CN103031460A - Preparation method and application of hyperelastic porous CuAlNi high temperature shape memory alloy - Google Patents

Abstract

The invention discloses a method for preparing a superelastic porous CuAlNi high-temperature shape memory alloy, which comprises the following steps: preparing a CuAlNi alloy ingot by arc melting or induction melting; pressing _NaAlO2 powder into a green body, and sintering in an air atmosphere , to get the NaAlO ₂ block; put the NaAlO ₂ block into the bottom of the tube furnace that can move up and down, put the CuAlNi alloy ingot on the NaAlO ₂ block, and keep it warm in a vacuum atmosphere; then fill the protective gas and keep it, and then put the The tube furnace is moved downwards out of the heating zone, cooled and immersed in a weak acid for ultrasonic oscillation, then placed in a vacuum furnace for heat treatment under a protective atmosphere, and then quenched into ice water to obtain a superelastic porous CuAlNi high temperature shape memory alloy. The porous CuAlNi shape memory alloy of the present invention has good superelasticity and mechanical properties at high temperature, and also exhibits good cycle stability.

Description

Preparation method and application of a superelastic porous CuAlNi high temperature shape memory alloy

technical field

The invention relates to the field of porous CuAlNi high-temperature shape memory alloys, in particular to a preparation method and application of a superelastic porous CuAlNi high-temperature shape memory alloy.

Background technique

Porous shape memory alloys can exhibit many excellent properties that can only be found in shape memory alloys and porous materials, such as unique shape memory effect and superelasticity, light weight, adjustable mechanical properties, high specific surface area and damping characteristics. Therefore, porous shape memory alloys have great application prospects in many fields, such as hard tissue replacement, energy absorbing devices, and battery electrode materials. Among the several porous shape memory alloys that have been prepared (including NiTi-based, Cu-based and Fe-based), the porous NiTi memory alloy is considered to be the most valuable one because of its stable shape memory effect and Superelastic, good biocompatibility and mechanical properties. This makes porous NiTi memory alloys have great application prospects in the field of biomedicine, especially in hard tissue repair and replacement. However, its high price and low phase transition temperature (-100~100°C) limit its application in some mass production or high working temperature occasions. In contrast, porous Cu-based memory alloys have great advantages in the automotive, manufacturing, and energy-absorbing and shock-absorbing industries due to their low cost and high phase transition temperature.

In addition to NiTi memory alloys, Cu-based memory alloys are currently the most widely used commercial shape memory alloys. There are two main types of binary alloys in Cu-based memory alloys: CuZn and CuAl, among which CuAl binary memory alloy is considered to be the most potential high-temperature memory alloy, not only because it exhibits a high phase transition temperature, but also because It has more excellent microstructural stability than CuZn alloy. In order to prevent the decomposition of the parent phase in CuAl binary memory alloys, Ni is usually added to form CuAlNi ternary alloys. Due to the intrinsic coarse grain characteristics of CuAlNi alloy, the shape memory effect and mechanical properties of polycrystalline CuAlNi memory alloy are far lower than those of polycrystalline NiTi memory alloy. However, single crystal CuAlNi memory alloys can exhibit very high superelasticity, even surpassing NiTi alloys. For example, [001] single crystals in CuAl ₁₄ Ni _4.2 (wt.%) can exhibit full superelasticity up to 17% at 205°C. The polycrystalline CuAlNi alloy is prone to transgranular fracture due to its large grain size (1 mm) and the brittle γ phase precipitated at the grain boundary, resulting in very poor shape memory effect (less than 1%) and toughness. In fact, it is very difficult and expensive to prepare large single-crystal samples. In order to improve the performance of CuAlNi alloy, the most effective way is to add some grain refinement elements, such as Ti, Mn, V and B, etc., or form a directional texture by rolling, such as CuAl ₁₂ Ni ₄ Mn ₄ B _0.04 alloy A 5% deformation at 150°C can produce a recoverable strain of 4.5%.

Recently, it has been found that the micron-scale polycrystalline CuAlNi alloy wire prepared by the melting wire drawing method can exhibit a complete superelasticity of up to 6.6% at room temperature, which is mainly attributed to the formation of a bamboo-like structure. , that is, the whole alloy crystal wire is like a bamboo, one of the crystal grains is like a section of bamboo, only two ends are in contact with the other crystal grain, and the other surfaces are free surfaces. This structure helps to release the stress caused by martensitic transformation, so the performance is greatly improved, and it is close to the performance of single crystal. Based on this principle, some researchers have prepared a porous NiMnGa magnetic memory alloy with a bamboo-like crystal structure by infiltration and precipitation. Each grain is only adjacent to one grain, and the other surfaces are connected to the pore wall. The magnetic memory performance of this polycrystalline sample is close to that of single crystal, but the porosity of this porous alloy is generally greater than 50%, which must limit its application range. Therefore, whether the grains of CuAlNi alloys are easy to grow can be used to prepare porous CuAlNi memory alloys with a complete bamboo-like crystal structure at any porosity, and exhibit better superelasticity at high temperatures. will be very meaningful.

Contents of the invention

In order to overcome the shortcomings and deficiencies of the prior art, the object of the present invention is to provide a method for preparing a superelastic porous CuAlNi high temperature shape memory alloy, which exhibits better mechanical properties and superelasticity at high temperatures (>200°C), And good high temperature cycle stability. Another object of the present invention is to provide the application of the superelastic porous CuAlNi high temperature shape memory alloy obtained by the above method.

The object of the present invention is achieved through the following technical solutions:

A preparation method of superelastic porous CuAlNi high temperature shape memory alloy, comprising the following steps:

(1) CuAlNi alloy ingot is prepared by arc melting or induction melting; the mass ratio of each element in the CuAlNi alloy ingot is Cu:Al:Ni=(100-x-y):x:y, where x is 13~15 , y is 3~5;

(2) Press the pore-forming agent NaAlO ₂ powder into a green body, and sinter it in an air atmosphere to obtain a NaAlO ₂ block;

(3) Put the _NaAlO2 block obtained in step (2) into the bottom of the tube furnace that can move up and down, and then put the CuAlNi alloy ingot obtained in step (1) on the _NaAlO2 block, in a vacuum atmosphere, the temperature is 1150 ° C Insulate at ~1250°C for 0.5h to 5h; then fill the protective gas with a pressure of 1.2×10 ⁵ Pa~2×10 ⁵ Pa and keep it for 1h to 5h, then move the tube furnace downward out of the heating zone, and obtain CuAlNi after cooling and NaAlO ₂ composite materials;

(4) immerse the composite material of CuAlNi and NaAlO ₂ obtained in step (3) into a weak acid and oscillate ultrasonically to dissolve and remove NaAlO ₂ to obtain a porous CuAlNi alloy;

(5) Putting the porous CuAlNi alloy obtained in step (4) into a vacuum furnace, performing heat treatment under a protective atmosphere, and then quenching into ice water to obtain a superelastic porous CuAlNi high temperature memory alloy.

The particle size of the NaAlO ₂ powder in step (2) is 50-1500 μm.

The specific conditions for the sintering in step (2) are: the temperature is 1350° C. to 1500° C., and the time is 10 hours to 24 hours.

The specific conditions for the pressing in step (2) are: the pressure is 5-600 MPa, the temperature is 30-100°C, and the time is 5 minutes-1 hour.

The vacuum atmosphere in step (3) has a degree of vacuum of 1×10 ^-2 Pa to 1×10 ^-3 Pa.

The protective gas is argon or nitrogen.

As described in step (3), move the tube furnace downwards out of the heating zone, specifically:

Move the tube furnace down out of the heating zone at a rate of 0.5mm/min~20mm/min.

In the step (4), put the composite material of CuAlNi and _NaAlO obtained in the step (3) into a weak acid and ultrasonically vibrate, specifically:

Immerse the composite material of CuAlNi and NaAlO ₂ obtained in step (3) into HCl or H ₂ SO ₄ with a solubility of 5% to 15% and vibrate ultrasonically. The time of ultrasonic oscillation is 15h~30h and the temperature is 30°C~80°C .

The heat treatment in step (5) specifically includes: the heat treatment temperature is 850° C. to 950° C., and the heat treatment time is 0.5h to 5h.

The elastic porous CuAlNi high-temperature shape memory alloy obtained by the above method is used for preparing energy absorbing and driving devices in automobiles and aerospace, or as electrode materials for batteries.

The principle of the present invention is: use _NaAlO2 powder as a pore-forming agent, sinter it into a _NaAlO2 block with a certain porosity, and then infiltrate the molten CuAlNi alloy into the gaps between the _NaAlO2 particles with the help of high-pressure gas to obtain Composite materials of NaAlO ₂ and CuAlNi; then use directional solidification to obtain CuAlNi alloy with very coarse grains; NaAlO ₂ has a large solubility in weak acid, while CuAlNi alloy is very small, NaAlO ₂ can be removed to obtain porous with coarse grains CuAlNi alloy; after quenching heat treatment, it exhibits high temperature superelasticity. Moreover, the porosity and pore size of the NaAlO _bulk can be controlled by utilizing different particle sizes and different pressing forces, so that the porosity, pore size, and connectivity of the porous CuAlNi alloy can be tuned. Different directional solidification speeds can control different grain sizes, so that complete bamboo-like structures can be obtained at different porosities. The porosity and pore size of porous CuAlNi can be further adjusted by soaking in weak acid for different time.

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

(1) The superelastic porous CuAlNi high-temperature shape memory alloy prepared by the present invention has a porous CuAlNi shape memory alloy with a bamboo-like crystal structure, which can not only obtain a complete bamboo-like structure at a high porosity, but also at a low porosity (<10 %), the porous CuAlNi high-temperature shape memory alloy with bamboo-like crystal structure can also be obtained.

(2) The invented porous CuAlNi memory alloy exhibits better mechanical properties and superelasticity at high temperature (>200°C), as well as good high temperature cycle stability.

(3) The present invention can control grain sizes of different sizes through different directional solidification speeds, so that complete bamboo-like structures can be obtained at different porosities. It is also possible to control the soaking time in weak acid to further adjust the porosity and pore size of porous CuAlNi.

Description of drawings

Figure 1 is a scanning electron micrograph of the porous CuAlNi alloy without NaAlO2 removal in Example ₁ .

Fig. 2 is a scanning electron micrograph of the porous CuAlNi alloy with NaAlO ₂ removed in Example 1.

Fig. 3 is a metallographic micrograph of the porous CuAlNi alloy after corrosion in Example 1.

Fig. 4 is the DSC curve of heating and cooling of the porous CuAlNi alloy in Example 1.

Fig. 5 is the compressive stress-strain curve of the porous CuAlNi alloy in Example 1 (the test temperature is 260°C, after 6 compression cycles, the pre-strain gradually increases).

Fig. 6 is the stress-strain curve of the porous CuAlNi alloy of Example 1 (the test temperature is 260°C).

Fig. 7 is the variation curve of the shape recovery rate of the porous CuAlNi alloy in Example 1 with the number of cycles (the test temperature is 260°C).

Fig. 8 is a scanning electron micrograph of the porous CuAlNi alloy without removing NaAlO ₂ in Example 2.

Fig. 9 is a scanning electron micrograph of the porous CuAlNi alloy with NaAlO2 removed in Example ₂ .

FIG. 10 is a metallographic micrograph of the porous CuAlNi alloy corroded in Example 2.

Fig. 11 is the DSC curve of heating and cooling of the porous CuAlNi alloy in Example 2.

Fig. 12 is the compressive stress-strain curve of the porous CuAlNi alloy in Example 2 (the test temperature is 260°C, after 3 compression cycles, the pre-strain gradually increases).

Fig. 13 is a metallographic micrograph of the CuAlNi alloy corroded in Example 3.

Fig. 14 is the compressive stress-strain curve of CuAlNi alloy in Example 3 (the test temperature is 210°C, after 9 compression cycles, the pre-strain gradually increases).

Detailed ways

The present invention will be described in further detail below in conjunction with the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

Example 1

(1) Cu _81.5 Al _14.5 Ni ₄ (wt.%) alloy ingot was prepared by arc melting;

(2) Press NaAlO ₂ powder with a purity of 99% and a particle size of 350-510 μm to form a green body, with a pressing force of 10 MPa, a temperature of 30°C, and a time of 10 minutes; sintering is carried out in an air atmosphere, and the sintering temperature is 1400°C , the sintering time is 12 hours, and the _NaAlO2 bulk is obtained;

(3) Put the NaAlO ₂ block into the bottom of the tube furnace that can move up and down, then put the Cu _81.5 Al _14.5 Ni ₄ alloy ingot on the NaAlO ₂ block, under 5×10 ^-3 Pa vacuum, at 1200℃ Keep it warm for 0.5h, then fill it with argon gas of 1.2×10 ⁵ Pa and keep it for 2h, then move the tube furnace down at a speed of 5mm/min out of the heating zone, and obtain Cu _81.5 Al _14.5 Ni ₄ and NaAlO ₂ after cooling composite materials;

The composite material was cut, and it was found that the CuAlNi alloy had completely infiltrated the gap between the NaAlO ₂ particles (as shown in Figure 1), and the size of the NaAlO ₂ particles was basically the same as that before sintering.

(4) The obtained composite material was immersed in weak HCl with a solubility of 10%, ultrasonically oscillated for 20 hours, and the temperature was 60°C; after dissolving and removing NaAlO ₂ particles, a porous Cu _81.5 Al _14.5 Ni ₄ alloy was obtained (as shown in Figure 2). The pores are all interconnected, and the pore size is 300-550 μm, and the porosity is 60%.

(5) The porous Cu _81.5 Al _14.5 Ni ₄ alloy was heated to 900 °C under the protection of argon, kept for 0.5 h and then rapidly cooled to ice water to obtain a porous CuAlNi alloy with a high transition temperature.

The metallographic micrograph of the porous Cu _81.5 Al _14.5 Ni ₄ alloy after heat treatment after corrosion is shown in Figure 3. It is found that only a few grain boundaries are observed in the entire sample, and the two ends of the grain boundaries must be connected with holes, forming a complete bamboo-like crystal structure. There are martensitic bars throughout the sample. The phase transformation behavior of the porous Cu _81.5 Al _14.5 Ni ₄ alloy was also characterized (as shown in Figure 4), and it was found that there were obvious endothermic or exothermic peaks during heating and cooling, which indicated that the sample had a martensitic transformation, And measured its A _f temperature (martensitic reverse transformation completion temperature) is 255 ℃.

Through the compression test of the porous Cu _81.5 Al _14.5 Ni ₄ alloy at 260 °C, it was found that it can fully recover under a pre-strain of less than 2.5%, exhibiting complete superelasticity. Under 3.9% pre-strain, 80% shape recovery can be maintained, as shown in Figure 5. Its compressive strength limit can reach 40MPa, and its elastic modulus is 2.8GPa. Moreover, it was subjected to a compression cycle test at 260°C with a prestrain of 2.6%, and it was found that it exhibited excellent high-temperature cycle stability, as shown in Figure 6. And except for the shape recovery rate of 94% in the first cycle, it is stable at about 98% after that, as shown in Figure 7.

The elastic porous CuAlNi high-temperature shape memory alloy prepared in this embodiment can be used to prepare energy absorbing and driving devices for automobiles and aerospace, or as electrode materials for batteries.

Example 2

(1) Cu ₈₃ Al ₁₃ Ni ₄ (wt.%) alloy ingot was prepared by arc melting;

(2) Press NaAlO ₂ powder with a purity of 99% and a particle size of 300-450 μm into a green body, with a pressing force of 50 MPa, a temperature of 50 °C, and a time of 5 minutes; sintering in an air atmosphere at a temperature of 1500 °C , the sintering time is 15 hours, and the _NaAlO2 bulk is obtained;

(3) Put the NaAlO ₂ block into the bottom of the tube furnace that can move up and down, then put the CuAlNi alloy ingot on the NaAlO ₂ block, keep it warm at 1250℃ for 5h under 2×10 ^-3 Pa vacuum, then Fill with argon gas of 2×10 ⁵ Pa and keep it for 5 hours, then move the tube furnace downwards out of the heating zone at a speed of 1 mm/min, and obtain a composite material of CuAlNi and NaAlO ₂ after cooling;

The composite material was cut, and it was found that the CuAlNi alloy had completely penetrated into the gaps between the NaAlO ₂ particles (as shown in Figure 8), and the size of the NaAlO ₂ particles was basically the same as that before sintering.

(4) The obtained composite material was immersed in 15% weak H ₂ SO ₄ , ultrasonically oscillated for 30 hours, and the temperature was 80°C; after dissolving and removing NaAlO ₂ particles, a porous CuAlNi alloy was obtained (as shown in Figure 9). The pores are all interconnected, and the pore size is 300-450 μm, and the porosity is 50%.

(5) The porous CuAlNi alloy was heated to 950°C under the protection of nitrogen, kept for 5 hours and then rapidly cooled into ice water to obtain a porous CuAlNi alloy with a high transition temperature.

The metallographic micrograph of the porous CuAlNi alloy after heat treatment after corrosion is shown in Figure 10. It is found that only a few grain boundaries are observed in the entire sample, and the two ends of the grain boundaries must be connected with holes to form complete bamboo-like grains. structure. There are martensitic bars throughout the sample. The phase transformation behavior of the porous CuAlNi alloy was also characterized (as shown in Figure 11), and its _Af temperature was measured to be 225 °C.

Through the compression test of the porous CuAlNi alloy at 260 °C, it is found that it can fully recover under the prestrain of less than 1%, exhibiting complete superelasticity. Under a pre-strain of 1.88%, the shape recovery rate is 69%, as shown in Fig. 12. Its compressive strength limit can reach 35MPa, and its elastic modulus is 3.2GPa.

Example 3

(1) Cu _81.5 Al ₁₄ Ni _4.5 (wt.%) alloy ingot was prepared by arc melting;

(2) Press NaAlO ₂ powder with a purity of 99% and a particle size of 50 μm into a green body, with a pressing force of 600 MPa, a temperature of 100 °C, and a time of 1 hour; sintering in an air atmosphere at a sintering temperature of 1500 °C, and sintering The time is 24 hours to obtain NaAlO _block ;

(3) Put the NaAlO ₂ block into the bottom of the tube furnace that can move up and down, then put the CuAlNi alloy ingot on the NaAlO ₂ block, keep it warm at 1200℃ for 2h under 1×10 ^-3 Pa vacuum, then Fill with argon gas of 2×10 ⁵ Pa and keep it for 5 hours, then move the tube furnace downwards out of the heating zone at a speed of 5 mm/min, and obtain a composite material of CuAlNi and NaAlO ₂ after cooling;

Cutting this composite material, it was found that the CuAlNi alloy basically did not infiltrate into the gaps between the NaAlO ₂ particles, and the NaAlO ₂ block and CuAlNi had a clear boundary.

(4) The obtained composite material was immersed in 5% weak HCl, ultrasonically oscillated for 15 hours, and the temperature was 60 ° C; after dissolving and removing NaAlO ₂ particles, a porous CuAlNi alloy was obtained, and its porosity was only 1%.

(5) The porous CuAlNi alloy was heated to 950°C under the protection of argon, kept for 0.5h and then rapidly cooled into ice water to obtain a porous CuAlNi alloy with a high transition temperature.

The corroded metallographic micrograph of the heat-treated porous CuAlNi alloy is shown in Figure 13. It was found that only a few grains were observed in the entire sample, the grain size was 4-5mm, and each grain was basically only 1 - Two adjacent crystal grains form a slub-like crystal structure. There are martensitic bars throughout the sample. Its _Af temperature was also measured to be 190°C.

Through the compression test of this CuAlNi alloy at 210 °C, it is found that it can basically recover completely under the prestrain of less than 6.64%, showing complete superelasticity. Under the pre-strain of 7.7%, the shape recovery rate can reach 86%, as shown in Figure 14. Its compressive strength limit can reach 850MPa, and its elastic modulus is 17.2GPa. Moreover, it can exhibit very good cycle stability at 210 °C.

Example 4

(1) Cu _81.5 Al ₁₄ Ni _4.5 (wt.%) alloy ingot was prepared by arc melting;

(2) Press NaAlO ₂ powder with a purity of 99% and a particle size of 500-750 μm into a green body, with a pressing force of 5 MPa, a temperature of 30°C, and a time of 5 minutes; sintering is carried out in an air atmosphere, and the sintering temperature is 1400°C , the sintering time is 24 hours, and the _NaAlO2 bulk is obtained;

(3) Put the NaAlO ₂ block into the bottom of the tube furnace that can move up and down, then put the CuAlNi alloy ingot on the NaAlO ₂ block, keep it warm at 1200℃ for 3h under the vacuum of 6×10 ^-3 Pa, then Fill with argon gas of 1.5×10 ⁵ Pa and keep it for 3 hours, then move the tube furnace downwards out of the heating zone at a speed of 10 mm/min, and obtain a composite material of CuAlNi and NaAlO ₂ after cooling;

The composite material was cut, and it was found that the CuAlNi alloy had completely infiltrated the gap between the NaAlO ₂ particles, and the size of the NaAlO ₂ particles was basically the same as that before sintering.

(4) The obtained composite material was immersed in 10% weak H ₂ SO ₄ , ultrasonically oscillated for 18 hours at a temperature of 60°C; after dissolving and removing NaAlO ₂ particles, a porous CuAlNi alloy was obtained. The pores are all interconnected, and the pore size is 550-800 μm, and the porosity is 70%.

(5) The porous CuAlNi alloy was heated to 950°C under the protection of nitrogen, kept for 3 hours and then rapidly cooled into ice water to obtain a porous CuAlNi alloy with a high transition temperature.

It was found that only a few grain boundaries were observed in the entire sample, and the two ends of the grain boundaries must be connected with holes to form a complete bamboo-like crystal structure. The entire sample is full of martensitic strips, and its A _f temperature is measured as 245°C.

Through the compression test of the porous CuAlNi alloy at 260 °C, it is found that it can fully recover under the prestrain of less than 2%, exhibiting complete superelasticity.

Example 5

(1) Cu ₈₂ Al ₁₃ Ni ₅ (wt.%) alloy ingots were prepared by arc melting;

(2) Press NaAlO ₂ powder with a purity of 99% and a particle size of 1000-1500 μm into a green body, with a pressing force of 50 MPa, a temperature of 30 °C, and a time of 10 minutes; sintering in an air atmosphere at a temperature of 1400 °C , the sintering time is 20 hours, and the _NaAlO2 bulk is obtained;

(3) Put the NaAlO ₂ block into the bottom of the tube furnace that can move up and down, then put the CuAlNi alloy ingot on the NaAlO ₂ block, keep it warm at 1150℃ for 3h under 4×10 ^-3 Pa vacuum, then Fill with argon gas of 1.5×10 ⁵ Pa and keep it for 2 hours, then move the tube furnace down out of the heating zone at a speed of 4 mm/min, and obtain a composite material of CuAlNi and NaAlO ₂ after cooling;

The composite material was cut, and it was found that the CuAlNi alloy had completely infiltrated the gap between the NaAlO ₂ particles, and the size of the NaAlO ₂ particles was basically the same as that before sintering.

(4) The obtained composite material was immersed in 15% weak HCl, ultrasonically oscillated for 24 hours, and the temperature was 40°C; after dissolving and removing NaAlO ₂ particles, a porous CuAlNi alloy was obtained. The pores are all interconnected, and the pore size is 1000~1500μm, and the porosity is 85%.

(5) The porous CuAlNi alloy was heated to 900°C under the protection of argon, kept for 1 hour and then rapidly cooled into ice water to obtain a porous CuAlNi alloy with a high transition temperature.

Example 6

(1) Cu ₈₂ Al ₁₅ Ni ₃ (wt.%) alloy ingots were prepared by arc melting;

(2) Press NaAlO ₂ powder with a purity of 99% and a particle size of 550-750 μm into a green body, with a pressing force of 200 MPa, a temperature of 30 °C, and a time of 30 minutes; sintering in an air atmosphere at a temperature of 1400 °C , the sintering time is 12 hours, and the _NaAlO2 bulk is obtained;

(3) Put the NaAlO ₂ block into the bottom of the tube furnace that can move up and down, then put the CuAlNi alloy ingot on the NaAlO ₂ block, and keep it at 1200℃ for 1h under the vacuum of 7×10 ^-3 Pa, then Fill with argon gas of 5×10 ⁵ Pa and keep it for 2 hours, then move the tube furnace downwards out of the heating zone at a speed of 6 mm/min, and obtain a composite material of CuAlNi and NaAlO ₂ after cooling;

(4) The obtained composite material was immersed in 12% weak H ₂ SO ₄ , ultrasonically oscillated for 30 hours, and the temperature was 80°C; after dissolving and removing NaAlO ₂ particles, a porous CuAlNi alloy was obtained. The pores are all interconnected, and the pore size is 600~800μm, and the porosity is 65%.

(5) The porous CuAlNi alloy was heated to 950°C under the protection of nitrogen, kept for 0.5h and then rapidly cooled into ice water to obtain a porous CuAlNi alloy with a high transition temperature.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the embodiment, and any other changes, modifications, substitutions and combinations made without departing from the spirit and principle of the present invention , simplification, all should be equivalent replacement methods, and are all included in the protection scope of the present invention.

Claims (10)

1. a preparation method of superelastic porous CuAlNi high temperature shape memory alloy, is characterized in that, comprises the following steps: (1) CuAlNi alloy ingot is prepared by arc melting or induction melting; the mass ratio of each element in the CuAlNi alloy ingot is Cu:Al:Ni=(100-x-y):x:y, where x is 13~15 , y is 3~5; (2) Press the pore-forming agent NaAlO ₂ powder into a green body, and sinter it in an air atmosphere to obtain a NaAlO ₂ block; (3) Put the _NaAlO2 block obtained in step (2) into the bottom of the tube furnace that can move up and down, and then put the CuAlNi alloy ingot obtained in step (1) on the _NaAlO2 block, in a vacuum atmosphere, the temperature is 1150 ° C Insulate at ~1250°C for 0.5h to 5h; then fill the protective gas with a pressure of 1.2×10 ⁵ Pa~2×10 ⁵ Pa and keep it for 1h to 5h, then move the tube furnace downward out of the heating zone, and obtain CuAlNi after cooling and NaAlO ₂ composite materials; (4) immerse the composite material of CuAlNi and NaAlO ₂ obtained in step (3) into a weak acid and oscillate ultrasonically to dissolve and remove NaAlO ₂ to obtain a porous CuAlNi alloy; (5) Putting the porous CuAlNi alloy obtained in step (4) into a vacuum furnace, performing heat treatment under a protective atmosphere, and then quenching into ice water to obtain a superelastic porous CuAlNi high temperature memory alloy. 2. The method for preparing superelastic porous CuAlNi high-temperature shape memory alloy according to claim 1, characterized in that the particle size of the NaAlO ₂ powder in step (2) is 50-1500 μm. 3. The method for preparing superelastic porous CuAlNi high-temperature shape memory alloy according to claim 1, characterized in that the sintering in step (2) is carried out under the following specific conditions: the temperature is 1350°C~1500°C, and the time is 10h~24h . 4. The method for preparing superelastic porous CuAlNi high-temperature shape memory alloy according to claim 1, characterized in that the pressing in step (2) is carried out under the following specific conditions: the pressure is 5-600 MPa, the temperature is 30-100°C, The time is 5 minutes to 1 hour. 5. The preparation method of superelastic porous CuAlNi high temperature shape memory alloy according to claim 1, characterized in that the vacuum atmosphere in step (3) has a vacuum degree of 1×10 ^-2 Pa~1×10 ^-3 Pa . 6 . The method for preparing superelastic porous CuAlNi high temperature shape memory alloy according to claim 1 , wherein the protective gas is argon or nitrogen. 7. The method for preparing superelastic porous CuAlNi high-temperature shape memory alloy according to claim 1, characterized in that, in step (3), the tube furnace is moved downwards out of the heating zone, specifically: Move the tube furnace down out of the heating zone at a rate of 0.5mm/min~20mm/min. 8. The preparation method of superelastic porous CuAlNi high temperature shape memory alloy according to claim 1, characterized in that, in step (4), the composite material of CuAlNi and _NaAlO2 obtained in step (3) is put into weak acid for ultrasonic oscillation ,Specifically: Put the composite material of CuAlNi and NaAlO ₂ obtained in step (3) into HCl or H ₂ SO ₄ with a solubility of 5%~15% for ultrasonic oscillation, the time of ultrasonic oscillation is 15h~30h, and the temperature is 30°C~80°C . 9. The preparation method of superelastic porous CuAlNi high temperature shape memory alloy according to claim 1, characterized in that the heat treatment in step (5) is specifically: the heat treatment temperature is 850°C~950°C, and the heat treatment time is 0.5h ~5h. 10. The elastic porous CuAlNi high-temperature shape memory alloy obtained by any one of claims 1 to 9 is used to prepare energy absorbing and driving devices for automobiles and aerospace, or as electrode materials for batteries.

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