20 Al 20 Fe 20 Transmission electron microscope image of high entropy amorphous alloy; Figure 5 As shown, the Gd prepared in the embodiment of the present invention 20 Dy 20 Er 20 Al 20 Fe 20 Thermomagnetic curve of high entropy amorphous alloy (external magnetic field is 500Oe); Figure 6 As shown, the Gd prepared in the embodiment of the present invention 20 Dy 20 Er 20 Al 20 Co 20 Thermomagnetic curve of high entropy amorphous alloy (external magnetic field is 500Oe).

[0063] The horizontal axis is temperature (K) and the vertical axis is magnetization (emu / g).

[0064] The Gd was measured using a scanning electron microscope (JEOL JSM-5600LV) and a transmission electron microscope (JEOL, JEM-2010, 200 kV). 20 Dy 20 Er 20 Al 20 Fe 20 , Gd 20 Dy 20 Er 20 Al 20 Co 20 , Gd 20 Dy 20 Er 20 Al 20 Ni 20 The microstructure of high entropy amorphous alloy strips is shown in the following figure. Figure 4-6 The scanning electron microscopy images of the free surfaces of all alloys showed a uniform structure without obvious impurities. The long-range disordered arrangement of atoms can be seen in the transmission electron microscopy images, indicating that the prepared alloys have an amorphous structure.

[0065] like Figure 7 As shown, the Gd prepared in the embodiment of the present invention 20 Dy 20 Er 20 Al 20 Ni 20 Thermomagnetic curve of high entropy amorphous alloy (external magnetic field is 500Oe); Figure 8 As shown, the Gd prepared in the embodiment of the present invention 20Dy 20 Er 20 Al 20 Fe 20 Isothermal magnetization curve of high entropy amorphous alloy; Fig. 9 As shown, the Gd prepared in the embodiment of the present invention 20 Dy 20 Er 20 Al 20 Co 20 Isothermal magnetization curves of high entropy amorphous alloys.

[0066] The horizontal axis is the external magnetic field (T), and the vertical axis is the magnetization intensity (emu / g).

[0067] From Gd 20 Dy 20 Er 20 Al 20 Fe 20 , Gd 20 Dy 20 Er 20 Al 20 Co 20 , Gd 20 Dy 20 Er 20 Al 20 Ni 20 A section was cut from the high entropy alloy strip, and the magnetocaloric curve of the prepared amorphous alloy was measured using a material comprehensive physical property measurement instrument (PPMS) produced by Quantum Design, USA.

[0068] By taking the derivative of the magnetocaloric curve, the temperature response Gd corresponding to the minimum value of the derivative curve is 20 Dy 20 Er 20 Al 20 Fe 20 , Gd 20 Dy 20 Er 20 Al 20 Co 20 , Gd 20 Dy 20 Er 20 Al 20 Ni 20 The phase transition critical points of high entropy amorphous alloys are 79, 41 and 36K, respectively, which represent the optimal working temperatures of high entropy amorphous alloys.

[0069] like Fig.10 As shown, the Gd prepared in the embodiment of the present invention 20 Dy 20 Er 20 Al 20 Ni20 Isothermal magnetization curve of high entropy amorphous alloy; Fig.11 As shown, the Gd prepared in the embodiment of the present invention 20 Dy 20 Er 20 Al 20 Fe 20 Magnetic entropy change curve of high entropy amorphous alloy; Fig.12 As shown, the Gd prepared in the embodiment of the present invention 20 Dy 20 Er 20 Al 20 Co 20 Magnetic entropy change curve of high entropy amorphous alloy.

[0070] The horizontal axis is temperature (K), and the vertical axis is magnetic entropy change (J kg -1 K -1 );

[0071] In Gd 20 Dy 20 Er 20 Al 20 Fe 20 , Gd 20 Dy 20 Er 20 Al 20 Co 20 , Gd 20 Dy 20 Er 20 Al 20 Ni 20 A series of isothermal magnetization curves were tested near the phase transition critical point of the high entropy amorphous alloy. For the prepared high entropy amorphous alloy, below the respective phase transition critical point, the magnetization intensity is sensitive to the applied magnetic field and quickly reaches saturation, showing a ferromagnetic state; above the respective phase transition critical point, the magnetization intensity changes linearly with the applied magnetic field, showing a paramagnetic state. Gd 20 Dy 20 Er 20 Al 20 Fe 20 , Gd 20 Dy 20 Er 20 Al 20 Co 20 , Gd 20 Dy 20 Er 20 Al 20 Ni 20 High entropy amorphous alloys undergo a transition from a ferromagnetic state to a paramagnetic state at their respective phase transition critical points.

[0072] The isothermal magnetic entropy change of the alloy can be calculated by combining the isothermal magnetization curve with the Maxwell relationship below.

[0073] During the isothermal magnetization process, the isothermal magnetic entropy change ΔS of the alloy M It can be calculated using Maxwell's formula:

[0074]

[0075] Where T represents temperature, H1 and H2 represent the minimum and maximum values ​​of the applied magnetic field, respectively.

[0076] like Fig.13 As shown, the Gd prepared in the embodiment of the present invention 20 Dy 20 Er 20 Al 20 Ni 20 Magnetic entropy change curve of high entropy amorphous alloy.

[0077] The horizontal axis is temperature (K), and the vertical axis is magnetic entropy change (J kg -1 K -1 ).

[0078] At different applied magnetic fields, Gd 20 Dy 20 Er 20 Al 20 Fe 20 , Gd 20 Dy 20 Er 20 Al 20 Co 20 , Gd 20 Dy 20 Er 20 Al 20 Ni 20 Isothermal magnetic entropy change ΔS of high entropy amorphous alloys M The results show that Gd 20 Dy 20 Er 20 Al 20 Fe 20 , Gd 20 Dy 20 Er 20 Al 20 Co 20 , Gd 20 Dy 20 Er 20 Al 20 Ni 20 The maximum isothermal magnetic entropy change of high entropy amorphous alloys at 0-5T reached 6.50 J kg -1 K-1 、Co:9.59J kg -1 K -1 and Ni:8.27 J kg -1 K -1 It is worth noting that the sample has a large magnetic entropy change in a wide temperature range.

[0079] Refrigeration capacity (RCP) is another key parameter for evaluating magnetocaloric effect. The refrigeration capacity calculated by the present invention is the product of the temperature range difference (refrigeration temperature span) corresponding to half the maximum isothermal magnetic entropy change value and the maximum isothermal magnetic entropy change value.

[0080] Table 1

[0081]

[0082] Table 1 lists the Gd 20 Dy 20 Er 20 Al 20 Fe 20 , Gd 20 Dy 20 Er 20 Al 20 Co 20 , Gd 20 Dy 20 Er 20 Al 20 Ni 20 Phase transition critical point, maximum isothermal magnetic entropy change, refrigeration temperature span and refrigeration capacity of high entropy amorphous alloys and several typical magnetic refrigeration materials. 20 Dy 20 Er 20 Al 20 Fe 20 , Gd 20 Dy 20 Er 20 Al 20 Co 20 , Gd 20 Dy 20 Er 20 Al 20 Ni 20 High entropy amorphous alloys have the advantages of large isothermal magnetic entropy change, wide refrigeration temperature range and large refrigeration capacity, and have certain application prospects.

[0083] 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 rare earth-based high entropy amorphous alloy, characterized in that: The general chemical formula is Gd x Dy x Er x Al x M x , x is the atomic percentage, and M is one or more of Fe, Co, and Ni.

2. The rare earth-based high entropy amorphous alloy according to claim 1, characterized in that: x＝20。 3. An application method of the rare earth-based high entropy amorphous alloy according to any one of claims 1 or 2, characterized in that: Used for magnetic refrigeration.

4. The application method of the rare earth-based high entropy amorphous alloy according to claim 3, characterized in that: It exhibits a wide refrigeration temperature range at 0-5T, which is Fe: 102K, Co: 63K, Ni: 59K.

5. The application method of the rare earth-based high entropy amorphous alloy according to claim 3, characterized in that: Gd at 0-5T x Dy x Er x Al x Co x The amorphous alloys exhibit the highest maximum isothermal magnetic entropy change, which is Fe: 6.50 J kg -1 K -1 , Co: 9.59Jkg -1 K -1 , Ni: 8.27 J kg -1 K -1 .

6. The application method of the rare earth-based high entropy amorphous alloy according to claim 3, characterized in that: The operating temperature range is: Fe: 31-133K, Co: 19-82K, Ni: 23-82K.

7. The application method of the rare earth-based high entropy amorphous alloy according to claim 3, characterized in that: The Curie temperatures are Fe:T C =79K, Co:T C =41K, Ni:T C =36K.

8. A method for preparing a rare earth-based high entropy amorphous alloy according to any one of claims 1 or 2, characterized in that: include: Accurately weigh metal gadolinium Gd, dysprosium Dy, erbium Er, aluminum Al, iron Fe, cobalt Co, and nickel Ni according to atomic ratio; The weighed raw materials are placed in a copper crucible in a vacuum arc melting furnace and evacuated. The vacuum degree in the furnace chamber is less than 5*10 -3 When the furnace pressure reaches 0.5 atmospheres, high-purity argon gas is filled in. Then the metal raw materials are melted by electric arc. After the smelting is completed, the alloy ingot is quickly cooled to room temperature and the furnace is opened for sampling. The prepared alloy ingot is crushed and placed in a glass tube, the glass tube containing the alloy block is installed in a belt-spinning furnace, the belt-spinning furnace is evacuated and purged, the alloy block is melted and belt-spinned, and the prepared strip is taken out from the collecting chamber of the belt-spinning furnace to obtain a rare earth-based high-entropy amorphous alloy.

9. The method for preparing a rare earth-based high entropy amorphous alloy according to claim 8, characterized in that: The vacuum degree in the furnace chamber is less than 10 -3 When the temperature reaches 0.0400 Pa, clean the furnace chamber with high-purity argon gas for at least 3 times; turn on the smelting power of the arc furnace, gradually increase the smelting current until all the metal raw materials are melted, keep warm for 5 minutes and then gradually reduce the smelting current. Each alloy ingot is smelted repeatedly for 3 times to ensure the uniformity of the alloy composition; grind the smelted alloy ingot, clean it with alcohol, then break the alloy ingot into blocks and put it into a glass tube; fix the glass in a vacuum belt spinning furnace, adjust the distance between the tube mouth of the glass tube and the copper roller to 1mm, and then adjust the injection pressure; turn on the power switch that controls the speed of the copper roller, wait until the speed of the copper roller reaches 3000 revolutions per minute, turn on the smelting power of the vacuum arc furnace, and gradually increase the current until the alloy block is completely melted; use the pressure difference to spray the alloy melt onto the high-speed rotating copper roller to form a strip with a width of 2mm and a thickness of 20um; turn off the smelting power, open the vent valve until the pressure in the furnace chamber reaches atmospheric pressure, open the furnace door of the vacuum arc furnace, and take out the sample.

10. An application method of the rare earth-based high entropy amorphous alloy according to any one of claims 1 or 2, characterized in that: Used in magnetic refrigerators.

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