Preparation method of Cu-Al-Mn-based elastic thermal refrigeration material

Abstract

The invention relates to a preparation method of a Cu-Al-Mn-based elastic thermal refrigeration material. The preparation method mainly comprises the following steps: (1) uniformly mixing Cu-Al-Mn-based alloy powder and Al2O3 powder to obtain mixed powder; (2) sintering the mixed powder into blocks; (3) carrying out heat treatment on the sintered block; wherein the Cu-Al-Mn based alloy powder and the Al2O3 powder are spherical particles, and the Cu-Al-Mn based alloy powder and the Al2O3 The particle diameter of the Cu-Al-Mn based alloy powder is 10 to 100 [mu] m; the particle diameter of the Al2O3 powder ranges from 20 nm to 500 nm. According to the method, Al2O3 nano-particles with high mechanical strength and Cu-Al-Mn spherical powder are mixed and sintered to obtain a microstructure with Cu-Al-Mn particles wrapped by Al2O3-rich particles, the mechanical property of the material is improved, and meanwhile the excellent elastic heat effect is achieved.

Description

Technical Field

[0001] The present invention relates to the field of preparation of shape memory alloy materials, and particularly to a preparation method of a Cu-Al-Mn-based elastocaloric refrigeration material. Background Art

[0002] Elastocaloric refrigeration is a solid-state refrigeration technology that generates a refrigeration effect by driving the phase change of an elastocaloric material with a stress field. Compared with the commonly used gas compression refrigeration method at present, the refrigerant in elastocaloric refrigeration is a solid, which does not produce the greenhouse effect and is more environmentally friendly. Due to its large refrigeration amplitude, elastocaloric refrigeration is considered to be the most promising technology among refrigeration technologies such as piezocaloric refrigeration, magnetocaloric refrigeration, and electrocaloric refrigeration. At present, researchers have discovered a variety of elastocaloric refrigeration materials, such as Ni-Ti, Ni-Mn-Co, Cu-Al-Mn, Fe-Pd and other systems. Among them, the Cu-Al-Mn-based alloy with the Heusler structure has the characteristics of a relatively wide temperature window, high thermal stability and low cost, and is currently recognized as one of the most promising elastocaloric refrigeration materials.

[0003] CN113174512A discloses a preparation method of a non-cold deformed high elastocaloric effect Ti-Ni bulk material, including: argon arc melting 48.8-49.3% Ti and 50.7-51.2% Ni metal raw materials; suction casting and wire electrical discharge machining of the molten alloy; performing solid solution homogenization treatment to make the micro-components uniform, aging treatment, and electrochemical surface finishing to obtain a coarse-grained bulk Ti-Ni alloy block. The prepared Ti-Ni bulk material does not require cold deformation processing, and the thickness of the plate-shaped bulk material is at the millimeter level. Under non-cold deformation conditions, a similar elastocaloric effect is achieved, and the adiabatic temperature change can reach up to 22.7K, enabling elastocaloric refrigeration applications in a larger range.

[0004] CN 118147487A discloses a Ti-Ni-Cu elastocaloric refrigeration thin plate and a preparation method thereof, including the following process: mixing high-purity metal particles according to the atomic ratio of metal elements Ti, Ni, and Cu in the material chemical general formula Ti 49.2 Ni 50.8-x Cu x (5<x≤7.5) and performing vacuum induction melting; performing hot rolling on the initial ingot; performing high-temperature homogenization treatment and water quenching on the hot-rolled plate; performing cold rolling on the homogenized plate at room temperature; performing low-temperature annealing treatment on the cold-rolled plate, and finally obtaining a Ti-Ni-Cu elastocaloric refrigeration thin plate. The prepared Ti-Ni-Cu alloy thin plate has both a large adiabatic temperature change and excellent anti-functional fatigue performance, and the obtained alloy thin plate has a large specific surface area.

[0005] Although polycrystalline copper-based shape memory alloys (Cu-Al-Mn) have good application prospects in the field of caloric refrigerants, they have problems such as coarse grains, poor plasticity, susceptibility to grain boundary cracking, short fatigue life, and poor cold working performance, which seriously restrict their widespread application. These problems are mainly related to the influence of their grain boundaries, precipitated phases, and stress concentration in the matrix. Existing research usually improves these properties by adding alloying elements (such as B, Ti, Fe, and Cr). Studies have shown that the addition of these elements can improve the strength of the alloy through solid solution strengthening of the precipitated phase. However, the introduction of precipitated phases also leads to a decrease in shape memory strain, affecting the caloric refrigerant effect of the material, thereby restricting its application effect in caloric refrigerants. Therefore, it is necessary to further improve the properties of polycrystalline copper-based shape memory alloys so that the alloy material has the mechanical properties of Cu-Al-Mn-based caloric refrigerant materials and has a good caloric refrigerant effect. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for preparing a Cu-Al-Mn based elastocaloric refrigeration material, which mainly comprises selecting Al2O3 particles of a specific particle size and mixing them with a Cu-Al-Mn based alloy for sintering to obtain a microstructure of a Cu-Al-Mn phase encapsulated by an Al2O3 phase.

[0007] The present invention provides a method for preparing a Cu-Al-Mn based elastocaloric refrigeration material, comprising the following steps:

[0008] (1) uniformly mixing Cu-Al-Mn based alloy powder and Al2O3 powder to obtain mixed powder;

[0009] (2) sintering the mixed powder into a block;

[0010] (3) heat treating the sintered block;

[0011] The Cu-Al-Mn based alloy powder and Al2O3 powder are spherical particles; the particle diameter of the Cu-Al-Mn based alloy powder is 10-100 μm; and the particle diameter of the Al2O3 powder is 20-500 nm.

[0012] Further preferably, the molar ratio of Cu, Al and Mn in the Cu-Al-Mn based alloy powder in step (1) is 70-75:15-20:10-15, more preferably 70-72:16-18:10-12.

[0013] Further preferably, the particle diameter of the Cu-Al-Mn based alloy powder in step (1) is 15-55 μm; the particle diameter of the Al 2 O 3 powder is 50-100 nm.

[0014] Further preferably, the mass of the Al2O3 powder in step (1) accounts for 0.5 to 2% of the total mass of the Cu-Al-Mn based alloy powder and the Al2O3 powder;

[0015] Further preferably, the sintering method in step (2) is spark plasma sintering.

[0016] Further preferably, the sintering temperature in step (2) is 650-850° C., the sintering time is 3-10 min, and the sintering pressure is 20-50 MPa.

[0017] Further preferably, the heat treatment in step (3) is carried out under the protection of an argon atmosphere, the heat treatment temperature is 600 to 1000° C., and the heat treatment time is 20 min to 6 h.

[0018] Further preferably, quenching is performed after the heat treatment in step (3), and more preferably water quenching is performed, and the water quenching time is 30-90 minutes.

[0019] A Cu-Al-Mn based elasto-caloric refrigeration material prepared by the method has a yield strength of more than 540 MPa and a -1 When the strain is loaded to 2.5%, an adiabatic temperature change of 2.09 K can be achieved.

[0020] Application of the Cu-Al-Mn based elastocaloric refrigeration material obtained by the preparation method in the field of refrigeration.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) By combining the two powders, Cu-Al-Mn particles with Al2O3 nanoparticles uniformly embedded on the surface can be obtained. This unique structure is beneficial for improving the uniformity of the sintered samples and enhancing the overall performance of the material, especially its stability under high temperature and high stress environments;

[0023] (2) The particle size of the selected Cu-Al-Mn based alloy powder is 15-53 μm. The moderate particle size helps to maintain the grain size of the sample, thereby effectively improving the strength and plasticity of the material and helping to optimize the transfer performance of its elastic-thermal effect;

[0024] (3) The selected Al2O3 nanoparticles have extremely high chemical stability, so the diffusion of Al2O3 is limited during the heat treatment and sintering process, effectively avoiding the negative impact on the elastic-thermal effect of the material, thereby achieving a balanced optimization of the mechanical properties and thermal response performance of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1This is a microscopic morphology of the Cu-Al-Mn based elastocaloric refrigeration material prepared in Example 1;

[0026] Figure 2 This is a microstructure diagram of the Cu-Al-Mn based elastocaloric refrigeration material prepared in Example 1;

[0027] Figure 3 This is the stress-strain diagram of the Cu-Al-Mn based elastocaloric refrigeration material prepared in Example 1;

[0028] Figure 4 The stress-strain diagram and adiabatic temperature change diagram of the Cu-Al-Mn based elastocaloric refrigeration material prepared in Example 1;

[0029] Figure 5 The stress-strain diagram and adiabatic temperature change diagram of the Cu-Al-Mn based elastocaloric refrigeration material prepared in Comparative Example 1;

[0030] Figure 6 The stress-strain diagram and adiabatic temperature change diagram of the Cu-Al-Mn based elastocaloric refrigeration material prepared in Comparative Example 2. DETAILED DESCRIPTION

[0031] In order to make the technical solutions and technical effects of the present invention clearer, the present invention will be described in detail below with reference to specific embodiments.

[0032] Example 1

[0033] A method for preparing a Cu-Al-Mn based elastocaloric refrigeration material comprises the following steps:

[0034] (1) Preparation of Cu by gas atomization method 71 Al 17.5 Mn 11.5 Spherical powder, screening the powder with a diameter of 15 to 53 μm as the raw material powder, selecting Al2O3 powder with a diameter of 50-100 nm, according to the mass of Al2O3 powder accounting for 1% of the total mass of Cu-Al-Mn based alloy powder and Al2O3 powder, and then placing the two powders in a ball mill and mixing them evenly;

[0035] (2) The mixed powder was placed in a 20 mm graphite mold and then sintered in a spark plasma sintering furnace at a sintering temperature of 800 °C, a sintering time of 10 min, a sintering pressure of 40 MPa, and a heating rate of 100 °C / min. After sintering, the mixture was cooled in the furnace.

[0036] (3) The surface of the sintered sample was polished and cleaned, and then sealed in a glass tube with argon protection and heat treated at 900°C for 200 minutes. After the heat treatment, it was water quenched for 30 minutes to obtain a Cu-Al-Mn based elastomeric refrigeration material.

[0037] Figure 1 This is a microscopic morphology image of Example 1 of the present invention, showing that nano-Al2O3 particles are evenly covered on the surface of Cu-Al-Mn particles. Figure 2 This is the microstructure diagram of Example 1 of the present invention. The black area at the grain boundary is nano-Al2O3 particles, indicating that they are uniformly distributed at the grain boundary. Figure 3 The stress-strain curve of Example 1 has a yield strength of 540 MPa, indicating that the method obtains an Al2O3 reinforcement phase uniformly distributed at the grain boundaries, significantly improving the mechanical properties of the material.

[0038] Example 2

[0039] A method for preparing a Cu-Al-Mn based elastocaloric refrigeration material comprises the following steps:

[0040] (1) Preparation of Cu with nominal composition by gas atomization method 70 Al 18 Mn 12 Spherical powder, wherein the powder with a diameter of 15 to 53 μm is selected as the raw material powder; Al2O3 powder with a diameter of 10 to 100 nm is selected, wherein the mass of the Al2O3 powder accounts for 0.5% of the mass of the Cu-Al-Mn based alloy powder and the Al2O3 powder, and then the two powders are placed in a ball mill and mixed uniformly;

[0041] (2) The mixed powder was placed in a Φ15 mm graphite mold and then sintered in a spark plasma sintering furnace at a sintering temperature of 750 °C, a sintering time of 10 min, a sintering pressure of 50 MPa, and a heating rate of 100 °C / min. After sintering, the mixture was cooled in the furnace.

[0042] (3) The surface of the sintered sample was polished and cleaned, then sealed in a glass tube with argon protection, heat treated at 800°C for 30 min, and then water quenched.

[0043] Example 3

[0044] A method for preparing a Cu-Al-Mn based elastocaloric refrigeration material comprises the following steps:

[0045] (1) Preparation of Cu with nominal composition by gas atomization method 71.5 Al 17 Mn 11.5 Spherical powder, select the powder with a diameter of 15 to 53 μm as the raw material powder, weigh Al2O3 powder with a diameter of 50 to 200 nm, where the mass of Al2O3 powder accounts for 2% of the total mass of Cu-Al-Mn based alloy powder and Al2O3 powder, and then place the two powders in a ball mill and mix them evenly;

[0046] (2) The mixed powder was placed in a Φ10 mm graphite mold and then sintered in a spark plasma sintering furnace at a sintering temperature of 820 °C, a sintering time of 5 min, a sintering pressure of 30 MPa, and a heating rate of 100 °C / min. After sintering, the mixture was cooled in the furnace.

[0047] (3) The surface of the sintered sample was polished and cleaned, then sealed in a glass tube with argon protection, heat treated at 800°C for 20 min, and then water quenched.

[0048] Comparative Example 1

[0049] Cu 71.5 Al 17 Mn 11.5 The particle size of the spherical powder and Al2O3 powder is 15-53 μm, and the other process conditions and steps are the same as those in Example 1. The yield strength of the obtained material is 540 MPa. -1 When the strain is loaded to 2.5%, an adiabatic temperature change of 2.09 K can be achieved.

[0050] Comparative Example 2

[0051] The heat treatment in step (3) was not performed, and the other process conditions and steps were the same as those in Example 1. The yield strength of the obtained material was 390 MPa. -1 When the strain is loaded to 3.4%, an adiabatic temperature change of 0.87K can be achieved.

[0052] The above embodiments are only used to illustrate the technical features of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit of the present invention, and the relevant changes and modifications will be included in the scope of protection of the present invention.

Claims

1. A method for preparing a Cu-Al-Mn based elastocaloric refrigeration material, comprising the following steps: (1) uniformly mixing Cu-Al-Mn based alloy powder and Al2O3 powder to obtain mixed powder; (2) sintering the mixed powder into a block; (3) heat treating the sintered block; The Cu-Al-Mn based alloy powder and Al2O3 powder are spherical particles; the particle diameter of the Cu-Al-Mn based alloy powder is 10-100 μm; and the particle diameter of the Al2O3 powder is 20-500 nm.

2. The method according to claim 1, characterized in that The molar ratio of Cu, Al and Mn in the Cu-Al-Mn based alloy powder in step (1) is 70-75:15-20:10-15, more preferably 70-72:16-18:10-12.

3. The method according to claim 1, characterized in that Step (1) The particle diameter of the Cu-Al-Mn based alloy powder is 15-55 μm; the particle diameter of the Al2O3 powder is 50-100 nm.

4. The method according to claim 1, characterized in that The mass of the Al2O3 powder in step (1) accounts for 0.5 to 2% of the total mass of the Cu-Al-Mn based alloy powder and the Al2O3 powder.

5. The method according to claim 1, characterized in that The sintering method described in step (2) is spark plasma sintering.

6. The method according to claim 1, characterized in that The sintering temperature in step (2) is 650-850° C., the sintering time is 3-10 min, and the sintering pressure is 20-50 MPa.

7. The method according to claim 1, characterized in that The heat treatment in step (3) is carried out under the protection of an argon atmosphere, the heat treatment temperature is 600 to 1000° C., and the heat treatment time is 20 min to 6 h.

8. The method according to claim 7, characterized in that After the heat treatment in step (3) is completed, quenching is performed, and more preferably water quenching is performed, and the water quenching time is 30-90 minutes.

9. A Cu-Al-Mn based elastocaloric refrigeration material prepared according to the method according to any one of claims 1 to 8, characterized in that The material has a yield strength of more than 540 MPa. -1 When the strain is loaded to 2.5%, an adiabatic temperature change of 2.09 K can be achieved.

10. Use of the Cu-Al-Mn based elastocaloric refrigeration material obtained according to the preparation method according to any one of claims 1 to 8 in the field of refrigeration.

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