CN116478540A - Composite material with both flexibility and magnetostrictive properties and its preparation method and application - Google Patents

Abstract

The invention provides a preparation method and application of a composite material with flexibility and magnetostriction performance, and belongs to the field of magnetostriction materials. The material is formed by compounding a magnetic material and a flexible organic material. The material has good flexibility and shape memory effect. Shows magnetostriction effect under the action of external magnetic field and responds to external magnetic field rapidly. Under the action of 2T magnetic field, the magnetostriction amplitude near room temperature can reach 400ppm. Along with the change of the content and the components of the magnetic particles, the magnetostriction performance of the material can be adjusted in a wide temperature range near room temperature. The preparation method of the magnetic drive flexible composite material is simple, and the problem of poor mechanical property of the magnetostrictive material is effectively solved.

Description

Composite material with both flexibility and magnetostrictive properties and its preparation method and application

technical field

The invention relates to a magnetic functional material, in particular to a composite material with both flexibility and magnetostrictive performance, a preparation method and application thereof.

Background technique

Under the action of an external magnetic field, the magnetostrictive material will shorten or elongate in a certain direction, thereby generating displacement and doing work. Under the action of an alternating magnetic field, it will repeatedly elongate and shorten, thereby generating vibration or sound waves. This material can convert electromagnetic energy (or electromagnetic information) into mechanical energy or acoustic energy (or mechanical displacement information or acoustic information). On the contrary, magnetostrictive materials can also convert mechanical energy (or mechanical displacement and information) into electromagnetic energy (or electromagnetic information), which is an important functional material for energy and information conversion. Magnetostrictive materials have broad application prospects in high-tech fields such as sonar underwater acoustic transducer technology, electroacoustic transducer technology, ocean detection and development technology, micro-displacement drive, vibration reduction and anti-vibration, noise reduction and anti-noise system, intelligent wings, robots, automation technology, fuel injection technology, valves, pumps, and wave oil recovery.

The main mechanism of the magnetostrictive phenomenon is the twin boundary motion in the martensitic phase, and to take full advantage of the above properties, a single crystal is usually required. The magnetostrictive properties of polycrystalline materials are greatly reduced. However, the growth of single crystals is rather tedious, and high-quality crystals are only limitedly available at rather high prices. In addition, the materials with large magnetostrictive coefficients found so far all show the characteristics of poor mechanical properties and easy fracture, which greatly limits the application of magnetostrictive materials.

In recent years, with the development of artificial intelligence technology, soft robots have received extensive attention in biomedical fields such as bionics, drug delivery, and remote control. Mechanical flexibility is the main factor that distinguishes it from traditional rigid material robots. These robots are able to respond to external stimuli such as heat, light, solvents, or electric or magnetic fields. Among various types of stimuli-responsive materials, the development of magnetically actuated soft robots has unique advantages and potential for many important applications. Magnetically driven soft robots can be remotely manipulated through magnetic fields because natural tissues and organs are transparent to static and low-frequency magnetic fields; at the same time, magnetic fields are relatively easy to control because their amplitude, phase, and frequency can be precisely and rapidly modulated. However, the field of magnetically actuated soft robots is still in its infancy, and further development is required in terms of material selection, design principles, fabrication methods, control mechanisms, and sensing methods. Among them, finding a suitable magnetically actuated flexible material is an important problem in its application. Magnetostrictive materials, which generate large strains driven by a magnetic field, are a strong candidate for soft robotic applications. However, the poor mechanical properties and easy fracture of magnetostrictive materials make it difficult to apply in soft robots.

In order to improve the mechanical properties of magnetostrictive materials, researchers compound magnetic materials with organic compounds such as epoxy resin. Composites can be tailored to specific applications through appropriate combinations of alloys and polymers, and can be prepared in various forms, including embedded particles, ribbons, or flakes. Applications of these materials in vibration damping, actuation and sensing are particularly interesting. The choice of polymer is critical to the functionality of the alloy-polymer hybrid. However, at present, in order to obtain large magnetostrictive properties, the polymers used by researchers are all high-strength polymers such as epoxy resins with strong stiffness. In order to apply magnetostrictive materials to soft robots, the flexibility of the material is more important than the magnetically actuated strain. Therefore, there is a need to develop composite materials with both flexibility and magnetostrictive properties that can satisfy practical soft robot applications.

Contents of the invention

The object of the present invention is to provide a material with both flexibility and magnetostrictive performance, its preparation method and application.

A composite material having both flexibility and magnetostrictive properties, characterized in that the composite material is composed of a magnetic material and a flexible organic material; the flexible organic material has good flexibility and can be bent arbitrarily without being brittle; the magnetic material has magnetostrictive properties and can be powder, thin strip or block.

Further, the flexible organic material is composed of one or more flexible materials selected from polyvinyl alcohol (PVA), polyester (PET), polyimide (PI), polyethylene naphthalate (PEN), hydrogel and polydimethylsiloxane (PDMS).

Further, the magnetic material is composed of one or more magnetic materials selected from Ni-based alloys, iron-based alloys, ferrite, (Tb, Dy)Fe ₂ compound-based alloys, and Ni ₂ MnGa-based alloys.

A method for preparing a composite material having both flexibility and magnetostrictive properties as described above, wherein the composite material is a Ni ₂ MnGa/PDMS composite material, and the preparation steps are as follows:

(1) carry out batching according to the chemical formula of Ni ₂ MnGa;

(2) putting the raw material configured in step (1) into an electric arc furnace for smelting to obtain an alloy ingot;

(3) annealing the alloy ingot obtained in step (2) at 600-1000° C., and then cooling to room temperature to obtain the magnetic material;

(4) mechanically crushing or ball milling the magnetic material obtained in step (3) into a powder with a suitable particle size;

(5) Add the magnetic particles obtained in step (4) into the flexible organic material solvent, and stir evenly;

(6) the mixture obtained in step (5) is put into orientation in a magnetic field;

(7) curing the mixture obtained in step (6) to obtain the composite material having both flexibility and magnetostrictive properties.

Further, the raw materials for synthesizing the Ni-Mn-Ga magnetic shape memory alloy are Ni, Mn and Ga respectively, the purity of which is not lower than 99.9%, and the purity of cobalt, silicon and carbon is not lower than 99.99%. The operation method for smelting in the step (2) is as follows: vacuumize the electric arc furnace to ≤3×10 ^-3 Pa, use argon with a purity greater than 99 wt%, and smelt at 1000-2000°C for 3-5 times under the protection of 1 atmosphere of argon.

Further, the annealing operation in the step (3) is: annealing at 600-1000°C and a vacuum degree of less than 3×10 ^-3 Pa for 3-15 days, and then cooling in a furnace or quenching in ice water to room temperature.

Further, the operation in the step (4) is: put the magnetic powder, alcohol lamp solvent and agate balls into a ball mill jar and mill for 0.5-240 hours to obtain magnetic particles with a suitable particle size.

Further, the operation in the step (6) is: put the mixture into a uniform magnetic field.

Further, the operation in the step (7) is: putting the mixture into an environment for solidifying the organic material, and the environment includes high temperature and light.

An application of a composite material having both flexibility and magnetostrictive properties prepared according to the method described above, the composite material having both flexibility and magnetostrictive properties is used to prepare a magnetically driven flexible robot. The magnetic material provided by the invention has magnetostrictive properties;

The magnetic material exhibits a magnetostrictive effect under the action of a magnetic field. The magnetostrictive effect refers to the variation of strain with magnetic induction intensity under a magnetic field.

Taking the Ni-Mn-Ga/PDMS composite material as an example, the present invention provides a method for preparing a material having both flexibility and magnetostrictive properties, which specifically includes the following steps:

The raw materials for synthesizing the Ni-Mn-Ga magnetic shape memory alloy are respectively Ni, Mn and Ga, the purity of which is not less than 99.9%, and the cobalt, silicon and carbon are not less than 99.99%.

The Ni-Mn-Ga alloy was prepared by smelting in a medium-frequency vacuum induction melting furnace, and cast into an ingot by water-cooled copper mold. The ingot was sealed in a quartz tube, annealed at 1073K for 5 days, and quenched with ice water.

The annealed alloy is ground into spherical particles with diameters of 40-50 μm, 100-150 μm and 400-450 μm respectively by using a ball mill.

(1) Use a 100-200 mesh sieve to take a particle sample with a particle size of 75-150 μm.

(2) Use a dropper to absorb 1g of polydimethylsiloxane and 0.1g of curing agent, mix and stir evenly, then add 1.5g of the sample in step (1), and stir evenly again.

(3) Put the uniformly stirred sample in step (2) into a vacuum drying oven, and dry it in an environment of 80.5° C. for 6-7 minutes to perform semi-curing pretreatment.

(4) Put the pretreated sample into a magnetic field for orientation.

(5) Put the oriented sample in step (4) into a vacuum drying oven, and dry it in an environment of 80.5°C for 20min-30min for complete curing.

The present invention combines Ni-Mn-Ga-based shape memory particles with organic flexible polymer materials in a mechanical mixing manner, uses an external magnetic field during the preparation process to orient the alloy particles, and finally obtains a magnetically driven flexible shape memory composite material.

In another aspect, the present invention also provides the application of the material with both flexibility and magnetostrictive properties prepared by the method of the present invention.

Compared with existing magnetostrictive materials and technologies, the flexible magnetostrictive material of the present invention has but not limited to the following beneficial effects:

1. The preparation method of the flexible magnetostrictive material of the present invention is simple, has no special requirements for equipment, and is easy to reach the level of industrial production. It has important practical value for the development of new flexible magnetic phase change memory composite materials.

2. The flexible magnetostrictive material of the present invention effectively solves the problem of poor mechanical properties of magnetostrictive alloys, and provides a good idea for the toughening process of magnetostrictive alloys.

3. The flexible magnetostrictive material in the present invention has obvious and controllable anisotropy, and has broad application prospects in flexible vibration damping, driving and sensing devices.

4. The flexible magnetostrictive material of the present invention has low material requirements, which reduces the dependence of the magnetostrictive material on materials.

5. The flexible magnetostrictive material of the present invention can be a polycrystalline material, which reduces the preparation cost of the material.

Description of drawings

Hereinafter, taking the Ni-Mn-Ga/PDMS composite material as an example, the embodiments of the present invention will be described in detail in conjunction with the accompanying drawings, wherein:

Fig. 1 is an X-ray diffraction pattern collected under a magnetic field of 0.01T at a characteristic temperature of a Ni-Mn-Ga alloy in a phase transformation temperature region.

Fig. 2 is the heat flow curve of the Ni-Mn-Ga alloy during the heating and cooling process.

Fig. 3 is the thermomagnetic curve of the Ni-Mn-Ga/PDMS composite material during the heating and cooling process.

Fig. 4 is the evolution curve of the Ni-Mn-Ga alloy bulk along the [010] magnetic driving strain with the magnetic field intensity.

Fig. 5 is the evolution curve of the magnetically driven strain of the Ni-Mn-Ga alloy bulk along the [001] direction with the magnetic field intensity.

Fig. 6 is the evolution curve of the magnetically driven strain of the Ni-Mn-Ga alloy bulk along the [010] direction at 280K with the magnetic field intensity.

Fig. 7 is the evolution curve of the magnetically driven strain of the Ni-Mn-Ga alloy bulk along the [010] direction at 290K with the magnetic field intensity.

Fig. 8 is the evolution curve of the magnetically driven strain of the Ni-Mn-Ga alloy bulk along the [010] direction at 300K with the magnetic field intensity.

Fig. 9 is the evolution curve of the magnetically driven strain of the Ni-Mn-Ga alloy bulk along the [010] direction at 305K with the magnetic field intensity.

Fig. 10 is the evolution curve of the magnetically driven strain of the Ni-Mn-Ga alloy bulk along the [010] direction at 310K with the magnetic field intensity.

Fig. 11 is the evolution curve of the magnetically driven strain of the Ni-Mn-Ga alloy bulk along the [010] direction at 320K with the magnetic field intensity.

Figure 12 is the evolution curve of the magnetically driven strain of the Ni-Mn-Ga/PDMS composite along the [001] direction with the magnetic field at 280K. The inset shows a schematic diagram of the bending of the composite under stress.

Figure 13 is the evolution curve of the magnetically driven strain of the Ni-Mn-Ga/PDMS composite along the [001] direction with the magnetic field at 290K.

Figure 14 is the evolution curve of the magnetically driven strain of the Ni-Mn-Ga/PDMS composite along the [001] direction with the magnetic field at 300K.

Detailed ways

The present invention will be further illustrated by specific examples below, but it should be understood that these examples are only used for more detailed description, and should not be construed as limiting the present invention in any form.

Embodiments of the present invention take Ni-Mn-Ga/PDMS composite material as an example, wherein the chemical raw materials and equipment included include:

Elemental Ni (purity 99.9wt%), elemental Mn (purity 99.9wt%), elemental Ga (purity 99.9wt%). The intermediate frequency vacuum induction melting furnace, annealing furnace, and vibrating sample magnetometer are produced by Quantum Design (USA), the model is Versa-Lab; the differential scanning calorimeter (DSC) is produced by TA Instruments, the model is Q200.

Example 1: Ni-Mn-Ga/PDMS flexible magnetostrictive composite material

1. Preparation of Ni-Mn-Ga/PDMS composites

1) Dosing according to the chemical formula of Ni-Mn-Ga;

2) The Ni-Mn-Ga alloy is prepared by smelting in an intermediate frequency vacuum induction melting furnace, and cast into an ingot by a water-cooled copper mold.

3) Seal the ingot in a quartz tube, anneal at 1173K for 5 days, and quench in ice water.

4) Using a ball mill to grind the annealed alloys into particles respectively.

5) Manually sieve to take particle samples with a particle size of 38-75 μm and 75-150 μm.

6) After mixing and stirring the polydimethylsiloxane solution and the curing agent evenly, add the sample in step 5, and stir evenly again.

7) Put the uniformly stirred sample in step 6 into a vacuum drying oven, and dry at 80° C. for 6-7 minutes for semi-curing pretreatment.

8) Put the sample in step 7 into a magnetic field for orientation.

9) Put the sample in step 8 into a vacuum drying oven, dry at 80°C for 20min-30min and solidify.

2. Performance test:

1) Crystal structure characterization

In order to confirm the change of the Ni-Mn-Ga alloy crystal structure before and after the phase transition, the inventors chose to collect its X-ray diffraction pattern near the characteristic temperature of the phase transition, and the results are shown in FIG. 1 . It can be seen that the Ni-Mn-Ga alloy has an obvious phase transformation from austenite to martensite near room temperature.

2) Thermal effect characterization

In order to measure the phase transition temperature of the Ni-Mn-Ga alloy structure, the inventors used a differential scanning calorimeter (DSC) to measure the change of heat flow with temperature, as shown in FIG. 2 . It can be seen that the structural phase transition of Ni-Mn-Ga alloy has obvious thermal effect during the heating process, and the phase transition temperature is about 311K. It can be known from this that the Ni-Mn-Ga alloy prepared by the present inventors is in the martensitic phase at room temperature.

3) Characterization of magnetic properties

The inventor measured the thermomagnetic curve (MT curve) of the Ni-Mn-Ga/PDMS composite material sample prepared in the embodiment of the present invention under a magnetic field of 0.01T by using a vibrating sample magnetometer, as shown in FIG. 3 . From the MT curve, it can be determined that the martensitic transformation temperature (T _stru ) of the Ni-Mn-Ga alloy sample is around room temperature, and it shows thermal hysteresis behavior, indicating the first-order phase transformation characteristics, which proves the coupling characteristics of its structural phase transition and magnetic phase transition.

4) Characterization of magnetically driven strain evolution with magnetic field

In order to explore the working performance of the samples, the inventors used strain gauges to measure the curves of the magnetically driven strain of the Ni-Mn-Ga alloy block along the [001] and [010] directions as a function of the magnetic field intensity. As shown in Figures 4-9, it can be confirmed that in the wide temperature range of 280K-320K, the Ni-Mn-Ga alloy has a certain magnetic driving strain. At around room temperature 290K, the magnetically actuated strain reaches the maximum. Comparing the magnetically driven strain of Ni-Mn-Ga alloy in two different directions, it can be clearly seen that the magnetically driven strain property of Ni-Mn-Ga alloy material has significant anisotropy, and the magnetically driven strain of Ni-Mn-Ga alloy in the [001] direction is much larger than that in the [010] direction.

Similarly, the inventors also studied the variation curves of the magnetic driving strain along the [001] and [010] directions of the Ni-Mn-Ga/PDMS composite material sample prepared in the embodiment of the present invention with the magnetic field intensity. As shown in Figures 10-12, the strain of the Ni-Mn-Ga/PDMS composite along the [001] direction at 290K reached 290 ppm in the first cycle, thus proving that the Ni-Mn-Ga/PDMS composite we prepared has excellent magnetostrictive properties.

By repeatedly bending the Ni-Mn-Ga/PDMS composite material tens of thousands of times, the Ni-Mn-Ga/PDMS composite material remains in its original state, and the magnetostrictive performance is only slightly decreased, thus proving its excellent mechanical properties.

Embodiment 2: (Tb,Dy)Fe ₂ /PVA flexible magnetostrictive composite material;

1. Preparation of (Tb,Dy)Fe ₂ /PVA composites

1) Dosing according to the chemical formula of (Tb,Dy)Fe ₂ ;

2) The (Tb,Dy)Fe ₂ alloy is prepared by smelting in an intermediate frequency vacuum induction melting furnace, and cast into an ingot by water-cooled copper mold.

3) Seal the ingot in a quartz tube, anneal at 1173K for 5 days, and quench in ice water.

4) Using a ball mill to grind the annealed alloys into particles respectively.

5) Manually sieve to take particle samples with a particle size of 38-75 μm and 75-150 μm.

6) After mixing and stirring the polydimethylsiloxane solution and the curing agent evenly, add the sample in step 5, and stir evenly again.

7) Put the uniformly stirred sample in step 6 into a vacuum drying oven, and dry at 80° C. for 6-7 minutes for semi-curing pretreatment.

8) Put the sample in step 7 into a magnetic field for orientation.

9) Put the sample in step 8 into a vacuum drying oven, dry at 80°C for 20min-30min and solidify.

2. Performance test:

1) Crystal structure characterization

In order to confirm the change of the crystal structure of (Tb,Dy)Fe ₂ alloy before and after the phase transition, the inventors chose to collect its X-ray diffraction pattern near the characteristic temperature of the phase transition.

2) Characterization of magnetic properties

The present inventor measured the thermomagnetic curve (MT curve) of the (Tb,Dy)Fe ₂ /PVA composite material sample prepared in the embodiment of the present invention under a magnetic field of 0.01T by using a vibrating sample magnetometer.

3) Characterization of magnetically driven strain evolution with magnetic field

In order to explore the working performance of the samples, the inventors used strain gauges to measure the magnetically driven strain curves of the (Tb,Dy)Fe ₂ alloy block along the [001] and [010] directions as a function of the magnetic field intensity

Similarly, the inventors also studied the variation curves of the magnetically driven strain along the [001] and [010] directions of the (Tb,Dy)Fe ₂ /PVA composite material sample prepared in the embodiment of the present invention as a function of the magnetic field intensity. The strain of (Tb, Dy) Fe ₂ /PVA composites can reach 200ppm in the first cycle near room temperature, which proves that the (Tb, Dy) Fe ₂ /PVA composites we prepared have excellent magnetostrictive properties.

By repeatedly bending the (Tb,Dy)Fe ₂ /PVA composite material tens of thousands of times, the (Tb,Dy)Fe ₂ /PVA composite material remains in its original shape with only a small drop in magnetostrictive properties, which proves its excellent mechanical properties.

Embodiment 3: Ni-Co/PET flexible magnetostrictive composite material.

1. Preparation of Ni-Co/PET composite materials

1) Dosing according to the chemical formula of Ni-Co;

2) The Ni-Co alloy is prepared by smelting in an intermediate frequency vacuum induction melting furnace, and cast into an ingot by a water-cooled copper mold.

3) Seal the ingot in a quartz tube, anneal at 1173K for 5 days, and quench in ice water.

4) Using a ball mill to grind the annealed alloys into particles respectively.

5) Manually sieve to take particle samples with a particle size of 38-75 μm and 75-150 μm.

6) After mixing and stirring the polydimethylsiloxane solution and the curing agent evenly, add the sample in step 5, and stir evenly again.

7) Put the uniformly stirred sample in step 6 into a vacuum drying oven, and dry at 80° C. for 6-7 minutes for semi-curing pretreatment.

8) Put the sample in step 7 into a magnetic field for orientation.

9) Put the sample in step 8 into a vacuum drying oven, dry at 80°C for 20min-30min and solidify.

2. Performance test:

1) Crystal structure characterization

In order to confirm the crystal structure of the Ni-Co alloy before and after the phase transition, the inventors chose to collect its X-ray diffraction pattern near the characteristic temperature of the phase transition.

2) Characterization of magnetic properties

The present inventor measured the thermomagnetic curve (M-T curve) of the Ni-Co/PET composite material sample prepared in the embodiment of the present invention under a magnetic field of 0.01T by using a vibrating sample magnetometer.

4) Characterization of magnetically driven strain evolution with magnetic field

In order to explore the working performance of the sample, the inventors used strain gauges to measure the variation curves of the magnetically driven strain of the Ni-Co alloy block along the two directions [001] and [010] with the intensity of the magnetic field.

Similarly, the inventors also studied the variation curves of the magnetic driving strain along the two directions [001] and [010] with the magnetic field intensity of the Ni-Co/PET composite material sample prepared in the embodiment of the present invention. The strain of the Ni-Co/PET composite along the [001] direction near room temperature reaches 90 ppm in the first cycle, thus demonstrating the excellent magnetostrictive properties of our prepared Ni-Co/PET composite.

By repeatedly bending the Ni-Co/PET composite material tens of thousands of times, the Ni-Co/PET composite material remains in its original shape with only a small decrease in magnetostrictive properties, thus proving its excellent mechanical properties.

While the invention has been described to a certain extent, it will be obvious that various changes may be made in various conditions without departing from the spirit and scope of the invention. It is to be understood that the invention is not limited to the described embodiments, but rather falls within the scope of the claims, which include equivalents to each of the elements described.

Claims (10)

1. A composite material having flexibility and magnetostrictive properties concurrently, is characterized in that, said composite material is made of magnetic material and flexible organic material; Described flexible organic material has good flexibility, can be arbitrarily bent and not brittle; Described magnetic material has magnetostrictive property, can be powder, thin band and block. 2. the composite material with flexibility and magnetostrictive performance according to claim 1, is characterized in that, described flexible organic material is made of one or more flexible materials in polyvinyl alcohol (PVA), polyester (PET), polyimide (PI), polyethylene naphthalene glycol ester (PEN), hydrogel and polydimethylsiloxane (PDMS). 3. the composite material having flexibility and magnetostrictive performance concurrently according to claim 1, is characterized in that, described magnetic material is made of one or more magnetic materials in Ni-based alloy, iron-based alloy, ferrite, (Tb, Dy) _Fe2 compound is the alloy of matrix and _Ni2MnGa -based alloy. 4. a kind of preparation method of the composite material that has flexibility and magnetostrictive performance concurrently as claimed in claim 1, it is characterized in that, described composite material is Ni ₂ MnGa/PDMS composite material, preparation steps are as follows: (1) Dosing according to the chemical formula of Ni ₂ MnGa; the raw materials are Ni, Mn and Ga respectively, with a purity not lower than 99.9%, cobalt, silicon and carbon not lower than 99.99%. (2) putting the raw material configured in step (1) into an electric arc furnace for smelting to obtain an alloy ingot; (3) annealing the alloy ingot obtained in step (2) at 600-1000° C., and then cooling to room temperature to obtain the magnetic material; (4) mechanically crushing or ball milling the magnetic material obtained in step (3) into a powder with a suitable particle size; (5) Add the magnetic particles obtained in step (4) into the flexible organic material solvent, and stir evenly; (6) the mixture obtained in step (5) is put into orientation in a magnetic field; (7) curing the mixture obtained in step (6) to obtain the composite material having both flexibility and magnetostrictive properties. 5. The method for preparing a composite material having both flexibility and magnetostrictive properties according to claim 4, characterized in that the purity of the raw material is ≥99.9wt%; the operation method of smelting in the step (2) is: vacuumize the electric arc furnace to ≤3× ^10-3Pa , use argon with a purity greater than 99wt%, and melt 3-5 times at 1000-2000°C under the protection of 1 atmosphere of argon. 6. The method for preparing a composite material having both flexibility and magnetostrictive properties according to claim 4, characterized in that the annealing operation in the step (3) is: annealing at 600-1000° C. and a vacuum degree of less than 3×10 ^-3 Pa for 3-15 days, and then cooling in a furnace or quenching in ice water to room temperature. 7. the preparation method of the composite material having flexibility and magnetostrictive performance concurrently according to claim 4, it is characterized in that the operation in the described step (4) is: magnetic powder and alcohol lamp solvent and agate ball are put into ball mill jar and ball milled for 0.5-240 hour, obtain the magnetic particle with suitable particle diameter. 8. The method for preparing a composite material having both flexibility and magnetostrictive properties according to claim 4, characterized in that the operation in the step (6) is: putting the mixture into a uniform magnetic field. 9. The preparation method of a composite material having both flexibility and magnetostrictive properties according to claim 4, characterized in that the operation in the step (7) is: putting the mixture into an environment where the organic material is solidified, and the environment includes high temperature and light. 10. An application of a composite material having both flexibility and magnetostrictive properties prepared by the method according to claim 4, characterized in that the composite material having both flexibility and magnetostrictive properties is used to prepare a magnetically driven soft robot.